| Message ID | 20211207002102.26414-3-paul@crapouillou.net (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Rework pm_ptr() and *_PM_OPS macros | expand |
On Tue, 7 Dec 2021 00:20:59 +0000 Paul Cercueil <paul@crapouillou.net> wrote: > The pm_ptr() macro was previously conditionally defined, according to > the value of the CONFIG_PM option. This meant that the pointed structure > was either referenced (if CONFIG_PM was set), or never referenced (if > CONFIG_PM was not set), causing it to be detected as unused by the > compiler. > > This worked fine, but required the __maybe_unused compiler attribute to > be used to every symbol pointed to by a pointer wrapped with pm_ptr(). > > We can do better. With this change, the pm_ptr() is now defined the > same, independently of the value of CONFIG_PM. It now uses the (?:) > ternary operator to conditionally resolve to its argument. Since the > condition is known at compile time, the compiler will then choose to > discard the unused symbols, which won't need to be tagged with > __maybe_unused anymore. > > This pm_ptr() macro is usually used with pointers to dev_pm_ops > structures created with SIMPLE_DEV_PM_OPS() or similar macros. These do > use a __maybe_unused flag, which is now useless with this change, so it > later can be removed. However in the meantime it causes no harm, and all > the drivers still compile fine with the new pm_ptr() macro. > > Signed-off-by: Paul Cercueil <paul@crapouillou.net> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> > --- > include/linux/pm.h | 6 +----- > 1 file changed, 1 insertion(+), 5 deletions(-) > > diff --git a/include/linux/pm.h b/include/linux/pm.h > index 1d8209c09686..b88ac7dcf2a2 100644 > --- a/include/linux/pm.h > +++ b/include/linux/pm.h > @@ -373,11 +373,7 @@ const struct dev_pm_ops __maybe_unused name = { \ > SET_RUNTIME_PM_OPS(suspend_fn, resume_fn, idle_fn) \ > } > > -#ifdef CONFIG_PM > -#define pm_ptr(_ptr) (_ptr) > -#else > -#define pm_ptr(_ptr) NULL > -#endif > +#define pm_ptr(_ptr) PTR_IF(IS_ENABLED(CONFIG_PM), (_ptr)) > > /* > * PM_EVENT_ messages
diff --git a/include/linux/pm.h b/include/linux/pm.h index 1d8209c09686..b88ac7dcf2a2 100644 --- a/include/linux/pm.h +++ b/include/linux/pm.h @@ -373,11 +373,7 @@ const struct dev_pm_ops __maybe_unused name = { \ SET_RUNTIME_PM_OPS(suspend_fn, resume_fn, idle_fn) \ } -#ifdef CONFIG_PM -#define pm_ptr(_ptr) (_ptr) -#else -#define pm_ptr(_ptr) NULL -#endif +#define pm_ptr(_ptr) PTR_IF(IS_ENABLED(CONFIG_PM), (_ptr)) /* * PM_EVENT_ messages
The pm_ptr() macro was previously conditionally defined, according to the value of the CONFIG_PM option. This meant that the pointed structure was either referenced (if CONFIG_PM was set), or never referenced (if CONFIG_PM was not set), causing it to be detected as unused by the compiler. This worked fine, but required the __maybe_unused compiler attribute to be used to every symbol pointed to by a pointer wrapped with pm_ptr(). We can do better. With this change, the pm_ptr() is now defined the same, independently of the value of CONFIG_PM. It now uses the (?:) ternary operator to conditionally resolve to its argument. Since the condition is known at compile time, the compiler will then choose to discard the unused symbols, which won't need to be tagged with __maybe_unused anymore. This pm_ptr() macro is usually used with pointers to dev_pm_ops structures created with SIMPLE_DEV_PM_OPS() or similar macros. These do use a __maybe_unused flag, which is now useless with this change, so it later can be removed. However in the meantime it causes no harm, and all the drivers still compile fine with the new pm_ptr() macro. Signed-off-by: Paul Cercueil <paul@crapouillou.net> --- include/linux/pm.h | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-)