linux-kernel - Re: [PATCH v1 1/1] math.h: Amend kernel-doc and add a note about signed type limits

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Message-ID: <aRID4efkPf6x6Gqi@google.com>
Date: Mon, 10 Nov 2025 23:25:21 +0800
From: Kuan-Wei Chiu <visitorckw@...il.com>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: linux-kernel@...r.kernel.org, Andrew Morton <akpm@...ux-foundation.org>,
	Jonathan Cameron <jic23@...nel.org>
Subject: Re: [PATCH v1 1/1] math.h: Amend kernel-doc and add a note about
 signed type limits

On Thu, Nov 06, 2025 at 04:20:51PM +0100, Andy Shevchenko wrote:
> First of all, amend the existing kernel-doc so the description
> of the function is decoupled with the parameter descriptions.
> Second, add a note to explain behaviour for the signed types when
> supplied value is the minimum (e.g., INT_MIN for int type).
> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>  include/linux/math.h | 13 +++++++++----
>  1 file changed, 9 insertions(+), 4 deletions(-)
> 
> diff --git a/include/linux/math.h b/include/linux/math.h
> index 7fcb980677a0..c02cc5b9e6ae 100644
> --- a/include/linux/math.h
> +++ b/include/linux/math.h
> @@ -180,11 +180,16 @@ __STRUCT_FRACT(u32)
>  
>  /**
>   * abs - return absolute value of an argument
> - * @x: the value.  If it is unsigned type, it is converted to signed type first.
> - *     char is treated as if it was signed (regardless of whether it really is)
> - *     but the macro's return type is preserved as char.
> + * @x: the value.
>   *
> - * Return: an absolute value of x.
> + * If it is unsigned type, @x is converted to signed type first.
> + * char is treated as if it was signed (regardless of whether it really is)
> + * but the macro's return type is preserved as char.
> + *
> + * NOTE, for signed type if @x is the minimum, the returned result is undefined
> + * as there is not enough bits to represent it as a positive number.

Nit: s/is/are

Otherwise, the patch is:
Reviewed-by: Kuan-Wei Chiu <visitorckw@...il.com>

Regards,
Kuan-Wei

> + *
> + * Return: an absolute value of @x.
>   */
>  #define abs(x)	__abs_choose_expr(x, long long,				\
>  		__abs_choose_expr(x, long,				\
> -- 
> 2.50.1
> 
>