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Date: Thu, 16 Jul 2009 11:19:20 +0800
From: Amerigo Wang <xiyou.wangcong@gmail.com>
To: Joe Perches <joe@perches.com>
Cc: LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] kernel.h: Verify that arguments to swap() are the same
	type
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On Wed, Jul 15, 2009 at 06:34:21PM -0700, Joe Perches wrote:
>Signed-off-by: Joe Perches <joe@perches.com>
>

Hmm, sounds reasonable.

Does this catch any actual wrong usages of swap()?

Acked-by: WANG Cong <xiyou.wangcong@gmail.com>


>diff --git a/include/linux/kernel.h b/include/linux/kernel.h
>index d6320a3..72878a5 100644
>--- a/include/linux/kernel.h
>+++ b/include/linux/kernel.h
>@@ -637,8 +637,13 @@ static inline void ftrace_dump(void) { }
> /*
>  * swap - swap value of @a and @b
>  */
>-#define swap(a, b) \
>-	do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0)
>+#define swap(a, b)				\
>+do {						\
>+	typeof(a) __tmp = (a);			\
>+	BUILD_BUG_ON(!__same_type(__tmp, (b)));	\
>+	(a) = (b);				\
>+	(b) = __tmp;				\
>+} while (0)
> 
> /**
>  * container_of - cast a member of a structure out to the containing structure
>
>
>--
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