From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Fri, 5 Mar 2010 21:03:35 +0000 (+0000)
Subject: bridge: Fix RCU race in br_multicast_stop
X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=10cc2b50eb4b01ca4dc014af2094d28b4ebe20d7;p=openwrt%2Fstaging%2Fblogic.git

bridge: Fix RCU race in br_multicast_stop

Thanks to Paul McKenny for pointing out that it is incorrect to use
synchronize_rcu_bh to ensure that pending callbacks have completed.
Instead we should use rcu_barrier_bh.

Reported-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index a1ffe1582c9a..12ce1eaa4f3e 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -1135,7 +1135,7 @@ void br_multicast_stop(struct net_bridge *br)
 
 	if (mdb->old) {
 		spin_unlock_bh(&br->multicast_lock);
-		synchronize_rcu_bh();
+		rcu_barrier_bh();
 		spin_lock_bh(&br->multicast_lock);
 		WARN_ON(mdb->old);
 	}