linux-kernel - Re: [PATCH 2/4] linux/array_size.h: Add ARRAY_SIZE_OF

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Message-ID: <57a30a95-b63c-7ad4-070f-db70262b6b7c@kernel.org>
Date:   Fri, 18 Aug 2023 00:03:09 +0200
From:   Alejandro Colomar <alx@...nel.org>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Lucas Segarra Fernandez <lucas.segarra.fernandez@...el.com>,
        herbert@...dor.apana.org.au, linux-kernel@...r.kernel.org,
        linux-crypto@...r.kernel.org, qat-linux@...el.com,
        andriy.shevchenko@...el.com,
        Giovanni Cabiddu <giovanni.cabiddu@...el.com>,
        Kees Cook <keescook@...omium.org>,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>
Subject: Re: [PATCH 2/4] linux/array_size.h: Add ARRAY_SIZE_OF_FIELD()

Hello Andy,

On 2023-08-17 23:30, Andy Shevchenko wrote:
> On Thu, Aug 17, 2023 at 11:34 PM Alejandro Colomar <alx@...nel.org> wrote:
>> On 2023-08-17 16:33, Lucas Segarra Fernandez wrote:
> 
> ...
> 
>> Some comment about the name:
>>
>> ARRAY_SIZE() is rather ambiguous, as there's array_size()[1], which means the
>> number of bytes needed to represent the array.  I suggest a name based on
>>
>> -  _Lengthof()  It has been proposed to ISO C to get the number of elements
>>                 of an array:
>>                 <https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2529.pdf>.
>>
>> -  sizeof_field()  The kernel macro for the size of a struct member
>>
>> So, how about lengthof_field()?
> 
> TBH I do not understand the motivation of making this kind of
> confusion and inconsistency.


> Are you suggesting renaming ARRAY_SIZE()
> to begin with?

No.  ARRAY_SIZE is a very old and known API.  It is array_size() that is
to be blamed, due to having a confusing name.

What I suggest is not reusing the root of the name of ARRAY_SIZE(), which
since the addition of array_size() may be less unambiguous (IMHO).

So, instead of ARRAY_SIZE_*(), which is derived from ARRAY_SIZE(), maybe
it would be more unambiguous to use the _Lengthof() name as a root, since
nobody has messed with it so far.

My suggestion is to keep ARRAY_SIZE() with its old name, but use
lengthof_field() for this struct variant of it.  It's also a shorter name,
which will make for shorter lines.

b19d57d0f3cc ("overflow.h: Add flex_array_size() helper")
	- (Mon Jun 8 20:22:33 2020 -0500)
610b15c50e86 ("overflow.h: Add allocation size calculation helpers")
	- (Mon May 7 16:47:02 2018 -0700)

Nevertheless, it was just a minor suggestion, and if array_size() was
seen as a good enough name, it wouldn't be as confusing as it seems to
me.  If you find them to be fine, go ahead.

Cheers,
Alex

> If so, it's definitely out of the scope of this series.
> 

-- 
<http://www.alejandro-colomar.es/>
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