[PATCH 1/9] ath9k_htc: Simplify TX URB management

[Sujith <Sujith.Manoharan@atheros.com>]

This patch simplifies URB management for transmission,
by removing the 'FLUSH' variable (which is not needed,
since we can determine if the URB has been killed by
looking at the URB status), and also handling the STOP
case properly.

Signed-off-by: Sujith <Sujith.Manoharan@atheros.com>
---
 drivers/net/wireless/ath/ath9k/hif_usb.c |  100 ++++++++++++++----------------
 drivers/net/wireless/ath/ath9k/hif_usb.h |    1 -
 2 files changed, 46 insertions(+), 55 deletions(-)

diff --git a/drivers/net/wireless/ath/ath9k/hif_usb.c b/drivers/net/wireless/ath/ath9k/hif_usb.c
index 3091bb3..cee5feb 100644
--- a/drivers/net/wireless/ath/ath9k/hif_usb.c
+++ b/drivers/net/wireless/ath/ath9k/hif_usb.c
@@ -93,14 +93,24 @@ static int hif_usb_send_regout(struct hif_device_usb *hif_dev,
 	return ret;
 }
 
+static inline void ath9k_skb_queue_purge(struct hif_device_usb *hif_dev,
+					 struct sk_buff_head *list)
+{
+	struct sk_buff *skb;
+
+	while ((skb = __skb_dequeue(list)) != NULL) {
+		dev_kfree_skb_any(skb);
+		TX_STAT_INC(skb_dropped);
+	}
+}
+
 static void hif_usb_tx_cb(struct urb *urb)
 {
 	struct tx_buf *tx_buf = (struct tx_buf *) urb->context;
 	struct hif_device_usb *hif_dev = tx_buf->hif_dev;
 	struct sk_buff *skb;
-	bool drop, flush;
 
-	if (!hif_dev)
+	if (!hif_dev || !tx_buf)
 		return;
 
 	switch (urb->status) {
@@ -108,57 +118,47 @@ static void hif_usb_tx_cb(struct urb *urb)
 		break;
 	case -ENOENT:
 	case -ECONNRESET:
-		break;
 	case -ENODEV:
 	case -ESHUTDOWN:
+		/*
+		 * The URB has been killed, free the SKBs
+		 * and return.
+		 */
+		ath9k_skb_queue_purge(hif_dev, &tx_buf->skb_queue);
 		return;
 	default:
 		break;
 	}
 
-	if (tx_buf) {
-		spin_lock(&hif_dev->tx.tx_lock);
-		drop = !!(hif_dev->tx.flags & HIF_USB_TX_STOP);
-		flush = !!(hif_dev->tx.flags & HIF_USB_TX_FLUSH);
-		spin_unlock(&hif_dev->tx.tx_lock);
-
-		while ((skb = __skb_dequeue(&tx_buf->skb_queue)) != NULL) {
-			if (!drop && !flush) {
-				ath9k_htc_txcompletion_cb(hif_dev->htc_handle,
-							  skb, 1);
-				TX_STAT_INC(skb_completed);
-			} else {
-				dev_kfree_skb_any(skb);
-				TX_STAT_INC(skb_dropped);
-			}
-		}
-
-		if (flush)
-			return;
-
-		tx_buf->len = tx_buf->offset = 0;
-		__skb_queue_head_init(&tx_buf->skb_queue);
-
-		spin_lock(&hif_dev->tx.tx_lock);
-		list_del(&tx_buf->list);
-		list_add_tail(&tx_buf->list, &hif_dev->tx.tx_buf);
-		hif_dev->tx.tx_buf_cnt++;
-		if (!drop)
-			__hif_usb_tx(hif_dev); /* Check for pending SKBs */
-		TX_STAT_INC(buf_completed);
+	/* Check if TX has been stopped */
+	spin_lock(&hif_dev->tx.tx_lock);
+	if (hif_dev->tx.flags & HIF_USB_TX_STOP) {
 		spin_unlock(&hif_dev->tx.tx_lock);
-	}
-}
-
-static inline void ath9k_skb_queue_purge(struct hif_device_usb *hif_dev,
-					 struct sk_buff_head *list)
-{
-	struct sk_buff *skb;
-
-	while ((skb = __skb_dequeue(list)) != NULL) {
-		dev_kfree_skb_any(skb);
-		TX_STAT_INC(skb_dropped);
-	}
+		ath9k_skb_queue_purge(hif_dev, &tx_buf->skb_queue);
+		goto add_free;
+	}
+	spin_unlock(&hif_dev->tx.tx_lock);
+
+	/* Complete the queued SKBs. */
+	while ((skb = __skb_dequeue(&tx_buf->skb_queue)) != NULL) {
+		ath9k_htc_txcompletion_cb(hif_dev->htc_handle,
+					  skb, 1);
+		TX_STAT_INC(skb_completed);
+	}
+
+add_free:
+	/* Re-initialize the SKB queue */
+	tx_buf->len = tx_buf->offset = 0;
+	__skb_queue_head_init(&tx_buf->skb_queue);
+
+	/* Add this TX buffer to the free list */
+	spin_lock(&hif_dev->tx.tx_lock);
+	list_move_tail(&tx_buf->list, &hif_dev->tx.tx_buf);
+	hif_dev->tx.tx_buf_cnt++;
+	if (!(hif_dev->tx.flags & HIF_USB_TX_STOP))
+		__hif_usb_tx(hif_dev); /* Check for pending SKBs */
+	TX_STAT_INC(buf_completed);
+	spin_unlock(&hif_dev->tx.tx_lock);
 }
 
