LinuxLists.cc - [PATCH 2/2] pm: allow drivers to drop #ifdef and __maybe

2021-04-08 21:00:43

Subject: [PATCH 2/2] pm: allow drivers to drop #ifdef and __maybe_unused from pm callbacks

Drivers typically surround suspend and resume callbacks with #ifdef
CONFIG_PM(_SLEEP) or mark them as __maybe_unused in order to avoid
-Wunused-const-variable warnings.

With this commit, drivers will be able to remove #ifdef CONFIG_PM(_SLEEP)
and __maybe_unsed because unused functions are dropped by the compiler
instead of the preprocessor.

Signed-off-by: Masahiro Yamada <[email protected]>
---

include/linux/pm.h | 67 +++++++++++++++++-----------------------------
1 file changed, 24 insertions(+), 43 deletions(-)

diff --git a/include/linux/pm.h b/include/linux/pm.h
index 482313a8ccfc..ca764566692a 100644
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -301,50 +301,37 @@ struct dev_pm_ops {
int (*runtime_idle)(struct device *dev);
};

-#ifdef CONFIG_PM_SLEEP
+#define pm_ptr(_ptr) PTR_IF(IS_ENABLED(CONFIG_PM), _ptr)
+#define pm_sleep_ptr(_ptr) PTR_IF(IS_ENABLED(CONFIG_PM_SLEEP), _ptr)
+
#define SET_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
- .suspend = suspend_fn, \
- .resume = resume_fn, \
- .freeze = suspend_fn, \
- .thaw = resume_fn, \
- .poweroff = suspend_fn, \
- .restore = resume_fn,
-#else
-#define SET_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn)
-#endif
+ .suspend = pm_sleep_ptr(suspend_fn), \
+ .resume = pm_sleep_ptr(resume_fn), \
+ .freeze = pm_sleep_ptr(suspend_fn), \
+ .thaw = pm_sleep_ptr(resume_fn), \
+ .poweroff = pm_sleep_ptr(suspend_fn), \
+ .restore = pm_sleep_ptr(resume_fn),

-#ifdef CONFIG_PM_SLEEP
#define SET_LATE_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
- .suspend_late = suspend_fn, \
- .resume_early = resume_fn, \
- .freeze_late = suspend_fn, \
- .thaw_early = resume_fn, \
- .poweroff_late = suspend_fn, \
- .restore_early = resume_fn,
-#else
-#define SET_LATE_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn)
-#endif
+ .suspend_late = pm_sleep_ptr(suspend_fn), \
+ .resume_early = pm_sleep_ptr(resume_fn), \
+ .freeze_late = pm_sleep_ptr(suspend_fn), \
+ .thaw_early = pm_sleep_ptr(resume_fn), \
+ .poweroff_late = pm_sleep_ptr(suspend_fn), \
+ .restore_early = pm_sleep_ptr(resume_fn),

-#ifdef CONFIG_PM_SLEEP
#define SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
- .suspend_noirq = suspend_fn, \
- .resume_noirq = resume_fn, \
- .freeze_noirq = suspend_fn, \
- .thaw_noirq = resume_fn, \
- .poweroff_noirq = suspend_fn, \
- .restore_noirq = resume_fn,
-#else
-#define SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn)
-#endif
+ .suspend_noirq = pm_sleep_ptr(suspend_fn), \
+ .resume_noirq = pm_sleep_ptr(resume_fn), \
+ .freeze_noirq = pm_sleep_ptr(suspend_fn), \
+ .thaw_noirq = pm_sleep_ptr(resume_fn), \
+ .poweroff_noirq = pm_sleep_ptr(suspend_fn), \
+ .restore_noirq = pm_sleep_ptr(resume_fn),

-#ifdef CONFIG_PM
#define SET_RUNTIME_PM_OPS(suspend_fn, resume_fn, idle_fn) \
- .runtime_suspend = suspend_fn, \
- .runtime_resume = resume_fn, \
- .runtime_idle = idle_fn,
-#else
-#define SET_RUNTIME_PM_OPS(suspend_fn, resume_fn, idle_fn)
-#endif
+ .runtime_suspend = pm_ptr(suspend_fn), \
+ .runtime_resume = pm_ptr(resume_fn), \
+ .runtime_idle = pm_ptr(idle_fn),

