Re: [PATCH] ipvs: fix dst_lock locking on dest update

---- Original Message ----
From: Julian Anastasov <ja@ssi.bg>
To: "David S. Miller" <davem@davemloft.net>
Cc: netdev@vger.kernel.org, lvs-devel@vger.kernel.org, "Simon Horman" <horms@verge.net.au>
Sent: Tue, Feb 22, 2011, 9:36 AM
Subject: [PATCH] ipvs: fix dst_lock locking on dest update

Fix dst_lock usage in __ip_vs_update_dest. We need
_bh locking because destination is updated in user context.
Can cause lockups on frequent destination updates.
Problem reported by Simon Kirby. Bug was introduced
in 2.6.37 from the "ipvs: changes for local real server"
change.

Signed-off-by: Julian Anastasov <ja@ssi.bg>

Signed-off-by: Hans Schillstrom <redacted>

---

	Dave, please apply to net-2.6.
Patch is for 2.6.37+ and applies to 2.6.38-rc6. There is
little fuzz when applying to net-next, let me know if
I should provide patch for other trees.

The patch seems to be OK in 2.6.38 expcept for line number.
All my thest runs without any problems.

quoted hunk

--- linux-2.6.37/net/netfilter/ipvs/ip_vs_ctl.c	2011-01-06 00:01:23.600069161 +0200
+++ linux/net/netfilter/ipvs/ip_vs_ctl.c	2011-02-19 23:14:44.463250743 +0200

@@ -810,9 +810,9 @@ __ip_vs_update_dest(struct ip_vs_service
 	dest->u_threshold = udest->u_threshold;
 	dest->l_threshold = udest->l_threshold;

-	spin_lock(&dest->dst_lock);
+	spin_lock_bh(&dest->dst_lock);
 	ip_vs_dst_reset(dest);
-	spin_unlock(&dest->dst_lock);
+	spin_unlock_bh(&dest->dst_lock);

 	if (add)
 		ip_vs_new_estimator(&dest->stats);
--

Hans Schillstrom [off-list ref]