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=-3.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 CBA81C5519F for ; Thu, 12 Nov 2020 19:54:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6F1A52078D for ; Thu, 12 Nov 2020 19:54:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="ETNNxEOp" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726807AbgKLTyn (ORCPT ); Thu, 12 Nov 2020 14:54:43 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:59326 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726702AbgKLTyn (ORCPT ); Thu, 12 Nov 2020 14:54:43 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1605210881; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=CFQzTySwNt2NOoQnXqVc/FjTwpXdtzoCtvmyjrkFsF0=; b=ETNNxEOpt4vlcRupVUcFnfvRcbOk3pNRDiOvx50kiiZb52UfgSkk3wF9FQ9AErqDObjIcJ 1tWj3wsRSe9oneXS3na8e32t81EOs6xSVPAqZ9j166jOC1j9vcCkgxujbBNGibheUCwD8T CErhZIszHgwoaJ2zJgwjMsZ2AhyHo4I= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-244-I2W0luy2PhO-4mHubwvvgg-1; Thu, 12 Nov 2020 14:54:37 -0500 X-MC-Unique: I2W0luy2PhO-4mHubwvvgg-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 480511087D7B; Thu, 12 Nov 2020 19:54:36 +0000 (UTC) Received: from localhost.localdomain (unknown [10.10.110.55]) by smtp.corp.redhat.com (Postfix) with ESMTP id E21586198C; Thu, 12 Nov 2020 19:54:29 +0000 (UTC) Message-ID: <5616ee6f15c2b9da73d23bcc23eca5befc824abe.camel@redhat.com> Subject: Re: [PATCH net-next] net-loopback: allow lo dev initial state to be controlled From: Dan Williams To: Andrew Lunn , Jian Yang Cc: davem@davemloft.net, kuba@kernel.org, netdev@vger.kernel.org, Mahesh Bandewar , Jian Yang Date: Thu, 12 Nov 2020 13:54:28 -0600 In-Reply-To: <20201112160832.GB1456319@lunn.ch> References: <20201111204308.3352959-1-jianyang.kernel@gmail.com> <20201112160832.GB1456319@lunn.ch> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.5 (3.36.5-1.fc32) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Thu, 2020-11-12 at 17:08 +0100, Andrew Lunn wrote: > On Wed, Nov 11, 2020 at 12:43:08PM -0800, Jian Yang wrote: > > From: Mahesh Bandewar > > > > Traditionally loopback devices comes up with initial state as DOWN > > for > > any new network-namespace. This would mean that anyone needing this > > device (which is mostly true except sandboxes where networking in > > not > > needed at all), would have to bring this UP by issuing something > > like > > 'ip link set lo up' which can be avoided if the initial state can > > be set > > as UP. > > How useful is lo if it is up, but has no IP address? I don't think > this change adds the IP addresses does it? So you still need > something > inside your netns to add the IP addresses? Which seems to make this > change pointless? lo gets addresses automatically these days, no? $ ip netns add blue $ ip netns exec blue ip addr 1: lo: mtu 65536 qdisc noop state DOWN group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 $ ip netns exec blue ip link set lo up $ ip netns exec blue ip addr 1: lo: mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever inet6 ::1/128 scope host valid_lft forever preferred_lft forever Dan