Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 4959 insertions, 0 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
new file mode 100644
index 0000000..2504927
--- /dev/null
+++ b/net/ipv4/tcp_input.c
@@ -0,0 +1,4959 @@
+/*
+ * INET		An implementation of the TCP/IP protocol suite for the LINUX
+ *		operating system.  INET is implemented using the  BSD Socket
+ *		interface as the means of communication with the user level.
+ *
+ *		Implementation of the Transmission Control Protocol(TCP).
+ *
+ * Version:	$Id: tcp_input.c,v 1.243 2002/02/01 22:01:04 davem Exp $
+ *
+ * Authors:	Ross Biro, <bir7@leland.Stanford.Edu>
+ *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
+ *		Mark Evans, <evansmp@uhura.aston.ac.uk>
+ *		Corey Minyard <wf-rch!minyard@relay.EU.net>
+ *		Florian La Roche, <flla@stud.uni-sb.de>
+ *		Charles Hedrick, <hedrick@klinzhai.rutgers.edu>
+ *		Linus Torvalds, <torvalds@cs.helsinki.fi>
+ *		Alan Cox, <gw4pts@gw4pts.ampr.org>
+ *		Matthew Dillon, <dillon@apollo.west.oic.com>
+ *		Arnt Gulbrandsen, <agulbra@nvg.unit.no>
+ *		Jorge Cwik, <jorge@laser.satlink.net>
+ */
+
+/*
+ * Changes:
+ *		Pedro Roque	:	Fast Retransmit/Recovery.
+ *					Two receive queues.
+ *					Retransmit queue handled by TCP.
+ *					Better retransmit timer handling.
+ *					New congestion avoidance.
+ *					Header prediction.
+ *					Variable renaming.
+ *
+ *		Eric		:	Fast Retransmit.
+ *		Randy Scott	:	MSS option defines.
+ *		Eric Schenk	:	Fixes to slow start algorithm.
+ *		Eric Schenk	:	Yet another double ACK bug.
+ *		Eric Schenk	:	Delayed ACK bug fixes.
+ *		Eric Schenk	:	Floyd style fast retrans war avoidance.
+ *		David S. Miller	:	Don't allow zero congestion window.
+ *		Eric Schenk	:	Fix retransmitter so that it sends
+ *					next packet on ack of previous packet.
+ *		Andi Kleen	:	Moved open_request checking here
+ *					and process RSTs for open_requests.
+ *		Andi Kleen	:	Better prune_queue, and other fixes.
+ *		Andrey Savochkin:	Fix RTT measurements in the presnce of
+ *					timestamps.
+ *		Andrey Savochkin:	Check sequence numbers correctly when
+ *					removing SACKs due to in sequence incoming
+ *					data segments.
+ *		Andi Kleen:		Make sure we never ack data there is not
+ *					enough room for. Also make this condition
+ *					a fatal error if it might still happen.
+ *		Andi Kleen:		Add tcp_measure_rcv_mss to make 
+ *					connections with MSS<min(MTU,ann. MSS)
+ *					work without delayed acks. 
+ *		Andi Kleen:		Process packets with PSH set in the
+ *					fast path.
+ *		J Hadi Salim:		ECN support
+ *	 	Andrei Gurtov,
+ *		Pasi Sarolahti,
+ *		Panu Kuhlberg:		Experimental audit of TCP (re)transmission
+ *					engine. Lots of bugs are found.
+ *		Pasi Sarolahti:		F-RTO for dealing with spurious RTOs
+ *		Angelo Dell'Aera:	TCP Westwood+ support
+ */
+
+#include <linux/config.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/sysctl.h>
+#include <net/tcp.h>
+#include <net/inet_common.h>
+#include <linux/ipsec.h>
+#include <asm/unaligned.h>
+
+int sysctl_tcp_timestamps = 1;
+int sysctl_tcp_window_scaling = 1;
+int sysctl_tcp_sack = 1;
+int sysctl_tcp_fack = 1;
+int sysctl_tcp_reordering = TCP_FASTRETRANS_THRESH;
+int sysctl_tcp_ecn;
+int sysctl_tcp_dsack = 1;
+int sysctl_tcp_app_win = 31;
+int sysctl_tcp_adv_win_scale = 2;
+
+int sysctl_tcp_stdurg;
+int sysctl_tcp_rfc1337;
+int sysctl_tcp_max_orphans = NR_FILE;
+int sysctl_tcp_frto;
+int sysctl_tcp_nometrics_save;
+int sysctl_tcp_westwood;
+int sysctl_tcp_vegas_cong_avoid;
+
+int sysctl_tcp_moderate_rcvbuf = 1;
+
+/* Default values of the Vegas variables, in fixed-point representation
+ * with V_PARAM_SHIFT bits to the right of the binary point.
+ */
+#define V_PARAM_SHIFT 1
+int sysctl_tcp_vegas_alpha = 1<<V_PARAM_SHIFT;
+int sysctl_tcp_vegas_beta  = 3<<V_PARAM_SHIFT;
+int sysctl_tcp_vegas_gamma = 1<<V_PARAM_SHIFT;
+int sysctl_tcp_bic = 1;
+int sysctl_tcp_bic_fast_convergence = 1;
+int sysctl_tcp_bic_low_window = 14;
+int sysctl_tcp_bic_beta = 819;		/* = 819/1024 (BICTCP_BETA_SCALE) */
+
+#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_DATA_LOST		0x80 /* SACK detected data lossage.		*/
+#define FLAG_SLOWPATH		0x100 /* Do not skip RFC checks for window update.*/
+
+#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 IsReno(tp) ((tp)->rx_opt.sack_ok == 0)
+#define IsFack(tp) ((tp)->rx_opt.sack_ok & 2)
+#define IsDSack(tp) ((tp)->rx_opt.sack_ok & 4)
+
+#define TCP_REMNANT (TCP_FLAG_FIN|TCP_FLAG_URG|TCP_FLAG_SYN|TCP_FLAG_PSH)
+
+/* Adapt the MSS value used to make delayed ack decision to the 
+ * real world.
+ */ 
+static inline void tcp_measure_rcv_mss(struct tcp_sock *tp,
+				       struct sk_buff *skb)
+{
+	unsigned int len, lss;
+
+	lss = tp->ack.last_seg_size; 
+	tp->ack.last_seg_size = 0; 
+
+	/* skb->len may jitter because of SACKs, even if peer
+	 * sends good full-sized frames.
+	 */
+	len = skb->len;
+	if (len >= tp->ack.rcv_mss) {
+		tp->ack.rcv_mss = len;
+	} else {
+		/* Otherwise, we make more careful check taking into account,
+		 * that SACKs block is variable.
+		 *
+		 * "len" is invariant segment length, including TCP header.
+		 */
+		len += skb->data - skb->h.raw;
+		if (len >= TCP_MIN_RCVMSS + sizeof(struct tcphdr) ||
+		    /* If PSH is not set, packet should be
+		     * full sized, provided peer TCP is not badly broken.
+		     * This observation (if it is correct 8)) allows
+		     * to handle super-low mtu links fairly.
+		     */
+		    (len >= TCP_MIN_MSS + sizeof(struct tcphdr) &&
+		     !(tcp_flag_word(skb->h.th)&TCP_REMNANT))) {
+			/* Subtract also invariant (if peer is RFC compliant),
+			 * tcp header plus fixed timestamp option length.
+			 * Resulting "len" is MSS free of SACK jitter.
+			 */
+			len -= tp->tcp_header_len;
+			tp->ack.last_seg_size = len;
+			if (len == lss) {
+				tp->ack.rcv_mss = len;
+				return;
+			}
+		}
+		tp->ack.pending |= TCP_ACK_PUSHED;
+	}
+}
+
+static void tcp_incr_quickack(struct tcp_sock *tp)
+{
+	unsigned quickacks = tp->rcv_wnd/(2*tp->ack.rcv_mss);
+
+	if (quickacks==0)
+		quickacks=2;
+	if (quickacks > tp->ack.quick)
+		tp->ack.quick = min(quickacks, TCP_MAX_QUICKACKS);
+}
+
+void tcp_enter_quickack_mode(struct tcp_sock *tp)
+{
+	tcp_incr_quickack(tp);
+	tp->ack.pingpong = 0;
+	tp->ack.ato = TCP_ATO_MIN;
+}
+
+/* Send ACKs quickly, if "quick" count is not exhausted
+ * and the session is not interactive.
+ */
+
+static __inline__ int tcp_in_quickack_mode(struct tcp_sock *tp)
+{
+	return (tp->ack.quick && !tp->ack.pingpong);
+}
+
+/* Buffer size and advertised window tuning.
+ *
+ * 1. Tuning sk->sk_sndbuf, when connection enters established state.
+ */
+
+static void tcp_fixup_sndbuf(struct sock *sk)
+{
+	int sndmem = tcp_sk(sk)->rx_opt.mss_clamp + MAX_TCP_HEADER + 16 +
+		     sizeof(struct sk_buff);
+
+	if (sk->sk_sndbuf < 3 * sndmem)
+		sk->sk_sndbuf = min(3 * sndmem, sysctl_tcp_wmem[2]);
+}
+
+/* 2. Tuning advertised window (window_clamp, rcv_ssthresh)
+ *
+ * All tcp_full_space() is split to two parts: "network" buffer, allocated
+ * forward and advertised in receiver window (tp->rcv_wnd) and
+ * "application buffer", required to isolate scheduling/application
+ * latencies from network.
+ * window_clamp is maximal advertised window. It can be less than
+ * tcp_full_space(), in this case tcp_full_space() - window_clamp
+ * is reserved for "application" buffer. The less window_clamp is
+ * the smoother our behaviour from viewpoint of network, but the lower
+ * throughput and the higher sensitivity of the connection to losses. 8)
+ *
+ * rcv_ssthresh is more strict window_clamp used at "slow start"
+ * phase to predict further behaviour of this connection.
+ * It is used for two goals:
+ * - to enforce header prediction at sender, even when application
+ *   requires some significant "application buffer". It is check #1.
+ * - to prevent pruning of receive queue because of misprediction
+ *   of receiver window. Check #2.
+ *
+ * The scheme does not work when sender sends good segments opening
+ * window and then starts to feed us spagetti. But it should work
+ * in common situations. Otherwise, we have to rely on queue collapsing.
+ */
+
+/* Slow part of check#2. */
+static int __tcp_grow_window(struct sock *sk, struct tcp_sock *tp,
+			     struct sk_buff *skb)
+{
+	/* Optimize this! */
+	int truesize = tcp_win_from_space(skb->truesize)/2;
+	int window = tcp_full_space(sk)/2;
+
+	while (tp->rcv_ssthresh <= window) {
+		if (truesize <= skb->len)
+			return 2*tp->ack.rcv_mss;
+
+		truesize >>= 1;
+		window >>= 1;
+	}
+	return 0;
+}
+
+static inline void tcp_grow_window(struct sock *sk, struct tcp_sock *tp,
+				   struct sk_buff *skb)
+{
+	/* Check #1 */
+	if (tp->rcv_ssthresh < tp->window_clamp &&
+	    (int)tp->rcv_ssthresh < tcp_space(sk) &&
+	    !tcp_memory_pressure) {
+		int incr;
+
+		/* Check #2. Increase window, if skb with such overhead
+		 * will fit to rcvbuf in future.
+		 */
+		if (tcp_win_from_space(skb->truesize) <= skb->len)
+			incr = 2*tp->advmss;
+		else
+			incr = __tcp_grow_window(sk, tp, skb);
+
+		if (incr) {
+			tp->rcv_ssthresh = min(tp->rcv_ssthresh + incr, tp->window_clamp);
+			tp->ack.quick |= 1;
+		}
+	}
+}
+
+/* 3. Tuning rcvbuf, when connection enters established state. */
+
+static void tcp_fixup_rcvbuf(struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	int rcvmem = tp->advmss + MAX_TCP_HEADER + 16 + sizeof(struct sk_buff);
+
+	/* Try to select rcvbuf so that 4 mss-sized segments
+	 * will fit to window and correspoding skbs will fit to our rcvbuf.
+	 * (was 3; 4 is minimum to allow fast retransmit to work.)
+	 */
+	while (tcp_win_from_space(rcvmem) < tp->advmss)
+		rcvmem += 128;
+	if (sk->sk_rcvbuf < 4 * rcvmem)
+		sk->sk_rcvbuf = min(4 * rcvmem, sysctl_tcp_rmem[2]);
+}
+
+/* 4. Try to fixup all. It is made iimediately after connection enters
+ *    established state.
+ */
+static void tcp_init_buffer_space(struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	int maxwin;
+
+	if (!(sk->sk_userlocks & SOCK_RCVBUF_LOCK))
+		tcp_fixup_rcvbuf(sk);
+	if (!(sk->sk_userlocks & SOCK_SNDBUF_LOCK))
+		tcp_fixup_sndbuf(sk);
+
+	tp->rcvq_space.space = tp->rcv_wnd;
+
+	maxwin = tcp_full_space(sk);
+
+	if (tp->window_clamp >= maxwin) {
+		tp->window_clamp = maxwin;
+
+		if (sysctl_tcp_app_win && maxwin > 4 * tp->advmss)
+			tp->window_clamp = max(maxwin -
+					       (maxwin >> sysctl_tcp_app_win),
+					       4 * tp->advmss);
+	}
+
+	/* Force reservation of one segment. */
+	if (sysctl_tcp_app_win &&
+	    tp->window_clamp > 2 * tp->advmss &&
+	    tp->window_clamp + tp->advmss > maxwin)
+		tp->window_clamp = max(2 * tp->advmss, maxwin - tp->advmss);
+
+	tp->rcv_ssthresh = min(tp->rcv_ssthresh, tp->window_clamp);
+	tp->snd_cwnd_stamp = tcp_time_stamp;
+}
+
+static void init_bictcp(struct tcp_sock *tp)
+{
+	tp->bictcp.cnt = 0;
+
+	tp->bictcp.last_max_cwnd = 0;
+	tp->bictcp.last_cwnd = 0;
+	tp->bictcp.last_stamp = 0;
+}
+
+/* 5. Recalculate window clamp after socket hit its memory bounds. */
+static void tcp_clamp_window(struct sock *sk, struct tcp_sock *tp)
+{
+	struct sk_buff *skb;
+	unsigned int app_win = tp->rcv_nxt - tp->copied_seq;
+	int ofo_win = 0;
+
+	tp->ack.quick = 0;
+
+	skb_queue_walk(&tp->out_of_order_queue, skb) {
+		ofo_win += skb->len;
+	}
+
+	/* If overcommit is due to out of order segments,
+	 * do not clamp window. Try to expand rcvbuf instead.
+	 */
+	if (ofo_win) {
+		if (sk->sk_rcvbuf < sysctl_tcp_rmem[2] &&
+		    !(sk->sk_userlocks & SOCK_RCVBUF_LOCK) &&
+		    !tcp_memory_pressure &&
+		    atomic_read(&tcp_memory_allocated) < sysctl_tcp_mem[0])
+			sk->sk_rcvbuf = min(atomic_read(&sk->sk_rmem_alloc),
+					    sysctl_tcp_rmem[2]);
+	}
+	if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf) {
+		app_win += ofo_win;
+		if (atomic_read(&sk->sk_rmem_alloc) >= 2 * sk->sk_rcvbuf)
+			app_win >>= 1;
+		if (app_win > tp->ack.rcv_mss)
+			app_win -= tp->ack.rcv_mss;
+		app_win = max(app_win, 2U*tp->advmss);
+
+		if (!ofo_win)
+			tp->window_clamp = min(tp->window_clamp, app_win);
+		tp->rcv_ssthresh = min(tp->window_clamp, 2U*tp->advmss);
+	}
+}
+
+/* Receiver "autotuning" code.
+ *
+ * The algorithm for RTT estimation w/o timestamps is based on
+ * Dynamic Right-Sizing (DRS) by Wu Feng and Mike Fisk of LANL.
+ * <http://www.lanl.gov/radiant/website/pubs/drs/lacsi2001.ps>
+ *
+ * More detail on this code can be found at
+ * <http://www.psc.edu/~jheffner/senior_thesis.ps>,
+ * though this reference is out of date.  A new paper
+ * is pending.
+ */
+static void tcp_rcv_rtt_update(struct tcp_sock *tp, u32 sample, int win_dep)
+{
+	u32 new_sample = tp->rcv_rtt_est.rtt;
+	long m = sample;
+
+	if (m == 0)
+		m = 1;
+
+	if (new_sample != 0) {
+		/* If we sample in larger samples in the non-timestamp
+		 * case, we could grossly overestimate the RTT especially
+		 * with chatty applications or bulk transfer apps which
+		 * are stalled on filesystem I/O.
+		 *
+		 * Also, since we are only going for a minimum in the
+		 * non-timestamp case, we do not smoothe things out
+		 * else with timestamps disabled convergance takes too
+		 * long.
+		 */
+		if (!win_dep) {
+			m -= (new_sample >> 3);
+			new_sample += m;
+		} else if (m < new_sample)
+			new_sample = m << 3;
+	} else {
+		/* No previous mesaure. */
+		new_sample = m << 3;
+	}
+
+	if (tp->rcv_rtt_est.rtt != new_sample)
+		tp->rcv_rtt_est.rtt = new_sample;
+}
+
+static inline void tcp_rcv_rtt_measure(struct tcp_sock *tp)
+{
+	if (tp->rcv_rtt_est.time == 0)
+		goto new_measure;
+	if (before(tp->rcv_nxt, tp->rcv_rtt_est.seq))
+		return;
+	tcp_rcv_rtt_update(tp,
+			   jiffies - tp->rcv_rtt_est.time,
+			   1);
+
+new_measure:
+	tp->rcv_rtt_est.seq = tp->rcv_nxt + tp->rcv_wnd;
+	tp->rcv_rtt_est.time = tcp_time_stamp;
+}
+
+static inline void tcp_rcv_rtt_measure_ts(struct tcp_sock *tp, struct sk_buff *skb)
+{
+	if (tp->rx_opt.rcv_tsecr &&
+	    (TCP_SKB_CB(skb)->end_seq -
+	     TCP_SKB_CB(skb)->seq >= tp->ack.rcv_mss))
+		tcp_rcv_rtt_update(tp, tcp_time_stamp - tp->rx_opt.rcv_tsecr, 0);
+}
+
+/*
+ * This function should be called every time data is copied to user space.
+ * It calculates the appropriate TCP receive buffer space.
+ */
+void tcp_rcv_space_adjust(struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	int time;
+	int space;
+	
+	if (tp->rcvq_space.time == 0)
+		goto new_measure;
+	
+	time = tcp_time_stamp - tp->rcvq_space.time;
+	if (time < (tp->rcv_rtt_est.rtt >> 3) ||
+	    tp->rcv_rtt_est.rtt == 0)
+		return;
+	
+	space = 2 * (tp->copied_seq - tp->rcvq_space.seq);
+
+	space = max(tp->rcvq_space.space, space);
+
+	if (tp->rcvq_space.space != space) {
+		int rcvmem;
+
+		tp->rcvq_space.space = space;
+
+		if (sysctl_tcp_moderate_rcvbuf) {
+			int new_clamp = space;
+
+			/* Receive space grows, normalize in order to
+			 * take into account packet headers and sk_buff
+			 * structure overhead.
+			 */
+			space /= tp->advmss;
+			if (!space)
+				space = 1;
+			rcvmem = (tp->advmss + MAX_TCP_HEADER +
+				  16 + sizeof(struct sk_buff));
+			while (tcp_win_from_space(rcvmem) < tp->advmss)
+				rcvmem += 128;
+			space *= rcvmem;
+			space = min(space, sysctl_tcp_rmem[2]);
+			if (space > sk->sk_rcvbuf) {
+				sk->sk_rcvbuf = space;
+
+				/* Make the window clamp follow along.  */
+				tp->window_clamp = new_clamp;
+			}
+		}
+	}
+	
+new_measure:
+	tp->rcvq_space.seq = tp->copied_seq;
+	tp->rcvq_space.time = tcp_time_stamp;
+}
+
+/* There is something which you must keep in mind when you analyze the
+ * behavior of the tp->ato delayed ack timeout interval.  When a
+ * connection starts up, we want to ack as quickly as possible.  The
+ * problem is that "good" TCP's do slow start at the beginning of data
+ * transmission.  The means that until we send the first few ACK's the
+ * sender will sit on his end and only queue most of his data, because
+ * he can only send snd_cwnd unacked packets at any given time.  For
+ * each ACK we send, he increments snd_cwnd and transmits more of his
+ * queue.  -DaveM
+ */
+static void tcp_event_data_recv(struct sock *sk, struct tcp_sock *tp, struct sk_buff *skb)
+{
+	u32 now;
+
+	tcp_schedule_ack(tp);
+
+	tcp_measure_rcv_mss(tp, skb);
+
+	tcp_rcv_rtt_measure(tp);
+	
+	now = tcp_time_stamp;
+
+	if (!tp->ack.ato) {
+		/* The _first_ data packet received, initialize
+		 * delayed ACK engine.
+		 */
+		tcp_incr_quickack(tp);
+		tp->ack.ato = TCP_ATO_MIN;
+	} else {
+		int m = now - tp->ack.lrcvtime;
+
+		if (m <= TCP_ATO_MIN/2) {
+			/* The fastest case is the first. */
+			tp->ack.ato = (tp->ack.ato>>1) + TCP_ATO_MIN/2;
+		} else if (m < tp->ack.ato) {
+			tp->ack.ato = (tp->ack.ato>>1) + m;
+			if (tp->ack.ato > tp->rto)
+				tp->ack.ato = tp->rto;
+		} else if (m > tp->rto) {
+			/* Too long gap. Apparently sender falled to
+			 * restart window, so that we send ACKs quickly.
+			 */
+			tcp_incr_quickack(tp);
+			sk_stream_mem_reclaim(sk);
+		}
+	}
+	tp->ack.lrcvtime = now;
+
+	TCP_ECN_check_ce(tp, skb);
+
+	if (skb->len >= 128)
+		tcp_grow_window(sk, tp, skb);
+}
+
+/* When starting a new connection, pin down the current choice of 
+ * congestion algorithm.
+ */
+void tcp_ca_init(struct tcp_sock *tp)
+{
+	if (sysctl_tcp_westwood) 
+		tp->adv_cong = TCP_WESTWOOD;
+	else if (sysctl_tcp_bic)
+		tp->adv_cong = TCP_BIC;
+	else if (sysctl_tcp_vegas_cong_avoid) {
+		tp->adv_cong = TCP_VEGAS;
+		tp->vegas.baseRTT = 0x7fffffff;
+		tcp_vegas_enable(tp);
+	} 
+}
+
+/* Do RTT sampling needed for Vegas.
+ * Basically we:
+ *   o min-filter RTT samples from within an RTT to get the current
+ *     propagation delay + queuing delay (we are min-filtering to try to
+ *     avoid the effects of delayed ACKs)
+ *   o min-filter RTT samples from a much longer window (forever for now)
+ *     to find the propagation delay (baseRTT)
+ */
+static inline void vegas_rtt_calc(struct tcp_sock *tp, __u32 rtt)
+{
+	__u32 vrtt = rtt + 1; /* Never allow zero rtt or baseRTT */
+
+	/* Filter to find propagation delay: */
+	if (vrtt < tp->vegas.baseRTT) 
+		tp->vegas.baseRTT = vrtt;
+
+	/* Find the min RTT during the last RTT to find
+	 * the current prop. delay + queuing delay:
+	 */
+	tp->vegas.minRTT = min(tp->vegas.minRTT, vrtt);
+	tp->vegas.cntRTT++;
+}
+
+/* Called to compute a smoothed rtt estimate. The data fed to this
+ * routine either comes from timestamps, or from segments that were
+ * known _not_ to have been retransmitted [see Karn/Partridge
+ * Proceedings SIGCOMM 87]. The algorithm is from the SIGCOMM 88
+ * piece by Van Jacobson.
