Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next

Pull networking updates from David Miller:
 "Highlights (1721 non-merge commits, this has to be a record of some
  sort):

   1) Add 'random' mode to team driver, from Jiri Pirko and Eric
      Dumazet.

   2) Make it so that any driver that supports configuration of multiple
      MAC addresses can provide the forwarding database add and del
      calls by providing a default implementation and hooking that up if
      the driver doesn't have an explicit set of handlers.  From Vlad
      Yasevich.

   3) Support GSO segmentation over tunnels and other encapsulating
      devices such as VXLAN, from Pravin B Shelar.

   4) Support L2 GRE tunnels in the flow dissector, from Michael Dalton.

   5) Implement Tail Loss Probe (TLP) detection in TCP, from Nandita
      Dukkipati.

   6) In the PHY layer, allow supporting wake-on-lan in situations where
      the PHY registers have to be written for it to be configured.

      Use it to support wake-on-lan in mv643xx_eth.

      From Michael Stapelberg.

   7) Significantly improve firewire IPV6 support, from YOSHIFUJI
      Hideaki.

   8) Allow multiple packets to be sent in a single transmission using
      network coding in batman-adv, from Martin Hundebøll.

   9) Add support for T5 cxgb4 chips, from Santosh Rastapur.

  10) Generalize the VXLAN forwarding tables so that there is more
      flexibility in configurating various aspects of the endpoints.
      From David Stevens.

  11) Support RSS and TSO in hardware over GRE tunnels in bxn2x driver,
      from Dmitry Kravkov.

  12) Zero copy support in nfnelink_queue, from Eric Dumazet and Pablo
      Neira Ayuso.

  13) Start adding networking selftests.

  14) In situations of overload on the same AF_PACKET fanout socket, or
      per-cpu packet receive queue, minimize drop by distributing the
      load to other cpus/fanouts.  From Willem de Bruijn and Eric
      Dumazet.

  15) Add support for new payload offset BPF instruction, from Daniel
      Borkmann.

  16) Convert several drivers over to mdoule_platform_driver(), from
      Sachin Kamat.

  17) Provide a minimal BPF JIT image disassembler userspace tool, from
      Daniel Borkmann.

  18) Rewrite F-RTO implementation in TCP to match the final
      specification of it in RFC4138 and RFC5682.  From Yuchung Cheng.

  19) Provide netlink socket diag of netlink sockets ("Yo dawg, I hear
      you like netlink, so I implemented netlink dumping of netlink
      sockets.") From Andrey Vagin.

  20) Remove ugly passing of rtnetlink attributes into rtnl_doit
      functions, from Thomas Graf.

  21) Allow userspace to be able to see if a configuration change occurs
      in the middle of an address or device list dump, from Nicolas
      Dichtel.

  22) Support RFC3168 ECN protection for ipv6 fragments, from Hannes
      Frederic Sowa.

  23) Increase accuracy of packet length used by packet scheduler, from
      Jason Wang.

  24) Beginning set of changes to make ipv4/ipv6 fragment handling more
      scalable and less susceptible to overload and locking contention,
      from Jesper Dangaard Brouer.

  25) Get rid of using non-type-safe NLMSG_* macros and use nlmsg_*()
      instead.  From Hong Zhiguo.

  26) Optimize route usage in IPVS by avoiding reference counting where
      possible, from Julian Anastasov.

  27) Convert IPVS schedulers to RCU, also from Julian Anastasov.

  28) Support cpu fanouts in xt_NFQUEUE netfilter target, from Holger
      Eitzenberger.

  29) Network namespace support for nf_log, ebt_log, xt_LOG, ipt_ULOG,
      nfnetlink_log, and nfnetlink_queue.  From Gao feng.

  30) Implement RFC3168 ECN protection, from Hannes Frederic Sowa.

  31) Support several new r8169 chips, from Hayes Wang.

  32) Support tokenized interface identifiers in ipv6, from Daniel
      Borkmann.

  33) Use usbnet_link_change() helper in USB net driver, from Ming Lei.

  34) Add 802.1ad vlan offload support, from Patrick McHardy.

  35) Support mmap() based netlink communication, also from Patrick
      McHardy.

  36) Support HW timestamping in mlx4 driver, from Amir Vadai.

  37) Rationalize AF_PACKET packet timestamping when transmitting, from
      Willem de Bruijn and Daniel Borkmann.

  38) Bring parity to what's provided by /proc/net/packet socket dumping
      and the info provided by netlink socket dumping of AF_PACKET
      sockets.  From Nicolas Dichtel.

  39) Fix peeking beyond zero sized SKBs in AF_UNIX, from Benjamin
      Poirier"

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1722 commits)
  filter: fix va_list build error
  af_unix: fix a fatal race with bit fields
  bnx2x: Prevent memory leak when cnic is absent
  bnx2x: correct reading of speed capabilities
  net: sctp: attribute printl with __printf for gcc fmt checks
  netlink: kconfig: move mmap i/o into netlink kconfig
  netpoll: convert mutex into a semaphore
  netlink: Fix skb ref counting.
  net_sched: act_ipt forward compat with xtables
  mlx4_en: fix a build error on 32bit arches
  Revert "bnx2x: allow nvram test to run when device is down"
  bridge: avoid OOPS if root port not found
  drivers: net: cpsw: fix kernel warn on cpsw irq enable
  sh_eth: use random MAC address if no valid one supplied
  3c509.c: call SET_NETDEV_DEV for all device types (ISA/ISAPnP/EISA)
  tg3: fix to append hardware time stamping flags
  unix/stream: fix peeking with an offset larger than data in queue
  unix/dgram: fix peeking with an offset larger than data in queue
  unix/dgram: peek beyond 0-sized skbs
  openvswitch: Remove unneeded ovs_netdev_get_ifindex()
  ...

