ath9k_htc: Handle TX queue overflow

Stop/restart TX queues when the internal SKB
queue is full. This helps handle TX better
under heavy load.

Signed-off-by: Sujith <Sujith.Manoharan@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/htc.h b/drivers/net/wireless/ath/ath9k/htc.h
index 698e6f1..e09c6c2 100644
--- a/drivers/net/wireless/ath/ath9k/htc.h
+++ b/drivers/net/wireless/ath/ath9k/htc.h
@@ -349,6 +349,9 @@
 	struct sk_buff *beacon;
 	spinlock_t beacon_lock;
 
+	bool tx_queues_stop;
+	spinlock_t tx_lock;
+
 	struct ieee80211_vif *vif;
 	unsigned int rxfilter;
 	struct tasklet_struct wmi_tasklet;