linux-kernel - Re: [PATCH v2] overflow.h: Add flex_array

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Date:   Mon, 08 Jun 2020 23:47:03 -0700
From:   Joe Perches <joe@...ches.com>
To:     "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        Kees Cook <keescook@...omium.org>
Cc:     linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Subject: Re: [PATCH v2] overflow.h: Add flex_array_size() helper

On Mon, 2020-06-08 at 20:22 -0500, Gustavo A. R. Silva wrote:
> Add flex_array_size() helper for the calculation of the size, in bytes,
> of a flexible array member contained within an enclosing structure.
[]
> diff --git a/include/linux/overflow.h b/include/linux/overflow.h
[]
> +/**
> + * flex_array_size() - Calculate size, in bytes, of a flexible array member
> + * within an enclosing structure. Read on for more details.

IMO: "Read on for more details" isn't useful here.
Perhaps better would be something like:

 * flex_array_size() - size of a flexible array (sizeof(typeof(member)) * count)

> + *
> + * @p: Pointer to the structure.
> + * @member: Name of the flexible array member.
> + * @count: Number of elements in the array.
> + *
> + * Calculates size, in bytes, of a flexible array @member of @count elements

IMO: "in bytes, " is redundant.  size is always bytes.

> + * within structure @p.
> + *
> + * Return: number of bytes needed or SIZE_MAX on overflow.
> + */
> +#define flex_array_size(p, member, count)					\
> +	array_size(count,							\
> +		    sizeof(*(p)->member) + __must_be_array((p)->member))
> +
>  #endif /* __LINUX_OVERFLOW_H */