On Tue, 4 Jan 2022 21:42:09 +0000
Paul Cercueil <paul@xxxxxxxxxxxxxxx> wrote:
> These macros are defined conditionally, according to CONFIG_PM:
> - if CONFIG_PM is enabled, these macros resolve to
> DEFINE_SIMPLE_DEV_PM_OPS(), and the dev_pm_ops symbol will be
> exported.
>
> - if CONFIG_PM is disabled, these macros will result in a dummy static
> dev_pm_ops to be created with the __maybe_unused flag. The dev_pm_ops
> will then be discarded by the compiler, along with the provided
> callback functions if they are not used anywhere else.
>
> In the second case, the symbol is not exported, which should be
> perfectly fine - users of the symbol should all use the pm_ptr() or
> pm_sleep_ptr() macro, so the dev_pm_ops marked as "extern" in the
> client's code will never be accessed.
>
> Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
> ---
> include/linux/pm.h | 33 ++++++++++++++++++++++++++++++---
> 1 file changed, 30 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/pm.h b/include/linux/pm.h
> index 389e600df233..a1ce29566aea 100644
> --- a/include/linux/pm.h
> +++ b/include/linux/pm.h
> @@ -8,6 +8,7 @@
> #ifndef _LINUX_PM_H
> #define _LINUX_PM_H
>
> +#include <linux/export.h>
> #include <linux/list.h>
> #include <linux/workqueue.h>
> #include <linux/spinlock.h>
> @@ -357,14 +358,40 @@ struct dev_pm_ops {
> #define SET_RUNTIME_PM_OPS(suspend_fn, resume_fn, idle_fn)
> #endif
>
> +#define _DEFINE_DEV_PM_OPS(name, \
> + suspend_fn, resume_fn, \
> + runtime_suspend_fn, runtime_resume_fn, idle_fn) \
> +const struct dev_pm_ops name = { \
> + SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
> + RUNTIME_PM_OPS(runtime_suspend_fn, runtime_resume_fn, idle_fn) \
> +}
> +
one blank line probably enough.
> +
> /*
> * Use this if you want to use the same suspend and resume callbacks for suspend
> * to RAM and hibernation.
> */
> #define DEFINE_SIMPLE_DEV_PM_OPS(name, suspend_fn, resume_fn) \
> -const struct dev_pm_ops name = { \
> - SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
> -}
> + _DEFINE_DEV_PM_OPS(name, suspend_fn, resume_fn, NULL, NULL, NULL)
> +
> +#ifdef CONFIG_PM
> +#define _EXPORT_DEV_PM_OPS(name, suspend_fn, resume_fn, runtime_suspend_fn, \
> + runtime_resume_fn, idle_fn, sec) \
> + _DEFINE_DEV_PM_OPS(name, suspend_fn, resume_fn, runtime_suspend_fn, \
> + runtime_resume_fn, idle_fn); \
> + _EXPORT_SYMBOL(name, sec)
> +#else
> +#define _EXPORT_DEV_PM_OPS(name, suspend_fn, resume_fn, runtime_suspend_fn, \
> + runtime_resume_fn, idle_fn, sec) \
> +static __maybe_unused _DEFINE_DEV_PM_OPS(__static_##name, suspend_fn, \
> + resume_fn, runtime_suspend_fn, \
> + runtime_resume_fn, idle_fn)
> +#endif
> +
> +#define EXPORT_SIMPLE_DEV_PM_OPS(name, suspend_fn, resume_fn) \
> + _EXPORT_DEV_PM_OPS(name, suspend_fn, resume_fn, NULL, NULL, NULL, "")
> +#define EXPORT_GPL_SIMPLE_DEV_PM_OPS(name, suspend_fn, resume_fn) \
> + _EXPORT_DEV_PM_OPS(name, suspend_fn, resume_fn, NULL, NULL, NULL, "_gpl")
So you can get away with these two cases because the SYSTEM_SLEEP_PM_OPS() all have
pm_sleep_ptr() wrappers. However, _EXPORT_DEV_PM_OPS() could be used directly and
would require __maybe_unused for the RUNTIME_PM_OPS() parameters which isn't ideal.
Maybe I'm missing some reason that isn't a problem though as easy to get lost in
these macros. :)
You could argue that the _ is meant to indicate that macro shouldn't be used directly
but I'm not that optimistic.
Jonathan
>
> /* Deprecated. Use DEFINE_SIMPLE_DEV_PM_OPS() instead. */
> #define SIMPLE_DEV_PM_OPS(name, suspend_fn, resume_fn) \