+ * NOTE: the next three routines used to be one big routine.
+ * To save cycles in the RFC 1323 implementation it was better to break
+ * it up into three procedures. -- erics
+ */
+static void tcp_rtt_estimator(struct tcp_sock *tp, __u32 mrtt)
+{
+	long m = mrtt; /* RTT */
+
+	if (tcp_vegas_enabled(tp))
+		vegas_rtt_calc(tp, mrtt);
+
+	/*	The following amusing code comes from Jacobson's
+	 *	article in SIGCOMM '88.  Note that rtt and mdev
+	 *	are scaled versions of rtt and mean deviation.
+	 *	This is designed to be as fast as possible 
+	 *	m stands for "measurement".
+	 *
+	 *	On a 1990 paper the rto value is changed to:
+	 *	RTO = rtt + 4 * mdev
+	 *
+	 * Funny. This algorithm seems to be very broken.
+	 * These formulae increase RTO, when it should be decreased, increase
+	 * too slowly, when it should be incresed fastly, decrease too fastly
+	 * etc. I guess in BSD RTO takes ONE value, so that it is absolutely
+	 * does not matter how to _calculate_ it. Seems, it was trap
+	 * that VJ failed to avoid. 8)
+	 */
+	if(m == 0)
+		m = 1;
+	if (tp->srtt != 0) {
+		m -= (tp->srtt >> 3);	/* m is now error in rtt est */
+		tp->srtt += m;		/* rtt = 7/8 rtt + 1/8 new */
+		if (m < 0) {
+			m = -m;		/* m is now abs(error) */
+			m -= (tp->mdev >> 2);   /* similar update on mdev */
+			/* This is similar to one of Eifel findings.
+			 * Eifel blocks mdev updates when rtt decreases.
+			 * This solution is a bit different: we use finer gain
+			 * for mdev in this case (alpha*beta).
+			 * Like Eifel it also prevents growth of rto,
+			 * but also it limits too fast rto decreases,
+			 * happening in pure Eifel.
+			 */
+			if (m > 0)
+				m >>= 3;
+		} else {
+			m -= (tp->mdev >> 2);   /* similar update on mdev */
+		}
+		tp->mdev += m;	    	/* mdev = 3/4 mdev + 1/4 new */
+		if (tp->mdev > tp->mdev_max) {
+			tp->mdev_max = tp->mdev;
+			if (tp->mdev_max > tp->rttvar)
+				tp->rttvar = tp->mdev_max;
+		}
+		if (after(tp->snd_una, tp->rtt_seq)) {
+			if (tp->mdev_max < tp->rttvar)
+				tp->rttvar -= (tp->rttvar-tp->mdev_max)>>2;
+			tp->rtt_seq = tp->snd_nxt;
+			tp->mdev_max = TCP_RTO_MIN;
+		}
+	} else {
+		/* no previous measure. */
+		tp->srtt = m<<3;	/* take the measured time to be rtt */
+		tp->mdev = m<<1;	/* make sure rto = 3*rtt */
+		tp->mdev_max = tp->rttvar = max(tp->mdev, TCP_RTO_MIN);
+		tp->rtt_seq = tp->snd_nxt;
+	}
+
+	tcp_westwood_update_rtt(tp, tp->srtt >> 3);
+}
+
+/* Calculate rto without backoff.  This is the second half of Van Jacobson's
+ * routine referred to above.
+ */
+static inline void tcp_set_rto(struct tcp_sock *tp)
+{
+	/* Old crap is replaced with new one. 8)
+	 *
+	 * More seriously:
+	 * 1. If rtt variance happened to be less 50msec, it is hallucination.
+	 *    It cannot be less due to utterly erratic ACK generation made
+	 *    at least by solaris and freebsd. "Erratic ACKs" has _nothing_
+	 *    to do with delayed acks, because at cwnd>2 true delack timeout
+	 *    is invisible. Actually, Linux-2.4 also generates erratic
+	 *    ACKs in some curcumstances.
+	 */
+	tp->rto = (tp->srtt >> 3) + tp->rttvar;
+
+	/* 2. Fixups made earlier cannot be right.
+	 *    If we do not estimate RTO correctly without them,
+	 *    all the algo is pure shit and should be replaced
+	 *    with correct one. It is exaclty, which we pretend to do.
+	 */
+}
+
+/* NOTE: clamping at TCP_RTO_MIN is not required, current algo
+ * guarantees that rto is higher.
+ */
+static inline void tcp_bound_rto(struct tcp_sock *tp)
+{
+	if (tp->rto > TCP_RTO_MAX)
+		tp->rto = TCP_RTO_MAX;
+}
+
+/* Save metrics learned by this TCP session.
+   This function is called only, when TCP finishes successfully
+   i.e. when it enters TIME-WAIT or goes from LAST-ACK to CLOSE.
+ */
+void tcp_update_metrics(struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct dst_entry *dst = __sk_dst_get(sk);
+
+	if (sysctl_tcp_nometrics_save)
+		return;
+
+	dst_confirm(dst);
+
+	if (dst && (dst->flags&DST_HOST)) {
+		int m;
+
+		if (tp->backoff || !tp->srtt) {
+			/* This session failed to estimate rtt. Why?
+			 * Probably, no packets returned in time.
+			 * Reset our results.
+			 */
+			if (!(dst_metric_locked(dst, RTAX_RTT)))
+				dst->metrics[RTAX_RTT-1] = 0;
+			return;
+		}
+
+		m = dst_metric(dst, RTAX_RTT) - tp->srtt;
+
+		/* If newly calculated rtt larger than stored one,
+		 * store new one. Otherwise, use EWMA. Remember,
+		 * rtt overestimation is always better than underestimation.
+		 */
+		if (!(dst_metric_locked(dst, RTAX_RTT))) {
+			if (m <= 0)
+				dst->metrics[RTAX_RTT-1] = tp->srtt;
+			else
+				dst->metrics[RTAX_RTT-1] -= (m>>3);
+		}
+
+		if (!(dst_metric_locked(dst, RTAX_RTTVAR))) {
+			if (m < 0)
+				m = -m;
+
+			/* Scale deviation to rttvar fixed point */
+			m >>= 1;
+			if (m < tp->mdev)
+				m = tp->mdev;
+
+			if (m >= dst_metric(dst, RTAX_RTTVAR))
+				dst->metrics[RTAX_RTTVAR-1] = m;
+			else
+				dst->metrics[RTAX_RTTVAR-1] -=
+					(dst->metrics[RTAX_RTTVAR-1] - m)>>2;
+		}
+
+		if (tp->snd_ssthresh >= 0xFFFF) {
+			/* Slow start still did not finish. */
+			if (dst_metric(dst, RTAX_SSTHRESH) &&
+			    !dst_metric_locked(dst, RTAX_SSTHRESH) &&
+			    (tp->snd_cwnd >> 1) > dst_metric(dst, RTAX_SSTHRESH))
+				dst->metrics[RTAX_SSTHRESH-1] = tp->snd_cwnd >> 1;
+			if (!dst_metric_locked(dst, RTAX_CWND) &&
+			    tp->snd_cwnd > dst_metric(dst, RTAX_CWND))
+				dst->metrics[RTAX_CWND-1] = tp->snd_cwnd;
+		} else if (tp->snd_cwnd > tp->snd_ssthresh &&
+			   tp->ca_state == TCP_CA_Open) {
+			/* Cong. avoidance phase, cwnd is reliable. */
+			if (!dst_metric_locked(dst, RTAX_SSTHRESH))
+				dst->metrics[RTAX_SSTHRESH-1] =
+					max(tp->snd_cwnd >> 1, tp->snd_ssthresh);
+			if (!dst_metric_locked(dst, RTAX_CWND))
+				dst->metrics[RTAX_CWND-1] = (dst->metrics[RTAX_CWND-1] + tp->snd_cwnd) >> 1;
+		} else {
+			/* Else slow start did not finish, cwnd is non-sense,
+			   ssthresh may be also invalid.
+			 */
+			if (!dst_metric_locked(dst, RTAX_CWND))
+				dst->metrics[RTAX_CWND-1] = (dst->metrics[RTAX_CWND-1] + tp->snd_ssthresh) >> 1;
+			if (dst->metrics[RTAX_SSTHRESH-1] &&
+			    !dst_metric_locked(dst, RTAX_SSTHRESH) &&
+			    tp->snd_ssthresh > dst->metrics[RTAX_SSTHRESH-1])
+				dst->metrics[RTAX_SSTHRESH-1] = tp->snd_ssthresh;
+		}
+
+		if (!dst_metric_locked(dst, RTAX_REORDERING)) {
+			if (dst->metrics[RTAX_REORDERING-1] < tp->reordering &&
+			    tp->reordering != sysctl_tcp_reordering)
+				dst->metrics[RTAX_REORDERING-1] = tp->reordering;
+		}
+	}
+}
+
+/* Numbers are taken from RFC2414.  */
+__u32 tcp_init_cwnd(struct tcp_sock *tp, struct dst_entry *dst)
+{
+	__u32 cwnd = (dst ? dst_metric(dst, RTAX_INITCWND) : 0);
+
+	if (!cwnd) {
+		if (tp->mss_cache_std > 1460)
+			cwnd = 2;
+		else
+			cwnd = (tp->mss_cache_std > 1095) ? 3 : 4;
+	}
+	return min_t(__u32, cwnd, tp->snd_cwnd_clamp);
+}
+
+/* Initialize metrics on socket. */
+
+static void tcp_init_metrics(struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct dst_entry *dst = __sk_dst_get(sk);
+
+	if (dst == NULL)
+		goto reset;
+
+	dst_confirm(dst);
+
+	if (dst_metric_locked(dst, RTAX_CWND))
+		tp->snd_cwnd_clamp = dst_metric(dst, RTAX_CWND);
+	if (dst_metric(dst, RTAX_SSTHRESH)) {
+		tp->snd_ssthresh = dst_metric(dst, RTAX_SSTHRESH);
+		if (tp->snd_ssthresh > tp->snd_cwnd_clamp)
+			tp->snd_ssthresh = tp->snd_cwnd_clamp;
+	}
+	if (dst_metric(dst, RTAX_REORDERING) &&
+	    tp->reordering != dst_metric(dst, RTAX_REORDERING)) {
+		tp->rx_opt.sack_ok &= ~2;
+		tp->reordering = dst_metric(dst, RTAX_REORDERING);
+	}
+
+	if (dst_metric(dst, RTAX_RTT) == 0)
+		goto reset;
+
+	if (!tp->srtt && dst_metric(dst, RTAX_RTT) < (TCP_TIMEOUT_INIT << 3))
+		goto reset;
+
+	/* Initial rtt is determined from SYN,SYN-ACK.
+	 * The segment is small and rtt may appear much
+	 * less than real one. Use per-dst memory
+	 * to make it more realistic.
+	 *
+	 * A bit of theory. RTT is time passed after "normal" sized packet
+	 * is sent until it is ACKed. In normal curcumstances sending small
+	 * packets force peer to delay ACKs and calculation is correct too.
+	 * The algorithm is adaptive and, provided we follow specs, it
+	 * NEVER underestimate RTT. BUT! If peer tries to make some clever
+	 * tricks sort of "quick acks" for time long enough to decrease RTT
+	 * to low value, and then abruptly stops to do it and starts to delay
+	 * ACKs, wait for troubles.
+	 */
+	if (dst_metric(dst, RTAX_RTT) > tp->srtt) {
+		tp->srtt = dst_metric(dst, RTAX_RTT);
+		tp->rtt_seq = tp->snd_nxt;
+	}
+	if (dst_metric(dst, RTAX_RTTVAR) > tp->mdev) {
+		tp->mdev = dst_metric(dst, RTAX_RTTVAR);
+		tp->mdev_max = tp->rttvar = max(tp->mdev, TCP_RTO_MIN);
+	}
+	tcp_set_rto(tp);
+	tcp_bound_rto(tp);
+	if (tp->rto < TCP_TIMEOUT_INIT && !tp->rx_opt.saw_tstamp)
+		goto reset;
+	tp->snd_cwnd = tcp_init_cwnd(tp, dst);
+	tp->snd_cwnd_stamp = tcp_time_stamp;
+	return;
+
+reset:
+	/* Play conservative. If timestamps are not
+	 * supported, TCP will fail to recalculate correct
+	 * rtt, if initial rto is too small. FORGET ALL AND RESET!
+	 */
+	if (!tp->rx_opt.saw_tstamp && tp->srtt) {
+		tp->srtt = 0;
+		tp->mdev = tp->mdev_max = tp->rttvar = TCP_TIMEOUT_INIT;
+		tp->rto = TCP_TIMEOUT_INIT;
+	}
+}
+
+static void tcp_update_reordering(struct tcp_sock *tp, int metric, int ts)
+{
+	if (metric > tp->reordering) {
+		tp->reordering = min(TCP_MAX_REORDERING, metric);
+
+		/* This exciting event is worth to be remembered. 8) */
+		if (ts)
+			NET_INC_STATS_BH(LINUX_MIB_TCPTSREORDER);
+		else if (IsReno(tp))
+			NET_INC_STATS_BH(LINUX_MIB_TCPRENOREORDER);
+		else if (IsFack(tp))
+			NET_INC_STATS_BH(LINUX_MIB_TCPFACKREORDER);
+		else
+			NET_INC_STATS_BH(LINUX_MIB_TCPSACKREORDER);
+#if FASTRETRANS_DEBUG > 1
+		printk(KERN_DEBUG "Disorder%d %d %u f%u s%u rr%d\n",
+		       tp->rx_opt.sack_ok, tp->ca_state,
+		       tp->reordering,
+		       tp->fackets_out,
+		       tp->sacked_out,
+		       tp->undo_marker ? tp->undo_retrans : 0);
+#endif
+		/* Disable FACK yet. */
+		tp->rx_opt.sack_ok &= ~2;
+	}
+}
+
+/* This procedure tags the retransmission queue when SACKs arrive.
+ *
+ * We have three tag bits: SACKED(S), RETRANS(R) and LOST(L).
+ * Packets in queue with these bits set are counted in variables
+ * sacked_out, retrans_out and lost_out, correspondingly.
+ *
+ * Valid combinations are:
+ * Tag  InFlight	Description
+ * 0	1		- orig segment is in flight.
+ * S	0		- nothing flies, orig reached receiver.
+ * L	0		- nothing flies, orig lost by net.
+ * R	2		- both orig and retransmit are in flight.
+ * L|R	1		- orig is lost, retransmit is in flight.
+ * S|R  1		- orig reached receiver, retrans is still in flight.
+ * (L|S|R is logically valid, it could occur when L|R is sacked,
+ *  but it is equivalent to plain S and code short-curcuits it to S.
+ *  L|S is logically invalid, it would mean -1 packet in flight 8))
+ *
+ * These 6 states form finite state machine, controlled by the following events:
+ * 1. New ACK (+SACK) arrives. (tcp_sacktag_write_queue())
+ * 2. Retransmission. (tcp_retransmit_skb(), tcp_xmit_retransmit_queue())
+ * 3. Loss detection event of one of three flavors:
+ *	A. Scoreboard estimator decided the packet is lost.
+ *	   A'. Reno "three dupacks" marks head of queue lost.
+ *	   A''. Its FACK modfication, head until snd.fack is lost.
+ *	B. SACK arrives sacking data transmitted after never retransmitted
+ *	   hole was sent out.
+ *	C. SACK arrives sacking SND.NXT at the moment, when the
+ *	   segment was retransmitted.
+ * 4. D-SACK added new rule: D-SACK changes any tag to S.
+ *
+ * It is pleasant to note, that state diagram turns out to be commutative,
+ * so that we are allowed not to be bothered by order of our actions,
+ * when multiple events arrive simultaneously. (see the function below).
+ *
+ * Reordering detection.
+ * --------------------
+ * Reordering metric is maximal distance, which a packet can be displaced
+ * in packet stream. With SACKs we can estimate it:
+ *
+ * 1. SACK fills old hole and the corresponding segment was not
+ *    ever retransmitted -> reordering. Alas, we cannot use it
+ *    when segment was retransmitted.
+ * 2. The last flaw is solved with D-SACK. D-SACK arrives
+ *    for retransmitted and already SACKed segment -> reordering..
+ * Both of these heuristics are not used in Loss state, when we cannot
+ * account for retransmits accurately.
+ */
+static int
+tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_una)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	unsigned char *ptr = ack_skb->h.raw + TCP_SKB_CB(ack_skb)->sacked;
+	struct tcp_sack_block *sp = (struct tcp_sack_block *)(ptr+2);
+	int num_sacks = (ptr[1] - TCPOLEN_SACK_BASE)>>3;
+	int reord = tp->packets_out;
+	int prior_fackets;
+	u32 lost_retrans = 0;
+	int flag = 0;
+	int i;
+
+	/* So, SACKs for already sent large segments will be lost.
+	 * Not good, but alternative is to resegment the queue. */
+	if (sk->sk_route_caps & NETIF_F_TSO) {
+		sk->sk_route_caps &= ~NETIF_F_TSO;
+		sock_set_flag(sk, SOCK_NO_LARGESEND);
+		tp->mss_cache = tp->mss_cache_std;
+	}
+
+	if (!tp->sacked_out)
+		tp->fackets_out = 0;
+	prior_fackets = tp->fackets_out;
+
+	for (i=0; i<num_sacks; i++, sp++) {
+		struct sk_buff *skb;
+		__u32 start_seq = ntohl(sp->start_seq);
+		__u32 end_seq = ntohl(sp->end_seq);
+		int fack_count = 0;
+		int dup_sack = 0;
+
+		/* Check for D-SACK. */
+		if (i == 0) {
+			u32 ack = TCP_SKB_CB(ack_skb)->ack_seq;
+
+			if (before(start_seq, ack)) {
+				dup_sack = 1;
+				tp->rx_opt.sack_ok |= 4;
+				NET_INC_STATS_BH(LINUX_MIB_TCPDSACKRECV);
+			} else if (num_sacks > 1 &&
+				   !after(end_seq, ntohl(sp[1].end_seq)) &&
+				   !before(start_seq, ntohl(sp[1].start_seq))) {
+				dup_sack = 1;
+				tp->rx_opt.sack_ok |= 4;
+				NET_INC_STATS_BH(LINUX_MIB_TCPDSACKOFORECV);
+			}
+
+			/* D-SACK for already forgotten data...
+			 * Do dumb counting. */
+			if (dup_sack &&
+			    !after(end_seq, prior_snd_una) &&
+			    after(end_seq, tp->undo_marker))
+				tp->undo_retrans--;
+
+			/* Eliminate too old ACKs, but take into
+			 * account more or less fresh ones, they can
+			 * contain valid SACK info.
+			 */
+			if (before(ack, prior_snd_una - tp->max_window))
+				return 0;
+		}
+
+		/* Event "B" in the comment above. */
+		if (after(end_seq, tp->high_seq))
+			flag |= FLAG_DATA_LOST;
+
+		sk_stream_for_retrans_queue(skb, sk) {
+			u8 sacked = TCP_SKB_CB(skb)->sacked;
+			int in_sack;
+
+			/* The retransmission queue is always in order, so
+			 * we can short-circuit the walk early.
+			 */
+			if(!before(TCP_SKB_CB(skb)->seq, end_seq))
+				break;
+
+			fack_count += tcp_skb_pcount(skb);
+
+			in_sack = !after(start_seq, TCP_SKB_CB(skb)->seq) &&
+				!before(end_seq, TCP_SKB_CB(skb)->end_seq);
+
+			/* Account D-SACK for retransmitted packet. */
+			if ((dup_sack && in_sack) &&
+			    (sacked & TCPCB_RETRANS) &&
+			    after(TCP_SKB_CB(skb)->end_seq, tp->undo_marker))
+				tp->undo_retrans--;
+
+			/* The frame is ACKed. */
+			if (!after(TCP_SKB_CB(skb)->end_seq, tp->snd_una)) {
+				if (sacked&TCPCB_RETRANS) {
+					if ((dup_sack && in_sack) &&
+					    (sacked&TCPCB_SACKED_ACKED))
+						reord = min(fack_count, reord);
+				} else {
+					/* If it was in a hole, we detected reordering. */
+					if (fack_count < prior_fackets &&
+					    !(sacked&TCPCB_SACKED_ACKED))
+						reord = min(fack_count, reord);
+				}
+
+				/* Nothing to do; acked frame is about to be dropped. */
+				continue;
+			}
+
+			if ((sacked&TCPCB_SACKED_RETRANS) &&
+			    after(end_seq, TCP_SKB_CB(skb)->ack_seq) &&
+			    (!lost_retrans || after(end_seq, lost_retrans)))
+				lost_retrans = end_seq;
+
+			if (!in_sack)
+				continue;
+
+			if (!(sacked&TCPCB_SACKED_ACKED)) {
+				if (sacked & TCPCB_SACKED_RETRANS) {
+					/* If the segment is not tagged as lost,
+					 * we do not clear RETRANS, believing
+					 * that retransmission is still in flight.
+					 */
+					if (sacked & TCPCB_LOST) {
+						TCP_SKB_CB(skb)->sacked &= ~(TCPCB_LOST|TCPCB_SACKED_RETRANS);
+						tp->lost_out -= tcp_skb_pcount(skb);
+						tp->retrans_out -= tcp_skb_pcount(skb);
+					}
+				} else {
+					/* New sack for not retransmitted frame,
+					 * which was in hole. It is reordering.
+					 */
+					if (!(sacked & TCPCB_RETRANS) &&
+					    fack_count < prior_fackets)
+						reord = min(fack_count, reord);
+
+					if (sacked & TCPCB_LOST) {
+						TCP_SKB_CB(skb)->sacked &= ~TCPCB_LOST;
+						tp->lost_out -= tcp_skb_pcount(skb);
+					}
+				}
+
+				TCP_SKB_CB(skb)->sacked |= TCPCB_SACKED_ACKED;
+				flag |= FLAG_DATA_SACKED;
+				tp->sacked_out += tcp_skb_pcount(skb);
+
+				if (fack_count > tp->fackets_out)
+					tp->fackets_out = fack_count;
+			} else {
+				if (dup_sack && (sacked&TCPCB_RETRANS))
+					reord = min(fack_count, reord);
+			}
+
+			/* D-SACK. We can detect redundant retransmission
+			 * in S|R and plain R frames and clear it.
+			 * undo_retrans is decreased above, L|R frames
+			 * are accounted above as well.
+			 */
+			if (dup_sack &&
+			    (TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_RETRANS)) {
+				TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS;
+				tp->retrans_out -= tcp_skb_pcount(skb);
+			}
+		}
+	}
+
+	/* Check for lost retransmit. This superb idea is
+	 * borrowed from "ratehalving". Event "C".
+	 * Later note: FACK people cheated me again 8),
+	 * we have to account for reordering! Ugly,
+	 * but should help.
