staging: wilc1000: use list_head to maintain 'rxq_entry_t elements in rx queue

Make use of 'list_head' data structure to maintain the rx buffer queue.
Modified wilc_wlan_rxq_add() to add the element at the tail by using
list_head API and wilc_wlan_rxq_remove() to remove the element from
head.
Signed-off-by: Ajay Singh <ajay.kathat@microchip.com>
Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/wilc1000/linux_wlan.c

@@ -1119,6 +1119,7 @@ int wilc_netdev_init(struct wilc **wilc, struct device *dev, int io_type,
 	wl->gpio = gpio;
 	wl->hif_func = ops;
 	INIT_LIST_HEAD(&wl->txq_head.list);
+	INIT_LIST_HEAD(&wl->rxq_head.list);
 
 	register_inetaddr_notifier(&g_dev_notifier);
 

drivers/staging/wilc1000/wilc_wfi_netdevice.h

@@ -161,8 +161,7 @@ struct wilc {
 	int txq_entries;
 	int txq_exit;
 
-	struct rxq_entry_t *rxq_head;
-	struct rxq_entry_t *rxq_tail;
+	struct rxq_entry_t rxq_head;
 	int rxq_entries;
 	int rxq_exit;
 

drivers/staging/wilc1000/wilc_wlan.c

@@ -404,15 +404,7 @@ static int wilc_wlan_rxq_add(struct wilc *wilc, struct rxq_entry_t *rqe)
 		return 0;
 
 	mutex_lock(&wilc->rxq_cs);
-	if (!wilc->rxq_head) {
-		rqe->next = NULL;
-		wilc->rxq_head = rqe;
-		wilc->rxq_tail = rqe;
-	} else {
-		wilc->rxq_tail->next = rqe;
-		rqe->next = NULL;
-		wilc->rxq_tail = rqe;
-	}
+	list_add_tail(&rqe->list, &wilc->rxq_head.list);
 	wilc->rxq_entries += 1;
 	mutex_unlock(&wilc->rxq_cs);
 	return wilc->rxq_entries;
@@ -420,17 +412,17 @@ static int wilc_wlan_rxq_add(struct wilc *wilc, struct rxq_entry_t *rqe)
 
 static struct rxq_entry_t *wilc_wlan_rxq_remove(struct wilc *wilc)
 {
-	if (wilc->rxq_head) {
-		struct rxq_entry_t *rqe;
+	struct rxq_entry_t *rqe = NULL;
 
 	mutex_lock(&wilc->rxq_cs);
-		rqe = wilc->rxq_head;
-		wilc->rxq_head = wilc->rxq_head->next;
+	if (!list_empty(&wilc->rxq_head.list)) {
+		rqe = list_first_entry(&wilc->rxq_head.list, struct rxq_entry_t,
+				       list);
+		list_del(&rqe->list);
 		wilc->rxq_entries -= 1;
+	}
 	mutex_unlock(&wilc->rxq_cs);
 	return rqe;
-	}
-	return NULL;
 }
 
 void chip_allow_sleep(struct wilc *wilc)

drivers/staging/wilc1000/wilc_wlan.h

@@ -218,7 +218,7 @@ struct txq_entry_t {
 };
 
 struct rxq_entry_t {
-	struct rxq_entry_t *next;
+	struct list_head list;
 	u8 *buffer;
 	int buffer_size;
 };