1 files changed, 144 insertions, 463 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 13b9c08fc158..08bbe6096528 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -93,12 +93,11 @@ int sysctl_tcp_stdurg __read_mostly;
 int sysctl_tcp_rfc1337 __read_mostly;
 int sysctl_tcp_max_orphans __read_mostly = NR_FILE;
 int sysctl_tcp_frto __read_mostly = 2;
-int sysctl_tcp_frto_response __read_mostly;
 
 int sysctl_tcp_thin_dupack __read_mostly;
 
 int sysctl_tcp_moderate_rcvbuf __read_mostly = 1;
-int sysctl_tcp_early_retrans __read_mostly = 2;
+int sysctl_tcp_early_retrans __read_mostly = 3;
 
 #define FLAG_DATA		0x01 /* Incoming frame contained data.		*/
 #define FLAG_WIN_UPDATE		0x02 /* Incoming ACK was a window update.	*/
@@ -108,10 +107,9 @@ int sysctl_tcp_early_retrans __read_mostly = 2;
 #define FLAG_DATA_SACKED	0x20 /* New SACK.				*/
 #define FLAG_ECE		0x40 /* ECE in this ACK				*/
 #define FLAG_SLOWPATH		0x100 /* Do not skip RFC checks for window update.*/
-#define FLAG_ONLY_ORIG_SACKED	0x200 /* SACKs only non-rexmit sent before RTO */
+#define FLAG_ORIG_SACK_ACKED	0x200 /* Never retransmitted data are (s)acked	*/
 #define FLAG_SND_UNA_ADVANCED	0x400 /* Snd_una was changed (!= FLAG_DATA_ACKED) */
 #define FLAG_DSACKING_ACK	0x800 /* SACK blocks contained D-SACK info */
-#define FLAG_NONHEAD_RETRANS_ACKED	0x1000 /* Non-head rexmitted data was ACKed */
 #define FLAG_SACK_RENEGING	0x2000 /* snd_una advanced to a sacked seq */
 #define FLAG_UPDATE_TS_RECENT	0x4000 /* tcp_replace_ts_recent() */
 
@@ -119,7 +117,6 @@ int sysctl_tcp_early_retrans __read_mostly = 2;
 #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 FLAG_ANY_PROGRESS	(FLAG_FORWARD_PROGRESS|FLAG_SND_UNA_ADVANCED)
 
 #define TCP_REMNANT (TCP_FLAG_FIN|TCP_FLAG_URG|TCP_FLAG_SYN|TCP_FLAG_PSH)
 #define TCP_HP_BITS (~(TCP_RESERVED_BITS|TCP_FLAG_PSH))
@@ -1160,10 +1157,8 @@ static u8 tcp_sacktag_one(struct sock *sk,
 					   tcp_highest_sack_seq(tp)))
 					state->reord = min(fack_count,
 							   state->reord);
-
-				/* SACK enhanced F-RTO (RFC4138; Appendix B) */
-				if (!after(end_seq, tp->frto_highmark))
-					state->flag |= FLAG_ONLY_ORIG_SACKED;
+				if (!after(end_seq, tp->high_seq))
+					state->flag |= FLAG_ORIG_SACK_ACKED;
 			}
 
 			if (sacked & TCPCB_LOST) {
@@ -1556,7 +1551,6 @@ static int
 tcp_sacktag_write_queue(struct sock *sk, const struct sk_buff *ack_skb,
 			u32 prior_snd_una)
 {
-	const struct inet_connection_sock *icsk = inet_csk(sk);
 	struct tcp_sock *tp = tcp_sk(sk);
 	const unsigned char *ptr = (skb_transport_header(ack_skb) +
 				    TCP_SKB_CB(ack_skb)->sacked);
@@ -1729,12 +1723,6 @@ walk:
 				       start_seq, end_seq, dup_sack);
 
 advance_sp:
-		/* SACK enhanced FRTO (RFC4138, Appendix B): Clearing correct
-		 * due to in-order walk
-		 */
-		if (after(end_seq, tp->frto_highmark))
-			state.flag &= ~FLAG_ONLY_ORIG_SACKED;
-
 		i++;
 	}
 
@@ -1751,8 +1739,7 @@ advance_sp:
 	tcp_verify_left_out(tp);
 
 	if ((state.reord < tp->fackets_out) &&
-	    ((icsk->icsk_ca_state != TCP_CA_Loss) || tp->undo_marker) &&
-	    (!tp->frto_highmark || after(tp->snd_una, tp->frto_highmark)))
+	    ((inet_csk(sk)->icsk_ca_state != TCP_CA_Loss) || tp->undo_marker))
 		tcp_update_reordering(sk, tp->fackets_out - state.reord, 0);
 
 out:
@@ -1826,197 +1813,6 @@ static inline void tcp_reset_reno_sack(struct tcp_sock *tp)
 	tp->sacked_out = 0;
 }
 
