1 files changed, 224 insertions, 293 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 9c6225780bd5..28af45abe062 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -347,24 +347,13 @@ static void tcp_grow_window(struct sock *sk, const struct sk_buff *skb)
 }
 
 /* 3. Tuning rcvbuf, when connection enters established state. */
-
 static void tcp_fixup_rcvbuf(struct sock *sk)
 {
 	u32 mss = tcp_sk(sk)->advmss;
-	u32 icwnd = TCP_DEFAULT_INIT_RCVWND;
 	int rcvmem;
 
-	/* Limit to 10 segments if mss <= 1460,
-	 * or 14600/mss segments, with a minimum of two segments.
-	 */
-	if (mss > 1460)
-		icwnd = max_t(u32, (1460 * TCP_DEFAULT_INIT_RCVWND) / mss, 2);
-
-	rcvmem = SKB_TRUESIZE(mss + MAX_TCP_HEADER);
-	while (tcp_win_from_space(rcvmem) < mss)
-		rcvmem += 128;
-
-	rcvmem *= icwnd;
+	rcvmem = 2 * SKB_TRUESIZE(mss + MAX_TCP_HEADER) *
+		 tcp_default_init_rwnd(mss);
 
 	if (sk->sk_rcvbuf < rcvmem)
 		sk->sk_rcvbuf = min(rcvmem, sysctl_tcp_rmem[2]);
@@ -1257,8 +1246,6 @@ static bool tcp_shifted_skb(struct sock *sk, struct sk_buff *skb,
 
 	if (skb == tp->retransmit_skb_hint)
 		tp->retransmit_skb_hint = prev;
-	if (skb == tp->scoreboard_skb_hint)
-		tp->scoreboard_skb_hint = prev;
 	if (skb == tp->lost_skb_hint) {
 		tp->lost_skb_hint = prev;
 		tp->lost_cnt_hint -= tcp_skb_pcount(prev);
@@ -1966,20 +1953,6 @@ static bool tcp_pause_early_retransmit(struct sock *sk, int flag)
 	return true;
 }
 
-static inline int tcp_skb_timedout(const struct sock *sk,
-				   const struct sk_buff *skb)
-{
-	return tcp_time_stamp - TCP_SKB_CB(skb)->when > inet_csk(sk)->icsk_rto;
-}
-
-static inline int tcp_head_timedout(const struct sock *sk)
-{
-	const struct tcp_sock *tp = tcp_sk(sk);
-
-	return tp->packets_out &&
-	       tcp_skb_timedout(sk, tcp_write_queue_head(sk));
-}
-
 /* Linux NewReno/SACK/FACK/ECN state machine.
  * --------------------------------------
  *
@@ -2086,12 +2059,6 @@ static bool tcp_time_to_recover(struct sock *sk, int flag)
 	if (tcp_dupack_heuristics(tp) > tp->reordering)
 		return true;
 
-	/* Trick#3 : when we use RFC2988 timer restart, fast
-	 * retransmit can be triggered by timeout of queue head.
-	 */
-	if (tcp_is_fack(tp) && tcp_head_timedout(sk))
-		return true;
-
 	/* Trick#4: It is still not OK... But will it be useful to delay
 	 * recovery more?
 	 */
@@ -2128,44 +2095,6 @@ static bool tcp_time_to_recover(struct sock *sk, int flag)
 	return false;
 }
 
-/* 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.
- *
- * Usefulness of this as is very questionable, since we should know which of
- * the segments is the next to timeout which is relatively expensive to find
- * in general case unless we add some data structure just for that. The
- * current approach certainly won't find the right one too often and when it
- * finally does find _something_ it usually marks large part of the window
- * right away (because a retransmission with a larger timestamp blocks the
- * loop from advancing). -ij
- */
-static void tcp_timeout_skbs(struct sock *sk)
-{
-	struct tcp_sock *tp = tcp_sk(sk);
-	struct sk_buff *skb;
-
-	if (!tcp_is_fack(tp) || !tcp_head_timedout(sk))
-		return;
-
-	skb = tp->scoreboard_skb_hint;
-	if (tp->scoreboard_skb_hint == NULL)
-		skb = tcp_write_queue_head(sk);
-
-	tcp_for_write_queue_from(skb, sk) {
-		if (skb == tcp_send_head(sk))
-			break;
-		if (!tcp_skb_timedout(sk, skb))
-			break;
-
-		tcp_skb_mark_lost(tp, skb);
-	}
-
-	tp->scoreboard_skb_hint = skb;
-
-	tcp_verify_left_out(tp);
-}
-
 /* Detect loss in event "A" above by marking head of queue up as lost.
  * For FACK or non-SACK(Reno) senders, the first "packets" number of segments
  * are considered lost. For RFC3517 SACK, a segment is considered lost if it
@@ -2251,8 +2180,6 @@ static void tcp_update_scoreboard(struct sock *sk, int fast_rexmit)
 		else if (fast_rexmit)
 			tcp_mark_head_lost(sk, 1, 1);
 	}
-
-	tcp_timeout_skbs(sk);
 }
 
