[PATCH] PM-runtime: fix denying of auto suspend in pm_suspend_timer_fn

[PATCH] PM-runtime: fix denying of auto suspend in pm_suspend_timer_fn

[Charan Teja Kalla]

pm_runtime_put_autosuspend() schedules a hrtimer to expire at
"dev->power.timer_expires". If the hrtimer's callback -
pm_suspend_timer_fn - observes that the current time equals
"dev->power.timer_expires", it unexpectedly bails out instead of
proceeding with runtime suspend.

pm_suspend_timer_fn():
if (expires > 0 && expires < ktime_get_mono_fast_ns()) {
	dev->power.timer_expires = 0;
	rpm_suspend(..)
}

Additionally, as ->timer_expires is not cleared, all the future auto
suspend requests will not schedule hrtimer to perform auto suspend.

rpm_suspend():
if ((rpmflags & RPM_AUTO) &&...) {
     if (!(dev->power.timer_expires && ...) { <-- this will fail.
	hrtimer_start_range_ns(&dev->power.suspend_timer,...);
  }
}

Fix this by aswell checking if current time reaches the set expiration.

Co-developed-by: Patrick Daly <quic_pdaly@quicinc.com>
Signed-off-by: Patrick Daly <quic_pdaly@quicinc.com>
Signed-off-by: Charan Teja Kalla <quic_charante@quicinc.com>
---
 drivers/base/power/runtime.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 205a4f8828b0..c55a7c70bc1a 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -1011,7 +1011,7 @@ static enum hrtimer_restart  pm_suspend_timer_fn(struct hrtimer *timer)
 	 * If 'expires' is after the current time, we've been called
 	 * too early.
 	 */
-	if (expires > 0 && expires < ktime_get_mono_fast_ns()) {
+	if (expires > 0 && expires <= ktime_get_mono_fast_ns()) {
 		dev->power.timer_expires = 0;
 		rpm_suspend(dev, dev->power.timer_autosuspends ?
 		    (RPM_ASYNC | RPM_AUTO) : RPM_ASYNC);
-- 
2.34.1

Re: [PATCH] PM-runtime: fix denying of auto suspend in pm_suspend_timer_fn

[Rafael J. Wysocki]

On Thu, May 15, 2025 at 8:42 AM Charan Teja Kalla
<quic_charante@quicinc.com> wrote:
>
> pm_runtime_put_autosuspend() schedules a hrtimer to expire at
> "dev->power.timer_expires". If the hrtimer's callback -
> pm_suspend_timer_fn - observes that the current time equals
> "dev->power.timer_expires", it unexpectedly bails out instead of
> proceeding with runtime suspend.
>
> pm_suspend_timer_fn():
> if (expires > 0 && expires < ktime_get_mono_fast_ns()) {
>         dev->power.timer_expires = 0;
>         rpm_suspend(..)
> }
>
> Additionally, as ->timer_expires is not cleared, all the future auto
> suspend requests will not schedule hrtimer to perform auto suspend.
>
> rpm_suspend():
> if ((rpmflags & RPM_AUTO) &&...) {
>      if (!(dev->power.timer_expires && ...) { <-- this will fail.
>         hrtimer_start_range_ns(&dev->power.suspend_timer,...);
>   }
> }
>
> Fix this by aswell checking if current time reaches the set expiration.
>
> Co-developed-by: Patrick Daly <quic_pdaly@quicinc.com>
> Signed-off-by: Patrick Daly <quic_pdaly@quicinc.com>
> Signed-off-by: Charan Teja Kalla <quic_charante@quicinc.com>
> ---
>  drivers/base/power/runtime.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
> index 205a4f8828b0..c55a7c70bc1a 100644
> --- a/drivers/base/power/runtime.c
> +++ b/drivers/base/power/runtime.c
> @@ -1011,7 +1011,7 @@ static enum hrtimer_restart  pm_suspend_timer_fn(struct hrtimer *timer)
>          * If 'expires' is after the current time, we've been called
>          * too early.
>          */
> -       if (expires > 0 && expires < ktime_get_mono_fast_ns()) {
> +       if (expires > 0 && expires <= ktime_get_mono_fast_ns()) {
>                 dev->power.timer_expires = 0;
>                 rpm_suspend(dev, dev->power.timer_autosuspends ?
>                     (RPM_ASYNC | RPM_AUTO) : RPM_ASYNC);
> --

Applied as 6.16 material, thanks!

Re: [PATCH] PM-runtime: fix denying of auto suspend in pm_suspend_timer_fn

[Charan Teja Kalla]

Hi Rafael,

On 5/17/2025 1:36 AM, Rafael J. Wysocki wrote:
>> diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
>> index 205a4f8828b0..c55a7c70bc1a 100644
>> --- a/drivers/base/power/runtime.c
>> +++ b/drivers/base/power/runtime.c
>> @@ -1011,7 +1011,7 @@ static enum hrtimer_restart  pm_suspend_timer_fn(struct hrtimer *timer)
>>          * If 'expires' is after the current time, we've been called
>>          * too early.
>>          */
>> -       if (expires > 0 && expires < ktime_get_mono_fast_ns()) {
>> +       if (expires > 0 && expires <= ktime_get_mono_fast_ns()) {
>>                 dev->power.timer_expires = 0;
>>                 rpm_suspend(dev, dev->power.timer_autosuspends ?
>>                     (RPM_ASYNC | RPM_AUTO) : RPM_ASYNC);
>> --
> Applied as 6.16 material, thanks!
Can you help me with why 'expires < ktime_get_mono_fast_ns())' is there?
We know that a timer callback is never going to get called before its
expiry. May be removal of this check altogether is the proper fix?

Thanks,
Charan