From ef14358546b115d9ea4108f21c6badd97334ad18 Mon Sep 17 00:00:00 2001
From: Heiner Kallweit <hkallweit1@gmail.com>
Date: Sun, 28 Jul 2019 11:25:19 +0200
Subject: [PATCH] r8169: make use of xmit_more
Git-commit: ef14358546b115d9ea4108f21c6badd97334ad18
Patch-mainline: v5.4-rc1
References: bsc#1175746
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: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/net/ethernet/realtek/r8169_main.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)
diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
index 61a23aee0eef..109779e449cd 100644
--- a/drivers/net/ethernet/realtek/r8169_main.c
+++ b/drivers/net/ethernet/realtek/r8169_main.c
@@ -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).
--
2.16.4