From: Heiner Kallweit <hkallweit1@gmail.com>
To: Realtek linux nic maintainers <nic_swsd@realtek.com>,
David Miller <davem@davemloft.net>
Cc: "netdev@vger.kernel.org" <netdev@vger.kernel.org>
Subject: [PATCH net-next v2 2/3] r8169: replace dma_rmb with READ_ONCE in rtl_rx
Date: Sun, 19 Apr 2020 20:15:29 +0200 [thread overview]
Message-ID: <70576d8a-1bb3-c692-6dbd-2304c233e592@gmail.com> (raw)
In-Reply-To: <a7e1d491-bede-6f86-cff0-f2b74d8af2b3@gmail.com>
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@gmail.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
next prev parent reply other threads:[~2020-04-19 18:16 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-19 18:13 [PATCH net-next v2 0/3] r8169: improve memory barriers Heiner Kallweit
2020-04-19 18:14 ` [PATCH net-next v2 1/3] r8169: use smp_store_mb in rtl_tx Heiner Kallweit
2020-04-19 18:15 ` Heiner Kallweit [this message]
2020-04-19 18:16 ` [PATCH net-next v2 3/3] r8169: use WRITE_ONCE instead of dma_wmb in rtl8169_mark_to_asic Heiner Kallweit
2020-04-19 19:00 ` Petko Manolov
2020-04-19 21:03 ` Heiner Kallweit
2020-04-19 21:38 ` Petko Manolov
2020-04-19 21:52 ` Heiner Kallweit
2020-04-19 22:33 ` Eric Dumazet
2020-04-19 21:54 ` [PATCH net-next v2 0/3] r8169: improve memory barriers Heiner Kallweit
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