linux-kernel - Re: [PATCH] PM-runtime: fix denying of auto suspend in pm_suspend_timer

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Message-ID: <CAJZ5v0hanp631h_VGijY5Joj=tQn=sENnzu5AZDuqWsMiOi+mw@mail.gmail.com>
Date: Fri, 16 May 2025 22:06:58 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Charan Teja Kalla <quic_charante@...cinc.com>
Cc: rafael@...nel.org, len.brown@...el.com, pavel@...nel.org, 
	gregkh@...uxfoundation.org, dakr@...nel.org, linux-pm@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Patrick Daly <quic_pdaly@...cinc.com>
Subject: Re: [PATCH] PM-runtime: fix denying of auto suspend in pm_suspend_timer_fn

On Thu, May 15, 2025 at 8:42 AM Charan Teja Kalla
<quic_charante@...cinc.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@...cinc.com>
> Signed-off-by: Patrick Daly <quic_pdaly@...cinc.com>
> Signed-off-by: Charan Teja Kalla <quic_charante@...cinc.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!