netdev - Re: [PATCH RFC] ipv6: fix route selection if kernel is not compiled with CONFIG_IPV6_ROUTER

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Date:	Wed, 10 Jul 2013 17:59:04 +0200
From:	Hannes Frederic Sowa <hannes@...essinduktion.org>
To:	Nicolas Dichtel <nicolas.dichtel@...nd.com>,
	netdev@...r.kernel.org, yoshfuji@...ux-ipv6.org,
	petrus.lt@...il.com, davem@...emloft.net
Subject: Re: [PATCH RFC] ipv6: fix route selection if kernel is not compiled with CONFIG_IPV6_ROUTER_PREF

On Wed, Jul 10, 2013 at 05:20:01PM +0200, Hannes Frederic Sowa wrote:
> On Wed, Jul 10, 2013 at 04:10:58PM +0200, Nicolas Dichtel wrote:
> > Le 10/07/2013 15:21, Hannes Frederic Sowa a écrit :
> > >On Wed, Jul 10, 2013 at 02:22:55PM +0200, Nicolas Dichtel wrote:
> > >>Le 10/07/2013 12:53, Hannes Frederic Sowa a écrit :
> > >The route with rt6i_gateway does actually expire because I got it from
> > >autoconf and ip -6 r l confirms this, too. It seems this is only the cached
> > >route (I will confirm shortly). Is this still ok?
> > I wonder why expires is 0. Even if this route is cached, the flag 
> > RTF_EXPIRES should be set. Am I wrong?
> 
> It seems it is possible cached route gets its expiration updated. As
> such it is not counted in the iteration but it is found as a sibling and its
> nsiblings count is updated again.

ip6_link_failure is the problem. We need to remove the route directly instead
of calling rt6_update_expires:

static void ip6_link_failure(struct sk_buff *skb)
{
        struct rt6_info *rt;

        icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_ADDR_UNREACH, 0);

        rt = (struct rt6_info *) skb_dst(skb);
        if (rt) {
                if (rt->rt6i_flags & RTF_CACHE)
                        rt6_update_expires(rt, 0);
                else if (rt->rt6i_node && (rt->rt6i_flags & RTF_DEFAULT))
                        rt->rt6i_node->fn_sernum = -1;
        }
}

Thanks,

  Hannes

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