linux-kernel - [PATCH 3.16 204/245] net/sonic: Use MMIO accessors

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Message-ID: <lsq.1587683028.584916903@decadent.org.uk>
Date:   Fri, 24 Apr 2020 00:07:11 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "David S. Miller" <davem@...emloft.net>,
        "Finn Thain" <fthain@...egraphics.com.au>,
        "Stan Johnson" <userm57@...oo.com>
Subject: [PATCH 3.16 204/245] net/sonic: Use MMIO accessors

3.16.83-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Finn Thain <fthain@...egraphics.com.au>

commit e3885f576196ddfc670b3d53e745de96ffcb49ab upstream.

The driver accesses descriptor memory which is simultaneously accessed by
the chip, so the compiler must not be allowed to re-order CPU accesses.
sonic_buf_get() used 'volatile' to prevent that. sonic_buf_put() should
have done so too but was overlooked.

Fixes: efcce839360f ("[PATCH] macsonic/jazzsonic network drivers update")
Tested-by: Stan Johnson <userm57@...oo.com>
Signed-off-by: Finn Thain <fthain@...egraphics.com.au>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/net/ethernet/natsemi/sonic.h | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

--- a/drivers/net/ethernet/natsemi/sonic.h
+++ b/drivers/net/ethernet/natsemi/sonic.h
@@ -342,30 +342,30 @@ static void sonic_tx_timeout(struct net_
    as far as we can tell. */
 /* OpenBSD calls this "SWO".  I'd like to think that sonic_buf_put()
    is a much better name. */
-static inline void sonic_buf_put(void* base, int bitmode,
+static inline void sonic_buf_put(u16 *base, int bitmode,
 				 int offset, __u16 val)
 {
 	if (bitmode)
 #ifdef __BIG_ENDIAN
-		((__u16 *) base + (offset*2))[1] = val;
+		__raw_writew(val, base + (offset * 2) + 1);
 #else
-		((__u16 *) base + (offset*2))[0] = val;
+		__raw_writew(val, base + (offset * 2) + 0);
 #endif
 	else
-	 	((__u16 *) base)[offset] = val;
+		__raw_writew(val, base + (offset * 1) + 0);
 }
 
-static inline __u16 sonic_buf_get(void* base, int bitmode,
+static inline __u16 sonic_buf_get(u16 *base, int bitmode,
 				  int offset)
 {
 	if (bitmode)
 #ifdef __BIG_ENDIAN
-		return ((volatile __u16 *) base + (offset*2))[1];
+		return __raw_readw(base + (offset * 2) + 1);
 #else
-		return ((volatile __u16 *) base + (offset*2))[0];
+		return __raw_readw(base + (offset * 2) + 0);
 #endif
 	else
-		return ((volatile __u16 *) base)[offset];
+		return __raw_readw(base + (offset * 1) + 0);
 }
 
 /* Inlines that you should actually use for reading/writing DMA buffers */