[gentoo-commits] proj/linux-patches:3.16 commit in: /

[Mike Pagano]

commit:     1b28da13cd7150f66fae58043d3de661105a513a
Author:     Mike Pagano <mpagano <AT> gentoo <DOT> org>
AuthorDate: Sat Sep 27 13:37:37 2014 +0000
Commit:     Mike Pagano <mpagano <AT> gentoo <DOT> org>
CommitDate: Sat Sep 27 13:37:37 2014 +0000
URL:        http://sources.gentoo.org/gitweb/?p=proj/linux-patches.git;a=commit;h=1b28da13

Move mpctp patch to experimental

---
 0000_README                                 |     9 +-
 5010_multipath-tcp-v3.16-872d7f6c6f4e.patch | 19230 ++++++++++++++++++++++++++
 2 files changed, 19235 insertions(+), 4 deletions(-)

diff --git a/0000_README b/0000_README
index d92e6b7..3cc9441 100644
--- a/0000_README
+++ b/0000_README
@@ -58,10 +58,6 @@ Patch:  2400_kcopy-patch-for-infiniband-driver.patch
 From:   Alexey Shvetsov <alexxy@g.o>
 Desc:   Zero copy for infiniband psm userspace driver
 
-Patch:  2500_multipath-tcp-v3.16-872d7f6c6f4e.patch
-From:   http://multipath-tcp.org/
-Desc:   Patch for simultaneous use of several IP-addresses/interfaces in TCP for better resource utilization, better throughput and smoother reaction to failures.
-
 Patch:  2700_ThinkPad-30-brightness-control-fix.patch
 From:   Seth Forshee <seth.forshee@×××××××××.com>
 Desc:   ACPI: Disable Windows 8 compatibility for some Lenovo ThinkPads
@@ -101,3 +97,8 @@ Desc:   BFQ v7r5 patch 2 for 3.16: BFQ Scheduler
 Patch:  5003_BFQ-3-block-add-Early-Queue-Merge-EQM-v7r5-for-3.16.0.patch
 From:   http://algo.ing.unimo.it/people/paolo/disk_sched/
 Desc:   BFQ v7r5 patch 3 for 3.16: Early Queue Merge (EQM)
+
+Patch:  5010_multipath-tcp-v3.16-872d7f6c6f4e.patch
+From:   http://multipath-tcp.org/
+Desc:   Patch for simultaneous use of several IP-addresses/interfaces in TCP for better resource utilization, better throughput and smoother reaction to failures.
+

diff --git a/5010_multipath-tcp-v3.16-872d7f6c6f4e.patch b/5010_multipath-tcp-v3.16-872d7f6c6f4e.patch
new file mode 100644
index 0000000..3000da3
--- /dev/null
+++ b/5010_multipath-tcp-v3.16-872d7f6c6f4e.patch
@@ -0,0 +1,19230 @@
+diff --git a/drivers/infiniband/hw/cxgb4/cm.c b/drivers/infiniband/hw/cxgb4/cm.c
+index 768a0fb67dd6..5a46d91a8df9 100644
+--- a/drivers/infiniband/hw/cxgb4/cm.c
++++ b/drivers/infiniband/hw/cxgb4/cm.c
+@@ -3432,7 +3432,7 @@ static void build_cpl_pass_accept_req(struct sk_buff *skb, int stid , u8 tos)
+ 	 */
+ 	memset(&tmp_opt, 0, sizeof(tmp_opt));
+ 	tcp_clear_options(&tmp_opt);
+-	tcp_parse_options(skb, &tmp_opt, 0, NULL);
++	tcp_parse_options(skb, &tmp_opt, NULL, 0, NULL);
+ 
+ 	req = (struct cpl_pass_accept_req *)__skb_push(skb, sizeof(*req));
+ 	memset(req, 0, sizeof(*req));
+diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
+index 2faef339d8f2..d86c853ffaad 100644
+--- a/include/linux/ipv6.h
++++ b/include/linux/ipv6.h
+@@ -256,16 +256,6 @@ static inline struct ipv6_pinfo * inet6_sk(const struct sock *__sk)
+ 	return inet_sk(__sk)->pinet6;
+ }
+ 
+-static inline struct request_sock *inet6_reqsk_alloc(struct request_sock_ops *ops)
+-{
+-	struct request_sock *req = reqsk_alloc(ops);
+-
+-	if (req)
+-		inet_rsk(req)->pktopts = NULL;
+-
+-	return req;
+-}
+-
+ static inline struct raw6_sock *raw6_sk(const struct sock *sk)
+ {
+ 	return (struct raw6_sock *)sk;
+@@ -309,12 +299,6 @@ static inline struct ipv6_pinfo * inet6_sk(const struct sock *__sk)
+ 	return NULL;
+ }
+ 
+-static inline struct inet6_request_sock *
+-			inet6_rsk(const struct request_sock *rsk)
+-{
+-	return NULL;
+-}
+-
+ static inline struct raw6_sock *raw6_sk(const struct sock *sk)
+ {
+ 	return NULL;
+diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
+index ec89301ada41..99ea4b0e3693 100644
+--- a/include/linux/skbuff.h
++++ b/include/linux/skbuff.h
+@@ -2784,8 +2784,10 @@ static inline bool __skb_checksum_validate_needed(struct sk_buff *skb,
+ 						  bool zero_okay,
+ 						  __sum16 check)
+ {
+-	if (skb_csum_unnecessary(skb) || (zero_okay && !check)) {
+-		skb->csum_valid = 1;
++	if (skb_csum_unnecessary(skb)) {
++		return false;
++	} else if (zero_okay && !check) {
++		skb->ip_summed = CHECKSUM_UNNECESSARY;
+ 		return false;
+ 	}
+ 
+diff --git a/include/linux/tcp.h b/include/linux/tcp.h
+index a0513210798f..7bc2e078d6ca 100644
+--- a/include/linux/tcp.h
++++ b/include/linux/tcp.h
+@@ -53,7 +53,7 @@ static inline unsigned int tcp_optlen(const struct sk_buff *skb)
+ /* TCP Fast Open */
+ #define TCP_FASTOPEN_COOKIE_MIN	4	/* Min Fast Open Cookie size in bytes */
+ #define TCP_FASTOPEN_COOKIE_MAX	16	/* Max Fast Open Cookie size in bytes */
+-#define TCP_FASTOPEN_COOKIE_SIZE 8	/* the size employed by this impl. */
++#define TCP_FASTOPEN_COOKIE_SIZE 4	/* the size employed by this impl. */
+ 
+ /* TCP Fast Open Cookie as stored in memory */
+ struct tcp_fastopen_cookie {
+@@ -72,6 +72,51 @@ struct tcp_sack_block {
+ 	u32	end_seq;
+ };
+ 
++struct tcp_out_options {
++	u16	options;	/* bit field of OPTION_* */
++	u8	ws;		/* window scale, 0 to disable */
++	u8	num_sack_blocks;/* number of SACK blocks to include */
++	u8	hash_size;	/* bytes in hash_location */
++	u16	mss;		/* 0 to disable */
++	__u8	*hash_location;	/* temporary pointer, overloaded */
++	__u32	tsval, tsecr;	/* need to include OPTION_TS */
++	struct tcp_fastopen_cookie *fastopen_cookie;	/* Fast open cookie */
++#ifdef CONFIG_MPTCP
++	u16	mptcp_options;	/* bit field of MPTCP related OPTION_* */
++	u8	dss_csum:1,
++		add_addr_v4:1,
++		add_addr_v6:1;	/* dss-checksum required? */
++
++	union {
++		struct {
++			__u64	sender_key;	/* sender's key for mptcp */
++			__u64	receiver_key;	/* receiver's key for mptcp */
++		} mp_capable;
++
++		struct {
++			__u64	sender_truncated_mac;
++			__u32	sender_nonce;
++					/* random number of the sender */
++			__u32	token;	/* token for mptcp */
++			u8	low_prio:1;
++		} mp_join_syns;
++	};
++
++	struct {
++		struct in_addr addr;
++		u8 addr_id;
++	} add_addr4;
++
++	struct {
++		struct in6_addr addr;
++		u8 addr_id;
++	} add_addr6;
++
++	u16	remove_addrs;	/* list of address id */
++	u8	addr_id;	/* address id (mp_join or add_address) */
++#endif /* CONFIG_MPTCP */
++};
++
+ /*These are used to set the sack_ok field in struct tcp_options_received */
+ #define TCP_SACK_SEEN     (1 << 0)   /*1 = peer is SACK capable, */
+ #define TCP_FACK_ENABLED  (1 << 1)   /*1 = FACK is enabled locally*/
+@@ -95,6 +140,9 @@ struct tcp_options_received {
+ 	u16	mss_clamp;	/* Maximal mss, negotiated at connection setup */
+ };
+ 
++struct mptcp_cb;
++struct mptcp_tcp_sock;
++
+ static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
+ {
+ 	rx_opt->tstamp_ok = rx_opt->sack_ok = 0;
+@@ -111,10 +159,7 @@ struct tcp_request_sock_ops;
+ 
+ struct tcp_request_sock {
+ 	struct inet_request_sock 	req;
+-#ifdef CONFIG_TCP_MD5SIG
+-	/* Only used by TCP MD5 Signature so far. */
+ 	const struct tcp_request_sock_ops *af_specific;
+-#endif
+ 	struct sock			*listener; /* needed for TFO */
+ 	u32				rcv_isn;
+ 	u32				snt_isn;
+@@ -130,6 +175,8 @@ static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req)
+ 	return (struct tcp_request_sock *)req;
+ }
+ 
++struct tcp_md5sig_key;
++
+ struct tcp_sock {
+ 	/* inet_connection_sock has to be the first member of tcp_sock */
+ 	struct inet_connection_sock	inet_conn;
+@@ -326,6 +373,37 @@ struct tcp_sock {
+ 	 * socket. Used to retransmit SYNACKs etc.
+ 	 */
+ 	struct request_sock *fastopen_rsk;
++
++	/* MPTCP/TCP-specific callbacks */
++	const struct tcp_sock_ops	*ops;
++
++	struct mptcp_cb		*mpcb;
++	struct sock		*meta_sk;
++	/* We keep these flags even if CONFIG_MPTCP is not checked, because
++	 * it allows checking MPTCP capability just by checking the mpc flag,
++	 * rather than adding ifdefs everywhere.
++	 */
++	u16     mpc:1,          /* Other end is multipath capable */
++		inside_tk_table:1, /* Is the tcp_sock inside the token-table? */
++		send_mp_fclose:1,
++		request_mptcp:1, /* Did we send out an MP_CAPABLE?
++				  * (this speeds up mptcp_doit() in tcp_recvmsg)
++				  */
++		mptcp_enabled:1, /* Is MPTCP enabled from the application ? */
++		pf:1, /* Potentially Failed state: when this flag is set, we
++		       * stop using the subflow
++		       */
++		mp_killed:1, /* Killed with a tcp_done in mptcp? */
++		was_meta_sk:1,	/* This was a meta sk (in case of reuse) */
++		is_master_sk,
++		close_it:1,	/* Must close socket in mptcp_data_ready? */
++		closing:1;
++	struct mptcp_tcp_sock *mptcp;
++#ifdef CONFIG_MPTCP
++	struct hlist_nulls_node tk_table;
++	u32		mptcp_loc_token;
++	u64		mptcp_loc_key;
++#endif /* CONFIG_MPTCP */
+ };
+ 
+ enum tsq_flags {
+@@ -337,6 +415,8 @@ enum tsq_flags {
+ 	TCP_MTU_REDUCED_DEFERRED,  /* tcp_v{4|6}_err() could not call
+ 				    * tcp_v{4|6}_mtu_reduced()
+ 				    */
++	MPTCP_PATH_MANAGER, /* MPTCP deferred creation of new subflows */
++	MPTCP_SUB_DEFERRED, /* A subflow got deferred - process them */
+ };
+ 
+ static inline struct tcp_sock *tcp_sk(const struct sock *sk)
+@@ -355,6 +435,7 @@ struct tcp_timewait_sock {
+ #ifdef CONFIG_TCP_MD5SIG
+ 	struct tcp_md5sig_key	  *tw_md5_key;
+ #endif
++	struct mptcp_tw		  *mptcp_tw;
+ };
+ 
+ static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk)
+diff --git a/include/net/inet6_connection_sock.h b/include/net/inet6_connection_sock.h
+index 74af137304be..83f63033897a 100644
+--- a/include/net/inet6_connection_sock.h
++++ b/include/net/inet6_connection_sock.h
+@@ -27,6 +27,8 @@ int inet6_csk_bind_conflict(const struct sock *sk,
+ 
+ struct dst_entry *inet6_csk_route_req(struct sock *sk, struct flowi6 *fl6,
+ 				      const struct request_sock *req);
++u32 inet6_synq_hash(const struct in6_addr *raddr, const __be16 rport,
++		    const u32 rnd, const u32 synq_hsize);
+ 
+ struct request_sock *inet6_csk_search_req(const struct sock *sk,
+ 					  struct request_sock ***prevp,
+diff --git a/include/net/inet_common.h b/include/net/inet_common.h
+index fe7994c48b75..780f229f46a8 100644
+--- a/include/net/inet_common.h
++++ b/include/net/inet_common.h
+@@ -1,6 +1,8 @@
+ #ifndef _INET_COMMON_H
+ #define _INET_COMMON_H
+ 
++#include <net/sock.h>
++
+ extern const struct proto_ops inet_stream_ops;
+ extern const struct proto_ops inet_dgram_ops;
+ 
+@@ -13,6 +15,8 @@ struct sock;
+ struct sockaddr;
+ struct socket;
+ 
++int inet_create(struct net *net, struct socket *sock, int protocol, int kern);
++int inet6_create(struct net *net, struct socket *sock, int protocol, int kern);
+ int inet_release(struct socket *sock);
+ int inet_stream_connect(struct socket *sock, struct sockaddr *uaddr,
+ 			int addr_len, int flags);
+diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h
+index 7a4313887568..f62159e39839 100644
+--- a/include/net/inet_connection_sock.h
++++ b/include/net/inet_connection_sock.h
+@@ -30,6 +30,7 @@
+ 
+ struct inet_bind_bucket;
+ struct tcp_congestion_ops;
++struct tcp_options_received;
+ 
+ /*
+  * Pointers to address related TCP functions
+@@ -243,6 +244,9 @@ static inline void inet_csk_reset_xmit_timer(struct sock *sk, const int what,
+ 
+ struct sock *inet_csk_accept(struct sock *sk, int flags, int *err);
+ 
++u32 inet_synq_hash(const __be32 raddr, const __be16 rport, const u32 rnd,
++		   const u32 synq_hsize);
++
+ struct request_sock *inet_csk_search_req(const struct sock *sk,
+ 					 struct request_sock ***prevp,
+ 					 const __be16 rport,
+diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h
+index b1edf17bec01..6a32d8d6b85e 100644
+--- a/include/net/inet_sock.h
++++ b/include/net/inet_sock.h
+@@ -86,10 +86,14 @@ struct inet_request_sock {
+ 				wscale_ok  : 1,
+ 				ecn_ok	   : 1,
+ 				acked	   : 1,
+-				no_srccheck: 1;
++				no_srccheck: 1,
++				mptcp_rqsk : 1,
++				saw_mpc    : 1;
+ 	kmemcheck_bitfield_end(flags);
+-	struct ip_options_rcu	*opt;
+-	struct sk_buff		*pktopts;
++	union {
++		struct ip_options_rcu	*opt;
++		struct sk_buff		*pktopts;
++	};
+ 	u32                     ir_mark;
+ };
+ 
+diff --git a/include/net/mptcp.h b/include/net/mptcp.h
+new file mode 100644
+index 000000000000..712780fc39e4
+--- /dev/null
++++ b/include/net/mptcp.h
+@@ -0,0 +1,1439 @@
++/*
++ *	MPTCP implementation
++ *
++ *	Initial Design & Implementation:
++ *	Sébastien Barré <sebastien.barre@×××××××××.be>
++ *
++ *	Current Maintainer & Author:
++ *	Christoph Paasch <christoph.paasch@×××××××××.be>
++ *
++ *	Additional authors:
++ *	Jaakko Korkeaniemi <jaakko.korkeaniemi@×××××.fi>
++ *	Gregory Detal <gregory.detal@×××××××××.be>
++ *	Fabien Duchêne <fabien.duchene@×××××××××.be>
++ *	Andreas Seelinger <Andreas.Seelinger@×××××××××××.de>
++ *	Lavkesh Lahngir <lavkesh51@×××××.com>
++ *	Andreas Ripke <ripke@××××××.eu>
++ *	Vlad Dogaru <vlad.dogaru@×××××.com>
++ *	Octavian Purdila <octavian.purdila@×××××.com>
++ *	John Ronan <jronan@××××.org>
++ *	Catalin Nicutar <catalin.nicutar@×××××.com>
++ *	Brandon Heller <brandonh@××××××××.edu>
++ *
++ *
++ *	This program is free software; you can redistribute it and/or
++ *      modify it under the terms of the GNU General Public License
++ *      as published by the Free Software Foundation; either version
++ *      2 of the License, or (at your option) any later version.
++ */
++
++#ifndef _MPTCP_H
++#define _MPTCP_H
++
++#include <linux/inetdevice.h>
++#include <linux/ipv6.h>
++#include <linux/list.h>
++#include <linux/net.h>
++#include <linux/netpoll.h>
++#include <linux/skbuff.h>
++#include <linux/socket.h>
++#include <linux/tcp.h>
++#include <linux/kernel.h>
++
++#include <asm/byteorder.h>
++#include <asm/unaligned.h>
++#include <crypto/hash.h>
++#include <net/tcp.h>
++
++#if defined(__LITTLE_ENDIAN_BITFIELD)
++	#define ntohll(x)  be64_to_cpu(x)
++	#define htonll(x)  cpu_to_be64(x)
++#elif defined(__BIG_ENDIAN_BITFIELD)
++	#define ntohll(x) (x)
++	#define htonll(x) (x)
++#endif
++
++struct mptcp_loc4 {
++	u8		loc4_id;
++	u8		low_prio:1;
++	struct in_addr	addr;
++};
++
++struct mptcp_rem4 {
++	u8		rem4_id;
++	__be16		port;
++	struct in_addr	addr;
++};
++
++struct mptcp_loc6 {
++	u8		loc6_id;
++	u8		low_prio:1;
++	struct in6_addr	addr;
++};
++
++struct mptcp_rem6 {
++	u8		rem6_id;
++	__be16		port;
++	struct in6_addr	addr;
++};
++
++struct mptcp_request_sock {
++	struct tcp_request_sock		req;
++	/* hlist-nulls entry to the hash-table. Depending on whether this is a
++	 * a new MPTCP connection or an additional subflow, the request-socket
++	 * is either in the mptcp_reqsk_tk_htb or mptcp_reqsk_htb.
++	 */
++	struct hlist_nulls_node		hash_entry;
++
++	union {
++		struct {
++			/* Only on initial subflows */
++			u64		mptcp_loc_key;
++			u64		mptcp_rem_key;
++			u32		mptcp_loc_token;
++		};
++
++		struct {
++			/* Only on additional subflows */
++			struct mptcp_cb	*mptcp_mpcb;
++			u32		mptcp_rem_nonce;
++			u32		mptcp_loc_nonce;
++			u64		mptcp_hash_tmac;
++		};
++	};
++
++	u8				loc_id;
++	u8				rem_id; /* Address-id in the MP_JOIN */
++	u8				dss_csum:1,
++					is_sub:1, /* Is this a new subflow? */
++					low_prio:1, /* Interface set to low-prio? */
++					rcv_low_prio:1;
++};
++
++struct mptcp_options_received {
++	u16	saw_mpc:1,
++		dss_csum:1,
++		drop_me:1,
++
++		is_mp_join:1,
++		join_ack:1,
++
++		saw_low_prio:2, /* 0x1 - low-prio set for this subflow
++				 * 0x2 - low-prio set for another subflow
++				 */
++		low_prio:1,
++
++		saw_add_addr:2, /* Saw at least one add_addr option:
++				 * 0x1: IPv4 - 0x2: IPv6
++				 */
++		more_add_addr:1, /* Saw one more add-addr. */
++
++		saw_rem_addr:1, /* Saw at least one rem_addr option */
++		more_rem_addr:1, /* Saw one more rem-addr. */
++
++		mp_fail:1,
++		mp_fclose:1;
++	u8	rem_id;		/* Address-id in the MP_JOIN */
++	u8	prio_addr_id;	/* Address-id in the MP_PRIO */
++
++	const unsigned char *add_addr_ptr; /* Pointer to add-address option */
++	const unsigned char *rem_addr_ptr; /* Pointer to rem-address option */
++
++	u32	data_ack;
++	u32	data_seq;
++	u16	data_len;
++
++	u32	mptcp_rem_token;/* Remote token */
++
++	/* Key inside the option (from mp_capable or fast_close) */
++	u64	mptcp_key;
++
++	u32	mptcp_recv_nonce;
++	u64	mptcp_recv_tmac;
++	u8	mptcp_recv_mac[20];
++};
++
++struct mptcp_tcp_sock {
++	struct tcp_sock	*next;		/* Next subflow socket */
++	struct hlist_node cb_list;
++	struct mptcp_options_received rx_opt;
++
++	 /* Those three fields record the current mapping */
++	u64	map_data_seq;
++	u32	map_subseq;
++	u16	map_data_len;
++	u16	slave_sk:1,
++		fully_established:1,
++		establish_increased:1,
++		second_packet:1,
++		attached:1,
++		send_mp_fail:1,
++		include_mpc:1,
++		mapping_present:1,
++		map_data_fin:1,
++		low_prio:1, /* use this socket as backup */
++		rcv_low_prio:1, /* Peer sent low-prio option to us */
++		send_mp_prio:1, /* Trigger to send mp_prio on this socket */
++		pre_established:1; /* State between sending 3rd ACK and
++				    * receiving the fourth ack of new subflows.
++				    */
++
++	/* isn: needed to translate abs to relative subflow seqnums */
++	u32	snt_isn;
++	u32	rcv_isn;
++	u8	path_index;
++	u8	loc_id;
++	u8	rem_id;
++
++#define MPTCP_SCHED_SIZE 4
++	u8	mptcp_sched[MPTCP_SCHED_SIZE] __aligned(8);
++
++	struct sk_buff  *shortcut_ofoqueue; /* Shortcut to the current modified
++					     * skb in the ofo-queue.
++					     */
++
++	int	init_rcv_wnd;
++	u32	infinite_cutoff_seq;
++	struct delayed_work work;
++	u32	mptcp_loc_nonce;
++	struct tcp_sock *tp; /* Where is my daddy? */
++	u32	last_end_data_seq;
++
++	/* MP_JOIN subflow: timer for retransmitting the 3rd ack */
++	struct timer_list mptcp_ack_timer;
++
++	/* HMAC of the third ack */
++	char sender_mac[20];
++};
++
++struct mptcp_tw {
++	struct list_head list;
++	u64 loc_key;
++	u64 rcv_nxt;
++	struct mptcp_cb __rcu *mpcb;
++	u8 meta_tw:1,
++	   in_list:1;
++};
++
++#define MPTCP_PM_NAME_MAX 16
++struct mptcp_pm_ops {
++	struct list_head list;
++
++	/* Signal the creation of a new MPTCP-session. */
++	void (*new_session)(const struct sock *meta_sk);
++	void (*release_sock)(struct sock *meta_sk);
++	void (*fully_established)(struct sock *meta_sk);
++	void (*new_remote_address)(struct sock *meta_sk);
++	int  (*get_local_id)(sa_family_t family, union inet_addr *addr,
++			     struct net *net, bool *low_prio);
++	void (*addr_signal)(struct sock *sk, unsigned *size,
++			    struct tcp_out_options *opts, struct sk_buff *skb);
++	void (*add_raddr)(struct mptcp_cb *mpcb, const union inet_addr *addr,
++			  sa_family_t family, __be16 port, u8 id);
++	void (*rem_raddr)(struct mptcp_cb *mpcb, u8 rem_id);
++	void (*init_subsocket_v4)(struct sock *sk, struct in_addr addr);
++	void (*init_subsocket_v6)(struct sock *sk, struct in6_addr addr);
++
++	char		name[MPTCP_PM_NAME_MAX];
++	struct module	*owner;
++};
++
++#define MPTCP_SCHED_NAME_MAX 16
++struct mptcp_sched_ops {
++	struct list_head list;
++
++	struct sock *		(*get_subflow)(struct sock *meta_sk,
++					       struct sk_buff *skb,
++					       bool zero_wnd_test);
++	struct sk_buff *	(*next_segment)(struct sock *meta_sk,
++						int *reinject,
++						struct sock **subsk,
++						unsigned int *limit);
++	void			(*init)(struct sock *sk);
++
++	char			name[MPTCP_SCHED_NAME_MAX];
++	struct module		*owner;
++};
++
++struct mptcp_cb {
++	/* list of sockets in this multipath connection */
++	struct tcp_sock *connection_list;
++	/* list of sockets that need a call to release_cb */
++	struct hlist_head callback_list;
++
++	/* High-order bits of 64-bit sequence numbers */
++	u32 snd_high_order[2];
++	u32 rcv_high_order[2];
++
++	u16	send_infinite_mapping:1,
++		in_time_wait:1,
++		list_rcvd:1, /* XXX TO REMOVE */
++		addr_signal:1, /* Path-manager wants us to call addr_signal */
++		dss_csum:1,
++		server_side:1,
++		infinite_mapping_rcv:1,
++		infinite_mapping_snd:1,
++		dfin_combined:1,   /* Was the DFIN combined with subflow-fin? */
++		passive_close:1,
++		snd_hiseq_index:1, /* Index in snd_high_order of snd_nxt */
++		rcv_hiseq_index:1; /* Index in rcv_high_order of rcv_nxt */
++
++	/* socket count in this connection */
++	u8 cnt_subflows;
++	u8 cnt_established;
++
++	struct mptcp_sched_ops *sched_ops;
++
++	struct sk_buff_head reinject_queue;
++	/* First cache-line boundary is here minus 8 bytes. But from the
++	 * reinject-queue only the next and prev pointers are regularly
++	 * accessed. Thus, the whole data-path is on a single cache-line.
++	 */
++
++	u64	csum_cutoff_seq;
++
++	/***** Start of fields, used for connection closure */
++	spinlock_t	 tw_lock;
++	unsigned char	 mptw_state;
++	u8		 dfin_path_index;
++
++	struct list_head tw_list;
++
++	/***** Start of fields, used for subflow establishment and closure */
++	atomic_t	mpcb_refcnt;
++
++	/* Mutex needed, because otherwise mptcp_close will complain that the
++	 * socket is owned by the user.
++	 * E.g., mptcp_sub_close_wq is taking the meta-lock.
++	 */
++	struct mutex	mpcb_mutex;
++
++	/***** Start of fields, used for subflow establishment */
++	struct sock *meta_sk;
++
++	/* Master socket, also part of the connection_list, this
++	 * socket is the one that the application sees.
++	 */
++	struct sock *master_sk;
++
++	__u64	mptcp_loc_key;
++	__u64	mptcp_rem_key;
++	__u32	mptcp_loc_token;
++	__u32	mptcp_rem_token;
++
++#define MPTCP_PM_SIZE 608
++	u8 mptcp_pm[MPTCP_PM_SIZE] __aligned(8);
++	struct mptcp_pm_ops *pm_ops;
++
++	u32 path_index_bits;
++	/* Next pi to pick up in case a new path becomes available */
++	u8 next_path_index;
++
++	/* Original snd/rcvbuf of the initial subflow.
++	 * Used for the new subflows on the server-side to allow correct
++	 * autotuning
++	 */
++	int orig_sk_rcvbuf;
++	int orig_sk_sndbuf;
++	u32 orig_window_clamp;
++
++	/* Timer for retransmitting SYN/ACK+MP_JOIN */
++	struct timer_list synack_timer;
++};
++
++#define MPTCP_SUB_CAPABLE			0
++#define MPTCP_SUB_LEN_CAPABLE_SYN		12
++#define MPTCP_SUB_LEN_CAPABLE_SYN_ALIGN		12
++#define MPTCP_SUB_LEN_CAPABLE_ACK		20
++#define MPTCP_SUB_LEN_CAPABLE_ACK_ALIGN		20
++
++#define MPTCP_SUB_JOIN			1
++#define MPTCP_SUB_LEN_JOIN_SYN		12
++#define MPTCP_SUB_LEN_JOIN_SYN_ALIGN	12
++#define MPTCP_SUB_LEN_JOIN_SYNACK	16
++#define MPTCP_SUB_LEN_JOIN_SYNACK_ALIGN	16
++#define MPTCP_SUB_LEN_JOIN_ACK		24
++#define MPTCP_SUB_LEN_JOIN_ACK_ALIGN	24
++
++#define MPTCP_SUB_DSS		2
++#define MPTCP_SUB_LEN_DSS	4
++#define MPTCP_SUB_LEN_DSS_ALIGN	4
++
++/* Lengths for seq and ack are the ones without the generic MPTCP-option header,
++ * as they are part of the DSS-option.
++ * To get the total length, just add the different options together.
++ */
++#define MPTCP_SUB_LEN_SEQ	10
++#define MPTCP_SUB_LEN_SEQ_CSUM	12
++#define MPTCP_SUB_LEN_SEQ_ALIGN	12
++
++#define MPTCP_SUB_LEN_SEQ_64		14
++#define MPTCP_SUB_LEN_SEQ_CSUM_64	16
++#define MPTCP_SUB_LEN_SEQ_64_ALIGN	16
++
++#define MPTCP_SUB_LEN_ACK	4
++#define MPTCP_SUB_LEN_ACK_ALIGN	4
++
++#define MPTCP_SUB_LEN_ACK_64		8
++#define MPTCP_SUB_LEN_ACK_64_ALIGN	8
++
++/* This is the "default" option-length we will send out most often.
++ * MPTCP DSS-header
++ * 32-bit data sequence number
++ * 32-bit data ack
++ *
++ * It is necessary to calculate the effective MSS we will be using when
++ * sending data.
++ */
++#define MPTCP_SUB_LEN_DSM_ALIGN  (MPTCP_SUB_LEN_DSS_ALIGN +		\
++				  MPTCP_SUB_LEN_SEQ_ALIGN +		\
++				  MPTCP_SUB_LEN_ACK_ALIGN)
++
++#define MPTCP_SUB_ADD_ADDR		3
++#define MPTCP_SUB_LEN_ADD_ADDR4		8
++#define MPTCP_SUB_LEN_ADD_ADDR6		20
++#define MPTCP_SUB_LEN_ADD_ADDR4_ALIGN	8
++#define MPTCP_SUB_LEN_ADD_ADDR6_ALIGN	20
++
++#define MPTCP_SUB_REMOVE_ADDR	4
++#define MPTCP_SUB_LEN_REMOVE_ADDR	4
++
++#define MPTCP_SUB_PRIO		5
++#define MPTCP_SUB_LEN_PRIO	3
++#define MPTCP_SUB_LEN_PRIO_ADDR	4
++#define MPTCP_SUB_LEN_PRIO_ALIGN	4
++
++#define MPTCP_SUB_FAIL		6
++#define MPTCP_SUB_LEN_FAIL	12
++#define MPTCP_SUB_LEN_FAIL_ALIGN	12
++
++#define MPTCP_SUB_FCLOSE	7
++#define MPTCP_SUB_LEN_FCLOSE	12
++#define MPTCP_SUB_LEN_FCLOSE_ALIGN	12
++
++
++#define OPTION_MPTCP		(1 << 5)
++
++#ifdef CONFIG_MPTCP
++
++/* Used for checking if the mptcp initialization has been successful */
++extern bool mptcp_init_failed;
++
++/* MPTCP options */
++#define OPTION_TYPE_SYN		(1 << 0)
++#define OPTION_TYPE_SYNACK	(1 << 1)
++#define OPTION_TYPE_ACK		(1 << 2)
++#define OPTION_MP_CAPABLE	(1 << 3)
++#define OPTION_DATA_ACK		(1 << 4)
++#define OPTION_ADD_ADDR		(1 << 5)
++#define OPTION_MP_JOIN		(1 << 6)
++#define OPTION_MP_FAIL		(1 << 7)
++#define OPTION_MP_FCLOSE	(1 << 8)
++#define OPTION_REMOVE_ADDR	(1 << 9)
++#define OPTION_MP_PRIO		(1 << 10)
++
++/* MPTCP flags: both TX and RX */
++#define MPTCPHDR_SEQ		0x01 /* DSS.M option is present */
++#define MPTCPHDR_FIN		0x02 /* DSS.F option is present */
++#define MPTCPHDR_SEQ64_INDEX	0x04 /* index of seq in mpcb->snd_high_order */
++/* MPTCP flags: RX only */
++#define MPTCPHDR_ACK		0x08
++#define MPTCPHDR_SEQ64_SET	0x10 /* Did we received a 64-bit seq number?  */
++#define MPTCPHDR_SEQ64_OFO	0x20 /* Is it not in our circular array? */
++#define MPTCPHDR_DSS_CSUM	0x40
++#define MPTCPHDR_JOIN		0x80
++/* MPTCP flags: TX only */
++#define MPTCPHDR_INF		0x08
++
++struct mptcp_option {
++	__u8	kind;
++	__u8	len;
++#if defined(__LITTLE_ENDIAN_BITFIELD)
++	__u8	ver:4,
++		sub:4;
++#elif defined(__BIG_ENDIAN_BITFIELD)
++	__u8	sub:4,
++		ver:4;
++#else
++#error	"Adjust your <asm/byteorder.h> defines"
++#endif
++};
++
++struct mp_capable {
++	__u8	kind;
++	__u8	len;
++#if defined(__LITTLE_ENDIAN_BITFIELD)
++	__u8	ver:4,
++		sub:4;
++	__u8	h:1,
++		rsv:5,
++		b:1,
++		a:1;
++#elif defined(__BIG_ENDIAN_BITFIELD)
++	__u8	sub:4,
++		ver:4;
++	__u8	a:1,
++		b:1,
++		rsv:5,
++		h:1;
++#else
++#error	"Adjust your <asm/byteorder.h> defines"
++#endif
++	__u64	sender_key;
++	__u64	receiver_key;
++} __attribute__((__packed__));
++
++struct mp_join {
++	__u8	kind;
++	__u8	len;
++#if defined(__LITTLE_ENDIAN_BITFIELD)
++	__u8	b:1,
++		rsv:3,
++		sub:4;
++#elif defined(__BIG_ENDIAN_BITFIELD)
++	__u8	sub:4,
++		rsv:3,
++		b:1;
++#else
++#error	"Adjust your <asm/byteorder.h> defines"
++#endif
++	__u8	addr_id;
++	union {
++		struct {
++			u32	token;
++			u32	nonce;
++		} syn;
++		struct {
++			__u64	mac;
++			u32	nonce;
++		} synack;
++		struct {
++			__u8	mac[20];
++		} ack;
++	} u;
++} __attribute__((__packed__));
++
++struct mp_dss {
++	__u8	kind;
++	__u8	len;
++#if defined(__LITTLE_ENDIAN_BITFIELD)
++	__u16	rsv1:4,
++		sub:4,
++		A:1,
++		a:1,
++		M:1,
++		m:1,
++		F:1,
++		rsv2:3;
++#elif defined(__BIG_ENDIAN_BITFIELD)
++	__u16	sub:4,
++		rsv1:4,
++		rsv2:3,
++		F:1,
++		m:1,
++		M:1,
++		a:1,
++		A:1;
++#else
++#error	"Adjust your <asm/byteorder.h> defines"
++#endif
++};
++
++struct mp_add_addr {
++	__u8	kind;
++	__u8	len;
++#if defined(__LITTLE_ENDIAN_BITFIELD)
++	__u8	ipver:4,
++		sub:4;
++#elif defined(__BIG_ENDIAN_BITFIELD)
++	__u8	sub:4,
++		ipver:4;
++#else
++#error	"Adjust your <asm/byteorder.h> defines"
++#endif
++	__u8	addr_id;
++	union {
++		struct {
++			struct in_addr	addr;
++			__be16		port;
++		} v4;
++		struct {
++			struct in6_addr	addr;
++			__be16		port;
++		} v6;
++	} u;
++} __attribute__((__packed__));
++
++struct mp_remove_addr {
++	__u8	kind;
++	__u8	len;
++#if defined(__LITTLE_ENDIAN_BITFIELD)
++	__u8	rsv:4,
++		sub:4;
++#elif defined(__BIG_ENDIAN_BITFIELD)
++	__u8	sub:4,
++		rsv:4;
++#else
++#error "Adjust your <asm/byteorder.h> defines"
++#endif
++	/* list of addr_id */
++	__u8	addrs_id;
++};
++
++struct mp_fail {
++	__u8	kind;
++	__u8	len;
++#if defined(__LITTLE_ENDIAN_BITFIELD)
++	__u16	rsv1:4,
++		sub:4,
++		rsv2:8;
++#elif defined(__BIG_ENDIAN_BITFIELD)
++	__u16	sub:4,
++		rsv1:4,
++		rsv2:8;
++#else
++#error	"Adjust your <asm/byteorder.h> defines"
++#endif
++	__be64	data_seq;
++} __attribute__((__packed__));
++
++struct mp_fclose {
++	__u8	kind;
++	__u8	len;
++#if defined(__LITTLE_ENDIAN_BITFIELD)
++	__u16	rsv1:4,
++		sub:4,
++		rsv2:8;
++#elif defined(__BIG_ENDIAN_BITFIELD)
++	__u16	sub:4,
++		rsv1:4,
++		rsv2:8;
++#else
++#error	"Adjust your <asm/byteorder.h> defines"
++#endif
++	__u64	key;
++} __attribute__((__packed__));
++
++struct mp_prio {
++	__u8	kind;
++	__u8	len;
++#if defined(__LITTLE_ENDIAN_BITFIELD)
++	__u8	b:1,
++		rsv:3,
++		sub:4;
++#elif defined(__BIG_ENDIAN_BITFIELD)
++	__u8	sub:4,
++		rsv:3,
++		b:1;
++#else
++#error	"Adjust your <asm/byteorder.h> defines"
++#endif
++	__u8	addr_id;
++} __attribute__((__packed__));
++
++static inline int mptcp_sub_len_dss(const struct mp_dss *m, const int csum)
++{
++	return 4 + m->A * (4 + m->a * 4) + m->M * (10 + m->m * 4 + csum * 2);
++}
++
++#define MPTCP_APP	2
++
++extern int sysctl_mptcp_enabled;
++extern int sysctl_mptcp_checksum;
++extern int sysctl_mptcp_debug;
++extern int sysctl_mptcp_syn_retries;
++
++extern struct workqueue_struct *mptcp_wq;
++
++#define mptcp_debug(fmt, args...)					\
++	do {								\
++		if (unlikely(sysctl_mptcp_debug))			\
++			pr_err(__FILE__ ": " fmt, ##args);	\
++	} while (0)
++
++/* Iterates over all subflows */
++#define mptcp_for_each_tp(mpcb, tp)					\
++	for ((tp) = (mpcb)->connection_list; (tp); (tp) = (tp)->mptcp->next)
++
++#define mptcp_for_each_sk(mpcb, sk)					\
++	for ((sk) = (struct sock *)(mpcb)->connection_list;		\
++	     sk;							\
++	     sk = (struct sock *)tcp_sk(sk)->mptcp->next)
++
++#define mptcp_for_each_sk_safe(__mpcb, __sk, __temp)			\
++	for (__sk = (struct sock *)(__mpcb)->connection_list,		\
++	     __temp = __sk ? (struct sock *)tcp_sk(__sk)->mptcp->next : NULL; \
++	     __sk;							\
++	     __sk = __temp,						\
++	     __temp = __sk ? (struct sock *)tcp_sk(__sk)->mptcp->next : NULL)
++
++/* Iterates over all bit set to 1 in a bitset */
++#define mptcp_for_each_bit_set(b, i)					\
++	for (i = ffs(b) - 1; i >= 0; i = ffs(b >> (i + 1) << (i + 1)) - 1)
++
++#define mptcp_for_each_bit_unset(b, i)					\
++	mptcp_for_each_bit_set(~b, i)
++
++extern struct lock_class_key meta_key;
++extern struct lock_class_key meta_slock_key;
++extern u32 mptcp_secret[MD5_MESSAGE_BYTES / 4];
++
++/* This is needed to ensure that two subsequent key/nonce-generation result in
++ * different keys/nonces if the IPs and ports are the same.
++ */
++extern u32 mptcp_seed;
++
++#define MPTCP_HASH_SIZE                1024
++
++extern struct hlist_nulls_head tk_hashtable[MPTCP_HASH_SIZE];
++
++/* This second hashtable is needed to retrieve request socks
++ * created as a result of a join request. While the SYN contains
++ * the token, the final ack does not, so we need a separate hashtable
++ * to retrieve the mpcb.
++ */
++extern struct hlist_nulls_head mptcp_reqsk_htb[MPTCP_HASH_SIZE];
++extern spinlock_t mptcp_reqsk_hlock;	/* hashtable protection */
++
++/* Lock, protecting the two hash-tables that hold the token. Namely,
++ * mptcp_reqsk_tk_htb and tk_hashtable
++ */
++extern spinlock_t mptcp_tk_hashlock;	/* hashtable protection */
++
++/* Request-sockets can be hashed in the tk_htb for collision-detection or in
++ * the regular htb for join-connections. We need to define different NULLS
++ * values so that we can correctly detect a request-socket that has been
++ * recycled. See also c25eb3bfb9729.
++ */
++#define MPTCP_REQSK_NULLS_BASE (1U << 29)
++
++
++void mptcp_data_ready(struct sock *sk);
++void mptcp_write_space(struct sock *sk);
++
++void mptcp_add_meta_ofo_queue(const struct sock *meta_sk, struct sk_buff *skb,
++			      struct sock *sk);
++void mptcp_ofo_queue(struct sock *meta_sk);
++void mptcp_purge_ofo_queue(struct tcp_sock *meta_tp);
++void mptcp_cleanup_rbuf(struct sock *meta_sk, int copied);
++int mptcp_add_sock(struct sock *meta_sk, struct sock *sk, u8 loc_id, u8 rem_id,
++		   gfp_t flags);
++void mptcp_del_sock(struct sock *sk);
++void mptcp_update_metasocket(struct sock *sock, const struct sock *meta_sk);
++void mptcp_reinject_data(struct sock *orig_sk, int clone_it);
++void mptcp_update_sndbuf(const struct tcp_sock *tp);
++void mptcp_send_fin(struct sock *meta_sk);
++void mptcp_send_active_reset(struct sock *meta_sk, gfp_t priority);
++bool mptcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle,
++		      int push_one, gfp_t gfp);
++void tcp_parse_mptcp_options(const struct sk_buff *skb,
++			     struct mptcp_options_received *mopt);
++void mptcp_parse_options(const uint8_t *ptr, int opsize,
++			 struct mptcp_options_received *mopt,
++			 const struct sk_buff *skb);
++void mptcp_syn_options(const struct sock *sk, struct tcp_out_options *opts,
++		       unsigned *remaining);
++void mptcp_synack_options(struct request_sock *req,
++			  struct tcp_out_options *opts,
++			  unsigned *remaining);
++void mptcp_established_options(struct sock *sk, struct sk_buff *skb,
++			       struct tcp_out_options *opts, unsigned *size);
++void mptcp_options_write(__be32 *ptr, struct tcp_sock *tp,
++			 const struct tcp_out_options *opts,
++			 struct sk_buff *skb);
++void mptcp_close(struct sock *meta_sk, long timeout);
++int mptcp_doit(struct sock *sk);
++int mptcp_create_master_sk(struct sock *meta_sk, __u64 remote_key, u32 window);
++int mptcp_check_req_fastopen(struct sock *child, struct request_sock *req);
++int mptcp_check_req_master(struct sock *sk, struct sock *child,
++			   struct request_sock *req,
++			   struct request_sock **prev);
++struct sock *mptcp_check_req_child(struct sock *sk, struct sock *child,
++				   struct request_sock *req,
++				   struct request_sock **prev,
++				   const struct mptcp_options_received *mopt);
++u32 __mptcp_select_window(struct sock *sk);
++void mptcp_select_initial_window(int __space, __u32 mss, __u32 *rcv_wnd,
++					__u32 *window_clamp, int wscale_ok,
++					__u8 *rcv_wscale, __u32 init_rcv_wnd,
++					const struct sock *sk);
++unsigned int mptcp_current_mss(struct sock *meta_sk);
++int mptcp_select_size(const struct sock *meta_sk, bool sg);
++void mptcp_key_sha1(u64 key, u32 *token, u64 *idsn);
++void mptcp_hmac_sha1(u8 *key_1, u8 *key_2, u8 *rand_1, u8 *rand_2,
++		     u32 *hash_out);
++void mptcp_clean_rtx_infinite(const struct sk_buff *skb, struct sock *sk);
++void mptcp_fin(struct sock *meta_sk);
++void mptcp_retransmit_timer(struct sock *meta_sk);
++int mptcp_write_wakeup(struct sock *meta_sk);
++void mptcp_sub_close_wq(struct work_struct *work);
++void mptcp_sub_close(struct sock *sk, unsigned long delay);
++struct sock *mptcp_select_ack_sock(const struct sock *meta_sk);
++void mptcp_fallback_meta_sk(struct sock *meta_sk);
++int mptcp_backlog_rcv(struct sock *meta_sk, struct sk_buff *skb);
++void mptcp_ack_handler(unsigned long);
++int mptcp_check_rtt(const struct tcp_sock *tp, int time);
++int mptcp_check_snd_buf(const struct tcp_sock *tp);
++int mptcp_handle_options(struct sock *sk, const struct tcphdr *th,
++			 const struct sk_buff *skb);
++void __init mptcp_init(void);
++int mptcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len);
++void mptcp_destroy_sock(struct sock *sk);
++int mptcp_rcv_synsent_state_process(struct sock *sk, struct sock **skptr,
++				    const struct sk_buff *skb,
++				    const struct mptcp_options_received *mopt);
++unsigned int mptcp_xmit_size_goal(const struct sock *meta_sk, u32 mss_now,
++				  int large_allowed);
++int mptcp_init_tw_sock(struct sock *sk, struct tcp_timewait_sock *tw);
++void mptcp_twsk_destructor(struct tcp_timewait_sock *tw);
++void mptcp_time_wait(struct sock *sk, int state, int timeo);
++void mptcp_disconnect(struct sock *sk);
++bool mptcp_should_expand_sndbuf(const struct sock *sk);
++int mptcp_retransmit_skb(struct sock *meta_sk, struct sk_buff *skb);
++void mptcp_tsq_flags(struct sock *sk);
++void mptcp_tsq_sub_deferred(struct sock *meta_sk);
++struct mp_join *mptcp_find_join(const struct sk_buff *skb);
++void mptcp_hash_remove_bh(struct tcp_sock *meta_tp);
++void mptcp_hash_remove(struct tcp_sock *meta_tp);
++struct sock *mptcp_hash_find(const struct net *net, const u32 token);
++int mptcp_lookup_join(struct sk_buff *skb, struct inet_timewait_sock *tw);
++int mptcp_do_join_short(struct sk_buff *skb,
++			const struct mptcp_options_received *mopt,
++			struct net *net);
++void mptcp_reqsk_destructor(struct request_sock *req);
++void mptcp_reqsk_new_mptcp(struct request_sock *req,
++			   const struct mptcp_options_received *mopt,
++			   const struct sk_buff *skb);
++int mptcp_check_req(struct sk_buff *skb, struct net *net);
++void mptcp_connect_init(struct sock *sk);
++void mptcp_sub_force_close(struct sock *sk);
++int mptcp_sub_len_remove_addr_align(u16 bitfield);
++void mptcp_remove_shortcuts(const struct mptcp_cb *mpcb,
++			    const struct sk_buff *skb);
++void mptcp_init_buffer_space(struct sock *sk);
++void mptcp_join_reqsk_init(struct mptcp_cb *mpcb, const struct request_sock *req,
++			   struct sk_buff *skb);
++void mptcp_reqsk_init(struct request_sock *req, const struct sk_buff *skb);
++int mptcp_conn_request(struct sock *sk, struct sk_buff *skb);
++void mptcp_init_congestion_control(struct sock *sk);
++
++/* MPTCP-path-manager registration/initialization functions */
++int mptcp_register_path_manager(struct mptcp_pm_ops *pm);
++void mptcp_unregister_path_manager(struct mptcp_pm_ops *pm);
++void mptcp_init_path_manager(struct mptcp_cb *mpcb);
++void mptcp_cleanup_path_manager(struct mptcp_cb *mpcb);
++void mptcp_fallback_default(struct mptcp_cb *mpcb);
++void mptcp_get_default_path_manager(char *name);
++int mptcp_set_default_path_manager(const char *name);
++extern struct mptcp_pm_ops mptcp_pm_default;
++
++/* MPTCP-scheduler registration/initialization functions */
++int mptcp_register_scheduler(struct mptcp_sched_ops *sched);
++void mptcp_unregister_scheduler(struct mptcp_sched_ops *sched);
++void mptcp_init_scheduler(struct mptcp_cb *mpcb);
++void mptcp_cleanup_scheduler(struct mptcp_cb *mpcb);
++void mptcp_get_default_scheduler(char *name);
++int mptcp_set_default_scheduler(const char *name);
++extern struct mptcp_sched_ops mptcp_sched_default;
++
++static inline void mptcp_reset_synack_timer(struct sock *meta_sk,
++					    unsigned long len)
++{
++	sk_reset_timer(meta_sk, &tcp_sk(meta_sk)->mpcb->synack_timer,
++		       jiffies + len);
++}
++
++static inline void mptcp_delete_synack_timer(struct sock *meta_sk)
++{
++	sk_stop_timer(meta_sk, &tcp_sk(meta_sk)->mpcb->synack_timer);
++}
++
++static inline bool is_mptcp_enabled(const struct sock *sk)
++{
++	if (!sysctl_mptcp_enabled || mptcp_init_failed)
++		return false;
++
++	if (sysctl_mptcp_enabled == MPTCP_APP && !tcp_sk(sk)->mptcp_enabled)
++		return false;
++
++	return true;
++}
++
++static inline int mptcp_pi_to_flag(int pi)
++{
++	return 1 << (pi - 1);
++}
++
++static inline
++struct mptcp_request_sock *mptcp_rsk(const struct request_sock *req)
++{
++	return (struct mptcp_request_sock *)req;
++}
++
++static inline
++struct request_sock *rev_mptcp_rsk(const struct mptcp_request_sock *req)
++{
++	return (struct request_sock *)req;
++}
++
++static inline bool mptcp_can_sendpage(struct sock *sk)
++{
++	struct sock *sk_it;
++
++	if (tcp_sk(sk)->mpcb->dss_csum)
++		return false;
++
++	mptcp_for_each_sk(tcp_sk(sk)->mpcb, sk_it) {
++		if (!(sk_it->sk_route_caps & NETIF_F_SG) ||
++		    !(sk_it->sk_route_caps & NETIF_F_ALL_CSUM))
++			return false;
++	}
++
++	return true;
++}
++
++static inline void mptcp_push_pending_frames(struct sock *meta_sk)
++{
++	/* We check packets out and send-head here. TCP only checks the
++	 * send-head. But, MPTCP also checks packets_out, as this is an
++	 * indication that we might want to do opportunistic reinjection.
++	 */
++	if (tcp_sk(meta_sk)->packets_out || tcp_send_head(meta_sk)) {
++		struct tcp_sock *tp = tcp_sk(meta_sk);
++
++		/* We don't care about the MSS, because it will be set in
++		 * mptcp_write_xmit.
++		 */
++		__tcp_push_pending_frames(meta_sk, 0, tp->nonagle);
++	}
++}
++
++static inline void mptcp_send_reset(struct sock *sk)
++{
++	tcp_sk(sk)->ops->send_active_reset(sk, GFP_ATOMIC);
++	mptcp_sub_force_close(sk);
++}
++
++static inline bool mptcp_is_data_seq(const struct sk_buff *skb)
++{
++	return TCP_SKB_CB(skb)->mptcp_flags & MPTCPHDR_SEQ;
++}
++
++static inline bool mptcp_is_data_fin(const struct sk_buff *skb)
++{
++	return TCP_SKB_CB(skb)->mptcp_flags & MPTCPHDR_FIN;
++}
++
++/* Is it a data-fin while in infinite mapping mode?
++ * In infinite mode, a subflow-fin is in fact a data-fin.
++ */
++static inline bool mptcp_is_data_fin2(const struct sk_buff *skb,
++				     const struct tcp_sock *tp)
++{
++	return mptcp_is_data_fin(skb) ||
++	       (tp->mpcb->infinite_mapping_rcv && tcp_hdr(skb)->fin);
++}
++
++static inline u8 mptcp_get_64_bit(u64 data_seq, struct mptcp_cb *mpcb)
++{
++	u64 data_seq_high = (u32)(data_seq >> 32);
++
++	if (mpcb->rcv_high_order[0] == data_seq_high)
++		return 0;
++	else if (mpcb->rcv_high_order[1] == data_seq_high)
++		return MPTCPHDR_SEQ64_INDEX;
++	else
++		return MPTCPHDR_SEQ64_OFO;
++}
++
++/* Sets the data_seq and returns pointer to the in-skb field of the data_seq.
++ * If the packet has a 64-bit dseq, the pointer points to the last 32 bits.
++ */
++static inline __u32 *mptcp_skb_set_data_seq(const struct sk_buff *skb,
++					    u32 *data_seq,
++					    struct mptcp_cb *mpcb)
++{
++	__u32 *ptr = (__u32 *)(skb_transport_header(skb) + TCP_SKB_CB(skb)->dss_off);
++
++	if (TCP_SKB_CB(skb)->mptcp_flags & MPTCPHDR_SEQ64_SET) {
++		u64 data_seq64 = get_unaligned_be64(ptr);
++
++		if (mpcb)
++			TCP_SKB_CB(skb)->mptcp_flags |= mptcp_get_64_bit(data_seq64, mpcb);
++
++		*data_seq = (u32)data_seq64;
++		ptr++;
++	} else {
++		*data_seq = get_unaligned_be32(ptr);
++	}
++
++	return ptr;
++}
++
++static inline struct sock *mptcp_meta_sk(const struct sock *sk)
++{
++	return tcp_sk(sk)->meta_sk;
++}
++
++static inline struct tcp_sock *mptcp_meta_tp(const struct tcp_sock *tp)
++{
++	return tcp_sk(tp->meta_sk);
++}
++
++static inline int is_meta_tp(const struct tcp_sock *tp)
++{
++	return tp->mpcb && mptcp_meta_tp(tp) == tp;
++}
++
++static inline int is_meta_sk(const struct sock *sk)
++{
++	return sk->sk_type == SOCK_STREAM  && sk->sk_protocol == IPPROTO_TCP &&
++	       mptcp(tcp_sk(sk)) && mptcp_meta_sk(sk) == sk;
++}
++
++static inline int is_master_tp(const struct tcp_sock *tp)
++{
++	return !mptcp(tp) || (!tp->mptcp->slave_sk && !is_meta_tp(tp));
++}
++
++static inline void mptcp_hash_request_remove(struct request_sock *req)
++{
++	int in_softirq = 0;
++
++	if (hlist_nulls_unhashed(&mptcp_rsk(req)->hash_entry))
++		return;
++
++	if (in_softirq()) {
++		spin_lock(&mptcp_reqsk_hlock);
++		in_softirq = 1;
++	} else {
++		spin_lock_bh(&mptcp_reqsk_hlock);
++	}
++
++	hlist_nulls_del_init_rcu(&mptcp_rsk(req)->hash_entry);
++
++	if (in_softirq)
++		spin_unlock(&mptcp_reqsk_hlock);
++	else
++		spin_unlock_bh(&mptcp_reqsk_hlock);
++}
++
++static inline void mptcp_init_mp_opt(struct mptcp_options_received *mopt)
++{
++	mopt->saw_mpc = 0;
++	mopt->dss_csum = 0;
++	mopt->drop_me = 0;
++
++	mopt->is_mp_join = 0;
++	mopt->join_ack = 0;
++
++	mopt->saw_low_prio = 0;
++	mopt->low_prio = 0;
++
++	mopt->saw_add_addr = 0;
++	mopt->more_add_addr = 0;
++
++	mopt->saw_rem_addr = 0;
++	mopt->more_rem_addr = 0;
++
++	mopt->mp_fail = 0;
++	mopt->mp_fclose = 0;
++}
++
++static inline void mptcp_reset_mopt(struct tcp_sock *tp)
++{
++	struct mptcp_options_received *mopt = &tp->mptcp->rx_opt;
++
++	mopt->saw_low_prio = 0;
++	mopt->saw_add_addr = 0;
++	mopt->more_add_addr = 0;
++	mopt->saw_rem_addr = 0;
++	mopt->more_rem_addr = 0;
++	mopt->join_ack = 0;
++	mopt->mp_fail = 0;
++	mopt->mp_fclose = 0;
++}
++
++static inline __be32 mptcp_get_highorder_sndbits(const struct sk_buff *skb,
++						 const struct mptcp_cb *mpcb)
++{
++	return htonl(mpcb->snd_high_order[(TCP_SKB_CB(skb)->mptcp_flags &
++			MPTCPHDR_SEQ64_INDEX) ? 1 : 0]);
++}
++
++static inline u64 mptcp_get_data_seq_64(const struct mptcp_cb *mpcb, int index,
++					u32 data_seq_32)
++{
++	return ((u64)mpcb->rcv_high_order[index] << 32) | data_seq_32;
++}
++
++static inline u64 mptcp_get_rcv_nxt_64(const struct tcp_sock *meta_tp)
++{
++	struct mptcp_cb *mpcb = meta_tp->mpcb;
++	return mptcp_get_data_seq_64(mpcb, mpcb->rcv_hiseq_index,
++				     meta_tp->rcv_nxt);
++}
++
++static inline void mptcp_check_sndseq_wrap(struct tcp_sock *meta_tp, int inc)
++{
++	if (unlikely(meta_tp->snd_nxt > meta_tp->snd_nxt + inc)) {
++		struct mptcp_cb *mpcb = meta_tp->mpcb;
++		mpcb->snd_hiseq_index = mpcb->snd_hiseq_index ? 0 : 1;
++		mpcb->snd_high_order[mpcb->snd_hiseq_index] += 2;
++	}
++}
++
++static inline void mptcp_check_rcvseq_wrap(struct tcp_sock *meta_tp,
++					   u32 old_rcv_nxt)
++{
++	if (unlikely(old_rcv_nxt > meta_tp->rcv_nxt)) {
++		struct mptcp_cb *mpcb = meta_tp->mpcb;
++		mpcb->rcv_high_order[mpcb->rcv_hiseq_index] += 2;
++		mpcb->rcv_hiseq_index = mpcb->rcv_hiseq_index ? 0 : 1;
++	}
++}
++
++static inline int mptcp_sk_can_send(const struct sock *sk)
++{
++	return tcp_passive_fastopen(sk) ||
++	       ((1 << sk->sk_state) & (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT) &&
++		!tcp_sk(sk)->mptcp->pre_established);
++}
++
++static inline int mptcp_sk_can_recv(const struct sock *sk)
++{
++	return (1 << sk->sk_state) & (TCPF_ESTABLISHED | TCPF_FIN_WAIT1 | TCPF_FIN_WAIT2);
++}
++
++static inline int mptcp_sk_can_send_ack(const struct sock *sk)
++{
++	return !((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV |
++					TCPF_CLOSE | TCPF_LISTEN)) &&
++	       !tcp_sk(sk)->mptcp->pre_established;
++}
++
++/* Only support GSO if all subflows supports it */
++static inline bool mptcp_sk_can_gso(const struct sock *meta_sk)
++{
++	struct sock *sk;
++
++	if (tcp_sk(meta_sk)->mpcb->dss_csum)
++		return false;
++
++	mptcp_for_each_sk(tcp_sk(meta_sk)->mpcb, sk) {
++		if (!mptcp_sk_can_send(sk))
++			continue;
++		if (!sk_can_gso(sk))
++			return false;
++	}
++	return true;
++}
++
++static inline bool mptcp_can_sg(const struct sock *meta_sk)
++{
++	struct sock *sk;
++
++	if (tcp_sk(meta_sk)->mpcb->dss_csum)
++		return false;
++
++	mptcp_for_each_sk(tcp_sk(meta_sk)->mpcb, sk) {
++		if (!mptcp_sk_can_send(sk))
++			continue;
++		if (!(sk->sk_route_caps & NETIF_F_SG))
++			return false;
++	}
++	return true;
++}
++
++static inline void mptcp_set_rto(struct sock *sk)
++{
++	struct tcp_sock *tp = tcp_sk(sk);
++	struct sock *sk_it;
++	struct inet_connection_sock *micsk = inet_csk(mptcp_meta_sk(sk));
++	__u32 max_rto = 0;
++
++	/* We are in recovery-phase on the MPTCP-level. Do not update the
++	 * RTO, because this would kill exponential backoff.
++	 */
++	if (micsk->icsk_retransmits)
++		return;
++
++	mptcp_for_each_sk(tp->mpcb, sk_it) {
++		if (mptcp_sk_can_send(sk_it) &&
++		    inet_csk(sk_it)->icsk_rto > max_rto)
++			max_rto = inet_csk(sk_it)->icsk_rto;
++	}
++	if (max_rto) {
++		micsk->icsk_rto = max_rto << 1;
++
++		/* A successfull rto-measurement - reset backoff counter */
++		micsk->icsk_backoff = 0;
++	}
++}
++
++static inline int mptcp_sysctl_syn_retries(void)
++{
++	return sysctl_mptcp_syn_retries;
++}
++
++static inline void mptcp_sub_close_passive(struct sock *sk)
++{
++	struct sock *meta_sk = mptcp_meta_sk(sk);
++	struct tcp_sock *tp = tcp_sk(sk), *meta_tp = tcp_sk(meta_sk);
++
++	/* Only close, if the app did a send-shutdown (passive close), and we
++	 * received the data-ack of the data-fin.
++	 */
++	if (tp->mpcb->passive_close && meta_tp->snd_una == meta_tp->write_seq)
++		mptcp_sub_close(sk, 0);
++}
++
++static inline bool mptcp_fallback_infinite(struct sock *sk, int flag)
++{
++	struct tcp_sock *tp = tcp_sk(sk);
++
++	/* If data has been acknowleged on the meta-level, fully_established
++	 * will have been set before and thus we will not fall back to infinite
++	 * mapping.
++	 */
++	if (likely(tp->mptcp->fully_established))
++		return false;
++
++	if (!(flag & MPTCP_FLAG_DATA_ACKED))
++		return false;
++
++	/* Don't fallback twice ;) */
++	if (tp->mpcb->infinite_mapping_snd)
++		return false;
++
++	pr_err("%s %#x will fallback - pi %d, src %pI4 dst %pI4 from %pS\n",
++	       __func__, tp->mpcb->mptcp_loc_token, tp->mptcp->path_index,
++	       &inet_sk(sk)->inet_saddr, &inet_sk(sk)->inet_daddr,
++	       __builtin_return_address(0));
++	if (!is_master_tp(tp))
++		return true;
++
++	tp->mpcb->infinite_mapping_snd = 1;
++	tp->mpcb->infinite_mapping_rcv = 1;
++	tp->mptcp->fully_established = 1;
++
++	return false;
++}
++
++/* Find the first index whose bit in the bit-field == 0 */
++static inline u8 mptcp_set_new_pathindex(struct mptcp_cb *mpcb)
++{
++	u8 base = mpcb->next_path_index;
++	int i;
++
++	/* Start at 1, because 0 is reserved for the meta-sk */
++	mptcp_for_each_bit_unset(mpcb->path_index_bits >> base, i) {
++		if (i + base < 1)
++			continue;
++		if (i + base >= sizeof(mpcb->path_index_bits) * 8)
++			break;
++		i += base;
++		mpcb->path_index_bits |= (1 << i);
++		mpcb->next_path_index = i + 1;
++		return i;
++	}
++	mptcp_for_each_bit_unset(mpcb->path_index_bits, i) {
++		if (i >= sizeof(mpcb->path_index_bits) * 8)
++			break;
++		if (i < 1)
++			continue;
++		mpcb->path_index_bits |= (1 << i);
++		mpcb->next_path_index = i + 1;
++		return i;
++	}
++
++	return 0;
++}
++
++static inline bool mptcp_v6_is_v4_mapped(const struct sock *sk)
++{
++	return sk->sk_family == AF_INET6 &&
++	       ipv6_addr_type(&inet6_sk(sk)->saddr) == IPV6_ADDR_MAPPED;
++}
++
++/* TCP and MPTCP mpc flag-depending functions */
++u16 mptcp_select_window(struct sock *sk);
++void mptcp_init_buffer_space(struct sock *sk);
++void mptcp_tcp_set_rto(struct sock *sk);
++
++/* TCP and MPTCP flag-depending functions */
++bool mptcp_prune_ofo_queue(struct sock *sk);
++
++#else /* CONFIG_MPTCP */
++#define mptcp_debug(fmt, args...)	\
++	do {				\
++	} while (0)
++
++/* Without MPTCP, we just do one iteration
++ * over the only socket available. This assumes that
++ * the sk/tp arg is the socket in that case.
++ */
++#define mptcp_for_each_sk(mpcb, sk)
++#define mptcp_for_each_sk_safe(__mpcb, __sk, __temp)
++
++static inline bool mptcp_is_data_fin(const struct sk_buff *skb)
++{
++	return false;
++}
++static inline bool mptcp_is_data_seq(const struct sk_buff *skb)
++{
++	return false;
++}
++static inline struct sock *mptcp_meta_sk(const struct sock *sk)
++{
++	return NULL;
++}
++static inline struct tcp_sock *mptcp_meta_tp(const struct tcp_sock *tp)
++{
++	return NULL;
++}
++static inline int is_meta_sk(const struct sock *sk)
++{
++	return 0;
++}
++static inline int is_master_tp(const struct tcp_sock *tp)
++{
++	return 0;
++}
++static inline void mptcp_purge_ofo_queue(struct tcp_sock *meta_tp) {}
++static inline void mptcp_del_sock(const struct sock *sk) {}
++static inline void mptcp_update_metasocket(struct sock *sock, const struct sock *meta_sk) {}
++static inline void mptcp_reinject_data(struct sock *orig_sk, int clone_it) {}
++static inline void mptcp_update_sndbuf(const struct tcp_sock *tp) {}
++static inline void mptcp_clean_rtx_infinite(const struct sk_buff *skb,
++					    const struct sock *sk) {}
++static inline void mptcp_sub_close(struct sock *sk, unsigned long delay) {}
++static inline void mptcp_set_rto(const struct sock *sk) {}
++static inline void mptcp_send_fin(const struct sock *meta_sk) {}
++static inline void mptcp_parse_options(const uint8_t *ptr, const int opsize,
++				       const struct mptcp_options_received *mopt,
++				       const struct sk_buff *skb) {}
++static inline void mptcp_syn_options(const struct sock *sk,
++				     struct tcp_out_options *opts,
++				     unsigned *remaining) {}
++static inline void mptcp_synack_options(struct request_sock *req,
++					struct tcp_out_options *opts,
++					unsigned *remaining) {}
++
++static inline void mptcp_established_options(struct sock *sk,
++					     struct sk_buff *skb,
++					     struct tcp_out_options *opts,
++					     unsigned *size) {}
++static inline void mptcp_options_write(__be32 *ptr, struct tcp_sock *tp,
++				       const struct tcp_out_options *opts,
++				       struct sk_buff *skb) {}
++static inline void mptcp_close(struct sock *meta_sk, long timeout) {}
++static inline int mptcp_doit(struct sock *sk)
++{
++	return 0;
++}
++static inline int mptcp_check_req_fastopen(struct sock *child,
++					   struct request_sock *req)
++{
++	return 1;
++}
++static inline int mptcp_check_req_master(const struct sock *sk,
++					 const struct sock *child,
++					 struct request_sock *req,
++					 struct request_sock **prev)
++{
++	return 1;
++}
++static inline struct sock *mptcp_check_req_child(struct sock *sk,
++						 struct sock *child,
++						 struct request_sock *req,
++						 struct request_sock **prev,
++						 const struct mptcp_options_received *mopt)
++{
++	return NULL;
++}
++static inline unsigned int mptcp_current_mss(struct sock *meta_sk)
++{
++	return 0;
++}
++static inline int mptcp_select_size(const struct sock *meta_sk, bool sg)
++{
++	return 0;
++}
++static inline void mptcp_sub_close_passive(struct sock *sk) {}
++static inline bool mptcp_fallback_infinite(const struct sock *sk, int flag)
++{
++	return false;
++}
++static inline void mptcp_init_mp_opt(const struct mptcp_options_received *mopt) {}
++static inline int mptcp_check_rtt(const struct tcp_sock *tp, int time)
++{
++	return 0;
++}
++static inline int mptcp_check_snd_buf(const struct tcp_sock *tp)
++{
++	return 0;
++}
++static inline int mptcp_sysctl_syn_retries(void)
++{
++	return 0;
++}
++static inline void mptcp_send_reset(const struct sock *sk) {}
++static inline int mptcp_handle_options(struct sock *sk,
++				       const struct tcphdr *th,
++				       struct sk_buff *skb)
++{
++	return 0;
++}
++static inline void mptcp_reset_mopt(struct tcp_sock *tp) {}
++static inline void  __init mptcp_init(void) {}
++static inline int mptcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len)
++{
++	return 0;
++}
++static inline bool mptcp_sk_can_gso(const struct sock *sk)
++{
++	return false;
++}
++static inline bool mptcp_can_sg(const struct sock *meta_sk)
++{
++	return false;
++}
++static inline unsigned int mptcp_xmit_size_goal(const struct sock *meta_sk,
++						u32 mss_now, int large_allowed)
++{
++	return 0;
++}
++static inline void mptcp_destroy_sock(struct sock *sk) {}
++static inline int mptcp_rcv_synsent_state_process(struct sock *sk,
++						  struct sock **skptr,
++						  struct sk_buff *skb,
++						  const struct mptcp_options_received *mopt)
++{
++	return 0;
++}
++static inline bool mptcp_can_sendpage(struct sock *sk)
++{
++	return false;
++}
++static inline int mptcp_init_tw_sock(struct sock *sk,
++				     struct tcp_timewait_sock *tw)
++{
++	return 0;
++}
++static inline void mptcp_twsk_destructor(struct tcp_timewait_sock *tw) {}
++static inline void mptcp_disconnect(struct sock *sk) {}
++static inline void mptcp_tsq_flags(struct sock *sk) {}
++static inline void mptcp_tsq_sub_deferred(struct sock *meta_sk) {}
++static inline void mptcp_hash_remove_bh(struct tcp_sock *meta_tp) {}
++static inline void mptcp_hash_remove(struct tcp_sock *meta_tp) {}
++static inline void mptcp_reqsk_new_mptcp(struct request_sock *req,
++					 const struct tcp_options_received *rx_opt,
++					 const struct mptcp_options_received *mopt,
++					 const struct sk_buff *skb) {}
++static inline void mptcp_remove_shortcuts(const struct mptcp_cb *mpcb,
++					  const struct sk_buff *skb) {}
++static inline void mptcp_delete_synack_timer(struct sock *meta_sk) {}
++#endif /* CONFIG_MPTCP */
++
++#endif /* _MPTCP_H */
+diff --git a/include/net/mptcp_v4.h b/include/net/mptcp_v4.h
+new file mode 100644
+index 000000000000..93ad97c77c5a
+--- /dev/null
++++ b/include/net/mptcp_v4.h
+@@ -0,0 +1,67 @@
++/*
++ *	MPTCP implementation
++ *
++ *	Initial Design & Implementation:
++ *	Sébastien Barré <sebastien.barre@×××××××××.be>
++ *
++ *	Current Maintainer & Author:
++ *	Christoph Paasch <christoph.paasch@×××××××××.be>
++ *
++ *	Additional authors:
++ *	Jaakko Korkeaniemi <jaakko.korkeaniemi@×××××.fi>
++ *	Gregory Detal <gregory.detal@×××××××××.be>
++ *	Fabien Duchêne <fabien.duchene@×××××××××.be>
++ *	Andreas Seelinger <Andreas.Seelinger@×××××××××××.de>
++ *	Lavkesh Lahngir <lavkesh51@×××××.com>
++ *	Andreas Ripke <ripke@××××××.eu>
++ *	Vlad Dogaru <vlad.dogaru@×××××.com>
++ *	Octavian Purdila <octavian.purdila@×××××.com>
++ *	John Ronan <jronan@××××.org>
++ *	Catalin Nicutar <catalin.nicutar@×××××.com>
++ *	Brandon Heller <brandonh@××××××××.edu>
++ *
++ *
++ *	This program is free software; you can redistribute it and/or
++ *      modify it under the terms of the GNU General Public License
++ *      as published by the Free Software Foundation; either version
++ *      2 of the License, or (at your option) any later version.
++ */
++
++#ifndef MPTCP_V4_H_
++#define MPTCP_V4_H_
++
++
++#include <linux/in.h>
++#include <linux/skbuff.h>
++#include <net/mptcp.h>
++#include <net/request_sock.h>
++#include <net/sock.h>
++
++extern struct request_sock_ops mptcp_request_sock_ops;
++extern const struct inet_connection_sock_af_ops mptcp_v4_specific;
++extern struct tcp_request_sock_ops mptcp_request_sock_ipv4_ops;
++extern struct tcp_request_sock_ops mptcp_join_request_sock_ipv4_ops;
++
++#ifdef CONFIG_MPTCP
++
++int mptcp_v4_do_rcv(struct sock *meta_sk, struct sk_buff *skb);
++struct sock *mptcp_v4_search_req(const __be16 rport, const __be32 raddr,
++				 const __be32 laddr, const struct net *net);
++int mptcp_init4_subsockets(struct sock *meta_sk, const struct mptcp_loc4 *loc,
++			   struct mptcp_rem4 *rem);
++int mptcp_pm_v4_init(void);
++void mptcp_pm_v4_undo(void);
++u32 mptcp_v4_get_nonce(__be32 saddr, __be32 daddr, __be16 sport, __be16 dport);
++u64 mptcp_v4_get_key(__be32 saddr, __be32 daddr, __be16 sport, __be16 dport);
++
++#else
++
++static inline int mptcp_v4_do_rcv(const struct sock *meta_sk,
++				  const struct sk_buff *skb)
++{
++	return 0;
++}
++
++#endif /* CONFIG_MPTCP */
++
++#endif /* MPTCP_V4_H_ */
+diff --git a/include/net/mptcp_v6.h b/include/net/mptcp_v6.h
+new file mode 100644
+index 000000000000..49a4f30ccd4d
+--- /dev/null
++++ b/include/net/mptcp_v6.h
+@@ -0,0 +1,69 @@
++/*
++ *	MPTCP implementation
++ *
++ *	Initial Design & Implementation:
++ *	Sébastien Barré <sebastien.barre@×××××××××.be>
++ *
++ *	Current Maintainer & Author:
++ *	Jaakko Korkeaniemi <jaakko.korkeaniemi@×××××.fi>
++ *
++ *	Additional authors:
++ *	Jaakko Korkeaniemi <jaakko.korkeaniemi@×××××.fi>
++ *	Gregory Detal <gregory.detal@×××××××××.be>
++ *	Fabien Duchêne <fabien.duchene@×××××××××.be>
++ *	Andreas Seelinger <Andreas.Seelinger@×××××××××××.de>
++ *	Lavkesh Lahngir <lavkesh51@×××××.com>
++ *	Andreas Ripke <ripke@××××××.eu>
++ *	Vlad Dogaru <vlad.dogaru@×××××.com>
++ *	Octavian Purdila <octavian.purdila@×××××.com>
++ *	John Ronan <jronan@××××.org>
++ *	Catalin Nicutar <catalin.nicutar@×××××.com>
++ *	Brandon Heller <brandonh@××××××××.edu>
++ *
++ *
++ *	This program is free software; you can redistribute it and/or
++ *      modify it under the terms of the GNU General Public License
++ *      as published by the Free Software Foundation; either version
++ *      2 of the License, or (at your option) any later version.
++ */
++
++#ifndef _MPTCP_V6_H
++#define _MPTCP_V6_H
++
++#include <linux/in6.h>
++#include <net/if_inet6.h>
++
++#include <net/mptcp.h>
++
++
++#ifdef CONFIG_MPTCP
++extern const struct inet_connection_sock_af_ops mptcp_v6_mapped;
++extern const struct inet_connection_sock_af_ops mptcp_v6_specific;
++extern struct request_sock_ops mptcp6_request_sock_ops;
++extern struct tcp_request_sock_ops mptcp_request_sock_ipv6_ops;
++extern struct tcp_request_sock_ops mptcp_join_request_sock_ipv6_ops;
++
++int mptcp_v6_do_rcv(struct sock *meta_sk, struct sk_buff *skb);
++struct sock *mptcp_v6_search_req(const __be16 rport, const struct in6_addr *raddr,
++				 const struct in6_addr *laddr, const struct net *net);
++int mptcp_init6_subsockets(struct sock *meta_sk, const struct mptcp_loc6 *loc,
++			   struct mptcp_rem6 *rem);
++int mptcp_pm_v6_init(void);
++void mptcp_pm_v6_undo(void);
++__u32 mptcp_v6_get_nonce(const __be32 *saddr, const __be32 *daddr,
++			 __be16 sport, __be16 dport);
++u64 mptcp_v6_get_key(const __be32 *saddr, const __be32 *daddr,
++		     __be16 sport, __be16 dport);
++
++#else /* CONFIG_MPTCP */
++
++#define mptcp_v6_mapped ipv6_mapped
++
++static inline int mptcp_v6_do_rcv(struct sock *meta_sk, struct sk_buff *skb)
++{
++	return 0;
++}
++
++#endif /* CONFIG_MPTCP */
++
++#endif /* _MPTCP_V6_H */
+diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
+index 361d26077196..bae95a11c531 100644
+--- a/include/net/net_namespace.h
++++ b/include/net/net_namespace.h
+@@ -16,6 +16,7 @@
+ #include <net/netns/packet.h>
+ #include <net/netns/ipv4.h>
+ #include <net/netns/ipv6.h>
++#include <net/netns/mptcp.h>
+ #include <net/netns/ieee802154_6lowpan.h>
+ #include <net/netns/sctp.h>
+ #include <net/netns/dccp.h>
+@@ -92,6 +93,9 @@ struct net {
+ #if IS_ENABLED(CONFIG_IPV6)
+ 	struct netns_ipv6	ipv6;
+ #endif
++#if IS_ENABLED(CONFIG_MPTCP)
++	struct netns_mptcp	mptcp;
++#endif
+ #if IS_ENABLED(CONFIG_IEEE802154_6LOWPAN)
+ 	struct netns_ieee802154_lowpan	ieee802154_lowpan;
+ #endif
+diff --git a/include/net/netns/mptcp.h b/include/net/netns/mptcp.h
+new file mode 100644
+index 000000000000..bad418b04cc8
+--- /dev/null
++++ b/include/net/netns/mptcp.h
+@@ -0,0 +1,44 @@
++/*
++ *	MPTCP implementation - MPTCP namespace
++ *
++ *	Initial Design & Implementation:
++ *	Sébastien Barré <sebastien.barre@×××××××××.be>
++ *
++ *	Current Maintainer:
++ *	Christoph Paasch <christoph.paasch@×××××××××.be>
++ *
++ *	Additional authors:
++ *	Jaakko Korkeaniemi <jaakko.korkeaniemi@×××××.fi>
++ *	Gregory Detal <gregory.detal@×××××××××.be>
++ *	Fabien Duchêne <fabien.duchene@×××××××××.be>
++ *	Andreas Seelinger <Andreas.Seelinger@×××××××××××.de>
++ *	Lavkesh Lahngir <lavkesh51@×××××.com>
++ *	Andreas Ripke <ripke@××××××.eu>
++ *	Vlad Dogaru <vlad.dogaru@×××××.com>
++ *	Octavian Purdila <octavian.purdila@×××××.com>
++ *	John Ronan <jronan@××××.org>
++ *	Catalin Nicutar <catalin.nicutar@×××××.com>
++ *	Brandon Heller <brandonh@××××××××.edu>
++ *
++ *
++ *	This program is free software; you can redistribute it and/or
++ *      modify it under the terms of the GNU General Public License
++ *      as published by the Free Software Foundation; either version
++ *      2 of the License, or (at your option) any later version.
++ */
++
++#ifndef __NETNS_MPTCP_H__
++#define __NETNS_MPTCP_H__
++
++#include <linux/compiler.h>
++
++enum {
++	MPTCP_PM_FULLMESH = 0,
++	MPTCP_PM_MAX
++};
++
++struct netns_mptcp {
++	void *path_managers[MPTCP_PM_MAX];
++};
++
++#endif /* __NETNS_MPTCP_H__ */
+diff --git a/include/net/request_sock.h b/include/net/request_sock.h
+index 7f830ff67f08..e79e87a8e1a6 100644
+--- a/include/net/request_sock.h
++++ b/include/net/request_sock.h
+@@ -164,7 +164,7 @@ struct request_sock_queue {
+ };
+ 
+ int reqsk_queue_alloc(struct request_sock_queue *queue,
+-		      unsigned int nr_table_entries);
++		      unsigned int nr_table_entries, gfp_t flags);
+ 
+ void __reqsk_queue_destroy(struct request_sock_queue *queue);
+ void reqsk_queue_destroy(struct request_sock_queue *queue);
+diff --git a/include/net/sock.h b/include/net/sock.h
+index 156350745700..0e23cae8861f 100644
+--- a/include/net/sock.h
++++ b/include/net/sock.h
+@@ -901,6 +901,16 @@ void sk_clear_memalloc(struct sock *sk);
+ 
+ int sk_wait_data(struct sock *sk, long *timeo);
+ 
++/* START - needed for MPTCP */
++struct sock *sk_prot_alloc(struct proto *prot, gfp_t priority, int family);
++void sock_lock_init(struct sock *sk);
++
++extern struct lock_class_key af_callback_keys[AF_MAX];
++extern char *const af_family_clock_key_strings[AF_MAX+1];
++
++#define SK_FLAGS_TIMESTAMP ((1UL << SOCK_TIMESTAMP) | (1UL << SOCK_TIMESTAMPING_RX_SOFTWARE))
++/* END - needed for MPTCP */
++
+ struct request_sock_ops;
+ struct timewait_sock_ops;
+ struct inet_hashinfo;
+diff --git a/include/net/tcp.h b/include/net/tcp.h
+index 7286db80e8b8..ff92e74cd684 100644
+--- a/include/net/tcp.h
++++ b/include/net/tcp.h
+@@ -177,6 +177,7 @@ void tcp_time_wait(struct sock *sk, int state, int timeo);
+ #define TCPOPT_SACK             5       /* SACK Block */
+ #define TCPOPT_TIMESTAMP	8	/* Better RTT estimations/PAWS */
+ #define TCPOPT_MD5SIG		19	/* MD5 Signature (RFC2385) */
++#define TCPOPT_MPTCP		30
+ #define TCPOPT_EXP		254	/* Experimental */
+ /* Magic number to be after the option value for sharing TCP
+  * experimental options. See draft-ietf-tcpm-experimental-options-00.txt
+@@ -229,6 +230,27 @@ void tcp_time_wait(struct sock *sk, int state, int timeo);
+ #define	TFO_SERVER_WO_SOCKOPT1	0x400
+ #define	TFO_SERVER_WO_SOCKOPT2	0x800
+ 
++/* Flags from tcp_input.c for tcp_ack */
++#define FLAG_DATA               0x01 /* Incoming frame contained data.          */
++#define FLAG_WIN_UPDATE         0x02 /* Incoming ACK was a window update.       */
++#define FLAG_DATA_ACKED         0x04 /* This ACK acknowledged new data.         */
++#define FLAG_RETRANS_DATA_ACKED 0x08 /* "" "" some of which was retransmitted.  */
++#define FLAG_SYN_ACKED          0x10 /* This ACK acknowledged SYN.              */
++#define FLAG_DATA_SACKED        0x20 /* New SACK.                               */
++#define FLAG_ECE                0x40 /* ECE in this ACK                         */
++#define FLAG_SLOWPATH           0x100 /* Do not skip RFC checks for window update.*/
++#define FLAG_ORIG_SACK_ACKED    0x200 /* Never retransmitted data are (s)acked  */
++#define FLAG_SND_UNA_ADVANCED   0x400 /* Snd_una was changed (!= FLAG_DATA_ACKED) */
++#define FLAG_DSACKING_ACK       0x800 /* SACK blocks contained D-SACK info */
++#define FLAG_SACK_RENEGING      0x2000 /* snd_una advanced to a sacked seq */
++#define FLAG_UPDATE_TS_RECENT   0x4000 /* tcp_replace_ts_recent() */
++#define MPTCP_FLAG_DATA_ACKED	0x8000
++
++#define FLAG_ACKED              (FLAG_DATA_ACKED|FLAG_SYN_ACKED)
++#define FLAG_NOT_DUP            (FLAG_DATA|FLAG_WIN_UPDATE|FLAG_ACKED)
++#define FLAG_CA_ALERT           (FLAG_DATA_SACKED|FLAG_ECE)
++#define FLAG_FORWARD_PROGRESS   (FLAG_ACKED|FLAG_DATA_SACKED)
++
+ extern struct inet_timewait_death_row tcp_death_row;
+ 
+ /* sysctl variables for tcp */
+@@ -344,6 +366,107 @@ extern struct proto tcp_prot;
+ #define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val)
+ #define TCP_ADD_STATS(net, field, val)	SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
+ 
++/**** START - Exports needed for MPTCP ****/
++extern const struct tcp_request_sock_ops tcp_request_sock_ipv4_ops;
++extern const struct tcp_request_sock_ops tcp_request_sock_ipv6_ops;
++
++struct mptcp_options_received;
++
++void tcp_enter_quickack_mode(struct sock *sk);
++int tcp_close_state(struct sock *sk);
++void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss_now,
++			 const struct sk_buff *skb);
++int tcp_xmit_probe_skb(struct sock *sk, int urgent);
++void tcp_event_new_data_sent(struct sock *sk, const struct sk_buff *skb);
++int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
++		     gfp_t gfp_mask);
++unsigned int tcp_mss_split_point(const struct sock *sk,
++				 const struct sk_buff *skb,
++				 unsigned int mss_now,
++				 unsigned int max_segs,
++				 int nonagle);
++bool tcp_nagle_test(const struct tcp_sock *tp, const struct sk_buff *skb,
++		    unsigned int cur_mss, int nonagle);
++bool tcp_snd_wnd_test(const struct tcp_sock *tp, const struct sk_buff *skb,
++		      unsigned int cur_mss);
++unsigned int tcp_cwnd_test(const struct tcp_sock *tp, const struct sk_buff *skb);
++int tcp_init_tso_segs(const struct sock *sk, struct sk_buff *skb,
++		      unsigned int mss_now);
++void __pskb_trim_head(struct sk_buff *skb, int len);
++void tcp_queue_skb(struct sock *sk, struct sk_buff *skb);
++void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags);
++void tcp_reset(struct sock *sk);
++bool tcp_may_update_window(const struct tcp_sock *tp, const u32 ack,
++			   const u32 ack_seq, const u32 nwin);
++bool tcp_urg_mode(const struct tcp_sock *tp);
++void tcp_ack_probe(struct sock *sk);
++void tcp_rearm_rto(struct sock *sk);
++int tcp_write_timeout(struct sock *sk);
++bool retransmits_timed_out(struct sock *sk, unsigned int boundary,
++			   unsigned int timeout, bool syn_set);
++void tcp_write_err(struct sock *sk);
++void tcp_adjust_pcount(struct sock *sk, const struct sk_buff *skb, int decr);
++void tcp_set_skb_tso_segs(const struct sock *sk, struct sk_buff *skb,
++			  unsigned int mss_now);
++
++int tcp_v4_rtx_synack(struct sock *sk, struct request_sock *req);
++void tcp_v4_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
++			   struct request_sock *req);
++__u32 tcp_v4_init_sequence(const struct sk_buff *skb);
++int tcp_v4_send_synack(struct sock *sk, struct dst_entry *dst,
++		       struct flowi *fl,
++		       struct request_sock *req,
++		       u16 queue_mapping,
++		       struct tcp_fastopen_cookie *foc);
++void tcp_v4_send_reset(struct sock *sk, struct sk_buff *skb);
++struct ip_options_rcu *tcp_v4_save_options(struct sk_buff *skb);
++struct sock *tcp_v4_hnd_req(struct sock *sk, struct sk_buff *skb);
++void tcp_v4_reqsk_destructor(struct request_sock *req);
++
++int tcp_v6_rtx_synack(struct sock *sk, struct request_sock *req);
++void tcp_v6_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
++			   struct request_sock *req);
++__u32 tcp_v6_init_sequence(const struct sk_buff *skb);
++int tcp_v6_send_synack(struct sock *sk, struct dst_entry *dst,
++		       struct flowi *fl, struct request_sock *req,
++		       u16 queue_mapping, struct tcp_fastopen_cookie *foc);
++void tcp_v6_send_reset(struct sock *sk, struct sk_buff *skb);
++int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb);
++int tcp_v6_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
++void tcp_v6_destroy_sock(struct sock *sk);
++void inet6_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb);
++void tcp_v6_hash(struct sock *sk);
++struct sock *tcp_v6_hnd_req(struct sock *sk,struct sk_buff *skb);
++struct sock *tcp_v6_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
++			          struct request_sock *req,
++				  struct dst_entry *dst);
++void tcp_v6_reqsk_destructor(struct request_sock *req);
++
++unsigned int tcp_xmit_size_goal(struct sock *sk, u32 mss_now,
++				       int large_allowed);
++u32 tcp_tso_acked(struct sock *sk, struct sk_buff *skb);
++
++void skb_clone_fraglist(struct sk_buff *skb);
++void copy_skb_header(struct sk_buff *new, const struct sk_buff *old);
++
++void inet_twsk_free(struct inet_timewait_sock *tw);
++int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb);
++/* These states need RST on ABORT according to RFC793 */
++static inline bool tcp_need_reset(int state)
++{
++	return (1 << state) &
++	       (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT | TCPF_FIN_WAIT1 |
++		TCPF_FIN_WAIT2 | TCPF_SYN_RECV);
++}
++
++bool tcp_dma_try_early_copy(struct sock *sk, struct sk_buff *skb,
++			    int hlen);
++int __must_check tcp_queue_rcv(struct sock *sk, struct sk_buff *skb, int hdrlen,
++			       bool *fragstolen);
++bool tcp_try_coalesce(struct sock *sk, struct sk_buff *to,
++		      struct sk_buff *from, bool *fragstolen);
++/**** END - Exports needed for MPTCP ****/
++
+ void tcp_tasklet_init(void);
+ 
+ void tcp_v4_err(struct sk_buff *skb, u32);
+@@ -440,6 +563,7 @@ int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
+ 		size_t len, int nonblock, int flags, int *addr_len);
+ void tcp_parse_options(const struct sk_buff *skb,
+ 		       struct tcp_options_received *opt_rx,
++		       struct mptcp_options_received *mopt_rx,
+ 		       int estab, struct tcp_fastopen_cookie *foc);
+ const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
+ 
+@@ -493,14 +617,8 @@ static inline u32 tcp_cookie_time(void)
+ 
+ u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th,
+ 			      u16 *mssp);
+-__u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb, __u16 *mss);
+-#else
+-static inline __u32 cookie_v4_init_sequence(struct sock *sk,
+-					    struct sk_buff *skb,
+-					    __u16 *mss)
+-{
+-	return 0;
+-}
++__u32 cookie_v4_init_sequence(struct sock *sk, const struct sk_buff *skb,
++			      __u16 *mss);
+ #endif
+ 
+ __u32 cookie_init_timestamp(struct request_sock *req);
+@@ -516,13 +634,6 @@ u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph,
+ 			      const struct tcphdr *th, u16 *mssp);
+ __u32 cookie_v6_init_sequence(struct sock *sk, const struct sk_buff *skb,
+ 			      __u16 *mss);
+-#else
+-static inline __u32 cookie_v6_init_sequence(struct sock *sk,
+-					    struct sk_buff *skb,
+-					    __u16 *mss)
+-{
+-	return 0;
+-}
+ #endif
+ /* tcp_output.c */
+ 
+@@ -551,10 +662,17 @@ void tcp_send_delayed_ack(struct sock *sk);
+ void tcp_send_loss_probe(struct sock *sk);
+ bool tcp_schedule_loss_probe(struct sock *sk);
+ 
++u16 tcp_select_window(struct sock *sk);
++bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle,
++		int push_one, gfp_t gfp);
++
+ /* tcp_input.c */
+ void tcp_resume_early_retransmit(struct sock *sk);
+ void tcp_rearm_rto(struct sock *sk);
+ void tcp_reset(struct sock *sk);
++void tcp_set_rto(struct sock *sk);
++bool tcp_should_expand_sndbuf(const struct sock *sk);
++bool tcp_prune_ofo_queue(struct sock *sk);
+ 
+ /* tcp_timer.c */
+ void tcp_init_xmit_timers(struct sock *);
+@@ -703,14 +821,27 @@ void tcp_send_window_probe(struct sock *sk);
+  */
+ struct tcp_skb_cb {
+ 	union {
+-		struct inet_skb_parm	h4;
++		union {
++			struct inet_skb_parm	h4;
+ #if IS_ENABLED(CONFIG_IPV6)
+-		struct inet6_skb_parm	h6;
++			struct inet6_skb_parm	h6;
+ #endif
+-	} header;	/* For incoming frames		*/
++		} header;	/* For incoming frames		*/
++#ifdef CONFIG_MPTCP
++		union {			/* For MPTCP outgoing frames */
++			__u32 path_mask; /* paths that tried to send this skb */
++			__u32 dss[6];	/* DSS options */
++		};
++#endif
++	};
+ 	__u32		seq;		/* Starting sequence number	*/
+ 	__u32		end_seq;	/* SEQ + FIN + SYN + datalen	*/
+ 	__u32		when;		/* used to compute rtt's	*/
++#ifdef CONFIG_MPTCP
++	__u8		mptcp_flags;	/* flags for the MPTCP layer    */
++	__u8		dss_off;	/* Number of 4-byte words until
++					 * seq-number */
++#endif
+ 	__u8		tcp_flags;	/* TCP header flags. (tcp[13])	*/
+ 
+ 	__u8		sacked;		/* State flags for SACK/FACK.	*/
+@@ -1075,7 +1206,8 @@ u32 tcp_default_init_rwnd(u32 mss);
+ /* Determine a window scaling and initial window to offer. */
+ void tcp_select_initial_window(int __space, __u32 mss, __u32 *rcv_wnd,
+ 			       __u32 *window_clamp, int wscale_ok,
+-			       __u8 *rcv_wscale, __u32 init_rcv_wnd);
++			       __u8 *rcv_wscale, __u32 init_rcv_wnd,
++			       const struct sock *sk);
+ 
+ static inline int tcp_win_from_space(int space)
+ {
+@@ -1084,15 +1216,34 @@ static inline int tcp_win_from_space(int space)
+ 		space - (space>>sysctl_tcp_adv_win_scale);
+ }
+ 
++#ifdef CONFIG_MPTCP
++extern struct static_key mptcp_static_key;
++static inline bool mptcp(const struct tcp_sock *tp)
++{
++	return static_key_false(&mptcp_static_key) && tp->mpc;
++}
++#else
++static inline bool mptcp(const struct tcp_sock *tp)
++{
++	return 0;
++}
++#endif
++
+ /* Note: caller must be prepared to deal with negative returns */ 
+ static inline int tcp_space(const struct sock *sk)
+ {
++	if (mptcp(tcp_sk(sk)))
++		sk = tcp_sk(sk)->meta_sk;
++
+ 	return tcp_win_from_space(sk->sk_rcvbuf -
+ 				  atomic_read(&sk->sk_rmem_alloc));
+ } 
+ 
+ static inline int tcp_full_space(const struct sock *sk)
+ {
++	if (mptcp(tcp_sk(sk)))
++		sk = tcp_sk(sk)->meta_sk;
++
+ 	return tcp_win_from_space(sk->sk_rcvbuf); 
+ }
+ 
+@@ -1115,6 +1266,8 @@ static inline void tcp_openreq_init(struct request_sock *req,
+ 	ireq->wscale_ok = rx_opt->wscale_ok;
+ 	ireq->acked = 0;
+ 	ireq->ecn_ok = 0;
++	ireq->mptcp_rqsk = 0;
++	ireq->saw_mpc = 0;
+ 	ireq->ir_rmt_port = tcp_hdr(skb)->source;
+ 	ireq->ir_num = ntohs(tcp_hdr(skb)->dest);
+ }
+@@ -1585,6 +1738,11 @@ int tcp4_proc_init(void);
+ void tcp4_proc_exit(void);
+ #endif
+ 
++int tcp_rtx_synack(struct sock *sk, struct request_sock *req);
++int tcp_conn_request(struct request_sock_ops *rsk_ops,
++		     const struct tcp_request_sock_ops *af_ops,
++		     struct sock *sk, struct sk_buff *skb);
++
+ /* TCP af-specific functions */
+ struct tcp_sock_af_ops {
+ #ifdef CONFIG_TCP_MD5SIG
+@@ -1601,7 +1759,32 @@ struct tcp_sock_af_ops {
+ #endif
+ };
+ 
++/* TCP/MPTCP-specific functions */
++struct tcp_sock_ops {
++	u32 (*__select_window)(struct sock *sk);
++	u16 (*select_window)(struct sock *sk);
++	void (*select_initial_window)(int __space, __u32 mss, __u32 *rcv_wnd,
++				      __u32 *window_clamp, int wscale_ok,
++				      __u8 *rcv_wscale, __u32 init_rcv_wnd,
++				      const struct sock *sk);
++	void (*init_buffer_space)(struct sock *sk);
++	void (*set_rto)(struct sock *sk);
++	bool (*should_expand_sndbuf)(const struct sock *sk);
++	void (*send_fin)(struct sock *sk);
++	bool (*write_xmit)(struct sock *sk, unsigned int mss_now, int nonagle,
++			   int push_one, gfp_t gfp);
++	void (*send_active_reset)(struct sock *sk, gfp_t priority);
++	int (*write_wakeup)(struct sock *sk);
++	bool (*prune_ofo_queue)(struct sock *sk);
++	void (*retransmit_timer)(struct sock *sk);
++	void (*time_wait)(struct sock *sk, int state, int timeo);
++	void (*cleanup_rbuf)(struct sock *sk, int copied);
++	void (*init_congestion_control)(struct sock *sk);
++};
++extern const struct tcp_sock_ops tcp_specific;
++
+ struct tcp_request_sock_ops {
++	u16 mss_clamp;
+ #ifdef CONFIG_TCP_MD5SIG
+ 	struct tcp_md5sig_key	*(*md5_lookup) (struct sock *sk,
+ 						struct request_sock *req);
+@@ -1611,8 +1794,39 @@ struct tcp_request_sock_ops {
+ 						  const struct request_sock *req,
+ 						  const struct sk_buff *skb);
+ #endif
++	int (*init_req)(struct request_sock *req, struct sock *sk,
++			 struct sk_buff *skb);
++#ifdef CONFIG_SYN_COOKIES
++	__u32 (*cookie_init_seq)(struct sock *sk, const struct sk_buff *skb,
++				 __u16 *mss);
++#endif
++	struct dst_entry *(*route_req)(struct sock *sk, struct flowi *fl,
++				       const struct request_sock *req,
++				       bool *strict);
++	__u32 (*init_seq)(const struct sk_buff *skb);
++	int (*send_synack)(struct sock *sk, struct dst_entry *dst,
++			   struct flowi *fl, struct request_sock *req,
++			   u16 queue_mapping, struct tcp_fastopen_cookie *foc);
++	void (*queue_hash_add)(struct sock *sk, struct request_sock *req,
++			       const unsigned long timeout);
+ };
+ 
++#ifdef CONFIG_SYN_COOKIES
++static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
++					 struct sock *sk, struct sk_buff *skb,
++					 __u16 *mss)
++{
++	return ops->cookie_init_seq(sk, skb, mss);
++}
++#else
++static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
++					 struct sock *sk, struct sk_buff *skb,
++					 __u16 *mss)
++{
++	return 0;
++}
++#endif
++
+ int tcpv4_offload_init(void);
+ 
+ void tcp_v4_init(void);
+diff --git a/include/uapi/linux/if.h b/include/uapi/linux/if.h
+index 9cf2394f0bcf..c2634b6ed854 100644
+--- a/include/uapi/linux/if.h
++++ b/include/uapi/linux/if.h
+@@ -109,6 +109,9 @@ enum net_device_flags {
+ #define IFF_DORMANT			IFF_DORMANT
+ #define IFF_ECHO			IFF_ECHO
+ 
++#define IFF_NOMULTIPATH	0x80000		/* Disable for MPTCP 		*/
++#define IFF_MPBACKUP	0x100000	/* Use as backup path for MPTCP */
++
+ #define IFF_VOLATILE	(IFF_LOOPBACK|IFF_POINTOPOINT|IFF_BROADCAST|IFF_ECHO|\
+ 		IFF_MASTER|IFF_SLAVE|IFF_RUNNING|IFF_LOWER_UP|IFF_DORMANT)
+ 
+diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
+index 3b9718328d8b..487475681d84 100644
+--- a/include/uapi/linux/tcp.h
++++ b/include/uapi/linux/tcp.h
+@@ -112,6 +112,7 @@ enum {
+ #define TCP_FASTOPEN		23	/* Enable FastOpen on listeners */
+ #define TCP_TIMESTAMP		24
+ #define TCP_NOTSENT_LOWAT	25	/* limit number of unsent bytes in write queue */
++#define MPTCP_ENABLED		26
+ 
+ struct tcp_repair_opt {
+ 	__u32	opt_code;
+diff --git a/net/Kconfig b/net/Kconfig
+index d92afe4204d9..96b58593ad5e 100644
+--- a/net/Kconfig
++++ b/net/Kconfig
+@@ -79,6 +79,7 @@ if INET
+ source "net/ipv4/Kconfig"
+ source "net/ipv6/Kconfig"
+ source "net/netlabel/Kconfig"
++source "net/mptcp/Kconfig"
+ 
+ endif # if INET
+ 
+diff --git a/net/Makefile b/net/Makefile
+index cbbbe6d657ca..244bac1435b1 100644
+--- a/net/Makefile
++++ b/net/Makefile
+@@ -20,6 +20,7 @@ obj-$(CONFIG_INET)		+= ipv4/
+ obj-$(CONFIG_XFRM)		+= xfrm/
+ obj-$(CONFIG_UNIX)		+= unix/
+ obj-$(CONFIG_NET)		+= ipv6/
++obj-$(CONFIG_MPTCP)		+= mptcp/
+ obj-$(CONFIG_PACKET)		+= packet/
+ obj-$(CONFIG_NET_KEY)		+= key/
+ obj-$(CONFIG_BRIDGE)		+= bridge/
+diff --git a/net/core/dev.c b/net/core/dev.c
+index 367a586d0c8a..215d2757fbf6 100644
+--- a/net/core/dev.c
++++ b/net/core/dev.c
+@@ -5420,7 +5420,7 @@ int __dev_change_flags(struct net_device *dev, unsigned int flags)
+ 
+ 	dev->flags = (flags & (IFF_DEBUG | IFF_NOTRAILERS | IFF_NOARP |
+ 			       IFF_DYNAMIC | IFF_MULTICAST | IFF_PORTSEL |
+-			       IFF_AUTOMEDIA)) |
++			       IFF_AUTOMEDIA | IFF_NOMULTIPATH | IFF_MPBACKUP)) |
+ 		     (dev->flags & (IFF_UP | IFF_VOLATILE | IFF_PROMISC |
+ 				    IFF_ALLMULTI));
+ 
+diff --git a/net/core/request_sock.c b/net/core/request_sock.c
+index 467f326126e0..909dfa13f499 100644
+--- a/net/core/request_sock.c
++++ b/net/core/request_sock.c
+@@ -38,7 +38,8 @@ int sysctl_max_syn_backlog = 256;
+ EXPORT_SYMBOL(sysctl_max_syn_backlog);
+ 
+ int reqsk_queue_alloc(struct request_sock_queue *queue,
+-		      unsigned int nr_table_entries)
++		      unsigned int nr_table_entries,
++		      gfp_t flags)
+ {
+ 	size_t lopt_size = sizeof(struct listen_sock);
+ 	struct listen_sock *lopt;
+@@ -48,9 +49,11 @@ int reqsk_queue_alloc(struct request_sock_queue *queue,
+ 	nr_table_entries = roundup_pow_of_two(nr_table_entries + 1);
+ 	lopt_size += nr_table_entries * sizeof(struct request_sock *);
+ 	if (lopt_size > PAGE_SIZE)
+-		lopt = vzalloc(lopt_size);
++		lopt = __vmalloc(lopt_size,
++			flags | __GFP_HIGHMEM | __GFP_ZERO,
++			PAGE_KERNEL);
+ 	else
+-		lopt = kzalloc(lopt_size, GFP_KERNEL);
++		lopt = kzalloc(lopt_size, flags);
+ 	if (lopt == NULL)
+ 		return -ENOMEM;
+ 
+diff --git a/net/core/skbuff.c b/net/core/skbuff.c
+index c1a33033cbe2..8abc5d60fbe3 100644
+--- a/net/core/skbuff.c
++++ b/net/core/skbuff.c
+@@ -472,7 +472,7 @@ static inline void skb_drop_fraglist(struct sk_buff *skb)
+ 	skb_drop_list(&skb_shinfo(skb)->frag_list);
+ }
+ 
+-static void skb_clone_fraglist(struct sk_buff *skb)
++void skb_clone_fraglist(struct sk_buff *skb)
+ {
+ 	struct sk_buff *list;
+ 
+@@ -897,7 +897,7 @@ static void skb_headers_offset_update(struct sk_buff *skb, int off)
+ 	skb->inner_mac_header += off;
+ }
+ 
+-static void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
++void copy_skb_header(struct sk_buff *new, const struct sk_buff *old)
+ {
+ 	__copy_skb_header(new, old);
+ 
+diff --git a/net/core/sock.c b/net/core/sock.c
+index 026e01f70274..359295523177 100644
+--- a/net/core/sock.c
++++ b/net/core/sock.c
+@@ -136,6 +136,11 @@
+ 
+ #include <trace/events/sock.h>
+ 
++#ifdef CONFIG_MPTCP
++#include <net/mptcp.h>
++#include <net/inet_common.h>
++#endif
++
+ #ifdef CONFIG_INET
+ #include <net/tcp.h>
+ #endif
+@@ -280,7 +285,7 @@ static const char *const af_family_slock_key_strings[AF_MAX+1] = {
+   "slock-AF_IEEE802154", "slock-AF_CAIF" , "slock-AF_ALG"      ,
+   "slock-AF_NFC"   , "slock-AF_VSOCK"    ,"slock-AF_MAX"
+ };
+-static const char *const af_family_clock_key_strings[AF_MAX+1] = {
++char *const af_family_clock_key_strings[AF_MAX+1] = {
+   "clock-AF_UNSPEC", "clock-AF_UNIX"     , "clock-AF_INET"     ,
+   "clock-AF_AX25"  , "clock-AF_IPX"      , "clock-AF_APPLETALK",
+   "clock-AF_NETROM", "clock-AF_BRIDGE"   , "clock-AF_ATMPVC"   ,
+@@ -301,7 +306,7 @@ static const char *const af_family_clock_key_strings[AF_MAX+1] = {
+  * sk_callback_lock locking rules are per-address-family,
+  * so split the lock classes by using a per-AF key:
+  */
+-static struct lock_class_key af_callback_keys[AF_MAX];
++struct lock_class_key af_callback_keys[AF_MAX];
+ 
+ /* Take into consideration the size of the struct sk_buff overhead in the
+  * determination of these values, since that is non-constant across
+@@ -422,8 +427,6 @@ static void sock_warn_obsolete_bsdism(const char *name)
+ 	}
+ }
+ 
+-#define SK_FLAGS_TIMESTAMP ((1UL << SOCK_TIMESTAMP) | (1UL << SOCK_TIMESTAMPING_RX_SOFTWARE))
+-
+ static void sock_disable_timestamp(struct sock *sk, unsigned long flags)
+ {
+ 	if (sk->sk_flags & flags) {
+@@ -1253,8 +1256,25 @@ lenout:
+  *
+  * (We also register the sk_lock with the lock validator.)