-static int tcp_is_sackfrto(const struct tcp_sock *tp)
-{
-	return (sysctl_tcp_frto == 0x2) && !tcp_is_reno(tp);
-}
-
-/* F-RTO can only be used if TCP has never retransmitted anything other than
- * head (SACK enhanced variant from Appendix B of RFC4138 is more robust here)
- */
-bool tcp_use_frto(struct sock *sk)
-{
-	const struct tcp_sock *tp = tcp_sk(sk);
-	const struct inet_connection_sock *icsk = inet_csk(sk);
-	struct sk_buff *skb;
-
-	if (!sysctl_tcp_frto)
-		return false;
-
-	/* MTU probe and F-RTO won't really play nicely along currently */
-	if (icsk->icsk_mtup.probe_size)
-		return false;
-
-	if (tcp_is_sackfrto(tp))
-		return true;
-
-	/* Avoid expensive walking of rexmit queue if possible */
-	if (tp->retrans_out > 1)
-		return false;
-
-	skb = tcp_write_queue_head(sk);
-	if (tcp_skb_is_last(sk, skb))
-		return true;
-	skb = tcp_write_queue_next(sk, skb);	/* Skips head */
-	tcp_for_write_queue_from(skb, sk) {
-		if (skb == tcp_send_head(sk))
-			break;
-		if (TCP_SKB_CB(skb)->sacked & TCPCB_RETRANS)
-			return false;
-		/* Short-circuit when first non-SACKed skb has been checked */
-		if (!(TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED))
-			break;
-	}
-	return true;
-}
-
-/* RTO occurred, but do not yet enter Loss state. Instead, defer RTO
- * recovery a bit and use heuristics in tcp_process_frto() to detect if
- * the RTO was spurious. Only clear SACKED_RETRANS of the head here to
- * keep retrans_out counting accurate (with SACK F-RTO, other than head
- * may still have that bit set); TCPCB_LOST and remaining SACKED_RETRANS
- * bits are handled if the Loss state is really to be entered (in
- * tcp_enter_frto_loss).
- *
- * Do like tcp_enter_loss() would; when RTO expires the second time it
- * does:
- *  "Reduce ssthresh if it has not yet been made inside this window."
- */
-void tcp_enter_frto(struct sock *sk)
-{
-	const struct inet_connection_sock *icsk = inet_csk(sk);
-	struct tcp_sock *tp = tcp_sk(sk);
-	struct sk_buff *skb;
-
-	if ((!tp->frto_counter && icsk->icsk_ca_state <= TCP_CA_Disorder) ||
-	    tp->snd_una == tp->high_seq ||
-	    ((icsk->icsk_ca_state == TCP_CA_Loss || tp->frto_counter) &&
-	     !icsk->icsk_retransmits)) {
-		tp->prior_ssthresh = tcp_current_ssthresh(sk);
-		/* Our state is too optimistic in ssthresh() call because cwnd
-		 * is not reduced until tcp_enter_frto_loss() when previous F-RTO
-		 * recovery has not yet completed. Pattern would be this: RTO,
-		 * Cumulative ACK, RTO (2xRTO for the same segment does not end
-		 * up here twice).
-		 * RFC4138 should be more specific on what to do, even though
-		 * RTO is quite unlikely to occur after the first Cumulative ACK
-		 * due to back-off and complexity of triggering events ...
-		 */
-		if (tp->frto_counter) {
-			u32 stored_cwnd;
-			stored_cwnd = tp->snd_cwnd;
-			tp->snd_cwnd = 2;
-			tp->snd_ssthresh = icsk->icsk_ca_ops->ssthresh(sk);
-			tp->snd_cwnd = stored_cwnd;
-		} else {
-			tp->snd_ssthresh = icsk->icsk_ca_ops->ssthresh(sk);
-		}
-		/* ... in theory, cong.control module could do "any tricks" in
-		 * ssthresh(), which means that ca_state, lost bits and lost_out
-		 * counter would have to be faked before the call occurs. We
-		 * consider that too expensive, unlikely and hacky, so modules
-		 * using these in ssthresh() must deal these incompatibility
-		 * issues if they receives CA_EVENT_FRTO and frto_counter != 0
-		 */
-		tcp_ca_event(sk, CA_EVENT_FRTO);
-	}
-
-	tp->undo_marker = tp->snd_una;
-	tp->undo_retrans = 0;
-
-	skb = tcp_write_queue_head(sk);
-	if (TCP_SKB_CB(skb)->sacked & TCPCB_RETRANS)
-		tp->undo_marker = 0;
-	if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS) {
-		TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS;
-		tp->retrans_out -= tcp_skb_pcount(skb);
-	}
-	tcp_verify_left_out(tp);
-
-	/* Too bad if TCP was application limited */
-	tp->snd_cwnd = min(tp->snd_cwnd, tcp_packets_in_flight(tp) + 1);
-
-	/* Earlier loss recovery underway (see RFC4138; Appendix B).
-	 * The last condition is necessary at least in tp->frto_counter case.
-	 */
-	if (tcp_is_sackfrto(tp) && (tp->frto_counter ||
-	    ((1 << icsk->icsk_ca_state) & (TCPF_CA_Recovery|TCPF_CA_Loss))) &&
-	    after(tp->high_seq, tp->snd_una)) {
-		tp->frto_highmark = tp->high_seq;
-	} else {
-		tp->frto_highmark = tp->snd_nxt;
-	}
-	tcp_set_ca_state(sk, TCP_CA_Disorder);
-	tp->high_seq = tp->snd_nxt;
-	tp->frto_counter = 1;
-}
-
-/* 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, int allowed_segments, int flag)
-{
-	struct tcp_sock *tp = tcp_sk(sk);
-	struct sk_buff *skb;
-
-	tp->lost_out = 0;
-	tp->retrans_out = 0;
-	if (tcp_is_reno(tp))
-		tcp_reset_reno_sack(tp);
-
-	tcp_for_write_queue(skb, sk) {
-		if (skb == tcp_send_head(sk))
-			break;
-
-		TCP_SKB_CB(skb)->sacked &= ~TCPCB_LOST;
-		/*
-		 * Count the retransmission made on RTO correctly (only when
-		 * waiting for the first ACK and did not get it)...
-		 */
-		if ((tp->frto_counter == 1) && !(flag & FLAG_DATA_ACKED)) {
-			/* For some reason this R-bit might get cleared? */
-			if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS)
-				tp->retrans_out += tcp_skb_pcount(skb);
-			/* ...enter this if branch just for the first segment */
-			flag |= FLAG_DATA_ACKED;
-		} else {
-			if (TCP_SKB_CB(skb)->sacked & TCPCB_RETRANS)
-				tp->undo_marker = 0;
-			TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS;
-		}
-
-		/* Marking forward transmissions that were made after RTO lost
-		 * can cause unnecessary retransmissions in some scenarios,
-		 * SACK blocks will mitigate that in some but not in all cases.
-		 * We used to not mark them but it was causing break-ups with
-		 * receivers that do only in-order receival.
-		 *
-		 * TODO: we could detect presence of such receiver and select
-		 * different behavior per flow.
-		 */
-		if (!(TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED)) {
-			TCP_SKB_CB(skb)->sacked |= TCPCB_LOST;
-			tp->lost_out += tcp_skb_pcount(skb);
-			tp->retransmit_high = TCP_SKB_CB(skb)->end_seq;
-		}
-	}
-	tcp_verify_left_out(tp);
-
-	tp->snd_cwnd = tcp_packets_in_flight(tp) + allowed_segments;
-	tp->snd_cwnd_cnt = 0;
-	tp->snd_cwnd_stamp = tcp_time_stamp;
-	tp->frto_counter = 0;
-
-	tp->reordering = min_t(unsigned int, tp->reordering,
-			       sysctl_tcp_reordering);
-	tcp_set_ca_state(sk, TCP_CA_Loss);
-	tp->high_seq = tp->snd_nxt;
-	TCP_ECN_queue_cwr(tp);
-
-	tcp_clear_all_retrans_hints(tp);
-}
-
 static void tcp_clear_retrans_partial(struct tcp_sock *tp)
 {
 	tp->retrans_out = 0;
@@ -2043,10 +1839,13 @@ void tcp_enter_loss(struct sock *sk, int how)
 	const struct inet_connection_sock *icsk = inet_csk(sk);
 	struct tcp_sock *tp = tcp_sk(sk);
 	struct sk_buff *skb;
+	bool new_recovery = false;
 
