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Commit ae1f23fb authored by Francois Romieu's avatar Francois Romieu
Browse files

r8169: fix early queue wake-up. 



With infinite gratitude to Eric Dumazet for allowing me to identify
the error.

Signed-off-by: default avatarFrancois Romieu <romieu@fr.zoreil.com>
Acked-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Cc: Hayes Wang <hayeswang@realtek.com>
parent aacafba8

drivers/net/ethernet/realtek/r8169.c

+18 −0
Original line number Original line Diff line number Diff line
@@ -5559,7 +5559,18 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb, 
	mmiowb();

	mmiowb();





	if (TX_BUFFS_AVAIL(tp) < MAX_SKB_FRAGS) {

	if (TX_BUFFS_AVAIL(tp) < MAX_SKB_FRAGS) {

		/* Avoid wrongly optimistic queue wake-up: rtl_tx thread must

		 * not miss a ring update when it notices a stopped queue.

		 */

		smp_wmb();

		netif_stop_queue(dev);

		netif_stop_queue(dev);

		/* Sync with rtl_tx:

		 * - publish queue status and cur_tx ring index (write barrier)

		 * - refresh dirty_tx ring index (read barrier).

		 * May the current thread have a pessimistic view of the ring

		 * status and forget to wake up queue, a racing rtl_tx thread

		 * can't.

		 */

		smp_mb();

		smp_mb();

		if (TX_BUFFS_AVAIL(tp) >= MAX_SKB_FRAGS)

		if (TX_BUFFS_AVAIL(tp) >= MAX_SKB_FRAGS)

			netif_wake_queue(dev);

			netif_wake_queue(dev);
@@ -5659,6 +5670,13 @@ static void rtl_tx(struct net_device *dev, struct rtl8169_private *tp) 




	if (tp->dirty_tx != dirty_tx) {

	if (tp->dirty_tx != dirty_tx) {

		tp->dirty_tx = dirty_tx;

		tp->dirty_tx = dirty_tx;

		/* Sync with rtl8169_start_xmit:

		 * - publish dirty_tx ring index (write barrier)

		 * - refresh cur_tx ring index and queue status (read barrier)

		 * May the current thread miss the stopped queue condition,

		 * a racing xmit thread can only have a right view of the

		 * ring status.

		 */

		smp_mb();

		smp_mb();

		if (netif_queue_stopped(dev) &&

		if (netif_queue_stopped(dev) &&

		    (TX_BUFFS_AVAIL(tp) >= MAX_SKB_FRAGS)) {

		    (TX_BUFFS_AVAIL(tp) >= MAX_SKB_FRAGS)) {