On Saturday, July 23, 2011, Colin Cross wrote:
> The list of functions that can be called in atomic context is
> non-intuitive (pm_runtime_put_sync can not, but
> pm_runtime_put_sync_suspend can, if pm_runtime_irq_safe has
> been called?).
However, this behavior is documented.
Also, if you have a clean use case for calling rpm_idle() with interrupts
off, it can be modified to work in analogy with rpm_suspend() in that respect.
> The code is actively misleading - the entry
> points all start with spin_lock_irqsave, suggesting they
> are safe to call in atomic context, but may later
> enable interrupts.
May I say it is this way for a reason?
> Add might_sleep_if to all the __pm_runtime_* entry points
> to enforce correct usage.
I'm not sure how this makes things better.
> Also add pm_runtime_put_sync_autosuspend to the list of
> functions that can be called in atomic context.
OK
In addition to that rpm_idle() is missing the __releases __acquires
annotations.
> Signed-off-by: Colin Cross <ccross@xxxxxxxxxxx>
> ---
> Documentation/power/runtime_pm.txt | 1 +
> drivers/base/power/runtime.c | 16 ++++++++++++++--
> 2 files changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/power/runtime_pm.txt b/Documentation/power/runtime_pm.txt
> index b24875b..22852b3 100644
> --- a/Documentation/power/runtime_pm.txt
> +++ b/Documentation/power/runtime_pm.txt
> @@ -469,6 +469,7 @@ pm_runtime_autosuspend()
> pm_runtime_resume()
> pm_runtime_get_sync()
> pm_runtime_put_sync_suspend()
> +pm_runtime_put_sync_autosuspend()
>
> 5. Run-time PM Initialization, Device Probing and Removal
>
> diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
> index 0d4587b..fdc4567 100644
> --- a/drivers/base/power/runtime.c
> +++ b/drivers/base/power/runtime.c
> @@ -732,6 +732,8 @@ int __pm_runtime_idle(struct device *dev, int rpmflags)
> unsigned long flags;
> int retval;
>
> + might_sleep_if(!(rpmflags & RPM_ASYNC));
> +
> if (rpmflags & RPM_GET_PUT) {
> if (!atomic_dec_and_test(&dev->power.usage_count))
> return 0;
> @@ -754,13 +756,16 @@ 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;
> @@ -782,13 +787,16 @@ 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);
>
> @@ -978,6 +986,8 @@ EXPORT_SYMBOL_GPL(pm_runtime_barrier);
> */
> void __pm_runtime_disable(struct device *dev, bool check_resume)
> {
> + might_sleep();
> +
Well, it's not correct to call spin_lock_irq() from interrupt context anyway.
> spin_lock_irq(&dev->power.lock);
>
> if (dev->power.disable_depth > 0) {
> @@ -1184,6 +1194,8 @@ void __pm_runtime_use_autosuspend(struct device *dev, bool use)
> {
> int old_delay, old_use;
>
> + might_sleep();
> +
> spin_lock_irq(&dev->power.lock);
> old_delay = dev->power.autosuspend_delay;
> old_use = dev->power.use_autosuspend;
>
Thanks,
Rafael
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