 	/* Reduce ssthresh if it has not yet been made inside this window. */
-	if (icsk->icsk_ca_state <= TCP_CA_Disorder || tp->snd_una == tp->high_seq ||
+	if (icsk->icsk_ca_state <= TCP_CA_Disorder ||
+	    !after(tp->high_seq, tp->snd_una) ||
 	    (icsk->icsk_ca_state == TCP_CA_Loss && !icsk->icsk_retransmits)) {
+		new_recovery = true;
 		tp->prior_ssthresh = tcp_current_ssthresh(sk);
 		tp->snd_ssthresh = icsk->icsk_ca_ops->ssthresh(sk);
 		tcp_ca_event(sk, CA_EVENT_LOSS);
@@ -2088,8 +1887,14 @@ void tcp_enter_loss(struct sock *sk, int how)
 	tcp_set_ca_state(sk, TCP_CA_Loss);
 	tp->high_seq = tp->snd_nxt;
 	TCP_ECN_queue_cwr(tp);
-	/* Abort F-RTO algorithm if one is in progress */
-	tp->frto_counter = 0;
+
+	/* F-RTO RFC5682 sec 3.1 step 1: retransmit SND.UNA if no previous
+	 * loss recovery is underway except recurring timeout(s) on
+	 * the same SND.UNA (sec 3.2). Disable F-RTO on path MTU probing
+	 */
+	tp->frto = sysctl_tcp_frto &&
+		   (new_recovery || icsk->icsk_retransmits) &&
+		   !inet_csk(sk)->icsk_mtup.probe_size;
 }
 
 /* If ACK arrived pointing to a remembered SACK, it means that our
@@ -2148,15 +1953,16 @@ static bool tcp_pause_early_retransmit(struct sock *sk, int flag)
 	 * max(RTT/4, 2msec) unless ack has ECE mark, no RTT samples
 	 * available, or RTO is scheduled to fire first.
 	 */
-	if (sysctl_tcp_early_retrans < 2 || (flag & FLAG_ECE) || !tp->srtt)
+	if (sysctl_tcp_early_retrans < 2 || sysctl_tcp_early_retrans > 3 ||
+	    (flag & FLAG_ECE) || !tp->srtt)
 		return false;
 
 	delay = max_t(unsigned long, (tp->srtt >> 5), msecs_to_jiffies(2));
 	if (!time_after(inet_csk(sk)->icsk_timeout, (jiffies + delay)))
 		return false;
 
-	inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, delay, TCP_RTO_MAX);
-	tp->early_retrans_delayed = 1;
+	inet_csk_reset_xmit_timer(sk, ICSK_TIME_EARLY_RETRANS, delay,
+				  TCP_RTO_MAX);
 	return true;
 }
 
@@ -2272,10 +2078,6 @@ static bool tcp_time_to_recover(struct sock *sk, int flag)
 	struct tcp_sock *tp = tcp_sk(sk);
 	__u32 packets_out;
 
-	/* Do not perform any recovery during F-RTO algorithm */
-	if (tp->frto_counter)
-		return false;
-
 	/* Trick#1: The loss is proven. */
 	if (tp->lost_out)
 		return true;
@@ -2319,7 +2121,7 @@ static bool tcp_time_to_recover(struct sock *sk, int flag)
 	 * interval if appropriate.
 	 */
 	if (tp->do_early_retrans && !tp->retrans_out && tp->sacked_out &&
-	    (tp->packets_out == (tp->sacked_out + 1) && tp->packets_out < 4) &&
+	    (tp->packets_out >= (tp->sacked_out + 1) && tp->packets_out < 4) &&
 	    !tcp_may_send_now(sk))
 		return !tcp_pause_early_retransmit(sk, flag);
 
@@ -2636,12 +2438,12 @@ static int tcp_try_undo_partial(struct sock *sk, int acked)
 	return failed;
 }
 
-/* Undo during loss recovery after partial ACK. */
-static bool tcp_try_undo_loss(struct sock *sk)
+/* 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 (tcp_may_undo(tp)) {
+	if (frto_undo || tcp_may_undo(tp)) {
 		struct sk_buff *skb;
 		tcp_for_write_queue(skb, sk) {
 			if (skb == tcp_send_head(sk))
@@ -2655,9 +2457,12 @@ static bool tcp_try_undo_loss(struct sock *sk)
 		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 (tcp_is_sack(tp))
+		if (frto_undo || tcp_is_sack(tp))
 			tcp_set_ca_state(sk, TCP_CA_Open);
 		return true;
 	}
@@ -2679,6 +2484,7 @@ static void tcp_init_cwnd_reduction(struct sock *sk, const bool set_ssthresh)
 	struct tcp_sock *tp = tcp_sk(sk);
 
 	tp->high_seq = tp->snd_nxt;
+	tp->tlp_high_seq = 0;
 	tp->snd_cwnd_cnt = 0;
 	tp->prior_cwnd = tp->snd_cwnd;
 	tp->prr_delivered = 0;
@@ -2756,7 +2562,7 @@ static void tcp_try_to_open(struct sock *sk, int flag, int newly_acked_sacked)
 
 	tcp_verify_left_out(tp);
 
