diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 67309ec..8758360 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -126,6 +126,10 @@ static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req)
  	return (struct tcp_request_sock *)req;
  }
  
+#ifdef CONFIG_TCP_ESTATS
+struct tcp_estats;
+#endif
+
  struct tcp_sock {
  	/* inet_connection_sock has to be the first member of tcp_sock */
  	struct inet_connection_sock	inet_conn;
@@ -309,6 +313,10 @@ struct tcp_sock {
  	struct tcp_md5sig_info	__rcu *md5sig_info;
  #endif
  
+#ifdef CONFIG_TCP_ESTATS
+	struct tcp_estats	*tcp_stats;
+#endif
+
  /* TCP fastopen related information */
  	struct tcp_fastopen_request *fastopen_req;
  	/* fastopen_rsk points to request_sock that resulted in this big
diff --git a/include/net/tcp_estats.h b/include/net/tcp_estats.h
new file mode 100644
index 0000000..ff6000e
--- /dev/null
+++ b/include/net/tcp_estats.h
@@ -0,0 +1,376 @@
+/*
+ * include/net/tcp_estats.h
+ *
+ * Implementation of TCP Extended Statistics MIB (RFC 4898)
+ *
+ * Authors:
+ *   John Estabrook <jsestabrook@gmail.com>
+ *   Andrew K. Adams <akadams@psc.edu>
+ *   Kevin Hogan <kwabena@google.com>
+ *   Dominin Hamon <dma@stripysock.com>
+ *   John Heffner <johnwheffner@gmail.com>
+ *
+ * The Web10Gig project.  See http://www.web10gig.org
+ *
+ * Copyright © 2011, Pittsburgh Supercomputing Center (PSC).
+ * 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 _TCP_ESTATS_H
+#define _TCP_ESTATS_H
+
+#include <net/sock.h>
+#include <linux/idr.h>
+#include <linux/in.h>
+#include <linux/jump_label.h>
+#include <linux/spinlock.h>
+#include <linux/tcp.h>
+#include <linux/workqueue.h>
+
+/* defines number of seconds that stats persist after connection ends */
+#define TCP_ESTATS_PERSIST_DELAY_SECS 5
+
+enum tcp_estats_sndlim_states {
+	TCP_ESTATS_SNDLIM_NONE = -1,
+	TCP_ESTATS_SNDLIM_SENDER,
+	TCP_ESTATS_SNDLIM_CWND,
+	TCP_ESTATS_SNDLIM_RWIN,
+	TCP_ESTATS_SNDLIM_STARTUP,
+	TCP_ESTATS_SNDLIM_TSODEFER,
+	TCP_ESTATS_SNDLIM_PACE,
+	TCP_ESTATS_SNDLIM_NSTATES	/* Keep at end */
+};
+
+enum tcp_estats_addrtype {
+	TCP_ESTATS_ADDRTYPE_IPV4 = 1,
+	TCP_ESTATS_ADDRTYPE_IPV6 = 2
+};
+
+enum tcp_estats_softerror_reason {
+	TCP_ESTATS_SOFTERROR_BELOW_DATA_WINDOW = 1,
+	TCP_ESTATS_SOFTERROR_ABOVE_DATA_WINDOW = 2,
+	TCP_ESTATS_SOFTERROR_BELOW_ACK_WINDOW = 3,
+	TCP_ESTATS_SOFTERROR_ABOVE_ACK_WINDOW = 4,
+	TCP_ESTATS_SOFTERROR_BELOW_TS_WINDOW = 5,
+	TCP_ESTATS_SOFTERROR_ABOVE_TS_WINDOW = 6,
+	TCP_ESTATS_SOFTERROR_DATA_CHECKSUM = 7,
+	TCP_ESTATS_SOFTERROR_OTHER = 8,
+};
+
+#define TCP_ESTATS_INACTIVE	2
+#define TCP_ESTATS_ACTIVE	1
+
+#define TCP_ESTATS_TABLEMASK_INACTIVE	0x00
+#define TCP_ESTATS_TABLEMASK_ACTIVE	0x01
+#define TCP_ESTATS_TABLEMASK_PERF	0x02
+#define TCP_ESTATS_TABLEMASK_PATH	0x04
+#define TCP_ESTATS_TABLEMASK_STACK	0x08
+#define TCP_ESTATS_TABLEMASK_APP	0x10
+#define TCP_ESTATS_TABLEMASK_EXTRAS	0x40
+
+#ifdef CONFIG_TCP_ESTATS
+
+extern struct static_key tcp_estats_enabled;
+
+#define TCP_ESTATS_CHECK(tp, table, expr)				\
+	do {								\
+		if (static_key_false(&tcp_estats_enabled)) {		\
+			if (likely((tp)->tcp_stats) &&			\
+			    likely((tp)->tcp_stats->tables.table)) {	\
+				(expr);					\
+			}						\
+		}							\
+	} while (0)
+
+#define TCP_ESTATS_VAR_INC(tp, table, var)				\
+	TCP_ESTATS_CHECK(tp, table, ++((tp)->tcp_stats->tables.table->var))
+#define TCP_ESTATS_VAR_DEC(tp, table, var)				\
+	TCP_ESTATS_CHECK(tp, table, --((tp)->tcp_stats->tables.table->var))
+#define TCP_ESTATS_VAR_ADD(tp, table, var, val)				\
+	TCP_ESTATS_CHECK(tp, table,					\
+			 ((tp)->tcp_stats->tables.table->var) += (val))
+#define TCP_ESTATS_VAR_SET(tp, table, var, val)				\
+	TCP_ESTATS_CHECK(tp, table,					\
+			 ((tp)->tcp_stats->tables.table->var) = (val))
+#define TCP_ESTATS_UPDATE(tp, func)					\
+	do {								\
+		if (static_key_false(&tcp_estats_enabled)) {		\
+			if (likely((tp)->tcp_stats)) {			\
+				(func);					\
+			}						\
+		}							\
+	} while (0)
+
+/*
+ * Variables that can be read and written directly.
