Re: [PATCH v4 07/13] minmax: Introduce {min,max}_array()

[Andy Shevchenko]

On Wed, Jun 14, 2023 at 10:49 AM Herve Codina <herve.codina@xxxxxxxxxxx> wrote:
>
> Introduce min_array() (resp max_array()) in order to get the
> minimal (resp maximum) of values present in an array.

Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
See a remark below.

> Signed-off-by: Herve Codina <herve.codina@xxxxxxxxxxx>
> ---
>  include/linux/minmax.h | 36 ++++++++++++++++++++++++++++++++++++
>  1 file changed, 36 insertions(+)
>
> diff --git a/include/linux/minmax.h b/include/linux/minmax.h
> index 396df1121bff..2cd0d34ce921 100644
> --- a/include/linux/minmax.h
> +++ b/include/linux/minmax.h
> @@ -133,6 +133,42 @@
>   */
>  #define max_t(type, x, y)      __careful_cmp((type)(x), (type)(y), >)
>
> +/*
> + * Do not check the array parameter using __must_be_array().
> + * In the following legit use-case where the "array" passed is a simple pointer,
> + * __must_be_array() will return a failure.
> + * --- 8< ---
> + * int *buff
> + * ...
> + * min = min_array(buff, nb_items);
> + * --- 8< ---
> + */
> +#define __minmax_array(op, array, len) ({                      \
> +       typeof(array) __array = (array);                        \
> +       typeof(len) __len = (len);                              \
> +       typeof(__array[0] + 0) __element = __array[--__len];    \

Do we need the ' + 0' part?

> +       while (__len--)                                         \
> +               __element = op(__element, __array[__len]);      \
> +       __element; })
> +
> +/**
> + * min_array - return minimum of values present in an array
> + * @array: array
> + * @len: array length
> + *
> + * Note that @len must not be zero (empty array).
> + */
> +#define min_array(array, len) __minmax_array(min, array, len)
> +
> +/**
> + * max_array - return maximum of values present in an array
> + * @array: array
> + * @len: array length
> + *
> + * Note that @len must not be zero (empty array).
> + */
> +#define max_array(array, len) __minmax_array(max, array, len)
> +
>  /**
>   * clamp_t - return a value clamped to a given range using a given type
>   * @type: the type of variable to use
> --
> 2.40.1
>


-- 
With Best Regards,
Andy Shevchenko