+  */
+-static inline void sock_lock_init(struct sock *sk)
+-{
++void sock_lock_init(struct sock *sk)
++{
++#ifdef CONFIG_MPTCP
++	/* Reclassify the lock-class for subflows */
++	if (sk->sk_type == SOCK_STREAM && sk->sk_protocol == IPPROTO_TCP)
++		if (mptcp(tcp_sk(sk)) || tcp_sk(sk)->is_master_sk) {
++			sock_lock_init_class_and_name(sk, "slock-AF_INET-MPTCP",
++						      &meta_slock_key,
++						      "sk_lock-AF_INET-MPTCP",
++						      &meta_key);
++
++			/* We don't yet have the mptcp-point.
++			 * Thus we still need inet_sock_destruct
++			 */
++			sk->sk_destruct = inet_sock_destruct;
++			return;
++		}
++#endif
++
+ 	sock_lock_init_class_and_name(sk,
+ 			af_family_slock_key_strings[sk->sk_family],
+ 			af_family_slock_keys + sk->sk_family,
+@@ -1301,7 +1321,7 @@ void sk_prot_clear_portaddr_nulls(struct sock *sk, int size)
+ }
+ EXPORT_SYMBOL(sk_prot_clear_portaddr_nulls);
+ 
+-static struct sock *sk_prot_alloc(struct proto *prot, gfp_t priority,
++struct sock *sk_prot_alloc(struct proto *prot, gfp_t priority,
+ 		int family)
+ {
+ 	struct sock *sk;
+diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c
+index 4db3c2a1679c..04cb17d4b0ce 100644
+--- a/net/dccp/ipv6.c
++++ b/net/dccp/ipv6.c
+@@ -386,7 +386,7 @@ static int dccp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
+ 	if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
+ 		goto drop;
+ 
+-	req = inet6_reqsk_alloc(&dccp6_request_sock_ops);
++	req = inet_reqsk_alloc(&dccp6_request_sock_ops);
+ 	if (req == NULL)
+ 		goto drop;
+ 
+diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig
+index 05c57f0fcabe..630434db0085 100644
+--- a/net/ipv4/Kconfig
++++ b/net/ipv4/Kconfig
+@@ -556,6 +556,30 @@ config TCP_CONG_ILLINOIS
+ 	For further details see:
+ 	  http://www.ews.uiuc.edu/~shaoliu/tcpillinois/index.html
+ 
++config TCP_CONG_COUPLED
++	tristate "MPTCP COUPLED CONGESTION CONTROL"
++	depends on MPTCP
++	default n
++	---help---
++	MultiPath TCP Coupled Congestion Control
++	To enable it, just put 'coupled' in tcp_congestion_control
++
++config TCP_CONG_OLIA
++	tristate "MPTCP Opportunistic Linked Increase"
++	depends on MPTCP
++	default n
++	---help---
++	MultiPath TCP Opportunistic Linked Increase Congestion Control
++	To enable it, just put 'olia' in tcp_congestion_control
++
++config TCP_CONG_WVEGAS
++	tristate "MPTCP WVEGAS CONGESTION CONTROL"
++	depends on MPTCP
++	default n
++	---help---
++	wVegas congestion control for MPTCP
++	To enable it, just put 'wvegas' in tcp_congestion_control
++
+ choice
+ 	prompt "Default TCP congestion control"
+ 	default DEFAULT_CUBIC
+@@ -584,6 +608,15 @@ choice
+ 	config DEFAULT_WESTWOOD
+ 		bool "Westwood" if TCP_CONG_WESTWOOD=y
+ 
++	config DEFAULT_COUPLED
++		bool "Coupled" if TCP_CONG_COUPLED=y
++
++	config DEFAULT_OLIA
++		bool "Olia" if TCP_CONG_OLIA=y
++
++	config DEFAULT_WVEGAS
++		bool "Wvegas" if TCP_CONG_WVEGAS=y
++
+ 	config DEFAULT_RENO
+ 		bool "Reno"
+ 
+@@ -605,6 +638,8 @@ config DEFAULT_TCP_CONG
+ 	default "vegas" if DEFAULT_VEGAS
+ 	default "westwood" if DEFAULT_WESTWOOD
+ 	default "veno" if DEFAULT_VENO
++	default "coupled" if DEFAULT_COUPLED
++	default "wvegas" if DEFAULT_WVEGAS
+ 	default "reno" if DEFAULT_RENO
+ 	default "cubic"
+ 
+diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
+index d156b3c5f363..4afd6d8d9028 100644
+--- a/net/ipv4/af_inet.c
++++ b/net/ipv4/af_inet.c
+@@ -104,6 +104,7 @@
+ #include <net/ip_fib.h>
+ #include <net/inet_connection_sock.h>
+ #include <net/tcp.h>
++#include <net/mptcp.h>
+ #include <net/udp.h>
+ #include <net/udplite.h>
+ #include <net/ping.h>
+@@ -246,8 +247,7 @@ EXPORT_SYMBOL(inet_listen);
+  *	Create an inet socket.
+  */
+ 
+-static int inet_create(struct net *net, struct socket *sock, int protocol,
+-		       int kern)
++int inet_create(struct net *net, struct socket *sock, int protocol, int kern)
+ {
+ 	struct sock *sk;
+ 	struct inet_protosw *answer;
+@@ -676,6 +676,23 @@ int inet_accept(struct socket *sock, struct socket *newsock, int flags)
+ 	lock_sock(sk2);
+ 
+ 	sock_rps_record_flow(sk2);
++
++	if (sk2->sk_protocol == IPPROTO_TCP && mptcp(tcp_sk(sk2))) {
++		struct sock *sk_it = sk2;
++
++		mptcp_for_each_sk(tcp_sk(sk2)->mpcb, sk_it)
++			sock_rps_record_flow(sk_it);
++
++		if (tcp_sk(sk2)->mpcb->master_sk) {
++			sk_it = tcp_sk(sk2)->mpcb->master_sk;
++
++			write_lock_bh(&sk_it->sk_callback_lock);
++			sk_it->sk_wq = newsock->wq;
++			sk_it->sk_socket = newsock;
++			write_unlock_bh(&sk_it->sk_callback_lock);
++		}
++	}
++
+ 	WARN_ON(!((1 << sk2->sk_state) &
+ 		  (TCPF_ESTABLISHED | TCPF_SYN_RECV |
+ 		  TCPF_CLOSE_WAIT | TCPF_CLOSE)));
+@@ -1763,6 +1780,9 @@ static int __init inet_init(void)
+ 
+ 	ip_init();
+ 
++	/* We must initialize MPTCP before TCP. */
++	mptcp_init();
++
+ 	tcp_v4_init();
+ 
+ 	/* Setup TCP slab cache for open requests. */
+diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
+index 14d02ea905b6..7d734d8af19b 100644
+--- a/net/ipv4/inet_connection_sock.c
++++ b/net/ipv4/inet_connection_sock.c
+@@ -23,6 +23,7 @@
+ #include <net/route.h>
+ #include <net/tcp_states.h>
+ #include <net/xfrm.h>
++#include <net/mptcp.h>
+ 
+ #ifdef INET_CSK_DEBUG
+ const char inet_csk_timer_bug_msg[] = "inet_csk BUG: unknown timer value\n";
+@@ -465,8 +466,8 @@ no_route:
+ }
+ EXPORT_SYMBOL_GPL(inet_csk_route_child_sock);
+ 
+-static inline u32 inet_synq_hash(const __be32 raddr, const __be16 rport,
+-				 const u32 rnd, const u32 synq_hsize)
++u32 inet_synq_hash(const __be32 raddr, const __be16 rport, const u32 rnd,
++		   const u32 synq_hsize)
+ {
+ 	return jhash_2words((__force u32)raddr, (__force u32)rport, rnd) & (synq_hsize - 1);
+ }
+@@ -647,7 +648,7 @@ void inet_csk_reqsk_queue_prune(struct sock *parent,
+ 
+ 	lopt->clock_hand = i;
+ 
+-	if (lopt->qlen)
++	if (lopt->qlen && !is_meta_sk(parent))
+ 		inet_csk_reset_keepalive_timer(parent, interval);
+ }
+ EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_prune);
+@@ -664,7 +665,9 @@ struct sock *inet_csk_clone_lock(const struct sock *sk,
+ 				 const struct request_sock *req,
+ 				 const gfp_t priority)
+ {
+-	struct sock *newsk = sk_clone_lock(sk, priority);
++	struct sock *newsk;
++
++	newsk = sk_clone_lock(sk, priority);
+ 
+ 	if (newsk != NULL) {
+ 		struct inet_connection_sock *newicsk = inet_csk(newsk);
+@@ -743,7 +746,8 @@ int inet_csk_listen_start(struct sock *sk, const int nr_table_entries)
+ {
+ 	struct inet_sock *inet = inet_sk(sk);
+ 	struct inet_connection_sock *icsk = inet_csk(sk);
+-	int rc = reqsk_queue_alloc(&icsk->icsk_accept_queue, nr_table_entries);
++	int rc = reqsk_queue_alloc(&icsk->icsk_accept_queue, nr_table_entries,
++				   GFP_KERNEL);
+ 
+ 	if (rc != 0)
+ 		return rc;
+@@ -801,9 +805,14 @@ void inet_csk_listen_stop(struct sock *sk)
+ 
+ 	while ((req = acc_req) != NULL) {
+ 		struct sock *child = req->sk;
++		bool mutex_taken = false;
+ 
+ 		acc_req = req->dl_next;
+ 
++		if (is_meta_sk(child)) {
++			mutex_lock(&tcp_sk(child)->mpcb->mpcb_mutex);
++			mutex_taken = true;
++		}
+ 		local_bh_disable();
+ 		bh_lock_sock(child);
+ 		WARN_ON(sock_owned_by_user(child));
+@@ -832,6 +841,8 @@ void inet_csk_listen_stop(struct sock *sk)
+ 
+ 		bh_unlock_sock(child);
+ 		local_bh_enable();
++		if (mutex_taken)
++			mutex_unlock(&tcp_sk(child)->mpcb->mpcb_mutex);
+ 		sock_put(child);
+ 
+ 		sk_acceptq_removed(sk);
+diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
+index c86624b36a62..0ff3fe004d62 100644
+--- a/net/ipv4/syncookies.c
++++ b/net/ipv4/syncookies.c
+@@ -170,7 +170,8 @@ u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th,
+ }
+ EXPORT_SYMBOL_GPL(__cookie_v4_init_sequence);
+ 
+-__u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb, __u16 *mssp)
++__u32 cookie_v4_init_sequence(struct sock *sk, const struct sk_buff *skb,
++			      __u16 *mssp)
+ {
+ 	const struct iphdr *iph = ip_hdr(skb);
+ 	const struct tcphdr *th = tcp_hdr(skb);
+@@ -284,7 +285,7 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
+ 
+ 	/* check for timestamp cookie support */
+ 	memset(&tcp_opt, 0, sizeof(tcp_opt));
+-	tcp_parse_options(skb, &tcp_opt, 0, NULL);
++	tcp_parse_options(skb, &tcp_opt, NULL, 0, NULL);
+ 
+ 	if (!cookie_check_timestamp(&tcp_opt, sock_net(sk), &ecn_ok))
+ 		goto out;
+@@ -355,10 +356,10 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
+ 	/* Try to redo what tcp_v4_send_synack did. */
+ 	req->window_clamp = tp->window_clamp ? :dst_metric(&rt->dst, RTAX_WINDOW);
+ 
+-	tcp_select_initial_window(tcp_full_space(sk), req->mss,
+-				  &req->rcv_wnd, &req->window_clamp,
+-				  ireq->wscale_ok, &rcv_wscale,
+-				  dst_metric(&rt->dst, RTAX_INITRWND));
++	tp->ops->select_initial_window(tcp_full_space(sk), req->mss,
++				       &req->rcv_wnd, &req->window_clamp,
++				       ireq->wscale_ok, &rcv_wscale,
++				       dst_metric(&rt->dst, RTAX_INITRWND), sk);
+ 
+ 	ireq->rcv_wscale  = rcv_wscale;
+ 
+diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
+index 9d2118e5fbc7..2cb89f886d45 100644
+--- a/net/ipv4/tcp.c
++++ b/net/ipv4/tcp.c
+@@ -271,6 +271,7 @@
+ 
+ #include <net/icmp.h>
+ #include <net/inet_common.h>
++#include <net/mptcp.h>
+ #include <net/tcp.h>
+ #include <net/xfrm.h>
+ #include <net/ip.h>
+@@ -371,6 +372,24 @@ static int retrans_to_secs(u8 retrans, int timeout, int rto_max)
+ 	return period;
+ }
+ 
++const struct tcp_sock_ops tcp_specific = {
++	.__select_window		= __tcp_select_window,
++	.select_window			= tcp_select_window,
++	.select_initial_window		= tcp_select_initial_window,
++	.init_buffer_space		= tcp_init_buffer_space,
++	.set_rto			= tcp_set_rto,
++	.should_expand_sndbuf		= tcp_should_expand_sndbuf,
++	.init_congestion_control	= tcp_init_congestion_control,
++	.send_fin			= tcp_send_fin,
++	.write_xmit			= tcp_write_xmit,
++	.send_active_reset		= tcp_send_active_reset,
++	.write_wakeup			= tcp_write_wakeup,
++	.prune_ofo_queue		= tcp_prune_ofo_queue,
++	.retransmit_timer		= tcp_retransmit_timer,
++	.time_wait			= tcp_time_wait,
++	.cleanup_rbuf			= tcp_cleanup_rbuf,
++};
++
+ /* Address-family independent initialization for a tcp_sock.
+  *
+  * NOTE: A lot of things set to zero explicitly by call to
+@@ -419,6 +438,8 @@ void tcp_init_sock(struct sock *sk)
+ 	sk->sk_sndbuf = sysctl_tcp_wmem[1];
+ 	sk->sk_rcvbuf = sysctl_tcp_rmem[1];
+ 
++	tp->ops = &tcp_specific;
++
+ 	local_bh_disable();
+ 	sock_update_memcg(sk);
+ 	sk_sockets_allocated_inc(sk);
+@@ -726,6 +747,14 @@ ssize_t tcp_splice_read(struct socket *sock, loff_t *ppos,
+ 	int ret;
+ 
+ 	sock_rps_record_flow(sk);
++
++#ifdef CONFIG_MPTCP
++	if (mptcp(tcp_sk(sk))) {
++		struct sock *sk_it;
++		mptcp_for_each_sk(tcp_sk(sk)->mpcb, sk_it)
++			sock_rps_record_flow(sk_it);
++	}
++#endif
+ 	/*
+ 	 * We can't seek on a socket input
+ 	 */
+@@ -821,8 +850,7 @@ struct sk_buff *sk_stream_alloc_skb(struct sock *sk, int size, gfp_t gfp)
+ 	return NULL;
+ }
+ 
+-static unsigned int tcp_xmit_size_goal(struct sock *sk, u32 mss_now,
+-				       int large_allowed)
++unsigned int tcp_xmit_size_goal(struct sock *sk, u32 mss_now, int large_allowed)
+ {
+ 	struct tcp_sock *tp = tcp_sk(sk);
+ 	u32 xmit_size_goal, old_size_goal;
+@@ -872,8 +900,13 @@ static int tcp_send_mss(struct sock *sk, int *size_goal, int flags)
+ {
+ 	int mss_now;
+ 
+-	mss_now = tcp_current_mss(sk);
+-	*size_goal = tcp_xmit_size_goal(sk, mss_now, !(flags & MSG_OOB));
++	if (mptcp(tcp_sk(sk))) {
++		mss_now = mptcp_current_mss(sk);
++		*size_goal = mptcp_xmit_size_goal(sk, mss_now, !(flags & MSG_OOB));
++	} else {
++		mss_now = tcp_current_mss(sk);
++		*size_goal = tcp_xmit_size_goal(sk, mss_now, !(flags & MSG_OOB));
++	}
+ 
+ 	return mss_now;
+ }
+@@ -892,11 +925,32 @@ static ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset,
+ 	 * is fully established.
+ 	 */
+ 	if (((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) &&
+-	    !tcp_passive_fastopen(sk)) {
++	    !tcp_passive_fastopen(mptcp(tp) && tp->mpcb->master_sk ?
++				  tp->mpcb->master_sk : sk)) {
+ 		if ((err = sk_stream_wait_connect(sk, &timeo)) != 0)
+ 			goto out_err;
+ 	}
+ 
++	if (mptcp(tp)) {
++		struct sock *sk_it = sk;
++
++		/* We must check this with socket-lock hold because we iterate
++		 * over the subflows.
++		 */
++		if (!mptcp_can_sendpage(sk)) {
++			ssize_t ret;
++
++			release_sock(sk);
++			ret = sock_no_sendpage(sk->sk_socket, page, offset,
++					       size, flags);
++			lock_sock(sk);
++			return ret;
++		}
++
++		mptcp_for_each_sk(tp->mpcb, sk_it)
++			sock_rps_record_flow(sk_it);
++	}
++
+ 	clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
+ 
+ 	mss_now = tcp_send_mss(sk, &size_goal, flags);
+@@ -1001,8 +1055,9 @@ int tcp_sendpage(struct sock *sk, struct page *page, int offset,
+ {
+ 	ssize_t res;
+ 
+-	if (!(sk->sk_route_caps & NETIF_F_SG) ||
+-	    !(sk->sk_route_caps & NETIF_F_ALL_CSUM))
++	/* If MPTCP is enabled, we check it later after establishment */
++	if (!mptcp(tcp_sk(sk)) && (!(sk->sk_route_caps & NETIF_F_SG) ||
++	    !(sk->sk_route_caps & NETIF_F_ALL_CSUM)))
+ 		return sock_no_sendpage(sk->sk_socket, page, offset, size,
+ 					flags);
+ 
+@@ -1018,6 +1073,9 @@ static inline int select_size(const struct sock *sk, bool sg)
+ 	const struct tcp_sock *tp = tcp_sk(sk);
+ 	int tmp = tp->mss_cache;
+ 
++	if (mptcp(tp))
++		return mptcp_select_size(sk, sg);
++
+ 	if (sg) {
+ 		if (sk_can_gso(sk)) {
+ 			/* Small frames wont use a full page:
+@@ -1100,11 +1158,18 @@ int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
+ 	 * is fully established.
+ 	 */
+ 	if (((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) &&
+-	    !tcp_passive_fastopen(sk)) {
++	    !tcp_passive_fastopen(mptcp(tp) && tp->mpcb->master_sk ?
++				  tp->mpcb->master_sk : sk)) {
+ 		if ((err = sk_stream_wait_connect(sk, &timeo)) != 0)
+ 			goto do_error;
+ 	}
+ 
++	if (mptcp(tp)) {
++		struct sock *sk_it = sk;
++		mptcp_for_each_sk(tp->mpcb, sk_it)
++			sock_rps_record_flow(sk_it);
++	}
++
+ 	if (unlikely(tp->repair)) {
+ 		if (tp->repair_queue == TCP_RECV_QUEUE) {
+ 			copied = tcp_send_rcvq(sk, msg, size);
+@@ -1132,7 +1197,10 @@ int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
+ 	if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
+ 		goto out_err;
+ 
+-	sg = !!(sk->sk_route_caps & NETIF_F_SG);
++	if (mptcp(tp))
++		sg = mptcp_can_sg(sk);
++	else
++		sg = !!(sk->sk_route_caps & NETIF_F_SG);
+ 
+ 	while (--iovlen >= 0) {
+ 		size_t seglen = iov->iov_len;
+@@ -1183,8 +1251,15 @@ new_segment:
+ 
+ 				/*
+ 				 * Check whether we can use HW checksum.
++				 *
++				 * If dss-csum is enabled, we do not do hw-csum.
++				 * In case of non-mptcp we check the
++				 * device-capabilities.
++				 * In case of mptcp, hw-csum's will be handled
++				 * later in mptcp_write_xmit.
+ 				 */
+-				if (sk->sk_route_caps & NETIF_F_ALL_CSUM)
++				if (((mptcp(tp) && !tp->mpcb->dss_csum) || !mptcp(tp)) &&
++				    (mptcp(tp) || sk->sk_route_caps & NETIF_F_ALL_CSUM))
+ 					skb->ip_summed = CHECKSUM_PARTIAL;
+ 
+ 				skb_entail(sk, skb);
+@@ -1422,7 +1497,7 @@ void tcp_cleanup_rbuf(struct sock *sk, int copied)
+ 
+ 		/* Optimize, __tcp_select_window() is not cheap. */
+ 		if (2*rcv_window_now <= tp->window_clamp) {
+-			__u32 new_window = __tcp_select_window(sk);
++			__u32 new_window = tp->ops->__select_window(sk);
+ 
+ 			/* Send ACK now, if this read freed lots of space
+ 			 * in our buffer. Certainly, new_window is new window.
+@@ -1587,7 +1662,7 @@ int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
+ 	/* Clean up data we have read: This will do ACK frames. */
+ 	if (copied > 0) {
+ 		tcp_recv_skb(sk, seq, &offset);
+-		tcp_cleanup_rbuf(sk, copied);
++		tp->ops->cleanup_rbuf(sk, copied);
+ 	}
+ 	return copied;
+ }
+@@ -1623,6 +1698,14 @@ int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
+ 
+ 	lock_sock(sk);
+ 
++#ifdef CONFIG_MPTCP
++	if (mptcp(tp)) {
++		struct sock *sk_it;
++		mptcp_for_each_sk(tp->mpcb, sk_it)
++			sock_rps_record_flow(sk_it);
++	}
++#endif
++
+ 	err = -ENOTCONN;
+ 	if (sk->sk_state == TCP_LISTEN)
+ 		goto out;
+@@ -1761,7 +1844,7 @@ int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
+ 			}
+ 		}
+ 
+-		tcp_cleanup_rbuf(sk, copied);
++		tp->ops->cleanup_rbuf(sk, copied);
+ 
+ 		if (!sysctl_tcp_low_latency && tp->ucopy.task == user_recv) {
+ 			/* Install new reader */
+@@ -1813,7 +1896,7 @@ int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
+ 			if (tp->rcv_wnd == 0 &&
+ 			    !skb_queue_empty(&sk->sk_async_wait_queue)) {
+ 				tcp_service_net_dma(sk, true);
+-				tcp_cleanup_rbuf(sk, copied);
++				tp->ops->cleanup_rbuf(sk, copied);
+ 			} else
+ 				dma_async_issue_pending(tp->ucopy.dma_chan);
+ 		}
+@@ -1993,7 +2076,7 @@ skip_copy:
+ 	 */
+ 
+ 	/* Clean up data we have read: This will do ACK frames. */
+-	tcp_cleanup_rbuf(sk, copied);
++	tp->ops->cleanup_rbuf(sk, copied);
+ 
+ 	release_sock(sk);
+ 	return copied;
+@@ -2070,7 +2153,7 @@ static const unsigned char new_state[16] = {
+   /* TCP_CLOSING	*/ TCP_CLOSING,
+ };
+ 
+-static int tcp_close_state(struct sock *sk)
++int tcp_close_state(struct sock *sk)
+ {
+ 	int next = (int)new_state[sk->sk_state];
+ 	int ns = next & TCP_STATE_MASK;
+@@ -2100,7 +2183,7 @@ void tcp_shutdown(struct sock *sk, int how)
+ 	     TCPF_SYN_RECV | TCPF_CLOSE_WAIT)) {
+ 		/* Clear out any half completed packets.  FIN if needed. */
+ 		if (tcp_close_state(sk))
+-			tcp_send_fin(sk);
++			tcp_sk(sk)->ops->send_fin(sk);
+ 	}
+ }
+ EXPORT_SYMBOL(tcp_shutdown);
+@@ -2125,6 +2208,11 @@ void tcp_close(struct sock *sk, long timeout)
+ 	int data_was_unread = 0;
+ 	int state;
+ 
++	if (is_meta_sk(sk)) {
++		mptcp_close(sk, timeout);
++		return;
++	}
++
+ 	lock_sock(sk);
+ 	sk->sk_shutdown = SHUTDOWN_MASK;
+ 
+@@ -2167,7 +2255,7 @@ void tcp_close(struct sock *sk, long timeout)
+ 		/* Unread data was tossed, zap the connection. */
+ 		NET_INC_STATS_USER(sock_net(sk), LINUX_MIB_TCPABORTONCLOSE);
+ 		tcp_set_state(sk, TCP_CLOSE);
+-		tcp_send_active_reset(sk, sk->sk_allocation);
++		tcp_sk(sk)->ops->send_active_reset(sk, sk->sk_allocation);
+ 	} else if (sock_flag(sk, SOCK_LINGER) && !sk->sk_lingertime) {
+ 		/* Check zero linger _after_ checking for unread data. */
+ 		sk->sk_prot->disconnect(sk, 0);
+@@ -2247,7 +2335,7 @@ adjudge_to_death:
+ 		struct tcp_sock *tp = tcp_sk(sk);
+ 		if (tp->linger2 < 0) {
+ 			tcp_set_state(sk, TCP_CLOSE);
+-			tcp_send_active_reset(sk, GFP_ATOMIC);
++			tp->ops->send_active_reset(sk, GFP_ATOMIC);
+ 			NET_INC_STATS_BH(sock_net(sk),
+ 					LINUX_MIB_TCPABORTONLINGER);
+ 		} else {
+@@ -2257,7 +2345,8 @@ adjudge_to_death:
+ 				inet_csk_reset_keepalive_timer(sk,
+ 						tmo - TCP_TIMEWAIT_LEN);
+ 			} else {
+-				tcp_time_wait(sk, TCP_FIN_WAIT2, tmo);
++				tcp_sk(sk)->ops->time_wait(sk, TCP_FIN_WAIT2,
++							   tmo);
+ 				goto out;
+ 			}
+ 		}
+@@ -2266,7 +2355,7 @@ adjudge_to_death:
+ 		sk_mem_reclaim(sk);
+ 		if (tcp_check_oom(sk, 0)) {
+ 			tcp_set_state(sk, TCP_CLOSE);
+-			tcp_send_active_reset(sk, GFP_ATOMIC);
++			tcp_sk(sk)->ops->send_active_reset(sk, GFP_ATOMIC);
+ 			NET_INC_STATS_BH(sock_net(sk),
+ 					LINUX_MIB_TCPABORTONMEMORY);
+ 		}
+@@ -2291,15 +2380,6 @@ out:
+ }
+ EXPORT_SYMBOL(tcp_close);
+ 
+-/* These states need RST on ABORT according to RFC793 */
+-
+-static inline bool tcp_need_reset(int state)
+-{
+-	return (1 << state) &
+-	       (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT | TCPF_FIN_WAIT1 |
+-		TCPF_FIN_WAIT2 | TCPF_SYN_RECV);
+-}
+-
+ int tcp_disconnect(struct sock *sk, int flags)
+ {
+ 	struct inet_sock *inet = inet_sk(sk);
+@@ -2322,7 +2402,7 @@ int tcp_disconnect(struct sock *sk, int flags)
+ 		/* The last check adjusts for discrepancy of Linux wrt. RFC
+ 		 * states
+ 		 */
+-		tcp_send_active_reset(sk, gfp_any());
++		tp->ops->send_active_reset(sk, gfp_any());
+ 		sk->sk_err = ECONNRESET;
+ 	} else if (old_state == TCP_SYN_SENT)
+ 		sk->sk_err = ECONNRESET;
+@@ -2340,6 +2420,13 @@ int tcp_disconnect(struct sock *sk, int flags)
+ 	if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
+ 		inet_reset_saddr(sk);
+ 
++	if (is_meta_sk(sk)) {
++		mptcp_disconnect(sk);
++	} else {
++		if (tp->inside_tk_table)
++			mptcp_hash_remove_bh(tp);
++	}
++
+ 	sk->sk_shutdown = 0;
+ 	sock_reset_flag(sk, SOCK_DONE);
+ 	tp->srtt_us = 0;
+@@ -2632,6 +2719,12 @@ static int do_tcp_setsockopt(struct sock *sk, int level,
+ 		break;
+ 
+ 	case TCP_DEFER_ACCEPT:
++		/* An established MPTCP-connection (mptcp(tp) only returns true
++		 * if the socket is established) should not use DEFER on new
++		 * subflows.
++		 */
++		if (mptcp(tp))
++			break;
+ 		/* Translate value in seconds to number of retransmits */
+ 		icsk->icsk_accept_queue.rskq_defer_accept =
+ 			secs_to_retrans(val, TCP_TIMEOUT_INIT / HZ,
+@@ -2659,7 +2752,7 @@ static int do_tcp_setsockopt(struct sock *sk, int level,
+ 			    (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT) &&
+ 			    inet_csk_ack_scheduled(sk)) {
+ 				icsk->icsk_ack.pending |= ICSK_ACK_PUSHED;
+-				tcp_cleanup_rbuf(sk, 1);
++				tp->ops->cleanup_rbuf(sk, 1);
+ 				if (!(val & 1))
+ 					icsk->icsk_ack.pingpong = 1;
+ 			}
+@@ -2699,6 +2792,18 @@ static int do_tcp_setsockopt(struct sock *sk, int level,
+ 		tp->notsent_lowat = val;
+ 		sk->sk_write_space(sk);
+ 		break;
++#ifdef CONFIG_MPTCP
++	case MPTCP_ENABLED:
++		if (sk->sk_state == TCP_CLOSE || sk->sk_state == TCP_LISTEN) {
++			if (val)
++				tp->mptcp_enabled = 1;
++			else
++				tp->mptcp_enabled = 0;
++		} else {
++			err = -EPERM;
++		}
++		break;
++#endif
+ 	default:
+ 		err = -ENOPROTOOPT;
+ 		break;
+@@ -2931,6 +3036,11 @@ static int do_tcp_getsockopt(struct sock *sk, int level,
+ 	case TCP_NOTSENT_LOWAT:
+ 		val = tp->notsent_lowat;
+ 		break;
++#ifdef CONFIG_MPTCP
++	case MPTCP_ENABLED:
++		val = tp->mptcp_enabled;
++		break;
++#endif
+ 	default:
+ 		return -ENOPROTOOPT;
+ 	}
+@@ -3120,8 +3230,11 @@ void tcp_done(struct sock *sk)
+ 	if (sk->sk_state == TCP_SYN_SENT || sk->sk_state == TCP_SYN_RECV)
+ 		TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_ATTEMPTFAILS);
+ 
++	WARN_ON(sk->sk_state == TCP_CLOSE);
+ 	tcp_set_state(sk, TCP_CLOSE);
++
+ 	tcp_clear_xmit_timers(sk);
++
+ 	if (req != NULL)
+ 		reqsk_fastopen_remove(sk, req, false);
+ 
+diff --git a/net/ipv4/tcp_fastopen.c b/net/ipv4/tcp_fastopen.c
+index 9771563ab564..5c230d96c4c1 100644
+--- a/net/ipv4/tcp_fastopen.c
++++ b/net/ipv4/tcp_fastopen.c
+@@ -7,6 +7,7 @@
+ #include <linux/rculist.h>
+ #include <net/inetpeer.h>
+ #include <net/tcp.h>
++#include <net/mptcp.h>
+ 
+ int sysctl_tcp_fastopen __read_mostly = TFO_CLIENT_ENABLE;
+ 
+@@ -133,7 +134,7 @@ static bool tcp_fastopen_create_child(struct sock *sk,
+ {
+ 	struct tcp_sock *tp;
+ 	struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
+-	struct sock *child;
++	struct sock *child, *meta_sk;
+ 
+ 	req->num_retrans = 0;
+ 	req->num_timeout = 0;
+@@ -176,13 +177,6 @@ static bool tcp_fastopen_create_child(struct sock *sk,
+ 	/* Add the child socket directly into the accept queue */
+ 	inet_csk_reqsk_queue_add(sk, req, child);
+ 
+-	/* Now finish processing the fastopen child socket. */
+-	inet_csk(child)->icsk_af_ops->rebuild_header(child);
+-	tcp_init_congestion_control(child);
+-	tcp_mtup_init(child);
+-	tcp_init_metrics(child);
+-	tcp_init_buffer_space(child);
+-
+ 	/* Queue the data carried in the SYN packet. We need to first
+ 	 * bump skb's refcnt because the caller will attempt to free it.
+ 	 *
+@@ -199,8 +193,24 @@ static bool tcp_fastopen_create_child(struct sock *sk,
+ 		tp->syn_data_acked = 1;
+ 	}
+ 	tcp_rsk(req)->rcv_nxt = tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
++
++	meta_sk = child;
++	if (!mptcp_check_req_fastopen(meta_sk, req)) {
++		child = tcp_sk(meta_sk)->mpcb->master_sk;
++		tp = tcp_sk(child);
++	}
++
++	/* Now finish processing the fastopen child socket. */
++	inet_csk(child)->icsk_af_ops->rebuild_header(child);
++	tp->ops->init_congestion_control(child);
++	tcp_mtup_init(child);
++	tcp_init_metrics(child);
++	tp->ops->init_buffer_space(child);
++
+ 	sk->sk_data_ready(sk);
+-	bh_unlock_sock(child);
++	if (mptcp(tcp_sk(child)))
++		bh_unlock_sock(child);
++	bh_unlock_sock(meta_sk);
+ 	sock_put(child);
+ 	WARN_ON(req->sk == NULL);
+ 	return true;
+diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
+index 40639c288dc2..3273bb69f387 100644
+--- a/net/ipv4/tcp_input.c
++++ b/net/ipv4/tcp_input.c
+@@ -74,6 +74,9 @@
+ #include <linux/ipsec.h>
+ #include <asm/unaligned.h>
+ #include <net/netdma.h>
++#include <net/mptcp.h>
++#include <net/mptcp_v4.h>
++#include <net/mptcp_v6.h>
+ 
+ int sysctl_tcp_timestamps __read_mostly = 1;
+ int sysctl_tcp_window_scaling __read_mostly = 1;
+@@ -99,25 +102,6 @@ int sysctl_tcp_thin_dupack __read_mostly;
+ int sysctl_tcp_moderate_rcvbuf __read_mostly = 1;
+ int sysctl_tcp_early_retrans __read_mostly = 3;
+ 
+-#define FLAG_DATA		0x01 /* Incoming frame contained data.		*/
+-#define FLAG_WIN_UPDATE		0x02 /* Incoming ACK was a window update.	*/
+-#define FLAG_DATA_ACKED		0x04 /* This ACK acknowledged new data.		*/
+-#define FLAG_RETRANS_DATA_ACKED	0x08 /* "" "" some of which was retransmitted.	*/
+-#define FLAG_SYN_ACKED		0x10 /* This ACK acknowledged SYN.		*/
+-#define FLAG_DATA_SACKED	0x20 /* New SACK.				*/
+-#define FLAG_ECE		0x40 /* ECE in this ACK				*/
+-#define FLAG_SLOWPATH		0x100 /* Do not skip RFC checks for window update.*/
+-#define FLAG_ORIG_SACK_ACKED	0x200 /* Never retransmitted data are (s)acked	*/
+-#define FLAG_SND_UNA_ADVANCED	0x400 /* Snd_una was changed (!= FLAG_DATA_ACKED) */
+-#define FLAG_DSACKING_ACK	0x800 /* SACK blocks contained D-SACK info */
+-#define FLAG_SACK_RENEGING	0x2000 /* snd_una advanced to a sacked seq */
+-#define FLAG_UPDATE_TS_RECENT	0x4000 /* tcp_replace_ts_recent() */
+-
+-#define FLAG_ACKED		(FLAG_DATA_ACKED|FLAG_SYN_ACKED)
+-#define FLAG_NOT_DUP		(FLAG_DATA|FLAG_WIN_UPDATE|FLAG_ACKED)
+-#define FLAG_CA_ALERT		(FLAG_DATA_SACKED|FLAG_ECE)
+-#define FLAG_FORWARD_PROGRESS	(FLAG_ACKED|FLAG_DATA_SACKED)
+-
+ #define TCP_REMNANT (TCP_FLAG_FIN|TCP_FLAG_URG|TCP_FLAG_SYN|TCP_FLAG_PSH)
+ #define TCP_HP_BITS (~(TCP_RESERVED_BITS|TCP_FLAG_PSH))
+ 
+@@ -181,7 +165,7 @@ static void tcp_incr_quickack(struct sock *sk)
+ 		icsk->icsk_ack.quick = min(quickacks, TCP_MAX_QUICKACKS);
+ }
+ 
+-static void tcp_enter_quickack_mode(struct sock *sk)
++void tcp_enter_quickack_mode(struct sock *sk)
+ {
+ 	struct inet_connection_sock *icsk = inet_csk(sk);
+ 	tcp_incr_quickack(sk);
+@@ -283,8 +267,12 @@ static void tcp_sndbuf_expand(struct sock *sk)
+ 	per_mss = roundup_pow_of_two(per_mss) +
+ 		  SKB_DATA_ALIGN(sizeof(struct sk_buff));
+ 
+-	nr_segs = max_t(u32, TCP_INIT_CWND, tp->snd_cwnd);
+-	nr_segs = max_t(u32, nr_segs, tp->reordering + 1);
++	if (mptcp(tp)) {
++		nr_segs = mptcp_check_snd_buf(tp);
++	} else {
++		nr_segs = max_t(u32, TCP_INIT_CWND, tp->snd_cwnd);
++		nr_segs = max_t(u32, nr_segs, tp->reordering + 1);
++	}
+ 
+ 	/* Fast Recovery (RFC 5681 3.2) :
+ 	 * Cubic needs 1.7 factor, rounded to 2 to include
+@@ -292,8 +280,16 @@ static void tcp_sndbuf_expand(struct sock *sk)
+ 	 */
+ 	sndmem = 2 * nr_segs * per_mss;
+ 
+-	if (sk->sk_sndbuf < sndmem)
++	/* MPTCP: after this sndmem is the new contribution of the
++	 * current subflow to the aggregated sndbuf */
++	if (sk->sk_sndbuf < sndmem) {
++		int old_sndbuf = sk->sk_sndbuf;
+ 		sk->sk_sndbuf = min(sndmem, sysctl_tcp_wmem[2]);
++		/* MPTCP: ok, the subflow sndbuf has grown, reflect
++		 * this in the aggregate buffer.*/
++		if (mptcp(tp) && old_sndbuf != sk->sk_sndbuf)
++			mptcp_update_sndbuf(tp);
++	}
+ }
+ 
+ /* 2. Tuning advertised window (window_clamp, rcv_ssthresh)
+@@ -342,10 +338,12 @@ static int __tcp_grow_window(const struct sock *sk, const struct sk_buff *skb)
+ static void tcp_grow_window(struct sock *sk, const struct sk_buff *skb)
+ {
+ 	struct tcp_sock *tp = tcp_sk(sk);
++	struct sock *meta_sk = mptcp(tp) ? mptcp_meta_sk(sk) : sk;
++	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
+ 
+ 	/* Check #1 */
+-	if (tp->rcv_ssthresh < tp->window_clamp &&
+-	    (int)tp->rcv_ssthresh < tcp_space(sk) &&
++	if (meta_tp->rcv_ssthresh < meta_tp->window_clamp &&
++	    (int)meta_tp->rcv_ssthresh < tcp_space(sk) &&
+ 	    !sk_under_memory_pressure(sk)) {
+ 		int incr;
+ 
+@@ -353,14 +351,14 @@ static void tcp_grow_window(struct sock *sk, const struct sk_buff *skb)
+ 		 * will fit to rcvbuf in future.
+ 		 */
+ 		if (tcp_win_from_space(skb->truesize) <= skb->len)
+-			incr = 2 * tp->advmss;
++			incr = 2 * meta_tp->advmss;
+ 		else
+-			incr = __tcp_grow_window(sk, skb);
++			incr = __tcp_grow_window(meta_sk, skb);
+ 
+ 		if (incr) {
+ 			incr = max_t(int, incr, 2 * skb->len);
+-			tp->rcv_ssthresh = min(tp->rcv_ssthresh + incr,
+-					       tp->window_clamp);
++			meta_tp->rcv_ssthresh = min(meta_tp->rcv_ssthresh + incr,
++					            meta_tp->window_clamp);
+ 			inet_csk(sk)->icsk_ack.quick |= 1;
+ 		}
+ 	}
+@@ -543,7 +541,10 @@ void tcp_rcv_space_adjust(struct sock *sk)
+ 	int copied;
+ 
+ 	time = tcp_time_stamp - tp->rcvq_space.time;
+-	if (time < (tp->rcv_rtt_est.rtt >> 3) || tp->rcv_rtt_est.rtt == 0)
++	if (mptcp(tp)) {
++		if (mptcp_check_rtt(tp, time))
++			return;
++	} else if (time < (tp->rcv_rtt_est.rtt >> 3) || tp->rcv_rtt_est.rtt == 0)
+ 		return;
+ 
+ 	/* Number of bytes copied to user in last RTT */
+@@ -761,7 +762,7 @@ static void tcp_update_pacing_rate(struct sock *sk)
+ /* Calculate rto without backoff.  This is the second half of Van Jacobson's
+  * routine referred to above.
+  */
+-static void tcp_set_rto(struct sock *sk)
++void tcp_set_rto(struct sock *sk)
+ {
+ 	const struct tcp_sock *tp = tcp_sk(sk);
+ 	/* Old crap is replaced with new one. 8)
+@@ -1376,7 +1377,11 @@ static struct sk_buff *tcp_shift_skb_data(struct sock *sk, struct sk_buff *skb,
+ 	int len;
+ 	int in_sack;
+ 
+-	if (!sk_can_gso(sk))
++	/* For MPTCP we cannot shift skb-data and remove one skb from the
++	 * send-queue, because this will make us loose the DSS-option (which
++	 * is stored in TCP_SKB_CB(skb)->dss) of the skb we are removing.
++	 */
++	if (!sk_can_gso(sk) || mptcp(tp))
+ 		goto fallback;
+ 
+ 	/* Normally R but no L won't result in plain S */
+@@ -2915,7 +2920,7 @@ static inline bool tcp_ack_update_rtt(struct sock *sk, const int flag,
+ 		return false;
+ 
+ 	tcp_rtt_estimator(sk, seq_rtt_us);
+-	tcp_set_rto(sk);
++	tp->ops->set_rto(sk);
+ 
+ 	/* RFC6298: only reset backoff on valid RTT measurement. */
+ 	inet_csk(sk)->icsk_backoff = 0;
+@@ -3000,7 +3005,7 @@ void tcp_resume_early_retransmit(struct sock *sk)
+ }
+ 
+ /* If we get here, the whole TSO packet has not been acked. */
+-static u32 tcp_tso_acked(struct sock *sk, struct sk_buff *skb)
++u32 tcp_tso_acked(struct sock *sk, struct sk_buff *skb)
+ {
+ 	struct tcp_sock *tp = tcp_sk(sk);
+ 	u32 packets_acked;
+@@ -3095,6 +3100,8 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets,
+ 		 */
+ 		if (!(scb->tcp_flags & TCPHDR_SYN)) {
+ 			flag |= FLAG_DATA_ACKED;
++			if (mptcp(tp) && mptcp_is_data_seq(skb))
++				flag |= MPTCP_FLAG_DATA_ACKED;
+ 		} else {
+ 			flag |= FLAG_SYN_ACKED;
+ 			tp->retrans_stamp = 0;
+@@ -3189,7 +3196,7 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets,
+ 	return flag;
+ }
+ 
+-static void tcp_ack_probe(struct sock *sk)
++void tcp_ack_probe(struct sock *sk)
+ {
+ 	const struct tcp_sock *tp = tcp_sk(sk);
+ 	struct inet_connection_sock *icsk = inet_csk(sk);
+@@ -3236,9 +3243,8 @@ static inline bool tcp_may_raise_cwnd(const struct sock *sk, const int flag)
+ /* Check that window update is acceptable.
+  * The function assumes that snd_una<=ack<=snd_next.
+  */
+-static inline bool tcp_may_update_window(const struct tcp_sock *tp,
+-					const u32 ack, const u32 ack_seq,
+-					const u32 nwin)
++bool tcp_may_update_window(const struct tcp_sock *tp, const u32 ack,
++			   const u32 ack_seq, const u32 nwin)
+ {
+ 	return	after(ack, tp->snd_una) ||
+ 		after(ack_seq, tp->snd_wl1) ||
+@@ -3357,7 +3363,7 @@ static void tcp_process_tlp_ack(struct sock *sk, u32 ack, int flag)
+ }
+ 
+ /* This routine deals with incoming acks, but not outgoing ones. */
+-static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
++static int tcp_ack(struct sock *sk, struct sk_buff *skb, int flag)
+ {
+ 	struct inet_connection_sock *icsk = inet_csk(sk);
+ 	struct tcp_sock *tp = tcp_sk(sk);
+@@ -3449,6 +3455,16 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
+ 				    sack_rtt_us);
+ 	acked -= tp->packets_out;
+ 
++	if (mptcp(tp)) {
++		if (mptcp_fallback_infinite(sk, flag)) {
++			pr_err("%s resetting flow\n", __func__);
++			mptcp_send_reset(sk);
++			goto invalid_ack;
++		}
++
++		mptcp_clean_rtx_infinite(skb, sk);
++	}
++
+ 	/* Advance cwnd if state allows */
+ 	if (tcp_may_raise_cwnd(sk, flag))
+ 		tcp_cong_avoid(sk, ack, acked);
+@@ -3512,8 +3528,9 @@ old_ack:
+  * the fast version below fails.
+  */
+ void tcp_parse_options(const struct sk_buff *skb,
+-		       struct tcp_options_received *opt_rx, int estab,
+-		       struct tcp_fastopen_cookie *foc)
++		       struct tcp_options_received *opt_rx,
++		       struct mptcp_options_received *mopt,
++		       int estab, struct tcp_fastopen_cookie *foc)
+ {
+ 	const unsigned char *ptr;
+ 	const struct tcphdr *th = tcp_hdr(skb);
+@@ -3596,6 +3613,9 @@ void tcp_parse_options(const struct sk_buff *skb,
+ 				 */
+ 				break;
+ #endif
++			case TCPOPT_MPTCP:
++				mptcp_parse_options(ptr - 2, opsize, mopt, skb);
++				break;
+ 			case TCPOPT_EXP:
+ 				/* Fast Open option shares code 254 using a
+ 				 * 16 bits magic number. It's valid only in
+@@ -3657,8 +3677,8 @@ static bool tcp_fast_parse_options(const struct sk_buff *skb,
+ 		if (tcp_parse_aligned_timestamp(tp, th))
+ 			return true;
+ 	}
+-
+-	tcp_parse_options(skb, &tp->rx_opt, 1, NULL);
++	tcp_parse_options(skb, &tp->rx_opt, mptcp(tp) ? &tp->mptcp->rx_opt : NULL,
++			  1, NULL);
+ 	if (tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr)
+ 		tp->rx_opt.rcv_tsecr -= tp->tsoffset;
+ 
+@@ -3831,6 +3851,8 @@ static void tcp_fin(struct sock *sk)
+ 		dst = __sk_dst_get(sk);
+ 		if (!dst || !dst_metric(dst, RTAX_QUICKACK))
+ 			inet_csk(sk)->icsk_ack.pingpong = 1;
++		if (mptcp(tp))
++			mptcp_sub_close_passive(sk);
+ 		break;
+ 
+ 	case TCP_CLOSE_WAIT:
+@@ -3852,9 +3874,16 @@ static void tcp_fin(struct sock *sk)
+ 		tcp_set_state(sk, TCP_CLOSING);
+ 		break;
+ 	case TCP_FIN_WAIT2:
++		if (mptcp(tp)) {
++			/* The socket will get closed by mptcp_data_ready.
++			 * We first have to process all data-sequences.
++			 */
++			tp->close_it = 1;
++			break;
++		}
+ 		/* Received a FIN -- send ACK and enter TIME_WAIT. */
+ 		tcp_send_ack(sk);
+-		tcp_time_wait(sk, TCP_TIME_WAIT, 0);
++		tp->ops->time_wait(sk, TCP_TIME_WAIT, 0);
+ 		break;
+ 	default:
+ 		/* Only TCP_LISTEN and TCP_CLOSE are left, in these
+@@ -3876,6 +3905,10 @@ static void tcp_fin(struct sock *sk)
+ 	if (!sock_flag(sk, SOCK_DEAD)) {
+ 		sk->sk_state_change(sk);
+ 
++		/* Don't wake up MPTCP-subflows */
++		if (mptcp(tp))
++			return;
++
+ 		/* Do not send POLL_HUP for half duplex close. */
+ 		if (sk->sk_shutdown == SHUTDOWN_MASK ||
+ 		    sk->sk_state == TCP_CLOSE)
+@@ -4073,7 +4106,11 @@ static void tcp_ofo_queue(struct sock *sk)
+ 			tcp_dsack_extend(sk, TCP_SKB_CB(skb)->seq, dsack);
+ 		}
+ 
+-		if (!after(TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt)) {
++		/* In case of MPTCP, the segment may be empty if it's a
++		 * non-data DATA_FIN. (see beginning of tcp_data_queue)
++		 */
++		if (!after(TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt) &&
++		    !(mptcp(tp) && TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq)) {
+ 			SOCK_DEBUG(sk, "ofo packet was already received\n");
+ 			__skb_unlink(skb, &tp->out_of_order_queue);
+ 			__kfree_skb(skb);
+@@ -4091,12 +4128,14 @@ static void tcp_ofo_queue(struct sock *sk)
+ 	}
+ }
+ 
+-static bool tcp_prune_ofo_queue(struct sock *sk);
+ static int tcp_prune_queue(struct sock *sk);
+ 
+ static int tcp_try_rmem_schedule(struct sock *sk, struct sk_buff *skb,
+ 				 unsigned int size)
+ {
++	if (mptcp(tcp_sk(sk)))
++		sk = mptcp_meta_sk(sk);
++
+ 	if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
+ 	    !sk_rmem_schedule(sk, skb, size)) {
+ 
+@@ -4104,7 +4143,7 @@ static int tcp_try_rmem_schedule(struct sock *sk, struct sk_buff *skb,
+ 			return -1;
+ 
+ 		if (!sk_rmem_schedule(sk, skb, size)) {
+-			if (!tcp_prune_ofo_queue(sk))
++			if (!tcp_sk(sk)->ops->prune_ofo_queue(sk))
+ 				return -1;
+ 
+ 			if (!sk_rmem_schedule(sk, skb, size))
+@@ -4127,15 +4166,16 @@ static int tcp_try_rmem_schedule(struct sock *sk, struct sk_buff *skb,
+  * Better try to coalesce them right now to avoid future collapses.
+  * Returns true if caller should free @from instead of queueing it
+  */
+-static bool tcp_try_coalesce(struct sock *sk,
+-			     struct sk_buff *to,
+-			     struct sk_buff *from,
+-			     bool *fragstolen)
++bool tcp_try_coalesce(struct sock *sk, struct sk_buff *to, struct sk_buff *from,
++		      bool *fragstolen)
+ {
+ 	int delta;
+ 
+ 	*fragstolen = false;
+ 
++	if (mptcp(tcp_sk(sk)) && !is_meta_sk(sk))
++		return false;
++
+ 	if (tcp_hdr(from)->fin)
+ 		return false;
+ 
+@@ -4225,7 +4265,9 @@ static void tcp_data_queue_ofo(struct sock *sk, struct sk_buff *skb)
+ 
+ 	/* Do skb overlap to previous one? */
+ 	if (skb1 && before(seq, TCP_SKB_CB(skb1)->end_seq)) {
+-		if (!after(end_seq, TCP_SKB_CB(skb1)->end_seq)) {
++		/* MPTCP allows non-data data-fin to be in the ofo-queue */
++		if (!after(end_seq, TCP_SKB_CB(skb1)->end_seq) &&
++		    !(mptcp(tp) && end_seq == seq)) {
+ 			/* All the bits are present. Drop. */
+ 			NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPOFOMERGE);
+ 			__kfree_skb(skb);
+@@ -4263,6 +4305,9 @@ static void tcp_data_queue_ofo(struct sock *sk, struct sk_buff *skb)
+ 					 end_seq);
+ 			break;
+ 		}
++		/* MPTCP allows non-data data-fin to be in the ofo-queue */
++		if (mptcp(tp) && TCP_SKB_CB(skb1)->seq == TCP_SKB_CB(skb1)->end_seq)
++			continue;
+ 		__skb_unlink(skb1, &tp->out_of_order_queue);
+ 		tcp_dsack_extend(sk, TCP_SKB_CB(skb1)->seq,
+ 				 TCP_SKB_CB(skb1)->end_seq);
+@@ -4280,8 +4325,8 @@ end:
+ 	}
+ }
+ 
+-static int __must_check tcp_queue_rcv(struct sock *sk, struct sk_buff *skb, int hdrlen,
+-		  bool *fragstolen)
++int __must_check tcp_queue_rcv(struct sock *sk, struct sk_buff *skb, int hdrlen,
++			       bool *fragstolen)
+ {
+ 	int eaten;
+ 	struct sk_buff *tail = skb_peek_tail(&sk->sk_receive_queue);
+@@ -4343,7 +4388,10 @@ static void tcp_data_queue(struct sock *sk, struct sk_buff *skb)
+ 	int eaten = -1;
+ 	bool fragstolen = false;
+ 
+-	if (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq)
++	/* If no data is present, but a data_fin is in the options, we still
++	 * have to call mptcp_queue_skb later on. */
++	if (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq &&
++	    !(mptcp(tp) && mptcp_is_data_fin(skb)))
+ 		goto drop;
+ 
+ 	skb_dst_drop(skb);
+@@ -4389,7 +4437,7 @@ queue_and_out:
+ 			eaten = tcp_queue_rcv(sk, skb, 0, &fragstolen);
+ 		}
+ 		tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
+-		if (skb->len)
++		if (skb->len || mptcp_is_data_fin(skb))
+ 			tcp_event_data_recv(sk, skb);
+ 		if (th->fin)
+ 			tcp_fin(sk);
+@@ -4411,7 +4459,11 @@ queue_and_out:
+ 
+ 		if (eaten > 0)
+ 			kfree_skb_partial(skb, fragstolen);
+-		if (!sock_flag(sk, SOCK_DEAD))
++		if (!sock_flag(sk, SOCK_DEAD) || mptcp(tp))
++			/* MPTCP: we always have to call data_ready, because
++			 * we may be about to receive a data-fin, which still
++			 * must get queued.
++			 */
+ 			sk->sk_data_ready(sk);
+ 		return;
+ 	}
+@@ -4463,6 +4515,8 @@ static struct sk_buff *tcp_collapse_one(struct sock *sk, struct sk_buff *skb,
+ 		next = skb_queue_next(list, skb);
+ 
+ 	__skb_unlink(skb, list);
++	if (mptcp(tcp_sk(sk)))
++		mptcp_remove_shortcuts(tcp_sk(sk)->mpcb, skb);
+ 	__kfree_skb(skb);
+ 	NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPRCVCOLLAPSED);
+ 
+@@ -4630,7 +4684,7 @@ static void tcp_collapse_ofo_queue(struct sock *sk)
+  * Purge the out-of-order queue.
+  * Return true if queue was pruned.
+  */
+-static bool tcp_prune_ofo_queue(struct sock *sk)
++bool tcp_prune_ofo_queue(struct sock *sk)
+ {
+ 	struct tcp_sock *tp = tcp_sk(sk);
+ 	bool res = false;
+@@ -4686,7 +4740,7 @@ static int tcp_prune_queue(struct sock *sk)
+ 	/* Collapsing did not help, destructive actions follow.
+ 	 * This must not ever occur. */
+ 
+-	tcp_prune_ofo_queue(sk);
++	tp->ops->prune_ofo_queue(sk);
+ 
+ 	if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf)
+ 		return 0;
+@@ -4702,7 +4756,29 @@ static int tcp_prune_queue(struct sock *sk)
+ 	return -1;
+ }
+ 
+-static bool tcp_should_expand_sndbuf(const struct sock *sk)
++/* RFC2861, slow part. Adjust cwnd, after it was not full during one rto.
++ * As additional protections, we do not touch cwnd in retransmission phases,
++ * and if application hit its sndbuf limit recently.
++ */
++void tcp_cwnd_application_limited(struct sock *sk)
++{
++	struct tcp_sock *tp = tcp_sk(sk);
++
++	if (inet_csk(sk)->icsk_ca_state == TCP_CA_Open &&
++	    sk->sk_socket && !test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) {
++		/* Limited by application or receiver window. */
++		u32 init_win = tcp_init_cwnd(tp, __sk_dst_get(sk));
++		u32 win_used = max(tp->snd_cwnd_used, init_win);
++		if (win_used < tp->snd_cwnd) {
++			tp->snd_ssthresh = tcp_current_ssthresh(sk);
++			tp->snd_cwnd = (tp->snd_cwnd + win_used) >> 1;
++		}
++		tp->snd_cwnd_used = 0;
++	}
++	tp->snd_cwnd_stamp = tcp_time_stamp;
++}
++
++bool tcp_should_expand_sndbuf(const struct sock *sk)
+ {
+ 	const struct tcp_sock *tp = tcp_sk(sk);
+ 
+@@ -4737,7 +4813,7 @@ static void tcp_new_space(struct sock *sk)
+ {
+ 	struct tcp_sock *tp = tcp_sk(sk);
+ 
+-	if (tcp_should_expand_sndbuf(sk)) {
++	if (tp->ops->should_expand_sndbuf(sk)) {
+ 		tcp_sndbuf_expand(sk);
+ 		tp->snd_cwnd_stamp = tcp_time_stamp;
+ 	}
+@@ -4749,8 +4825,9 @@ static void tcp_check_space(struct sock *sk)
+ {
+ 	if (sock_flag(sk, SOCK_QUEUE_SHRUNK)) {
+ 		sock_reset_flag(sk, SOCK_QUEUE_SHRUNK);
+-		if (sk->sk_socket &&
+-		    test_bit(SOCK_NOSPACE, &sk->sk_socket->flags))
++		if (mptcp(tcp_sk(sk)) ||
++		    (sk->sk_socket &&
++			test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)))
+ 			tcp_new_space(sk);
+ 	}
+ }
+@@ -4773,7 +4850,7 @@ static void __tcp_ack_snd_check(struct sock *sk, int ofo_possible)
+ 	     /* ... and right edge of window advances far enough.
+ 	      * (tcp_recvmsg() will send ACK otherwise). Or...
+ 	      */
+-	     __tcp_select_window(sk) >= tp->rcv_wnd) ||
++	     tp->ops->__select_window(sk) >= tp->rcv_wnd) ||
+ 	    /* We ACK each frame or... */
+ 	    tcp_in_quickack_mode(sk) ||
+ 	    /* We have out of order data. */
+@@ -4875,6 +4952,10 @@ static void tcp_urg(struct sock *sk, struct sk_buff *skb, const struct tcphdr *t
+ {
+ 	struct tcp_sock *tp = tcp_sk(sk);
+ 
++	/* MPTCP urgent data is not yet supported */
++	if (mptcp(tp))
++		return;
++
+ 	/* Check if we get a new urgent pointer - normally not. */
+ 	if (th->urg)
+ 		tcp_check_urg(sk, th);
+@@ -4942,8 +5023,7 @@ static inline bool tcp_checksum_complete_user(struct sock *sk,
+ }
+ 
+ #ifdef CONFIG_NET_DMA
+-static bool tcp_dma_try_early_copy(struct sock *sk, struct sk_buff *skb,
+-				  int hlen)
++bool tcp_dma_try_early_copy(struct sock *sk, struct sk_buff *skb, int hlen)
+ {
+ 	struct tcp_sock *tp = tcp_sk(sk);
+ 	int chunk = skb->len - hlen;
+@@ -5052,9 +5132,15 @@ syn_challenge:
+ 		goto discard;
+ 	}
+ 
++	/* If valid: post process the received MPTCP options. */
++	if (mptcp(tp) && mptcp_handle_options(sk, th, skb))
++		goto discard;
++
+ 	return true;
+ 
+ discard:
++	if (mptcp(tp))
++		mptcp_reset_mopt(tp);
+ 	__kfree_skb(skb);
+ 	return false;
+ }
+@@ -5106,6 +5192,10 @@ void tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
+ 
+ 	tp->rx_opt.saw_tstamp = 0;
+ 
++	/* MPTCP: force slowpath. */
++	if (mptcp(tp))
++		goto slow_path;
++
+ 	/*	pred_flags is 0xS?10 << 16 + snd_wnd
+ 	 *	if header_prediction is to be made
+ 	 *	'S' will always be tp->tcp_header_len >> 2
+@@ -5205,7 +5295,7 @@ void tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
+ 					NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPHPHITSTOUSER);
+ 				}
+ 				if (copied_early)
+-					tcp_cleanup_rbuf(sk, skb->len);
++					tp->ops->cleanup_rbuf(sk, skb->len);
+ 			}
+ 			if (!eaten) {
+ 				if (tcp_checksum_complete_user(sk, skb))
+@@ -5313,14 +5403,14 @@ void tcp_finish_connect(struct sock *sk, struct sk_buff *skb)
+ 
+ 	tcp_init_metrics(sk);
+ 
+-	tcp_init_congestion_control(sk);
++	tp->ops->init_congestion_control(sk);
+ 
+ 	/* Prevent spurious tcp_cwnd_restart() on first data
+ 	 * packet.
+ 	 */
+ 	tp->lsndtime = tcp_time_stamp;
+ 
+-	tcp_init_buffer_space(sk);
++	tp->ops->init_buffer_space(sk);
+ 
+ 	if (sock_flag(sk, SOCK_KEEPOPEN))
+ 		inet_csk_reset_keepalive_timer(sk, keepalive_time_when(tp));
+@@ -5350,7 +5440,7 @@ static bool tcp_rcv_fastopen_synack(struct sock *sk, struct sk_buff *synack,
+ 		/* Get original SYNACK MSS value if user MSS sets mss_clamp */
+ 		tcp_clear_options(&opt);
+ 		opt.user_mss = opt.mss_clamp = 0;
+-		tcp_parse_options(synack, &opt, 0, NULL);
++		tcp_parse_options(synack, &opt, NULL, 0, NULL);
+ 		mss = opt.mss_clamp;
+ 	}
+ 
+@@ -5365,7 +5455,11 @@ static bool tcp_rcv_fastopen_synack(struct sock *sk, struct sk_buff *synack,
+ 
+ 	tcp_fastopen_cache_set(sk, mss, cookie, syn_drop);
+ 
+-	if (data) { /* Retransmit unacked data in SYN */
++	/* In mptcp case, we do not rely on "retransmit", but instead on
++	 * "transmit", because if fastopen data is not acked, the retransmission
++	 * becomes the first MPTCP data (see mptcp_rcv_synsent_fastopen).
++	 */
++	if (data && !mptcp(tp)) { /* Retransmit unacked data in SYN */
+ 		tcp_for_write_queue_from(data, sk) {
+ 			if (data == tcp_send_head(sk) ||
+ 			    __tcp_retransmit_skb(sk, data))
+@@ -5388,8 +5482,11 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
+ 	struct tcp_sock *tp = tcp_sk(sk);
+ 	struct tcp_fastopen_cookie foc = { .len = -1 };
+ 	int saved_clamp = tp->rx_opt.mss_clamp;
++	struct mptcp_options_received mopt;
++	mptcp_init_mp_opt(&mopt);
+ 
+-	tcp_parse_options(skb, &tp->rx_opt, 0, &foc);
++	tcp_parse_options(skb, &tp->rx_opt,
++			  mptcp(tp) ? &tp->mptcp->rx_opt : &mopt, 0, &foc);
+ 	if (tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr)
+ 		tp->rx_opt.rcv_tsecr -= tp->tsoffset;
+ 
+@@ -5448,6 +5545,30 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
+ 		tcp_init_wl(tp, TCP_SKB_CB(skb)->seq);
+ 		tcp_ack(sk, skb, FLAG_SLOWPATH);
+ 
++		if (tp->request_mptcp || mptcp(tp)) {
++			int ret;
++			ret = mptcp_rcv_synsent_state_process(sk, &sk,
++							      skb, &mopt);
++
++			/* May have changed if we support MPTCP */
++			tp = tcp_sk(sk);
++			icsk = inet_csk(sk);
++
++			if (ret == 1)
++				goto reset_and_undo;
++			if (ret == 2)
++				goto discard;
++		}
++
++		if (mptcp(tp) && !is_master_tp(tp)) {
++			/* Timer for repeating the ACK until an answer
++			 * arrives. Used only when establishing an additional
++			 * subflow inside of an MPTCP connection.
++			 */
++			sk_reset_timer(sk, &tp->mptcp->mptcp_ack_timer,
++				       jiffies + icsk->icsk_rto);
++		}
++
+ 		/* Ok.. it's good. Set up sequence numbers and
+ 		 * move to established.
+ 		 */
+@@ -5474,6 +5595,11 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
+ 			tp->tcp_header_len = sizeof(struct tcphdr);
+ 		}
+ 
++		if (mptcp(tp)) {
++			tp->tcp_header_len += MPTCP_SUB_LEN_DSM_ALIGN;
++			tp->advmss -= MPTCP_SUB_LEN_DSM_ALIGN;
++		}
++
+ 		if (tcp_is_sack(tp) && sysctl_tcp_fack)
+ 			tcp_enable_fack(tp);
+ 
+@@ -5494,9 +5620,12 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
+ 		    tcp_rcv_fastopen_synack(sk, skb, &foc))
+ 			return -1;
+ 
+-		if (sk->sk_write_pending ||
++		/* With MPTCP we cannot send data on the third ack due to the
++		 * lack of option-space to combine with an MP_CAPABLE.
++		 */
++		if (!mptcp(tp) && (sk->sk_write_pending ||
+ 		    icsk->icsk_accept_queue.rskq_defer_accept ||
+-		    icsk->icsk_ack.pingpong) {
++		    icsk->icsk_ack.pingpong)) {
+ 			/* Save one ACK. Data will be ready after
+ 			 * several ticks, if write_pending is set.
+ 			 *
+@@ -5536,6 +5665,7 @@ discard:
+ 	    tcp_paws_reject(&tp->rx_opt, 0))
+ 		goto discard_and_undo;
+ 
++	/* TODO - check this here for MPTCP */
+ 	if (th->syn) {
+ 		/* We see SYN without ACK. It is attempt of
+ 		 * simultaneous connect with crossed SYNs.
+@@ -5552,6 +5682,11 @@ discard:
+ 			tp->tcp_header_len = sizeof(struct tcphdr);
+ 		}
+ 
++		if (mptcp(tp)) {
++			tp->tcp_header_len += MPTCP_SUB_LEN_DSM_ALIGN;
++			tp->advmss -= MPTCP_SUB_LEN_DSM_ALIGN;
++		}
++
+ 		tp->rcv_nxt = TCP_SKB_CB(skb)->seq + 1;
+ 		tp->rcv_wup = TCP_SKB_CB(skb)->seq + 1;
+ 
+@@ -5610,6 +5745,7 @@ reset_and_undo:
+ 
+ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
+ 			  const struct tcphdr *th, unsigned int len)
++	__releases(&sk->sk_lock.slock)
+ {
+ 	struct tcp_sock *tp = tcp_sk(sk);
+ 	struct inet_connection_sock *icsk = inet_csk(sk);
+@@ -5661,6 +5797,16 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
+ 
+ 	case TCP_SYN_SENT:
+ 		queued = tcp_rcv_synsent_state_process(sk, skb, th, len);
++		if (is_meta_sk(sk)) {
++			sk = tcp_sk(sk)->mpcb->master_sk;
++			tp = tcp_sk(sk);
++
++			/* Need to call it here, because it will announce new
++			 * addresses, which can only be done after the third ack
++			 * of the 3-way handshake.
++			 */
++			mptcp_update_metasocket(sk, tp->meta_sk);
++		}
+ 		if (queued >= 0)
+ 			return queued;
+ 
+@@ -5668,6 +5814,8 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
+ 		tcp_urg(sk, skb, th);
+ 		__kfree_skb(skb);
+ 		tcp_data_snd_check(sk);
++		if (mptcp(tp) && is_master_tp(tp))
++			bh_unlock_sock(sk);
+ 		return 0;
+ 	}
+ 
+@@ -5706,11 +5854,11 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
+ 			synack_stamp = tp->lsndtime;
+ 			/* Make sure socket is routed, for correct metrics. */
+ 			icsk->icsk_af_ops->rebuild_header(sk);
+-			tcp_init_congestion_control(sk);
++			tp->ops->init_congestion_control(sk);
+ 
+ 			tcp_mtup_init(sk);
+ 			tp->copied_seq = tp->rcv_nxt;
+-			tcp_init_buffer_space(sk);
++			tp->ops->init_buffer_space(sk);
+ 		}
+ 		smp_mb();
+ 		tcp_set_state(sk, TCP_ESTABLISHED);
+@@ -5730,6 +5878,8 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
+ 
+ 		if (tp->rx_opt.tstamp_ok)
+ 			tp->advmss -= TCPOLEN_TSTAMP_ALIGNED;
++		if (mptcp(tp))
++			tp->advmss -= MPTCP_SUB_LEN_DSM_ALIGN;
+ 
+ 		if (req) {
+ 			/* Re-arm the timer because data may have been sent out.
+@@ -5751,6 +5901,12 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
+ 
+ 		tcp_initialize_rcv_mss(sk);
+ 		tcp_fast_path_on(tp);
++		/* Send an ACK when establishing a new
++		 * MPTCP subflow, i.e. using an MP_JOIN
++		 * subtype.
++		 */
++		if (mptcp(tp) && !is_master_tp(tp))
++			tcp_send_ack(sk);
+ 		break;
+ 
+ 	case TCP_FIN_WAIT1: {
+@@ -5802,7 +5958,8 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
+ 		tmo = tcp_fin_time(sk);
+ 		if (tmo > TCP_TIMEWAIT_LEN) {
+ 			inet_csk_reset_keepalive_timer(sk, tmo - TCP_TIMEWAIT_LEN);
+-		} else if (th->fin || sock_owned_by_user(sk)) {
++		} else if (th->fin || mptcp_is_data_fin(skb) ||
++			   sock_owned_by_user(sk)) {
+ 			/* Bad case. We could lose such FIN otherwise.
+ 			 * It is not a big problem, but it looks confusing
+ 			 * and not so rare event. We still can lose it now,
+@@ -5811,7 +5968,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
+ 			 */
+ 			inet_csk_reset_keepalive_timer(sk, tmo);
+ 		} else {
+-			tcp_time_wait(sk, TCP_FIN_WAIT2, tmo);
++			tp->ops->time_wait(sk, TCP_FIN_WAIT2, tmo);
+ 			goto discard;
+ 		}
+ 		break;
+@@ -5819,7 +5976,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
+ 
+ 	case TCP_CLOSING:
+ 		if (tp->snd_una == tp->write_seq) {
+-			tcp_time_wait(sk, TCP_TIME_WAIT, 0);
++			tp->ops->time_wait(sk, TCP_TIME_WAIT, 0);
+ 			goto discard;
+ 		}
+ 		break;
+@@ -5831,6 +5988,9 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
+ 			goto discard;
+ 		}
+ 		break;
++	case TCP_CLOSE:
++		if (tp->mp_killed)
++			goto discard;
+ 	}
+ 
+ 	/* step 6: check the URG bit */
+@@ -5851,7 +6011,11 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
+ 		 */
+ 		if (sk->sk_shutdown & RCV_SHUTDOWN) {
+ 			if (TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq &&
+-			    after(TCP_SKB_CB(skb)->end_seq - th->fin, tp->rcv_nxt)) {
++			    after(TCP_SKB_CB(skb)->end_seq - th->fin, tp->rcv_nxt) &&
++			    !mptcp(tp)) {
++				/* In case of mptcp, the reset is handled by
++				 * mptcp_rcv_state_process
++				 */
+ 				NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPABORTONDATA);
+ 				tcp_reset(sk);
+ 				return 1;
+@@ -5877,3 +6041,154 @@ discard:
+ 	return 0;
+ }
+ EXPORT_SYMBOL(tcp_rcv_state_process);
++
++static inline void pr_drop_req(struct request_sock *req, __u16 port, int family)
++{
++	struct inet_request_sock *ireq = inet_rsk(req);
++
++	if (family == AF_INET)
++		LIMIT_NETDEBUG(KERN_DEBUG pr_fmt("drop open request from %pI4/%u\n"),
++			       &ireq->ir_rmt_addr, port);
++#if IS_ENABLED(CONFIG_IPV6)
++	else if (family == AF_INET6)
++		LIMIT_NETDEBUG(KERN_DEBUG pr_fmt("drop open request from %pI6/%u\n"),
++			       &ireq->ir_v6_rmt_addr, port);
++#endif
++}
++
++int tcp_conn_request(struct request_sock_ops *rsk_ops,
++		     const struct tcp_request_sock_ops *af_ops,
++		     struct sock *sk, struct sk_buff *skb)
++{
++	struct tcp_options_received tmp_opt;
++	struct request_sock *req;
++	struct tcp_sock *tp = tcp_sk(sk);
++	struct dst_entry *dst = NULL;
++	__u32 isn = TCP_SKB_CB(skb)->when;
++	bool want_cookie = false, fastopen;
++	struct flowi fl;
++	struct tcp_fastopen_cookie foc = { .len = -1 };
++	int err;
++
++
++	/* TW buckets are converted to open requests without
++	 * limitations, they conserve resources and peer is
++	 * evidently real one.
++	 */
++	if ((sysctl_tcp_syncookies == 2 ||
++	     inet_csk_reqsk_queue_is_full(sk)) && !isn) {
++		want_cookie = tcp_syn_flood_action(sk, skb, rsk_ops->slab_name);
++		if (!want_cookie)
++			goto drop;
++	}
++
++
++	/* Accept backlog is full. If we have already queued enough
++	 * of warm entries in syn queue, drop request. It is better than
++	 * clogging syn queue with openreqs with exponentially increasing
++	 * timeout.
++	 */
++	if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1) {
++		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
++		goto drop;
++	}
++
++	req = inet_reqsk_alloc(rsk_ops);
++	if (!req)
++		goto drop;
++
++	tcp_rsk(req)->af_specific = af_ops;
++
++	tcp_clear_options(&tmp_opt);
++	tmp_opt.mss_clamp = af_ops->mss_clamp;
++	tmp_opt.user_mss  = tp->rx_opt.user_mss;
++	tcp_parse_options(skb, &tmp_opt, NULL, 0, want_cookie ? NULL : &foc);
++
++	if (want_cookie && !tmp_opt.saw_tstamp)
++		tcp_clear_options(&tmp_opt);
++
++	tmp_opt.tstamp_ok = tmp_opt.saw_tstamp;
++	tcp_openreq_init(req, &tmp_opt, skb);
++
++	if (af_ops->init_req(req, sk, skb))
++		goto drop_and_free;
++
++	if (security_inet_conn_request(sk, skb, req))
++		goto drop_and_free;
++
++	if (!want_cookie || tmp_opt.tstamp_ok)
++		TCP_ECN_create_request(req, skb, sock_net(sk));
++
++	if (want_cookie) {
++		isn = cookie_init_sequence(af_ops, sk, skb, &req->mss);
++		req->cookie_ts = tmp_opt.tstamp_ok;
++	} else if (!isn) {
++		/* VJ's idea. We save last timestamp seen
++		 * from the destination in peer table, when entering
++		 * state TIME-WAIT, and check against it before
++		 * accepting new connection request.
++		 *
++		 * If "isn" is not zero, this request hit alive
++		 * timewait bucket, so that all the necessary checks
++		 * are made in the function processing timewait state.
++		 */
++		if (tmp_opt.saw_tstamp && tcp_death_row.sysctl_tw_recycle) {
++			bool strict;
++
++			dst = af_ops->route_req(sk, &fl, req, &strict);
++			if (dst && strict &&
++			    !tcp_peer_is_proven(req, dst, true)) {
++				NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_PAWSPASSIVEREJECTED);
++				goto drop_and_release;
++			}
++		}
++		/* Kill the following clause, if you dislike this way. */
++		else if (!sysctl_tcp_syncookies &&
++			 (sysctl_max_syn_backlog - inet_csk_reqsk_queue_len(sk) <
++			  (sysctl_max_syn_backlog >> 2)) &&
++			 !tcp_peer_is_proven(req, dst, false)) {
++			/* Without syncookies last quarter of
++			 * backlog is filled with destinations,
++			 * proven to be alive.
++			 * It means that we continue to communicate
++			 * to destinations, already remembered
++			 * to the moment of synflood.
++			 */
++			pr_drop_req(req, ntohs(tcp_hdr(skb)->source),
++				    rsk_ops->family);
++			goto drop_and_release;
++		}
++
++		isn = af_ops->init_seq(skb);
++	}
++	if (!dst) {
++		dst = af_ops->route_req(sk, &fl, req, NULL);
++		if (!dst)
++			goto drop_and_free;
++	}
++
++	tcp_rsk(req)->snt_isn = isn;
++	tcp_openreq_init_rwin(req, sk, dst);
++	fastopen = !want_cookie &&
++		   tcp_try_fastopen(sk, skb, req, &foc, dst);
++	err = af_ops->send_synack(sk, dst, &fl, req,
++				  skb_get_queue_mapping(skb), &foc);
++	if (!fastopen) {
++		if (err || want_cookie)
++			goto drop_and_free;
++
++		tcp_rsk(req)->listener = NULL;
++		af_ops->queue_hash_add(sk, req, TCP_TIMEOUT_INIT);
++	}
++
++	return 0;
++
++drop_and_release:
++	dst_release(dst);
++drop_and_free:
++	reqsk_free(req);
++drop:
++	NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
++	return 0;
++}
++EXPORT_SYMBOL(tcp_conn_request);
+diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
+index 77cccda1ad0c..c77017f600f1 100644
+--- a/net/ipv4/tcp_ipv4.c
++++ b/net/ipv4/tcp_ipv4.c
+@@ -67,6 +67,8 @@
+ #include <net/icmp.h>
+ #include <net/inet_hashtables.h>
+ #include <net/tcp.h>
++#include <net/mptcp.h>
++#include <net/mptcp_v4.h>
+ #include <net/transp_v6.h>
+ #include <net/ipv6.h>
+ #include <net/inet_common.h>
+@@ -99,7 +101,7 @@ static int tcp_v4_md5_hash_hdr(char *md5_hash, const struct tcp_md5sig_key *key,
+ struct inet_hashinfo tcp_hashinfo;
+ EXPORT_SYMBOL(tcp_hashinfo);
+ 
+-static inline __u32 tcp_v4_init_sequence(const struct sk_buff *skb)
++__u32 tcp_v4_init_sequence(const struct sk_buff *skb)
+ {
+ 	return secure_tcp_sequence_number(ip_hdr(skb)->daddr,
+ 					  ip_hdr(skb)->saddr,
+@@ -334,7 +336,7 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
+ 	struct inet_sock *inet;
+ 	const int type = icmp_hdr(icmp_skb)->type;
+ 	const int code = icmp_hdr(icmp_skb)->code;
+-	struct sock *sk;
++	struct sock *sk, *meta_sk;
+ 	struct sk_buff *skb;
+ 	struct request_sock *fastopen;
+ 	__u32 seq, snd_una;
+@@ -358,13 +360,19 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
+ 		return;
+ 	}
+ 
+-	bh_lock_sock(sk);
++	tp = tcp_sk(sk);
++	if (mptcp(tp))
++		meta_sk = mptcp_meta_sk(sk);
++	else
++		meta_sk = sk;
++
++	bh_lock_sock(meta_sk);
+ 	/* If too many ICMPs get dropped on busy
+ 	 * servers this needs to be solved differently.
+ 	 * We do take care of PMTU discovery (RFC1191) special case :
+ 	 * we can receive locally generated ICMP messages while socket is held.
+ 	 */
+-	if (sock_owned_by_user(sk)) {
++	if (sock_owned_by_user(meta_sk)) {
+ 		if (!(type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED))
+ 			NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS);
+ 	}
+@@ -377,7 +385,6 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
+ 	}
+ 
+ 	icsk = inet_csk(sk);
+-	tp = tcp_sk(sk);
+ 	seq = ntohl(th->seq);
+ 	/* XXX (TFO) - tp->snd_una should be ISN (tcp_create_openreq_child() */
+ 	fastopen = tp->fastopen_rsk;
+@@ -411,11 +418,13 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
+ 				goto out;
+ 
+ 			tp->mtu_info = info;
+-			if (!sock_owned_by_user(sk)) {
++			if (!sock_owned_by_user(meta_sk)) {
+ 				tcp_v4_mtu_reduced(sk);
+ 			} else {
+ 				if (!test_and_set_bit(TCP_MTU_REDUCED_DEFERRED, &tp->tsq_flags))
+ 					sock_hold(sk);
++				if (mptcp(tp))
++					mptcp_tsq_flags(sk);
+ 			}
+ 			goto out;
+ 		}
+@@ -429,7 +438,7 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
+ 		    !icsk->icsk_backoff || fastopen)
+ 			break;
+ 
+-		if (sock_owned_by_user(sk))
++		if (sock_owned_by_user(meta_sk))
+ 			break;
+ 
+ 		icsk->icsk_backoff--;
+@@ -463,7 +472,7 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
+ 	switch (sk->sk_state) {
+ 		struct request_sock *req, **prev;
+ 	case TCP_LISTEN:
+-		if (sock_owned_by_user(sk))
++		if (sock_owned_by_user(meta_sk))
+ 			goto out;
+ 
+ 		req = inet_csk_search_req(sk, &prev, th->dest,
+@@ -499,7 +508,7 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
+ 		if (fastopen && fastopen->sk == NULL)
+ 			break;
+ 
+-		if (!sock_owned_by_user(sk)) {
++		if (!sock_owned_by_user(meta_sk)) {
+ 			sk->sk_err = err;
+ 
+ 			sk->sk_error_report(sk);
+@@ -528,7 +537,7 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
+ 	 */
+ 
+ 	inet = inet_sk(sk);
+-	if (!sock_owned_by_user(sk) && inet->recverr) {
++	if (!sock_owned_by_user(meta_sk) && inet->recverr) {
+ 		sk->sk_err = err;
+ 		sk->sk_error_report(sk);
+ 	} else	{ /* Only an error on timeout */
+@@ -536,7 +545,7 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
+ 	}
+ 
+ out:
+-	bh_unlock_sock(sk);
++	bh_unlock_sock(meta_sk);
+ 	sock_put(sk);
+ }
+ 
+@@ -578,7 +587,7 @@ EXPORT_SYMBOL(tcp_v4_send_check);
+  *	Exception: precedence violation. We do not implement it in any case.
+  */
+ 
+-static void tcp_v4_send_reset(struct sock *sk, struct sk_buff *skb)
++void tcp_v4_send_reset(struct sock *sk, struct sk_buff *skb)
+ {
+ 	const struct tcphdr *th = tcp_hdr(skb);
+ 	struct {
+@@ -702,10 +711,10 @@ release_sk1:
+    outside socket context is ugly, certainly. What can I do?
+  */
+ 
+-static void tcp_v4_send_ack(struct sk_buff *skb, u32 seq, u32 ack,
++static void tcp_v4_send_ack(struct sk_buff *skb, u32 seq, u32 ack, u32 data_ack,
+ 			    u32 win, u32 tsval, u32 tsecr, int oif,
+ 			    struct tcp_md5sig_key *key,
+-			    int reply_flags, u8 tos)
++			    int reply_flags, u8 tos, int mptcp)
+ {
+ 	const struct tcphdr *th = tcp_hdr(skb);
+ 	struct {
+@@ -714,6 +723,10 @@ static void tcp_v4_send_ack(struct sk_buff *skb, u32 seq, u32 ack,
+ #ifdef CONFIG_TCP_MD5SIG
+ 			   + (TCPOLEN_MD5SIG_ALIGNED >> 2)
+ #endif
++#ifdef CONFIG_MPTCP
++			   + ((MPTCP_SUB_LEN_DSS >> 2) +
++			      (MPTCP_SUB_LEN_ACK >> 2))
++#endif
+ 			];
+ 	} rep;
+ 	struct ip_reply_arg arg;
+@@ -758,6 +771,21 @@ static void tcp_v4_send_ack(struct sk_buff *skb, u32 seq, u32 ack,
+ 				    ip_hdr(skb)->daddr, &rep.th);
+ 	}
+ #endif
++#ifdef CONFIG_MPTCP
++	if (mptcp) {
++		int offset = (tsecr) ? 3 : 0;
++		/* Construction of 32-bit data_ack */
++		rep.opt[offset++] = htonl((TCPOPT_MPTCP << 24) |
++					  ((MPTCP_SUB_LEN_DSS + MPTCP_SUB_LEN_ACK) << 16) |
++					  (0x20 << 8) |
++					  (0x01));
++		rep.opt[offset] = htonl(data_ack);
++
++		arg.iov[0].iov_len += MPTCP_SUB_LEN_DSS + MPTCP_SUB_LEN_ACK;
++		rep.th.doff = arg.iov[0].iov_len / 4;
++	}
++#endif /* CONFIG_MPTCP */
++
+ 	arg.flags = reply_flags;
+ 	arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr,
+ 				      ip_hdr(skb)->saddr, /* XXX */
+@@ -776,36 +804,44 @@ static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb)
+ {
+ 	struct inet_timewait_sock *tw = inet_twsk(sk);
+ 	struct tcp_timewait_sock *tcptw = tcp_twsk(sk);
++	u32 data_ack = 0;
++	int mptcp = 0;
++
++	if (tcptw->mptcp_tw && tcptw->mptcp_tw->meta_tw) {
++		data_ack = (u32)tcptw->mptcp_tw->rcv_nxt;
++		mptcp = 1;
++	}
+ 
+ 	tcp_v4_send_ack(skb, tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,
++			data_ack,
+ 			tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale,
+ 			tcp_time_stamp + tcptw->tw_ts_offset,
+ 			tcptw->tw_ts_recent,
+ 			tw->tw_bound_dev_if,
+ 			tcp_twsk_md5_key(tcptw),
+ 			tw->tw_transparent ? IP_REPLY_ARG_NOSRCCHECK : 0,
+-			tw->tw_tos
++			tw->tw_tos, mptcp
+ 			);
+ 
+ 	inet_twsk_put(tw);
+ }
+ 
+-static void tcp_v4_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
+-				  struct request_sock *req)
++void tcp_v4_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
++			   struct request_sock *req)
+ {
+ 	/* sk->sk_state == TCP_LISTEN -> for regular TCP_SYN_RECV
+ 	 * sk->sk_state == TCP_SYN_RECV -> for Fast Open.
+ 	 */
+ 	tcp_v4_send_ack(skb, (sk->sk_state == TCP_LISTEN) ?
+ 			tcp_rsk(req)->snt_isn + 1 : tcp_sk(sk)->snd_nxt,
+-			tcp_rsk(req)->rcv_nxt, req->rcv_wnd,
++			tcp_rsk(req)->rcv_nxt, 0, req->rcv_wnd,
+ 			tcp_time_stamp,
+ 			req->ts_recent,
+ 			0,
+ 			tcp_md5_do_lookup(sk, (union tcp_md5_addr *)&ip_hdr(skb)->daddr,
+ 					  AF_INET),
+ 			inet_rsk(req)->no_srccheck ? IP_REPLY_ARG_NOSRCCHECK : 0,
+-			ip_hdr(skb)->tos);
++			ip_hdr(skb)->tos, 0);
+ }
+ 
+ /*
+@@ -813,10 +849,11 @@ static void tcp_v4_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
+  *	This still operates on a request_sock only, not on a big
+  *	socket.
+  */
+-static int tcp_v4_send_synack(struct sock *sk, struct dst_entry *dst,
+-			      struct request_sock *req,
+-			      u16 queue_mapping,
+-			      struct tcp_fastopen_cookie *foc)
++int tcp_v4_send_synack(struct sock *sk, struct dst_entry *dst,
++		       struct flowi *fl,
++		       struct request_sock *req,
++		       u16 queue_mapping,
++		       struct tcp_fastopen_cookie *foc)
+ {
+ 	const struct inet_request_sock *ireq = inet_rsk(req);
+ 	struct flowi4 fl4;
+@@ -844,21 +881,10 @@ static int tcp_v4_send_synack(struct sock *sk, struct dst_entry *dst,
+ 	return err;
+ }
+ 
+-static int tcp_v4_rtx_synack(struct sock *sk, struct request_sock *req)
+-{
+-	int res = tcp_v4_send_synack(sk, NULL, req, 0, NULL);
+-
+-	if (!res) {
+-		TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_RETRANSSEGS);
+-		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPSYNRETRANS);
+-	}
+-	return res;
+-}
+-
+ /*
+  *	IPv4 request_sock destructor.