+ *
+ * Contains all variables from RFC 4898. Commented fields are
+ * either not implemented (only StartTimeStamp
+ * remains unimplemented in this release) or have
+ * handlers and do not need struct storage.
+ */
+struct tcp_estats_connection_table {
+	u32			AddressType;
+	union { struct in_addr addr; struct in6_addr addr6; }	LocalAddress;
+	union { struct in_addr addr; struct in6_addr addr6; }	RemAddress;
+	u16			LocalPort;
+	u16			RemPort;
+};
+
+struct tcp_estats_perf_table {
+	u32		SegsOut;
+	u32		DataSegsOut;
+	u64		DataOctetsOut;
+	u32		SegsRetrans;
+	u32		OctetsRetrans;
+	u32		SegsIn;
+	u32		DataSegsIn;
+	u64		DataOctetsIn;
+	/*		ElapsedSecs */
+	/*		ElapsedMicroSecs */
+	/*		StartTimeStamp */
+	/*		CurMSS */
+	/*		PipeSize */
+	u32		MaxPipeSize;
+	/*		SmoothedRTT */
+	/*		CurRTO */
+	u32		CongSignals;
+	/*		CurCwnd */
+	/*		CurSsthresh */
+	u32		Timeouts;
+	/*		CurRwinSent */
+	u32		MaxRwinSent;
+	u32		ZeroRwinSent;
+	/*		CurRwinRcvd */
+	u32		MaxRwinRcvd;
+	u32		ZeroRwinRcvd;
+	/*		SndLimTransRwin */
+	/*		SndLimTransCwnd */
+	/*		SndLimTransSnd */
+	/*		SndLimTimeRwin */
+	/*		SndLimTimeCwnd */
+	/*		SndLimTimeSnd */
+	u32		snd_lim_trans[TCP_ESTATS_SNDLIM_NSTATES];
+	u32		snd_lim_time[TCP_ESTATS_SNDLIM_NSTATES];
+};
+
+struct tcp_estats_path_table {
+	/*		RetranThresh */
+	u32		NonRecovDAEpisodes;
+	u32		SumOctetsReordered;
+	u32		NonRecovDA;
+	u32		SampleRTT;
+	/*		RTTVar */
+	u32		MaxRTT;
+	u32		MinRTT;
+	u64		SumRTT;
+	u32		CountRTT;
+	u32		MaxRTO;
+	u32		MinRTO;
+	u8		IpTtl;
+	u8		IpTosIn;
+	/*		IpTosOut */
+	u32		PreCongSumCwnd;
+	u32		PreCongSumRTT;
+	u32		PostCongSumRTT;
+	u32		PostCongCountRTT;
+	u32		ECNsignals;
+	u32		DupAckEpisodes;
+	/*		RcvRTT */
+	u32		DupAcksOut;
+	u32		CERcvd;
+	u32		ECESent;
+};
+
+struct tcp_estats_stack_table {
+	u32		ActiveOpen;
+	/*		MSSSent */
+	/*		MSSRcvd */
+	/*		WinScaleSent */
+	/*		WinScaleRcvd */
+	/*		TimeStamps */
+	/*		ECN */
+	/*		WillSendSACK */
+	/*		WillUseSACK */
+	/*		State */
+	/*		Nagle */
+	u32		MaxSsCwnd;
+	u32		MaxCaCwnd;
+	u32		MaxSsthresh;
+	u32		MinSsthresh;
+	/*		InRecovery */
+	u32		DupAcksIn;
+	u32		SpuriousFrDetected;
+	u32		SpuriousRtoDetected;
+	u32		SoftErrors;
+	u32		SoftErrorReason;
+	u32		SlowStart;
+	u32		CongAvoid;
+	u32		OtherReductions;
+	u32		CongOverCount;
+	u32		FastRetran;
+	u32		SubsequentTimeouts;
+	/*		CurTimeoutCount */
+	u32		AbruptTimeouts;
+	u32		SACKsRcvd;
+	u32		SACKBlocksRcvd;
+	u32		SendStall;
+	u32		DSACKDups;
+	u32		MaxMSS;
+	u32		MinMSS;
+	u32		SndInitial;
+	u32		RecInitial;
+	/*		CurRetxQueue */
+	/*		MaxRetxQueue */
+	/*		CurReasmQueue */
+	u32		MaxReasmQueue;
+	u32		EarlyRetrans;
+	u32		EarlyRetransDelay;
+};
+
+struct tcp_estats_app_table {
+	/*		SndUna */
+	/*		SndNxt */
+	u32		SndMax;
+	u64		ThruOctetsAcked;
+	/*		RcvNxt */
+	u64		ThruOctetsReceived;
+	/*		CurAppWQueue */
+	u32		MaxAppWQueue;
+	/*		CurAppRQueue */
+	u32		MaxAppRQueue;
+};
+
+/*
+    currently, no backing store is needed for tuning elements in
+     web10g - they are all read or written to directly in other
+     data structures (such as the socket)
+*/
+
+struct tcp_estats_extras_table {
+	/*		OtherReductionsCV */
+	u32		OtherReductionsCM;
+	u32		Priority;
+};
+
+struct tcp_estats_tables {
+	struct tcp_estats_connection_table	*connection_table;
+	struct tcp_estats_perf_table		*perf_table;
+	struct tcp_estats_path_table		*path_table;
+	struct tcp_estats_stack_table		*stack_table;
+	struct tcp_estats_app_table		*app_table;
+	struct tcp_estats_extras_table		*extras_table;
+};
+
+struct tcp_estats {
+	int				tcpe_cid; /* idr map id */
+
+	struct sock			*sk;
+	kuid_t				uid;
+	kgid_t				gid;
+	int				ids;
+
+	atomic_t			users;
+
+	enum tcp_estats_sndlim_states	limstate;
+	ktime_t				limstate_ts;
+#ifdef CONFIG_TCP_ESTATS_STRICT_ELAPSEDTIME
+	ktime_t				start_ts;
+	ktime_t				current_ts;
+#else
+	unsigned long			start_ts;
+	unsigned long			current_ts;
+#endif
+	struct timeval			start_tv;
+
+        int				queued;
+        struct work_struct		create_notify;
+        struct work_struct		establish_notify;
+        struct delayed_work		destroy_notify;
+
