From: "Michael S. Tsirkin" <mst@redhat.com>
To: Pan Xinhui <xinhui@linux.vnet.ibm.com>
Cc: linux-kernel@vger.kernel.org, ysato@users.sourceforge.jp,
dalias@libc.org, peterz@infradead.org, linux-sh@vger.kernel.org
Subject: Re: [PATCH] sh: cmpxchg: fix a bit shift bug in big_endian os
Date: Tue, 19 Apr 2016 10:00:38 +0000 [thread overview]
Message-ID: <20160419125927-mutt-send-email-mst@redhat.com> (raw)
In-Reply-To: <5715D72D.7060501@linux.vnet.ibm.com>
On Tue, Apr 19, 2016 at 02:58:53PM +0800, Pan Xinhui wrote:
> From: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
>
> Correct bitoff in big endian OS.
>
> Fixes: 3226aad81aa6 ("sh: support 1 and 2 byte xchg")
> Signed-off-by: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
I would add: current code works correctly for 1 byte but not for 2 bytes.
Acked-by: Michael S. Tsirkin <mst@redhat.com>
> ---
> arch/sh/include/asm/cmpxchg-xchg.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/sh/include/asm/cmpxchg-xchg.h b/arch/sh/include/asm/cmpxchg-xchg.h
> index 7219719..1e881f5 100644
> --- a/arch/sh/include/asm/cmpxchg-xchg.h
> +++ b/arch/sh/include/asm/cmpxchg-xchg.h
> @@ -21,7 +21,7 @@ static inline u32 __xchg_cmpxchg(volatile void *ptr, u32 x, int size)
> int off = (unsigned long)ptr % sizeof(u32);
> volatile u32 *p = ptr - off;
> #ifdef __BIG_ENDIAN
> - int bitoff = (sizeof(u32) - 1 - off) * BITS_PER_BYTE;
> + int bitoff = (sizeof(u32) - size - off) * BITS_PER_BYTE;
> #else
> int bitoff = off * BITS_PER_BYTE;
> #endif
> --
> 1.9.1
next prev parent reply other threads:[~2016-04-19 10:00 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-19 6:58 [PATCH] sh: cmpxchg: fix a bit shift bug in big_endian os Pan Xinhui
2016-04-19 10:00 ` Michael S. Tsirkin [this message]
2016-04-20 6:41 ` [PATCH V2]sh: " Pan Xinhui
2016-04-26 1:39 ` Rich Felker
2016-04-26 10:07 ` Pan Xinhui
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