From mboxrd@z Thu Jan 1 00:00:00 1970 From: Per Hurtig Subject: [PATCH] tcp: fixing TLP's FIN recovery Date: Sat, 7 Jun 2014 13:10:19 +0200 Message-ID: <1402139419-9118-1-git-send-email-per.hurtig@kau.se> References: <1402081628.3645.315.camel@edumazet-glaptop2.roam.corp.google.com> Cc: Per Hurtig , eric.dumazet@gmail.com, anna.brunstrom@kau.se, mohammad.rajiullah@kau.se, ncardwell@google.com, nanditad@google.com To: netdev@vger.kernel.org Return-path: Received: from smtp.kau.se ([193.10.220.38]:53445 "EHLO tiger.dc.kau.se" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752425AbaFGLTf (ORCPT ); Sat, 7 Jun 2014 07:19:35 -0400 In-Reply-To: <1402081628.3645.315.camel@edumazet-glaptop2.roam.corp.google.com> Sender: netdev-owner@vger.kernel.org List-ID: Fix to a problem observed when losing a FIN segment that does not contain data. In such situations, TLP is unable to recover from *any* tail loss and instead adds at least PTO ms to the retransmission process, i.e., RTO = RTO + PTO. --- net/ipv4/tcp_output.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index d463c35..6573765 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -2130,8 +2130,10 @@ void tcp_send_loss_probe(struct sock *sk) if (WARN_ON(!skb || !tcp_skb_pcount(skb))) goto rearm_timer; - /* Probe with zero data doesn't trigger fast recovery. */ - if (skb->len > 0) + /* Probe with zero data doesn't trigger fast recovery, if not + * FIN flag is set. + */ + if ((skb->len > 0) || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)) err = __tcp_retransmit_skb(sk, skb); /* Record snd_nxt for loss detection. */ -- 1.9.1