 /* CWND moderation, preventing bursts due to too big ACKs
@@ -2307,10 +2234,22 @@ static void DBGUNDO(struct sock *sk, const char *msg)
 #define DBGUNDO(x...) do { } while (0)
 #endif
 
-static void tcp_undo_cwr(struct sock *sk, const bool undo_ssthresh)
+static void tcp_undo_cwnd_reduction(struct sock *sk, bool unmark_loss)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 
+	if (unmark_loss) {
+		struct sk_buff *skb;
+
+		tcp_for_write_queue(skb, sk) {
+			if (skb == tcp_send_head(sk))
+				break;
+			TCP_SKB_CB(skb)->sacked &= ~TCPCB_LOST;
+		}
+		tp->lost_out = 0;
+		tcp_clear_all_retrans_hints(tp);
+	}
+
 	if (tp->prior_ssthresh) {
 		const struct inet_connection_sock *icsk = inet_csk(sk);
 
@@ -2319,7 +2258,7 @@ static void tcp_undo_cwr(struct sock *sk, const bool undo_ssthresh)
 		else
 			tp->snd_cwnd = max(tp->snd_cwnd, tp->snd_ssthresh << 1);
 
-		if (undo_ssthresh && tp->prior_ssthresh > tp->snd_ssthresh) {
+		if (tp->prior_ssthresh > tp->snd_ssthresh) {
 			tp->snd_ssthresh = tp->prior_ssthresh;
 			TCP_ECN_withdraw_cwr(tp);
 		}
@@ -2327,6 +2266,7 @@ static void tcp_undo_cwr(struct sock *sk, const bool undo_ssthresh)
 		tp->snd_cwnd = max(tp->snd_cwnd, tp->snd_ssthresh);
 	}
 	tp->snd_cwnd_stamp = tcp_time_stamp;
+	tp->undo_marker = 0;
 }
 
 static inline bool tcp_may_undo(const struct tcp_sock *tp)
@@ -2346,14 +2286,13 @@ static bool tcp_try_undo_recovery(struct sock *sk)
 		 * or our original transmission succeeded.
 		 */
 		DBGUNDO(sk, inet_csk(sk)->icsk_ca_state == TCP_CA_Loss ? "loss" : "retrans");
-		tcp_undo_cwr(sk, true);
+		tcp_undo_cwnd_reduction(sk, false);
 		if (inet_csk(sk)->icsk_ca_state == TCP_CA_Loss)
 			mib_idx = LINUX_MIB_TCPLOSSUNDO;
 		else
 			mib_idx = LINUX_MIB_TCPFULLUNDO;
 
 		NET_INC_STATS_BH(sock_net(sk), mib_idx);
-		tp->undo_marker = 0;
 	}
 	if (tp->snd_una == tp->high_seq && tcp_is_reno(tp)) {
 		/* Hold old state until something *above* high_seq
@@ -2367,16 +2306,17 @@ static bool tcp_try_undo_recovery(struct sock *sk)
 }
 
 /* Try to undo cwnd reduction, because D-SACKs acked all retransmitted data */
-static void tcp_try_undo_dsack(struct sock *sk)
+static bool tcp_try_undo_dsack(struct sock *sk)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 
 	if (tp->undo_marker && !tp->undo_retrans) {
 		DBGUNDO(sk, "D-SACK");
-		tcp_undo_cwr(sk, true);
-		tp->undo_marker = 0;
+		tcp_undo_cwnd_reduction(sk, false);
 		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPDSACKUNDO);
+		return true;
 	}
+	return false;
 }
 
