This is a note to let you know that I've just added the patch titled
r8169: remove unneeded memory barrier in rtl_tx
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-remove-unneeded-memory-barrier-in-rtl_tx.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 fa50bbd7b5166ac8d67069dd278938a046792afa
Author: Heiner Kallweit <hkallweit1@xxxxxxxxx>
Date: Thu Oct 29 18:56:06 2020 +0100
r8169: remove unneeded memory barrier in rtl_tx
[ Upstream commit 3a689e34973e8717cd57991c6fcf527dc56062b5 ]
tp->dirty_tx isn't changed outside rtl_tx(). Therefore I see no need
to guarantee a specific order of reading tp->dirty_tx and tp->cur_tx.
Having said that we can remove the memory barrier.
In addition use READ_ONCE() when reading tp->cur_tx because it can
change in parallel to rtl_tx().
Signed-off-by: Heiner Kallweit <hkallweit1@xxxxxxxxx>
Link: https://lore.kernel.org/r/2264563a-fa9e-11b0-2c42-31bc6b8e2790@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 c29d43c5f4504..84c8362a65cd1 100644
--- a/drivers/net/ethernet/realtek/r8169_main.c
+++ b/drivers/net/ethernet/realtek/r8169_main.c
@@ -4472,9 +4472,8 @@ static void rtl_tx(struct net_device *dev, struct rtl8169_private *tp,
unsigned int dirty_tx, tx_left, bytes_compl = 0, pkts_compl = 0;
dirty_tx = tp->dirty_tx;
- smp_rmb();
- for (tx_left = tp->cur_tx - dirty_tx; tx_left > 0; tx_left--) {
+ for (tx_left = READ_ONCE(tp->cur_tx) - dirty_tx; tx_left; tx_left--) {
unsigned int entry = dirty_tx % NUM_TX_DESC;
struct sk_buff *skb = tp->tx_skb[entry].skb;
u32 status;