+  */
+-static void tcp_v4_reqsk_destructor(struct request_sock *req)
++void tcp_v4_reqsk_destructor(struct request_sock *req)
+ {
+ 	kfree(inet_rsk(req)->opt);
+ }
+@@ -896,7 +922,7 @@ EXPORT_SYMBOL(tcp_syn_flood_action);
+ /*
+  * Save and compile IPv4 options into the request_sock if needed.
+  */
+-static struct ip_options_rcu *tcp_v4_save_options(struct sk_buff *skb)
++struct ip_options_rcu *tcp_v4_save_options(struct sk_buff *skb)
+ {
+ 	const struct ip_options *opt = &(IPCB(skb)->opt);
+ 	struct ip_options_rcu *dopt = NULL;
+@@ -1237,161 +1263,71 @@ static bool tcp_v4_inbound_md5_hash(struct sock *sk, const struct sk_buff *skb)
+ 
+ #endif
+ 
++static int tcp_v4_init_req(struct request_sock *req, struct sock *sk,
++			   struct sk_buff *skb)
++{
++	struct inet_request_sock *ireq = inet_rsk(req);
++
++	ireq->ir_loc_addr = ip_hdr(skb)->daddr;
++	ireq->ir_rmt_addr = ip_hdr(skb)->saddr;
++	ireq->no_srccheck = inet_sk(sk)->transparent;
++	ireq->opt = tcp_v4_save_options(skb);
++	ireq->ir_mark = inet_request_mark(sk, skb);
++
++	return 0;
++}
++
++static struct dst_entry *tcp_v4_route_req(struct sock *sk, struct flowi *fl,
++					  const struct request_sock *req,
++					  bool *strict)
++{
++	struct dst_entry *dst = inet_csk_route_req(sk, &fl->u.ip4, req);
++
++	if (strict) {
++		if (fl->u.ip4.daddr == inet_rsk(req)->ir_rmt_addr)
++			*strict = true;
++		else
++			*strict = false;
++	}
++
++	return dst;
++}
++
+ struct request_sock_ops tcp_request_sock_ops __read_mostly = {
+ 	.family		=	PF_INET,
+ 	.obj_size	=	sizeof(struct tcp_request_sock),
+-	.rtx_syn_ack	=	tcp_v4_rtx_synack,
++	.rtx_syn_ack	=	tcp_rtx_synack,
+ 	.send_ack	=	tcp_v4_reqsk_send_ack,
+ 	.destructor	=	tcp_v4_reqsk_destructor,
+ 	.send_reset	=	tcp_v4_send_reset,
+ 	.syn_ack_timeout = 	tcp_syn_ack_timeout,
+ };
+ 
++const struct tcp_request_sock_ops tcp_request_sock_ipv4_ops = {
++	.mss_clamp	=	TCP_MSS_DEFAULT,
+ #ifdef CONFIG_TCP_MD5SIG
+-static const struct tcp_request_sock_ops tcp_request_sock_ipv4_ops = {
+ 	.md5_lookup	=	tcp_v4_reqsk_md5_lookup,
+ 	.calc_md5_hash	=	tcp_v4_md5_hash_skb,
+-};
+ #endif
++	.init_req	=	tcp_v4_init_req,
++#ifdef CONFIG_SYN_COOKIES
++	.cookie_init_seq =	cookie_v4_init_sequence,
++#endif
++	.route_req	=	tcp_v4_route_req,
++	.init_seq	=	tcp_v4_init_sequence,
++	.send_synack	=	tcp_v4_send_synack,
++	.queue_hash_add =	inet_csk_reqsk_queue_hash_add,
++};
+ 
+ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
+ {
+-	struct tcp_options_received tmp_opt;
+-	struct request_sock *req;
+-	struct inet_request_sock *ireq;
+-	struct tcp_sock *tp = tcp_sk(sk);
+-	struct dst_entry *dst = NULL;
+-	__be32 saddr = ip_hdr(skb)->saddr;
+-	__be32 daddr = ip_hdr(skb)->daddr;
+-	__u32 isn = TCP_SKB_CB(skb)->when;
+-	bool want_cookie = false, fastopen;
+-	struct flowi4 fl4;
+-	struct tcp_fastopen_cookie foc = { .len = -1 };
+-	int err;
+-
+ 	/* Never answer to SYNs send to broadcast or multicast */
+ 	if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
+ 		goto drop;
+ 
+-	/* TW buckets are converted to open requests without
+-	 * limitations, they conserve resources and peer is
+-	 * evidently real one.
+-	 */
+-	if ((sysctl_tcp_syncookies == 2 ||
+-	     inet_csk_reqsk_queue_is_full(sk)) && !isn) {
+-		want_cookie = tcp_syn_flood_action(sk, skb, "TCP");
+-		if (!want_cookie)
+-			goto drop;
+-	}
+-
+-	/* Accept backlog is full. If we have already queued enough
+-	 * of warm entries in syn queue, drop request. It is better than
+-	 * clogging syn queue with openreqs with exponentially increasing
+-	 * timeout.
+-	 */
+-	if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1) {
+-		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
+-		goto drop;
+-	}
+-
+-	req = inet_reqsk_alloc(&tcp_request_sock_ops);
+-	if (!req)
+-		goto drop;
+-
+-#ifdef CONFIG_TCP_MD5SIG
+-	tcp_rsk(req)->af_specific = &tcp_request_sock_ipv4_ops;
+-#endif
+-
+-	tcp_clear_options(&tmp_opt);
+-	tmp_opt.mss_clamp = TCP_MSS_DEFAULT;
+-	tmp_opt.user_mss  = tp->rx_opt.user_mss;
+-	tcp_parse_options(skb, &tmp_opt, 0, want_cookie ? NULL : &foc);
+-
+-	if (want_cookie && !tmp_opt.saw_tstamp)
+-		tcp_clear_options(&tmp_opt);
+-
+-	tmp_opt.tstamp_ok = tmp_opt.saw_tstamp;
+-	tcp_openreq_init(req, &tmp_opt, skb);
++	return tcp_conn_request(&tcp_request_sock_ops,
++				&tcp_request_sock_ipv4_ops, sk, skb);
+ 
+-	ireq = inet_rsk(req);
+-	ireq->ir_loc_addr = daddr;
+-	ireq->ir_rmt_addr = saddr;
+-	ireq->no_srccheck = inet_sk(sk)->transparent;
+-	ireq->opt = tcp_v4_save_options(skb);
+-	ireq->ir_mark = inet_request_mark(sk, skb);
+-
+-	if (security_inet_conn_request(sk, skb, req))
+-		goto drop_and_free;
+-
+-	if (!want_cookie || tmp_opt.tstamp_ok)
+-		TCP_ECN_create_request(req, skb, sock_net(sk));
+-
+-	if (want_cookie) {
+-		isn = cookie_v4_init_sequence(sk, skb, &req->mss);
+-		req->cookie_ts = tmp_opt.tstamp_ok;
+-	} else if (!isn) {
+-		/* VJ's idea. We save last timestamp seen
+-		 * from the destination in peer table, when entering
+-		 * state TIME-WAIT, and check against it before
+-		 * accepting new connection request.
+-		 *
+-		 * If "isn" is not zero, this request hit alive
+-		 * timewait bucket, so that all the necessary checks
+-		 * are made in the function processing timewait state.
+-		 */
+-		if (tmp_opt.saw_tstamp &&
+-		    tcp_death_row.sysctl_tw_recycle &&
+-		    (dst = inet_csk_route_req(sk, &fl4, req)) != NULL &&
+-		    fl4.daddr == saddr) {
+-			if (!tcp_peer_is_proven(req, dst, true)) {
+-				NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_PAWSPASSIVEREJECTED);
+-				goto drop_and_release;
+-			}
+-		}
+-		/* Kill the following clause, if you dislike this way. */
+-		else if (!sysctl_tcp_syncookies &&
+-			 (sysctl_max_syn_backlog - inet_csk_reqsk_queue_len(sk) <
+-			  (sysctl_max_syn_backlog >> 2)) &&
+-			 !tcp_peer_is_proven(req, dst, false)) {
+-			/* Without syncookies last quarter of
+-			 * backlog is filled with destinations,
+-			 * proven to be alive.
+-			 * It means that we continue to communicate
+-			 * to destinations, already remembered
+-			 * to the moment of synflood.
+-			 */
+-			LIMIT_NETDEBUG(KERN_DEBUG pr_fmt("drop open request from %pI4/%u\n"),
+-				       &saddr, ntohs(tcp_hdr(skb)->source));
+-			goto drop_and_release;
+-		}
+-
+-		isn = tcp_v4_init_sequence(skb);
+-	}
+-	if (!dst && (dst = inet_csk_route_req(sk, &fl4, req)) == NULL)
+-		goto drop_and_free;
+-
+-	tcp_rsk(req)->snt_isn = isn;
+-	tcp_rsk(req)->snt_synack = tcp_time_stamp;
+-	tcp_openreq_init_rwin(req, sk, dst);
+-	fastopen = !want_cookie &&
+-		   tcp_try_fastopen(sk, skb, req, &foc, dst);
+-	err = tcp_v4_send_synack(sk, dst, req,
+-				 skb_get_queue_mapping(skb), &foc);
+-	if (!fastopen) {
+-		if (err || want_cookie)
+-			goto drop_and_free;
+-
+-		tcp_rsk(req)->snt_synack = tcp_time_stamp;
+-		tcp_rsk(req)->listener = NULL;
+-		inet_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT);
+-	}
+-
+-	return 0;
+-
+-drop_and_release:
+-	dst_release(dst);
+-drop_and_free:
+-	reqsk_free(req);
+ drop:
+ 	NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
+ 	return 0;
+@@ -1497,7 +1433,7 @@ put_and_exit:
+ }
+ EXPORT_SYMBOL(tcp_v4_syn_recv_sock);
+ 
+-static struct sock *tcp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
++struct sock *tcp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
+ {
+ 	struct tcphdr *th = tcp_hdr(skb);
+ 	const struct iphdr *iph = ip_hdr(skb);
+@@ -1514,8 +1450,15 @@ static struct sock *tcp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
+ 
+ 	if (nsk) {
+ 		if (nsk->sk_state != TCP_TIME_WAIT) {
++			/* Don't lock again the meta-sk. It has been locked
++			 * before mptcp_v4_do_rcv.
++			 */
++			if (mptcp(tcp_sk(nsk)) && !is_meta_sk(sk))
++				bh_lock_sock(mptcp_meta_sk(nsk));
+ 			bh_lock_sock(nsk);
++
+ 			return nsk;
++
+ 		}
+ 		inet_twsk_put(inet_twsk(nsk));
+ 		return NULL;
+@@ -1550,6 +1493,9 @@ int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
+ 		goto discard;
+ #endif
+ 
++	if (is_meta_sk(sk))
++		return mptcp_v4_do_rcv(sk, skb);
++
+ 	if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */
+ 		struct dst_entry *dst = sk->sk_rx_dst;
+ 
+@@ -1681,7 +1627,7 @@ bool tcp_prequeue(struct sock *sk, struct sk_buff *skb)
+ 	} else if (skb_queue_len(&tp->ucopy.prequeue) == 1) {
+ 		wake_up_interruptible_sync_poll(sk_sleep(sk),
+ 					   POLLIN | POLLRDNORM | POLLRDBAND);
+-		if (!inet_csk_ack_scheduled(sk))
++		if (!inet_csk_ack_scheduled(sk) && !mptcp(tp))
+ 			inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
+ 						  (3 * tcp_rto_min(sk)) / 4,
+ 						  TCP_RTO_MAX);
+@@ -1698,7 +1644,7 @@ int tcp_v4_rcv(struct sk_buff *skb)
+ {
+ 	const struct iphdr *iph;
+ 	const struct tcphdr *th;
+-	struct sock *sk;
++	struct sock *sk, *meta_sk = NULL;
+ 	int ret;
+ 	struct net *net = dev_net(skb->dev);
+ 
+@@ -1732,18 +1678,42 @@ int tcp_v4_rcv(struct sk_buff *skb)
+ 	TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin +
+ 				    skb->len - th->doff * 4);
+ 	TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq);
++#ifdef CONFIG_MPTCP
++	TCP_SKB_CB(skb)->mptcp_flags = 0;
++	TCP_SKB_CB(skb)->dss_off = 0;
++#endif
+ 	TCP_SKB_CB(skb)->when	 = 0;
+ 	TCP_SKB_CB(skb)->ip_dsfield = ipv4_get_dsfield(iph);
+ 	TCP_SKB_CB(skb)->sacked	 = 0;
+ 
+ 	sk = __inet_lookup_skb(&tcp_hashinfo, skb, th->source, th->dest);
+-	if (!sk)
+-		goto no_tcp_socket;
+ 
+ process:
+-	if (sk->sk_state == TCP_TIME_WAIT)
++	if (sk && sk->sk_state == TCP_TIME_WAIT)
+ 		goto do_time_wait;
+ 
++#ifdef CONFIG_MPTCP
++	if (!sk && th->syn && !th->ack) {
++		int ret = mptcp_lookup_join(skb, NULL);
++
++		if (ret < 0) {
++			tcp_v4_send_reset(NULL, skb);
++			goto discard_it;
++		} else if (ret > 0) {
++			return 0;
++		}
++	}
++
++	/* Is there a pending request sock for this segment ? */
++	if ((!sk || sk->sk_state == TCP_LISTEN) && mptcp_check_req(skb, net)) {
++		if (sk)
++			sock_put(sk);
++		return 0;
++	}
++#endif
++	if (!sk)
++		goto no_tcp_socket;
++
+ 	if (unlikely(iph->ttl < inet_sk(sk)->min_ttl)) {
+ 		NET_INC_STATS_BH(net, LINUX_MIB_TCPMINTTLDROP);
+ 		goto discard_and_relse;
+@@ -1759,11 +1729,21 @@ process:
+ 	sk_mark_napi_id(sk, skb);
+ 	skb->dev = NULL;
+ 
+-	bh_lock_sock_nested(sk);
++	if (mptcp(tcp_sk(sk))) {
++		meta_sk = mptcp_meta_sk(sk);
++
++		bh_lock_sock_nested(meta_sk);
++		if (sock_owned_by_user(meta_sk))
++			skb->sk = sk;
++	} else {
++		meta_sk = sk;
++		bh_lock_sock_nested(sk);
++	}
++
+ 	ret = 0;
+-	if (!sock_owned_by_user(sk)) {
++	if (!sock_owned_by_user(meta_sk)) {
+ #ifdef CONFIG_NET_DMA
+-		struct tcp_sock *tp = tcp_sk(sk);
++		struct tcp_sock *tp = tcp_sk(meta_sk);
+ 		if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list)
+ 			tp->ucopy.dma_chan = net_dma_find_channel();
+ 		if (tp->ucopy.dma_chan)
+@@ -1771,16 +1751,16 @@ process:
+ 		else
+ #endif
+ 		{
+-			if (!tcp_prequeue(sk, skb))
++			if (!tcp_prequeue(meta_sk, skb))
+ 				ret = tcp_v4_do_rcv(sk, skb);
+ 		}
+-	} else if (unlikely(sk_add_backlog(sk, skb,
+-					   sk->sk_rcvbuf + sk->sk_sndbuf))) {
+-		bh_unlock_sock(sk);
++	} else if (unlikely(sk_add_backlog(meta_sk, skb,
++					   meta_sk->sk_rcvbuf + meta_sk->sk_sndbuf))) {
++		bh_unlock_sock(meta_sk);
+ 		NET_INC_STATS_BH(net, LINUX_MIB_TCPBACKLOGDROP);
+ 		goto discard_and_relse;
+ 	}
+-	bh_unlock_sock(sk);
++	bh_unlock_sock(meta_sk);
+ 
+ 	sock_put(sk);
+ 
+@@ -1835,6 +1815,18 @@ do_time_wait:
+ 			sk = sk2;
+ 			goto process;
+ 		}
++#ifdef CONFIG_MPTCP
++		if (th->syn && !th->ack) {
++			int ret = mptcp_lookup_join(skb, inet_twsk(sk));
++
++			if (ret < 0) {
++				tcp_v4_send_reset(NULL, skb);
++				goto discard_it;
++			} else if (ret > 0) {
++				return 0;
++			}
++		}
++#endif
+ 		/* Fall through to ACK */
+ 	}
+ 	case TCP_TW_ACK:
+@@ -1900,7 +1892,12 @@ static int tcp_v4_init_sock(struct sock *sk)
+ 
+ 	tcp_init_sock(sk);
+ 
+-	icsk->icsk_af_ops = &ipv4_specific;
++#ifdef CONFIG_MPTCP
++	if (is_mptcp_enabled(sk))
++		icsk->icsk_af_ops = &mptcp_v4_specific;
++	else
++#endif
++		icsk->icsk_af_ops = &ipv4_specific;
+ 
+ #ifdef CONFIG_TCP_MD5SIG
+ 	tcp_sk(sk)->af_specific = &tcp_sock_ipv4_specific;
+@@ -1917,6 +1914,11 @@ void tcp_v4_destroy_sock(struct sock *sk)
+ 
+ 	tcp_cleanup_congestion_control(sk);
+ 
++	if (mptcp(tp))
++		mptcp_destroy_sock(sk);
++	if (tp->inside_tk_table)
++		mptcp_hash_remove(tp);
++
+ 	/* Cleanup up the write buffer. */
+ 	tcp_write_queue_purge(sk);
+ 
+@@ -2481,6 +2483,19 @@ void tcp4_proc_exit(void)
+ }
+ #endif /* CONFIG_PROC_FS */
+ 
++#ifdef CONFIG_MPTCP
++static void tcp_v4_clear_sk(struct sock *sk, int size)
++{
++	struct tcp_sock *tp = tcp_sk(sk);
++
++	/* we do not want to clear tk_table field, because of RCU lookups */
++	sk_prot_clear_nulls(sk, offsetof(struct tcp_sock, tk_table));
++
++	size -= offsetof(struct tcp_sock, tk_table) + sizeof(tp->tk_table);
++	memset((char *)&tp->tk_table + sizeof(tp->tk_table), 0, size);
++}
++#endif
++
+ struct proto tcp_prot = {
+ 	.name			= "TCP",
+ 	.owner			= THIS_MODULE,
+@@ -2528,6 +2543,9 @@ struct proto tcp_prot = {
+ 	.destroy_cgroup		= tcp_destroy_cgroup,
+ 	.proto_cgroup		= tcp_proto_cgroup,
+ #endif
++#ifdef CONFIG_MPTCP
++	.clear_sk		= tcp_v4_clear_sk,
++#endif
+ };
+ EXPORT_SYMBOL(tcp_prot);
+ 
+diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
+index e68e0d4af6c9..ae6946857dff 100644
+--- a/net/ipv4/tcp_minisocks.c
++++ b/net/ipv4/tcp_minisocks.c
+@@ -18,11 +18,13 @@
+  *		Jorge Cwik, <jorge@×××××××××××××.net>
+  */
+ 
++#include <linux/kconfig.h>
+ #include <linux/mm.h>
+ #include <linux/module.h>
+ #include <linux/slab.h>
+ #include <linux/sysctl.h>
+ #include <linux/workqueue.h>
++#include <net/mptcp.h>
+ #include <net/tcp.h>
+ #include <net/inet_common.h>
+ #include <net/xfrm.h>
+@@ -95,10 +97,13 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb,
+ 	struct tcp_options_received tmp_opt;
+ 	struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw);
+ 	bool paws_reject = false;
++	struct mptcp_options_received mopt;
+ 
+ 	tmp_opt.saw_tstamp = 0;
+ 	if (th->doff > (sizeof(*th) >> 2) && tcptw->tw_ts_recent_stamp) {
+-		tcp_parse_options(skb, &tmp_opt, 0, NULL);
++		mptcp_init_mp_opt(&mopt);
++
++		tcp_parse_options(skb, &tmp_opt, &mopt, 0, NULL);
+ 
+ 		if (tmp_opt.saw_tstamp) {
+ 			tmp_opt.rcv_tsecr	-= tcptw->tw_ts_offset;
+@@ -106,6 +111,11 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb,
+ 			tmp_opt.ts_recent_stamp	= tcptw->tw_ts_recent_stamp;
+ 			paws_reject = tcp_paws_reject(&tmp_opt, th->rst);
+ 		}
++
++		if (unlikely(mopt.mp_fclose) && tcptw->mptcp_tw) {
++			if (mopt.mptcp_key == tcptw->mptcp_tw->loc_key)
++				goto kill_with_rst;
++		}
+ 	}
+ 
+ 	if (tw->tw_substate == TCP_FIN_WAIT2) {
+@@ -128,6 +138,16 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb,
+ 		if (!th->ack ||
+ 		    !after(TCP_SKB_CB(skb)->end_seq, tcptw->tw_rcv_nxt) ||
+ 		    TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq) {
++			/* If mptcp_is_data_fin() returns true, we are sure that
++			 * mopt has been initialized - otherwise it would not
++			 * be a DATA_FIN.
++			 */
++			if (tcptw->mptcp_tw && tcptw->mptcp_tw->meta_tw &&
++			    mptcp_is_data_fin(skb) &&
++			    TCP_SKB_CB(skb)->seq == tcptw->tw_rcv_nxt &&
++			    mopt.data_seq + 1 == (u32)tcptw->mptcp_tw->rcv_nxt)
++				return TCP_TW_ACK;
++
+ 			inet_twsk_put(tw);
+ 			return TCP_TW_SUCCESS;
+ 		}
+@@ -290,6 +310,15 @@ void tcp_time_wait(struct sock *sk, int state, int timeo)
+ 		tcptw->tw_ts_recent_stamp = tp->rx_opt.ts_recent_stamp;
+ 		tcptw->tw_ts_offset	= tp->tsoffset;
+ 
++		if (mptcp(tp)) {
++			if (mptcp_init_tw_sock(sk, tcptw)) {
++				inet_twsk_free(tw);
++				goto exit;
++			}
++		} else {
++			tcptw->mptcp_tw = NULL;
++		}
++
+ #if IS_ENABLED(CONFIG_IPV6)
+ 		if (tw->tw_family == PF_INET6) {
+ 			struct ipv6_pinfo *np = inet6_sk(sk);
+@@ -347,15 +376,18 @@ void tcp_time_wait(struct sock *sk, int state, int timeo)
+ 		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPTIMEWAITOVERFLOW);
+ 	}
+ 
++exit:
+ 	tcp_update_metrics(sk);
+ 	tcp_done(sk);
+ }
+ 
+ void tcp_twsk_destructor(struct sock *sk)
+ {
+-#ifdef CONFIG_TCP_MD5SIG
+ 	struct tcp_timewait_sock *twsk = tcp_twsk(sk);
+ 
++	if (twsk->mptcp_tw)
++		mptcp_twsk_destructor(twsk);
++#ifdef CONFIG_TCP_MD5SIG
+ 	if (twsk->tw_md5_key)
+ 		kfree_rcu(twsk->tw_md5_key, rcu);
+ #endif
+@@ -382,13 +414,14 @@ void tcp_openreq_init_rwin(struct request_sock *req,
+ 		req->window_clamp = tcp_full_space(sk);
+ 
+ 	/* tcp_full_space because it is guaranteed to be the first packet */
+-	tcp_select_initial_window(tcp_full_space(sk),
+-		mss - (ireq->tstamp_ok ? TCPOLEN_TSTAMP_ALIGNED : 0),
++	tp->ops->select_initial_window(tcp_full_space(sk),
++		mss - (ireq->tstamp_ok ? TCPOLEN_TSTAMP_ALIGNED : 0) -
++		(ireq->saw_mpc ? MPTCP_SUB_LEN_DSM_ALIGN : 0),
+ 		&req->rcv_wnd,
+ 		&req->window_clamp,
+ 		ireq->wscale_ok,
+ 		&rcv_wscale,
+-		dst_metric(dst, RTAX_INITRWND));
++		dst_metric(dst, RTAX_INITRWND), sk);
+ 	ireq->rcv_wscale = rcv_wscale;
+ }
+ EXPORT_SYMBOL(tcp_openreq_init_rwin);
+@@ -499,6 +532,8 @@ struct sock *tcp_create_openreq_child(struct sock *sk, struct request_sock *req,
+ 			newtp->rx_opt.ts_recent_stamp = 0;
+ 			newtp->tcp_header_len = sizeof(struct tcphdr);
+ 		}
++		if (ireq->saw_mpc)
++			newtp->tcp_header_len += MPTCP_SUB_LEN_DSM_ALIGN;
+ 		newtp->tsoffset = 0;
+ #ifdef CONFIG_TCP_MD5SIG
+ 		newtp->md5sig_info = NULL;	/*XXX*/
+@@ -535,16 +570,20 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
+ 			   bool fastopen)
+ {
+ 	struct tcp_options_received tmp_opt;
++	struct mptcp_options_received mopt;
+ 	struct sock *child;
+ 	const struct tcphdr *th = tcp_hdr(skb);
+ 	__be32 flg = tcp_flag_word(th) & (TCP_FLAG_RST|TCP_FLAG_SYN|TCP_FLAG_ACK);
+ 	bool paws_reject = false;
+ 
+-	BUG_ON(fastopen == (sk->sk_state == TCP_LISTEN));
++	BUG_ON(!mptcp(tcp_sk(sk)) && fastopen == (sk->sk_state == TCP_LISTEN));
+ 
+ 	tmp_opt.saw_tstamp = 0;
++
++	mptcp_init_mp_opt(&mopt);
++
+ 	if (th->doff > (sizeof(struct tcphdr)>>2)) {
+-		tcp_parse_options(skb, &tmp_opt, 0, NULL);
++		tcp_parse_options(skb, &tmp_opt, &mopt, 0, NULL);
+ 
+ 		if (tmp_opt.saw_tstamp) {
+ 			tmp_opt.ts_recent = req->ts_recent;
+@@ -583,7 +622,14 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
+ 		 *
+ 		 * Reset timer after retransmitting SYNACK, similar to
+ 		 * the idea of fast retransmit in recovery.
++		 *
++		 * Fall back to TCP if MP_CAPABLE is not set.
+ 		 */
++
++		if (inet_rsk(req)->saw_mpc && !mopt.saw_mpc)
++			inet_rsk(req)->saw_mpc = false;
++
++
+ 		if (!inet_rtx_syn_ack(sk, req))
+ 			req->expires = min(TCP_TIMEOUT_INIT << req->num_timeout,
+ 					   TCP_RTO_MAX) + jiffies;
+@@ -718,9 +764,21 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
+ 	 * socket is created, wait for troubles.
+ 	 */
+ 	child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL);
++
+ 	if (child == NULL)
+ 		goto listen_overflow;
+ 
++	if (!is_meta_sk(sk)) {
++		int ret = mptcp_check_req_master(sk, child, req, prev);
++		if (ret < 0)
++			goto listen_overflow;
++
++		/* MPTCP-supported */
++		if (!ret)
++			return tcp_sk(child)->mpcb->master_sk;
++	} else {
++		return mptcp_check_req_child(sk, child, req, prev, &mopt);
++	}
+ 	inet_csk_reqsk_queue_unlink(sk, req, prev);
+ 	inet_csk_reqsk_queue_removed(sk, req);
+ 
+@@ -746,7 +804,17 @@ embryonic_reset:
+ 		tcp_reset(sk);
+ 	}
+ 	if (!fastopen) {
+-		inet_csk_reqsk_queue_drop(sk, req, prev);
++		if (is_meta_sk(sk)) {
++			/* We want to avoid stoping the keepalive-timer and so
++			 * avoid ending up in inet_csk_reqsk_queue_removed ...
++			 */
++			inet_csk_reqsk_queue_unlink(sk, req, prev);
++			if (reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req) == 0)
++				mptcp_delete_synack_timer(sk);
++			reqsk_free(req);
++		} else {
++			inet_csk_reqsk_queue_drop(sk, req, prev);
++		}
+ 		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_EMBRYONICRSTS);
+ 	}
+ 	return NULL;
+@@ -770,8 +838,9 @@ int tcp_child_process(struct sock *parent, struct sock *child,
+ {
+ 	int ret = 0;
+ 	int state = child->sk_state;
++	struct sock *meta_sk = mptcp(tcp_sk(child)) ? mptcp_meta_sk(child) : child;
+ 
+-	if (!sock_owned_by_user(child)) {
++	if (!sock_owned_by_user(meta_sk)) {
+ 		ret = tcp_rcv_state_process(child, skb, tcp_hdr(skb),
+ 					    skb->len);
+ 		/* Wakeup parent, send SIGIO */
+@@ -782,10 +851,14 @@ int tcp_child_process(struct sock *parent, struct sock *child,
+ 		 * in main socket hash table and lock on listening
+ 		 * socket does not protect us more.
+ 		 */
+-		__sk_add_backlog(child, skb);
++		if (mptcp(tcp_sk(child)))
++			skb->sk = child;
++		__sk_add_backlog(meta_sk, skb);
+ 	}
+ 
+-	bh_unlock_sock(child);
++	if (mptcp(tcp_sk(child)))
++		bh_unlock_sock(child);
++	bh_unlock_sock(meta_sk);
+ 	sock_put(child);
+ 	return ret;
+ }
+diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
+index 179b51e6bda3..efd31b6c5784 100644
+--- a/net/ipv4/tcp_output.c
++++ b/net/ipv4/tcp_output.c
+@@ -36,6 +36,12 @@
+ 
+ #define pr_fmt(fmt) "TCP: " fmt
+ 
++#include <net/mptcp.h>
++#include <net/mptcp_v4.h>
++#if IS_ENABLED(CONFIG_IPV6)
++#include <net/mptcp_v6.h>
++#endif
++#include <net/ipv6.h>
+ #include <net/tcp.h>
+ 
+ #include <linux/compiler.h>
+@@ -68,11 +74,8 @@ int sysctl_tcp_slow_start_after_idle __read_mostly = 1;
+ unsigned int sysctl_tcp_notsent_lowat __read_mostly = UINT_MAX;
+ EXPORT_SYMBOL(sysctl_tcp_notsent_lowat);
+ 
+-static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle,
+-			   int push_one, gfp_t gfp);
+-
+ /* Account for new data that has been sent to the network. */
+-static void tcp_event_new_data_sent(struct sock *sk, const struct sk_buff *skb)
++void tcp_event_new_data_sent(struct sock *sk, const struct sk_buff *skb)
+ {
+ 	struct inet_connection_sock *icsk = inet_csk(sk);
+ 	struct tcp_sock *tp = tcp_sk(sk);
+@@ -214,7 +217,7 @@ u32 tcp_default_init_rwnd(u32 mss)
+ void tcp_select_initial_window(int __space, __u32 mss,
+ 			       __u32 *rcv_wnd, __u32 *window_clamp,
+ 			       int wscale_ok, __u8 *rcv_wscale,
+-			       __u32 init_rcv_wnd)
++			       __u32 init_rcv_wnd, const struct sock *sk)
+ {
+ 	unsigned int space = (__space < 0 ? 0 : __space);
+ 
+@@ -269,12 +272,16 @@ EXPORT_SYMBOL(tcp_select_initial_window);
+  * value can be stuffed directly into th->window for an outgoing
+  * frame.
+  */
+-static u16 tcp_select_window(struct sock *sk)
++u16 tcp_select_window(struct sock *sk)
+ {
+ 	struct tcp_sock *tp = tcp_sk(sk);
+ 	u32 old_win = tp->rcv_wnd;
+-	u32 cur_win = tcp_receive_window(tp);
+-	u32 new_win = __tcp_select_window(sk);
++	/* The window must never shrink at the meta-level. At the subflow we
++	 * have to allow this. Otherwise we may announce a window too large
++	 * for the current meta-level sk_rcvbuf.
++	 */
++	u32 cur_win = tcp_receive_window(mptcp(tp) ? tcp_sk(mptcp_meta_sk(sk)) : tp);
++	u32 new_win = tp->ops->__select_window(sk);
+ 
+ 	/* Never shrink the offered window */
+ 	if (new_win < cur_win) {
+@@ -290,6 +297,7 @@ static u16 tcp_select_window(struct sock *sk)
+ 				      LINUX_MIB_TCPWANTZEROWINDOWADV);
+ 		new_win = ALIGN(cur_win, 1 << tp->rx_opt.rcv_wscale);
+ 	}
++
+ 	tp->rcv_wnd = new_win;
+ 	tp->rcv_wup = tp->rcv_nxt;
+ 
+@@ -374,7 +382,7 @@ static inline void TCP_ECN_send(struct sock *sk, struct sk_buff *skb,
+ /* Constructs common control bits of non-data skb. If SYN/FIN is present,
+  * auto increment end seqno.
+  */
+-static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags)
++void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags)
+ {
+ 	struct skb_shared_info *shinfo = skb_shinfo(skb);
+ 
+@@ -394,7 +402,7 @@ static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags)
+ 	TCP_SKB_CB(skb)->end_seq = seq;
+ }
+ 
+-static inline bool tcp_urg_mode(const struct tcp_sock *tp)
++bool tcp_urg_mode(const struct tcp_sock *tp)
+ {
+ 	return tp->snd_una != tp->snd_up;
+ }
+@@ -404,17 +412,7 @@ static inline bool tcp_urg_mode(const struct tcp_sock *tp)
+ #define OPTION_MD5		(1 << 2)
+ #define OPTION_WSCALE		(1 << 3)
+ #define OPTION_FAST_OPEN_COOKIE	(1 << 8)
+-
+-struct tcp_out_options {
+-	u16 options;		/* bit field of OPTION_* */
+-	u16 mss;		/* 0 to disable */
+-	u8 ws;			/* window scale, 0 to disable */
+-	u8 num_sack_blocks;	/* number of SACK blocks to include */
+-	u8 hash_size;		/* bytes in hash_location */
+-	__u8 *hash_location;	/* temporary pointer, overloaded */
+-	__u32 tsval, tsecr;	/* need to include OPTION_TS */
+-	struct tcp_fastopen_cookie *fastopen_cookie;	/* Fast open cookie */
+-};
++/* Before adding here - take a look at OPTION_MPTCP in include/net/mptcp.h */
+ 
+ /* Write previously computed TCP options to the packet.
+  *
+@@ -430,7 +428,7 @@ struct tcp_out_options {
+  * (but it may well be that other scenarios fail similarly).
+  */
+ static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp,
+-			      struct tcp_out_options *opts)
++			      struct tcp_out_options *opts, struct sk_buff *skb)
+ {
+ 	u16 options = opts->options;	/* mungable copy */
+ 
+@@ -513,6 +511,9 @@ static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp,
+ 		}
+ 		ptr += (foc->len + 3) >> 2;
+ 	}
++
++	if (unlikely(OPTION_MPTCP & opts->options))
++		mptcp_options_write(ptr, tp, opts, skb);
+ }
+ 
+ /* Compute TCP options for SYN packets. This is not the final
+@@ -564,6 +565,8 @@ static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb,
+ 		if (unlikely(!(OPTION_TS & opts->options)))
+ 			remaining -= TCPOLEN_SACKPERM_ALIGNED;
+ 	}
++	if (tp->request_mptcp || mptcp(tp))
++		mptcp_syn_options(sk, opts, &remaining);
+ 
+ 	if (fastopen && fastopen->cookie.len >= 0) {
+ 		u32 need = TCPOLEN_EXP_FASTOPEN_BASE + fastopen->cookie.len;
+@@ -637,6 +640,9 @@ static unsigned int tcp_synack_options(struct sock *sk,
+ 		}
+ 	}
+ 
++	if (ireq->saw_mpc)
++		mptcp_synack_options(req, opts, &remaining);
++
+ 	return MAX_TCP_OPTION_SPACE - remaining;
+ }
+ 
+@@ -670,16 +676,22 @@ static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb
+ 		opts->tsecr = tp->rx_opt.ts_recent;
+ 		size += TCPOLEN_TSTAMP_ALIGNED;
+ 	}
++	if (mptcp(tp))
++		mptcp_established_options(sk, skb, opts, &size);
+ 
+ 	eff_sacks = tp->rx_opt.num_sacks + tp->rx_opt.dsack;
+ 	if (unlikely(eff_sacks)) {
+-		const unsigned int remaining = MAX_TCP_OPTION_SPACE - size;
+-		opts->num_sack_blocks =
+-			min_t(unsigned int, eff_sacks,
+-			      (remaining - TCPOLEN_SACK_BASE_ALIGNED) /
+-			      TCPOLEN_SACK_PERBLOCK);
+-		size += TCPOLEN_SACK_BASE_ALIGNED +
+-			opts->num_sack_blocks * TCPOLEN_SACK_PERBLOCK;
++		const unsigned remaining = MAX_TCP_OPTION_SPACE - size;
++		if (remaining < TCPOLEN_SACK_BASE_ALIGNED)
++			opts->num_sack_blocks = 0;
++		else
++			opts->num_sack_blocks =
++			    min_t(unsigned int, eff_sacks,
++				  (remaining - TCPOLEN_SACK_BASE_ALIGNED) /
++				  TCPOLEN_SACK_PERBLOCK);
++		if (opts->num_sack_blocks)
++			size += TCPOLEN_SACK_BASE_ALIGNED +
++			    opts->num_sack_blocks * TCPOLEN_SACK_PERBLOCK;
+ 	}
+ 
+ 	return size;
+@@ -711,8 +723,8 @@ static void tcp_tsq_handler(struct sock *sk)
+ 	if ((1 << sk->sk_state) &
+ 	    (TCPF_ESTABLISHED | TCPF_FIN_WAIT1 | TCPF_CLOSING |
+ 	     TCPF_CLOSE_WAIT  | TCPF_LAST_ACK))
+-		tcp_write_xmit(sk, tcp_current_mss(sk), tcp_sk(sk)->nonagle,
+-			       0, GFP_ATOMIC);
++		tcp_sk(sk)->ops->write_xmit(sk, tcp_current_mss(sk),
++					    tcp_sk(sk)->nonagle, 0, GFP_ATOMIC);
+ }
+ /*
+  * One tasklet per cpu tries to send more skbs.
+@@ -727,7 +739,7 @@ static void tcp_tasklet_func(unsigned long data)
+ 	unsigned long flags;
+ 	struct list_head *q, *n;
+ 	struct tcp_sock *tp;
+-	struct sock *sk;
++	struct sock *sk, *meta_sk;
+ 
+ 	local_irq_save(flags);
+ 	list_splice_init(&tsq->head, &list);
+@@ -738,15 +750,25 @@ static void tcp_tasklet_func(unsigned long data)
+ 		list_del(&tp->tsq_node);
+ 
+ 		sk = (struct sock *)tp;
+-		bh_lock_sock(sk);
++		meta_sk = mptcp(tp) ? mptcp_meta_sk(sk) : sk;
++		bh_lock_sock(meta_sk);
+ 
+-		if (!sock_owned_by_user(sk)) {
++		if (!sock_owned_by_user(meta_sk)) {
+ 			tcp_tsq_handler(sk);
++			if (mptcp(tp))
++				tcp_tsq_handler(meta_sk);
+ 		} else {
++			if (mptcp(tp) && sk->sk_state == TCP_CLOSE)
++				goto exit;
++
+ 			/* defer the work to tcp_release_cb() */
+ 			set_bit(TCP_TSQ_DEFERRED, &tp->tsq_flags);
++
++			if (mptcp(tp))
++				mptcp_tsq_flags(sk);
+ 		}
+-		bh_unlock_sock(sk);
++exit:
++		bh_unlock_sock(meta_sk);
+ 
+ 		clear_bit(TSQ_QUEUED, &tp->tsq_flags);
+ 		sk_free(sk);
+@@ -756,7 +778,10 @@ static void tcp_tasklet_func(unsigned long data)
+ #define TCP_DEFERRED_ALL ((1UL << TCP_TSQ_DEFERRED) |		\
+ 			  (1UL << TCP_WRITE_TIMER_DEFERRED) |	\
+ 			  (1UL << TCP_DELACK_TIMER_DEFERRED) |	\
+-			  (1UL << TCP_MTU_REDUCED_DEFERRED))
++			  (1UL << TCP_MTU_REDUCED_DEFERRED) |   \
++			  (1UL << MPTCP_PATH_MANAGER) |		\
++			  (1UL << MPTCP_SUB_DEFERRED))
++
+ /**
+  * tcp_release_cb - tcp release_sock() callback
+  * @sk: socket
+@@ -803,6 +828,13 @@ void tcp_release_cb(struct sock *sk)
+ 		sk->sk_prot->mtu_reduced(sk);
+ 		__sock_put(sk);
+ 	}
++	if (flags & (1UL << MPTCP_PATH_MANAGER)) {
++		if (tcp_sk(sk)->mpcb->pm_ops->release_sock)
++			tcp_sk(sk)->mpcb->pm_ops->release_sock(sk);
++		__sock_put(sk);
++	}
++	if (flags & (1UL << MPTCP_SUB_DEFERRED))
++		mptcp_tsq_sub_deferred(sk);
+ }
+ EXPORT_SYMBOL(tcp_release_cb);
+ 
+@@ -862,8 +894,8 @@ void tcp_wfree(struct sk_buff *skb)
+  * We are working here with either a clone of the original
+  * SKB, or a fresh unique copy made by the retransmit engine.
+  */
+-static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
+-			    gfp_t gfp_mask)
++int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
++		        gfp_t gfp_mask)
+ {
+ 	const struct inet_connection_sock *icsk = inet_csk(sk);
+ 	struct inet_sock *inet;
+@@ -933,7 +965,7 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
+ 		 */
+ 		th->window	= htons(min(tp->rcv_wnd, 65535U));
+ 	} else {
+-		th->window	= htons(tcp_select_window(sk));
++		th->window	= htons(tp->ops->select_window(sk));
+ 	}
+ 	th->check		= 0;
+ 	th->urg_ptr		= 0;
+@@ -949,7 +981,7 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
+ 		}
+ 	}
+ 
+-	tcp_options_write((__be32 *)(th + 1), tp, &opts);
++	tcp_options_write((__be32 *)(th + 1), tp, &opts, skb);
+ 	if (likely((tcb->tcp_flags & TCPHDR_SYN) == 0))
+ 		TCP_ECN_send(sk, skb, tcp_header_size);
+ 
+@@ -988,7 +1020,7 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
+  * NOTE: probe0 timer is not checked, do not forget tcp_push_pending_frames,
+  * otherwise socket can stall.
+  */
+-static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb)
++void tcp_queue_skb(struct sock *sk, struct sk_buff *skb)
+ {
+ 	struct tcp_sock *tp = tcp_sk(sk);
+ 
+@@ -1001,15 +1033,16 @@ static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb)
+ }
+ 
+ /* Initialize TSO segments for a packet. */
+-static void tcp_set_skb_tso_segs(const struct sock *sk, struct sk_buff *skb,
+-				 unsigned int mss_now)
++void tcp_set_skb_tso_segs(const struct sock *sk, struct sk_buff *skb,
++			  unsigned int mss_now)
+ {
+ 	struct skb_shared_info *shinfo = skb_shinfo(skb);
+ 
+ 	/* Make sure we own this skb before messing gso_size/gso_segs */
+ 	WARN_ON_ONCE(skb_cloned(skb));
+ 
+-	if (skb->len <= mss_now || skb->ip_summed == CHECKSUM_NONE) {
++	if (skb->len <= mss_now || (is_meta_sk(sk) && !mptcp_sk_can_gso(sk)) ||
++	    (!is_meta_sk(sk) && !sk_can_gso(sk)) || skb->ip_summed == CHECKSUM_NONE) {
+ 		/* Avoid the costly divide in the normal
+ 		 * non-TSO case.
+ 		 */
+@@ -1041,7 +1074,7 @@ static void tcp_adjust_fackets_out(struct sock *sk, const struct sk_buff *skb,
+ /* Pcount in the middle of the write queue got changed, we need to do various
+  * tweaks to fix counters
+  */
+-static void tcp_adjust_pcount(struct sock *sk, const struct sk_buff *skb, int decr)
++void tcp_adjust_pcount(struct sock *sk, const struct sk_buff *skb, int decr)
+ {
+ 	struct tcp_sock *tp = tcp_sk(sk);
+ 
+@@ -1164,7 +1197,7 @@ int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len,
+  * eventually). The difference is that pulled data not copied, but
+  * immediately discarded.
+  */
+-static void __pskb_trim_head(struct sk_buff *skb, int len)
++void __pskb_trim_head(struct sk_buff *skb, int len)
+ {
+ 	struct skb_shared_info *shinfo;
+ 	int i, k, eat;
+@@ -1205,6 +1238,9 @@ static void __pskb_trim_head(struct sk_buff *skb, int len)
+ /* Remove acked data from a packet in the transmit queue. */
+ int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len)
+ {
++	if (mptcp(tcp_sk(sk)) && !is_meta_sk(sk) && mptcp_is_data_seq(skb))
++		return mptcp_trim_head(sk, skb, len);
++
+ 	if (skb_unclone(skb, GFP_ATOMIC))
+ 		return -ENOMEM;
+ 
+@@ -1222,6 +1258,15 @@ int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len)
+ 	if (tcp_skb_pcount(skb) > 1)
+ 		tcp_set_skb_tso_segs(sk, skb, tcp_skb_mss(skb));
+ 
++#ifdef CONFIG_MPTCP
++	/* Some data got acked - we assume that the seq-number reached the dest.
++	 * Anyway, our MPTCP-option has been trimmed above - we lost it here.
++	 * Only remove the SEQ if the call does not come from a meta retransmit.
++	 */
++	if (mptcp(tcp_sk(sk)) && !is_meta_sk(sk))
++		TCP_SKB_CB(skb)->mptcp_flags &= ~MPTCPHDR_SEQ;
++#endif
++
+ 	return 0;
+ }
+ 
+@@ -1379,6 +1424,7 @@ unsigned int tcp_current_mss(struct sock *sk)
+ 
+ 	return mss_now;
+ }
++EXPORT_SYMBOL(tcp_current_mss);
+ 
+ /* RFC2861, slow part. Adjust cwnd, after it was not full during one rto.
+  * As additional protections, we do not touch cwnd in retransmission phases,
+@@ -1446,8 +1492,8 @@ static bool tcp_minshall_check(const struct tcp_sock *tp)
+  * But we can avoid doing the divide again given we already have
+  *  skb_pcount = skb->len / mss_now
+  */
+-static void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss_now,
+-				const struct sk_buff *skb)
++void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss_now,
++			 const struct sk_buff *skb)
+ {
+ 	if (skb->len < tcp_skb_pcount(skb) * mss_now)
+ 		tp->snd_sml = TCP_SKB_CB(skb)->end_seq;
+@@ -1468,11 +1514,11 @@ static bool tcp_nagle_check(bool partial, const struct tcp_sock *tp,
+ 		 (!nonagle && tp->packets_out && tcp_minshall_check(tp)));
+ }
+ /* Returns the portion of skb which can be sent right away */
+-static unsigned int tcp_mss_split_point(const struct sock *sk,
+-					const struct sk_buff *skb,
+-					unsigned int mss_now,
+-					unsigned int max_segs,
+-					int nonagle)
++unsigned int tcp_mss_split_point(const struct sock *sk,
++				 const struct sk_buff *skb,
++				 unsigned int mss_now,
++				 unsigned int max_segs,
++				 int nonagle)
+ {
+ 	const struct tcp_sock *tp = tcp_sk(sk);
+ 	u32 partial, needed, window, max_len;
+@@ -1502,13 +1548,14 @@ static unsigned int tcp_mss_split_point(const struct sock *sk,
+ /* Can at least one segment of SKB be sent right now, according to the
+  * congestion window rules?  If so, return how many segments are allowed.
+  */
+-static inline unsigned int tcp_cwnd_test(const struct tcp_sock *tp,
+-					 const struct sk_buff *skb)
++unsigned int tcp_cwnd_test(const struct tcp_sock *tp,
++			   const struct sk_buff *skb)
+ {
+ 	u32 in_flight, cwnd;
+ 
+ 	/* Don't be strict about the congestion window for the final FIN.  */
+-	if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) &&
++	if (skb &&
++	    (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) &&
+ 	    tcp_skb_pcount(skb) == 1)
+ 		return 1;
+ 
+@@ -1524,8 +1571,8 @@ static inline unsigned int tcp_cwnd_test(const struct tcp_sock *tp,
+  * This must be invoked the first time we consider transmitting
+  * SKB onto the wire.
+  */
+-static int tcp_init_tso_segs(const struct sock *sk, struct sk_buff *skb,
+-			     unsigned int mss_now)
++int tcp_init_tso_segs(const struct sock *sk, struct sk_buff *skb,
++		      unsigned int mss_now)
+ {
+ 	int tso_segs = tcp_skb_pcount(skb);
+ 
+@@ -1540,8 +1587,8 @@ static int tcp_init_tso_segs(const struct sock *sk, struct sk_buff *skb,
+ /* Return true if the Nagle test allows this packet to be
+  * sent now.
+  */
+-static inline bool tcp_nagle_test(const struct tcp_sock *tp, const struct sk_buff *skb,
+-				  unsigned int cur_mss, int nonagle)
++bool tcp_nagle_test(const struct tcp_sock *tp, const struct sk_buff *skb,
++		    unsigned int cur_mss, int nonagle)
+ {
+ 	/* Nagle rule does not apply to frames, which sit in the middle of the
+ 	 * write_queue (they have no chances to get new data).
+@@ -1553,7 +1600,8 @@ static inline bool tcp_nagle_test(const struct tcp_sock *tp, const struct sk_buf
+ 		return true;
+ 
+ 	/* Don't use the nagle rule for urgent data (or for the final FIN). */
+-	if (tcp_urg_mode(tp) || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN))
++	if (tcp_urg_mode(tp) || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) ||
++	    mptcp_is_data_fin(skb))
+ 		return true;
+ 
+ 	if (!tcp_nagle_check(skb->len < cur_mss, tp, nonagle))
+@@ -1563,9 +1611,8 @@ static inline bool tcp_nagle_test(const struct tcp_sock *tp, const struct sk_buf
+ }
+ 
+ /* Does at least the first segment of SKB fit into the send window? */
+-static bool tcp_snd_wnd_test(const struct tcp_sock *tp,
+-			     const struct sk_buff *skb,
+-			     unsigned int cur_mss)
++bool tcp_snd_wnd_test(const struct tcp_sock *tp, const struct sk_buff *skb,
++		      unsigned int cur_mss)
+ {
+ 	u32 end_seq = TCP_SKB_CB(skb)->end_seq;
+ 
+@@ -1676,7 +1723,7 @@ static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb,
+ 	u32 send_win, cong_win, limit, in_flight;
+ 	int win_divisor;
+ 
+-	if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
++	if ((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) || mptcp_is_data_fin(skb))
+ 		goto send_now;
+ 
+ 	if (icsk->icsk_ca_state != TCP_CA_Open)
+@@ -1888,7 +1935,7 @@ static int tcp_mtu_probe(struct sock *sk)
+  * Returns true, if no segments are in flight and we have queued segments,
+  * but cannot send anything now because of SWS or another problem.
+  */
+-static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle,
++bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle,
+ 			   int push_one, gfp_t gfp)
+ {
+ 	struct tcp_sock *tp = tcp_sk(sk);
+@@ -1900,7 +1947,11 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle,
+ 
+ 	sent_pkts = 0;
+ 
+-	if (!push_one) {
++	/* pmtu not yet supported with MPTCP. Should be possible, by early
++	 * exiting the loop inside tcp_mtu_probe, making sure that only one
++	 * single DSS-mapping gets probed.
++	 */
++	if (!push_one && !mptcp(tp)) {
+ 		/* Do MTU probing. */
+ 		result = tcp_mtu_probe(sk);
+ 		if (!result) {
+@@ -2099,7 +2150,8 @@ void tcp_send_loss_probe(struct sock *sk)
+ 	int err = -1;
+ 
+ 	if (tcp_send_head(sk) != NULL) {
+-		err = tcp_write_xmit(sk, mss, TCP_NAGLE_OFF, 2, GFP_ATOMIC);
++		err = tp->ops->write_xmit(sk, mss, TCP_NAGLE_OFF, 2,
++					  GFP_ATOMIC);
+ 		goto rearm_timer;
+ 	}
+ 
+@@ -2159,8 +2211,8 @@ void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
+ 	if (unlikely(sk->sk_state == TCP_CLOSE))
+ 		return;
+ 
+-	if (tcp_write_xmit(sk, cur_mss, nonagle, 0,
+-			   sk_gfp_atomic(sk, GFP_ATOMIC)))
++	if (tcp_sk(sk)->ops->write_xmit(sk, cur_mss, nonagle, 0,
++					sk_gfp_atomic(sk, GFP_ATOMIC)))
+ 		tcp_check_probe_timer(sk);
+ }
+ 
+@@ -2173,7 +2225,8 @@ void tcp_push_one(struct sock *sk, unsigned int mss_now)
+ 
+ 	BUG_ON(!skb || skb->len < mss_now);
+ 
+-	tcp_write_xmit(sk, mss_now, TCP_NAGLE_PUSH, 1, sk->sk_allocation);
++	tcp_sk(sk)->ops->write_xmit(sk, mss_now, TCP_NAGLE_PUSH, 1,
++				    sk->sk_allocation);
+ }
+ 
+ /* This function returns the amount that we can raise the
+@@ -2386,6 +2439,10 @@ static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *to,
+ 	if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)
+ 		return;
+ 
++	/* Currently not supported for MPTCP - but it should be possible */
++	if (mptcp(tp))
++		return;
++
+ 	tcp_for_write_queue_from_safe(skb, tmp, sk) {
+ 		if (!tcp_can_collapse(sk, skb))
+ 			break;
+@@ -2843,7 +2900,7 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
+ 
+ 	/* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */
+ 	th->window = htons(min(req->rcv_wnd, 65535U));
+-	tcp_options_write((__be32 *)(th + 1), tp, &opts);
++	tcp_options_write((__be32 *)(th + 1), tp, &opts, skb);
+ 	th->doff = (tcp_header_size >> 2);
+ 	TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_OUTSEGS);
+ 
+@@ -2897,13 +2954,13 @@ static void tcp_connect_init(struct sock *sk)
+ 	    (tp->window_clamp > tcp_full_space(sk) || tp->window_clamp == 0))
+ 		tp->window_clamp = tcp_full_space(sk);
+ 
+-	tcp_select_initial_window(tcp_full_space(sk),
+-				  tp->advmss - (tp->rx_opt.ts_recent_stamp ? tp->tcp_header_len - sizeof(struct tcphdr) : 0),
+-				  &tp->rcv_wnd,
+-				  &tp->window_clamp,
+-				  sysctl_tcp_window_scaling,
+-				  &rcv_wscale,
+-				  dst_metric(dst, RTAX_INITRWND));
++	tp->ops->select_initial_window(tcp_full_space(sk),
++				       tp->advmss - (tp->rx_opt.ts_recent_stamp ? tp->tcp_header_len - sizeof(struct tcphdr) : 0),
++				       &tp->rcv_wnd,
++				       &tp->window_clamp,
++				       sysctl_tcp_window_scaling,
++				       &rcv_wscale,
++				       dst_metric(dst, RTAX_INITRWND), sk);
+ 
+ 	tp->rx_opt.rcv_wscale = rcv_wscale;
+ 	tp->rcv_ssthresh = tp->rcv_wnd;
+@@ -2927,6 +2984,36 @@ static void tcp_connect_init(struct sock *sk)
+ 	inet_csk(sk)->icsk_rto = TCP_TIMEOUT_INIT;
+ 	inet_csk(sk)->icsk_retransmits = 0;
+ 	tcp_clear_retrans(tp);
++
++#ifdef CONFIG_MPTCP
++	if (sysctl_mptcp_enabled && mptcp_doit(sk)) {
++		if (is_master_tp(tp)) {
++			tp->request_mptcp = 1;
++			mptcp_connect_init(sk);
++		} else if (tp->mptcp) {
++			struct inet_sock *inet	= inet_sk(sk);
++
++			tp->mptcp->snt_isn	= tp->write_seq;
++			tp->mptcp->init_rcv_wnd	= tp->rcv_wnd;
++
++			/* Set nonce for new subflows */
++			if (sk->sk_family == AF_INET)
++				tp->mptcp->mptcp_loc_nonce = mptcp_v4_get_nonce(
++							inet->inet_saddr,
++							inet->inet_daddr,
++							inet->inet_sport,
++							inet->inet_dport);
++#if IS_ENABLED(CONFIG_IPV6)
++			else
++				tp->mptcp->mptcp_loc_nonce = mptcp_v6_get_nonce(
++						inet6_sk(sk)->saddr.s6_addr32,
++						sk->sk_v6_daddr.s6_addr32,
++						inet->inet_sport,
++						inet->inet_dport);
++#endif
++		}
++	}
++#endif
+ }
+ 
+ static void tcp_connect_queue_skb(struct sock *sk, struct sk_buff *skb)
+@@ -3176,6 +3263,7 @@ void tcp_send_ack(struct sock *sk)
+ 	TCP_SKB_CB(buff)->when = tcp_time_stamp;
+ 	tcp_transmit_skb(sk, buff, 0, sk_gfp_atomic(sk, GFP_ATOMIC));
+ }
++EXPORT_SYMBOL(tcp_send_ack);
+ 
+ /* This routine sends a packet with an out of date sequence
+  * number. It assumes the other end will try to ack it.
+@@ -3188,7 +3276,7 @@ void tcp_send_ack(struct sock *sk)
+  * one is with SEG.SEQ=SND.UNA to deliver urgent pointer, another is
+  * out-of-date with SND.UNA-1 to probe window.
+  */
+-static int tcp_xmit_probe_skb(struct sock *sk, int urgent)
++int tcp_xmit_probe_skb(struct sock *sk, int urgent)
+ {
+ 	struct tcp_sock *tp = tcp_sk(sk);
+ 	struct sk_buff *skb;
+@@ -3270,7 +3358,7 @@ void tcp_send_probe0(struct sock *sk)
+ 	struct tcp_sock *tp = tcp_sk(sk);
+ 	int err;
+ 
+-	err = tcp_write_wakeup(sk);
++	err = tp->ops->write_wakeup(sk);
+ 
+ 	if (tp->packets_out || !tcp_send_head(sk)) {
+ 		/* Cancel probe timer, if it is not required. */
+@@ -3301,3 +3389,18 @@ void tcp_send_probe0(struct sock *sk)
+ 					  TCP_RTO_MAX);
+ 	}
+ }
++
++int tcp_rtx_synack(struct sock *sk, struct request_sock *req)
++{
++	const struct tcp_request_sock_ops *af_ops = tcp_rsk(req)->af_specific;
++	struct flowi fl;
++	int res;
++
++	res = af_ops->send_synack(sk, NULL, &fl, req, 0, NULL);
++	if (!res) {
++		TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_RETRANSSEGS);
++		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPSYNRETRANS);
++	}
++	return res;
++}
++EXPORT_SYMBOL(tcp_rtx_synack);
+diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
+index 286227abed10..966b873cbf3e 100644
+--- a/net/ipv4/tcp_timer.c
++++ b/net/ipv4/tcp_timer.c
+@@ -20,6 +20,7 @@
+ 
+ #include <linux/module.h>
+ #include <linux/gfp.h>
++#include <net/mptcp.h>
+ #include <net/tcp.h>
+ 
+ int sysctl_tcp_syn_retries __read_mostly = TCP_SYN_RETRIES;
+@@ -32,7 +33,7 @@ int sysctl_tcp_retries2 __read_mostly = TCP_RETR2;
+ int sysctl_tcp_orphan_retries __read_mostly;
+ int sysctl_tcp_thin_linear_timeouts __read_mostly;
+ 
+-static void tcp_write_err(struct sock *sk)
++void tcp_write_err(struct sock *sk)
+ {
+ 	sk->sk_err = sk->sk_err_soft ? : ETIMEDOUT;
+ 	sk->sk_error_report(sk);
+@@ -74,7 +75,7 @@ static int tcp_out_of_resources(struct sock *sk, int do_reset)
+ 		    (!tp->snd_wnd && !tp->packets_out))
+ 			do_reset = 1;
+ 		if (do_reset)
+-			tcp_send_active_reset(sk, GFP_ATOMIC);
++			tp->ops->send_active_reset(sk, GFP_ATOMIC);
+ 		tcp_done(sk);
+ 		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPABORTONMEMORY);
+ 		return 1;
+@@ -124,10 +125,8 @@ static void tcp_mtu_probing(struct inet_connection_sock *icsk, struct sock *sk)
+  * retransmissions with an initial RTO of TCP_RTO_MIN or TCP_TIMEOUT_INIT if
+  * syn_set flag is set.
+  */
+-static bool retransmits_timed_out(struct sock *sk,
+-				  unsigned int boundary,
+-				  unsigned int timeout,
+-				  bool syn_set)
++bool retransmits_timed_out(struct sock *sk, unsigned int boundary,
++			   unsigned int timeout, bool syn_set)
+ {
+ 	unsigned int linear_backoff_thresh, start_ts;
+ 	unsigned int rto_base = syn_set ? TCP_TIMEOUT_INIT : TCP_RTO_MIN;
+@@ -153,7 +152,7 @@ static bool retransmits_timed_out(struct sock *sk,
+ }
+ 
+ /* A write timeout has occurred. Process the after effects. */
+-static int tcp_write_timeout(struct sock *sk)
++int tcp_write_timeout(struct sock *sk)
+ {
+ 	struct inet_connection_sock *icsk = inet_csk(sk);
+ 	struct tcp_sock *tp = tcp_sk(sk);
+@@ -171,6 +170,10 @@ static int tcp_write_timeout(struct sock *sk)
+ 		}
+ 		retry_until = icsk->icsk_syn_retries ? : sysctl_tcp_syn_retries;
+ 		syn_set = true;
++		/* Stop retransmitting MP_CAPABLE options in SYN if timed out. */
++		if (tcp_sk(sk)->request_mptcp &&
++		    icsk->icsk_retransmits >= mptcp_sysctl_syn_retries())
++			tcp_sk(sk)->request_mptcp = 0;
+ 	} else {
+ 		if (retransmits_timed_out(sk, sysctl_tcp_retries1, 0, 0)) {
+ 			/* Black hole detection */
+@@ -251,18 +254,22 @@ out:
+ static void tcp_delack_timer(unsigned long data)
+ {
+ 	struct sock *sk = (struct sock *)data;
++	struct tcp_sock *tp = tcp_sk(sk);
++	struct sock *meta_sk = mptcp(tp) ? mptcp_meta_sk(sk) : sk;
+ 
+-	bh_lock_sock(sk);
+-	if (!sock_owned_by_user(sk)) {
++	bh_lock_sock(meta_sk);
++	if (!sock_owned_by_user(meta_sk)) {
+ 		tcp_delack_timer_handler(sk);
+ 	} else {
+ 		inet_csk(sk)->icsk_ack.blocked = 1;
+-		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_DELAYEDACKLOCKED);
++		NET_INC_STATS_BH(sock_net(meta_sk), LINUX_MIB_DELAYEDACKLOCKED);
+ 		/* deleguate our work to tcp_release_cb() */
+ 		if (!test_and_set_bit(TCP_DELACK_TIMER_DEFERRED, &tcp_sk(sk)->tsq_flags))
+ 			sock_hold(sk);
++		if (mptcp(tp))
++			mptcp_tsq_flags(sk);
+ 	}
+-	bh_unlock_sock(sk);
++	bh_unlock_sock(meta_sk);
+ 	sock_put(sk);
+ }
+ 
+@@ -479,6 +486,10 @@ out_reset_timer:
+ 		__sk_dst_reset(sk);
+ 
+ out:;
++	if (mptcp(tp)) {
++		mptcp_reinject_data(sk, 1);
++		mptcp_set_rto(sk);
++	}
+ }
+ 
+ void tcp_write_timer_handler(struct sock *sk)
+@@ -505,7 +516,7 @@ void tcp_write_timer_handler(struct sock *sk)
+ 		break;
+ 	case ICSK_TIME_RETRANS:
+ 		icsk->icsk_pending = 0;
+-		tcp_retransmit_timer(sk);
++		tcp_sk(sk)->ops->retransmit_timer(sk);
+ 		break;
+ 	case ICSK_TIME_PROBE0:
+ 		icsk->icsk_pending = 0;
+@@ -520,16 +531,19 @@ out:
+ static void tcp_write_timer(unsigned long data)
+ {
+ 	struct sock *sk = (struct sock *)data;
++	struct sock *meta_sk = mptcp(tcp_sk(sk)) ? mptcp_meta_sk(sk) : sk;
+ 
+-	bh_lock_sock(sk);
+-	if (!sock_owned_by_user(sk)) {
++	bh_lock_sock(meta_sk);
++	if (!sock_owned_by_user(meta_sk)) {
+ 		tcp_write_timer_handler(sk);
+ 	} else {
+ 		/* deleguate our work to tcp_release_cb() */
+ 		if (!test_and_set_bit(TCP_WRITE_TIMER_DEFERRED, &tcp_sk(sk)->tsq_flags))
+ 			sock_hold(sk);
++		if (mptcp(tcp_sk(sk)))
++			mptcp_tsq_flags(sk);
+ 	}
+-	bh_unlock_sock(sk);
++	bh_unlock_sock(meta_sk);
+ 	sock_put(sk);
+ }
+ 
+@@ -566,11 +580,12 @@ static void tcp_keepalive_timer (unsigned long data)
+ 	struct sock *sk = (struct sock *) data;
+ 	struct inet_connection_sock *icsk = inet_csk(sk);
+ 	struct tcp_sock *tp = tcp_sk(sk);
++	struct sock *meta_sk = mptcp(tp) ? mptcp_meta_sk(sk) : sk;
+ 	u32 elapsed;
+ 
+ 	/* Only process if socket is not in use. */
+-	bh_lock_sock(sk);
+-	if (sock_owned_by_user(sk)) {
++	bh_lock_sock(meta_sk);
++	if (sock_owned_by_user(meta_sk)) {
+ 		/* Try again later. */
+ 		inet_csk_reset_keepalive_timer (sk, HZ/20);
+ 		goto out;
+@@ -581,16 +596,38 @@ static void tcp_keepalive_timer (unsigned long data)
+ 		goto out;
+ 	}
+ 
++	if (tp->send_mp_fclose) {
++		/* MUST do this before tcp_write_timeout, because retrans_stamp
++		 * may have been set to 0 in another part while we are
++		 * retransmitting MP_FASTCLOSE. Then, we would crash, because
++		 * retransmits_timed_out accesses the meta-write-queue.
++		 *
++		 * We make sure that the timestamp is != 0.
++		 */
++		if (!tp->retrans_stamp)
++			tp->retrans_stamp = tcp_time_stamp ? : 1;
++
++		if (tcp_write_timeout(sk))
++			goto out;
++
++		tcp_send_ack(sk);
++		icsk->icsk_retransmits++;
++
++		icsk->icsk_rto = min(icsk->icsk_rto << 1, TCP_RTO_MAX);
++		elapsed = icsk->icsk_rto;
++		goto resched;
++	}
++
+ 	if (sk->sk_state == TCP_FIN_WAIT2 && sock_flag(sk, SOCK_DEAD)) {
+ 		if (tp->linger2 >= 0) {
+ 			const int tmo = tcp_fin_time(sk) - TCP_TIMEWAIT_LEN;
+ 
+ 			if (tmo > 0) {
+-				tcp_time_wait(sk, TCP_FIN_WAIT2, tmo);
++				tp->ops->time_wait(sk, TCP_FIN_WAIT2, tmo);
+ 				goto out;
+ 			}
+ 		}
+-		tcp_send_active_reset(sk, GFP_ATOMIC);
++		tp->ops->send_active_reset(sk, GFP_ATOMIC);
+ 		goto death;
+ 	}
+ 
+@@ -614,11 +651,11 @@ static void tcp_keepalive_timer (unsigned long data)
+ 		    icsk->icsk_probes_out > 0) ||
+ 		    (icsk->icsk_user_timeout == 0 &&
+ 		    icsk->icsk_probes_out >= keepalive_probes(tp))) {
+-			tcp_send_active_reset(sk, GFP_ATOMIC);
++			tp->ops->send_active_reset(sk, GFP_ATOMIC);
+ 			tcp_write_err(sk);
+ 			goto out;
+ 		}
+-		if (tcp_write_wakeup(sk) <= 0) {
++		if (tp->ops->write_wakeup(sk) <= 0) {
+ 			icsk->icsk_probes_out++;
+ 			elapsed = keepalive_intvl_when(tp);
+ 		} else {
+@@ -642,7 +679,7 @@ death:
+ 	tcp_done(sk);
+ 
+ out:
+-	bh_unlock_sock(sk);
++	bh_unlock_sock(meta_sk);
+ 	sock_put(sk);
+ }
+ 
+diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
+index 5667b3003af9..7139c2973fd2 100644
+--- a/net/ipv6/addrconf.c
++++ b/net/ipv6/addrconf.c
+@@ -760,6 +760,7 @@ void inet6_ifa_finish_destroy(struct inet6_ifaddr *ifp)
+ 
+ 	kfree_rcu(ifp, rcu);
+ }
++EXPORT_SYMBOL(inet6_ifa_finish_destroy);
+ 
+ static void
+ ipv6_link_dev_addr(struct inet6_dev *idev, struct inet6_ifaddr *ifp)
+diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
+index 7cb4392690dd..7057afbca4df 100644
+--- a/net/ipv6/af_inet6.c
++++ b/net/ipv6/af_inet6.c
+@@ -97,8 +97,7 @@ static __inline__ struct ipv6_pinfo *inet6_sk_generic(struct sock *sk)
+ 	return (struct ipv6_pinfo *)(((u8 *)sk) + offset);
+ }
+ 
+-static int inet6_create(struct net *net, struct socket *sock, int protocol,
+-			int kern)
++int inet6_create(struct net *net, struct socket *sock, int protocol, int kern)
+ {
+ 	struct inet_sock *inet;
+ 	struct ipv6_pinfo *np;
+diff --git a/net/ipv6/inet6_connection_sock.c b/net/ipv6/inet6_connection_sock.c
+index a245e5ddffbd..99c892b8992d 100644
+--- a/net/ipv6/inet6_connection_sock.c
++++ b/net/ipv6/inet6_connection_sock.c
+@@ -96,8 +96,8 @@ struct dst_entry *inet6_csk_route_req(struct sock *sk,
+ /*
+  * request_sock (formerly open request) hash tables.
+  */
+-static u32 inet6_synq_hash(const struct in6_addr *raddr, const __be16 rport,
+-			   const u32 rnd, const u32 synq_hsize)
++u32 inet6_synq_hash(const struct in6_addr *raddr, const __be16 rport,
++		    const u32 rnd, const u32 synq_hsize)
+ {
+ 	u32 c;
+ 
+diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
+index edb58aff4ae7..ea4d9fda0927 100644
+--- a/net/ipv6/ipv6_sockglue.c
++++ b/net/ipv6/ipv6_sockglue.c
+@@ -48,6 +48,8 @@
+ #include <net/addrconf.h>
+ #include <net/inet_common.h>
+ #include <net/tcp.h>
++#include <net/mptcp.h>
++#include <net/mptcp_v4.h>
+ #include <net/udp.h>
+ #include <net/udplite.h>
+ #include <net/xfrm.h>
+@@ -196,7 +198,12 @@ static int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
+ 				sock_prot_inuse_add(net, &tcp_prot, 1);
+ 				local_bh_enable();
+ 				sk->sk_prot = &tcp_prot;
+-				icsk->icsk_af_ops = &ipv4_specific;
++#ifdef CONFIG_MPTCP
++				if (is_mptcp_enabled(sk))
++					icsk->icsk_af_ops = &mptcp_v4_specific;
++				else
++#endif
++					icsk->icsk_af_ops = &ipv4_specific;
+ 				sk->sk_socket->ops = &inet_stream_ops;
+ 				sk->sk_family = PF_INET;
+ 				tcp_sync_mss(sk, icsk->icsk_pmtu_cookie);
+diff --git a/net/ipv6/syncookies.c b/net/ipv6/syncookies.c
+index a822b880689b..b2b38869d795 100644
+--- a/net/ipv6/syncookies.c
++++ b/net/ipv6/syncookies.c
+@@ -181,13 +181,13 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
+ 
+ 	/* check for timestamp cookie support */
+ 	memset(&tcp_opt, 0, sizeof(tcp_opt));
+-	tcp_parse_options(skb, &tcp_opt, 0, NULL);
++	tcp_parse_options(skb, &tcp_opt, NULL, 0, NULL);
+ 
+ 	if (!cookie_check_timestamp(&tcp_opt, sock_net(sk), &ecn_ok))
+ 		goto out;
+ 
+ 	ret = NULL;
+-	req = inet6_reqsk_alloc(&tcp6_request_sock_ops);
++	req = inet_reqsk_alloc(&tcp6_request_sock_ops);
+ 	if (!req)
+ 		goto out;
+ 
+@@ -255,10 +255,10 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
+ 	}
+ 
+ 	req->window_clamp = tp->window_clamp ? :dst_metric(dst, RTAX_WINDOW);
+-	tcp_select_initial_window(tcp_full_space(sk), req->mss,
+-				  &req->rcv_wnd, &req->window_clamp,
+-				  ireq->wscale_ok, &rcv_wscale,
+-				  dst_metric(dst, RTAX_INITRWND));
++	tp->ops->select_initial_window(tcp_full_space(sk), req->mss,
++				       &req->rcv_wnd, &req->window_clamp,
++				       ireq->wscale_ok, &rcv_wscale,
++				       dst_metric(dst, RTAX_INITRWND), sk);
+ 
+ 	ireq->rcv_wscale = rcv_wscale;
+ 
+diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
+index 229239ad96b1..fda94d71666e 100644
+--- a/net/ipv6/tcp_ipv6.c
++++ b/net/ipv6/tcp_ipv6.c
+@@ -63,6 +63,8 @@
+ #include <net/inet_common.h>
+ #include <net/secure_seq.h>
+ #include <net/tcp_memcontrol.h>
++#include <net/mptcp.h>
++#include <net/mptcp_v6.h>
+ #include <net/busy_poll.h>
+ 
+ #include <linux/proc_fs.h>
+@@ -71,12 +73,6 @@
+ #include <linux/crypto.h>
+ #include <linux/scatterlist.h>
+ 
+-static void	tcp_v6_send_reset(struct sock *sk, struct sk_buff *skb);
+-static void	tcp_v6_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
+-				      struct request_sock *req);
+-
+-static int	tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb);
+-
+ static const struct inet_connection_sock_af_ops ipv6_mapped;
+ static const struct inet_connection_sock_af_ops ipv6_specific;
+ #ifdef CONFIG_TCP_MD5SIG
+@@ -90,7 +86,7 @@ static struct tcp_md5sig_key *tcp_v6_md5_do_lookup(struct sock *sk,
+ }
+ #endif
+ 
+-static void inet6_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb)
++void inet6_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb)
+ {
+ 	struct dst_entry *dst = skb_dst(skb);
+ 	const struct rt6_info *rt = (const struct rt6_info *)dst;
+@@ -102,10 +98,11 @@ static void inet6_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb)
+ 		inet6_sk(sk)->rx_dst_cookie = rt->rt6i_node->fn_sernum;
+ }
+ 
+-static void tcp_v6_hash(struct sock *sk)
++void tcp_v6_hash(struct sock *sk)
+ {
+ 	if (sk->sk_state != TCP_CLOSE) {
+-		if (inet_csk(sk)->icsk_af_ops == &ipv6_mapped) {
++		if (inet_csk(sk)->icsk_af_ops == &ipv6_mapped ||
++		    inet_csk(sk)->icsk_af_ops == &mptcp_v6_mapped) {
+ 			tcp_prot.hash(sk);
+ 			return;
+ 		}
+@@ -115,7 +112,7 @@ static void tcp_v6_hash(struct sock *sk)
+ 	}
+ }
+ 
+-static __u32 tcp_v6_init_sequence(const struct sk_buff *skb)
++__u32 tcp_v6_init_sequence(const struct sk_buff *skb)
+ {
+ 	return secure_tcpv6_sequence_number(ipv6_hdr(skb)->daddr.s6_addr32,
+ 					    ipv6_hdr(skb)->saddr.s6_addr32,
+@@ -123,7 +120,7 @@ static __u32 tcp_v6_init_sequence(const struct sk_buff *skb)
+ 					    tcp_hdr(skb)->source);
+ }
+ 
+-static int tcp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
++int tcp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
+ 			  int addr_len)
+ {
+ 	struct sockaddr_in6 *usin = (struct sockaddr_in6 *) uaddr;
+@@ -215,7 +212,12 @@ static int tcp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
+ 		sin.sin_port = usin->sin6_port;
+ 		sin.sin_addr.s_addr = usin->sin6_addr.s6_addr32[3];
+ 
+-		icsk->icsk_af_ops = &ipv6_mapped;
++#ifdef CONFIG_MPTCP
++		if (is_mptcp_enabled(sk))
++			icsk->icsk_af_ops = &mptcp_v6_mapped;
++		else
++#endif
++			icsk->icsk_af_ops = &ipv6_mapped;
+ 		sk->sk_backlog_rcv = tcp_v4_do_rcv;
+ #ifdef CONFIG_TCP_MD5SIG
+ 		tp->af_specific = &tcp_sock_ipv6_mapped_specific;
+@@ -225,7 +227,12 @@ static int tcp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
+ 
+ 		if (err) {
+ 			icsk->icsk_ext_hdr_len = exthdrlen;
+-			icsk->icsk_af_ops = &ipv6_specific;
++#ifdef CONFIG_MPTCP
++			if (is_mptcp_enabled(sk))
++				icsk->icsk_af_ops = &mptcp_v6_specific;
++			else
++#endif
++				icsk->icsk_af_ops = &ipv6_specific;
+ 			sk->sk_backlog_rcv = tcp_v6_do_rcv;
+ #ifdef CONFIG_TCP_MD5SIG
+ 			tp->af_specific = &tcp_sock_ipv6_specific;
+@@ -337,7 +344,7 @@ static void tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
+ 	const struct ipv6hdr *hdr = (const struct ipv6hdr *)skb->data;
+ 	const struct tcphdr *th = (struct tcphdr *)(skb->data+offset);
+ 	struct ipv6_pinfo *np;
+-	struct sock *sk;
++	struct sock *sk, *meta_sk;
+ 	int err;
+ 	struct tcp_sock *tp;
+ 	struct request_sock *fastopen;
+@@ -358,8 +365,14 @@ static void tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
+ 		return;
+ 	}
+ 
+-	bh_lock_sock(sk);
+-	if (sock_owned_by_user(sk) && type != ICMPV6_PKT_TOOBIG)
++	tp = tcp_sk(sk);
++	if (mptcp(tp))
++		meta_sk = mptcp_meta_sk(sk);
++	else
++		meta_sk = sk;
++
++	bh_lock_sock(meta_sk);
++	if (sock_owned_by_user(meta_sk) && type != ICMPV6_PKT_TOOBIG)
+ 		NET_INC_STATS_BH(net, LINUX_MIB_LOCKDROPPEDICMPS);
+ 
+ 	if (sk->sk_state == TCP_CLOSE)
+@@ -370,7 +383,6 @@ static void tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
+ 		goto out;
+ 	}
+ 
+-	tp = tcp_sk(sk);
+ 	seq = ntohl(th->seq);
+ 	/* XXX (TFO) - tp->snd_una should be ISN (tcp_create_openreq_child() */
+ 	fastopen = tp->fastopen_rsk;
+@@ -403,11 +415,15 @@ static void tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
+ 			goto out;
+ 
+ 		tp->mtu_info = ntohl(info);
+-		if (!sock_owned_by_user(sk))
++		if (!sock_owned_by_user(meta_sk))
+ 			tcp_v6_mtu_reduced(sk);
+-		else if (!test_and_set_bit(TCP_MTU_REDUCED_DEFERRED,
++		else {
++			if (!test_and_set_bit(TCP_MTU_REDUCED_DEFERRED,
+ 					   &tp->tsq_flags))
+-			sock_hold(sk);
++				sock_hold(sk);
++			if (mptcp(tp))
++				mptcp_tsq_flags(sk);
++		}
+ 		goto out;
+ 	}
+ 
+@@ -417,7 +433,7 @@ static void tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
+ 	switch (sk->sk_state) {
+ 		struct request_sock *req, **prev;
+ 	case TCP_LISTEN:
+-		if (sock_owned_by_user(sk))
++		if (sock_owned_by_user(meta_sk))
+ 			goto out;
+ 
+ 		req = inet6_csk_search_req(sk, &prev, th->dest, &hdr->daddr,
+@@ -447,7 +463,7 @@ static void tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
+ 		if (fastopen && fastopen->sk == NULL)
+ 			break;
+ 
+-		if (!sock_owned_by_user(sk)) {
++		if (!sock_owned_by_user(meta_sk)) {
+ 			sk->sk_err = err;
+ 			sk->sk_error_report(sk);		/* Wake people up to see the error (see connect in sock.c) */
+ 
+@@ -457,26 +473,27 @@ static void tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
+ 		goto out;
+ 	}
+ 
+-	if (!sock_owned_by_user(sk) && np->recverr) {
++	if (!sock_owned_by_user(meta_sk) && np->recverr) {
+ 		sk->sk_err = err;
+ 		sk->sk_error_report(sk);
+ 	} else
+ 		sk->sk_err_soft = err;
+ 
+ out:
+-	bh_unlock_sock(sk);
++	bh_unlock_sock(meta_sk);
+ 	sock_put(sk);
+ }
+ 
+ 
+-static int tcp_v6_send_synack(struct sock *sk, struct dst_entry *dst,
+-			      struct flowi6 *fl6,
+-			      struct request_sock *req,
+-			      u16 queue_mapping,
+-			      struct tcp_fastopen_cookie *foc)
++int tcp_v6_send_synack(struct sock *sk, struct dst_entry *dst,
++		       struct flowi *fl,
++		       struct request_sock *req,
++		       u16 queue_mapping,
++		       struct tcp_fastopen_cookie *foc)
+ {
+ 	struct inet_request_sock *ireq = inet_rsk(req);
+ 	struct ipv6_pinfo *np = inet6_sk(sk);
++	struct flowi6 *fl6 = &fl->u.ip6;
+ 	struct sk_buff *skb;
+ 	int err = -ENOMEM;
+ 
+@@ -497,18 +514,21 @@ static int tcp_v6_send_synack(struct sock *sk, struct dst_entry *dst,
+ 		skb_set_queue_mapping(skb, queue_mapping);
+ 		err = ip6_xmit(sk, skb, fl6, np->opt, np->tclass);
+ 		err = net_xmit_eval(err);
++		if (!tcp_rsk(req)->snt_synack && !err)
++			tcp_rsk(req)->snt_synack = tcp_time_stamp;
+ 	}
+ 
+ done:
+ 	return err;
+ }
+ 
+-static int tcp_v6_rtx_synack(struct sock *sk, struct request_sock *req)
++int tcp_v6_rtx_synack(struct sock *sk, struct request_sock *req)
+ {
+-	struct flowi6 fl6;
++	const struct tcp_request_sock_ops *af_ops = tcp_rsk(req)->af_specific;
++	struct flowi fl;
+ 	int res;
+ 
+-	res = tcp_v6_send_synack(sk, NULL, &fl6, req, 0, NULL);
++	res = af_ops->send_synack(sk, NULL, &fl, req, 0, NULL);
+ 	if (!res) {
+ 		TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_RETRANSSEGS);
+ 		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPSYNRETRANS);
+@@ -516,7 +536,7 @@ static int tcp_v6_rtx_synack(struct sock *sk, struct request_sock *req)
+ 	return res;
+ }
+ 
+-static void tcp_v6_reqsk_destructor(struct request_sock *req)
++void tcp_v6_reqsk_destructor(struct request_sock *req)
+ {
+ 	kfree_skb(inet_rsk(req)->pktopts);
+ }
+@@ -718,27 +738,74 @@ static int tcp_v6_inbound_md5_hash(struct sock *sk, const struct sk_buff *skb)
+ }
+ #endif
+ 
++static int tcp_v6_init_req(struct request_sock *req, struct sock *sk,
++			   struct sk_buff *skb)
++{
++	struct inet_request_sock *ireq = inet_rsk(req);
++	struct ipv6_pinfo *np = inet6_sk(sk);
++
++	ireq->ir_v6_rmt_addr = ipv6_hdr(skb)->saddr;
++	ireq->ir_v6_loc_addr = ipv6_hdr(skb)->daddr;
++
++	ireq->ir_iif = sk->sk_bound_dev_if;
++	ireq->ir_mark = inet_request_mark(sk, skb);
++
++	/* So that link locals have meaning */
++	if (!sk->sk_bound_dev_if &&
++	    ipv6_addr_type(&ireq->ir_v6_rmt_addr) & IPV6_ADDR_LINKLOCAL)
++		ireq->ir_iif = inet6_iif(skb);
++
++	if (!TCP_SKB_CB(skb)->when &&
++	    (ipv6_opt_accepted(sk, skb) || np->rxopt.bits.rxinfo ||
++	     np->rxopt.bits.rxoinfo || np->rxopt.bits.rxhlim ||
++	     np->rxopt.bits.rxohlim || np->repflow)) {
++		atomic_inc(&skb->users);
++		ireq->pktopts = skb;
++	}
++
++	return 0;
++}
++
++static struct dst_entry *tcp_v6_route_req(struct sock *sk, struct flowi *fl,
++					  const struct request_sock *req,
++					  bool *strict)
++{
++	if (strict)
++		*strict = true;
++	return inet6_csk_route_req(sk, &fl->u.ip6, req);
++}
++
+ struct request_sock_ops tcp6_request_sock_ops __read_mostly = {
+ 	.family		=	AF_INET6,
+ 	.obj_size	=	sizeof(struct tcp6_request_sock),
+-	.rtx_syn_ack	=	tcp_v6_rtx_synack,
++	.rtx_syn_ack	=	tcp_rtx_synack,
+ 	.send_ack	=	tcp_v6_reqsk_send_ack,
+ 	.destructor	=	tcp_v6_reqsk_destructor,
+ 	.send_reset	=	tcp_v6_send_reset,
+ 	.syn_ack_timeout =	tcp_syn_ack_timeout,
+ };
+ 
++const struct tcp_request_sock_ops tcp_request_sock_ipv6_ops = {
++	.mss_clamp	=	IPV6_MIN_MTU - sizeof(struct tcphdr) -
++				sizeof(struct ipv6hdr),
+ #ifdef CONFIG_TCP_MD5SIG
+-static const struct tcp_request_sock_ops tcp_request_sock_ipv6_ops = {
+ 	.md5_lookup	=	tcp_v6_reqsk_md5_lookup,
+ 	.calc_md5_hash	=	tcp_v6_md5_hash_skb,
+-};
+ #endif
++	.init_req	=	tcp_v6_init_req,
++#ifdef CONFIG_SYN_COOKIES
++	.cookie_init_seq =	cookie_v6_init_sequence,
++#endif
++	.route_req	=	tcp_v6_route_req,
++	.init_seq	=	tcp_v6_init_sequence,
++	.send_synack	=	tcp_v6_send_synack,
++	.queue_hash_add =	inet6_csk_reqsk_queue_hash_add,
++};
+ 
+-static void tcp_v6_send_response(struct sk_buff *skb, u32 seq, u32 ack, u32 win,
+-				 u32 tsval, u32 tsecr, int oif,
+-				 struct tcp_md5sig_key *key, int rst, u8 tclass,
+-				 u32 label)
++static void tcp_v6_send_response(struct sk_buff *skb, u32 seq, u32 ack,
++				 u32 data_ack, u32 win, u32 tsval, u32 tsecr,
++				 int oif, struct tcp_md5sig_key *key, int rst,
++				 u8 tclass, u32 label, int mptcp)
+ {
+ 	const struct tcphdr *th = tcp_hdr(skb);
+ 	struct tcphdr *t1;
+@@ -756,7 +823,10 @@ static void tcp_v6_send_response(struct sk_buff *skb, u32 seq, u32 ack, u32 win,
+ 	if (key)
+ 		tot_len += TCPOLEN_MD5SIG_ALIGNED;
+ #endif
+-
++#ifdef CONFIG_MPTCP
++	if (mptcp)
++		tot_len += MPTCP_SUB_LEN_DSS + MPTCP_SUB_LEN_ACK;
++#endif
+ 	buff = alloc_skb(MAX_HEADER + sizeof(struct ipv6hdr) + tot_len,
+ 			 GFP_ATOMIC);
+ 	if (buff == NULL)
+@@ -794,6 +864,17 @@ static void tcp_v6_send_response(struct sk_buff *skb, u32 seq, u32 ack, u32 win,
+ 		tcp_v6_md5_hash_hdr((__u8 *)topt, key,
+ 				    &ipv6_hdr(skb)->saddr,
+ 				    &ipv6_hdr(skb)->daddr, t1);
++		topt += 4;
++	}
++#endif
++#ifdef CONFIG_MPTCP
++	if (mptcp) {
++		/* Construction of 32-bit data_ack */
++		*topt++ = htonl((TCPOPT_MPTCP << 24) |
++				((MPTCP_SUB_LEN_DSS + MPTCP_SUB_LEN_ACK) << 16) |
++				(0x20 << 8) |
++				(0x01));
++		*topt++ = htonl(data_ack);
+ 	}
+ #endif
+ 
+@@ -834,7 +915,7 @@ static void tcp_v6_send_response(struct sk_buff *skb, u32 seq, u32 ack, u32 win,
+ 	kfree_skb(buff);
+ }
+ 
+-static void tcp_v6_send_reset(struct sock *sk, struct sk_buff *skb)
++void tcp_v6_send_reset(struct sock *sk, struct sk_buff *skb)
+ {
+ 	const struct tcphdr *th = tcp_hdr(skb);
+ 	u32 seq = 0, ack_seq = 0;
+@@ -891,7 +972,7 @@ static void tcp_v6_send_reset(struct sock *sk, struct sk_buff *skb)
+ 			  (th->doff << 2);
+ 
+ 	oif = sk ? sk->sk_bound_dev_if : 0;
+-	tcp_v6_send_response(skb, seq, ack_seq, 0, 0, 0, oif, key, 1, 0, 0);
++	tcp_v6_send_response(skb, seq, ack_seq, 0, 0, 0, 0, oif, key, 1, 0, 0, 0);
+ 
+ #ifdef CONFIG_TCP_MD5SIG
+ release_sk1:
+@@ -902,45 +983,52 @@ release_sk1:
+ #endif
+ }
+ 
+-static void tcp_v6_send_ack(struct sk_buff *skb, u32 seq, u32 ack,
++static void tcp_v6_send_ack(struct sk_buff *skb, u32 seq, u32 ack, u32 data_ack,
+ 			    u32 win, u32 tsval, u32 tsecr, int oif,
+ 			    struct tcp_md5sig_key *key, u8 tclass,
+-			    u32 label)
++			    u32 label, int mptcp)
+ {
+-	tcp_v6_send_response(skb, seq, ack, win, tsval, tsecr, oif, key, 0, tclass,
+-			     label);
++	tcp_v6_send_response(skb, seq, ack, data_ack, win, tsval, tsecr, oif,
++			     key, 0, tclass, label, mptcp);
+ }
+ 
+ static void tcp_v6_timewait_ack(struct sock *sk, struct sk_buff *skb)
+ {
+ 	struct inet_timewait_sock *tw = inet_twsk(sk);
+ 	struct tcp_timewait_sock *tcptw = tcp_twsk(sk);
++	u32 data_ack = 0;
++	int mptcp = 0;
+ 
++	if (tcptw->mptcp_tw && tcptw->mptcp_tw->meta_tw) {
++		data_ack = (u32)tcptw->mptcp_tw->rcv_nxt;
++		mptcp = 1;
++	}
+ 	tcp_v6_send_ack(skb, tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,
++			data_ack,
+ 			tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale,
+ 			tcp_time_stamp + tcptw->tw_ts_offset,
+ 			tcptw->tw_ts_recent, tw->tw_bound_dev_if, tcp_twsk_md5_key(tcptw),
+-			tw->tw_tclass, (tw->tw_flowlabel << 12));
++			tw->tw_tclass, (tw->tw_flowlabel << 12), mptcp);
+ 
+ 	inet_twsk_put(tw);
+ }
+ 
+-static void tcp_v6_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
+-				  struct request_sock *req)
++void tcp_v6_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
++			   struct request_sock *req)
+ {
+ 	/* sk->sk_state == TCP_LISTEN -> for regular TCP_SYN_RECV
+ 	 * sk->sk_state == TCP_SYN_RECV -> for Fast Open.
+ 	 */
+ 	tcp_v6_send_ack(skb, (sk->sk_state == TCP_LISTEN) ?
+ 			tcp_rsk(req)->snt_isn + 1 : tcp_sk(sk)->snd_nxt,
+-			tcp_rsk(req)->rcv_nxt,
++			tcp_rsk(req)->rcv_nxt, 0,
+ 			req->rcv_wnd, tcp_time_stamp, req->ts_recent, sk->sk_bound_dev_if,
+ 			tcp_v6_md5_do_lookup(sk, &ipv6_hdr(skb)->daddr),
+-			0, 0);
++			0, 0, 0);
+ }
+ 
+ 
+-static struct sock *tcp_v6_hnd_req(struct sock *sk, struct sk_buff *skb)
++struct sock *tcp_v6_hnd_req(struct sock *sk, struct sk_buff *skb)
+ {
+ 	struct request_sock *req, **prev;
+ 	const struct tcphdr *th = tcp_hdr(skb);
+@@ -959,7 +1047,13 @@ static struct sock *tcp_v6_hnd_req(struct sock *sk, struct sk_buff *skb)
+ 
+ 	if (nsk) {
+ 		if (nsk->sk_state != TCP_TIME_WAIT) {
++			/* Don't lock again the meta-sk. It has been locked
++			 * before mptcp_v6_do_rcv.
++			 */
++			if (mptcp(tcp_sk(nsk)) && !is_meta_sk(sk))
++				bh_lock_sock(mptcp_meta_sk(nsk));
+ 			bh_lock_sock(nsk);
++
+ 			return nsk;
+ 		}
+ 		inet_twsk_put(inet_twsk(nsk));
+@@ -973,161 +1067,25 @@ static struct sock *tcp_v6_hnd_req(struct sock *sk, struct sk_buff *skb)
+ 	return sk;
+ }
+ 
+-/* FIXME: this is substantially similar to the ipv4 code.
+- * Can some kind of merge be done? -- erics
+- */
+-static int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
++int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
+ {
+-	struct tcp_options_received tmp_opt;
+-	struct request_sock *req;
+-	struct inet_request_sock *ireq;
+-	struct ipv6_pinfo *np = inet6_sk(sk);
+-	struct tcp_sock *tp = tcp_sk(sk);
+-	__u32 isn = TCP_SKB_CB(skb)->when;
+-	struct dst_entry *dst = NULL;
+-	struct tcp_fastopen_cookie foc = { .len = -1 };
+-	bool want_cookie = false, fastopen;
+-	struct flowi6 fl6;
+-	int err;
+-
+ 	if (skb->protocol == htons(ETH_P_IP))
+ 		return tcp_v4_conn_request(sk, skb);
+ 
+ 	if (!ipv6_unicast_destination(skb))
+ 		goto drop;
+ 
+-	if ((sysctl_tcp_syncookies == 2 ||
+-	     inet_csk_reqsk_queue_is_full(sk)) && !isn) {
+-		want_cookie = tcp_syn_flood_action(sk, skb, "TCPv6");
+-		if (!want_cookie)
+-			goto drop;
+-	}
+-
+-	if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1) {
+-		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
+-		goto drop;
+-	}
+-
+-	req = inet6_reqsk_alloc(&tcp6_request_sock_ops);
+-	if (req == NULL)
+-		goto drop;
+-
+-#ifdef CONFIG_TCP_MD5SIG
+-	tcp_rsk(req)->af_specific = &tcp_request_sock_ipv6_ops;
+-#endif
+-
+-	tcp_clear_options(&tmp_opt);
+-	tmp_opt.mss_clamp = IPV6_MIN_MTU - sizeof(struct tcphdr) - sizeof(struct ipv6hdr);
+-	tmp_opt.user_mss = tp->rx_opt.user_mss;
+-	tcp_parse_options(skb, &tmp_opt, 0, want_cookie ? NULL : &foc);
+-
+-	if (want_cookie && !tmp_opt.saw_tstamp)
+-		tcp_clear_options(&tmp_opt);
++	return tcp_conn_request(&tcp6_request_sock_ops,
++				&tcp_request_sock_ipv6_ops, sk, skb);
+ 
+-	tmp_opt.tstamp_ok = tmp_opt.saw_tstamp;
+-	tcp_openreq_init(req, &tmp_opt, skb);
+-
+-	ireq = inet_rsk(req);
+-	ireq->ir_v6_rmt_addr = ipv6_hdr(skb)->saddr;
+-	ireq->ir_v6_loc_addr = ipv6_hdr(skb)->daddr;
+-	if (!want_cookie || tmp_opt.tstamp_ok)
+-		TCP_ECN_create_request(req, skb, sock_net(sk));
+-
+-	ireq->ir_iif = sk->sk_bound_dev_if;
+-	ireq->ir_mark = inet_request_mark(sk, skb);
+-
+-	/* So that link locals have meaning */
+-	if (!sk->sk_bound_dev_if &&
+-	    ipv6_addr_type(&ireq->ir_v6_rmt_addr) & IPV6_ADDR_LINKLOCAL)
+-		ireq->ir_iif = inet6_iif(skb);
+-
+-	if (!isn) {
+-		if (ipv6_opt_accepted(sk, skb) ||
+-		    np->rxopt.bits.rxinfo || np->rxopt.bits.rxoinfo ||
+-		    np->rxopt.bits.rxhlim || np->rxopt.bits.rxohlim ||
+-		    np->repflow) {
+-			atomic_inc(&skb->users);
+-			ireq->pktopts = skb;
+-		}
+-
+-		if (want_cookie) {
+-			isn = cookie_v6_init_sequence(sk, skb, &req->mss);
+-			req->cookie_ts = tmp_opt.tstamp_ok;
+-			goto have_isn;
+-		}
+-
+-		/* VJ's idea. We save last timestamp seen
+-		 * from the destination in peer table, when entering
+-		 * state TIME-WAIT, and check against it before
+-		 * accepting new connection request.
