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

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Date:   Fri, 7 Jan 2022 17:26:07 +0100
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Paul Cercueil <paul@...pouillou.net>
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

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?

>
> 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?

>  #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