diff mbox series

[net-next] r8169: remove unneeded memory barrier in rtl_tx

Message ID 2264563a-fa9e-11b0-2c42-31bc6b8e2790@gmail.com (mailing list archive)
State Not Applicable
Delegated to: Netdev Maintainers
Headers show
Series [net-next] r8169: remove unneeded memory barrier in rtl_tx | expand

Commit Message

Heiner Kallweit Oct. 29, 2020, 5:56 p.m. UTC
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@gmail.com>
---
 drivers/net/ethernet/realtek/r8169_main.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

Comments

Jakub Kicinski Oct. 31, 2020, 11:36 p.m. UTC | #1
On Thu, 29 Oct 2020 18:56:06 +0100 Heiner Kallweit wrote:
> 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@gmail.com>

Applied, thanks!
diff mbox series

Patch

diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
index b6c11aaa5..75df476c6 100644
--- a/drivers/net/ethernet/realtek/r8169_main.c
+++ b/drivers/net/ethernet/realtek/r8169_main.c
@@ -4364,9 +4364,8 @@  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;