Commit 794867ee authored Apr 20, 2020 by Heiner Kallweit Committed by David S. Miller Apr 20, 2020

r8169: change wmb to smb_wmb in rtl8169_start_xmit



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>

parent 82ebc889

drivers/net/ethernet/realtek/r8169_main.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -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;

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