Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754309AbbHLIO5 (ORCPT ); Wed, 12 Aug 2015 04:14:57 -0400 Received: from mail-ob0-f176.google.com ([209.85.214.176]:36408 "EHLO mail-ob0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753951AbbHLIOx (ORCPT ); Wed, 12 Aug 2015 04:14:53 -0400 MIME-Version: 1.0 In-Reply-To: <55CA608B.1070302@gmail.com> References: <55C1D207.3040905@iogearbox.net> <55C24BAE.7090702@gmail.com> <55C3B8C8.9030507@redhat.com> <55C4D803.3090108@redhat.com> <878u9njaon.fsf@stressinduktion.org> <878u9jijuc.fsf@stressinduktion.org> <87y4hjgy6p.fsf@stressinduktion.org> <55CA608B.1070302@gmail.com> From: Zang MingJie Date: Wed, 12 Aug 2015 16:14:33 +0800 Message-ID: Subject: Re: [BUG] net/ipv4: inconsistent routing table To: Alexander Duyck Cc: Hannes Frederic Sowa , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2036 Lines: 54 On Wed, Aug 12, 2015 at 4:52 AM, Alexander Duyck wrote: > On 08/10/2015 04:50 AM, Hannes Frederic Sowa wrote: >> >> Hello, >> >> Zang MingJie writes: >> >>> Here comes several options: >>> >>> 1. reject local next hop w/ EINVAL >>> 2. delete route when local next hop removed >> >> Will also cause some people to complain. >> >>> 3. transition between RT_SCOPE_HOST amd RT_SCOPE_LINK >> >> I don't understand the scope transition. I know Alex mentioned it for >> the first time. Maybe he can explain? > > > If I am not mistaken part of the issue in terms of the behaviour being seen > is due to the fact that the nexthop scope is recorded only when the route is > added, and there is code in place in rt_set_nexthop which will only use the > gateway if the scope is RT_SCOPE_LINK. So what we would probably need to do > is go through and audit any routes on a given interface every time an > address is added or removed and if the nh_gw is equal to the address added > or removed would would need to transition between RT_SCOPE_LINK and > RT_SCOPE_HOST since the gateway is transitioning between the local system > and somewhere on the other side of the link. > > The problem is that this would still be a behaviour change and there may be > somebody that has heartburn about it. That's why I'm going to introduce a sysconf entry, with the entry unset, keep compatibility; with the entry set, fix the bug. > >>> 4. document it >> >> I prefer that one :) > > > Yeah, me too. The fact is things have worked this way up until now and I > suspect the reason why this hasn't been reported until now is simply because > in many cases it works since routes are usually updated if you are moving > the gateway onto the local system. > > - Alex -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/