From 794867ee6730fe3f0d419d3911f35a725cafe3a8 Mon Sep 17 00:00:00 2001
From: Heiner Kallweit <hkallweit1@gmail.com>
Date: Mon, 20 Apr 2020 22:52:59 +0200
Subject: [PATCH] r8169: change wmb to smb_wmb in rtl8169_start_xmit
Git-commit: 794867ee6730fe3f0d419d3911f35a725cafe3a8
Patch-mainline: v5.8-rc1
References: bsc#1175746
A barrier is needed here to ensure that rtl_tx sees the descriptor
changes (DescOwn set) before the updated tp->cur_tx value. Else it may
wrongly assume that the transfer has been finished already. For this
purpose smp_wmb() is sufficient.
No separate barrier is needed for ordering the descriptor changes
with the MMIO doorbell write. The needed barrier is included in
the non-relaxed writel() used by rtl8169_doorbell().
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 | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
index b8cc064ee9f5..b7a2853e7396 100644
--- a/drivers/net/ethernet/realtek/r8169_main.c
+++ b/drivers/net/ethernet/realtek/r8169_main.c
@@ -4249,8 +4249,8 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb,
txd_first->opts1 |= cpu_to_le32(DescOwn | FirstFrag);
- /* Force all memory writes to complete before notifying device */
- wmb();
+ /* rtl_tx needs to see descriptor changes before updated tp->cur_tx */
+ smp_wmb();
tp->cur_tx += frags + 1;
--
2.16.4