+	struct tcp_estats_tables	tables;
+
+	struct rcu_head			rcu;
+};
+
+extern struct idr tcp_estats_idr;
+
+extern int tcp_estats_wq_enabled;
+extern struct workqueue_struct *tcp_estats_wq;
+extern void (*create_notify_func)(struct work_struct *work);
+extern void (*establish_notify_func)(struct work_struct *work);
+extern void (*destroy_notify_func)(struct work_struct *work);
+
+extern unsigned long persist_delay;
+extern spinlock_t tcp_estats_idr_lock;
+
+/* For the TCP code */
+extern int  tcp_estats_create(struct sock *sk, enum tcp_estats_addrtype t,
+			      int active);
+extern void tcp_estats_destroy(struct sock *sk);
+extern void tcp_estats_establish(struct sock *sk);
+extern void tcp_estats_free(struct rcu_head *rcu);
+
+extern void tcp_estats_update_snd_nxt(struct tcp_sock *tp);
+extern void tcp_estats_update_acked(struct tcp_sock *tp, u32 ack);
+extern void tcp_estats_update_rtt(struct sock *sk, unsigned long rtt_sample);
+extern void tcp_estats_update_timeout(struct sock *sk);
+extern void tcp_estats_update_mss(struct tcp_sock *tp);
+extern void tcp_estats_update_rwin_rcvd(struct tcp_sock *tp);
+extern void tcp_estats_update_sndlim(struct tcp_sock *tp,
+				     enum tcp_estats_sndlim_states why);
+extern void tcp_estats_update_rcvd(struct tcp_sock *tp, u32 seq);
+extern void tcp_estats_update_rwin_sent(struct tcp_sock *tp);
+extern void tcp_estats_update_congestion(struct tcp_sock *tp);
+extern void tcp_estats_update_post_congestion(struct tcp_sock *tp);
+extern void tcp_estats_update_segsend(struct sock *sk, int pcount,
+                                      u32 seq, u32 end_seq, int flags);
+extern void tcp_estats_update_segrecv(struct tcp_sock *tp, struct sk_buff *skb);
+extern void tcp_estats_update_finish_segrecv(struct tcp_sock *tp);
+extern void tcp_estats_update_writeq(struct sock *sk);
+extern void tcp_estats_update_recvq(struct sock *sk);
+
+extern void tcp_estats_init(void);
+
+static inline void tcp_estats_use(struct tcp_estats *stats)
+{
+	atomic_inc(&stats->users);
+}
+
+static inline int tcp_estats_use_if_valid(struct tcp_estats *stats)
+{
+	return atomic_inc_not_zero(&stats->users);
+}
+
+static inline void tcp_estats_unuse(struct tcp_estats *stats)
+{
+	if (atomic_dec_and_test(&stats->users)) {
+		sock_put(stats->sk);
+		stats->sk = NULL;
+		call_rcu(&stats->rcu, tcp_estats_free);
+	}
+}
+
+#else /* !CONFIG_TCP_ESTATS */
+
+#define tcp_estats_enabled	(0)
+
+#define TCP_ESTATS_VAR_INC(tp, table, var)	do {} while (0)
+#define TCP_ESTATS_VAR_DEC(tp, table, var)	do {} while (0)
+#define TCP_ESTATS_VAR_ADD(tp, table, var, val)	do {} while (0)
+#define TCP_ESTATS_VAR_SET(tp, table, var, val)	do {} while (0)
+#define TCP_ESTATS_UPDATE(tp, func)		do {} while (0)
+
+static inline void tcp_estats_init(void) { }
+static inline void tcp_estats_establish(struct sock *sk) { }
+static inline void tcp_estats_create(struct sock *sk,
+				     enum tcp_estats_addrtype t,
+				     int active) { }
+static inline void tcp_estats_destroy(struct sock *sk) { }
+
+#endif /* CONFIG_TCP_ESTATS */
+
+#endif /* _TCP_ESTATS_H */
diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig
index bd29016..c04ba8f 100644
--- a/net/ipv4/Kconfig
+++ b/net/ipv4/Kconfig
@@ -680,3 +680,28 @@ config TCP_MD5SIG
  	  on the Internet.
  
  	  If unsure, say N.
+
+config TCP_ESTATS
+	bool "TCP: Extended TCP statistics (RFC4898) MIB"
+	---help---
+	  RFC 4898 specifies a number of extended statistics for TCP. This
+	  data can be accessed using netlink. See http://www.web10g.org for
+	  more details.
+
+if TCP_ESTATS
+
+config TCP_ESTATS_STRICT_ELAPSEDTIME	
+	bool "TCP: ESTATS strict ElapsedSecs/Msecs counters"
+	depends on TCP_ESTATS
+	default n
+	---help---
+	  Elapsed time since beginning of connection.
+	  RFC4898 defines ElapsedSecs/Msecs as being updated via ktime_get
+	  at each protocol event (sending or receiving of a segment);
+	  as this can be a performance hit, leaving this config option off
+	  will update elapsed based on on the jiffies counter instead.
+	  Set to Y for strict conformance with the MIB.
+
+	  If unsure, say N.
