Re: [PATCH v3] PM: Fix symbol export for _SIMPLE_ variants of _PM_OPS()

[Paul Cercueil <paul@crapouillou.net>]

Hi,

Le mercredi 20 septembre 2023 à 14:11 +0530, Raag Jadav a écrit :
> Currently EXPORT_*_SIMPLE_DEV_PM_OPS() use EXPORT_*_DEV_PM_OPS() set
> of macros to export dev_pm_ops symbol, which export the symbol in
> case
> CONFIG_PM=y but don't take CONFIG_PM_SLEEP into consideration.
> 
> Since _SIMPLE_ variants of _PM_OPS() do not include runtime PM
> handles
> and are only used in case CONFIG_PM_SLEEP=y, we should not be
> exporting
> their dev_pm_ops symbol in case CONFIG_PM_SLEEP=n.
> 
> This can be fixed by having two distinct set of export macros for
> both
> _RUNTIME_ and _SIMPLE_ variants of _PM_OPS(), such that the export of
> dev_pm_ops symbol used in each variant depends on CONFIG_PM and
> CONFIG_PM_SLEEP respectively.
> 
> Introduce _DEV_SLEEP_PM_OPS() set of export macros for _SIMPLE_
> variants
> of _PM_OPS(), which export dev_pm_ops symbol only in case
> CONFIG_PM_SLEEP=y
> and discard it otherwise.
> 
> Fixes: 34e1ed189fab ("PM: Improve EXPORT_*_DEV_PM_OPS macros")
> Signed-off-by: Raag Jadav <raag.jadav@intel.com>
> ---
> PS: This is a standalone fix and works without updating any drivers.

I had to double-check that, to make sure that none of the drivers using
these macros also use pm_ptr() instead of pm_sleep_ptr() to access the
exported dev_pm_ops.

I did not check extensively but everything seems to use pm_sleep_ptr(),
so it looks safe enough.

> 
> Changes since v2:
> - Drop redundant patches
> 
> Changes since v1:
> - Update drivers to new set of macros
> 
>  include/linux/pm.h | 43 +++++++++++++++++++++++++++++--------------
>  1 file changed, 29 insertions(+), 14 deletions(-)
> 
> diff --git a/include/linux/pm.h b/include/linux/pm.h
> index 1400c37b29c7..99a8146fa479 100644
> --- a/include/linux/pm.h
> +++ b/include/linux/pm.h
> @@ -374,24 +374,39 @@ const struct dev_pm_ops name = { \
>         RUNTIME_PM_OPS(runtime_suspend_fn, runtime_resume_fn,
> idle_fn) \
>  }
>  
> -#ifdef CONFIG_PM
> -#define _EXPORT_DEV_PM_OPS(name, license,
> ns)                          \
> +#define _EXPORT_PM_OPS(name, license,
> ns)                              \
>         const struct dev_pm_ops
> name;                                   \
>         __EXPORT_SYMBOL(name, license,
> ns);                             \
>         const struct dev_pm_ops name
> -#define EXPORT_PM_FN_GPL(name)         EXPORT_SYMBOL_GPL(name)
> -#define EXPORT_PM_FN_NS_GPL(name, ns)  EXPORT_SYMBOL_NS_GPL(name,
> ns)
> -#else
> -#define _EXPORT_DEV_PM_OPS(name, license,
> ns)                          \
> +
> +#define _PM_OPS(name, license,

This macro creates a dev_pm_ops that's meant to be garbage-collected by
the compiler; so maybe name it _USELESS_PM_OPS() or something like
that.

(I could have said that in your v2 patch, sorry)

