linux-kernel - Re: [PATCH v2 1/6] PM: core: Remove DEFINE_UNIVERSAL_DEV_PM

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Message-Id: <U5MC5R.JX72XLGEKI8P@crapouillou.net>
Date:   Fri, 07 Jan 2022 16:37:06 +0000
From:   Paul Cercueil <paul@...pouillou.net>
To:     Ulf Hansson <ulf.hansson@...aro.org>
Cc:     "Rafael J . Wysocki" <rafael@...nel.org>,
        Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Linus Walleij <linus.walleij@...aro.org>,
        Arnd Bergmann <arnd@...db.de>, Len Brown <len.brown@...el.com>,
        Pavel Machek <pavel@....cz>, list@...ndingux.net,
        linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mips@...r.kernel.org, linux-mmc@...r.kernel.org,
        linux-pm@...r.kernel.org,
        Jonathan Cameron <jonathan.cameron@...wei.com>
Subject: Re: [PATCH v2 1/6] PM: core: Remove DEFINE_UNIVERSAL_DEV_PM_OPS()
 macro

Hi Ulf,

Le ven., janv. 7 2022 at 17:26:07 +0100, Ulf Hansson 
<ulf.hansson@...aro.org> a écrit :
> On Wed, 5 Jan 2022 at 19:29, Paul Cercueil <paul@...pouillou.net> 
> wrote:
>> 
>>  The deprecated UNIVERSAL_DEV_PM_OPS() macro uses the provided 
>> callbacks
>>  for both runtime PM and system sleep, which is very likely to be a
>>  mistake, as a system sleep can be triggered while a given device is
>>  already PM-suspended, which would cause the suspend callback to be
>>  called twice.
>> 
>>  The amount of users of UNIVERSAL_DEV_PM_OPS() is also tiny (16
>>  occurences) compared to the number of places where
>>  SET_SYSTEM_SLEEP_PM_OPS() is used with pm_runtime_force_suspend() 
>> and
>>  pm_runtime_force_resume(), which makes me think that none of these 
>> cases
>>  are actually valid.
>> 
>>  As this macro is currently unused, remove it before someone starts 
>> to
>>  use it in yet another invalid case.
> 
> I assume you refer to DEFINE_UNIVERSAL_DEV_PM_OPS here. Can you
> perhaps make that more clear?

I can.

>> 
>>  Signed-off-by: Paul Cercueil <paul@...pouillou.net>
>>  Acked-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
>>  ---
>> 
>>  Notes:
>>      v2: No change
>> 
>>   include/linux/pm.h | 19 ++++++-------------
>>   1 file changed, 6 insertions(+), 13 deletions(-)
>> 
>>  diff --git a/include/linux/pm.h b/include/linux/pm.h
>>  index e1e9402180b9..31bbaafb06d2 100644
>>  --- a/include/linux/pm.h
>>  +++ b/include/linux/pm.h
>>  @@ -366,6 +366,12 @@ static const struct dev_pm_ops name = { \
>>          SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
>>   }
>> 
>>  +/* Deprecated. Use DEFINE_SIMPLE_DEV_PM_OPS() instead. */
>>  +#define SIMPLE_DEV_PM_OPS(name, suspend_fn, resume_fn) \
>>  +const struct dev_pm_ops __maybe_unused name = { \
>>  +       SET_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
>>  +}
>>  +
>>   /*
>>    * Use this for defining a set of PM operations to be used in all 
>> situations
>>    * (system suspend, hibernation or runtime PM).
>>  @@ -379,19 +385,6 @@ static const struct dev_pm_ops name = { \
>>    * .resume_early(), to the same routines as .runtime_suspend() and
>>    * .runtime_resume(), respectively (and analogously for 
>> hibernation).
>>    */
>>  -#define DEFINE_UNIVERSAL_DEV_PM_OPS(name, suspend_fn, resume_fn, 
>> idle_fn) \
>>  -static const struct dev_pm_ops name = { \
>>  -       SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
>>  -       RUNTIME_PM_OPS(suspend_fn, resume_fn, idle_fn) \
>>  -}
>>  -
>>  -/* Deprecated. Use DEFINE_SIMPLE_DEV_PM_OPS() instead. */
>>  -#define SIMPLE_DEV_PM_OPS(name, suspend_fn, resume_fn) \
>>  -const struct dev_pm_ops __maybe_unused name = { \
>>  -       SET_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
>>  -}
>>  -
>>  -/* Deprecated. Use DEFINE_UNIVERSAL_DEV_PM_OPS() instead. */
> 
> Shouldn't this macro be deprecated any more?

I can only deprecate it if there is an alternative for it. The 
alternative is DEFINE_RUNTIME_DEV_PM_OPS() which is added in patch 4/6.

Cheers,
-Paul

>>   #define UNIVERSAL_DEV_PM_OPS(name, suspend_fn, resume_fn, idle_fn) 
>> \
>>   const struct dev_pm_ops __maybe_unused name = { \
>>          SET_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
>>  --
>>  2.34.1
>> 
> 
> Kind regards
> Uffe