usb: gadget: u_ether: use better list accessors

We have helpers for some of these, let's rely on them instead of open
coding what they do in u_ether.c
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/gadget/function/u_ether.c

@@ -401,13 +401,12 @@ static int alloc_requests(struct eth_dev *dev, struct gether *link, unsigned n)
 static void rx_fill(struct eth_dev *dev, gfp_t gfp_flags)
 {
 	struct usb_request	*req;
+	struct usb_request	*tmp;
 	unsigned long		flags;
 
 	/* fill unused rxq slots with some skb */
 	spin_lock_irqsave(&dev->req_lock, flags);
-	while (!list_empty(&dev->rx_reqs)) {
-		req = container_of(dev->rx_reqs.next,
-				struct usb_request, list);
+	list_for_each_entry_safe(req, tmp, &dev->rx_reqs, list) {
 		list_del_init(&req->list);
 		spin_unlock_irqrestore(&dev->req_lock, flags);
 
@@ -527,7 +526,7 @@ static netdev_tx_t eth_start_xmit(struct sk_buff *skb,
 		return NETDEV_TX_BUSY;
 	}
 
-	req = container_of(dev->tx_reqs.next, struct usb_request, list);
+	req = list_first_entry(&dev->tx_reqs, struct usb_request, list);
 	list_del(&req->list);
 
 	/* temporarily stop TX queue when the freelist empties */
@@ -1122,6 +1121,7 @@ void gether_disconnect(struct gether *link)
 {
 	struct eth_dev		*dev = link->ioport;
 	struct usb_request	*req;
+	struct usb_request	*tmp;
 
 	WARN_ON(!dev);
 	if (!dev)
@@ -1138,9 +1138,7 @@ void gether_disconnect(struct gether *link)
 	 */
 	usb_ep_disable(link->in_ep);
 	spin_lock(&dev->req_lock);
-	while (!list_empty(&dev->tx_reqs)) {
-		req = container_of(dev->tx_reqs.next,
-					struct usb_request, list);
+	list_for_each_entry_safe(req, tmp, &dev->tx_reqs, list) {
 		list_del(&req->list);
 
 		spin_unlock(&dev->req_lock);
@@ -1152,9 +1150,7 @@ void gether_disconnect(struct gether *link)
 
 	usb_ep_disable(link->out_ep);
 	spin_lock(&dev->req_lock);
-	while (!list_empty(&dev->rx_reqs)) {
-		req = container_of(dev->rx_reqs.next,
-					struct usb_request, list);
+	list_for_each_entry_safe(req, tmp, &dev->rx_reqs, list) {
 		list_del(&req->list);
 
 		spin_unlock(&dev->req_lock);