1 files changed, 32 insertions, 13 deletions

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index d3b691f3a9e8..c31badfee806 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1904,7 +1904,9 @@ static int tso_fragment(struct sock *sk, enum tcp_queue tcp_queue,
  * This algorithm is from John Heffner.
  */
 static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb,
-                                 bool *is_cwnd_limited, u32 max_segs)
+                                 bool *is_cwnd_limited,
+                                 bool *is_rwnd_limited,
+                                 u32 max_segs)
 {
         const struct inet_connection_sock *icsk = inet_csk(sk);
         u32 send_win, cong_win, limit, in_flight;
@@ -1913,9 +1915,6 @@ static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb,
         int win_divisor;
         s64 delta;
 
-        if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
-                goto send_now;
-
         if (icsk->icsk_ca_state >= TCP_CA_Recovery)
                 goto send_now;
 
@@ -1981,10 +1980,27 @@ static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb,
         if ((s64)(delta - (u64)NSEC_PER_USEC * (tp->srtt_us >> 4)) < 0)
                 goto send_now;
 
-        /* Ok, it looks like it is advisable to defer. */
+        /* Ok, it looks like it is advisable to defer.
+         * Three cases are tracked :
+         * 1) We are cwnd-limited
+         * 2) We are rwnd-limited
+         * 3) We are application limited.
+         */
+        if (cong_win < send_win) {
+                if (cong_win <= skb->len) {
+                        *is_cwnd_limited = true;
+                        return true;
+                }
+        } else {
+                if (send_win <= skb->len) {
+                        *is_rwnd_limited = true;
+                        return true;
+                }
+        }
 
-        if (cong_win < send_win && cong_win <= skb->len)
-                *is_cwnd_limited = true;
+        /* If this packet won't get more data, do not wait. */
+        if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)
+                goto send_now;
 
         return true;
 
@@ -2365,7 +2381,7 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle,
                 } else {
                         if (!push_one &&
                             tcp_tso_should_defer(sk, skb, &is_cwnd_limited,
-                                                 max_segs))
+                                                 &is_rwnd_limited, max_segs))
                                 break;
                 }
 
@@ -2503,15 +2519,18 @@ void tcp_send_loss_probe(struct sock *sk)
                 goto rearm_timer;
         }
         skb = skb_rb_last(&sk->tcp_rtx_queue);
+        if (unlikely(!skb)) {
+                WARN_ONCE(tp->packets_out,
+                          "invalid inflight: %u state %u cwnd %u mss %d\n",
+                          tp->packets_out, sk->sk_state, tp->snd_cwnd, mss);
+                inet_csk(sk)->icsk_pending = 0;
+                return;
+        }
 
         /* At most one outstanding TLP retransmission. */
         if (tp->tlp_high_seq)
                 goto rearm_timer;
 
-        /* Retransmit last segment. */
-        if (WARN_ON(!skb))
-                goto rearm_timer;
-
         if (skb_still_in_host_queue(sk, skb))
                 goto rearm_timer;
 
@@ -2929,7 +2948,7 @@ int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs)
                 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);
+                NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPRETRANSFAIL, segs);
         }
         return err;
 }