linux-kernel - [PATCH 3.18 66/85] NET: stmmac: align DMA stuff to largest cache line length

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Date:   Tue,  7 Aug 2018 20:52:08 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 3.18 66/85] NET: stmmac: align DMA stuff to largest cache line length

3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>

[ Upstream commit 9939a46d90c6c76f4533d534dbadfa7b39dc6acc ]

As for today STMMAC_ALIGN macro (which is used to align DMA stuff)
relies on L1 line length (L1_CACHE_BYTES).
This isn't correct in case of system with several cache levels
which might have L1 cache line length smaller than L2 line. This
can lead to sharing one cache line between DMA buffer and other
data, so we can lose this data while invalidate DMA buffer before
DMA transaction.

Fix that by using SMP_CACHE_BYTES instead of L1_CACHE_BYTES for
aligning.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -53,7 +53,7 @@
 #include "stmmac.h"
 #include <linux/reset.h>

-#define STMMAC_ALIGN(x)	L1_CACHE_ALIGN(x)
+#define	STMMAC_ALIGN(x)		__ALIGN_KERNEL(x, SMP_CACHE_BYTES)

 /* Module parameters */
 #define TX_TIMEO	5000