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wl1251: Fix queue stopping/waking for TX path 

This patch was adapted from 06f7bc7db7
(from linus's linux-2.6 tree of kernel.org)

here's the original message:
    The queue stopping/waking functionality was broken in a way that could
    cause huge latencies in TX transfers and even cause the TX to stall in the
    right circumstances. Correct these problems.

Signed-off-by: Denis 'GNUtoo' Carikli <GNUtoo@no-log.org>
Acked-by: Kalle Valo <kvalo@adurom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Denis 'GNUtoo' Carikli 2010-08-27 23:48:19 +02:00 committed by John W. Linville
parent 391a200a89
commit 9df86e2e70
3 changed files with 24 additions and 13 deletions
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5
drivers/net/wireless/wl12xx/wl1251.h
View File

@ -272,6 +272,8 @@ struct wl1251 {
int irq;
bool use_eeprom;
spinlock_t wl_lock;
enum wl1251_state state;
struct mutex mutex;
@ -399,7 +401,8 @@ void wl1251_disable_interrupts(struct wl1251 *wl);
#define WL1251_DEFAULT_POWER_LEVEL 20
#define WL1251_TX_QUEUE_MAX_LENGTH 20
#define WL1251_TX_QUEUE_LOW_WATERMARK 10
#define WL1251_TX_QUEUE_HIGH_WATERMARK 25
#define WL1251_DEFAULT_BEACON_INT 100
#define WL1251_DEFAULT_DTIM_PERIOD 1

12
drivers/net/wireless/wl12xx/wl1251_main.c
View File

@ -375,6 +375,7 @@ static void wl1251_filter_work(struct work_struct *work)
static int wl1251_op_tx(struct ieee80211_hw *hw, struct sk_buff *skb)
{
struct wl1251 *wl = hw->priv;
unsigned long flags;
skb_queue_tail(&wl->tx_queue, skb);
@ -389,16 +390,13 @@ static int wl1251_op_tx(struct ieee80211_hw *hw, struct sk_buff *skb)
* The workqueue is slow to process the tx_queue and we need stop
* the queue here, otherwise the queue will get too long.
*/
if (skb_queue_len(&wl->tx_queue) >= WL1251_TX_QUEUE_MAX_LENGTH) {
if (skb_queue_len(&wl->tx_queue) >= WL1251_TX_QUEUE_HIGH_WATERMARK) {
wl1251_debug(DEBUG_TX, "op_tx: tx_queue full, stop queues");
ieee80211_stop_queues(wl->hw);
/*
* FIXME: this is racy, the variable is not properly
* protected. Maybe fix this by removing the stupid
* variable altogether and checking the real queue state?
*/
spin_lock_irqsave(&wl->wl_lock, flags);
ieee80211_stop_queues(wl->hw);
wl->tx_queue_stopped = true;
spin_unlock_irqrestore(&wl->wl_lock, flags);
}
return NETDEV_TX_OK;

20
drivers/net/wireless/wl12xx/wl1251_tx.c
View File

@ -320,11 +320,6 @@ void wl1251_tx_work(struct work_struct *work)
ret = wl1251_tx_frame(wl, skb);
if (ret == -EBUSY) {
/* firmware buffer is full, stop queues */
wl1251_debug(DEBUG_TX, "tx_work: fw buffer full, "
"stop queues");
ieee80211_stop_queues(wl->hw);
wl->tx_queue_stopped = true;
skb_queue_head(&wl->tx_queue, skb);
goto out;
} else if (ret < 0) {
@ -447,6 +442,7 @@ void wl1251_tx_complete(struct wl1251 *wl)
{
int i, result_index, num_complete = 0;
struct tx_result result[FW_TX_CMPLT_BLOCK_SIZE], *result_ptr;
unsigned long flags;
if (unlikely(wl->state != WL1251_STATE_ON))
return;
@ -475,6 +471,20 @@ void wl1251_tx_complete(struct wl1251 *wl)
}
}
if (wl->tx_queue_stopped
&&
skb_queue_len(&wl->tx_queue) <= WL1251_TX_QUEUE_LOW_WATERMARK){
/* firmware buffer 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 */
if (num_complete) {
/*