+
+endif
diff --git a/net/ipv4/Makefile b/net/ipv4/Makefile
index 518c04e..7e2c69a 100644
--- a/net/ipv4/Makefile
+++ b/net/ipv4/Makefile
@@ -36,6 +36,7 @@ obj-$(CONFIG_INET_TUNNEL) += tunnel4.o
  obj-$(CONFIG_INET_XFRM_MODE_TRANSPORT) += xfrm4_mode_transport.o
  obj-$(CONFIG_INET_XFRM_MODE_TUNNEL) += xfrm4_mode_tunnel.o
  obj-$(CONFIG_IP_PNP) += ipconfig.o
+obj-$(CONFIG_TCP_ESTATS) += tcp_estats.o
  obj-$(CONFIG_NETFILTER)	+= netfilter.o netfilter/
  obj-$(CONFIG_INET_DIAG) += inet_diag.o
  obj-$(CONFIG_INET_TCP_DIAG) += tcp_diag.o
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index e0ee384..edc5a66 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -42,6 +42,11 @@ static int tcp_syn_retries_max = MAX_TCP_SYNCNT;
  static int ip_ping_group_range_min[] = { 0, 0 };
  static int ip_ping_group_range_max[] = { GID_T_MAX, GID_T_MAX };
  
+/* Extended statistics (RFC4898). */
+#ifdef CONFIG_TCP_ESTATS
+int sysctl_tcp_estats __read_mostly;
+#endif  /* CONFIG_TCP_ESTATS */
+
  /* Update system visible IP port range */
  static void set_local_port_range(struct net *net, int range[2])
  {
@@ -767,6 +772,15 @@ static struct ctl_table ipv4_table[] = {
  		.proc_handler	= proc_dointvec_minmax,
  		.extra1		= &one
  	},
+#ifdef CONFIG_TCP_ESTATS
+	{
+		.procname	= "tcp_estats",
+		.data		= &sysctl_tcp_estats,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec
+	},
+#endif /* CONFIG TCP ESTATS */
  	{ }
  };
  
diff --git a/net/ipv4/tcp_estats.c b/net/ipv4/tcp_estats.c
new file mode 100644
index 0000000..e817540
--- /dev/null
+++ b/net/ipv4/tcp_estats.c
@@ -0,0 +1,736 @@
+/*
+ * net/ipv4/tcp_estats.c
+ *
+ * Implementation of TCP ESTATS MIB (RFC 4898)
+ *
+ * Authors:
+ *   John Estabrook <jsestabrook@gmail.com>
+ *   Andrew K. Adams <akadams@psc.edu>
+ *   Kevin Hogan <kwabena@google.com>
+ *   Dominin Hamon <dma@stripysock.com>
+ *   John Heffner <johnwheffner@gmail.com>
+ *
+ * The Web10Gig project.  See http://www.web10gig.org
+ *
+ * Copyright © 2011, Pittsburgh Supercomputing Center (PSC).
+ * 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>
+#ifndef CONFIG_TCP_ESTATS_STRICT_ELAPSEDTIME
+#include <linux/jiffies.h>
+#endif
+#include <linux/types.h>
+#include <linux/socket.h>
+#include <linux/string.h>
+#include <net/tcp_estats.h>
+#include <net/tcp.h>
+#include <asm/atomic.h>
+#include <asm/byteorder.h>
+
+#define ESTATS_INF32	0xffffffff
+
+#define ESTATS_MAX_CID	5000000
+
+extern int sysctl_tcp_estats;
+
+struct idr tcp_estats_idr;
+EXPORT_SYMBOL(tcp_estats_idr);
+static int next_id = 1;
+DEFINE_SPINLOCK(tcp_estats_idr_lock);
+EXPORT_SYMBOL(tcp_estats_idr_lock);
+
+int tcp_estats_wq_enabled __read_mostly = 0;
+EXPORT_SYMBOL(tcp_estats_wq_enabled);
+struct workqueue_struct *tcp_estats_wq = NULL;
+EXPORT_SYMBOL(tcp_estats_wq);
+void (*create_notify_func)(struct work_struct *work);
+EXPORT_SYMBOL(create_notify_func);
+void (*establish_notify_func)(struct work_struct *work);
+EXPORT_SYMBOL(establish_notify_func);
+void (*destroy_notify_func)(struct work_struct *work);
+EXPORT_SYMBOL(destroy_notify_func);
+unsigned long persist_delay = 0;
+EXPORT_SYMBOL(persist_delay);
+
+struct static_key tcp_estats_enabled __read_mostly = STATIC_KEY_INIT_FALSE;
+EXPORT_SYMBOL(tcp_estats_enabled);
+
+/* if HAVE_JUMP_LABEL is defined, then static_key_slow_inc/dec uses a
+ *   mutex in its implementation, and hence can't be called if in_interrupt().
+ * if HAVE_JUMP_LABEL is NOT defined, then no mutex is used, hence no need
+ *   for deferring enable/disable */
+#ifdef HAVE_JUMP_LABEL
+static atomic_t tcp_estats_enabled_deferred;
+
+static void tcp_estats_handle_deferred_enable_disable(void)
+{
+	int count = atomic_xchg(&tcp_estats_enabled_deferred, 0);
+
+	while (count > 0) {
+		static_key_slow_inc(&tcp_estats_enabled);
+		--count;
+	}
+
+	while (count < 0) {
+		static_key_slow_dec(&tcp_estats_enabled);
+		++count;
+	}
+}
+#endif
+
+static inline void tcp_estats_enable(void)
+{
+#ifdef HAVE_JUMP_LABEL
+	if (in_interrupt()) {
+		atomic_inc(&tcp_estats_enabled_deferred);
+		return;
+	}
+	tcp_estats_handle_deferred_enable_disable();
+#endif
+	static_key_slow_inc(&tcp_estats_enabled);
+}
+
+static inline void tcp_estats_disable(void)
+{
+#ifdef HAVE_JUMP_LABEL
+	if (in_interrupt()) {
+		atomic_dec(&tcp_estats_enabled_deferred);
+		return;
+	}
+	tcp_estats_handle_deferred_enable_disable();
+#endif
+	static_key_slow_dec(&tcp_estats_enabled);
+}
+
+/* Calculates the required amount of memory for any enabled tables. */
+int tcp_estats_get_allocation_size(int sysctl)
+{
+	int size = sizeof(struct tcp_estats) +
+		sizeof(struct tcp_estats_connection_table);
+
+	if (sysctl & TCP_ESTATS_TABLEMASK_PERF)
+		size += sizeof(struct tcp_estats_perf_table);
+	if (sysctl & TCP_ESTATS_TABLEMASK_PATH)
+		size += sizeof(struct tcp_estats_path_table);
+	if (sysctl & TCP_ESTATS_TABLEMASK_STACK)
+		size += sizeof(struct tcp_estats_stack_table);
+	if (sysctl & TCP_ESTATS_TABLEMASK_APP)
+		size += sizeof(struct tcp_estats_app_table);
+	if (sysctl & TCP_ESTATS_TABLEMASK_EXTRAS)
+		size += sizeof(struct tcp_estats_extras_table);
+	return size;
+}
+
+/* Called whenever a TCP/IPv4 sock is created.