+	 */
+	if (lost_retrans && tp->ca_state == TCP_CA_Recovery) {
+		struct sk_buff *skb;
+
+		sk_stream_for_retrans_queue(skb, sk) {
+			if (after(TCP_SKB_CB(skb)->seq, lost_retrans))
+				break;
+			if (!after(TCP_SKB_CB(skb)->end_seq, tp->snd_una))
+				continue;
+			if ((TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_RETRANS) &&
+			    after(lost_retrans, TCP_SKB_CB(skb)->ack_seq) &&
+			    (IsFack(tp) ||
+			     !before(lost_retrans,
+				     TCP_SKB_CB(skb)->ack_seq + tp->reordering *
+				     tp->mss_cache_std))) {
+				TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS;
+				tp->retrans_out -= tcp_skb_pcount(skb);
+
+				if (!(TCP_SKB_CB(skb)->sacked&(TCPCB_LOST|TCPCB_SACKED_ACKED))) {
+					tp->lost_out += tcp_skb_pcount(skb);
+					TCP_SKB_CB(skb)->sacked |= TCPCB_LOST;
+					flag |= FLAG_DATA_SACKED;
+					NET_INC_STATS_BH(LINUX_MIB_TCPLOSTRETRANSMIT);
+				}
+			}
+		}
+	}
+
+	tp->left_out = tp->sacked_out + tp->lost_out;
+
+	if ((reord < tp->fackets_out) && tp->ca_state != TCP_CA_Loss)
+		tcp_update_reordering(tp, ((tp->fackets_out + 1) - reord), 0);
+
+#if FASTRETRANS_DEBUG > 0
+	BUG_TRAP((int)tp->sacked_out >= 0);
+	BUG_TRAP((int)tp->lost_out >= 0);
+	BUG_TRAP((int)tp->retrans_out >= 0);
+	BUG_TRAP((int)tcp_packets_in_flight(tp) >= 0);
+#endif
+	return flag;
+}
+
+/* RTO occurred, but do not yet enter loss state. Instead, transmit two new
+ * segments to see from the next ACKs whether any data was really missing.
+ * If the RTO was spurious, new ACKs should arrive.
+ */
+void tcp_enter_frto(struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct sk_buff *skb;
+
+	tp->frto_counter = 1;
+
+	if (tp->ca_state <= TCP_CA_Disorder ||
+            tp->snd_una == tp->high_seq ||
+            (tp->ca_state == TCP_CA_Loss && !tp->retransmits)) {
+		tp->prior_ssthresh = tcp_current_ssthresh(tp);
+		if (!tcp_westwood_ssthresh(tp))
+			tp->snd_ssthresh = tcp_recalc_ssthresh(tp);
+	}
+
+	/* Have to clear retransmission markers here to keep the bookkeeping
+	 * in shape, even though we are not yet in Loss state.
+	 * If something was really lost, it is eventually caught up
+	 * in tcp_enter_frto_loss.
+	 */
+	tp->retrans_out = 0;
+	tp->undo_marker = tp->snd_una;
+	tp->undo_retrans = 0;
+
+	sk_stream_for_retrans_queue(skb, sk) {
+		TCP_SKB_CB(skb)->sacked &= ~TCPCB_RETRANS;
+	}
+	tcp_sync_left_out(tp);
+
+	tcp_set_ca_state(tp, TCP_CA_Open);
+	tp->frto_highmark = tp->snd_nxt;
+}
+
+/* Enter Loss state after F-RTO was applied. Dupack arrived after RTO,
+ * which indicates that we should follow the traditional RTO recovery,
+ * i.e. mark everything lost and do go-back-N retransmission.
+ */
+static void tcp_enter_frto_loss(struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct sk_buff *skb;
+	int cnt = 0;
+
+	tp->sacked_out = 0;
+	tp->lost_out = 0;
+	tp->fackets_out = 0;
+
+	sk_stream_for_retrans_queue(skb, sk) {
+		cnt += tcp_skb_pcount(skb);
+		TCP_SKB_CB(skb)->sacked &= ~TCPCB_LOST;
+		if (!(TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_ACKED)) {
+
+			/* Do not mark those segments lost that were
+			 * forward transmitted after RTO
+			 */
+			if (!after(TCP_SKB_CB(skb)->end_seq,
+				   tp->frto_highmark)) {
+				TCP_SKB_CB(skb)->sacked |= TCPCB_LOST;
+				tp->lost_out += tcp_skb_pcount(skb);
+			}
+		} else {
+			tp->sacked_out += tcp_skb_pcount(skb);
+			tp->fackets_out = cnt;
+		}
+	}
+	tcp_sync_left_out(tp);
+
+	tp->snd_cwnd = tp->frto_counter + tcp_packets_in_flight(tp)+1;
+	tp->snd_cwnd_cnt = 0;
+	tp->snd_cwnd_stamp = tcp_time_stamp;
+	tp->undo_marker = 0;
+	tp->frto_counter = 0;
+
+	tp->reordering = min_t(unsigned int, tp->reordering,
+					     sysctl_tcp_reordering);
+	tcp_set_ca_state(tp, TCP_CA_Loss);
+	tp->high_seq = tp->frto_highmark;
+	TCP_ECN_queue_cwr(tp);
+
+	init_bictcp(tp);
+}
+
+void tcp_clear_retrans(struct tcp_sock *tp)
+{
+	tp->left_out = 0;
+	tp->retrans_out = 0;
+
+	tp->fackets_out = 0;
+	tp->sacked_out = 0;
+	tp->lost_out = 0;
+
+	tp->undo_marker = 0;
+	tp->undo_retrans = 0;
+}
+
+/* Enter Loss state. If "how" is not zero, forget all SACK information
+ * and reset tags completely, otherwise preserve SACKs. If receiver
+ * dropped its ofo queue, we will know this due to reneging detection.
+ */
+void tcp_enter_loss(struct sock *sk, int how)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct sk_buff *skb;
+	int cnt = 0;
+
+	/* Reduce ssthresh if it has not yet been made inside this window. */
+	if (tp->ca_state <= TCP_CA_Disorder || tp->snd_una == tp->high_seq ||
+	    (tp->ca_state == TCP_CA_Loss && !tp->retransmits)) {
+		tp->prior_ssthresh = tcp_current_ssthresh(tp);
+		tp->snd_ssthresh = tcp_recalc_ssthresh(tp);
+	}
+	tp->snd_cwnd	   = 1;
+	tp->snd_cwnd_cnt   = 0;
+	tp->snd_cwnd_stamp = tcp_time_stamp;
+
+	tcp_clear_retrans(tp);
+
+	/* Push undo marker, if it was plain RTO and nothing
+	 * was retransmitted. */
+	if (!how)
+		tp->undo_marker = tp->snd_una;
+
+	sk_stream_for_retrans_queue(skb, sk) {
+		cnt += tcp_skb_pcount(skb);
+		if (TCP_SKB_CB(skb)->sacked&TCPCB_RETRANS)
+			tp->undo_marker = 0;
+		TCP_SKB_CB(skb)->sacked &= (~TCPCB_TAGBITS)|TCPCB_SACKED_ACKED;
+		if (!(TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_ACKED) || how) {
+			TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_ACKED;
+			TCP_SKB_CB(skb)->sacked |= TCPCB_LOST;
+			tp->lost_out += tcp_skb_pcount(skb);
+		} else {
+			tp->sacked_out += tcp_skb_pcount(skb);
+			tp->fackets_out = cnt;
+		}
+	}
+	tcp_sync_left_out(tp);
+
+	tp->reordering = min_t(unsigned int, tp->reordering,
+					     sysctl_tcp_reordering);
+	tcp_set_ca_state(tp, TCP_CA_Loss);
+	tp->high_seq = tp->snd_nxt;
+	TCP_ECN_queue_cwr(tp);
+}
+
+static int tcp_check_sack_reneging(struct sock *sk, struct tcp_sock *tp)
+{
+	struct sk_buff *skb;
+
+	/* If ACK arrived pointing to a remembered SACK,
+	 * it means that our remembered SACKs do not reflect
+	 * real state of receiver i.e.
+	 * receiver _host_ is heavily congested (or buggy).
+	 * Do processing similar to RTO timeout.
+	 */
+	if ((skb = skb_peek(&sk->sk_write_queue)) != NULL &&
+	    (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED)) {
+		NET_INC_STATS_BH(LINUX_MIB_TCPSACKRENEGING);
+
+		tcp_enter_loss(sk, 1);
+		tp->retransmits++;
+		tcp_retransmit_skb(sk, skb_peek(&sk->sk_write_queue));
+		tcp_reset_xmit_timer(sk, TCP_TIME_RETRANS, tp->rto);
+		return 1;
+	}
+	return 0;
+}
+
+static inline int tcp_fackets_out(struct tcp_sock *tp)
+{
+	return IsReno(tp) ? tp->sacked_out+1 : tp->fackets_out;
+}
+
+static inline int tcp_skb_timedout(struct tcp_sock *tp, struct sk_buff *skb)
+{
+	return (tcp_time_stamp - TCP_SKB_CB(skb)->when > tp->rto);
+}
+
+static inline int tcp_head_timedout(struct sock *sk, struct tcp_sock *tp)
+{
+	return tp->packets_out &&
+	       tcp_skb_timedout(tp, skb_peek(&sk->sk_write_queue));
+}
+
+/* Linux NewReno/SACK/FACK/ECN state machine.
+ * --------------------------------------
+ *
+ * "Open"	Normal state, no dubious events, fast path.
+ * "Disorder"   In all the respects it is "Open",
+ *		but requires a bit more attention. It is entered when
+ *		we see some SACKs or dupacks. It is split of "Open"
+ *		mainly to move some processing from fast path to slow one.
+ * "CWR"	CWND was reduced due to some Congestion Notification event.
+ *		It can be ECN, ICMP source quench, local device congestion.
+ * "Recovery"	CWND was reduced, we are fast-retransmitting.
+ * "Loss"	CWND was reduced due to RTO timeout or SACK reneging.
+ *
+ * tcp_fastretrans_alert() is entered:
+ * - each incoming ACK, if state is not "Open"
+ * - when arrived ACK is unusual, namely:
+ *	* SACK
+ *	* Duplicate ACK.
+ *	* ECN ECE.
+ *
+ * Counting packets in flight is pretty simple.
+ *
+ *	in_flight = packets_out - left_out + retrans_out
+ *
+ *	packets_out is SND.NXT-SND.UNA counted in packets.
+ *
+ *	retrans_out is number of retransmitted segments.
+ *
+ *	left_out is number of segments left network, but not ACKed yet.
+ *
+ *		left_out = sacked_out + lost_out
+ *
+ *     sacked_out: Packets, which arrived to receiver out of order
+ *		   and hence not ACKed. With SACKs this number is simply
+ *		   amount of SACKed data. Even without SACKs
+ *		   it is easy to give pretty reliable estimate of this number,
+ *		   counting duplicate ACKs.
+ *
+ *       lost_out: Packets lost by network. TCP has no explicit
+ *		   "loss notification" feedback from network (for now).
+ *		   It means that this number can be only _guessed_.
+ *		   Actually, it is the heuristics to predict lossage that
+ *		   distinguishes different algorithms.
+ *
+ *	F.e. after RTO, when all the queue is considered as lost,
+ *	lost_out = packets_out and in_flight = retrans_out.
+ *
+ *		Essentially, we have now two algorithms counting
+ *		lost packets.
+ *
+ *		FACK: It is the simplest heuristics. As soon as we decided
+ *		that something is lost, we decide that _all_ not SACKed
+ *		packets until the most forward SACK are lost. I.e.
+ *		lost_out = fackets_out - sacked_out and left_out = fackets_out.
+ *		It is absolutely correct estimate, if network does not reorder
+ *		packets. And it loses any connection to reality when reordering
+ *		takes place. We use FACK by default until reordering
+ *		is suspected on the path to this destination.
+ *
+ *		NewReno: when Recovery is entered, we assume that one segment
+ *		is lost (classic Reno). While we are in Recovery and
+ *		a partial ACK arrives, we assume that one more packet
+ *		is lost (NewReno). This heuristics are the same in NewReno
+ *		and SACK.
+ *
+ *  Imagine, that's all! Forget about all this shamanism about CWND inflation
+ *  deflation etc. CWND is real congestion window, never inflated, changes
+ *  only according to classic VJ rules.
+ *
+ * Really tricky (and requiring careful tuning) part of algorithm
+ * is hidden in functions tcp_time_to_recover() and tcp_xmit_retransmit_queue().
+ * The first determines the moment _when_ we should reduce CWND and,
+ * hence, slow down forward transmission. In fact, it determines the moment
+ * when we decide that hole is caused by loss, rather than by a reorder.
+ *
+ * tcp_xmit_retransmit_queue() decides, _what_ we should retransmit to fill
+ * holes, caused by lost packets.
+ *
+ * And the most logically complicated part of algorithm is undo
+ * heuristics. We detect false retransmits due to both too early
+ * fast retransmit (reordering) and underestimated RTO, analyzing
+ * timestamps and D-SACKs. When we detect that some segments were
+ * retransmitted by mistake and CWND reduction was wrong, we undo
+ * window reduction and abort recovery phase. This logic is hidden
+ * inside several functions named tcp_try_undo_<something>.
+ */
+
+/* This function decides, when we should leave Disordered state
+ * and enter Recovery phase, reducing congestion window.
+ *
+ * Main question: may we further continue forward transmission
+ * with the same cwnd?
+ */
+static int tcp_time_to_recover(struct sock *sk, struct tcp_sock *tp)
+{
+	__u32 packets_out;
+
+	/* Trick#1: The loss is proven. */
+	if (tp->lost_out)
+		return 1;
+
+	/* Not-A-Trick#2 : Classic rule... */
+	if (tcp_fackets_out(tp) > tp->reordering)
+		return 1;
+
+	/* Trick#3 : when we use RFC2988 timer restart, fast
+	 * retransmit can be triggered by timeout of queue head.
+	 */
+	if (tcp_head_timedout(sk, tp))
+		return 1;
+
+	/* Trick#4: It is still not OK... But will it be useful to delay
+	 * recovery more?
+	 */
+	packets_out = tp->packets_out;
+	if (packets_out <= tp->reordering &&
+	    tp->sacked_out >= max_t(__u32, packets_out/2, sysctl_tcp_reordering) &&
+	    !tcp_may_send_now(sk, tp)) {
+		/* We have nothing to send. This connection is limited
+		 * either by receiver window or by application.
+		 */
+		return 1;
+	}
+
+	return 0;
+}
+
+/* If we receive more dupacks than we expected counting segments
+ * in assumption of absent reordering, interpret this as reordering.
+ * The only another reason could be bug in receiver TCP.
+ */
+static void tcp_check_reno_reordering(struct tcp_sock *tp, int addend)
+{
+	u32 holes;
+
+	holes = max(tp->lost_out, 1U);
+	holes = min(holes, tp->packets_out);
+
+	if ((tp->sacked_out + holes) > tp->packets_out) {
+		tp->sacked_out = tp->packets_out - holes;
+		tcp_update_reordering(tp, tp->packets_out+addend, 0);
+	}
+}
+
+/* Emulate SACKs for SACKless connection: account for a new dupack. */
+
+static void tcp_add_reno_sack(struct tcp_sock *tp)
+{
+	tp->sacked_out++;
+	tcp_check_reno_reordering(tp, 0);
+	tcp_sync_left_out(tp);
+}
+
+/* Account for ACK, ACKing some data in Reno Recovery phase. */
+
+static void tcp_remove_reno_sacks(struct sock *sk, struct tcp_sock *tp, int acked)
+{
+	if (acked > 0) {
+		/* One ACK acked hole. The rest eat duplicate ACKs. */
+		if (acked-1 >= tp->sacked_out)
+			tp->sacked_out = 0;
+		else
+			tp->sacked_out -= acked-1;
+	}
+	tcp_check_reno_reordering(tp, acked);
+	tcp_sync_left_out(tp);
+}
+
+static inline void tcp_reset_reno_sack(struct tcp_sock *tp)
+{
+	tp->sacked_out = 0;
+	tp->left_out = tp->lost_out;
+}
+
+/* Mark head of queue up as lost. */
+static void tcp_mark_head_lost(struct sock *sk, struct tcp_sock *tp,
+			       int packets, u32 high_seq)
+{
+	struct sk_buff *skb;
+	int cnt = packets;
+
+	BUG_TRAP(cnt <= tp->packets_out);
+
+	sk_stream_for_retrans_queue(skb, sk) {
+		cnt -= tcp_skb_pcount(skb);
+		if (cnt < 0 || after(TCP_SKB_CB(skb)->end_seq, high_seq))
+			break;
+		if (!(TCP_SKB_CB(skb)->sacked&TCPCB_TAGBITS)) {
+			TCP_SKB_CB(skb)->sacked |= TCPCB_LOST;
+			tp->lost_out += tcp_skb_pcount(skb);
+		}
+	}
+	tcp_sync_left_out(tp);
+}
+
+/* Account newly detected lost packet(s) */
+
+static void tcp_update_scoreboard(struct sock *sk, struct tcp_sock *tp)
+{
+	if (IsFack(tp)) {
+		int lost = tp->fackets_out - tp->reordering;
+		if (lost <= 0)
+			lost = 1;
+		tcp_mark_head_lost(sk, tp, lost, tp->high_seq);
+	} else {
+		tcp_mark_head_lost(sk, tp, 1, tp->high_seq);
+	}
+
+	/* New heuristics: it is possible only after we switched
+	 * to restart timer each time when something is ACKed.
+	 * Hence, we can detect timed out packets during fast
+	 * retransmit without falling to slow start.
+	 */
+	if (tcp_head_timedout(sk, tp)) {
+		struct sk_buff *skb;
+
+		sk_stream_for_retrans_queue(skb, sk) {
+			if (tcp_skb_timedout(tp, skb) &&
+			    !(TCP_SKB_CB(skb)->sacked&TCPCB_TAGBITS)) {
+				TCP_SKB_CB(skb)->sacked |= TCPCB_LOST;
+				tp->lost_out += tcp_skb_pcount(skb);
+			}
+		}
+		tcp_sync_left_out(tp);
+	}
+}
+
+/* CWND moderation, preventing bursts due to too big ACKs
+ * in dubious situations.
+ */
+static inline void tcp_moderate_cwnd(struct tcp_sock *tp)
+{
+	tp->snd_cwnd = min(tp->snd_cwnd,
+			   tcp_packets_in_flight(tp)+tcp_max_burst(tp));
+	tp->snd_cwnd_stamp = tcp_time_stamp;
+}
+
+/* Decrease cwnd each second ack. */
+
+static void tcp_cwnd_down(struct tcp_sock *tp)
+{
+	int decr = tp->snd_cwnd_cnt + 1;
+	__u32 limit;
+
+	/*
+	 * TCP Westwood
+	 * Here limit is evaluated as BWestimation*RTTmin (for obtaining it
+	 * in packets we use mss_cache). If sysctl_tcp_westwood is off
+	 * tcp_westwood_bw_rttmin() returns 0. In such case snd_ssthresh is
+	 * still used as usual. It prevents other strange cases in which
+	 * BWE*RTTmin could assume value 0. It should not happen but...
+	 */
+
+	if (!(limit = tcp_westwood_bw_rttmin(tp)))
+		limit = tp->snd_ssthresh/2;
+
+	tp->snd_cwnd_cnt = decr&1;
+	decr >>= 1;
+
+	if (decr && tp->snd_cwnd > limit)
+		tp->snd_cwnd -= decr;
+
+	tp->snd_cwnd = min(tp->snd_cwnd, tcp_packets_in_flight(tp)+1);
+	tp->snd_cwnd_stamp = tcp_time_stamp;
+}
+
+/* Nothing was retransmitted or returned timestamp is less
+ * than timestamp of the first retransmission.
+ */
+static inline int tcp_packet_delayed(struct tcp_sock *tp)
+{
+	return !tp->retrans_stamp ||
+		(tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr &&
+		 (__s32)(tp->rx_opt.rcv_tsecr - tp->retrans_stamp) < 0);
+}
+
+/* Undo procedures. */
+
+#if FASTRETRANS_DEBUG > 1
+static void DBGUNDO(struct sock *sk, struct tcp_sock *tp, const char *msg)
+{
+	struct inet_sock *inet = inet_sk(sk);
+	printk(KERN_DEBUG "Undo %s %u.%u.%u.%u/%u c%u l%u ss%u/%u p%u\n",
+	       msg,
+	       NIPQUAD(inet->daddr), ntohs(inet->dport),
+	       tp->snd_cwnd, tp->left_out,
+	       tp->snd_ssthresh, tp->prior_ssthresh,
+	       tp->packets_out);
+}
+#else
+#define DBGUNDO(x...) do { } while (0)
+#endif
+
+static void tcp_undo_cwr(struct tcp_sock *tp, int undo)
+{
+	if (tp->prior_ssthresh) {
+		if (tcp_is_bic(tp))
+			tp->snd_cwnd = max(tp->snd_cwnd, tp->bictcp.last_max_cwnd);
+		else
+			tp->snd_cwnd = max(tp->snd_cwnd, tp->snd_ssthresh<<1);
+
+		if (undo && tp->prior_ssthresh > tp->snd_ssthresh) {
+			tp->snd_ssthresh = tp->prior_ssthresh;
+			TCP_ECN_withdraw_cwr(tp);
+		}
+	} else {
+		tp->snd_cwnd = max(tp->snd_cwnd, tp->snd_ssthresh);
+	}
+	tcp_moderate_cwnd(tp);
+	tp->snd_cwnd_stamp = tcp_time_stamp;
+}
+
+static inline int tcp_may_undo(struct tcp_sock *tp)
+{
+	return tp->undo_marker &&
+		(!tp->undo_retrans || tcp_packet_delayed(tp));
+}
+
+/* People celebrate: "We love our President!" */
+static int tcp_try_undo_recovery(struct sock *sk, struct tcp_sock *tp)
+{
+	if (tcp_may_undo(tp)) {
+		/* Happy end! We did not retransmit anything
+		 * or our original transmission succeeded.
+		 */
+		DBGUNDO(sk, tp, tp->ca_state == TCP_CA_Loss ? "loss" : "retrans");
+		tcp_undo_cwr(tp, 1);
+		if (tp->ca_state == TCP_CA_Loss)
+			NET_INC_STATS_BH(LINUX_MIB_TCPLOSSUNDO);
+		else
+			NET_INC_STATS_BH(LINUX_MIB_TCPFULLUNDO);
+		tp->undo_marker = 0;
+	}
+	if (tp->snd_una == tp->high_seq && IsReno(tp)) {
+		/* Hold old state until something *above* high_seq
+		 * is ACKed. For Reno it is MUST to prevent false
+		 * fast retransmits (RFC2582). SACK TCP is safe. */
+		tcp_moderate_cwnd(tp);
+		return 1;
+	}
+	tcp_set_ca_state(tp, TCP_CA_Open);
+	return 0;
+}
+
+/* Try to undo cwnd reduction, because D-SACKs acked all retransmitted data */
+static void tcp_try_undo_dsack(struct sock *sk, struct tcp_sock *tp)
+{
+	if (tp->undo_marker && !tp->undo_retrans) {
+		DBGUNDO(sk, tp, "D-SACK");
+		tcp_undo_cwr(tp, 1);
+		tp->undo_marker = 0;
+		NET_INC_STATS_BH(LINUX_MIB_TCPDSACKUNDO);
+	}
+}
+
+/* Undo during fast recovery after partial ACK. */
+
+static int tcp_try_undo_partial(struct sock *sk, struct tcp_sock *tp,
+				int acked)
+{
+	/* Partial ACK arrived. Force Hoe's retransmit. */
+	int failed = IsReno(tp) || tp->fackets_out>tp->reordering;
+
+	if (tcp_may_undo(tp)) {
+		/* Plain luck! Hole if filled with delayed
+		 * packet, rather than with a retransmit.
+		 */
+		if (tp->retrans_out == 0)
+			tp->retrans_stamp = 0;
+
+		tcp_update_reordering(tp, tcp_fackets_out(tp)+acked, 1);
+
+		DBGUNDO(sk, tp, "Hoe");
+		tcp_undo_cwr(tp, 0);
+		NET_INC_STATS_BH(LINUX_MIB_TCPPARTIALUNDO);
+
+		/* So... Do not make Hoe's retransmit yet.
+		 * If the first packet was delayed, the rest
+		 * ones are most probably delayed as well.