/*
* Use this if you want to use the same suspend and resume callbacks for suspend
@@ -374,12 +361,6 @@ const struct dev_pm_ops __maybe_unused name = { \
SET_RUNTIME_PM_OPS(suspend_fn, resume_fn, idle_fn) \
}

-#ifdef CONFIG_PM
-#define pm_ptr(_ptr) (_ptr)
-#else
-#define pm_ptr(_ptr) NULL
-#endif
-
/*
* PM_EVENT_ messages
*
--
2.27.0

2021-04-08 21:31:39

by Arnd Bergmann

[permalink] [raw]

Subject: Re: [PATCH 2/2] pm: allow drivers to drop #ifdef and __maybe_unused from pm callbacks

On Thu, Apr 8, 2021 at 11:00 PM Masahiro Yamada <[email protected]> wrote:
>
> Drivers typically surround suspend and resume callbacks with #ifdef
> CONFIG_PM(_SLEEP) or mark them as __maybe_unused in order to avoid
> -Wunused-const-variable warnings.
>
> With this commit, drivers will be able to remove #ifdef CONFIG_PM(_SLEEP)
> and __maybe_unsed because unused functions are dropped by the compiler
> instead of the preprocessor.
>
> Signed-off-by: Masahiro Yamada <[email protected]>

I tried this before and could not get it to work right.

>
> -#ifdef CONFIG_PM_SLEEP
> +#define pm_ptr(_ptr) PTR_IF(IS_ENABLED(CONFIG_PM), _ptr)
> +#define pm_sleep_ptr(_ptr) PTR_IF(IS_ENABLED(CONFIG_PM_SLEEP), _ptr)
> +
> #define SET_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
> - .suspend = suspend_fn, \
> - .resume = resume_fn, \
> - .freeze = suspend_fn, \
> - .thaw = resume_fn, \
> - .poweroff = suspend_fn, \
> - .restore = resume_fn,
> -#else
> -#define SET_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn)
> -#endif
> + .suspend = pm_sleep_ptr(suspend_fn), \
> + .resume = pm_sleep_ptr(resume_fn), \
> + .freeze = pm_sleep_ptr(suspend_fn), \
> + .thaw = pm_sleep_ptr(resume_fn), \
> + .poweroff = pm_sleep_ptr(suspend_fn), \
> + .restore = pm_sleep_ptr(resume_fn),

The problem that I think you inevitably hit is that you run into a missing
declaration for any driver that still uses an #ifdef around a static
function.

The only way I can see us doing this is to create a new set of
macros that behave like the version you propose here but leave
the old macros in place until the last such #ifdef has been removed.

Arnd

2021-04-08 23:53:00

by kernel test robot

[permalink] [raw]

Subject: Re: [PATCH 2/2] pm: allow drivers to drop #ifdef and __maybe_unused from pm callbacks

Hi Masahiro,

I love your patch! Yet something to improve:

[auto build test ERROR on pinctrl/devel]
[also build test ERROR on pm/linux-next soc/for-next linus/master v5.12-rc6]
[cannot apply to next-20210408]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url: https://github.com/0day-ci/linux/commits/Masahiro-Yamada/linux-kconfig-h-move-IF_ENABLED-out-of-linux-kconfig-h/20210409-050128
base: https://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl.git devel
config: nds32-randconfig-r004-20210408 (attached as .config)
compiler: nds32le-linux-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/0day-ci/linux/commit/01dfb9e1a54c14b3f491c3a5e93f1e8756042567
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Masahiro-Yamada/linux-kconfig-h-move-IF_ENABLED-out-of-linux-kconfig-h/20210409-050128
git checkout 01dfb9e1a54c14b3f491c3a5e93f1e8756042567
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=nds32

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <[email protected]>

All errors (new ones prefixed by >>):