+ * net/ipv4/tcp_ipv4.c: tcp_v4_syn_recv_sock,
+ *			tcp_v4_init_sock
+ * Allocates a stats structure and initializes values.
+ */
+int tcp_estats_create(struct sock *sk, enum tcp_estats_addrtype addrtype,
+		      int active)
+{
+	struct tcp_estats *stats;
+	struct tcp_estats_tables *tables;
+	struct tcp_sock *tp = tcp_sk(sk);
+	void *estats_mem;
+	int sysctl;
+	int ret;
+
+	/* Read the sysctl once before calculating memory needs and initializing
+	 * tables to avoid raciness. */
+	sysctl = ACCESS_ONCE(sysctl_tcp_estats);
+	if (likely(sysctl == TCP_ESTATS_TABLEMASK_INACTIVE)) {
+		return 0;
+	}
+
+	estats_mem = kzalloc(tcp_estats_get_allocation_size(sysctl), gfp_any());
+	if (!estats_mem)
+		return -ENOMEM;
+
+	stats = estats_mem;
+	estats_mem += sizeof(struct tcp_estats);
+
+	tables = &stats->tables;
+
+	tables->connection_table = estats_mem;
+	estats_mem += sizeof(struct tcp_estats_connection_table);
+
+	if (sysctl & TCP_ESTATS_TABLEMASK_PERF) {
+		tables->perf_table = estats_mem;
+		estats_mem += sizeof(struct tcp_estats_perf_table);
+	}
+	if (sysctl & TCP_ESTATS_TABLEMASK_PATH) {
+		tables->path_table = estats_mem;
+		estats_mem += sizeof(struct tcp_estats_path_table);
+	}
+	if (sysctl & TCP_ESTATS_TABLEMASK_STACK) {
+		tables->stack_table = estats_mem;
+		estats_mem += sizeof(struct tcp_estats_stack_table);
+	}
+	if (sysctl & TCP_ESTATS_TABLEMASK_APP) {
+		tables->app_table = estats_mem;
+		estats_mem += sizeof(struct tcp_estats_app_table);
+	}
+	if (sysctl & TCP_ESTATS_TABLEMASK_EXTRAS) {
+		tables->extras_table = estats_mem;
+		estats_mem += sizeof(struct tcp_estats_extras_table);
+	}
+
+	stats->tcpe_cid = -1;
+	stats->queued = 0;
+
+	tables->connection_table->AddressType = addrtype;
+
+	sock_hold(sk);
+	stats->sk = sk;
+	atomic_set(&stats->users, 0);
+
+	stats->limstate = TCP_ESTATS_SNDLIM_STARTUP;
+	stats->limstate_ts = ktime_get();
+#ifdef CONFIG_TCP_ESTATS_STRICT_ELAPSEDTIME
+	stats->start_ts = stats->current_ts = stats->limstate_ts;
+#else
+	stats->start_ts = stats->current_ts = jiffies;
+#endif
+	do_gettimeofday(&stats->start_tv);
+
+	/* order is important -
+	 * must have stats hooked into tp and tcp_estats_enabled()
+	 * in order to have the TCP_ESTATS_VAR_<> macros work */
+	tp->tcp_stats = stats;
+	tcp_estats_enable();
+
+	TCP_ESTATS_VAR_SET(tp, stack_table, ActiveOpen, active);
+
+	TCP_ESTATS_VAR_SET(tp, app_table, SndMax, tp->snd_nxt);
+	TCP_ESTATS_VAR_SET(tp, stack_table, SndInitial, tp->snd_nxt);
+
+	TCP_ESTATS_VAR_SET(tp, path_table, MinRTT, ESTATS_INF32);
+	TCP_ESTATS_VAR_SET(tp, path_table, MinRTO, ESTATS_INF32);
+	TCP_ESTATS_VAR_SET(tp, stack_table, MinMSS, ESTATS_INF32);
+	TCP_ESTATS_VAR_SET(tp, stack_table, MinSsthresh, ESTATS_INF32);
+
+	tcp_estats_use(stats);
+
+	if (tcp_estats_wq_enabled) {
+		tcp_estats_use(stats);
+		stats->queued = 1;
+		stats->tcpe_cid = 0;
+		INIT_WORK(&stats->create_notify, create_notify_func);
+		ret = queue_work(tcp_estats_wq, &stats->create_notify);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(tcp_estats_create);
+
+void tcp_estats_destroy(struct sock *sk)
+{
+	struct tcp_estats *stats = tcp_sk(sk)->tcp_stats;
+
+	if (stats == NULL)
+		return;
+
+	/* Attribute final sndlim time. */
+	tcp_estats_update_sndlim(tcp_sk(stats->sk), stats->limstate);
+
+	if (tcp_estats_wq_enabled && stats->queued) {
+		INIT_DELAYED_WORK(&stats->destroy_notify,
+			destroy_notify_func);
+		queue_delayed_work(tcp_estats_wq, &stats->destroy_notify,
+			persist_delay);
+	}
+	tcp_estats_unuse(stats);
+}
+
+/* Do not call directly.  Called from tcp_estats_unuse() through call_rcu. */
+void tcp_estats_free(struct rcu_head *rcu)
+{
+	struct tcp_estats *stats = container_of(rcu, struct tcp_estats, rcu);
+	tcp_estats_disable();
+	kfree(stats);
+}
+EXPORT_SYMBOL(tcp_estats_free);
+
+/* Called when a connection enters the ESTABLISHED state, and has all its
+ * state initialized.
