linux-kernel - Re: [PATCH 1/2] linux/kconfig.h: replace IF_ENABLED() with PTR

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Date:   Sat, 10 Apr 2021 12:52:32 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Arnd Bergmann <arnd@...db.de>,
        Paul Cercueil <paul@...pouillou.net>,
        Linus Walleij <linus.walleij@...aro.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-mips@...r.kernel.org
Subject: Re: [PATCH 1/2] linux/kconfig.h: replace IF_ENABLED() with PTR_IF()
 in <linux/kernel.h>

On Fri, Apr 9, 2021 at 6:24 PM Andy Shevchenko
<andy.shevchenko@...il.com> wrote:
>
> On Fri, Apr 9, 2021 at 12:00 AM Masahiro Yamada <masahiroy@...nel.org> wrote:
> >
> > <linux/kconfig.h> is included from all the kernel-space source files,
> > including C, assembly, linker scripts. It is intended to contain minimal
>
> a minimal
>
> > set of macros to evaluate CONFIG options.
> >
> > IF_ENABLED() is an intruder here because (x ? y : z) is C code, which
> > should not be included from assembly files or linker scripts.
> >
> > Also, <linux/kconfig.h> is no longer self-contained because NULL is
> > defined in <linux/stddef.h>.
> >
> > Move IF_ENABLED() out to <linux/kernel.h> as PTR_IF().
> >
> > PTR_IF(IS_ENABLED(CONFIG_FOO), ...) is slightly longer than
> > IF_ENABLED(CONFIG_FOO, ...), but it is not a big deal because
> > sub-systems often define dedicated macros such as of_match_ptr(),
> > pm_ptr() etc. for common use-cases.
>
> >  include/linux/kernel.h            |  2 ++
>
> Why kernel.h? Shouldn't it belong to a particular domain with a
> respective header file?
>
> Really what we have in the kernel.h right now is a complete train
> wreck of something.
> We have to define what exactly is kernel.h for?


<linux/kernel.h> contains random utility macros.

I did not find a good header to put it in otherwise.


>
> Arnd? Others? Shall we start a wider discussion on the topic?
>
> --
> With Best Regards,
> Andy Shevchenko


--
Best Regards
Masahiro Yamada