From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Ricardo Leitner Subject: Re: [patch net] ipv6: do not create neighbor entries for local delivery Date: Thu, 08 Aug 2013 16:11:28 -0300 Message-ID: <5203ED60.30108@redhat.com> References: <20130130082608.GA1604@minipsycho.orion> <20130808190136.GE14001@order.stressinduktion.org> <5203EB4C.5020905@redhat.com> <20130808190624.GF14001@order.stressinduktion.org> Reply-To: mleitner@redhat.com Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit To: 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 Return-path: Received: from mx1.redhat.com ([209.132.183.28]:34934 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966155Ab3HHTMK (ORCPT ); Thu, 8 Aug 2013 15:12:10 -0400 In-Reply-To: <20130808190624.GF14001@order.stressinduktion.org> Sender: netdev-owner@vger.kernel.org List-ID: 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." Thanks, Marcelo