linux-kernel - [PATCH 3.14 119/140] neigh: set nud_state to NUD_INCOMPLETE when probing router reachability

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Message-Id: <20140529043104.915904961@linuxfoundation.org>
Date:	Wed, 28 May 2014 21:34:18 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Duan Jiong <duanj.fnst@...fujitsu.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: [PATCH 3.14 119/140] neigh: set nud_state to NUD_INCOMPLETE when probing router reachability

3.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Duan Jiong <duanj.fnst@...fujitsu.com>

[ Upstream commit 2176d5d41891753774f648b67470398a5acab584 ]

Since commit 7e98056964("ipv6: router reachability probing"), a router falls
into NUD_FAILED will be probed.

Now if function rt6_select() selects a router which neighbour state is NUD_FAILED,
and at the same time function rt6_probe() changes the neighbour state to NUD_PROBE,
then function dst_neigh_output() can directly send packets, but actually the
neighbour still is unreachable. If we set nud_state to NUD_INCOMPLETE instead
NUD_PROBE, packets will not be sent out until the neihbour is reachable.

In addition, because the route should be probes with a single NS, so we must
set neigh->probes to neigh_max_probes(), then the neigh timer timeout and function
neigh_timer_handler() will not send other NS Messages.

Signed-off-by: Duan Jiong <duanj.fnst@...fujitsu.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/core/neighbour.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -1247,8 +1247,8 @@ void __neigh_set_probe_once(struct neigh
 	neigh->updated = jiffies;
 	if (!(neigh->nud_state & NUD_FAILED))
 		return;
-	neigh->nud_state = NUD_PROBE;
-	atomic_set(&neigh->probes, NEIGH_VAR(neigh->parms, UCAST_PROBES));
+	neigh->nud_state = NUD_INCOMPLETE;
+	atomic_set(&neigh->probes, neigh_max_probes(neigh));
 	neigh_add_timer(neigh,
 			jiffies + NEIGH_VAR(neigh->parms, RETRANS_TIME));
 }

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