From: Thomas Graf <tgraf@redhat.com>
Date: Thu, 9 Dec 2010 14:31:50 -0500
Subject: [net] ipv6: try all routers with unknown reachable state
Message-id: <20101209143150.GA10723@lsx.localdomain>
Patchwork-id: 30024
O-Subject: [RHEL5.6 PATCH] ipv6: Try to use all routers which are not known to
	be unreachable (BZ661393)
Bugzilla: 661393
RH-Acked-by: Neil Horman <nhorman@redhat.com>
RH-Acked-by: Jiri Pirko <jpirko@redhat.com>
RH-Acked-by: David S. Miller <davem@redhat.com>

rt6_check_neigh() is currently assuming that all !NUD_VALID
neighbours are unreachable. This assumption is wrong and
results in all routes being unreachable if the nexthop of such
routes is not the default gateway. Instead we should consider
all neighbours which are !NUD_FAILED while prioritizing
neighbours known to be valid.

Straight backport of:
commit ea73ee23c43d6eb75f88c4fc9e1230b44673c0d2
Author: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Date:   Mon Nov 6 09:45:44 2006 -0800

    [IPV6] ROUTE: Try to use router which is not known unreachable.

    Only routers in "FAILED" state should be considered unreachable.
    Otherwise, we do not try to use speicific routes unless all least specific
    routers are considered unreachable.

    Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>

Brew:
https://brewweb.devel.redhat.com/taskinfo?taskID=2939324

Tested by the customer.

Please ACK!

Signed-off-by: Jarod Wilson <jarod@redhat.com>

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 87a1d5c..17b6acc 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -341,6 +341,8 @@ static int inline rt6_check_neigh(struct rt6_info *rt)
 		read_lock_bh(&neigh->lock);
 		if (neigh->nud_state & NUD_VALID)
 			m = 2;
+		else if (!(neigh->nud_state & NUD_FAILED))
+			m = 1;
 		read_unlock_bh(&neigh->lock);
 	}
 	return m;