-	if (!tp->frto_counter && !tcp_any_retrans_done(sk))
+	if (!tcp_any_retrans_done(sk))
 		tp->retrans_stamp = 0;
 
 	if (flag & FLAG_ECE)
@@ -2873,6 +2679,58 @@ static void tcp_enter_recovery(struct sock *sk, bool ece_ack)
 	tcp_set_ca_state(sk, TCP_CA_Recovery);
 }
 
+/* Process an ACK in CA_Loss state. Move to CA_Open if lost data are
+ * recovered or spurious. Otherwise retransmits more on partial ACKs.
+ */
+static void tcp_process_loss(struct sock *sk, int flag, bool is_dupack)
+{
+	struct inet_connection_sock *icsk = inet_csk(sk);
+	struct tcp_sock *tp = tcp_sk(sk);
+	bool recovered = !before(tp->snd_una, tp->high_seq);
+
+	if (tp->frto) { /* F-RTO RFC5682 sec 3.1 (sack enhanced version). */
+		if (flag & FLAG_ORIG_SACK_ACKED) {
+			/* Step 3.b. A timeout is spurious if not all data are
+			 * lost, i.e., never-retransmitted data are (s)acked.
+			 */
+			tcp_try_undo_loss(sk, true);
+			return;
+		}
+		if (after(tp->snd_nxt, tp->high_seq) &&
+		    (flag & FLAG_DATA_SACKED || is_dupack)) {
+			tp->frto = 0; /* Loss was real: 2nd part of step 3.a */
+		} else if (flag & FLAG_SND_UNA_ADVANCED && !recovered) {
+			tp->high_seq = tp->snd_nxt;
+			__tcp_push_pending_frames(sk, tcp_current_mss(sk),
+						  TCP_NAGLE_OFF);
+			if (after(tp->snd_nxt, tp->high_seq))
+				return; /* Step 2.b */
+			tp->frto = 0;
+		}
+	}
+
+	if (recovered) {
+		/* F-RTO RFC5682 sec 3.1 step 2.a and 1st part of step 3.a */
+		icsk->icsk_retransmits = 0;
+		tcp_try_undo_recovery(sk);
+		return;
+	}
+	if (flag & FLAG_DATA_ACKED)
+		icsk->icsk_retransmits = 0;
+	if (tcp_is_reno(tp)) {
+		/* A Reno DUPACK means new data in F-RTO step 2.b above are
+		 * delivered. Lower inflight to clock out (re)tranmissions.
+		 */
+		if (after(tp->snd_nxt, tp->high_seq) && is_dupack)
+			tcp_add_reno_sack(sk);
+		else if (flag & FLAG_SND_UNA_ADVANCED)
+			tcp_reset_reno_sack(tp);
+	}
+	if (tcp_try_undo_loss(sk, false))
+		return;
+	tcp_xmit_retransmit_queue(sk);
+}
+
 /* 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
@@ -2919,12 +2777,6 @@ static void tcp_fastretrans_alert(struct sock *sk, int pkts_acked,
 		tp->retrans_stamp = 0;
 	} else if (!before(tp->snd_una, tp->high_seq)) {
 		switch (icsk->icsk_ca_state) {
-		case TCP_CA_Loss:
-			icsk->icsk_retransmits = 0;
-			if (tcp_try_undo_recovery(sk))
-				return;
-			break;
-
 		case TCP_CA_CWR:
 			/* CWR is to be held something *above* high_seq
 			 * is ACKed for CWR bit to reach receiver. */
@@ -2955,18 +2807,10 @@ static void tcp_fastretrans_alert(struct sock *sk, int pkts_acked,
 		newly_acked_sacked = pkts_acked + tp->sacked_out - prior_sacked;
 		break;
 	case TCP_CA_Loss:
-		if (flag & FLAG_DATA_ACKED)
-			icsk->icsk_retransmits = 0;
-		if (tcp_is_reno(tp) && flag & FLAG_SND_UNA_ADVANCED)
-			tcp_reset_reno_sack(tp);
-		if (!tcp_try_undo_loss(sk)) {
-			tcp_moderate_cwnd(tp);
-			tcp_xmit_retransmit_queue(sk);
-			return;
-		}
+		tcp_process_loss(sk, flag, is_dupack);
 		if (icsk->icsk_ca_state != TCP_CA_Open)
 			return;
-		/* Loss is undone; fall through to processing in Open state. */
+		/* Fall through to processing in Open state. */
 	default:
 		if (tcp_is_reno(tp)) {
 			if (flag & FLAG_SND_UNA_ADVANCED)
@@ -3079,6 +2923,7 @@ static void tcp_cong_avoid(struct sock *sk, u32 ack, u32 in_flight)
  */
 void tcp_rearm_rto(struct sock *sk)
 {
+	const struct inet_connection_sock *icsk = inet_csk(sk);
 	struct tcp_sock *tp = tcp_sk(sk);
 
 	/* If the retrans timer is currently being used by Fast Open
@@ -3092,12 +2937,13 @@ void tcp_rearm_rto(struct sock *sk)
 	} else {
 		u32 rto = inet_csk(sk)->icsk_rto;
 		/* Offset the time elapsed after installing regular RTO */
-		if (tp->early_retrans_delayed) {
+		if (icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS ||
+		    icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) {
 			struct sk_buff *skb = tcp_write_queue_head(sk);
 			const u32 rto_time_stamp = TCP_SKB_CB(skb)->when + rto;
 			s32 delta = (s32)(rto_time_stamp - tcp_time_stamp);
 			/* delta may not be positive if the socket is locked
-			 * when the delayed ER timer fires and is rescheduled.
+			 * when the retrans timer fires and is rescheduled.
 			 */
 			if (delta > 0)
 				rto = delta;
@@ -3105,7 +2951,6 @@ void tcp_rearm_rto(struct sock *sk)
 		inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, rto,
 					  TCP_RTO_MAX);
 	}
-	tp->early_retrans_delayed = 0;
 }
 
