1 files changed, 29 insertions, 11 deletions

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 9299de0da..670804d4c 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -164,8 +164,7 @@ static void tcp_event_data_sent(struct tcp_sock *tp,
 }
 
 /* Account for an ACK we sent. */
-static inline void tcp_event_ack_sent(struct sock *sk, unsigned int pkts,
-				      u32 rcv_nxt)
+static inline void tcp_event_ack_sent(struct sock *sk, u32 rcv_nxt)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 
@@ -179,7 +178,7 @@ static inline void tcp_event_ack_sent(struct sock *sk, unsigned int pkts,
 
 	if (unlikely(rcv_nxt != tp->rcv_nxt))
 		return;  /* Special ACK sent by DCTCP to reflect ECN */
-	tcp_dec_quickack_mode(sk, pkts);
+	tcp_dec_quickack_mode(sk);
 	inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
 }
 
@@ -1091,7 +1090,7 @@ static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb,
 	skb_set_hash_from_sk(skb, sk);
 	refcount_add(skb->truesize, &sk->sk_wmem_alloc);
 
-	skb_set_dst_pending_confirm(skb, sk->sk_dst_pending_confirm);
+	skb_set_dst_pending_confirm(skb, READ_ONCE(sk->sk_dst_pending_confirm));
 
 	/* Build TCP header and checksum it. */
 	th = (struct tcphdr *)skb->data;
@@ -1139,7 +1138,7 @@ static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb,
 	icsk->icsk_af_ops->send_check(sk, skb);
 
 	if (likely(tcb->tcp_flags & TCPHDR_ACK))
-		tcp_event_ack_sent(sk, tcp_skb_pcount(skb), rcv_nxt);
+		tcp_event_ack_sent(sk, rcv_nxt);
 
 	if (skb->len != tcp_header_size) {
 		tcp_event_data_sent(tp, sk);
@@ -2221,6 +2220,18 @@ static int tcp_mtu_probe(struct sock *sk)
 	return -1;
 }
 
+static bool tcp_rtx_queue_empty_or_single_skb(const struct sock *sk)
+{
+	const struct rb_node *node = sk->tcp_rtx_queue.rb_node;
+
+	/* No skb in the rtx queue. */
+	if (!node)
+		return true;
+
+	/* Only one skb in rtx queue. */
+	return !node->rb_left && !node->rb_right;
+}
+
 /* TCP Small Queues :
  * Control number of packets in qdisc/devices to two packets / or ~1 ms.
  * (These limits are doubled for retransmits)
@@ -2243,12 +2254,12 @@ 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 skb if rtx queue is empty.
+		/* Always send skb if rtx queue is empty or has one skb.
 		 * 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 (tcp_rtx_queue_empty(sk))
+		if (tcp_rtx_queue_empty_or_single_skb(sk))
 			return false;
 
 		set_bit(TSQ_THROTTLED, &sk->sk_tsq_flags);
@@ -2450,7 +2461,7 @@ bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto)
 {
 	struct inet_connection_sock *icsk = inet_csk(sk);
 	struct tcp_sock *tp = tcp_sk(sk);
-	u32 timeout, rto_delta_us;
+	u32 timeout, timeout_us, rto_delta_us;
 	int early_retrans;
 
 	/* Don't do any loss probe on a Fast Open connection before 3WHS
@@ -2474,11 +2485,12 @@ bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto)
 	 * sample is available then probe after TCP_TIMEOUT_INIT.
 	 */
 	if (tp->srtt_us) {
-		timeout = usecs_to_jiffies(tp->srtt_us >> 2);
+		timeout_us = tp->srtt_us >> 2;
 		if (tp->packets_out == 1)
-			timeout += TCP_RTO_MIN;
+			timeout_us += tcp_rto_min_us(sk);
 		else
-			timeout += TCP_TIMEOUT_MIN;
+			timeout_us += TCP_TIMEOUT_MIN_US;
+		timeout = usecs_to_jiffies(timeout_us);
 	} else {
 		timeout = TCP_TIMEOUT_INIT;
 	}
@@ -2878,7 +2890,13 @@ int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs)
 	if (skb_still_in_host_queue(sk, skb))
 		return -EBUSY;
 
+start:
 	if (before(TCP_SKB_CB(skb)->seq, tp->snd_una)) {
+		if (unlikely(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) {
+			TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_SYN;
+			TCP_SKB_CB(skb)->seq++;
+			goto start;
+		}
 		if (unlikely(before(TCP_SKB_CB(skb)->end_seq, tp->snd_una))) {
 			WARN_ON_ONCE(1);
 			return -EINVAL;