[PATCH v2] wifi: ath9k_htc: bound TX aggregation to MAX_TX_BUF_SIZE

[Georgios Karantzas <gck.kara@gmail.com>]

Bound the TX batch by cumulative byte length, not just record count.

Fixes: fb9987d0f748c983 ("ath9k_htc: Support for AR9271 chipset.")
Signed-off-by: Georgios Karantzas <gck.kara@gmail.com>
---
v2:
- 72-col wrap + Fixes: tag.
- Accounting kept: deferred len += offset never fires on early break.
- (!i) guard dropped per review.

 drivers/net/wireless/ath/ath9k/hif_usb.c | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/drivers/net/wireless/ath/ath9k/hif_usb.c b/drivers/net/wireless/ath/ath9k/hif_usb.c
index 0a3d2190b..533e74565 100644
--- a/drivers/net/wireless/ath/ath9k/hif_usb.c
+++ b/drivers/net/wireless/ath/ath9k/hif_usb.c
@@ -328,11 +328,14 @@ static int __hif_usb_tx(struct hif_device_usb *hif_dev)
 	tx_skb_cnt = min_t(u16, hif_dev->tx.tx_skb_cnt, MAX_TX_AGGR_NUM);
 
 	for (i = 0; i < tx_skb_cnt; i++) {
-		nskb = __skb_dequeue(&hif_dev->tx.tx_skb_queue);
+		nskb = skb_peek(&hif_dev->tx.tx_skb_queue);
+		if (!nskb)
+			break;
 
-		/* Should never be NULL */
-		BUG_ON(!nskb);
+		if (tx_buf->offset + nskb->len + 4 > MAX_TX_BUF_SIZE)
+			break;
 
+		nskb = __skb_dequeue(&hif_dev->tx.tx_skb_queue);
 		hif_dev->tx.tx_skb_cnt--;
 
 		buf = tx_buf->buf;
@@ -342,13 +345,8 @@ static int __hif_usb_tx(struct hif_device_usb *hif_dev)
 		*hdr++ = cpu_to_le16(ATH_USB_TX_STREAM_MODE_TAG);
 		buf += 4;
 		memcpy(buf, nskb->data, nskb->len);
-		tx_buf->len = nskb->len + 4;
-
-		if (i < (tx_skb_cnt - 1))
-			tx_buf->offset += (((tx_buf->len - 1) / 4) + 1) * 4;
-
-		if (i == (tx_skb_cnt - 1))
-			tx_buf->len += tx_buf->offset;
+		tx_buf->len = tx_buf->offset + nskb->len + 4;
+		tx_buf->offset += (((nskb->len + 3) / 4) + 1) * 4;
 
 		__skb_queue_tail(&tx_buf->skb_queue, nskb);
 		TX_STAT_INC(hif_dev, skb_queued);
-- 
2.47.3