+ * net/ipv4/tcp_input.c: tcp_rcv_state_process,
+ *			 tcp_rcv_synsent_state_process
+ * Here we link the statistics structure in so it is visible in the /proc
+ * fs, and do some final init.
+ */
+void tcp_estats_establish(struct sock *sk)
+{
+	struct inet_sock *inet = inet_sk(sk);
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct tcp_estats *stats = tp->tcp_stats;
+	struct tcp_estats_connection_table *conn_table;
+
+	if (stats == NULL)
+		return;
+
+	conn_table = stats->tables.connection_table;
+
+	/* Let's set these here, since they can't change once the
+	 * connection is established.
+	 */
+	conn_table->LocalPort = inet->inet_num;
+	conn_table->RemPort = ntohs(inet->inet_dport);
+
+	if (conn_table->AddressType == TCP_ESTATS_ADDRTYPE_IPV4) {
+		memcpy(&conn_table->LocalAddress.addr, &inet->inet_rcv_saddr,
+			sizeof(struct in_addr));
+		memcpy(&conn_table->RemAddress.addr, &inet->inet_daddr,
+			sizeof(struct in_addr));
+	}
+#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
+	else if (conn_table->AddressType == TCP_ESTATS_ADDRTYPE_IPV6) {
+		memcpy(&conn_table->LocalAddress.addr6, &(sk)->sk_v6_rcv_saddr,
+		       sizeof(struct in6_addr));
+		/* ipv6 daddr now uses a different struct than saddr */
+		memcpy(&conn_table->RemAddress.addr6, &(sk)->sk_v6_daddr,
+		       sizeof(struct in6_addr));
+	}
+#endif
+	else {
+		pr_err("TCP ESTATS: AddressType not valid.\n");
+	}
+
+	tcp_estats_update_finish_segrecv(tp);
+	tcp_estats_update_rwin_rcvd(tp);
+	tcp_estats_update_rwin_sent(tp);
+
+	TCP_ESTATS_VAR_SET(tp, stack_table, RecInitial, tp->rcv_nxt);
+
+	tcp_estats_update_sndlim(tp, TCP_ESTATS_SNDLIM_SENDER);
+
+	if (tcp_estats_wq_enabled && stats->queued) {
+		INIT_WORK(&stats->establish_notify, establish_notify_func);
+		queue_work(tcp_estats_wq, &stats->establish_notify);
+	}
+}
+
+/*
+ * Statistics update functions
+ */
+
+void tcp_estats_update_snd_nxt(struct tcp_sock *tp)
+{
+	struct tcp_estats *stats = tp->tcp_stats;
+
+	if (stats->tables.app_table) {
+		if (after(tp->snd_nxt, stats->tables.app_table->SndMax))
+			stats->tables.app_table->SndMax = tp->snd_nxt;
+	}
+}
+
+void tcp_estats_update_acked(struct tcp_sock *tp, u32 ack)
+{
+	struct tcp_estats *stats = tp->tcp_stats;
+
+	if (stats->tables.app_table)
+		stats->tables.app_table->ThruOctetsAcked += ack - tp->snd_una;
+}
+
+void tcp_estats_update_rtt(struct sock *sk, unsigned long rtt_sample)
+{
+	struct tcp_estats *stats = tcp_sk(sk)->tcp_stats;
+	struct tcp_estats_path_table *path_table = stats->tables.path_table;
+	unsigned long rtt_sample_msec = rtt_sample/1000;
+	u32 rto;
+
+	if (path_table == NULL)
+		return;
+
+	path_table->SampleRTT = rtt_sample_msec;
+
+	if (rtt_sample_msec > path_table->MaxRTT)
+		path_table->MaxRTT = rtt_sample_msec;
+	if (rtt_sample_msec < path_table->MinRTT)
+		path_table->MinRTT = rtt_sample_msec;
+
+	path_table->CountRTT++;
+	path_table->SumRTT += rtt_sample_msec;
+
+	rto = jiffies_to_msecs(inet_csk(sk)->icsk_rto);
+	if (rto > path_table->MaxRTO)
+		path_table->MaxRTO = rto;
+	if (rto < path_table->MinRTO)
+		path_table->MinRTO = rto;
+}
+
+void tcp_estats_update_timeout(struct sock *sk)
+{
+	if (inet_csk(sk)->icsk_backoff)
+		TCP_ESTATS_VAR_INC(tcp_sk(sk), stack_table, SubsequentTimeouts);
+	else
+		TCP_ESTATS_VAR_INC(tcp_sk(sk), perf_table, Timeouts);
+
+	if (inet_csk(sk)->icsk_ca_state == TCP_CA_Open)
+		TCP_ESTATS_VAR_INC(tcp_sk(sk), stack_table, AbruptTimeouts);
+}
+
+void tcp_estats_update_mss(struct tcp_sock *tp)
+{
+	struct tcp_estats *stats = tp->tcp_stats;
+	struct tcp_estats_stack_table *stack_table = stats->tables.stack_table;
+	int mss = tp->mss_cache;
+
+	if (stack_table == NULL)
+		return;
+
+	if (mss > stack_table->MaxMSS)
+		stack_table->MaxMSS = mss;
+	if (mss < stack_table->MinMSS)
+		stack_table->MinMSS = mss;
+}
+
+void tcp_estats_update_finish_segrecv(struct tcp_sock *tp)
+{
+	struct tcp_estats *stats = tp->tcp_stats;
+	struct tcp_estats_tables *tables = &stats->tables;
+	struct tcp_estats_perf_table *perf_table = tables->perf_table;
+	struct tcp_estats_stack_table *stack_table = tables->stack_table;
+	u32 mss = tp->mss_cache;
+	u32 cwnd;
+	u32 ssthresh;
+	u32 pipe_size;
+
+#ifdef CONFIG_TCP_ESTATS_STRICT_ELAPSEDTIME
+	stats->current_ts = ktime_get();
+#else
+	stats->current_ts = jiffies;
+#endif
+
+	if (stack_table != NULL) {