+		 */
+		failed = 0;
+	}
+	return failed;
+}
+
+/* Undo during loss recovery after partial ACK. */
+static int tcp_try_undo_loss(struct sock *sk, struct tcp_sock *tp)
+{
+	if (tcp_may_undo(tp)) {
+		struct sk_buff *skb;
+		sk_stream_for_retrans_queue(skb, sk) {
+			TCP_SKB_CB(skb)->sacked &= ~TCPCB_LOST;
+		}
+		DBGUNDO(sk, tp, "partial loss");
+		tp->lost_out = 0;
+		tp->left_out = tp->sacked_out;
+		tcp_undo_cwr(tp, 1);
+		NET_INC_STATS_BH(LINUX_MIB_TCPLOSSUNDO);
+		tp->retransmits = 0;
+		tp->undo_marker = 0;
+		if (!IsReno(tp))
+			tcp_set_ca_state(tp, TCP_CA_Open);
+		return 1;
+	}
+	return 0;
+}
+
+static inline void tcp_complete_cwr(struct tcp_sock *tp)
+{
+	if (tcp_westwood_cwnd(tp)) 
+		tp->snd_ssthresh = tp->snd_cwnd;
+	else
+		tp->snd_cwnd = min(tp->snd_cwnd, tp->snd_ssthresh);
+	tp->snd_cwnd_stamp = tcp_time_stamp;
+}
+
+static void tcp_try_to_open(struct sock *sk, struct tcp_sock *tp, int flag)
+{
+	tp->left_out = tp->sacked_out;
+
+	if (tp->retrans_out == 0)
+		tp->retrans_stamp = 0;
+
+	if (flag&FLAG_ECE)
+		tcp_enter_cwr(tp);
+
+	if (tp->ca_state != TCP_CA_CWR) {
+		int state = TCP_CA_Open;
+
+		if (tp->left_out || tp->retrans_out || tp->undo_marker)
+			state = TCP_CA_Disorder;
+
+		if (tp->ca_state != state) {
+			tcp_set_ca_state(tp, state);
+			tp->high_seq = tp->snd_nxt;
+		}
+		tcp_moderate_cwnd(tp);
+	} else {
+		tcp_cwnd_down(tp);
+	}
+}
+
+/* Process an event, which can update packets-in-flight not trivially.
+ * Main goal of this function is to calculate new estimate for left_out,
+ * taking into account both packets sitting in receiver's buffer and
+ * packets lost by network.
+ *
+ * Besides that it does CWND reduction, when packet loss is detected
+ * and changes state of machine.
+ *
+ * It does _not_ decide what to send, it is made in function
+ * tcp_xmit_retransmit_queue().
+ */
+static void
+tcp_fastretrans_alert(struct sock *sk, u32 prior_snd_una,
+		      int prior_packets, int flag)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	int is_dupack = (tp->snd_una == prior_snd_una && !(flag&FLAG_NOT_DUP));
+
+	/* Some technical things:
+	 * 1. Reno does not count dupacks (sacked_out) automatically. */
+	if (!tp->packets_out)
+		tp->sacked_out = 0;
+        /* 2. SACK counts snd_fack in packets inaccurately. */
+	if (tp->sacked_out == 0)
+		tp->fackets_out = 0;
+
+        /* Now state machine starts.
+	 * A. ECE, hence prohibit cwnd undoing, the reduction is required. */
+	if (flag&FLAG_ECE)
+		tp->prior_ssthresh = 0;
+
+	/* B. In all the states check for reneging SACKs. */
+	if (tp->sacked_out && tcp_check_sack_reneging(sk, tp))
+		return;
+
+	/* C. Process data loss notification, provided it is valid. */
+	if ((flag&FLAG_DATA_LOST) &&
+	    before(tp->snd_una, tp->high_seq) &&
+	    tp->ca_state != TCP_CA_Open &&
+	    tp->fackets_out > tp->reordering) {
+		tcp_mark_head_lost(sk, tp, tp->fackets_out-tp->reordering, tp->high_seq);
+		NET_INC_STATS_BH(LINUX_MIB_TCPLOSS);
+	}
+
+	/* D. Synchronize left_out to current state. */
+	tcp_sync_left_out(tp);
+
+	/* E. Check state exit conditions. State can be terminated
+	 *    when high_seq is ACKed. */
+	if (tp->ca_state == TCP_CA_Open) {
+		if (!sysctl_tcp_frto)
+			BUG_TRAP(tp->retrans_out == 0);
+		tp->retrans_stamp = 0;
+	} else if (!before(tp->snd_una, tp->high_seq)) {
+		switch (tp->ca_state) {
+		case TCP_CA_Loss:
+			tp->retransmits = 0;
+			if (tcp_try_undo_recovery(sk, tp))
+				return;
+			break;
+
+		case TCP_CA_CWR:
+			/* CWR is to be held something *above* high_seq
+			 * is ACKed for CWR bit to reach receiver. */
+			if (tp->snd_una != tp->high_seq) {
+				tcp_complete_cwr(tp);
+				tcp_set_ca_state(tp, TCP_CA_Open);
+			}
+			break;
+
+		case TCP_CA_Disorder:
+			tcp_try_undo_dsack(sk, tp);
+			if (!tp->undo_marker ||
+			    /* For SACK case do not Open to allow to undo
+			     * catching for all duplicate ACKs. */
+			    IsReno(tp) || tp->snd_una != tp->high_seq) {
+				tp->undo_marker = 0;
+				tcp_set_ca_state(tp, TCP_CA_Open);
+			}
+			break;
+
+		case TCP_CA_Recovery:
+			if (IsReno(tp))
+				tcp_reset_reno_sack(tp);
+			if (tcp_try_undo_recovery(sk, tp))
+				return;
+			tcp_complete_cwr(tp);
+			break;
+		}
+	}
+
+	/* F. Process state. */
+	switch (tp->ca_state) {
+	case TCP_CA_Recovery:
+		if (prior_snd_una == tp->snd_una) {
+			if (IsReno(tp) && is_dupack)
+				tcp_add_reno_sack(tp);
+		} else {
+			int acked = prior_packets - tp->packets_out;
+			if (IsReno(tp))
+				tcp_remove_reno_sacks(sk, tp, acked);
+			is_dupack = tcp_try_undo_partial(sk, tp, acked);
+		}
+		break;
+	case TCP_CA_Loss:
+		if (flag&FLAG_DATA_ACKED)
+			tp->retransmits = 0;
+		if (!tcp_try_undo_loss(sk, tp)) {
+			tcp_moderate_cwnd(tp);
+			tcp_xmit_retransmit_queue(sk);
+			return;
+		}
+		if (tp->ca_state != TCP_CA_Open)
+			return;
+		/* Loss is undone; fall through to processing in Open state. */
+	default:
+		if (IsReno(tp)) {
+			if (tp->snd_una != prior_snd_una)
+				tcp_reset_reno_sack(tp);
+			if (is_dupack)
+				tcp_add_reno_sack(tp);
+		}
+
+		if (tp->ca_state == TCP_CA_Disorder)
+			tcp_try_undo_dsack(sk, tp);
+
+		if (!tcp_time_to_recover(sk, tp)) {
+			tcp_try_to_open(sk, tp, flag);
+			return;
+		}
+
+		/* Otherwise enter Recovery state */
+
+		if (IsReno(tp))
+			NET_INC_STATS_BH(LINUX_MIB_TCPRENORECOVERY);
+		else
+			NET_INC_STATS_BH(LINUX_MIB_TCPSACKRECOVERY);
+
+		tp->high_seq = tp->snd_nxt;
+		tp->prior_ssthresh = 0;
+		tp->undo_marker = tp->snd_una;
+		tp->undo_retrans = tp->retrans_out;
+
+		if (tp->ca_state < TCP_CA_CWR) {
+			if (!(flag&FLAG_ECE))
+				tp->prior_ssthresh = tcp_current_ssthresh(tp);
+			tp->snd_ssthresh = tcp_recalc_ssthresh(tp);
+			TCP_ECN_queue_cwr(tp);
+		}
+
+		tp->snd_cwnd_cnt = 0;
+		tcp_set_ca_state(tp, TCP_CA_Recovery);
+	}
+
+	if (is_dupack || tcp_head_timedout(sk, tp))
+		tcp_update_scoreboard(sk, tp);
+	tcp_cwnd_down(tp);
+	tcp_xmit_retransmit_queue(sk);
+}
+
+/* Read draft-ietf-tcplw-high-performance before mucking
+ * with this code. (Superceeds RFC1323)
+ */
+static void tcp_ack_saw_tstamp(struct tcp_sock *tp, int flag)
+{
+	__u32 seq_rtt;
+
+	/* RTTM Rule: A TSecr value received in a segment is used to
+	 * update the averaged RTT measurement only if the segment
+	 * acknowledges some new data, i.e., only if it advances the
+	 * left edge of the send window.
+	 *
+	 * See draft-ietf-tcplw-high-performance-00, section 3.3.
+	 * 1998/04/10 Andrey V. Savochkin <saw@msu.ru>
+	 *
+	 * Changed: reset backoff as soon as we see the first valid sample.
+	 * If we do not, we get strongly overstimated rto. With timestamps
+	 * samples are accepted even from very old segments: f.e., when rtt=1
+	 * increases to 8, we retransmit 5 times and after 8 seconds delayed
+	 * answer arrives rto becomes 120 seconds! If at least one of segments
+	 * in window is lost... Voila.	 			--ANK (010210)
+	 */
+	seq_rtt = tcp_time_stamp - tp->rx_opt.rcv_tsecr;
+	tcp_rtt_estimator(tp, seq_rtt);
+	tcp_set_rto(tp);
+	tp->backoff = 0;
+	tcp_bound_rto(tp);
+}
+
+static void tcp_ack_no_tstamp(struct tcp_sock *tp, u32 seq_rtt, int flag)
+{
+	/* We don't have a timestamp. Can only use
+	 * packets that are not retransmitted to determine
+	 * rtt estimates. Also, we must not reset the
+	 * backoff for rto until we get a non-retransmitted
+	 * packet. This allows us to deal with a situation
+	 * where the network delay has increased suddenly.
+	 * I.e. Karn's algorithm. (SIGCOMM '87, p5.)
+	 */
+
+	if (flag & FLAG_RETRANS_DATA_ACKED)
+		return;
+
+	tcp_rtt_estimator(tp, seq_rtt);
+	tcp_set_rto(tp);
+	tp->backoff = 0;
+	tcp_bound_rto(tp);
+}
+
+static inline void tcp_ack_update_rtt(struct tcp_sock *tp,
+				      int flag, s32 seq_rtt)
+{
+	/* Note that peer MAY send zero echo. In this case it is ignored. (rfc1323) */
+	if (tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr)
+		tcp_ack_saw_tstamp(tp, flag);
+	else if (seq_rtt >= 0)
+		tcp_ack_no_tstamp(tp, seq_rtt, flag);
+}
+
+/*
+ * Compute congestion window to use.
+ *
+ * This is from the implementation of BICTCP in
+ * Lison-Xu, Kahaled Harfoush, and Injog Rhee.
+ *  "Binary Increase Congestion Control for Fast, Long Distance
+ *  Networks" in InfoComm 2004
+ * Available from:
+ *  http://www.csc.ncsu.edu/faculty/rhee/export/bitcp.pdf
+ *
+ * Unless BIC is enabled and congestion window is large
+ * this behaves the same as the original Reno.
+ */
+static inline __u32 bictcp_cwnd(struct tcp_sock *tp)
+{
+	/* orignal Reno behaviour */
+	if (!tcp_is_bic(tp))
+		return tp->snd_cwnd;
+
+	if (tp->bictcp.last_cwnd == tp->snd_cwnd &&
+	   (s32)(tcp_time_stamp - tp->bictcp.last_stamp) <= (HZ>>5))
+		return tp->bictcp.cnt;
+
+	tp->bictcp.last_cwnd = tp->snd_cwnd;
+	tp->bictcp.last_stamp = tcp_time_stamp;
+      
+	/* start off normal */
+	if (tp->snd_cwnd <= sysctl_tcp_bic_low_window)
+		tp->bictcp.cnt = tp->snd_cwnd;
+
+	/* binary increase */
+	else if (tp->snd_cwnd < tp->bictcp.last_max_cwnd) {
+		__u32 	dist = (tp->bictcp.last_max_cwnd - tp->snd_cwnd)
+			/ BICTCP_B;
+
+		if (dist > BICTCP_MAX_INCREMENT)
+			/* linear increase */
+			tp->bictcp.cnt = tp->snd_cwnd / BICTCP_MAX_INCREMENT;
+		else if (dist <= 1U)
+			/* binary search increase */
+			tp->bictcp.cnt = tp->snd_cwnd * BICTCP_FUNC_OF_MIN_INCR
+				/ BICTCP_B;
+		else
+			/* binary search increase */
+			tp->bictcp.cnt = tp->snd_cwnd / dist;
+	} else {
+		/* slow start amd linear increase */
+		if (tp->snd_cwnd < tp->bictcp.last_max_cwnd + BICTCP_B)
+			/* slow start */
+			tp->bictcp.cnt = tp->snd_cwnd * BICTCP_FUNC_OF_MIN_INCR
+				/ BICTCP_B;
+		else if (tp->snd_cwnd < tp->bictcp.last_max_cwnd
+			 		+ BICTCP_MAX_INCREMENT*(BICTCP_B-1))
+			/* slow start */
+			tp->bictcp.cnt = tp->snd_cwnd * (BICTCP_B-1)
+				/ (tp->snd_cwnd-tp->bictcp.last_max_cwnd);
+		else
+			/* linear increase */
+			tp->bictcp.cnt = tp->snd_cwnd / BICTCP_MAX_INCREMENT;
+	}
+	return tp->bictcp.cnt;
+}
+
+/* This is Jacobson's slow start and congestion avoidance. 
+ * SIGCOMM '88, p. 328.
+ */
+static inline void reno_cong_avoid(struct tcp_sock *tp)
+{
+        if (tp->snd_cwnd <= tp->snd_ssthresh) {
+                /* In "safe" area, increase. */
+		if (tp->snd_cwnd < tp->snd_cwnd_clamp)
+			tp->snd_cwnd++;
+	} else {
+                /* In dangerous area, increase slowly.
+		 * In theory this is tp->snd_cwnd += 1 / tp->snd_cwnd
+		 */
+		if (tp->snd_cwnd_cnt >= bictcp_cwnd(tp)) {
+			if (tp->snd_cwnd < tp->snd_cwnd_clamp)
+				tp->snd_cwnd++;
+			tp->snd_cwnd_cnt=0;
+		} else
+			tp->snd_cwnd_cnt++;
+        }
+	tp->snd_cwnd_stamp = tcp_time_stamp;
+}
+
+/* This is based on the congestion detection/avoidance scheme described in
+ *    Lawrence S. Brakmo and Larry L. Peterson.
+ *    "TCP Vegas: End to end congestion avoidance on a global internet."
+ *    IEEE Journal on Selected Areas in Communication, 13(8):1465--1480,
+ *    October 1995. Available from:
+ *	ftp://ftp.cs.arizona.edu/xkernel/Papers/jsac.ps
+ *
+ * See http://www.cs.arizona.edu/xkernel/ for their implementation.
+ * The main aspects that distinguish this implementation from the
+ * Arizona Vegas implementation are:
+ *   o We do not change the loss detection or recovery mechanisms of
+ *     Linux in any way. Linux already recovers from losses quite well,
+ *     using fine-grained timers, NewReno, and FACK.
+ *   o To avoid the performance penalty imposed by increasing cwnd
+ *     only every-other RTT during slow start, we increase during
+ *     every RTT during slow start, just like Reno.
+ *   o Largely to allow continuous cwnd growth during slow start,
+ *     we use the rate at which ACKs come back as the "actual"
+ *     rate, rather than the rate at which data is sent.
+ *   o To speed convergence to the right rate, we set the cwnd
+ *     to achieve the right ("actual") rate when we exit slow start.
+ *   o To filter out the noise caused by delayed ACKs, we use the
+ *     minimum RTT sample observed during the last RTT to calculate
+ *     the actual rate.
+ *   o When the sender re-starts from idle, it waits until it has
+ *     received ACKs for an entire flight of new data before making
+ *     a cwnd adjustment decision. The original Vegas implementation
+ *     assumed senders never went idle.
+ */
+static void vegas_cong_avoid(struct tcp_sock *tp, u32 ack, u32 seq_rtt)
+{
+	/* The key players are v_beg_snd_una and v_beg_snd_nxt.
+	 *
+	 * These are so named because they represent the approximate values
+	 * of snd_una and snd_nxt at the beginning of the current RTT. More
+	 * precisely, they represent the amount of data sent during the RTT.
+	 * At the end of the RTT, when we receive an ACK for v_beg_snd_nxt,
+	 * we will calculate that (v_beg_snd_nxt - v_beg_snd_una) outstanding
+	 * bytes of data have been ACKed during the course of the RTT, giving
+	 * an "actual" rate of:
+	 *
+	 *     (v_beg_snd_nxt - v_beg_snd_una) / (rtt duration)
+	 *
+	 * Unfortunately, v_beg_snd_una is not exactly equal to snd_una,
+	 * because delayed ACKs can cover more than one segment, so they
+	 * don't line up nicely with the boundaries of RTTs.
+	 *
+	 * Another unfortunate fact of life is that delayed ACKs delay the
+	 * advance of the left edge of our send window, so that the number
+	 * of bytes we send in an RTT is often less than our cwnd will allow.
+	 * So we keep track of our cwnd separately, in v_beg_snd_cwnd.
+	 */
+
+	if (after(ack, tp->vegas.beg_snd_nxt)) {
+		/* Do the Vegas once-per-RTT cwnd adjustment. */
+		u32 old_wnd, old_snd_cwnd;
+
+		
+		/* Here old_wnd is essentially the window of data that was
+		 * sent during the previous RTT, and has all
+		 * been acknowledged in the course of the RTT that ended
+		 * with the ACK we just received. Likewise, old_snd_cwnd
+		 * is the cwnd during the previous RTT.
+		 */
+		old_wnd = (tp->vegas.beg_snd_nxt - tp->vegas.beg_snd_una) /
+			tp->mss_cache_std;
+		old_snd_cwnd = tp->vegas.beg_snd_cwnd;
+
+		/* Save the extent of the current window so we can use this
+		 * at the end of the next RTT.
+		 */
+		tp->vegas.beg_snd_una  = tp->vegas.beg_snd_nxt;
+		tp->vegas.beg_snd_nxt  = tp->snd_nxt;
+		tp->vegas.beg_snd_cwnd = tp->snd_cwnd;
+
+		/* Take into account the current RTT sample too, to
+		 * decrease the impact of delayed acks. This double counts
+		 * this sample since we count it for the next window as well,
+		 * but that's not too awful, since we're taking the min,
+		 * rather than averaging.
+		 */
+		vegas_rtt_calc(tp, seq_rtt);
+
+		/* We do the Vegas calculations only if we got enough RTT
+		 * samples that we can be reasonably sure that we got
+		 * at least one RTT sample that wasn't from a delayed ACK.
+		 * If we only had 2 samples total,
+		 * then that means we're getting only 1 ACK per RTT, which
+		 * means they're almost certainly delayed ACKs.
+		 * If  we have 3 samples, we should be OK.
+		 */
+
+		if (tp->vegas.cntRTT <= 2) {
+			/* We don't have enough RTT samples to do the Vegas
+			 * calculation, so we'll behave like Reno.
+			 */
+			if (tp->snd_cwnd > tp->snd_ssthresh)
+				tp->snd_cwnd++;
+		} else {
+			u32 rtt, target_cwnd, diff;
+
+			/* We have enough RTT samples, so, using the Vegas
+			 * algorithm, we determine if we should increase or
+			 * decrease cwnd, and by how much.
+			 */
+
+			/* Pluck out the RTT we are using for the Vegas
+			 * calculations. This is the min RTT seen during the
+			 * last RTT. Taking the min filters out the effects
+			 * of delayed ACKs, at the cost of noticing congestion
+			 * a bit later.
+			 */
+			rtt = tp->vegas.minRTT;
+
+			/* Calculate the cwnd we should have, if we weren't
+			 * going too fast.
+			 *
+			 * This is:
+			 *     (actual rate in segments) * baseRTT
+			 * We keep it as a fixed point number with
+			 * V_PARAM_SHIFT bits to the right of the binary point.
+			 */
+			target_cwnd = ((old_wnd * tp->vegas.baseRTT)
+				       << V_PARAM_SHIFT) / rtt;
+
+			/* Calculate the difference between the window we had,
+			 * and the window we would like to have. This quantity
+			 * is the "Diff" from the Arizona Vegas papers.
+			 *
+			 * Again, this is a fixed point number with
+			 * V_PARAM_SHIFT bits to the right of the binary
+			 * point.
+			 */
+			diff = (old_wnd << V_PARAM_SHIFT) - target_cwnd;
+
+			if (tp->snd_cwnd < tp->snd_ssthresh) {
+				/* Slow start.  */
+				if (diff > sysctl_tcp_vegas_gamma) {
+					/* Going too fast. Time to slow down
+					 * and switch to congestion avoidance.
+					 */
+					tp->snd_ssthresh = 2;
+
+					/* Set cwnd to match the actual rate
+					 * exactly:
+					 *   cwnd = (actual rate) * baseRTT
+					 * Then we add 1 because the integer
+					 * truncation robs us of full link
+					 * utilization.
+					 */
+					tp->snd_cwnd = min(tp->snd_cwnd,
+							   (target_cwnd >>
+							    V_PARAM_SHIFT)+1);
+
+				}
+			} else {
+				/* Congestion avoidance. */
+				u32 next_snd_cwnd;
+
+				/* Figure out where we would like cwnd
+				 * to be.
+				 */
+				if (diff > sysctl_tcp_vegas_beta) {
+					/* The old window was too fast, so
+					 * we slow down.
+					 */
+					next_snd_cwnd = old_snd_cwnd - 1;
+				} else if (diff < sysctl_tcp_vegas_alpha) {
+					/* We don't have enough extra packets
+					 * in the network, so speed up.
+					 */
+					next_snd_cwnd = old_snd_cwnd + 1;
+				} else {
+					/* Sending just as fast as we
+					 * should be.
+					 */
+					next_snd_cwnd = old_snd_cwnd;
+				}
+
+				/* Adjust cwnd upward or downward, toward the
+				 * desired value.
+				 */
+				if (next_snd_cwnd > tp->snd_cwnd)
+					tp->snd_cwnd++;
+				else if (next_snd_cwnd < tp->snd_cwnd)
+					tp->snd_cwnd--;
+			}
+		}
+
+		/* Wipe the slate clean for the next RTT. */
+		tp->vegas.cntRTT = 0;
+		tp->vegas.minRTT = 0x7fffffff;
+	}
+
+	/* The following code is executed for every ack we receive,
+	 * except for conditions checked in should_advance_cwnd()
+	 * before the call to tcp_cong_avoid(). Mainly this means that
+	 * we only execute this code if the ack actually acked some
+	 * data.
+	 */
+
+	/* If we are in slow start, increase our cwnd in response to this ACK.
+	 * (If we are not in slow start then we are in congestion avoidance,
+	 * and adjust our congestion window only once per RTT. See the code
+	 * above.)
+	 */
+	if (tp->snd_cwnd <= tp->snd_ssthresh) 
+		tp->snd_cwnd++;
+
+	/* to keep cwnd from growing without bound */
+	tp->snd_cwnd = min_t(u32, tp->snd_cwnd, tp->snd_cwnd_clamp);
+
+	/* Make sure that we are never so timid as to reduce our cwnd below
+	 * 2 MSS.
+	 *
+	 * Going below 2 MSS would risk huge delayed ACKs from our receiver.
