6.17-stable review patch. If anyone has any objections, please let me know.
------------------
From: Brian Norris briannorris@chromium.org
commit fed7eaa4f037361fe4f3d4170649d6849a25998d upstream.
APIs based on __pm_runtime_idle() (pm_runtime_idle(), pm_request_idle()) do not return 1 when already suspended. They return -EAGAIN. This is already covered in the docs, so the entry for "1" is redundant and conflicting.
(pm_runtime_put() and pm_runtime_put_sync() were previously incorrect, but that's fixed in "PM: runtime: pm_runtime_put{,_sync}() returns 1 when already suspended", to ensure consistency with APIs like pm_runtime_put_autosuspend().)
RPM_GET_PUT APIs based on __pm_runtime_suspend() do return 1 when already suspended, but the language is a little unclear -- it's not really an "error", so it seems better to list as a clarification before the 0/success case. Additionally, they only actually return 1 when the refcount makes it to 0; if the usage counter is still non-zero, we return 0.
pm_runtime_put(), etc., also don't appear at first like they can ever see "-EAGAIN: Runtime PM usage_count non-zero", because in non-racy conditions, pm_runtime_put() would drop its reference count, see it's non-zero, and return early (in __pm_runtime_idle()). However, it's possible to race with another actor that increments the usage_count afterward, since rpm_idle() is protected by a separate lock; in such a case, we may see -EAGAIN.
Because this case is only seen in the presence of concurrent actors, it makes sense to clarify that this is when "usage_count **became** non-zero", by way of some racing actor.
Lastly, pm_runtime_put_sync_suspend() duplicated some -EAGAIN language. Fix that.
Fixes: 271ff96d6066 ("PM: runtime: Document return values of suspend-related API functions") Link: https://lore.kernel.org/linux-pm/aJ5pkEJuixTaybV4@google.com/ Signed-off-by: Brian Norris briannorris@chromium.org Reviewed-by: Sakari Ailus sakari.ailus@linux.intel.com Cc: 6.17+ stable@vger.kernel.org # 6.17+ Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- include/linux/pm_runtime.h | 56 ++++++++++++++++++++++++--------------------- 1 file changed, 31 insertions(+), 25 deletions(-)
--- a/include/linux/pm_runtime.h +++ b/include/linux/pm_runtime.h @@ -350,13 +350,12 @@ static inline int pm_runtime_force_resum * * 0: Success. * * -EINVAL: Runtime PM error. * * -EACCES: Runtime PM disabled. - * * -EAGAIN: Runtime PM usage_count non-zero, Runtime PM status change ongoing - * or device not in %RPM_ACTIVE state. + * * -EAGAIN: Runtime PM usage counter non-zero, Runtime PM status change + * ongoing or device not in %RPM_ACTIVE state. * * -EBUSY: Runtime PM child_count non-zero. * * -EPERM: Device PM QoS resume latency 0. * * -EINPROGRESS: Suspend already in progress. * * -ENOSYS: CONFIG_PM not enabled. - * * 1: Device already suspended. * Other values and conditions for the above values are possible as returned by * Runtime PM idle and suspend callbacks. */ @@ -370,14 +369,15 @@ static inline int pm_runtime_idle(struct * @dev: Target device. * * Return: + * * 1: Success; device was already suspended. * * 0: Success. * * -EINVAL: Runtime PM error. * * -EACCES: Runtime PM disabled. - * * -EAGAIN: Runtime PM usage_count non-zero or Runtime PM status change ongoing. + * * -EAGAIN: Runtime PM usage counter non-zero or Runtime PM status change + * ongoing. * * -EBUSY: Runtime PM child_count non-zero. * * -EPERM: Device PM QoS resume latency 0. * * -ENOSYS: CONFIG_PM not enabled. - * * 1: Device already suspended. * Other values and conditions for the above values are possible as returned by * Runtime PM suspend callbacks. */ @@ -396,14 +396,15 @@ static inline int pm_runtime_suspend(str * engaging its "idle check" callback. * * Return: + * * 1: Success; device was already suspended. * * 0: Success. * * -EINVAL: Runtime PM error. * * -EACCES: Runtime PM disabled. - * * -EAGAIN: Runtime PM usage_count non-zero or Runtime PM status change ongoing. + * * -EAGAIN: Runtime PM usage counter non-zero or Runtime PM status change + * ongoing. * * -EBUSY: Runtime PM child_count non-zero. * * -EPERM: Device PM QoS resume latency 0. * * -ENOSYS: CONFIG_PM not enabled. - * * 1: Device already suspended. * Other values and conditions for the above values are possible as returned by * Runtime PM suspend callbacks. */ @@ -433,13 +434,12 @@ static inline int pm_runtime_resume(stru * * 0: Success. * * -EINVAL: Runtime PM error. * * -EACCES: Runtime PM disabled. - * * -EAGAIN: Runtime PM usage_count non-zero, Runtime PM status change ongoing - * or device not in %RPM_ACTIVE state. + * * -EAGAIN: Runtime PM usage counter non-zero, Runtime PM status change + * ongoing or device not in %RPM_ACTIVE state. * * -EBUSY: Runtime PM child_count non-zero. * * -EPERM: Device PM QoS resume latency 0. * * -EINPROGRESS: Suspend already in progress. * * -ENOSYS: CONFIG_PM not enabled. - * * 1: Device already suspended. */ static inline int pm_request_idle(struct device *dev) { @@ -464,15 +464,16 @@ static inline int pm_request_resume(stru * equivalent pm_runtime_autosuspend() for @dev asynchronously. * * Return: + * * 1: Success; device was already suspended. * * 0: Success. * * -EINVAL: Runtime PM error. * * -EACCES: Runtime PM disabled. - * * -EAGAIN: Runtime PM usage_count non-zero or Runtime PM status change ongoing. + * * -EAGAIN: Runtime PM usage counter non-zero or Runtime PM status change + * ongoing. * * -EBUSY: Runtime PM child_count non-zero. * * -EPERM: Device PM QoS resume latency 0. * * -EINPROGRESS: Suspend already in progress. * * -ENOSYS: CONFIG_PM not enabled. - * * 1: Device already suspended. */ static inline int pm_request_autosuspend(struct device *dev) { @@ -540,15 +541,16 @@ static inline int pm_runtime_resume_and_ * equal to 0, queue up a work item for @dev like in pm_request_idle(). * * Return: + * * 1: Success. Usage counter dropped to zero, but device was already suspended. * * 0: Success. * * -EINVAL: Runtime PM error. * * -EACCES: Runtime PM disabled. - * * -EAGAIN: Runtime PM usage_count non-zero or Runtime PM status change ongoing. + * * -EAGAIN: Runtime PM usage counter became non-zero or Runtime PM status + * change ongoing. * * -EBUSY: Runtime PM child_count non-zero. * * -EPERM: Device PM QoS resume latency 0. * * -EINPROGRESS: Suspend already in progress. * * -ENOSYS: CONFIG_PM not enabled. - * * 1: Device already suspended. */ static inline int pm_runtime_put(struct device *dev) { @@ -565,15 +567,16 @@ DEFINE_FREE(pm_runtime_put, struct devic * equal to 0, queue up a work item for @dev like in pm_request_autosuspend(). * * Return: + * * 1: Success. Usage counter dropped to zero, but device was already suspended. * * 0: Success. * * -EINVAL: Runtime PM error. * * -EACCES: Runtime PM disabled. - * * -EAGAIN: Runtime PM usage_count non-zero or Runtime PM status change ongoing. + * * -EAGAIN: Runtime PM usage counter became non-zero or Runtime PM status + * change ongoing. * * -EBUSY: Runtime PM child_count non-zero. * * -EPERM: Device PM QoS resume latency 0. * * -EINPROGRESS: Suspend already in progress. * * -ENOSYS: CONFIG_PM not enabled. - * * 1: Device already suspended. */ static inline int __pm_runtime_put_autosuspend(struct device *dev) { @@ -590,15 +593,16 @@ static inline int __pm_runtime_put_autos * in pm_request_autosuspend(). * * Return: + * * 1: Success. Usage counter dropped to zero, but device was already suspended. * * 0: Success. * * -EINVAL: Runtime PM error. * * -EACCES: Runtime PM disabled. - * * -EAGAIN: Runtime PM usage_count non-zero or Runtime PM status change ongoing. + * * -EAGAIN: Runtime PM usage counter became non-zero or Runtime PM status + * change ongoing. * * -EBUSY: Runtime PM child_count non-zero. * * -EPERM: Device PM QoS resume latency 0. * * -EINPROGRESS: Suspend already in progress. * * -ENOSYS: CONFIG_PM not enabled. - * * 1: Device already suspended. */ static inline int pm_runtime_put_autosuspend(struct device *dev) { @@ -619,14 +623,15 @@ static inline int pm_runtime_put_autosus * if it returns an error code. * * Return: + * * 1: Success. Usage counter dropped to zero, but device was already suspended. * * 0: Success. * * -EINVAL: Runtime PM error. * * -EACCES: Runtime PM disabled. - * * -EAGAIN: Runtime PM usage_count non-zero or Runtime PM status change ongoing. + * * -EAGAIN: Runtime PM usage counter became non-zero or Runtime PM status + * change ongoing. * * -EBUSY: Runtime PM child_count non-zero. * * -EPERM: Device PM QoS resume latency 0. * * -ENOSYS: CONFIG_PM not enabled. - * * 1: Device already suspended. * Other values and conditions for the above values are possible as returned by * Runtime PM suspend callbacks. */ @@ -646,15 +651,15 @@ static inline int pm_runtime_put_sync(st * if it returns an error code. * * Return: + * * 1: Success. Usage counter dropped to zero, but device was already suspended. * * 0: Success. * * -EINVAL: Runtime PM error. * * -EACCES: Runtime PM disabled. - * * -EAGAIN: Runtime PM usage_count non-zero or Runtime PM status change ongoing. - * * -EAGAIN: usage_count non-zero or Runtime PM status change ongoing. + * * -EAGAIN: Runtime PM usage counter became non-zero or Runtime PM status + * change ongoing. * * -EBUSY: Runtime PM child_count non-zero. * * -EPERM: Device PM QoS resume latency 0. * * -ENOSYS: CONFIG_PM not enabled. - * * 1: Device already suspended. * Other values and conditions for the above values are possible as returned by * Runtime PM suspend callbacks. */ @@ -677,15 +682,16 @@ static inline int pm_runtime_put_sync_su * if it returns an error code. * * Return: + * * 1: Success. Usage counter dropped to zero, but device was already suspended. * * 0: Success. * * -EINVAL: Runtime PM error. * * -EACCES: Runtime PM disabled. - * * -EAGAIN: Runtime PM usage_count non-zero or Runtime PM status change ongoing. + * * -EAGAIN: Runtime PM usage counter became non-zero or Runtime PM status + * change ongoing. * * -EBUSY: Runtime PM child_count non-zero. * * -EPERM: Device PM QoS resume latency 0. * * -EINPROGRESS: Suspend already in progress. * * -ENOSYS: CONFIG_PM not enabled. - * * 1: Device already suspended. * Other values and conditions for the above values are possible as returned by * Runtime PM suspend callbacks. */