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(p200300EA8F29600039DC7003657CDD6E.dip0.t-ipconnect.de. [2003:ea:8f29:6000:39dc:7003:657c:dd6e]) by smtp.googlemail.com with ESMTPSA id k14sm41789390wrp.53.2020.04.19.10.44.37 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 19 Apr 2020 10:44:37 -0700 (PDT) Subject: [PATCH net-next 3/4] r8169: replace dma_rmb with READ_ONCE in rtl_rx From: Heiner Kallweit To: Realtek linux nic maintainers , David Miller Cc: "netdev@vger.kernel.org" References: Message-ID: Date: Sun, 19 Apr 2020 19:42:29 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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 --- 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 038cd6fde..df788063e 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