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

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Message-ID: <05ab102b936ce922c4fae67bf5dd3e323aff0b93.camel@perches.com>
Date:   Mon, 08 Jun 2020 15:34:52 -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] overflow.h: Add flex_array_size() helper

On Mon, 2020-06-08 at 17:17 -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.
> 
> Example of usage:
> foo
> struct something {
> 	size_t count;
> 	struct foo items[];
> };
> 
> struct something *instance;
[]
> diff --git a/include/linux/overflow.h b/include/linux/overflow.h
[]
> +/**
> + * flex_array_size() - Calculate size of a flexible array member within
> + * an enclosing structure.

These comment descriptions do not match

> + * Calculates size of memory needed for flexible array @member of @count
> + * elements within structure @p.

The first comment shows the size of an array member.
The second shows the size of an array member * count

Also the struct_size and flex_array_size definitions
are using two different forms:

		sizeof(*(p)->member) + __must_be_array((p)->member),\
and
		sizeof((p)->member[0]) + __must_be_array((p)->member))

Consistency would be nice.