Cheers,
-Paul

> ns)                                     \
>         static __maybe_unused const struct dev_pm_ops __static_##name
> +
> +#ifdef CONFIG_PM
> +#define _EXPORT_DEV_PM_OPS(name, license,
> ns)          _EXPORT_PM_OPS(name, license, ns)
> +#define
> EXPORT_PM_FN_GPL(name)                         EXPORT_SYMBOL_GPL(name
> )
> +#define EXPORT_PM_FN_NS_GPL(name,
> ns)                  EXPORT_SYMBOL_NS_GPL(name, ns)
> +#else
> +#define _EXPORT_DEV_PM_OPS(name, license, ns)          _PM_OPS(name,
> license, ns)
>  #define EXPORT_PM_FN_GPL(name)
>  #define EXPORT_PM_FN_NS_GPL(name, ns)
>  #endif
>  
> -#define EXPORT_DEV_PM_OPS(name) _EXPORT_DEV_PM_OPS(name, "", "")
> -#define EXPORT_GPL_DEV_PM_OPS(name) _EXPORT_DEV_PM_OPS(name, "GPL",
> "")
> -#define EXPORT_NS_DEV_PM_OPS(name, ns) _EXPORT_DEV_PM_OPS(name, "",
> #ns)
> -#define EXPORT_NS_GPL_DEV_PM_OPS(name, ns) _EXPORT_DEV_PM_OPS(name,
> "GPL", #ns)
> +#ifdef CONFIG_PM_SLEEP
> +#define _EXPORT_DEV_SLEEP_PM_OPS(name, license,
> ns)    _EXPORT_PM_OPS(name, license, ns)
> +#else
> +#define _EXPORT_DEV_SLEEP_PM_OPS(name, license, ns)    _PM_OPS(name,
> license, ns)
> +#endif
> +
> +#define
> EXPORT_DEV_PM_OPS(name)                                _EXPORT_DEV_PM
> _OPS(name, "", "")
> +#define
> EXPORT_GPL_DEV_PM_OPS(name)                    _EXPORT_DEV_PM_OPS(nam
> e, "GPL", "")
> +#define EXPORT_NS_DEV_PM_OPS(name,
> ns)                 _EXPORT_DEV_PM_OPS(name, "", #ns)
> +#define EXPORT_NS_GPL_DEV_PM_OPS(name,
> ns)             _EXPORT_DEV_PM_OPS(name, "GPL", #ns)
> +
> +#define
> EXPORT_DEV_SLEEP_PM_OPS(name)                  _EXPORT_DEV_SLEEP_PM_O
> PS(name, "", "")
> +#define
> EXPORT_GPL_DEV_SLEEP_PM_OPS(name)              _EXPORT_DEV_SLEEP_PM_O
> PS(name, "GPL", "")
> +#define EXPORT_NS_DEV_SLEEP_PM_OPS(name,
> ns)           _EXPORT_DEV_SLEEP_PM_OPS(name, "", #ns)
> +#define EXPORT_NS_GPL_DEV_SLEEP_PM_OPS(name,
> ns)       _EXPORT_DEV_SLEEP_PM_OPS(name, "GPL", #ns)
>  
>  /*
>   * Use this if you want to use the same suspend and resume callbacks
> for suspend
> @@ -404,19 +419,19 @@ const struct dev_pm_ops name = { \
>         _DEFINE_DEV_PM_OPS(name, suspend_fn, resume_fn, NULL, NULL,
> NULL)
>  
>  #define EXPORT_SIMPLE_DEV_PM_OPS(name, suspend_fn, resume_fn) \
> -       EXPORT_DEV_PM_OPS(name) = { \
> +       EXPORT_DEV_SLEEP_PM_OPS(name) = { \
>                 SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
>         }
>  #define EXPORT_GPL_SIMPLE_DEV_PM_OPS(name, suspend_fn, resume_fn) \
> -       EXPORT_GPL_DEV_PM_OPS(name) = { \
> +       EXPORT_GPL_DEV_SLEEP_PM_OPS(name) = { \
>                 SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
>         }
>  #define EXPORT_NS_SIMPLE_DEV_PM_OPS(name, suspend_fn, resume_fn,
> ns)   \
> -       EXPORT_NS_DEV_PM_OPS(name, ns) = { \
> +       EXPORT_NS_DEV_SLEEP_PM_OPS(name, ns) = { \
>                 SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
>         }
>  #define EXPORT_NS_GPL_SIMPLE_DEV_PM_OPS(name, suspend_fn, resume_fn,
> ns)       \
> -       EXPORT_NS_GPL_DEV_PM_OPS(name, ns) = { \
> +       EXPORT_NS_GPL_DEV_SLEEP_PM_OPS(name, ns) = { \
>                 SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
>         }
>