diff options
Diffstat (limited to 'net/ipv4/tcp_input.c')
| -rw-r--r-- | net/ipv4/tcp_input.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 4c2dd9f863f7..62508a2f9b21 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4199,6 +4199,17 @@ static void tcp_dsack_extend(struct sock *sk, u32 seq, u32 end_seq) tcp_sack_extend(tp->duplicate_sack, seq, end_seq); } +static void tcp_rcv_spurious_retrans(struct sock *sk, const struct sk_buff *skb) +{ + /* When the ACK path fails or drops most ACKs, the sender would + * timeout and spuriously retransmit the same segment repeatedly. + * The receiver remembers and reflects via DSACKs. Leverage the + * DSACK state and change the txhash to re-route speculatively. + */ + if (TCP_SKB_CB(skb)->seq == tcp_sk(sk)->duplicate_sack[0].start_seq) + sk_rethink_txhash(sk); +} + static void tcp_send_dupack(struct sock *sk, const struct sk_buff *skb) { struct tcp_sock *tp = tcp_sk(sk); @@ -4211,6 +4222,7 @@ static void tcp_send_dupack(struct sock *sk, const struct sk_buff *skb) if (tcp_is_sack(tp) && sock_net(sk)->ipv4.sysctl_tcp_dsack) { u32 end_seq = TCP_SKB_CB(skb)->end_seq; + tcp_rcv_spurious_retrans(sk, skb); if (after(TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt)) end_seq = tp->rcv_nxt; tcp_dsack_set(sk, TCP_SKB_CB(skb)->seq, end_seq); @@ -4755,6 +4767,7 @@ queue_and_out: } if (!after(TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt)) { + tcp_rcv_spurious_retrans(sk, skb); /* A retransmit, 2nd most common case. Force an immediate ack. */ NET_INC_STATS(sock_net(sk), LINUX_MIB_DELAYEDACKLOST); tcp_dsack_set(sk, TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq); |