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=-0.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 683F7C43381 for ; Mon, 18 Feb 2019 20:48:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 384C32146E for ; Mon, 18 Feb 2019 20:48:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="QSE7EFZ/" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728892AbfBRUsJ (ORCPT ); Mon, 18 Feb 2019 15:48:09 -0500 Received: from mail-pg1-f193.google.com ([209.85.215.193]:46000 "EHLO mail-pg1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725844AbfBRUsJ (ORCPT ); Mon, 18 Feb 2019 15:48:09 -0500 Received: by mail-pg1-f193.google.com with SMTP id y4so9007383pgc.12 for ; Mon, 18 Feb 2019 12:48:08 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=TlUPiUE1DES1W7grCqidMxBTvZNgzNo5o0pQO6X1Xu0=; b=QSE7EFZ/gwgQvqQofnRdZ+x8jYqpVwlU1PZLgvpkMGD02gEWB11kOafFbecizJs+GO 2BEMhO8fO/sH4b8M04A2mpkVDQOEBTwjSU/exvSS0jWWsBIcVHEuCH/3wIGoCZlvlZxr kPH6p7xNNltjMIdMsxR6PvfF/p2vvsp80yaDUGjaUVRuOeEvZYsRpSmHZuHtLG+wz/qP SYZFdJ0IlhQPCMbEyiBmcEPSryVLW24BHn3a8SryNmrmw+uu+/M1CF44PgbRMzZjz1Bg q9fZlBPrK3QXex1VoTiClUX/hvYxNusM+rvCZscpiLNicXIGXf0BVOgPA1VFNOiXfbkX mFow== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=TlUPiUE1DES1W7grCqidMxBTvZNgzNo5o0pQO6X1Xu0=; b=pC58EjRt8hkfAn1mj+gnWL8aPr4EwExXPO5Ku83zNY8I1qYs7QQyWMZrIMuafZk4ST 3zaBf2SGYiqNi7qeeZzaTPiycWw3HrAI89H/L7hiDDQD63ULdyFWgYNyqN8nLX6lhdpk Z3ewNSvDhl3XhZU+nRz5pr7VTXOOjDZYCKU15/xfx9R5LSfz5Gm1R775MvzaIelUQXcf VkRtJEATXLW0v66V2TxenzEKo5u7l6YePytYv0ne0sWiOwzN2ODi5ggq0FW298gMtjkn i4OdxDfcf0nkM+E/DdAPAF83pooUy+v54PqncabHb+QUah/nLXoJErNfVyXdC2CwNIjv UFNA== X-Gm-Message-State: AHQUAub3trWHaGZrk213t2R0i+Sko8m0n4rr4ifQd9k255AkAXdMPI2h 0UO7QOHN5zbZF8hrlJwDenZaO42h8MQ7fAJxlsR3mQ== X-Google-Smtp-Source: AHgI3IZKtAPKkpu9JP7nJ8wEXohnnAdO0QCbHFS27v2a6mmqZEQEAKJB3nDEx4v7kXU5zBDFnZZD1LVeL5IkSniXynU= X-Received: by 2002:a63:28c1:: with SMTP id o184mr6403024pgo.123.1550522888364; Mon, 18 Feb 2019 12:48:08 -0800 (PST) MIME-Version: 1.0 References: <20190214074712.17846-1-vladbu@mellanox.com> <20190214074712.17846-10-vladbu@mellanox.com> In-Reply-To: <20190214074712.17846-10-vladbu@mellanox.com> From: Cong Wang Date: Mon, 18 Feb 2019 12:47:56 -0800 Message-ID: Subject: Re: [PATCH net-next 09/12] net: sched: flower: handle concurrent tcf proto deletion To: Vlad Buslov Cc: Linux Kernel Network Developers , Jamal Hadi Salim , Jiri Pirko , David Miller Content-Type: text/plain; charset="UTF-8" Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Wed, Feb 13, 2019 at 11:47 PM Vlad Buslov wrote: > > Without rtnl lock protection tcf proto can be deleted concurrently. Check > tcf proto 'deleting' flag after taking tcf spinlock to verify that no > concurrent deletion is in progress. Return EAGAIN error if concurrent > deletion detected, which will cause caller to retry and possibly create new > instance of tcf proto. > Please state the reason why you prefer retry over locking the whole tp without retrying, that is why and how it is better? Personally I always prefer non-retry logic, because it is very easy to understand and justify its correctness. As you prefer otherwise, please share your reasoning in changelog. Thanks!