Re: [PATCH 1/2] linux/kconfig.h: replace IF_ENABLED() with PTR_IF() in <linux/kernel.h>

[Paul Cercueil <paul@crapouillou.net>]

Le ven. 9 avril 2021 à 17:30, Masahiro Yamada <masahiroy@kernel.org> a 
écrit :
> On Fri, Apr 9, 2021 at 5:15 PM Paul Cercueil <paul@crapouillou.net> 
> wrote:
>> 
>>  Hi Masahiro,
>> 
>>  Le ven. 9 avril 2021 à 5:58, Masahiro Yamada 
>> <masahiroy@kernel.org> a
>>  écrit :
>>  > <linux/kconfig.h> is included from all the kernel-space source 
>> files,
>>  > including C, assembly, linker scripts. It is intended to contain
>>  > 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.
>> 
>>  What's the idea behind changing IF_ENABLED() to PTR_IF()? You didn't
>>  explain that. What's wrong with IF_ENABLED()?
> 
> 
> PTR_IF() is a more generalized variant, which I believe is
> a better fit in <linux/kernel.h>
> The first parameter does not need to be a CONFIG option,
> but any expression.

Fair enough, but we could still have IF_ENABLED as a specialized 
variant of PTR_IF:

#define IF_ENABLED(cfg, ptr) PTR_IF(IS_ENABLED(cfg), (ptr))