+	 */
+	tp->snd_cwnd = max(tp->snd_cwnd, 2U);
+
+	tp->snd_cwnd_stamp = tcp_time_stamp;
+}
+
+static inline void tcp_cong_avoid(struct tcp_sock *tp, u32 ack, u32 seq_rtt)
+{
+	if (tcp_vegas_enabled(tp))
+		vegas_cong_avoid(tp, ack, seq_rtt);
+	else
+		reno_cong_avoid(tp);
+}
+
+/* Restart timer after forward progress on connection.
+ * RFC2988 recommends to restart timer to now+rto.
+ */
+
+static inline void tcp_ack_packets_out(struct sock *sk, struct tcp_sock *tp)
+{
+	if (!tp->packets_out) {
+		tcp_clear_xmit_timer(sk, TCP_TIME_RETRANS);
+	} else {
+		tcp_reset_xmit_timer(sk, TCP_TIME_RETRANS, tp->rto);
+	}
+}
+
+/* There is one downside to this scheme.  Although we keep the
+ * ACK clock ticking, adjusting packet counters and advancing
+ * congestion window, we do not liberate socket send buffer
+ * space.
+ *
+ * Mucking with skb->truesize and sk->sk_wmem_alloc et al.
+ * then making a write space wakeup callback is a possible
+ * future enhancement.  WARNING: it is not trivial to make.
+ */
+static int tcp_tso_acked(struct sock *sk, struct sk_buff *skb,
+			 __u32 now, __s32 *seq_rtt)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct tcp_skb_cb *scb = TCP_SKB_CB(skb); 
+	__u32 seq = tp->snd_una;
+	__u32 packets_acked;
+	int acked = 0;
+
+	/* If we get here, the whole TSO packet has not been
+	 * acked.
+	 */
+	BUG_ON(!after(scb->end_seq, seq));
+
+	packets_acked = tcp_skb_pcount(skb);
+	if (tcp_trim_head(sk, skb, seq - scb->seq))
+		return 0;
+	packets_acked -= tcp_skb_pcount(skb);
+
+	if (packets_acked) {
+		__u8 sacked = scb->sacked;
+
+		acked |= FLAG_DATA_ACKED;
+		if (sacked) {
+			if (sacked & TCPCB_RETRANS) {
+				if (sacked & TCPCB_SACKED_RETRANS)
+					tp->retrans_out -= packets_acked;
+				acked |= FLAG_RETRANS_DATA_ACKED;
+				*seq_rtt = -1;
+			} else if (*seq_rtt < 0)
+				*seq_rtt = now - scb->when;
+			if (sacked & TCPCB_SACKED_ACKED)
+				tp->sacked_out -= packets_acked;
+			if (sacked & TCPCB_LOST)
+				tp->lost_out -= packets_acked;
+			if (sacked & TCPCB_URG) {
+				if (tp->urg_mode &&
+				    !before(seq, tp->snd_up))
+					tp->urg_mode = 0;
+			}
+		} else if (*seq_rtt < 0)
+			*seq_rtt = now - scb->when;
+
+		if (tp->fackets_out) {
+			__u32 dval = min(tp->fackets_out, packets_acked);
+			tp->fackets_out -= dval;
+		}
+		tp->packets_out -= packets_acked;
+
+		BUG_ON(tcp_skb_pcount(skb) == 0);
+		BUG_ON(!before(scb->seq, scb->end_seq));
+	}
+
+	return acked;
+}
+
+
+/* Remove acknowledged frames from the retransmission queue. */
+static int tcp_clean_rtx_queue(struct sock *sk, __s32 *seq_rtt_p)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct sk_buff *skb;
+	__u32 now = tcp_time_stamp;
+	int acked = 0;
+	__s32 seq_rtt = -1;
+
+	while ((skb = skb_peek(&sk->sk_write_queue)) &&
+	       skb != sk->sk_send_head) {
+		struct tcp_skb_cb *scb = TCP_SKB_CB(skb); 
+		__u8 sacked = scb->sacked;
+
+		/* If our packet is before the ack sequence we can
+		 * discard it as it's confirmed to have arrived at
+		 * the other end.
+		 */
+		if (after(scb->end_seq, tp->snd_una)) {
+			if (tcp_skb_pcount(skb) > 1)
+				acked |= tcp_tso_acked(sk, skb,
+						       now, &seq_rtt);
+			break;
+		}
+
+		/* Initial outgoing SYN's get put onto the write_queue
+		 * just like anything else we transmit.  It is not
+		 * true data, and if we misinform our callers that
+		 * this ACK acks real data, we will erroneously exit
+		 * connection startup slow start one packet too
+		 * quickly.  This is severely frowned upon behavior.
+		 */
+		if (!(scb->flags & TCPCB_FLAG_SYN)) {
+			acked |= FLAG_DATA_ACKED;
+		} else {
+			acked |= FLAG_SYN_ACKED;
+			tp->retrans_stamp = 0;
+		}
+
+		if (sacked) {
+			if (sacked & TCPCB_RETRANS) {
+				if(sacked & TCPCB_SACKED_RETRANS)
+					tp->retrans_out -= tcp_skb_pcount(skb);
+				acked |= FLAG_RETRANS_DATA_ACKED;
+				seq_rtt = -1;
+			} else if (seq_rtt < 0)
+				seq_rtt = now - scb->when;
+			if (sacked & TCPCB_SACKED_ACKED)
+				tp->sacked_out -= tcp_skb_pcount(skb);
+			if (sacked & TCPCB_LOST)
+				tp->lost_out -= tcp_skb_pcount(skb);
+			if (sacked & TCPCB_URG) {
+				if (tp->urg_mode &&
+				    !before(scb->end_seq, tp->snd_up))
+					tp->urg_mode = 0;
+			}
+		} else if (seq_rtt < 0)
+			seq_rtt = now - scb->when;
+		tcp_dec_pcount_approx(&tp->fackets_out, skb);
+		tcp_packets_out_dec(tp, skb);
+		__skb_unlink(skb, skb->list);
+		sk_stream_free_skb(sk, skb);
+	}
+
+	if (acked&FLAG_ACKED) {
+		tcp_ack_update_rtt(tp, acked, seq_rtt);
+		tcp_ack_packets_out(sk, tp);
+	}
+
+#if FASTRETRANS_DEBUG > 0
+	BUG_TRAP((int)tp->sacked_out >= 0);
+	BUG_TRAP((int)tp->lost_out >= 0);
+	BUG_TRAP((int)tp->retrans_out >= 0);
+	if (!tp->packets_out && tp->rx_opt.sack_ok) {
+		if (tp->lost_out) {
+			printk(KERN_DEBUG "Leak l=%u %d\n",
+			       tp->lost_out, tp->ca_state);
+			tp->lost_out = 0;
+		}
+		if (tp->sacked_out) {
+			printk(KERN_DEBUG "Leak s=%u %d\n",
+			       tp->sacked_out, tp->ca_state);
+			tp->sacked_out = 0;
+		}
+		if (tp->retrans_out) {
+			printk(KERN_DEBUG "Leak r=%u %d\n",
+			       tp->retrans_out, tp->ca_state);
+			tp->retrans_out = 0;
+		}
+	}
+#endif
+	*seq_rtt_p = seq_rtt;
+	return acked;
+}
+
+static void tcp_ack_probe(struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	/* Was it a usable window open? */
+
+	if (!after(TCP_SKB_CB(sk->sk_send_head)->end_seq,
+		   tp->snd_una + tp->snd_wnd)) {
+		tp->backoff = 0;
+		tcp_clear_xmit_timer(sk, TCP_TIME_PROBE0);
+		/* Socket must be waked up by subsequent tcp_data_snd_check().
+		 * This function is not for random using!
+		 */
+	} else {
+		tcp_reset_xmit_timer(sk, TCP_TIME_PROBE0,
+				     min(tp->rto << tp->backoff, TCP_RTO_MAX));
+	}
+}
+
+static inline int tcp_ack_is_dubious(struct tcp_sock *tp, int flag)
+{
+	return (!(flag & FLAG_NOT_DUP) || (flag & FLAG_CA_ALERT) ||
+		tp->ca_state != TCP_CA_Open);
+}
+
+static inline int tcp_may_raise_cwnd(struct tcp_sock *tp, int flag)
+{
+	return (!(flag & FLAG_ECE) || tp->snd_cwnd < tp->snd_ssthresh) &&
+		!((1<<tp->ca_state)&(TCPF_CA_Recovery|TCPF_CA_CWR));
+}
+
+/* Check that window update is acceptable.
+ * The function assumes that snd_una<=ack<=snd_next.
+ */
+static inline int tcp_may_update_window(struct tcp_sock *tp, u32 ack,
+					u32 ack_seq, u32 nwin)
+{
+	return (after(ack, tp->snd_una) ||
+		after(ack_seq, tp->snd_wl1) ||
+		(ack_seq == tp->snd_wl1 && nwin > tp->snd_wnd));
+}
+
+/* Update our send window.
+ *
+ * Window update algorithm, described in RFC793/RFC1122 (used in linux-2.2
+ * and in FreeBSD. NetBSD's one is even worse.) is wrong.
+ */
+static int tcp_ack_update_window(struct sock *sk, struct tcp_sock *tp,
+				 struct sk_buff *skb, u32 ack, u32 ack_seq)
+{
+	int flag = 0;
+	u32 nwin = ntohs(skb->h.th->window);
+
+	if (likely(!skb->h.th->syn))
+		nwin <<= tp->rx_opt.snd_wscale;
+
+	if (tcp_may_update_window(tp, ack, ack_seq, nwin)) {
+		flag |= FLAG_WIN_UPDATE;
+		tcp_update_wl(tp, ack, ack_seq);
+
+		if (tp->snd_wnd != nwin) {
+			tp->snd_wnd = nwin;
+
+			/* Note, it is the only place, where
+			 * fast path is recovered for sending TCP.
+			 */
+			tcp_fast_path_check(sk, tp);
+
+			if (nwin > tp->max_window) {
+				tp->max_window = nwin;
+				tcp_sync_mss(sk, tp->pmtu_cookie);
+			}
+		}
+	}
+
+	tp->snd_una = ack;
+
+	return flag;
+}
+
+static void tcp_process_frto(struct sock *sk, u32 prior_snd_una)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	
+	tcp_sync_left_out(tp);
+	
+	if (tp->snd_una == prior_snd_una ||
+	    !before(tp->snd_una, tp->frto_highmark)) {
+		/* RTO was caused by loss, start retransmitting in
+		 * go-back-N slow start
+		 */
+		tcp_enter_frto_loss(sk);
+		return;
+	}
+
+	if (tp->frto_counter == 1) {
+		/* First ACK after RTO advances the window: allow two new
+		 * segments out.
+		 */
+		tp->snd_cwnd = tcp_packets_in_flight(tp) + 2;
+	} else {
+		/* Also the second ACK after RTO advances the window.
+		 * The RTO was likely spurious. Reduce cwnd and continue
+		 * in congestion avoidance
+		 */
+		tp->snd_cwnd = min(tp->snd_cwnd, tp->snd_ssthresh);
+		tcp_moderate_cwnd(tp);
+	}
+
+	/* F-RTO affects on two new ACKs following RTO.
+	 * At latest on third ACK the TCP behavor is back to normal.
+	 */
+	tp->frto_counter = (tp->frto_counter + 1) % 3;
+}
+
+/*
+ * TCP Westwood+
+ */
+
+/*
+ * @init_westwood
+ * This function initializes fields used in TCP Westwood+. We can't
+ * get no information about RTTmin at this time so we simply set it to
+ * TCP_WESTWOOD_INIT_RTT. This value was chosen to be too conservative
+ * since in this way we're sure it will be updated in a consistent
+ * way as soon as possible. It will reasonably happen within the first
+ * RTT period of the connection lifetime.
+ */
+
+static void init_westwood(struct sock *sk)
+{
+        struct tcp_sock *tp = tcp_sk(sk);
+
+        tp->westwood.bw_ns_est = 0;
+        tp->westwood.bw_est = 0;
+        tp->westwood.accounted = 0;
+        tp->westwood.cumul_ack = 0;
+        tp->westwood.rtt_win_sx = tcp_time_stamp;
+        tp->westwood.rtt = TCP_WESTWOOD_INIT_RTT;
+        tp->westwood.rtt_min = TCP_WESTWOOD_INIT_RTT;
+        tp->westwood.snd_una = tp->snd_una;
+}
+
+/*
+ * @westwood_do_filter
+ * Low-pass filter. Implemented using constant coeffients.
+ */
+
+static inline __u32 westwood_do_filter(__u32 a, __u32 b)
+{
+	return (((7 * a) + b) >> 3);
+}
+
+static void westwood_filter(struct sock *sk, __u32 delta)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	tp->westwood.bw_ns_est =
+		westwood_do_filter(tp->westwood.bw_ns_est, 
+				   tp->westwood.bk / delta);
+	tp->westwood.bw_est =
+		westwood_do_filter(tp->westwood.bw_est,
+				   tp->westwood.bw_ns_est);
+}
+
+/* 
+ * @westwood_update_rttmin
+ * It is used to update RTTmin. In this case we MUST NOT use
+ * WESTWOOD_RTT_MIN minimum bound since we could be on a LAN!
+ */
+
+static inline __u32 westwood_update_rttmin(const struct sock *sk)
+{
+	const struct tcp_sock *tp = tcp_sk(sk);
+	__u32 rttmin = tp->westwood.rtt_min;
+
+	if (tp->westwood.rtt != 0 &&
+	    (tp->westwood.rtt < tp->westwood.rtt_min || !rttmin))
+		rttmin = tp->westwood.rtt;
+
+	return rttmin;
+}
+
+/*
+ * @westwood_acked
+ * Evaluate increases for dk. 
+ */
+
+static inline __u32 westwood_acked(const struct sock *sk)
+{
+	const struct tcp_sock *tp = tcp_sk(sk);
+
+	return tp->snd_una - tp->westwood.snd_una;
+}
+
+/*
+ * @westwood_new_window
+ * It evaluates if we are receiving data inside the same RTT window as
+ * when we started.
+ * Return value:
+ * It returns 0 if we are still evaluating samples in the same RTT
+ * window, 1 if the sample has to be considered in the next window.
+ */
+
+static int westwood_new_window(const struct sock *sk)
+{
+	const struct tcp_sock *tp = tcp_sk(sk);
+	__u32 left_bound;
+	__u32 rtt;
+	int ret = 0;
+
+	left_bound = tp->westwood.rtt_win_sx;
+	rtt = max(tp->westwood.rtt, (u32) TCP_WESTWOOD_RTT_MIN);
+
+	/*
+	 * A RTT-window has passed. Be careful since if RTT is less than
+	 * 50ms we don't filter but we continue 'building the sample'.
+	 * This minimum limit was choosen since an estimation on small
+	 * time intervals is better to avoid...
+	 * Obvioulsy on a LAN we reasonably will always have
+	 * right_bound = left_bound + WESTWOOD_RTT_MIN
+         */
+
+	if ((left_bound + rtt) < tcp_time_stamp)
+		ret = 1;
+
+	return ret;
+}
+
+/*
+ * @westwood_update_window
+ * It updates RTT evaluation window if it is the right moment to do
+ * it. If so it calls filter for evaluating bandwidth. 
+ */
+
+static void __westwood_update_window(struct sock *sk, __u32 now)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	__u32 delta = now - tp->westwood.rtt_win_sx;
+
+        if (delta) {
+		if (tp->westwood.rtt)
+			westwood_filter(sk, delta);
+
+		tp->westwood.bk = 0;
+		tp->westwood.rtt_win_sx = tcp_time_stamp;
+	}
+}
+
+
+static void westwood_update_window(struct sock *sk, __u32 now)
+{
+	if (westwood_new_window(sk)) 
+		__westwood_update_window(sk, now);
+}
+
+/*
+ * @__tcp_westwood_fast_bw
+ * It is called when we are in fast path. In particular it is called when
+ * header prediction is successfull. In such case infact update is
+ * straight forward and doesn't need any particular care.
+ */
+
+static void __tcp_westwood_fast_bw(struct sock *sk, struct sk_buff *skb)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	westwood_update_window(sk, tcp_time_stamp);
+
+	tp->westwood.bk += westwood_acked(sk);
+	tp->westwood.snd_una = tp->snd_una;
+	tp->westwood.rtt_min = westwood_update_rttmin(sk);
+}
+
+static inline void tcp_westwood_fast_bw(struct sock *sk, struct sk_buff *skb)
+{
+        if (tcp_is_westwood(tcp_sk(sk)))
+                __tcp_westwood_fast_bw(sk, skb);
+}
+
+
+/*
+ * @westwood_dupack_update
+ * It updates accounted and cumul_ack when receiving a dupack.
+ */
+
+static void westwood_dupack_update(struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	tp->westwood.accounted += tp->mss_cache_std;
+	tp->westwood.cumul_ack = tp->mss_cache_std;
+}
+
+static inline int westwood_may_change_cumul(struct tcp_sock *tp)
+{
+	return (tp->westwood.cumul_ack > tp->mss_cache_std);
+}
+
+static inline void westwood_partial_update(struct tcp_sock *tp)
+{
+	tp->westwood.accounted -= tp->westwood.cumul_ack;
+	tp->westwood.cumul_ack = tp->mss_cache_std;
+}
+
+static inline void westwood_complete_update(struct tcp_sock *tp)
+{
+	tp->westwood.cumul_ack -= tp->westwood.accounted;
+	tp->westwood.accounted = 0;
+}
+
+/*
+ * @westwood_acked_count
+ * This function evaluates cumul_ack for evaluating dk in case of
+ * delayed or partial acks.
+ */
+
+static inline __u32 westwood_acked_count(struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	tp->westwood.cumul_ack = westwood_acked(sk);
+
+        /* If cumul_ack is 0 this is a dupack since it's not moving
+         * tp->snd_una.
+         */
+        if (!(tp->westwood.cumul_ack))
+                westwood_dupack_update(sk);
+
+        if (westwood_may_change_cumul(tp)) {
+		/* Partial or delayed ack */
+		if (tp->westwood.accounted >= tp->westwood.cumul_ack)
+			westwood_partial_update(tp);
+		else
+			westwood_complete_update(tp);
+	}
+
+	tp->westwood.snd_una = tp->snd_una;
+
+	return tp->westwood.cumul_ack;
+}
+
+
+/*
+ * @__tcp_westwood_slow_bw
+ * It is called when something is going wrong..even if there could
+ * be no problems! Infact a simple delayed packet may trigger a
+ * dupack. But we need to be careful in such case.
+ */
+
+static void __tcp_westwood_slow_bw(struct sock *sk, struct sk_buff *skb)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	westwood_update_window(sk, tcp_time_stamp);
+
+	tp->westwood.bk += westwood_acked_count(sk);
+	tp->westwood.rtt_min = westwood_update_rttmin(sk);
+}
+
+static inline void tcp_westwood_slow_bw(struct sock *sk, struct sk_buff *skb)
+{
+        if (tcp_is_westwood(tcp_sk(sk)))
+                __tcp_westwood_slow_bw(sk, skb);
+}
+
+/* This routine deals with incoming acks, but not outgoing ones. */
+static int tcp_ack(struct sock *sk, struct sk_buff *skb, int flag)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	u32 prior_snd_una = tp->snd_una;
+	u32 ack_seq = TCP_SKB_CB(skb)->seq;
+	u32 ack = TCP_SKB_CB(skb)->ack_seq;
+	u32 prior_in_flight;
+	s32 seq_rtt;
+	int prior_packets;
+
+	/* If the ack is newer than sent or older than previous acks
+	 * then we can probably ignore it.
+	 */
+	if (after(ack, tp->snd_nxt))
+		goto uninteresting_ack;
+
+	if (before(ack, prior_snd_una))
+		goto old_ack;
+
+	if (!(flag&FLAG_SLOWPATH) && after(ack, prior_snd_una)) {
+		/* Window is constant, pure forward advance.
+		 * No more checks are required.
+		 * Note, we use the fact that SND.UNA>=SND.WL2.
+		 */
+		tcp_update_wl(tp, ack, ack_seq);
+		tp->snd_una = ack;
+		tcp_westwood_fast_bw(sk, skb);
+		flag |= FLAG_WIN_UPDATE;
+
+		NET_INC_STATS_BH(LINUX_MIB_TCPHPACKS);
+	} else {
+		if (ack_seq != TCP_SKB_CB(skb)->end_seq)
+			flag |= FLAG_DATA;
+		else
+			NET_INC_STATS_BH(LINUX_MIB_TCPPUREACKS);
+
+		flag |= tcp_ack_update_window(sk, tp, skb, ack, ack_seq);
+
+		if (TCP_SKB_CB(skb)->sacked)
+			flag |= tcp_sacktag_write_queue(sk, skb, prior_snd_una);
+
+		if (TCP_ECN_rcv_ecn_echo(tp, skb->h.th))
+			flag |= FLAG_ECE;
+
+		tcp_westwood_slow_bw(sk,skb);
+	}
+
+	/* We passed data and got it acked, remove any soft error
+	 * log. Something worked...
+	 */
+	sk->sk_err_soft = 0;
+	tp->rcv_tstamp = tcp_time_stamp;
+	prior_packets = tp->packets_out;
+	if (!prior_packets)
+		goto no_queue;
+
+	prior_in_flight = tcp_packets_in_flight(tp);
+
+	/* See if we can take anything off of the retransmit queue. */
+	flag |= tcp_clean_rtx_queue(sk, &seq_rtt);
+
+	if (tp->frto_counter)
+		tcp_process_frto(sk, prior_snd_una);
+
+	if (tcp_ack_is_dubious(tp, flag)) {
+		/* Advanve CWND, if state allows this. */
+		if ((flag & FLAG_DATA_ACKED) &&
+		    (tcp_vegas_enabled(tp) || prior_in_flight >= tp->snd_cwnd) &&
+		    tcp_may_raise_cwnd(tp, flag))
+			tcp_cong_avoid(tp, ack, seq_rtt);
+		tcp_fastretrans_alert(sk, prior_snd_una, prior_packets, flag);
+	} else {
+		if ((flag & FLAG_DATA_ACKED) && 
+		    (tcp_vegas_enabled(tp) || prior_in_flight >= tp->snd_cwnd))
+			tcp_cong_avoid(tp, ack, seq_rtt);
+	}
+
+	if ((flag & FLAG_FORWARD_PROGRESS) || !(flag&FLAG_NOT_DUP))
+		dst_confirm(sk->sk_dst_cache);
+
+	return 1;
+
+no_queue:
+	tp->probes_out = 0;
+
+	/* If this ack opens up a zero window, clear backoff.  It was
+	 * being used to time the probes, and is probably far higher than
+	 * it needs to be for normal retransmission.
+	 */
+	if (sk->sk_send_head)
+		tcp_ack_probe(sk);
+	return 1;
+
+old_ack:
+	if (TCP_SKB_CB(skb)->sacked)
+		tcp_sacktag_write_queue(sk, skb, prior_snd_una);
+
+uninteresting_ack:
+	SOCK_DEBUG(sk, "Ack %u out of %u:%u\n", ack, tp->snd_una, tp->snd_nxt);
+	return 0;
+}
+
+
+/* Look for tcp options. Normally only called on SYN and SYNACK packets.
+ * But, this can also be called on packets in the established flow when
+ * the fast version below fails.
