From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sergei Shtylyov Subject: Re: PROBLEM: Linux 3.9 more-specific ipv6 route ignored until next-hop is in neighbor cache Date: Wed, 03 Jul 2013 22:21:19 +0400 Message-ID: <51D46B9F.6050400@cogentembedded.com> References: <20130703050007.GA11216@order.stressinduktion.org> <20130703181546.GC12615@order.stressinduktion.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit To: Pierre Emeriaud , netdev@vger.kernel.org, yoshfuji@linux-ipv6.org Return-path: Received: from mail-la0-f43.google.com ([209.85.215.43]:54282 "EHLO mail-la0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932633Ab3GCSVW (ORCPT ); Wed, 3 Jul 2013 14:21:22 -0400 Received: by mail-la0-f43.google.com with SMTP id gw10so447224lab.30 for ; Wed, 03 Jul 2013 11:21:19 -0700 (PDT) In-Reply-To: <20130703181546.GC12615@order.stressinduktion.org> Sender: netdev-owner@vger.kernel.org List-ID: Hello. On 07/03/2013 10:15 PM, Hannes Frederic Sowa wrote: > I looked up the relevant RFCs and do think this is the proper fix. Could you > give it a test? > [PATCH net] ipv6: rt6_check_neigh should successfully verify neigh if no NUD information are available > After the removal of rt->n we do not create a neighbour entry at route > insertion time (rt6_bind_neighbour is gone). As long as no neighbour is > created because of "useful traffic" we skip this routing entry because > rt6_check_neigh cannot pick up a valid neighbour (neigh == NULL) and > thus returns false. > This change was introduced by commit > 887c95cc1da53f66a5890fdeab13414613010097 ("ipv6: Complete neighbour > entry removal from dst_entry.") > To quote RFC4191: > "If the host has no information about the router's reachability, then > the host assumes the router is reachable." > and also: > "A host MUST NOT probe a router's reachability in the absence of useful > traffic that the host would have sent to the router if it were reachable." > So, just assume the router is reachable and let's rt6_probe do the > rest. We don't need to create a neighbour on route insertion time. > If we don't compile with CONFIG_IPV6_ROUTER_PREF (RFC4191 support) > a neighbour is only valid if its nud_state is NUD_VALID. I did not find > any references that we should probe the router on route insertion time > via the other RFCs. So skip this route in that case. > Reported-by: Pierre Emeriaud > Cc: YOSHIFUJI Hideaki > Signed-off-by: Hannes Frederic Sowa > --- > net/ipv6/route.c | 4 ++++ > 1 file changed, 4 insertions(+) > diff --git a/net/ipv6/route.c b/net/ipv6/route.c > index ad0aa6b..450979d 100644 > --- a/net/ipv6/route.c > +++ b/net/ipv6/route.c > @@ -547,6 +547,10 @@ static inline bool rt6_check_neigh(struct rt6_info *rt) > ret = true; > #endif > read_unlock(&neigh->lock); > + } else { > +#ifdef CONFIG_IPV6_ROUTER_PREF How about: } else if (IS_ENABLED(CONFIG_IPV6_ROUTER_PREF)) { > + ret = true; > +#endif > } WBR, Sergei