rtl8xxxu: Simplify locking of a skb list accesses

The 'c2hcmd_lock' spinlock is only used to protect some __skb_queue_tail()
and __skb_dequeue() calls.
Use the lock provided in the skb itself and call skb_queue_tail() and
skb_dequeue(). These functions already include the correct locking.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/8bcec6429615aeb498482dc7e1955ce09b456585.1617613700.git.christophe.jaillet@wanadoo.fr

drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu.h

@@ -1391,7 +1391,6 @@ struct rtl8xxxu_priv {
 	struct delayed_work ra_watchdog;
 	struct work_struct c2hcmd_work;
 	struct sk_buff_head c2hcmd_queue;
-	spinlock_t c2hcmd_lock;
 	struct rtl8xxxu_btcoex bt_coex;
 	struct rtl8xxxu_ra_report ra_report;
 };

drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c

@@ -5423,7 +5423,6 @@ static void rtl8xxxu_c2hcmd_callback(struct work_struct *work)
 	struct rtl8xxxu_priv *priv;
 	struct rtl8723bu_c2h *c2h;
 	struct sk_buff *skb = NULL;
-	unsigned long flags;
 	u8 bt_info = 0;
 	struct rtl8xxxu_btcoex *btcoex;
 	struct rtl8xxxu_ra_report *rarpt;
@@ -5439,9 +5438,7 @@ static void rtl8xxxu_c2hcmd_callback(struct work_struct *work)
 		goto out;
 
 	while (!skb_queue_empty(&priv->c2hcmd_queue)) {
-		spin_lock_irqsave(&priv->c2hcmd_lock, flags);
-		skb = __skb_dequeue(&priv->c2hcmd_queue);
-		spin_unlock_irqrestore(&priv->c2hcmd_lock, flags);
+		skb = skb_dequeue(&priv->c2hcmd_queue);
 
 		c2h = (struct rtl8723bu_c2h *)skb->data;
 
@@ -5499,7 +5496,6 @@ static void rtl8723bu_handle_c2h(struct rtl8xxxu_priv *priv,
 	struct rtl8723bu_c2h *c2h = (struct rtl8723bu_c2h *)skb->data;
 	struct device *dev = &priv->udev->dev;
 	int len;
-	unsigned long flags;
 
 	len = skb->len - 2;
 
@@ -5538,9 +5534,7 @@ static void rtl8723bu_handle_c2h(struct rtl8xxxu_priv *priv,
 		break;
 	}
 
-	spin_lock_irqsave(&priv->c2hcmd_lock, flags);
-	__skb_queue_tail(&priv->c2hcmd_queue, skb);
-	spin_unlock_irqrestore(&priv->c2hcmd_lock, flags);
+	skb_queue_tail(&priv->c2hcmd_queue, skb);
 
 	schedule_work(&priv->c2hcmd_work);
 }
@@ -6606,7 +6600,6 @@ static int rtl8xxxu_probe(struct usb_interface *interface,
 	spin_lock_init(&priv->rx_urb_lock);
 	INIT_WORK(&priv->rx_urb_wq, rtl8xxxu_rx_urb_work);
 	INIT_DELAYED_WORK(&priv->ra_watchdog, rtl8xxxu_watchdog_callback);
-	spin_lock_init(&priv->c2hcmd_lock);
 	INIT_WORK(&priv->c2hcmd_work, rtl8xxxu_c2hcmd_callback);
 	skb_queue_head_init(&priv->c2hcmd_queue);