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Date: Sun, 19 Apr 2020 20:15:29 +0200 From: Heiner Kallweit <hkallweit1@...il.com> To: Realtek linux nic maintainers <nic_swsd@...ltek.com>, David Miller <davem@...emloft.net> Cc: "netdev@...r.kernel.org" <netdev@...r.kernel.org> Subject: [PATCH net-next v2 2/3] r8169: replace dma_rmb with READ_ONCE in rtl_rx We want to ensure that desc->opts1 is read before desc->opts2. This doesn't require a full compiler barrier. READ_ONCE provides the ordering guarantee we need. Signed-off-by: Heiner Kallweit <hkallweit1@...il.com> --- drivers/net/ethernet/realtek/r8169_main.c | 11 +++-------- 1 file changed, 3 insertions(+), 8 deletions(-) diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c index dd6113fd7..2fc65aca3 100644 --- a/drivers/net/ethernet/realtek/r8169_main.c +++ b/drivers/net/ethernet/realtek/r8169_main.c @@ -1548,7 +1548,7 @@ static inline u32 rtl8169_tx_vlan_tag(struct sk_buff *skb) static void rtl8169_rx_vlan_tag(struct RxDesc *desc, struct sk_buff *skb) { - u32 opts2 = le32_to_cpu(desc->opts2); + u32 opts2 = le32_to_cpu(READ_ONCE(desc->opts2)); if (opts2 & RxVlanTag) __vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q), swab16(opts2 & 0xffff)); @@ -4490,16 +4490,11 @@ static int rtl_rx(struct net_device *dev, struct rtl8169_private *tp, u32 budget struct RxDesc *desc = tp->RxDescArray + entry; u32 status; - status = le32_to_cpu(desc->opts1); + /* Use READ_ONCE to order descriptor field reads */ + status = le32_to_cpu(READ_ONCE(desc->opts1)); if (status & DescOwn) break; - /* This barrier is needed to keep us from reading - * any other fields out of the Rx descriptor until - * we know the status of DescOwn - */ - dma_rmb(); - if (unlikely(status & RxRES)) { netif_info(tp, rx_err, dev, "Rx ERROR. status = %08x\n", status); -- 2.26.1
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