Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752731AbdHIJCX (ORCPT ); Wed, 9 Aug 2017 05:02:23 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46594 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752333AbdHIJCW (ORCPT ); Wed, 9 Aug 2017 05:02:22 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com BA92A6406D Authentication-Results: ext-mx01.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx01.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=otubo@redhat.com Reply-To: otubo@redhat.com Subject: Re: [PATCH] hv_set_ifconfig.sh double check before setting ip To: David Miller Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, devel@linuxdriverproject.org, sthemmin@microsoft.com, haiyangz@microsoft.com, kys@microsoft.com References: <20170808135345.17027-1-otubo@redhat.com> <20170808.211150.2070475124549651350.davem@davemloft.net> From: Eduardo Otubo Organization: Red Hat Message-ID: <494db0c8-8c31-f2ce-17fc-7b96b74f0b28@redhat.com> Date: Wed, 9 Aug 2017 11:02:12 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: <20170808.211150.2070475124549651350.davem@davemloft.net> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Wed, 09 Aug 2017 09:02:22 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1366 Lines: 35 On 08/09/2017 06:11 AM, David Miller wrote: > From: Eduardo Otubo > Date: Tue, 8 Aug 2017 15:53:45 +0200 > >> This patch fixes the behavior of the hv_set_ifconfig script when setting >> the interface ip. Sometimes the interface has already been configured by >> network daemon, in this case hv_set_ifconfig causes "RTNETLINK: file >> exists error"; in order to avoid this error this patch makes sure double >> checks the interface before trying anything. >> >> Signed-off-by: Eduardo Otubo > > And if the daemon sets the address after you test it but before > you try to set it in the script, what happens? > > This is why I hate changes like this. They don't remove the problem, > they make it smaller. And smaller in a bad way. Smaller makes the > problem even more harder to diagnose when it happens. > > There is implicitly no synchonization between network configuration > daemons and things people run by hand like this script. > > So, caveat emptor. > > I'm not applying this, sorry. > This is just part of the resolution, actually. For RHEL I also configure hyperv-daemons' systemd config file to be run only after network service is up. So perhaps my solution should be distro-agnostic and only involve this script as part of it? In this case I'll elaborate a little more then. Thanks for the comment.