rt2x00: Always call ieee80211_stop_queue() when return NETDEV_TX_BUSY

Apparently it was possible that ieee80211_stop_queue() was not full while
NETDEV_TX_BUSY was being reported back. I think that is what causing the WARN_ON().
This moves all calls to ieee80211_stop_queue() in rt2x00mac.c where it is easier
to determine if the queue should be halted.

Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/rt2x00/rt2x00mac.c b/drivers/net/wireless/rt2x00/rt2x00mac.c
index bae4442..1ab2fb6 100644
--- a/drivers/net/wireless/rt2x00/rt2x00mac.c
+++ b/drivers/net/wireless/rt2x00/rt2x00mac.c
@@ -84,7 +84,7 @@
 	 */
 	if (!test_bit(DEVICE_PRESENT, &rt2x00dev->flags)) {
 		ieee80211_stop_queues(hw);
-		return 0;
+		return NETDEV_TX_OK;
 	}
 
 	/*
@@ -110,15 +110,24 @@
 	if (!is_rts_frame(frame_control) && !is_cts_frame(frame_control) &&
 	    (control->flags & (IEEE80211_TXCTL_USE_RTS_CTS |
 			       IEEE80211_TXCTL_USE_CTS_PROTECT))) {
-		if (rt2x00_ring_free(ring) <= 1)
+		if (rt2x00_ring_free(ring) <= 1) {
+			ieee80211_stop_queue(rt2x00dev->hw, control->queue);
 			return NETDEV_TX_BUSY;
+		}
 
-		if (rt2x00mac_tx_rts_cts(rt2x00dev, ring, skb, control))
+		if (rt2x00mac_tx_rts_cts(rt2x00dev, ring, skb, control)) {
+			ieee80211_stop_queue(rt2x00dev->hw, control->queue);
 			return NETDEV_TX_BUSY;
+		}
 	}
 
-	if (rt2x00dev->ops->lib->write_tx_data(rt2x00dev, ring, skb, control))
+	if (rt2x00dev->ops->lib->write_tx_data(rt2x00dev, ring, skb, control)) {
+		ieee80211_stop_queue(rt2x00dev->hw, control->queue);
 		return NETDEV_TX_BUSY;
+	}
+
+	if (rt2x00_ring_full(ring))
+		ieee80211_stop_queue(rt2x00dev->hw, control->queue);
 
 	if (rt2x00dev->ops->lib->kick_tx_queue)
 		rt2x00dev->ops->lib->kick_tx_queue(rt2x00dev, control->queue);