In file included from drivers/input/rmi4/rmi_spi.c:7:
drivers/input/rmi4/rmi_spi.c:507:26: error: 'rmi_spi_suspend' undeclared here (not in a function); did you mean 'rmi_driver_suspend'?
507 | SET_SYSTEM_SLEEP_PM_OPS(rmi_spi_suspend, rmi_spi_resume)
| ^~~~~~~~~~~~~~~
include/linux/kernel.h:41:38: note: in definition of macro 'PTR_IF'
41 | #define PTR_IF(cond, ptr) ((cond) ? (ptr) : NULL)
| ^~~
include/linux/pm.h:308:14: note: in expansion of macro 'pm_sleep_ptr'
308 | .suspend = pm_sleep_ptr(suspend_fn), \
| ^~~~~~~~~~~~
drivers/input/rmi4/rmi_spi.c:507:2: note: in expansion of macro 'SET_SYSTEM_SLEEP_PM_OPS'
507 | SET_SYSTEM_SLEEP_PM_OPS(rmi_spi_suspend, rmi_spi_resume)
| ^~~~~~~~~~~~~~~~~~~~~~~
drivers/input/rmi4/rmi_spi.c:507:43: error: 'rmi_spi_resume' undeclared here (not in a function); did you mean 'rmi_spi_pm'?
507 | SET_SYSTEM_SLEEP_PM_OPS(rmi_spi_suspend, rmi_spi_resume)
| ^~~~~~~~~~~~~~
include/linux/kernel.h:41:38: note: in definition of macro 'PTR_IF'
41 | #define PTR_IF(cond, ptr) ((cond) ? (ptr) : NULL)
| ^~~
include/linux/pm.h:309:14: note: in expansion of macro 'pm_sleep_ptr'
309 | .resume = pm_sleep_ptr(resume_fn), \
| ^~~~~~~~~~~~
drivers/input/rmi4/rmi_spi.c:507:2: note: in expansion of macro 'SET_SYSTEM_SLEEP_PM_OPS'
507 | SET_SYSTEM_SLEEP_PM_OPS(rmi_spi_suspend, rmi_spi_resume)
| ^~~~~~~~~~~~~~~~~~~~~~~
>> drivers/input/rmi4/rmi_spi.c:508:21: error: 'rmi_spi_runtime_suspend' undeclared here (not in a function)
508 | SET_RUNTIME_PM_OPS(rmi_spi_runtime_suspend, rmi_spi_runtime_resume,
| ^~~~~~~~~~~~~~~~~~~~~~~
include/linux/kernel.h:41:38: note: in definition of macro 'PTR_IF'
41 | #define PTR_IF(cond, ptr) ((cond) ? (ptr) : NULL)
| ^~~
include/linux/pm.h:332:21: note: in expansion of macro 'pm_ptr'
332 | .runtime_suspend = pm_ptr(suspend_fn), \
| ^~~~~~
drivers/input/rmi4/rmi_spi.c:508:2: note: in expansion of macro 'SET_RUNTIME_PM_OPS'
508 | SET_RUNTIME_PM_OPS(rmi_spi_runtime_suspend, rmi_spi_runtime_resume,
| ^~~~~~~~~~~~~~~~~~
>> drivers/input/rmi4/rmi_spi.c:508:46: error: 'rmi_spi_runtime_resume' undeclared here (not in a function)
508 | SET_RUNTIME_PM_OPS(rmi_spi_runtime_suspend, rmi_spi_runtime_resume,
| ^~~~~~~~~~~~~~~~~~~~~~
include/linux/kernel.h:41:38: note: in definition of macro 'PTR_IF'
41 | #define PTR_IF(cond, ptr) ((cond) ? (ptr) : NULL)
| ^~~
include/linux/pm.h:333:21: note: in expansion of macro 'pm_ptr'
333 | .runtime_resume = pm_ptr(resume_fn), \
| ^~~~~~
drivers/input/rmi4/rmi_spi.c:508:2: note: in expansion of macro 'SET_RUNTIME_PM_OPS'
508 | SET_RUNTIME_PM_OPS(rmi_spi_runtime_suspend, rmi_spi_runtime_resume,
| ^~~~~~~~~~~~~~~~~~
--
In file included from include/linux/list.h:9,
from include/linux/rculist.h:10,
from include/linux/pid.h:5,
from include/linux/sched.h:14,
from include/linux/ratelimit.h:6,
from include/linux/dev_printk.h:16,
from include/linux/device.h:15,
from include/linux/backlight.h:12,
from drivers/video/backlight/ams369fg06.c:11:
>> drivers/video/backlight/ams369fg06.c:541:45: error: 'ams369fg06_suspend' undeclared here (not in a function); did you mean 'ams369fg06_probe'?
541 | static SIMPLE_DEV_PM_OPS(ams369fg06_pm_ops, ams369fg06_suspend,
| ^~~~~~~~~~~~~~~~~~
include/linux/kernel.h:41:38: note: in definition of macro 'PTR_IF'
