From cd75eff64dae8856afbf6ef0f0ca3c145465d8e0 Mon Sep 17 00:00:00 2001 From: Yuchung Cheng Date: Mon, 29 Apr 2013 08:44:51 +0000 Subject: tcp: reset timer after any SYNACK retransmit Linux immediately returns SYNACK on (spurious) SYN retransmits, but keeps the SYNACK timer running independently. Thus the timer may fire right after the SYNACK retransmit and causes a SYN-SYNACK cross-fire burst. Adopt the fast retransmit/recovery idea in established state by re-arming the SYNACK timer after the fast (SYNACK) retransmit. The timer may fire late up to 500ms due to the current SYNACK timer wheel, but it's OK to be conservative when network is congested. Eric's new listener design should address this issue. Signed-off-by: Yuchung Cheng Acked-by: Eric Dumazet Acked-by: Neal Cardwell Signed-off-by: David S. Miller --- net/ipv4/tcp_minisocks.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'net/ipv4/tcp_minisocks.c') diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c index 05eaf890461..0f017882725 100644 --- a/net/ipv4/tcp_minisocks.c +++ b/net/ipv4/tcp_minisocks.c @@ -551,8 +551,13 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb, * * Note that even if there is new data in the SYN packet * they will be thrown away too. + * + * Reset timer after retransmitting SYNACK, similar to + * the idea of fast retransmit in recovery. */ - inet_rtx_syn_ack(sk, req); + if (!inet_rtx_syn_ack(sk, req)) + req->expires = min(TCP_TIMEOUT_INIT << req->num_timeout, + TCP_RTO_MAX) + jiffies; return NULL; } -- cgit v1.2.3-18-g5258