libertas: use private SDIO workqueue to avoid scheduling latency

The libertas SDIO interface scheduled the packet worker, resulting in
unwanted latency for every data packet or command sent to the firmware.
Fix a bug on the SDIO probe error path too.
Signed-off-by: NDan Williams <dcbw@redhat.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/libertas/if_sdio.c

@@ -95,6 +95,8 @@ struct if_sdio_card {
 
 	spinlock_t		lock;
 	struct if_sdio_packet	*packets;
+
+	struct workqueue_struct	*workqueue;
 	struct work_struct	packet_worker;
 };
 
@@ -746,7 +748,7 @@ static int if_sdio_host_to_card(struct lbs_private *priv,
 
 	spin_unlock_irqrestore(&card->lock, flags);
 
-	schedule_work(&card->packet_worker);
+	queue_work(card->workqueue, &card->packet_worker);
 
 	ret = 0;
 
@@ -836,6 +838,7 @@ static int if_sdio_probe(struct sdio_func *func,
 	card->func = func;
 	card->model = model;
 	spin_lock_init(&card->lock);
+	card->workqueue = create_workqueue("libertas_sdio");
 	INIT_WORK(&card->packet_worker, if_sdio_host_to_card_worker);
 
 	for (i = 0;i < ARRAY_SIZE(if_sdio_models);i++) {
@@ -933,9 +936,8 @@ static int if_sdio_probe(struct sdio_func *func,
 	return ret;
 
 err_activate_card:
-	flush_scheduled_work();
-	free_netdev(priv->dev);
-	kfree(priv);
+	flush_workqueue(card->workqueue);
+	lbs_remove_card(priv);
 reclaim:
 	sdio_claim_host(func);
 release_int:
@@ -945,6 +947,7 @@ static int if_sdio_probe(struct sdio_func *func,
 release:
 	sdio_release_host(func);
 free:
+	destroy_workqueue(card->workqueue);
 	while (card->packets) {
 		packet = card->packets;
 		card->packets = card->packets->next;
@@ -971,7 +974,8 @@ static void if_sdio_remove(struct sdio_func *func)
 	lbs_stop_card(card->priv);
 	lbs_remove_card(card->priv);
 
-	flush_scheduled_work();
+	flush_workqueue(card->workqueue);
+	destroy_workqueue(card->workqueue);
 
 	sdio_claim_host(func);
 	sdio_release_irq(func);