+		cwnd = tp->snd_cwnd * mss;
+		if (tp->snd_cwnd <= tp->snd_ssthresh) {
+			if (cwnd > stack_table->MaxSsCwnd)
+				stack_table->MaxSsCwnd = cwnd;
+		} else if (cwnd > stack_table->MaxCaCwnd) {
+			stack_table->MaxCaCwnd = cwnd;
+		}
+	}
+
+	if (perf_table != NULL) {
+		pipe_size = tcp_packets_in_flight(tp) * mss;
+		if (pipe_size > perf_table->MaxPipeSize)
+			perf_table->MaxPipeSize = pipe_size;
+	}
+
+	/* Discard initiail ssthresh set at infinity. */
+	if (tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH) {
+		return;
+	}
+
+	if (stack_table != NULL) {
+		ssthresh = tp->snd_ssthresh * tp->mss_cache;
+		if (ssthresh > stack_table->MaxSsthresh)
+			stack_table->MaxSsthresh = ssthresh;
+		if (ssthresh < stack_table->MinSsthresh)
+			stack_table->MinSsthresh = ssthresh;
+	}
+}
+EXPORT_SYMBOL(tcp_estats_update_finish_segrecv);
+
+void tcp_estats_update_rwin_rcvd(struct tcp_sock *tp)
+{
+	struct tcp_estats *stats = tp->tcp_stats;
+	struct tcp_estats_perf_table *perf_table = stats->tables.perf_table;
+	u32 win = tp->snd_wnd;
+
+	if (perf_table == NULL)
+		return;
+
+	if (win > perf_table->MaxRwinRcvd)
+		perf_table->MaxRwinRcvd = win;
+	if (win == 0)
+		perf_table->ZeroRwinRcvd++;
+}
+
+void tcp_estats_update_rwin_sent(struct tcp_sock *tp)
+{
+	struct tcp_estats *stats = tp->tcp_stats;
+	struct tcp_estats_perf_table *perf_table = stats->tables.perf_table;
+	u32 win = tp->rcv_wnd;
+
+	if (perf_table == NULL)
+		return;
+
+	if (win > perf_table->MaxRwinSent)
+		perf_table->MaxRwinSent = win;
+	if (win == 0)
+		perf_table->ZeroRwinSent++;
+}
+
+void tcp_estats_update_sndlim(struct tcp_sock *tp,
+			      enum tcp_estats_sndlim_states state)
+{
+	struct tcp_estats *stats = tp->tcp_stats;
+	struct tcp_estats_perf_table *perf_table = stats->tables.perf_table;
+	ktime_t now;
+
+	if (state <= TCP_ESTATS_SNDLIM_NONE ||
+	    state >= TCP_ESTATS_SNDLIM_NSTATES) {
+		pr_err("tcp_estats_update_sndlim: BUG: state out of range %d\n",
+		       state);
+		return;
+	}
+
+	if (perf_table == NULL)
+		return;
+
+	now = ktime_get();
+	perf_table->snd_lim_time[stats->limstate]
+	    += ktime_to_us(ktime_sub(now, stats->limstate_ts));
+	stats->limstate_ts = now;
+	if (stats->limstate != state) {
+		stats->limstate = state;
+		perf_table->snd_lim_trans[state]++;
+	}
+}
+
+void tcp_estats_update_congestion(struct tcp_sock *tp)
+{
+	struct tcp_estats *stats = tp->tcp_stats;
+	struct tcp_estats_path_table *path_table = stats->tables.path_table;
+
+	TCP_ESTATS_VAR_INC(tp, perf_table, CongSignals);
+
+	if (path_table != NULL) {
+		path_table->PreCongSumCwnd += tp->snd_cwnd * tp->mss_cache;
+		path_table->PreCongSumRTT += path_table->SampleRTT;
+	}
+}
+
+void tcp_estats_update_post_congestion(struct tcp_sock *tp)
+{
+	struct tcp_estats *stats = tp->tcp_stats;
+	struct tcp_estats_path_table *path_table = stats->tables.path_table;
+
+	if (path_table != NULL) {
+		path_table->PostCongCountRTT++;
+		path_table->PostCongSumRTT += path_table->SampleRTT;
+	}
+}
+
+void tcp_estats_update_segsend(struct sock *sk, int pcount,
+			       u32 seq, u32 end_seq, int flags)
+{
+	struct tcp_estats *stats = tcp_sk(sk)->tcp_stats;
+	struct tcp_estats_perf_table *perf_table = stats->tables.perf_table;
+	struct tcp_estats_app_table *app_table = stats->tables.app_table;
+
+	int data_len = end_seq - seq;
+
+#ifdef CONFIG_TCP_ESTATS_STRICT_ELAPSEDTIME
+	stats->current_ts = ktime_get();
+#else
+	stats->current_ts = jiffies;
+#endif
+
+	if (perf_table == NULL)
+		return;
+
+	/* We know we're sending a segment. */
+	perf_table->SegsOut += pcount;
+
+	/* A pure ACK contains no data; everything else is data. */
+	if (data_len > 0) {
+		perf_table->DataSegsOut += pcount;
+		perf_table->DataOctetsOut += data_len;
+	}
+
+	/* Check for retransmission. */
+	if (flags & TCPHDR_SYN) {
+		if (inet_csk(sk)->icsk_retransmits)
+			perf_table->SegsRetrans++;
+	} else if (app_table != NULL &&
+		   before(seq, app_table->SndMax)) {
+		perf_table->SegsRetrans += pcount;
+		perf_table->OctetsRetrans += data_len;
+	}
+}
+
+void tcp_estats_update_segrecv(struct tcp_sock *tp, struct sk_buff *skb)
+{
+	struct tcp_estats_tables *tables = &tp->tcp_stats->tables;
+	struct tcp_estats_path_table *path_table = tables->path_table;
+	struct tcp_estats_perf_table *perf_table = tables->perf_table;
+	struct tcp_estats_stack_table *stack_table = tables->stack_table;
