vxlan: release lock after each bucket in vxlan_cleanup

We're seeing some softlockups from this function when there
are a lot fdb entries on a vxlan device. Taking the lock for
each bucket instead of the whole table is enough to fix that.
Signed-off-by: Sorin Dumitru <sdumitru@ixiacom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/vxlan.c

@@ -2131,9 +2131,10 @@ static void vxlan_cleanup(unsigned long arg)
 	if (!netif_running(vxlan->dev))
 		return;
 
-	spin_lock_bh(&vxlan->hash_lock);
 	for (h = 0; h < FDB_HASH_SIZE; ++h) {
 		struct hlist_node *p, *n;
+
+		spin_lock_bh(&vxlan->hash_lock);
 		hlist_for_each_safe(p, n, &vxlan->fdb_head[h]) {
 			struct vxlan_fdb *f
 				= container_of(p, struct vxlan_fdb, hlist);
@@ -2152,8 +2153,8 @@ static void vxlan_cleanup(unsigned long arg)
 			} else if (time_before(timeout, next_timer))
 				next_timer = timeout;
 		}
+		spin_unlock_bh(&vxlan->hash_lock);
 	}
-	spin_unlock_bh(&vxlan->hash_lock);
 
 	mod_timer(&vxlan->age_timer, next_timer);
 }