 /* This function is called when the delayed ER timer fires. TCP enters
@@ -3193,8 +3038,6 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets,
 			flag |= FLAG_RETRANS_DATA_ACKED;
 			ca_seq_rtt = -1;
 			seq_rtt = -1;
-			if ((flag & FLAG_DATA_ACKED) || (acked_pcount > 1))
-				flag |= FLAG_NONHEAD_RETRANS_ACKED;
 		} else {
 			ca_seq_rtt = now - scb->when;
 			last_ackt = skb->tstamp;
@@ -3203,6 +3046,8 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets,
 			}
 			if (!(sacked & TCPCB_SACKED_ACKED))
 				reord = min(pkts_acked, reord);
+			if (!after(scb->end_seq, tp->high_seq))
+				flag |= FLAG_ORIG_SACK_ACKED;
 		}
 
 		if (sacked & TCPCB_SACKED_ACKED)
@@ -3403,150 +3248,6 @@ static int tcp_ack_update_window(struct sock *sk, const struct sk_buff *skb, u32
 	return flag;
 }
 
-/* A very conservative spurious RTO response algorithm: reduce cwnd and
- * continue in congestion avoidance.
- */
-static void tcp_conservative_spur_to_response(struct tcp_sock *tp)
-{
-	tp->snd_cwnd = min(tp->snd_cwnd, tp->snd_ssthresh);
-	tp->snd_cwnd_cnt = 0;
-	TCP_ECN_queue_cwr(tp);
-	tcp_moderate_cwnd(tp);
-}
-
-/* A conservative spurious RTO response algorithm: reduce cwnd using
- * PRR and continue in congestion avoidance.
- */
-static void tcp_cwr_spur_to_response(struct sock *sk)
-{
-	tcp_enter_cwr(sk, 0);
-}
-
-static void tcp_undo_spur_to_response(struct sock *sk, int flag)
-{
-	if (flag & FLAG_ECE)
-		tcp_cwr_spur_to_response(sk);
-	else
-		tcp_undo_cwr(sk, true);
-}
-
-/* F-RTO spurious RTO detection algorithm (RFC4138)
- *
- * F-RTO affects during two new ACKs following RTO (well, almost, see inline
- * comments). State (ACK number) is kept in frto_counter. When ACK advances
- * window (but not to or beyond highest sequence sent before RTO):
- *   On First ACK,  send two new segments out.
- *   On Second ACK, RTO was likely spurious. Do spurious response (response
- *                  algorithm is not part of the F-RTO detection algorithm
- *                  given in RFC4138 but can be selected separately).
- * Otherwise (basically on duplicate ACK), RTO was (likely) caused by a loss
- * and TCP falls back to conventional RTO recovery. F-RTO allows overriding
- * of Nagle, this is done using frto_counter states 2 and 3, when a new data
- * segment of any size sent during F-RTO, state 2 is upgraded to 3.
- *
- * Rationale: if the RTO was spurious, new ACKs should arrive from the
- * original window even after we transmit two new data segments.
- *
- * SACK version:
- *   on first step, wait until first cumulative ACK arrives, then move to
- *   the second step. In second step, the next ACK decides.
- *
- * F-RTO is implemented (mainly) in four functions:
- *   - tcp_use_frto() is used to determine if TCP is can use F-RTO
- *   - tcp_enter_frto() prepares TCP state on RTO if F-RTO is used, it is
- *     called when tcp_use_frto() showed green light
- *   - tcp_process_frto() handles incoming ACKs during F-RTO algorithm
- *   - tcp_enter_frto_loss() is called if there is not enough evidence
- *     to prove that the RTO is indeed spurious. It transfers the control
- *     from F-RTO to the conventional RTO recovery
- */
-static bool tcp_process_frto(struct sock *sk, int flag)
-{
-	struct tcp_sock *tp = tcp_sk(sk);
-
-	tcp_verify_left_out(tp);
-
-	/* Duplicate the behavior from Loss state (fastretrans_alert) */
-	if (flag & FLAG_DATA_ACKED)
-		inet_csk(sk)->icsk_retransmits = 0;
-
-	if ((flag & FLAG_NONHEAD_RETRANS_ACKED) ||
-	    ((tp->frto_counter >= 2) && (flag & FLAG_RETRANS_DATA_ACKED)))
-		tp->undo_marker = 0;
-
-	if (!before(tp->snd_una, tp->frto_highmark)) {
-		tcp_enter_frto_loss(sk, (tp->frto_counter == 1 ? 2 : 3), flag);
-		return true;
-	}
-
-	if (!tcp_is_sackfrto(tp)) {
-		/* RFC4138 shortcoming in step 2; should also have case c):
-		 * ACK isn't duplicate nor advances window, e.g., opposite dir
-		 * data, winupdate
-		 */
-		if (!(flag & FLAG_ANY_PROGRESS) && (flag & FLAG_NOT_DUP))
-			return true;
-
-		if (!(flag & FLAG_DATA_ACKED)) {
-			tcp_enter_frto_loss(sk, (tp->frto_counter == 1 ? 0 : 3),
-					    flag);
-			return true;
-		}
-	} else {
-		if (!(flag & FLAG_DATA_ACKED) && (tp->frto_counter == 1)) {
-			if (!tcp_packets_in_flight(tp)) {
-				tcp_enter_frto_loss(sk, 2, flag);
-				return true;
-			}
-
-			/* Prevent sending of new data. */
-			tp->snd_cwnd = min(tp->snd_cwnd,
-					   tcp_packets_in_flight(tp));
-			return true;
-		}
-
-		if ((tp->frto_counter >= 2) &&
-		    (!(flag & FLAG_FORWARD_PROGRESS) ||
-		     ((flag & FLAG_DATA_SACKED) &&
-		      !(flag & FLAG_ONLY_ORIG_SACKED)))) {
-			/* RFC4138 shortcoming (see comment above) */
-			if (!(flag & FLAG_FORWARD_PROGRESS) &&
-			    (flag & FLAG_NOT_DUP))
-				return true;
-
-			tcp_enter_frto_loss(sk, 3, flag);
-			return true;
-		}
-	}
-
-	if (tp->frto_counter == 1) {
-		/* tcp_may_send_now needs to see updated state */
-		tp->snd_cwnd = tcp_packets_in_flight(tp) + 2;
-		tp->frto_counter = 2;
-
-		if (!tcp_may_send_now(sk))
-			tcp_enter_frto_loss(sk, 2, flag);
-
-		return true;
-	} else {
-		switch (sysctl_tcp_frto_response) {
-		case 2:
-			tcp_undo_spur_to_response(sk, flag);
-			break;
-		case 1:
-			tcp_conservative_spur_to_response(tp);
-			break;
-		default:
-			tcp_cwr_spur_to_response(sk);
-			break;
-		}
-		tp->frto_counter = 0;
-		tp->undo_marker = 0;
-		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPSPURIOUSRTOS);
-	}
-	return false;
-}
-
 /* RFC 5961 7 [ACK Throttling] */
 static void tcp_send_challenge_ack(struct sock *sk)
 {
@@ -3586,6 +3287,38 @@ static void tcp_replace_ts_recent(struct tcp_sock *tp, u32 seq)
 	}
 }
 
