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([2a01:e0a:410:bb00:4d55:9a74:c1b4:3b01]) by smtp.gmail.com with ESMTPSA id o17sm7979490wmd.34.2020.11.19.00.03.05 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 19 Nov 2020 00:03:06 -0800 (PST) Reply-To: nicolas.dichtel@6wind.com 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==?= Cc: David Ahern , 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: Nicolas Dichtel Organization: 6WIND Message-ID: Date: Thu, 19 Nov 2020 09:03:05 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 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 Le 18/11/2020 à 18:39, Mahesh Bandewar (महेश बंडेवार) a écrit : > 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 Sure. > 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. The networking is very limited with only a loopback. Do you have some real use case in mind?