41 | #define PTR_IF(cond, ptr) ((cond) ? (ptr) : NULL)
| ^~~
include/linux/pm.h:308:14: note: in expansion of macro 'pm_sleep_ptr'
308 | .suspend = pm_sleep_ptr(suspend_fn), \
| ^~~~~~~~~~~~
include/linux/pm.h:342:2: note: in expansion of macro 'SET_SYSTEM_SLEEP_PM_OPS'
342 | SET_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
| ^~~~~~~~~~~~~~~~~~~~~~~
drivers/video/backlight/ams369fg06.c:541:8: note: in expansion of macro 'SIMPLE_DEV_PM_OPS'
541 | static SIMPLE_DEV_PM_OPS(ams369fg06_pm_ops, ams369fg06_suspend,
| ^~~~~~~~~~~~~~~~~
>> drivers/video/backlight/ams369fg06.c:542:4: error: 'ams369fg06_resume' undeclared here (not in a function); did you mean 'ams369fg06_remove'?
542 | ams369fg06_resume);
| ^~~~~~~~~~~~~~~~~
include/linux/kernel.h:41:38: note: in definition of macro 'PTR_IF'
41 | #define PTR_IF(cond, ptr) ((cond) ? (ptr) : NULL)
| ^~~
include/linux/pm.h:309:14: note: in expansion of macro 'pm_sleep_ptr'
309 | .resume = pm_sleep_ptr(resume_fn), \
| ^~~~~~~~~~~~
include/linux/pm.h:342:2: note: in expansion of macro 'SET_SYSTEM_SLEEP_PM_OPS'
342 | SET_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
| ^~~~~~~~~~~~~~~~~~~~~~~
drivers/video/backlight/ams369fg06.c:541:8: note: in expansion of macro 'SIMPLE_DEV_PM_OPS'
541 | static SIMPLE_DEV_PM_OPS(ams369fg06_pm_ops, ams369fg06_suspend,
| ^~~~~~~~~~~~~~~~~
--
In file included from include/linux/delay.h:22,
from drivers/video/backlight/vgg2432a4.c:11:
>> drivers/video/backlight/vgg2432a4.c:246:44: error: 'vgg2432a4_suspend' undeclared here (not in a function); did you mean 'vgg2432a4_client'?
246 | static SIMPLE_DEV_PM_OPS(vgg2432a4_pm_ops, vgg2432a4_suspend, vgg2432a4_resume);
| ^~~~~~~~~~~~~~~~~
include/linux/kernel.h:41:38: note: in definition of macro 'PTR_IF'
41 | #define PTR_IF(cond, ptr) ((cond) ? (ptr) : NULL)
| ^~~
include/linux/pm.h:308:14: note: in expansion of macro 'pm_sleep_ptr'
308 | .suspend = pm_sleep_ptr(suspend_fn), \
| ^~~~~~~~~~~~
include/linux/pm.h:342:2: note: in expansion of macro 'SET_SYSTEM_SLEEP_PM_OPS'
342 | SET_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
| ^~~~~~~~~~~~~~~~~~~~~~~
drivers/video/backlight/vgg2432a4.c:246:8: note: in expansion of macro 'SIMPLE_DEV_PM_OPS'
246 | static SIMPLE_DEV_PM_OPS(vgg2432a4_pm_ops, vgg2432a4_suspend, vgg2432a4_resume);
| ^~~~~~~~~~~~~~~~~
>> drivers/video/backlight/vgg2432a4.c:246:63: error: 'vgg2432a4_resume' undeclared here (not in a function); did you mean 'vgg2432a4_remove'?
246 | static SIMPLE_DEV_PM_OPS(vgg2432a4_pm_ops, vgg2432a4_suspend, vgg2432a4_resume);
| ^~~~~~~~~~~~~~~~
include/linux/kernel.h:41:38: note: in definition of macro 'PTR_IF'
41 | #define PTR_IF(cond, ptr) ((cond) ? (ptr) : NULL)
| ^~~
include/linux/pm.h:309:14: note: in expansion of macro 'pm_sleep_ptr'
309 | .resume = pm_sleep_ptr(resume_fn), \
| ^~~~~~~~~~~~
include/linux/pm.h:342:2: note: in expansion of macro 'SET_SYSTEM_SLEEP_PM_OPS'
342 | SET_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
| ^~~~~~~~~~~~~~~~~~~~~~~
drivers/video/backlight/vgg2432a4.c:246:8: note: in expansion of macro 'SIMPLE_DEV_PM_OPS'
246 | static SIMPLE_DEV_PM_OPS(vgg2432a4_pm_ops, vgg2432a4_suspend, vgg2432a4_resume);
| ^~~~~~~~~~~~~~~~~

