Re: [PATCH v2 3/6] PM: core: Add EXPORT[_GPL]_SIMPLE_DEV_PM_OPS macros

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Le ven., janv. 7 2022 at 17:33:04 +0100, Ulf Hansson <ulf.hansson@xxxxxxxxxx> a écrit :
On Wed, 5 Jan 2022 at 19:30, 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.

How common is it to export the dev_pm_ops? Do we really need a macro for this?

$ rgrep EXPORT_SYMBOL drivers/ |grep pm_ops |wc -l
44

That should be enough to justify a macro.

Cheers,
-Paul


The similar comment/question applies for patch5.


 Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
 Acked-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>

Kind regards
Uffe

 ---

 Notes:
     v2: Remove useless empty line

  include/linux/pm.h | 32 +++++++++++++++++++++++++++++---
  1 file changed, 29 insertions(+), 3 deletions(-)

 diff --git a/include/linux/pm.h b/include/linux/pm.h
 index 389e600df233..b82f40e701ab 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 +358,39 @@ 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) \
 +}
 +
  /*
* 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")

  /* Deprecated. Use DEFINE_SIMPLE_DEV_PM_OPS() instead. */
  #define SIMPLE_DEV_PM_OPS(name, suspend_fn, resume_fn) \
 --
 2.34.1






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