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=-11.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 74DEAC433E0 for ; Tue, 9 Feb 2021 11:58:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1EDE764E6F for ; Tue, 9 Feb 2021 11:58:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230074AbhBIL6S (ORCPT ); Tue, 9 Feb 2021 06:58:18 -0500 Received: from hqnvemgate26.nvidia.com ([216.228.121.65]:6174 "EHLO hqnvemgate26.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229608AbhBIL4A (ORCPT ); Tue, 9 Feb 2021 06:56:00 -0500 Received: from hqmail.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate26.nvidia.com (using TLS: TLSv1.2, AES256-SHA) id ; Tue, 09 Feb 2021 03:55:06 -0800 Received: from DRHQMAIL107.nvidia.com (10.27.9.16) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Tue, 9 Feb 2021 11:55:06 +0000 Received: from yaviefel (172.20.145.6) by DRHQMAIL107.nvidia.com (10.27.9.16) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Tue, 9 Feb 2021 11:55:04 +0000 References: <20210201233445.2044327-1-jianyang.kernel@gmail.com> User-agent: mu4e 1.4.10; emacs 27.1 From: Petr Machata To: Jian Yang CC: , , , Mahesh Bandewar , Jian Yang Subject: Re: [PATCH net-next v3] net-loopback: set lo dev initial state to UP In-Reply-To: <20210201233445.2044327-1-jianyang.kernel@gmail.com> Date: Tue, 9 Feb 2021 12:54:59 +0100 Message-ID: <87czx978x8.fsf@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [172.20.145.6] X-ClientProxiedBy: HQMAIL111.nvidia.com (172.20.187.18) To DRHQMAIL107.nvidia.com (10.27.9.16) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1612871706; bh=aegypDXr+8IR3JMPfc+C8psFduede0a9I2TflVS0M1E=; h=References:User-agent:From:To:CC:Subject:In-Reply-To:Date: Message-ID:MIME-Version:Content-Type:X-Originating-IP: X-ClientProxiedBy; b=eumHX7Mz17JIFmdGnsj5Jxy38Db63Mae6v9EIqSC/JQjyxyMmqpSoxLV/p6TV7SUv QmLBCf9TYwjLwHj96iF5kSXV1LR7oVJqYjAbGCAvwCOTRJYmpETNzptUV1THuurYna ynsqm6FiYhIqC2nag54AGATDqYx8ntcmqsbbil8lqHXcNslaZ9x5tyyvaQV+JNuIX9 JRERUJ3/j9wpO+MTVgxi3RRFkoaeDg0JZuDCkHeOzOy3+53OR0EukqCRkBzVAvyk3p A3HuZaQNII49cSASjWSm8C3XdpQb+MkfP5WjPhdE4Ga5wWjSfENwn8CkS1hS4wLqVV fPhIT1yJVtafg== Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Jian Yang writes: > From: Jian Yang > > Traditionally loopback devices come up with initial state as DOWN for > any new network-namespace. This would mean that anyone needing this > device would have to bring this UP by issuing something like 'ip link > set lo up'. This can be avoided if the initial state is set as UP. This will break user scripts, and it fact breaks kernel's very own selftest. We currently have this internally: diff --git a/tools/testing/selftests/net/fib_nexthops.sh b/tools/testing/selftests/net/fib_nexthops.sh index 4c7d33618437..bf8ed24ab3ba 100755 --- a/tools/testing/selftests/net/fib_nexthops.sh +++ b/tools/testing/selftests/net/fib_nexthops.sh @@ -121,8 +121,6 @@ create_ns() set -e ip netns add ${n} ip netns set ${n} $((nsid++)) - ip -netns ${n} addr add 127.0.0.1/8 dev lo - ip -netns ${n} link set lo up ip netns exec ${n} sysctl -qw net.ipv4.ip_forward=1 ip netns exec ${n} sysctl -qw net.ipv4.fib_multipath_use_neigh=1 -- 2.26.2 This now fails because the ip commands are run within a "set -e" block, and kernel rejects addition of a duplicate address.