+ */
+void tcp_parse_options(struct sk_buff *skb, struct tcp_options_received *opt_rx, int estab)
+{
+	unsigned char *ptr;
+	struct tcphdr *th = skb->h.th;
+	int length=(th->doff*4)-sizeof(struct tcphdr);
+
+	ptr = (unsigned char *)(th + 1);
+	opt_rx->saw_tstamp = 0;
+
+	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 */
+	  			switch(opcode) {
+				case TCPOPT_MSS:
+					if(opsize==TCPOLEN_MSS && th->syn && !estab) {
+						u16 in_mss = ntohs(get_unaligned((__u16 *)ptr));
+						if (in_mss) {
+							if (opt_rx->user_mss && opt_rx->user_mss < in_mss)
+								in_mss = opt_rx->user_mss;
+							opt_rx->mss_clamp = in_mss;
+						}
+					}
+					break;
+				case TCPOPT_WINDOW:
+					if(opsize==TCPOLEN_WINDOW && th->syn && !estab)
+						if (sysctl_tcp_window_scaling) {
+							__u8 snd_wscale = *(__u8 *) ptr;
+							opt_rx->wscale_ok = 1;
+							if (snd_wscale > 14) {
+								if(net_ratelimit())
+									printk(KERN_INFO "tcp_parse_options: Illegal window "
+									       "scaling value %d >14 received.\n",
+									       snd_wscale);
+								snd_wscale = 14;
+							}
+							opt_rx->snd_wscale = snd_wscale;
+						}
+					break;
+				case TCPOPT_TIMESTAMP:
+					if(opsize==TCPOLEN_TIMESTAMP) {
+						if ((estab && opt_rx->tstamp_ok) ||
+						    (!estab && sysctl_tcp_timestamps)) {
+							opt_rx->saw_tstamp = 1;
+							opt_rx->rcv_tsval = ntohl(get_unaligned((__u32 *)ptr));
+							opt_rx->rcv_tsecr = ntohl(get_unaligned((__u32 *)(ptr+4)));
+						}
+					}
+					break;
+				case TCPOPT_SACK_PERM:
+					if(opsize==TCPOLEN_SACK_PERM && th->syn && !estab) {
+						if (sysctl_tcp_sack) {
+							opt_rx->sack_ok = 1;
+							tcp_sack_reset(opt_rx);
+						}
+					}
+					break;
+
+				case TCPOPT_SACK:
+					if((opsize >= (TCPOLEN_SACK_BASE + TCPOLEN_SACK_PERBLOCK)) &&
+					   !((opsize - TCPOLEN_SACK_BASE) % TCPOLEN_SACK_PERBLOCK) &&
+					   opt_rx->sack_ok) {
+						TCP_SKB_CB(skb)->sacked = (ptr - 2) - (unsigned char *)th;
+					}
+	  			};
+	  			ptr+=opsize-2;
+	  			length-=opsize;
+	  	};
+	}
+}
+
+/* Fast parse options. This hopes to only see timestamps.
+ * If it is wrong it falls back on tcp_parse_options().
+ */
+static inline int tcp_fast_parse_options(struct sk_buff *skb, struct tcphdr *th,
+					 struct tcp_sock *tp)
+{
+	if (th->doff == sizeof(struct tcphdr)>>2) {
+		tp->rx_opt.saw_tstamp = 0;
+		return 0;
+	} else if (tp->rx_opt.tstamp_ok &&
+		   th->doff == (sizeof(struct tcphdr)>>2)+(TCPOLEN_TSTAMP_ALIGNED>>2)) {
+		__u32 *ptr = (__u32 *)(th + 1);
+		if (*ptr == ntohl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16)
+				  | (TCPOPT_TIMESTAMP << 8) | TCPOLEN_TIMESTAMP)) {
+			tp->rx_opt.saw_tstamp = 1;
+			++ptr;
+			tp->rx_opt.rcv_tsval = ntohl(*ptr);
+			++ptr;
+			tp->rx_opt.rcv_tsecr = ntohl(*ptr);
+			return 1;
+		}
+	}
+	tcp_parse_options(skb, &tp->rx_opt, 1);
+	return 1;
+}
+
+static inline void tcp_store_ts_recent(struct tcp_sock *tp)
+{
+	tp->rx_opt.ts_recent = tp->rx_opt.rcv_tsval;
+	tp->rx_opt.ts_recent_stamp = xtime.tv_sec;
+}
+
+static inline void tcp_replace_ts_recent(struct tcp_sock *tp, u32 seq)
+{
+	if (tp->rx_opt.saw_tstamp && !after(seq, tp->rcv_wup)) {
+		/* PAWS bug workaround wrt. ACK frames, the PAWS discard
+		 * extra check below makes sure this can only happen
+		 * for pure ACK frames.  -DaveM
+		 *
+		 * Not only, also it occurs for expired timestamps.
+		 */
+
+		if((s32)(tp->rx_opt.rcv_tsval - tp->rx_opt.ts_recent) >= 0 ||
+		   xtime.tv_sec >= tp->rx_opt.ts_recent_stamp + TCP_PAWS_24DAYS)
+			tcp_store_ts_recent(tp);
+	}
+}
+
+/* Sorry, PAWS as specified is broken wrt. pure-ACKs -DaveM
+ *
+ * It is not fatal. If this ACK does _not_ change critical state (seqs, window)
+ * it can pass through stack. So, the following predicate verifies that
+ * this segment is not used for anything but congestion avoidance or
+ * fast retransmit. Moreover, we even are able to eliminate most of such
+ * second order effects, if we apply some small "replay" window (~RTO)
+ * to timestamp space.
+ *
+ * All these measures still do not guarantee that we reject wrapped ACKs
+ * on networks with high bandwidth, when sequence space is recycled fastly,
+ * but it guarantees that such events will be very rare and do not affect
+ * connection seriously. This doesn't look nice, but alas, PAWS is really
+ * buggy extension.
+ *
+ * [ Later note. Even worse! It is buggy for segments _with_ data. RFC
+ * states that events when retransmit arrives after original data are rare.
+ * It is a blatant lie. VJ forgot about fast retransmit! 8)8) It is
+ * the biggest problem on large power networks even with minor reordering.
+ * OK, let's give it small replay window. If peer clock is even 1hz, it is safe
+ * up to bandwidth of 18Gigabit/sec. 8) ]
+ */
+
+static int tcp_disordered_ack(struct tcp_sock *tp, struct sk_buff *skb)
+{
+	struct tcphdr *th = skb->h.th;
+	u32 seq = TCP_SKB_CB(skb)->seq;
+	u32 ack = TCP_SKB_CB(skb)->ack_seq;
+
+	return (/* 1. Pure ACK with correct sequence number. */
+		(th->ack && seq == TCP_SKB_CB(skb)->end_seq && seq == tp->rcv_nxt) &&
+
+		/* 2. ... and duplicate ACK. */
+		ack == tp->snd_una &&
+
+		/* 3. ... and does not update window. */
+		!tcp_may_update_window(tp, ack, seq, ntohs(th->window) << tp->rx_opt.snd_wscale) &&
+
+		/* 4. ... and sits in replay window. */
+		(s32)(tp->rx_opt.ts_recent - tp->rx_opt.rcv_tsval) <= (tp->rto*1024)/HZ);
+}
+
+static inline int tcp_paws_discard(struct tcp_sock *tp, struct sk_buff *skb)
+{
+	return ((s32)(tp->rx_opt.ts_recent - tp->rx_opt.rcv_tsval) > TCP_PAWS_WINDOW &&
+		xtime.tv_sec < tp->rx_opt.ts_recent_stamp + TCP_PAWS_24DAYS &&
+		!tcp_disordered_ack(tp, skb));
+}
+
+/* Check segment sequence number for validity.
+ *
+ * Segment controls are considered valid, if the segment
+ * fits to the window after truncation to the window. Acceptability
+ * of data (and SYN, FIN, of course) is checked separately.
+ * See tcp_data_queue(), for example.
+ *
+ * Also, controls (RST is main one) are accepted using RCV.WUP instead
+ * of RCV.NXT. Peer still did not advance his SND.UNA when we
+ * delayed ACK, so that hisSND.UNA<=ourRCV.WUP.
+ * (borrowed from freebsd)
+ */
+
+static inline int tcp_sequence(struct tcp_sock *tp, u32 seq, u32 end_seq)
+{
+	return	!before(end_seq, tp->rcv_wup) &&
+		!after(seq, tp->rcv_nxt + tcp_receive_window(tp));
+}
+
+/* When we get a reset we do this. */
+static void tcp_reset(struct sock *sk)
+{
+	/* We want the right error as BSD sees it (and indeed as we do). */
+	switch (sk->sk_state) {
+		case TCP_SYN_SENT:
+			sk->sk_err = ECONNREFUSED;
+			break;
+		case TCP_CLOSE_WAIT:
+			sk->sk_err = EPIPE;
+			break;
+		case TCP_CLOSE:
+			return;
+		default:
+			sk->sk_err = ECONNRESET;
+	}
+
+	if (!sock_flag(sk, SOCK_DEAD))
+		sk->sk_error_report(sk);
+
+	tcp_done(sk);
+}
+
+/*
+ * 	Process the FIN bit. This now behaves as it is supposed to work
+ *	and the FIN takes effect when it is validly part of sequence
+ *	space. Not before when we get holes.
+ *
+ *	If we are ESTABLISHED, a received fin moves us to CLOSE-WAIT
+ *	(and thence onto LAST-ACK and finally, CLOSE, we never enter
+ *	TIME-WAIT)
+ *
+ *	If we are in FINWAIT-1, a received FIN indicates simultaneous
+ *	close and we go into CLOSING (and later onto TIME-WAIT)
+ *
+ *	If we are in FINWAIT-2, a received FIN moves us to TIME-WAIT.
+ */
+static void tcp_fin(struct sk_buff *skb, struct sock *sk, struct tcphdr *th)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	tcp_schedule_ack(tp);
+
+	sk->sk_shutdown |= RCV_SHUTDOWN;
+	sock_set_flag(sk, SOCK_DONE);
+
+	switch (sk->sk_state) {
+		case TCP_SYN_RECV:
+		case TCP_ESTABLISHED:
+			/* Move to CLOSE_WAIT */
+			tcp_set_state(sk, TCP_CLOSE_WAIT);
+			tp->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(sk, TCP_CLOSING);
+			break;
+		case TCP_FIN_WAIT2:
+			/* Received a FIN -- send ACK and enter TIME_WAIT. */
+			tcp_send_ack(sk);
+			tcp_time_wait(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.
+			 */
+			printk(KERN_ERR "%s: Impossible, sk->sk_state=%d\n",
+			       __FUNCTION__, 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.
+	 */
+	__skb_queue_purge(&tp->out_of_order_queue);
+	if (tp->rx_opt.sack_ok)
+		tcp_sack_reset(&tp->rx_opt);
+	sk_stream_mem_reclaim(sk);
+
+	if (!sock_flag(sk, SOCK_DEAD)) {
+		sk->sk_state_change(sk);
+
+		/* Do not send POLL_HUP for half duplex close. */
+		if (sk->sk_shutdown == SHUTDOWN_MASK ||
+		    sk->sk_state == TCP_CLOSE)
+			sk_wake_async(sk, 1, POLL_HUP);
+		else
+			sk_wake_async(sk, 1, POLL_IN);
+	}
+}
+
+static __inline__ int
+tcp_sack_extend(struct tcp_sack_block *sp, u32 seq, u32 end_seq)
+{
+	if (!after(seq, sp->end_seq) && !after(sp->start_seq, end_seq)) {
+		if (before(seq, sp->start_seq))
+			sp->start_seq = seq;
+		if (after(end_seq, sp->end_seq))
+			sp->end_seq = end_seq;
+		return 1;
+	}
+	return 0;
+}
+
+static inline void tcp_dsack_set(struct tcp_sock *tp, u32 seq, u32 end_seq)
+{
+	if (tp->rx_opt.sack_ok && sysctl_tcp_dsack) {
+		if (before(seq, tp->rcv_nxt))
+			NET_INC_STATS_BH(LINUX_MIB_TCPDSACKOLDSENT);
+		else
+			NET_INC_STATS_BH(LINUX_MIB_TCPDSACKOFOSENT);
+
+		tp->rx_opt.dsack = 1;
+		tp->duplicate_sack[0].start_seq = seq;
+		tp->duplicate_sack[0].end_seq = end_seq;
+		tp->rx_opt.eff_sacks = min(tp->rx_opt.num_sacks + 1, 4 - tp->rx_opt.tstamp_ok);
+	}
+}
+
+static inline void tcp_dsack_extend(struct tcp_sock *tp, u32 seq, u32 end_seq)
+{
+	if (!tp->rx_opt.dsack)
+		tcp_dsack_set(tp, seq, end_seq);
+	else
+		tcp_sack_extend(tp->duplicate_sack, seq, end_seq);
+}
+
+static void tcp_send_dupack(struct sock *sk, struct sk_buff *skb)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	if (TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq &&
+	    before(TCP_SKB_CB(skb)->seq, tp->rcv_nxt)) {
+		NET_INC_STATS_BH(LINUX_MIB_DELAYEDACKLOST);
+		tcp_enter_quickack_mode(tp);
+
+		if (tp->rx_opt.sack_ok && sysctl_tcp_dsack) {
+			u32 end_seq = TCP_SKB_CB(skb)->end_seq;
+
+			if (after(TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt))
+				end_seq = tp->rcv_nxt;
+			tcp_dsack_set(tp, TCP_SKB_CB(skb)->seq, end_seq);
+		}
+	}
+
+	tcp_send_ack(sk);
+}
+
+/* These routines update the SACK block as out-of-order packets arrive or
+ * in-order packets close up the sequence space.
+ */
+static void tcp_sack_maybe_coalesce(struct tcp_sock *tp)
+{
+	int this_sack;
+	struct tcp_sack_block *sp = &tp->selective_acks[0];
+	struct tcp_sack_block *swalk = sp+1;
+
+	/* See if the recent change to the first SACK eats into
+	 * or hits the sequence space of other SACK blocks, if so coalesce.
+	 */
+	for (this_sack = 1; this_sack < tp->rx_opt.num_sacks; ) {
+		if (tcp_sack_extend(sp, swalk->start_seq, swalk->end_seq)) {
+			int i;
+
+			/* Zap SWALK, by moving every further SACK up by one slot.
+			 * Decrease num_sacks.
+			 */
+			tp->rx_opt.num_sacks--;
+			tp->rx_opt.eff_sacks = min(tp->rx_opt.num_sacks + tp->rx_opt.dsack, 4 - tp->rx_opt.tstamp_ok);
+			for(i=this_sack; i < tp->rx_opt.num_sacks; i++)
+				sp[i] = sp[i+1];
+			continue;
+		}
+		this_sack++, swalk++;
+	}
+}
+
+static __inline__ void tcp_sack_swap(struct tcp_sack_block *sack1, struct tcp_sack_block *sack2)
+{
+	__u32 tmp;
+
+	tmp = sack1->start_seq;
+	sack1->start_seq = sack2->start_seq;
+	sack2->start_seq = tmp;
+
+	tmp = sack1->end_seq;
+	sack1->end_seq = sack2->end_seq;
+	sack2->end_seq = tmp;
+}
+
+static void tcp_sack_new_ofo_skb(struct sock *sk, u32 seq, u32 end_seq)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct tcp_sack_block *sp = &tp->selective_acks[0];
+	int cur_sacks = tp->rx_opt.num_sacks;
+	int this_sack;
+
+	if (!cur_sacks)
+		goto new_sack;
+
+	for (this_sack=0; this_sack<cur_sacks; this_sack++, sp++) {
+		if (tcp_sack_extend(sp, seq, end_seq)) {
+			/* Rotate this_sack to the first one. */
+			for (; this_sack>0; this_sack--, sp--)
+				tcp_sack_swap(sp, sp-1);
+			if (cur_sacks > 1)
+				tcp_sack_maybe_coalesce(tp);
+			return;
+		}
+	}
+
+	/* Could not find an adjacent existing SACK, build a new one,
+	 * put it at the front, and shift everyone else down.  We
+	 * always know there is at least one SACK present already here.
+	 *
+	 * If the sack array is full, forget about the last one.
+	 */
+	if (this_sack >= 4) {
+		this_sack--;
+		tp->rx_opt.num_sacks--;
+		sp--;
+	}
+	for(; this_sack > 0; this_sack--, sp--)
+		*sp = *(sp-1);
+
+new_sack:
+	/* Build the new head SACK, and we're done. */
+	sp->start_seq = seq;
+	sp->end_seq = end_seq;
+	tp->rx_opt.num_sacks++;
+	tp->rx_opt.eff_sacks = min(tp->rx_opt.num_sacks + tp->rx_opt.dsack, 4 - tp->rx_opt.tstamp_ok);
+}
+
+/* RCV.NXT advances, some SACKs should be eaten. */
+
+static void tcp_sack_remove(struct tcp_sock *tp)
+{
+	struct tcp_sack_block *sp = &tp->selective_acks[0];
+	int num_sacks = tp->rx_opt.num_sacks;
+	int this_sack;
+
+	/* Empty ofo queue, hence, all the SACKs are eaten. Clear. */
+	if (skb_queue_len(&tp->out_of_order_queue) == 0) {
+		tp->rx_opt.num_sacks = 0;
+		tp->rx_opt.eff_sacks = tp->rx_opt.dsack;
+		return;
+	}
+
+	for(this_sack = 0; this_sack < num_sacks; ) {
+		/* Check if the start of the sack is covered by RCV.NXT. */
+		if (!before(tp->rcv_nxt, sp->start_seq)) {
+			int i;
+
+			/* RCV.NXT must cover all the block! */
+			BUG_TRAP(!before(tp->rcv_nxt, sp->end_seq));
+
+			/* Zap this SACK, by moving forward any other SACKS. */
+			for (i=this_sack+1; i < num_sacks; i++)
+				tp->selective_acks[i-1] = tp->selective_acks[i];
+			num_sacks--;
+			continue;
+		}
+		this_sack++;
+		sp++;
+	}
+	if (num_sacks != tp->rx_opt.num_sacks) {
+		tp->rx_opt.num_sacks = num_sacks;
+		tp->rx_opt.eff_sacks = min(tp->rx_opt.num_sacks + tp->rx_opt.dsack, 4 - tp->rx_opt.tstamp_ok);
+	}
+}
+
+/* This one checks to see if we can put data from the
+ * out_of_order queue into the receive_queue.
+ */
+static void tcp_ofo_queue(struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	__u32 dsack_high = tp->rcv_nxt;
+	struct sk_buff *skb;
+
+	while ((skb = skb_peek(&tp->out_of_order_queue)) != NULL) {
+		if (after(TCP_SKB_CB(skb)->seq, tp->rcv_nxt))
+			break;
+
+		if (before(TCP_SKB_CB(skb)->seq, dsack_high)) {
+			__u32 dsack = dsack_high;
+			if (before(TCP_SKB_CB(skb)->end_seq, dsack_high))
+				dsack_high = TCP_SKB_CB(skb)->end_seq;
+			tcp_dsack_extend(tp, TCP_SKB_CB(skb)->seq, dsack);
+		}
+
+		if (!after(TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt)) {
+			SOCK_DEBUG(sk, "ofo packet was already received \n");
+			__skb_unlink(skb, skb->list);
+			__kfree_skb(skb);
+			continue;
+		}
+		SOCK_DEBUG(sk, "ofo requeuing : rcv_next %X seq %X - %X\n",
+			   tp->rcv_nxt, TCP_SKB_CB(skb)->seq,
+			   TCP_SKB_CB(skb)->end_seq);
+
+		__skb_unlink(skb, skb->list);
+		__skb_queue_tail(&sk->sk_receive_queue, skb);
+		tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
+		if(skb->h.th->fin)
+			tcp_fin(skb, sk, skb->h.th);
+	}
+}
+
+static int tcp_prune_queue(struct sock *sk);
+
+static void tcp_data_queue(struct sock *sk, struct sk_buff *skb)
+{
+	struct tcphdr *th = skb->h.th;
+	struct tcp_sock *tp = tcp_sk(sk);
+	int eaten = -1;
+
+	if (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq)
+		goto drop;
+
+	th = skb->h.th;
+	__skb_pull(skb, th->doff*4);
+
+	TCP_ECN_accept_cwr(tp, skb);
+
+	if (tp->rx_opt.dsack) {
+		tp->rx_opt.dsack = 0;
+		tp->rx_opt.eff_sacks = min_t(unsigned int, tp->rx_opt.num_sacks,
+						    4 - tp->rx_opt.tstamp_ok);
+	}
+
+	/*  Queue data for delivery to the user.
+	 *  Packets in sequence go to the receive queue.
+	 *  Out of sequence packets to the out_of_order_queue.
+	 */
+	if (TCP_SKB_CB(skb)->seq == tp->rcv_nxt) {
+		if (tcp_receive_window(tp) == 0)
+			goto out_of_window;
+
+		/* Ok. In sequence. In window. */
+		if (tp->ucopy.task == current &&
+		    tp->copied_seq == tp->rcv_nxt && tp->ucopy.len &&
+		    sock_owned_by_user(sk) && !tp->urg_data) {
+			int chunk = min_t(unsigned int, skb->len,
+							tp->ucopy.len);
+
+			__set_current_state(TASK_RUNNING);
+
+			local_bh_enable();
+			if (!skb_copy_datagram_iovec(skb, 0, tp->ucopy.iov, chunk)) {
+				tp->ucopy.len -= chunk;
+				tp->copied_seq += chunk;
+				eaten = (chunk == skb->len && !th->fin);
+				tcp_rcv_space_adjust(sk);
+			}
+			local_bh_disable();
+		}
+
+		if (eaten <= 0) {
+queue_and_out:
+			if (eaten < 0 &&
+			    (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
+			     !sk_stream_rmem_schedule(sk, skb))) {
+				if (tcp_prune_queue(sk) < 0 ||
+				    !sk_stream_rmem_schedule(sk, skb))
+					goto drop;
+			}
+			sk_stream_set_owner_r(skb, sk);
+			__skb_queue_tail(&sk->sk_receive_queue, skb);
+		}
+		tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
+		if(skb->len)
+			tcp_event_data_recv(sk, tp, skb);
+		if(th->fin)
+			tcp_fin(skb, sk, th);
+
+		if (skb_queue_len(&tp->out_of_order_queue)) {
+			tcp_ofo_queue(sk);
+
+			/* RFC2581. 4.2. SHOULD send immediate ACK, when
+			 * gap in queue is filled.
+			 */
+			if (!skb_queue_len(&tp->out_of_order_queue))
+				tp->ack.pingpong = 0;
+		}
+
+		if (tp->rx_opt.num_sacks)
+			tcp_sack_remove(tp);
+
+		tcp_fast_path_check(sk, tp);
+
+		if (eaten > 0)
+			__kfree_skb(skb);
+		else if (!sock_flag(sk, SOCK_DEAD))
+			sk->sk_data_ready(sk, 0);
+		return;
+	}
+
+	if (!after(TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt)) {
+		/* A retransmit, 2nd most common case.  Force an immediate ack. */
+		NET_INC_STATS_BH(LINUX_MIB_DELAYEDACKLOST);
+		tcp_dsack_set(tp, TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq);
+
+out_of_window:
+		tcp_enter_quickack_mode(tp);
+		tcp_schedule_ack(tp);
+drop:
+		__kfree_skb(skb);
+		return;
+	}
+
+	/* Out of window. F.e. zero window probe. */
+	if (!before(TCP_SKB_CB(skb)->seq, tp->rcv_nxt + tcp_receive_window(tp)))
+		goto out_of_window;
+
+	tcp_enter_quickack_mode(tp);
+
+	if (before(TCP_SKB_CB(skb)->seq, tp->rcv_nxt)) {
+		/* Partial packet, seq < rcv_next < end_seq */
+		SOCK_DEBUG(sk, "partial packet: rcv_next %X seq %X - %X\n",
+			   tp->rcv_nxt, TCP_SKB_CB(skb)->seq,
+			   TCP_SKB_CB(skb)->end_seq);
+
+		tcp_dsack_set(tp, TCP_SKB_CB(skb)->seq, tp->rcv_nxt);
+		
+		/* If window is closed, drop tail of packet. But after
+		 * remembering D-SACK for its head made in previous line.