 /* We can clear retrans_stamp when there are no retransmissions in the
@@ -2408,60 +2348,20 @@ static bool tcp_any_retrans_done(const struct sock *sk)
 	return false;
 }
 
-/* Undo during fast recovery after partial ACK. */
-
-static int tcp_try_undo_partial(struct sock *sk, int acked)
-{
-	struct tcp_sock *tp = tcp_sk(sk);
-	/* Partial ACK arrived. Force Hoe's retransmit. */
-	int failed = tcp_is_reno(tp) || (tcp_fackets_out(tp) > tp->reordering);
-
-	if (tcp_may_undo(tp)) {
-		/* Plain luck! Hole if filled with delayed
-		 * packet, rather than with a retransmit.
-		 */
-		if (!tcp_any_retrans_done(sk))
-			tp->retrans_stamp = 0;
-
-		tcp_update_reordering(sk, tcp_fackets_out(tp) + acked, 1);
-
-		DBGUNDO(sk, "Hoe");
-		tcp_undo_cwr(sk, false);
-		NET_INC_STATS_BH(sock_net(sk), 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 or using F-RTO. */
 static bool tcp_try_undo_loss(struct sock *sk, bool frto_undo)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 
 	if (frto_undo || tcp_may_undo(tp)) {
-		struct sk_buff *skb;
-		tcp_for_write_queue(skb, sk) {
-			if (skb == tcp_send_head(sk))
-				break;
-			TCP_SKB_CB(skb)->sacked &= ~TCPCB_LOST;
-		}
-
-		tcp_clear_all_retrans_hints(tp);
+		tcp_undo_cwnd_reduction(sk, true);
 
 		DBGUNDO(sk, "partial loss");
-		tp->lost_out = 0;
-		tcp_undo_cwr(sk, true);
 		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPLOSSUNDO);
 		if (frto_undo)
 			NET_INC_STATS_BH(sock_net(sk),
 					 LINUX_MIB_TCPSPURIOUSRTOS);
 		inet_csk(sk)->icsk_retransmits = 0;
-		tp->undo_marker = 0;
 		if (frto_undo || tcp_is_sack(tp))
 			tcp_set_ca_state(sk, TCP_CA_Open);
 		return true;
@@ -2494,12 +2394,14 @@ static void tcp_init_cwnd_reduction(struct sock *sk, const bool set_ssthresh)
 	TCP_ECN_queue_cwr(tp);
 }
 
-static void tcp_cwnd_reduction(struct sock *sk, int newly_acked_sacked,
+static void tcp_cwnd_reduction(struct sock *sk, const int prior_unsacked,
 			       int fast_rexmit)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 	int sndcnt = 0;
 	int delta = tp->snd_ssthresh - tcp_packets_in_flight(tp);
+	int newly_acked_sacked = prior_unsacked -
+				 (tp->packets_out - tp->sacked_out);
 
 	tp->prr_delivered += newly_acked_sacked;
 	if (tcp_packets_in_flight(tp) > tp->snd_ssthresh) {
@@ -2556,7 +2458,7 @@ static void tcp_try_keep_open(struct sock *sk)
 	}
 }
 
-static void tcp_try_to_open(struct sock *sk, int flag, int newly_acked_sacked)
+static void tcp_try_to_open(struct sock *sk, int flag, const int prior_unsacked)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 
@@ -2573,7 +2475,7 @@ static void tcp_try_to_open(struct sock *sk, int flag, int newly_acked_sacked)
 		if (inet_csk(sk)->icsk_ca_state != TCP_CA_Open)
 			tcp_moderate_cwnd(tp);
 	} else {
-		tcp_cwnd_reduction(sk, newly_acked_sacked, 0);
+		tcp_cwnd_reduction(sk, prior_unsacked, 0);
 	}
 }
 
@@ -2731,6 +2633,40 @@ static void tcp_process_loss(struct sock *sk, int flag, bool is_dupack)
 	tcp_xmit_retransmit_queue(sk);
 }
 
+/* Undo during fast recovery after partial ACK. */
+static bool tcp_try_undo_partial(struct sock *sk, const int acked,
+				 const int prior_unsacked)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+
+	if (tp->undo_marker && tcp_packet_delayed(tp)) {
+		/* Plain luck! Hole if filled with delayed
+		 * packet, rather than with a retransmit.
+		 */
+		tcp_update_reordering(sk, tcp_fackets_out(tp) + acked, 1);
+
+		/* We are getting evidence that the reordering degree is higher
+		 * than we realized. If there are no retransmits out then we
+		 * can undo. Otherwise we clock out new packets but do not
+		 * mark more packets lost or retransmit more.
+		 */
+		if (tp->retrans_out) {
+			tcp_cwnd_reduction(sk, prior_unsacked, 0);
+			return true;
+		}
+
+		if (!tcp_any_retrans_done(sk))
+			tp->retrans_stamp = 0;
+
+		DBGUNDO(sk, "partial recovery");
+		tcp_undo_cwnd_reduction(sk, true);
+		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPPARTIALUNDO);
+		tcp_try_keep_open(sk);
+		return true;
+	}
+	return false;
+}
+
 /* 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
@@ -2742,15 +2678,14 @@ static void tcp_process_loss(struct sock *sk, int flag, bool is_dupack)
  * It does _not_ decide what to send, it is made in function
  * tcp_xmit_retransmit_queue().
  */
-static void tcp_fastretrans_alert(struct sock *sk, int pkts_acked,
-				  int prior_sacked, int prior_packets,
+static void tcp_fastretrans_alert(struct sock *sk, const int acked,
+				  const int prior_unsacked,
 				  bool is_dupack, int flag)
 {
 	struct inet_connection_sock *icsk = inet_csk(sk);
 	struct tcp_sock *tp = tcp_sk(sk);
-	int do_lost = is_dupack || ((flag & FLAG_DATA_SACKED) &&
+	bool do_lost = is_dupack || ((flag & FLAG_DATA_SACKED) &&
 				    (tcp_fackets_out(tp) > tp->reordering));
-	int newly_acked_sacked = 0;
 	int fast_rexmit = 0;
 
 	if (WARN_ON(!tp->packets_out && tp->sacked_out))
@@ -2802,10 +2737,17 @@ static void tcp_fastretrans_alert(struct sock *sk, int pkts_acked,
 		if (!(flag & FLAG_SND_UNA_ADVANCED)) {
 			if (tcp_is_reno(tp) && is_dupack)
 				tcp_add_reno_sack(sk);
-		} else
-			do_lost = tcp_try_undo_partial(sk, pkts_acked);
-		newly_acked_sacked = prior_packets - tp->packets_out +
-				     tp->sacked_out - prior_sacked;
+		} else {
+			if (tcp_try_undo_partial(sk, acked, prior_unsacked))
+				return;
+			/* Partial ACK arrived. Force fast retransmit. */
+			do_lost = tcp_is_reno(tp) ||
+				  tcp_fackets_out(tp) > tp->reordering;
+		}
+		if (tcp_try_undo_dsack(sk)) {
+			tcp_try_keep_open(sk);
+			return;
+		}
 		break;
 	case TCP_CA_Loss:
 		tcp_process_loss(sk, flag, is_dupack);
@@ -2819,14 +2761,12 @@ static void tcp_fastretrans_alert(struct sock *sk, int pkts_acked,
 			if (is_dupack)
 				tcp_add_reno_sack(sk);
 		}
-		newly_acked_sacked = prior_packets - tp->packets_out +
-				     tp->sacked_out - prior_sacked;
 
 		if (icsk->icsk_ca_state <= TCP_CA_Disorder)
 			tcp_try_undo_dsack(sk);
 
 		if (!tcp_time_to_recover(sk, flag)) {
-			tcp_try_to_open(sk, flag, newly_acked_sacked);
+			tcp_try_to_open(sk, flag, prior_unsacked);
 			return;
 		}
 
@@ -2846,9 +2786,9 @@ static void tcp_fastretrans_alert(struct sock *sk, int pkts_acked,
 		fast_rexmit = 1;
 	}
 
-	if (do_lost || (tcp_is_fack(tp) && tcp_head_timedout(sk)))
+	if (do_lost)
 		tcp_update_scoreboard(sk, fast_rexmit);
-	tcp_cwnd_reduction(sk, newly_acked_sacked, fast_rexmit);
+	tcp_cwnd_reduction(sk, prior_unsacked, fast_rexmit);
 	tcp_xmit_retransmit_queue(sk);
 }
 
@@ -3079,7 +3019,6 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets,
 
 		tcp_unlink_write_queue(skb, sk);
 		sk_wmem_free_skb(sk, skb);
-		tp->scoreboard_skb_hint = NULL;
 		if (skb == tp->retransmit_skb_hint)
 			tp->retransmit_skb_hint = NULL;
 		if (skb == tp->lost_skb_hint)
@@ -3333,9 +3272,8 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
 	u32 prior_in_flight;
 	u32 prior_fackets;
 	int prior_packets = tp->packets_out;
-	int prior_sacked = tp->sacked_out;
-	int pkts_acked = 0;
-	int previous_packets_out = 0;
+	const int prior_unsacked = tp->packets_out - tp->sacked_out;
+	int acked = 0; /* Number of packets newly acked */
 
 	/* If the ack is older than previous acks
 	 * then we can probably ignore it.
@@ -3410,18 +3348,17 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
 		goto no_queue;
 
 	/* See if we can take anything off of the retransmit queue. */
-	previous_packets_out = tp->packets_out;
+	acked = tp->packets_out;
 	flag |= tcp_clean_rtx_queue(sk, prior_fackets, prior_snd_una);
-
-	pkts_acked = previous_packets_out - tp->packets_out;
+	acked -= tp->packets_out;
 
 	if (tcp_ack_is_dubious(sk, flag)) {
 		/* Advance CWND, if state allows this. */
 		if ((flag & FLAG_DATA_ACKED) && tcp_may_raise_cwnd(sk, flag))
 			tcp_cong_avoid(sk, ack, prior_in_flight);
 		is_dupack = !(flag & (FLAG_SND_UNA_ADVANCED | FLAG_NOT_DUP));
-		tcp_fastretrans_alert(sk, pkts_acked, prior_sacked,
-				      prior_packets, is_dupack, flag);
+		tcp_fastretrans_alert(sk, acked, prior_unsacked,
+				      is_dupack, flag);
 	} else {
 		if (flag & FLAG_DATA_ACKED)
 			tcp_cong_avoid(sk, ack, prior_in_flight);
@@ -3443,8 +3380,8 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
 no_queue:
 	/* If data was DSACKed, see if we can undo a cwnd reduction. */
 	if (flag & FLAG_DSACKING_ACK)
-		tcp_fastretrans_alert(sk, pkts_acked, prior_sacked,
-				      prior_packets, is_dupack, flag);
+		tcp_fastretrans_alert(sk, acked, prior_unsacked,
+				      is_dupack, flag);
 	/* 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.
@@ -3466,8 +3403,8 @@ old_ack:
 	 */
 	if (TCP_SKB_CB(skb)->sacked) {
 		flag |= tcp_sacktag_write_queue(sk, skb, prior_snd_una);
-		tcp_fastretrans_alert(sk, pkts_acked, prior_sacked,
-				      prior_packets, is_dupack, flag);
+		tcp_fastretrans_alert(sk, acked, prior_unsacked,
+				      is_dupack, flag);
 	}
 
 	SOCK_DEBUG(sk, "Ack %u before %u:%u\n", ack, tp->snd_una, tp->snd_nxt);
@@ -3780,6 +3717,7 @@ void tcp_reset(struct sock *sk)
 static void tcp_fin(struct sock *sk)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
+	const struct dst_entry *dst;
 
 	inet_csk_schedule_ack(sk);
 
@@ -3791,7 +3729,9 @@ static void tcp_fin(struct sock *sk)
 	case TCP_ESTABLISHED:
 		/* Move to CLOSE_WAIT */
 		tcp_set_state(sk, TCP_CLOSE_WAIT);
-		inet_csk(sk)->icsk_ack.pingpong = 1;
+		dst = __sk_dst_get(sk);
+		if (!dst || !dst_metric(dst, RTAX_QUICKACK))
+			inet_csk(sk)->icsk_ack.pingpong = 1;
 		break;
 
 	case TCP_CLOSE_WAIT:
@@ -5601,6 +5541,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
 	struct inet_connection_sock *icsk = inet_csk(sk);
 	struct request_sock *req;
 	int queued = 0;
+	bool acceptable;
 
 	tp->rx_opt.saw_tstamp = 0;
 
@@ -5671,157 +5612,147 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
 		return 0;
 
 	/* step 5: check the ACK field */
-	if (true) {
-		int acceptable = tcp_ack(sk, skb, FLAG_SLOWPATH |
-						  FLAG_UPDATE_TS_RECENT) > 0;
-
-		switch (sk->sk_state) {
-		case TCP_SYN_RECV:
-			if (acceptable) {
-				/* Once we leave TCP_SYN_RECV, we no longer
-				 * need req so release it.
-				 */
-				if (req) {
-					tcp_synack_rtt_meas(sk, req);
-					tp->total_retrans = req->num_retrans;
-
-					reqsk_fastopen_remove(sk, req, false);
-				} else {
-					/* Make sure socket is routed, for
-					 * correct metrics.
-					 */
-					icsk->icsk_af_ops->rebuild_header(sk);
-					tcp_init_congestion_control(sk);
+	acceptable = tcp_ack(sk, skb, FLAG_SLOWPATH |
+				      FLAG_UPDATE_TS_RECENT) > 0;
 
-					tcp_mtup_init(sk);
-					tcp_init_buffer_space(sk);
-					tp->copied_seq = tp->rcv_nxt;
-				}
-				smp_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,
-						      SOCK_WAKE_IO, 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)->seq);
-
-				if (tp->rx_opt.tstamp_ok)
-					tp->advmss -= TCPOLEN_TSTAMP_ALIGNED;
-
-				if (req) {
-					/* Re-arm the timer because data may
-					 * have been sent out. This is similar
-					 * to the regular data transmission case
-					 * when new data has just been ack'ed.
-					 *
-					 * (TFO) - we could try to be more
-					 * aggressive and retranmitting any data
-					 * sooner based on when they were sent
-					 * out.
-					 */
-					tcp_rearm_rto(sk);
-				} else
-					tcp_init_metrics(sk);
+	switch (sk->sk_state) {
+	case TCP_SYN_RECV:
+		if (!acceptable)
+			return 1;
 
-				/* Prevent spurious tcp_cwnd_restart() on
-				 * first data packet.
-				 */
-				tp->lsndtime = tcp_time_stamp;
+		/* Once we leave TCP_SYN_RECV, we no longer need req
+		 * so release it.
+		 */
+		if (req) {
+			tcp_synack_rtt_meas(sk, req);
+			tp->total_retrans = req->num_retrans;
 
-				tcp_initialize_rcv_mss(sk);
-				tcp_fast_path_on(tp);
-			} else {
-				return 1;
-			}
-			break;
+			reqsk_fastopen_remove(sk, req, false);
+		} else {
+			/* Make sure socket is routed, for correct metrics. */
+			icsk->icsk_af_ops->rebuild_header(sk);
+			tcp_init_congestion_control(sk);
+
+			tcp_mtup_init(sk);
+			tcp_init_buffer_space(sk);
+			tp->copied_seq = tp->rcv_nxt;
+		}
+		smp_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, SOCK_WAKE_IO, 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)->seq);
 
-		case TCP_FIN_WAIT1:
-			/* If we enter the TCP_FIN_WAIT1 state and we are a
-			 * Fast Open socket and this is the first acceptable
-			 * ACK we have received, this would have acknowledged
-			 * our SYNACK so stop the SYNACK timer.
+		if (tp->rx_opt.tstamp_ok)
+			tp->advmss -= TCPOLEN_TSTAMP_ALIGNED;
+
+		if (req) {
+			/* Re-arm the timer because data may have been sent out.
+			 * This is similar to the regular data transmission case
+			 * when new data has just been ack'ed.
+			 *
+			 * (TFO) - we could try to be more aggressive and
+			 * retransmitting any data sooner based on when they
+			 * are sent out.
 			 */
-			if (req != NULL) {
-				/* Return RST if ack_seq is invalid.
-				 * Note that RFC793 only says to generate a
-				 * DUPACK for it but for TCP Fast Open it seems
-				 * better to treat this case like TCP_SYN_RECV
-				 * above.
-				 */
-				if (!acceptable)
-					return 1;
-				/* We no longer need the request sock. */
-				reqsk_fastopen_remove(sk, req, false);
-				tcp_rearm_rto(sk);
-			}
-			if (tp->snd_una == tp->write_seq) {
-				struct dst_entry *dst;
-
-				tcp_set_state(sk, TCP_FIN_WAIT2);
-				sk->sk_shutdown |= SEND_SHUTDOWN;
-
-				dst = __sk_dst_get(sk);
-				if (dst)
-					dst_confirm(dst);
-
-				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(sock_net(sk), LINUX_MIB_TCPABORTONDATA);
-						return 1;
-					}
+			tcp_rearm_rto(sk);
+		} else
+			tcp_init_metrics(sk);
 
