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

Paul Cercueil <paul@xxxxxxxxxxxxxxx> · Fri, 09 Apr 2021 10:38:39 +0100

Le ven. 9 avril 2021 à 17:30, Masahiro Yamada <masahiroy@xxxxxxxxxx> a 
écrit :
On Fri, Apr 9, 2021 at 5:15 PM Paul Cercueil <paul@xxxxxxxxxxxxxxx> 
wrote:

 Hi Masahiro,

 Le ven. 9 avril 2021 à 5:58, Masahiro Yamada 
<masahiroy@xxxxxxxxxx> 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@xxxxxxxxxx>
 > ---
 >
 >  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