+/* This routine deals with acks during a TLP episode.
+ * Ref: loss detection algorithm in draft-dukkipati-tcpm-tcp-loss-probe.
+ */
+static void tcp_process_tlp_ack(struct sock *sk, u32 ack, int flag)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	bool is_tlp_dupack = (ack == tp->tlp_high_seq) &&
+			     !(flag & (FLAG_SND_UNA_ADVANCED |
+				       FLAG_NOT_DUP | FLAG_DATA_SACKED));
+
+	/* Mark the end of TLP episode on receiving TLP dupack or when
+	 * ack is after tlp_high_seq.
+	 */
+	if (is_tlp_dupack) {
+		tp->tlp_high_seq = 0;
+		return;
+	}
+
+	if (after(ack, tp->tlp_high_seq)) {
+		tp->tlp_high_seq = 0;
+		/* Don't reduce cwnd if DSACK arrives for TLP retrans. */
+		if (!(flag & FLAG_DSACKING_ACK)) {
+			tcp_init_cwnd_reduction(sk, true);
+			tcp_set_ca_state(sk, TCP_CA_CWR);
+			tcp_end_cwnd_reduction(sk);
+			tcp_set_ca_state(sk, TCP_CA_Open);
+			NET_INC_STATS_BH(sock_net(sk),
+					 LINUX_MIB_TCPLOSSPROBERECOVERY);
+		}
+	}
+}
+
 /* This routine deals with incoming acks, but not outgoing ones. */
 static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
 {
@@ -3600,7 +3333,6 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
 	int prior_packets;
 	int prior_sacked = tp->sacked_out;
 	int pkts_acked = 0;
-	bool frto_cwnd = false;
 
 	/* If the ack is older than previous acks
 	 * then we can probably ignore it.
@@ -3620,7 +3352,8 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
 	if (after(ack, tp->snd_nxt))
 		goto invalid_ack;
 
-	if (tp->early_retrans_delayed)
+	if (icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS ||
+	    icsk->icsk_pending == ICSK_TIME_LOSS_PROBE)
 		tcp_rearm_rto(sk);
 
 	if (after(ack, prior_snd_una))
@@ -3679,30 +3412,29 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
 
 	pkts_acked = prior_packets - tp->packets_out;
 
-	if (tp->frto_counter)
-		frto_cwnd = tcp_process_frto(sk, flag);
-	/* Guarantee sacktag reordering detection against wrap-arounds */
-	if (before(tp->frto_highmark, tp->snd_una))
-		tp->frto_highmark = 0;
-
 	if (tcp_ack_is_dubious(sk, flag)) {
 		/* Advance CWND, if state allows this. */
-		if ((flag & FLAG_DATA_ACKED) && !frto_cwnd &&
-		    tcp_may_raise_cwnd(sk, flag))
+		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,
 				      is_dupack, flag);
 	} else {
-		if ((flag & FLAG_DATA_ACKED) && !frto_cwnd)
+		if (flag & FLAG_DATA_ACKED)
 			tcp_cong_avoid(sk, ack, prior_in_flight);
 	}
 
+	if (tp->tlp_high_seq)
+		tcp_process_tlp_ack(sk, ack, flag);
+
 	if ((flag & FLAG_FORWARD_PROGRESS) || !(flag & FLAG_NOT_DUP)) {
 		struct dst_entry *dst = __sk_dst_get(sk);
 		if (dst)
 			dst_confirm(dst);
 	}
+
+	if (icsk->icsk_pending == ICSK_TIME_RETRANS)
+		tcp_schedule_loss_probe(sk);
 	return 1;
 
 no_queue:
@@ -3716,6 +3448,9 @@ no_queue:
 	 */
 	if (tcp_send_head(sk))
 		tcp_ack_probe(sk);
+
+	if (tp->tlp_high_seq)
+		tcp_process_tlp_ack(sk, ack, flag);
 	return 1;
 
