[Intel-gfx] [PATCH] drm/i915: Add a warning on shutdown if signal threads still active

[Chris Wilson]

On Mon, Nov 21, 2016 at 10:42:37AM +0000, Tvrtko Ursulin wrote:
> 
> On 21/11/2016 09:40, Chris Wilson wrote:
> >When unloading the module, it is expected that we have finished
> >executing all requests and so the signal threads should be idle. Add a
> >warning in case there are any residual requests in the signaler rbtrees
> >at that point.
> >
> >Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> >---
> > drivers/gpu/drm/i915/intel_breadcrumbs.c | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> >diff --git a/drivers/gpu/drm/i915/intel_breadcrumbs.c b/drivers/gpu/drm/i915/intel_breadcrumbs.c
> >index c9c46a538edb..b7006e90a167 100644
> >--- a/drivers/gpu/drm/i915/intel_breadcrumbs.c
> >+++ b/drivers/gpu/drm/i915/intel_breadcrumbs.c
> >@@ -623,6 +623,8 @@ void intel_engine_fini_breadcrumbs(struct intel_engine_cs *engine)
> > {
> > 	struct intel_breadcrumbs *b = &engine->breadcrumbs;
> >
> >+	WARN_ON(READ_ONCE(b->first_signal));
> >+	WARN_ON(!RB_EMPTY_ROOT(&b->signals));
> > 	if (!IS_ERR_OR_NULL(b->signaler))
> > 		kthread_stop(b->signaler);
> >
> >
> 
> Not sure if you are just testing out theories on the CI, but in any
> case looks to me it wouldn't harm to have this in.

Only staring at the impossible, ruling out the unlikely. A leak here
would be caught by the request kmem_cache, but being explicit might help
in future.
 
> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

Imagine if I added a 

WARN_ON(READ_ONCE(b->first_waiter));
WARN_ON(!RB_EMPTY_ROOT(&b->waiters));

as well? Still r-b or go with a second patch for the afterthought?
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre