Merge remote-tracking branch 'net-next/master'

1 files changed, 106 insertions, 75 deletions

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 0bc9e46a5369..53dc1267c85e 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -42,6 +42,8 @@
 #include <linux/gfp.h>
 #include <linux/module.h>
 
+#include <trace/events/tcp.h>
+
 /* People can turn this off for buggy TCP's found in printers etc. */
 int sysctl_tcp_retrans_collapse __read_mostly = 1;
 
@@ -66,15 +68,17 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle,
 			   int push_one, gfp_t gfp);
 
 /* Account for new data that has been sent to the network. */
-static void tcp_event_new_data_sent(struct sock *sk, const struct sk_buff *skb)
+static void tcp_event_new_data_sent(struct sock *sk, struct sk_buff *skb)
 {
 	struct inet_connection_sock *icsk = inet_csk(sk);
 	struct tcp_sock *tp = tcp_sk(sk);
 	unsigned int prior_packets = tp->packets_out;
 
-	tcp_advance_send_head(sk, skb);
 	tp->snd_nxt = TCP_SKB_CB(skb)->end_seq;
 
+	__skb_unlink(skb, &sk->sk_write_queue);
+	tcp_rbtree_insert(&sk->tcp_rtx_queue, skb);
+
 	tp->packets_out += tcp_skb_pcount(skb);
 	if (!prior_packets || icsk->icsk_pending == ICSK_TIME_LOSS_PROBE)
 		tcp_rearm_rto(sk);
@@ -971,6 +975,12 @@ static void tcp_internal_pacing(struct sock *sk, const struct sk_buff *skb)
 		      HRTIMER_MODE_ABS_PINNED);
 }
 
+static void tcp_update_skb_after_send(struct tcp_sock *tp, struct sk_buff *skb)
+{
+	skb->skb_mstamp = tp->tcp_mstamp;
+	list_move_tail(&skb->tcp_tsorted_anchor, &tp->tsorted_sent_queue);
+}
+
 /* This routine actually transmits TCP packets queued in by
  * tcp_do_sendmsg().  This is used by both the initial
  * transmission and possible later retransmissions.
@@ -1003,10 +1013,14 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
 		TCP_SKB_CB(skb)->tx.in_flight = TCP_SKB_CB(skb)->end_seq
 			- tp->snd_una;
 		oskb = skb;
-		if (unlikely(skb_cloned(skb)))
-			skb = pskb_copy(skb, gfp_mask);
-		else
-			skb = skb_clone(skb, gfp_mask);
+
+		tcp_skb_tsorted_save(oskb) {
+			if (unlikely(skb_cloned(oskb)))
+				skb = pskb_copy(oskb, gfp_mask);
+			else
+				skb = skb_clone(oskb, gfp_mask);
+		} tcp_skb_tsorted_restore(oskb);
+
 		if (unlikely(!skb))
 			return -ENOBUFS;
 	}
@@ -1127,7 +1141,7 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
 		err = net_xmit_eval(err);
 	}
 	if (!err && oskb) {
-		oskb->skb_mstamp = tp->tcp_mstamp;
+		tcp_update_skb_after_send(tp, oskb);
 		tcp_rate_skb_sent(sk, oskb);
 	}
 	return err;
@@ -1239,12 +1253,25 @@ static void tcp_skb_fragment_eor(struct sk_buff *skb, struct sk_buff *skb2)
 	TCP_SKB_CB(skb)->eor = 0;
 }
 
+/* Insert buff after skb on the write or rtx queue of sk.  */
+static void tcp_insert_write_queue_after(struct sk_buff *skb,
+					 struct sk_buff *buff,
+					 struct sock *sk,
+					 enum tcp_queue tcp_queue)
+{
+	if (tcp_queue == TCP_FRAG_IN_WRITE_QUEUE)
+		__skb_queue_after(&sk->sk_write_queue, skb, buff);
+	else
+		tcp_rbtree_insert(&sk->tcp_rtx_queue, buff);
+}
+
 /* Function to create two new TCP segments.  Shrinks the given segment
  * to the specified size and appends a new segment with the rest of the
  * packet to the list.  This won't be called frequently, I hope.
  * Remember, these are still headerless SKBs at this point.
  */
-int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len,
+int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue,
+		 struct sk_buff *skb, u32 len,
 		 unsigned int mss_now, gfp_t gfp)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
@@ -1327,7 +1354,8 @@ int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len,
 
 	/* Link BUFF into the send queue. */
 	__skb_header_release(buff);
-	tcp_insert_write_queue_after(skb, buff, sk);
+	tcp_insert_write_queue_after(skb, buff, sk, tcp_queue);
+	list_add(&buff->tcp_tsorted_anchor, &skb->tcp_tsorted_anchor);
 
 	return 0;
 }
@@ -1614,10 +1642,10 @@ static void tcp_cwnd_validate(struct sock *sk, bool is_cwnd_limited)
 		 * is caused by insufficient sender buffer:
 		 * 1) just sent some data (see tcp_write_xmit)
 		 * 2) not cwnd limited (this else condition)
-		 * 3) no more data to send (null tcp_send_head )
+		 * 3) no more data to send (tcp_write_queue_empty())
 		 * 4) application is hitting buffer limit (SOCK_NOSPACE)
 		 */
-		if (!tcp_send_head(sk) && sk->sk_socket &&
+		if (tcp_write_queue_empty(sk) && sk->sk_socket &&
 		    test_bit(SOCK_NOSPACE, &sk->sk_socket->flags) &&
 		    (1 << sk->sk_state) & (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT))
 			tcp_chrono_start(sk, TCP_CHRONO_SNDBUF_LIMITED);
@@ -1813,7 +1841,8 @@ static bool tcp_snd_wnd_test(const struct tcp_sock *tp,
  * know that all the data is in scatter-gather pages, and that the
  * packet has never been sent out before (and thus is not cloned).
  */
-static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len,
+static int tso_fragment(struct sock *sk, enum tcp_queue tcp_queue,
+			struct sk_buff *skb, unsigned int len,
 			unsigned int mss_now, gfp_t gfp)
 {
 	struct sk_buff *buff;
@@ -1822,7 +1851,7 @@ static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len,
 
 	/* All of a TSO frame must be composed of paged data.  */
 	if (skb->len != skb->data_len)
-		return tcp_fragment(sk, skb, len, mss_now, gfp);
+		return tcp_fragment(sk, tcp_queue, skb, len, mss_now, gfp);
 
 	buff = sk_stream_alloc_skb(sk, 0, gfp, true);
 	if (unlikely(!buff))
@@ -1858,7 +1887,7 @@ static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len,
 
 	/* Link BUFF into the send queue. */
 	__skb_header_release(buff);
-	tcp_insert_write_queue_after(skb, buff, sk);
+	tcp_insert_write_queue_after(skb, buff, sk, tcp_queue);
 
 	return 0;
 }
@@ -1928,8 +1957,10 @@ static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb,
 			goto send_now;
 	}
 
-	head = tcp_write_queue_head(sk);
-
+	/* TODO : use tsorted_sent_queue ? */
+	head = tcp_rtx_queue_head(sk);
+	if (!head)
+		goto send_now;
 	age = tcp_stamp_us_delta(tp->tcp_mstamp, head->skb_mstamp);
 	/* If next ACK is likely to come too late (half srtt), do not defer */
 	if (age < (tp->srtt_us >> 4))
@@ -2147,13 +2178,12 @@ static bool tcp_small_queue_check(struct sock *sk, const struct sk_buff *skb,
 	limit <<= factor;
 
 	if (refcount_read(&sk->sk_wmem_alloc) > limit) {
-		/* Always send the 1st or 2nd skb in write queue.
+		/* Always send skb if rtx queue is empty.
 		 * No need to wait for TX completion to call us back,
 		 * after softirq/tasklet schedule.
 		 * This helps when TX completions are delayed too much.
 		 */
-		if (skb == sk->sk_write_queue.next ||
-		    skb->prev == sk->sk_write_queue.next)
+		if (tcp_rtx_queue_empty(sk))
 			return false;
 
 		set_bit(TSQ_THROTTLED, &sk->sk_tsq_flags);
@@ -2204,7 +2234,7 @@ void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type)
 	 * it's the "most interesting" or current chrono we are
 	 * tracking and starts busy chrono if we have pending data.
 	 */
-	if (tcp_write_queue_empty(sk))
+	if (tcp_rtx_and_write_queues_empty(sk))
 		tcp_chrono_set(tp, TCP_CHRONO_UNSPEC);
 	else if (type == tp->chrono_type)
 		tcp_chrono_set(tp, TCP_CHRONO_BUSY);
@@ -2260,7 +2290,7 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle,
 
 		if (unlikely(tp->repair) && tp->repair_queue == TCP_SEND_QUEUE) {
 			/* "skb_mstamp" is used as a start point for the retransmit timer */
-			skb->skb_mstamp = tp->tcp_mstamp;
+			tcp_update_skb_after_send(tp, skb);
 			goto repair; /* Skip network transmission */
 		}
 
@@ -2299,7 +2329,8 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle,
 						    nonagle);
 
 		if (skb->len > limit &&
-		    unlikely(tso_fragment(sk, skb, limit, mss_now, gfp)))
+		    unlikely(tso_fragment(sk, TCP_FRAG_IN_WRITE_QUEUE,
+					  skb, limit, mss_now, gfp)))
 			break;
 
 		if (test_bit(TCP_TSQ_DEFERRED, &sk->sk_tsq_flags))
@@ -2339,7 +2370,7 @@ repair:
 		tcp_cwnd_validate(sk, is_cwnd_limited);
 		return false;
 	}
-	return !tp->packets_out && tcp_send_head(sk);
+	return !tp->packets_out && !tcp_write_queue_empty(sk);
 }
 
 bool tcp_schedule_loss_probe(struct sock *sk)
@@ -2363,7 +2394,7 @@ bool tcp_schedule_loss_probe(struct sock *sk)
 		return false;
 
 	if ((tp->snd_cwnd > tcp_packets_in_flight(tp)) &&
-	     tcp_send_head(sk))
+	     !tcp_write_queue_empty(sk))
 		return false;
 
 	/* Probe timeout is 2*rtt. Add minimum RTO to account
@@ -2416,18 +2447,14 @@ void tcp_send_loss_probe(struct sock *sk)
 	int mss = tcp_current_mss(sk);
 
 	skb = tcp_send_head(sk);
-	if (skb) {
-		if (tcp_snd_wnd_test(tp, skb, mss)) {
-			pcount = tp->packets_out;
-			tcp_write_xmit(sk, mss, TCP_NAGLE_OFF, 2, GFP_ATOMIC);
-			if (tp->packets_out > pcount)
-				goto probe_sent;
-			goto rearm_timer;
-		}
-		skb = tcp_write_queue_prev(sk, skb);
-	} else {
-		skb = tcp_write_queue_tail(sk);
+	if (skb && tcp_snd_wnd_test(tp, skb, mss)) {
+		pcount = tp->packets_out;
+		tcp_write_xmit(sk, mss, TCP_NAGLE_OFF, 2, GFP_ATOMIC);
+		if (tp->packets_out > pcount)
+			goto probe_sent;
+		goto rearm_timer;
 	}
+	skb = skb_rb_last(&sk->tcp_rtx_queue);
 
 	/* At most one outstanding TLP retransmission. */
 	if (tp->tlp_high_seq)
@@ -2445,10 +2472,11 @@ void tcp_send_loss_probe(struct sock *sk)
 		goto rearm_timer;
 
 	if ((pcount > 1) && (skb->len > (pcount - 1) * mss)) {
-		if (unlikely(tcp_fragment(sk, skb, (pcount - 1) * mss, mss,
+		if (unlikely(tcp_fragment(sk, TCP_FRAG_IN_RTX_QUEUE, skb,
+					  (pcount - 1) * mss, mss,
 					  GFP_ATOMIC)))
 			goto rearm_timer;
-		skb = tcp_write_queue_next(sk, skb);
+		skb = skb_rb_next(skb);
 	}
 
 	if (WARN_ON(!skb || !tcp_skb_pcount(skb)))
@@ -2648,7 +2676,7 @@ void tcp_skb_collapse_tstamp(struct sk_buff *skb,
 static bool tcp_collapse_retrans(struct sock *sk, struct sk_buff *skb)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
-	struct sk_buff *next_skb = tcp_write_queue_next(sk, skb);
+	struct sk_buff *next_skb = skb_rb_next(skb);
 	int skb_size, next_skb_size;
 
 	skb_size = skb->len;
@@ -2665,8 +2693,6 @@ static bool tcp_collapse_retrans(struct sock *sk, struct sk_buff *skb)
 	}
 	tcp_highest_sack_combine(sk, next_skb, skb);
 
-	tcp_unlink_write_queue(next_skb, sk);
-
 	if (next_skb->ip_summed == CHECKSUM_PARTIAL)
 		skb->ip_summed = CHECKSUM_PARTIAL;
 
@@ -2694,7 +2720,7 @@ static bool tcp_collapse_retrans(struct sock *sk, struct sk_buff *skb)
 
 	tcp_skb_collapse_tstamp(skb, next_skb);
 
-	sk_wmem_free_skb(sk, next_skb);
+	tcp_rtx_queue_unlink_and_free(next_skb, sk);
 	return true;
 }
 
@@ -2705,8 +2731,6 @@ static bool tcp_can_collapse(const struct sock *sk, const struct sk_buff *skb)
 		return false;
 	if (skb_cloned(skb))
 		return false;
-	if (skb == tcp_send_head(sk))
-		return false;
 	/* Some heuristics for collapsing over SACK'd could be invented */
 	if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED)
 		return false;
@@ -2729,7 +2753,7 @@ static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *to,
 	if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)
 		return;
 
-	tcp_for_write_queue_from_safe(skb, tmp, sk) {
+	skb_rbtree_walk_from_safe(skb, tmp) {
 		if (!tcp_can_collapse(sk, skb))
 			break;
 
@@ -2804,7 +2828,8 @@ int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs)
 
 	len = cur_mss * segs;
 	if (skb->len > len) {
-		if (tcp_fragment(sk, skb, len, cur_mss, GFP_ATOMIC))
+		if (tcp_fragment(sk, TCP_FRAG_IN_RTX_QUEUE, skb, len,
+				 cur_mss, GFP_ATOMIC))
 			return -ENOMEM; /* We'll try again later. */
 	} else {
 		if (skb_unclone(skb, GFP_ATOMIC))
@@ -2838,17 +2863,21 @@ int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs)
 		     skb_headroom(skb) >= 0xFFFF)) {
 		struct sk_buff *nskb;
 
