wlcore: Use spin_trylock in wlcore_irq_locked() for running the queue

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
wlcore_irq() already holds the mutex calling wlcore_irq_locked().
And we only need the spinlock to see if we need to run the queue
or not.

To simplify the locking, we can use spin_trylock and always run the
tx queue unless we know there's nothing to do.
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200702162951.45392-3-tony@atomide.com

drivers/net/wireless/ti/wlcore/main.c

@@ -521,6 +521,7 @@ static int wlcore_irq_locked(struct wl1271 *wl)
 	int ret = 0;
 	u32 intr;
 	int loopcount = WL1271_IRQ_MAX_LOOPS;
+	bool run_tx_queue = true;
 	bool done = false;
 	unsigned int defer_count;
 	unsigned long flags;
@@ -586,19 +587,22 @@ static int wlcore_irq_locked(struct wl1271 *wl)
 				goto err_ret;
 
 			/* Check if any tx blocks were freed */
-			spin_lock_irqsave(&wl->wl_lock, flags);
-			if (!test_bit(WL1271_FLAG_FW_TX_BUSY, &wl->flags) &&
-			    wl1271_tx_total_queue_count(wl) > 0) {
-				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))
+						run_tx_queue = false;
+					spin_unlock_irqrestore(&wl->wl_lock, flags);
+				}
+
 				/*
 				 * In order to avoid starvation of the TX path,
 				 * call the work function directly.
 				 */
-				ret = wlcore_tx_work_locked(wl);
-				if (ret < 0)
-					goto err_ret;
-			} else {
-				spin_unlock_irqrestore(&wl->wl_lock, flags);
+				if (run_tx_queue) {
+					ret = wlcore_tx_work_locked(wl);
+					if (ret < 0)
+						goto err_ret;
+				}
 			}
 
 			/* check for tx results */