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Commit 311aab73 authored by Colin Cross's avatar Colin Cross Committed by Rafael J. Wysocki
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PM / Runtime: Add might_sleep() to runtime PM functions 



Some of the entry points to pm runtime are not safe to
call in atomic context unless pm_runtime_irq_safe() has
been called.  Inspecting the code, it is not immediately
obvious that the functions sleep at all, as they run
inside a spin_lock_irqsave, but under some conditions
they can drop the lock and turn on irqs.

If a driver incorrectly calls the pm_runtime apis, it can
cause sleeping and irq processing when it expects to stay
in atomic context.

Add might_sleep_if to the majority of the __pm_runtime_* entry points
to enforce correct usage.

Add pm_runtime_put_sync_autosuspend to the list of
functions that can be called in atomic context.

Signed-off-by: default avatarColin Cross <ccross@android.com>
Reviewed-by: default avatarKevin Hilman <khilman@ti.com>
Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
parent 17f2ae7f

Documentation/power/runtime_pm.txt

+1 −0
Original line number Diff line number Diff line
@@ -484,6 +484,7 @@ pm_runtime_resume() 
pm_runtime_get_sync()

pm_runtime_put_sync()

pm_runtime_put_sync_suspend()

pm_runtime_put_sync_autosuspend()



5. Runtime PM Initialization, Device Probing and Removal

drivers/base/power/runtime.c

+12 −3
Original line number Diff line number Diff line
@@ -732,13 +732,16 @@ EXPORT_SYMBOL_GPL(pm_schedule_suspend); 
 * return immediately if it is larger than zero.  Then carry out an idle

 * notification, either synchronous or asynchronous.

 *

 * This routine may be called in atomic context if the RPM_ASYNC flag is set.

 * This routine may be called in atomic context if the RPM_ASYNC flag is set,

 * or if pm_runtime_irq_safe() has been called.

 */

int __pm_runtime_idle(struct device *dev, int rpmflags)

{

	unsigned long flags;

	int retval;



	might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe);



	if (rpmflags & RPM_GET_PUT) {

		if (!atomic_dec_and_test(&dev->power.usage_count))

			return 0;
@@ -761,13 +764,16 @@ EXPORT_SYMBOL_GPL(__pm_runtime_idle); 
 * return immediately if it is larger than zero.  Then carry out a suspend,

 * either synchronous or asynchronous.

 *

 * This routine may be called in atomic context if the RPM_ASYNC flag is set.

 * This routine may be called in atomic context if the RPM_ASYNC flag is set,

 * or if pm_runtime_irq_safe() has been called.

 */

int __pm_runtime_suspend(struct device *dev, int rpmflags)

{

	unsigned long flags;

	int retval;



	might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe);



	if (rpmflags & RPM_GET_PUT) {

		if (!atomic_dec_and_test(&dev->power.usage_count))

			return 0;
@@ -789,13 +795,16 @@ EXPORT_SYMBOL_GPL(__pm_runtime_suspend); 
 * If the RPM_GET_PUT flag is set, increment the device's usage count.  Then

 * carry out a resume, either synchronous or asynchronous.

 *

 * This routine may be called in atomic context if the RPM_ASYNC flag is set.

 * This routine may be called in atomic context if the RPM_ASYNC flag is set,

 * or if pm_runtime_irq_safe() has been called.

 */

int __pm_runtime_resume(struct device *dev, int rpmflags)

{

	unsigned long flags;

	int retval;



	might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe);



	if (rpmflags & RPM_GET_PUT)

		atomic_inc(&dev->power.usage_count);