+-		 *
+-		 * If "isn" is not zero, this request hit alive
+-		 * timewait bucket, so that all the necessary checks
+-		 * are made in the function processing timewait state.
+-		 */
+-		if (tmp_opt.saw_tstamp &&
+-		    tcp_death_row.sysctl_tw_recycle &&
+-		    (dst = inet6_csk_route_req(sk, &fl6, req)) != NULL) {
+-			if (!tcp_peer_is_proven(req, dst, true)) {
+-				NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_PAWSPASSIVEREJECTED);
+-				goto drop_and_release;
+-			}
+-		}
+-		/* Kill the following clause, if you dislike this way. */
+-		else if (!sysctl_tcp_syncookies &&
+-			 (sysctl_max_syn_backlog - inet_csk_reqsk_queue_len(sk) <
+-			  (sysctl_max_syn_backlog >> 2)) &&
+-			 !tcp_peer_is_proven(req, dst, false)) {
+-			/* Without syncookies last quarter of
+-			 * backlog is filled with destinations,
+-			 * proven to be alive.
+-			 * It means that we continue to communicate
+-			 * to destinations, already remembered
+-			 * to the moment of synflood.
+-			 */
+-			LIMIT_NETDEBUG(KERN_DEBUG "TCP: drop open request from %pI6/%u\n",
+-				       &ireq->ir_v6_rmt_addr, ntohs(tcp_hdr(skb)->source));
+-			goto drop_and_release;
+-		}
+-
+-		isn = tcp_v6_init_sequence(skb);
+-	}
+-have_isn:
+-
+-	if (security_inet_conn_request(sk, skb, req))
+-		goto drop_and_release;
+-
+-	if (!dst && (dst = inet6_csk_route_req(sk, &fl6, req)) == NULL)
+-		goto drop_and_free;
+-
+-	tcp_rsk(req)->snt_isn = isn;
+-	tcp_rsk(req)->snt_synack = tcp_time_stamp;
+-	tcp_openreq_init_rwin(req, sk, dst);
+-	fastopen = !want_cookie &&
+-		   tcp_try_fastopen(sk, skb, req, &foc, dst);
+-	err = tcp_v6_send_synack(sk, dst, &fl6, req,
+-				 skb_get_queue_mapping(skb), &foc);
+-	if (!fastopen) {
+-		if (err || want_cookie)
+-			goto drop_and_free;
+-
+-		tcp_rsk(req)->listener = NULL;
+-		inet6_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT);
+-	}
+-	return 0;
+-
+-drop_and_release:
+-	dst_release(dst);
+-drop_and_free:
+-	reqsk_free(req);
+ drop:
+ 	NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
+ 	return 0; /* don't send reset */
+ }
+ 
+-static struct sock *tcp_v6_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
+-					 struct request_sock *req,
+-					 struct dst_entry *dst)
++struct sock *tcp_v6_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
++				  struct request_sock *req,
++				  struct dst_entry *dst)
+ {
+ 	struct inet_request_sock *ireq;
+ 	struct ipv6_pinfo *newnp, *np = inet6_sk(sk);
+@@ -1165,7 +1123,12 @@ static struct sock *tcp_v6_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
+ 
+ 		newsk->sk_v6_rcv_saddr = newnp->saddr;
+ 
+-		inet_csk(newsk)->icsk_af_ops = &ipv6_mapped;
++#ifdef CONFIG_MPTCP
++		if (is_mptcp_enabled(newsk))
++			inet_csk(newsk)->icsk_af_ops = &mptcp_v6_mapped;
++		else
++#endif
++			inet_csk(newsk)->icsk_af_ops = &ipv6_mapped;
+ 		newsk->sk_backlog_rcv = tcp_v4_do_rcv;
+ #ifdef CONFIG_TCP_MD5SIG
+ 		newtp->af_specific = &tcp_sock_ipv6_mapped_specific;
+@@ -1329,7 +1292,7 @@ out:
+  * This is because we cannot sleep with the original spinlock
+  * held.
+  */
+-static int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
++int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
+ {
+ 	struct ipv6_pinfo *np = inet6_sk(sk);
+ 	struct tcp_sock *tp;
+@@ -1351,6 +1314,9 @@ static int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
+ 		goto discard;
+ #endif
+ 
++	if (is_meta_sk(sk))
++		return mptcp_v6_do_rcv(sk, skb);
++
+ 	if (sk_filter(sk, skb))
+ 		goto discard;
+ 
+@@ -1472,7 +1438,7 @@ static int tcp_v6_rcv(struct sk_buff *skb)
+ {
+ 	const struct tcphdr *th;
+ 	const struct ipv6hdr *hdr;
+-	struct sock *sk;
++	struct sock *sk, *meta_sk = NULL;
+ 	int ret;
+ 	struct net *net = dev_net(skb->dev);
+ 
+@@ -1503,18 +1469,43 @@ static int tcp_v6_rcv(struct sk_buff *skb)
+ 	TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin +
+ 				    skb->len - th->doff*4);
+ 	TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq);
++#ifdef CONFIG_MPTCP
++	TCP_SKB_CB(skb)->mptcp_flags = 0;
++	TCP_SKB_CB(skb)->dss_off = 0;
++#endif
+ 	TCP_SKB_CB(skb)->when = 0;
+ 	TCP_SKB_CB(skb)->ip_dsfield = ipv6_get_dsfield(hdr);
+ 	TCP_SKB_CB(skb)->sacked = 0;
+ 
+ 	sk = __inet6_lookup_skb(&tcp_hashinfo, skb, th->source, th->dest);
+-	if (!sk)
+-		goto no_tcp_socket;
+ 
+ process:
+-	if (sk->sk_state == TCP_TIME_WAIT)
++	if (sk && sk->sk_state == TCP_TIME_WAIT)
+ 		goto do_time_wait;
+ 
++#ifdef CONFIG_MPTCP
++	if (!sk && th->syn && !th->ack) {
++		int ret = mptcp_lookup_join(skb, NULL);
++
++		if (ret < 0) {
++			tcp_v6_send_reset(NULL, skb);
++			goto discard_it;
++		} else if (ret > 0) {
++			return 0;
++		}
++	}
++
++	/* Is there a pending request sock for this segment ? */
++	if ((!sk || sk->sk_state == TCP_LISTEN) && mptcp_check_req(skb, net)) {
++		if (sk)
++			sock_put(sk);
++		return 0;
++	}
++#endif
++
++	if (!sk)
++		goto no_tcp_socket;
++
+ 	if (hdr->hop_limit < inet6_sk(sk)->min_hopcount) {
+ 		NET_INC_STATS_BH(net, LINUX_MIB_TCPMINTTLDROP);
+ 		goto discard_and_relse;
+@@ -1529,11 +1520,21 @@ process:
+ 	sk_mark_napi_id(sk, skb);
+ 	skb->dev = NULL;
+ 
+-	bh_lock_sock_nested(sk);
++	if (mptcp(tcp_sk(sk))) {
++		meta_sk = mptcp_meta_sk(sk);
++
++		bh_lock_sock_nested(meta_sk);
++		if (sock_owned_by_user(meta_sk))
++			skb->sk = sk;
++	} else {
++		meta_sk = sk;
++		bh_lock_sock_nested(sk);
++	}
++
+ 	ret = 0;
+-	if (!sock_owned_by_user(sk)) {
++	if (!sock_owned_by_user(meta_sk)) {
+ #ifdef CONFIG_NET_DMA
+-		struct tcp_sock *tp = tcp_sk(sk);
++		struct tcp_sock *tp = tcp_sk(meta_sk);
+ 		if (!tp->ucopy.dma_chan && tp->ucopy.pinned_list)
+ 			tp->ucopy.dma_chan = net_dma_find_channel();
+ 		if (tp->ucopy.dma_chan)
+@@ -1541,16 +1542,17 @@ process:
+ 		else
+ #endif
+ 		{
+-			if (!tcp_prequeue(sk, skb))
++			if (!tcp_prequeue(meta_sk, skb))
+ 				ret = tcp_v6_do_rcv(sk, skb);
+ 		}
+-	} else if (unlikely(sk_add_backlog(sk, skb,
+-					   sk->sk_rcvbuf + sk->sk_sndbuf))) {
+-		bh_unlock_sock(sk);
++	} else if (unlikely(sk_add_backlog(meta_sk, skb,
++					   meta_sk->sk_rcvbuf + meta_sk->sk_sndbuf))) {
++		bh_unlock_sock(meta_sk);
+ 		NET_INC_STATS_BH(net, LINUX_MIB_TCPBACKLOGDROP);
+ 		goto discard_and_relse;
+ 	}
+-	bh_unlock_sock(sk);
++
++	bh_unlock_sock(meta_sk);
+ 
+ 	sock_put(sk);
+ 	return ret ? -1 : 0;
+@@ -1607,6 +1609,18 @@ do_time_wait:
+ 			sk = sk2;
+ 			goto process;
+ 		}
++#ifdef CONFIG_MPTCP
++		if (th->syn && !th->ack) {
++			int ret = mptcp_lookup_join(skb, inet_twsk(sk));
++
++			if (ret < 0) {
++				tcp_v6_send_reset(NULL, skb);
++				goto discard_it;
++			} else if (ret > 0) {
++				return 0;
++			}
++		}
++#endif
+ 		/* Fall through to ACK */
+ 	}
+ 	case TCP_TW_ACK:
+@@ -1657,7 +1671,7 @@ static void tcp_v6_early_demux(struct sk_buff *skb)
+ 	}
+ }
+ 
+-static struct timewait_sock_ops tcp6_timewait_sock_ops = {
++struct timewait_sock_ops tcp6_timewait_sock_ops = {
+ 	.twsk_obj_size	= sizeof(struct tcp6_timewait_sock),
+ 	.twsk_unique	= tcp_twsk_unique,
+ 	.twsk_destructor = tcp_twsk_destructor,
+@@ -1730,7 +1744,12 @@ static int tcp_v6_init_sock(struct sock *sk)
+ 
+ 	tcp_init_sock(sk);
+ 
+-	icsk->icsk_af_ops = &ipv6_specific;
++#ifdef CONFIG_MPTCP
++	if (is_mptcp_enabled(sk))
++		icsk->icsk_af_ops = &mptcp_v6_specific;
++	else
++#endif
++		icsk->icsk_af_ops = &ipv6_specific;
+ 
+ #ifdef CONFIG_TCP_MD5SIG
+ 	tcp_sk(sk)->af_specific = &tcp_sock_ipv6_specific;
+@@ -1739,7 +1758,7 @@ static int tcp_v6_init_sock(struct sock *sk)
+ 	return 0;
+ }
+ 
+-static void tcp_v6_destroy_sock(struct sock *sk)
++void tcp_v6_destroy_sock(struct sock *sk)
+ {
+ 	tcp_v4_destroy_sock(sk);
+ 	inet6_destroy_sock(sk);
+@@ -1924,12 +1943,28 @@ void tcp6_proc_exit(struct net *net)
+ static void tcp_v6_clear_sk(struct sock *sk, int size)
+ {
+ 	struct inet_sock *inet = inet_sk(sk);
++#ifdef CONFIG_MPTCP
++	struct tcp_sock *tp = tcp_sk(sk);
++	/* size_tk_table goes from the end of tk_table to the end of sk */
++	int size_tk_table = size - offsetof(struct tcp_sock, tk_table) -
++			    sizeof(tp->tk_table);
++#endif
+ 
+ 	/* we do not want to clear pinet6 field, because of RCU lookups */
+ 	sk_prot_clear_nulls(sk, offsetof(struct inet_sock, pinet6));
+ 
+ 	size -= offsetof(struct inet_sock, pinet6) + sizeof(inet->pinet6);
++
++#ifdef CONFIG_MPTCP
++	/* We zero out only from pinet6 to tk_table */
++	size -= size_tk_table + sizeof(tp->tk_table);
++#endif
+ 	memset(&inet->pinet6 + 1, 0, size);
++
++#ifdef CONFIG_MPTCP
++	memset((char *)&tp->tk_table + sizeof(tp->tk_table), 0, size_tk_table);
++#endif
++
+ }
+ 
+ struct proto tcpv6_prot = {
+diff --git a/net/mptcp/Kconfig b/net/mptcp/Kconfig
+new file mode 100644
+index 000000000000..cdfc03adabf8
+--- /dev/null
++++ b/net/mptcp/Kconfig
+@@ -0,0 +1,115 @@
++#
++# MPTCP configuration
++#
++config MPTCP
++        bool "MPTCP protocol"
++        depends on (IPV6=y || IPV6=n)
++        ---help---
++          This replaces the normal TCP stack with a Multipath TCP stack,
++          able to use several paths at once.
++
++menuconfig MPTCP_PM_ADVANCED
++	bool "MPTCP: advanced path-manager control"
++	depends on MPTCP=y
++	---help---
++	  Support for selection of different path-managers. You should choose 'Y' here,
++	  because otherwise you will not actively create new MPTCP-subflows.
++
++if MPTCP_PM_ADVANCED
++
++config MPTCP_FULLMESH
++	tristate "MPTCP Full-Mesh Path-Manager"
++	depends on MPTCP=y
++	---help---
++	  This path-management module will create a full-mesh among all IP-addresses.
++
++config MPTCP_NDIFFPORTS
++	tristate "MPTCP ndiff-ports"
++	depends on MPTCP=y
++	---help---
++	  This path-management module will create multiple subflows between the same
++	  pair of IP-addresses, modifying the source-port. You can set the number
++	  of subflows via the mptcp_ndiffports-sysctl.
++
++config MPTCP_BINDER
++	tristate "MPTCP Binder"
++	depends on (MPTCP=y)
++	---help---
++	  This path-management module works like ndiffports, and adds the sysctl
++	  option to set the gateway (and/or path to) per each additional subflow
++	  via Loose Source Routing (IPv4 only).
++
++choice
++	prompt "Default MPTCP Path-Manager"
++	default DEFAULT
++	help
++	  Select the Path-Manager of your choice
++
++	config DEFAULT_FULLMESH
++		bool "Full mesh" if MPTCP_FULLMESH=y
++
++	config DEFAULT_NDIFFPORTS
++		bool "ndiff-ports" if MPTCP_NDIFFPORTS=y
++
++	config DEFAULT_BINDER
++		bool "binder" if MPTCP_BINDER=y
++
++	config DEFAULT_DUMMY
++		bool "Default"
++
++endchoice
++
++endif
++
++config DEFAULT_MPTCP_PM
++	string
++	default "default" if DEFAULT_DUMMY
++	default "fullmesh" if DEFAULT_FULLMESH 
++	default "ndiffports" if DEFAULT_NDIFFPORTS
++	default "binder" if DEFAULT_BINDER
++	default "default"
++
++menuconfig MPTCP_SCHED_ADVANCED
++	bool "MPTCP: advanced scheduler control"
++	depends on MPTCP=y
++	---help---
++	  Support for selection of different schedulers. You should choose 'Y' here,
++	  if you want to choose a different scheduler than the default one.
++
++if MPTCP_SCHED_ADVANCED
++
++config MPTCP_ROUNDROBIN
++	tristate "MPTCP Round-Robin"
++	depends on (MPTCP=y)
++	---help---
++	  This is a very simple round-robin scheduler. Probably has bad performance
++	  but might be interesting for researchers.
++
++choice
++	prompt "Default MPTCP Scheduler"
++	default DEFAULT
++	help
++	  Select the Scheduler of your choice
++
++	config DEFAULT_SCHEDULER
++		bool "Default"
++		---help---
++		  This is the default scheduler, sending first on the subflow
++		  with the lowest RTT.
++
++	config DEFAULT_ROUNDROBIN
++		bool "Round-Robin" if MPTCP_ROUNDROBIN=y
++		---help---
++		  This is the round-rob scheduler, sending in a round-robin
++		  fashion..
++
++endchoice
++endif
++
++config DEFAULT_MPTCP_SCHED
++	string
++	depends on (MPTCP=y)
++	default "default" if DEFAULT_SCHEDULER
++	default "roundrobin" if DEFAULT_ROUNDROBIN
++	default "default"
++
+diff --git a/net/mptcp/Makefile b/net/mptcp/Makefile
+new file mode 100644
+index 000000000000..35561a7012e3
+--- /dev/null
++++ b/net/mptcp/Makefile
+@@ -0,0 +1,20 @@
++#
++## Makefile for MultiPath TCP support code.
++#
++#
++
++obj-$(CONFIG_MPTCP) += mptcp.o
++
++mptcp-y := mptcp_ctrl.o mptcp_ipv4.o mptcp_ofo_queue.o mptcp_pm.o \
++	   mptcp_output.o mptcp_input.o mptcp_sched.o
++
++obj-$(CONFIG_TCP_CONG_COUPLED) += mptcp_coupled.o
++obj-$(CONFIG_TCP_CONG_OLIA) += mptcp_olia.o
++obj-$(CONFIG_TCP_CONG_WVEGAS) += mptcp_wvegas.o
++obj-$(CONFIG_MPTCP_FULLMESH) += mptcp_fullmesh.o
++obj-$(CONFIG_MPTCP_NDIFFPORTS) += mptcp_ndiffports.o
++obj-$(CONFIG_MPTCP_BINDER) += mptcp_binder.o
++obj-$(CONFIG_MPTCP_ROUNDROBIN) += mptcp_rr.o
++
++mptcp-$(subst m,y,$(CONFIG_IPV6)) += mptcp_ipv6.o
++
+diff --git a/net/mptcp/mptcp_binder.c b/net/mptcp/mptcp_binder.c
+new file mode 100644
+index 000000000000..95d8da560715
+--- /dev/null
++++ b/net/mptcp/mptcp_binder.c
+@@ -0,0 +1,487 @@
++#include <linux/module.h>
++
++#include <net/mptcp.h>
++#include <net/mptcp_v4.h>
++
++#include <linux/route.h>
++#include <linux/inet.h>
++#include <linux/mroute.h>
++#include <linux/spinlock_types.h>
++#include <net/inet_ecn.h>
++#include <net/route.h>
++#include <net/xfrm.h>
++#include <net/compat.h>
++#include <linux/slab.h>
++
++#define MPTCP_GW_MAX_LISTS	10
++#define MPTCP_GW_LIST_MAX_LEN	6
++#define MPTCP_GW_SYSCTL_MAX_LEN	(15 * MPTCP_GW_LIST_MAX_LEN *	\
++							MPTCP_GW_MAX_LISTS)
++
++struct mptcp_gw_list {
++	struct in_addr list[MPTCP_GW_MAX_LISTS][MPTCP_GW_LIST_MAX_LEN];
++	u8 len[MPTCP_GW_MAX_LISTS];
++};
++
++struct binder_priv {
++	/* Worker struct for subflow establishment */
++	struct work_struct subflow_work;
++
++	struct mptcp_cb *mpcb;
++
++	/* Prevent multiple sub-sockets concurrently iterating over sockets */
++	spinlock_t *flow_lock;
++};
++
++static struct mptcp_gw_list *mptcp_gws;
++static rwlock_t mptcp_gws_lock;
++
++static int mptcp_binder_ndiffports __read_mostly = 1;
++
++static char sysctl_mptcp_binder_gateways[MPTCP_GW_SYSCTL_MAX_LEN] __read_mostly;
++
++static int mptcp_get_avail_list_ipv4(struct sock *sk)
++{
++	int i, j, list_taken, opt_ret, opt_len;
++	unsigned char *opt_ptr, *opt_end_ptr, opt[MAX_IPOPTLEN];
++
++	for (i = 0; i < MPTCP_GW_MAX_LISTS; ++i) {
++		if (mptcp_gws->len[i] == 0)
++			goto error;
++
++		mptcp_debug("mptcp_get_avail_list_ipv4: List %i\n", i);
++		list_taken = 0;
++
++		/* Loop through all sub-sockets in this connection */
++		mptcp_for_each_sk(tcp_sk(sk)->mpcb, sk) {
++			mptcp_debug("mptcp_get_avail_list_ipv4: Next sock\n");
++
++			/* Reset length and options buffer, then retrieve
++			 * from socket
++			 */
++			opt_len = MAX_IPOPTLEN;
++			memset(opt, 0, MAX_IPOPTLEN);
++			opt_ret = ip_getsockopt(sk, IPPROTO_IP,
++				IP_OPTIONS, opt, &opt_len);
++			if (opt_ret < 0) {
++				mptcp_debug(KERN_ERR "%s: MPTCP subsocket getsockopt() IP_OPTIONS failed, error %d\n",
++					    __func__, opt_ret);
++				goto error;
++			}
++
++			/* If socket has no options, it has no stake in this list */
++			if (opt_len <= 0)
++				continue;
++
++			/* Iterate options buffer */
++			for (opt_ptr = &opt[0]; opt_ptr < &opt[opt_len]; opt_ptr++) {
++				if (*opt_ptr == IPOPT_LSRR) {
++					mptcp_debug("mptcp_get_avail_list_ipv4: LSRR options found\n");
++					goto sock_lsrr;
++				}
++			}
++			continue;
++
++sock_lsrr:
++			/* Pointer to the 2nd to last address */
++			opt_end_ptr = opt_ptr+(*(opt_ptr+1))-4;
++
++			/* Addresses start 3 bytes after type offset */
++			opt_ptr += 3;
++			j = 0;
++
++			/* Different length lists cannot be the same */
++			if ((opt_end_ptr-opt_ptr)/4 != mptcp_gws->len[i])
++				continue;
++
++			/* Iterate if we are still inside options list
++			 * and sysctl list
++			 */
++			while (opt_ptr < opt_end_ptr && j < mptcp_gws->len[i]) {
++				/* If there is a different address, this list must
++				 * not be set on this socket
++				 */
++				if (memcmp(&mptcp_gws->list[i][j], opt_ptr, 4))
++					break;
++
++				/* Jump 4 bytes to next address */
++				opt_ptr += 4;
++				j++;
++			}
++
++			/* Reached the end without a differing address, lists
++			 * are therefore identical.
++			 */
++			if (j == mptcp_gws->len[i]) {
++				mptcp_debug("mptcp_get_avail_list_ipv4: List already used\n");
++				list_taken = 1;
++				break;
++			}
++		}
++
++		/* Free list found if not taken by a socket */
++		if (!list_taken) {
++			mptcp_debug("mptcp_get_avail_list_ipv4: List free\n");
++			break;
++		}
++	}
++
++	if (i >= MPTCP_GW_MAX_LISTS)
++		goto error;
++
++	return i;
++error:
++	return -1;
++}
++
++/* The list of addresses is parsed each time a new connection is opened,
++ *  to make sure it's up to date. In case of error, all the lists are
++ *  marked as unavailable and the subflow's fingerprint is set to 0.
++ */
++static void mptcp_v4_add_lsrr(struct sock *sk, struct in_addr addr)
++{
++	int i, j, ret;
++	unsigned char opt[MAX_IPOPTLEN] = {0};
++	struct tcp_sock *tp = tcp_sk(sk);
++	struct binder_priv *fmp = (struct binder_priv *)&tp->mpcb->mptcp_pm[0];
++
++	/* Read lock: multiple sockets can read LSRR addresses at the same
++	 * time, but writes are done in mutual exclusion.
++	 * Spin lock: must search for free list for one socket at a time, or
++	 * multiple sockets could take the same list.
++	 */
++	read_lock(&mptcp_gws_lock);
++	spin_lock(fmp->flow_lock);
++
++	i = mptcp_get_avail_list_ipv4(sk);
++
++	/* Execution enters here only if a free path is found.
++	 */
++	if (i >= 0) {
++		opt[0] = IPOPT_NOP;
++		opt[1] = IPOPT_LSRR;
++		opt[2] = sizeof(mptcp_gws->list[i][0].s_addr) *
++				(mptcp_gws->len[i] + 1) + 3;
++		opt[3] = IPOPT_MINOFF;
++		for (j = 0; j < mptcp_gws->len[i]; ++j)
++			memcpy(opt + 4 +
++				(j * sizeof(mptcp_gws->list[i][0].s_addr)),
++				&mptcp_gws->list[i][j].s_addr,
++				sizeof(mptcp_gws->list[i][0].s_addr));
++		/* Final destination must be part of IP_OPTIONS parameter. */
++		memcpy(opt + 4 + (j * sizeof(addr.s_addr)), &addr.s_addr,
++		       sizeof(addr.s_addr));
++
++		/* setsockopt must be inside the lock, otherwise another
++		 * subflow could fail to see that we have taken a list.
++		 */
++		ret = ip_setsockopt(sk, IPPROTO_IP, IP_OPTIONS, opt,
++				4 + sizeof(mptcp_gws->list[i][0].s_addr)
++				* (mptcp_gws->len[i] + 1));
++
++		if (ret < 0) {
++			mptcp_debug(KERN_ERR "%s: MPTCP subsock setsockopt() IP_OPTIONS failed, error %d\n",
++				    __func__, ret);
++		}
++	}
++
++	spin_unlock(fmp->flow_lock);
++	read_unlock(&mptcp_gws_lock);
++
++	return;
++}
++
++/* Parses gateways string for a list of paths to different
++ * gateways, and stores them for use with the Loose Source Routing (LSRR)
++ * socket option. Each list must have "," separated addresses, and the lists
++ * themselves must be separated by "-". Returns -1 in case one or more of the
++ * addresses is not a valid ipv4/6 address.
++ */
++static int mptcp_parse_gateway_ipv4(char *gateways)
++{
++	int i, j, k, ret;
++	char *tmp_string = NULL;
++	struct in_addr tmp_addr;
++
++	tmp_string = kzalloc(16, GFP_KERNEL);
++	if (tmp_string == NULL)
++		return -ENOMEM;
++
++	write_lock(&mptcp_gws_lock);
++
++	memset(mptcp_gws, 0, sizeof(struct mptcp_gw_list));
++
++	/* A TMP string is used since inet_pton needs a null terminated string
++	 * but we do not want to modify the sysctl for obvious reasons.
++	 * i will iterate over the SYSCTL string, j will iterate over the
++	 * temporary string where each IP is copied into, k will iterate over
++	 * the IPs in each list.
++	 */
++	for (i = j = k = 0;
++			i < MPTCP_GW_SYSCTL_MAX_LEN && k < MPTCP_GW_MAX_LISTS;
++			++i) {
++		if (gateways[i] == '-' || gateways[i] == ',' || gateways[i] == '\0') {
++			/* If the temp IP is empty and the current list is
++			 *  empty, we are done.
++			 */
++			if (j == 0 && mptcp_gws->len[k] == 0)
++				break;
++
++			/* Terminate the temp IP string, then if it is
++			 * non-empty parse the IP and copy it.
++			 */
++			tmp_string[j] = '\0';
++			if (j > 0) {
++				mptcp_debug("mptcp_parse_gateway_list tmp: %s i: %d\n", tmp_string, i);
++
++				ret = in4_pton(tmp_string, strlen(tmp_string),
++						(u8 *)&tmp_addr.s_addr, '\0',
++						NULL);
++
++				if (ret) {
++					mptcp_debug("mptcp_parse_gateway_list ret: %d s_addr: %pI4\n",
++						    ret,
++						    &tmp_addr.s_addr);
++					memcpy(&mptcp_gws->list[k][mptcp_gws->len[k]].s_addr,
++					       &tmp_addr.s_addr,
++					       sizeof(tmp_addr.s_addr));
++					mptcp_gws->len[k]++;
++					j = 0;
++					tmp_string[j] = '\0';
++					/* Since we can't impose a limit to
++					 * what the user can input, make sure
++					 * there are not too many IPs in the
++					 * SYSCTL string.
++					 */
++					if (mptcp_gws->len[k] > MPTCP_GW_LIST_MAX_LEN) {
++						mptcp_debug("mptcp_parse_gateway_list too many members in list %i: max %i\n",
++							    k,
++							    MPTCP_GW_LIST_MAX_LEN);
++						goto error;
++					}
++				} else {
++					goto error;
++				}
++			}
++
++			if (gateways[i] == '-' || gateways[i] == '\0')
++				++k;
++		} else {
++			tmp_string[j] = gateways[i];
++			++j;
++		}
++	}
++
++	/* Number of flows is number of gateway lists plus master flow */
++	mptcp_binder_ndiffports = k+1;
++
++	write_unlock(&mptcp_gws_lock);
++	kfree(tmp_string);
++
++	return 0;
++
++error:
++	memset(mptcp_gws, 0, sizeof(struct mptcp_gw_list));
++	memset(gateways, 0, sizeof(char) * MPTCP_GW_SYSCTL_MAX_LEN);
++	write_unlock(&mptcp_gws_lock);
++	kfree(tmp_string);
++	return -1;
++}
++
++/**
++ * Create all new subflows, by doing calls to mptcp_initX_subsockets
++ *
++ * This function uses a goto next_subflow, to allow releasing the lock between
++ * new subflows and giving other processes a chance to do some work on the
++ * socket and potentially finishing the communication.
++ **/
++static void create_subflow_worker(struct work_struct *work)
++{
++	const struct binder_priv *pm_priv = container_of(work,
++						     struct binder_priv,
++						     subflow_work);
++	struct mptcp_cb *mpcb = pm_priv->mpcb;
++	struct sock *meta_sk = mpcb->meta_sk;
++	int iter = 0;
++
++next_subflow:
++	if (iter) {
++		release_sock(meta_sk);
++		mutex_unlock(&mpcb->mpcb_mutex);
++
++		cond_resched();
++	}
++	mutex_lock(&mpcb->mpcb_mutex);
++	lock_sock_nested(meta_sk, SINGLE_DEPTH_NESTING);
++
++	iter++;
++
++	if (sock_flag(meta_sk, SOCK_DEAD))
++		goto exit;
++
++	if (mpcb->master_sk &&
++	    !tcp_sk(mpcb->master_sk)->mptcp->fully_established)
++		goto exit;
++
++	if (mptcp_binder_ndiffports > iter &&
++	    mptcp_binder_ndiffports > mpcb->cnt_subflows) {
++		struct mptcp_loc4 loc;
++		struct mptcp_rem4 rem;
++
++		loc.addr.s_addr = inet_sk(meta_sk)->inet_saddr;
++		loc.loc4_id = 0;
++		loc.low_prio = 0;
++
++		rem.addr.s_addr = inet_sk(meta_sk)->inet_daddr;
++		rem.port = inet_sk(meta_sk)->inet_dport;
++		rem.rem4_id = 0; /* Default 0 */
++
++		mptcp_init4_subsockets(meta_sk, &loc, &rem);
++
++		goto next_subflow;
++	}
++
++exit:
++	release_sock(meta_sk);
++	mutex_unlock(&mpcb->mpcb_mutex);
++	sock_put(meta_sk);
++}
++
++static void binder_new_session(const struct sock *meta_sk)
++{
++	struct mptcp_cb *mpcb = tcp_sk(meta_sk)->mpcb;
++	struct binder_priv *fmp = (struct binder_priv *)&mpcb->mptcp_pm[0];
++	static DEFINE_SPINLOCK(flow_lock);
++
++#if IS_ENABLED(CONFIG_IPV6)
++	if (meta_sk->sk_family == AF_INET6 &&
++	    !mptcp_v6_is_v4_mapped(meta_sk)) {
++			mptcp_fallback_default(mpcb);
++			return;
++	}
++#endif
++
++	/* Initialize workqueue-struct */
++	INIT_WORK(&fmp->subflow_work, create_subflow_worker);
++	fmp->mpcb = mpcb;
++
++	fmp->flow_lock = &flow_lock;
++}
++
++static void binder_create_subflows(struct sock *meta_sk)
++{
++	struct mptcp_cb *mpcb = tcp_sk(meta_sk)->mpcb;
++	struct binder_priv *pm_priv = (struct binder_priv *)&mpcb->mptcp_pm[0];
++
++	if (mpcb->infinite_mapping_snd || mpcb->infinite_mapping_rcv ||
++	    mpcb->send_infinite_mapping ||
++	    mpcb->server_side || sock_flag(meta_sk, SOCK_DEAD))
++		return;
++
++	if (!work_pending(&pm_priv->subflow_work)) {
++		sock_hold(meta_sk);
++		queue_work(mptcp_wq, &pm_priv->subflow_work);
++	}
++}
++
++static int binder_get_local_id(sa_family_t family, union inet_addr *addr,
++				  struct net *net, bool *low_prio)
++{
++	return 0;
++}
++
++/* Callback functions, executed when syctl mptcp.mptcp_gateways is updated.
++ * Inspired from proc_tcp_congestion_control().
++ */
++static int proc_mptcp_gateways(ctl_table *ctl, int write,
++				       void __user *buffer, size_t *lenp,
++				       loff_t *ppos)
++{
++	int ret;
++	ctl_table tbl = {
++		.maxlen = MPTCP_GW_SYSCTL_MAX_LEN,
++	};
++
++	if (write) {
++		tbl.data = kzalloc(MPTCP_GW_SYSCTL_MAX_LEN, GFP_KERNEL);
++		if (tbl.data == NULL)
++			return -1;
++		ret = proc_dostring(&tbl, write, buffer, lenp, ppos);
++		if (ret == 0) {
++			ret = mptcp_parse_gateway_ipv4(tbl.data);
++			memcpy(ctl->data, tbl.data, MPTCP_GW_SYSCTL_MAX_LEN);
++		}
++		kfree(tbl.data);
++	} else {
++		ret = proc_dostring(ctl, write, buffer, lenp, ppos);
++	}
++
++
++	return ret;
++}
++
++static struct mptcp_pm_ops binder __read_mostly = {
++	.new_session = binder_new_session,
++	.fully_established = binder_create_subflows,
++	.get_local_id = binder_get_local_id,
++	.init_subsocket_v4 = mptcp_v4_add_lsrr,
++	.name = "binder",
++	.owner = THIS_MODULE,
++};
++
++static struct ctl_table binder_table[] = {
++	{
++		.procname = "mptcp_binder_gateways",
++		.data = &sysctl_mptcp_binder_gateways,
++		.maxlen = sizeof(char) * MPTCP_GW_SYSCTL_MAX_LEN,
++		.mode = 0644,
++		.proc_handler = &proc_mptcp_gateways
++	},
++	{ }
++};
++
++struct ctl_table_header *mptcp_sysctl_binder;
++
++/* General initialization of MPTCP_PM */
++static int __init binder_register(void)
++{
++	mptcp_gws = kzalloc(sizeof(*mptcp_gws), GFP_KERNEL);
++	if (!mptcp_gws)
++		return -ENOMEM;
++
++	rwlock_init(&mptcp_gws_lock);
++
++	BUILD_BUG_ON(sizeof(struct binder_priv) > MPTCP_PM_SIZE);
++
++	mptcp_sysctl_binder = register_net_sysctl(&init_net, "net/mptcp",
++			binder_table);
++	if (!mptcp_sysctl_binder)
++		goto sysctl_fail;
++
++	if (mptcp_register_path_manager(&binder))
++		goto pm_failed;
++
++	return 0;
++
++pm_failed:
++	unregister_net_sysctl_table(mptcp_sysctl_binder);
++sysctl_fail:
++	kfree(mptcp_gws);
++
++	return -1;
++}
++
++static void binder_unregister(void)
++{
++	mptcp_unregister_path_manager(&binder);
++	unregister_net_sysctl_table(mptcp_sysctl_binder);
++	kfree(mptcp_gws);
++}
++
++module_init(binder_register);
++module_exit(binder_unregister);
++
++MODULE_AUTHOR("Luca Boccassi, Duncan Eastoe, Christoph Paasch (ndiffports)");
++MODULE_LICENSE("GPL");
++MODULE_DESCRIPTION("BINDER MPTCP");
++MODULE_VERSION("0.1");
+diff --git a/net/mptcp/mptcp_coupled.c b/net/mptcp/mptcp_coupled.c
+new file mode 100644
+index 000000000000..5d761164eb85
+--- /dev/null
++++ b/net/mptcp/mptcp_coupled.c
+@@ -0,0 +1,270 @@
++/*
++ *	MPTCP implementation - Linked Increase congestion control Algorithm (LIA)
++ *
++ *	Initial Design & Implementation:
++ *	Sébastien Barré <sebastien.barre@×××××××××.be>
++ *
++ *	Current Maintainer & Author:
++ *	Christoph Paasch <christoph.paasch@×××××××××.be>
++ *
++ *	Additional authors:
++ *	Jaakko Korkeaniemi <jaakko.korkeaniemi@×××××.fi>
++ *	Gregory Detal <gregory.detal@×××××××××.be>
++ *	Fabien Duchêne <fabien.duchene@×××××××××.be>
++ *	Andreas Seelinger <Andreas.Seelinger@×××××××××××.de>
++ *	Lavkesh Lahngir <lavkesh51@×××××.com>
++ *	Andreas Ripke <ripke@××××××.eu>
++ *	Vlad Dogaru <vlad.dogaru@×××××.com>
++ *	Octavian Purdila <octavian.purdila@×××××.com>
++ *	John Ronan <jronan@××××.org>
++ *	Catalin Nicutar <catalin.nicutar@×××××.com>
++ *	Brandon Heller <brandonh@××××××××.edu>
++ *
++ *
++ *	This program is free software; you can redistribute it and/or
++ *      modify it under the terms of the GNU General Public License
++ *      as published by the Free Software Foundation; either version
++ *      2 of the License, or (at your option) any later version.
++ */
++#include <net/tcp.h>
++#include <net/mptcp.h>
++
++#include <linux/module.h>
++
++/* Scaling is done in the numerator with alpha_scale_num and in the denominator
++ * with alpha_scale_den.
++ *
++ * To downscale, we just need to use alpha_scale.
++ *
++ * We have: alpha_scale = alpha_scale_num / (alpha_scale_den ^ 2)
++ */
++static int alpha_scale_den = 10;
++static int alpha_scale_num = 32;
++static int alpha_scale = 12;
++
++struct mptcp_ccc {
++	u64	alpha;
++	bool	forced_update;
++};
++
++static inline int mptcp_ccc_sk_can_send(const struct sock *sk)
++{
++	return mptcp_sk_can_send(sk) && tcp_sk(sk)->srtt_us;
++}
++
++static inline u64 mptcp_get_alpha(const struct sock *meta_sk)
++{
++	return ((struct mptcp_ccc *)inet_csk_ca(meta_sk))->alpha;
++}
++
++static inline void mptcp_set_alpha(const struct sock *meta_sk, u64 alpha)
++{
++	((struct mptcp_ccc *)inet_csk_ca(meta_sk))->alpha = alpha;
++}
++
++static inline u64 mptcp_ccc_scale(u32 val, int scale)
++{
++	return (u64) val << scale;
++}
++
++static inline bool mptcp_get_forced(const struct sock *meta_sk)
++{
++	return ((struct mptcp_ccc *)inet_csk_ca(meta_sk))->forced_update;
++}
++
++static inline void mptcp_set_forced(const struct sock *meta_sk, bool force)
++{
++	((struct mptcp_ccc *)inet_csk_ca(meta_sk))->forced_update = force;
++}
++
++static void mptcp_ccc_recalc_alpha(const struct sock *sk)
++{
++	const struct mptcp_cb *mpcb = tcp_sk(sk)->mpcb;
++	const struct sock *sub_sk;
++	int best_cwnd = 0, best_rtt = 0, can_send = 0;
++	u64 max_numerator = 0, sum_denominator = 0, alpha = 1;
++
++	if (!mpcb)
++		return;
++
++	/* Only one subflow left - fall back to normal reno-behavior
++	 * (set alpha to 1)
++	 */
++	if (mpcb->cnt_established <= 1)
++		goto exit;
++
++	/* Do regular alpha-calculation for multiple subflows */
++
++	/* Find the max numerator of the alpha-calculation */
++	mptcp_for_each_sk(mpcb, sub_sk) {
++		struct tcp_sock *sub_tp = tcp_sk(sub_sk);
++		u64 tmp;
++
++		if (!mptcp_ccc_sk_can_send(sub_sk))
++			continue;
++
++		can_send++;
++
++		/* We need to look for the path, that provides the max-value.
++		 * Integer-overflow is not possible here, because
++		 * tmp will be in u64.
++		 */
++		tmp = div64_u64(mptcp_ccc_scale(sub_tp->snd_cwnd,
++				alpha_scale_num), (u64)sub_tp->srtt_us * sub_tp->srtt_us);
++
++		if (tmp >= max_numerator) {
++			max_numerator = tmp;
++			best_cwnd = sub_tp->snd_cwnd;
++			best_rtt = sub_tp->srtt_us;
++		}
++	}
++
++	/* No subflow is able to send - we don't care anymore */
++	if (unlikely(!can_send))
++		goto exit;
++
++	/* Calculate the denominator */
++	mptcp_for_each_sk(mpcb, sub_sk) {
++		struct tcp_sock *sub_tp = tcp_sk(sub_sk);
++
++		if (!mptcp_ccc_sk_can_send(sub_sk))
++			continue;
++
++		sum_denominator += div_u64(
++				mptcp_ccc_scale(sub_tp->snd_cwnd,
++						alpha_scale_den) * best_rtt,
++						sub_tp->srtt_us);
++	}
++	sum_denominator *= sum_denominator;
++	if (unlikely(!sum_denominator)) {
++		pr_err("%s: sum_denominator == 0, cnt_established:%d\n",
++		       __func__, mpcb->cnt_established);
++		mptcp_for_each_sk(mpcb, sub_sk) {
++			struct tcp_sock *sub_tp = tcp_sk(sub_sk);
++			pr_err("%s: pi:%d, state:%d\n, rtt:%u, cwnd: %u",
++			       __func__, sub_tp->mptcp->path_index,
++			       sub_sk->sk_state, sub_tp->srtt_us,
++			       sub_tp->snd_cwnd);
++		}
++	}
++
++	alpha = div64_u64(mptcp_ccc_scale(best_cwnd, alpha_scale_num), sum_denominator);
++
++	if (unlikely(!alpha))
++		alpha = 1;
++
++exit:
++	mptcp_set_alpha(mptcp_meta_sk(sk), alpha);
++}
++
++static void mptcp_ccc_init(struct sock *sk)
++{
++	if (mptcp(tcp_sk(sk))) {
++		mptcp_set_forced(mptcp_meta_sk(sk), 0);
++		mptcp_set_alpha(mptcp_meta_sk(sk), 1);
++	}
++	/* If we do not mptcp, behave like reno: return */
++}
++
++static void mptcp_ccc_cwnd_event(struct sock *sk, enum tcp_ca_event event)
++{
++	if (event == CA_EVENT_LOSS)
++		mptcp_ccc_recalc_alpha(sk);
++}
++
++static void mptcp_ccc_set_state(struct sock *sk, u8 ca_state)
++{
++	if (!mptcp(tcp_sk(sk)))
++		return;
++
++	mptcp_set_forced(mptcp_meta_sk(sk), 1);
++}
++
++static void mptcp_ccc_cong_avoid(struct sock *sk, u32 ack, u32 acked)
++{
++	struct tcp_sock *tp = tcp_sk(sk);
++	const struct mptcp_cb *mpcb = tp->mpcb;
++	int snd_cwnd;
++
++	if (!mptcp(tp)) {
++		tcp_reno_cong_avoid(sk, ack, acked);
++		return;
++	}
++
++	if (!tcp_is_cwnd_limited(sk))
++		return;
++
++	if (tp->snd_cwnd <= tp->snd_ssthresh) {
++		/* In "safe" area, increase. */
++		tcp_slow_start(tp, acked);
++		mptcp_ccc_recalc_alpha(sk);
++		return;
++	}
++
++	if (mptcp_get_forced(mptcp_meta_sk(sk))) {
++		mptcp_ccc_recalc_alpha(sk);
++		mptcp_set_forced(mptcp_meta_sk(sk), 0);
++	}
++
++	if (mpcb->cnt_established > 1) {
++		u64 alpha = mptcp_get_alpha(mptcp_meta_sk(sk));
++
++		/* This may happen, if at the initialization, the mpcb
++		 * was not yet attached to the sock, and thus
++		 * initializing alpha failed.
++		 */
++		if (unlikely(!alpha))
++			alpha = 1;
++
++		snd_cwnd = (int) div_u64 ((u64) mptcp_ccc_scale(1, alpha_scale),
++						alpha);
++
++		/* snd_cwnd_cnt >= max (scale * tot_cwnd / alpha, cwnd)
++		 * Thus, we select here the max value.
++		 */
++		if (snd_cwnd < tp->snd_cwnd)
++			snd_cwnd = tp->snd_cwnd;
++	} else {
++		snd_cwnd = tp->snd_cwnd;
++	}
++
++	if (tp->snd_cwnd_cnt >= snd_cwnd) {
++		if (tp->snd_cwnd < tp->snd_cwnd_clamp) {
++			tp->snd_cwnd++;
++			mptcp_ccc_recalc_alpha(sk);
++		}
++
++		tp->snd_cwnd_cnt = 0;
++	} else {
++		tp->snd_cwnd_cnt++;
++	}
++}
++
++static struct tcp_congestion_ops mptcp_ccc = {
++	.init		= mptcp_ccc_init,
++	.ssthresh	= tcp_reno_ssthresh,
++	.cong_avoid	= mptcp_ccc_cong_avoid,
++	.cwnd_event	= mptcp_ccc_cwnd_event,
++	.set_state	= mptcp_ccc_set_state,
++	.owner		= THIS_MODULE,
++	.name		= "lia",
++};
++
++static int __init mptcp_ccc_register(void)
++{
++	BUILD_BUG_ON(sizeof(struct mptcp_ccc) > ICSK_CA_PRIV_SIZE);
++	return tcp_register_congestion_control(&mptcp_ccc);
++}
++
++static void __exit mptcp_ccc_unregister(void)
++{
++	tcp_unregister_congestion_control(&mptcp_ccc);
++}
++
++module_init(mptcp_ccc_register);
++module_exit(mptcp_ccc_unregister);
++
++MODULE_AUTHOR("Christoph Paasch, Sébastien Barré");
++MODULE_LICENSE("GPL");
++MODULE_DESCRIPTION("MPTCP LINKED INCREASE CONGESTION CONTROL ALGORITHM");
++MODULE_VERSION("0.1");
+diff --git a/net/mptcp/mptcp_ctrl.c b/net/mptcp/mptcp_ctrl.c
+new file mode 100644
+index 000000000000..28dfa0479f5e
+--- /dev/null
++++ b/net/mptcp/mptcp_ctrl.c
+@@ -0,0 +1,2401 @@
++/*
++ *	MPTCP implementation - MPTCP-control
++ *
++ *	Initial Design & Implementation:
++ *	Sébastien Barré <sebastien.barre@×××××××××.be>
++ *
++ *	Current Maintainer & Author:
++ *	Christoph Paasch <christoph.paasch@×××××××××.be>
++ *
++ *	Additional authors:
++ *	Jaakko Korkeaniemi <jaakko.korkeaniemi@×××××.fi>
++ *	Gregory Detal <gregory.detal@×××××××××.be>
++ *	Fabien Duchêne <fabien.duchene@×××××××××.be>
++ *	Andreas Seelinger <Andreas.Seelinger@×××××××××××.de>
++ *	Lavkesh Lahngir <lavkesh51@×××××.com>
++ *	Andreas Ripke <ripke@××××××.eu>
++ *	Vlad Dogaru <vlad.dogaru@×××××.com>
++ *	Octavian Purdila <octavian.purdila@×××××.com>
++ *	John Ronan <jronan@××××.org>
++ *	Catalin Nicutar <catalin.nicutar@×××××.com>
++ *	Brandon Heller <brandonh@××××××××.edu>
++ *
++ *
++ *	This program is free software; you can redistribute it and/or
++ *      modify it under the terms of the GNU General Public License
++ *      as published by the Free Software Foundation; either version
++ *      2 of the License, or (at your option) any later version.
++ */
++
++#include <net/inet_common.h>
++#include <net/inet6_hashtables.h>
++#include <net/ipv6.h>
++#include <net/ip6_checksum.h>
++#include <net/mptcp.h>
++#include <net/mptcp_v4.h>
++#if IS_ENABLED(CONFIG_IPV6)
++#include <net/ip6_route.h>
++#include <net/mptcp_v6.h>
++#endif
++#include <net/sock.h>
++#include <net/tcp.h>
++#include <net/tcp_states.h>
++#include <net/transp_v6.h>
++#include <net/xfrm.h>
++
++#include <linux/cryptohash.h>
++#include <linux/kconfig.h>
++#include <linux/module.h>
++#include <linux/netpoll.h>
++#include <linux/list.h>
++#include <linux/jhash.h>
++#include <linux/tcp.h>
++#include <linux/net.h>
++#include <linux/in.h>
++#include <linux/random.h>
++#include <linux/inetdevice.h>
++#include <linux/workqueue.h>
++#include <linux/atomic.h>
++#include <linux/sysctl.h>
++
++static struct kmem_cache *mptcp_sock_cache __read_mostly;
++static struct kmem_cache *mptcp_cb_cache __read_mostly;
++static struct kmem_cache *mptcp_tw_cache __read_mostly;
++
++int sysctl_mptcp_enabled __read_mostly = 1;
++int sysctl_mptcp_checksum __read_mostly = 1;
++int sysctl_mptcp_debug __read_mostly;
++EXPORT_SYMBOL(sysctl_mptcp_debug);
++int sysctl_mptcp_syn_retries __read_mostly = 3;
++
++bool mptcp_init_failed __read_mostly;
++
++struct static_key mptcp_static_key = STATIC_KEY_INIT_FALSE;
++EXPORT_SYMBOL(mptcp_static_key);
++
++static int proc_mptcp_path_manager(ctl_table *ctl, int write,
++				   void __user *buffer, size_t *lenp,
++				   loff_t *ppos)
++{
++	char val[MPTCP_PM_NAME_MAX];
++	ctl_table tbl = {
++		.data = val,
++		.maxlen = MPTCP_PM_NAME_MAX,
++	};
++	int ret;
++
++	mptcp_get_default_path_manager(val);
++
++	ret = proc_dostring(&tbl, write, buffer, lenp, ppos);
++	if (write && ret == 0)
++		ret = mptcp_set_default_path_manager(val);
++	return ret;
++}
++
++static int proc_mptcp_scheduler(ctl_table *ctl, int write,
++				void __user *buffer, size_t *lenp,
++				loff_t *ppos)
++{
++	char val[MPTCP_SCHED_NAME_MAX];
++	ctl_table tbl = {
++		.data = val,
++		.maxlen = MPTCP_SCHED_NAME_MAX,
++	};
++	int ret;
++
++	mptcp_get_default_scheduler(val);
++
++	ret = proc_dostring(&tbl, write, buffer, lenp, ppos);
++	if (write && ret == 0)
++		ret = mptcp_set_default_scheduler(val);
++	return ret;
++}
++
++static struct ctl_table mptcp_table[] = {
++	{
++		.procname = "mptcp_enabled",
++		.data = &sysctl_mptcp_enabled,
++		.maxlen = sizeof(int),
++		.mode = 0644,
++		.proc_handler = &proc_dointvec
++	},
++	{
++		.procname = "mptcp_checksum",
++		.data = &sysctl_mptcp_checksum,
++		.maxlen = sizeof(int),
++		.mode = 0644,
++		.proc_handler = &proc_dointvec
++	},
++	{
++		.procname = "mptcp_debug",
++		.data = &sysctl_mptcp_debug,
++		.maxlen = sizeof(int),
++		.mode = 0644,
++		.proc_handler = &proc_dointvec
++	},
++	{
++		.procname = "mptcp_syn_retries",
++		.data = &sysctl_mptcp_syn_retries,
++		.maxlen = sizeof(int),
++		.mode = 0644,
++		.proc_handler = &proc_dointvec
++	},
++	{
++		.procname	= "mptcp_path_manager",
++		.mode		= 0644,
++		.maxlen		= MPTCP_PM_NAME_MAX,
++		.proc_handler	= proc_mptcp_path_manager,
++	},
++	{
++		.procname	= "mptcp_scheduler",
++		.mode		= 0644,
++		.maxlen		= MPTCP_SCHED_NAME_MAX,
++		.proc_handler	= proc_mptcp_scheduler,
++	},
++	{ }
++};
++
++static inline u32 mptcp_hash_tk(u32 token)
++{
++	return token % MPTCP_HASH_SIZE;
++}
++
++struct hlist_nulls_head tk_hashtable[MPTCP_HASH_SIZE];
++EXPORT_SYMBOL(tk_hashtable);
++
++/* This second hashtable is needed to retrieve request socks
++ * created as a result of a join request. While the SYN contains
++ * the token, the final ack does not, so we need a separate hashtable
++ * to retrieve the mpcb.
++ */
++struct hlist_nulls_head mptcp_reqsk_htb[MPTCP_HASH_SIZE];
++spinlock_t mptcp_reqsk_hlock;	/* hashtable protection */
++
++/* The following hash table is used to avoid collision of token */
++static struct hlist_nulls_head mptcp_reqsk_tk_htb[MPTCP_HASH_SIZE];
++spinlock_t mptcp_tk_hashlock;	/* hashtable protection */
++
++static bool mptcp_reqsk_find_tk(const u32 token)
++{
++	const u32 hash = mptcp_hash_tk(token);
++	const struct mptcp_request_sock *mtreqsk;
++	const struct hlist_nulls_node *node;
++
++begin:
++	hlist_nulls_for_each_entry_rcu(mtreqsk, node,
++				       &mptcp_reqsk_tk_htb[hash], hash_entry) {
++		if (token == mtreqsk->mptcp_loc_token)
++			return true;
++	}
++	/* A request-socket is destroyed by RCU. So, it might have been recycled
++	 * and put into another hash-table list. So, after the lookup we may
++	 * end up in a different list. So, we may need to restart.
++	 *
++	 * See also the comment in __inet_lookup_established.
++	 */
++	if (get_nulls_value(node) != hash)
++		goto begin;
++	return false;
++}
++
++static void mptcp_reqsk_insert_tk(struct request_sock *reqsk, const u32 token)
++{
++	u32 hash = mptcp_hash_tk(token);
++
++	hlist_nulls_add_head_rcu(&mptcp_rsk(reqsk)->hash_entry,
++				 &mptcp_reqsk_tk_htb[hash]);
++}
++
++static void mptcp_reqsk_remove_tk(const struct request_sock *reqsk)
++{
++	rcu_read_lock();
++	spin_lock(&mptcp_tk_hashlock);
++	hlist_nulls_del_init_rcu(&mptcp_rsk(reqsk)->hash_entry);
++	spin_unlock(&mptcp_tk_hashlock);
++	rcu_read_unlock();
++}
++
++void mptcp_reqsk_destructor(struct request_sock *req)
++{
++	if (!mptcp_rsk(req)->is_sub) {
++		if (in_softirq()) {
++			mptcp_reqsk_remove_tk(req);
++		} else {
++			rcu_read_lock_bh();
++			spin_lock(&mptcp_tk_hashlock);
++			hlist_nulls_del_init_rcu(&mptcp_rsk(req)->hash_entry);
++			spin_unlock(&mptcp_tk_hashlock);
++			rcu_read_unlock_bh();
++		}
++	} else {
++		mptcp_hash_request_remove(req);
++	}
++}
++
++static void __mptcp_hash_insert(struct tcp_sock *meta_tp, const u32 token)
++{
++	u32 hash = mptcp_hash_tk(token);
++	hlist_nulls_add_head_rcu(&meta_tp->tk_table, &tk_hashtable[hash]);
++	meta_tp->inside_tk_table = 1;
++}
++
++static bool mptcp_find_token(u32 token)
++{
++	const u32 hash = mptcp_hash_tk(token);
++	const struct tcp_sock *meta_tp;
++	const struct hlist_nulls_node *node;
++
++begin:
++	hlist_nulls_for_each_entry_rcu(meta_tp, node, &tk_hashtable[hash], tk_table) {
++		if (token == meta_tp->mptcp_loc_token)
++			return true;
++	}
++	/* A TCP-socket is destroyed by RCU. So, it might have been recycled
++	 * and put into another hash-table list. So, after the lookup we may
++	 * end up in a different list. So, we may need to restart.
++	 *
++	 * See also the comment in __inet_lookup_established.
++	 */
++	if (get_nulls_value(node) != hash)
++		goto begin;
++	return false;
++}
++
++static void mptcp_set_key_reqsk(struct request_sock *req,
++				const struct sk_buff *skb)
++{
++	const struct inet_request_sock *ireq = inet_rsk(req);
++	struct mptcp_request_sock *mtreq = mptcp_rsk(req);
++
++	if (skb->protocol == htons(ETH_P_IP)) {
++		mtreq->mptcp_loc_key = mptcp_v4_get_key(ip_hdr(skb)->saddr,
++							ip_hdr(skb)->daddr,
++							htons(ireq->ir_num),
++							ireq->ir_rmt_port);
++#if IS_ENABLED(CONFIG_IPV6)
++	} else {
++		mtreq->mptcp_loc_key = mptcp_v6_get_key(ipv6_hdr(skb)->saddr.s6_addr32,
++							ipv6_hdr(skb)->daddr.s6_addr32,
++							htons(ireq->ir_num),
++							ireq->ir_rmt_port);
++#endif
++	}
++
++	mptcp_key_sha1(mtreq->mptcp_loc_key, &mtreq->mptcp_loc_token, NULL);
++}
++
++/* New MPTCP-connection request, prepare a new token for the meta-socket that
++ * will be created in mptcp_check_req_master(), and store the received token.
++ */
++void mptcp_reqsk_new_mptcp(struct request_sock *req,
++			   const struct mptcp_options_received *mopt,
++			   const struct sk_buff *skb)
++{
++	struct mptcp_request_sock *mtreq = mptcp_rsk(req);
++
++	inet_rsk(req)->saw_mpc = 1;
++
++	rcu_read_lock();
++	spin_lock(&mptcp_tk_hashlock);
++	do {
++		mptcp_set_key_reqsk(req, skb);
++	} while (mptcp_reqsk_find_tk(mtreq->mptcp_loc_token) ||
++		 mptcp_find_token(mtreq->mptcp_loc_token));
++
++	mptcp_reqsk_insert_tk(req, mtreq->mptcp_loc_token);
++	spin_unlock(&mptcp_tk_hashlock);
++	rcu_read_unlock();
++	mtreq->mptcp_rem_key = mopt->mptcp_key;
++}
++
++static void mptcp_set_key_sk(const struct sock *sk)
++{
++	struct tcp_sock *tp = tcp_sk(sk);
++	const struct inet_sock *isk = inet_sk(sk);
++
++	if (sk->sk_family == AF_INET)
++		tp->mptcp_loc_key = mptcp_v4_get_key(isk->inet_saddr,
++						     isk->inet_daddr,
++						     isk->inet_sport,
++						     isk->inet_dport);
++#if IS_ENABLED(CONFIG_IPV6)
++	else
++		tp->mptcp_loc_key = mptcp_v6_get_key(inet6_sk(sk)->saddr.s6_addr32,
++						     sk->sk_v6_daddr.s6_addr32,
++						     isk->inet_sport,
++						     isk->inet_dport);
++#endif
++
++	mptcp_key_sha1(tp->mptcp_loc_key,
++		       &tp->mptcp_loc_token, NULL);
++}
++
++void mptcp_connect_init(struct sock *sk)
++{
++	struct tcp_sock *tp = tcp_sk(sk);
++
++	rcu_read_lock_bh();
++	spin_lock(&mptcp_tk_hashlock);
++	do {
++		mptcp_set_key_sk(sk);
++	} while (mptcp_reqsk_find_tk(tp->mptcp_loc_token) ||
++		 mptcp_find_token(tp->mptcp_loc_token));
++
++	__mptcp_hash_insert(tp, tp->mptcp_loc_token);
++	spin_unlock(&mptcp_tk_hashlock);
++	rcu_read_unlock_bh();
++}
++
++/**
++ * This function increments the refcount of the mpcb struct.
++ * It is the responsibility of the caller to decrement when releasing
++ * the structure.
++ */
++struct sock *mptcp_hash_find(const struct net *net, const u32 token)
++{
++	const u32 hash = mptcp_hash_tk(token);
++	const struct tcp_sock *meta_tp;
++	struct sock *meta_sk = NULL;
++	const struct hlist_nulls_node *node;
++
++	rcu_read_lock();
++begin:
++	hlist_nulls_for_each_entry_rcu(meta_tp, node, &tk_hashtable[hash],
++				       tk_table) {
++		meta_sk = (struct sock *)meta_tp;
++		if (token == meta_tp->mptcp_loc_token &&
++		    net_eq(net, sock_net(meta_sk))) {
++			if (unlikely(!atomic_inc_not_zero(&meta_sk->sk_refcnt)))
++				goto out;
++			if (unlikely(token != meta_tp->mptcp_loc_token ||
++				     !net_eq(net, sock_net(meta_sk)))) {
++				sock_gen_put(meta_sk);
++				goto begin;
++			}
++			goto found;
++		}
++	}
++	/* A TCP-socket is destroyed by RCU. So, it might have been recycled
++	 * and put into another hash-table list. So, after the lookup we may
++	 * end up in a different list. So, we may need to restart.
++	 *
++	 * See also the comment in __inet_lookup_established.
++	 */
++	if (get_nulls_value(node) != hash)
++		goto begin;
++out:
++	meta_sk = NULL;
++found:
++	rcu_read_unlock();
++	return meta_sk;
++}
++
++void mptcp_hash_remove_bh(struct tcp_sock *meta_tp)
++{
++	/* remove from the token hashtable */
++	rcu_read_lock_bh();
++	spin_lock(&mptcp_tk_hashlock);
++	hlist_nulls_del_init_rcu(&meta_tp->tk_table);
++	meta_tp->inside_tk_table = 0;
++	spin_unlock(&mptcp_tk_hashlock);
++	rcu_read_unlock_bh();
++}
++
++void mptcp_hash_remove(struct tcp_sock *meta_tp)
++{
++	rcu_read_lock();
++	spin_lock(&mptcp_tk_hashlock);
++	hlist_nulls_del_init_rcu(&meta_tp->tk_table);
++	meta_tp->inside_tk_table = 0;
++	spin_unlock(&mptcp_tk_hashlock);
++	rcu_read_unlock();
++}
++
++struct sock *mptcp_select_ack_sock(const struct sock *meta_sk)
++{
++	const struct tcp_sock *meta_tp = tcp_sk(meta_sk);
++	struct sock *sk, *rttsk = NULL, *lastsk = NULL;
++	u32 min_time = 0, last_active = 0;
++
++	mptcp_for_each_sk(meta_tp->mpcb, sk) {
++		struct tcp_sock *tp = tcp_sk(sk);
++		u32 elapsed;
++
++		if (!mptcp_sk_can_send_ack(sk) || tp->pf)
++			continue;
++
++		elapsed = keepalive_time_elapsed(tp);
++
++		/* We take the one with the lowest RTT within a reasonable
++		 * (meta-RTO)-timeframe
++		 */
++		if (elapsed < inet_csk(meta_sk)->icsk_rto) {
++			if (!min_time || tp->srtt_us < min_time) {
++				min_time = tp->srtt_us;
++				rttsk = sk;
++			}
++			continue;
++		}
++
++		/* Otherwise, we just take the most recent active */
++		if (!rttsk && (!last_active || elapsed < last_active)) {
++			last_active = elapsed;
++			lastsk = sk;
++		}
++	}
++
++	if (rttsk)
++		return rttsk;
++
++	return lastsk;
++}
++EXPORT_SYMBOL(mptcp_select_ack_sock);
++
++static void mptcp_sock_def_error_report(struct sock *sk)
++{
++	const struct mptcp_cb *mpcb = tcp_sk(sk)->mpcb;
++
++	if (!sock_flag(sk, SOCK_DEAD))
++		mptcp_sub_close(sk, 0);
++
++	if (mpcb->infinite_mapping_rcv || mpcb->infinite_mapping_snd ||
++	    mpcb->send_infinite_mapping) {
++		struct sock *meta_sk = mptcp_meta_sk(sk);
++
++		meta_sk->sk_err = sk->sk_err;
++		meta_sk->sk_err_soft = sk->sk_err_soft;
++
++		if (!sock_flag(meta_sk, SOCK_DEAD))
++			meta_sk->sk_error_report(meta_sk);
++
++		tcp_done(meta_sk);
++	}
++
++	sk->sk_err = 0;
++	return;
++}
++
++static void mptcp_mpcb_put(struct mptcp_cb *mpcb)
++{
++	if (atomic_dec_and_test(&mpcb->mpcb_refcnt)) {
++		mptcp_cleanup_path_manager(mpcb);
++		mptcp_cleanup_scheduler(mpcb);
++		kmem_cache_free(mptcp_cb_cache, mpcb);
++	}
++}
++
++static void mptcp_sock_destruct(struct sock *sk)
++{
++	struct tcp_sock *tp = tcp_sk(sk);
++
++	inet_sock_destruct(sk);
++
++	if (!is_meta_sk(sk) && !tp->was_meta_sk) {
++		BUG_ON(!hlist_unhashed(&tp->mptcp->cb_list));
++
++		kmem_cache_free(mptcp_sock_cache, tp->mptcp);
++		tp->mptcp = NULL;
++
++		/* Taken when mpcb pointer was set */
++		sock_put(mptcp_meta_sk(sk));
++		mptcp_mpcb_put(tp->mpcb);
++	} else {
++		struct mptcp_cb *mpcb = tp->mpcb;
++		struct mptcp_tw *mptw;
++
++		/* The mpcb is disappearing - we can make the final
++		 * update to the rcv_nxt of the time-wait-sock and remove
++		 * its reference to the mpcb.
++		 */
++		spin_lock_bh(&mpcb->tw_lock);
++		list_for_each_entry_rcu(mptw, &mpcb->tw_list, list) {
++			list_del_rcu(&mptw->list);
++			mptw->in_list = 0;
++			mptcp_mpcb_put(mpcb);
++			rcu_assign_pointer(mptw->mpcb, NULL);
++		}
++		spin_unlock_bh(&mpcb->tw_lock);
++
++		mptcp_mpcb_put(mpcb);
++
++		mptcp_debug("%s destroying meta-sk\n", __func__);
++	}
++
++	WARN_ON(!static_key_false(&mptcp_static_key));
++	/* Must be the last call, because is_meta_sk() above still needs the
++	 * static key
++	 */
++	static_key_slow_dec(&mptcp_static_key);
++}
++
++void mptcp_destroy_sock(struct sock *sk)
++{
++	if (is_meta_sk(sk)) {
++		struct sock *sk_it, *tmpsk;
++
++		__skb_queue_purge(&tcp_sk(sk)->mpcb->reinject_queue);
++		mptcp_purge_ofo_queue(tcp_sk(sk));
++
++		/* We have to close all remaining subflows. Normally, they
++		 * should all be about to get closed. But, if the kernel is
++		 * forcing a closure (e.g., tcp_write_err), the subflows might
++		 * not have been closed properly (as we are waiting for the
++		 * DATA_ACK of the DATA_FIN).
++		 */
++		mptcp_for_each_sk_safe(tcp_sk(sk)->mpcb, sk_it, tmpsk) {
++			/* Already did call tcp_close - waiting for graceful
++			 * closure, or if we are retransmitting fast-close on
++			 * the subflow. The reset (or timeout) will kill the
++			 * subflow..
++			 */
++			if (tcp_sk(sk_it)->closing ||
++			    tcp_sk(sk_it)->send_mp_fclose)
++				continue;
++
++			/* Allow the delayed work first to prevent time-wait state */
++			if (delayed_work_pending(&tcp_sk(sk_it)->mptcp->work))
++				continue;
++
++			mptcp_sub_close(sk_it, 0);
++		}
++
++		mptcp_delete_synack_timer(sk);
++	} else {
++		mptcp_del_sock(sk);
++	}
++}
++
++static void mptcp_set_state(struct sock *sk)
++{
++	struct sock *meta_sk = mptcp_meta_sk(sk);
++
++	/* Meta is not yet established - wake up the application */
++	if ((1 << meta_sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV) &&
++	    sk->sk_state == TCP_ESTABLISHED) {
++		tcp_set_state(meta_sk, TCP_ESTABLISHED);
++
++		if (!sock_flag(meta_sk, SOCK_DEAD)) {
++			meta_sk->sk_state_change(meta_sk);
++			sk_wake_async(meta_sk, SOCK_WAKE_IO, POLL_OUT);
++		}
++	}
++
++	if (sk->sk_state == TCP_ESTABLISHED) {
++		tcp_sk(sk)->mptcp->establish_increased = 1;
++		tcp_sk(sk)->mpcb->cnt_established++;
++	}
++}
++
++void mptcp_init_congestion_control(struct sock *sk)
++{
++	struct inet_connection_sock *icsk = inet_csk(sk);
++	struct inet_connection_sock *meta_icsk = inet_csk(mptcp_meta_sk(sk));
++	const struct tcp_congestion_ops *ca = meta_icsk->icsk_ca_ops;
++
++	/* The application didn't set the congestion control to use
++	 * fallback to the default one.
++	 */
++	if (ca == &tcp_init_congestion_ops)
++		goto use_default;
++
++	/* Use the same congestion control as set by the user. If the
++	 * module is not available fallback to the default one.
++	 */
++	if (!try_module_get(ca->owner)) {
++		pr_warn("%s: fallback to the system default CC\n", __func__);
++		goto use_default;
++	}
++
++	icsk->icsk_ca_ops = ca;
++	if (icsk->icsk_ca_ops->init)
++		icsk->icsk_ca_ops->init(sk);
++
++	return;
++
++use_default:
++	icsk->icsk_ca_ops = &tcp_init_congestion_ops;
++	tcp_init_congestion_control(sk);
++}
++
++u32 mptcp_secret[MD5_MESSAGE_BYTES / 4] ____cacheline_aligned;
++u32 mptcp_seed = 0;
++
++void mptcp_key_sha1(u64 key, u32 *token, u64 *idsn)
++{
++	u32 workspace[SHA_WORKSPACE_WORDS];
++	u32 mptcp_hashed_key[SHA_DIGEST_WORDS];
++	u8 input[64];
++	int i;
++
++	memset(workspace, 0, sizeof(workspace));
++
++	/* Initialize input with appropriate padding */
++	memset(&input[9], 0, sizeof(input) - 10); /* -10, because the last byte
++						   * is explicitly set too
++						   */
++	memcpy(input, &key, sizeof(key)); /* Copy key to the msg beginning */
++	input[8] = 0x80; /* Padding: First bit after message = 1 */
++	input[63] = 0x40; /* Padding: Length of the message = 64 bits */
++
++	sha_init(mptcp_hashed_key);
++	sha_transform(mptcp_hashed_key, input, workspace);
++
++	for (i = 0; i < 5; i++)
++		mptcp_hashed_key[i] = cpu_to_be32(mptcp_hashed_key[i]);
++
++	if (token)
++		*token = mptcp_hashed_key[0];
++	if (idsn)
++		*idsn = *((u64 *)&mptcp_hashed_key[3]);
++}
++
++void mptcp_hmac_sha1(u8 *key_1, u8 *key_2, u8 *rand_1, u8 *rand_2,
++		       u32 *hash_out)
++{
++	u32 workspace[SHA_WORKSPACE_WORDS];
++	u8 input[128]; /* 2 512-bit blocks */
++	int i;
++
++	memset(workspace, 0, sizeof(workspace));
++
++	/* Generate key xored with ipad */
++	memset(input, 0x36, 64);
++	for (i = 0; i < 8; i++)
++		input[i] ^= key_1[i];
++	for (i = 0; i < 8; i++)
++		input[i + 8] ^= key_2[i];
++
++	memcpy(&input[64], rand_1, 4);
++	memcpy(&input[68], rand_2, 4);
++	input[72] = 0x80; /* Padding: First bit after message = 1 */
++	memset(&input[73], 0, 53);
++
++	/* Padding: Length of the message = 512 + 64 bits */
++	input[126] = 0x02;
++	input[127] = 0x40;
++
++	sha_init(hash_out);
++	sha_transform(hash_out, input, workspace);
++	memset(workspace, 0, sizeof(workspace));
++
++	sha_transform(hash_out, &input[64], workspace);
++	memset(workspace, 0, sizeof(workspace));
++
++	for (i = 0; i < 5; i++)
++		hash_out[i] = cpu_to_be32(hash_out[i]);
++
++	/* Prepare second part of hmac */
++	memset(input, 0x5C, 64);
++	for (i = 0; i < 8; i++)
++		input[i] ^= key_1[i];
++	for (i = 0; i < 8; i++)
++		input[i + 8] ^= key_2[i];
++
++	memcpy(&input[64], hash_out, 20);
++	input[84] = 0x80;
++	memset(&input[85], 0, 41);
++
++	/* Padding: Length of the message = 512 + 160 bits */
++	input[126] = 0x02;
++	input[127] = 0xA0;
++
++	sha_init(hash_out);
++	sha_transform(hash_out, input, workspace);
++	memset(workspace, 0, sizeof(workspace));
++
++	sha_transform(hash_out, &input[64], workspace);
++
++	for (i = 0; i < 5; i++)
++		hash_out[i] = cpu_to_be32(hash_out[i]);
++}
++
++static void mptcp_mpcb_inherit_sockopts(struct sock *meta_sk, struct sock *master_sk)
++{
++	/* Socket-options handled by sk_clone_lock while creating the meta-sk.
++	 * ======
++	 * SO_SNDBUF, SO_SNDBUFFORCE, SO_RCVBUF, SO_RCVBUFFORCE, SO_RCVLOWAT,
++	 * SO_RCVTIMEO, SO_SNDTIMEO, SO_ATTACH_FILTER, SO_DETACH_FILTER,
++	 * TCP_NODELAY, TCP_CORK
++	 *
++	 * Socket-options handled in this function here
++	 * ======
++	 * TCP_DEFER_ACCEPT
++	 * SO_KEEPALIVE
++	 *
++	 * Socket-options on the todo-list
++	 * ======
++	 * SO_BINDTODEVICE - should probably prevent creation of new subsocks
++	 *		     across other devices. - what about the api-draft?
++	 * SO_DEBUG
++	 * SO_REUSEADDR - probably we don't care about this
++	 * SO_DONTROUTE, SO_BROADCAST
++	 * SO_OOBINLINE
++	 * SO_LINGER
++	 * SO_TIMESTAMP* - I don't think this is of concern for a SOCK_STREAM
++	 * SO_PASSSEC - I don't think this is of concern for a SOCK_STREAM
++	 * SO_RXQ_OVFL
++	 * TCP_COOKIE_TRANSACTIONS
++	 * TCP_MAXSEG
++	 * TCP_THIN_* - Handled by sk_clone_lock, but we need to support this
++	 *		in mptcp_retransmit_timer. AND we need to check what is
++	 *		about the subsockets.
++	 * TCP_LINGER2
++	 * TCP_WINDOW_CLAMP
++	 * TCP_USER_TIMEOUT
++	 * TCP_MD5SIG
++	 *
++	 * Socket-options of no concern for the meta-socket (but for the subsocket)
++	 * ======
++	 * SO_PRIORITY
++	 * SO_MARK
++	 * TCP_CONGESTION
++	 * TCP_SYNCNT
++	 * TCP_QUICKACK
++	 */
++
++	/* DEFER_ACCEPT should not be set on the meta, as we want to accept new subflows directly */
++	inet_csk(meta_sk)->icsk_accept_queue.rskq_defer_accept = 0;
++
++	/* Keepalives are handled entirely at the MPTCP-layer */
++	if (sock_flag(meta_sk, SOCK_KEEPOPEN)) {
++		inet_csk_reset_keepalive_timer(meta_sk,
++					       keepalive_time_when(tcp_sk(meta_sk)));
++		sock_reset_flag(master_sk, SOCK_KEEPOPEN);
++		inet_csk_delete_keepalive_timer(master_sk);
++	}
++
++	/* Do not propagate subflow-errors up to the MPTCP-layer */
++	inet_sk(master_sk)->recverr = 0;
++}
++
++static void mptcp_sub_inherit_sockopts(const struct sock *meta_sk, struct sock *sub_sk)
++{
++	/* IP_TOS also goes to the subflow. */
++	if (inet_sk(sub_sk)->tos != inet_sk(meta_sk)->tos) {
++		inet_sk(sub_sk)->tos = inet_sk(meta_sk)->tos;
++		sub_sk->sk_priority = meta_sk->sk_priority;
++		sk_dst_reset(sub_sk);
++	}
++
++	/* Inherit SO_REUSEADDR */
++	sub_sk->sk_reuse = meta_sk->sk_reuse;
++
++	/* Inherit snd/rcv-buffer locks */
++	sub_sk->sk_userlocks = meta_sk->sk_userlocks & ~SOCK_BINDPORT_LOCK;
++
++	/* Nagle/Cork is forced off on the subflows. It is handled at the meta-layer */
++	tcp_sk(sub_sk)->nonagle = TCP_NAGLE_OFF|TCP_NAGLE_PUSH;
++
++	/* Keepalives are handled entirely at the MPTCP-layer */
++	if (sock_flag(sub_sk, SOCK_KEEPOPEN)) {
++		sock_reset_flag(sub_sk, SOCK_KEEPOPEN);
++		inet_csk_delete_keepalive_timer(sub_sk);
++	}
++
++	/* Do not propagate subflow-errors up to the MPTCP-layer */
++	inet_sk(sub_sk)->recverr = 0;
++}
++
++int mptcp_backlog_rcv(struct sock *meta_sk, struct sk_buff *skb)
++{
++	/* skb-sk may be NULL if we receive a packet immediatly after the
++	 * SYN/ACK + MP_CAPABLE.
++	 */
++	struct sock *sk = skb->sk ? skb->sk : meta_sk;
++	int ret = 0;
++
++	skb->sk = NULL;
++
++	if (unlikely(!atomic_inc_not_zero(&sk->sk_refcnt))) {
++		kfree_skb(skb);
++		return 0;
++	}
++
++	if (sk->sk_family == AF_INET)
++		ret = tcp_v4_do_rcv(sk, skb);
++#if IS_ENABLED(CONFIG_IPV6)
++	else
++		ret = tcp_v6_do_rcv(sk, skb);
++#endif
++
++	sock_put(sk);
++	return ret;
++}
++
++struct lock_class_key meta_key;
++struct lock_class_key meta_slock_key;
++
++static void mptcp_synack_timer_handler(unsigned long data)
++{
++	struct sock *meta_sk = (struct sock *) data;
++	struct listen_sock *lopt = inet_csk(meta_sk)->icsk_accept_queue.listen_opt;
++
++	/* Only process if socket is not in use. */
++	bh_lock_sock(meta_sk);
++
++	if (sock_owned_by_user(meta_sk)) {
++		/* Try again later. */
++		mptcp_reset_synack_timer(meta_sk, HZ/20);
++		goto out;
++	}
++
++	/* May happen if the queue got destructed in mptcp_close */
++	if (!lopt)
++		goto out;
++
++	inet_csk_reqsk_queue_prune(meta_sk, TCP_SYNQ_INTERVAL,
++				   TCP_TIMEOUT_INIT, TCP_RTO_MAX);
++
++	if (lopt->qlen)
++		mptcp_reset_synack_timer(meta_sk, TCP_SYNQ_INTERVAL);
++
++out:
++	bh_unlock_sock(meta_sk);
++	sock_put(meta_sk);
++}
++
++static const struct tcp_sock_ops mptcp_meta_specific = {
++	.__select_window		= __mptcp_select_window,
++	.select_window			= mptcp_select_window,
++	.select_initial_window		= mptcp_select_initial_window,
++	.init_buffer_space		= mptcp_init_buffer_space,
++	.set_rto			= mptcp_tcp_set_rto,
++	.should_expand_sndbuf		= mptcp_should_expand_sndbuf,
++	.init_congestion_control	= mptcp_init_congestion_control,
++	.send_fin			= mptcp_send_fin,
++	.write_xmit			= mptcp_write_xmit,
++	.send_active_reset		= mptcp_send_active_reset,
++	.write_wakeup			= mptcp_write_wakeup,
++	.prune_ofo_queue		= mptcp_prune_ofo_queue,
++	.retransmit_timer		= mptcp_retransmit_timer,
++	.time_wait			= mptcp_time_wait,
++	.cleanup_rbuf			= mptcp_cleanup_rbuf,
++};
++
++static const struct tcp_sock_ops mptcp_sub_specific = {
++	.__select_window		= __mptcp_select_window,
++	.select_window			= mptcp_select_window,
++	.select_initial_window		= mptcp_select_initial_window,
++	.init_buffer_space		= mptcp_init_buffer_space,
++	.set_rto			= mptcp_tcp_set_rto,
++	.should_expand_sndbuf		= mptcp_should_expand_sndbuf,
++	.init_congestion_control	= mptcp_init_congestion_control,
++	.send_fin			= tcp_send_fin,
++	.write_xmit			= tcp_write_xmit,
++	.send_active_reset		= tcp_send_active_reset,
++	.write_wakeup			= tcp_write_wakeup,
++	.prune_ofo_queue		= tcp_prune_ofo_queue,
++	.retransmit_timer		= tcp_retransmit_timer,
++	.time_wait			= tcp_time_wait,
++	.cleanup_rbuf			= tcp_cleanup_rbuf,
++};
++
++static int mptcp_alloc_mpcb(struct sock *meta_sk, __u64 remote_key, u32 window)
++{
++	struct mptcp_cb *mpcb;
++	struct sock *master_sk;
++	struct inet_connection_sock *master_icsk, *meta_icsk = inet_csk(meta_sk);
++	struct tcp_sock *master_tp, *meta_tp = tcp_sk(meta_sk);
++	u64 idsn;
++
++	dst_release(meta_sk->sk_rx_dst);
++	meta_sk->sk_rx_dst = NULL;
++	/* This flag is set to announce sock_lock_init to
++	 * reclassify the lock-class of the master socket.
++	 */
++	meta_tp->is_master_sk = 1;
++	master_sk = sk_clone_lock(meta_sk, GFP_ATOMIC | __GFP_ZERO);
++	meta_tp->is_master_sk = 0;
++	if (!master_sk)
++		return -ENOBUFS;
++
++	master_tp = tcp_sk(master_sk);
++	master_icsk = inet_csk(master_sk);
++
++	mpcb = kmem_cache_zalloc(mptcp_cb_cache, GFP_ATOMIC);
++	if (!mpcb) {
++		/* sk_free (and __sk_free) requirese wmem_alloc to be 1.
++		 * All the rest is set to 0 thanks to __GFP_ZERO above.
++		 */
++		atomic_set(&master_sk->sk_wmem_alloc, 1);
++		sk_free(master_sk);
++		return -ENOBUFS;
++	}
++
++#if IS_ENABLED(CONFIG_IPV6)
++	if (meta_icsk->icsk_af_ops == &mptcp_v6_mapped) {
++		struct ipv6_pinfo *newnp, *np = inet6_sk(meta_sk);
++
++		inet_sk(master_sk)->pinet6 = &((struct tcp6_sock *)master_sk)->inet6;
++
++		newnp = inet6_sk(master_sk);
++		memcpy(newnp, np, sizeof(struct ipv6_pinfo));
++
++		newnp->ipv6_mc_list = NULL;
++		newnp->ipv6_ac_list = NULL;
++		newnp->ipv6_fl_list = NULL;
++		newnp->opt = NULL;
++		newnp->pktoptions = NULL;
++		(void)xchg(&newnp->rxpmtu, NULL);
++	} else if (meta_sk->sk_family == AF_INET6) {
++		struct ipv6_pinfo *newnp, *np = inet6_sk(meta_sk);
++
++		inet_sk(master_sk)->pinet6 = &((struct tcp6_sock *)master_sk)->inet6;
++
++		newnp = inet6_sk(master_sk);
++		memcpy(newnp, np, sizeof(struct ipv6_pinfo));
++
++		newnp->hop_limit	= -1;
++		newnp->mcast_hops	= IPV6_DEFAULT_MCASTHOPS;
++		newnp->mc_loop	= 1;
++		newnp->pmtudisc	= IPV6_PMTUDISC_WANT;
++		newnp->ipv6only	= sock_net(master_sk)->ipv6.sysctl.bindv6only;
++	}
++#endif
++
++	meta_tp->mptcp = NULL;
++
++	/* Store the keys and generate the peer's token */
++	mpcb->mptcp_loc_key = meta_tp->mptcp_loc_key;
++	mpcb->mptcp_loc_token = meta_tp->mptcp_loc_token;
++
++	/* Generate Initial data-sequence-numbers */
++	mptcp_key_sha1(mpcb->mptcp_loc_key, NULL, &idsn);
++	idsn = ntohll(idsn) + 1;
++	mpcb->snd_high_order[0] = idsn >> 32;
++	mpcb->snd_high_order[1] = mpcb->snd_high_order[0] - 1;
++
++	meta_tp->write_seq = (u32)idsn;
++	meta_tp->snd_sml = meta_tp->write_seq;
++	meta_tp->snd_una = meta_tp->write_seq;
++	meta_tp->snd_nxt = meta_tp->write_seq;
++	meta_tp->pushed_seq = meta_tp->write_seq;
++	meta_tp->snd_up = meta_tp->write_seq;
++
++	mpcb->mptcp_rem_key = remote_key;
++	mptcp_key_sha1(mpcb->mptcp_rem_key, &mpcb->mptcp_rem_token, &idsn);
++	idsn = ntohll(idsn) + 1;
++	mpcb->rcv_high_order[0] = idsn >> 32;
++	mpcb->rcv_high_order[1] = mpcb->rcv_high_order[0] + 1;
++	meta_tp->copied_seq = (u32) idsn;
++	meta_tp->rcv_nxt = (u32) idsn;
++	meta_tp->rcv_wup = (u32) idsn;
++
++	meta_tp->snd_wl1 = meta_tp->rcv_nxt - 1;
++	meta_tp->snd_wnd = window;
++	meta_tp->retrans_stamp = 0; /* Set in tcp_connect() */
++
++	meta_tp->packets_out = 0;
++	meta_icsk->icsk_probes_out = 0;
++
++	/* Set mptcp-pointers */
++	master_tp->mpcb = mpcb;
++	master_tp->meta_sk = meta_sk;
++	meta_tp->mpcb = mpcb;
++	meta_tp->meta_sk = meta_sk;
++	mpcb->meta_sk = meta_sk;
++	mpcb->master_sk = master_sk;
++
++	meta_tp->was_meta_sk = 0;
++
++	/* Initialize the queues */
++	skb_queue_head_init(&mpcb->reinject_queue);
++	skb_queue_head_init(&master_tp->out_of_order_queue);
++	tcp_prequeue_init(master_tp);
++	INIT_LIST_HEAD(&master_tp->tsq_node);
++
++	master_tp->tsq_flags = 0;
++
++	mutex_init(&mpcb->mpcb_mutex);
++
++	/* Init the accept_queue structure, we support a queue of 32 pending
++	 * connections, it does not need to be huge, since we only store  here
++	 * pending subflow creations.
++	 */
++	if (reqsk_queue_alloc(&meta_icsk->icsk_accept_queue, 32, GFP_ATOMIC)) {
++		inet_put_port(master_sk);
++		kmem_cache_free(mptcp_cb_cache, mpcb);
++		sk_free(master_sk);
++		return -ENOMEM;
++	}
++
++	/* Redefine function-pointers as the meta-sk is now fully ready */
++	static_key_slow_inc(&mptcp_static_key);
++	meta_tp->mpc = 1;
++	meta_tp->ops = &mptcp_meta_specific;
++
++	meta_sk->sk_backlog_rcv = mptcp_backlog_rcv;
++	meta_sk->sk_destruct = mptcp_sock_destruct;
++
++	/* Meta-level retransmit timer */
++	meta_icsk->icsk_rto *= 2; /* Double of initial - rto */
++
++	tcp_init_xmit_timers(master_sk);
++	/* Has been set for sending out the SYN */
++	inet_csk_clear_xmit_timer(meta_sk, ICSK_TIME_RETRANS);
++
++	if (!meta_tp->inside_tk_table) {
++		/* Adding the meta_tp in the token hashtable - coming from server-side */
++		rcu_read_lock();
++		spin_lock(&mptcp_tk_hashlock);
++
++		__mptcp_hash_insert(meta_tp, mpcb->mptcp_loc_token);
++
++		spin_unlock(&mptcp_tk_hashlock);
++		rcu_read_unlock();
++	}
++	master_tp->inside_tk_table = 0;
++
++	/* Init time-wait stuff */
++	INIT_LIST_HEAD(&mpcb->tw_list);
++	spin_lock_init(&mpcb->tw_lock);
++
++	INIT_HLIST_HEAD(&mpcb->callback_list);
++
++	mptcp_mpcb_inherit_sockopts(meta_sk, master_sk);
++
++	mpcb->orig_sk_rcvbuf = meta_sk->sk_rcvbuf;
++	mpcb->orig_sk_sndbuf = meta_sk->sk_sndbuf;
++	mpcb->orig_window_clamp = meta_tp->window_clamp;
++
++	/* The meta is directly linked - set refcnt to 1 */
++	atomic_set(&mpcb->mpcb_refcnt, 1);
++
++	mptcp_init_path_manager(mpcb);
++	mptcp_init_scheduler(mpcb);
++
++	setup_timer(&mpcb->synack_timer, mptcp_synack_timer_handler,
++		    (unsigned long)meta_sk);
++
++	mptcp_debug("%s: created mpcb with token %#x\n",
++		    __func__, mpcb->mptcp_loc_token);
++
++	return 0;
++}
++
++void mptcp_fallback_meta_sk(struct sock *meta_sk)
++{
++	kfree(inet_csk(meta_sk)->icsk_accept_queue.listen_opt);
++	kmem_cache_free(mptcp_cb_cache, tcp_sk(meta_sk)->mpcb);
++}
++
++int mptcp_add_sock(struct sock *meta_sk, struct sock *sk, u8 loc_id, u8 rem_id,
++		   gfp_t flags)
++{
++	struct mptcp_cb *mpcb	= tcp_sk(meta_sk)->mpcb;
++	struct tcp_sock *tp	= tcp_sk(sk);
++
++	tp->mptcp = kmem_cache_zalloc(mptcp_sock_cache, flags);
++	if (!tp->mptcp)
++		return -ENOMEM;
++
++	tp->mptcp->path_index = mptcp_set_new_pathindex(mpcb);
++	/* No more space for more subflows? */
++	if (!tp->mptcp->path_index) {
++		kmem_cache_free(mptcp_sock_cache, tp->mptcp);
++		return -EPERM;
++	}
++
++	INIT_HLIST_NODE(&tp->mptcp->cb_list);
++
++	tp->mptcp->tp = tp;
++	tp->mpcb = mpcb;
++	tp->meta_sk = meta_sk;
++
++	static_key_slow_inc(&mptcp_static_key);
++	tp->mpc = 1;
++	tp->ops = &mptcp_sub_specific;
++
++	tp->mptcp->loc_id = loc_id;
++	tp->mptcp->rem_id = rem_id;
++	if (mpcb->sched_ops->init)
++		mpcb->sched_ops->init(sk);
++
++	/* The corresponding sock_put is in mptcp_sock_destruct(). It cannot be
++	 * included in mptcp_del_sock(), because the mpcb must remain alive
++	 * until the last subsocket is completely destroyed.
++	 */
++	sock_hold(meta_sk);
++	atomic_inc(&mpcb->mpcb_refcnt);
++
++	tp->mptcp->next = mpcb->connection_list;
++	mpcb->connection_list = tp;
++	tp->mptcp->attached = 1;
++
++	mpcb->cnt_subflows++;
++	atomic_add(atomic_read(&((struct sock *)tp)->sk_rmem_alloc),
++		   &meta_sk->sk_rmem_alloc);
++
++	mptcp_sub_inherit_sockopts(meta_sk, sk);
++	INIT_DELAYED_WORK(&tp->mptcp->work, mptcp_sub_close_wq);
++
++	/* As we successfully allocated the mptcp_tcp_sock, we have to
++	 * change the function-pointers here (for sk_destruct to work correctly)
++	 */
++	sk->sk_error_report = mptcp_sock_def_error_report;
++	sk->sk_data_ready = mptcp_data_ready;
++	sk->sk_write_space = mptcp_write_space;
++	sk->sk_state_change = mptcp_set_state;
++	sk->sk_destruct = mptcp_sock_destruct;
++
++	if (sk->sk_family == AF_INET)
++		mptcp_debug("%s: token %#x pi %d, src_addr:%pI4:%d dst_addr:%pI4:%d, cnt_subflows now %d\n",
++			    __func__ , mpcb->mptcp_loc_token,
++			    tp->mptcp->path_index,
++			    &((struct inet_sock *)tp)->inet_saddr,
++			    ntohs(((struct inet_sock *)tp)->inet_sport),
++			    &((struct inet_sock *)tp)->inet_daddr,
++			    ntohs(((struct inet_sock *)tp)->inet_dport),
++			    mpcb->cnt_subflows);
++#if IS_ENABLED(CONFIG_IPV6)
++	else
++		mptcp_debug("%s: token %#x pi %d, src_addr:%pI6:%d dst_addr:%pI6:%d, cnt_subflows now %d\n",
++			    __func__ , mpcb->mptcp_loc_token,
++			    tp->mptcp->path_index, &inet6_sk(sk)->saddr,
++			    ntohs(((struct inet_sock *)tp)->inet_sport),
++			    &sk->sk_v6_daddr,
++			    ntohs(((struct inet_sock *)tp)->inet_dport),
++			    mpcb->cnt_subflows);
++#endif
++
++	return 0;
++}
++
++void mptcp_del_sock(struct sock *sk)
++{
++	struct tcp_sock *tp = tcp_sk(sk), *tp_prev;
++	struct mptcp_cb *mpcb;
++
++	if (!tp->mptcp || !tp->mptcp->attached)
++		return;
++
++	mpcb = tp->mpcb;
++	tp_prev = mpcb->connection_list;
++
++	mptcp_debug("%s: Removing subsock tok %#x pi:%d state %d is_meta? %d\n",
++		    __func__, mpcb->mptcp_loc_token, tp->mptcp->path_index,
++		    sk->sk_state, is_meta_sk(sk));
++
++	if (tp_prev == tp) {
++		mpcb->connection_list = tp->mptcp->next;
++	} else {
++		for (; tp_prev && tp_prev->mptcp->next; tp_prev = tp_prev->mptcp->next) {
++			if (tp_prev->mptcp->next == tp) {
++				tp_prev->mptcp->next = tp->mptcp->next;
++				break;
++			}
++		}
++	}
++	mpcb->cnt_subflows--;
++	if (tp->mptcp->establish_increased)
++		mpcb->cnt_established--;
++
++	tp->mptcp->next = NULL;
++	tp->mptcp->attached = 0;
++	mpcb->path_index_bits &= ~(1 << tp->mptcp->path_index);
++
++	if (!skb_queue_empty(&sk->sk_write_queue))
++		mptcp_reinject_data(sk, 0);
++
++	if (is_master_tp(tp))
++		mpcb->master_sk = NULL;
++	else if (tp->mptcp->pre_established)
++		sk_stop_timer(sk, &tp->mptcp->mptcp_ack_timer);
++
++	rcu_assign_pointer(inet_sk(sk)->inet_opt, NULL);
++}
++
++/* Updates the metasocket ULID/port data, based on the given sock.
++ * The argument sock must be the sock accessible to the application.
++ * In this function, we update the meta socket info, based on the changes
++ * in the application socket (bind, address allocation, ...)
++ */
++void mptcp_update_metasocket(struct sock *sk, const struct sock *meta_sk)
++{
++	if (tcp_sk(sk)->mpcb->pm_ops->new_session)
++		tcp_sk(sk)->mpcb->pm_ops->new_session(meta_sk);
++
++	tcp_sk(sk)->mptcp->send_mp_prio = tcp_sk(sk)->mptcp->low_prio;
++}
++
++/* Clean up the receive buffer for full frames taken by the user,
++ * then send an ACK if necessary.  COPIED is the number of bytes
++ * tcp_recvmsg has given to the user so far, it speeds up the
++ * calculation of whether or not we must ACK for the sake of
++ * a window update.
++ */
++void mptcp_cleanup_rbuf(struct sock *meta_sk, int copied)
++{
++	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
++	struct sock *sk;
++	__u32 rcv_window_now = 0;
++
++	if (copied > 0 && !(meta_sk->sk_shutdown & RCV_SHUTDOWN)) {
++		rcv_window_now = tcp_receive_window(meta_tp);
++
++		if (2 * rcv_window_now > meta_tp->window_clamp)
++			rcv_window_now = 0;
++	}
++
++	mptcp_for_each_sk(meta_tp->mpcb, sk) {
++		struct tcp_sock *tp = tcp_sk(sk);
++		const struct inet_connection_sock *icsk = inet_csk(sk);
++
++		if (!mptcp_sk_can_send_ack(sk))
++			continue;
++
++		if (!inet_csk_ack_scheduled(sk))
++			goto second_part;
++		/* Delayed ACKs frequently hit locked sockets during bulk
++		 * receive.
++		 */
++		if (icsk->icsk_ack.blocked ||
++		    /* Once-per-two-segments ACK was not sent by tcp_input.c */
++		    tp->rcv_nxt - tp->rcv_wup > icsk->icsk_ack.rcv_mss ||
++		    /* If this read emptied read buffer, we send ACK, if
++		     * connection is not bidirectional, user drained
++		     * receive buffer and there was a small segment
++		     * in queue.
++		     */
++		    (copied > 0 &&
++		     ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED2) ||
++		      ((icsk->icsk_ack.pending & ICSK_ACK_PUSHED) &&
++		       !icsk->icsk_ack.pingpong)) &&
++		     !atomic_read(&meta_sk->sk_rmem_alloc))) {
++			tcp_send_ack(sk);
++			continue;
++		}
++
++second_part:
++		/* This here is the second part of tcp_cleanup_rbuf */
++		if (rcv_window_now) {
++			__u32 new_window = tp->ops->__select_window(sk);
++
++			/* Send ACK now, if this read freed lots of space
++			 * in our buffer. Certainly, new_window is new window.
++			 * We can advertise it now, if it is not less than
++			 * current one.
++			 * "Lots" means "at least twice" here.
