On 2021-05-26 at 20:07:28 +0530, Imre Deak wrote: > It's possible that an already dequeued put_async_work() will release the > reference (*) that was put asynchronously after the dequeue happened. > This leaves an async-put work pending, without any reference to release. > A subsequent async-put may trigger the > > drm_WARN_ON(!queue_delayed_work(&power_domains->async_put_work)); > > warn due to async_put_work() still pending. To avoid the warn, cancel > the pending async_put_work() when releasing the reference at (*) above. Not able to visulize the race here between __intel_display_power_put_async and intel_display_power_put_async_work() considering both are protected by power_domains->lock. queue_delayed_work_on() documentation says following about return value. "Return: %false if @work was already on a queue, %true otherwise." AFAIU from the doc, queue_delayed_work will return false only when work was in queue after dequeued put_async_work() it should return true ? Thanks, Anshuman Gupta. > > Fixes: https://gitlab.freedesktop.org/drm/intel/-/issues/3421 > Fixes: https://gitlab.freedesktop.org/drm/intel/-/issues/2289 > Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx> > --- > drivers/gpu/drm/i915/display/intel_display_power.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/drivers/gpu/drm/i915/display/intel_display_power.c b/drivers/gpu/drm/i915/display/intel_display_power.c > index 2f7d1664c4738..a95bbf23e6b7c 100644 > --- a/drivers/gpu/drm/i915/display/intel_display_power.c > +++ b/drivers/gpu/drm/i915/display/intel_display_power.c > @@ -2263,6 +2263,12 @@ intel_display_power_put_async_work(struct work_struct *work) > fetch_and_zero(&power_domains->async_put_domains[1]); > queue_async_put_domains_work(power_domains, > fetch_and_zero(&new_work_wakeref)); > + } else { > + /* > + * Cancel the work that got queued after this one got dequeued, > + * since here we released the corresponding async-put reference. > + */ > + cancel_delayed_work(&power_domains->async_put_work); > } > > out_verify: > -- > 2.27.0 > > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx > https://lists.freedesktop.org/mailman/listinfo/intel-gfx _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
