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 B4654C33C9E for ; Fri, 17 Jan 2020 18:48:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 88DCC2083E for ; Fri, 17 Jan 2020 18:48:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="jQRQTldy" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729424AbgAQSs0 (ORCPT ); Fri, 17 Jan 2020 13:48:26 -0500 Received: from mail-pg1-f195.google.com ([209.85.215.195]:34127 "EHLO mail-pg1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726897AbgAQSs0 (ORCPT ); Fri, 17 Jan 2020 13:48:26 -0500 Received: by mail-pg1-f195.google.com with SMTP id r11so12093282pgf.1; Fri, 17 Jan 2020 10:48:26 -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=uf2grPri+Pk70ySyorIWRt3xOE6amIrsICg9f4UOiek=; b=jQRQTldyPxOJDIzuGEiFZ7SbwJbDbJJZIZJtShG+tPkycNQT1BrpN5BPde5niFnHKu qCTwnSpXS7gL1IRfmnw6K2RtOQCqhGRHemIr4uGyUTmKeXqLJ2qgo40JAhrYjRce3u5u 6HwQyNb8ABAznP5xHcoxVfEeVq+3YY0WIuQSxZNF1Olw7PQwFGzecFHc4JZgDjULHNrt dv2LrSbKaxXlqUAS9bBlBqGVxrhcA7sqfD806e/OpXBG0K2Dt43ABqD51Y0Ffe2Oi5WM s7hZ9w9FtGIDpELVVJ74Rf2jQYkhep+KLV4mvfiANFL5c5UhVB6x6+rBvJrbogB9Bct8 TDBw== 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=uf2grPri+Pk70ySyorIWRt3xOE6amIrsICg9f4UOiek=; b=PXBmw1XeVYMcVFsTcZ9QvYAuXBT6yGMgvwxpfGFq3rZSgGVSKdHt+UsuI7+oRp7ftD aEnJaS+REEcMoho/s18Lp1yNDF08PZgG6TyYsHKvrUnmdPtwX3XKbRU0UBXHXYAMhGxz VRXbIiW8uOEtrY02hMdSbIGRqAhIOKSrnNLkKj/wd+VqXQj5QeF5SMQaKkXIncgkgf/p VS2rSBF5KstTz6Uyb/adfHpXRlcRQLocs4Y9NfNYEk+mrEXbQSq9p0T4XBpGThGAvfho cpr++wsdH6vLgzXMzbQ7IWCtBImgJoRJnW4MaazSNzIQYNHoFPNYlZKAyEuJkN6/aQzJ T3jg== X-Gm-Message-State: APjAAAXJx6JEDBSRQGSGcbtOYGVhc1Oxj88rWlIRgK46ZtgsrBFU8wAU oT2tWv0AaGAMYb1eAr3kqWc= X-Google-Smtp-Source: APXvYqyvXwmbIo2pROIrbwWIUHlo1UI2+KfXA/vCZHjGuwWa9d4r5hP8/q1nJyTRTwffia3TMmlJ5w== X-Received: by 2002:aa7:9816:: with SMTP id e22mr4382433pfl.229.1579286905813; Fri, 17 Jan 2020 10:48:25 -0800 (PST) Received: from [192.168.86.235] (c-73-241-150-58.hsd1.ca.comcast.net. [73.241.150.58]) by smtp.gmail.com with ESMTPSA id v15sm8304050pju.15.2020.01.17.10.48.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 17 Jan 2020 10:48:25 -0800 (PST) Subject: Re: [PATCH] net: optimize cmpxchg in ip_idents_reserve To: Arvind Sankar , Eric Dumazet Cc: Peter Zijlstra , Shaokun Zhang , David Miller , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, jinyuqi@huawei.com, kuznet@ms2.inr.ac.ru, yoshfuji@linux-ipv6.org, edumazet@google.com, guoyang2@huawei.com, Will Deacon References: <1579058620-26684-1-git-send-email-zhangshaokun@hisilicon.com> <20200116.042722.153124126288244814.davem@davemloft.net> <930faaff-4d18-452d-2e44-ef05b65dc858@gmail.com> <1b3aaddf-22f5-1846-90f1-42e68583c1e4@gmail.com> <430496fc-9f26-8cb4-91d8-505fda9af230@hisilicon.com> <20200117123253.GC14879@hirez.programming.kicks-ass.net> <7e6c6202-24bb-a532-adde-d53dd6fb14c3@gmail.com> <20200117180324.GA2623847@rani.riverdale.lan> <94573cea-a833-9b48-6581-8cc5cdd19b89@gmail.com> <20200117183800.GA2649345@rani.riverdale.lan> From: Eric Dumazet Message-ID: <45224c36-9941-aae5-aca4-e2c8e3723355@gmail.com> Date: Fri, 17 Jan 2020 10:48:19 -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: <20200117183800.GA2649345@rani.riverdale.lan> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/17/20 10:38 AM, Arvind Sankar wrote: > On Fri, Jan 17, 2020 at 10:16:45AM -0800, Eric Dumazet wrote: >> Wasńt it the case back in 2016 already for linux-4.8 ? >> >> What will prevent someone to send another report to netdev/lkml ? >> >> -fno-strict-overflow support is not a prereq for CONFIG_UBSAN. >> >> Fact that we kept in lib/ubsan.c and lib/test_ubsan.c code for >> test_ubsan_add_overflow() and test_ubsan_sub_overflow() is disturbing. >> > > No, it was bumped in 2018 in commit cafa0010cd51 ("Raise the minimum > required gcc version to 4.6"). That raised it from 3.2 -> 4.6. > This seems good to me, for gcc at least. Maybe it is time to enfore -fno-strict-overflow in KBUILD_CFLAGS instead of making it conditional. Thanks.