++			 */
++			if (new_window && new_window >= 2 * rcv_window_now)
++				tcp_send_ack(sk);
++		}
++	}
++}
++
++static int mptcp_sub_send_fin(struct sock *sk)
++{
++	struct tcp_sock *tp = tcp_sk(sk);
++	struct sk_buff *skb = tcp_write_queue_tail(sk);
++	int mss_now;
++
++	/* Optimization, tack on the FIN if we have a queue of
++	 * unsent frames.  But be careful about outgoing SACKS
++	 * and IP options.
++	 */
++	mss_now = tcp_current_mss(sk);
++
++	if (tcp_send_head(sk) != NULL) {
++		TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_FIN;
++		TCP_SKB_CB(skb)->end_seq++;
++		tp->write_seq++;
++	} else {
++		skb = alloc_skb_fclone(MAX_TCP_HEADER, GFP_ATOMIC);
++		if (!skb)
++			return 1;
++
++		/* Reserve space for headers and prepare control bits. */
++		skb_reserve(skb, MAX_TCP_HEADER);
++		/* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */
++		tcp_init_nondata_skb(skb, tp->write_seq,
++				     TCPHDR_ACK | TCPHDR_FIN);
++		tcp_queue_skb(sk, skb);
++	}
++	__tcp_push_pending_frames(sk, mss_now, TCP_NAGLE_OFF);
++
++	return 0;
++}
++
++void mptcp_sub_close_wq(struct work_struct *work)
++{
++	struct tcp_sock *tp = container_of(work, struct mptcp_tcp_sock, work.work)->tp;
++	struct sock *sk = (struct sock *)tp;
++	struct sock *meta_sk = mptcp_meta_sk(sk);
++
++	mutex_lock(&tp->mpcb->mpcb_mutex);
++	lock_sock_nested(meta_sk, SINGLE_DEPTH_NESTING);
++
++	if (sock_flag(sk, SOCK_DEAD))
++		goto exit;
++
++	/* We come from tcp_disconnect. We are sure that meta_sk is set */
++	if (!mptcp(tp)) {
++		tp->closing = 1;
++		sock_rps_reset_flow(sk);
++		tcp_close(sk, 0);
++		goto exit;
++	}
++
++	if (meta_sk->sk_shutdown == SHUTDOWN_MASK || sk->sk_state == TCP_CLOSE) {
++		tp->closing = 1;
++		sock_rps_reset_flow(sk);
++		tcp_close(sk, 0);
++	} else if (tcp_close_state(sk)) {
++		sk->sk_shutdown |= SEND_SHUTDOWN;
++		tcp_send_fin(sk);
++	}
++
++exit:
++	release_sock(meta_sk);
++	mutex_unlock(&tp->mpcb->mpcb_mutex);
++	sock_put(sk);
++}
++
++void mptcp_sub_close(struct sock *sk, unsigned long delay)
++{
++	struct tcp_sock *tp = tcp_sk(sk);
++	struct delayed_work *work = &tcp_sk(sk)->mptcp->work;
++
++	/* We are already closing - e.g., call from sock_def_error_report upon
++	 * tcp_disconnect in tcp_close.
++	 */
++	if (tp->closing)
++		return;
++
++	/* Work already scheduled ? */
++	if (work_pending(&work->work)) {
++		/* Work present - who will be first ? */
++		if (jiffies + delay > work->timer.expires)
++			return;
++
++		/* Try canceling - if it fails, work will be executed soon */
++		if (!cancel_delayed_work(work))
++			return;
++		sock_put(sk);
++	}
++
++	if (!delay) {
++		unsigned char old_state = sk->sk_state;
++
++		/* If we are in user-context we can directly do the closing
++		 * procedure. No need to schedule a work-queue.
++		 */
++		if (!in_softirq()) {
++			if (sock_flag(sk, SOCK_DEAD))
++				return;
++
++			if (!mptcp(tp)) {
++				tp->closing = 1;
++				sock_rps_reset_flow(sk);
++				tcp_close(sk, 0);
++				return;
++			}
++
++			if (mptcp_meta_sk(sk)->sk_shutdown == SHUTDOWN_MASK ||
++			    sk->sk_state == TCP_CLOSE) {
++				tp->closing = 1;
++				sock_rps_reset_flow(sk);
++				tcp_close(sk, 0);
++			} else if (tcp_close_state(sk)) {
++				sk->sk_shutdown |= SEND_SHUTDOWN;
++				tcp_send_fin(sk);
++			}
++
++			return;
++		}
++
++		/* We directly send the FIN. Because it may take so a long time,
++		 * untile the work-queue will get scheduled...
++		 *
++		 * If mptcp_sub_send_fin returns 1, it failed and thus we reset
++		 * the old state so that tcp_close will finally send the fin
++		 * in user-context.
++		 */
++		if (!sk->sk_err && old_state != TCP_CLOSE &&
++		    tcp_close_state(sk) && mptcp_sub_send_fin(sk)) {
++			if (old_state == TCP_ESTABLISHED)
++				TCP_INC_STATS(sock_net(sk), TCP_MIB_CURRESTAB);
++			sk->sk_state = old_state;
++		}
++	}
++
++	sock_hold(sk);
++	queue_delayed_work(mptcp_wq, work, delay);
++}
++
++void mptcp_sub_force_close(struct sock *sk)
++{
++	/* The below tcp_done may have freed the socket, if he is already dead.
++	 * Thus, we are not allowed to access it afterwards. That's why
++	 * we have to store the dead-state in this local variable.
++	 */
++	int sock_is_dead = sock_flag(sk, SOCK_DEAD);
++
++	tcp_sk(sk)->mp_killed = 1;
++
++	if (sk->sk_state != TCP_CLOSE)
++		tcp_done(sk);
++
++	if (!sock_is_dead)
++		mptcp_sub_close(sk, 0);
++}
++EXPORT_SYMBOL(mptcp_sub_force_close);
++
++/* Update the mpcb send window, based on the contributions
++ * of each subflow
++ */
++void mptcp_update_sndbuf(const struct tcp_sock *tp)
++{
++	struct sock *meta_sk = tp->meta_sk, *sk;
++	int new_sndbuf = 0, old_sndbuf = meta_sk->sk_sndbuf;
++
++	mptcp_for_each_sk(tp->mpcb, sk) {
++		if (!mptcp_sk_can_send(sk))
++			continue;
++
++		new_sndbuf += sk->sk_sndbuf;
++
++		if (new_sndbuf > sysctl_tcp_wmem[2] || new_sndbuf < 0) {
++			new_sndbuf = sysctl_tcp_wmem[2];
++			break;
++		}
++	}
++	meta_sk->sk_sndbuf = max(min(new_sndbuf, sysctl_tcp_wmem[2]), meta_sk->sk_sndbuf);
++
++	/* The subflow's call to sk_write_space in tcp_new_space ends up in
++	 * mptcp_write_space.
++	 * It has nothing to do with waking up the application.
++	 * So, we do it here.
++	 */
++	if (old_sndbuf != meta_sk->sk_sndbuf)
++		meta_sk->sk_write_space(meta_sk);
++}
++
++void mptcp_close(struct sock *meta_sk, long timeout)
++{
++	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
++	struct sock *sk_it, *tmpsk;
++	struct mptcp_cb *mpcb = meta_tp->mpcb;
++	struct sk_buff *skb;
++	int data_was_unread = 0;
++	int state;
++
++	mptcp_debug("%s: Close of meta_sk with tok %#x\n",
++		    __func__, mpcb->mptcp_loc_token);
++
++	mutex_lock(&mpcb->mpcb_mutex);
++	lock_sock(meta_sk);
++
++	if (meta_tp->inside_tk_table) {
++		/* Detach the mpcb from the token hashtable */
++		mptcp_hash_remove_bh(meta_tp);
++		reqsk_queue_destroy(&inet_csk(meta_sk)->icsk_accept_queue);
++	}
++
++	meta_sk->sk_shutdown = SHUTDOWN_MASK;
++	/* We need to flush the recv. buffs.  We do this only on the
++	 * descriptor close, not protocol-sourced closes, because the
++	 * reader process may not have drained the data yet!
++	 */
++	while ((skb = __skb_dequeue(&meta_sk->sk_receive_queue)) != NULL) {
++		u32 len = TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq -
++			  tcp_hdr(skb)->fin;
++		data_was_unread += len;
++		__kfree_skb(skb);
++	}
++
++	sk_mem_reclaim(meta_sk);
++
++	/* If socket has been already reset (e.g. in tcp_reset()) - kill it. */
++	if (meta_sk->sk_state == TCP_CLOSE) {
++		mptcp_for_each_sk_safe(mpcb, sk_it, tmpsk) {
++			if (tcp_sk(sk_it)->send_mp_fclose)
++				continue;
++			mptcp_sub_close(sk_it, 0);
++		}
++		goto adjudge_to_death;
++	}
++
++	if (data_was_unread) {
++		/* Unread data was tossed, zap the connection. */
++		NET_INC_STATS_USER(sock_net(meta_sk), LINUX_MIB_TCPABORTONCLOSE);
++		tcp_set_state(meta_sk, TCP_CLOSE);
++		tcp_sk(meta_sk)->ops->send_active_reset(meta_sk,
++							meta_sk->sk_allocation);
++	} else if (sock_flag(meta_sk, SOCK_LINGER) && !meta_sk->sk_lingertime) {
++		/* Check zero linger _after_ checking for unread data. */
++		meta_sk->sk_prot->disconnect(meta_sk, 0);
++		NET_INC_STATS_USER(sock_net(meta_sk), LINUX_MIB_TCPABORTONDATA);
++	} else if (tcp_close_state(meta_sk)) {
++		mptcp_send_fin(meta_sk);
++	} else if (meta_tp->snd_una == meta_tp->write_seq) {
++		/* The DATA_FIN has been sent and acknowledged
++		 * (e.g., by sk_shutdown). Close all the other subflows
++		 */
++		mptcp_for_each_sk_safe(mpcb, sk_it, tmpsk) {
++			unsigned long delay = 0;
++			/* If we are the passive closer, don't trigger
++			 * subflow-fin until the subflow has been finned
++			 * by the peer. - thus we add a delay
++			 */
++			if (mpcb->passive_close &&
++			    sk_it->sk_state == TCP_ESTABLISHED)
++				delay = inet_csk(sk_it)->icsk_rto << 3;
++
++			mptcp_sub_close(sk_it, delay);
++		}
++	}
++
++	sk_stream_wait_close(meta_sk, timeout);
++
++adjudge_to_death:
++	state = meta_sk->sk_state;
++	sock_hold(meta_sk);
++	sock_orphan(meta_sk);
++
++	/* socket will be freed after mptcp_close - we have to prevent
++	 * access from the subflows.
++	 */
++	mptcp_for_each_sk(mpcb, sk_it) {
++		/* Similar to sock_orphan, but we don't set it DEAD, because
++		 * the callbacks are still set and must be called.
++		 */
++		write_lock_bh(&sk_it->sk_callback_lock);
++		sk_set_socket(sk_it, NULL);
++		sk_it->sk_wq  = NULL;
++		write_unlock_bh(&sk_it->sk_callback_lock);
++	}
++
++	/* It is the last release_sock in its life. It will remove backlog. */
++	release_sock(meta_sk);
++
++	/* Now socket is owned by kernel and we acquire BH lock
++	 * to finish close. No need to check for user refs.
++	 */
++	local_bh_disable();
++	bh_lock_sock(meta_sk);
++	WARN_ON(sock_owned_by_user(meta_sk));
++
++	percpu_counter_inc(meta_sk->sk_prot->orphan_count);
++
++	/* Have we already been destroyed by a softirq or backlog? */
++	if (state != TCP_CLOSE && meta_sk->sk_state == TCP_CLOSE)
++		goto out;
++
++	/*	This is a (useful) BSD violating of the RFC. There is a
++	 *	problem with TCP as specified in that the other end could
++	 *	keep a socket open forever with no application left this end.
++	 *	We use a 3 minute timeout (about the same as BSD) then kill
++	 *	our end. If they send after that then tough - BUT: long enough
++	 *	that we won't make the old 4*rto = almost no time - whoops
++	 *	reset mistake.
++	 *
++	 *	Nope, it was not mistake. It is really desired behaviour
++	 *	f.e. on http servers, when such sockets are useless, but
++	 *	consume significant resources. Let's do it with special
++	 *	linger2	option.					--ANK
++	 */
++
++	if (meta_sk->sk_state == TCP_FIN_WAIT2) {
++		if (meta_tp->linger2 < 0) {
++			tcp_set_state(meta_sk, TCP_CLOSE);
++			meta_tp->ops->send_active_reset(meta_sk, GFP_ATOMIC);
++			NET_INC_STATS_BH(sock_net(meta_sk),
++					 LINUX_MIB_TCPABORTONLINGER);
++		} else {
++			const int tmo = tcp_fin_time(meta_sk);
++
++			if (tmo > TCP_TIMEWAIT_LEN) {
++				inet_csk_reset_keepalive_timer(meta_sk,
++							       tmo - TCP_TIMEWAIT_LEN);
++			} else {
++				meta_tp->ops->time_wait(meta_sk, TCP_FIN_WAIT2,
++							tmo);
++				goto out;
++			}
++		}
++	}
++	if (meta_sk->sk_state != TCP_CLOSE) {
++		sk_mem_reclaim(meta_sk);
++		if (tcp_too_many_orphans(meta_sk, 0)) {
++			if (net_ratelimit())
++				pr_info("MPTCP: too many of orphaned sockets\n");
++			tcp_set_state(meta_sk, TCP_CLOSE);
++			meta_tp->ops->send_active_reset(meta_sk, GFP_ATOMIC);
++			NET_INC_STATS_BH(sock_net(meta_sk),
++					 LINUX_MIB_TCPABORTONMEMORY);
++		}
++	}
++
++
++	if (meta_sk->sk_state == TCP_CLOSE)
++		inet_csk_destroy_sock(meta_sk);
++	/* Otherwise, socket is reprieved until protocol close. */
++
++out:
++	bh_unlock_sock(meta_sk);
++	local_bh_enable();
++	mutex_unlock(&mpcb->mpcb_mutex);
++	sock_put(meta_sk); /* Taken by sock_hold */
++}
++
++void mptcp_disconnect(struct sock *sk)
++{
++	struct sock *subsk, *tmpsk;
++	struct tcp_sock *tp = tcp_sk(sk);
++
++	mptcp_delete_synack_timer(sk);
++
++	__skb_queue_purge(&tp->mpcb->reinject_queue);
++
++	if (tp->inside_tk_table) {
++		mptcp_hash_remove_bh(tp);
++		reqsk_queue_destroy(&inet_csk(tp->meta_sk)->icsk_accept_queue);
++	}
++
++	local_bh_disable();
++	mptcp_for_each_sk_safe(tp->mpcb, subsk, tmpsk) {
++		/* The socket will get removed from the subsocket-list
++		 * and made non-mptcp by setting mpc to 0.
++		 *
++		 * This is necessary, because tcp_disconnect assumes
++		 * that the connection is completly dead afterwards.
++		 * Thus we need to do a mptcp_del_sock. Due to this call
++		 * we have to make it non-mptcp.
++		 *
++		 * We have to lock the socket, because we set mpc to 0.
++		 * An incoming packet would take the subsocket's lock
++		 * and go on into the receive-path.
++		 * This would be a race.
++		 */
++
++		bh_lock_sock(subsk);
++		mptcp_del_sock(subsk);
++		tcp_sk(subsk)->mpc = 0;
++		tcp_sk(subsk)->ops = &tcp_specific;
++		mptcp_sub_force_close(subsk);
++		bh_unlock_sock(subsk);
++	}
++	local_bh_enable();
++
++	tp->was_meta_sk = 1;
++	tp->mpc = 0;
++	tp->ops = &tcp_specific;
++}
++
++
++/* Returns 1 if we should enable MPTCP for that socket. */
++int mptcp_doit(struct sock *sk)
++{
++	/* Do not allow MPTCP enabling if the MPTCP initialization failed */
++	if (mptcp_init_failed)
++		return 0;
++
++	if (sysctl_mptcp_enabled == MPTCP_APP && !tcp_sk(sk)->mptcp_enabled)
++		return 0;
++
++	/* Socket may already be established (e.g., called from tcp_recvmsg) */
++	if (mptcp(tcp_sk(sk)) || tcp_sk(sk)->request_mptcp)
++		return 1;
++
++	/* Don't do mptcp over loopback */
++	if (sk->sk_family == AF_INET &&
++	    (ipv4_is_loopback(inet_sk(sk)->inet_daddr) ||
++	     ipv4_is_loopback(inet_sk(sk)->inet_saddr)))
++		return 0;
++#if IS_ENABLED(CONFIG_IPV6)
++	if (sk->sk_family == AF_INET6 &&
++	    (ipv6_addr_loopback(&sk->sk_v6_daddr) ||
++	     ipv6_addr_loopback(&inet6_sk(sk)->saddr)))
++		return 0;
++#endif
++	if (mptcp_v6_is_v4_mapped(sk) &&
++	    ipv4_is_loopback(inet_sk(sk)->inet_saddr))
++		return 0;
++
++#ifdef CONFIG_TCP_MD5SIG
++	/* If TCP_MD5SIG is enabled, do not do MPTCP - there is no Option-Space */
++	if (tcp_sk(sk)->af_specific->md5_lookup(sk, sk))
++		return 0;
++#endif
++
++	return 1;
++}
++
++int mptcp_create_master_sk(struct sock *meta_sk, __u64 remote_key, u32 window)
++{
++	struct tcp_sock *master_tp;
++	struct sock *master_sk;
++
++	if (mptcp_alloc_mpcb(meta_sk, remote_key, window))
++		goto err_alloc_mpcb;
++
++	master_sk = tcp_sk(meta_sk)->mpcb->master_sk;
++	master_tp = tcp_sk(master_sk);
++
++	if (mptcp_add_sock(meta_sk, master_sk, 0, 0, GFP_ATOMIC))
++		goto err_add_sock;
++
++	if (__inet_inherit_port(meta_sk, master_sk) < 0)
++		goto err_add_sock;
++
++	meta_sk->sk_prot->unhash(meta_sk);
++
++	if (master_sk->sk_family == AF_INET || mptcp_v6_is_v4_mapped(master_sk))
++		__inet_hash_nolisten(master_sk, NULL);
++#if IS_ENABLED(CONFIG_IPV6)
++	else
++		__inet6_hash(master_sk, NULL);
++#endif
++
++	master_tp->mptcp->init_rcv_wnd = master_tp->rcv_wnd;
++
++	return 0;
++
++err_add_sock:
++	mptcp_fallback_meta_sk(meta_sk);
++
++	inet_csk_prepare_forced_close(master_sk);
++	tcp_done(master_sk);
++	inet_csk_prepare_forced_close(meta_sk);
++	tcp_done(meta_sk);
++
++err_alloc_mpcb:
++	return -ENOBUFS;
++}
++
++static int __mptcp_check_req_master(struct sock *child,
++				    struct request_sock *req)
++{
++	struct tcp_sock *child_tp = tcp_sk(child);
++	struct sock *meta_sk = child;
++	struct mptcp_cb *mpcb;
++	struct mptcp_request_sock *mtreq;
++
++	/* Never contained an MP_CAPABLE */
++	if (!inet_rsk(req)->mptcp_rqsk)
++		return 1;
++
++	if (!inet_rsk(req)->saw_mpc) {
++		/* Fallback to regular TCP, because we saw one SYN without
++		 * MP_CAPABLE. In tcp_check_req we continue the regular path.
++		 * But, the socket has been added to the reqsk_tk_htb, so we
++		 * must still remove it.
++		 */
++		mptcp_reqsk_remove_tk(req);
++		return 1;
++	}
++
++	/* Just set this values to pass them to mptcp_alloc_mpcb */
++	mtreq = mptcp_rsk(req);
++	child_tp->mptcp_loc_key = mtreq->mptcp_loc_key;
++	child_tp->mptcp_loc_token = mtreq->mptcp_loc_token;
++
++	if (mptcp_create_master_sk(meta_sk, mtreq->mptcp_rem_key,
++				   child_tp->snd_wnd))
++		return -ENOBUFS;
++
++	child = tcp_sk(child)->mpcb->master_sk;
++	child_tp = tcp_sk(child);
++	mpcb = child_tp->mpcb;
++
++	child_tp->mptcp->snt_isn = tcp_rsk(req)->snt_isn;
++	child_tp->mptcp->rcv_isn = tcp_rsk(req)->rcv_isn;
++
++	mpcb->dss_csum = mtreq->dss_csum;
++	mpcb->server_side = 1;
++
++	/* Will be moved to ESTABLISHED by  tcp_rcv_state_process() */
++	mptcp_update_metasocket(child, meta_sk);
++
++	/* Needs to be done here additionally, because when accepting a
++	 * new connection we pass by __reqsk_free and not reqsk_free.
++	 */
++	mptcp_reqsk_remove_tk(req);
++
++	/* Hold when creating the meta-sk in tcp_vX_syn_recv_sock. */
++	sock_put(meta_sk);
++
++	return 0;
++}
++
++int mptcp_check_req_fastopen(struct sock *child, struct request_sock *req)
++{
++	struct sock *meta_sk = child, *master_sk;
++	struct sk_buff *skb;
++	u32 new_mapping;
++	int ret;
++
++	ret = __mptcp_check_req_master(child, req);
++	if (ret)
++		return ret;
++
++	master_sk = tcp_sk(meta_sk)->mpcb->master_sk;
++
++	/* We need to rewind copied_seq as it is set to IDSN + 1 and as we have
++	 * pre-MPTCP data in the receive queue.
++	 */
++	tcp_sk(meta_sk)->copied_seq -= tcp_sk(master_sk)->rcv_nxt -
++				       tcp_rsk(req)->rcv_isn - 1;
++
++	/* Map subflow sequence number to data sequence numbers. We need to map
++	 * these data to [IDSN - len - 1, IDSN[.
++	 */
++	new_mapping = tcp_sk(meta_sk)->copied_seq - tcp_rsk(req)->rcv_isn - 1;
++
++	/* There should be only one skb: the SYN + data. */
++	skb_queue_walk(&meta_sk->sk_receive_queue, skb) {
++		TCP_SKB_CB(skb)->seq += new_mapping;
++		TCP_SKB_CB(skb)->end_seq += new_mapping;
++	}
++
++	/* With fastopen we change the semantics of the relative subflow
++	 * sequence numbers to deal with middleboxes that could add/remove
++	 * multiple bytes in the SYN. We chose to start counting at rcv_nxt - 1
++	 * instead of the regular TCP ISN.
++	 */
++	tcp_sk(master_sk)->mptcp->rcv_isn = tcp_sk(master_sk)->rcv_nxt - 1;
++
++	/* We need to update copied_seq of the master_sk to account for the
++	 * already moved data to the meta receive queue.
++	 */
++	tcp_sk(master_sk)->copied_seq = tcp_sk(master_sk)->rcv_nxt;
++
++	/* Handled by the master_sk */
++	tcp_sk(meta_sk)->fastopen_rsk = NULL;
++
++	return 0;
++}
++
++int mptcp_check_req_master(struct sock *sk, struct sock *child,
++			   struct request_sock *req,
++			   struct request_sock **prev)
++{
++	struct sock *meta_sk = child;
++	int ret;
++
++	ret = __mptcp_check_req_master(child, req);
++	if (ret)
++		return ret;
++
++	inet_csk_reqsk_queue_unlink(sk, req, prev);
++	inet_csk_reqsk_queue_removed(sk, req);
++	inet_csk_reqsk_queue_add(sk, req, meta_sk);
++
++	return 0;
++}
++
++struct sock *mptcp_check_req_child(struct sock *meta_sk, struct sock *child,
++				   struct request_sock *req,
++				   struct request_sock **prev,
++				   const struct mptcp_options_received *mopt)
++{
++	struct tcp_sock *child_tp = tcp_sk(child);
++	struct mptcp_request_sock *mtreq = mptcp_rsk(req);
++	struct mptcp_cb *mpcb = tcp_sk(meta_sk)->mpcb;
++	u8 hash_mac_check[20];
++
++	child_tp->inside_tk_table = 0;
++
++	if (!mopt->join_ack)
++		goto teardown;
++
++	mptcp_hmac_sha1((u8 *)&mpcb->mptcp_rem_key,
++			(u8 *)&mpcb->mptcp_loc_key,
++			(u8 *)&mtreq->mptcp_rem_nonce,
++			(u8 *)&mtreq->mptcp_loc_nonce,
++			(u32 *)hash_mac_check);
++
++	if (memcmp(hash_mac_check, (char *)&mopt->mptcp_recv_mac, 20))
++		goto teardown;
++
++	/* Point it to the same struct socket and wq as the meta_sk */
++	sk_set_socket(child, meta_sk->sk_socket);
++	child->sk_wq = meta_sk->sk_wq;
++
++	if (mptcp_add_sock(meta_sk, child, mtreq->loc_id, mtreq->rem_id, GFP_ATOMIC)) {
++		/* Has been inherited, but now child_tp->mptcp is NULL */
++		child_tp->mpc = 0;
++		child_tp->ops = &tcp_specific;
++
++		/* TODO when we support acking the third ack for new subflows,
++		 * we should silently discard this third ack, by returning NULL.
++		 *
++		 * Maybe, at the retransmission we will have enough memory to
++		 * fully add the socket to the meta-sk.
++		 */
++		goto teardown;
++	}
++
++	/* The child is a clone of the meta socket, we must now reset
++	 * some of the fields
++	 */
++	child_tp->mptcp->rcv_low_prio = mtreq->rcv_low_prio;
++
++	/* We should allow proper increase of the snd/rcv-buffers. Thus, we
++	 * use the original values instead of the bloated up ones from the
++	 * clone.
++	 */
++	child->sk_sndbuf = mpcb->orig_sk_sndbuf;
++	child->sk_rcvbuf = mpcb->orig_sk_rcvbuf;
++
++	child_tp->mptcp->slave_sk = 1;
++	child_tp->mptcp->snt_isn = tcp_rsk(req)->snt_isn;
++	child_tp->mptcp->rcv_isn = tcp_rsk(req)->rcv_isn;
++	child_tp->mptcp->init_rcv_wnd = req->rcv_wnd;
++
++	child_tp->tsq_flags = 0;
++
++	/* Subflows do not use the accept queue, as they
++	 * are attached immediately to the mpcb.
++	 */
++	inet_csk_reqsk_queue_unlink(meta_sk, req, prev);
++	reqsk_queue_removed(&inet_csk(meta_sk)->icsk_accept_queue, req);
++	reqsk_free(req);
++	return child;
++
++teardown:
++	/* Drop this request - sock creation failed. */
++	inet_csk_reqsk_queue_unlink(meta_sk, req, prev);
++	reqsk_queue_removed(&inet_csk(meta_sk)->icsk_accept_queue, req);
++	reqsk_free(req);
++	inet_csk_prepare_forced_close(child);
++	tcp_done(child);
++	return meta_sk;
++}
++
++int mptcp_init_tw_sock(struct sock *sk, struct tcp_timewait_sock *tw)
++{
++	struct mptcp_tw *mptw;
++	struct tcp_sock *tp = tcp_sk(sk);
++	struct mptcp_cb *mpcb = tp->mpcb;
++
++	/* A subsocket in tw can only receive data. So, if we are in
++	 * infinite-receive, then we should not reply with a data-ack or act
++	 * upon general MPTCP-signaling. We prevent this by simply not creating
++	 * the mptcp_tw_sock.
++	 */
++	if (mpcb->infinite_mapping_rcv) {
++		tw->mptcp_tw = NULL;
++		return 0;
++	}
++
++	/* Alloc MPTCP-tw-sock */
++	mptw = kmem_cache_alloc(mptcp_tw_cache, GFP_ATOMIC);
++	if (!mptw)
++		return -ENOBUFS;
++
++	atomic_inc(&mpcb->mpcb_refcnt);
++
++	tw->mptcp_tw = mptw;
++	mptw->loc_key = mpcb->mptcp_loc_key;
++	mptw->meta_tw = mpcb->in_time_wait;
++	if (mptw->meta_tw) {
++		mptw->rcv_nxt = mptcp_get_rcv_nxt_64(mptcp_meta_tp(tp));
++		if (mpcb->mptw_state != TCP_TIME_WAIT)
++			mptw->rcv_nxt++;
++	}
++	rcu_assign_pointer(mptw->mpcb, mpcb);
++
++	spin_lock(&mpcb->tw_lock);
++	list_add_rcu(&mptw->list, &tp->mpcb->tw_list);
++	mptw->in_list = 1;
++	spin_unlock(&mpcb->tw_lock);
++
++	return 0;
++}
++
++void mptcp_twsk_destructor(struct tcp_timewait_sock *tw)
++{
++	struct mptcp_cb *mpcb;
++
++	rcu_read_lock();
++	mpcb = rcu_dereference(tw->mptcp_tw->mpcb);
++
++	/* If we are still holding a ref to the mpcb, we have to remove ourself
++	 * from the list and drop the ref properly.
++	 */
++	if (mpcb && atomic_inc_not_zero(&mpcb->mpcb_refcnt)) {
++		spin_lock(&mpcb->tw_lock);
++		if (tw->mptcp_tw->in_list) {
++			list_del_rcu(&tw->mptcp_tw->list);
++			tw->mptcp_tw->in_list = 0;
++		}
++		spin_unlock(&mpcb->tw_lock);
++
++		/* Twice, because we increased it above */
++		mptcp_mpcb_put(mpcb);
++		mptcp_mpcb_put(mpcb);
++	}
++
++	rcu_read_unlock();
++
++	kmem_cache_free(mptcp_tw_cache, tw->mptcp_tw);
++}
++
++/* Updates the rcv_nxt of the time-wait-socks and allows them to ack a
++ * data-fin.
++ */
++void mptcp_time_wait(struct sock *sk, int state, int timeo)
++{
++	struct tcp_sock *tp = tcp_sk(sk);
++	struct mptcp_tw *mptw;
++
++	/* Used for sockets that go into tw after the meta
++	 * (see mptcp_init_tw_sock())
++	 */
++	tp->mpcb->in_time_wait = 1;
++	tp->mpcb->mptw_state = state;
++
++	/* Update the time-wait-sock's information */
++	rcu_read_lock_bh();
++	list_for_each_entry_rcu(mptw, &tp->mpcb->tw_list, list) {
++		mptw->meta_tw = 1;
++		mptw->rcv_nxt = mptcp_get_rcv_nxt_64(tp);
++
++		/* We want to ack a DATA_FIN, but are yet in FIN_WAIT_2 -
++		 * pretend as if the DATA_FIN has already reached us, that way
++		 * the checks in tcp_timewait_state_process will be good as the
++		 * DATA_FIN comes in.
++		 */
++		if (state != TCP_TIME_WAIT)
++			mptw->rcv_nxt++;
++	}
++	rcu_read_unlock_bh();
++
++	tcp_done(sk);
++}
++
++void mptcp_tsq_flags(struct sock *sk)
++{
++	struct tcp_sock *tp = tcp_sk(sk);
++	struct sock *meta_sk = mptcp_meta_sk(sk);
++
++	/* It will be handled as a regular deferred-call */
++	if (is_meta_sk(sk))
++		return;
++
++	if (hlist_unhashed(&tp->mptcp->cb_list)) {
++		hlist_add_head(&tp->mptcp->cb_list, &tp->mpcb->callback_list);
++		/* We need to hold it here, as the sock_hold is not assured
++		 * by the release_sock as it is done in regular TCP.
++		 *
++		 * The subsocket may get inet_csk_destroy'd while it is inside
++		 * the callback_list.
++		 */
++		sock_hold(sk);
++	}
++
++	if (!test_and_set_bit(MPTCP_SUB_DEFERRED, &tcp_sk(meta_sk)->tsq_flags))
++		sock_hold(meta_sk);
++}
++
++void mptcp_tsq_sub_deferred(struct sock *meta_sk)
++{
++	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
++	struct mptcp_tcp_sock *mptcp;
++	struct hlist_node *tmp;
++
++	BUG_ON(!is_meta_sk(meta_sk) && !meta_tp->was_meta_sk);
++
++	__sock_put(meta_sk);
++	hlist_for_each_entry_safe(mptcp, tmp, &meta_tp->mpcb->callback_list, cb_list) {
++		struct tcp_sock *tp = mptcp->tp;
++		struct sock *sk = (struct sock *)tp;
++
++		hlist_del_init(&mptcp->cb_list);
++		sk->sk_prot->release_cb(sk);
++		/* Final sock_put (cfr. mptcp_tsq_flags */
++		sock_put(sk);
++	}
++}
++
++void mptcp_join_reqsk_init(struct mptcp_cb *mpcb, const struct request_sock *req,
++			   struct sk_buff *skb)
++{
++	struct mptcp_request_sock *mtreq = mptcp_rsk(req);
++	struct mptcp_options_received mopt;
++	u8 mptcp_hash_mac[20];
++
++	mptcp_init_mp_opt(&mopt);
++	tcp_parse_mptcp_options(skb, &mopt);
++
++	mtreq = mptcp_rsk(req);
++	mtreq->mptcp_mpcb = mpcb;
++	mtreq->is_sub = 1;
++	inet_rsk(req)->mptcp_rqsk = 1;
++
++	mtreq->mptcp_rem_nonce = mopt.mptcp_recv_nonce;
++
++	mptcp_hmac_sha1((u8 *)&mpcb->mptcp_loc_key,
++			(u8 *)&mpcb->mptcp_rem_key,
++			(u8 *)&mtreq->mptcp_loc_nonce,
++			(u8 *)&mtreq->mptcp_rem_nonce, (u32 *)mptcp_hash_mac);
++	mtreq->mptcp_hash_tmac = *(u64 *)mptcp_hash_mac;
++
++	mtreq->rem_id = mopt.rem_id;
++	mtreq->rcv_low_prio = mopt.low_prio;
++	inet_rsk(req)->saw_mpc = 1;
++}
++
++void mptcp_reqsk_init(struct request_sock *req, const struct sk_buff *skb)
++{
++	struct mptcp_options_received mopt;
++	struct mptcp_request_sock *mreq = mptcp_rsk(req);
++
++	mptcp_init_mp_opt(&mopt);
++	tcp_parse_mptcp_options(skb, &mopt);
++
++	mreq->is_sub = 0;
++	inet_rsk(req)->mptcp_rqsk = 1;
++	mreq->dss_csum = mopt.dss_csum;
++	mreq->hash_entry.pprev = NULL;
++
++	mptcp_reqsk_new_mptcp(req, &mopt, skb);
++}
++
++int mptcp_conn_request(struct sock *sk, struct sk_buff *skb)
++{
++	struct mptcp_options_received mopt;
++	const struct tcp_sock *tp = tcp_sk(sk);
++	__u32 isn = TCP_SKB_CB(skb)->when;
++	bool want_cookie = false;
++
++	if ((sysctl_tcp_syncookies == 2 ||
++	     inet_csk_reqsk_queue_is_full(sk)) && !isn) {
++		want_cookie = tcp_syn_flood_action(sk, skb,
++						   mptcp_request_sock_ops.slab_name);
++		if (!want_cookie)
++			goto drop;
++	}
++
++	mptcp_init_mp_opt(&mopt);
++	tcp_parse_mptcp_options(skb, &mopt);
++
++	if (mopt.is_mp_join)
++		return mptcp_do_join_short(skb, &mopt, sock_net(sk));
++	if (mopt.drop_me)
++		goto drop;
++
++	if (sysctl_mptcp_enabled == MPTCP_APP && !tp->mptcp_enabled)
++		mopt.saw_mpc = 0;
++
++	if (skb->protocol == htons(ETH_P_IP)) {
++		if (mopt.saw_mpc && !want_cookie) {
++			if (skb_rtable(skb)->rt_flags &
++			    (RTCF_BROADCAST | RTCF_MULTICAST))
++				goto drop;
++
++			return tcp_conn_request(&mptcp_request_sock_ops,
++						&mptcp_request_sock_ipv4_ops,
++						sk, skb);
++		}
++
++		return tcp_v4_conn_request(sk, skb);
++#if IS_ENABLED(CONFIG_IPV6)
++	} else {
++		if (mopt.saw_mpc && !want_cookie) {
++			if (!ipv6_unicast_destination(skb))
++				goto drop;
++
++			return tcp_conn_request(&mptcp6_request_sock_ops,
++						&mptcp_request_sock_ipv6_ops,
++						sk, skb);
++		}
++
++		return tcp_v6_conn_request(sk, skb);
++#endif
++	}
++drop:
++	NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
++	return 0;
++}
++
++struct workqueue_struct *mptcp_wq;
++EXPORT_SYMBOL(mptcp_wq);
++
++/* Output /proc/net/mptcp */
++static int mptcp_pm_seq_show(struct seq_file *seq, void *v)
++{
++	struct tcp_sock *meta_tp;
++	const struct net *net = seq->private;
++	int i, n = 0;
++
++	seq_printf(seq, "  sl  loc_tok  rem_tok  v6 local_address                         remote_address                        st ns tx_queue rx_queue inode");
++	seq_putc(seq, '\n');
++
++	for (i = 0; i < MPTCP_HASH_SIZE; i++) {
++		struct hlist_nulls_node *node;
++		rcu_read_lock_bh();
++		hlist_nulls_for_each_entry_rcu(meta_tp, node,
++					       &tk_hashtable[i], tk_table) {
++			struct mptcp_cb *mpcb = meta_tp->mpcb;
++			struct sock *meta_sk = (struct sock *)meta_tp;
++			struct inet_sock *isk = inet_sk(meta_sk);
++
++			if (!mptcp(meta_tp) || !net_eq(net, sock_net(meta_sk)))
++				continue;
++
++			if (capable(CAP_NET_ADMIN)) {
++				seq_printf(seq, "%4d: %04X %04X ", n++,
++						mpcb->mptcp_loc_token,
++						mpcb->mptcp_rem_token);
++			} else {
++				seq_printf(seq, "%4d: %04X %04X ", n++, -1, -1);
++			}
++			if (meta_sk->sk_family == AF_INET ||
++			    mptcp_v6_is_v4_mapped(meta_sk)) {
++				seq_printf(seq, " 0 %08X:%04X                         %08X:%04X                        ",
++					   isk->inet_rcv_saddr,
++					   ntohs(isk->inet_sport),
++					   isk->inet_daddr,
++					   ntohs(isk->inet_dport));
++#if IS_ENABLED(CONFIG_IPV6)
++			} else if (meta_sk->sk_family == AF_INET6) {
++				struct in6_addr *src = &meta_sk->sk_v6_rcv_saddr;
++				struct in6_addr *dst = &meta_sk->sk_v6_daddr;
++				seq_printf(seq, " 1 %08X%08X%08X%08X:%04X %08X%08X%08X%08X:%04X",
++					   src->s6_addr32[0], src->s6_addr32[1],
++					   src->s6_addr32[2], src->s6_addr32[3],
++					   ntohs(isk->inet_sport),
++					   dst->s6_addr32[0], dst->s6_addr32[1],
++					   dst->s6_addr32[2], dst->s6_addr32[3],
++					   ntohs(isk->inet_dport));
++#endif
++			}
++			seq_printf(seq, " %02X %02X %08X:%08X %lu",
++				   meta_sk->sk_state, mpcb->cnt_subflows,
++				   meta_tp->write_seq - meta_tp->snd_una,
++				   max_t(int, meta_tp->rcv_nxt -
++					 meta_tp->copied_seq, 0),
++				   sock_i_ino(meta_sk));
++			seq_putc(seq, '\n');
++		}
++
++		rcu_read_unlock_bh();
++	}
++
++	return 0;
++}
++
++static int mptcp_pm_seq_open(struct inode *inode, struct file *file)
++{
++	return single_open_net(inode, file, mptcp_pm_seq_show);
++}
++
++static const struct file_operations mptcp_pm_seq_fops = {
++	.owner = THIS_MODULE,
++	.open = mptcp_pm_seq_open,
++	.read = seq_read,
++	.llseek = seq_lseek,
++	.release = single_release_net,
++};
++
++static int mptcp_pm_init_net(struct net *net)
++{
++	if (!proc_create("mptcp", S_IRUGO, net->proc_net, &mptcp_pm_seq_fops))
++		return -ENOMEM;
++
++	return 0;
++}
++
++static void mptcp_pm_exit_net(struct net *net)
++{
++	remove_proc_entry("mptcp", net->proc_net);
++}
++
++static struct pernet_operations mptcp_pm_proc_ops = {
++	.init = mptcp_pm_init_net,
++	.exit = mptcp_pm_exit_net,
++};
++
++/* General initialization of mptcp */
++void __init mptcp_init(void)
++{
++	int i;
++	struct ctl_table_header *mptcp_sysctl;
++
++	mptcp_sock_cache = kmem_cache_create("mptcp_sock",
++					     sizeof(struct mptcp_tcp_sock),
++					     0, SLAB_HWCACHE_ALIGN,
++					     NULL);
++	if (!mptcp_sock_cache)
++		goto mptcp_sock_cache_failed;
++
++	mptcp_cb_cache = kmem_cache_create("mptcp_cb", sizeof(struct mptcp_cb),
++					   0, SLAB_DESTROY_BY_RCU|SLAB_HWCACHE_ALIGN,
++					   NULL);
++	if (!mptcp_cb_cache)
++		goto mptcp_cb_cache_failed;
++
++	mptcp_tw_cache = kmem_cache_create("mptcp_tw", sizeof(struct mptcp_tw),
++					   0, SLAB_DESTROY_BY_RCU|SLAB_HWCACHE_ALIGN,
++					   NULL);
++	if (!mptcp_tw_cache)
++		goto mptcp_tw_cache_failed;
++
++	get_random_bytes(mptcp_secret, sizeof(mptcp_secret));
++
++	mptcp_wq = alloc_workqueue("mptcp_wq", WQ_UNBOUND | WQ_MEM_RECLAIM, 8);
++	if (!mptcp_wq)
++		goto alloc_workqueue_failed;
++
++	for (i = 0; i < MPTCP_HASH_SIZE; i++) {
++		INIT_HLIST_NULLS_HEAD(&tk_hashtable[i], i);
++		INIT_HLIST_NULLS_HEAD(&mptcp_reqsk_htb[i],
++				      i + MPTCP_REQSK_NULLS_BASE);
++		INIT_HLIST_NULLS_HEAD(&mptcp_reqsk_tk_htb[i], i);
++	}
++
++	spin_lock_init(&mptcp_reqsk_hlock);
++	spin_lock_init(&mptcp_tk_hashlock);
++
++	if (register_pernet_subsys(&mptcp_pm_proc_ops))
++		goto pernet_failed;
++
++#if IS_ENABLED(CONFIG_IPV6)
++	if (mptcp_pm_v6_init())
++		goto mptcp_pm_v6_failed;
++#endif
++	if (mptcp_pm_v4_init())
++		goto mptcp_pm_v4_failed;
++
++	mptcp_sysctl = register_net_sysctl(&init_net, "net/mptcp", mptcp_table);
++	if (!mptcp_sysctl)
++		goto register_sysctl_failed;
++
++	if (mptcp_register_path_manager(&mptcp_pm_default))
++		goto register_pm_failed;
++
++	if (mptcp_register_scheduler(&mptcp_sched_default))
++		goto register_sched_failed;
++
++	pr_info("MPTCP: Stable release v0.89.0-rc");
++
++	mptcp_init_failed = false;
++
++	return;
++
++register_sched_failed:
++	mptcp_unregister_path_manager(&mptcp_pm_default);
++register_pm_failed:
++	unregister_net_sysctl_table(mptcp_sysctl);
++register_sysctl_failed:
++	mptcp_pm_v4_undo();
++mptcp_pm_v4_failed:
++#if IS_ENABLED(CONFIG_IPV6)
++	mptcp_pm_v6_undo();
++mptcp_pm_v6_failed:
++#endif
++	unregister_pernet_subsys(&mptcp_pm_proc_ops);
++pernet_failed:
++	destroy_workqueue(mptcp_wq);
++alloc_workqueue_failed:
++	kmem_cache_destroy(mptcp_tw_cache);
++mptcp_tw_cache_failed:
++	kmem_cache_destroy(mptcp_cb_cache);
++mptcp_cb_cache_failed:
++	kmem_cache_destroy(mptcp_sock_cache);
++mptcp_sock_cache_failed:
++	mptcp_init_failed = true;
++}
+diff --git a/net/mptcp/mptcp_fullmesh.c b/net/mptcp/mptcp_fullmesh.c
+new file mode 100644
+index 000000000000..3a54413ce25b
+--- /dev/null
++++ b/net/mptcp/mptcp_fullmesh.c
+@@ -0,0 +1,1722 @@
++#include <linux/module.h>
++
++#include <net/mptcp.h>
++#include <net/mptcp_v4.h>
++
++#if IS_ENABLED(CONFIG_IPV6)
++#include <net/mptcp_v6.h>
++#include <net/addrconf.h>
++#endif
++
++enum {
++	MPTCP_EVENT_ADD = 1,
++	MPTCP_EVENT_DEL,
++	MPTCP_EVENT_MOD,
++};
++
++#define MPTCP_SUBFLOW_RETRY_DELAY	1000
++
++/* Max number of local or remote addresses we can store.
++ * When changing, see the bitfield below in fullmesh_rem4/6.
++ */
++#define MPTCP_MAX_ADDR	8
++
++struct fullmesh_rem4 {
++	u8		rem4_id;
++	u8		bitfield;
++	u8		retry_bitfield;
++	__be16		port;
++	struct in_addr	addr;
++};
++
++struct fullmesh_rem6 {
++	u8		rem6_id;
++	u8		bitfield;
++	u8		retry_bitfield;
++	__be16		port;
++	struct in6_addr	addr;
++};
++
++struct mptcp_loc_addr {
++	struct mptcp_loc4 locaddr4[MPTCP_MAX_ADDR];
++	u8 loc4_bits;
++	u8 next_v4_index;
++
++	struct mptcp_loc6 locaddr6[MPTCP_MAX_ADDR];
++	u8 loc6_bits;
++	u8 next_v6_index;
++};
++
++struct mptcp_addr_event {
++	struct list_head list;
++	unsigned short	family;
++	u8	code:7,
++		low_prio:1;
++	union inet_addr addr;
++};
++
++struct fullmesh_priv {
++	/* Worker struct for subflow establishment */
++	struct work_struct subflow_work;
++	/* Delayed worker, when the routing-tables are not yet ready. */
++	struct delayed_work subflow_retry_work;
++
++	/* Remote addresses */
++	struct fullmesh_rem4 remaddr4[MPTCP_MAX_ADDR];
++	struct fullmesh_rem6 remaddr6[MPTCP_MAX_ADDR];
++
++	struct mptcp_cb *mpcb;
++
++	u16 remove_addrs; /* Addresses to remove */
++	u8 announced_addrs_v4; /* IPv4 Addresses we did announce */
++	u8 announced_addrs_v6; /* IPv6 Addresses we did announce */
++
++	u8	add_addr; /* Are we sending an add_addr? */
++
++	u8 rem4_bits;
++	u8 rem6_bits;
++};
++
++struct mptcp_fm_ns {
++	struct mptcp_loc_addr __rcu *local;
++	spinlock_t local_lock; /* Protecting the above pointer */
++	struct list_head events;
++	struct delayed_work address_worker;
++
++	struct net *net;
++};
++
++static struct mptcp_pm_ops full_mesh __read_mostly;
++
++static void full_mesh_create_subflows(struct sock *meta_sk);
++
++static struct mptcp_fm_ns *fm_get_ns(const struct net *net)
++{
++	return (struct mptcp_fm_ns *)net->mptcp.path_managers[MPTCP_PM_FULLMESH];
++}
++
++static struct fullmesh_priv *fullmesh_get_priv(const struct mptcp_cb *mpcb)
++{
++	return (struct fullmesh_priv *)&mpcb->mptcp_pm[0];
++}
++
++/* Find the first free index in the bitfield */
++static int __mptcp_find_free_index(u8 bitfield, u8 base)
++{
++	int i;
++
++	/* There are anyways no free bits... */
++	if (bitfield == 0xff)
++		goto exit;
++
++	i = ffs(~(bitfield >> base)) - 1;
++	if (i < 0)
++		goto exit;
++
++	/* No free bits when starting at base, try from 0 on */
++	if (i + base >= sizeof(bitfield) * 8)
++		return __mptcp_find_free_index(bitfield, 0);
++
++	return i + base;
++exit:
++	return -1;
++}
++
++static int mptcp_find_free_index(u8 bitfield)
++{
++	return __mptcp_find_free_index(bitfield, 0);
++}
++
++static void mptcp_addv4_raddr(struct mptcp_cb *mpcb,
++			      const struct in_addr *addr,
++			      __be16 port, u8 id)
++{
++	int i;
++	struct fullmesh_rem4 *rem4;
++	struct fullmesh_priv *fmp = fullmesh_get_priv(mpcb);
++
++	mptcp_for_each_bit_set(fmp->rem4_bits, i) {
++		rem4 = &fmp->remaddr4[i];
++
++		/* Address is already in the list --- continue */
++		if (rem4->rem4_id == id &&
++		    rem4->addr.s_addr == addr->s_addr && rem4->port == port)
++			return;
++
++		/* This may be the case, when the peer is behind a NAT. He is
++		 * trying to JOIN, thus sending the JOIN with a certain ID.
++		 * However the src_addr of the IP-packet has been changed. We
++		 * update the addr in the list, because this is the address as
++		 * OUR BOX sees it.
++		 */
++		if (rem4->rem4_id == id && rem4->addr.s_addr != addr->s_addr) {
++			/* update the address */
++			mptcp_debug("%s: updating old addr:%pI4 to addr %pI4 with id:%d\n",
++				    __func__, &rem4->addr.s_addr,
++				    &addr->s_addr, id);
++			rem4->addr.s_addr = addr->s_addr;
++			rem4->port = port;
++			mpcb->list_rcvd = 1;
++			return;
++		}
++	}
++
++	i = mptcp_find_free_index(fmp->rem4_bits);
++	/* Do we have already the maximum number of local/remote addresses? */
++	if (i < 0) {
++		mptcp_debug("%s: At max num of remote addresses: %d --- not adding address: %pI4\n",
++			    __func__, MPTCP_MAX_ADDR, &addr->s_addr);
++		return;
++	}
++
++	rem4 = &fmp->remaddr4[i];
++
++	/* Address is not known yet, store it */
++	rem4->addr.s_addr = addr->s_addr;
++	rem4->port = port;
++	rem4->bitfield = 0;
++	rem4->retry_bitfield = 0;
++	rem4->rem4_id = id;
++	mpcb->list_rcvd = 1;
++	fmp->rem4_bits |= (1 << i);
++
++	return;
++}
++
++static void mptcp_addv6_raddr(struct mptcp_cb *mpcb,
++			      const struct in6_addr *addr,
++			      __be16 port, u8 id)
++{
++	int i;
++	struct fullmesh_rem6 *rem6;
++	struct fullmesh_priv *fmp = fullmesh_get_priv(mpcb);
++
++	mptcp_for_each_bit_set(fmp->rem6_bits, i) {
++		rem6 = &fmp->remaddr6[i];
++
++		/* Address is already in the list --- continue */
++		if (rem6->rem6_id == id &&
++		    ipv6_addr_equal(&rem6->addr, addr) && rem6->port == port)
++			return;
++
++		/* This may be the case, when the peer is behind a NAT. He is
++		 * trying to JOIN, thus sending the JOIN with a certain ID.
++		 * However the src_addr of the IP-packet has been changed. We
++		 * update the addr in the list, because this is the address as
++		 * OUR BOX sees it.
++		 */
++		if (rem6->rem6_id == id) {
++			/* update the address */
++			mptcp_debug("%s: updating old addr: %pI6 to addr %pI6 with id:%d\n",
++				    __func__, &rem6->addr, addr, id);
++			rem6->addr = *addr;
++			rem6->port = port;
++			mpcb->list_rcvd = 1;
++			return;
++		}
++	}
++
++	i = mptcp_find_free_index(fmp->rem6_bits);
++	/* Do we have already the maximum number of local/remote addresses? */
++	if (i < 0) {
++		mptcp_debug("%s: At max num of remote addresses: %d --- not adding address: %pI6\n",
++			    __func__, MPTCP_MAX_ADDR, addr);
++		return;
++	}
++
++	rem6 = &fmp->remaddr6[i];
++
++	/* Address is not known yet, store it */
++	rem6->addr = *addr;
++	rem6->port = port;
++	rem6->bitfield = 0;
++	rem6->retry_bitfield = 0;
++	rem6->rem6_id = id;
++	mpcb->list_rcvd = 1;
++	fmp->rem6_bits |= (1 << i);
++
++	return;
++}
++
++static void mptcp_v4_rem_raddress(struct mptcp_cb *mpcb, u8 id)
++{
++	int i;
++	struct fullmesh_priv *fmp = fullmesh_get_priv(mpcb);
++
++	mptcp_for_each_bit_set(fmp->rem4_bits, i) {
++		if (fmp->remaddr4[i].rem4_id == id) {
++			/* remove address from bitfield */
++			fmp->rem4_bits &= ~(1 << i);
++
++			break;
++		}
++	}
++}
++
++static void mptcp_v6_rem_raddress(const struct mptcp_cb *mpcb, u8 id)
++{
++	int i;
++	struct fullmesh_priv *fmp = fullmesh_get_priv(mpcb);
++
++	mptcp_for_each_bit_set(fmp->rem6_bits, i) {
++		if (fmp->remaddr6[i].rem6_id == id) {
++			/* remove address from bitfield */
++			fmp->rem6_bits &= ~(1 << i);
++
++			break;
++		}
++	}
++}
++
++/* Sets the bitfield of the remote-address field */
++static void mptcp_v4_set_init_addr_bit(const struct mptcp_cb *mpcb,
++				       const struct in_addr *addr, u8 index)
++{
++	int i;
++	struct fullmesh_priv *fmp = fullmesh_get_priv(mpcb);
++
++	mptcp_for_each_bit_set(fmp->rem4_bits, i) {
++		if (fmp->remaddr4[i].addr.s_addr == addr->s_addr) {
++			fmp->remaddr4[i].bitfield |= (1 << index);
++			return;
++		}
++	}
++}
++
++/* Sets the bitfield of the remote-address field */
++static void mptcp_v6_set_init_addr_bit(struct mptcp_cb *mpcb,
++				       const struct in6_addr *addr, u8 index)
++{
++	int i;
++	struct fullmesh_priv *fmp = fullmesh_get_priv(mpcb);
++
++	mptcp_for_each_bit_set(fmp->rem6_bits, i) {
++		if (ipv6_addr_equal(&fmp->remaddr6[i].addr, addr)) {
++			fmp->remaddr6[i].bitfield |= (1 << index);
++			return;
++		}
++	}
++}
++
++static void mptcp_set_init_addr_bit(struct mptcp_cb *mpcb,
++				    const union inet_addr *addr,
++				    sa_family_t family, u8 id)
++{
++	if (family == AF_INET)
++		mptcp_v4_set_init_addr_bit(mpcb, &addr->in, id);
++	else
++		mptcp_v6_set_init_addr_bit(mpcb, &addr->in6, id);
++}
++
++static void retry_subflow_worker(struct work_struct *work)
++{
++	struct delayed_work *delayed_work = container_of(work,
++							 struct delayed_work,
++							 work);
++	struct fullmesh_priv *fmp = container_of(delayed_work,
++						 struct fullmesh_priv,
++						 subflow_retry_work);
++	struct mptcp_cb *mpcb = fmp->mpcb;
++	struct sock *meta_sk = mpcb->meta_sk;
++	struct mptcp_loc_addr *mptcp_local;
++	struct mptcp_fm_ns *fm_ns = fm_get_ns(sock_net(meta_sk));
++	int iter = 0, i;
++
++	/* We need a local (stable) copy of the address-list. Really, it is not
++	 * such a big deal, if the address-list is not 100% up-to-date.
++	 */
++	rcu_read_lock_bh();
++	mptcp_local = rcu_dereference_bh(fm_ns->local);
++	mptcp_local = kmemdup(mptcp_local, sizeof(*mptcp_local), GFP_ATOMIC);
++	rcu_read_unlock_bh();
++
++	if (!mptcp_local)
++		return;
++
++next_subflow:
++	if (iter) {
++		release_sock(meta_sk);
++		mutex_unlock(&mpcb->mpcb_mutex);
++
++		cond_resched();
++	}
++	mutex_lock(&mpcb->mpcb_mutex);
++	lock_sock_nested(meta_sk, SINGLE_DEPTH_NESTING);
++
++	iter++;
++
++	if (sock_flag(meta_sk, SOCK_DEAD))
++		goto exit;
++
++	mptcp_for_each_bit_set(fmp->rem4_bits, i) {
++		struct fullmesh_rem4 *rem = &fmp->remaddr4[i];
++		/* Do we need to retry establishing a subflow ? */
++		if (rem->retry_bitfield) {
++			int i = mptcp_find_free_index(~rem->retry_bitfield);
++			struct mptcp_rem4 rem4;
++
++			rem->bitfield |= (1 << i);
++			rem->retry_bitfield &= ~(1 << i);
++
++			rem4.addr = rem->addr;
++			rem4.port = rem->port;
++			rem4.rem4_id = rem->rem4_id;
++
++			mptcp_init4_subsockets(meta_sk, &mptcp_local->locaddr4[i], &rem4);
++			goto next_subflow;
++		}
++	}
++
++#if IS_ENABLED(CONFIG_IPV6)
++	mptcp_for_each_bit_set(fmp->rem6_bits, i) {
++		struct fullmesh_rem6 *rem = &fmp->remaddr6[i];
++
++		/* Do we need to retry establishing a subflow ? */
++		if (rem->retry_bitfield) {
++			int i = mptcp_find_free_index(~rem->retry_bitfield);
++			struct mptcp_rem6 rem6;
++
++			rem->bitfield |= (1 << i);
++			rem->retry_bitfield &= ~(1 << i);
++
++			rem6.addr = rem->addr;
++			rem6.port = rem->port;
++			rem6.rem6_id = rem->rem6_id;
++
++			mptcp_init6_subsockets(meta_sk, &mptcp_local->locaddr6[i], &rem6);
++			goto next_subflow;
++		}
++	}
++#endif
++
++exit:
++	kfree(mptcp_local);
++	release_sock(meta_sk);
++	mutex_unlock(&mpcb->mpcb_mutex);
++	sock_put(meta_sk);
++}
++
++/**
++ * Create all new subflows, by doing calls to mptcp_initX_subsockets
++ *
++ * This function uses a goto next_subflow, to allow releasing the lock between
++ * new subflows and giving other processes a chance to do some work on the
++ * socket and potentially finishing the communication.
++ **/
++static void create_subflow_worker(struct work_struct *work)
++{
++	struct fullmesh_priv *fmp = container_of(work, struct fullmesh_priv,
++						 subflow_work);
++	struct mptcp_cb *mpcb = fmp->mpcb;
++	struct sock *meta_sk = mpcb->meta_sk;
++	struct mptcp_loc_addr *mptcp_local;
++	const struct mptcp_fm_ns *fm_ns = fm_get_ns(sock_net(meta_sk));
++	int iter = 0, retry = 0;
++	int i;
++
++	/* We need a local (stable) copy of the address-list. Really, it is not
++	 * such a big deal, if the address-list is not 100% up-to-date.
++	 */
++	rcu_read_lock_bh();
++	mptcp_local = rcu_dereference_bh(fm_ns->local);
++	mptcp_local = kmemdup(mptcp_local, sizeof(*mptcp_local), GFP_ATOMIC);
++	rcu_read_unlock_bh();
++
++	if (!mptcp_local)
++		return;
++
++next_subflow:
++	if (iter) {
++		release_sock(meta_sk);
++		mutex_unlock(&mpcb->mpcb_mutex);
++
++		cond_resched();
++	}
++	mutex_lock(&mpcb->mpcb_mutex);
++	lock_sock_nested(meta_sk, SINGLE_DEPTH_NESTING);
++
++	iter++;
++
++	if (sock_flag(meta_sk, SOCK_DEAD))
++		goto exit;
++
++	if (mpcb->master_sk &&
++	    !tcp_sk(mpcb->master_sk)->mptcp->fully_established)
++		goto exit;
++
++	mptcp_for_each_bit_set(fmp->rem4_bits, i) {
++		struct fullmesh_rem4 *rem;
++		u8 remaining_bits;
++
++		rem = &fmp->remaddr4[i];
++		remaining_bits = ~(rem->bitfield) & mptcp_local->loc4_bits;
++
++		/* Are there still combinations to handle? */
++		if (remaining_bits) {
++			int i = mptcp_find_free_index(~remaining_bits);
++			struct mptcp_rem4 rem4;
++
++			rem->bitfield |= (1 << i);
++
++			rem4.addr = rem->addr;
++			rem4.port = rem->port;
++			rem4.rem4_id = rem->rem4_id;
++
++			/* If a route is not yet available then retry once */
++			if (mptcp_init4_subsockets(meta_sk, &mptcp_local->locaddr4[i],
++						   &rem4) == -ENETUNREACH)
++				retry = rem->retry_bitfield |= (1 << i);
++			goto next_subflow;
++		}
++	}
++
++#if IS_ENABLED(CONFIG_IPV6)
++	mptcp_for_each_bit_set(fmp->rem6_bits, i) {
++		struct fullmesh_rem6 *rem;
++		u8 remaining_bits;
++
++		rem = &fmp->remaddr6[i];
++		remaining_bits = ~(rem->bitfield) & mptcp_local->loc6_bits;
++
++		/* Are there still combinations to handle? */
++		if (remaining_bits) {
++			int i = mptcp_find_free_index(~remaining_bits);
++			struct mptcp_rem6 rem6;
++
++			rem->bitfield |= (1 << i);
++
++			rem6.addr = rem->addr;
++			rem6.port = rem->port;
++			rem6.rem6_id = rem->rem6_id;
++
++			/* If a route is not yet available then retry once */
++			if (mptcp_init6_subsockets(meta_sk, &mptcp_local->locaddr6[i],
++						   &rem6) == -ENETUNREACH)
++				retry = rem->retry_bitfield |= (1 << i);
++			goto next_subflow;
++		}
++	}
++#endif
++
++	if (retry && !delayed_work_pending(&fmp->subflow_retry_work)) {
++		sock_hold(meta_sk);
++		queue_delayed_work(mptcp_wq, &fmp->subflow_retry_work,
++				   msecs_to_jiffies(MPTCP_SUBFLOW_RETRY_DELAY));
++	}
++
++exit:
++	kfree(mptcp_local);
++	release_sock(meta_sk);
++	mutex_unlock(&mpcb->mpcb_mutex);
++	sock_put(meta_sk);
++}
++
++static void announce_remove_addr(u8 addr_id, struct sock *meta_sk)
++{
++	struct mptcp_cb *mpcb = tcp_sk(meta_sk)->mpcb;
++	struct fullmesh_priv *fmp = fullmesh_get_priv(mpcb);
++	struct sock *sk = mptcp_select_ack_sock(meta_sk);
++
++	fmp->remove_addrs |= (1 << addr_id);
++	mpcb->addr_signal = 1;
++
++	if (sk)
++		tcp_send_ack(sk);
++}
++
++static void update_addr_bitfields(struct sock *meta_sk,
++				  const struct mptcp_loc_addr *mptcp_local)
++{
++	struct mptcp_cb *mpcb = tcp_sk(meta_sk)->mpcb;
++	struct fullmesh_priv *fmp = fullmesh_get_priv(mpcb);
++	int i;
++
++	/* The bits in announced_addrs_* always match with loc*_bits. So, a
++	 * simply & operation unsets the correct bits, because these go from
++	 * announced to non-announced
++	 */
++	fmp->announced_addrs_v4 &= mptcp_local->loc4_bits;
++
++	mptcp_for_each_bit_set(fmp->rem4_bits, i) {
++		fmp->remaddr4[i].bitfield &= mptcp_local->loc4_bits;
++		fmp->remaddr4[i].retry_bitfield &= mptcp_local->loc4_bits;
++	}
++
++	fmp->announced_addrs_v6 &= mptcp_local->loc6_bits;
++
++	mptcp_for_each_bit_set(fmp->rem6_bits, i) {
++		fmp->remaddr6[i].bitfield &= mptcp_local->loc6_bits;
++		fmp->remaddr6[i].retry_bitfield &= mptcp_local->loc6_bits;
++	}
++}
++
++static int mptcp_find_address(const struct mptcp_loc_addr *mptcp_local,
++			      sa_family_t family, const union inet_addr *addr)
++{
++	int i;
++	u8 loc_bits;
++	bool found = false;
++
++	if (family == AF_INET)
++		loc_bits = mptcp_local->loc4_bits;
++	else
++		loc_bits = mptcp_local->loc6_bits;
++
++	mptcp_for_each_bit_set(loc_bits, i) {
++		if (family == AF_INET &&
++		    mptcp_local->locaddr4[i].addr.s_addr == addr->in.s_addr) {
++			found = true;
++			break;
++		}
++		if (family == AF_INET6 &&
++		    ipv6_addr_equal(&mptcp_local->locaddr6[i].addr,
++				    &addr->in6)) {
++			found = true;
++			break;
++		}
++	}
++
++	if (!found)
++		return -1;
++
++	return i;
++}
++
++static void mptcp_address_worker(struct work_struct *work)
++{
++	const struct delayed_work *delayed_work = container_of(work,
++							 struct delayed_work,
++							 work);
++	struct mptcp_fm_ns *fm_ns = container_of(delayed_work,
++						 struct mptcp_fm_ns,
++						 address_worker);
++	struct net *net = fm_ns->net;
++	struct mptcp_addr_event *event = NULL;
++	struct mptcp_loc_addr *mptcp_local, *old;
++	int i, id = -1; /* id is used in the socket-code on a delete-event */
++	bool success; /* Used to indicate if we succeeded handling the event */
++
++next_event:
++	success = false;
++	kfree(event);
++
++	/* First, let's dequeue an event from our event-list */
++	rcu_read_lock_bh();
++	spin_lock(&fm_ns->local_lock);
++
++	event = list_first_entry_or_null(&fm_ns->events,
++					 struct mptcp_addr_event, list);
++	if (!event) {
++		spin_unlock(&fm_ns->local_lock);
++		rcu_read_unlock_bh();
++		return;
++	}
++
++	list_del(&event->list);
++
++	mptcp_local = rcu_dereference_bh(fm_ns->local);
++
++	if (event->code == MPTCP_EVENT_DEL) {
++		id = mptcp_find_address(mptcp_local, event->family, &event->addr);
++
++		/* Not in the list - so we don't care */
++		if (id < 0) {
++			mptcp_debug("%s could not find id\n", __func__);
++			goto duno;
++		}
++
++		old = mptcp_local;
++		mptcp_local = kmemdup(mptcp_local, sizeof(*mptcp_local),
++				      GFP_ATOMIC);
++		if (!mptcp_local)
++			goto duno;
++
++		if (event->family == AF_INET)
++			mptcp_local->loc4_bits &= ~(1 << id);
++		else
++			mptcp_local->loc6_bits &= ~(1 << id);
++
++		rcu_assign_pointer(fm_ns->local, mptcp_local);
++		kfree(old);
++	} else {
++		int i = mptcp_find_address(mptcp_local, event->family, &event->addr);
++		int j = i;
++
++		if (j < 0) {
++			/* Not in the list, so we have to find an empty slot */
++			if (event->family == AF_INET)
++				i = __mptcp_find_free_index(mptcp_local->loc4_bits,
++							    mptcp_local->next_v4_index);
++			if (event->family == AF_INET6)
++				i = __mptcp_find_free_index(mptcp_local->loc6_bits,
++							    mptcp_local->next_v6_index);
++
++			if (i < 0) {
++				mptcp_debug("%s no more space\n", __func__);
++				goto duno;
++			}
++
++			/* It might have been a MOD-event. */
++			event->code = MPTCP_EVENT_ADD;
++		} else {
++			/* Let's check if anything changes */
++			if (event->family == AF_INET &&
++			    event->low_prio == mptcp_local->locaddr4[i].low_prio)
++				goto duno;
++
++			if (event->family == AF_INET6 &&
++			    event->low_prio == mptcp_local->locaddr6[i].low_prio)
++				goto duno;
++		}
++
++		old = mptcp_local;
++		mptcp_local = kmemdup(mptcp_local, sizeof(*mptcp_local),
++				      GFP_ATOMIC);
++		if (!mptcp_local)
++			goto duno;
++
++		if (event->family == AF_INET) {
++			mptcp_local->locaddr4[i].addr.s_addr = event->addr.in.s_addr;
++			mptcp_local->locaddr4[i].loc4_id = i + 1;
++			mptcp_local->locaddr4[i].low_prio = event->low_prio;
++		} else {
++			mptcp_local->locaddr6[i].addr = event->addr.in6;
++			mptcp_local->locaddr6[i].loc6_id = i + MPTCP_MAX_ADDR;
++			mptcp_local->locaddr6[i].low_prio = event->low_prio;
++		}
++
++		if (j < 0) {
++			if (event->family == AF_INET) {
++				mptcp_local->loc4_bits |= (1 << i);
++				mptcp_local->next_v4_index = i + 1;
++			} else {
++				mptcp_local->loc6_bits |= (1 << i);
++				mptcp_local->next_v6_index = i + 1;
++			}
++		}
++
++		rcu_assign_pointer(fm_ns->local, mptcp_local);
++		kfree(old);
++	}
++	success = true;
++
++duno:
++	spin_unlock(&fm_ns->local_lock);
++	rcu_read_unlock_bh();
++
++	if (!success)
++		goto next_event;
++
++	/* Now we iterate over the MPTCP-sockets and apply the event. */
++	for (i = 0; i < MPTCP_HASH_SIZE; i++) {
++		const struct hlist_nulls_node *node;
++		struct tcp_sock *meta_tp;
++
++		rcu_read_lock_bh();
++		hlist_nulls_for_each_entry_rcu(meta_tp, node, &tk_hashtable[i],
++					       tk_table) {
++			struct mptcp_cb *mpcb = meta_tp->mpcb;
++			struct sock *meta_sk = (struct sock *)meta_tp, *sk;
++			struct fullmesh_priv *fmp = fullmesh_get_priv(mpcb);
++			bool meta_v4 = meta_sk->sk_family == AF_INET;
++
++			if (sock_net(meta_sk) != net)
++				continue;
++
++			if (meta_v4) {
++				/* skip IPv6 events if meta is IPv4 */
++				if (event->family == AF_INET6)
++					continue;
++			}
++			/* skip IPv4 events if IPV6_V6ONLY is set */
++			else if (event->family == AF_INET &&
++				 inet6_sk(meta_sk)->ipv6only)
++				continue;
++
++			if (unlikely(!atomic_inc_not_zero(&meta_sk->sk_refcnt)))
++				continue;
++
++			bh_lock_sock(meta_sk);
++
++			if (!mptcp(meta_tp) || !is_meta_sk(meta_sk) ||
++			    mpcb->infinite_mapping_snd ||
++			    mpcb->infinite_mapping_rcv ||
++			    mpcb->send_infinite_mapping)
++				goto next;
++
++			/* May be that the pm has changed in-between */
++			if (mpcb->pm_ops != &full_mesh)
++				goto next;
++
++			if (sock_owned_by_user(meta_sk)) {
++				if (!test_and_set_bit(MPTCP_PATH_MANAGER,
++						      &meta_tp->tsq_flags))
++					sock_hold(meta_sk);
++
++				goto next;
++			}
++
++			if (event->code == MPTCP_EVENT_ADD) {
++				fmp->add_addr++;
++				mpcb->addr_signal = 1;
++
++				sk = mptcp_select_ack_sock(meta_sk);
++				if (sk)
++					tcp_send_ack(sk);
++
++				full_mesh_create_subflows(meta_sk);
++			}
++
++			if (event->code == MPTCP_EVENT_DEL) {
++				struct sock *sk, *tmpsk;
++				struct mptcp_loc_addr *mptcp_local;
++				bool found = false;
++
++				mptcp_local = rcu_dereference_bh(fm_ns->local);
++
++				/* In any case, we need to update our bitfields */
++				if (id >= 0)
++					update_addr_bitfields(meta_sk, mptcp_local);
++
++				/* Look for the socket and remove him */
++				mptcp_for_each_sk_safe(mpcb, sk, tmpsk) {
++					if ((event->family == AF_INET6 &&
++					     (sk->sk_family == AF_INET ||
++					      mptcp_v6_is_v4_mapped(sk))) ||
++					    (event->family == AF_INET &&
++					     (sk->sk_family == AF_INET6 &&
++					      !mptcp_v6_is_v4_mapped(sk))))
++						continue;
++
++					if (event->family == AF_INET &&
++					    (sk->sk_family == AF_INET ||
++					     mptcp_v6_is_v4_mapped(sk)) &&
++					     inet_sk(sk)->inet_saddr != event->addr.in.s_addr)
++						continue;
++
++					if (event->family == AF_INET6 &&
++					    sk->sk_family == AF_INET6 &&
++					    !ipv6_addr_equal(&inet6_sk(sk)->saddr, &event->addr.in6))
++						continue;
++
++					/* Reinject, so that pf = 1 and so we
++					 * won't select this one as the
++					 * ack-sock.
++					 */
++					mptcp_reinject_data(sk, 0);
++
++					/* We announce the removal of this id */
++					announce_remove_addr(tcp_sk(sk)->mptcp->loc_id, meta_sk);
++
++					mptcp_sub_force_close(sk);
++					found = true;
++				}
++
++				if (found)
++					goto next;
++
++				/* The id may have been given by the event,
++				 * matching on a local address. And it may not
++				 * have matched on one of the above sockets,
++				 * because the client never created a subflow.
++				 * So, we have to finally remove it here.
++				 */
++				if (id > 0)
++					announce_remove_addr(id, meta_sk);
++			}
++
++			if (event->code == MPTCP_EVENT_MOD) {
++				struct sock *sk;
++
++				mptcp_for_each_sk(mpcb, sk) {
++					struct tcp_sock *tp = tcp_sk(sk);
++					if (event->family == AF_INET &&
++					    (sk->sk_family == AF_INET ||
++					     mptcp_v6_is_v4_mapped(sk)) &&
++					     inet_sk(sk)->inet_saddr == event->addr.in.s_addr) {
++						if (event->low_prio != tp->mptcp->low_prio) {
++							tp->mptcp->send_mp_prio = 1;
++							tp->mptcp->low_prio = event->low_prio;
++
++							tcp_send_ack(sk);
++						}
++					}
++
++					if (event->family == AF_INET6 &&
++					    sk->sk_family == AF_INET6 &&
++					    !ipv6_addr_equal(&inet6_sk(sk)->saddr, &event->addr.in6)) {
++						if (event->low_prio != tp->mptcp->low_prio) {
++							tp->mptcp->send_mp_prio = 1;
++							tp->mptcp->low_prio = event->low_prio;
++
++							tcp_send_ack(sk);
++						}
++					}
++				}
++			}
++next:
++			bh_unlock_sock(meta_sk);
++			sock_put(meta_sk);
++		}
++		rcu_read_unlock_bh();
++	}
++	goto next_event;
++}
++
++static struct mptcp_addr_event *lookup_similar_event(const struct net *net,
++						     const struct mptcp_addr_event *event)
++{
++	struct mptcp_addr_event *eventq;
++	struct mptcp_fm_ns *fm_ns = fm_get_ns(net);
++
++	list_for_each_entry(eventq, &fm_ns->events, list) {
++		if (eventq->family != event->family)
++			continue;
++		if (event->family == AF_INET) {
++			if (eventq->addr.in.s_addr == event->addr.in.s_addr)
++				return eventq;
++		} else {
++			if (ipv6_addr_equal(&eventq->addr.in6, &event->addr.in6))
++				return eventq;
++		}
++	}
++	return NULL;
++}
++
++/* We already hold the net-namespace MPTCP-lock */
++static void add_pm_event(struct net *net, const struct mptcp_addr_event *event)
++{
++	struct mptcp_addr_event *eventq = lookup_similar_event(net, event);
++	struct mptcp_fm_ns *fm_ns = fm_get_ns(net);
++
++	if (eventq) {
++		switch (event->code) {
++		case MPTCP_EVENT_DEL:
++			mptcp_debug("%s del old_code %u\n", __func__, eventq->code);
++			list_del(&eventq->list);
++			kfree(eventq);
++			break;
++		case MPTCP_EVENT_ADD:
++			mptcp_debug("%s add old_code %u\n", __func__, eventq->code);
++			eventq->low_prio = event->low_prio;
++			eventq->code = MPTCP_EVENT_ADD;
++			return;
++		case MPTCP_EVENT_MOD:
++			mptcp_debug("%s mod old_code %u\n", __func__, eventq->code);
++			eventq->low_prio = event->low_prio;
++			eventq->code = MPTCP_EVENT_MOD;
++			return;
++		}
++	}
++
++	/* OK, we have to add the new address to the wait queue */
++	eventq = kmemdup(event, sizeof(struct mptcp_addr_event), GFP_ATOMIC);
++	if (!eventq)
++		return;
++
++	list_add_tail(&eventq->list, &fm_ns->events);
++
++	/* Create work-queue */
++	if (!delayed_work_pending(&fm_ns->address_worker))
++		queue_delayed_work(mptcp_wq, &fm_ns->address_worker,
++				   msecs_to_jiffies(500));
++}
++
++static void addr4_event_handler(const struct in_ifaddr *ifa, unsigned long event,
++				struct net *net)
++{
++	const struct net_device *netdev = ifa->ifa_dev->dev;
++	struct mptcp_fm_ns *fm_ns = fm_get_ns(net);
++	struct mptcp_addr_event mpevent;
++
++	if (ifa->ifa_scope > RT_SCOPE_LINK ||
++	    ipv4_is_loopback(ifa->ifa_local))
++		return;
++
++	spin_lock_bh(&fm_ns->local_lock);
++
++	mpevent.family = AF_INET;
++	mpevent.addr.in.s_addr = ifa->ifa_local;
++	mpevent.low_prio = (netdev->flags & IFF_MPBACKUP) ? 1 : 0;
++
++	if (event == NETDEV_DOWN || !netif_running(netdev) ||
++	    (netdev->flags & IFF_NOMULTIPATH) || !(netdev->flags & IFF_UP))
++		mpevent.code = MPTCP_EVENT_DEL;
++	else if (event == NETDEV_UP)
++		mpevent.code = MPTCP_EVENT_ADD;
++	else if (event == NETDEV_CHANGE)
++		mpevent.code = MPTCP_EVENT_MOD;
++
++	mptcp_debug("%s created event for %pI4, code %u prio %u\n", __func__,
++		    &ifa->ifa_local, mpevent.code, mpevent.low_prio);
++	add_pm_event(net, &mpevent);
++
++	spin_unlock_bh(&fm_ns->local_lock);
++	return;
++}
++
++/* React on IPv4-addr add/rem-events */
++static int mptcp_pm_inetaddr_event(struct notifier_block *this,
++				   unsigned long event, void *ptr)
++{
++	const struct in_ifaddr *ifa = (struct in_ifaddr *)ptr;
++	struct net *net = dev_net(ifa->ifa_dev->dev);
++
++	if (!(event == NETDEV_UP || event == NETDEV_DOWN ||
++	      event == NETDEV_CHANGE))
++		return NOTIFY_DONE;
++
++	addr4_event_handler(ifa, event, net);
++
++	return NOTIFY_DONE;
++}
++
++static struct notifier_block mptcp_pm_inetaddr_notifier = {
++		.notifier_call = mptcp_pm_inetaddr_event,
++};
++
++#if IS_ENABLED(CONFIG_IPV6)
++
++/* IPV6-related address/interface watchers */
++struct mptcp_dad_data {
++	struct timer_list timer;
++	struct inet6_ifaddr *ifa;
++};
++
++static void dad_callback(unsigned long arg);
++static int inet6_addr_event(struct notifier_block *this,
++				     unsigned long event, void *ptr);
++
++static int ipv6_is_in_dad_state(const struct inet6_ifaddr *ifa)
++{
++	return (ifa->flags & IFA_F_TENTATIVE) &&
++	       ifa->state == INET6_IFADDR_STATE_DAD;
++}
++
++static void dad_init_timer(struct mptcp_dad_data *data,
++				 struct inet6_ifaddr *ifa)
++{
++	data->ifa = ifa;
++	data->timer.data = (unsigned long)data;
++	data->timer.function = dad_callback;
++	if (ifa->idev->cnf.rtr_solicit_delay)
++		data->timer.expires = jiffies + ifa->idev->cnf.rtr_solicit_delay;
++	else
++		data->timer.expires = jiffies + (HZ/10);
++}
++
++static void dad_callback(unsigned long arg)
++{
++	struct mptcp_dad_data *data = (struct mptcp_dad_data *)arg;
++
++	if (ipv6_is_in_dad_state(data->ifa)) {
++		dad_init_timer(data, data->ifa);
++		add_timer(&data->timer);
++	} else {
++		inet6_addr_event(NULL, NETDEV_UP, data->ifa);
++		in6_ifa_put(data->ifa);
++		kfree(data);
++	}
++}
++
++static inline void dad_setup_timer(struct inet6_ifaddr *ifa)
++{
++	struct mptcp_dad_data *data;
++
++	data = kmalloc(sizeof(*data), GFP_ATOMIC);
++
++	if (!data)
++		return;
++
++	init_timer(&data->timer);
++	dad_init_timer(data, ifa);
++	add_timer(&data->timer);
++	in6_ifa_hold(ifa);
++}
++
++static void addr6_event_handler(const struct inet6_ifaddr *ifa, unsigned long event,
++				struct net *net)
++{
++	const struct net_device *netdev = ifa->idev->dev;
++	int addr_type = ipv6_addr_type(&ifa->addr);
++	struct mptcp_fm_ns *fm_ns = fm_get_ns(net);
++	struct mptcp_addr_event mpevent;
++
++	if (ifa->scope > RT_SCOPE_LINK ||
++	    addr_type == IPV6_ADDR_ANY ||
++	    (addr_type & IPV6_ADDR_LOOPBACK) ||
++	    (addr_type & IPV6_ADDR_LINKLOCAL))
++		return;
++
++	spin_lock_bh(&fm_ns->local_lock);
++
++	mpevent.family = AF_INET6;
++	mpevent.addr.in6 = ifa->addr;
++	mpevent.low_prio = (netdev->flags & IFF_MPBACKUP) ? 1 : 0;
++
++	if (event == NETDEV_DOWN || !netif_running(netdev) ||
++	    (netdev->flags & IFF_NOMULTIPATH) || !(netdev->flags & IFF_UP))
++		mpevent.code = MPTCP_EVENT_DEL;
++	else if (event == NETDEV_UP)
++		mpevent.code = MPTCP_EVENT_ADD;
++	else if (event == NETDEV_CHANGE)
++		mpevent.code = MPTCP_EVENT_MOD;
++
++	mptcp_debug("%s created event for %pI6, code %u prio %u\n", __func__,
++		    &ifa->addr, mpevent.code, mpevent.low_prio);
++	add_pm_event(net, &mpevent);
++
++	spin_unlock_bh(&fm_ns->local_lock);
++	return;
++}
++
++/* React on IPv6-addr add/rem-events */
++static int inet6_addr_event(struct notifier_block *this, unsigned long event,
++			    void *ptr)
++{
++	struct inet6_ifaddr *ifa6 = (struct inet6_ifaddr *)ptr;
++	struct net *net = dev_net(ifa6->idev->dev);
++
++	if (!(event == NETDEV_UP || event == NETDEV_DOWN ||
++	      event == NETDEV_CHANGE))
++		return NOTIFY_DONE;
++
++	if (ipv6_is_in_dad_state(ifa6))
++		dad_setup_timer(ifa6);
++	else
++		addr6_event_handler(ifa6, event, net);
++
++	return NOTIFY_DONE;
++}
++
++static struct notifier_block inet6_addr_notifier = {
++		.notifier_call = inet6_addr_event,
++};
++
++#endif
++
++/* React on ifup/down-events */
++static int netdev_event(struct notifier_block *this, unsigned long event,
++			void *ptr)
++{
++	const struct net_device *dev = netdev_notifier_info_to_dev(ptr);
++	struct in_device *in_dev;
++#if IS_ENABLED(CONFIG_IPV6)
++	struct inet6_dev *in6_dev;
++#endif
++
++	if (!(event == NETDEV_UP || event == NETDEV_DOWN ||
++	      event == NETDEV_CHANGE))
++		return NOTIFY_DONE;
++
++	rcu_read_lock();
++	in_dev = __in_dev_get_rtnl(dev);
++
++	if (in_dev) {
++		for_ifa(in_dev) {
++			mptcp_pm_inetaddr_event(NULL, event, ifa);
++		} endfor_ifa(in_dev);
++	}
++
++#if IS_ENABLED(CONFIG_IPV6)
++	in6_dev = __in6_dev_get(dev);
++
++	if (in6_dev) {
++		struct inet6_ifaddr *ifa6;
++		list_for_each_entry(ifa6, &in6_dev->addr_list, if_list)
++			inet6_addr_event(NULL, event, ifa6);
++	}
++#endif
++
++	rcu_read_unlock();
++	return NOTIFY_DONE;
++}
++
++static struct notifier_block mptcp_pm_netdev_notifier = {
++		.notifier_call = netdev_event,
++};
++
++static void full_mesh_add_raddr(struct mptcp_cb *mpcb,
++				const union inet_addr *addr,
++				sa_family_t family, __be16 port, u8 id)
++{
++	if (family == AF_INET)
++		mptcp_addv4_raddr(mpcb, &addr->in, port, id);
++	else
++		mptcp_addv6_raddr(mpcb, &addr->in6, port, id);
++}
++
++static void full_mesh_new_session(const struct sock *meta_sk)
++{
++	struct mptcp_loc_addr *mptcp_local;
++	struct mptcp_cb *mpcb = tcp_sk(meta_sk)->mpcb;
++	struct fullmesh_priv *fmp = fullmesh_get_priv(mpcb);
++	const struct mptcp_fm_ns *fm_ns = fm_get_ns(sock_net(meta_sk));
++	int i, index;
++	union inet_addr saddr, daddr;
++	sa_family_t family;
++	bool meta_v4 = meta_sk->sk_family == AF_INET;
++
++	/* Init local variables necessary for the rest */
++	if (meta_sk->sk_family == AF_INET || mptcp_v6_is_v4_mapped(meta_sk)) {
++		saddr.ip = inet_sk(meta_sk)->inet_saddr;
++		daddr.ip = inet_sk(meta_sk)->inet_daddr;
++		family = AF_INET;
++#if IS_ENABLED(CONFIG_IPV6)
++	} else {
++		saddr.in6 = inet6_sk(meta_sk)->saddr;
++		daddr.in6 = meta_sk->sk_v6_daddr;
++		family = AF_INET6;
++#endif
++	}
++
++	rcu_read_lock();
++	mptcp_local = rcu_dereference(fm_ns->local);
++
++	index = mptcp_find_address(mptcp_local, family, &saddr);
++	if (index < 0)
++		goto fallback;
++
++	full_mesh_add_raddr(mpcb, &daddr, family, 0, 0);
++	mptcp_set_init_addr_bit(mpcb, &daddr, family, index);
++
++	/* Initialize workqueue-struct */
++	INIT_WORK(&fmp->subflow_work, create_subflow_worker);
++	INIT_DELAYED_WORK(&fmp->subflow_retry_work, retry_subflow_worker);
++	fmp->mpcb = mpcb;
++
++	if (!meta_v4 && inet6_sk(meta_sk)->ipv6only)
++		goto skip_ipv4;
++
++	/* Look for the address among the local addresses */
++	mptcp_for_each_bit_set(mptcp_local->loc4_bits, i) {
++		__be32 ifa_address = mptcp_local->locaddr4[i].addr.s_addr;
++
++		/* We do not need to announce the initial subflow's address again */
++		if (family == AF_INET && saddr.ip == ifa_address)
++			continue;
++
++		fmp->add_addr++;
++		mpcb->addr_signal = 1;
++	}
++
++skip_ipv4:
++#if IS_ENABLED(CONFIG_IPV6)
++	/* skip IPv6 addresses if meta-socket is IPv4 */
++	if (meta_v4)
++		goto skip_ipv6;
++
++	mptcp_for_each_bit_set(mptcp_local->loc6_bits, i) {
++		const struct in6_addr *ifa6 = &mptcp_local->locaddr6[i].addr;
++
++		/* We do not need to announce the initial subflow's address again */
++		if (family == AF_INET6 && ipv6_addr_equal(&saddr.in6, ifa6))
++			continue;
++
++		fmp->add_addr++;
++		mpcb->addr_signal = 1;
++	}
++
++skip_ipv6:
++#endif
++
++	rcu_read_unlock();
++
++	if (family == AF_INET)
++		fmp->announced_addrs_v4 |= (1 << index);
++	else
++		fmp->announced_addrs_v6 |= (1 << index);
++
++	for (i = fmp->add_addr; i && fmp->add_addr; i--)
++		tcp_send_ack(mpcb->master_sk);
++
++	return;
++
++fallback:
++	rcu_read_unlock();
++	mptcp_fallback_default(mpcb);
++	return;
++}
++
++static void full_mesh_create_subflows(struct sock *meta_sk)
++{
++	const struct mptcp_cb *mpcb = tcp_sk(meta_sk)->mpcb;
++	struct fullmesh_priv *fmp = fullmesh_get_priv(mpcb);
++
++	if (mpcb->infinite_mapping_snd || mpcb->infinite_mapping_rcv ||
++	    mpcb->send_infinite_mapping ||
++	    mpcb->server_side || sock_flag(meta_sk, SOCK_DEAD))
++		return;
++
++	if (mpcb->master_sk &&
++	    !tcp_sk(mpcb->master_sk)->mptcp->fully_established)
++		return;
++
++	if (!work_pending(&fmp->subflow_work)) {
++		sock_hold(meta_sk);
++		queue_work(mptcp_wq, &fmp->subflow_work);
++	}
++}
++
++/* Called upon release_sock, if the socket was owned by the user during
++ * a path-management event.
++ */
++static void full_mesh_release_sock(struct sock *meta_sk)
++{
++	struct mptcp_loc_addr *mptcp_local;
++	struct mptcp_cb *mpcb = tcp_sk(meta_sk)->mpcb;
++	struct fullmesh_priv *fmp = fullmesh_get_priv(mpcb);
++	const struct mptcp_fm_ns *fm_ns = fm_get_ns(sock_net(meta_sk));
++	struct sock *sk, *tmpsk;
++	bool meta_v4 = meta_sk->sk_family == AF_INET;
++	int i;
++
++	rcu_read_lock();
++	mptcp_local = rcu_dereference(fm_ns->local);
++
++	if (!meta_v4 && inet6_sk(meta_sk)->ipv6only)
++		goto skip_ipv4;
++
++	/* First, detect modifications or additions */
++	mptcp_for_each_bit_set(mptcp_local->loc4_bits, i) {
++		struct in_addr ifa = mptcp_local->locaddr4[i].addr;
++		bool found = false;
++
++		mptcp_for_each_sk(mpcb, sk) {
++			struct tcp_sock *tp = tcp_sk(sk);
++
++			if (sk->sk_family == AF_INET6 &&
++			    !mptcp_v6_is_v4_mapped(sk))
++				continue;
++
++			if (inet_sk(sk)->inet_saddr != ifa.s_addr)
++				continue;
++
++			found = true;
++
++			if (mptcp_local->locaddr4[i].low_prio != tp->mptcp->low_prio) {
++				tp->mptcp->send_mp_prio = 1;
++				tp->mptcp->low_prio = mptcp_local->locaddr4[i].low_prio;
++
++				tcp_send_ack(sk);
++			}
++		}
++
++		if (!found) {
++			fmp->add_addr++;
++			mpcb->addr_signal = 1;
++
++			sk = mptcp_select_ack_sock(meta_sk);
++			if (sk)
++				tcp_send_ack(sk);
++			full_mesh_create_subflows(meta_sk);
++		}
++	}
++
++skip_ipv4:
++#if IS_ENABLED(CONFIG_IPV6)
++	/* skip IPv6 addresses if meta-socket is IPv4 */
++	if (meta_v4)
++		goto removal;
++
++	mptcp_for_each_bit_set(mptcp_local->loc6_bits, i) {
++		struct in6_addr ifa = mptcp_local->locaddr6[i].addr;
++		bool found = false;
++
++		mptcp_for_each_sk(mpcb, sk) {
++			struct tcp_sock *tp = tcp_sk(sk);
++
++			if (sk->sk_family == AF_INET ||
++			    mptcp_v6_is_v4_mapped(sk))
++				continue;
++
++			if (!ipv6_addr_equal(&inet6_sk(sk)->saddr, &ifa))
++				continue;
++
++			found = true;
++
++			if (mptcp_local->locaddr6[i].low_prio != tp->mptcp->low_prio) {
++				tp->mptcp->send_mp_prio = 1;
++				tp->mptcp->low_prio = mptcp_local->locaddr6[i].low_prio;
++
++				tcp_send_ack(sk);
++			}
++		}
++
++		if (!found) {
++			fmp->add_addr++;
++			mpcb->addr_signal = 1;
++
++			sk = mptcp_select_ack_sock(meta_sk);
++			if (sk)
++				tcp_send_ack(sk);
++			full_mesh_create_subflows(meta_sk);
++		}
++	}
++
++removal:
++#endif
++
++	/* Now, detect address-removals */
++	mptcp_for_each_sk_safe(mpcb, sk, tmpsk) {
++		bool shall_remove = true;
++
++		if (sk->sk_family == AF_INET || mptcp_v6_is_v4_mapped(sk)) {
++			mptcp_for_each_bit_set(mptcp_local->loc4_bits, i) {
++				if (inet_sk(sk)->inet_saddr == mptcp_local->locaddr4[i].addr.s_addr) {
++					shall_remove = false;
++					break;
++				}
++			}
++		} else {
++			mptcp_for_each_bit_set(mptcp_local->loc6_bits, i) {
++				if (ipv6_addr_equal(&inet6_sk(sk)->saddr, &mptcp_local->locaddr6[i].addr)) {
++					shall_remove = false;
++					break;
++				}
++			}
++		}
++
++		if (shall_remove) {
++			/* Reinject, so that pf = 1 and so we
++			 * won't select this one as the
++			 * ack-sock.
