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=-2.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 957A0C35240 for ; Fri, 31 Jan 2020 22:53:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6A3E120707 for ; Fri, 31 Jan 2020 22:53:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="BOOJ0Umn" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726749AbgAaWxt (ORCPT ); Fri, 31 Jan 2020 17:53:49 -0500 Received: from mail-pj1-f66.google.com ([209.85.216.66]:36453 "EHLO mail-pj1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726239AbgAaWxt (ORCPT ); Fri, 31 Jan 2020 17:53:49 -0500 Received: by mail-pj1-f66.google.com with SMTP id gv17so3595545pjb.1; Fri, 31 Jan 2020 14:53:47 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=O64ZrPgfOSQfg7giHCwyJ23cxOCbiT2C1hToXNCQpWY=; b=BOOJ0Umnh+z2fup1+C6AYpqK8dw/9bii6hztTW4wh+y+LkZJF2CKGz/18Fm825U1Dj WFyhP237naoFQ8e+VIMnumKLEHmoRKvvUnjzMygt+DKP+p0Ql+p/TsTjByl0yYiI3iQ4 DovBBDFVI/DC0AnHmJt89Ggra1beaiBH2OUbG5RWTesrXGFIBv5hNfGfLYXHCZ9ZgS+l UxgknH2OodFR0xNk4NuQ7EfqLQMHtagYyh9tFB8XW0oTD5tcyb9liWUlAnzjA461jneW vHcUaDPVeYRkXyBlMlxkMnNNSxU+eBROYVgjmDAEvm6zTTGS3aJ5giXxxI7DxrUM0Xq1 PvRQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=O64ZrPgfOSQfg7giHCwyJ23cxOCbiT2C1hToXNCQpWY=; b=CY/el1qbIBCzWAGYK34Cw0kidcfUp2ChqxjBUYaeq6NjFcImMv9acjDzDGvtqrzDHK fawjS/HcDsbbbnC74YCIdpAuZc9Vpp8Y423w/PdmpTO5Qbq+p8QWUuqqLi3b94aJS0jq e9y8jQxUNaQOSbscKzpmCLcoIYvkv3uMWRoaJmrZva03RrJrJNHrK3tPPKU0xofkrN4H KMQipqIzVeD1Z/99KtlFAVZ3dbk7ie5egd95lep3XE0zbikXxin5VE1BTdu1Vkw8ja41 YKhzONIybnGAtpd96e6x10R89zcnQuGqe06yyySJ2Kn4foLyfs7krMbvMsK1mvlhHJvp d0sw== X-Gm-Message-State: APjAAAXvJ04Va4Ggn80cTCLZW06ddjI/j3jTWvpeEuzfh6xKnyBN+m+n o3c1eIoiXE+k181CXvHvCCo= X-Google-Smtp-Source: APXvYqzToYKFMEvzvWEdWk6mTmkSMmNSEEJM3PIkpoZY38eIfpy8Ev8fJPhmwggC6n+nHu4XY3wsyA== X-Received: by 2002:a17:902:8d94:: with SMTP id v20mr2737008plo.259.1580511227385; Fri, 31 Jan 2020 14:53:47 -0800 (PST) Received: from ?IPv6:2620:15c:2c1:200:55c7:81e6:c7d8:94b? ([2620:15c:2c1:200:55c7:81e6:c7d8:94b]) by smtp.gmail.com with ESMTPSA id r26sm10876261pga.55.2020.01.31.14.53.44 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 31 Jan 2020 14:53:46 -0800 (PST) Subject: Re: [PATCH 2/3] tcp: Reduce SYN resend delay if a suspicous ACK is received To: Neal Cardwell , Eric Dumazet Cc: sjpark@amazon.com, Eric Dumazet , David Miller , shuah@kernel.org, Netdev , linux-kselftest@vger.kernel.org, LKML , sj38.park@gmail.com, aams@amazon.com, SeongJae Park , Yuchung Cheng References: <20200131122421.23286-1-sjpark@amazon.com> <20200131122421.23286-3-sjpark@amazon.com> From: Eric Dumazet Message-ID: <7d36a817-5519-8496-17cf-00eda5ed4ec7@gmail.com> Date: Fri, 31 Jan 2020 14:53:43 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/31/20 2:11 PM, Neal Cardwell wrote: > I looked into fixing this, but my quick reading of the Linux > tcp_rcv_state_process() code is that it should behave correctly and > that a connection in FIN_WAIT_1 that receives a FIN/ACK should move to > TIME_WAIT. > > SeongJae, do you happen to have a tcpdump trace of the problematic > sequence where the "process A" ends up in FIN_WAIT_2 when it should be > in TIME_WAIT? > > If I have time I will try to construct a packetdrill case to verify > the behavior in this case. Unfortunately you wont be able to reproduce the issue with packetdrill, since it involved packets being processed at the same time (race window)