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r8169: change wmb to smb_wmb in rtl8169_start_xmit

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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>
This commit is contained in:
Heiner Kallweit 2020-04-20 22:52:59 +02:00 committed by David S. Miller
parent 82ebc88909
commit 794867ee67
1 changed files with 2 additions and 2 deletions
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4
drivers/net/ethernet/realtek/r8169_main.c
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@ -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;