-					tmo = tcp_fin_time(sk);
-					if (tmo > TCP_TIMEWAIT_LEN) {
-						inet_csk_reset_keepalive_timer(sk, tmo - TCP_TIMEWAIT_LEN);
-					} else if (th->fin || sock_owned_by_user(sk)) {
-						/* Bad case. We could lose such FIN otherwise.
-						 * It is not a big problem, but it looks confusing
-						 * and not so rare event. We still can lose it now,
-						 * if it spins in bh_lock_sock(), but it is really
-						 * marginal case.
-						 */
-						inet_csk_reset_keepalive_timer(sk, tmo);
-					} else {
-						tcp_time_wait(sk, TCP_FIN_WAIT2, tmo);
-						goto discard;
-					}
-				}
-			}
-			break;
+		/* Prevent spurious tcp_cwnd_restart() on first data packet */
+		tp->lsndtime = tcp_time_stamp;
 
-		case TCP_CLOSING:
-			if (tp->snd_una == tp->write_seq) {
-				tcp_time_wait(sk, TCP_TIME_WAIT, 0);
-				goto discard;
-			}
+		tcp_initialize_rcv_mss(sk);
+		tcp_fast_path_on(tp);
+		break;
+
+	case TCP_FIN_WAIT1: {
+		struct dst_entry *dst;
+		int tmo;
+
+		/* If we enter the TCP_FIN_WAIT1 state and we are a
+		 * Fast Open socket and this is the first acceptable
+		 * ACK we have received, this would have acknowledged
+		 * our SYNACK so stop the SYNACK timer.
+		 */
+		if (req != NULL) {
+			/* Return RST if ack_seq is invalid.
+			 * Note that RFC793 only says to generate a
+			 * DUPACK for it but for TCP Fast Open it seems
+			 * better to treat this case like TCP_SYN_RECV
+			 * above.
+			 */
+			if (!acceptable)
+				return 1;
+			/* We no longer need the request sock. */
+			reqsk_fastopen_remove(sk, req, false);
+			tcp_rearm_rto(sk);
+		}
+		if (tp->snd_una != tp->write_seq)
 			break;
 
-		case TCP_LAST_ACK:
-			if (tp->snd_una == tp->write_seq) {
-				tcp_update_metrics(sk);
-				tcp_done(sk);
-				goto discard;
-			}
+		tcp_set_state(sk, TCP_FIN_WAIT2);
+		sk->sk_shutdown |= SEND_SHUTDOWN;
+
+		dst = __sk_dst_get(sk);
+		if (dst)
+			dst_confirm(dst);
+
+		if (!sock_flag(sk, SOCK_DEAD)) {
+			/* Wake up lingering close() */
+			sk->sk_state_change(sk);
 			break;
 		}
+
+		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(sock_net(sk), LINUX_MIB_TCPABORTONDATA);
+			return 1;
+		}
+
+		tmo = tcp_fin_time(sk);
+		if (tmo > TCP_TIMEWAIT_LEN) {
+			inet_csk_reset_keepalive_timer(sk, tmo - TCP_TIMEWAIT_LEN);
+		} else if (th->fin || sock_owned_by_user(sk)) {
+			/* Bad case. We could lose such FIN otherwise.
+			 * It is not a big problem, but it looks confusing
+			 * and not so rare event. We still can lose it now,
+			 * if it spins in bh_lock_sock(), but it is really
+			 * marginal case.
+			 */
+			inet_csk_reset_keepalive_timer(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;
 	}
 
 	/* step 6: check the URG bit */