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=-13.2 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL 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 2FE8CC5519F for ; Wed, 18 Nov 2020 19:54:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CC835246BC for ; Wed, 18 Nov 2020 19:54:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="qRpeAS+b" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726340AbgKRTyT (ORCPT ); Wed, 18 Nov 2020 14:54:19 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33068 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725710AbgKRTyS (ORCPT ); Wed, 18 Nov 2020 14:54:18 -0500 Received: from mail-yb1-xb44.google.com (mail-yb1-xb44.google.com [IPv6:2607:f8b0:4864:20::b44]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8F957C0613D4 for ; Wed, 18 Nov 2020 11:54:18 -0800 (PST) Received: by mail-yb1-xb44.google.com with SMTP id l14so2867479ybq.3 for ; Wed, 18 Nov 2020 11:54:18 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=8bgKYchYM+nfbrr1GYtm4pfVBjrHm8YD9MQK640tk3o=; b=qRpeAS+bmvZSzyJ4t3jKqlThky4GJ61rSpKwEF/bwrkN/2OgXxha7d56tezehXoiWB a+FrD3XXWdmAGHdUFg6bG+TFkjj11c/5htHQ356SbeMYs5tE92ScLLU7WimxsV+mNt2r EiGeJSQzDumFfBzzwgjiuxgsbgoWg/SK3gof6mpNBRtps/bTQVhYs6WNiJHFiQPRTD3d QXDPoyWmm0kDqKlHB6d4xjfnCne8+n1ggG2yfYN6xYLug9n61JlKjnCxOIbP3ph6ukuW 4Aa70jtvm7vTXXcFfHi6Y09u/OEWBRglhnrHu1wQDRJDLPd1b+kYKsVT9ACXf/wEJgBh DvCA== 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:content-transfer-encoding; bh=8bgKYchYM+nfbrr1GYtm4pfVBjrHm8YD9MQK640tk3o=; b=CE8Eo8le1SEOwstSplpz8hQJlGn1eiG961oV/JWpPOB43L8qyZtJ1LwsMbxunaQR8r M8KUBkInH7dJtR8rUlKSYb+ioU+vKIAYMM6pgWFJa96OPbHoYYvyNAgxOuhtGS3KAv2z Ps/2fcqWaqBQmglE9bQ+dbk47FNOlRzy3LNQoJ/teYph4m1Wmr+fNYxJSNHw+ZNTLF+b 5Z/3Rm4fReLWF7BW2ofHyZUE2FS6jRt9XOObQmULdrBl/9g0wPGUsr5iC0tQ7B6MDHXY M3y7mSQYgwQljijkusW3DQUgILJzfWWjtQxR2gI9KHIczqTlmkd5eiSlC4l5guEl+QA1 y4qQ== X-Gm-Message-State: AOAM531uCyTh8s5HPUyt8WGlxriA/AM7kb1xyYp4Ll5Hgxfe5vM1tnfg Rf4K1Zx3qoMHH+wdpR5hLamc+P+QlBwZ9hruVK4RvBPkPkQ= X-Google-Smtp-Source: ABdhPJxTuapO0G6IJrrkNNVFcECaBL6BIDWdvMeIcWSp2bkBWrh7++G5xYWTMCd0bu6tAlbEZ3CmFGFL+9HZqUMpYfI= X-Received: by 2002:a25:6ec3:: with SMTP id j186mr8398593ybc.335.1605729257515; Wed, 18 Nov 2020 11:54:17 -0800 (PST) MIME-Version: 1.0 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> <7b3f1d07-eca4-b012-c46a-e1f09bba9d6f@gmail.com> In-Reply-To: <7b3f1d07-eca4-b012-c46a-e1f09bba9d6f@gmail.com> From: =?UTF-8?B?TWFoZXNoIEJhbmRld2FyICjgpK7gpLngpYfgpLYg4KSs4KSC4KSh4KWH4KS14KS+4KSwKQ==?= Date: Wed, 18 Nov 2020 11:54:01 -0800 Message-ID: Subject: Re: [PATCH net-next] net-loopback: allow lo dev initial state to be controlled To: David Ahern Cc: nicolas.dichtel@6wind.com, Ido Schimmel , Jakub Kicinski , Jian Yang , David Miller , linux-netdev , Jian Yang , Eric Dumazet Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Wed, Nov 18, 2020 at 10:04 AM David Ahern wrote: > > On 11/18/20 10:39 AM, Mahesh Bandewar (=E0=A4=AE=E0=A4=B9=E0=A5=87=E0=A4= =B6 =E0=A4=AC=E0=A4=82=E0=A4=A1=E0=A5=87=E0=A4=B5=E0=A4=BE=E0=A4=B0) wrote: > > On Wed, Nov 18, 2020 at 8:58 AM Nicolas Dichtel > > wrote: > >> > >> Le 18/11/2020 =C3=A0 02:12, David Ahern a =C3=A9crit : > >> [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 r= eal > >>> 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. I'm open to ideas within the bounds of maintaining backward compatibility. However, not able to see how we can pull it off without creating a 'loopback' device.