netdev - [PATCH v2] neigh: set nud_state to NUD_INCOMPLETE when probing router reachability

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Message-ID: <536C64C0.5050204@cn.fujitsu.com>
Date:	Fri, 9 May 2014 13:16:48 +0800
From:	Duan Jiong <duanj.fnst@...fujitsu.com>
To:	David Miller <davem@...emloft.net>
CC:	netdev <netdev@...r.kernel.org>, Jiri Benc <jbenc@...hat.com>,
	<hannes@...essinduktion.org>
Subject: [PATCH v2] neigh: set nud_state to NUD_INCOMPLETE when probing router
 reachability

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>
---
Changes from v1:
	*modify changelog to explain in detail why use neigh_max_probes().

 net/core/neighbour.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 8f8a96e..32d872e 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -1248,8 +1248,8 @@ void __neigh_set_probe_once(struct neighbour *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));
 }
-- 
1.8.3.1
--
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