atm: Bad locking on br2684_devs modifications.

The list_del happens under read-locked devs_lock.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/atm/br2684.c b/net/atm/br2684.c
index 3a74ff8..13858e2 100644
--- a/net/atm/br2684.c
+++ b/net/atm/br2684.c
@@ -346,9 +346,9 @@
 		/* skb==NULL means VCC is being destroyed */
 		br2684_close_vcc(brvcc);
 		if (list_empty(&brdev->brvccs)) {
-			read_lock(&devs_lock);
+			write_lock_irq(&devs_lock);
 			list_del(&brdev->br2684_devs);
-			read_unlock(&devs_lock);
+			write_unlock_irq(&devs_lock);
 			unregister_netdev(net_dev);
 		}
 		return;