++			 */
++			mptcp_reinject_data(sk, 0);
++
++			announce_remove_addr(tcp_sk(sk)->mptcp->loc_id,
++					     meta_sk);
++
++			mptcp_sub_force_close(sk);
++		}
++	}
++
++	/* Just call it optimistically. It actually cannot do any harm */
++	update_addr_bitfields(meta_sk, mptcp_local);
++
++	rcu_read_unlock();
++}
++
++static int full_mesh_get_local_id(sa_family_t family, union inet_addr *addr,
++				  struct net *net, bool *low_prio)
++{
++	struct mptcp_loc_addr *mptcp_local;
++	const struct mptcp_fm_ns *fm_ns = fm_get_ns(net);
++	int index, id = -1;
++
++	/* Handle the backup-flows */
++	rcu_read_lock();
++	mptcp_local = rcu_dereference(fm_ns->local);
++
++	index = mptcp_find_address(mptcp_local, family, addr);
++
++	if (index != -1) {
++		if (family == AF_INET) {
++			id = mptcp_local->locaddr4[index].loc4_id;
++			*low_prio = mptcp_local->locaddr4[index].low_prio;
++		} else {
++			id = mptcp_local->locaddr6[index].loc6_id;
++			*low_prio = mptcp_local->locaddr6[index].low_prio;
++		}
++	}
++
++
++	rcu_read_unlock();
++
++	return id;
++}
++
++static void full_mesh_addr_signal(struct sock *sk, unsigned *size,
++				  struct tcp_out_options *opts,
++				  struct sk_buff *skb)
++{
++	const struct tcp_sock *tp = tcp_sk(sk);
++	struct mptcp_cb *mpcb = tp->mpcb;
++	struct sock *meta_sk = mpcb->meta_sk;
++	struct fullmesh_priv *fmp = fullmesh_get_priv(mpcb);
++	struct mptcp_loc_addr *mptcp_local;
++	struct mptcp_fm_ns *fm_ns = fm_get_ns(sock_net(sk));
++	int remove_addr_len;
++	u8 unannouncedv4 = 0, unannouncedv6 = 0;
++	bool meta_v4 = meta_sk->sk_family == AF_INET;
++
++	mpcb->addr_signal = 0;
++
++	if (likely(!fmp->add_addr))
++		goto remove_addr;
++
++	rcu_read_lock();
++	mptcp_local = rcu_dereference(fm_ns->local);
++
++	if (!meta_v4 && inet6_sk(meta_sk)->ipv6only)
++		goto skip_ipv4;
++
++	/* IPv4 */
++	unannouncedv4 = (~fmp->announced_addrs_v4) & mptcp_local->loc4_bits;
++	if (unannouncedv4 &&
++	    MAX_TCP_OPTION_SPACE - *size >= MPTCP_SUB_LEN_ADD_ADDR4_ALIGN) {
++		int ind = mptcp_find_free_index(~unannouncedv4);
++
++		opts->options |= OPTION_MPTCP;
++		opts->mptcp_options |= OPTION_ADD_ADDR;
++		opts->add_addr4.addr_id = mptcp_local->locaddr4[ind].loc4_id;
++		opts->add_addr4.addr = mptcp_local->locaddr4[ind].addr;
++		opts->add_addr_v4 = 1;
++
++		if (skb) {
++			fmp->announced_addrs_v4 |= (1 << ind);
++			fmp->add_addr--;
++		}
++		*size += MPTCP_SUB_LEN_ADD_ADDR4_ALIGN;
++	}
++
++	if (meta_v4)
++		goto skip_ipv6;
++
++skip_ipv4:
++	/* IPv6 */
++	unannouncedv6 = (~fmp->announced_addrs_v6) & mptcp_local->loc6_bits;
++	if (unannouncedv6 &&
++	    MAX_TCP_OPTION_SPACE - *size >= MPTCP_SUB_LEN_ADD_ADDR6_ALIGN) {
++		int ind = mptcp_find_free_index(~unannouncedv6);
++
++		opts->options |= OPTION_MPTCP;
++		opts->mptcp_options |= OPTION_ADD_ADDR;
++		opts->add_addr6.addr_id = mptcp_local->locaddr6[ind].loc6_id;
++		opts->add_addr6.addr = mptcp_local->locaddr6[ind].addr;
++		opts->add_addr_v6 = 1;
++
++		if (skb) {
++			fmp->announced_addrs_v6 |= (1 << ind);
++			fmp->add_addr--;
++		}
++		*size += MPTCP_SUB_LEN_ADD_ADDR6_ALIGN;
++	}
++
++skip_ipv6:
++	rcu_read_unlock();
++
++	if (!unannouncedv4 && !unannouncedv6 && skb)
++		fmp->add_addr--;
++
++remove_addr:
++	if (likely(!fmp->remove_addrs))
++		goto exit;
++
++	remove_addr_len = mptcp_sub_len_remove_addr_align(fmp->remove_addrs);
++	if (MAX_TCP_OPTION_SPACE - *size < remove_addr_len)
++		goto exit;
++
++	opts->options |= OPTION_MPTCP;
++	opts->mptcp_options |= OPTION_REMOVE_ADDR;
++	opts->remove_addrs = fmp->remove_addrs;
++	*size += remove_addr_len;
++	if (skb)
++		fmp->remove_addrs = 0;
++
++exit:
++	mpcb->addr_signal = !!(fmp->add_addr || fmp->remove_addrs);
++}
++
++static void full_mesh_rem_raddr(struct mptcp_cb *mpcb, u8 rem_id)
++{
++	mptcp_v4_rem_raddress(mpcb, rem_id);
++	mptcp_v6_rem_raddress(mpcb, rem_id);
++}
++
++/* Output /proc/net/mptcp_fullmesh */
++static int mptcp_fm_seq_show(struct seq_file *seq, void *v)
++{
++	const struct net *net = seq->private;
++	struct mptcp_loc_addr *mptcp_local;
++	const struct mptcp_fm_ns *fm_ns = fm_get_ns(net);
++	int i;
++
++	seq_printf(seq, "Index, Address-ID, Backup, IP-address\n");
++
++	rcu_read_lock_bh();
++	mptcp_local = rcu_dereference(fm_ns->local);
++
++	seq_printf(seq, "IPv4, next v4-index: %u\n", mptcp_local->next_v4_index);
++
++	mptcp_for_each_bit_set(mptcp_local->loc4_bits, i) {
++		struct mptcp_loc4 *loc4 = &mptcp_local->locaddr4[i];
++
++		seq_printf(seq, "%u, %u, %u, %pI4\n", i, loc4->loc4_id,
++			   loc4->low_prio, &loc4->addr);
++	}
++
++	seq_printf(seq, "IPv6, next v6-index: %u\n", mptcp_local->next_v6_index);
++
++	mptcp_for_each_bit_set(mptcp_local->loc6_bits, i) {
++		struct mptcp_loc6 *loc6 = &mptcp_local->locaddr6[i];
++
++		seq_printf(seq, "%u, %u, %u, %pI6\n", i, loc6->loc6_id,
++			   loc6->low_prio, &loc6->addr);
++	}
++	rcu_read_unlock_bh();
++
++	return 0;
++}
++
++static int mptcp_fm_seq_open(struct inode *inode, struct file *file)
++{
++	return single_open_net(inode, file, mptcp_fm_seq_show);
++}
++
++static const struct file_operations mptcp_fm_seq_fops = {
++	.owner = THIS_MODULE,
++	.open = mptcp_fm_seq_open,
++	.read = seq_read,
++	.llseek = seq_lseek,
++	.release = single_release_net,
++};
++
++static int mptcp_fm_init_net(struct net *net)
++{
++	struct mptcp_loc_addr *mptcp_local;
++	struct mptcp_fm_ns *fm_ns;
++	int err = 0;
++
++	fm_ns = kzalloc(sizeof(*fm_ns), GFP_KERNEL);
++	if (!fm_ns)
++		return -ENOBUFS;
++
++	mptcp_local = kzalloc(sizeof(*mptcp_local), GFP_KERNEL);
++	if (!mptcp_local) {
++		err = -ENOBUFS;
++		goto err_mptcp_local;
++	}
++
++	if (!proc_create("mptcp_fullmesh", S_IRUGO, net->proc_net,
++			 &mptcp_fm_seq_fops)) {
++		err = -ENOMEM;
++		goto err_seq_fops;
++	}
++
++	mptcp_local->next_v4_index = 1;
++
++	rcu_assign_pointer(fm_ns->local, mptcp_local);
++	INIT_DELAYED_WORK(&fm_ns->address_worker, mptcp_address_worker);
++	INIT_LIST_HEAD(&fm_ns->events);
++	spin_lock_init(&fm_ns->local_lock);
++	fm_ns->net = net;
++	net->mptcp.path_managers[MPTCP_PM_FULLMESH] = fm_ns;
++
++	return 0;
++err_seq_fops:
++	kfree(mptcp_local);
++err_mptcp_local:
++	kfree(fm_ns);
++	return err;
++}
++
++static void mptcp_fm_exit_net(struct net *net)
++{
++	struct mptcp_addr_event *eventq, *tmp;
++	struct mptcp_fm_ns *fm_ns;
++	struct mptcp_loc_addr *mptcp_local;
++
++	fm_ns = fm_get_ns(net);
++	cancel_delayed_work_sync(&fm_ns->address_worker);
++
++	rcu_read_lock_bh();
++
++	mptcp_local = rcu_dereference_bh(fm_ns->local);
++	kfree(mptcp_local);
++
++	spin_lock(&fm_ns->local_lock);
++	list_for_each_entry_safe(eventq, tmp, &fm_ns->events, list) {
++		list_del(&eventq->list);
++		kfree(eventq);
++	}
++	spin_unlock(&fm_ns->local_lock);
++
++	rcu_read_unlock_bh();
++
++	remove_proc_entry("mptcp_fullmesh", net->proc_net);
++
++	kfree(fm_ns);
++}
++
++static struct pernet_operations full_mesh_net_ops = {
++	.init = mptcp_fm_init_net,
++	.exit = mptcp_fm_exit_net,
++};
++
++static struct mptcp_pm_ops full_mesh __read_mostly = {
++	.new_session = full_mesh_new_session,
++	.release_sock = full_mesh_release_sock,
++	.fully_established = full_mesh_create_subflows,
++	.new_remote_address = full_mesh_create_subflows,
++	.get_local_id = full_mesh_get_local_id,
++	.addr_signal = full_mesh_addr_signal,
++	.add_raddr = full_mesh_add_raddr,
++	.rem_raddr = full_mesh_rem_raddr,
++	.name = "fullmesh",
++	.owner = THIS_MODULE,
++};
++
++/* General initialization of MPTCP_PM */
++static int __init full_mesh_register(void)
++{
++	int ret;
++
++	BUILD_BUG_ON(sizeof(struct fullmesh_priv) > MPTCP_PM_SIZE);
++
++	ret = register_pernet_subsys(&full_mesh_net_ops);
++	if (ret)
++		goto out;
++
++	ret = register_inetaddr_notifier(&mptcp_pm_inetaddr_notifier);
++	if (ret)
++		goto err_reg_inetaddr;
++	ret = register_netdevice_notifier(&mptcp_pm_netdev_notifier);
++	if (ret)
++		goto err_reg_netdev;
++
++#if IS_ENABLED(CONFIG_IPV6)
++	ret = register_inet6addr_notifier(&inet6_addr_notifier);
++	if (ret)
++		goto err_reg_inet6addr;
++#endif
++
++	ret = mptcp_register_path_manager(&full_mesh);
++	if (ret)
++		goto err_reg_pm;
++
++out:
++	return ret;
++
++
++err_reg_pm:
++#if IS_ENABLED(CONFIG_IPV6)
++	unregister_inet6addr_notifier(&inet6_addr_notifier);
++err_reg_inet6addr:
++#endif
++	unregister_netdevice_notifier(&mptcp_pm_netdev_notifier);
++err_reg_netdev:
++	unregister_inetaddr_notifier(&mptcp_pm_inetaddr_notifier);
++err_reg_inetaddr:
++	unregister_pernet_subsys(&full_mesh_net_ops);
++	goto out;
++}
++
++static void full_mesh_unregister(void)
++{
++#if IS_ENABLED(CONFIG_IPV6)
++	unregister_inet6addr_notifier(&inet6_addr_notifier);
++#endif
++	unregister_netdevice_notifier(&mptcp_pm_netdev_notifier);
++	unregister_inetaddr_notifier(&mptcp_pm_inetaddr_notifier);
++	unregister_pernet_subsys(&full_mesh_net_ops);
++	mptcp_unregister_path_manager(&full_mesh);
++}
++
++module_init(full_mesh_register);
++module_exit(full_mesh_unregister);
++
++MODULE_AUTHOR("Christoph Paasch");
++MODULE_LICENSE("GPL");
++MODULE_DESCRIPTION("Full-Mesh MPTCP");
++MODULE_VERSION("0.88");
+diff --git a/net/mptcp/mptcp_input.c b/net/mptcp/mptcp_input.c
+new file mode 100644
+index 000000000000..43704ccb639e
+--- /dev/null
++++ b/net/mptcp/mptcp_input.c
+@@ -0,0 +1,2405 @@
++/*
++ *	MPTCP implementation - Sending side
++ *
++ *	Initial Design & Implementation:
++ *	Sébastien Barré <sebastien.barre@×××××××××.be>
++ *
++ *	Current Maintainer & Author:
++ *	Christoph Paasch <christoph.paasch@×××××××××.be>
++ *
++ *	Additional authors:
++ *	Jaakko Korkeaniemi <jaakko.korkeaniemi@×××××.fi>
++ *	Gregory Detal <gregory.detal@×××××××××.be>
++ *	Fabien Duchêne <fabien.duchene@×××××××××.be>
++ *	Andreas Seelinger <Andreas.Seelinger@×××××××××××.de>
++ *	Lavkesh Lahngir <lavkesh51@×××××.com>
++ *	Andreas Ripke <ripke@××××××.eu>
++ *	Vlad Dogaru <vlad.dogaru@×××××.com>
++ *	Octavian Purdila <octavian.purdila@×××××.com>
++ *	John Ronan <jronan@××××.org>
++ *	Catalin Nicutar <catalin.nicutar@×××××.com>
++ *	Brandon Heller <brandonh@××××××××.edu>
++ *
++ *
++ *	This program is free software; you can redistribute it and/or
++ *      modify it under the terms of the GNU General Public License
++ *      as published by the Free Software Foundation; either version
++ *      2 of the License, or (at your option) any later version.
++ */
++
++#include <asm/unaligned.h>
++
++#include <net/mptcp.h>
++#include <net/mptcp_v4.h>
++#include <net/mptcp_v6.h>
++
++#include <linux/kconfig.h>
++
++/* is seq1 < seq2 ? */
++static inline bool before64(const u64 seq1, const u64 seq2)
++{
++	return (s64)(seq1 - seq2) < 0;
++}
++
++/* is seq1 > seq2 ? */
++#define after64(seq1, seq2)	before64(seq2, seq1)
++
++static inline void mptcp_become_fully_estab(struct sock *sk)
++{
++	tcp_sk(sk)->mptcp->fully_established = 1;
++
++	if (is_master_tp(tcp_sk(sk)) &&
++	    tcp_sk(sk)->mpcb->pm_ops->fully_established)
++		tcp_sk(sk)->mpcb->pm_ops->fully_established(mptcp_meta_sk(sk));
++}
++
++/* Similar to tcp_tso_acked without any memory accounting */
++static inline int mptcp_tso_acked_reinject(const struct sock *meta_sk,
++					   struct sk_buff *skb)
++{
++	const struct tcp_sock *meta_tp = tcp_sk(meta_sk);
++	u32 packets_acked, len;
++
++	BUG_ON(!after(TCP_SKB_CB(skb)->end_seq, meta_tp->snd_una));
++
++	packets_acked = tcp_skb_pcount(skb);
++
++	if (skb_unclone(skb, GFP_ATOMIC))
++		return 0;
++
++	len = meta_tp->snd_una - TCP_SKB_CB(skb)->seq;
++	__pskb_trim_head(skb, len);
++
++	TCP_SKB_CB(skb)->seq += len;
++	skb->ip_summed = CHECKSUM_PARTIAL;
++	skb->truesize	     -= len;
++
++	/* Any change of skb->len requires recalculation of tso factor. */
++	if (tcp_skb_pcount(skb) > 1)
++		tcp_set_skb_tso_segs(meta_sk, skb, tcp_skb_mss(skb));
++	packets_acked -= tcp_skb_pcount(skb);
++
++	if (packets_acked) {
++		BUG_ON(tcp_skb_pcount(skb) == 0);
++		BUG_ON(!before(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq));
++	}
++
++	return packets_acked;
++}
++
++/**
++ * Cleans the meta-socket retransmission queue and the reinject-queue.
++ * @sk must be the metasocket.
++ */
++static void mptcp_clean_rtx_queue(struct sock *meta_sk, u32 prior_snd_una)
++{
++	struct sk_buff *skb, *tmp;
++	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
++	struct mptcp_cb *mpcb = meta_tp->mpcb;
++	bool acked = false;
++	u32 acked_pcount;
++
++	while ((skb = tcp_write_queue_head(meta_sk)) &&
++	       skb != tcp_send_head(meta_sk)) {
++		bool fully_acked = true;
++
++		if (before(meta_tp->snd_una, TCP_SKB_CB(skb)->end_seq)) {
++			if (tcp_skb_pcount(skb) == 1 ||
++			    !after(meta_tp->snd_una, TCP_SKB_CB(skb)->seq))
++				break;
++
++			acked_pcount = tcp_tso_acked(meta_sk, skb);
++			if (!acked_pcount)
++				break;
++
++			fully_acked = false;
++		} else {
++			acked_pcount = tcp_skb_pcount(skb);
++		}
++
++		acked = true;
++		meta_tp->packets_out -= acked_pcount;
++		meta_tp->retrans_stamp = 0;
++
++		if (!fully_acked)
++			break;
++
++		tcp_unlink_write_queue(skb, meta_sk);
++
++		if (mptcp_is_data_fin(skb)) {
++			struct sock *sk_it;
++
++			/* DATA_FIN has been acknowledged - now we can close
++			 * the subflows
++			 */
++			mptcp_for_each_sk(mpcb, sk_it) {
++				unsigned long delay = 0;
++
++				/* If we are the passive closer, don't trigger
++				 * subflow-fin until the subflow has been finned
++				 * by the peer - thus we add a delay.
++				 */
++				if (mpcb->passive_close &&
++				    sk_it->sk_state == TCP_ESTABLISHED)
++					delay = inet_csk(sk_it)->icsk_rto << 3;
++
++				mptcp_sub_close(sk_it, delay);
++			}
++		}
++		sk_wmem_free_skb(meta_sk, skb);
++	}
++	/* Remove acknowledged data from the reinject queue */
++	skb_queue_walk_safe(&mpcb->reinject_queue, skb, tmp) {
++		if (before(meta_tp->snd_una, TCP_SKB_CB(skb)->end_seq)) {
++			if (tcp_skb_pcount(skb) == 1 ||
++			    !after(meta_tp->snd_una, TCP_SKB_CB(skb)->seq))
++				break;
++
++			mptcp_tso_acked_reinject(meta_sk, skb);
++			break;
++		}
++
++		__skb_unlink(skb, &mpcb->reinject_queue);
++		__kfree_skb(skb);
++	}
++
++	if (likely(between(meta_tp->snd_up, prior_snd_una, meta_tp->snd_una)))
++		meta_tp->snd_up = meta_tp->snd_una;
++
++	if (acked) {
++		tcp_rearm_rto(meta_sk);
++		/* Normally this is done in tcp_try_undo_loss - but MPTCP
++		 * does not call this function.
++		 */
++		inet_csk(meta_sk)->icsk_retransmits = 0;
++	}
++}
++
++/* Inspired by tcp_rcv_state_process */
++static int mptcp_rcv_state_process(struct sock *meta_sk, struct sock *sk,
++				   const struct sk_buff *skb, u32 data_seq,
++				   u16 data_len)
++{
++	struct tcp_sock *meta_tp = tcp_sk(meta_sk), *tp = tcp_sk(sk);
++	const struct tcphdr *th = tcp_hdr(skb);
++
++	/* State-machine handling if FIN has been enqueued and he has
++	 * been acked (snd_una == write_seq) - it's important that this
++	 * here is after sk_wmem_free_skb because otherwise
++	 * sk_forward_alloc is wrong upon inet_csk_destroy_sock()
++	 */
++	switch (meta_sk->sk_state) {
++	case TCP_FIN_WAIT1: {
++		struct dst_entry *dst;
++		int tmo;
++
++		if (meta_tp->snd_una != meta_tp->write_seq)
++			break;
++
++		tcp_set_state(meta_sk, TCP_FIN_WAIT2);
++		meta_sk->sk_shutdown |= SEND_SHUTDOWN;
++
++		dst = __sk_dst_get(sk);
++		if (dst)
++			dst_confirm(dst);
++
++		if (!sock_flag(meta_sk, SOCK_DEAD)) {
++			/* Wake up lingering close() */
++			meta_sk->sk_state_change(meta_sk);
++			break;
++		}
++
++		if (meta_tp->linger2 < 0 ||
++		    (data_len &&
++		     after(data_seq + data_len - (mptcp_is_data_fin2(skb, tp) ? 1 : 0),
++			   meta_tp->rcv_nxt))) {
++			mptcp_send_active_reset(meta_sk, GFP_ATOMIC);
++			tcp_done(meta_sk);
++			NET_INC_STATS_BH(sock_net(meta_sk), LINUX_MIB_TCPABORTONDATA);
++			return 1;
++		}
++
++		tmo = tcp_fin_time(meta_sk);
++		if (tmo > TCP_TIMEWAIT_LEN) {
++			inet_csk_reset_keepalive_timer(meta_sk, tmo - TCP_TIMEWAIT_LEN);
++		} else if (mptcp_is_data_fin2(skb, tp) || sock_owned_by_user(meta_sk)) {
++			/* Bad case. We could lose such FIN otherwise.
++			 * It is not a big problem, but it looks confusing
++			 * and not so rare event. We still can lose it now,
++			 * if it spins in bh_lock_sock(), but it is really
++			 * marginal case.
++			 */
++			inet_csk_reset_keepalive_timer(meta_sk, tmo);
++		} else {
++			meta_tp->ops->time_wait(meta_sk, TCP_FIN_WAIT2, tmo);
++		}
++		break;
++	}
++	case TCP_CLOSING:
++	case TCP_LAST_ACK:
++		if (meta_tp->snd_una == meta_tp->write_seq) {
++			tcp_done(meta_sk);
++			return 1;
++		}
++		break;
++	}
++
++	/* step 7: process the segment text */
++	switch (meta_sk->sk_state) {
++	case TCP_FIN_WAIT1:
++	case TCP_FIN_WAIT2:
++		/* RFC 793 says to queue data in these states,
++		 * RFC 1122 says we MUST send a reset.
++		 * BSD 4.4 also does reset.
++		 */
++		if (meta_sk->sk_shutdown & RCV_SHUTDOWN) {
++			if (TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq &&
++			    after(TCP_SKB_CB(skb)->end_seq - th->fin, tp->rcv_nxt) &&
++			    !mptcp_is_data_fin2(skb, tp)) {
++				NET_INC_STATS_BH(sock_net(meta_sk), LINUX_MIB_TCPABORTONDATA);
++				mptcp_send_active_reset(meta_sk, GFP_ATOMIC);
++				tcp_reset(meta_sk);
++				return 1;
++			}
++		}
++		break;
++	}
++
++	return 0;
++}
++
++/**
++ * @return:
++ *  i) 1: Everything's fine.
++ *  ii) -1: A reset has been sent on the subflow - csum-failure
++ *  iii) 0: csum-failure but no reset sent, because it's the last subflow.
++ *	 Last packet should not be destroyed by the caller because it has
++ *	 been done here.
++ */
++static int mptcp_verif_dss_csum(struct sock *sk)
++{
++	struct tcp_sock *tp = tcp_sk(sk);
++	struct sk_buff *tmp, *tmp1, *last = NULL;
++	__wsum csum_tcp = 0; /* cumulative checksum of pld + mptcp-header */
++	int ans = 1, overflowed = 0, offset = 0, dss_csum_added = 0;
++	int iter = 0;
++
++	skb_queue_walk_safe(&sk->sk_receive_queue, tmp, tmp1) {
++		unsigned int csum_len;
++
++		if (before(tp->mptcp->map_subseq + tp->mptcp->map_data_len, TCP_SKB_CB(tmp)->end_seq))
++			/* Mapping ends in the middle of the packet -
++			 * csum only these bytes
++			 */
++			csum_len = tp->mptcp->map_subseq + tp->mptcp->map_data_len - TCP_SKB_CB(tmp)->seq;
++		else
++			csum_len = tmp->len;
++
++		offset = 0;
++		if (overflowed) {
++			char first_word[4];
++			first_word[0] = 0;
++			first_word[1] = 0;
++			first_word[2] = 0;
++			first_word[3] = *(tmp->data);
++			csum_tcp = csum_partial(first_word, 4, csum_tcp);
++			offset = 1;
++			csum_len--;
++			overflowed = 0;
++		}
++
++		csum_tcp = skb_checksum(tmp, offset, csum_len, csum_tcp);
++
++		/* Was it on an odd-length? Then we have to merge the next byte
++		 * correctly (see above)
++		 */
++		if (csum_len != (csum_len & (~1)))
++			overflowed = 1;
++
++		if (mptcp_is_data_seq(tmp) && !dss_csum_added) {
++			__be32 data_seq = htonl((u32)(tp->mptcp->map_data_seq >> 32));
++
++			/* If a 64-bit dss is present, we increase the offset
++			 * by 4 bytes, as the high-order 64-bits will be added
++			 * in the final csum_partial-call.
++			 */
++			u32 offset = skb_transport_offset(tmp) +
++				     TCP_SKB_CB(tmp)->dss_off;
++			if (TCP_SKB_CB(tmp)->mptcp_flags & MPTCPHDR_SEQ64_SET)
++				offset += 4;
++
++			csum_tcp = skb_checksum(tmp, offset,
++						MPTCP_SUB_LEN_SEQ_CSUM,
++						csum_tcp);
++
++			csum_tcp = csum_partial(&data_seq,
++						sizeof(data_seq), csum_tcp);
++
++			dss_csum_added = 1; /* Just do it once */
++		}
++		last = tmp;
++		iter++;
++
++		if (!skb_queue_is_last(&sk->sk_receive_queue, tmp) &&
++		    !before(TCP_SKB_CB(tmp1)->seq,
++			    tp->mptcp->map_subseq + tp->mptcp->map_data_len))
++			break;
++	}
++
++	/* Now, checksum must be 0 */
++	if (unlikely(csum_fold(csum_tcp))) {
++		pr_err("%s csum is wrong: %#x data_seq %u dss_csum_added %d overflowed %d iterations %d\n",
++		       __func__, csum_fold(csum_tcp), TCP_SKB_CB(last)->seq,
++		       dss_csum_added, overflowed, iter);
++
++		tp->mptcp->send_mp_fail = 1;
++
++		/* map_data_seq is the data-seq number of the
++		 * mapping we are currently checking
++		 */
++		tp->mpcb->csum_cutoff_seq = tp->mptcp->map_data_seq;
++
++		if (tp->mpcb->cnt_subflows > 1) {
++			mptcp_send_reset(sk);
++			ans = -1;
++		} else {
++			tp->mpcb->send_infinite_mapping = 1;
++
++			/* Need to purge the rcv-queue as it's no more valid */
++			while ((tmp = __skb_dequeue(&sk->sk_receive_queue)) != NULL) {
++				tp->copied_seq = TCP_SKB_CB(tmp)->end_seq;
++				kfree_skb(tmp);
++			}
++
++			ans = 0;
++		}
++	}
++
++	return ans;
++}
++
++static inline void mptcp_prepare_skb(struct sk_buff *skb,
++				     const struct sock *sk)
++{
++	const struct tcp_sock *tp = tcp_sk(sk);
++	struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
++	u32 inc = 0;
++
++	/* If skb is the end of this mapping (end is always at mapping-boundary
++	 * thanks to the splitting/trimming), then we need to increase
++	 * data-end-seq by 1 if this here is a data-fin.
++	 *
++	 * We need to do -1 because end_seq includes the subflow-FIN.
++	 */
++	if (tp->mptcp->map_data_fin &&
++	    (tcb->end_seq - (tcp_hdr(skb)->fin ? 1 : 0)) ==
++	    (tp->mptcp->map_subseq + tp->mptcp->map_data_len)) {
++		inc = 1;
++
++		/* We manually set the fin-flag if it is a data-fin. For easy
++		 * processing in tcp_recvmsg.
++		 */
++		tcp_hdr(skb)->fin = 1;
++	} else {
++		/* We may have a subflow-fin with data but without data-fin */
++		tcp_hdr(skb)->fin = 0;
++	}
++
++	/* Adapt data-seq's to the packet itself. We kinda transform the
++	 * dss-mapping to a per-packet granularity. This is necessary to
++	 * correctly handle overlapping mappings coming from different
++	 * subflows. Otherwise it would be a complete mess.
++	 */
++	tcb->seq = ((u32)tp->mptcp->map_data_seq) + tcb->seq - tp->mptcp->map_subseq;
++	tcb->end_seq = tcb->seq + skb->len + inc;
++}
++
++/**
++ * @return: 1 if the segment has been eaten and can be suppressed,
++ *          otherwise 0.
++ */
++static inline int mptcp_direct_copy(const struct sk_buff *skb,
++				    struct sock *meta_sk)
++{
++	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
++	int chunk = min_t(unsigned int, skb->len, meta_tp->ucopy.len);
++	int eaten = 0;
++
++	__set_current_state(TASK_RUNNING);
++
++	local_bh_enable();
++	if (!skb_copy_datagram_iovec(skb, 0, meta_tp->ucopy.iov, chunk)) {
++		meta_tp->ucopy.len -= chunk;
++		meta_tp->copied_seq += chunk;
++		eaten = (chunk == skb->len);
++		tcp_rcv_space_adjust(meta_sk);
++	}
++	local_bh_disable();
++	return eaten;
++}
++
++static inline void mptcp_reset_mapping(struct tcp_sock *tp)
++{
++	tp->mptcp->map_data_len = 0;
++	tp->mptcp->map_data_seq = 0;
++	tp->mptcp->map_subseq = 0;
++	tp->mptcp->map_data_fin = 0;
++	tp->mptcp->mapping_present = 0;
++}
++
++/* The DSS-mapping received on the sk only covers the second half of the skb
++ * (cut at seq). We trim the head from the skb.
++ * Data will be freed upon kfree().
++ *
++ * Inspired by tcp_trim_head().
++ */
++static void mptcp_skb_trim_head(struct sk_buff *skb, struct sock *sk, u32 seq)
++{
++	int len = seq - TCP_SKB_CB(skb)->seq;
++	u32 new_seq = TCP_SKB_CB(skb)->seq + len;
++
++	if (len < skb_headlen(skb))
++		__skb_pull(skb, len);
++	else
++		__pskb_trim_head(skb, len - skb_headlen(skb));
++
++	TCP_SKB_CB(skb)->seq = new_seq;
++
++	skb->truesize -= len;
++	atomic_sub(len, &sk->sk_rmem_alloc);
++	sk_mem_uncharge(sk, len);
++}
++
++/* The DSS-mapping received on the sk only covers the first half of the skb
++ * (cut at seq). We create a second skb (@return), and queue it in the rcv-queue
++ * as further packets may resolve the mapping of the second half of data.
++ *
++ * Inspired by tcp_fragment().
++ */
++static int mptcp_skb_split_tail(struct sk_buff *skb, struct sock *sk, u32 seq)
++{
++	struct sk_buff *buff;
++	int nsize;
++	int nlen, len;
++
++	len = seq - TCP_SKB_CB(skb)->seq;
++	nsize = skb_headlen(skb) - len + tcp_sk(sk)->tcp_header_len;
++	if (nsize < 0)
++		nsize = 0;
++
++	/* Get a new skb... force flag on. */
++	buff = alloc_skb(nsize, GFP_ATOMIC);
++	if (buff == NULL)
++		return -ENOMEM;
++
++	skb_reserve(buff, tcp_sk(sk)->tcp_header_len);
++	skb_reset_transport_header(buff);
++
++	tcp_hdr(buff)->fin = tcp_hdr(skb)->fin;
++	tcp_hdr(skb)->fin = 0;
++
++	/* We absolutly need to call skb_set_owner_r before refreshing the
++	 * truesize of buff, otherwise the moved data will account twice.
++	 */
++	skb_set_owner_r(buff, sk);
++	nlen = skb->len - len - nsize;
++	buff->truesize += nlen;
++	skb->truesize -= nlen;
++
++	/* Correct the sequence numbers. */
++	TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len;
++	TCP_SKB_CB(buff)->end_seq = TCP_SKB_CB(skb)->end_seq;
++	TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(buff)->seq;
++
++	skb_split(skb, buff, len);
++
++	__skb_queue_after(&sk->sk_receive_queue, skb, buff);
++
++	return 0;
++}
++
++/* @return: 0  everything is fine. Just continue processing
++ *	    1  subflow is broken stop everything
++ *	    -1 this packet was broken - continue with the next one.
++ */
++static int mptcp_prevalidate_skb(struct sock *sk, struct sk_buff *skb)
++{
++	struct tcp_sock *tp = tcp_sk(sk);
++
++	/* If we are in infinite mode, the subflow-fin is in fact a data-fin. */
++	if (!skb->len && tcp_hdr(skb)->fin && !mptcp_is_data_fin(skb) &&
++	    !tp->mpcb->infinite_mapping_rcv) {
++		/* Remove a pure subflow-fin from the queue and increase
++		 * copied_seq.
++		 */
++		tp->copied_seq = TCP_SKB_CB(skb)->end_seq;
++		__skb_unlink(skb, &sk->sk_receive_queue);
++		__kfree_skb(skb);
++		return -1;
++	}
++
++	/* If we are not yet fully established and do not know the mapping for
++	 * this segment, this path has to fallback to infinite or be torn down.
++	 */
++	if (!tp->mptcp->fully_established && !mptcp_is_data_seq(skb) &&
++	    !tp->mptcp->mapping_present && !tp->mpcb->infinite_mapping_rcv) {
++		pr_err("%s %#x will fallback - pi %d from %pS, seq %u\n",
++		       __func__, tp->mpcb->mptcp_loc_token,
++		       tp->mptcp->path_index, __builtin_return_address(0),
++		       TCP_SKB_CB(skb)->seq);
++
++		if (!is_master_tp(tp)) {
++			mptcp_send_reset(sk);
++			return 1;
++		}
++
++		tp->mpcb->infinite_mapping_snd = 1;
++		tp->mpcb->infinite_mapping_rcv = 1;
++		/* We do a seamless fallback and should not send a inf.mapping. */
++		tp->mpcb->send_infinite_mapping = 0;
++		tp->mptcp->fully_established = 1;
++	}
++
++	/* Receiver-side becomes fully established when a whole rcv-window has
++	 * been received without the need to fallback due to the previous
++	 * condition.
++	 */
++	if (!tp->mptcp->fully_established) {
++		tp->mptcp->init_rcv_wnd -= skb->len;
++		if (tp->mptcp->init_rcv_wnd < 0)
++			mptcp_become_fully_estab(sk);
++	}
++
++	return 0;
++}
++
++/* @return: 0  everything is fine. Just continue processing
++ *	    1  subflow is broken stop everything
++ *	    -1 this packet was broken - continue with the next one.
++ */
++static int mptcp_detect_mapping(struct sock *sk, struct sk_buff *skb)
++{
++	struct tcp_sock *tp = tcp_sk(sk), *meta_tp = mptcp_meta_tp(tp);
++	struct mptcp_cb *mpcb = tp->mpcb;
++	struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
++	u32 *ptr;
++	u32 data_seq, sub_seq, data_len, tcp_end_seq;
++
++	/* If we are in infinite-mapping-mode, the subflow is guaranteed to be
++	 * in-order at the data-level. Thus data-seq-numbers can be inferred
++	 * from what is expected at the data-level.
++	 */
++	if (mpcb->infinite_mapping_rcv) {
++		tp->mptcp->map_data_seq = mptcp_get_rcv_nxt_64(meta_tp);
++		tp->mptcp->map_subseq = tcb->seq;
++		tp->mptcp->map_data_len = skb->len;
++		tp->mptcp->map_data_fin = tcp_hdr(skb)->fin;
++		tp->mptcp->mapping_present = 1;
++		return 0;
++	}
++
++	/* No mapping here? Exit - it is either already set or still on its way */
++	if (!mptcp_is_data_seq(skb)) {
++		/* Too many packets without a mapping - this subflow is broken */
++		if (!tp->mptcp->mapping_present &&
++		    tp->rcv_nxt - tp->copied_seq > 65536) {
++			mptcp_send_reset(sk);
++			return 1;
++		}
++
++		return 0;
++	}
++
++	ptr = mptcp_skb_set_data_seq(skb, &data_seq, mpcb);
++	ptr++;
++	sub_seq = get_unaligned_be32(ptr) + tp->mptcp->rcv_isn;
++	ptr++;
++	data_len = get_unaligned_be16(ptr);
++
++	/* If it's an empty skb with DATA_FIN, sub_seq must get fixed.
++	 * The draft sets it to 0, but we really would like to have the
++	 * real value, to have an easy handling afterwards here in this
++	 * function.
++	 */
++	if (mptcp_is_data_fin(skb) && skb->len == 0)
++		sub_seq = TCP_SKB_CB(skb)->seq;
++
++	/* If there is already a mapping - we check if it maps with the current
++	 * one. If not - we reset.
++	 */
++	if (tp->mptcp->mapping_present &&
++	    (data_seq != (u32)tp->mptcp->map_data_seq ||
++	     sub_seq != tp->mptcp->map_subseq ||
++	     data_len != tp->mptcp->map_data_len + tp->mptcp->map_data_fin ||
++	     mptcp_is_data_fin(skb) != tp->mptcp->map_data_fin)) {
++		/* Mapping in packet is different from what we want */
++		pr_err("%s Mappings do not match!\n", __func__);
++		pr_err("%s dseq %u mdseq %u, sseq %u msseq %u dlen %u mdlen %u dfin %d mdfin %d\n",
++		       __func__, data_seq, (u32)tp->mptcp->map_data_seq,
++		       sub_seq, tp->mptcp->map_subseq, data_len,
++		       tp->mptcp->map_data_len, mptcp_is_data_fin(skb),
++		       tp->mptcp->map_data_fin);
++		mptcp_send_reset(sk);
++		return 1;
++	}
++
++	/* If the previous check was good, the current mapping is valid and we exit. */
++	if (tp->mptcp->mapping_present)
++		return 0;
++
++	/* Mapping not yet set on this subflow - we set it here! */
++
++	if (!data_len) {
++		mpcb->infinite_mapping_rcv = 1;
++		tp->mptcp->fully_established = 1;
++		/* We need to repeat mp_fail's until the sender felt
++		 * back to infinite-mapping - here we stop repeating it.
++		 */
++		tp->mptcp->send_mp_fail = 0;
++
++		/* We have to fixup data_len - it must be the same as skb->len */
++		data_len = skb->len + (mptcp_is_data_fin(skb) ? 1 : 0);
++		sub_seq = tcb->seq;
++
++		/* TODO kill all other subflows than this one */
++		/* data_seq and so on are set correctly */
++
++		/* At this point, the meta-ofo-queue has to be emptied,
++		 * as the following data is guaranteed to be in-order at
++		 * the data and subflow-level
++		 */
++		mptcp_purge_ofo_queue(meta_tp);
++	}
++
++	/* We are sending mp-fail's and thus are in fallback mode.
++	 * Ignore packets which do not announce the fallback and still
++	 * want to provide a mapping.
++	 */
++	if (tp->mptcp->send_mp_fail) {
++		tp->copied_seq = TCP_SKB_CB(skb)->end_seq;
++		__skb_unlink(skb, &sk->sk_receive_queue);
++		__kfree_skb(skb);
++		return -1;
++	}
++
++	/* FIN increased the mapping-length by 1 */
++	if (mptcp_is_data_fin(skb))
++		data_len--;
++
++	/* Subflow-sequences of packet must be
++	 * (at least partially) be part of the DSS-mapping's
++	 * subflow-sequence-space.
++	 *
++	 * Basically the mapping is not valid, if either of the
++	 * following conditions is true:
++	 *
++	 * 1. It's not a data_fin and
++	 *    MPTCP-sub_seq >= TCP-end_seq
++	 *
++	 * 2. It's a data_fin and TCP-end_seq > TCP-seq and
++	 *    MPTCP-sub_seq >= TCP-end_seq
++	 *
++	 * The previous two can be merged into:
++	 *    TCP-end_seq > TCP-seq and MPTCP-sub_seq >= TCP-end_seq
++	 *    Because if it's not a data-fin, TCP-end_seq > TCP-seq
++	 *
++	 * 3. It's a data_fin and skb->len == 0 and
++	 *    MPTCP-sub_seq > TCP-end_seq
++	 *
++	 * 4. It's not a data_fin and TCP-end_seq > TCP-seq and
++	 *    MPTCP-sub_seq + MPTCP-data_len <= TCP-seq
++	 *
++	 * 5. MPTCP-sub_seq is prior to what we already copied (copied_seq)
++	 */
++
++	/* subflow-fin is not part of the mapping - ignore it here ! */
++	tcp_end_seq = tcb->end_seq - tcp_hdr(skb)->fin;
++	if ((!before(sub_seq, tcb->end_seq) && after(tcp_end_seq, tcb->seq)) ||
++	    (mptcp_is_data_fin(skb) && skb->len == 0 && after(sub_seq, tcb->end_seq)) ||
++	    (!after(sub_seq + data_len, tcb->seq) && after(tcp_end_seq, tcb->seq)) ||
++	    before(sub_seq, tp->copied_seq)) {
++		/* Subflow-sequences of packet is different from what is in the
++		 * packet's dss-mapping. The peer is misbehaving - reset
++		 */
++		pr_err("%s Packet's mapping does not map to the DSS sub_seq %u "
++		       "end_seq %u, tcp_end_seq %u seq %u dfin %u len %u data_len %u"
++		       "copied_seq %u\n", __func__, sub_seq, tcb->end_seq, tcp_end_seq, tcb->seq, mptcp_is_data_fin(skb),
++		       skb->len, data_len, tp->copied_seq);
++		mptcp_send_reset(sk);
++		return 1;
++	}
++
++	/* Does the DSS had 64-bit seqnum's ? */
++	if (!(tcb->mptcp_flags & MPTCPHDR_SEQ64_SET)) {
++		/* Wrapped around? */
++		if (unlikely(after(data_seq, meta_tp->rcv_nxt) && data_seq < meta_tp->rcv_nxt)) {
++			tp->mptcp->map_data_seq = mptcp_get_data_seq_64(mpcb, !mpcb->rcv_hiseq_index, data_seq);
++		} else {
++			/* Else, access the default high-order bits */
++			tp->mptcp->map_data_seq = mptcp_get_data_seq_64(mpcb, mpcb->rcv_hiseq_index, data_seq);
++		}
++	} else {
++		tp->mptcp->map_data_seq = mptcp_get_data_seq_64(mpcb, (tcb->mptcp_flags & MPTCPHDR_SEQ64_INDEX) ? 1 : 0, data_seq);
++
++		if (unlikely(tcb->mptcp_flags & MPTCPHDR_SEQ64_OFO)) {
++			/* We make sure that the data_seq is invalid.
++			 * It will be dropped later.
++			 */
++			tp->mptcp->map_data_seq += 0xFFFFFFFF;
++			tp->mptcp->map_data_seq += 0xFFFFFFFF;
++		}
++	}
++
++	tp->mptcp->map_data_len = data_len;
++	tp->mptcp->map_subseq = sub_seq;
++	tp->mptcp->map_data_fin = mptcp_is_data_fin(skb) ? 1 : 0;
++	tp->mptcp->mapping_present = 1;
++
++	return 0;
++}
++
++/* Similar to tcp_sequence(...) */
++static inline bool mptcp_sequence(const struct tcp_sock *meta_tp,
++				 u64 data_seq, u64 end_data_seq)
++{
++	const struct mptcp_cb *mpcb = meta_tp->mpcb;
++	u64 rcv_wup64;
++
++	/* Wrap-around? */
++	if (meta_tp->rcv_wup > meta_tp->rcv_nxt) {
++		rcv_wup64 = ((u64)(mpcb->rcv_high_order[mpcb->rcv_hiseq_index] - 1) << 32) |
++				meta_tp->rcv_wup;
++	} else {
++		rcv_wup64 = mptcp_get_data_seq_64(mpcb, mpcb->rcv_hiseq_index,
++						  meta_tp->rcv_wup);
++	}
++
++	return	!before64(end_data_seq, rcv_wup64) &&
++		!after64(data_seq, mptcp_get_rcv_nxt_64(meta_tp) + tcp_receive_window(meta_tp));
++}
++
++/* @return: 0  everything is fine. Just continue processing
++ *	    -1 this packet was broken - continue with the next one.
++ */
++static int mptcp_validate_mapping(struct sock *sk, struct sk_buff *skb)
++{
++	struct tcp_sock *tp = tcp_sk(sk);
++	struct sk_buff *tmp, *tmp1;
++	u32 tcp_end_seq;
++
++	if (!tp->mptcp->mapping_present)
++		return 0;
++
++	/* either, the new skb gave us the mapping and the first segment
++	 * in the sub-rcv-queue has to be trimmed ...
++	 */
++	tmp = skb_peek(&sk->sk_receive_queue);
++	if (before(TCP_SKB_CB(tmp)->seq, tp->mptcp->map_subseq) &&
++	    after(TCP_SKB_CB(tmp)->end_seq, tp->mptcp->map_subseq))
++		mptcp_skb_trim_head(tmp, sk, tp->mptcp->map_subseq);
++
++	/* ... or the new skb (tail) has to be split at the end. */
++	tcp_end_seq = TCP_SKB_CB(skb)->end_seq - (tcp_hdr(skb)->fin ? 1 : 0);
++	if (after(tcp_end_seq, tp->mptcp->map_subseq + tp->mptcp->map_data_len)) {
++		u32 seq = tp->mptcp->map_subseq + tp->mptcp->map_data_len;
++		if (mptcp_skb_split_tail(skb, sk, seq)) { /* Allocation failed */
++			/* TODO : maybe handle this here better.
++			 * We now just force meta-retransmission.
++			 */
++			tp->copied_seq = TCP_SKB_CB(skb)->end_seq;
++			__skb_unlink(skb, &sk->sk_receive_queue);
++			__kfree_skb(skb);
++			return -1;
++		}
++	}
++
++	/* Now, remove old sk_buff's from the receive-queue.
++	 * This may happen if the mapping has been lost for these segments and
++	 * the next mapping has already been received.
++	 */
++	if (before(TCP_SKB_CB(skb_peek(&sk->sk_receive_queue))->seq, tp->mptcp->map_subseq)) {
++		skb_queue_walk_safe(&sk->sk_receive_queue, tmp1, tmp) {
++			if (!before(TCP_SKB_CB(tmp1)->seq, tp->mptcp->map_subseq))
++				break;
++
++			tp->copied_seq = TCP_SKB_CB(tmp1)->end_seq;
++			__skb_unlink(tmp1, &sk->sk_receive_queue);
++
++			/* Impossible that we could free skb here, because his
++			 * mapping is known to be valid from previous checks
++			 */
++			__kfree_skb(tmp1);
++		}
++	}
++
++	return 0;
++}
++
++/* @return: 0  everything is fine. Just continue processing
++ *	    1  subflow is broken stop everything
++ *	    -1 this mapping has been put in the meta-receive-queue
++ *	    -2 this mapping has been eaten by the application
++ */
++static int mptcp_queue_skb(struct sock *sk)
++{
++	struct tcp_sock *tp = tcp_sk(sk), *meta_tp = mptcp_meta_tp(tp);
++	struct sock *meta_sk = mptcp_meta_sk(sk);
++	struct mptcp_cb *mpcb = tp->mpcb;
++	struct sk_buff *tmp, *tmp1;
++	u64 rcv_nxt64 = mptcp_get_rcv_nxt_64(meta_tp);
++	bool data_queued = false;
++
++	/* Have we not yet received the full mapping? */
++	if (!tp->mptcp->mapping_present ||
++	    before(tp->rcv_nxt, tp->mptcp->map_subseq + tp->mptcp->map_data_len))
++		return 0;
++
++	/* Is this an overlapping mapping? rcv_nxt >= end_data_seq
++	 * OR
++	 * This mapping is out of window
++	 */
++	if (!before64(rcv_nxt64, tp->mptcp->map_data_seq + tp->mptcp->map_data_len + tp->mptcp->map_data_fin) ||
++	    !mptcp_sequence(meta_tp, tp->mptcp->map_data_seq,
++			    tp->mptcp->map_data_seq + tp->mptcp->map_data_len + tp->mptcp->map_data_fin)) {
++		skb_queue_walk_safe(&sk->sk_receive_queue, tmp1, tmp) {
++			__skb_unlink(tmp1, &sk->sk_receive_queue);
++			tp->copied_seq = TCP_SKB_CB(tmp1)->end_seq;
++			__kfree_skb(tmp1);
++
++			if (!skb_queue_empty(&sk->sk_receive_queue) &&
++			    !before(TCP_SKB_CB(tmp)->seq,
++				    tp->mptcp->map_subseq + tp->mptcp->map_data_len))
++				break;
++		}
++
++		mptcp_reset_mapping(tp);
++
++		return -1;
++	}
++
++	/* Record it, because we want to send our data_fin on the same path */
++	if (tp->mptcp->map_data_fin) {
++		mpcb->dfin_path_index = tp->mptcp->path_index;
++		mpcb->dfin_combined = !!(sk->sk_shutdown & RCV_SHUTDOWN);
++	}
++
++	/* Verify the checksum */
++	if (mpcb->dss_csum && !mpcb->infinite_mapping_rcv) {
++		int ret = mptcp_verif_dss_csum(sk);
++
++		if (ret <= 0) {
++			mptcp_reset_mapping(tp);
++			return 1;
++		}
++	}
++
++	if (before64(rcv_nxt64, tp->mptcp->map_data_seq)) {
++		/* Seg's have to go to the meta-ofo-queue */
++		skb_queue_walk_safe(&sk->sk_receive_queue, tmp1, tmp) {
++			tp->copied_seq = TCP_SKB_CB(tmp1)->end_seq;
++			mptcp_prepare_skb(tmp1, sk);
++			__skb_unlink(tmp1, &sk->sk_receive_queue);
++			/* MUST be done here, because fragstolen may be true later.
++			 * Then, kfree_skb_partial will not account the memory.
++			 */
++			skb_orphan(tmp1);
++
++			if (!mpcb->in_time_wait) /* In time-wait, do not receive data */
++				mptcp_add_meta_ofo_queue(meta_sk, tmp1, sk);
++			else
++				__kfree_skb(tmp1);
++
++			if (!skb_queue_empty(&sk->sk_receive_queue) &&
++			    !before(TCP_SKB_CB(tmp)->seq,
++				    tp->mptcp->map_subseq + tp->mptcp->map_data_len))
++				break;
++		}
++		tcp_enter_quickack_mode(sk);
++	} else {
++		/* Ready for the meta-rcv-queue */
++		skb_queue_walk_safe(&sk->sk_receive_queue, tmp1, tmp) {
++			int eaten = 0;
++			const bool copied_early = false;
++			bool fragstolen = false;
++			u32 old_rcv_nxt = meta_tp->rcv_nxt;
++
++			tp->copied_seq = TCP_SKB_CB(tmp1)->end_seq;
++			mptcp_prepare_skb(tmp1, sk);
++			__skb_unlink(tmp1, &sk->sk_receive_queue);
++			/* MUST be done here, because fragstolen may be true.
++			 * Then, kfree_skb_partial will not account the memory.
++			 */
++			skb_orphan(tmp1);
++
++			/* This segment has already been received */
++			if (!after(TCP_SKB_CB(tmp1)->end_seq, meta_tp->rcv_nxt)) {
++				__kfree_skb(tmp1);
++				goto next;
++			}
++
++#ifdef CONFIG_NET_DMA
++			if (TCP_SKB_CB(tmp1)->seq == meta_tp->rcv_nxt  &&
++			    meta_tp->ucopy.task == current &&
++			    meta_tp->copied_seq == meta_tp->rcv_nxt &&
++			    tmp1->len <= meta_tp->ucopy.len &&
++			    sock_owned_by_user(meta_sk) &&
++			    tcp_dma_try_early_copy(meta_sk, tmp1, 0)) {
++				copied_early = true;
++				eaten = 1;
++			}
++#endif
++
++			/* Is direct copy possible ? */
++			if (TCP_SKB_CB(tmp1)->seq == meta_tp->rcv_nxt &&
++			    meta_tp->ucopy.task == current &&
++			    meta_tp->copied_seq == meta_tp->rcv_nxt &&
++			    meta_tp->ucopy.len && sock_owned_by_user(meta_sk) &&
++			    !copied_early)
++				eaten = mptcp_direct_copy(tmp1, meta_sk);
++
++			if (mpcb->in_time_wait) /* In time-wait, do not receive data */
++				eaten = 1;
++
++			if (!eaten)
++				eaten = tcp_queue_rcv(meta_sk, tmp1, 0, &fragstolen);
++
++			meta_tp->rcv_nxt = TCP_SKB_CB(tmp1)->end_seq;
++			mptcp_check_rcvseq_wrap(meta_tp, old_rcv_nxt);
++
++#ifdef CONFIG_NET_DMA
++			if (copied_early)
++				meta_tp->cleanup_rbuf(meta_sk, tmp1->len);
++#endif
++
++			if (tcp_hdr(tmp1)->fin && !mpcb->in_time_wait)
++				mptcp_fin(meta_sk);
++
++			/* Check if this fills a gap in the ofo queue */
++			if (!skb_queue_empty(&meta_tp->out_of_order_queue))
++				mptcp_ofo_queue(meta_sk);
++
++#ifdef CONFIG_NET_DMA
++			if (copied_early)
++				__skb_queue_tail(&meta_sk->sk_async_wait_queue,
++						 tmp1);
++			else
++#endif
++			if (eaten)
++				kfree_skb_partial(tmp1, fragstolen);
++
++			data_queued = true;
++next:
++			if (!skb_queue_empty(&sk->sk_receive_queue) &&
++			    !before(TCP_SKB_CB(tmp)->seq,
++				    tp->mptcp->map_subseq + tp->mptcp->map_data_len))
++				break;
++		}
++	}
++
++	inet_csk(meta_sk)->icsk_ack.lrcvtime = tcp_time_stamp;
++	mptcp_reset_mapping(tp);
++
++	return data_queued ? -1 : -2;
++}
++
++void mptcp_data_ready(struct sock *sk)
++{
++	struct sock *meta_sk = mptcp_meta_sk(sk);
++	struct sk_buff *skb, *tmp;
++	int queued = 0;
++
++	/* restart before the check, because mptcp_fin might have changed the
++	 * state.
++	 */
++restart:
++	/* If the meta cannot receive data, there is no point in pushing data.
++	 * If we are in time-wait, we may still be waiting for the final FIN.
++	 * So, we should proceed with the processing.
++	 */
++	if (!mptcp_sk_can_recv(meta_sk) && !tcp_sk(sk)->mpcb->in_time_wait) {
++		skb_queue_purge(&sk->sk_receive_queue);
++		tcp_sk(sk)->copied_seq = tcp_sk(sk)->rcv_nxt;
++		goto exit;
++	}
++
++	/* Iterate over all segments, detect their mapping (if we don't have
++	 * one yet), validate them and push everything one level higher.
++	 */
++	skb_queue_walk_safe(&sk->sk_receive_queue, skb, tmp) {
++		int ret;
++		/* Pre-validation - e.g., early fallback */
++		ret = mptcp_prevalidate_skb(sk, skb);
++		if (ret < 0)
++			goto restart;
++		else if (ret > 0)
++			break;
++
++		/* Set the current mapping */
++		ret = mptcp_detect_mapping(sk, skb);
++		if (ret < 0)
++			goto restart;
++		else if (ret > 0)
++			break;
++
++		/* Validation */
++		if (mptcp_validate_mapping(sk, skb) < 0)
++			goto restart;
++
++		/* Push a level higher */
++		ret = mptcp_queue_skb(sk);
++		if (ret < 0) {
++			if (ret == -1)
++				queued = ret;
++			goto restart;
++		} else if (ret == 0) {
++			continue;
++		} else { /* ret == 1 */
++			break;
++		}
++	}
++
++exit:
++	if (tcp_sk(sk)->close_it) {
++		tcp_send_ack(sk);
++		tcp_sk(sk)->ops->time_wait(sk, TCP_TIME_WAIT, 0);
++	}
++
++	if (queued == -1 && !sock_flag(meta_sk, SOCK_DEAD))
++		meta_sk->sk_data_ready(meta_sk);
++}
++
++
++int mptcp_check_req(struct sk_buff *skb, struct net *net)
++{
++	const struct tcphdr *th = tcp_hdr(skb);
++	struct sock *meta_sk = NULL;
++
++	/* MPTCP structures not initialized */
++	if (mptcp_init_failed)
++		return 0;
++
++	if (skb->protocol == htons(ETH_P_IP))
++		meta_sk = mptcp_v4_search_req(th->source, ip_hdr(skb)->saddr,
++					      ip_hdr(skb)->daddr, net);
++#if IS_ENABLED(CONFIG_IPV6)
++	else /* IPv6 */
++		meta_sk = mptcp_v6_search_req(th->source, &ipv6_hdr(skb)->saddr,
++					      &ipv6_hdr(skb)->daddr, net);
++#endif /* CONFIG_IPV6 */
++
++	if (!meta_sk)
++		return 0;
++
++	TCP_SKB_CB(skb)->mptcp_flags |= MPTCPHDR_JOIN;
++
++	bh_lock_sock_nested(meta_sk);
++	if (sock_owned_by_user(meta_sk)) {
++		skb->sk = meta_sk;
++		if (unlikely(sk_add_backlog(meta_sk, skb,
++					    meta_sk->sk_rcvbuf + meta_sk->sk_sndbuf))) {
++			bh_unlock_sock(meta_sk);
++			NET_INC_STATS_BH(net, LINUX_MIB_TCPBACKLOGDROP);
++			sock_put(meta_sk); /* Taken by mptcp_search_req */
++			kfree_skb(skb);
++			return 1;
++		}
++	} else if (skb->protocol == htons(ETH_P_IP)) {
++		tcp_v4_do_rcv(meta_sk, skb);
++#if IS_ENABLED(CONFIG_IPV6)
++	} else { /* IPv6 */
++		tcp_v6_do_rcv(meta_sk, skb);
++#endif /* CONFIG_IPV6 */
++	}
++	bh_unlock_sock(meta_sk);
++	sock_put(meta_sk); /* Taken by mptcp_vX_search_req */
++	return 1;
++}
++
++struct mp_join *mptcp_find_join(const struct sk_buff *skb)
++{
++	const struct tcphdr *th = tcp_hdr(skb);
++	unsigned char *ptr;
++	int length = (th->doff * 4) - sizeof(struct tcphdr);
++
++	/* Jump through the options to check whether JOIN is there */
++	ptr = (unsigned char *)(th + 1);
++	while (length > 0) {
++		int opcode = *ptr++;
++		int opsize;
++
++		switch (opcode) {
++		case TCPOPT_EOL:
++			return NULL;
++		case TCPOPT_NOP:	/* Ref: RFC 793 section 3.1 */
++			length--;
++			continue;
++		default:
++			opsize = *ptr++;
++			if (opsize < 2)	/* "silly options" */
++				return NULL;
++			if (opsize > length)
++				return NULL;  /* don't parse partial options */
++			if (opcode == TCPOPT_MPTCP &&
++			    ((struct mptcp_option *)(ptr - 2))->sub == MPTCP_SUB_JOIN) {
++				return (struct mp_join *)(ptr - 2);
++			}
++			ptr += opsize - 2;
++			length -= opsize;
++		}
++	}
++	return NULL;
++}
++
++int mptcp_lookup_join(struct sk_buff *skb, struct inet_timewait_sock *tw)
++{
++	const struct mptcp_cb *mpcb;
++	struct sock *meta_sk;
++	u32 token;
++	bool meta_v4;
++	struct mp_join *join_opt = mptcp_find_join(skb);
++	if (!join_opt)
++		return 0;
++
++	/* MPTCP structures were not initialized, so return error */
++	if (mptcp_init_failed)
++		return -1;
++
++	token = join_opt->u.syn.token;
++	meta_sk = mptcp_hash_find(dev_net(skb_dst(skb)->dev), token);
++	if (!meta_sk) {
++		mptcp_debug("%s:mpcb not found:%x\n", __func__, token);
++		return -1;
++	}
++
++	meta_v4 = meta_sk->sk_family == AF_INET;
++	if (meta_v4) {
++		if (skb->protocol == htons(ETH_P_IPV6)) {
++			mptcp_debug("SYN+MP_JOIN with IPV6 address on pure IPV4 meta\n");
++			sock_put(meta_sk); /* Taken by mptcp_hash_find */
++			return -1;
++		}
++	} else if (skb->protocol == htons(ETH_P_IP) &&
++		   inet6_sk(meta_sk)->ipv6only) {
++		mptcp_debug("SYN+MP_JOIN with IPV4 address on IPV6_V6ONLY meta\n");
++		sock_put(meta_sk); /* Taken by mptcp_hash_find */
++		return -1;
++	}
++
++	mpcb = tcp_sk(meta_sk)->mpcb;
++	if (mpcb->infinite_mapping_rcv || mpcb->send_infinite_mapping) {
++		/* We are in fallback-mode on the reception-side -
++		 * no new subflows!
++		 */
++		sock_put(meta_sk); /* Taken by mptcp_hash_find */
++		return -1;
++	}
++
++	/* Coming from time-wait-sock processing in tcp_v4_rcv.
++	 * We have to deschedule it before continuing, because otherwise
++	 * mptcp_v4_do_rcv will hit again on it inside tcp_v4_hnd_req.
++	 */
++	if (tw) {
++		inet_twsk_deschedule(tw, &tcp_death_row);
++		inet_twsk_put(tw);
++	}
++
++	TCP_SKB_CB(skb)->mptcp_flags |= MPTCPHDR_JOIN;
++	/* OK, this is a new syn/join, let's create a new open request and
++	 * send syn+ack
++	 */
++	bh_lock_sock_nested(meta_sk);
++	if (sock_owned_by_user(meta_sk)) {
++		skb->sk = meta_sk;
++		if (unlikely(sk_add_backlog(meta_sk, skb,
++					    meta_sk->sk_rcvbuf + meta_sk->sk_sndbuf))) {
++			bh_unlock_sock(meta_sk);
++			NET_INC_STATS_BH(sock_net(meta_sk),
++					 LINUX_MIB_TCPBACKLOGDROP);
++			sock_put(meta_sk); /* Taken by mptcp_hash_find */
++			kfree_skb(skb);
++			return 1;
++		}
++	} else if (skb->protocol == htons(ETH_P_IP)) {
++		tcp_v4_do_rcv(meta_sk, skb);
++#if IS_ENABLED(CONFIG_IPV6)
++	} else {
++		tcp_v6_do_rcv(meta_sk, skb);
++#endif /* CONFIG_IPV6 */
++	}
++	bh_unlock_sock(meta_sk);
++	sock_put(meta_sk); /* Taken by mptcp_hash_find */
++	return 1;
++}
++
++int mptcp_do_join_short(struct sk_buff *skb,
++			const struct mptcp_options_received *mopt,
++			struct net *net)
++{
++	struct sock *meta_sk;
++	u32 token;
++	bool meta_v4;
++
++	token = mopt->mptcp_rem_token;
++	meta_sk = mptcp_hash_find(net, token);
++	if (!meta_sk) {
++		mptcp_debug("%s:mpcb not found:%x\n", __func__, token);
++		return -1;
++	}
++
++	meta_v4 = meta_sk->sk_family == AF_INET;
++	if (meta_v4) {
++		if (skb->protocol == htons(ETH_P_IPV6)) {
++			mptcp_debug("SYN+MP_JOIN with IPV6 address on pure IPV4 meta\n");
++			sock_put(meta_sk); /* Taken by mptcp_hash_find */
++			return -1;
++		}
++	} else if (skb->protocol == htons(ETH_P_IP) &&
++		   inet6_sk(meta_sk)->ipv6only) {
++		mptcp_debug("SYN+MP_JOIN with IPV4 address on IPV6_V6ONLY meta\n");
++		sock_put(meta_sk); /* Taken by mptcp_hash_find */
++		return -1;
++	}
++
++	TCP_SKB_CB(skb)->mptcp_flags |= MPTCPHDR_JOIN;
++
++	/* OK, this is a new syn/join, let's create a new open request and
++	 * send syn+ack
++	 */
++	bh_lock_sock(meta_sk);
++
++	/* This check is also done in mptcp_vX_do_rcv. But, there we cannot
++	 * call tcp_vX_send_reset, because we hold already two socket-locks.
++	 * (the listener and the meta from above)
++	 *
++	 * And the send-reset will try to take yet another one (ip_send_reply).
++	 * Thus, we propagate the reset up to tcp_rcv_state_process.
++	 */
++	if (tcp_sk(meta_sk)->mpcb->infinite_mapping_rcv ||
++	    tcp_sk(meta_sk)->mpcb->send_infinite_mapping ||
++	    meta_sk->sk_state == TCP_CLOSE || !tcp_sk(meta_sk)->inside_tk_table) {
++		bh_unlock_sock(meta_sk);
++		sock_put(meta_sk); /* Taken by mptcp_hash_find */
++		return -1;
++	}
++
++	if (sock_owned_by_user(meta_sk)) {
++		skb->sk = meta_sk;
++		if (unlikely(sk_add_backlog(meta_sk, skb,
++					    meta_sk->sk_rcvbuf + meta_sk->sk_sndbuf)))
++			NET_INC_STATS_BH(net, LINUX_MIB_TCPBACKLOGDROP);
++		else
++			/* Must make sure that upper layers won't free the
++			 * skb if it is added to the backlog-queue.
++			 */
++			skb_get(skb);
++	} else {
++		/* mptcp_v4_do_rcv tries to free the skb - we prevent this, as
++		 * the skb will finally be freed by tcp_v4_do_rcv (where we are
++		 * coming from)
++		 */
++		skb_get(skb);
++		if (skb->protocol == htons(ETH_P_IP)) {
++			tcp_v4_do_rcv(meta_sk, skb);
++#if IS_ENABLED(CONFIG_IPV6)
++		} else { /* IPv6 */
++			tcp_v6_do_rcv(meta_sk, skb);
++#endif /* CONFIG_IPV6 */
++		}
++	}
++
++	bh_unlock_sock(meta_sk);
++	sock_put(meta_sk); /* Taken by mptcp_hash_find */
++	return 0;
++}
++
++/**
++ * Equivalent of tcp_fin() for MPTCP
++ * Can be called only when the FIN is validly part
++ * of the data seqnum space. Not before when we get holes.
++ */
++void mptcp_fin(struct sock *meta_sk)
++{
++	struct sock *sk = NULL, *sk_it;
++	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
++	struct mptcp_cb *mpcb = meta_tp->mpcb;
++
++	mptcp_for_each_sk(mpcb, sk_it) {
++		if (tcp_sk(sk_it)->mptcp->path_index == mpcb->dfin_path_index) {
++			sk = sk_it;
++			break;
++		}
++	}
++
++	if (!sk || sk->sk_state == TCP_CLOSE)
++		sk = mptcp_select_ack_sock(meta_sk);
++
++	inet_csk_schedule_ack(sk);
++
++	meta_sk->sk_shutdown |= RCV_SHUTDOWN;
++	sock_set_flag(meta_sk, SOCK_DONE);
++
++	switch (meta_sk->sk_state) {
++	case TCP_SYN_RECV:
++	case TCP_ESTABLISHED:
++		/* Move to CLOSE_WAIT */
++		tcp_set_state(meta_sk, TCP_CLOSE_WAIT);
++		inet_csk(sk)->icsk_ack.pingpong = 1;
++		break;
++
++	case TCP_CLOSE_WAIT:
++	case TCP_CLOSING:
++		/* Received a retransmission of the FIN, do
++		 * nothing.
++		 */
++		break;
++	case TCP_LAST_ACK:
++		/* RFC793: Remain in the LAST-ACK state. */
++		break;
++
++	case TCP_FIN_WAIT1:
++		/* This case occurs when a simultaneous close
++		 * happens, we must ack the received FIN and
++		 * enter the CLOSING state.
++		 */
++		tcp_send_ack(sk);
++		tcp_set_state(meta_sk, TCP_CLOSING);
++		break;
++	case TCP_FIN_WAIT2:
++		/* Received a FIN -- send ACK and enter TIME_WAIT. */
++		tcp_send_ack(sk);
++		meta_tp->ops->time_wait(meta_sk, TCP_TIME_WAIT, 0);
++		break;
++	default:
++		/* Only TCP_LISTEN and TCP_CLOSE are left, in these
++		 * cases we should never reach this piece of code.
++		 */
++		pr_err("%s: Impossible, meta_sk->sk_state=%d\n", __func__,
++		       meta_sk->sk_state);
++		break;
++	}
++
++	/* It _is_ possible, that we have something out-of-order _after_ FIN.
++	 * Probably, we should reset in this case. For now drop them.
++	 */
++	mptcp_purge_ofo_queue(meta_tp);
++	sk_mem_reclaim(meta_sk);
++
++	if (!sock_flag(meta_sk, SOCK_DEAD)) {
++		meta_sk->sk_state_change(meta_sk);
++
++		/* Do not send POLL_HUP for half duplex close. */
++		if (meta_sk->sk_shutdown == SHUTDOWN_MASK ||
++		    meta_sk->sk_state == TCP_CLOSE)
++			sk_wake_async(meta_sk, SOCK_WAKE_WAITD, POLL_HUP);
++		else
++			sk_wake_async(meta_sk, SOCK_WAKE_WAITD, POLL_IN);
++	}
++
++	return;
++}
++
++static void mptcp_xmit_retransmit_queue(struct sock *meta_sk)
++{
++	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
++	struct sk_buff *skb;
++
++	if (!meta_tp->packets_out)
++		return;
++
++	tcp_for_write_queue(skb, meta_sk) {
++		if (skb == tcp_send_head(meta_sk))
++			break;
++
++		if (mptcp_retransmit_skb(meta_sk, skb))
++			return;
++
++		if (skb == tcp_write_queue_head(meta_sk))
++			inet_csk_reset_xmit_timer(meta_sk, ICSK_TIME_RETRANS,
++						  inet_csk(meta_sk)->icsk_rto,
++						  TCP_RTO_MAX);
++	}
++}
++
++/* Handle the DATA_ACK */
++static void mptcp_data_ack(struct sock *sk, const struct sk_buff *skb)
++{
++	struct sock *meta_sk = mptcp_meta_sk(sk);
++	struct tcp_sock *meta_tp = tcp_sk(meta_sk), *tp = tcp_sk(sk);
++	struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
++	u32 prior_snd_una = meta_tp->snd_una;
++	int prior_packets;
++	u32 nwin, data_ack, data_seq;
++	u16 data_len = 0;
++
++	/* A valid packet came in - subflow is operational again */
++	tp->pf = 0;
++
++	/* Even if there is no data-ack, we stop retransmitting.
++	 * Except if this is a SYN/ACK. Then it is just a retransmission
++	 */
++	if (tp->mptcp->pre_established && !tcp_hdr(skb)->syn) {
++		tp->mptcp->pre_established = 0;
++		sk_stop_timer(sk, &tp->mptcp->mptcp_ack_timer);
++	}
++
++	/* If we are in infinite mapping mode, rx_opt.data_ack has been
++	 * set by mptcp_clean_rtx_infinite.
++	 */
++	if (!(tcb->mptcp_flags & MPTCPHDR_ACK) && !tp->mpcb->infinite_mapping_snd)
++		goto exit;
++
++	data_ack = tp->mptcp->rx_opt.data_ack;
++
++	if (unlikely(!tp->mptcp->fully_established) &&
++	    tp->mptcp->snt_isn + 1 != TCP_SKB_CB(skb)->ack_seq)
++		/* As soon as a subflow-data-ack (not acking syn, thus snt_isn + 1)
++		 * includes a data-ack, we are fully established
++		 */
++		mptcp_become_fully_estab(sk);
++
++	/* Get the data_seq */
++	if (mptcp_is_data_seq(skb)) {
++		data_seq = tp->mptcp->rx_opt.data_seq;
++		data_len = tp->mptcp->rx_opt.data_len;
++	} else {
++		data_seq = meta_tp->snd_wl1;
++	}
++
++	/* If the ack is older than previous acks
++	 * then we can probably ignore it.
++	 */
++	if (before(data_ack, prior_snd_una))
++		goto exit;
++
++	/* If the ack includes data we haven't sent yet, discard
++	 * this segment (RFC793 Section 3.9).
++	 */
++	if (after(data_ack, meta_tp->snd_nxt))
++		goto exit;
++
++	/*** Now, update the window  - inspired by tcp_ack_update_window ***/
++	nwin = ntohs(tcp_hdr(skb)->window);
++
++	if (likely(!tcp_hdr(skb)->syn))
++		nwin <<= tp->rx_opt.snd_wscale;
++
++	if (tcp_may_update_window(meta_tp, data_ack, data_seq, nwin)) {
++		tcp_update_wl(meta_tp, data_seq);
++
++		/* Draft v09, Section 3.3.5:
++		 * [...] It should only update its local receive window values
++		 * when the largest sequence number allowed (i.e.  DATA_ACK +
++		 * receive window) increases. [...]
++		 */
++		if (meta_tp->snd_wnd != nwin &&
++		    !before(data_ack + nwin, tcp_wnd_end(meta_tp))) {
++			meta_tp->snd_wnd = nwin;
++
++			if (nwin > meta_tp->max_window)
++				meta_tp->max_window = nwin;
++		}
++	}
++	/*** Done, update the window ***/
++
++	/* We passed data and got it acked, remove any soft error
++	 * log. Something worked...
++	 */
++	sk->sk_err_soft = 0;
++	inet_csk(meta_sk)->icsk_probes_out = 0;
++	meta_tp->rcv_tstamp = tcp_time_stamp;
++	prior_packets = meta_tp->packets_out;
++	if (!prior_packets)
++		goto no_queue;
++
++	meta_tp->snd_una = data_ack;
++
++	mptcp_clean_rtx_queue(meta_sk, prior_snd_una);
++
++	/* We are in loss-state, and something got acked, retransmit the whole
++	 * queue now!
++	 */
++	if (inet_csk(meta_sk)->icsk_ca_state == TCP_CA_Loss &&
++	    after(data_ack, prior_snd_una)) {
++		mptcp_xmit_retransmit_queue(meta_sk);
++		inet_csk(meta_sk)->icsk_ca_state = TCP_CA_Open;
++	}
++
++	/* Simplified version of tcp_new_space, because the snd-buffer
++	 * is handled by all the subflows.
++	 */
++	if (sock_flag(meta_sk, SOCK_QUEUE_SHRUNK)) {
++		sock_reset_flag(meta_sk, SOCK_QUEUE_SHRUNK);
++		if (meta_sk->sk_socket &&
++		    test_bit(SOCK_NOSPACE, &meta_sk->sk_socket->flags))
++			meta_sk->sk_write_space(meta_sk);
++	}
++
++	if (meta_sk->sk_state != TCP_ESTABLISHED &&
++	    mptcp_rcv_state_process(meta_sk, sk, skb, data_seq, data_len))
++		return;
++
++exit:
++	mptcp_push_pending_frames(meta_sk);
++
++	return;
++
++no_queue:
++	if (tcp_send_head(meta_sk))
++		tcp_ack_probe(meta_sk);
++
++	mptcp_push_pending_frames(meta_sk);
++
++	return;
++}
++
++void mptcp_clean_rtx_infinite(const struct sk_buff *skb, struct sock *sk)
++{
++	struct tcp_sock *tp = tcp_sk(sk), *meta_tp = tcp_sk(mptcp_meta_sk(sk));
++
++	if (!tp->mpcb->infinite_mapping_snd)
++		return;
++
++	/* The difference between both write_seq's represents the offset between
++	 * data-sequence and subflow-sequence. As we are infinite, this must
++	 * match.
++	 *
++	 * Thus, from this difference we can infer the meta snd_una.
++	 */
++	tp->mptcp->rx_opt.data_ack = meta_tp->snd_nxt - tp->snd_nxt +
++				     tp->snd_una;
++
++	mptcp_data_ack(sk, skb);
++}
++
++/**** static functions used by mptcp_parse_options */
++
++static void mptcp_send_reset_rem_id(const struct mptcp_cb *mpcb, u8 rem_id)
++{
++	struct sock *sk_it, *tmpsk;
++
++	mptcp_for_each_sk_safe(mpcb, sk_it, tmpsk) {
++		if (tcp_sk(sk_it)->mptcp->rem_id == rem_id) {
++			mptcp_reinject_data(sk_it, 0);
++			sk_it->sk_err = ECONNRESET;
++			if (tcp_need_reset(sk_it->sk_state))
++				tcp_sk(sk_it)->ops->send_active_reset(sk_it,
++								      GFP_ATOMIC);
++			mptcp_sub_force_close(sk_it);
++		}
++	}
++}
++
++void mptcp_parse_options(const uint8_t *ptr, int opsize,
++			 struct mptcp_options_received *mopt,
++			 const struct sk_buff *skb)
++{
++	const struct mptcp_option *mp_opt = (struct mptcp_option *)ptr;
++
++	/* If the socket is mp-capable we would have a mopt. */
++	if (!mopt)
++		return;
++
++	switch (mp_opt->sub) {
++	case MPTCP_SUB_CAPABLE:
++	{
++		const struct mp_capable *mpcapable = (struct mp_capable *)ptr;
++
++		if (opsize != MPTCP_SUB_LEN_CAPABLE_SYN &&
++		    opsize != MPTCP_SUB_LEN_CAPABLE_ACK) {
++			mptcp_debug("%s: mp_capable: bad option size %d\n",
++				    __func__, opsize);
++			break;
++		}
++
++		if (!sysctl_mptcp_enabled)
++			break;
++
++		/* We only support MPTCP version 0 */
++		if (mpcapable->ver != 0)
++			break;
++
++		/* MPTCP-RFC 6824:
++		 * "If receiving a message with the 'B' flag set to 1, and this
++		 * is not understood, then this SYN MUST be silently ignored;
++		 */
++		if (mpcapable->b) {
++			mopt->drop_me = 1;
++			break;
++		}
++
++		/* MPTCP-RFC 6824:
++		 * "An implementation that only supports this method MUST set
++		 *  bit "H" to 1, and bits "C" through "G" to 0."
++		 */
++		if (!mpcapable->h)
++			break;
++
++		mopt->saw_mpc = 1;
++		mopt->dss_csum = sysctl_mptcp_checksum || mpcapable->a;
++
++		if (opsize >= MPTCP_SUB_LEN_CAPABLE_SYN)
++			mopt->mptcp_key = mpcapable->sender_key;
++
++		break;
++	}
++	case MPTCP_SUB_JOIN:
++	{
++		const struct mp_join *mpjoin = (struct mp_join *)ptr;
++
++		if (opsize != MPTCP_SUB_LEN_JOIN_SYN &&
++		    opsize != MPTCP_SUB_LEN_JOIN_SYNACK &&
++		    opsize != MPTCP_SUB_LEN_JOIN_ACK) {
++			mptcp_debug("%s: mp_join: bad option size %d\n",
++				    __func__, opsize);
++			break;
++		}
++
++		/* saw_mpc must be set, because in tcp_check_req we assume that
++		 * it is set to support falling back to reg. TCP if a rexmitted
++		 * SYN has no MP_CAPABLE or MP_JOIN
++		 */
++		switch (opsize) {
++		case MPTCP_SUB_LEN_JOIN_SYN:
++			mopt->is_mp_join = 1;
++			mopt->saw_mpc = 1;
++			mopt->low_prio = mpjoin->b;
++			mopt->rem_id = mpjoin->addr_id;
++			mopt->mptcp_rem_token = mpjoin->u.syn.token;
++			mopt->mptcp_recv_nonce = mpjoin->u.syn.nonce;
++			break;
++		case MPTCP_SUB_LEN_JOIN_SYNACK:
++			mopt->saw_mpc = 1;
++			mopt->low_prio = mpjoin->b;
++			mopt->rem_id = mpjoin->addr_id;
++			mopt->mptcp_recv_tmac = mpjoin->u.synack.mac;
++			mopt->mptcp_recv_nonce = mpjoin->u.synack.nonce;
++			break;
++		case MPTCP_SUB_LEN_JOIN_ACK:
++			mopt->saw_mpc = 1;
++			mopt->join_ack = 1;
++			memcpy(mopt->mptcp_recv_mac, mpjoin->u.ack.mac, 20);
++			break;
++		}
++		break;
++	}
++	case MPTCP_SUB_DSS:
++	{
++		const struct mp_dss *mdss = (struct mp_dss *)ptr;
++		struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
++
++		/* We check opsize for the csum and non-csum case. We do this,
++		 * because the draft says that the csum SHOULD be ignored if
++		 * it has not been negotiated in the MP_CAPABLE but still is
++		 * present in the data.
++		 *
++		 * It will get ignored later in mptcp_queue_skb.
++		 */
++		if (opsize != mptcp_sub_len_dss(mdss, 0) &&
++		    opsize != mptcp_sub_len_dss(mdss, 1)) {
++			mptcp_debug("%s: mp_dss: bad option size %d\n",
++				    __func__, opsize);
++			break;
++		}
++
++		ptr += 4;
++
++		if (mdss->A) {
++			tcb->mptcp_flags |= MPTCPHDR_ACK;
++
++			if (mdss->a) {
++				mopt->data_ack = (u32) get_unaligned_be64(ptr);
++				ptr += MPTCP_SUB_LEN_ACK_64;
++			} else {
++				mopt->data_ack = get_unaligned_be32(ptr);
++				ptr += MPTCP_SUB_LEN_ACK;
++			}
++		}
++
++		tcb->dss_off = (ptr - skb_transport_header(skb));
++
++		if (mdss->M) {
++			if (mdss->m) {
++				u64 data_seq64 = get_unaligned_be64(ptr);
++
++				tcb->mptcp_flags |= MPTCPHDR_SEQ64_SET;
++				mopt->data_seq = (u32) data_seq64;
++
++				ptr += 12; /* 64-bit dseq + subseq */
++			} else {
++				mopt->data_seq = get_unaligned_be32(ptr);
++				ptr += 8; /* 32-bit dseq + subseq */
++			}
++			mopt->data_len = get_unaligned_be16(ptr);
++
++			tcb->mptcp_flags |= MPTCPHDR_SEQ;
++
++			/* Is a check-sum present? */
++			if (opsize == mptcp_sub_len_dss(mdss, 1))
++				tcb->mptcp_flags |= MPTCPHDR_DSS_CSUM;
++
++			/* DATA_FIN only possible with DSS-mapping */
++			if (mdss->F)
++				tcb->mptcp_flags |= MPTCPHDR_FIN;
++		}
++
++		break;
++	}
++	case MPTCP_SUB_ADD_ADDR:
++	{
++#if IS_ENABLED(CONFIG_IPV6)
++		const struct mp_add_addr *mpadd = (struct mp_add_addr *)ptr;
++
++		if ((mpadd->ipver == 4 && opsize != MPTCP_SUB_LEN_ADD_ADDR4 &&
++		     opsize != MPTCP_SUB_LEN_ADD_ADDR4 + 2) ||
++		    (mpadd->ipver == 6 && opsize != MPTCP_SUB_LEN_ADD_ADDR6 &&
++		     opsize != MPTCP_SUB_LEN_ADD_ADDR6 + 2)) {
++#else
++		if (opsize != MPTCP_SUB_LEN_ADD_ADDR4 &&
++		    opsize != MPTCP_SUB_LEN_ADD_ADDR4 + 2) {
++#endif /* CONFIG_IPV6 */
++			mptcp_debug("%s: mp_add_addr: bad option size %d\n",
++				    __func__, opsize);
++			break;
++		}
++
++		/* We have to manually parse the options if we got two of them. */
++		if (mopt->saw_add_addr) {
++			mopt->more_add_addr = 1;
++			break;
++		}
++		mopt->saw_add_addr = 1;
++		mopt->add_addr_ptr = ptr;
++		break;
++	}
++	case MPTCP_SUB_REMOVE_ADDR:
++		if ((opsize - MPTCP_SUB_LEN_REMOVE_ADDR) < 0) {
++			mptcp_debug("%s: mp_remove_addr: bad option size %d\n",
++				    __func__, opsize);
++			break;
++		}
++
++		if (mopt->saw_rem_addr) {
++			mopt->more_rem_addr = 1;
++			break;
++		}
++		mopt->saw_rem_addr = 1;
++		mopt->rem_addr_ptr = ptr;
++		break;
++	case MPTCP_SUB_PRIO:
++	{
++		const struct mp_prio *mpprio = (struct mp_prio *)ptr;
++
++		if (opsize != MPTCP_SUB_LEN_PRIO &&
++		    opsize != MPTCP_SUB_LEN_PRIO_ADDR) {
++			mptcp_debug("%s: mp_prio: bad option size %d\n",
++				    __func__, opsize);
++			break;
++		}
++
++		mopt->saw_low_prio = 1;
++		mopt->low_prio = mpprio->b;
++
++		if (opsize == MPTCP_SUB_LEN_PRIO_ADDR) {
++			mopt->saw_low_prio = 2;
++			mopt->prio_addr_id = mpprio->addr_id;
++		}
++		break;
++	}
++	case MPTCP_SUB_FAIL:
++		if (opsize != MPTCP_SUB_LEN_FAIL) {
++			mptcp_debug("%s: mp_fail: bad option size %d\n",
++				    __func__, opsize);
++			break;
++		}
++		mopt->mp_fail = 1;
++		break;
++	case MPTCP_SUB_FCLOSE:
++		if (opsize != MPTCP_SUB_LEN_FCLOSE) {
++			mptcp_debug("%s: mp_fclose: bad option size %d\n",
++				    __func__, opsize);
++			break;
++		}
++
++		mopt->mp_fclose = 1;
++		mopt->mptcp_key = ((struct mp_fclose *)ptr)->key;
++
++		break;
++	default:
++		mptcp_debug("%s: Received unkown subtype: %d\n",
++			    __func__, mp_opt->sub);
++		break;
++	}
++}
++
++/** Parse only MPTCP options */
++void tcp_parse_mptcp_options(const struct sk_buff *skb,
++			     struct mptcp_options_received *mopt)
++{
++	const struct tcphdr *th = tcp_hdr(skb);
++	int length = (th->doff * 4) - sizeof(struct tcphdr);
++	const unsigned char *ptr = (const unsigned char *)(th + 1);
++
++	while (length > 0) {
++		int opcode = *ptr++;
++		int opsize;
++
++		switch (opcode) {
++		case TCPOPT_EOL:
++			return;
++		case TCPOPT_NOP:	/* Ref: RFC 793 section 3.1 */
++			length--;
++			continue;
++		default:
++			opsize = *ptr++;
++			if (opsize < 2)	/* "silly options" */
++				return;
++			if (opsize > length)
++				return;	/* don't parse partial options */
++			if (opcode == TCPOPT_MPTCP)
++				mptcp_parse_options(ptr - 2, opsize, mopt, skb);
++		}
++		ptr += opsize - 2;
++		length -= opsize;
++	}
++}
++
++int mptcp_check_rtt(const struct tcp_sock *tp, int time)
++{
++	struct mptcp_cb *mpcb = tp->mpcb;
++	struct sock *sk;
++	u32 rtt_max = 0;
++
++	/* In MPTCP, we take the max delay across all flows,
++	 * in order to take into account meta-reordering buffers.
++	 */
++	mptcp_for_each_sk(mpcb, sk) {
++		if (!mptcp_sk_can_recv(sk))
++			continue;
++
++		if (rtt_max < tcp_sk(sk)->rcv_rtt_est.rtt)
++			rtt_max = tcp_sk(sk)->rcv_rtt_est.rtt;
++	}
++	if (time < (rtt_max >> 3) || !rtt_max)
++		return 1;
++
++	return 0;
++}
++
++static void mptcp_handle_add_addr(const unsigned char *ptr, struct sock *sk)
++{
++	struct mp_add_addr *mpadd = (struct mp_add_addr *)ptr;
++	struct mptcp_cb *mpcb = tcp_sk(sk)->mpcb;
++	__be16 port = 0;
++	union inet_addr addr;
++	sa_family_t family;
++
++	if (mpadd->ipver == 4) {
++		if (mpadd->len == MPTCP_SUB_LEN_ADD_ADDR4 + 2)
++			port  = mpadd->u.v4.port;
++		family = AF_INET;
++		addr.in = mpadd->u.v4.addr;
++#if IS_ENABLED(CONFIG_IPV6)
++	} else if (mpadd->ipver == 6) {
++		if (mpadd->len == MPTCP_SUB_LEN_ADD_ADDR6 + 2)
++			port  = mpadd->u.v6.port;
++		family = AF_INET6;
++		addr.in6 = mpadd->u.v6.addr;
++#endif /* CONFIG_IPV6 */
++	} else {
++		return;
++	}
++
++	if (mpcb->pm_ops->add_raddr)
++		mpcb->pm_ops->add_raddr(mpcb, &addr, family, port, mpadd->addr_id);
++}
++
++static void mptcp_handle_rem_addr(const unsigned char *ptr, struct sock *sk)
++{
++	struct mp_remove_addr *mprem = (struct mp_remove_addr *)ptr;
++	int i;
++	u8 rem_id;
++	struct mptcp_cb *mpcb = tcp_sk(sk)->mpcb;
++
++	for (i = 0; i <= mprem->len - MPTCP_SUB_LEN_REMOVE_ADDR; i++) {
++		rem_id = (&mprem->addrs_id)[i];
++
++		if (mpcb->pm_ops->rem_raddr)
++			mpcb->pm_ops->rem_raddr(mpcb, rem_id);
++		mptcp_send_reset_rem_id(mpcb, rem_id);
++	}
++}
++
++static void mptcp_parse_addropt(const struct sk_buff *skb, struct sock *sk)
++{
++	struct tcphdr *th = tcp_hdr(skb);
++	unsigned char *ptr;
++	int length = (th->doff * 4) - sizeof(struct tcphdr);
++
++	/* Jump through the options to check whether ADD_ADDR is there */
++	ptr = (unsigned char *)(th + 1);
++	while (length > 0) {
++		int opcode = *ptr++;
++		int opsize;
++
++		switch (opcode) {
++		case TCPOPT_EOL:
++			return;
++		case TCPOPT_NOP:
++			length--;
++			continue;
++		default:
++			opsize = *ptr++;
++			if (opsize < 2)
++				return;
++			if (opsize > length)
++				return;  /* don't parse partial options */
++			if (opcode == TCPOPT_MPTCP &&
++			    ((struct mptcp_option *)ptr)->sub == MPTCP_SUB_ADD_ADDR) {
++#if IS_ENABLED(CONFIG_IPV6)
++				struct mp_add_addr *mpadd = (struct mp_add_addr *)ptr;
++				if ((mpadd->ipver == 4 && opsize != MPTCP_SUB_LEN_ADD_ADDR4 &&
++				     opsize != MPTCP_SUB_LEN_ADD_ADDR4 + 2) ||
++				    (mpadd->ipver == 6 && opsize != MPTCP_SUB_LEN_ADD_ADDR6 &&
++				     opsize != MPTCP_SUB_LEN_ADD_ADDR6 + 2))
++#else
++				if (opsize != MPTCP_SUB_LEN_ADD_ADDR4 &&
++				    opsize != MPTCP_SUB_LEN_ADD_ADDR4 + 2)
++#endif /* CONFIG_IPV6 */
++					goto cont;
++
++				mptcp_handle_add_addr(ptr, sk);
++			}
++			if (opcode == TCPOPT_MPTCP &&
++			    ((struct mptcp_option *)ptr)->sub == MPTCP_SUB_REMOVE_ADDR) {
++				if ((opsize - MPTCP_SUB_LEN_REMOVE_ADDR) < 0)
++					goto cont;
++
++				mptcp_handle_rem_addr(ptr, sk);
++			}
++cont:
++			ptr += opsize - 2;
++			length -= opsize;
++		}
++	}
++	return;
++}
++
++static inline int mptcp_mp_fail_rcvd(struct sock *sk, const struct tcphdr *th)
++{
++	struct mptcp_tcp_sock *mptcp = tcp_sk(sk)->mptcp;
++	struct sock *meta_sk = mptcp_meta_sk(sk);
++	struct mptcp_cb *mpcb = tcp_sk(sk)->mpcb;
++
++	if (unlikely(mptcp->rx_opt.mp_fail)) {
++		mptcp->rx_opt.mp_fail = 0;
++
++		if (!th->rst && !mpcb->infinite_mapping_snd) {
++			struct sock *sk_it;
++
++			mpcb->send_infinite_mapping = 1;
++			/* We resend everything that has not been acknowledged */
++			meta_sk->sk_send_head = tcp_write_queue_head(meta_sk);
++
++			/* We artificially restart the whole send-queue. Thus,
++			 * it is as if no packets are in flight
++			 */
++			tcp_sk(meta_sk)->packets_out = 0;
++
++			/* If the snd_nxt already wrapped around, we have to
++			 * undo the wrapping, as we are restarting from snd_una
++			 * on.
++			 */
++			if (tcp_sk(meta_sk)->snd_nxt < tcp_sk(meta_sk)->snd_una) {
++				mpcb->snd_high_order[mpcb->snd_hiseq_index] -= 2;
++				mpcb->snd_hiseq_index = mpcb->snd_hiseq_index ? 0 : 1;
++			}
++			tcp_sk(meta_sk)->snd_nxt = tcp_sk(meta_sk)->snd_una;
++
++			/* Trigger a sending on the meta. */
++			mptcp_push_pending_frames(meta_sk);
++
++			mptcp_for_each_sk(mpcb, sk_it) {
++				if (sk != sk_it)
++					mptcp_sub_force_close(sk_it);
++			}
++		}
++
++		return 0;
++	}
++
++	if (unlikely(mptcp->rx_opt.mp_fclose)) {
++		struct sock *sk_it, *tmpsk;
++
++		mptcp->rx_opt.mp_fclose = 0;
++		if (mptcp->rx_opt.mptcp_key != mpcb->mptcp_loc_key)
++			return 0;
++
++		if (tcp_need_reset(sk->sk_state))
++			tcp_sk(sk)->ops->send_active_reset(sk, GFP_ATOMIC);
++
++		mptcp_for_each_sk_safe(mpcb, sk_it, tmpsk)
++			mptcp_sub_force_close(sk_it);
++
++		tcp_reset(meta_sk);
++
++		return 1;
++	}
++
++	return 0;
++}
++
++static inline void mptcp_path_array_check(struct sock *meta_sk)
++{
++	struct mptcp_cb *mpcb = tcp_sk(meta_sk)->mpcb;
++
++	if (unlikely(mpcb->list_rcvd)) {
++		mpcb->list_rcvd = 0;
++		if (mpcb->pm_ops->new_remote_address)
++			mpcb->pm_ops->new_remote_address(meta_sk);
++	}
++}
++
++int mptcp_handle_options(struct sock *sk, const struct tcphdr *th,
++			 const struct sk_buff *skb)
++{
++	struct tcp_sock *tp = tcp_sk(sk);
++	struct mptcp_options_received *mopt = &tp->mptcp->rx_opt;
++
++	if (tp->mpcb->infinite_mapping_rcv || tp->mpcb->infinite_mapping_snd)
++		return 0;
++
++	if (mptcp_mp_fail_rcvd(sk, th))
++		return 1;
++
++	/* RFC 6824, Section 3.3:
++	 * If a checksum is not present when its use has been negotiated, the
++	 * receiver MUST close the subflow with a RST as it is considered broken.
++	 */
++	if (mptcp_is_data_seq(skb) && tp->mpcb->dss_csum &&
++	    !(TCP_SKB_CB(skb)->mptcp_flags & MPTCPHDR_DSS_CSUM)) {
++		if (tcp_need_reset(sk->sk_state))
++			tp->ops->send_active_reset(sk, GFP_ATOMIC);
++
++		mptcp_sub_force_close(sk);
++		return 1;
++	}
++
++	/* We have to acknowledge retransmissions of the third
++	 * ack.
++	 */
++	if (mopt->join_ack) {
++		tcp_send_delayed_ack(sk);
++		mopt->join_ack = 0;
++	}
++
++	if (mopt->saw_add_addr || mopt->saw_rem_addr) {
++		if (mopt->more_add_addr || mopt->more_rem_addr) {
++			mptcp_parse_addropt(skb, sk);
++		} else {
++			if (mopt->saw_add_addr)
++				mptcp_handle_add_addr(mopt->add_addr_ptr, sk);
++			if (mopt->saw_rem_addr)
++				mptcp_handle_rem_addr(mopt->rem_addr_ptr, sk);
++		}
++
++		mopt->more_add_addr = 0;
++		mopt->saw_add_addr = 0;
++		mopt->more_rem_addr = 0;
++		mopt->saw_rem_addr = 0;
++	}
++	if (mopt->saw_low_prio) {
++		if (mopt->saw_low_prio == 1) {
++			tp->mptcp->rcv_low_prio = mopt->low_prio;
++		} else {
++			struct sock *sk_it;
++			mptcp_for_each_sk(tp->mpcb, sk_it) {
++				struct mptcp_tcp_sock *mptcp = tcp_sk(sk_it)->mptcp;
++				if (mptcp->rem_id == mopt->prio_addr_id)
++					mptcp->rcv_low_prio = mopt->low_prio;
++			}
++		}
++		mopt->saw_low_prio = 0;
++	}
++
++	mptcp_data_ack(sk, skb);
++
++	mptcp_path_array_check(mptcp_meta_sk(sk));
++	/* Socket may have been mp_killed by a REMOVE_ADDR */
++	if (tp->mp_killed)
++		return 1;
++
++	return 0;
++}
++
++/* In case of fastopen, some data can already be in the write queue.
++ * We need to update the sequence number of the segments as they
++ * were initially TCP sequence numbers.
++ */
++static void mptcp_rcv_synsent_fastopen(struct sock *meta_sk)
++{
++	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
++	struct tcp_sock *master_tp = tcp_sk(meta_tp->mpcb->master_sk);
++	struct sk_buff *skb;
++	u32 new_mapping = meta_tp->write_seq - master_tp->snd_una;
++
++	/* There should only be one skb in write queue: the data not
++	 * acknowledged in the SYN+ACK. In this case, we need to map
++	 * this data to data sequence numbers.
++	 */
++	skb_queue_walk(&meta_sk->sk_write_queue, skb) {
++		/* If the server only acknowledges partially the data sent in
++		 * the SYN, we need to trim the acknowledged part because
++		 * we don't want to retransmit this already received data.
++		 * When we reach this point, tcp_ack() has already cleaned up
++		 * fully acked segments. However, tcp trims partially acked
++		 * segments only when retransmitting. Since MPTCP comes into
++		 * play only now, we will fake an initial transmit, and
++		 * retransmit_skb() will not be called. The following fragment
++		 * comes from __tcp_retransmit_skb().
++		 */
++		if (before(TCP_SKB_CB(skb)->seq, master_tp->snd_una)) {
++			BUG_ON(before(TCP_SKB_CB(skb)->end_seq,
++				      master_tp->snd_una));
++			/* tcp_trim_head can only returns ENOMEM if skb is
++			 * cloned. It is not the case here (see
++			 * tcp_send_syn_data).
++			 */
++			BUG_ON(tcp_trim_head(meta_sk, skb, master_tp->snd_una -
++					     TCP_SKB_CB(skb)->seq));
++		}
++
++		TCP_SKB_CB(skb)->seq += new_mapping;
++		TCP_SKB_CB(skb)->end_seq += new_mapping;
++	}
++
++	/* We can advance write_seq by the number of bytes unacknowledged
++	 * and that were mapped in the previous loop.
++	 */
++	meta_tp->write_seq += master_tp->write_seq - master_tp->snd_una;
++
++	/* The packets from the master_sk will be entailed to it later
++	 * Until that time, its write queue is empty, and
++	 * write_seq must align with snd_una
++	 */
++	master_tp->snd_nxt = master_tp->write_seq = master_tp->snd_una;
++	master_tp->packets_out = 0;
++
++	/* Although these data have been sent already over the subsk,
++	 * They have never been sent over the meta_sk, so we rewind
++	 * the send_head so that tcp considers it as an initial send
++	 * (instead of retransmit).
++	 */
++	meta_sk->sk_send_head = tcp_write_queue_head(meta_sk);
++}
++
++/* The skptr is needed, because if we become MPTCP-capable, we have to switch
++ * from meta-socket to master-socket.
++ *
++ * @return: 1 - we want to reset this connection
++ *	    2 - we want to discard the received syn/ack
++ *	    0 - everything is fine - continue
++ */
++int mptcp_rcv_synsent_state_process(struct sock *sk, struct sock **skptr,
++				    const struct sk_buff *skb,
++				    const struct mptcp_options_received *mopt)
++{
++	struct tcp_sock *tp = tcp_sk(sk);
++
++	if (mptcp(tp)) {
++		u8 hash_mac_check[20];
++		struct mptcp_cb *mpcb = tp->mpcb;
++
++		mptcp_hmac_sha1((u8 *)&mpcb->mptcp_rem_key,
++				(u8 *)&mpcb->mptcp_loc_key,
++				(u8 *)&tp->mptcp->rx_opt.mptcp_recv_nonce,
++				(u8 *)&tp->mptcp->mptcp_loc_nonce,
++				(u32 *)hash_mac_check);
++		if (memcmp(hash_mac_check,
++			   (char *)&tp->mptcp->rx_opt.mptcp_recv_tmac, 8)) {
++			mptcp_sub_force_close(sk);
++			return 1;
++		}
++
++		/* Set this flag in order to postpone data sending
++		 * until the 4th ack arrives.
