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 21:06:24 +0200 Message-ID: <20130808190624.GF14001@order.stressinduktion.org> References: <20130130082608.GA1604@minipsycho.orion> <20130808190136.GE14001@order.stressinduktion.org> <5203EB4C.5020905@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]:39990 "EHLO order.stressinduktion.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752450Ab3HHTGZ (ORCPT ); Thu, 8 Aug 2013 15:06:25 -0400 Content-Disposition: inline In-Reply-To: <5203EB4C.5020905@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: 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. Greetings, Hannes