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Commit ef143585 authored by Heiner Kallweit's avatar Heiner Kallweit Committed by David S. Miller
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r8169: make use of xmit_more 

There was a previous attempt to use xmit_more, but the change had to be
reverted because under load sometimes a transmit timeout occurred [0].
Maybe this was caused by a missing memory barrier, the new attempt
keeps the memory barrier before the call to netif_stop_queue like it
is used by the driver as of today. The new attempt also changes the
order of some calls as suggested by Eric.

[0] https://lkml.org/lkml/2019/2/10/39



Signed-off-by: default avatarHeiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 171a9bae

drivers/net/ethernet/realtek/r8169_main.c

+12 −5
Original line number Diff line number Diff line
@@ -5641,6 +5641,8 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb, 
	struct device *d = tp_to_dev(tp);

	dma_addr_t mapping;

	u32 opts[2], len;

	bool stop_queue;

	bool door_bell;

	int frags;



	if (unlikely(!rtl_tx_slots_avail(tp, skb_shinfo(skb)->nr_frags))) {
@@ -5684,13 +5686,13 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb, 


	txd->opts2 = cpu_to_le32(opts[1]);



	netdev_sent_queue(dev, skb->len);



	skb_tx_timestamp(skb);



	/* Force memory writes to complete before releasing descriptor */

	dma_wmb();



	door_bell = __netdev_sent_queue(dev, skb->len, netdev_xmit_more());



	txd->opts1 = rtl8169_get_txd_opts1(opts[0], len, entry);



	/* Force all memory writes to complete before notifying device */
@@ -5698,14 +5700,19 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb, 


	tp->cur_tx += frags + 1;



	RTL_W8(tp, TxPoll, NPQ);



	if (!rtl_tx_slots_avail(tp, MAX_SKB_FRAGS)) {

	stop_queue = !rtl_tx_slots_avail(tp, MAX_SKB_FRAGS);

	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.

		 */

		smp_wmb();

		netif_stop_queue(dev);

	}



	if (door_bell)

		RTL_W8(tp, TxPoll, NPQ);



	if (unlikely(stop_queue)) {

		/* Sync with rtl_tx:

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

		 * - refresh dirty_tx ring index (read barrier).