3.9-stable review patch. If anyone has any objections, please let me know.
------------------ From: Yuchung Cheng <[email protected]> [ Upstream commit cd75eff64dae8856afbf6ef0f0ca3c145465d8e0 ] 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 <[email protected]> Acked-by: Eric Dumazet <[email protected]> Acked-by: Neal Cardwell <[email protected]> Signed-off-by: David S. Miller <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- net/ipv4/tcp_minisocks.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/net/ipv4/tcp_minisocks.c +++ b/net/ipv4/tcp_minisocks.c @@ -583,8 +583,13 @@ struct sock *tcp_check_req(struct sock * * * 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; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