+	struct tcphdr *th = tcp_hdr(skb);
+	struct iphdr *iph = ip_hdr(skb);
+
+	if (perf_table != NULL)
+		perf_table->SegsIn++;
+
+	if (skb->len == th->doff * 4) {
+		if (stack_table != NULL &&
+		    TCP_SKB_CB(skb)->ack_seq == tp->snd_una)
+			stack_table->DupAcksIn++;
+	} else {
+		if (perf_table != NULL) {
+			perf_table->DataSegsIn++;
+			perf_table->DataOctetsIn += skb->len - th->doff * 4;
+		}
+	}
+
+	if (path_table != NULL) {
+		path_table->IpTtl = iph->ttl;
+		path_table->IpTosIn = iph->tos;
+	}
+}
+EXPORT_SYMBOL(tcp_estats_update_segrecv);
+
+void tcp_estats_update_rcvd(struct tcp_sock *tp, u32 seq)
+{
+        /* After much debate, it was decided that "seq - rcv_nxt" is
+           indeed what we want, as opposed to what Krishnan suggested
+           to better match the RFC: "seq - tp->rcv_wup" */
+	TCP_ESTATS_VAR_ADD(tp, app_table, ThruOctetsReceived,
+			   seq - tp->rcv_nxt);
+}
+
+void tcp_estats_update_writeq(struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct tcp_estats_app_table *app_table =
+			tp->tcp_stats->tables.app_table;
+	int len;
+
+	if (app_table == NULL)
+		return;
+
+	len = tp->write_seq - app_table->SndMax;
+
+	if (len > app_table->MaxAppWQueue)
+		app_table->MaxAppWQueue = len;
+}
+
+static inline u32 ofo_qlen(struct tcp_sock *tp)
+{
+	if (!skb_peek(&tp->out_of_order_queue))
+		return 0;
+	else
+		return TCP_SKB_CB(tp->out_of_order_queue.prev)->end_seq -
+		    TCP_SKB_CB(tp->out_of_order_queue.next)->seq;
+}
+
+void tcp_estats_update_recvq(struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct tcp_estats_tables *tables = &tp->tcp_stats->tables;
+	struct tcp_estats_app_table *app_table = tables->app_table;
+	struct tcp_estats_stack_table *stack_table = tables->stack_table;
+
+	if (app_table != NULL) {
+		u32 len = tp->rcv_nxt - tp->copied_seq;
+		if (app_table->MaxAppRQueue < len)
+			app_table->MaxAppRQueue = len;
+	}
+
+	if (stack_table != NULL) {
+		u32 len = ofo_qlen(tp);
+		if (stack_table->MaxReasmQueue < len)
+			stack_table->MaxReasmQueue = len;
+	}
+}
+
+/*
+ * Manage connection ID table
+ */
+
+static int get_new_cid(struct tcp_estats *stats)
+{
+         int id_cid;
+
+again:
+         spin_lock_bh(&tcp_estats_idr_lock);
+         id_cid = idr_alloc(&tcp_estats_idr, stats, next_id, 0, GFP_KERNEL);
+         if (unlikely(id_cid == -ENOSPC)) {
+                 spin_unlock_bh(&tcp_estats_idr_lock);
+                 goto again;
+         }
+         if (unlikely(id_cid == -ENOMEM)) {
+                 spin_unlock_bh(&tcp_estats_idr_lock);
+                 return -ENOMEM;
+         }
+         next_id = (id_cid + 1) % ESTATS_MAX_CID;
+         stats->tcpe_cid = id_cid;
+         spin_unlock_bh(&tcp_estats_idr_lock);
+         return 0;
+}
+
+static void create_func(struct work_struct *work)
+{
+	/* stub for netlink notification of new connections */
+	;
+}
+
+static void establish_func(struct work_struct *work)
+{
+	struct tcp_estats *stats = container_of(work, struct tcp_estats,
+						establish_notify);
+	int err = 0;
+
+	if ((stats->tcpe_cid) > 0) {
+		pr_err("TCP estats container established multiple times.\n");
+		return;
+	}
+
+	if ((stats->tcpe_cid) == 0) {
+		err = get_new_cid(stats);
+		if (err)
+			pr_devel("get_new_cid error %d\n", err);
+	}
+}
+
+static void destroy_func(struct work_struct *work)
+{
+	struct tcp_estats *stats = container_of(work, struct tcp_estats,
+						destroy_notify.work);
+
+	int id_cid = stats->tcpe_cid;
+
+	if (id_cid == 0)
+		pr_devel("TCP estats destroyed before being established.\n");
+
+	if (id_cid >= 0) {
+		if (id_cid) {
+			spin_lock_bh(&tcp_estats_idr_lock);
+			idr_remove(&tcp_estats_idr, id_cid);
+			spin_unlock_bh(&tcp_estats_idr_lock);
+		}
+		stats->tcpe_cid = -1;
+
+		tcp_estats_unuse(stats);
+	}
+}
+
+void __init tcp_estats_init()
+{
+	idr_init(&tcp_estats_idr);
+
+	create_notify_func = &create_func;
+	establish_notify_func = &establish_func;
+	destroy_notify_func = &destroy_func;
+
+	persist_delay = TCP_ESTATS_PERSIST_DELAY_SECS * HZ;
+
+	tcp_estats_wq = alloc_workqueue("tcp_estats", WQ_MEM_RECLAIM, 256);
+	if (tcp_estats_wq == NULL) {
+		pr_err("tcp_estats_init(): alloc_workqueue failed\n");
+		goto cleanup_fail;
+	}
+
+	tcp_estats_wq_enabled = 1;
+	return;
+
+cleanup_fail:
+	pr_err("TCP ESTATS: initialization failed.\n");
+}
