linux-kernel - Re: [PATCH] Make sure the value in abs() does not get truncated if it is greater than 2^32

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Message-ID: <alpine.LNX.2.00.0909120053470.31018@swampdragon.chaosbits.net>
Date:	Sat, 12 Sep 2009 00:54:12 +0200 (CEST)
From:	Jesper Juhl <jj@...osbits.net>
To:	Rolf Eike Beer <eike-kernel@...tec.de>
cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Make sure the value in abs() does not get truncated if
 it is greater than 2^32

On Thu, 3 Sep 2009, Rolf Eike Beer wrote:

> I was just digging a bit around in linux/kernel.h and stumbled over the abs() 
> makro. For me it looks as it would return wrong results on 64 bit platforms 
> if the input value is greater than 2^32.
> 

I think you are right.


> Signed-off-by: Rolf Eike Beer <eike-kernel@...tec.de>
> ---
>  include/linux/kernel.h |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/include/linux/kernel.h b/include/linux/kernel.h
> index d6320a3..1e6eb66 100644
> --- a/include/linux/kernel.h
> +++ b/include/linux/kernel.h
> @@ -145,7 +145,7 @@ extern int _cond_resched(void);
>  #define might_sleep_if(cond) do { if (cond) might_sleep(); } while (0)
>  
>  #define abs(x) ({				\
> -		int __x = (x);			\
> +		long __x = (x);			\
>  		(__x < 0) ? -__x : __x;		\
>  	})
>  
> 

-- 
Jesper Juhl <jj@...osbits.net>             http://www.chaosbits.net/
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