r8169: remove nr_frags argument from rtl_tx_slots_avail

The only time when nr_frags isn't SKB_MAX_FRAGS is when entering
rtl8169_start_xmit(). However we can use SKB_MAX_FRAGS also here
because when queue isn't stopped there should always be room for
MAX_SKB_FRAGS + 1 descriptors.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Link: https://lore.kernel.org/r/3d1f2ad7-31d5-2cac-4f4a-394f8a3cab63@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/realtek/r8169_main.c

@@ -4141,14 +4141,13 @@ static bool rtl8169_tso_csum_v2(struct rtl8169_private *tp,
 	return true;
 }
 
-static bool rtl_tx_slots_avail(struct rtl8169_private *tp,
-			       unsigned int nr_frags)
+static bool rtl_tx_slots_avail(struct rtl8169_private *tp)
 {
 	unsigned int slots_avail = READ_ONCE(tp->dirty_tx) + NUM_TX_DESC
 					- READ_ONCE(tp->cur_tx);
 
 	/* A skbuff with nr_frags needs nr_frags+1 entries in the tx queue */
-	return slots_avail > nr_frags;
+	return slots_avail > MAX_SKB_FRAGS;
 }
 
 /* Versions RTL8102e and from RTL8168c onwards support csum_v2 */
@@ -4183,7 +4182,7 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb,
 
 	txd_first = tp->TxDescArray + entry;
 
-	if (unlikely(!rtl_tx_slots_avail(tp, frags))) {
+	if (unlikely(!rtl_tx_slots_avail(tp))) {
 		if (net_ratelimit())
 			netdev_err(dev, "BUG! Tx Ring full when queue awake!\n");
 		goto err_stop_0;
@@ -4228,7 +4227,7 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb,
 
 	WRITE_ONCE(tp->cur_tx, tp->cur_tx + frags + 1);
 
-	stop_queue = !rtl_tx_slots_avail(tp, MAX_SKB_FRAGS);
+	stop_queue = !rtl_tx_slots_avail(tp);
 	if (unlikely(stop_queue)) {
 		/* Avoid wrongly optimistic queue wake-up: rtl_tx thread must
 		 * not miss a ring update when it notices a stopped queue.
@@ -4243,7 +4242,7 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb,
 		 * can't.
 		 */
 		smp_mb__after_atomic();
-		if (rtl_tx_slots_avail(tp, MAX_SKB_FRAGS))
+		if (rtl_tx_slots_avail(tp))
 			netif_start_queue(dev);
 		door_bell = true;
 	}
@@ -4394,10 +4393,8 @@ static void rtl_tx(struct net_device *dev, struct rtl8169_private *tp,
 		 * ring status.
 		 */
 		smp_store_mb(tp->dirty_tx, dirty_tx);
-		if (netif_queue_stopped(dev) &&
-		    rtl_tx_slots_avail(tp, MAX_SKB_FRAGS)) {
+		if (netif_queue_stopped(dev) && rtl_tx_slots_avail(tp))
 			netif_wake_queue(dev);
-		}
 		/*
 		 * 8168 hack: TxPoll requests are lost when the Tx packets are
 		 * too close. Let's kick an extra TxPoll request when a burst