wlcore: Use spin_trylock in wlcore_irq() to see if we need to queue tx

We currently have a collection of flags and locking between the
threaded irq and tx work:

- wl->flags bitops
- wl->mutex
- wl->wl_lock spinlock

The bitops flags do not need a spinlock around them, and we only need
the spinlock to see if we need to queue tx work or not. And wlcore_irq()
holds the mutex.

To simplify the locking, we can use spin_trylock and always queue tx
work unless we know there's nothing to do.

Let's also update the comment a bit while at it.

Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200702162951.45392-4-tony@atomide.com

diff --git a/drivers/net/wireless/ti/wlcore/main.c b/drivers/net/wireless/ti/wlcore/main.c
index 458457cbab59ce22a1494fca967b7d518dcce201..4cdfd4f566affbc033a6ebd812e0eb5b756fcf3a 100644 (file)
--- a/drivers/net/wireless/ti/wlcore/main.c
+++ b/drivers/net/wireless/ti/wlcore/main.c
@@ -652,6 +652,7 @@ static irqreturn_t wlcore_irq(int irq, void *cookie)
        int ret;
        unsigned long flags;
        struct wl1271 *wl = cookie;
+       bool queue_tx_work = true;
 
        set_bit(WL1271_FLAG_IRQ_RUNNING, &wl->flags);
 
@@ -684,13 +685,17 @@ static irqreturn_t wlcore_irq(int irq, void *cookie)
        if (ret)
                wl12xx_queue_recovery_work(wl);
 
-       spin_lock_irqsave(&wl->wl_lock, flags);
-       /* In case TX was not handled here, queue TX work */
+       /* In case TX was not handled in wlcore_irq_locked(), queue TX work */
        clear_bit(WL1271_FLAG_TX_PENDING, &wl->flags);
-       if (!test_bit(WL1271_FLAG_FW_TX_BUSY, &wl->flags) &&
-           wl1271_tx_total_queue_count(wl) > 0)
-               ieee80211_queue_work(wl->hw, &wl->tx_work);
-       spin_unlock_irqrestore(&wl->wl_lock, flags);
+       if (!test_bit(WL1271_FLAG_FW_TX_BUSY, &wl->flags)) {
+               if (spin_trylock_irqsave(&wl->wl_lock, flags)) {
+                       if (!wl1271_tx_total_queue_count(wl))
+                               queue_tx_work = false;
+                       spin_unlock_irqrestore(&wl->wl_lock, flags);
+               }
+               if (queue_tx_work)
+                       ieee80211_queue_work(wl->hw, &wl->tx_work);
+       }
 
        mutex_unlock(&wl->mutex);