linux-kernel - [PATCH AUTOSEL 4.19 05/68] net: stmmac: don't set own bit too early for jumbo frames

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Message-Id: <20190422194516.11634-5-sashal@kernel.org>
Date:   Mon, 22 Apr 2019 15:44:13 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Aaro Koskinen <aaro.koskinen@...ia.com>,
        "David S . Miller" <davem@...emloft.net>,
        Sasha Levin <sashal@...nel.org>, netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 4.19 05/68] net: stmmac: don't set own bit too early for jumbo frames

From: Aaro Koskinen <aaro.koskinen@...ia.com>

[ Upstream commit 80acbed9f8fca1db3fbe915540b756f048aa0fd7 ]

Commit 0e80bdc9a72d ("stmmac: first frame prep at the end of xmit
routine") overlooked jumbo frames when re-ordering the code, and as a
result the own bit was not getting set anymore for the first jumbo frame
descriptor. Commit 487e2e22ab79 ("net: stmmac: Set OWN bit for jumbo
frames") tried to fix this, but now the bit is getting set too early and
the DMA may start while we are still setting up the remaining descriptors.
And with the chain mode the own bit remains still unset.

Fix by setting the own bit at the end of xmit also with jumbo frames.

Fixes: 0e80bdc9a72d ("stmmac: first frame prep at the end of xmit routine")
Fixes: 487e2e22ab79 ("net: stmmac: Set OWN bit for jumbo frames")
Signed-off-by: Aaro Koskinen <aaro.koskinen@...ia.com>
Acked-by: Jose Abreu <joabreu@...opsys.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin (Microsoft) <sashal@...nel.org>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 886176be818e..3d35cbeb1028 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -3197,14 +3197,16 @@ static netdev_tx_t stmmac_xmit(struct sk_buff *skb, struct net_device *dev)
 		stmmac_prepare_tx_desc(priv, first, 1, nopaged_len,
 				csum_insertion, priv->mode, 1, last_segment,
 				skb->len);
-
-		/* The own bit must be the latest setting done when prepare the
-		 * descriptor and then barrier is needed to make sure that
-		 * all is coherent before granting the DMA engine.
-		 */
-		wmb();
+	} else {
+		stmmac_set_tx_owner(priv, first);
 	}
 
+	/* The own bit must be the latest setting done when prepare the
+	 * descriptor and then barrier is needed to make sure that
+	 * all is coherent before granting the DMA engine.
+	 */
+	wmb();
+
 	netdev_tx_sent_queue(netdev_get_tx_queue(dev, queue), skb->len);
 
 	stmmac_enable_dma_transmission(priv, priv->ioaddr);
-- 
2.19.1