 /* TX lock has to be taken */
@@ -178,8 +178,7 @@ static int __hif_usb_tx(struct hif_device_usb *hif_dev)
 		return 0;
 
 	tx_buf = list_first_entry(&hif_dev->tx.tx_buf, struct tx_buf, list);
-	list_del(&tx_buf->list);
-	list_add_tail(&tx_buf->list, &hif_dev->tx.tx_pending);
+	list_move_tail(&tx_buf->list, &hif_dev->tx.tx_pending);
 	hif_dev->tx.tx_buf_cnt--;
 
 	tx_skb_cnt = min_t(u16, hif_dev->tx.tx_skb_cnt, MAX_TX_AGGR_NUM);
@@ -548,20 +547,17 @@ free:
 
 static void ath9k_hif_usb_dealloc_tx_urbs(struct hif_device_usb *hif_dev)
 {
-	unsigned long flags;
 	struct tx_buf *tx_buf = NULL, *tx_buf_tmp = NULL;
 
-	list_for_each_entry_safe(tx_buf, tx_buf_tmp, &hif_dev->tx.tx_buf, list) {
+	list_for_each_entry_safe(tx_buf, tx_buf_tmp,
+				 &hif_dev->tx.tx_buf, list) {
+		usb_kill_urb(tx_buf->urb);
 		list_del(&tx_buf->list);
 		usb_free_urb(tx_buf->urb);
 		kfree(tx_buf->buf);
 		kfree(tx_buf);
 	}
 
-	spin_lock_irqsave(&hif_dev->tx.tx_lock, flags);
-	hif_dev->tx.flags |= HIF_USB_TX_FLUSH;
-	spin_unlock_irqrestore(&hif_dev->tx.tx_lock, flags);
-
 	list_for_each_entry_safe(tx_buf, tx_buf_tmp,
 				 &hif_dev->tx.tx_pending, list) {
 		usb_kill_urb(tx_buf->urb);
@@ -570,10 +566,6 @@ static void ath9k_hif_usb_dealloc_tx_urbs(struct hif_device_usb *hif_dev)
 		kfree(tx_buf->buf);
 		kfree(tx_buf);
 	}
-
-	spin_lock_irqsave(&hif_dev->tx.tx_lock, flags);
-	hif_dev->tx.flags &= ~HIF_USB_TX_FLUSH;
-	spin_unlock_irqrestore(&hif_dev->tx.tx_lock, flags);
 }
 
 static int ath9k_hif_usb_alloc_tx_urbs(struct hif_device_usb *hif_dev)
diff --git a/drivers/net/wireless/ath/ath9k/hif_usb.h b/drivers/net/wireless/ath/ath9k/hif_usb.h
index 7d49a8a..0aca49b 100644
--- a/drivers/net/wireless/ath/ath9k/hif_usb.h
+++ b/drivers/net/wireless/ath/ath9k/hif_usb.h
@@ -61,7 +61,6 @@ struct tx_buf {
 };
 
 #define HIF_USB_TX_STOP  BIT(0)
-#define HIF_USB_TX_FLUSH BIT(1)
 
 struct hif_usb_tx {
 	u8 flags;
-- 
1.7.0.5