vim +/rmi_spi_runtime_suspend +508 drivers/input/rmi4/rmi_spi.c

8d99758dee31ff Andrew Duggan 2016-03-10 505
8d99758dee31ff Andrew Duggan 2016-03-10 506 static const struct dev_pm_ops rmi_spi_pm = {
8d99758dee31ff Andrew Duggan 2016-03-10 @507 SET_SYSTEM_SLEEP_PM_OPS(rmi_spi_suspend, rmi_spi_resume)
8d99758dee31ff Andrew Duggan 2016-03-10 @508 SET_RUNTIME_PM_OPS(rmi_spi_runtime_suspend, rmi_spi_runtime_resume,
8d99758dee31ff Andrew Duggan 2016-03-10 509 NULL)
8d99758dee31ff Andrew Duggan 2016-03-10 510 };
8d99758dee31ff Andrew Duggan 2016-03-10 511

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/[email protected]

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2021-04-08 23:57:56

by kernel test robot

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Subject: Re: [PATCH 2/2] pm: allow drivers to drop #ifdef and __maybe_unused from pm callbacks

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2021-04-09 03:19:25

by Masahiro Yamada

[permalink] [raw]

Subject: Re: [PATCH 2/2] pm: allow drivers to drop #ifdef and __maybe_unused from pm callbacks

On Fri, Apr 9, 2021 at 6:30 AM Arnd Bergmann <[email protected]> wrote:
>
> On Thu, Apr 8, 2021 at 11:00 PM Masahiro Yamada <[email protected]> wrote:
> >
> > Drivers typically surround suspend and resume callbacks with #ifdef
> > CONFIG_PM(_SLEEP) or mark them as __maybe_unused in order to avoid
> > -Wunused-const-variable warnings.
> >
> > With this commit, drivers will be able to remove #ifdef CONFIG_PM(_SLEEP)
> > and __maybe_unsed because unused functions are dropped by the compiler
> > instead of the preprocessor.
> >
> > Signed-off-by: Masahiro Yamada <[email protected]>
>
> I tried this before and could not get it to work right.
>
> >
> > -#ifdef CONFIG_PM_SLEEP
> > +#define pm_ptr(_ptr) PTR_IF(IS_ENABLED(CONFIG_PM), _ptr)
> > +#define pm_sleep_ptr(_ptr) PTR_IF(IS_ENABLED(CONFIG_PM_SLEEP), _ptr)
> > +
> > #define SET_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
> > - .suspend = suspend_fn, \
> > - .resume = resume_fn, \
> > - .freeze = suspend_fn, \
> > - .thaw = resume_fn, \
> > - .poweroff = suspend_fn, \
> > - .restore = resume_fn,
> > -#else
> > -#define SET_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn)
> > -#endif
> > + .suspend = pm_sleep_ptr(suspend_fn), \
> > + .resume = pm_sleep_ptr(resume_fn), \
> > + .freeze = pm_sleep_ptr(suspend_fn), \
> > + .thaw = pm_sleep_ptr(resume_fn), \
> > + .poweroff = pm_sleep_ptr(suspend_fn), \
> > + .restore = pm_sleep_ptr(resume_fn),
>
> The problem that I think you inevitably hit is that you run into a missing
> declaration for any driver that still uses an #ifdef around a static
> function.
>
> The only way I can see us doing this is to create a new set of
> macros that behave like the version you propose here but leave
> the old macros in place until the last such #ifdef has been removed.
>
> Arnd

Agh, you are right.
We cannot change all the callsites atomically due to the huge amount of users.

--
Best Regards
Masahiro Yamada