From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Frederic Sowa Subject: Re: [patch net] ipv6: do not create neighbor entries for local delivery Date: Thu, 8 Aug 2013 21:16:53 +0200 Message-ID: <20130808191653.GG14001@order.stressinduktion.org> References: <20130130082608.GA1604@minipsycho.orion> <20130808190136.GE14001@order.stressinduktion.org> <5203EB4C.5020905@redhat.com> <20130808190624.GF14001@order.stressinduktion.org> <5203ED60.30108@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Cc: Debabrata Banerjee , Jiri Pirko , "davem@davemloft.net" , "netdev@vger.kernel.org" , Alexey Kuznetsov , "jmorris@namei.org" , "yoshfuji@linux-ipv6.org" , Patrick McHardy , "Banerjee, Debabrata" , Joshua Hunt To: Marcelo Ricardo Leitner Return-path: Received: from order.stressinduktion.org ([87.106.68.36]:40011 "EHLO order.stressinduktion.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966174Ab3HHTQz (ORCPT ); Thu, 8 Aug 2013 15:16:55 -0400 Content-Disposition: inline In-Reply-To: <5203ED60.30108@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, Aug 08, 2013 at 04:11:28PM -0300, Marcelo Ricardo Leitner wrote: > Em 08-08-2013 16:06, Hannes Frederic Sowa escreveu: > >On Thu, Aug 08, 2013 at 04:02:36PM -0300, Marcelo Ricardo Leitner wrote: > >>Em 08-08-2013 16:01, Hannes Frederic Sowa escreveu: > >>>On Thu, Aug 08, 2013 at 02:45:40PM -0400, Debabrata Banerjee wrote: > >>>>On Wed, Jan 30, 2013 at 3:26 AM, Jiri Pirko wrote: > >>>>>From: Marcelo Ricardo Leitner > >>>>I'm not sure this patch is doing the right thing. It seems to break > >>>>IPv6 loopback functionality, it is no longer equivalent to IPv4, as > >>>>stated above. It doesn't just stop neighbor creation but it stops > >>>>cached route creation. Seems like a scary change for a stable tree. > >>>>See below: > >>>> > >>>>$ ip -4 route show local > >>>>local 127.0.0.0/8 dev lo proto kernel scope host src 127.0.0.1 > >>>> > >>>>This local route enables us to use the whole loopback network, any > >>>>address inside 127.0.0.0/8 will work. > >>>> > >>>>$ ping -c1 127.0.0.9 > >>>>PING 127.0.0.9 (127.0.0.9) 56(84) bytes of data. > >>>>64 bytes from 127.0.0.9: icmp_seq=1 ttl=64 time=0.012 ms > >>>> > >>>>--- 127.0.0.9 ping statistics --- > >>>>1 packets transmitted, 1 received, 0% packet loss, time 0ms > >>>>rtt min/avg/max/mdev = 0.012/0.012/0.012/0.000 ms > >>>> > >>>>This also used to work equivalently for IPv6 local loopback routes: > >>>> > >>>>$ ip -6 route add local 2001:::/64 dev lo > >>>>$ ping6 -c1 2001::9 > >>>>PING 2001::9(2001::9) 56 data bytes > >>>>64 bytes from 2001::9: icmp_seq=1 ttl=64 time=0.010 ms > >>>> > >>>>--- 2001::9 ping statistics --- > >>>>1 packets transmitted, 1 received, 0% packet loss, time 0ms > >>>>rtt min/avg/max/mdev = 0.010/0.010/0.010/0.000 ms > >>>> > >>>>However with this patch, this is very broken: > >>>> > >>>>$ ip -6 route add local 2001::/64 dev lo > >>>>$ ping6 -c1 2001::9 > >>>>PING 2001::9(2001::9) 56 data bytes > >>>>ping: sendmsg: Invalid argument > >>>> > >>>>--- 2001::9 ping statistics --- > >>>>1 packets transmitted, 0 received, 100% packet loss, time 0ms > >>> > >>>Which kernel version are you using? Perhaps you miss another fix? It > >>>works > >>>for > >>>me. Also I cannot find this patch in net-next? > >> > >>It wasn't needed/applied as the route cache was removed. > > > >Do you mean the rt->n(eighbour) removal? There was no removal of a route > >cache > >in IPv6 land. The cache is merely in the routing table itself. > > Yes, my bad, sorry. s/route/neighour/. It was discussed on this thread: > http://article.gmane.org/gmane.linux.network/255318 > > "Note also that YOSHIFUJI Hideaki's patches to remove the cached neighbour > entirely from ipv6 routes will have the same effect, so your patch won't > be needed." Ok, thanks! But it somehow managed to get into stable kernels, nor? Kernels after rt->n removal should not be affected. At least the example above works on my net-next kernel correctly. Greetings, Hannes