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=-4.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,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 E824CC3E8C5 for ; Wed, 18 Nov 2020 18:04:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 777882075A for ; Wed, 18 Nov 2020 18:04:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="qv3w44v1" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726156AbgKRSEw (ORCPT ); Wed, 18 Nov 2020 13:04:52 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44192 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726081AbgKRSEw (ORCPT ); Wed, 18 Nov 2020 13:04:52 -0500 Received: from mail-io1-xd42.google.com (mail-io1-xd42.google.com [IPv6:2607:f8b0:4864:20::d42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2DF65C0613D4 for ; Wed, 18 Nov 2020 10:04:52 -0800 (PST) Received: by mail-io1-xd42.google.com with SMTP id r9so2976290ioo.7 for ; Wed, 18 Nov 2020 10:04:52 -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=EYbIc0bx6KawQTbjukp0zhf42kppKq6tBuivLh8ljys=; b=qv3w44v1jflbM5MVlGFyaax4gpD+2Cio80ZI1qgEyS5v38YUp0di5dSkXOctEuYoiZ nqCwU+JcmFWwzmEn1ibWkpwPCB1ONvi4vQ1QtDfjcpEmANCgATU68YmiRyRTULH+kGul /GKXC8psfPwviKcJdCfBodMCZqP+45s8VUXbkWIY1gS+hlXj6y88Grj/jwVu8ZtKz1Mr oqC637vBjSEGrwZG99pboNXLtL1qONyhjybQ15O6UDDp7q4sh8+o45tPceA/xfk2YyOZ l/ej7wTeQH1Sj3mmkHEKo4E/9kRiEfeWaGBzR5CPk2oJefqEUKR9ZCzdTDfoX3x0QK33 y87g== 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=EYbIc0bx6KawQTbjukp0zhf42kppKq6tBuivLh8ljys=; b=BommVmk6/3f97566PJZSsjUGIRlqBHyT8rUCUanKUFc0gOwLpLYwS52zgaaF3GCeeb TIrubfVLHR3RbxTUsaJfapneJvKeX6IL5x/162BWXhfRU/HsR/mCdE7X5LFPO5hwf9Yx 4xIhlvS+1MLL0wEVn1vGboptCOm3db4FJcyz7JnbNmIwEtZDBfuwK2FlVVs6DQE0DsZ9 dxEp4ADNbT/C2LsWHCvkvLyFdZCwavoMtttHS9UBSh4ey4yhaKxp06b5QRTxQ9MjzYEH R9ySaCxC/2JybS6CttIi/xW9F+it0L6XYs3oGkdqXpW445oo7HpPOck9k5Y7saeB/Wyv 6QXQ== X-Gm-Message-State: AOAM5326xGaHfULnw25P4tfltV7XhM8gfSeu1hVYvA/mlf+hNKLeh3wq eGCigi3KmyxtAtdiLmb2yOY= X-Google-Smtp-Source: ABdhPJwN53K9Z87nL8GdCraNynJTBlPPRmoPsCBqwiv4AuJZ2IZasyq9cKoZcRds7POOeofP+WoyCQ== X-Received: by 2002:a6b:8bcf:: with SMTP id n198mr15912100iod.122.1605722691663; Wed, 18 Nov 2020 10:04:51 -0800 (PST) Received: from Davids-MacBook-Pro.local ([2601:284:8203:54f0:cd3a:ec11:4d4f:e8d8]) by smtp.googlemail.com with ESMTPSA id c3sm16299621ila.47.2020.11.18.10.04.50 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 18 Nov 2020 10:04:50 -0800 (PST) Subject: Re: [PATCH net-next] net-loopback: allow lo dev initial state to be controlled To: =?UTF-8?B?TWFoZXNoIEJhbmRld2FyICjgpK7gpLngpYfgpLYg4KSs4KSC4KSh4KWH4KS1?= =?UTF-8?B?4KS+4KSwKQ==?= , nicolas.dichtel@6wind.com Cc: Ido Schimmel , Jakub Kicinski , Jian Yang , David Miller , linux-netdev , Jian Yang , Eric Dumazet References: <20201111204308.3352959-1-jianyang.kernel@gmail.com> <20201114101709.42ee19e0@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> <20201116123447.2be5a827@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> <20201117171830.GA286718@shredder.lan> <7e16f1f3-2551-dff5-8039-bcede955bbfc@6wind.com> From: David Ahern Message-ID: <7b3f1d07-eca4-b012-c46a-e1f09bba9d6f@gmail.com> Date: Wed, 18 Nov 2020 11:04:50 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.4.3 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 11/18/20 10:39 AM, Mahesh Bandewar (महेश बंडेवार) wrote: > On Wed, Nov 18, 2020 at 8:58 AM Nicolas Dichtel > wrote: >> >> Le 18/11/2020 à 02:12, David Ahern a écrit : >> [snip] >>> If there is no harm in just creating lo in the up state, why not just do >>> it vs relying on a sysctl? It only affects 'local' networking so no real >>> impact to containers that do not do networking (ie., packets can't >>> escape). Linux has a lot of sysctl options; is this one really needed? >>> > I started with that approach but then I was informed about these > containers that disable networking all together including loopback. > Also bringing up by default would break backward compatibility hence > resorted to sysctl. >> +1 >> >> And thus, it will benefit to everybody. > > Well, it benefits everyone who uses networking (most of us) inside > netns but would create problems for workloads that create netns to > disable networking. One can always disable it after creating the netns > but that would mean change in the workflow and it could be viewed as > regression. > Then perhaps the relevant sysctl -- or maybe netns attribute -- is whether to create a loopback device at all.