-		nskb = __pskb_copy(skb, MAX_TCP_HEADER, GFP_ATOMIC);
-		err = nskb ? tcp_transmit_skb(sk, nskb, 0, GFP_ATOMIC) :
-			     -ENOBUFS;
+		tcp_skb_tsorted_save(skb) {
+			nskb = __pskb_copy(skb, MAX_TCP_HEADER, GFP_ATOMIC);
+			err = nskb ? tcp_transmit_skb(sk, nskb, 0, GFP_ATOMIC) :
+				     -ENOBUFS;
+		} tcp_skb_tsorted_restore(skb);
+
 		if (!err)
-			skb->skb_mstamp = tp->tcp_mstamp;
+			tcp_update_skb_after_send(tp, skb);
 	} else {
 		err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC);
 	}
 
 	if (likely(!err)) {
 		TCP_SKB_CB(skb)->sacked |= TCPCB_EVER_RETRANS;
+		trace_tcp_retransmit_skb(sk, skb);
 	} else if (err != -EBUSY) {
 		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPRETRANSFAIL);
 	}
@@ -2892,29 +2921,21 @@ int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs)
 void tcp_xmit_retransmit_queue(struct sock *sk)
 {
 	const struct inet_connection_sock *icsk = inet_csk(sk);
+	struct sk_buff *skb, *rtx_head, *hole = NULL;
 	struct tcp_sock *tp = tcp_sk(sk);
-	struct sk_buff *skb;
-	struct sk_buff *hole = NULL;
 	u32 max_segs;
 	int mib_idx;
 
 	if (!tp->packets_out)
 		return;
 
-	if (tp->retransmit_skb_hint) {
-		skb = tp->retransmit_skb_hint;
-	} else {
-		skb = tcp_write_queue_head(sk);
-	}
-
+	rtx_head = tcp_rtx_queue_head(sk);
+	skb = tp->retransmit_skb_hint ?: rtx_head;
 	max_segs = tcp_tso_segs(sk, tcp_current_mss(sk));
-	tcp_for_write_queue_from(skb, sk) {
+	skb_rbtree_walk_from(skb) {
 		__u8 sacked;
 		int segs;
 
-		if (skb == tcp_send_head(sk))
-			break;
-
 		if (tcp_pacing_check(sk))
 			break;
 
@@ -2959,7 +2980,7 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
 		if (tcp_in_cwnd_reduction(sk))
 			tp->prr_out += tcp_skb_pcount(skb);
 
-		if (skb == tcp_write_queue_head(sk) &&
+		if (skb == rtx_head &&
 		    icsk->icsk_pending != ICSK_TIME_REO_TIMEOUT)
 			inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
 						  inet_csk(sk)->icsk_rto,
@@ -3001,12 +3022,15 @@ void tcp_send_fin(struct sock *sk)
 	 * Note: in the latter case, FIN packet will be sent after a timeout,
 	 * as TCP stack thinks it has already been transmitted.
 	 */
-	if (tskb && (tcp_send_head(sk) || tcp_under_memory_pressure(sk))) {
+	if (!tskb && tcp_under_memory_pressure(sk))
+		tskb = skb_rb_last(&sk->tcp_rtx_queue);
+
+	if (tskb) {
 coalesce:
 		TCP_SKB_CB(tskb)->tcp_flags |= TCPHDR_FIN;
 		TCP_SKB_CB(tskb)->end_seq++;
 		tp->write_seq++;
-		if (!tcp_send_head(sk)) {
+		if (tcp_write_queue_empty(sk)) {
 			/* This means tskb was already sent.
 			 * Pretend we included the FIN on previous transmit.
 			 * We need to set tp->snd_nxt to the value it would have
@@ -3023,6 +3047,7 @@ coalesce:
 				goto coalesce;
 			return;
 		}
+		INIT_LIST_HEAD(&skb->tcp_tsorted_anchor);
 		skb_reserve(skb, MAX_TCP_HEADER);
 		sk_forced_mem_schedule(sk, skb->truesize);
 		/* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */
@@ -3071,20 +3096,24 @@ int tcp_send_synack(struct sock *sk)
 {
 	struct sk_buff *skb;
 