++		 */
++		tp->mptcp->pre_established = 1;
++		tp->mptcp->rcv_low_prio = tp->mptcp->rx_opt.low_prio;
++
++		mptcp_hmac_sha1((u8 *)&mpcb->mptcp_loc_key,
++				(u8 *)&mpcb->mptcp_rem_key,
++				(u8 *)&tp->mptcp->mptcp_loc_nonce,
++				(u8 *)&tp->mptcp->rx_opt.mptcp_recv_nonce,
++				(u32 *)&tp->mptcp->sender_mac[0]);
++
++	} else if (mopt->saw_mpc) {
++		struct sock *meta_sk = sk;
++
++		if (mptcp_create_master_sk(sk, mopt->mptcp_key,
++					   ntohs(tcp_hdr(skb)->window)))
++			return 2;
++
++		sk = tcp_sk(sk)->mpcb->master_sk;
++		*skptr = sk;
++		tp = tcp_sk(sk);
++
++		/* If fastopen was used data might be in the send queue. We
++		 * need to update their sequence number to MPTCP-level seqno.
++		 * Note that it can happen in rare cases that fastopen_req is
++		 * NULL and syn_data is 0 but fastopen indeed occurred and
++		 * data has been queued in the write queue (but not sent).
++		 * Example of such rare cases: connect is non-blocking and
++		 * TFO is configured to work without cookies.
++		 */
++		if (!skb_queue_empty(&meta_sk->sk_write_queue))
++			mptcp_rcv_synsent_fastopen(meta_sk);
++
++		/* -1, because the SYN consumed 1 byte. In case of TFO, we
++		 * start the subflow-sequence number as if the data of the SYN
++		 * is not part of any mapping.
++		 */
++		tp->mptcp->snt_isn = tp->snd_una - 1;
++		tp->mpcb->dss_csum = mopt->dss_csum;
++		tp->mptcp->include_mpc = 1;
++
++		/* Ensure that fastopen is handled at the meta-level. */
++		tp->fastopen_req = NULL;
++
++		sk_set_socket(sk, mptcp_meta_sk(sk)->sk_socket);
++		sk->sk_wq = mptcp_meta_sk(sk)->sk_wq;
++
++		 /* hold in sk_clone_lock due to initialization to 2 */
++		sock_put(sk);
++	} else {
++		tp->request_mptcp = 0;
++
++		if (tp->inside_tk_table)
++			mptcp_hash_remove(tp);
++	}
++
++	if (mptcp(tp))
++		tp->mptcp->rcv_isn = TCP_SKB_CB(skb)->seq;
++
++	return 0;
++}
++
++bool mptcp_should_expand_sndbuf(const struct sock *sk)
++{
++	const struct sock *sk_it;
++	const struct sock *meta_sk = mptcp_meta_sk(sk);
++	const struct tcp_sock *meta_tp = tcp_sk(meta_sk);
++	int cnt_backups = 0;
++	int backup_available = 0;
++
++	/* We circumvent this check in tcp_check_space, because we want to
++	 * always call sk_write_space. So, we reproduce the check here.
++	 */
++	if (!meta_sk->sk_socket ||
++	    !test_bit(SOCK_NOSPACE, &meta_sk->sk_socket->flags))
++		return false;
++
++	/* If the user specified a specific send buffer setting, do
++	 * not modify it.
++	 */
++	if (meta_sk->sk_userlocks & SOCK_SNDBUF_LOCK)
++		return false;
++
++	/* If we are under global TCP memory pressure, do not expand.  */
++	if (sk_under_memory_pressure(meta_sk))
++		return false;
++
++	/* If we are under soft global TCP memory pressure, do not expand.  */
++	if (sk_memory_allocated(meta_sk) >= sk_prot_mem_limits(meta_sk, 0))
++		return false;
++
++
++	/* For MPTCP we look for a subsocket that could send data.
++	 * If we found one, then we update the send-buffer.
++	 */
++	mptcp_for_each_sk(meta_tp->mpcb, sk_it) {
++		struct tcp_sock *tp_it = tcp_sk(sk_it);
++
++		if (!mptcp_sk_can_send(sk_it))
++			continue;
++
++		/* Backup-flows have to be counted - if there is no other
++		 * subflow we take the backup-flow into account.
++		 */
++		if (tp_it->mptcp->rcv_low_prio || tp_it->mptcp->low_prio)
++			cnt_backups++;
++
++		if (tp_it->packets_out < tp_it->snd_cwnd) {
++			if (tp_it->mptcp->rcv_low_prio || tp_it->mptcp->low_prio) {
++				backup_available = 1;
++				continue;
++			}
++			return true;
++		}
++	}
++
++	/* Backup-flow is available for sending - update send-buffer */
++	if (meta_tp->mpcb->cnt_established == cnt_backups && backup_available)
++		return true;
++	return false;
++}
++
++void mptcp_init_buffer_space(struct sock *sk)
++{
++	struct tcp_sock *tp = tcp_sk(sk);
++	struct sock *meta_sk = mptcp_meta_sk(sk);
++	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
++	int space;
++
++	tcp_init_buffer_space(sk);
++
++	if (is_master_tp(tp)) {
++		meta_tp->rcvq_space.space = meta_tp->rcv_wnd;
++		meta_tp->rcvq_space.time = tcp_time_stamp;
++		meta_tp->rcvq_space.seq = meta_tp->copied_seq;
++
++		/* If there is only one subflow, we just use regular TCP
++		 * autotuning. User-locks are handled already by
++		 * tcp_init_buffer_space
++		 */
++		meta_tp->window_clamp = tp->window_clamp;
++		meta_tp->rcv_ssthresh = tp->rcv_ssthresh;
++		meta_sk->sk_rcvbuf = sk->sk_rcvbuf;
++		meta_sk->sk_sndbuf = sk->sk_sndbuf;
++
++		return;
++	}
++
++	if (meta_sk->sk_userlocks & SOCK_RCVBUF_LOCK)
++		goto snd_buf;
++
++	/* Adding a new subflow to the rcv-buffer space. We make a simple
++	 * addition, to give some space to allow traffic on the new subflow.
++	 * Autotuning will increase it further later on.
++	 */
++	space = min(meta_sk->sk_rcvbuf + sk->sk_rcvbuf, sysctl_tcp_rmem[2]);
++	if (space > meta_sk->sk_rcvbuf) {
++		meta_tp->window_clamp += tp->window_clamp;
++		meta_tp->rcv_ssthresh += tp->rcv_ssthresh;
++		meta_sk->sk_rcvbuf = space;
++	}
++
++snd_buf:
++	if (meta_sk->sk_userlocks & SOCK_SNDBUF_LOCK)
++		return;
++
++	/* Adding a new subflow to the send-buffer space. We make a simple
++	 * addition, to give some space to allow traffic on the new subflow.
++	 * Autotuning will increase it further later on.
++	 */
++	space = min(meta_sk->sk_sndbuf + sk->sk_sndbuf, sysctl_tcp_wmem[2]);
++	if (space > meta_sk->sk_sndbuf) {
++		meta_sk->sk_sndbuf = space;
++		meta_sk->sk_write_space(meta_sk);
++	}
++}
++
++void mptcp_tcp_set_rto(struct sock *sk)
++{
++	tcp_set_rto(sk);
++	mptcp_set_rto(sk);
++}
+diff --git a/net/mptcp/mptcp_ipv4.c b/net/mptcp/mptcp_ipv4.c
+new file mode 100644
+index 000000000000..1183d1305d35
+--- /dev/null
++++ b/net/mptcp/mptcp_ipv4.c
+@@ -0,0 +1,483 @@
++/*
++ *	MPTCP implementation - IPv4-specific functions
++ *
++ *	Initial Design & Implementation:
++ *	Sébastien Barré <sebastien.barre@×××××××××.be>
++ *
++ *	Current Maintainer:
++ *	Christoph Paasch <christoph.paasch@×××××××××.be>
++ *
++ *	Additional authors:
++ *	Jaakko Korkeaniemi <jaakko.korkeaniemi@×××××.fi>
++ *	Gregory Detal <gregory.detal@×××××××××.be>
++ *	Fabien Duchêne <fabien.duchene@×××××××××.be>
++ *	Andreas Seelinger <Andreas.Seelinger@×××××××××××.de>
++ *	Lavkesh Lahngir <lavkesh51@×××××.com>
++ *	Andreas Ripke <ripke@××××××.eu>
++ *	Vlad Dogaru <vlad.dogaru@×××××.com>
++ *	Octavian Purdila <octavian.purdila@×××××.com>
++ *	John Ronan <jronan@××××.org>
++ *	Catalin Nicutar <catalin.nicutar@×××××.com>
++ *	Brandon Heller <brandonh@××××××××.edu>
++ *
++ *
++ *	This program is free software; you can redistribute it and/or
++ *      modify it under the terms of the GNU General Public License
++ *      as published by the Free Software Foundation; either version
++ *      2 of the License, or (at your option) any later version.
++ */
++
++#include <linux/export.h>
++#include <linux/ip.h>
++#include <linux/list.h>
++#include <linux/skbuff.h>
++#include <linux/spinlock.h>
++#include <linux/tcp.h>
++
++#include <net/inet_common.h>
++#include <net/inet_connection_sock.h>
++#include <net/mptcp.h>
++#include <net/mptcp_v4.h>
++#include <net/request_sock.h>
++#include <net/tcp.h>
++
++u32 mptcp_v4_get_nonce(__be32 saddr, __be32 daddr, __be16 sport, __be16 dport)
++{
++	u32 hash[MD5_DIGEST_WORDS];
++
++	hash[0] = (__force u32)saddr;
++	hash[1] = (__force u32)daddr;
++	hash[2] = ((__force u16)sport << 16) + (__force u16)dport;
++	hash[3] = mptcp_seed++;
++
++	md5_transform(hash, mptcp_secret);
++
++	return hash[0];
++}
++
++u64 mptcp_v4_get_key(__be32 saddr, __be32 daddr, __be16 sport, __be16 dport)
++{
++	u32 hash[MD5_DIGEST_WORDS];
++
++	hash[0] = (__force u32)saddr;
++	hash[1] = (__force u32)daddr;
++	hash[2] = ((__force u16)sport << 16) + (__force u16)dport;
++	hash[3] = mptcp_seed++;
++
++	md5_transform(hash, mptcp_secret);
++
++	return *((u64 *)hash);
++}
++
++
++static void mptcp_v4_reqsk_destructor(struct request_sock *req)
++{
++	mptcp_reqsk_destructor(req);
++
++	tcp_v4_reqsk_destructor(req);
++}
++
++static int mptcp_v4_init_req(struct request_sock *req, struct sock *sk,
++			     struct sk_buff *skb)
++{
++	tcp_request_sock_ipv4_ops.init_req(req, sk, skb);
++	mptcp_reqsk_init(req, skb);
++
++	return 0;
++}
++
++static int mptcp_v4_join_init_req(struct request_sock *req, struct sock *sk,
++				  struct sk_buff *skb)
++{
++	struct mptcp_request_sock *mtreq = mptcp_rsk(req);
++	struct mptcp_cb *mpcb = tcp_sk(sk)->mpcb;
++	union inet_addr addr;
++	int loc_id;
++	bool low_prio = false;
++
++	/* We need to do this as early as possible. Because, if we fail later
++	 * (e.g., get_local_id), then reqsk_free tries to remove the
++	 * request-socket from the htb in mptcp_hash_request_remove as pprev
++	 * may be different from NULL.
++	 */
++	mtreq->hash_entry.pprev = NULL;
++
++	tcp_request_sock_ipv4_ops.init_req(req, sk, skb);
++
++	mtreq->mptcp_loc_nonce = mptcp_v4_get_nonce(ip_hdr(skb)->saddr,
++						    ip_hdr(skb)->daddr,
++						    tcp_hdr(skb)->source,
++						    tcp_hdr(skb)->dest);
++	addr.ip = inet_rsk(req)->ir_loc_addr;
++	loc_id = mpcb->pm_ops->get_local_id(AF_INET, &addr, sock_net(sk), &low_prio);
++	if (loc_id == -1)
++		return -1;
++	mtreq->loc_id = loc_id;
++	mtreq->low_prio = low_prio;
++
++	mptcp_join_reqsk_init(mpcb, req, skb);
++
++	return 0;
++}
++
++/* Similar to tcp_request_sock_ops */
++struct request_sock_ops mptcp_request_sock_ops __read_mostly = {
++	.family		=	PF_INET,
++	.obj_size	=	sizeof(struct mptcp_request_sock),
++	.rtx_syn_ack	=	tcp_rtx_synack,
++	.send_ack	=	tcp_v4_reqsk_send_ack,
++	.destructor	=	mptcp_v4_reqsk_destructor,
++	.send_reset	=	tcp_v4_send_reset,
++	.syn_ack_timeout =	tcp_syn_ack_timeout,
++};
++
++static void mptcp_v4_reqsk_queue_hash_add(struct sock *meta_sk,
++					  struct request_sock *req,
++					  const unsigned long timeout)
++{
++	const u32 h1 = inet_synq_hash(inet_rsk(req)->ir_rmt_addr,
++				     inet_rsk(req)->ir_rmt_port,
++				     0, MPTCP_HASH_SIZE);
++	/* We cannot call inet_csk_reqsk_queue_hash_add(), because we do not
++	 * want to reset the keepalive-timer (responsible for retransmitting
++	 * SYN/ACKs). We do not retransmit SYN/ACKs+MP_JOINs, because we cannot
++	 * overload the keepalive timer. Also, it's not a big deal, because the
++	 * third ACK of the MP_JOIN-handshake is sent in a reliable manner. So,
++	 * if the third ACK gets lost, the client will handle the retransmission
++	 * anyways. If our SYN/ACK gets lost, the client will retransmit the
++	 * SYN.
++	 */
++	struct inet_connection_sock *meta_icsk = inet_csk(meta_sk);
++	struct listen_sock *lopt = meta_icsk->icsk_accept_queue.listen_opt;
++	const u32 h2 = inet_synq_hash(inet_rsk(req)->ir_rmt_addr,
++				     inet_rsk(req)->ir_rmt_port,
++				     lopt->hash_rnd, lopt->nr_table_entries);
++
++	reqsk_queue_hash_req(&meta_icsk->icsk_accept_queue, h2, req, timeout);
++	if (reqsk_queue_added(&meta_icsk->icsk_accept_queue) == 0)
++		mptcp_reset_synack_timer(meta_sk, timeout);
++
++	rcu_read_lock();
++	spin_lock(&mptcp_reqsk_hlock);
++	hlist_nulls_add_head_rcu(&mptcp_rsk(req)->hash_entry, &mptcp_reqsk_htb[h1]);
++	spin_unlock(&mptcp_reqsk_hlock);
++	rcu_read_unlock();
++}
++
++/* Similar to tcp_v4_conn_request */
++static int mptcp_v4_join_request(struct sock *meta_sk, struct sk_buff *skb)
++{
++	return tcp_conn_request(&mptcp_request_sock_ops,
++				&mptcp_join_request_sock_ipv4_ops,
++				meta_sk, skb);
++}
++
++/* We only process join requests here. (either the SYN or the final ACK) */
++int mptcp_v4_do_rcv(struct sock *meta_sk, struct sk_buff *skb)
++{
++	const struct mptcp_cb *mpcb = tcp_sk(meta_sk)->mpcb;
++	struct sock *child, *rsk = NULL;
++	int ret;
++
++	if (!(TCP_SKB_CB(skb)->mptcp_flags & MPTCPHDR_JOIN)) {
++		struct tcphdr *th = tcp_hdr(skb);
++		const struct iphdr *iph = ip_hdr(skb);
++		struct sock *sk;
++
++		sk = inet_lookup_established(sock_net(meta_sk), &tcp_hashinfo,
++					     iph->saddr, th->source, iph->daddr,
++					     th->dest, inet_iif(skb));
++
++		if (!sk) {
++			kfree_skb(skb);
++			return 0;
++		}
++		if (is_meta_sk(sk)) {
++			WARN("%s Did not find a sub-sk - did found the meta!\n", __func__);
++			kfree_skb(skb);
++			sock_put(sk);
++			return 0;
++		}
++
++		if (sk->sk_state == TCP_TIME_WAIT) {
++			inet_twsk_put(inet_twsk(sk));
++			kfree_skb(skb);
++			return 0;
++		}
++
++		ret = tcp_v4_do_rcv(sk, skb);
++		sock_put(sk);
++
++		return ret;
++	}
++	TCP_SKB_CB(skb)->mptcp_flags = 0;
++
++	/* Has been removed from the tk-table. Thus, no new subflows.
++	 *
++	 * Check for close-state is necessary, because we may have been closed
++	 * without passing by mptcp_close().
++	 *
++	 * When falling back, no new subflows are allowed either.
++	 */
++	if (meta_sk->sk_state == TCP_CLOSE || !tcp_sk(meta_sk)->inside_tk_table ||
++	    mpcb->infinite_mapping_rcv || mpcb->send_infinite_mapping)
++		goto reset_and_discard;
++
++	child = tcp_v4_hnd_req(meta_sk, skb);
++
++	if (!child)
++		goto discard;
++
++	if (child != meta_sk) {
++		sock_rps_save_rxhash(child, skb);
++		/* We don't call tcp_child_process here, because we hold
++		 * already the meta-sk-lock and are sure that it is not owned
++		 * by the user.
++		 */
++		ret = tcp_rcv_state_process(child, skb, tcp_hdr(skb), skb->len);
++		bh_unlock_sock(child);
++		sock_put(child);
++		if (ret) {
++			rsk = child;
++			goto reset_and_discard;
++		}
++	} else {
++		if (tcp_hdr(skb)->syn) {
++			mptcp_v4_join_request(meta_sk, skb);
++			goto discard;
++		}
++		goto reset_and_discard;
++	}
++	return 0;
++
++reset_and_discard:
++	if (reqsk_queue_len(&inet_csk(meta_sk)->icsk_accept_queue)) {
++		const struct tcphdr *th = tcp_hdr(skb);
++		const struct iphdr *iph = ip_hdr(skb);
++		struct request_sock **prev, *req;
++		/* If we end up here, it means we should not have matched on the
++		 * request-socket. But, because the request-sock queue is only
++		 * destroyed in mptcp_close, the socket may actually already be
++		 * in close-state (e.g., through shutdown()) while still having
++		 * pending request sockets.
++		 */
++		req = inet_csk_search_req(meta_sk, &prev, th->source,
++					  iph->saddr, iph->daddr);
++		if (req) {
++			inet_csk_reqsk_queue_unlink(meta_sk, req, prev);
++			reqsk_queue_removed(&inet_csk(meta_sk)->icsk_accept_queue,
++					    req);
++			reqsk_free(req);
++		}
++	}
++
++	tcp_v4_send_reset(rsk, skb);
++discard:
++	kfree_skb(skb);
++	return 0;
++}
++
++/* After this, the ref count of the meta_sk associated with the request_sock
++ * is incremented. Thus it is the responsibility of the caller
++ * to call sock_put() when the reference is not needed anymore.
++ */
++struct sock *mptcp_v4_search_req(const __be16 rport, const __be32 raddr,
++				 const __be32 laddr, const struct net *net)
++{
++	const struct mptcp_request_sock *mtreq;
++	struct sock *meta_sk = NULL;
++	const struct hlist_nulls_node *node;
++	const u32 hash = inet_synq_hash(raddr, rport, 0, MPTCP_HASH_SIZE);
++
++	rcu_read_lock();
++begin:
++	hlist_nulls_for_each_entry_rcu(mtreq, node, &mptcp_reqsk_htb[hash],
++				       hash_entry) {
++		struct inet_request_sock *ireq = inet_rsk(rev_mptcp_rsk(mtreq));
++		meta_sk = mtreq->mptcp_mpcb->meta_sk;
++
++		if (ireq->ir_rmt_port == rport &&
++		    ireq->ir_rmt_addr == raddr &&
++		    ireq->ir_loc_addr == laddr &&
++		    rev_mptcp_rsk(mtreq)->rsk_ops->family == AF_INET &&
++		    net_eq(net, sock_net(meta_sk)))
++			goto found;
++		meta_sk = NULL;
++	}
++	/* A request-socket is destroyed by RCU. So, it might have been recycled
++	 * and put into another hash-table list. So, after the lookup we may
++	 * end up in a different list. So, we may need to restart.
++	 *
++	 * See also the comment in __inet_lookup_established.
++	 */
++	if (get_nulls_value(node) != hash + MPTCP_REQSK_NULLS_BASE)
++		goto begin;
++
++found:
++	if (meta_sk && unlikely(!atomic_inc_not_zero(&meta_sk->sk_refcnt)))
++		meta_sk = NULL;
++	rcu_read_unlock();
++
++	return meta_sk;
++}
++
++/* Create a new IPv4 subflow.
++ *
++ * We are in user-context and meta-sock-lock is hold.
++ */
++int mptcp_init4_subsockets(struct sock *meta_sk, const struct mptcp_loc4 *loc,
++			   struct mptcp_rem4 *rem)
++{
++	struct tcp_sock *tp;
++	struct sock *sk;
++	struct sockaddr_in loc_in, rem_in;
++	struct socket sock;
++	int ret;
++
++	/** First, create and prepare the new socket */
++
++	sock.type = meta_sk->sk_socket->type;
++	sock.state = SS_UNCONNECTED;
++	sock.wq = meta_sk->sk_socket->wq;
++	sock.file = meta_sk->sk_socket->file;
++	sock.ops = NULL;
++
++	ret = inet_create(sock_net(meta_sk), &sock, IPPROTO_TCP, 1);
++	if (unlikely(ret < 0)) {
++		mptcp_debug("%s inet_create failed ret: %d\n", __func__, ret);
++		return ret;
++	}
++
++	sk = sock.sk;
++	tp = tcp_sk(sk);
++
++	/* All subsockets need the MPTCP-lock-class */
++	lockdep_set_class_and_name(&(sk)->sk_lock.slock, &meta_slock_key, "slock-AF_INET-MPTCP");
++	lockdep_init_map(&(sk)->sk_lock.dep_map, "sk_lock-AF_INET-MPTCP", &meta_key, 0);
++
++	if (mptcp_add_sock(meta_sk, sk, loc->loc4_id, rem->rem4_id, GFP_KERNEL))
++		goto error;
++
++	tp->mptcp->slave_sk = 1;
++	tp->mptcp->low_prio = loc->low_prio;
++
++	/* Initializing the timer for an MPTCP subflow */
++	setup_timer(&tp->mptcp->mptcp_ack_timer, mptcp_ack_handler, (unsigned long)sk);
++
++	/** Then, connect the socket to the peer */
++	loc_in.sin_family = AF_INET;
++	rem_in.sin_family = AF_INET;
++	loc_in.sin_port = 0;
++	if (rem->port)
++		rem_in.sin_port = rem->port;
++	else
++		rem_in.sin_port = inet_sk(meta_sk)->inet_dport;
++	loc_in.sin_addr = loc->addr;
++	rem_in.sin_addr = rem->addr;
++
++	ret = sock.ops->bind(&sock, (struct sockaddr *)&loc_in, sizeof(struct sockaddr_in));
++	if (ret < 0) {
++		mptcp_debug("%s: MPTCP subsocket bind() failed, error %d\n",
++			    __func__, ret);
++		goto error;
++	}
++
++	mptcp_debug("%s: token %#x pi %d src_addr:%pI4:%d dst_addr:%pI4:%d\n",
++		    __func__, tcp_sk(meta_sk)->mpcb->mptcp_loc_token,
++		    tp->mptcp->path_index, &loc_in.sin_addr,
++		    ntohs(loc_in.sin_port), &rem_in.sin_addr,
++		    ntohs(rem_in.sin_port));
++
++	if (tcp_sk(meta_sk)->mpcb->pm_ops->init_subsocket_v4)
++		tcp_sk(meta_sk)->mpcb->pm_ops->init_subsocket_v4(sk, rem->addr);
++
++	ret = sock.ops->connect(&sock, (struct sockaddr *)&rem_in,
++				sizeof(struct sockaddr_in), O_NONBLOCK);
++	if (ret < 0 && ret != -EINPROGRESS) {
++		mptcp_debug("%s: MPTCP subsocket connect() failed, error %d\n",
++			    __func__, ret);
++		goto error;
++	}
++
++	sk_set_socket(sk, meta_sk->sk_socket);
++	sk->sk_wq = meta_sk->sk_wq;
++
++	return 0;
++
++error:
++	/* May happen if mptcp_add_sock fails first */
++	if (!mptcp(tp)) {
++		tcp_close(sk, 0);
++	} else {
++		local_bh_disable();
++		mptcp_sub_force_close(sk);
++		local_bh_enable();
++	}
++	return ret;
++}
++EXPORT_SYMBOL(mptcp_init4_subsockets);
++
++const struct inet_connection_sock_af_ops mptcp_v4_specific = {
++	.queue_xmit	   = ip_queue_xmit,
++	.send_check	   = tcp_v4_send_check,
++	.rebuild_header	   = inet_sk_rebuild_header,
++	.sk_rx_dst_set	   = inet_sk_rx_dst_set,
++	.conn_request	   = mptcp_conn_request,
++	.syn_recv_sock	   = tcp_v4_syn_recv_sock,
++	.net_header_len	   = sizeof(struct iphdr),
++	.setsockopt	   = ip_setsockopt,
++	.getsockopt	   = ip_getsockopt,
++	.addr2sockaddr	   = inet_csk_addr2sockaddr,
++	.sockaddr_len	   = sizeof(struct sockaddr_in),
++	.bind_conflict	   = inet_csk_bind_conflict,
++#ifdef CONFIG_COMPAT
++	.compat_setsockopt = compat_ip_setsockopt,
++	.compat_getsockopt = compat_ip_getsockopt,
++#endif
++};
++
++struct tcp_request_sock_ops mptcp_request_sock_ipv4_ops;
++struct tcp_request_sock_ops mptcp_join_request_sock_ipv4_ops;
++
++/* General initialization of IPv4 for MPTCP */
++int mptcp_pm_v4_init(void)
++{
++	int ret = 0;
++	struct request_sock_ops *ops = &mptcp_request_sock_ops;
++
++	mptcp_request_sock_ipv4_ops = tcp_request_sock_ipv4_ops;
++	mptcp_request_sock_ipv4_ops.init_req = mptcp_v4_init_req;
++
++	mptcp_join_request_sock_ipv4_ops = tcp_request_sock_ipv4_ops;
++	mptcp_join_request_sock_ipv4_ops.init_req = mptcp_v4_join_init_req;
++	mptcp_join_request_sock_ipv4_ops.queue_hash_add = mptcp_v4_reqsk_queue_hash_add;
++
++	ops->slab_name = kasprintf(GFP_KERNEL, "request_sock_%s", "MPTCP");
++	if (ops->slab_name == NULL) {
++		ret = -ENOMEM;
++		goto out;
++	}
++
++	ops->slab = kmem_cache_create(ops->slab_name, ops->obj_size, 0,
++				      SLAB_DESTROY_BY_RCU|SLAB_HWCACHE_ALIGN,
++				      NULL);
++
++	if (ops->slab == NULL) {
++		ret =  -ENOMEM;
++		goto err_reqsk_create;
++	}
++
++out:
++	return ret;
++
++err_reqsk_create:
++	kfree(ops->slab_name);
++	ops->slab_name = NULL;
++	goto out;
++}
++
++void mptcp_pm_v4_undo(void)
++{
++	kmem_cache_destroy(mptcp_request_sock_ops.slab);
++	kfree(mptcp_request_sock_ops.slab_name);
++}
+diff --git a/net/mptcp/mptcp_ipv6.c b/net/mptcp/mptcp_ipv6.c
+new file mode 100644
+index 000000000000..1036973aa855
+--- /dev/null
++++ b/net/mptcp/mptcp_ipv6.c
+@@ -0,0 +1,518 @@
++/*
++ *	MPTCP implementation - IPv6-specific functions
++ *
++ *	Initial Design & Implementation:
++ *	Sébastien Barré <sebastien.barre@×××××××××.be>
++ *
++ *	Current Maintainer:
++ *	Jaakko Korkeaniemi <jaakko.korkeaniemi@×××××.fi>
++ *
++ *	Additional authors:
++ *	Jaakko Korkeaniemi <jaakko.korkeaniemi@×××××.fi>
++ *	Gregory Detal <gregory.detal@×××××××××.be>
++ *	Fabien Duchêne <fabien.duchene@×××××××××.be>
++ *	Andreas Seelinger <Andreas.Seelinger@×××××××××××.de>
++ *	Lavkesh Lahngir <lavkesh51@×××××.com>
++ *	Andreas Ripke <ripke@××××××.eu>
++ *	Vlad Dogaru <vlad.dogaru@×××××.com>
++ *	Octavian Purdila <octavian.purdila@×××××.com>
++ *	John Ronan <jronan@××××.org>
++ *	Catalin Nicutar <catalin.nicutar@×××××.com>
++ *	Brandon Heller <brandonh@××××××××.edu>
++ *
++ *
++ *	This program is free software; you can redistribute it and/or
++ *      modify it under the terms of the GNU General Public License
++ *      as published by the Free Software Foundation; either version
++ *      2 of the License, or (at your option) any later version.
++ */
++
++#include <linux/export.h>
++#include <linux/in6.h>
++#include <linux/kernel.h>
++
++#include <net/addrconf.h>
++#include <net/flow.h>
++#include <net/inet6_connection_sock.h>
++#include <net/inet6_hashtables.h>
++#include <net/inet_common.h>
++#include <net/ipv6.h>
++#include <net/ip6_checksum.h>
++#include <net/ip6_route.h>
++#include <net/mptcp.h>
++#include <net/mptcp_v6.h>
++#include <net/tcp.h>
++#include <net/transp_v6.h>
++
++__u32 mptcp_v6_get_nonce(const __be32 *saddr, const __be32 *daddr,
++			 __be16 sport, __be16 dport)
++{
++	u32 secret[MD5_MESSAGE_BYTES / 4];
++	u32 hash[MD5_DIGEST_WORDS];
++	u32 i;
++
++	memcpy(hash, saddr, 16);
++	for (i = 0; i < 4; i++)
++		secret[i] = mptcp_secret[i] + (__force u32)daddr[i];
++	secret[4] = mptcp_secret[4] +
++		    (((__force u16)sport << 16) + (__force u16)dport);
++	secret[5] = mptcp_seed++;
++	for (i = 6; i < MD5_MESSAGE_BYTES / 4; i++)
++		secret[i] = mptcp_secret[i];
++
++	md5_transform(hash, secret);
++
++	return hash[0];
++}
++
++u64 mptcp_v6_get_key(const __be32 *saddr, const __be32 *daddr,
++		     __be16 sport, __be16 dport)
++{
++	u32 secret[MD5_MESSAGE_BYTES / 4];
++	u32 hash[MD5_DIGEST_WORDS];
++	u32 i;
++
++	memcpy(hash, saddr, 16);
++	for (i = 0; i < 4; i++)
++		secret[i] = mptcp_secret[i] + (__force u32)daddr[i];
++	secret[4] = mptcp_secret[4] +
++		    (((__force u16)sport << 16) + (__force u16)dport);
++	secret[5] = mptcp_seed++;
++	for (i = 6; i < MD5_MESSAGE_BYTES / 4; i++)
++		secret[i] = mptcp_secret[i];
++
++	md5_transform(hash, secret);
++
++	return *((u64 *)hash);
++}
++
++static void mptcp_v6_reqsk_destructor(struct request_sock *req)
++{
++	mptcp_reqsk_destructor(req);
++
++	tcp_v6_reqsk_destructor(req);
++}
++
++static int mptcp_v6_init_req(struct request_sock *req, struct sock *sk,
++			     struct sk_buff *skb)
++{
++	tcp_request_sock_ipv6_ops.init_req(req, sk, skb);
++	mptcp_reqsk_init(req, skb);
++
++	return 0;
++}
++
++static int mptcp_v6_join_init_req(struct request_sock *req, struct sock *sk,
++				  struct sk_buff *skb)
++{
++	struct mptcp_request_sock *mtreq = mptcp_rsk(req);
++	struct mptcp_cb *mpcb = tcp_sk(sk)->mpcb;
++	union inet_addr addr;
++	int loc_id;
++	bool low_prio = false;
++
++	/* We need to do this as early as possible. Because, if we fail later
++	 * (e.g., get_local_id), then reqsk_free tries to remove the
++	 * request-socket from the htb in mptcp_hash_request_remove as pprev
++	 * may be different from NULL.
++	 */
++	mtreq->hash_entry.pprev = NULL;
++
++	tcp_request_sock_ipv6_ops.init_req(req, sk, skb);
++
++	mtreq->mptcp_loc_nonce = mptcp_v6_get_nonce(ipv6_hdr(skb)->saddr.s6_addr32,
++						    ipv6_hdr(skb)->daddr.s6_addr32,
++						    tcp_hdr(skb)->source,
++						    tcp_hdr(skb)->dest);
++	addr.in6 = inet_rsk(req)->ir_v6_loc_addr;
++	loc_id = mpcb->pm_ops->get_local_id(AF_INET6, &addr, sock_net(sk), &low_prio);
++	if (loc_id == -1)
++		return -1;
++	mtreq->loc_id = loc_id;
++	mtreq->low_prio = low_prio;
++
++	mptcp_join_reqsk_init(mpcb, req, skb);
++
++	return 0;
++}
++
++/* Similar to tcp6_request_sock_ops */
++struct request_sock_ops mptcp6_request_sock_ops __read_mostly = {
++	.family		=	AF_INET6,
++	.obj_size	=	sizeof(struct mptcp_request_sock),
++	.rtx_syn_ack	=	tcp_v6_rtx_synack,
++	.send_ack	=	tcp_v6_reqsk_send_ack,
++	.destructor	=	mptcp_v6_reqsk_destructor,
++	.send_reset	=	tcp_v6_send_reset,
++	.syn_ack_timeout =	tcp_syn_ack_timeout,
++};
++
++static void mptcp_v6_reqsk_queue_hash_add(struct sock *meta_sk,
++					  struct request_sock *req,
++					  const unsigned long timeout)
++{
++	const u32 h1 = inet6_synq_hash(&inet_rsk(req)->ir_v6_rmt_addr,
++				      inet_rsk(req)->ir_rmt_port,
++				      0, MPTCP_HASH_SIZE);
++	/* We cannot call inet6_csk_reqsk_queue_hash_add(), because we do not
++	 * want to reset the keepalive-timer (responsible for retransmitting
++	 * SYN/ACKs). We do not retransmit SYN/ACKs+MP_JOINs, because we cannot
++	 * overload the keepalive timer. Also, it's not a big deal, because the
++	 * third ACK of the MP_JOIN-handshake is sent in a reliable manner. So,
++	 * if the third ACK gets lost, the client will handle the retransmission
++	 * anyways. If our SYN/ACK gets lost, the client will retransmit the
++	 * SYN.
++	 */
++	struct inet_connection_sock *meta_icsk = inet_csk(meta_sk);
++	struct listen_sock *lopt = meta_icsk->icsk_accept_queue.listen_opt;
++	const u32 h2 = inet6_synq_hash(&inet_rsk(req)->ir_v6_rmt_addr,
++				      inet_rsk(req)->ir_rmt_port,
++				      lopt->hash_rnd, lopt->nr_table_entries);
++
++	reqsk_queue_hash_req(&meta_icsk->icsk_accept_queue, h2, req, timeout);
++	if (reqsk_queue_added(&meta_icsk->icsk_accept_queue) == 0)
++		mptcp_reset_synack_timer(meta_sk, timeout);
++
++	rcu_read_lock();
++	spin_lock(&mptcp_reqsk_hlock);
++	hlist_nulls_add_head_rcu(&mptcp_rsk(req)->hash_entry, &mptcp_reqsk_htb[h1]);
++	spin_unlock(&mptcp_reqsk_hlock);
++	rcu_read_unlock();
++}
++
++static int mptcp_v6_join_request(struct sock *meta_sk, struct sk_buff *skb)
++{
++	return tcp_conn_request(&mptcp6_request_sock_ops,
++				&mptcp_join_request_sock_ipv6_ops,
++				meta_sk, skb);
++}
++
++int mptcp_v6_do_rcv(struct sock *meta_sk, struct sk_buff *skb)
++{
++	const struct mptcp_cb *mpcb = tcp_sk(meta_sk)->mpcb;
++	struct sock *child, *rsk = NULL;
++	int ret;
++
++	if (!(TCP_SKB_CB(skb)->mptcp_flags & MPTCPHDR_JOIN)) {
++		struct tcphdr *th = tcp_hdr(skb);
++		const struct ipv6hdr *ip6h = ipv6_hdr(skb);
++		struct sock *sk;
++
++		sk = __inet6_lookup_established(sock_net(meta_sk),
++						&tcp_hashinfo,
++						&ip6h->saddr, th->source,
++						&ip6h->daddr, ntohs(th->dest),
++						inet6_iif(skb));
++
++		if (!sk) {
++			kfree_skb(skb);
++			return 0;
++		}
++		if (is_meta_sk(sk)) {
++			WARN("%s Did not find a sub-sk!\n", __func__);
++			kfree_skb(skb);
++			sock_put(sk);
++			return 0;
++		}
++
++		if (sk->sk_state == TCP_TIME_WAIT) {
++			inet_twsk_put(inet_twsk(sk));
++			kfree_skb(skb);
++			return 0;
++		}
++
++		ret = tcp_v6_do_rcv(sk, skb);
++		sock_put(sk);
++
++		return ret;
++	}
++	TCP_SKB_CB(skb)->mptcp_flags = 0;
++
++	/* Has been removed from the tk-table. Thus, no new subflows.
++	 *
++	 * Check for close-state is necessary, because we may have been closed
++	 * without passing by mptcp_close().
++	 *
++	 * When falling back, no new subflows are allowed either.
++	 */
++	if (meta_sk->sk_state == TCP_CLOSE || !tcp_sk(meta_sk)->inside_tk_table ||
++	    mpcb->infinite_mapping_rcv || mpcb->send_infinite_mapping)
++		goto reset_and_discard;
++
++	child = tcp_v6_hnd_req(meta_sk, skb);
++
++	if (!child)
++		goto discard;
++
++	if (child != meta_sk) {
++		sock_rps_save_rxhash(child, skb);
++		/* We don't call tcp_child_process here, because we hold
++		 * already the meta-sk-lock and are sure that it is not owned
++		 * by the user.
++		 */
++		ret = tcp_rcv_state_process(child, skb, tcp_hdr(skb), skb->len);
++		bh_unlock_sock(child);
++		sock_put(child);
++		if (ret) {
++			rsk = child;
++			goto reset_and_discard;
++		}
++	} else {
++		if (tcp_hdr(skb)->syn) {
++			mptcp_v6_join_request(meta_sk, skb);
++			goto discard;
++		}
++		goto reset_and_discard;
++	}
++	return 0;
++
++reset_and_discard:
++	if (reqsk_queue_len(&inet_csk(meta_sk)->icsk_accept_queue)) {
++		const struct tcphdr *th = tcp_hdr(skb);
++		struct request_sock **prev, *req;
++		/* If we end up here, it means we should not have matched on the
++		 * request-socket. But, because the request-sock queue is only
++		 * destroyed in mptcp_close, the socket may actually already be
++		 * in close-state (e.g., through shutdown()) while still having
++		 * pending request sockets.
++		 */
++		req = inet6_csk_search_req(meta_sk, &prev, th->source,
++					   &ipv6_hdr(skb)->saddr,
++					   &ipv6_hdr(skb)->daddr, inet6_iif(skb));
++		if (req) {
++			inet_csk_reqsk_queue_unlink(meta_sk, req, prev);
++			reqsk_queue_removed(&inet_csk(meta_sk)->icsk_accept_queue,
++					    req);
++			reqsk_free(req);
++		}
++	}
++
++	tcp_v6_send_reset(rsk, skb);
++discard:
++	kfree_skb(skb);
++	return 0;
++}
++
++/* After this, the ref count of the meta_sk associated with the request_sock
++ * is incremented. Thus it is the responsibility of the caller
++ * to call sock_put() when the reference is not needed anymore.
++ */
++struct sock *mptcp_v6_search_req(const __be16 rport, const struct in6_addr *raddr,
++				 const struct in6_addr *laddr, const struct net *net)
++{
++	const struct mptcp_request_sock *mtreq;
++	struct sock *meta_sk = NULL;
++	const struct hlist_nulls_node *node;
++	const u32 hash = inet6_synq_hash(raddr, rport, 0, MPTCP_HASH_SIZE);
++
++	rcu_read_lock();
++begin:
++	hlist_nulls_for_each_entry_rcu(mtreq, node, &mptcp_reqsk_htb[hash],
++				       hash_entry) {
++		struct inet_request_sock *treq = inet_rsk(rev_mptcp_rsk(mtreq));
++		meta_sk = mtreq->mptcp_mpcb->meta_sk;
++
++		if (inet_rsk(rev_mptcp_rsk(mtreq))->ir_rmt_port == rport &&
++		    rev_mptcp_rsk(mtreq)->rsk_ops->family == AF_INET6 &&
++		    ipv6_addr_equal(&treq->ir_v6_rmt_addr, raddr) &&
++		    ipv6_addr_equal(&treq->ir_v6_loc_addr, laddr) &&
++		    net_eq(net, sock_net(meta_sk)))
++			goto found;
++		meta_sk = NULL;
++	}
++	/* A request-socket is destroyed by RCU. So, it might have been recycled
++	 * and put into another hash-table list. So, after the lookup we may
++	 * end up in a different list. So, we may need to restart.
++	 *
++	 * See also the comment in __inet_lookup_established.
++	 */
++	if (get_nulls_value(node) != hash + MPTCP_REQSK_NULLS_BASE)
++		goto begin;
++
++found:
++	if (meta_sk && unlikely(!atomic_inc_not_zero(&meta_sk->sk_refcnt)))
++		meta_sk = NULL;
++	rcu_read_unlock();
++
++	return meta_sk;
++}
++
++/* Create a new IPv6 subflow.
++ *
++ * We are in user-context and meta-sock-lock is hold.
++ */
++int mptcp_init6_subsockets(struct sock *meta_sk, const struct mptcp_loc6 *loc,
++			   struct mptcp_rem6 *rem)
++{
++	struct tcp_sock *tp;
++	struct sock *sk;
++	struct sockaddr_in6 loc_in, rem_in;
++	struct socket sock;
++	int ret;
++
++	/** First, create and prepare the new socket */
++
++	sock.type = meta_sk->sk_socket->type;
++	sock.state = SS_UNCONNECTED;
++	sock.wq = meta_sk->sk_socket->wq;
++	sock.file = meta_sk->sk_socket->file;
++	sock.ops = NULL;
++
++	ret = inet6_create(sock_net(meta_sk), &sock, IPPROTO_TCP, 1);
++	if (unlikely(ret < 0)) {
++		mptcp_debug("%s inet6_create failed ret: %d\n", __func__, ret);
++		return ret;
++	}
++
++	sk = sock.sk;
++	tp = tcp_sk(sk);
++
++	/* All subsockets need the MPTCP-lock-class */
++	lockdep_set_class_and_name(&(sk)->sk_lock.slock, &meta_slock_key, "slock-AF_INET-MPTCP");
++	lockdep_init_map(&(sk)->sk_lock.dep_map, "sk_lock-AF_INET-MPTCP", &meta_key, 0);
++
++	if (mptcp_add_sock(meta_sk, sk, loc->loc6_id, rem->rem6_id, GFP_KERNEL))
++		goto error;
++
++	tp->mptcp->slave_sk = 1;
++	tp->mptcp->low_prio = loc->low_prio;
++
++	/* Initializing the timer for an MPTCP subflow */
++	setup_timer(&tp->mptcp->mptcp_ack_timer, mptcp_ack_handler, (unsigned long)sk);
++
++	/** Then, connect the socket to the peer */
++	loc_in.sin6_family = AF_INET6;
++	rem_in.sin6_family = AF_INET6;
++	loc_in.sin6_port = 0;
++	if (rem->port)
++		rem_in.sin6_port = rem->port;
++	else
++		rem_in.sin6_port = inet_sk(meta_sk)->inet_dport;
++	loc_in.sin6_addr = loc->addr;
++	rem_in.sin6_addr = rem->addr;
++
++	ret = sock.ops->bind(&sock, (struct sockaddr *)&loc_in, sizeof(struct sockaddr_in6));
++	if (ret < 0) {
++		mptcp_debug("%s: MPTCP subsocket bind()failed, error %d\n",
++			    __func__, ret);
++		goto error;
++	}
++
++	mptcp_debug("%s: token %#x pi %d src_addr:%pI6:%d dst_addr:%pI6:%d\n",
++		    __func__, tcp_sk(meta_sk)->mpcb->mptcp_loc_token,
++		    tp->mptcp->path_index, &loc_in.sin6_addr,
++		    ntohs(loc_in.sin6_port), &rem_in.sin6_addr,
++		    ntohs(rem_in.sin6_port));
++
++	if (tcp_sk(meta_sk)->mpcb->pm_ops->init_subsocket_v6)
++		tcp_sk(meta_sk)->mpcb->pm_ops->init_subsocket_v6(sk, rem->addr);
++
++	ret = sock.ops->connect(&sock, (struct sockaddr *)&rem_in,
++				sizeof(struct sockaddr_in6), O_NONBLOCK);
++	if (ret < 0 && ret != -EINPROGRESS) {
++		mptcp_debug("%s: MPTCP subsocket connect() failed, error %d\n",
++			    __func__, ret);
++		goto error;
++	}
++
++	sk_set_socket(sk, meta_sk->sk_socket);
++	sk->sk_wq = meta_sk->sk_wq;
++
++	return 0;
++
++error:
++	/* May happen if mptcp_add_sock fails first */
++	if (!mptcp(tp)) {
++		tcp_close(sk, 0);
++	} else {
++		local_bh_disable();
++		mptcp_sub_force_close(sk);
++		local_bh_enable();
++	}
++	return ret;
++}
++EXPORT_SYMBOL(mptcp_init6_subsockets);
++
++const struct inet_connection_sock_af_ops mptcp_v6_specific = {
++	.queue_xmit	   = inet6_csk_xmit,
++	.send_check	   = tcp_v6_send_check,
++	.rebuild_header	   = inet6_sk_rebuild_header,
++	.sk_rx_dst_set	   = inet6_sk_rx_dst_set,
++	.conn_request	   = mptcp_conn_request,
++	.syn_recv_sock	   = tcp_v6_syn_recv_sock,
++	.net_header_len	   = sizeof(struct ipv6hdr),
++	.net_frag_header_len = sizeof(struct frag_hdr),
++	.setsockopt	   = ipv6_setsockopt,
++	.getsockopt	   = ipv6_getsockopt,
++	.addr2sockaddr	   = inet6_csk_addr2sockaddr,
++	.sockaddr_len	   = sizeof(struct sockaddr_in6),
++	.bind_conflict	   = inet6_csk_bind_conflict,
++#ifdef CONFIG_COMPAT
++	.compat_setsockopt = compat_ipv6_setsockopt,
++	.compat_getsockopt = compat_ipv6_getsockopt,
++#endif
++};
++
++const struct inet_connection_sock_af_ops mptcp_v6_mapped = {
++	.queue_xmit	   = ip_queue_xmit,
++	.send_check	   = tcp_v4_send_check,
++	.rebuild_header	   = inet_sk_rebuild_header,
++	.sk_rx_dst_set	   = inet_sk_rx_dst_set,
++	.conn_request	   = mptcp_conn_request,
++	.syn_recv_sock	   = tcp_v6_syn_recv_sock,
++	.net_header_len	   = sizeof(struct iphdr),
++	.setsockopt	   = ipv6_setsockopt,
++	.getsockopt	   = ipv6_getsockopt,
++	.addr2sockaddr	   = inet6_csk_addr2sockaddr,
++	.sockaddr_len	   = sizeof(struct sockaddr_in6),
++	.bind_conflict	   = inet6_csk_bind_conflict,
++#ifdef CONFIG_COMPAT
++	.compat_setsockopt = compat_ipv6_setsockopt,
++	.compat_getsockopt = compat_ipv6_getsockopt,
++#endif
++};
++
++struct tcp_request_sock_ops mptcp_request_sock_ipv6_ops;
++struct tcp_request_sock_ops mptcp_join_request_sock_ipv6_ops;
++
++int mptcp_pm_v6_init(void)
++{
++	int ret = 0;
++	struct request_sock_ops *ops = &mptcp6_request_sock_ops;
++
++	mptcp_request_sock_ipv6_ops = tcp_request_sock_ipv6_ops;
++	mptcp_request_sock_ipv6_ops.init_req = mptcp_v6_init_req;
++
++	mptcp_join_request_sock_ipv6_ops = tcp_request_sock_ipv6_ops;
++	mptcp_join_request_sock_ipv6_ops.init_req = mptcp_v6_join_init_req;
++	mptcp_join_request_sock_ipv6_ops.queue_hash_add = mptcp_v6_reqsk_queue_hash_add;
++
++	ops->slab_name = kasprintf(GFP_KERNEL, "request_sock_%s", "MPTCP6");
++	if (ops->slab_name == NULL) {
++		ret = -ENOMEM;
++		goto out;
++	}
++
++	ops->slab = kmem_cache_create(ops->slab_name, ops->obj_size, 0,
++				      SLAB_DESTROY_BY_RCU|SLAB_HWCACHE_ALIGN,
++				      NULL);
++
++	if (ops->slab == NULL) {
++		ret =  -ENOMEM;
++		goto err_reqsk_create;
++	}
++
++out:
++	return ret;
++
++err_reqsk_create:
++	kfree(ops->slab_name);
++	ops->slab_name = NULL;
++	goto out;
++}
++
++void mptcp_pm_v6_undo(void)
++{
++	kmem_cache_destroy(mptcp6_request_sock_ops.slab);
++	kfree(mptcp6_request_sock_ops.slab_name);
++}
+diff --git a/net/mptcp/mptcp_ndiffports.c b/net/mptcp/mptcp_ndiffports.c
+new file mode 100644
+index 000000000000..6f5087983175
+--- /dev/null
++++ b/net/mptcp/mptcp_ndiffports.c
+@@ -0,0 +1,161 @@
++#include <linux/module.h>
++
++#include <net/mptcp.h>
++#include <net/mptcp_v4.h>
++
++#if IS_ENABLED(CONFIG_IPV6)
++#include <net/mptcp_v6.h>
++#endif
++
++struct ndiffports_priv {
++	/* Worker struct for subflow establishment */
++	struct work_struct subflow_work;
++
++	struct mptcp_cb *mpcb;
++};
++
++static int num_subflows __read_mostly = 2;
++module_param(num_subflows, int, 0644);
++MODULE_PARM_DESC(num_subflows, "choose the number of subflows per MPTCP connection");
++
++/**
++ * Create all new subflows, by doing calls to mptcp_initX_subsockets
++ *
++ * This function uses a goto next_subflow, to allow releasing the lock between
++ * new subflows and giving other processes a chance to do some work on the
++ * socket and potentially finishing the communication.
++ **/
++static void create_subflow_worker(struct work_struct *work)
++{
++	const struct ndiffports_priv *pm_priv = container_of(work,
++						     struct ndiffports_priv,
++						     subflow_work);
++	struct mptcp_cb *mpcb = pm_priv->mpcb;
++	struct sock *meta_sk = mpcb->meta_sk;
++	int iter = 0;
++
++next_subflow:
++	if (iter) {
++		release_sock(meta_sk);
++		mutex_unlock(&mpcb->mpcb_mutex);
++
++		cond_resched();
++	}
++	mutex_lock(&mpcb->mpcb_mutex);
++	lock_sock_nested(meta_sk, SINGLE_DEPTH_NESTING);
++
++	iter++;
++
++	if (sock_flag(meta_sk, SOCK_DEAD))
++		goto exit;
++
++	if (mpcb->master_sk &&
++	    !tcp_sk(mpcb->master_sk)->mptcp->fully_established)
++		goto exit;
++
++	if (num_subflows > iter && num_subflows > mpcb->cnt_subflows) {
++		if (meta_sk->sk_family == AF_INET ||
++		    mptcp_v6_is_v4_mapped(meta_sk)) {
++			struct mptcp_loc4 loc;
++			struct mptcp_rem4 rem;
++
++			loc.addr.s_addr = inet_sk(meta_sk)->inet_saddr;
++			loc.loc4_id = 0;
++			loc.low_prio = 0;
++
++			rem.addr.s_addr = inet_sk(meta_sk)->inet_daddr;
++			rem.port = inet_sk(meta_sk)->inet_dport;
++			rem.rem4_id = 0; /* Default 0 */
++
++			mptcp_init4_subsockets(meta_sk, &loc, &rem);
++		} else {
++#if IS_ENABLED(CONFIG_IPV6)
++			struct mptcp_loc6 loc;
++			struct mptcp_rem6 rem;
++
++			loc.addr = inet6_sk(meta_sk)->saddr;
++			loc.loc6_id = 0;
++			loc.low_prio = 0;
++
++			rem.addr = meta_sk->sk_v6_daddr;
++			rem.port = inet_sk(meta_sk)->inet_dport;
++			rem.rem6_id = 0; /* Default 0 */
++
++			mptcp_init6_subsockets(meta_sk, &loc, &rem);
++#endif
++		}
++		goto next_subflow;
++	}
++
++exit:
++	release_sock(meta_sk);
++	mutex_unlock(&mpcb->mpcb_mutex);
++	sock_put(meta_sk);
++}
++
++static void ndiffports_new_session(const struct sock *meta_sk)
++{
++	struct mptcp_cb *mpcb = tcp_sk(meta_sk)->mpcb;
++	struct ndiffports_priv *fmp = (struct ndiffports_priv *)&mpcb->mptcp_pm[0];
++
++	/* Initialize workqueue-struct */
++	INIT_WORK(&fmp->subflow_work, create_subflow_worker);
++	fmp->mpcb = mpcb;
++}
++
++static void ndiffports_create_subflows(struct sock *meta_sk)
++{
++	const struct mptcp_cb *mpcb = tcp_sk(meta_sk)->mpcb;
++	struct ndiffports_priv *pm_priv = (struct ndiffports_priv *)&mpcb->mptcp_pm[0];
++
++	if (mpcb->infinite_mapping_snd || mpcb->infinite_mapping_rcv ||
++	    mpcb->send_infinite_mapping ||
++	    mpcb->server_side || sock_flag(meta_sk, SOCK_DEAD))
++		return;
++
++	if (!work_pending(&pm_priv->subflow_work)) {
++		sock_hold(meta_sk);
++		queue_work(mptcp_wq, &pm_priv->subflow_work);
++	}
++}
++
++static int ndiffports_get_local_id(sa_family_t family, union inet_addr *addr,
++				   struct net *net, bool *low_prio)
++{
++	return 0;
++}
++
++static struct mptcp_pm_ops ndiffports __read_mostly = {
++	.new_session = ndiffports_new_session,
++	.fully_established = ndiffports_create_subflows,
++	.get_local_id = ndiffports_get_local_id,
++	.name = "ndiffports",
++	.owner = THIS_MODULE,
++};
++
++/* General initialization of MPTCP_PM */
++static int __init ndiffports_register(void)
++{
++	BUILD_BUG_ON(sizeof(struct ndiffports_priv) > MPTCP_PM_SIZE);
++
++	if (mptcp_register_path_manager(&ndiffports))
++		goto exit;
++
++	return 0;
++
++exit:
++	return -1;
++}
++
++static void ndiffports_unregister(void)
++{
++	mptcp_unregister_path_manager(&ndiffports);
++}
++
++module_init(ndiffports_register);
++module_exit(ndiffports_unregister);
++
++MODULE_AUTHOR("Christoph Paasch");
++MODULE_LICENSE("GPL");
++MODULE_DESCRIPTION("NDIFF-PORTS MPTCP");
++MODULE_VERSION("0.88");
+diff --git a/net/mptcp/mptcp_ofo_queue.c b/net/mptcp/mptcp_ofo_queue.c
+new file mode 100644
+index 000000000000..ec4e98622637
+--- /dev/null
++++ b/net/mptcp/mptcp_ofo_queue.c
+@@ -0,0 +1,295 @@
++/*
++ *	MPTCP implementation - Fast algorithm for MPTCP meta-reordering
++ *
++ *	Initial Design & Implementation:
++ *	Sébastien Barré <sebastien.barre@×××××××××.be>
++ *
++ *	Current Maintainer & Author:
++ *	Christoph Paasch <christoph.paasch@×××××××××.be>
++ *
++ *	Additional authors:
++ *	Jaakko Korkeaniemi <jaakko.korkeaniemi@×××××.fi>
++ *	Gregory Detal <gregory.detal@×××××××××.be>
++ *	Fabien Duchêne <fabien.duchene@×××××××××.be>
++ *	Andreas Seelinger <Andreas.Seelinger@×××××××××××.de>
++ *	Lavkesh Lahngir <lavkesh51@×××××.com>
++ *	Andreas Ripke <ripke@××××××.eu>
++ *	Vlad Dogaru <vlad.dogaru@×××××.com>
++ *	Octavian Purdila <octavian.purdila@×××××.com>
++ *	John Ronan <jronan@××××.org>
++ *	Catalin Nicutar <catalin.nicutar@×××××.com>
++ *	Brandon Heller <brandonh@××××××××.edu>
++ *
++ *	This program is free software; you can redistribute it and/or
++ *      modify it under the terms of the GNU General Public License
++ *      as published by the Free Software Foundation; either version
++ *      2 of the License, or (at your option) any later version.
++ */
++
++#include <linux/skbuff.h>
++#include <linux/slab.h>
++#include <net/tcp.h>
++#include <net/mptcp.h>
++
++void mptcp_remove_shortcuts(const struct mptcp_cb *mpcb,
++			    const struct sk_buff *skb)
++{
++	struct tcp_sock *tp;
++
++	mptcp_for_each_tp(mpcb, tp) {
++		if (tp->mptcp->shortcut_ofoqueue == skb) {
++			tp->mptcp->shortcut_ofoqueue = NULL;
++			return;
++		}
++	}
++}
++
++/* Does 'skb' fits after 'here' in the queue 'head' ?
++ * If yes, we queue it and return 1
++ */
++static int mptcp_ofo_queue_after(struct sk_buff_head *head,
++				 struct sk_buff *skb, struct sk_buff *here,
++				 const struct tcp_sock *tp)
++{
++	struct sock *meta_sk = tp->meta_sk;
++	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
++	u32 seq = TCP_SKB_CB(skb)->seq;
++	u32 end_seq = TCP_SKB_CB(skb)->end_seq;
++
++	/* We want to queue skb after here, thus seq >= end_seq */
++	if (before(seq, TCP_SKB_CB(here)->end_seq))
++		return 0;
++
++	if (seq == TCP_SKB_CB(here)->end_seq) {
++		bool fragstolen = false;
++
++		if (!tcp_try_coalesce(meta_sk, here, skb, &fragstolen)) {
++			__skb_queue_after(&meta_tp->out_of_order_queue, here, skb);
++			return 1;
++		} else {
++			kfree_skb_partial(skb, fragstolen);
++			return -1;
++		}
++	}
++
++	/* If here is the last one, we can always queue it */
++	if (skb_queue_is_last(head, here)) {
++		__skb_queue_after(head, here, skb);
++		return 1;
++	} else {
++		struct sk_buff *skb1 = skb_queue_next(head, here);
++		/* It's not the last one, but does it fits between 'here' and
++		 * the one after 'here' ? Thus, does end_seq <= after_here->seq
++		 */
++		if (!after(end_seq, TCP_SKB_CB(skb1)->seq)) {
++			__skb_queue_after(head, here, skb);
++			return 1;
++		}
++	}
++
++	return 0;
++}
++
++static void try_shortcut(struct sk_buff *shortcut, struct sk_buff *skb,
++			 struct sk_buff_head *head, struct tcp_sock *tp)
++{
++	struct sock *meta_sk = tp->meta_sk;
++	struct tcp_sock *tp_it, *meta_tp = tcp_sk(meta_sk);
++	struct mptcp_cb *mpcb = meta_tp->mpcb;
++	struct sk_buff *skb1, *best_shortcut = NULL;
++	u32 seq = TCP_SKB_CB(skb)->seq;
++	u32 end_seq = TCP_SKB_CB(skb)->end_seq;
++	u32 distance = 0xffffffff;
++
++	/* First, check the tp's shortcut */
++	if (!shortcut) {
++		if (skb_queue_empty(head)) {
++			__skb_queue_head(head, skb);
++			goto end;
++		}
++	} else {
++		int ret = mptcp_ofo_queue_after(head, skb, shortcut, tp);
++		/* Does the tp's shortcut is a hit? If yes, we insert. */
++
++		if (ret) {
++			skb = (ret > 0) ? skb : NULL;
++			goto end;
++		}
++	}
++
++	/* Check the shortcuts of the other subsockets. */
++	mptcp_for_each_tp(mpcb, tp_it) {
++		shortcut = tp_it->mptcp->shortcut_ofoqueue;
++		/* Can we queue it here? If yes, do so! */
++		if (shortcut) {
++			int ret = mptcp_ofo_queue_after(head, skb, shortcut, tp);
++
++			if (ret) {
++				skb = (ret > 0) ? skb : NULL;
++				goto end;
++			}
++		}
++
++		/* Could not queue it, check if we are close.
++		 * We are looking for a shortcut, close enough to seq to
++		 * set skb1 prematurely and thus improve the subsequent lookup,
++		 * which tries to find a skb1 so that skb1->seq <= seq.
++		 *
++		 * So, here we only take shortcuts, whose shortcut->seq > seq,
++		 * and minimize the distance between shortcut->seq and seq and
++		 * set best_shortcut to this one with the minimal distance.
++		 *
++		 * That way, the subsequent while-loop is shortest.
++		 */
++		if (shortcut && after(TCP_SKB_CB(shortcut)->seq, seq)) {
++			/* Are we closer than the current best shortcut? */
++			if ((u32)(TCP_SKB_CB(shortcut)->seq - seq) < distance) {
++				distance = (u32)(TCP_SKB_CB(shortcut)->seq - seq);
++				best_shortcut = shortcut;
++			}
++		}
++	}
++
++	if (best_shortcut)
++		skb1 = best_shortcut;
++	else
++		skb1 = skb_peek_tail(head);
++
++	if (seq == TCP_SKB_CB(skb1)->end_seq) {
++		bool fragstolen = false;
++
++		if (!tcp_try_coalesce(meta_sk, skb1, skb, &fragstolen)) {
++			__skb_queue_after(&meta_tp->out_of_order_queue, skb1, skb);
++		} else {
++			kfree_skb_partial(skb, fragstolen);
++			skb = NULL;
++		}
++
++		goto end;
++	}
++
++	/* Find the insertion point, starting from best_shortcut if available.
++	 *
++	 * Inspired from tcp_data_queue_ofo.
++	 */
++	while (1) {
++		/* skb1->seq <= seq */
++		if (!after(TCP_SKB_CB(skb1)->seq, seq))
++			break;
++		if (skb_queue_is_first(head, skb1)) {
++			skb1 = NULL;
++			break;
++		}
++		skb1 = skb_queue_prev(head, skb1);
++	}
++
++	/* Do skb overlap to previous one? */
++	if (skb1 && before(seq, TCP_SKB_CB(skb1)->end_seq)) {
++		if (!after(end_seq, TCP_SKB_CB(skb1)->end_seq)) {
++			/* All the bits are present. */
++			__kfree_skb(skb);
++			skb = NULL;
++			goto end;
++		}
++		if (seq == TCP_SKB_CB(skb1)->seq) {
++			if (skb_queue_is_first(head, skb1))
++				skb1 = NULL;
++			else
++				skb1 = skb_queue_prev(head, skb1);
++		}
++	}
++	if (!skb1)
++		__skb_queue_head(head, skb);
++	else
++		__skb_queue_after(head, skb1, skb);
++
++	/* And clean segments covered by new one as whole. */
++	while (!skb_queue_is_last(head, skb)) {
++		skb1 = skb_queue_next(head, skb);
++
++		if (!after(end_seq, TCP_SKB_CB(skb1)->seq))
++			break;
++
++		__skb_unlink(skb1, head);
++		mptcp_remove_shortcuts(mpcb, skb1);
++		__kfree_skb(skb1);
++	}
++
++end:
++	if (skb) {
++		skb_set_owner_r(skb, meta_sk);
++		tp->mptcp->shortcut_ofoqueue = skb;
++	}
++
++	return;
++}
++
++/**
++ * @sk: the subflow that received this skb.
++ */
++void mptcp_add_meta_ofo_queue(const struct sock *meta_sk, struct sk_buff *skb,
++			      struct sock *sk)
++{
++	struct tcp_sock *tp = tcp_sk(sk);
++
++	try_shortcut(tp->mptcp->shortcut_ofoqueue, skb,
++		     &tcp_sk(meta_sk)->out_of_order_queue, tp);
++}
++
++bool mptcp_prune_ofo_queue(struct sock *sk)
++{
++	struct tcp_sock *tp	= tcp_sk(sk);
++	bool res		= false;
++
++	if (!skb_queue_empty(&tp->out_of_order_queue)) {
++		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_OFOPRUNED);
++		mptcp_purge_ofo_queue(tp);
++
++		/* No sack at the mptcp-level */
++		sk_mem_reclaim(sk);
++		res = true;
++	}
++
++	return res;
++}
++
++void mptcp_ofo_queue(struct sock *meta_sk)
++{
++	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
++	struct sk_buff *skb;
++
++	while ((skb = skb_peek(&meta_tp->out_of_order_queue)) != NULL) {
++		u32 old_rcv_nxt = meta_tp->rcv_nxt;
++		if (after(TCP_SKB_CB(skb)->seq, meta_tp->rcv_nxt))
++			break;
++
++		if (!after(TCP_SKB_CB(skb)->end_seq, meta_tp->rcv_nxt)) {
++			__skb_unlink(skb, &meta_tp->out_of_order_queue);
++			mptcp_remove_shortcuts(meta_tp->mpcb, skb);
++			__kfree_skb(skb);
++			continue;
++		}
++
++		__skb_unlink(skb, &meta_tp->out_of_order_queue);
++		mptcp_remove_shortcuts(meta_tp->mpcb, skb);
++
++		__skb_queue_tail(&meta_sk->sk_receive_queue, skb);
++		meta_tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
++		mptcp_check_rcvseq_wrap(meta_tp, old_rcv_nxt);
++
++		if (tcp_hdr(skb)->fin)
++			mptcp_fin(meta_sk);
++	}
++}
++
++void mptcp_purge_ofo_queue(struct tcp_sock *meta_tp)
++{
++	struct sk_buff_head *head = &meta_tp->out_of_order_queue;
++	struct sk_buff *skb, *tmp;
++
++	skb_queue_walk_safe(head, skb, tmp) {
++		__skb_unlink(skb, head);
++		mptcp_remove_shortcuts(meta_tp->mpcb, skb);
++		kfree_skb(skb);
++	}
++}
+diff --git a/net/mptcp/mptcp_olia.c b/net/mptcp/mptcp_olia.c
+new file mode 100644
+index 000000000000..53f5c43bb488
+--- /dev/null
++++ b/net/mptcp/mptcp_olia.c
+@@ -0,0 +1,311 @@
++/*
++ * MPTCP implementation - OPPORTUNISTIC LINKED INCREASES CONGESTION CONTROL:
++ *
++ * Algorithm design:
++ * Ramin Khalili <ramin.khalili@××××.ch>
++ * Nicolas Gast <nicolas.gast@××××.ch>
++ * Jean-Yves Le Boudec <jean-yves.leboudec@××××.ch>
++ *
++ * Implementation:
++ * Ramin Khalili <ramin.khalili@××××.ch>
++ *
++ * Ported to the official MPTCP-kernel:
++ * Christoph Paasch <christoph.paasch@×××××××××.be>
++ *
++ * This program is free software; you can redistribute it and/or
++ * modify it under the terms of the GNU General Public License
++ * as published by the Free Software Foundation; either version
++ * 2 of the License, or (at your option) any later version.
++ */
++
++
++#include <net/tcp.h>
++#include <net/mptcp.h>
++
++#include <linux/module.h>
++
++static int scale = 10;
++
++struct mptcp_olia {
++	u32	mptcp_loss1;
++	u32	mptcp_loss2;
++	u32	mptcp_loss3;
++	int	epsilon_num;
++	u32	epsilon_den;
++	int	mptcp_snd_cwnd_cnt;
++};
++
++static inline int mptcp_olia_sk_can_send(const struct sock *sk)
++{
++	return mptcp_sk_can_send(sk) && tcp_sk(sk)->srtt_us;
++}
++
++static inline u64 mptcp_olia_scale(u64 val, int scale)
++{
++	return (u64) val << scale;
++}
++
++/* take care of artificially inflate (see RFC5681)
++ * of cwnd during fast-retransmit phase
++ */
++static u32 mptcp_get_crt_cwnd(struct sock *sk)
++{
++	const struct inet_connection_sock *icsk = inet_csk(sk);
++
++	if (icsk->icsk_ca_state == TCP_CA_Recovery)
++		return tcp_sk(sk)->snd_ssthresh;
++	else
++		return tcp_sk(sk)->snd_cwnd;
++}
++
++/* return the dominator of the first term of  the increasing term */
++static u64 mptcp_get_rate(const struct mptcp_cb *mpcb , u32 path_rtt)
++{
++	struct sock *sk;
++	u64 rate = 1; /* We have to avoid a zero-rate because it is used as a divisor */
++
++	mptcp_for_each_sk(mpcb, sk) {
++		struct tcp_sock *tp = tcp_sk(sk);
++		u64 scaled_num;
++		u32 tmp_cwnd;
++
++		if (!mptcp_olia_sk_can_send(sk))
++			continue;
++
++		tmp_cwnd = mptcp_get_crt_cwnd(sk);
++		scaled_num = mptcp_olia_scale(tmp_cwnd, scale) * path_rtt;
++		rate += div_u64(scaled_num , tp->srtt_us);
++	}
++	rate *= rate;
++	return rate;
++}
++
++/* find the maximum cwnd, used to find set M */
++static u32 mptcp_get_max_cwnd(const struct mptcp_cb *mpcb)
++{
++	struct sock *sk;
++	u32 best_cwnd = 0;
++
++	mptcp_for_each_sk(mpcb, sk) {
++		u32 tmp_cwnd;
++
++		if (!mptcp_olia_sk_can_send(sk))
++			continue;
++
++		tmp_cwnd = mptcp_get_crt_cwnd(sk);
++		if (tmp_cwnd > best_cwnd)
++			best_cwnd = tmp_cwnd;
++	}
++	return best_cwnd;
++}
++
++static void mptcp_get_epsilon(const struct mptcp_cb *mpcb)
++{
++	struct mptcp_olia *ca;
++	struct tcp_sock *tp;
++	struct sock *sk;
++	u64 tmp_int, tmp_rtt, best_int = 0, best_rtt = 1;
++	u32 max_cwnd = 1, best_cwnd = 1, tmp_cwnd;
++	u8 M = 0, B_not_M = 0;
++
++	/* TODO - integrate this in the following loop - we just want to iterate once */
++
++	max_cwnd = mptcp_get_max_cwnd(mpcb);
++
++	/* find the best path */
++	mptcp_for_each_sk(mpcb, sk) {
++		tp = tcp_sk(sk);
++		ca = inet_csk_ca(sk);
++
++		if (!mptcp_olia_sk_can_send(sk))
++			continue;
++
++		tmp_rtt = (u64)tp->srtt_us * tp->srtt_us;
++		/* TODO - check here and rename variables */
++		tmp_int = max(ca->mptcp_loss3 - ca->mptcp_loss2,
++			      ca->mptcp_loss2 - ca->mptcp_loss1);
++
++		tmp_cwnd = mptcp_get_crt_cwnd(sk);
++		if ((u64)tmp_int * best_rtt >= (u64)best_int * tmp_rtt) {
++			best_rtt = tmp_rtt;
++			best_int = tmp_int;
++			best_cwnd = tmp_cwnd;
++		}
++	}
++
++	/* TODO - integrate this here in mptcp_get_max_cwnd and in the previous loop */
++	/* find the size of M and B_not_M */
++	mptcp_for_each_sk(mpcb, sk) {
++		tp = tcp_sk(sk);
++		ca = inet_csk_ca(sk);
++
++		if (!mptcp_olia_sk_can_send(sk))
++			continue;
++
++		tmp_cwnd = mptcp_get_crt_cwnd(sk);
++		if (tmp_cwnd == max_cwnd) {
++			M++;
++		} else {
++			tmp_rtt = (u64)tp->srtt_us * tp->srtt_us;
++			tmp_int = max(ca->mptcp_loss3 - ca->mptcp_loss2,
++				      ca->mptcp_loss2 - ca->mptcp_loss1);
++
++			if ((u64)tmp_int * best_rtt == (u64)best_int * tmp_rtt)
++				B_not_M++;
++		}
++	}
++
++	/* check if the path is in M or B_not_M and set the value of epsilon accordingly */
++	mptcp_for_each_sk(mpcb, sk) {
++		tp = tcp_sk(sk);
++		ca = inet_csk_ca(sk);
++
++		if (!mptcp_olia_sk_can_send(sk))
++			continue;
++
++		if (B_not_M == 0) {
++			ca->epsilon_num = 0;
++			ca->epsilon_den = 1;
++		} else {
++			tmp_rtt = (u64)tp->srtt_us * tp->srtt_us;
++			tmp_int = max(ca->mptcp_loss3 - ca->mptcp_loss2,
++				      ca->mptcp_loss2 - ca->mptcp_loss1);
++			tmp_cwnd = mptcp_get_crt_cwnd(sk);
++
++			if (tmp_cwnd < max_cwnd &&
++			    (u64)tmp_int * best_rtt == (u64)best_int * tmp_rtt) {
++				ca->epsilon_num = 1;
++				ca->epsilon_den = mpcb->cnt_established * B_not_M;
++			} else if (tmp_cwnd == max_cwnd) {
++				ca->epsilon_num = -1;
++				ca->epsilon_den = mpcb->cnt_established  * M;
++			} else {
++				ca->epsilon_num = 0;
++				ca->epsilon_den = 1;
++			}
++		}
++	}
++}
++
++/* setting the initial values */
++static void mptcp_olia_init(struct sock *sk)
++{
++	const struct tcp_sock *tp = tcp_sk(sk);
++	struct mptcp_olia *ca = inet_csk_ca(sk);
++
++	if (mptcp(tp)) {
++		ca->mptcp_loss1 = tp->snd_una;
++		ca->mptcp_loss2 = tp->snd_una;
++		ca->mptcp_loss3 = tp->snd_una;
++		ca->mptcp_snd_cwnd_cnt = 0;
++		ca->epsilon_num = 0;
++		ca->epsilon_den = 1;
++	}
++}
++
++/* updating inter-loss distance and ssthresh */
++static void mptcp_olia_set_state(struct sock *sk, u8 new_state)
++{
++	if (!mptcp(tcp_sk(sk)))
++		return;
++
++	if (new_state == TCP_CA_Loss ||
++	    new_state == TCP_CA_Recovery || new_state == TCP_CA_CWR) {
++		struct mptcp_olia *ca = inet_csk_ca(sk);
++
++		if (ca->mptcp_loss3 != ca->mptcp_loss2 &&
++		    !inet_csk(sk)->icsk_retransmits) {
++			ca->mptcp_loss1 = ca->mptcp_loss2;
++			ca->mptcp_loss2 = ca->mptcp_loss3;
++		}
++	}
++}
++
++/* main algorithm */
++static void mptcp_olia_cong_avoid(struct sock *sk, u32 ack, u32 acked)
++{
++	struct tcp_sock *tp = tcp_sk(sk);
++	struct mptcp_olia *ca = inet_csk_ca(sk);
++	const struct mptcp_cb *mpcb = tp->mpcb;
++
++	u64 inc_num, inc_den, rate, cwnd_scaled;
++
++	if (!mptcp(tp)) {
++		tcp_reno_cong_avoid(sk, ack, acked);
++		return;
++	}
++
++	ca->mptcp_loss3 = tp->snd_una;
++
++	if (!tcp_is_cwnd_limited(sk))
++		return;
++
++	/* slow start if it is in the safe area */
++	if (tp->snd_cwnd <= tp->snd_ssthresh) {
++		tcp_slow_start(tp, acked);
++		return;
++	}
++
++	mptcp_get_epsilon(mpcb);
++	rate = mptcp_get_rate(mpcb, tp->srtt_us);
++	cwnd_scaled = mptcp_olia_scale(tp->snd_cwnd, scale);
++	inc_den = ca->epsilon_den * tp->snd_cwnd * rate ? : 1;
++
++	/* calculate the increasing term, scaling is used to reduce the rounding effect */
++	if (ca->epsilon_num == -1) {
++		if (ca->epsilon_den * cwnd_scaled * cwnd_scaled < rate) {
++			inc_num = rate - ca->epsilon_den *
++				cwnd_scaled * cwnd_scaled;
++			ca->mptcp_snd_cwnd_cnt -= div64_u64(
++			    mptcp_olia_scale(inc_num , scale) , inc_den);
++		} else {
++			inc_num = ca->epsilon_den *
++			    cwnd_scaled * cwnd_scaled - rate;
++			ca->mptcp_snd_cwnd_cnt += div64_u64(
++			    mptcp_olia_scale(inc_num , scale) , inc_den);
++		}
++	} else {
++		inc_num = ca->epsilon_num * rate +
++		    ca->epsilon_den * cwnd_scaled * cwnd_scaled;
++		ca->mptcp_snd_cwnd_cnt += div64_u64(
++		    mptcp_olia_scale(inc_num , scale) , inc_den);
++	}
++
++
++	if (ca->mptcp_snd_cwnd_cnt >= (1 << scale) - 1) {
++		if (tp->snd_cwnd < tp->snd_cwnd_clamp)
++			tp->snd_cwnd++;
++		ca->mptcp_snd_cwnd_cnt = 0;
++	} else if (ca->mptcp_snd_cwnd_cnt <= 0 - (1 << scale) + 1) {
++		tp->snd_cwnd = max((int) 1 , (int) tp->snd_cwnd - 1);
++		ca->mptcp_snd_cwnd_cnt = 0;
++	}
++}
++
++static struct tcp_congestion_ops mptcp_olia = {
++	.init		= mptcp_olia_init,
++	.ssthresh	= tcp_reno_ssthresh,
++	.cong_avoid	= mptcp_olia_cong_avoid,
++	.set_state	= mptcp_olia_set_state,
++	.owner		= THIS_MODULE,
++	.name		= "olia",
++};
++
++static int __init mptcp_olia_register(void)
++{
++	BUILD_BUG_ON(sizeof(struct mptcp_olia) > ICSK_CA_PRIV_SIZE);
++	return tcp_register_congestion_control(&mptcp_olia);
++}
++
++static void __exit mptcp_olia_unregister(void)
++{
++	tcp_unregister_congestion_control(&mptcp_olia);
++}
++
++module_init(mptcp_olia_register);
++module_exit(mptcp_olia_unregister);
++
++MODULE_AUTHOR("Ramin Khalili, Nicolas Gast, Jean-Yves Le Boudec");
++MODULE_LICENSE("GPL");
++MODULE_DESCRIPTION("MPTCP COUPLED CONGESTION CONTROL");
++MODULE_VERSION("0.1");
+diff --git a/net/mptcp/mptcp_output.c b/net/mptcp/mptcp_output.c
+new file mode 100644
+index 000000000000..400ea254c078
+--- /dev/null
++++ b/net/mptcp/mptcp_output.c
+@@ -0,0 +1,1743 @@
++/*
++ *	MPTCP implementation - Sending side
++ *
++ *	Initial Design & Implementation:
++ *	Sébastien Barré <sebastien.barre@×××××××××.be>
++ *
++ *	Current Maintainer & Author:
++ *	Christoph Paasch <christoph.paasch@×××××××××.be>
++ *
++ *	Additional authors:
++ *	Jaakko Korkeaniemi <jaakko.korkeaniemi@×××××.fi>
++ *	Gregory Detal <gregory.detal@×××××××××.be>
++ *	Fabien Duchêne <fabien.duchene@×××××××××.be>
++ *	Andreas Seelinger <Andreas.Seelinger@×××××××××××.de>
++ *	Lavkesh Lahngir <lavkesh51@×××××.com>
++ *	Andreas Ripke <ripke@××××××.eu>
++ *	Vlad Dogaru <vlad.dogaru@×××××.com>
++ *	Octavian Purdila <octavian.purdila@×××××.com>
++ *	John Ronan <jronan@××××.org>
++ *	Catalin Nicutar <catalin.nicutar@×××××.com>
++ *	Brandon Heller <brandonh@××××××××.edu>
++ *
++ *
++ *	This program is free software; you can redistribute it and/or
++ *      modify it under the terms of the GNU General Public License
++ *      as published by the Free Software Foundation; either version
++ *      2 of the License, or (at your option) any later version.
++ */
++
++#include <linux/kconfig.h>
++#include <linux/skbuff.h>
++#include <linux/tcp.h>
++
++#include <net/mptcp.h>
++#include <net/mptcp_v4.h>
++#include <net/mptcp_v6.h>
++#include <net/sock.h>
++
++static const int mptcp_dss_len = MPTCP_SUB_LEN_DSS_ALIGN +
++				 MPTCP_SUB_LEN_ACK_ALIGN +
++				 MPTCP_SUB_LEN_SEQ_ALIGN;
++
++static inline int mptcp_sub_len_remove_addr(u16 bitfield)
++{
++	unsigned int c;
++	for (c = 0; bitfield; c++)
++		bitfield &= bitfield - 1;
++	return MPTCP_SUB_LEN_REMOVE_ADDR + c - 1;
++}
++
++int mptcp_sub_len_remove_addr_align(u16 bitfield)
++{
++	return ALIGN(mptcp_sub_len_remove_addr(bitfield), 4);
++}
++EXPORT_SYMBOL(mptcp_sub_len_remove_addr_align);
++
++/* get the data-seq and end-data-seq and store them again in the
++ * tcp_skb_cb
++ */
++static int mptcp_reconstruct_mapping(struct sk_buff *skb)
++{
++	const struct mp_dss *mpdss = (struct mp_dss *)TCP_SKB_CB(skb)->dss;
++	u32 *p32;
++	u16 *p16;
++
++	if (!mpdss->M)
++		return 1;
++
++	/* Move the pointer to the data-seq */
++	p32 = (u32 *)mpdss;
++	p32++;
++	if (mpdss->A) {
++		p32++;
++		if (mpdss->a)
++			p32++;
++	}
++
++	TCP_SKB_CB(skb)->seq = ntohl(*p32);
++
++	/* Get the data_len to calculate the end_data_seq */
++	p32++;
++	p32++;
++	p16 = (u16 *)p32;
++	TCP_SKB_CB(skb)->end_seq = ntohs(*p16) + TCP_SKB_CB(skb)->seq;
++
++	return 0;
++}
++
++static void mptcp_find_and_set_pathmask(const struct sock *meta_sk, struct sk_buff *skb)
++{
++	struct sk_buff *skb_it;
++
++	skb_it = tcp_write_queue_head(meta_sk);
++
++	tcp_for_write_queue_from(skb_it, meta_sk) {
++		if (skb_it == tcp_send_head(meta_sk))
++			break;
++
++		if (TCP_SKB_CB(skb_it)->seq == TCP_SKB_CB(skb)->seq) {
++			TCP_SKB_CB(skb)->path_mask = TCP_SKB_CB(skb_it)->path_mask;
++			break;
++		}
++	}
++}
++
++/* Reinject data from one TCP subflow to the meta_sk. If sk == NULL, we are
++ * coming from the meta-retransmit-timer
++ */
++static void __mptcp_reinject_data(struct sk_buff *orig_skb, struct sock *meta_sk,
++				  struct sock *sk, int clone_it)
++{
++	struct sk_buff *skb, *skb1;
++	const struct tcp_sock *meta_tp = tcp_sk(meta_sk);
++	struct mptcp_cb *mpcb = meta_tp->mpcb;
++	u32 seq, end_seq;
++
++	if (clone_it) {
++		/* pskb_copy is necessary here, because the TCP/IP-headers
++		 * will be changed when it's going to be reinjected on another
++		 * subflow.
++		 */
++		skb = pskb_copy_for_clone(orig_skb, GFP_ATOMIC);
++	} else {
++		__skb_unlink(orig_skb, &sk->sk_write_queue);
++		sock_set_flag(sk, SOCK_QUEUE_SHRUNK);
++		sk->sk_wmem_queued -= orig_skb->truesize;
++		sk_mem_uncharge(sk, orig_skb->truesize);
++		skb = orig_skb;
++	}
++	if (unlikely(!skb))
++		return;
++
++	if (sk && mptcp_reconstruct_mapping(skb)) {
++		__kfree_skb(skb);
++		return;
++	}
++
++	skb->sk = meta_sk;
++
++	/* If it reached already the destination, we don't have to reinject it */
++	if (!after(TCP_SKB_CB(skb)->end_seq, meta_tp->snd_una)) {
++		__kfree_skb(skb);
++		return;
++	}
++
++	/* Only reinject segments that are fully covered by the mapping */
++	if (skb->len + (mptcp_is_data_fin(skb) ? 1 : 0) !=
++	    TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq) {
++		u32 seq = TCP_SKB_CB(skb)->seq;
++		u32 end_seq = TCP_SKB_CB(skb)->end_seq;
++
++		__kfree_skb(skb);
++
++		/* Ok, now we have to look for the full mapping in the meta
++		 * send-queue :S
++		 */
++		tcp_for_write_queue(skb, meta_sk) {
++			/* Not yet at the mapping? */
++			if (before(TCP_SKB_CB(skb)->seq, seq))
++				continue;
++			/* We have passed by the mapping */
++			if (after(TCP_SKB_CB(skb)->end_seq, end_seq))
++				return;
++
++			__mptcp_reinject_data(skb, meta_sk, NULL, 1);
++		}
++		return;
++	}
++
++	/* Segment goes back to the MPTCP-layer. So, we need to zero the
++	 * path_mask/dss.
++	 */
++	memset(TCP_SKB_CB(skb)->dss, 0 , mptcp_dss_len);
++
++	/* We need to find out the path-mask from the meta-write-queue
++	 * to properly select a subflow.
++	 */
++	mptcp_find_and_set_pathmask(meta_sk, skb);
++
++	/* If it's empty, just add */
++	if (skb_queue_empty(&mpcb->reinject_queue)) {
++		skb_queue_head(&mpcb->reinject_queue, skb);
++		return;
++	}
++
++	/* Find place to insert skb - or even we can 'drop' it, as the
++	 * data is already covered by other skb's in the reinject-queue.
++	 *
++	 * This is inspired by code from tcp_data_queue.
++	 */
++
++	skb1 = skb_peek_tail(&mpcb->reinject_queue);
++	seq = TCP_SKB_CB(skb)->seq;
++	while (1) {
++		if (!after(TCP_SKB_CB(skb1)->seq, seq))
++			break;
++		if (skb_queue_is_first(&mpcb->reinject_queue, skb1)) {
++			skb1 = NULL;
++			break;
++		}
++		skb1 = skb_queue_prev(&mpcb->reinject_queue, skb1);
++	}
++
++	/* Do skb overlap to previous one? */
++	end_seq = TCP_SKB_CB(skb)->end_seq;
++	if (skb1 && before(seq, TCP_SKB_CB(skb1)->end_seq)) {
++		if (!after(end_seq, TCP_SKB_CB(skb1)->end_seq)) {
++			/* All the bits are present. Don't reinject */
++			__kfree_skb(skb);
++			return;
++		}
++		if (seq == TCP_SKB_CB(skb1)->seq) {
++			if (skb_queue_is_first(&mpcb->reinject_queue, skb1))
++				skb1 = NULL;
++			else
++				skb1 = skb_queue_prev(&mpcb->reinject_queue, skb1);
++		}
++	}
++	if (!skb1)
++		__skb_queue_head(&mpcb->reinject_queue, skb);
++	else
++		__skb_queue_after(&mpcb->reinject_queue, skb1, skb);
++
++	/* And clean segments covered by new one as whole. */
++	while (!skb_queue_is_last(&mpcb->reinject_queue, skb)) {
++		skb1 = skb_queue_next(&mpcb->reinject_queue, skb);
++
++		if (!after(end_seq, TCP_SKB_CB(skb1)->seq))
++			break;
++
++		__skb_unlink(skb1, &mpcb->reinject_queue);
++		__kfree_skb(skb1);
++	}
++	return;
++}
++
++/* Inserts data into the reinject queue */
++void mptcp_reinject_data(struct sock *sk, int clone_it)
++{
++	struct sk_buff *skb_it, *tmp;
++	struct tcp_sock *tp = tcp_sk(sk);
++	struct sock *meta_sk = tp->meta_sk;
++
++	/* It has already been closed - there is really no point in reinjecting */
++	if (meta_sk->sk_state == TCP_CLOSE)
++		return;
++
++	skb_queue_walk_safe(&sk->sk_write_queue, skb_it, tmp) {
++		struct tcp_skb_cb *tcb = TCP_SKB_CB(skb_it);
++		/* Subflow syn's and fin's are not reinjected.
++		 *
++		 * As well as empty subflow-fins with a data-fin.
++		 * They are reinjected below (without the subflow-fin-flag)
++		 */
++		if (tcb->tcp_flags & TCPHDR_SYN ||
++		    (tcb->tcp_flags & TCPHDR_FIN && !mptcp_is_data_fin(skb_it)) ||
++		    (tcb->tcp_flags & TCPHDR_FIN && mptcp_is_data_fin(skb_it) && !skb_it->len))
++			continue;
++
++		__mptcp_reinject_data(skb_it, meta_sk, sk, clone_it);
++	}
++
++	skb_it = tcp_write_queue_tail(meta_sk);
++	/* If sk has sent the empty data-fin, we have to reinject it too. */
++	if (skb_it && mptcp_is_data_fin(skb_it) && skb_it->len == 0 &&
++	    TCP_SKB_CB(skb_it)->path_mask & mptcp_pi_to_flag(tp->mptcp->path_index)) {
++		__mptcp_reinject_data(skb_it, meta_sk, NULL, 1);
++	}
++
++	mptcp_push_pending_frames(meta_sk);
++
++	tp->pf = 1;
++}
++EXPORT_SYMBOL(mptcp_reinject_data);
++
++static void mptcp_combine_dfin(const struct sk_buff *skb, const struct sock *meta_sk,
++			       struct sock *subsk)
++{
++	const struct tcp_sock *meta_tp = tcp_sk(meta_sk);
++	struct mptcp_cb *mpcb = meta_tp->mpcb;
++	struct sock *sk_it;
++	int all_empty = 1, all_acked;
++
++	/* In infinite mapping we always try to combine */
++	if (mpcb->infinite_mapping_snd && tcp_close_state(subsk)) {
++		subsk->sk_shutdown |= SEND_SHUTDOWN;
++		TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_FIN;
++		return;
++	}
++
++	/* Don't combine, if they didn't combine - otherwise we end up in
++	 * TIME_WAIT, even if our app is smart enough to avoid it
++	 */
++	if (meta_sk->sk_shutdown & RCV_SHUTDOWN) {
++		if (!mpcb->dfin_combined)
++			return;
++	}
++
++	/* If no other subflow has data to send, we can combine */
++	mptcp_for_each_sk(mpcb, sk_it) {
++		if (!mptcp_sk_can_send(sk_it))
++			continue;
++
++		if (!tcp_write_queue_empty(sk_it))
++			all_empty = 0;
++	}
++
++	/* If all data has been DATA_ACKed, we can combine.
++	 * -1, because the data_fin consumed one byte
++	 */
++	all_acked = (meta_tp->snd_una == (meta_tp->write_seq - 1));
++
++	if ((all_empty || all_acked) && tcp_close_state(subsk)) {
++		subsk->sk_shutdown |= SEND_SHUTDOWN;
++		TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_FIN;
++	}
++}
++
++static int mptcp_write_dss_mapping(const struct tcp_sock *tp, const struct sk_buff *skb,
++				   __be32 *ptr)
++{
++	const struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
++	__be32 *start = ptr;
++	__u16 data_len;
++
++	*ptr++ = htonl(tcb->seq); /* data_seq */
++
++	/* If it's a non-data DATA_FIN, we set subseq to 0 (draft v7) */
++	if (mptcp_is_data_fin(skb) && skb->len == 0)
++		*ptr++ = 0; /* subseq */
++	else
++		*ptr++ = htonl(tp->write_seq - tp->mptcp->snt_isn); /* subseq */
++
++	if (tcb->mptcp_flags & MPTCPHDR_INF)
++		data_len = 0;
++	else
++		data_len = tcb->end_seq - tcb->seq;
++
++	if (tp->mpcb->dss_csum && data_len) {
++		__be16 *p16 = (__be16 *)ptr;
++		__be32 hdseq = mptcp_get_highorder_sndbits(skb, tp->mpcb);
++		__wsum csum;
++
++		*ptr = htonl(((data_len) << 16) |
++			     (TCPOPT_EOL << 8) |
++			     (TCPOPT_EOL));
++		csum = csum_partial(ptr - 2, 12, skb->csum);
++		p16++;
++		*p16++ = csum_fold(csum_partial(&hdseq, sizeof(hdseq), csum));
++	} else {
++		*ptr++ = htonl(((data_len) << 16) |
++			       (TCPOPT_NOP << 8) |
++			       (TCPOPT_NOP));
++	}
++
++	return ptr - start;
++}
++
++static int mptcp_write_dss_data_ack(const struct tcp_sock *tp, const struct sk_buff *skb,
++				    __be32 *ptr)
++{
++	struct mp_dss *mdss = (struct mp_dss *)ptr;
++	__be32 *start = ptr;
++
++	mdss->kind = TCPOPT_MPTCP;
++	mdss->sub = MPTCP_SUB_DSS;
++	mdss->rsv1 = 0;
++	mdss->rsv2 = 0;
++	mdss->F = mptcp_is_data_fin(skb) ? 1 : 0;
++	mdss->m = 0;
++	mdss->M = mptcp_is_data_seq(skb) ? 1 : 0;
++	mdss->a = 0;
++	mdss->A = 1;
++	mdss->len = mptcp_sub_len_dss(mdss, tp->mpcb->dss_csum);
++	ptr++;
++
++	*ptr++ = htonl(mptcp_meta_tp(tp)->rcv_nxt);
++
++	return ptr - start;
++}
++
++/* RFC6824 states that once a particular subflow mapping has been sent
++ * out it must never be changed. However, packets may be split while
++ * they are in the retransmission queue (due to SACK or ACKs) and that
++ * arguably means that we would change the mapping (e.g. it splits it,
++ * our sends out a subset of the initial mapping).
++ *
++ * Furthermore, the skb checksum is not always preserved across splits
++ * (e.g. mptcp_fragment) which would mean that we need to recompute
++ * the DSS checksum in this case.
++ *
++ * To avoid this we save the initial DSS mapping which allows us to
++ * send the same DSS mapping even for fragmented retransmits.
++ */
++static void mptcp_save_dss_data_seq(const struct tcp_sock *tp, struct sk_buff *skb)
++{
++	struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
++	__be32 *ptr = (__be32 *)tcb->dss;
++
++	tcb->mptcp_flags |= MPTCPHDR_SEQ;
++
++	ptr += mptcp_write_dss_data_ack(tp, skb, ptr);
++	ptr += mptcp_write_dss_mapping(tp, skb, ptr);
++}
++
++/* Write the saved DSS mapping to the header */
++static int mptcp_write_dss_data_seq(const struct tcp_sock *tp, struct sk_buff *skb,
++				    __be32 *ptr)
++{
++	__be32 *start = ptr;
++
++	memcpy(ptr, TCP_SKB_CB(skb)->dss, mptcp_dss_len);
++
++	/* update the data_ack */
++	start[1] = htonl(mptcp_meta_tp(tp)->rcv_nxt);
++
++	/* dss is in a union with inet_skb_parm and
++	 * the IP layer expects zeroed IPCB fields.
++	 */
++	memset(TCP_SKB_CB(skb)->dss, 0 , mptcp_dss_len);
++
++	return mptcp_dss_len/sizeof(*ptr);
++}
++
++static bool mptcp_skb_entail(struct sock *sk, struct sk_buff *skb, int reinject)
++{
++	struct tcp_sock *tp = tcp_sk(sk);
++	const struct sock *meta_sk = mptcp_meta_sk(sk);
++	const struct mptcp_cb *mpcb = tp->mpcb;
++	struct tcp_skb_cb *tcb;
++	struct sk_buff *subskb = NULL;
++
++	if (!reinject)
++		TCP_SKB_CB(skb)->mptcp_flags |= (mpcb->snd_hiseq_index ?
++						  MPTCPHDR_SEQ64_INDEX : 0);
++
++	subskb = pskb_copy_for_clone(skb, GFP_ATOMIC);
++	if (!subskb)
++		return false;
++
++	/* At the subflow-level we need to call again tcp_init_tso_segs. We
++	 * force this, by setting gso_segs to 0. It has been set to 1 prior to
++	 * the call to mptcp_skb_entail.
++	 */
++	skb_shinfo(subskb)->gso_segs = 0;
++
++	TCP_SKB_CB(skb)->path_mask |= mptcp_pi_to_flag(tp->mptcp->path_index);
++
++	if (!(sk->sk_route_caps & NETIF_F_ALL_CSUM) &&
++	    skb->ip_summed == CHECKSUM_PARTIAL) {
++		subskb->csum = skb->csum = skb_checksum(skb, 0, skb->len, 0);
++		subskb->ip_summed = skb->ip_summed = CHECKSUM_NONE;
++	}
++
++	tcb = TCP_SKB_CB(subskb);
++
++	if (tp->mpcb->send_infinite_mapping &&
++	    !tp->mpcb->infinite_mapping_snd &&
++	    !before(tcb->seq, mptcp_meta_tp(tp)->snd_nxt)) {
++		tp->mptcp->fully_established = 1;
++		tp->mpcb->infinite_mapping_snd = 1;
++		tp->mptcp->infinite_cutoff_seq = tp->write_seq;
++		tcb->mptcp_flags |= MPTCPHDR_INF;
++	}
++
++	if (mptcp_is_data_fin(subskb))
++		mptcp_combine_dfin(subskb, meta_sk, sk);
++
++	mptcp_save_dss_data_seq(tp, subskb);
++
++	tcb->seq = tp->write_seq;
++	tcb->sacked = 0; /* reset the sacked field: from the point of view
++			  * of this subflow, we are sending a brand new
++			  * segment
++			  */
++	/* Take into account seg len */
++	tp->write_seq += subskb->len + ((tcb->tcp_flags & TCPHDR_FIN) ? 1 : 0);
++	tcb->end_seq = tp->write_seq;
++
++	/* If it's a non-payload DATA_FIN (also no subflow-fin), the
++	 * segment is not part of the subflow but on a meta-only-level.
