From c58e7ed28b4534ed073371843d03c433d6a9fe34 Mon Sep 17 00:00:00 2001 From: Krzysztof Kozlowski Date: Wed, 26 May 2021 12:22:51 -0400 Subject: PM: runtime: document common mistake with pm_runtime_get_sync() pm_runtime_get_sync(), contradictory to intuition, does not drop the runtime PM usage counter on errors which lead to several wrong usages in drivers (missing the put). pm_runtime_resume_and_get() was added as a better implementation so document the preference of using it, hoping it will stop bad patterns. Suggested-by: Marek Szyprowski Signed-off-by: Krzysztof Kozlowski [ rjw: Documentation change edits ] Signed-off-by: Rafael J. Wysocki --- Documentation/power/runtime_pm.rst | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'Documentation/power/runtime_pm.rst') diff --git a/Documentation/power/runtime_pm.rst b/Documentation/power/runtime_pm.rst index 18ae21bf7f92..b48cac5f9048 100644 --- a/Documentation/power/runtime_pm.rst +++ b/Documentation/power/runtime_pm.rst @@ -378,7 +378,11 @@ drivers/base/power/runtime.c and include/linux/pm_runtime.h: `int pm_runtime_get_sync(struct device *dev);` - increment the device's usage counter, run pm_runtime_resume(dev) and - return its result + return its result; + note that it does not drop the device's usage counter on errors, so + consider using pm_runtime_resume_and_get() instead of it, especially + if its return value is checked by the caller, as this is likely to + result in cleaner code. `int pm_runtime_get_if_in_use(struct device *dev);` - return -EINVAL if 'power.disable_depth' is nonzero; otherwise, if the -- cgit v1.2.3-59-g8ed1b