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SubjectRe: [PATCH] PM / Runtime: return the right value when deferred_resume is true in rpm_suspend()
Date
On Tuesday, January 15, 2013 11:26:11 PM Chuansheng Liu wrote:
>
> For the case that in rpm_suspend() and deferred_resume is true,
> the rpm_resume() will be called, and if rpm_resume() return error,
> at this time, the device is still in SUSPENDED state.
>
> In this case it is still an suspend succeeding case, we should
> return non-error instead of EAGAIN.
>
> An example like below for this case:
> CPU1: CPU2:
> pm_runtime_get_sync()
> pm_runtime_put_sync_suspend()
> rpm_suspend()
> __update_runtime_status(dev, RPM_SUSPENDING)
> rpm_callback()
> spin_unlock_irq()
> ... pm_runtime_get()
> spin_lock_irqsave()
> cb() rpm_resume()
> ... dev->power.deferred_resume = true
> spin_unlock_irqrestore()
> spin_lock_irq()
> __update_runtime_status(dev, RPM_SUSPENDED)
> rpm_resume() is called due to deferred_resume is true
>
> Here if rpm_resume() failed in CPU1, the runtime_status is still SUSPENDED,
> we should return 0 in this case.

No, we shouldn't.

Please note that rpm_resume() may fail for multiple reasons and some of them
actually mean real errors, in which case we shouldn't return 0, because that
may confuse the caller.

However, if we return -EAGAIN regardless, whatever the caller does next will
be fine.

Thanks,
Rafael


> Signed-off-by: liu chuansheng <chuansheng.liu@intel.com>
> ---
> drivers/base/power/runtime.c | 8 +++++---
> 1 files changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
> index 3148b10..0adc713 100644
> --- a/drivers/base/power/runtime.c
> +++ b/drivers/base/power/runtime.c
> @@ -436,9 +436,11 @@ static int rpm_suspend(struct device *dev, int rpmflags)
>
> if (dev->power.deferred_resume) {
> dev->power.deferred_resume = false;
> - rpm_resume(dev, 0);
> - retval = -EAGAIN;
> - goto out;
> + if (rpm_resume(dev, 0) >= 0) {
> + /* In case resuming succeeded, return EAGAIN error */
> + retval = -EAGAIN;
> + goto out;
> + }
> }
>
> /* Maybe the parent is now able to suspend. */
>
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.


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