On Fri, Mar 03, 2017 at 02:52:59PM +0000, Chris Wilson wrote:
> On Fri, Mar 03, 2017 at 02:45:57PM +0000, Chris Wilson wrote:
> > ---
> > drivers/gpu/drm/i915/i915_irq.c | 10 ++++------
> > 1 file changed, 4 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_irq.c
> > b/drivers/gpu/drm/i915/i915_irq.c
> > index 5fa2c4c56b09..73ab5abf20d7 100644
> > --- a/drivers/gpu/drm/i915/i915_irq.c
> > +++ b/drivers/gpu/drm/i915/i915_irq.c
> > @@ -1039,8 +1039,6 @@ static void notify_ring(struct intel_engine_cs
> > *engine)
> > atomic_inc(&engine->irq_count);
> > set_bit(ENGINE_IRQ_BREADCRUMB, &engine->irq_posted);
> >
> > - rcu_read_lock();
> > -
> > spin_lock(&engine->breadcrumbs.lock);
> > wait = engine->breadcrumbs.first_wait;
> > if (wait) {
> > @@ -1057,7 +1055,7 @@ static void notify_ring(struct intel_engine_cs
> > *engine)
> > */
> > if (i915_seqno_passed(intel_engine_get_seqno(engine),
> > wait->seqno))
> > - rq = wait->request;
> > + rq = i915_gem_request_get(wait->request);
> >
> > wake_up_process(wait->tsk);
> > } else {
> > @@ -1065,10 +1063,10 @@ static void notify_ring(struct intel_engine_cs
> > *engine)
> > }
> > spin_unlock(&engine->breadcrumbs.lock);
> >
> > - if (rq)
> > + if (rq) {
> > dma_fence_signal(&rq->fence);
> > -
> > - rcu_read_unlock();
> > + i915_gem_request_put(rq);
> > + }
>
> The alternative would be to place spin_unlock_wait() in
> i915_fence_release. The advantages of that will be avoiding the extra
> work inside the interrupt handler.
That's not enough as there's an open window before we acquire the
fence->lock.
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
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