+		 */
+		if (!tcp_receive_window(tp))
+			goto out_of_window;
+		goto queue_and_out;
+	}
+
+	TCP_ECN_check_ce(tp, skb);
+
+	if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf ||
+	    !sk_stream_rmem_schedule(sk, skb)) {
+		if (tcp_prune_queue(sk) < 0 ||
+		    !sk_stream_rmem_schedule(sk, skb))
+			goto drop;
+	}
+
+	/* Disable header prediction. */
+	tp->pred_flags = 0;
+	tcp_schedule_ack(tp);
+
+	SOCK_DEBUG(sk, "out of order segment: rcv_next %X seq %X - %X\n",
+		   tp->rcv_nxt, TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq);
+
+	sk_stream_set_owner_r(skb, sk);
+
+	if (!skb_peek(&tp->out_of_order_queue)) {
+		/* Initial out of order segment, build 1 SACK. */
+		if (tp->rx_opt.sack_ok) {
+			tp->rx_opt.num_sacks = 1;
+			tp->rx_opt.dsack     = 0;
+			tp->rx_opt.eff_sacks = 1;
+			tp->selective_acks[0].start_seq = TCP_SKB_CB(skb)->seq;
+			tp->selective_acks[0].end_seq =
+						TCP_SKB_CB(skb)->end_seq;
+		}
+		__skb_queue_head(&tp->out_of_order_queue,skb);
+	} else {
+		struct sk_buff *skb1 = tp->out_of_order_queue.prev;
+		u32 seq = TCP_SKB_CB(skb)->seq;
+		u32 end_seq = TCP_SKB_CB(skb)->end_seq;
+
+		if (seq == TCP_SKB_CB(skb1)->end_seq) {
+			__skb_append(skb1, skb);
+
+			if (!tp->rx_opt.num_sacks ||
+			    tp->selective_acks[0].end_seq != seq)
+				goto add_sack;
+
+			/* Common case: data arrive in order after hole. */
+			tp->selective_acks[0].end_seq = end_seq;
+			return;
+		}
+
+		/* Find place to insert this segment. */
+		do {
+			if (!after(TCP_SKB_CB(skb1)->seq, seq))
+				break;
+		} while ((skb1 = skb1->prev) !=
+			 (struct sk_buff*)&tp->out_of_order_queue);
+
+		/* Do skb overlap to previous one? */
+		if (skb1 != (struct sk_buff*)&tp->out_of_order_queue &&
+		    before(seq, TCP_SKB_CB(skb1)->end_seq)) {
+			if (!after(end_seq, TCP_SKB_CB(skb1)->end_seq)) {
+				/* All the bits are present. Drop. */
+				__kfree_skb(skb);
+				tcp_dsack_set(tp, seq, end_seq);
+				goto add_sack;
+			}
+			if (after(seq, TCP_SKB_CB(skb1)->seq)) {
+				/* Partial overlap. */
+				tcp_dsack_set(tp, seq, TCP_SKB_CB(skb1)->end_seq);
+			} else {
+				skb1 = skb1->prev;
+			}
+		}
+		__skb_insert(skb, skb1, skb1->next, &tp->out_of_order_queue);
+		
+		/* And clean segments covered by new one as whole. */
+		while ((skb1 = skb->next) !=
+		       (struct sk_buff*)&tp->out_of_order_queue &&
+		       after(end_seq, TCP_SKB_CB(skb1)->seq)) {
+		       if (before(end_seq, TCP_SKB_CB(skb1)->end_seq)) {
+			       tcp_dsack_extend(tp, TCP_SKB_CB(skb1)->seq, end_seq);
+			       break;
+		       }
+		       __skb_unlink(skb1, skb1->list);
+		       tcp_dsack_extend(tp, TCP_SKB_CB(skb1)->seq, TCP_SKB_CB(skb1)->end_seq);
+		       __kfree_skb(skb1);
+		}
+
+add_sack:
+		if (tp->rx_opt.sack_ok)
+			tcp_sack_new_ofo_skb(sk, seq, end_seq);
+	}
+}
+
+/* Collapse contiguous sequence of skbs head..tail with
+ * sequence numbers start..end.
+ * Segments with FIN/SYN are not collapsed (only because this
+ * simplifies code)
+ */
+static void
+tcp_collapse(struct sock *sk, struct sk_buff *head,
+	     struct sk_buff *tail, u32 start, u32 end)
+{
+	struct sk_buff *skb;
+
+	/* First, check that queue is collapsable and find
+	 * the point where collapsing can be useful. */
+	for (skb = head; skb != tail; ) {
+		/* No new bits? It is possible on ofo queue. */
+		if (!before(start, TCP_SKB_CB(skb)->end_seq)) {
+			struct sk_buff *next = skb->next;
+			__skb_unlink(skb, skb->list);
+			__kfree_skb(skb);
+			NET_INC_STATS_BH(LINUX_MIB_TCPRCVCOLLAPSED);
+			skb = next;
+			continue;
+		}
+
+		/* The first skb to collapse is:
+		 * - not SYN/FIN and
+		 * - bloated or contains data before "start" or
+		 *   overlaps to the next one.
+		 */
+		if (!skb->h.th->syn && !skb->h.th->fin &&
+		    (tcp_win_from_space(skb->truesize) > skb->len ||
+		     before(TCP_SKB_CB(skb)->seq, start) ||
+		     (skb->next != tail &&
+		      TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb->next)->seq)))
+			break;
+
+		/* Decided to skip this, advance start seq. */
+		start = TCP_SKB_CB(skb)->end_seq;
+		skb = skb->next;
+	}
+	if (skb == tail || skb->h.th->syn || skb->h.th->fin)
+		return;
+
+	while (before(start, end)) {
+		struct sk_buff *nskb;
+		int header = skb_headroom(skb);
+		int copy = SKB_MAX_ORDER(header, 0);
+
+		/* Too big header? This can happen with IPv6. */
+		if (copy < 0)
+			return;
+		if (end-start < copy)
+			copy = end-start;
+		nskb = alloc_skb(copy+header, GFP_ATOMIC);
+		if (!nskb)
+			return;
+		skb_reserve(nskb, header);
+		memcpy(nskb->head, skb->head, header);
+		nskb->nh.raw = nskb->head + (skb->nh.raw-skb->head);
+		nskb->h.raw = nskb->head + (skb->h.raw-skb->head);
+		nskb->mac.raw = nskb->head + (skb->mac.raw-skb->head);
+		memcpy(nskb->cb, skb->cb, sizeof(skb->cb));
+		TCP_SKB_CB(nskb)->seq = TCP_SKB_CB(nskb)->end_seq = start;
+		__skb_insert(nskb, skb->prev, skb, skb->list);
+		sk_stream_set_owner_r(nskb, sk);
+
+		/* Copy data, releasing collapsed skbs. */
+		while (copy > 0) {
+			int offset = start - TCP_SKB_CB(skb)->seq;
+			int size = TCP_SKB_CB(skb)->end_seq - start;
+
+			if (offset < 0) BUG();
+			if (size > 0) {
+				size = min(copy, size);
+				if (skb_copy_bits(skb, offset, skb_put(nskb, size), size))
+					BUG();
+				TCP_SKB_CB(nskb)->end_seq += size;
+				copy -= size;
+				start += size;
+			}
+			if (!before(start, TCP_SKB_CB(skb)->end_seq)) {
+				struct sk_buff *next = skb->next;
+				__skb_unlink(skb, skb->list);
+				__kfree_skb(skb);
+				NET_INC_STATS_BH(LINUX_MIB_TCPRCVCOLLAPSED);
+				skb = next;
+				if (skb == tail || skb->h.th->syn || skb->h.th->fin)
+					return;
+			}
+		}
+	}
+}
+
+/* Collapse ofo queue. Algorithm: select contiguous sequence of skbs
+ * and tcp_collapse() them until all the queue is collapsed.
+ */
+static void tcp_collapse_ofo_queue(struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct sk_buff *skb = skb_peek(&tp->out_of_order_queue);
+	struct sk_buff *head;
+	u32 start, end;
+
+	if (skb == NULL)
+		return;
+
+	start = TCP_SKB_CB(skb)->seq;
+	end = TCP_SKB_CB(skb)->end_seq;
+	head = skb;
+
+	for (;;) {
+		skb = skb->next;
+
+		/* Segment is terminated when we see gap or when
+		 * we are at the end of all the queue. */
+		if (skb == (struct sk_buff *)&tp->out_of_order_queue ||
+		    after(TCP_SKB_CB(skb)->seq, end) ||
+		    before(TCP_SKB_CB(skb)->end_seq, start)) {
+			tcp_collapse(sk, head, skb, start, end);
+			head = skb;
+			if (skb == (struct sk_buff *)&tp->out_of_order_queue)
+				break;
+			/* Start new segment */
+			start = TCP_SKB_CB(skb)->seq;
+			end = TCP_SKB_CB(skb)->end_seq;
+		} else {
+			if (before(TCP_SKB_CB(skb)->seq, start))
+				start = TCP_SKB_CB(skb)->seq;
+			if (after(TCP_SKB_CB(skb)->end_seq, end))
+				end = TCP_SKB_CB(skb)->end_seq;
+		}
+	}
+}
+
+/* Reduce allocated memory if we can, trying to get
+ * the socket within its memory limits again.
+ *
+ * Return less than zero if we should start dropping frames
+ * until the socket owning process reads some of the data
+ * to stabilize the situation.
+ */
+static int tcp_prune_queue(struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk); 
+
+	SOCK_DEBUG(sk, "prune_queue: c=%x\n", tp->copied_seq);
+
+	NET_INC_STATS_BH(LINUX_MIB_PRUNECALLED);
+
+	if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)
+		tcp_clamp_window(sk, tp);
+	else if (tcp_memory_pressure)
+		tp->rcv_ssthresh = min(tp->rcv_ssthresh, 4U * tp->advmss);
+
+	tcp_collapse_ofo_queue(sk);
+	tcp_collapse(sk, sk->sk_receive_queue.next,
+		     (struct sk_buff*)&sk->sk_receive_queue,
+		     tp->copied_seq, tp->rcv_nxt);
+	sk_stream_mem_reclaim(sk);
+
+	if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf)
+		return 0;
+
+	/* Collapsing did not help, destructive actions follow.
+	 * This must not ever occur. */
+
+	/* First, purge the out_of_order queue. */
+	if (skb_queue_len(&tp->out_of_order_queue)) {
+		NET_ADD_STATS_BH(LINUX_MIB_OFOPRUNED, 
+				 skb_queue_len(&tp->out_of_order_queue));
+		__skb_queue_purge(&tp->out_of_order_queue);
+
+		/* Reset SACK state.  A conforming SACK implementation will
+		 * do the same at a timeout based retransmit.  When a connection
+		 * is in a sad state like this, we care only about integrity
+		 * of the connection not performance.
+		 */
+		if (tp->rx_opt.sack_ok)
+			tcp_sack_reset(&tp->rx_opt);
+		sk_stream_mem_reclaim(sk);
+	}
+
+	if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf)
+		return 0;
+
+	/* If we are really being abused, tell the caller to silently
+	 * drop receive data on the floor.  It will get retransmitted
+	 * and hopefully then we'll have sufficient space.
+	 */
+	NET_INC_STATS_BH(LINUX_MIB_RCVPRUNED);
+
+	/* Massive buffer overcommit. */
+	tp->pred_flags = 0;
+	return -1;
+}
+
+
+/* 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 (tp->ca_state == TCP_CA_Open &&
+	    sk->sk_socket && !test_bit(SOCK_NOSPACE, &sk->sk_socket->flags)) {
+		/* Limited by application or receiver window. */
+		u32 win_used = max(tp->snd_cwnd_used, 2U);
+		if (win_used < tp->snd_cwnd) {
+			tp->snd_ssthresh = tcp_current_ssthresh(tp);
+			tp->snd_cwnd = (tp->snd_cwnd + win_used) >> 1;
+		}
+		tp->snd_cwnd_used = 0;
+	}
+	tp->snd_cwnd_stamp = tcp_time_stamp;
+}
+
+
+/* When incoming ACK allowed to free some skb from write_queue,
+ * we remember this event in flag SOCK_QUEUE_SHRUNK and wake up socket
+ * on the exit from tcp input handler.
+ *
+ * PROBLEM: sndbuf expansion does not work well with largesend.
+ */
+static void tcp_new_space(struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	if (tp->packets_out < tp->snd_cwnd &&
+	    !(sk->sk_userlocks & SOCK_SNDBUF_LOCK) &&
+	    !tcp_memory_pressure &&
+	    atomic_read(&tcp_memory_allocated) < sysctl_tcp_mem[0]) {
+ 		int sndmem = max_t(u32, tp->rx_opt.mss_clamp, tp->mss_cache_std) +
+			MAX_TCP_HEADER + 16 + sizeof(struct sk_buff),
+		    demanded = max_t(unsigned int, tp->snd_cwnd,
+						   tp->reordering + 1);
+		sndmem *= 2*demanded;
+		if (sndmem > sk->sk_sndbuf)
+			sk->sk_sndbuf = min(sndmem, sysctl_tcp_wmem[2]);
+		tp->snd_cwnd_stamp = tcp_time_stamp;
+	}
+
+	sk->sk_write_space(sk);
+}
+
+static inline 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))
+			tcp_new_space(sk);
+	}
+}
+
+static void __tcp_data_snd_check(struct sock *sk, struct sk_buff *skb)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	if (after(TCP_SKB_CB(skb)->end_seq, tp->snd_una + tp->snd_wnd) ||
+	    tcp_packets_in_flight(tp) >= tp->snd_cwnd ||
+	    tcp_write_xmit(sk, tp->nonagle))
+		tcp_check_probe_timer(sk, tp);
+}
+
+static __inline__ void tcp_data_snd_check(struct sock *sk)
+{
+	struct sk_buff *skb = sk->sk_send_head;
+
+	if (skb != NULL)
+		__tcp_data_snd_check(sk, skb);
+	tcp_check_space(sk);
+}
+
+/*
+ * Check if sending an ack is needed.
+ */
+static void __tcp_ack_snd_check(struct sock *sk, int ofo_possible)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	    /* More than one full frame received... */
+	if (((tp->rcv_nxt - tp->rcv_wup) > tp->ack.rcv_mss
+	     /* ... and right edge of window advances far enough.
+	      * (tcp_recvmsg() will send ACK otherwise). Or...
+	      */
+	     && __tcp_select_window(sk) >= tp->rcv_wnd) ||
+	    /* We ACK each frame or... */
+	    tcp_in_quickack_mode(tp) ||
+	    /* We have out of order data. */
+	    (ofo_possible &&
+	     skb_peek(&tp->out_of_order_queue))) {
+		/* Then ack it now */
+		tcp_send_ack(sk);
+	} else {
+		/* Else, send delayed ack. */
+		tcp_send_delayed_ack(sk);
+	}
+}
+
+static __inline__ void tcp_ack_snd_check(struct sock *sk)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	if (!tcp_ack_scheduled(tp)) {
+		/* We sent a data segment already. */
+		return;
+	}
+	__tcp_ack_snd_check(sk, 1);
+}
+
+/*
+ *	This routine is only called when we have urgent data
+ *	signalled. Its the 'slow' part of tcp_urg. It could be
+ *	moved inline now as tcp_urg is only called from one
+ *	place. We handle URGent data wrong. We have to - as
+ *	BSD still doesn't use the correction from RFC961.
+ *	For 1003.1g we should support a new option TCP_STDURG to permit
+ *	either form (or just set the sysctl tcp_stdurg).
+ */
+ 
+static void tcp_check_urg(struct sock * sk, struct tcphdr * th)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	u32 ptr = ntohs(th->urg_ptr);
+
+	if (ptr && !sysctl_tcp_stdurg)
+		ptr--;
+	ptr += ntohl(th->seq);
+
+	/* Ignore urgent data that we've already seen and read. */
+	if (after(tp->copied_seq, ptr))
+		return;
+
+	/* Do not replay urg ptr.
+	 *
+	 * NOTE: interesting situation not covered by specs.
+	 * Misbehaving sender may send urg ptr, pointing to segment,
+	 * which we already have in ofo queue. We are not able to fetch
+	 * such data and will stay in TCP_URG_NOTYET until will be eaten
+	 * by recvmsg(). Seems, we are not obliged to handle such wicked
+	 * situations. But it is worth to think about possibility of some
+	 * DoSes using some hypothetical application level deadlock.
+	 */
+	if (before(ptr, tp->rcv_nxt))
+		return;
+
+	/* Do we already have a newer (or duplicate) urgent pointer? */
+	if (tp->urg_data && !after(ptr, tp->urg_seq))
+		return;
+
+	/* Tell the world about our new urgent pointer. */
+	sk_send_sigurg(sk);
+
+	/* We may be adding urgent data when the last byte read was
+	 * urgent. To do this requires some care. We cannot just ignore
+	 * tp->copied_seq since we would read the last urgent byte again
+	 * as data, nor can we alter copied_seq until this data arrives
+	 * or we break the sematics of SIOCATMARK (and thus sockatmark())
+	 *
+	 * NOTE. Double Dutch. Rendering to plain English: author of comment
+	 * above did something sort of 	send("A", MSG_OOB); send("B", MSG_OOB);
+	 * and expect that both A and B disappear from stream. This is _wrong_.
+	 * Though this happens in BSD with high probability, this is occasional.
+	 * Any application relying on this is buggy. Note also, that fix "works"
+	 * only in this artificial test. Insert some normal data between A and B and we will
+	 * decline of BSD again. Verdict: it is better to remove to trap
+	 * buggy users.
+	 */
+	if (tp->urg_seq == tp->copied_seq && tp->urg_data &&
+	    !sock_flag(sk, SOCK_URGINLINE) &&
+	    tp->copied_seq != tp->rcv_nxt) {
+		struct sk_buff *skb = skb_peek(&sk->sk_receive_queue);
+		tp->copied_seq++;
+		if (skb && !before(tp->copied_seq, TCP_SKB_CB(skb)->end_seq)) {
+			__skb_unlink(skb, skb->list);
+			__kfree_skb(skb);
+		}
+	}
+
+	tp->urg_data   = TCP_URG_NOTYET;
+	tp->urg_seq    = ptr;
+
+	/* Disable header prediction. */
+	tp->pred_flags = 0;
+}
+
+/* This is the 'fast' part of urgent handling. */
+static void tcp_urg(struct sock *sk, struct sk_buff *skb, struct tcphdr *th)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	/* Check if we get a new urgent pointer - normally not. */
+	if (th->urg)
+		tcp_check_urg(sk,th);
+
+	/* Do we wait for any urgent data? - normally not... */
+	if (tp->urg_data == TCP_URG_NOTYET) {
+		u32 ptr = tp->urg_seq - ntohl(th->seq) + (th->doff * 4) -
+			  th->syn;
+
+		/* Is the urgent pointer pointing into this packet? */	 
+		if (ptr < skb->len) {
+			u8 tmp;
+			if (skb_copy_bits(skb, ptr, &tmp, 1))
+				BUG();
+			tp->urg_data = TCP_URG_VALID | tmp;
+			if (!sock_flag(sk, SOCK_DEAD))
+				sk->sk_data_ready(sk, 0);
+		}
+	}
+}
+
+static int tcp_copy_to_iovec(struct sock *sk, struct sk_buff *skb, int hlen)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	int chunk = skb->len - hlen;
+	int err;
+
+	local_bh_enable();
+	if (skb->ip_summed==CHECKSUM_UNNECESSARY)
+		err = skb_copy_datagram_iovec(skb, hlen, tp->ucopy.iov, chunk);
+	else
+		err = skb_copy_and_csum_datagram_iovec(skb, hlen,
+						       tp->ucopy.iov);
+
+	if (!err) {
+		tp->ucopy.len -= chunk;
+		tp->copied_seq += chunk;
+		tcp_rcv_space_adjust(sk);
+	}
+
+	local_bh_disable();
+	return err;
+}
+
+static int __tcp_checksum_complete_user(struct sock *sk, struct sk_buff *skb)
+{
+	int result;
+
+	if (sock_owned_by_user(sk)) {
+		local_bh_enable();
+		result = __tcp_checksum_complete(skb);
+		local_bh_disable();
+	} else {
+		result = __tcp_checksum_complete(skb);
+	}
+	return result;
+}
+
+static __inline__ int
+tcp_checksum_complete_user(struct sock *sk, struct sk_buff *skb)
+{
+	return skb->ip_summed != CHECKSUM_UNNECESSARY &&
+		__tcp_checksum_complete_user(sk, skb);
+}
+
+/*
+ *	TCP receive function for the ESTABLISHED state. 
+ *
+ *	It is split into a fast path and a slow path. The fast path is 
+ * 	disabled when:
+ *	- A zero window was announced from us - zero window probing
+ *        is only handled properly in the slow path. 
+ *	- Out of order segments arrived.
+ *	- Urgent data is expected.
+ *	- There is no buffer space left
+ *	- Unexpected TCP flags/window values/header lengths are received
+ *	  (detected by checking the TCP header against pred_flags) 
+ *	- Data is sent in both directions. Fast path only supports pure senders
+ *	  or pure receivers (this means either the sequence number or the ack
+ *	  value must stay constant)
+ *	- Unexpected TCP option.
+ *
+ *	When these conditions are not satisfied it drops into a standard 
+ *	receive procedure patterned after RFC793 to handle all cases.
+ *	The first three cases are guaranteed by proper pred_flags setting,
+ *	the rest is checked inline. Fast processing is turned on in 
+ *	tcp_data_queue when everything is OK.
+ */
+int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
+			struct tcphdr *th, unsigned len)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	/*
+	 *	Header prediction.
+	 *	The code loosely follows the one in the famous 
+	 *	"30 instruction TCP receive" Van Jacobson mail.
+	 *	
+	 *	Van's trick is to deposit buffers into socket queue 
+	 *	on a device interrupt, to call tcp_recv function
+	 *	on the receive process context and checksum and copy
+	 *	the buffer to user space. smart...
+	 *
+	 *	Our current scheme is not silly either but we take the 
+	 *	extra cost of the net_bh soft interrupt processing...
+	 *	We do checksum and copy also but from device to kernel.
+	 */
+
+	tp->rx_opt.saw_tstamp = 0;
+
+	/*	pred_flags is 0xS?10 << 16 + snd_wnd
+	 *	if header_predition is to be made
+	 *	'S' will always be tp->tcp_header_len >> 2
+	 *	'?' will be 0 for the fast path, otherwise pred_flags is 0 to
+	 *  turn it off	(when there are holes in the receive 
+	 *	 space for instance)
+	 *	PSH flag is ignored.
+	 */
+
+	if ((tcp_flag_word(th) & TCP_HP_BITS) == tp->pred_flags &&
+		TCP_SKB_CB(skb)->seq == tp->rcv_nxt) {
+		int tcp_header_len = tp->tcp_header_len;
+
+		/* Timestamp header prediction: tcp_header_len
+		 * is automatically equal to th->doff*4 due to pred_flags
+		 * match.
+		 */
+
+		/* Check timestamp */
+		if (tcp_header_len == sizeof(struct tcphdr) + TCPOLEN_TSTAMP_ALIGNED) {
+			__u32 *ptr = (__u32 *)(th + 1);
+
+			/* No? Slow path! */
+			if (*ptr != ntohl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16)
+					  | (TCPOPT_TIMESTAMP << 8) | TCPOLEN_TIMESTAMP))
+				goto slow_path;
+
+			tp->rx_opt.saw_tstamp = 1;
+			++ptr; 
+			tp->rx_opt.rcv_tsval = ntohl(*ptr);
+			++ptr;
+			tp->rx_opt.rcv_tsecr = ntohl(*ptr);
+
+			/* If PAWS failed, check it more carefully in slow path */
+			if ((s32)(tp->rx_opt.rcv_tsval - tp->rx_opt.ts_recent) < 0)
+				goto slow_path;
+
+			/* DO NOT update ts_recent here, if checksum fails
+			 * and timestamp was corrupted part, it will result
+			 * in a hung connection since we will drop all
+			 * future packets due to the PAWS test.