++	 */
++	if (!mptcp_is_data_fin(subskb) || tcb->end_seq != tcb->seq) {
++		tcp_add_write_queue_tail(sk, subskb);
++		sk->sk_wmem_queued += subskb->truesize;
++		sk_mem_charge(sk, subskb->truesize);
++	} else {
++		int err;
++
++		/* Necessary to initialize for tcp_transmit_skb. mss of 1, as
++		 * skb->len = 0 will force tso_segs to 1.
++		 */
++		tcp_init_tso_segs(sk, subskb, 1);
++		/* Empty data-fins are sent immediatly on the subflow */
++		TCP_SKB_CB(subskb)->when = tcp_time_stamp;
++		err = tcp_transmit_skb(sk, subskb, 1, GFP_ATOMIC);
++
++		/* It has not been queued, we can free it now. */
++		kfree_skb(subskb);
++
++		if (err)
++			return false;
++	}
++
++	if (!tp->mptcp->fully_established) {
++		tp->mptcp->second_packet = 1;
++		tp->mptcp->last_end_data_seq = TCP_SKB_CB(skb)->end_seq;
++	}
++
++	return true;
++}
++
++/* Fragment an skb and update the mptcp meta-data. Due to reinject, we
++ * might need to undo some operations done by tcp_fragment.
++ */
++static int mptcp_fragment(struct sock *meta_sk, struct sk_buff *skb, u32 len,
++			  gfp_t gfp, int reinject)
++{
++	int ret, diff, old_factor;
++	struct sk_buff *buff;
++	u8 flags;
++
++	if (skb_headlen(skb) < len)
++		diff = skb->len - len;
++	else
++		diff = skb->data_len;
++	old_factor = tcp_skb_pcount(skb);
++
++	/* The mss_now in tcp_fragment is used to set the tso_segs of the skb.
++	 * At the MPTCP-level we do not care about the absolute value. All we
++	 * care about is that it is set to 1 for accurate packets_out
++	 * accounting.
++	 */
++	ret = tcp_fragment(meta_sk, skb, len, UINT_MAX, gfp);
++	if (ret)
++		return ret;
++
++	buff = skb->next;
++
++	flags = TCP_SKB_CB(skb)->mptcp_flags;
++	TCP_SKB_CB(skb)->mptcp_flags = flags & ~(MPTCPHDR_FIN);
++	TCP_SKB_CB(buff)->mptcp_flags = flags;
++	TCP_SKB_CB(buff)->path_mask = TCP_SKB_CB(skb)->path_mask;
++
++	/* If reinject == 1, the buff will be added to the reinject
++	 * queue, which is currently not part of memory accounting. So
++	 * undo the changes done by tcp_fragment and update the
++	 * reinject queue. Also, undo changes to the packet counters.
++	 */
++	if (reinject == 1) {
++		int undo = buff->truesize - diff;
++		meta_sk->sk_wmem_queued -= undo;
++		sk_mem_uncharge(meta_sk, undo);
++
++		tcp_sk(meta_sk)->mpcb->reinject_queue.qlen++;
++		meta_sk->sk_write_queue.qlen--;
++
++		if (!before(tcp_sk(meta_sk)->snd_nxt, TCP_SKB_CB(buff)->end_seq)) {
++			undo = old_factor - tcp_skb_pcount(skb) -
++				tcp_skb_pcount(buff);
++			if (undo)
++				tcp_adjust_pcount(meta_sk, skb, -undo);
++		}
++	}
++
++	return 0;
++}
++
++/* Inspired by tcp_write_wakeup */
++int mptcp_write_wakeup(struct sock *meta_sk)
++{
++	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
++	struct sk_buff *skb;
++	struct sock *sk_it;
++	int ans = 0;
++
++	if (meta_sk->sk_state == TCP_CLOSE)
++		return -1;
++
++	skb = tcp_send_head(meta_sk);
++	if (skb &&
++	    before(TCP_SKB_CB(skb)->seq, tcp_wnd_end(meta_tp))) {
++		unsigned int mss;
++		unsigned int seg_size = tcp_wnd_end(meta_tp) - TCP_SKB_CB(skb)->seq;
++		struct sock *subsk = meta_tp->mpcb->sched_ops->get_subflow(meta_sk, skb, true);
++		struct tcp_sock *subtp;
++		if (!subsk)
++			goto window_probe;
++		subtp = tcp_sk(subsk);
++		mss = tcp_current_mss(subsk);
++
++		seg_size = min(tcp_wnd_end(meta_tp) - TCP_SKB_CB(skb)->seq,
++			       tcp_wnd_end(subtp) - subtp->write_seq);
++
++		if (before(meta_tp->pushed_seq, TCP_SKB_CB(skb)->end_seq))
++			meta_tp->pushed_seq = TCP_SKB_CB(skb)->end_seq;
++
++		/* We are probing the opening of a window
++		 * but the window size is != 0
++		 * must have been a result SWS avoidance ( sender )
++		 */
++		if (seg_size < TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq ||
++		    skb->len > mss) {
++			seg_size = min(seg_size, mss);
++			TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH;
++			if (mptcp_fragment(meta_sk, skb, seg_size,
++					   GFP_ATOMIC, 0))
++				return -1;
++		} else if (!tcp_skb_pcount(skb)) {
++			/* see mptcp_write_xmit on why we use UINT_MAX */
++			tcp_set_skb_tso_segs(meta_sk, skb, UINT_MAX);
++		}
++
++		TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH;
++		if (!mptcp_skb_entail(subsk, skb, 0))
++			return -1;
++		TCP_SKB_CB(skb)->when = tcp_time_stamp;
++
++		mptcp_check_sndseq_wrap(meta_tp, TCP_SKB_CB(skb)->end_seq -
++						 TCP_SKB_CB(skb)->seq);
++		tcp_event_new_data_sent(meta_sk, skb);
++
++		__tcp_push_pending_frames(subsk, mss, TCP_NAGLE_PUSH);
++
++		return 0;
++	} else {
++window_probe:
++		if (between(meta_tp->snd_up, meta_tp->snd_una + 1,
++			    meta_tp->snd_una + 0xFFFF)) {
++			mptcp_for_each_sk(meta_tp->mpcb, sk_it) {
++				if (mptcp_sk_can_send_ack(sk_it))
++					tcp_xmit_probe_skb(sk_it, 1);
++			}
++		}
++
++		/* At least one of the tcp_xmit_probe_skb's has to succeed */
++		mptcp_for_each_sk(meta_tp->mpcb, sk_it) {
++			int ret;
++
++			if (!mptcp_sk_can_send_ack(sk_it))
++				continue;
++
++			ret = tcp_xmit_probe_skb(sk_it, 0);
++			if (unlikely(ret > 0))
++				ans = ret;
++		}
++		return ans;
++	}
++}
++
++bool mptcp_write_xmit(struct sock *meta_sk, unsigned int mss_now, int nonagle,
++		     int push_one, gfp_t gfp)
++{
++	struct tcp_sock *meta_tp = tcp_sk(meta_sk), *subtp;
++	struct sock *subsk = NULL;
++	struct mptcp_cb *mpcb = meta_tp->mpcb;
++	struct sk_buff *skb;
++	unsigned int sent_pkts;
++	int reinject = 0;
++	unsigned int sublimit;
++
++	sent_pkts = 0;
++
++	while ((skb = mpcb->sched_ops->next_segment(meta_sk, &reinject, &subsk,
++						    &sublimit))) {
++		unsigned int limit;
++
++		subtp = tcp_sk(subsk);
++		mss_now = tcp_current_mss(subsk);
++
++		if (reinject == 1) {
++			if (!after(TCP_SKB_CB(skb)->end_seq, meta_tp->snd_una)) {
++				/* Segment already reached the peer, take the next one */
++				__skb_unlink(skb, &mpcb->reinject_queue);
++				__kfree_skb(skb);
++				continue;
++			}
++		}
++
++		/* If the segment was cloned (e.g. a meta retransmission),
++		 * the header must be expanded/copied so that there is no
++		 * corruption of TSO information.
++		 */
++		if (skb_unclone(skb, GFP_ATOMIC))
++			break;
++
++		if (unlikely(!tcp_snd_wnd_test(meta_tp, skb, mss_now)))
++			break;
++
++		/* Force tso_segs to 1 by using UINT_MAX.
++		 * We actually don't care about the exact number of segments
++		 * emitted on the subflow. We need just to set tso_segs, because
++		 * we still need an accurate packets_out count in
++		 * tcp_event_new_data_sent.
++		 */
++		tcp_set_skb_tso_segs(meta_sk, skb, UINT_MAX);
++
++		/* Check for nagle, irregardless of tso_segs. If the segment is
++		 * actually larger than mss_now (TSO segment), then
++		 * tcp_nagle_check will have partial == false and always trigger
++		 * the transmission.
++		 * tcp_write_xmit has a TSO-level nagle check which is not
++		 * subject to the MPTCP-level. It is based on the properties of
++		 * the subflow, not the MPTCP-level.
++		 */
++		if (unlikely(!tcp_nagle_test(meta_tp, skb, mss_now,
++					     (tcp_skb_is_last(meta_sk, skb) ?
++					      nonagle : TCP_NAGLE_PUSH))))
++			break;
++
++		limit = mss_now;
++		/* skb->len > mss_now is the equivalent of tso_segs > 1 in
++		 * tcp_write_xmit. Otherwise split-point would return 0.
++		 */
++		if (skb->len > mss_now && !tcp_urg_mode(meta_tp))
++			/* We limit the size of the skb so that it fits into the
++			 * window. Call tcp_mss_split_point to avoid duplicating
++			 * code.
++			 * We really only care about fitting the skb into the
++			 * window. That's why we use UINT_MAX. If the skb does
++			 * not fit into the cwnd_quota or the NIC's max-segs
++			 * limitation, it will be split by the subflow's
++			 * tcp_write_xmit which does the appropriate call to
++			 * tcp_mss_split_point.
++			 */
++			limit = tcp_mss_split_point(meta_sk, skb, mss_now,
++						    UINT_MAX / mss_now,
++						    nonagle);
++
++		if (sublimit)
++			limit = min(limit, sublimit);
++
++		if (skb->len > limit &&
++		    unlikely(mptcp_fragment(meta_sk, skb, limit, gfp, reinject)))
++			break;
++
++		if (!mptcp_skb_entail(subsk, skb, reinject))
++			break;
++		/* Nagle is handled at the MPTCP-layer, so
++		 * always push on the subflow
++		 */
++		__tcp_push_pending_frames(subsk, mss_now, TCP_NAGLE_PUSH);
++		TCP_SKB_CB(skb)->when = tcp_time_stamp;
++
++		if (!reinject) {
++			mptcp_check_sndseq_wrap(meta_tp,
++						TCP_SKB_CB(skb)->end_seq -
++						TCP_SKB_CB(skb)->seq);
++			tcp_event_new_data_sent(meta_sk, skb);
++		}
++
++		tcp_minshall_update(meta_tp, mss_now, skb);
++		sent_pkts += tcp_skb_pcount(skb);
++
++		if (reinject > 0) {
++			__skb_unlink(skb, &mpcb->reinject_queue);
++			kfree_skb(skb);
++		}
++
++		if (push_one)
++			break;
++	}
++
++	return !meta_tp->packets_out && tcp_send_head(meta_sk);
++}
++
++void mptcp_write_space(struct sock *sk)
++{
++	mptcp_push_pending_frames(mptcp_meta_sk(sk));
++}
++
++u32 __mptcp_select_window(struct sock *sk)
++{
++	struct inet_connection_sock *icsk = inet_csk(sk);
++	struct tcp_sock *tp = tcp_sk(sk), *meta_tp = mptcp_meta_tp(tp);
++	int mss, free_space, full_space, window;
++
++	/* MSS for the peer's data.  Previous versions used mss_clamp
++	 * here.  I don't know if the value based on our guesses
++	 * of peer's MSS is better for the performance.  It's more correct
++	 * but may be worse for the performance because of rcv_mss
++	 * fluctuations.  --SAW  1998/11/1
++	 */
++	mss = icsk->icsk_ack.rcv_mss;
++	free_space = tcp_space(sk);
++	full_space = min_t(int, meta_tp->window_clamp,
++			tcp_full_space(sk));
++
++	if (mss > full_space)
++		mss = full_space;
++
++	if (free_space < (full_space >> 1)) {
++		icsk->icsk_ack.quick = 0;
++
++		if (tcp_memory_pressure)
++			/* TODO this has to be adapted when we support different
++			 * MSS's among the subflows.
++			 */
++			meta_tp->rcv_ssthresh = min(meta_tp->rcv_ssthresh,
++						    4U * meta_tp->advmss);
++
++		if (free_space < mss)
++			return 0;
++	}
++
++	if (free_space > meta_tp->rcv_ssthresh)
++		free_space = meta_tp->rcv_ssthresh;
++
++	/* Don't do rounding if we are using window scaling, since the
++	 * scaled window will not line up with the MSS boundary anyway.
++	 */
++	window = meta_tp->rcv_wnd;
++	if (tp->rx_opt.rcv_wscale) {
++		window = free_space;
++
++		/* Advertise enough space so that it won't get scaled away.
++		 * Import case: prevent zero window announcement if
++		 * 1<<rcv_wscale > mss.
++		 */
++		if (((window >> tp->rx_opt.rcv_wscale) << tp->
++		     rx_opt.rcv_wscale) != window)
++			window = (((window >> tp->rx_opt.rcv_wscale) + 1)
++				  << tp->rx_opt.rcv_wscale);
++	} else {
++		/* Get the largest window that is a nice multiple of mss.
++		 * Window clamp already applied above.
++		 * If our current window offering is within 1 mss of the
++		 * free space we just keep it. This prevents the divide
++		 * and multiply from happening most of the time.
++		 * We also don't do any window rounding when the free space
++		 * is too small.
++		 */
++		if (window <= free_space - mss || window > free_space)
++			window = (free_space / mss) * mss;
++		else if (mss == full_space &&
++			 free_space > window + (full_space >> 1))
++			window = free_space;
++	}
++
++	return window;
++}
++
++void mptcp_syn_options(const struct sock *sk, struct tcp_out_options *opts,
++		       unsigned *remaining)
++{
++	const struct tcp_sock *tp = tcp_sk(sk);
++
++	opts->options |= OPTION_MPTCP;
++	if (is_master_tp(tp)) {
++		opts->mptcp_options |= OPTION_MP_CAPABLE | OPTION_TYPE_SYN;
++		*remaining -= MPTCP_SUB_LEN_CAPABLE_SYN_ALIGN;
++		opts->mp_capable.sender_key = tp->mptcp_loc_key;
++		opts->dss_csum = !!sysctl_mptcp_checksum;
++	} else {
++		const struct mptcp_cb *mpcb = tp->mpcb;
++
++		opts->mptcp_options |= OPTION_MP_JOIN | OPTION_TYPE_SYN;
++		*remaining -= MPTCP_SUB_LEN_JOIN_SYN_ALIGN;
++		opts->mp_join_syns.token = mpcb->mptcp_rem_token;
++		opts->mp_join_syns.low_prio  = tp->mptcp->low_prio;
++		opts->addr_id = tp->mptcp->loc_id;
++		opts->mp_join_syns.sender_nonce = tp->mptcp->mptcp_loc_nonce;
++	}
++}
++
++void mptcp_synack_options(struct request_sock *req,
++			  struct tcp_out_options *opts, unsigned *remaining)
++{
++	struct mptcp_request_sock *mtreq;
++	mtreq = mptcp_rsk(req);
++
++	opts->options |= OPTION_MPTCP;
++	/* MPCB not yet set - thus it's a new MPTCP-session */
++	if (!mtreq->is_sub) {
++		opts->mptcp_options |= OPTION_MP_CAPABLE | OPTION_TYPE_SYNACK;
++		opts->mp_capable.sender_key = mtreq->mptcp_loc_key;
++		opts->dss_csum = !!sysctl_mptcp_checksum || mtreq->dss_csum;
++		*remaining -= MPTCP_SUB_LEN_CAPABLE_SYN_ALIGN;
++	} else {
++		opts->mptcp_options |= OPTION_MP_JOIN | OPTION_TYPE_SYNACK;
++		opts->mp_join_syns.sender_truncated_mac =
++				mtreq->mptcp_hash_tmac;
++		opts->mp_join_syns.sender_nonce = mtreq->mptcp_loc_nonce;
++		opts->mp_join_syns.low_prio = mtreq->low_prio;
++		opts->addr_id = mtreq->loc_id;
++		*remaining -= MPTCP_SUB_LEN_JOIN_SYNACK_ALIGN;
++	}
++}
++
++void mptcp_established_options(struct sock *sk, struct sk_buff *skb,
++			       struct tcp_out_options *opts, unsigned *size)
++{
++	struct tcp_sock *tp = tcp_sk(sk);
++	struct mptcp_cb *mpcb = tp->mpcb;
++	const struct tcp_skb_cb *tcb = skb ? TCP_SKB_CB(skb) : NULL;
++
++	/* We are coming from tcp_current_mss with the meta_sk as an argument.
++	 * It does not make sense to check for the options, because when the
++	 * segment gets sent, another subflow will be chosen.
++	 */
++	if (!skb && is_meta_sk(sk))
++		return;
++
++	/* In fallback mp_fail-mode, we have to repeat it until the fallback
++	 * has been done by the sender
++	 */
++	if (unlikely(tp->mptcp->send_mp_fail)) {
++		opts->options |= OPTION_MPTCP;
++		opts->mptcp_options |= OPTION_MP_FAIL;
++		*size += MPTCP_SUB_LEN_FAIL;
++		return;
++	}
++
++	if (unlikely(tp->send_mp_fclose)) {
++		opts->options |= OPTION_MPTCP;
++		opts->mptcp_options |= OPTION_MP_FCLOSE;
++		opts->mp_capable.receiver_key = mpcb->mptcp_rem_key;
++		*size += MPTCP_SUB_LEN_FCLOSE_ALIGN;
++		return;
++	}
++
++	/* 1. If we are the sender of the infinite-mapping, we need the
++	 *    MPTCPHDR_INF-flag, because a retransmission of the
++	 *    infinite-announcment still needs the mptcp-option.
++	 *
++	 *    We need infinite_cutoff_seq, because retransmissions from before
++	 *    the infinite-cutoff-moment still need the MPTCP-signalling to stay
++	 *    consistent.
++	 *
++	 * 2. If we are the receiver of the infinite-mapping, we always skip
++	 *    mptcp-options, because acknowledgments from before the
++	 *    infinite-mapping point have already been sent out.
++	 *
++	 * I know, the whole infinite-mapping stuff is ugly...
++	 *
++	 * TODO: Handle wrapped data-sequence numbers
++	 *       (even if it's very unlikely)
++	 */
++	if (unlikely(mpcb->infinite_mapping_snd) &&
++	    ((mpcb->send_infinite_mapping && tcb &&
++	      mptcp_is_data_seq(skb) &&
++	      !(tcb->mptcp_flags & MPTCPHDR_INF) &&
++	      !before(tcb->seq, tp->mptcp->infinite_cutoff_seq)) ||
++	     !mpcb->send_infinite_mapping))
++		return;
++
++	if (unlikely(tp->mptcp->include_mpc)) {
++		opts->options |= OPTION_MPTCP;
++		opts->mptcp_options |= OPTION_MP_CAPABLE |
++				       OPTION_TYPE_ACK;
++		*size += MPTCP_SUB_LEN_CAPABLE_ACK_ALIGN;
++		opts->mp_capable.sender_key = mpcb->mptcp_loc_key;
++		opts->mp_capable.receiver_key = mpcb->mptcp_rem_key;
++		opts->dss_csum = mpcb->dss_csum;
++
++		if (skb)
++			tp->mptcp->include_mpc = 0;
++	}
++	if (unlikely(tp->mptcp->pre_established)) {
++		opts->options |= OPTION_MPTCP;
++		opts->mptcp_options |= OPTION_MP_JOIN | OPTION_TYPE_ACK;
++		*size += MPTCP_SUB_LEN_JOIN_ACK_ALIGN;
++	}
++
++	if (!tp->mptcp->include_mpc && !tp->mptcp->pre_established) {
++		opts->options |= OPTION_MPTCP;
++		opts->mptcp_options |= OPTION_DATA_ACK;
++		/* If !skb, we come from tcp_current_mss and thus we always
++		 * assume that the DSS-option will be set for the data-packet.
++		 */
++		if (skb && !mptcp_is_data_seq(skb)) {
++			*size += MPTCP_SUB_LEN_ACK_ALIGN;
++		} else {
++			/* Doesn't matter, if csum included or not. It will be
++			 * either 10 or 12, and thus aligned = 12
++			 */
++			*size += MPTCP_SUB_LEN_ACK_ALIGN +
++				 MPTCP_SUB_LEN_SEQ_ALIGN;
++		}
++
++		*size += MPTCP_SUB_LEN_DSS_ALIGN;
++	}
++
++	if (unlikely(mpcb->addr_signal) && mpcb->pm_ops->addr_signal)
++		mpcb->pm_ops->addr_signal(sk, size, opts, skb);
++
++	if (unlikely(tp->mptcp->send_mp_prio) &&
++	    MAX_TCP_OPTION_SPACE - *size >= MPTCP_SUB_LEN_PRIO_ALIGN) {
++		opts->options |= OPTION_MPTCP;
++		opts->mptcp_options |= OPTION_MP_PRIO;
++		if (skb)
++			tp->mptcp->send_mp_prio = 0;
++		*size += MPTCP_SUB_LEN_PRIO_ALIGN;
++	}
++
++	return;
++}
++
++u16 mptcp_select_window(struct sock *sk)
++{
++	u16 new_win		= tcp_select_window(sk);
++	struct tcp_sock *tp	= tcp_sk(sk);
++	struct tcp_sock *meta_tp = mptcp_meta_tp(tp);
++
++	meta_tp->rcv_wnd	= tp->rcv_wnd;
++	meta_tp->rcv_wup	= meta_tp->rcv_nxt;
++
++	return new_win;
++}
++
++void mptcp_options_write(__be32 *ptr, struct tcp_sock *tp,
++			 const struct tcp_out_options *opts,
++			 struct sk_buff *skb)
++{
++	if (unlikely(OPTION_MP_CAPABLE & opts->mptcp_options)) {
++		struct mp_capable *mpc = (struct mp_capable *)ptr;
++
++		mpc->kind = TCPOPT_MPTCP;
++
++		if ((OPTION_TYPE_SYN & opts->mptcp_options) ||
++		    (OPTION_TYPE_SYNACK & opts->mptcp_options)) {
++			mpc->sender_key = opts->mp_capable.sender_key;
++			mpc->len = MPTCP_SUB_LEN_CAPABLE_SYN;
++			ptr += MPTCP_SUB_LEN_CAPABLE_SYN_ALIGN >> 2;
++		} else if (OPTION_TYPE_ACK & opts->mptcp_options) {
++			mpc->sender_key = opts->mp_capable.sender_key;
++			mpc->receiver_key = opts->mp_capable.receiver_key;
++			mpc->len = MPTCP_SUB_LEN_CAPABLE_ACK;
++			ptr += MPTCP_SUB_LEN_CAPABLE_ACK_ALIGN >> 2;
++		}
++
++		mpc->sub = MPTCP_SUB_CAPABLE;
++		mpc->ver = 0;
++		mpc->a = opts->dss_csum;
++		mpc->b = 0;
++		mpc->rsv = 0;
++		mpc->h = 1;
++	}
++
++	if (unlikely(OPTION_MP_JOIN & opts->mptcp_options)) {
++		struct mp_join *mpj = (struct mp_join *)ptr;
++
++		mpj->kind = TCPOPT_MPTCP;
++		mpj->sub = MPTCP_SUB_JOIN;
++		mpj->rsv = 0;
++
++		if (OPTION_TYPE_SYN & opts->mptcp_options) {
++			mpj->len = MPTCP_SUB_LEN_JOIN_SYN;
++			mpj->u.syn.token = opts->mp_join_syns.token;
++			mpj->u.syn.nonce = opts->mp_join_syns.sender_nonce;
++			mpj->b = opts->mp_join_syns.low_prio;
++			mpj->addr_id = opts->addr_id;
++			ptr += MPTCP_SUB_LEN_JOIN_SYN_ALIGN >> 2;
++		} else if (OPTION_TYPE_SYNACK & opts->mptcp_options) {
++			mpj->len = MPTCP_SUB_LEN_JOIN_SYNACK;
++			mpj->u.synack.mac =
++				opts->mp_join_syns.sender_truncated_mac;
++			mpj->u.synack.nonce = opts->mp_join_syns.sender_nonce;
++			mpj->b = opts->mp_join_syns.low_prio;
++			mpj->addr_id = opts->addr_id;
++			ptr += MPTCP_SUB_LEN_JOIN_SYNACK_ALIGN >> 2;
++		} else if (OPTION_TYPE_ACK & opts->mptcp_options) {
++			mpj->len = MPTCP_SUB_LEN_JOIN_ACK;
++			mpj->addr_id = 0; /* addr_id is rsv (RFC 6824, p. 21) */
++			memcpy(mpj->u.ack.mac, &tp->mptcp->sender_mac[0], 20);
++			ptr += MPTCP_SUB_LEN_JOIN_ACK_ALIGN >> 2;
++		}
++	}
++	if (unlikely(OPTION_ADD_ADDR & opts->mptcp_options)) {
++		struct mp_add_addr *mpadd = (struct mp_add_addr *)ptr;
++
++		mpadd->kind = TCPOPT_MPTCP;
++		if (opts->add_addr_v4) {
++			mpadd->len = MPTCP_SUB_LEN_ADD_ADDR4;
++			mpadd->sub = MPTCP_SUB_ADD_ADDR;
++			mpadd->ipver = 4;
++			mpadd->addr_id = opts->add_addr4.addr_id;
++			mpadd->u.v4.addr = opts->add_addr4.addr;
++			ptr += MPTCP_SUB_LEN_ADD_ADDR4_ALIGN >> 2;
++		} else if (opts->add_addr_v6) {
++			mpadd->len = MPTCP_SUB_LEN_ADD_ADDR6;
++			mpadd->sub = MPTCP_SUB_ADD_ADDR;
++			mpadd->ipver = 6;
++			mpadd->addr_id = opts->add_addr6.addr_id;
++			memcpy(&mpadd->u.v6.addr, &opts->add_addr6.addr,
++			       sizeof(mpadd->u.v6.addr));
++			ptr += MPTCP_SUB_LEN_ADD_ADDR6_ALIGN >> 2;
++		}
++	}
++	if (unlikely(OPTION_REMOVE_ADDR & opts->mptcp_options)) {
++		struct mp_remove_addr *mprem = (struct mp_remove_addr *)ptr;
++		u8 *addrs_id;
++		int id, len, len_align;
++
++		len = mptcp_sub_len_remove_addr(opts->remove_addrs);
++		len_align = mptcp_sub_len_remove_addr_align(opts->remove_addrs);
++
++		mprem->kind = TCPOPT_MPTCP;
++		mprem->len = len;
++		mprem->sub = MPTCP_SUB_REMOVE_ADDR;
++		mprem->rsv = 0;
++		addrs_id = &mprem->addrs_id;
++
++		mptcp_for_each_bit_set(opts->remove_addrs, id)
++			*(addrs_id++) = id;
++
++		/* Fill the rest with NOP's */
++		if (len_align > len) {
++			int i;
++			for (i = 0; i < len_align - len; i++)
++				*(addrs_id++) = TCPOPT_NOP;
++		}
++
++		ptr += len_align >> 2;
++	}
++	if (unlikely(OPTION_MP_FAIL & opts->mptcp_options)) {
++		struct mp_fail *mpfail = (struct mp_fail *)ptr;
++
++		mpfail->kind = TCPOPT_MPTCP;
++		mpfail->len = MPTCP_SUB_LEN_FAIL;
++		mpfail->sub = MPTCP_SUB_FAIL;
++		mpfail->rsv1 = 0;
++		mpfail->rsv2 = 0;
++		mpfail->data_seq = htonll(tp->mpcb->csum_cutoff_seq);
++
++		ptr += MPTCP_SUB_LEN_FAIL_ALIGN >> 2;
++	}
++	if (unlikely(OPTION_MP_FCLOSE & opts->mptcp_options)) {
++		struct mp_fclose *mpfclose = (struct mp_fclose *)ptr;
++
++		mpfclose->kind = TCPOPT_MPTCP;
++		mpfclose->len = MPTCP_SUB_LEN_FCLOSE;
++		mpfclose->sub = MPTCP_SUB_FCLOSE;
++		mpfclose->rsv1 = 0;
++		mpfclose->rsv2 = 0;
++		mpfclose->key = opts->mp_capable.receiver_key;
++
++		ptr += MPTCP_SUB_LEN_FCLOSE_ALIGN >> 2;
++	}
++
++	if (OPTION_DATA_ACK & opts->mptcp_options) {
++		if (!mptcp_is_data_seq(skb))
++			ptr += mptcp_write_dss_data_ack(tp, skb, ptr);
++		else
++			ptr += mptcp_write_dss_data_seq(tp, skb, ptr);
++	}
++	if (unlikely(OPTION_MP_PRIO & opts->mptcp_options)) {
++		struct mp_prio *mpprio = (struct mp_prio *)ptr;
++
++		mpprio->kind = TCPOPT_MPTCP;
++		mpprio->len = MPTCP_SUB_LEN_PRIO;
++		mpprio->sub = MPTCP_SUB_PRIO;
++		mpprio->rsv = 0;
++		mpprio->b = tp->mptcp->low_prio;
++		mpprio->addr_id = TCPOPT_NOP;
++
++		ptr += MPTCP_SUB_LEN_PRIO_ALIGN >> 2;
++	}
++}
++
++/* Sends the datafin */
++void mptcp_send_fin(struct sock *meta_sk)
++{
++	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
++	struct sk_buff *skb = tcp_write_queue_tail(meta_sk);
++	int mss_now;
++
++	if ((1 << meta_sk->sk_state) & (TCPF_CLOSE_WAIT | TCPF_LAST_ACK))
++		meta_tp->mpcb->passive_close = 1;
++
++	/* Optimization, tack on the FIN if we have a queue of
++	 * unsent frames.  But be careful about outgoing SACKS
++	 * and IP options.
++	 */
++	mss_now = mptcp_current_mss(meta_sk);
++
++	if (tcp_send_head(meta_sk) != NULL) {
++		TCP_SKB_CB(skb)->mptcp_flags |= MPTCPHDR_FIN;
++		TCP_SKB_CB(skb)->end_seq++;
++		meta_tp->write_seq++;
++	} else {
++		/* Socket is locked, keep trying until memory is available. */
++		for (;;) {
++			skb = alloc_skb_fclone(MAX_TCP_HEADER,
++					       meta_sk->sk_allocation);
++			if (skb)
++				break;
++			yield();
++		}
++		/* Reserve space for headers and prepare control bits. */
++		skb_reserve(skb, MAX_TCP_HEADER);
++
++		tcp_init_nondata_skb(skb, meta_tp->write_seq, TCPHDR_ACK);
++		TCP_SKB_CB(skb)->end_seq++;
++		TCP_SKB_CB(skb)->mptcp_flags |= MPTCPHDR_FIN;
++		tcp_queue_skb(meta_sk, skb);
++	}
++	__tcp_push_pending_frames(meta_sk, mss_now, TCP_NAGLE_OFF);
++}
++
++void mptcp_send_active_reset(struct sock *meta_sk, gfp_t priority)
++{
++	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
++	struct mptcp_cb *mpcb = meta_tp->mpcb;
++	struct sock *sk = NULL, *sk_it = NULL, *tmpsk;
++
++	if (!mpcb->cnt_subflows)
++		return;
++
++	WARN_ON(meta_tp->send_mp_fclose);
++
++	/* First - select a socket */
++	sk = mptcp_select_ack_sock(meta_sk);
++
++	/* May happen if no subflow is in an appropriate state */
++	if (!sk)
++		return;
++
++	/* We are in infinite mode - just send a reset */
++	if (mpcb->infinite_mapping_snd || mpcb->infinite_mapping_rcv) {
++		sk->sk_err = ECONNRESET;
++		if (tcp_need_reset(sk->sk_state))
++			tcp_send_active_reset(sk, priority);
++		mptcp_sub_force_close(sk);
++		return;
++	}
++
++
++	tcp_sk(sk)->send_mp_fclose = 1;
++	/** Reset all other subflows */
++
++	/* tcp_done must be handled with bh disabled */
++	if (!in_serving_softirq())
++		local_bh_disable();
++
++	mptcp_for_each_sk_safe(mpcb, sk_it, tmpsk) {
++		if (tcp_sk(sk_it)->send_mp_fclose)
++			continue;
++
++		sk_it->sk_err = ECONNRESET;
++		if (tcp_need_reset(sk_it->sk_state))
++			tcp_send_active_reset(sk_it, GFP_ATOMIC);
++		mptcp_sub_force_close(sk_it);
++	}
++
++	if (!in_serving_softirq())
++		local_bh_enable();
++
++	tcp_send_ack(sk);
++	inet_csk_reset_keepalive_timer(sk, inet_csk(sk)->icsk_rto);
++
++	meta_tp->send_mp_fclose = 1;
++}
++
++static void mptcp_ack_retransmit_timer(struct sock *sk)
++{
++	struct sk_buff *skb;
++	struct tcp_sock *tp = tcp_sk(sk);
++	struct inet_connection_sock *icsk = inet_csk(sk);
++
++	if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk))
++		goto out; /* Routing failure or similar */
++
++	if (!tp->retrans_stamp)
++		tp->retrans_stamp = tcp_time_stamp ? : 1;
++
++	if (tcp_write_timeout(sk)) {
++		tp->mptcp->pre_established = 0;
++		sk_stop_timer(sk, &tp->mptcp->mptcp_ack_timer);
++		tp->ops->send_active_reset(sk, GFP_ATOMIC);
++		goto out;
++	}
++
++	skb = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC);
++	if (skb == NULL) {
++		sk_reset_timer(sk, &tp->mptcp->mptcp_ack_timer,
++			       jiffies + icsk->icsk_rto);
++		return;
++	}
++
++	/* Reserve space for headers and prepare control bits */
++	skb_reserve(skb, MAX_TCP_HEADER);
++	tcp_init_nondata_skb(skb, tp->snd_una, TCPHDR_ACK);
++
++	TCP_SKB_CB(skb)->when = tcp_time_stamp;
++	if (tcp_transmit_skb(sk, skb, 0, GFP_ATOMIC) > 0) {
++		/* Retransmission failed because of local congestion,
++		 * do not backoff.
++		 */
++		if (!icsk->icsk_retransmits)
++			icsk->icsk_retransmits = 1;
++		sk_reset_timer(sk, &tp->mptcp->mptcp_ack_timer,
++			       jiffies + icsk->icsk_rto);
++		return;
++	}
++
++
++	icsk->icsk_retransmits++;
++	icsk->icsk_rto = min(icsk->icsk_rto << 1, TCP_RTO_MAX);
++	sk_reset_timer(sk, &tp->mptcp->mptcp_ack_timer,
++		       jiffies + icsk->icsk_rto);
++	if (retransmits_timed_out(sk, sysctl_tcp_retries1 + 1, 0, 0))
++		__sk_dst_reset(sk);
++
++out:;
++}
++
++void mptcp_ack_handler(unsigned long data)
++{
++	struct sock *sk = (struct sock *)data;
++	struct sock *meta_sk = mptcp_meta_sk(sk);
++
++	bh_lock_sock(meta_sk);
++	if (sock_owned_by_user(meta_sk)) {
++		/* Try again later */
++		sk_reset_timer(sk, &tcp_sk(sk)->mptcp->mptcp_ack_timer,
++			       jiffies + (HZ / 20));
++		goto out_unlock;
++	}
++
++	if (sk->sk_state == TCP_CLOSE)
++		goto out_unlock;
++	if (!tcp_sk(sk)->mptcp->pre_established)
++		goto out_unlock;
++
++	mptcp_ack_retransmit_timer(sk);
++
++	sk_mem_reclaim(sk);
++
++out_unlock:
++	bh_unlock_sock(meta_sk);
++	sock_put(sk);
++}
++
++/* Similar to tcp_retransmit_skb
++ *
++ * The diff is that we handle the retransmission-stats (retrans_stamp) at the
++ * meta-level.
++ */
++int mptcp_retransmit_skb(struct sock *meta_sk, struct sk_buff *skb)
++{
++	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
++	struct sock *subsk;
++	unsigned int limit, mss_now;
++	int err = -1;
++
++	/* Do not sent more than we queued. 1/4 is reserved for possible
++	 * copying overhead: fragmentation, tunneling, mangling etc.
++	 *
++	 * This is a meta-retransmission thus we check on the meta-socket.
++	 */
++	if (atomic_read(&meta_sk->sk_wmem_alloc) >
++	    min(meta_sk->sk_wmem_queued + (meta_sk->sk_wmem_queued >> 2), meta_sk->sk_sndbuf)) {
++		return -EAGAIN;
++	}
++
++	/* We need to make sure that the retransmitted segment can be sent on a
++	 * subflow right now. If it is too big, it needs to be fragmented.
++	 */
++	subsk = meta_tp->mpcb->sched_ops->get_subflow(meta_sk, skb, false);
++	if (!subsk) {
++		/* We want to increase icsk_retransmits, thus return 0, so that
++		 * mptcp_retransmit_timer enters the desired branch.
++		 */
++		err = 0;
++		goto failed;
++	}
++	mss_now = tcp_current_mss(subsk);
++
++	/* If the segment was cloned (e.g. a meta retransmission), the header
++	 * must be expanded/copied so that there is no corruption of TSO
++	 * information.
++	 */
++	if (skb_unclone(skb, GFP_ATOMIC)) {
++		err = -ENOMEM;
++		goto failed;
++	}
++
++	/* Must have been set by mptcp_write_xmit before */
++	BUG_ON(!tcp_skb_pcount(skb));
++
++	limit = mss_now;
++	/* skb->len > mss_now is the equivalent of tso_segs > 1 in
++	 * tcp_write_xmit. Otherwise split-point would return 0.
++	 */
++	if (skb->len > mss_now && !tcp_urg_mode(meta_tp))
++		limit = tcp_mss_split_point(meta_sk, skb, mss_now,
++					    UINT_MAX / mss_now,
++					    TCP_NAGLE_OFF);
++
++	if (skb->len > limit &&
++	    unlikely(mptcp_fragment(meta_sk, skb, limit,
++				    GFP_ATOMIC, 0)))
++		goto failed;
++
++	if (!mptcp_skb_entail(subsk, skb, -1))
++		goto failed;
++	TCP_SKB_CB(skb)->when = tcp_time_stamp;
++
++	/* Update global TCP statistics. */
++	TCP_INC_STATS(sock_net(meta_sk), TCP_MIB_RETRANSSEGS);
++
++	/* Diff to tcp_retransmit_skb */
++
++	/* Save stamp of the first retransmit. */
++	if (!meta_tp->retrans_stamp)
++		meta_tp->retrans_stamp = TCP_SKB_CB(skb)->when;
++
++	__tcp_push_pending_frames(subsk, mss_now, TCP_NAGLE_PUSH);
++
++	return 0;
++
++failed:
++	NET_INC_STATS_BH(sock_net(meta_sk), LINUX_MIB_TCPRETRANSFAIL);
++	return err;
++}
++
++/* Similar to tcp_retransmit_timer
++ *
++ * The diff is that we have to handle retransmissions of the FAST_CLOSE-message
++ * and that we don't have an srtt estimation at the meta-level.
++ */
++void mptcp_retransmit_timer(struct sock *meta_sk)
++{
++	struct tcp_sock *meta_tp = tcp_sk(meta_sk);
++	struct mptcp_cb *mpcb = meta_tp->mpcb;
++	struct inet_connection_sock *meta_icsk = inet_csk(meta_sk);
++	int err;
++
++	/* In fallback, retransmission is handled at the subflow-level */
++	if (!meta_tp->packets_out || mpcb->infinite_mapping_snd ||
++	    mpcb->send_infinite_mapping)
++		return;
++
++	WARN_ON(tcp_write_queue_empty(meta_sk));
++
++	if (!meta_tp->snd_wnd && !sock_flag(meta_sk, SOCK_DEAD) &&
++	    !((1 << meta_sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))) {
++		/* Receiver dastardly shrinks window. Our retransmits
++		 * become zero probes, but we should not timeout this
++		 * connection. If the socket is an orphan, time it out,
++		 * we cannot allow such beasts to hang infinitely.
++		 */
++		struct inet_sock *meta_inet = inet_sk(meta_sk);
++		if (meta_sk->sk_family == AF_INET) {
++			LIMIT_NETDEBUG(KERN_DEBUG "MPTCP: Peer %pI4:%u/%u unexpectedly shrunk window %u:%u (repaired)\n",
++				       &meta_inet->inet_daddr,
++				       ntohs(meta_inet->inet_dport),
++				       meta_inet->inet_num, meta_tp->snd_una,
++				       meta_tp->snd_nxt);
++		}
++#if IS_ENABLED(CONFIG_IPV6)
++		else if (meta_sk->sk_family == AF_INET6) {
++			LIMIT_NETDEBUG(KERN_DEBUG "MPTCP: Peer %pI6:%u/%u unexpectedly shrunk window %u:%u (repaired)\n",
++				       &meta_sk->sk_v6_daddr,
++				       ntohs(meta_inet->inet_dport),
++				       meta_inet->inet_num, meta_tp->snd_una,
++				       meta_tp->snd_nxt);
++		}
++#endif
++		if (tcp_time_stamp - meta_tp->rcv_tstamp > TCP_RTO_MAX) {
++			tcp_write_err(meta_sk);
++			return;
++		}
++
++		mptcp_retransmit_skb(meta_sk, tcp_write_queue_head(meta_sk));
++		goto out_reset_timer;
++	}
++
++	if (tcp_write_timeout(meta_sk))
++		return;
++
++	if (meta_icsk->icsk_retransmits == 0)
++		NET_INC_STATS_BH(sock_net(meta_sk), LINUX_MIB_TCPTIMEOUTS);
++
++	meta_icsk->icsk_ca_state = TCP_CA_Loss;
++
++	err = mptcp_retransmit_skb(meta_sk, tcp_write_queue_head(meta_sk));
++	if (err > 0) {
++		/* Retransmission failed because of local congestion,
++		 * do not backoff.
++		 */
++		if (!meta_icsk->icsk_retransmits)
++			meta_icsk->icsk_retransmits = 1;
++		inet_csk_reset_xmit_timer(meta_sk, ICSK_TIME_RETRANS,
++					  min(meta_icsk->icsk_rto, TCP_RESOURCE_PROBE_INTERVAL),
++					  TCP_RTO_MAX);
++		return;
++	}
++
++	/* Increase the timeout each time we retransmit.  Note that
++	 * we do not increase the rtt estimate.  rto is initialized
++	 * from rtt, but increases here.  Jacobson (SIGCOMM 88) suggests
++	 * that doubling rto each time is the least we can get away with.
++	 * In KA9Q, Karn uses this for the first few times, and then
++	 * goes to quadratic.  netBSD doubles, but only goes up to *64,
++	 * and clamps at 1 to 64 sec afterwards.  Note that 120 sec is
++	 * defined in the protocol as the maximum possible RTT.  I guess
++	 * we'll have to use something other than TCP to talk to the
++	 * University of Mars.
++	 *
++	 * PAWS allows us longer timeouts and large windows, so once
++	 * implemented ftp to mars will work nicely. We will have to fix
++	 * the 120 second clamps though!
++	 */
++	meta_icsk->icsk_backoff++;
++	meta_icsk->icsk_retransmits++;
++
++out_reset_timer:
++	/* If stream is thin, use linear timeouts. Since 'icsk_backoff' is
++	 * used to reset timer, set to 0. Recalculate 'icsk_rto' as this
++	 * might be increased if the stream oscillates between thin and thick,
++	 * thus the old value might already be too high compared to the value
++	 * set by 'tcp_set_rto' in tcp_input.c which resets the rto without
++	 * backoff. Limit to TCP_THIN_LINEAR_RETRIES before initiating
++	 * exponential backoff behaviour to avoid continue hammering
++	 * linear-timeout retransmissions into a black hole
++	 */
++	if (meta_sk->sk_state == TCP_ESTABLISHED &&
++	    (meta_tp->thin_lto || sysctl_tcp_thin_linear_timeouts) &&
++	    tcp_stream_is_thin(meta_tp) &&
++	    meta_icsk->icsk_retransmits <= TCP_THIN_LINEAR_RETRIES) {
++		meta_icsk->icsk_backoff = 0;
++		/* We cannot do the same as in tcp_write_timer because the
++		 * srtt is not set here.
++		 */
++		mptcp_set_rto(meta_sk);
++	} else {
++		/* Use normal (exponential) backoff */
++		meta_icsk->icsk_rto = min(meta_icsk->icsk_rto << 1, TCP_RTO_MAX);
++	}
++	inet_csk_reset_xmit_timer(meta_sk, ICSK_TIME_RETRANS, meta_icsk->icsk_rto, TCP_RTO_MAX);
++
++	return;
++}
++
++/* Modify values to an mptcp-level for the initial window of new subflows */
++void mptcp_select_initial_window(int __space, __u32 mss, __u32 *rcv_wnd,
++				__u32 *window_clamp, int wscale_ok,
++				__u8 *rcv_wscale, __u32 init_rcv_wnd,
++				 const struct sock *sk)
++{
++	struct mptcp_cb *mpcb = tcp_sk(sk)->mpcb;
++
++	*window_clamp = mpcb->orig_window_clamp;
++	__space = tcp_win_from_space(mpcb->orig_sk_rcvbuf);
++
++	tcp_select_initial_window(__space, mss, rcv_wnd, window_clamp,
++				  wscale_ok, rcv_wscale, init_rcv_wnd, sk);
++}
++
++static inline u64 mptcp_calc_rate(const struct sock *meta_sk, unsigned int mss,
++				  unsigned int (*mss_cb)(struct sock *sk))
++{
++	struct sock *sk;
++	u64 rate = 0;
++
++	mptcp_for_each_sk(tcp_sk(meta_sk)->mpcb, sk) {
++		struct tcp_sock *tp = tcp_sk(sk);
++		int this_mss;
++		u64 this_rate;
++
++		if (!mptcp_sk_can_send(sk))
++			continue;
++
++		/* Do not consider subflows without a RTT estimation yet
++		 * otherwise this_rate >>> rate.
++		 */
++		if (unlikely(!tp->srtt_us))
++			continue;
++
++		this_mss = mss_cb(sk);
++
++		/* If this_mss is smaller than mss, it means that a segment will
++		 * be splitted in two (or more) when pushed on this subflow. If
++		 * you consider that mss = 1428 and this_mss = 1420 then two
++		 * segments will be generated: a 1420-byte and 8-byte segment.
++		 * The latter will introduce a large overhead as for a single
++		 * data segment 2 slots will be used in the congestion window.
++		 * Therefore reducing by ~2 the potential throughput of this
++		 * subflow. Indeed, 1428 will be send while 2840 could have been
++		 * sent if mss == 1420 reducing the throughput by 2840 / 1428.
++		 *
++		 * The following algorithm take into account this overhead
++		 * when computing the potential throughput that MPTCP can
++		 * achieve when generating mss-byte segments.
++		 *
++		 * The formulae is the following:
++		 *  \sum_{\forall sub} ratio * \frac{mss * cwnd_sub}{rtt_sub}
++		 * Where ratio is computed as follows:
++		 *  \frac{mss}{\ceil{mss / mss_sub} * mss_sub}
++		 *
++		 * ratio gives the reduction factor of the theoretical
++		 * throughput a subflow can achieve if MPTCP uses a specific
++		 * MSS value.
++		 */
++		this_rate = div64_u64((u64)mss * mss * (USEC_PER_SEC << 3) *
++				      max(tp->snd_cwnd, tp->packets_out),
++				      (u64)tp->srtt_us *
++				      DIV_ROUND_UP(mss, this_mss) * this_mss);
++		rate += this_rate;
++	}
++
++	return rate;
++}
++
++static unsigned int __mptcp_current_mss(const struct sock *meta_sk,
++					unsigned int (*mss_cb)(struct sock *sk))
++{
++	unsigned int mss = 0;
++	u64 rate = 0;
++	struct sock *sk;
++
++	mptcp_for_each_sk(tcp_sk(meta_sk)->mpcb, sk) {
++		int this_mss;
++		u64 this_rate;
++
++		if (!mptcp_sk_can_send(sk))
++			continue;
++
++		this_mss = mss_cb(sk);
++
++		/* Same mss values will produce the same throughput. */
++		if (this_mss == mss)
++			continue;
++
++		/* See whether using this mss value can theoretically improve
++		 * the performances.
++		 */
++		this_rate = mptcp_calc_rate(meta_sk, this_mss, mss_cb);
++		if (this_rate >= rate) {
++			mss = this_mss;
++			rate = this_rate;
++		}
++	}
++
++	return mss;
++}
++
++unsigned int mptcp_current_mss(struct sock *meta_sk)
++{
++	unsigned int mss = __mptcp_current_mss(meta_sk, tcp_current_mss);
++
++	/* If no subflow is available, we take a default-mss from the
++	 * meta-socket.
++	 */
++	return !mss ? tcp_current_mss(meta_sk) : mss;
++}
++
++static unsigned int mptcp_select_size_mss(struct sock *sk)
++{
++	return tcp_sk(sk)->mss_cache;
++}
++
++int mptcp_select_size(const struct sock *meta_sk, bool sg)
++{
++	unsigned int mss = __mptcp_current_mss(meta_sk, mptcp_select_size_mss);
++
++	if (sg) {
++		if (mptcp_sk_can_gso(meta_sk)) {
++			mss = SKB_WITH_OVERHEAD(2048 - MAX_TCP_HEADER);
++		} else {
++			int pgbreak = SKB_MAX_HEAD(MAX_TCP_HEADER);
++
++			if (mss >= pgbreak &&
++			    mss <= pgbreak + (MAX_SKB_FRAGS - 1) * PAGE_SIZE)
++				mss = pgbreak;
++		}
++	}
++
++	return !mss ? tcp_sk(meta_sk)->mss_cache : mss;
++}
++
++int mptcp_check_snd_buf(const struct tcp_sock *tp)
++{
++	const struct sock *sk;
++	u32 rtt_max = tp->srtt_us;
++	u64 bw_est;
++
++	if (!tp->srtt_us)
++		return tp->reordering + 1;
++
++	mptcp_for_each_sk(tp->mpcb, sk) {
++		if (!mptcp_sk_can_send(sk))
++			continue;
++
++		if (rtt_max < tcp_sk(sk)->srtt_us)
++			rtt_max = tcp_sk(sk)->srtt_us;
++	}
++
++	bw_est = div64_u64(((u64)tp->snd_cwnd * rtt_max) << 16,
++				(u64)tp->srtt_us);
++
++	return max_t(unsigned int, (u32)(bw_est >> 16),
++			tp->reordering + 1);
++}
++
++unsigned int mptcp_xmit_size_goal(const struct sock *meta_sk, u32 mss_now,
++				  int large_allowed)
++{
++	struct sock *sk;
++	u32 xmit_size_goal = 0;
++
++	if (large_allowed && mptcp_sk_can_gso(meta_sk)) {
++		mptcp_for_each_sk(tcp_sk(meta_sk)->mpcb, sk) {
++			int this_size_goal;
++
++			if (!mptcp_sk_can_send(sk))
++				continue;
++
++			this_size_goal = tcp_xmit_size_goal(sk, mss_now, 1);
++			if (this_size_goal > xmit_size_goal)
++				xmit_size_goal = this_size_goal;
++		}
++	}
++
++	return max(xmit_size_goal, mss_now);
++}
++
++/* Similar to tcp_trim_head - but we correctly copy the DSS-option */
++int mptcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len)
++{
++	if (skb_cloned(skb)) {
++		if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
++			return -ENOMEM;
++	}
++
++	__pskb_trim_head(skb, len);
++
++	TCP_SKB_CB(skb)->seq += len;
++	skb->ip_summed = CHECKSUM_PARTIAL;
++
++	skb->truesize	     -= len;
++	sk->sk_wmem_queued   -= len;
++	sk_mem_uncharge(sk, len);
++	sock_set_flag(sk, SOCK_QUEUE_SHRUNK);
++
++	/* Any change of skb->len requires recalculation of tso factor. */
++	if (tcp_skb_pcount(skb) > 1)
++		tcp_set_skb_tso_segs(sk, skb, tcp_skb_mss(skb));
++
++	return 0;
++}
+diff --git a/net/mptcp/mptcp_pm.c b/net/mptcp/mptcp_pm.c
+new file mode 100644
+index 000000000000..9542f950729f
+--- /dev/null
++++ b/net/mptcp/mptcp_pm.c
+@@ -0,0 +1,169 @@
++/*
++ *     MPTCP implementation - MPTCP-subflow-management
++ *
++ *     Initial Design & Implementation:
++ *     Sébastien Barré <sebastien.barre@×××××××××.be>
++ *
++ *     Current Maintainer & Author:
++ *     Christoph Paasch <christoph.paasch@×××××××××.be>
++ *
++ *     Additional authors:
++ *     Jaakko Korkeaniemi <jaakko.korkeaniemi@×××××.fi>
++ *     Gregory Detal <gregory.detal@×××××××××.be>
++ *     Fabien Duchêne <fabien.duchene@×××××××××.be>
++ *     Andreas Seelinger <Andreas.Seelinger@×××××××××××.de>
++ *     Lavkesh Lahngir <lavkesh51@×××××.com>
++ *     Andreas Ripke <ripke@××××××.eu>
++ *     Vlad Dogaru <vlad.dogaru@×××××.com>
++ *     Octavian Purdila <octavian.purdila@×××××.com>
++ *     John Ronan <jronan@××××.org>
++ *     Catalin Nicutar <catalin.nicutar@×××××.com>
++ *     Brandon Heller <brandonh@××××××××.edu>
++ *
++ *
++ *     This program is free software; you can redistribute it and/or
++ *      modify it under the terms of the GNU General Public License
++ *      as published by the Free Software Foundation; either version
++ *      2 of the License, or (at your option) any later version.
++ */
++
++
++#include <linux/module.h>
++#include <net/mptcp.h>
++
++static DEFINE_SPINLOCK(mptcp_pm_list_lock);
++static LIST_HEAD(mptcp_pm_list);
++
++static int mptcp_default_id(sa_family_t family, union inet_addr *addr,
++			    struct net *net, bool *low_prio)
++{
++	return 0;
++}
++
++struct mptcp_pm_ops mptcp_pm_default = {
++	.get_local_id = mptcp_default_id, /* We do not care */
++	.name = "default",
++	.owner = THIS_MODULE,
++};
++
++static struct mptcp_pm_ops *mptcp_pm_find(const char *name)
++{
++	struct mptcp_pm_ops *e;
++
++	list_for_each_entry_rcu(e, &mptcp_pm_list, list) {
++		if (strcmp(e->name, name) == 0)
++			return e;
++	}
++
++	return NULL;
++}
++
++int mptcp_register_path_manager(struct mptcp_pm_ops *pm)
++{
++	int ret = 0;
++
++	if (!pm->get_local_id)
++		return -EINVAL;
++
++	spin_lock(&mptcp_pm_list_lock);
++	if (mptcp_pm_find(pm->name)) {
++		pr_notice("%s already registered\n", pm->name);
++		ret = -EEXIST;
++	} else {
++		list_add_tail_rcu(&pm->list, &mptcp_pm_list);
++		pr_info("%s registered\n", pm->name);
++	}
++	spin_unlock(&mptcp_pm_list_lock);
++
++	return ret;
++}
++EXPORT_SYMBOL_GPL(mptcp_register_path_manager);
++
++void mptcp_unregister_path_manager(struct mptcp_pm_ops *pm)
++{
++	spin_lock(&mptcp_pm_list_lock);
++	list_del_rcu(&pm->list);
++	spin_unlock(&mptcp_pm_list_lock);
++}
++EXPORT_SYMBOL_GPL(mptcp_unregister_path_manager);
++
++void mptcp_get_default_path_manager(char *name)
++{
++	struct mptcp_pm_ops *pm;
++
++	BUG_ON(list_empty(&mptcp_pm_list));
++
++	rcu_read_lock();
++	pm = list_entry(mptcp_pm_list.next, struct mptcp_pm_ops, list);
++	strncpy(name, pm->name, MPTCP_PM_NAME_MAX);
++	rcu_read_unlock();
++}
++
++int mptcp_set_default_path_manager(const char *name)
++{
++	struct mptcp_pm_ops *pm;
++	int ret = -ENOENT;
++
++	spin_lock(&mptcp_pm_list_lock);
++	pm = mptcp_pm_find(name);
++#ifdef CONFIG_MODULES
++	if (!pm && capable(CAP_NET_ADMIN)) {
++		spin_unlock(&mptcp_pm_list_lock);
++
++		request_module("mptcp_%s", name);
++		spin_lock(&mptcp_pm_list_lock);
++		pm = mptcp_pm_find(name);
++	}
++#endif
++
++	if (pm) {
++		list_move(&pm->list, &mptcp_pm_list);
++		ret = 0;
++	} else {
++		pr_info("%s is not available\n", name);
++	}
++	spin_unlock(&mptcp_pm_list_lock);
++
++	return ret;
++}
++
++void mptcp_init_path_manager(struct mptcp_cb *mpcb)
++{
++	struct mptcp_pm_ops *pm;
++
++	rcu_read_lock();
++	list_for_each_entry_rcu(pm, &mptcp_pm_list, list) {
++		if (try_module_get(pm->owner)) {
++			mpcb->pm_ops = pm;
++			break;
++		}
++	}
++	rcu_read_unlock();
++}
++
++/* Manage refcounts on socket close. */
++void mptcp_cleanup_path_manager(struct mptcp_cb *mpcb)
++{
++	module_put(mpcb->pm_ops->owner);
++}
++
++/* Fallback to the default path-manager. */
++void mptcp_fallback_default(struct mptcp_cb *mpcb)
++{
++	struct mptcp_pm_ops *pm;
++
++	mptcp_cleanup_path_manager(mpcb);
++	pm = mptcp_pm_find("default");
++
++	/* Cannot fail - it's the default module */
++	try_module_get(pm->owner);
++	mpcb->pm_ops = pm;
++}
++EXPORT_SYMBOL_GPL(mptcp_fallback_default);
++
++/* Set default value from kernel configuration at bootup */
++static int __init mptcp_path_manager_default(void)
++{
++	return mptcp_set_default_path_manager(CONFIG_DEFAULT_MPTCP_PM);
++}
++late_initcall(mptcp_path_manager_default);
+diff --git a/net/mptcp/mptcp_rr.c b/net/mptcp/mptcp_rr.c
+new file mode 100644
+index 000000000000..93278f684069
+--- /dev/null
++++ b/net/mptcp/mptcp_rr.c
+@@ -0,0 +1,301 @@
++/* MPTCP Scheduler module selector. Highly inspired by tcp_cong.c */
++
++#include <linux/module.h>
++#include <net/mptcp.h>
++
++static unsigned char num_segments __read_mostly = 1;
++module_param(num_segments, byte, 0644);
++MODULE_PARM_DESC(num_segments, "The number of consecutive segments that are part of a burst");
++
++static bool cwnd_limited __read_mostly = 1;
++module_param(cwnd_limited, bool, 0644);
++MODULE_PARM_DESC(cwnd_limited, "if set to 1, the scheduler tries to fill the congestion-window on all subflows");
++
++struct rrsched_priv {
++	unsigned char quota;
++};
++
++static struct rrsched_priv *rrsched_get_priv(const struct tcp_sock *tp)
++{
++	return (struct rrsched_priv *)&tp->mptcp->mptcp_sched[0];
++}
++
++/* If the sub-socket sk available to send the skb? */
++static bool mptcp_rr_is_available(const struct sock *sk, const struct sk_buff *skb,
++				  bool zero_wnd_test, bool cwnd_test)
++{
++	const struct tcp_sock *tp = tcp_sk(sk);
++	unsigned int space, in_flight;
++
++	/* Set of states for which we are allowed to send data */
++	if (!mptcp_sk_can_send(sk))
++		return false;
++
++	/* We do not send data on this subflow unless it is
++	 * fully established, i.e. the 4th ack has been received.
++	 */
++	if (tp->mptcp->pre_established)
++		return false;
++
++	if (tp->pf)
++		return false;
++
++	if (inet_csk(sk)->icsk_ca_state == TCP_CA_Loss) {
++		/* If SACK is disabled, and we got a loss, TCP does not exit
++		 * the loss-state until something above high_seq has been acked.
++		 * (see tcp_try_undo_recovery)
++		 *
++		 * high_seq is the snd_nxt at the moment of the RTO. As soon
++		 * as we have an RTO, we won't push data on the subflow.
++		 * Thus, snd_una can never go beyond high_seq.
++		 */
++		if (!tcp_is_reno(tp))
++			return false;
++		else if (tp->snd_una != tp->high_seq)
++			return false;
++	}
++
++	if (!tp->mptcp->fully_established) {
++		/* Make sure that we send in-order data */
++		if (skb && tp->mptcp->second_packet &&
++		    tp->mptcp->last_end_data_seq != TCP_SKB_CB(skb)->seq)
++			return false;
++	}
++
++	if (!cwnd_test)
++		goto zero_wnd_test;
++
++	in_flight = tcp_packets_in_flight(tp);
++	/* Not even a single spot in the cwnd */
++	if (in_flight >= tp->snd_cwnd)
++		return false;
++
++	/* Now, check if what is queued in the subflow's send-queue
++	 * already fills the cwnd.
++	 */
++	space = (tp->snd_cwnd - in_flight) * tp->mss_cache;
++
++	if (tp->write_seq - tp->snd_nxt > space)
++		return false;
++
++zero_wnd_test:
++	if (zero_wnd_test && !before(tp->write_seq, tcp_wnd_end(tp)))
++		return false;
++
++	return true;
++}
++
++/* Are we not allowed to reinject this skb on tp? */
++static int mptcp_rr_dont_reinject_skb(const struct tcp_sock *tp, const struct sk_buff *skb)
++{
++	/* If the skb has already been enqueued in this sk, try to find
++	 * another one.
++	 */
++	return skb &&
++		/* Has the skb already been enqueued into this subsocket? */
++		mptcp_pi_to_flag(tp->mptcp->path_index) & TCP_SKB_CB(skb)->path_mask;
++}
++
++/* We just look for any subflow that is available */
++static struct sock *rr_get_available_subflow(struct sock *meta_sk,
++					     struct sk_buff *skb,
++					     bool zero_wnd_test)
++{
++	const struct mptcp_cb *mpcb = tcp_sk(meta_sk)->mpcb;
++	struct sock *sk, *bestsk = NULL, *backupsk = NULL;
++
++	/* Answer data_fin on same subflow!!! */
++	if (meta_sk->sk_shutdown & RCV_SHUTDOWN &&
++	    skb && mptcp_is_data_fin(skb)) {
++		mptcp_for_each_sk(mpcb, sk) {
++			if (tcp_sk(sk)->mptcp->path_index == mpcb->dfin_path_index &&
++			    mptcp_rr_is_available(sk, skb, zero_wnd_test, true))
++				return sk;
++		}
++	}
++
++	/* First, find the best subflow */
++	mptcp_for_each_sk(mpcb, sk) {
++		struct tcp_sock *tp = tcp_sk(sk);
++
++		if (!mptcp_rr_is_available(sk, skb, zero_wnd_test, true))
++			continue;
++
++		if (mptcp_rr_dont_reinject_skb(tp, skb)) {
++			backupsk = sk;
++			continue;
++		}
++
++		bestsk = sk;
++	}
++
++	if (bestsk) {
++		sk = bestsk;
++	} else if (backupsk) {
++		/* It has been sent on all subflows once - let's give it a
++		 * chance again by restarting its pathmask.
++		 */
++		if (skb)
++			TCP_SKB_CB(skb)->path_mask = 0;
++		sk = backupsk;
++	}
++
++	return sk;
++}
++
++/* Returns the next segment to be sent from the mptcp meta-queue.
++ * (chooses the reinject queue if any segment is waiting in it, otherwise,
++ * chooses the normal write queue).
++ * Sets *@reinject to 1 if the returned segment comes from the
++ * reinject queue. Sets it to 0 if it is the regular send-head of the meta-sk,
++ * and sets it to -1 if it is a meta-level retransmission to optimize the
++ * receive-buffer.
++ */
++static struct sk_buff *__mptcp_rr_next_segment(const struct sock *meta_sk, int *reinject)
++{
++	const struct mptcp_cb *mpcb = tcp_sk(meta_sk)->mpcb;
++	struct sk_buff *skb = NULL;
++
++	*reinject = 0;
++
++	/* If we are in fallback-mode, just take from the meta-send-queue */
++	if (mpcb->infinite_mapping_snd || mpcb->send_infinite_mapping)
++		return tcp_send_head(meta_sk);
++
++	skb = skb_peek(&mpcb->reinject_queue);
++
++	if (skb)
++		*reinject = 1;
++	else
++		skb = tcp_send_head(meta_sk);
++	return skb;
++}
++
++static struct sk_buff *mptcp_rr_next_segment(struct sock *meta_sk,
++					     int *reinject,
++					     struct sock **subsk,
++					     unsigned int *limit)
++{
++	const struct mptcp_cb *mpcb = tcp_sk(meta_sk)->mpcb;
++	struct sock *sk_it, *choose_sk = NULL;
++	struct sk_buff *skb = __mptcp_rr_next_segment(meta_sk, reinject);
++	unsigned char split = num_segments;
++	unsigned char iter = 0, full_subs = 0;
++
++	/* As we set it, we have to reset it as well. */
++	*limit = 0;
++
++	if (!skb)
++		return NULL;
++
++	if (*reinject) {
++		*subsk = rr_get_available_subflow(meta_sk, skb, false);
++		if (!*subsk)
++			return NULL;
++
++		return skb;
++	}
++
++retry:
++
++	/* First, we look for a subflow who is currently being used */
++	mptcp_for_each_sk(mpcb, sk_it) {
++		struct tcp_sock *tp_it = tcp_sk(sk_it);
++		struct rrsched_priv *rsp = rrsched_get_priv(tp_it);
++
++		if (!mptcp_rr_is_available(sk_it, skb, false, cwnd_limited))
++			continue;
++
++		iter++;
++
++		/* Is this subflow currently being used? */
++		if (rsp->quota > 0 && rsp->quota < num_segments) {
++			split = num_segments - rsp->quota;
++			choose_sk = sk_it;
++			goto found;
++		}
++
++		/* Or, it's totally unused */
++		if (!rsp->quota) {
++			split = num_segments;
++			choose_sk = sk_it;
++		}
++
++		/* Or, it must then be fully used  */
++		if (rsp->quota == num_segments)
++			full_subs++;
++	}
++
++	/* All considered subflows have a full quota, and we considered at
++	 * least one.
++	 */
++	if (iter && iter == full_subs) {
++		/* So, we restart this round by setting quota to 0 and retry
++		 * to find a subflow.
++		 */
++		mptcp_for_each_sk(mpcb, sk_it) {
++			struct tcp_sock *tp_it = tcp_sk(sk_it);
++			struct rrsched_priv *rsp = rrsched_get_priv(tp_it);
++
++			if (!mptcp_rr_is_available(sk_it, skb, false, cwnd_limited))
++				continue;
++
++			rsp->quota = 0;
++		}
++
++		goto retry;
++	}
++
++found:
++	if (choose_sk) {
++		unsigned int mss_now;
++		struct tcp_sock *choose_tp = tcp_sk(choose_sk);
++		struct rrsched_priv *rsp = rrsched_get_priv(choose_tp);
++
++		if (!mptcp_rr_is_available(choose_sk, skb, false, true))
++			return NULL;
++
++		*subsk = choose_sk;
++		mss_now = tcp_current_mss(*subsk);
++		*limit = split * mss_now;
++
++		if (skb->len > mss_now)
++			rsp->quota += DIV_ROUND_UP(skb->len, mss_now);
++		else
++			rsp->quota++;
++
++		return skb;
++	}
++
++	return NULL;
++}
++
++static struct mptcp_sched_ops mptcp_sched_rr = {
++	.get_subflow = rr_get_available_subflow,
++	.next_segment = mptcp_rr_next_segment,
++	.name = "roundrobin",
++	.owner = THIS_MODULE,
++};
++
++static int __init rr_register(void)
++{
++	BUILD_BUG_ON(sizeof(struct rrsched_priv) > MPTCP_SCHED_SIZE);
++
++	if (mptcp_register_scheduler(&mptcp_sched_rr))
++		return -1;
++
++	return 0;
++}
++
++static void rr_unregister(void)
++{
++	mptcp_unregister_scheduler(&mptcp_sched_rr);
++}
++
++module_init(rr_register);
++module_exit(rr_unregister);
++
++MODULE_AUTHOR("Christoph Paasch");
++MODULE_LICENSE("GPL");
++MODULE_DESCRIPTION("ROUNDROBIN MPTCP");
++MODULE_VERSION("0.89");
+diff --git a/net/mptcp/mptcp_sched.c b/net/mptcp/mptcp_sched.c
+new file mode 100644
+index 000000000000..6c7ff4eceac1
+--- /dev/null
++++ b/net/mptcp/mptcp_sched.c
+@@ -0,0 +1,493 @@
++/* MPTCP Scheduler module selector. Highly inspired by tcp_cong.c */
++
++#include <linux/module.h>
++#include <net/mptcp.h>
++
++static DEFINE_SPINLOCK(mptcp_sched_list_lock);
++static LIST_HEAD(mptcp_sched_list);
++
++struct defsched_priv {
++	u32	last_rbuf_opti;
++};
++
++static struct defsched_priv *defsched_get_priv(const struct tcp_sock *tp)
++{
++	return (struct defsched_priv *)&tp->mptcp->mptcp_sched[0];
++}
++
++/* If the sub-socket sk available to send the skb? */
++static bool mptcp_is_available(struct sock *sk, const struct sk_buff *skb,
++			       bool zero_wnd_test)
++{
++	const struct tcp_sock *tp = tcp_sk(sk);
++	unsigned int mss_now, space, in_flight;
++
++	/* Set of states for which we are allowed to send data */
++	if (!mptcp_sk_can_send(sk))
++		return false;
++
++	/* We do not send data on this subflow unless it is
++	 * fully established, i.e. the 4th ack has been received.
++	 */
++	if (tp->mptcp->pre_established)
++		return false;
++
++	if (tp->pf)
++		return false;
++
++	if (inet_csk(sk)->icsk_ca_state == TCP_CA_Loss) {
++		/* If SACK is disabled, and we got a loss, TCP does not exit
++		 * the loss-state until something above high_seq has been acked.
++		 * (see tcp_try_undo_recovery)
++		 *
++		 * high_seq is the snd_nxt at the moment of the RTO. As soon
++		 * as we have an RTO, we won't push data on the subflow.
++		 * Thus, snd_una can never go beyond high_seq.
++		 */
++		if (!tcp_is_reno(tp))
++			return false;
++		else if (tp->snd_una != tp->high_seq)
++			return false;
++	}
++
++	if (!tp->mptcp->fully_established) {
++		/* Make sure that we send in-order data */
++		if (skb && tp->mptcp->second_packet &&
++		    tp->mptcp->last_end_data_seq != TCP_SKB_CB(skb)->seq)
++			return false;
++	}
++
++	/* If TSQ is already throttling us, do not send on this subflow. When
++	 * TSQ gets cleared the subflow becomes eligible again.
++	 */
++	if (test_bit(TSQ_THROTTLED, &tp->tsq_flags))
++		return false;
++
++	in_flight = tcp_packets_in_flight(tp);
++	/* Not even a single spot in the cwnd */
++	if (in_flight >= tp->snd_cwnd)
++		return false;
++
++	/* Now, check if what is queued in the subflow's send-queue
++	 * already fills the cwnd.
++	 */
++	space = (tp->snd_cwnd - in_flight) * tp->mss_cache;
++
++	if (tp->write_seq - tp->snd_nxt > space)
++		return false;
++
++	if (zero_wnd_test && !before(tp->write_seq, tcp_wnd_end(tp)))
++		return false;
++
++	mss_now = tcp_current_mss(sk);
++
++	/* Don't send on this subflow if we bypass the allowed send-window at
++	 * the per-subflow level. Similar to tcp_snd_wnd_test, but manually
++	 * calculated end_seq (because here at this point end_seq is still at
++	 * the meta-level).
++	 */
++	if (skb && !zero_wnd_test &&
++	    after(tp->write_seq + min(skb->len, mss_now), tcp_wnd_end(tp)))
++		return false;
++
++	return true;
++}
++
++/* Are we not allowed to reinject this skb on tp? */
++static int mptcp_dont_reinject_skb(const struct tcp_sock *tp, const struct sk_buff *skb)
++{
++	/* If the skb has already been enqueued in this sk, try to find
++	 * another one.
++	 */
++	return skb &&
++		/* Has the skb already been enqueued into this subsocket? */
++		mptcp_pi_to_flag(tp->mptcp->path_index) & TCP_SKB_CB(skb)->path_mask;
++}
++
++/* This is the scheduler. This function decides on which flow to send
++ * a given MSS. If all subflows are found to be busy, NULL is returned
++ * The flow is selected based on the shortest RTT.
++ * If all paths have full cong windows, we simply return NULL.
++ *
++ * Additionally, this function is aware of the backup-subflows.
++ */
++static struct sock *get_available_subflow(struct sock *meta_sk,
++					  struct sk_buff *skb,
++					  bool zero_wnd_test)
++{
++	struct mptcp_cb *mpcb = tcp_sk(meta_sk)->mpcb;
++	struct sock *sk, *bestsk = NULL, *lowpriosk = NULL, *backupsk = NULL;
++	u32 min_time_to_peer = 0xffffffff, lowprio_min_time_to_peer = 0xffffffff;
++	int cnt_backups = 0;
++
++	/* if there is only one subflow, bypass the scheduling function */
++	if (mpcb->cnt_subflows == 1) {
++		bestsk = (struct sock *)mpcb->connection_list;
++		if (!mptcp_is_available(bestsk, skb, zero_wnd_test))
++			bestsk = NULL;
++		return bestsk;
++	}
++
++	/* Answer data_fin on same subflow!!! */
++	if (meta_sk->sk_shutdown & RCV_SHUTDOWN &&
++	    skb && mptcp_is_data_fin(skb)) {
++		mptcp_for_each_sk(mpcb, sk) {
++			if (tcp_sk(sk)->mptcp->path_index == mpcb->dfin_path_index &&
++			    mptcp_is_available(sk, skb, zero_wnd_test))
++				return sk;
++		}
++	}
++
++	/* First, find the best subflow */
++	mptcp_for_each_sk(mpcb, sk) {
++		struct tcp_sock *tp = tcp_sk(sk);
++
++		if (tp->mptcp->rcv_low_prio || tp->mptcp->low_prio)
++			cnt_backups++;
++
++		if ((tp->mptcp->rcv_low_prio || tp->mptcp->low_prio) &&
++		    tp->srtt_us < lowprio_min_time_to_peer) {
++			if (!mptcp_is_available(sk, skb, zero_wnd_test))
++				continue;
++
++			if (mptcp_dont_reinject_skb(tp, skb)) {
++				backupsk = sk;
++				continue;
++			}
++
++			lowprio_min_time_to_peer = tp->srtt_us;
++			lowpriosk = sk;
++		} else if (!(tp->mptcp->rcv_low_prio || tp->mptcp->low_prio) &&
++			   tp->srtt_us < min_time_to_peer) {
++			if (!mptcp_is_available(sk, skb, zero_wnd_test))
++				continue;
++
++			if (mptcp_dont_reinject_skb(tp, skb)) {
++				backupsk = sk;
++				continue;
++			}
++
++			min_time_to_peer = tp->srtt_us;
++			bestsk = sk;
++		}
++	}
++
++	if (mpcb->cnt_established == cnt_backups && lowpriosk) {
++		sk = lowpriosk;
++	} else if (bestsk) {
++		sk = bestsk;
++	} else if (backupsk) {
++		/* It has been sent on all subflows once - let's give it a
++		 * chance again by restarting its pathmask.
++		 */
++		if (skb)
++			TCP_SKB_CB(skb)->path_mask = 0;
++		sk = backupsk;
++	}
++
++	return sk;
++}
++
++static struct sk_buff *mptcp_rcv_buf_optimization(struct sock *sk, int penal)
++{
++	struct sock *meta_sk;
++	const struct tcp_sock *tp = tcp_sk(sk);
++	struct tcp_sock *tp_it;
++	struct sk_buff *skb_head;
++	struct defsched_priv *dsp = defsched_get_priv(tp);
++
++	if (tp->mpcb->cnt_subflows == 1)
++		return NULL;
++
++	meta_sk = mptcp_meta_sk(sk);
++	skb_head = tcp_write_queue_head(meta_sk);
++
++	if (!skb_head || skb_head == tcp_send_head(meta_sk))
++		return NULL;
++
++	/* If penalization is optional (coming from mptcp_next_segment() and
++	 * We are not send-buffer-limited we do not penalize. The retransmission
++	 * is just an optimization to fix the idle-time due to the delay before
++	 * we wake up the application.
++	 */
++	if (!penal && sk_stream_memory_free(meta_sk))
++		goto retrans;
++
++	/* Only penalize again after an RTT has elapsed */
++	if (tcp_time_stamp - dsp->last_rbuf_opti < usecs_to_jiffies(tp->srtt_us >> 3))
++		goto retrans;
++
++	/* Half the cwnd of the slow flow */
++	mptcp_for_each_tp(tp->mpcb, tp_it) {
++		if (tp_it != tp &&
++		    TCP_SKB_CB(skb_head)->path_mask & mptcp_pi_to_flag(tp_it->mptcp->path_index)) {
++			if (tp->srtt_us < tp_it->srtt_us && inet_csk((struct sock *)tp_it)->icsk_ca_state == TCP_CA_Open) {
++				tp_it->snd_cwnd = max(tp_it->snd_cwnd >> 1U, 1U);
++				if (tp_it->snd_ssthresh != TCP_INFINITE_SSTHRESH)
++					tp_it->snd_ssthresh = max(tp_it->snd_ssthresh >> 1U, 2U);
++
++				dsp->last_rbuf_opti = tcp_time_stamp;
++			}
++			break;
++		}
++	}
++
++retrans:
++
++	/* Segment not yet injected into this path? Take it!!! */
++	if (!(TCP_SKB_CB(skb_head)->path_mask & mptcp_pi_to_flag(tp->mptcp->path_index))) {
++		bool do_retrans = false;
++		mptcp_for_each_tp(tp->mpcb, tp_it) {
++			if (tp_it != tp &&
++			    TCP_SKB_CB(skb_head)->path_mask & mptcp_pi_to_flag(tp_it->mptcp->path_index)) {
++				if (tp_it->snd_cwnd <= 4) {
++					do_retrans = true;
++					break;
++				}
++
++				if (4 * tp->srtt_us >= tp_it->srtt_us) {
++					do_retrans = false;
++					break;
++				} else {
++					do_retrans = true;
++				}
++			}
++		}
++
++		if (do_retrans && mptcp_is_available(sk, skb_head, false))
++			return skb_head;
++	}
++	return NULL;
++}
++
++/* Returns the next segment to be sent from the mptcp meta-queue.
++ * (chooses the reinject queue if any segment is waiting in it, otherwise,
++ * chooses the normal write queue).
++ * Sets *@reinject to 1 if the returned segment comes from the
++ * reinject queue. Sets it to 0 if it is the regular send-head of the meta-sk,
++ * and sets it to -1 if it is a meta-level retransmission to optimize the
++ * receive-buffer.
++ */
++static struct sk_buff *__mptcp_next_segment(struct sock *meta_sk, int *reinject)
++{
++	const struct mptcp_cb *mpcb = tcp_sk(meta_sk)->mpcb;
++	struct sk_buff *skb = NULL;
++
++	*reinject = 0;
++
++	/* If we are in fallback-mode, just take from the meta-send-queue */
++	if (mpcb->infinite_mapping_snd || mpcb->send_infinite_mapping)
++		return tcp_send_head(meta_sk);
++
++	skb = skb_peek(&mpcb->reinject_queue);
++
++	if (skb) {
++		*reinject = 1;
++	} else {
++		skb = tcp_send_head(meta_sk);
++
++		if (!skb && meta_sk->sk_socket &&
++		    test_bit(SOCK_NOSPACE, &meta_sk->sk_socket->flags) &&
++		    sk_stream_wspace(meta_sk) < sk_stream_min_wspace(meta_sk)) {
++			struct sock *subsk = get_available_subflow(meta_sk, NULL,
++								   false);
++			if (!subsk)
++				return NULL;
++
++			skb = mptcp_rcv_buf_optimization(subsk, 0);
++			if (skb)
++				*reinject = -1;
++		}
++	}
++	return skb;
++}
++
++static struct sk_buff *mptcp_next_segment(struct sock *meta_sk,
++					  int *reinject,
++					  struct sock **subsk,
++					  unsigned int *limit)
++{
++	struct sk_buff *skb = __mptcp_next_segment(meta_sk, reinject);
++	unsigned int mss_now;
++	struct tcp_sock *subtp;
++	u16 gso_max_segs;
++	u32 max_len, max_segs, window, needed;
++
++	/* As we set it, we have to reset it as well. */
++	*limit = 0;
++
++	if (!skb)
++		return NULL;
++
++	*subsk = get_available_subflow(meta_sk, skb, false);
++	if (!*subsk)
++		return NULL;
++
++	subtp = tcp_sk(*subsk);
++	mss_now = tcp_current_mss(*subsk);
++
++	if (!*reinject && unlikely(!tcp_snd_wnd_test(tcp_sk(meta_sk), skb, mss_now))) {
++		skb = mptcp_rcv_buf_optimization(*subsk, 1);
++		if (skb)
++			*reinject = -1;
++		else
++			return NULL;
++	}
++
++	/* No splitting required, as we will only send one single segment */
++	if (skb->len <= mss_now)
++		return skb;
++
++	/* The following is similar to tcp_mss_split_point, but
++	 * we do not care about nagle, because we will anyways
++	 * use TCP_NAGLE_PUSH, which overrides this.
++	 *
++	 * So, we first limit according to the cwnd/gso-size and then according
++	 * to the subflow's window.
++	 */
++
++	gso_max_segs = (*subsk)->sk_gso_max_segs;
++	if (!gso_max_segs) /* No gso supported on the subflow's NIC */
++		gso_max_segs = 1;
++	max_segs = min_t(unsigned int, tcp_cwnd_test(subtp, skb), gso_max_segs);
++	if (!max_segs)
++		return NULL;
++
++	max_len = mss_now * max_segs;
++	window = tcp_wnd_end(subtp) - subtp->write_seq;
++
++	needed = min(skb->len, window);
++	if (max_len <= skb->len)
++		/* Take max_win, which is actually the cwnd/gso-size */
++		*limit = max_len;
++	else
++		/* Or, take the window */
++		*limit = needed;
++
++	return skb;
++}
++
++static void defsched_init(struct sock *sk)
++{
++	struct defsched_priv *dsp = defsched_get_priv(tcp_sk(sk));
++
++	dsp->last_rbuf_opti = tcp_time_stamp;
++}
++
++struct mptcp_sched_ops mptcp_sched_default = {
++	.get_subflow = get_available_subflow,
++	.next_segment = mptcp_next_segment,
++	.init = defsched_init,
++	.name = "default",
++	.owner = THIS_MODULE,
++};
++
++static struct mptcp_sched_ops *mptcp_sched_find(const char *name)
++{
++	struct mptcp_sched_ops *e;
++
++	list_for_each_entry_rcu(e, &mptcp_sched_list, list) {
++		if (strcmp(e->name, name) == 0)
++			return e;
++	}
++
++	return NULL;
++}
++
++int mptcp_register_scheduler(struct mptcp_sched_ops *sched)
++{
++	int ret = 0;
++
++	if (!sched->get_subflow || !sched->next_segment)
++		return -EINVAL;
++
++	spin_lock(&mptcp_sched_list_lock);
++	if (mptcp_sched_find(sched->name)) {
++		pr_notice("%s already registered\n", sched->name);
++		ret = -EEXIST;
++	} else {
++		list_add_tail_rcu(&sched->list, &mptcp_sched_list);
++		pr_info("%s registered\n", sched->name);
++	}
++	spin_unlock(&mptcp_sched_list_lock);
++
++	return ret;
++}
++EXPORT_SYMBOL_GPL(mptcp_register_scheduler);
++
++void mptcp_unregister_scheduler(struct mptcp_sched_ops *sched)
++{
++	spin_lock(&mptcp_sched_list_lock);
++	list_del_rcu(&sched->list);
++	spin_unlock(&mptcp_sched_list_lock);
++}
++EXPORT_SYMBOL_GPL(mptcp_unregister_scheduler);
++
++void mptcp_get_default_scheduler(char *name)
++{
++	struct mptcp_sched_ops *sched;
++
++	BUG_ON(list_empty(&mptcp_sched_list));
++
++	rcu_read_lock();
++	sched = list_entry(mptcp_sched_list.next, struct mptcp_sched_ops, list);
++	strncpy(name, sched->name, MPTCP_SCHED_NAME_MAX);
++	rcu_read_unlock();
++}
++
++int mptcp_set_default_scheduler(const char *name)
++{
++	struct mptcp_sched_ops *sched;
++	int ret = -ENOENT;
++
++	spin_lock(&mptcp_sched_list_lock);
++	sched = mptcp_sched_find(name);
++#ifdef CONFIG_MODULES
++	if (!sched && capable(CAP_NET_ADMIN)) {
++		spin_unlock(&mptcp_sched_list_lock);
++
++		request_module("mptcp_%s", name);
++		spin_lock(&mptcp_sched_list_lock);
++		sched = mptcp_sched_find(name);
++	}
++#endif
++
++	if (sched) {
++		list_move(&sched->list, &mptcp_sched_list);
++		ret = 0;
++	} else {
++		pr_info("%s is not available\n", name);
++	}
++	spin_unlock(&mptcp_sched_list_lock);
++
++	return ret;
++}
++
++void mptcp_init_scheduler(struct mptcp_cb *mpcb)
++{
++	struct mptcp_sched_ops *sched;
++
++	rcu_read_lock();
++	list_for_each_entry_rcu(sched, &mptcp_sched_list, list) {
++		if (try_module_get(sched->owner)) {
++			mpcb->sched_ops = sched;
++			break;
++		}
++	}
++	rcu_read_unlock();
++}
++
++/* Manage refcounts on socket close. */
++void mptcp_cleanup_scheduler(struct mptcp_cb *mpcb)
++{
++	module_put(mpcb->sched_ops->owner);
++}
++
++/* Set default value from kernel configuration at bootup */
++static int __init mptcp_scheduler_default(void)
++{
++	BUILD_BUG_ON(sizeof(struct defsched_priv) > MPTCP_SCHED_SIZE);
++
++	return mptcp_set_default_scheduler(CONFIG_DEFAULT_MPTCP_SCHED);
++}
++late_initcall(mptcp_scheduler_default);
+diff --git a/net/mptcp/mptcp_wvegas.c b/net/mptcp/mptcp_wvegas.c
+new file mode 100644
+index 000000000000..29ca1d868d17
+--- /dev/null
++++ b/net/mptcp/mptcp_wvegas.c
+@@ -0,0 +1,268 @@
++/*
++ *	MPTCP implementation - WEIGHTED VEGAS
++ *
++ *	Algorithm design:
++ *	Yu Cao <cyAnalyst@×××.com>
++ *	Mingwei Xu <xmw@××××××××××××××××××××××.cn>
++ *	Xiaoming Fu <fu@××××××××××××××××××.de>
++ *
++ *	Implementation:
++ *	Yu Cao <cyAnalyst@×××.com>
++ *	Enhuan Dong <deh13@××××××××××××××××××.cn>
++ *
++ *	Ported to the official MPTCP-kernel:
++ *	Christoph Paasch <christoph.paasch@×××××××××.be>
++ *
++ *	This program is free software; you can redistribute it and/or
++ *	modify it under the terms of the GNU General Public License
++ *	as published by the Free Software Foundation; either version
++ *	2 of the License, or (at your option) any later version.
++ */
++
++#include <linux/skbuff.h>
++#include <net/tcp.h>
++#include <net/mptcp.h>
++#include <linux/module.h>
++#include <linux/tcp.h>
++
++static int initial_alpha = 2;
++static int total_alpha = 10;
++static int gamma = 1;
++
++module_param(initial_alpha, int, 0644);
++MODULE_PARM_DESC(initial_alpha, "initial alpha for all subflows");
++module_param(total_alpha, int, 0644);
++MODULE_PARM_DESC(total_alpha, "total alpha for all subflows");
++module_param(gamma, int, 0644);
++MODULE_PARM_DESC(gamma, "limit on increase (scale by 2)");
++
++#define MPTCP_WVEGAS_SCALE 16
++
++/* wVegas variables */
++struct wvegas {
++	u32	beg_snd_nxt;	/* right edge during last RTT */
++	u8	doing_wvegas_now;/* if true, do wvegas for this RTT */
++
++	u16	cnt_rtt;		/* # of RTTs measured within last RTT */
++	u32 sampled_rtt; /* cumulative RTTs measured within last RTT (in usec) */
++	u32	base_rtt;	/* the min of all wVegas RTT measurements seen (in usec) */
++
++	u64 instant_rate; /* cwnd / srtt_us, unit: pkts/us * 2^16 */
++	u64 weight; /* the ratio of subflow's rate to the total rate, * 2^16 */
++	int alpha; /* alpha for each subflows */
++
++	u32 queue_delay; /* queue delay*/
++};
++
++
++static inline u64 mptcp_wvegas_scale(u32 val, int scale)
++{
++	return (u64) val << scale;
++}
++
++static void wvegas_enable(const struct sock *sk)
++{
++	const struct tcp_sock *tp = tcp_sk(sk);
++	struct wvegas *wvegas = inet_csk_ca(sk);
++
++	wvegas->doing_wvegas_now = 1;
++
++	wvegas->beg_snd_nxt = tp->snd_nxt;
++
++	wvegas->cnt_rtt = 0;
++	wvegas->sampled_rtt = 0;
++
++	wvegas->instant_rate = 0;
++	wvegas->alpha = initial_alpha;
++	wvegas->weight = mptcp_wvegas_scale(1, MPTCP_WVEGAS_SCALE);
++
++	wvegas->queue_delay = 0;
++}
++
++static inline void wvegas_disable(const struct sock *sk)
++{
++	struct wvegas *wvegas = inet_csk_ca(sk);
++
++	wvegas->doing_wvegas_now = 0;
++}
++
++static void mptcp_wvegas_init(struct sock *sk)
++{
++	struct wvegas *wvegas = inet_csk_ca(sk);
++
++	wvegas->base_rtt = 0x7fffffff;
++	wvegas_enable(sk);
++}
++
++static inline u64 mptcp_wvegas_rate(u32 cwnd, u32 rtt_us)
++{
++	return div_u64(mptcp_wvegas_scale(cwnd, MPTCP_WVEGAS_SCALE), rtt_us);
++}
++
++static void mptcp_wvegas_pkts_acked(struct sock *sk, u32 cnt, s32 rtt_us)
++{
++	struct wvegas *wvegas = inet_csk_ca(sk);
++	u32 vrtt;
++
++	if (rtt_us < 0)
++		return;
++
++	vrtt = rtt_us + 1;
++
++	if (vrtt < wvegas->base_rtt)
++		wvegas->base_rtt = vrtt;
++
++	wvegas->sampled_rtt += vrtt;
++	wvegas->cnt_rtt++;
++}
++
++static void mptcp_wvegas_state(struct sock *sk, u8 ca_state)
++{
++	if (ca_state == TCP_CA_Open)
++		wvegas_enable(sk);
++	else
++		wvegas_disable(sk);
++}
++
++static void mptcp_wvegas_cwnd_event(struct sock *sk, enum tcp_ca_event event)
++{
++	if (event == CA_EVENT_CWND_RESTART) {
++		mptcp_wvegas_init(sk);
++	} else if (event == CA_EVENT_LOSS) {
++		struct wvegas *wvegas = inet_csk_ca(sk);
++		wvegas->instant_rate = 0;
++	}
++}
++
++static inline u32 mptcp_wvegas_ssthresh(const struct tcp_sock *tp)
++{
++	return  min(tp->snd_ssthresh, tp->snd_cwnd - 1);
++}
++
++static u64 mptcp_wvegas_weight(const struct mptcp_cb *mpcb, const struct sock *sk)
++{
++	u64 total_rate = 0;
++	struct sock *sub_sk;
++	const struct wvegas *wvegas = inet_csk_ca(sk);
++
++	if (!mpcb)
++		return wvegas->weight;
++
++
++	mptcp_for_each_sk(mpcb, sub_sk) {
++		struct wvegas *sub_wvegas = inet_csk_ca(sub_sk);
++
++		/* sampled_rtt is initialized by 0 */
++		if (mptcp_sk_can_send(sub_sk) && (sub_wvegas->sampled_rtt > 0))
++			total_rate += sub_wvegas->instant_rate;
++	}
++
++	if (total_rate && wvegas->instant_rate)
++		return div64_u64(mptcp_wvegas_scale(wvegas->instant_rate, MPTCP_WVEGAS_SCALE), total_rate);
++	else
++		return wvegas->weight;
++}
++
++static void mptcp_wvegas_cong_avoid(struct sock *sk, u32 ack, u32 acked)
++{
++	struct tcp_sock *tp = tcp_sk(sk);
++	struct wvegas *wvegas = inet_csk_ca(sk);
++
++	if (!wvegas->doing_wvegas_now) {
++		tcp_reno_cong_avoid(sk, ack, acked);
++		return;
++	}
++
++	if (after(ack, wvegas->beg_snd_nxt)) {
++		wvegas->beg_snd_nxt  = tp->snd_nxt;
++
++		if (wvegas->cnt_rtt <= 2) {
++			tcp_reno_cong_avoid(sk, ack, acked);
++		} else {
++			u32 rtt, diff, q_delay;
++			u64 target_cwnd;
++
++			rtt = wvegas->sampled_rtt / wvegas->cnt_rtt;
++			target_cwnd = div_u64(((u64)tp->snd_cwnd * wvegas->base_rtt), rtt);
++
++			diff = div_u64((u64)tp->snd_cwnd * (rtt - wvegas->base_rtt), rtt);
++
++			if (diff > gamma && tp->snd_cwnd <= tp->snd_ssthresh) {
++				tp->snd_cwnd = min(tp->snd_cwnd, (u32)target_cwnd+1);
++				tp->snd_ssthresh = mptcp_wvegas_ssthresh(tp);
++
++			} else if (tp->snd_cwnd <= tp->snd_ssthresh) {
++				tcp_slow_start(tp, acked);
++			} else {
++				if (diff >= wvegas->alpha) {
++					wvegas->instant_rate = mptcp_wvegas_rate(tp->snd_cwnd, rtt);
++					wvegas->weight = mptcp_wvegas_weight(tp->mpcb, sk);
++					wvegas->alpha = max(2U, (u32)((wvegas->weight * total_alpha) >> MPTCP_WVEGAS_SCALE));
++				}
++				if (diff > wvegas->alpha) {
++					tp->snd_cwnd--;
++					tp->snd_ssthresh = mptcp_wvegas_ssthresh(tp);
++				} else if (diff < wvegas->alpha) {
++					tp->snd_cwnd++;
++				}
++
++				/* Try to drain link queue if needed*/
++				q_delay = rtt - wvegas->base_rtt;
++				if ((wvegas->queue_delay == 0) || (wvegas->queue_delay > q_delay))
++					wvegas->queue_delay = q_delay;
++
++				if (q_delay >= 2 * wvegas->queue_delay) {
++					u32 backoff_factor = div_u64(mptcp_wvegas_scale(wvegas->base_rtt, MPTCP_WVEGAS_SCALE), 2 * rtt);
++					tp->snd_cwnd = ((u64)tp->snd_cwnd * backoff_factor) >> MPTCP_WVEGAS_SCALE;
++					wvegas->queue_delay = 0;
++				}
++			}
++
++			if (tp->snd_cwnd < 2)
++				tp->snd_cwnd = 2;
++			else if (tp->snd_cwnd > tp->snd_cwnd_clamp)
++				tp->snd_cwnd = tp->snd_cwnd_clamp;
++
++			tp->snd_ssthresh = tcp_current_ssthresh(sk);
++		}
++
++		wvegas->cnt_rtt = 0;
++		wvegas->sampled_rtt = 0;
++	}
++	/* Use normal slow start */
++	else if (tp->snd_cwnd <= tp->snd_ssthresh)
++		tcp_slow_start(tp, acked);
++}
++
++
++static struct tcp_congestion_ops mptcp_wvegas __read_mostly = {
++	.init		= mptcp_wvegas_init,
++	.ssthresh	= tcp_reno_ssthresh,
++	.cong_avoid	= mptcp_wvegas_cong_avoid,
++	.pkts_acked	= mptcp_wvegas_pkts_acked,
++	.set_state	= mptcp_wvegas_state,
++	.cwnd_event	= mptcp_wvegas_cwnd_event,
++
++	.owner		= THIS_MODULE,
++	.name		= "wvegas",
++};
++
++static int __init mptcp_wvegas_register(void)
++{
++	BUILD_BUG_ON(sizeof(struct wvegas) > ICSK_CA_PRIV_SIZE);
++	tcp_register_congestion_control(&mptcp_wvegas);
++	return 0;
++}
++
++static void __exit mptcp_wvegas_unregister(void)
++{
++	tcp_unregister_congestion_control(&mptcp_wvegas);
++}
++
++module_init(mptcp_wvegas_register);
++module_exit(mptcp_wvegas_unregister);
++
++MODULE_AUTHOR("Yu Cao, Enhuan Dong");
++MODULE_LICENSE("GPL");
++MODULE_DESCRIPTION("MPTCP wVegas");
++MODULE_VERSION("0.1");