-Paul

> 
> 
>>  Cheers,
>>  -Paul
>> 
>>  > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
>>  > ---
>>  >
>>  >  drivers/pinctrl/pinctrl-ingenic.c | 20 ++++++++++----------
>>  >  include/linux/kconfig.h           |  6 ------
>>  >  include/linux/kernel.h            |  2 ++
>>  >  3 files changed, 12 insertions(+), 16 deletions(-)
>>  >
>>  > diff --git a/drivers/pinctrl/pinctrl-ingenic.c
>>  > b/drivers/pinctrl/pinctrl-ingenic.c
>>  > index f2746125b077..b21e2ae4528d 100644
>>  > --- a/drivers/pinctrl/pinctrl-ingenic.c
>>  > +++ b/drivers/pinctrl/pinctrl-ingenic.c
>>  > @@ -2496,43 +2496,43 @@ static int __init
>>  > ingenic_pinctrl_probe(struct platform_device *pdev)
>>  >  static const struct of_device_id ingenic_pinctrl_of_match[] = {
>>  >       {
>>  >               .compatible = "ingenic,jz4740-pinctrl",
>>  > -             .data = IF_ENABLED(CONFIG_MACH_JZ4740, 
>> &jz4740_chip_info)
>>  > +             .data = PTR_IF(IS_ENABLED(CONFIG_MACH_JZ4740), 
>> &jz4740_chip_info)
>>  >       },
>>  >       {
>>  >               .compatible = "ingenic,jz4725b-pinctrl",
>>  > -             .data = IF_ENABLED(CONFIG_MACH_JZ4725B, 
>> &jz4725b_chip_info)
>>  > +             .data = PTR_IF(IS_ENABLED(CONFIG_MACH_JZ4725B), 
>> &jz4725b_chip_info)
>>  >       },
>>  >       {
>>  >               .compatible = "ingenic,jz4760-pinctrl",
>>  > -             .data = IF_ENABLED(CONFIG_MACH_JZ4760, 
>> &jz4760_chip_info)
>>  > +             .data = PTR_IF(IS_ENABLED(CONFIG_MACH_JZ4760), 
>> &jz4760_chip_info)
>>  >       },
>>  >       {
>>  >               .compatible = "ingenic,jz4760b-pinctrl",
>>  > -             .data = IF_ENABLED(CONFIG_MACH_JZ4760, 
>> &jz4760_chip_info)
>>  > +             .data = PTR_IF(IS_ENABLED(CONFIG_MACH_JZ4760), 
>> &jz4760_chip_info)
>>  >       },
>>  >       {
>>  >               .compatible = "ingenic,jz4770-pinctrl",
>>  > -             .data = IF_ENABLED(CONFIG_MACH_JZ4770, 
>> &jz4770_chip_info)
>>  > +             .data = PTR_IF(IS_ENABLED(CONFIG_MACH_JZ4770), 
>> &jz4770_chip_info)
>>  >       },
>>  >       {
>>  >               .compatible = "ingenic,jz4780-pinctrl",
>>  > -             .data = IF_ENABLED(CONFIG_MACH_JZ4780, 
>> &jz4780_chip_info)
>>  > +             .data = PTR_IF(IS_ENABLED(CONFIG_MACH_JZ4780), 
>> &jz4780_chip_info)
>>  >       },
>>  >       {
>>  >               .compatible = "ingenic,x1000-pinctrl",
>>  > -             .data = IF_ENABLED(CONFIG_MACH_X1000, 
>> &x1000_chip_info)
>>  > +             .data = PTR_IF(IS_ENABLED(CONFIG_MACH_X1000), 
>> &x1000_chip_info)
>>  >       },
>>  >       {
>>  >               .compatible = "ingenic,x1000e-pinctrl",
>>  > -             .data = IF_ENABLED(CONFIG_MACH_X1000, 
>> &x1000_chip_info)
>>  > +             .data = PTR_IF(IS_ENABLED(CONFIG_MACH_X1000), 
>> &x1000_chip_info)
>>  >       },
>>  >       {
>>  >               .compatible = "ingenic,x1500-pinctrl",
>>  > -             .data = IF_ENABLED(CONFIG_MACH_X1500, 
>> &x1500_chip_info)
>>  > +             .data = PTR_IF(IS_ENABLED(CONFIG_MACH_X1500), 
>> &x1500_chip_info)
>>  >       },
>>  >       {
>>  >               .compatible = "ingenic,x1830-pinctrl",
>>  > -             .data = IF_ENABLED(CONFIG_MACH_X1830, 
>> &x1830_chip_info)
>>  > +             .data = PTR_IF(IS_ENABLED(CONFIG_MACH_X1830), 
>> &x1830_chip_info)
>>  >       },
>>  >       { /* sentinel */ },
>>  >  };
>>  > diff --git a/include/linux/kconfig.h b/include/linux/kconfig.h
>>  > index 24a59cb06963..cc8fa109cfa3 100644
>>  > --- a/include/linux/kconfig.h
>>  > +++ b/include/linux/kconfig.h
>>  > @@ -70,10 +70,4 @@
>>  >   */
>>  >  #define IS_ENABLED(option) __or(IS_BUILTIN(option),
>>  > IS_MODULE(option))
>>  >
>>  > -/*
>>  > - * IF_ENABLED(CONFIG_FOO, ptr) evaluates to (ptr) if CONFIG_FOO 
>> is
>>  > set to 'y'
>>  > - * or 'm', NULL otherwise.
>>  > - */
>>  > -#define IF_ENABLED(option, ptr) (IS_ENABLED(option) ? (ptr) : 
>> NULL)
>>  > -
>>  >  #endif /* __LINUX_KCONFIG_H */
>>  > diff --git a/include/linux/kernel.h b/include/linux/kernel.h
>>  > index 5b7ed6dc99ac..8685ca4cf287 100644
>>  > --- a/include/linux/kernel.h
>>  > +++ b/include/linux/kernel.h
>>  > @@ -38,6 +38,8 @@
>>  >  #define PTR_ALIGN_DOWN(p, a) ((typeof(p))ALIGN_DOWN((unsigned
>>  > long)(p), (a)))
>>  >  #define IS_ALIGNED(x, a)             (((x) & ((typeof(x))(a) - 
>> 1)) == 0)
>>  >
>>  > +#define PTR_IF(cond, ptr)    ((cond) ? (ptr) : NULL)
>>  > +
>>  >  /* generic data direction definitions */
>>  >  #define READ                 0
>>  >  #define WRITE                        1
>>  > --
>>  > 2.27.0
>>  >
>> 
>> 
> 
> 
> --
> Best Regards
> Masahiro Yamada