diff options
Diffstat (limited to 'net/ipv4/tcp_input.c')
| -rw-r--r-- | net/ipv4/tcp_input.c | 25 |
1 files changed, 21 insertions, 4 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 723cee63791f..a283fc12186e 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -1239,14 +1239,31 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_ /* F-RTO can only be used if these conditions are satisfied: * - there must be some unsent new data * - the advertised window should allow sending it + * - TCP has never retransmitted anything other than head */ -int tcp_use_frto(const struct sock *sk) +int tcp_use_frto(struct sock *sk) { const struct tcp_sock *tp = tcp_sk(sk); + struct sk_buff *skb; + + if (!sysctl_tcp_frto || !sk->sk_send_head || + after(TCP_SKB_CB(sk->sk_send_head)->end_seq, + tp->snd_una + tp->snd_wnd)) + return 0; - return (sysctl_tcp_frto && sk->sk_send_head && - !after(TCP_SKB_CB(sk->sk_send_head)->end_seq, - tp->snd_una + tp->snd_wnd)); + /* Avoid expensive walking of rexmit queue if possible */ + if (tp->retrans_out > 1) + return 0; + + skb = skb_peek(&sk->sk_write_queue)->next; /* Skips head */ + sk_stream_for_retrans_queue_from(skb, sk) { + if (TCP_SKB_CB(skb)->sacked&TCPCB_RETRANS) + return 0; + /* Short-circuit when first non-SACKed skb has been checked */ + if (!(TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_ACKED)) + break; + } + return 1; } /* RTO occurred, but do not yet enter Loss state. Instead, defer RTO |
