From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7084BC33CB3 for ; Wed, 15 Jan 2020 21:37:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 51166222C3 for ; Wed, 15 Jan 2020 21:37:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729821AbgAOVhT (ORCPT ); Wed, 15 Jan 2020 16:37:19 -0500 Received: from shards.monkeyblade.net ([23.128.96.9]:60388 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729578AbgAOVhP (ORCPT ); Wed, 15 Jan 2020 16:37:15 -0500 Received: from localhost (unknown [62.21.130.100]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) (Authenticated sender: davem-davemloft) by shards.monkeyblade.net (Postfix) with ESMTPSA id 156D315A0E3E8; Wed, 15 Jan 2020 13:37:11 -0800 (PST) Date: Wed, 15 Jan 2020 13:35:42 -0800 (PST) Message-Id: <20200115.133542.149188857628032129.davem@davemloft.net> To: yangpc@wangsu.com Cc: edumazet@google.com, kuznet@ms2.inr.ac.ru, yoshfuji@linux-ipv6.org, ast@kernel.org, daniel@iogearbox.net, kafai@fb.com, songliubraving@fb.com, yhs@fb.com, andriin@fb.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] tcp: fix marked lost packets not being retransmitted From: David Miller In-Reply-To: <1578993820-2114-1-git-send-email-yangpc@wangsu.com> References: <1578993820-2114-1-git-send-email-yangpc@wangsu.com> X-Mailer: Mew version 6.8 on Emacs 26.3 Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Wed, 15 Jan 2020 13:37:14 -0800 (PST) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Pengcheng Yang Date: Tue, 14 Jan 2020 17:23:40 +0800 > When the packet pointed to by retransmit_skb_hint is unlinked by ACK, > retransmit_skb_hint will be set to NULL in tcp_clean_rtx_queue(). > If packet loss is detected at this time, retransmit_skb_hint will be set > to point to the current packet loss in tcp_verify_retransmit_hint(), > then the packets that were previously marked lost but not retransmitted > due to the restriction of cwnd will be skipped and cannot be > retransmitted. > > To fix this, when retransmit_skb_hint is NULL, retransmit_skb_hint can > be reset only after all marked lost packets are retransmitted > (retrans_out >= lost_out), otherwise we need to traverse from > tcp_rtx_queue_head in tcp_xmit_retransmit_queue(). > > Packetdrill to demonstrate: ... > Signed-off-by: Pengcheng Yang Applied, thank you.