From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nicolas Dichtel Subject: Re: [PATCH net v3 2/2] ipv6: fix ECMP route replacement Date: Wed, 20 May 2015 10:56:31 +0200 Message-ID: <555C4C3F.8030003@6wind.com> References: <239760fdec3e503029fae3e5bb9d4eb3c4c33c20.1431974706.git.mkubecek@suse.cz> Reply-To: nicolas.dichtel@6wind.com Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Alexey Kuznetsov , James Morris , Hideaki YOSHIFUJI , Patrick McHardy , roopa To: Michal Kubecek , "David S. Miller" Return-path: In-Reply-To: <239760fdec3e503029fae3e5bb9d4eb3c4c33c20.1431974706.git.mkubecek@suse.cz> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Le 18/05/2015 20:54, Michal Kubecek a =C3=A9crit : > 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 on= e > already, replace it and all its siblings (if any). > > 2. If the new route is ECMP-able and no matching ECMP-able route exis= ts, > replace first matching non-ECMP-able (if any) or just add the new one= =2E > > 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 LGTM. Acked-by: Nicolas Dichtel