rt2x00: Add an error message when trying to send on a full queue

We already tell mac80211 to stop the queue when we hit a certain
threshold. Hence, it shouldn't happen at all that a frame gets queued
for tx on a full queue. Add an error message for this case.
Signed-off-by: Helmut Schaa <helmut.schaa@googlemail.com>
Acked-by: Gertjan van Wingerde <gwingerde@gmail.com>
Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/rt2x00/rt2x00queue.c

@@ -482,8 +482,11 @@ int rt2x00queue_write_tx_frame(struct data_queue *queue, struct sk_buff *skb,
 	struct skb_frame_desc *skbdesc;
 	u8 rate_idx, rate_flags;
 
-	if (unlikely(rt2x00queue_full(queue)))
+	if (unlikely(rt2x00queue_full(queue))) {
+		ERROR(queue->rt2x00dev,
+		      "Dropping frame due to full tx queue %d.\n", queue->qid);
 		return -ENOBUFS;
+	}
 
 	if (unlikely(test_and_set_bit(ENTRY_OWNER_DEVICE_DATA,
 				      &entry->flags))) {