From e7332a41442bde1c14550998cadceca34c967dfc Mon Sep 17 00:00:00 2001 From: David Gnedt Date: Sun, 30 Jan 2011 20:10:46 +0100 Subject: [PATCH] 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 9df86e2e702c6d5547aced7f241addd2d698bb11 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: David Gnedt Acked-by: Kalle Valo Signed-off-by: John W. Linville --- drivers/net/wireless/wl1251/tx.c | 48 ++++++++------------------------ 1 file changed, 12 insertions(+), 36 deletions(-) diff --git a/drivers/net/wireless/wl1251/tx.c b/drivers/net/wireless/wl1251/tx.c index 554b4f9a3d3e..10112de55493 100644 --- a/drivers/net/wireless/wl1251/tx.c +++ b/drivers/net/wireless/wl1251/tx.c @@ -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 */ -- GitLab