From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steffen Klassert Subject: Re: [PATCH RFC 1/2] ipv6: Fix after pmtu events dissapearing host routes Date: Mon, 9 Feb 2015 11:26:21 +0100 Message-ID: <20150209102620.GC13046@secunet.com> References: <54C78B8D.1070104@huawei.com> <20150128121026.GM13046@secunet.com> <20150128121150.GN13046@secunet.com> <20150205235628.GA1916791@devbig242.prn2.facebook.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: Yang Yingliang , netdev , Hannes Frederic Sowa , "David S. Miller" To: Martin Lau Return-path: Received: from a.mx.secunet.com ([195.81.216.161]:60123 "EHLO a.mx.secunet.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759491AbbBIK02 (ORCPT ); Mon, 9 Feb 2015 05:26:28 -0500 Content-Disposition: inline In-Reply-To: <20150205235628.GA1916791@devbig242.prn2.facebook.com> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, Feb 05, 2015 at 03:56:29PM -0800, Martin Lau wrote: > On Wed, Jan 28, 2015 at 01:11:51PM +0100, Steffen Klassert wrote: > > We currently don't clone host routes before we use them. > > If a pmtu event is received on such a route, it gets > > an expires value. As soon as the expiration time is > > elapsed, the route is deleted. As a result, the host > > is not reachable any more. > > > > We fix this by cloning host routes if they are gatewayed, > > i.e. if pmtu events can happen. > > > > Signed-off-by: Steffen Klassert > > --- > > net/ipv6/route.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/net/ipv6/route.c b/net/ipv6/route.c > > index c910831..3e864e7 100644 > > --- a/net/ipv6/route.c > > +++ b/net/ipv6/route.c > > @@ -961,7 +961,7 @@ redo_rt6_select: > > > > if (!(rt->rt6i_flags & (RTF_NONEXTHOP | RTF_GATEWAY))) > > nrt = rt6_alloc_cow(rt, &fl6->daddr, &fl6->saddr); > > - else if (!(rt->dst.flags & DST_HOST)) > > + else if (!(rt->dst.flags & DST_HOST) || (rt->rt6i_flags & RTF_GATEWAY)) > > nrt = rt6_alloc_clone(rt, &fl6->daddr); > The del path may also require changes. I am thinking: > 1. Create a /128 via gateway route > 2. Send some traffic and RTF_CACHE rt is created > 3. Delete the /128 route by ip route del. I suspect the RTF_CACHE route may be > deleted and the route added in (1) stays. Good point. Both routes are on the same fib node. The cached one has the better metric, so I guess this one will be found and deleted. I'll check this. Thanks for the hint!