On Thu, 21 Feb 2019 at 10:35, Rafael J. Wysocki <raf...@kernel.org> wrote:
>
> On Thu, Feb 21, 2019 at 8:59 AM Vincent Guittot
> <vincent.guit...@linaro.org> wrote:
> >
> > When rpm_resume() desactivates the autosuspend timer, it should only try
> > to cancel hrtimer but not wait for the handler to finish because both
> > rpm_resume() and pm_suspend_timer_fn() are taking the power.lock.
> > We can have the deadlock sequence:
> > CPU0 CPU1
> > rpm_resume()
> > spin_lock_irqsave
> > pm_suspend_timer_fn()
> > spin_lock_irqsave
> > pm_runtime_deactivate_timer()
> > hrtimer_cancel()
>
> Everybody has missed this, not good.
yes. default behavior if different between timer and hrtimer
del_timer() is equivalent to hrtimer_try_to_cancel()
and hrtimer_cancel() to del_timer_sync()
>
> > hrtimer_try_to_cancel() is enough because dev->power.timer_expires is also
> > set to 0.
> >
> > Fixes: 8234f6734c5d ("PM-runtime: Switch autosuspend over to using
> > hrtimers")
> > Reported-by: Sunzhaosheng Sun(Zhaosheng) <sunzhaosh...@hisilicon.com>
> > Signed-off-by: Vincent Guittot <vincent.guit...@linaro.org>
> > ---
> > 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 04407d9..78937c4 100644
> > --- a/drivers/base/power/runtime.c
> > +++ b/drivers/base/power/runtime.c
> > @@ -121,7 +121,7 @@ EXPORT_SYMBOL_GPL(pm_runtime_suspended_time);
> > static void pm_runtime_deactivate_timer(struct device *dev)
> > {
> > if (dev->power.timer_expires > 0) {
> > - hrtimer_cancel(&dev->power.suspend_timer);
> > + hrtimer_try_to_cancel(&dev->power.suspend_timer);
> > dev->power.timer_expires = 0;
> > }
> > }
> > --
>
> Applied with some changelog modifications, thanks!
Thanks
