This is a note to let you know that I've just added the patch titled
r8169: improve rtl8169_start_xmit
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
r8169-improve-rtl8169_start_xmit.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 9e7264d0481da6e57af83dffd7f6d21d6c37b042
Author: Heiner Kallweit <hkallweit1@xxxxxxxxx>
Date: Sat Nov 14 21:49:53 2020 +0100
r8169: improve rtl8169_start_xmit
[ Upstream commit 41294e6a434d4f19e957c55b275ea0324f275009 ]
Improve the following in rtl8169_start_xmit:
- tp->cur_tx can be accessed in parallel by rtl_tx(), therefore
annotate the race by using WRITE_ONCE
- avoid checking stop_queue a second time by moving the doorbell check
- netif_stop_queue() uses atomic operation set_bit() that includes a
full memory barrier on some platforms, therefore use
smp_mb__after_atomic to avoid overhead
Signed-off-by: Heiner Kallweit <hkallweit1@xxxxxxxxx>
Link: https://lore.kernel.org/r/80085451-3eaf-507a-c7c0-08d607c46fbc@xxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Stable-dep-of: c71e3a5cffd5 ("r8169: Fix possible ring buffer corruption on fragmented Tx packets.")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
index 0847b64fbb2f4..b678fd1436a4c 100644
--- a/drivers/net/ethernet/realtek/r8169_main.c
+++ b/drivers/net/ethernet/realtek/r8169_main.c
@@ -4331,7 +4331,7 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb,
/* rtl_tx needs to see descriptor changes before updated tp->cur_tx */
smp_wmb();
- tp->cur_tx += frags + 1;
+ WRITE_ONCE(tp->cur_tx, tp->cur_tx + frags + 1);
stop_queue = !rtl_tx_slots_avail(tp, MAX_SKB_FRAGS);
if (unlikely(stop_queue)) {
@@ -4340,13 +4340,6 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb,
*/
smp_wmb();
netif_stop_queue(dev);
- door_bell = true;
- }
-
- if (door_bell)
- rtl8169_doorbell(tp);
-
- 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).
@@ -4354,11 +4347,15 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb,
* status and forget to wake up queue, a racing rtl_tx thread
* can't.
*/
- smp_mb();
+ smp_mb__after_atomic();
if (rtl_tx_slots_avail(tp, MAX_SKB_FRAGS))
netif_start_queue(dev);
+ door_bell = true;
}
+ if (door_bell)
+ rtl8169_doorbell(tp);
+
return NETDEV_TX_OK;
err_dma_1:
