bridge: Fix potential deadlock on br->multicast_lock

multicast_lock is taken in softirq context, so we should use
spin_lock_bh() in userspace.

call-chain in softirq context:
run_timer_softirq()
	br_multicast_query_expired()

call-chain in userspace:
sysfs_write_file()
	store_multicast_snooping()
		br_multicast_toggle()

Signed-off-by: Andrew Vagin <avagin@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index 995cbe0ac0b2b1e74f2b4762d61a13102d9f66bb..2eefe275b338827968f7c62ab856d23151d7a494 100644 (file)
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -1770,7 +1770,7 @@ int br_multicast_toggle(struct net_bridge *br, unsigned long val)
        int err = 0;
        struct net_bridge_mdb_htable *mdb;
 
-       spin_lock(&br->multicast_lock);
+       spin_lock_bh(&br->multicast_lock);
        if (br->multicast_disabled == !val)
                goto unlock;
 
@@ -1806,7 +1806,7 @@ rollback:
        }
 
 unlock:
-       spin_unlock(&br->multicast_lock);
+       spin_unlock_bh(&br->multicast_lock);
 
        return err;
 }