From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH net v3 2/2] ipv6: fix ECMP route replacement Date: Tue, 19 May 2015 16:51:03 -0400 (EDT) Message-ID: <20150519.165103.1598743813050681946.davem@davemloft.net> References: <239760fdec3e503029fae3e5bb9d4eb3c4c33c20.1431974706.git.mkubecek@suse.cz> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: nicolas.dichtel@6wind.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kuznet@ms2.inr.ac.ru, jmorris@namei.org, yoshfuji@linux-ipv6.org, kaber@trash.net, roopa@cumulusnetworks.com To: mkubecek@suse.cz Return-path: Received: from shards.monkeyblade.net ([149.20.54.216]:48071 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751191AbbESUvG (ORCPT ); Tue, 19 May 2015 16:51:06 -0400 In-Reply-To: <239760fdec3e503029fae3e5bb9d4eb3c4c33c20.1431974706.git.mkubecek@suse.cz> Sender: netdev-owner@vger.kernel.org List-ID: From: Michal Kubecek Date: Mon, 18 May 2015 20:54:00 +0200 (CEST) > When replacing an IPv6 multipath route with "ip route replace", i.e. > NLM_F_CREATE | NLM_F_REPLACE, fib6_add_rt2node() replaces only first > matching route without fixing its siblings, resulting in corrupted > siblings linked list; removing one of the siblings can then end in an > infinite loop. > > IPv6 ECMP implementation is a bit different from IPv4 so that route > replacement cannot work in exactly the same way. This should be a > reasonable approximation: > > 1. If the new route is ECMP-able and there is a matching ECMP-able one > already, replace it and all its siblings (if any). > > 2. If the new route is ECMP-able and no matching ECMP-able route exists, > replace first matching non-ECMP-able (if any) or just add the new one. > > 3. If the new route is not ECMP-able, replace first matching > non-ECMP-able route (if any) or add the new route. > > We also need to remove the NLM_F_REPLACE flag after replacing old > route(s) by first nexthop of an ECMP route so that each subsequent > nexthop does not replace previous one. > > Fixes: 51ebd3181572 ("ipv6: add support of equal cost multipath (ECMP)") > Signed-off-by: Michal Kubecek Can I get some reviews please from interested parties? As far as I can tell, this faithfully implements the policy we decided upon at the end of the previous thread for this patch. But I could be wrong :-) Thanks.