mac80211: debounce queue stop/wake

When the queue status changes we need to do a fair
bit of work, so ignore no-op changes early.
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

net/mac80211/util.c

@@ -276,6 +276,9 @@ static void __ieee80211_wake_queue(struct ieee80211_hw *hw, int queue,
 	if (WARN_ON(queue >= hw->queues))
 		return;
 
+	if (!test_bit(reason, &local->queue_stop_reasons[queue]))
+		return;
+
 	__clear_bit(reason, &local->queue_stop_reasons[queue]);
 
 	if (local->queue_stop_reasons[queue] != 0)
@@ -323,6 +326,9 @@ static void __ieee80211_stop_queue(struct ieee80211_hw *hw, int queue,
 	if (WARN_ON(queue >= hw->queues))
 		return;
 
+	if (test_bit(reason, &local->queue_stop_reasons[queue]))
+		return;
+
 	__set_bit(reason, &local->queue_stop_reasons[queue]);
 
 	rcu_read_lock();