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 a1ffe15..12ce1ea 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -1135,7 +1135,7 @@
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);
}