+			 */
+		}
+
+		if (len <= tcp_header_len) {
+			/* Bulk data transfer: sender */
+			if (len == tcp_header_len) {
+				/* Predicted packet is in window by definition.
+				 * seq == rcv_nxt and rcv_wup <= rcv_nxt.
+				 * Hence, check seq<=rcv_wup reduces to:
+				 */
+				if (tcp_header_len ==
+				    (sizeof(struct tcphdr) + TCPOLEN_TSTAMP_ALIGNED) &&
+				    tp->rcv_nxt == tp->rcv_wup)
+					tcp_store_ts_recent(tp);
+
+				tcp_rcv_rtt_measure_ts(tp, skb);
+
+				/* We know that such packets are checksummed
+				 * on entry.
+				 */
+				tcp_ack(sk, skb, 0);
+				__kfree_skb(skb); 
+				tcp_data_snd_check(sk);
+				return 0;
+			} else { /* Header too small */
+				TCP_INC_STATS_BH(TCP_MIB_INERRS);
+				goto discard;
+			}
+		} else {
+			int eaten = 0;
+
+			if (tp->ucopy.task == current &&
+			    tp->copied_seq == tp->rcv_nxt &&
+			    len - tcp_header_len <= tp->ucopy.len &&
+			    sock_owned_by_user(sk)) {
+				__set_current_state(TASK_RUNNING);
+
+				if (!tcp_copy_to_iovec(sk, skb, tcp_header_len)) {
+					/* Predicted packet is in window by definition.
+					 * seq == rcv_nxt and rcv_wup <= rcv_nxt.
+					 * Hence, check seq<=rcv_wup reduces to:
+					 */
+					if (tcp_header_len ==
+					    (sizeof(struct tcphdr) +
+					     TCPOLEN_TSTAMP_ALIGNED) &&
+					    tp->rcv_nxt == tp->rcv_wup)
+						tcp_store_ts_recent(tp);
+
+					tcp_rcv_rtt_measure_ts(tp, skb);
+
+					__skb_pull(skb, tcp_header_len);
+					tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
+					NET_INC_STATS_BH(LINUX_MIB_TCPHPHITSTOUSER);
+					eaten = 1;
+				}
+			}
+			if (!eaten) {
+				if (tcp_checksum_complete_user(sk, skb))
+					goto csum_error;
+
+				/* Predicted packet is in window by definition.
+				 * seq == rcv_nxt and rcv_wup <= rcv_nxt.
+				 * Hence, check seq<=rcv_wup reduces to:
+				 */
+				if (tcp_header_len ==
+				    (sizeof(struct tcphdr) + TCPOLEN_TSTAMP_ALIGNED) &&
+				    tp->rcv_nxt == tp->rcv_wup)
+					tcp_store_ts_recent(tp);
+
+				tcp_rcv_rtt_measure_ts(tp, skb);
+
+				if ((int)skb->truesize > sk->sk_forward_alloc)
+					goto step5;
+
+				NET_INC_STATS_BH(LINUX_MIB_TCPHPHITS);
+
+				/* Bulk data transfer: receiver */
+				__skb_pull(skb,tcp_header_len);
+				__skb_queue_tail(&sk->sk_receive_queue, skb);
+				sk_stream_set_owner_r(skb, sk);
+				tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
+			}
+
+			tcp_event_data_recv(sk, tp, skb);
+
+			if (TCP_SKB_CB(skb)->ack_seq != tp->snd_una) {
+				/* Well, only one small jumplet in fast path... */
+				tcp_ack(sk, skb, FLAG_DATA);
+				tcp_data_snd_check(sk);
+				if (!tcp_ack_scheduled(tp))
+					goto no_ack;
+			}
+
+			if (eaten) {
+				if (tcp_in_quickack_mode(tp)) {
+					tcp_send_ack(sk);
+				} else {
+					tcp_send_delayed_ack(sk);
+				}
+			} else {
+				__tcp_ack_snd_check(sk, 0);
+			}
+
+no_ack:
+			if (eaten)
+				__kfree_skb(skb);
+			else
+				sk->sk_data_ready(sk, 0);
+			return 0;
+		}
+	}
+
+slow_path:
+	if (len < (th->doff<<2) || tcp_checksum_complete_user(sk, skb))
+		goto csum_error;
+
+	/*
+	 * RFC1323: H1. Apply PAWS check first.
+	 */
+	if (tcp_fast_parse_options(skb, th, tp) && tp->rx_opt.saw_tstamp &&
+	    tcp_paws_discard(tp, skb)) {
+		if (!th->rst) {
+			NET_INC_STATS_BH(LINUX_MIB_PAWSESTABREJECTED);
+			tcp_send_dupack(sk, skb);
+			goto discard;
+		}
+		/* Resets are accepted even if PAWS failed.
+
+		   ts_recent update must be made after we are sure
+		   that the packet is in window.
+		 */
+	}
+
+	/*
+	 *	Standard slow path.
+	 */
+
+	if (!tcp_sequence(tp, TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq)) {
+		/* RFC793, page 37: "In all states except SYN-SENT, all reset
+		 * (RST) segments are validated by checking their SEQ-fields."
+		 * And page 69: "If an incoming segment is not acceptable,
+		 * an acknowledgment should be sent in reply (unless the RST bit
+		 * is set, if so drop the segment and return)".
+		 */
+		if (!th->rst)
+			tcp_send_dupack(sk, skb);
+		goto discard;
+	}
+
+	if(th->rst) {
+		tcp_reset(sk);
+		goto discard;
+	}
+
+	tcp_replace_ts_recent(tp, TCP_SKB_CB(skb)->seq);
+
+	if (th->syn && !before(TCP_SKB_CB(skb)->seq, tp->rcv_nxt)) {
+		TCP_INC_STATS_BH(TCP_MIB_INERRS);
+		NET_INC_STATS_BH(LINUX_MIB_TCPABORTONSYN);
+		tcp_reset(sk);
+		return 1;
+	}
+
+step5:
+	if(th->ack)
+		tcp_ack(sk, skb, FLAG_SLOWPATH);
+
+	tcp_rcv_rtt_measure_ts(tp, skb);
+
+	/* Process urgent data. */
+	tcp_urg(sk, skb, th);
+
+	/* step 7: process the segment text */
+	tcp_data_queue(sk, skb);
+
+	tcp_data_snd_check(sk);
+	tcp_ack_snd_check(sk);
+	return 0;
+
+csum_error:
+	TCP_INC_STATS_BH(TCP_MIB_INERRS);
+
+discard:
+	__kfree_skb(skb);
+	return 0;
+}
+
+static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
+					 struct tcphdr *th, unsigned len)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	int saved_clamp = tp->rx_opt.mss_clamp;
+
+	tcp_parse_options(skb, &tp->rx_opt, 0);
+
+	if (th->ack) {
+		/* rfc793:
+		 * "If the state is SYN-SENT then
+		 *    first check the ACK bit
+		 *      If the ACK bit is set
+		 *	  If SEG.ACK =< ISS, or SEG.ACK > SND.NXT, send
+		 *        a reset (unless the RST bit is set, if so drop
+		 *        the segment and return)"
+		 *
+		 *  We do not send data with SYN, so that RFC-correct
+		 *  test reduces to:
+		 */
+		if (TCP_SKB_CB(skb)->ack_seq != tp->snd_nxt)
+			goto reset_and_undo;
+
+		if (tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr &&
+		    !between(tp->rx_opt.rcv_tsecr, tp->retrans_stamp,
+			     tcp_time_stamp)) {
+			NET_INC_STATS_BH(LINUX_MIB_PAWSACTIVEREJECTED);
+			goto reset_and_undo;
+		}
+
+		/* Now ACK is acceptable.
+		 *
+		 * "If the RST bit is set
+		 *    If the ACK was acceptable then signal the user "error:
+		 *    connection reset", drop the segment, enter CLOSED state,
+		 *    delete TCB, and return."
+		 */
+
+		if (th->rst) {
+			tcp_reset(sk);
+			goto discard;
+		}
+
+		/* rfc793:
+		 *   "fifth, if neither of the SYN or RST bits is set then
+		 *    drop the segment and return."
+		 *
+		 *    See note below!
+		 *                                        --ANK(990513)
+		 */
+		if (!th->syn)
+			goto discard_and_undo;
+
+		/* rfc793:
+		 *   "If the SYN bit is on ...
+		 *    are acceptable then ...
+		 *    (our SYN has been ACKed), change the connection
+		 *    state to ESTABLISHED..."
+		 */
+
+		TCP_ECN_rcv_synack(tp, th);
+		if (tp->ecn_flags&TCP_ECN_OK)
+			sock_set_flag(sk, SOCK_NO_LARGESEND);
+
+		tp->snd_wl1 = TCP_SKB_CB(skb)->seq;
+		tcp_ack(sk, skb, FLAG_SLOWPATH);
+
+		/* Ok.. it's good. Set up sequence numbers and
+		 * move to established.
+		 */
+		tp->rcv_nxt = TCP_SKB_CB(skb)->seq + 1;
+		tp->rcv_wup = TCP_SKB_CB(skb)->seq + 1;
+
+		/* RFC1323: The window in SYN & SYN/ACK segments is
+		 * never scaled.
+		 */
+		tp->snd_wnd = ntohs(th->window);
+		tcp_init_wl(tp, TCP_SKB_CB(skb)->ack_seq, TCP_SKB_CB(skb)->seq);
+
+		if (!tp->rx_opt.wscale_ok) {
+			tp->rx_opt.snd_wscale = tp->rx_opt.rcv_wscale = 0;
+			tp->window_clamp = min(tp->window_clamp, 65535U);
+		}
+
+		if (tp->rx_opt.saw_tstamp) {
+			tp->rx_opt.tstamp_ok	   = 1;
+			tp->tcp_header_len =
+				sizeof(struct tcphdr) + TCPOLEN_TSTAMP_ALIGNED;
+			tp->advmss	    -= TCPOLEN_TSTAMP_ALIGNED;
+			tcp_store_ts_recent(tp);
+		} else {
+			tp->tcp_header_len = sizeof(struct tcphdr);
+		}
+
+		if (tp->rx_opt.sack_ok && sysctl_tcp_fack)
+			tp->rx_opt.sack_ok |= 2;
+
+		tcp_sync_mss(sk, tp->pmtu_cookie);
+		tcp_initialize_rcv_mss(sk);
+
+		/* Remember, tcp_poll() does not lock socket!
+		 * Change state from SYN-SENT only after copied_seq
+		 * is initialized. */
+		tp->copied_seq = tp->rcv_nxt;
+		mb();
+		tcp_set_state(sk, TCP_ESTABLISHED);
+
+		/* Make sure socket is routed, for correct metrics.  */
+		tp->af_specific->rebuild_header(sk);
+
+		tcp_init_metrics(sk);
+
+		/* Prevent spurious tcp_cwnd_restart() on first data
+		 * packet.
+		 */
+		tp->lsndtime = tcp_time_stamp;
+
+		tcp_init_buffer_space(sk);
+
+		if (sock_flag(sk, SOCK_KEEPOPEN))
+			tcp_reset_keepalive_timer(sk, keepalive_time_when(tp));
+
+		if (!tp->rx_opt.snd_wscale)
+			__tcp_fast_path_on(tp, tp->snd_wnd);
+		else
+			tp->pred_flags = 0;
+
+		if (!sock_flag(sk, SOCK_DEAD)) {
+			sk->sk_state_change(sk);
+			sk_wake_async(sk, 0, POLL_OUT);
+		}
+
+		if (sk->sk_write_pending || tp->defer_accept || tp->ack.pingpong) {
+			/* Save one ACK. Data will be ready after
+			 * several ticks, if write_pending is set.
+			 *
+			 * It may be deleted, but with this feature tcpdumps
+			 * look so _wonderfully_ clever, that I was not able
+			 * to stand against the temptation 8)     --ANK
+			 */
+			tcp_schedule_ack(tp);
+			tp->ack.lrcvtime = tcp_time_stamp;
+			tp->ack.ato	 = TCP_ATO_MIN;
+			tcp_incr_quickack(tp);
+			tcp_enter_quickack_mode(tp);
+			tcp_reset_xmit_timer(sk, TCP_TIME_DACK, TCP_DELACK_MAX);
+
+discard:
+			__kfree_skb(skb);
+			return 0;
+		} else {
+			tcp_send_ack(sk);
+		}
+		return -1;
+	}
+
+	/* No ACK in the segment */
+
+	if (th->rst) {
+		/* rfc793:
+		 * "If the RST bit is set
+		 *
+		 *      Otherwise (no ACK) drop the segment and return."
+		 */
+
+		goto discard_and_undo;
+	}
+
+	/* PAWS check. */
+	if (tp->rx_opt.ts_recent_stamp && tp->rx_opt.saw_tstamp && tcp_paws_check(&tp->rx_opt, 0))
+		goto discard_and_undo;
+
+	if (th->syn) {
+		/* We see SYN without ACK. It is attempt of
+		 * simultaneous connect with crossed SYNs.
+		 * Particularly, it can be connect to self.
+		 */
+		tcp_set_state(sk, TCP_SYN_RECV);
+
+		if (tp->rx_opt.saw_tstamp) {
+			tp->rx_opt.tstamp_ok = 1;
+			tcp_store_ts_recent(tp);
+			tp->tcp_header_len =
+				sizeof(struct tcphdr) + TCPOLEN_TSTAMP_ALIGNED;
+		} else {
+			tp->tcp_header_len = sizeof(struct tcphdr);
+		}
+
+		tp->rcv_nxt = TCP_SKB_CB(skb)->seq + 1;
+		tp->rcv_wup = TCP_SKB_CB(skb)->seq + 1;
+
+		/* RFC1323: The window in SYN & SYN/ACK segments is
+		 * never scaled.
+		 */
+		tp->snd_wnd    = ntohs(th->window);
+		tp->snd_wl1    = TCP_SKB_CB(skb)->seq;
+		tp->max_window = tp->snd_wnd;
+
+		TCP_ECN_rcv_syn(tp, th);
+		if (tp->ecn_flags&TCP_ECN_OK)
+			sock_set_flag(sk, SOCK_NO_LARGESEND);
+
+		tcp_sync_mss(sk, tp->pmtu_cookie);
+		tcp_initialize_rcv_mss(sk);
+
+
+		tcp_send_synack(sk);
+#if 0
+		/* Note, we could accept data and URG from this segment.
+		 * There are no obstacles to make this.
+		 *
+		 * However, if we ignore data in ACKless segments sometimes,
+		 * we have no reasons to accept it sometimes.
+		 * Also, seems the code doing it in step6 of tcp_rcv_state_process
+		 * is not flawless. So, discard packet for sanity.
+		 * Uncomment this return to process the data.
+		 */
+		return -1;
+#else
+		goto discard;
+#endif
+	}
+	/* "fifth, if neither of the SYN or RST bits is set then
+	 * drop the segment and return."
+	 */
+
+discard_and_undo:
+	tcp_clear_options(&tp->rx_opt);
+	tp->rx_opt.mss_clamp = saved_clamp;
+	goto discard;
+
+reset_and_undo:
+	tcp_clear_options(&tp->rx_opt);
+	tp->rx_opt.mss_clamp = saved_clamp;
+	return 1;
+}
+
+
+/*
+ *	This function implements the receiving procedure of RFC 793 for
+ *	all states except ESTABLISHED and TIME_WAIT. 
+ *	It's called from both tcp_v4_rcv and tcp_v6_rcv and should be
+ *	address independent.
+ */
+	
+int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
+			  struct tcphdr *th, unsigned len)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	int queued = 0;
+
+	tp->rx_opt.saw_tstamp = 0;
+
+	switch (sk->sk_state) {
+	case TCP_CLOSE:
+		goto discard;
+
+	case TCP_LISTEN:
+		if(th->ack)
+			return 1;
+
+		if(th->rst)
+			goto discard;
+
+		if(th->syn) {
+			if(tp->af_specific->conn_request(sk, skb) < 0)
+				return 1;
+
+			init_westwood(sk);
+			init_bictcp(tp);
+
+			/* Now we have several options: In theory there is 
+			 * nothing else in the frame. KA9Q has an option to 
+			 * send data with the syn, BSD accepts data with the
+			 * syn up to the [to be] advertised window and 
+			 * Solaris 2.1 gives you a protocol error. For now 
+			 * we just ignore it, that fits the spec precisely 
+			 * and avoids incompatibilities. It would be nice in
+			 * future to drop through and process the data.
+			 *
+			 * Now that TTCP is starting to be used we ought to 
+			 * queue this data.
+			 * But, this leaves one open to an easy denial of
+		 	 * service attack, and SYN cookies can't defend
+			 * against this problem. So, we drop the data
+			 * in the interest of security over speed.
+			 */
+			goto discard;
+		}
+		goto discard;
+
+	case TCP_SYN_SENT:
+		init_westwood(sk);
+		init_bictcp(tp);
+
+		queued = tcp_rcv_synsent_state_process(sk, skb, th, len);
+		if (queued >= 0)
+			return queued;
+
+		/* Do step6 onward by hand. */
+		tcp_urg(sk, skb, th);
+		__kfree_skb(skb);
+		tcp_data_snd_check(sk);
+		return 0;
+	}
+
+	if (tcp_fast_parse_options(skb, th, tp) && tp->rx_opt.saw_tstamp &&
+	    tcp_paws_discard(tp, skb)) {
+		if (!th->rst) {
+			NET_INC_STATS_BH(LINUX_MIB_PAWSESTABREJECTED);
+			tcp_send_dupack(sk, skb);
+			goto discard;
+		}
+		/* Reset is accepted even if it did not pass PAWS. */
+	}
+
+	/* step 1: check sequence number */
+	if (!tcp_sequence(tp, TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq)) {
+		if (!th->rst)
+			tcp_send_dupack(sk, skb);
+		goto discard;
+	}
+
+	/* step 2: check RST bit */
+	if(th->rst) {
+		tcp_reset(sk);
+		goto discard;
+	}
+
+	tcp_replace_ts_recent(tp, TCP_SKB_CB(skb)->seq);
+
+	/* step 3: check security and precedence [ignored] */
+
+	/*	step 4:
+	 *
+	 *	Check for a SYN in window.
+	 */
+	if (th->syn && !before(TCP_SKB_CB(skb)->seq, tp->rcv_nxt)) {
+		NET_INC_STATS_BH(LINUX_MIB_TCPABORTONSYN);
+		tcp_reset(sk);
+		return 1;
+	}
+
+	/* step 5: check the ACK field */
+	if (th->ack) {
+		int acceptable = tcp_ack(sk, skb, FLAG_SLOWPATH);
+
+		switch(sk->sk_state) {
+		case TCP_SYN_RECV:
+			if (acceptable) {
+				tp->copied_seq = tp->rcv_nxt;
+				mb();
+				tcp_set_state(sk, TCP_ESTABLISHED);
+				sk->sk_state_change(sk);
+
+				/* Note, that this wakeup is only for marginal
+				 * crossed SYN case. Passively open sockets
+				 * are not waked up, because sk->sk_sleep ==
+				 * NULL and sk->sk_socket == NULL.
+				 */
+				if (sk->sk_socket) {
+					sk_wake_async(sk,0,POLL_OUT);
+				}
+
+				tp->snd_una = TCP_SKB_CB(skb)->ack_seq;
+				tp->snd_wnd = ntohs(th->window) <<
+					      tp->rx_opt.snd_wscale;
+				tcp_init_wl(tp, TCP_SKB_CB(skb)->ack_seq,
+					    TCP_SKB_CB(skb)->seq);
+
+				/* tcp_ack considers this ACK as duplicate
+				 * and does not calculate rtt.
+				 * Fix it at least with timestamps.
+				 */
+				if (tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr &&
+				    !tp->srtt)
+					tcp_ack_saw_tstamp(tp, 0);
+
+				if (tp->rx_opt.tstamp_ok)
+					tp->advmss -= TCPOLEN_TSTAMP_ALIGNED;
+
+				/* Make sure socket is routed, for
+				 * correct metrics.
+				 */
+				tp->af_specific->rebuild_header(sk);
+
+				tcp_init_metrics(sk);
+
+				/* Prevent spurious tcp_cwnd_restart() on
+				 * first data packet.
+				 */
+				tp->lsndtime = tcp_time_stamp;
+
+				tcp_initialize_rcv_mss(sk);
+				tcp_init_buffer_space(sk);
+				tcp_fast_path_on(tp);
+			} else {
+				return 1;
+			}
+			break;
+
+		case TCP_FIN_WAIT1:
+			if (tp->snd_una == tp->write_seq) {
+				tcp_set_state(sk, TCP_FIN_WAIT2);
+				sk->sk_shutdown |= SEND_SHUTDOWN;
+				dst_confirm(sk->sk_dst_cache);
+
+				if (!sock_flag(sk, SOCK_DEAD))
+					/* Wake up lingering close() */
+					sk->sk_state_change(sk);
+				else {
+					int tmo;
+
+					if (tp->linger2 < 0 ||
+					    (TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq &&
+					     after(TCP_SKB_CB(skb)->end_seq - th->fin, tp->rcv_nxt))) {
+						tcp_done(sk);
+						NET_INC_STATS_BH(LINUX_MIB_TCPABORTONDATA);
+						return 1;
+					}
+
+					tmo = tcp_fin_time(tp);
+					if (tmo > TCP_TIMEWAIT_LEN) {
+						tcp_reset_keepalive_timer(sk, tmo - TCP_TIMEWAIT_LEN);
+					} else if (th->fin || 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,
+						 * if it spins in bh_lock_sock(), but it is really
+						 * marginal case.
+						 */
+						tcp_reset_keepalive_timer(sk, tmo);
+					} else {
+						tcp_time_wait(sk, TCP_FIN_WAIT2, tmo);
+						goto discard;
+					}
+				}
+			}
+			break;
+
+		case TCP_CLOSING:
+			if (tp->snd_una == tp->write_seq) {
+				tcp_time_wait(sk, TCP_TIME_WAIT, 0);
+				goto discard;
+			}
+			break;
+
+		case TCP_LAST_ACK:
+			if (tp->snd_una == tp->write_seq) {
+				tcp_update_metrics(sk);
+				tcp_done(sk);
+				goto discard;
+			}
+			break;
+		}
+	} else
+		goto discard;
+
+	/* step 6: check the URG bit */
+	tcp_urg(sk, skb, th);
+
+	/* step 7: process the segment text */
+	switch (sk->sk_state) {
+	case TCP_CLOSE_WAIT:
+	case TCP_CLOSING:
+	case TCP_LAST_ACK:
+		if (!before(TCP_SKB_CB(skb)->seq, tp->rcv_nxt))
+			break;
+	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 (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)) {
+				NET_INC_STATS_BH(LINUX_MIB_TCPABORTONDATA);
+				tcp_reset(sk);
+				return 1;
+			}
+		}
+		/* Fall through */
+	case TCP_ESTABLISHED: 
+		tcp_data_queue(sk, skb);
+		queued = 1;
+		break;
+	}
+
+	/* tcp_data could move socket to TIME-WAIT */
+	if (sk->sk_state != TCP_CLOSE) {
+		tcp_data_snd_check(sk);
+		tcp_ack_snd_check(sk);
+	}
+
+	if (!queued) { 
+discard:
+		__kfree_skb(skb);
+	}
+	return 0;
+}
+
+EXPORT_SYMBOL(sysctl_tcp_ecn);
+EXPORT_SYMBOL(sysctl_tcp_reordering);
+EXPORT_SYMBOL(tcp_parse_options);
+EXPORT_SYMBOL(tcp_rcv_established);
+EXPORT_SYMBOL(tcp_rcv_state_process);