 invalid_ack:
@@ -3740,8 +3475,8 @@ old_ack:
  * But, this can also be called on packets in the established flow when
  * the fast version below fails.
  */
-void tcp_parse_options(const struct sk_buff *skb, struct tcp_options_received *opt_rx,
-		       const u8 **hvpp, int estab,
+void tcp_parse_options(const struct sk_buff *skb,
+		       struct tcp_options_received *opt_rx, int estab,
 		       struct tcp_fastopen_cookie *foc)
 {
 	const unsigned char *ptr;
@@ -3825,31 +3560,6 @@ void tcp_parse_options(const struct sk_buff *skb, struct tcp_options_received *o
 				 */
 				break;
 #endif
-			case TCPOPT_COOKIE:
-				/* This option is variable length.
-				 */
-				switch (opsize) {
-				case TCPOLEN_COOKIE_BASE:
-					/* not yet implemented */
-					break;
-				case TCPOLEN_COOKIE_PAIR:
-					/* not yet implemented */
-					break;
-				case TCPOLEN_COOKIE_MIN+0:
-				case TCPOLEN_COOKIE_MIN+2:
-				case TCPOLEN_COOKIE_MIN+4:
-				case TCPOLEN_COOKIE_MIN+6:
-				case TCPOLEN_COOKIE_MAX:
-					/* 16-bit multiple */
-					opt_rx->cookie_plus = opsize;
-					*hvpp = ptr;
-					break;
-				default:
-					/* ignore option */
-					break;
-				}
-				break;
-
 			case TCPOPT_EXP:
 				/* Fast Open option shares code 254 using a
 				 * 16 bits magic number. It's valid only in
@@ -3895,8 +3605,7 @@ static bool tcp_parse_aligned_timestamp(struct tcp_sock *tp, const struct tcphdr
  * If it is wrong it falls back on tcp_parse_options().
  */
 static bool tcp_fast_parse_options(const struct sk_buff *skb,
-				   const struct tcphdr *th,
-				   struct tcp_sock *tp, const u8 **hvpp)
+				   const struct tcphdr *th, struct tcp_sock *tp)
 {
 	/* In the spirit of fast parsing, compare doff directly to constant
 	 * values.  Because equality is used, short doff can be ignored here.
@@ -3910,7 +3619,7 @@ static bool tcp_fast_parse_options(const struct sk_buff *skb,
 			return true;
 	}
 
-	tcp_parse_options(skb, &tp->rx_opt, hvpp, 1, NULL);
+	tcp_parse_options(skb, &tp->rx_opt, 1, NULL);
 	if (tp->rx_opt.saw_tstamp)
 		tp->rx_opt.rcv_tsecr -= tp->tsoffset;
 
@@ -5270,12 +4979,10 @@ out:
 static bool tcp_validate_incoming(struct sock *sk, struct sk_buff *skb,
 				  const struct tcphdr *th, int syn_inerr)
 {
-	const u8 *hash_location;
 	struct tcp_sock *tp = tcp_sk(sk);
 
 	/* RFC1323: H1. Apply PAWS check first. */
-	if (tcp_fast_parse_options(skb, th, tp, &hash_location) &&
-	    tp->rx_opt.saw_tstamp &&
+	if (tcp_fast_parse_options(skb, th, tp) && tp->rx_opt.saw_tstamp &&
 	    tcp_paws_discard(sk, skb)) {
 		if (!th->rst) {
 			NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_PAWSESTABREJECTED);
@@ -5566,6 +5273,7 @@ step5:
 	return 0;
 
 csum_error:
+	TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_CSUMERRORS);
 	TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_INERRS);
 
 discard:
@@ -5624,12 +5332,11 @@ static bool tcp_rcv_fastopen_synack(struct sock *sk, struct sk_buff *synack,
 
 	if (mss == tp->rx_opt.user_mss) {
 		struct tcp_options_received opt;
-		const u8 *hash_location;
 
 		/* Get original SYNACK MSS value if user MSS sets mss_clamp */
 		tcp_clear_options(&opt);
 		opt.user_mss = opt.mss_clamp = 0;
-		tcp_parse_options(synack, &opt, &hash_location, 0, NULL);
+		tcp_parse_options(synack, &opt, 0, NULL);
 		mss = opt.mss_clamp;
 	}
 
@@ -5660,14 +5367,12 @@ static bool tcp_rcv_fastopen_synack(struct sock *sk, struct sk_buff *synack,
 static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
 					 const struct tcphdr *th, unsigned int len)
 {
-	const u8 *hash_location;
 	struct inet_connection_sock *icsk = inet_csk(sk);
 	struct tcp_sock *tp = tcp_sk(sk);
-	struct tcp_cookie_values *cvp = tp->cookie_values;
 	struct tcp_fastopen_cookie foc = { .len = -1 };
 	int saved_clamp = tp->rx_opt.mss_clamp;
 
-	tcp_parse_options(skb, &tp->rx_opt, &hash_location, 0, &foc);
+	tcp_parse_options(skb, &tp->rx_opt, 0, &foc);
 	if (tp->rx_opt.saw_tstamp)
 		tp->rx_opt.rcv_tsecr -= tp->tsoffset;
 
@@ -5764,30 +5469,6 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
 		 * is initialized. */
 		tp->copied_seq = tp->rcv_nxt;
 
-		if (cvp != NULL &&
-		    cvp->cookie_pair_size > 0 &&
-		    tp->rx_opt.cookie_plus > 0) {
-			int cookie_size = tp->rx_opt.cookie_plus
-					- TCPOLEN_COOKIE_BASE;
-			int cookie_pair_size = cookie_size
-					     + cvp->cookie_desired;
-
-			/* A cookie extension option was sent and returned.
-			 * Note that each incoming SYNACK replaces the
-			 * Responder cookie.  The initial exchange is most
-			 * fragile, as protection against spoofing relies
-			 * entirely upon the sequence and timestamp (above).
-			 * This replacement strategy allows the correct pair to
-			 * pass through, while any others will be filtered via
-			 * Responder verification later.
-			 */
-			if (sizeof(cvp->cookie_pair) >= cookie_pair_size) {
-				memcpy(&cvp->cookie_pair[cvp->cookie_desired],
-				       hash_location, cookie_size);
-				cvp->cookie_pair_size = cookie_pair_size;
-			}
-		}
-
 		smp_mb();
 
 		tcp_finish_connect(sk, skb);