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>

drivers/net/wireless/ath/ath9k/htc.h

@@ -349,6 +349,9 @@ struct ath9k_htc_priv {
 	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;

drivers/net/wireless/ath/ath9k/htc_drv_init.c

@@ -449,6 +449,7 @@ static int ath9k_init_priv(struct ath9k_htc_priv *priv, u16 devid)
 
 	spin_lock_init(&priv->wmi->wmi_lock);
 	spin_lock_init(&priv->beacon_lock);
+	spin_lock_init(&priv->tx_lock);
 	mutex_init(&priv->mutex);
 	mutex_init(&priv->aggr_work.mutex);
 	tasklet_init(&priv->wmi_tasklet, ath9k_wmi_tasklet,

drivers/net/wireless/ath/ath9k/htc_drv_main.c

@@ -994,7 +994,7 @@ static int ath9k_htc_tx(struct ieee80211_hw *hw, struct sk_buff *skb)
 {
 	struct ieee80211_hdr *hdr;
 	struct ath9k_htc_priv *priv = hw->priv;
-	int padpos, padsize;
+	int padpos, padsize, ret;
 
 	hdr = (struct ieee80211_hdr *) skb->data;
 
@@ -1008,8 +1008,19 @@ static int ath9k_htc_tx(struct ieee80211_hw *hw, struct sk_buff *skb)
 		memmove(skb->data, skb->data + padsize, padpos);
 	}
 
-	if (ath9k_htc_tx_start(priv, skb) != 0) {
-		ath_print(ath9k_hw_common(priv->ah), ATH_DBG_XMIT, "Tx failed");
+	ret = ath9k_htc_tx_start(priv, skb);
+	if (ret != 0) {
+		if (ret == -ENOMEM) {
+			ath_print(ath9k_hw_common(priv->ah), ATH_DBG_XMIT,
+				  "Stopping TX queues\n");
+			ieee80211_stop_queues(hw);
+			spin_lock_bh(&priv->tx_lock);
+			priv->tx_queues_stop = true;
+			spin_unlock_bh(&priv->tx_lock);
+		} else {
+			ath_print(ath9k_hw_common(priv->ah), ATH_DBG_XMIT,
+				  "Tx failed");
+		}
 		goto fail_tx;
 	}
 
@@ -1074,6 +1085,12 @@ static int ath9k_htc_start(struct ieee80211_hw *hw)
 	priv->op_flags &= ~OP_INVALID;
 	htc_start(priv->htc);
 
+	spin_lock_bh(&priv->tx_lock);
+	priv->tx_queues_stop = false;
+	spin_unlock_bh(&priv->tx_lock);
+
+	ieee80211_wake_queues(hw);
+
 mutex_unlock:
 	mutex_unlock(&priv->mutex);
 	return ret;

drivers/net/wireless/ath/ath9k/htc_drv_txrx.c

@@ -226,6 +226,18 @@ void ath9k_tx_tasklet(unsigned long data)
 		/* Send status to mac80211 */
 		ieee80211_tx_status(priv->hw, skb);
 	}
+
+	/* Wake TX queues if needed */
+	spin_lock_bh(&priv->tx_lock);
+	if (priv->tx_queues_stop) {
+		priv->tx_queues_stop = false;
+		spin_unlock_bh(&priv->tx_lock);
+		ath_print(ath9k_hw_common(priv->ah), ATH_DBG_XMIT,
+			  "Waking up TX queues\n");
+		ieee80211_wake_queues(priv->hw);
+		return;
+	}
+	spin_unlock_bh(&priv->tx_lock);
 }
 
 void ath9k_htc_txep(void *drv_priv, struct sk_buff *skb,