linux-kernel - Re: [PATCH] kstrtox: drop kstrtol()/kstrtoul() when possible

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Message-ID: <BANLkTim=2isrqtBCLoZN9kkeqCo1jcKkUw@mail.gmail.com>
Date:	Fri, 20 May 2011 09:54:44 +0200
From:	Geert Uytterhoeven <geert@...ux-m68k.org>
To:	Alexey Dobriyan <adobriyan@...il.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, arnd@...db.de, mmarek@...e.cz,
	linux-kbuild@...r.kernel.org
Subject: Re: [PATCH] kstrtox: drop kstrtol()/kstrtoul() when possible

On Fri, May 20, 2011 at 09:21, Alexey Dobriyan <adobriyan@...il.com> wrote:
> On Thu, May 19, 2011 at 11:54:49PM -0700, Andrew Morton wrote:
>> On Fri, 20 May 2011 09:48:27 +0300 Alexey Dobriyan <adobriyan@...il.com> wrote:
>>
>> > On Fri, May 20, 2011 at 08:20:42AM +0200, Geert Uytterhoeven wrote:
>> > > On Fri, May 20, 2011 at 08:15, Alexey Dobriyan <adobriyan@...il.com> wrote:
>> > > > If "long" and "long long" types are identical at runtime,
>> > > > kstrtol() can be aliased to kstrtoll().
>> > > >
>> > > > Unfortunately, one can't write
>> > > >
>> > > > __ __ __ __#if sizeof(long) == sizeof(long long) ...
>> > >
>> > > One can write #ifdef CONFIG_64BIT instead.
>> >
>> > And alignment will match, on any arch, now and in future?
>> > I don't think so.
>>
>> Don't worry about it.
>>
>> z:/usr/src/linux-2.6.39> grep -r "#[    ]*if.*CONFIG_64BIT" . | wc -l
>> 547
>>
>> So much other stuff will break that kstrtofoo is a drop in the bucket.
>
> Meh.
> The point was that patch is obviously correct and will work in future.
> CONFIG_64BIT means many things and you guys ask me to overload CONFIG_64BIT
> one more time.

In Linux, CONFIG_64BIT means that sizeof(long) == 8. Alignment of 8 byte longs
and 8 byte long long should be identical, as w.r.t. the CPU they're
the same type.

> On X32, CONFIG_64BIT trick already doesn't technically work.

Why? On X32, CONFIG_64bit is not set, and sizeof(long) == 4 and
sizeof(long long) == 8.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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