Commit e7332a41 authored by David Gnedt's avatar David Gnedt Committed by John W. Linville
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wl1251: fix queue stopping/waking for TX path 



The queue stopping/waking functionality was broken in a way that could
cause the TX to stall if the right circumstances are met.

The problem was caused by tx_work, which is scheduled on each TX operation.
If the firmware buffer is full, tx_work does nothing. In combinition with
stopped queues or non-continues transfers, tx_work is never scheduled again.
Moreover the low watermark introduced by
9df86e2e never takes effect because of some
old code.

Solve this by scheduling tx_work every time tx_queue is non-empty and
firmware buffer is freed on tx_complete.

This also solves a possible but unlikely case: If less frames than the high
watermark are queued, but more than firmware buffer can hold. This results
in queues staying awake but the only scheduled tx_work doesn't transfer all
frames, so the remaining frames are stuck in the queue until more frames
get queued and tx_work is scheduled again.

Signed-off-by: default avatarDavid Gnedt <david.gnedt@davizone.at>
Acked-by: default avatarKalle Valo <kvalo@adurom.com>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent 172710bf

drivers/net/wireless/wl1251/tx.c

+12 −36
Original line number Diff line number Diff line
@@ -368,7 +368,7 @@ static void wl1251_tx_packet_cb(struct wl1251 *wl, 
{

	struct ieee80211_tx_info *info;

	struct sk_buff *skb;

	int hdrlen, ret;

	int hdrlen;

	u8 *frame;



	skb = wl->tx_frames[result->id];
@@ -407,40 +407,12 @@ static void wl1251_tx_packet_cb(struct wl1251 *wl, 
	ieee80211_tx_status(wl->hw, skb);



	wl->tx_frames[result->id] = NULL;



	if (wl->tx_queue_stopped) {

		wl1251_debug(DEBUG_TX, "cb: queue was stopped");



		skb = skb_dequeue(&wl->tx_queue);



		/* The skb can be NULL because tx_work might have been

		   scheduled before the queue was stopped making the

		   queue empty */



		if (skb) {

			ret = wl1251_tx_frame(wl, skb);

			if (ret == -EBUSY) {

				/* firmware buffer is still full */

				wl1251_debug(DEBUG_TX, "cb: fw buffer "

					     "still full");

				skb_queue_head(&wl->tx_queue, skb);

				return;

			} else if (ret < 0) {

				dev_kfree_skb(skb);

				return;

			}

		}



		wl1251_debug(DEBUG_TX, "cb: waking queues");

		ieee80211_wake_queues(wl->hw);

		wl->tx_queue_stopped = false;

	}

}



/* Called upon reception of a TX complete interrupt */

void wl1251_tx_complete(struct wl1251 *wl)

{

	int i, result_index, num_complete = 0;

	int i, result_index, num_complete = 0, queue_len;

	struct tx_result result[FW_TX_CMPLT_BLOCK_SIZE], *result_ptr;

	unsigned long flags;
@@ -471,18 +443,22 @@ void wl1251_tx_complete(struct wl1251 *wl) 
		}

	}



	if (wl->tx_queue_stopped

	    &&

	    skb_queue_len(&wl->tx_queue) <= WL1251_TX_QUEUE_LOW_WATERMARK){

	queue_len = skb_queue_len(&wl->tx_queue);



		/* firmware buffer has space, restart queues */

	if ((num_complete > 0) && (queue_len > 0)) {

		/* firmware buffer has space, reschedule tx_work */

		wl1251_debug(DEBUG_TX, "tx_complete: reschedule tx_work");

		ieee80211_queue_work(wl->hw, &wl->tx_work);

	}



	if (wl->tx_queue_stopped &&

	    queue_len <= WL1251_TX_QUEUE_LOW_WATERMARK) {

		/* tx_queue has space, restart queues */

		wl1251_debug(DEBUG_TX, "tx_complete: waking queues");

		spin_lock_irqsave(&wl->wl_lock, flags);

		ieee80211_wake_queues(wl->hw);

		wl->tx_queue_stopped = false;

		spin_unlock_irqrestore(&wl->wl_lock, flags);

		ieee80211_queue_work(wl->hw, &wl->tx_work);



	}



	/* Every completed frame needs to be acknowledged */