-	skb = tcp_write_queue_head(sk);
+	skb = tcp_rtx_queue_head(sk);
 	if (!skb || !(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) {
-		pr_debug("%s: wrong queue state\n", __func__);
+		pr_err("%s: wrong queue state\n", __func__);
 		return -EFAULT;
 	}
 	if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK)) {
 		if (skb_cloned(skb)) {
-			struct sk_buff *nskb = skb_copy(skb, GFP_ATOMIC);
+			struct sk_buff *nskb;
+
+			tcp_skb_tsorted_save(skb) {
+				nskb = skb_copy(skb, GFP_ATOMIC);
+			} tcp_skb_tsorted_restore(skb);
 			if (!nskb)
 				return -ENOMEM;
-			tcp_unlink_write_queue(skb, sk);
+			INIT_LIST_HEAD(&nskb->tcp_tsorted_anchor);
+			tcp_rtx_queue_unlink_and_free(skb, sk);
 			__skb_header_release(nskb);
-			__tcp_add_write_queue_head(sk, nskb);
-			sk_wmem_free_skb(sk, skb);
+			tcp_rbtree_insert(&sk->tcp_rtx_queue, nskb);
 			sk->sk_wmem_queued += nskb->truesize;
 			sk_mem_charge(sk, nskb->truesize);
 			skb = nskb;
@@ -3307,7 +3336,6 @@ static void tcp_connect_queue_skb(struct sock *sk, struct sk_buff *skb)
 
 	tcb->end_seq += skb->len;
 	__skb_header_release(skb);
-	__tcp_add_write_queue_tail(sk, skb);
 	sk->sk_wmem_queued += skb->truesize;
 	sk_mem_charge(sk, skb->truesize);
 	tp->write_seq = tcb->end_seq;
@@ -3385,12 +3413,13 @@ static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn)
 	TCP_SKB_CB(syn_data)->tcp_flags = TCPHDR_ACK | TCPHDR_PSH;
 	if (!err) {
 		tp->syn_data = (fo->copied > 0);
+		tcp_rbtree_insert(&sk->tcp_rtx_queue, syn_data);
 		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPORIGDATASENT);
 		goto done;
 	}
 
-	/* data was not sent, this is our new send_head */
-	sk->sk_send_head = syn_data;
+	/* data was not sent, put it in write_queue */
+	__skb_queue_tail(&sk->sk_write_queue, syn_data);
 	tp->packets_out -= tcp_skb_pcount(syn_data);
 
 fallback:
@@ -3433,6 +3462,7 @@ int tcp_connect(struct sock *sk)
 	tp->retrans_stamp = tcp_time_stamp(tp);
 	tcp_connect_queue_skb(sk, buff);
 	tcp_ecn_send_syn(sk, buff);
+	tcp_rbtree_insert(&sk->tcp_rtx_queue, buff);
 
 	/* Send off SYN; include data in Fast Open. */
 	err = tp->fastopen_req ? tcp_send_syn_data(sk, buff) :
@@ -3627,7 +3657,8 @@ int tcp_write_wakeup(struct sock *sk, int mib)
 		    skb->len > mss) {
 			seg_size = min(seg_size, mss);
 			TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH;
-			if (tcp_fragment(sk, skb, seg_size, mss, GFP_ATOMIC))
+			if (tcp_fragment(sk, TCP_FRAG_IN_WRITE_QUEUE,
+					 skb, seg_size, mss, GFP_ATOMIC))
 				return -1;
 		} else if (!tcp_skb_pcount(skb))
 			tcp_set_skb_tso_segs(skb, mss);
@@ -3657,7 +3688,7 @@ void tcp_send_probe0(struct sock *sk)
 
 	err = tcp_write_wakeup(sk, LINUX_MIB_TCPWINPROBE);
 
-	if (tp->packets_out || !tcp_send_head(sk)) {
+	if (tp->packets_out || tcp_write_queue_empty(sk)) {
 		/* Cancel probe timer, if it is not required. */
 		icsk->icsk_probes_out = 0;
 		icsk->icsk_backoff = 0;