drm/i915/breadcrumbs: Assert all missed breadcrumbs were signaled

When parking the engines and their breadcrumbs, if we have waiters left
then they missed their wakeup. Verify that each waiter's seqno did
complete.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180222092545.17216-2-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/intel_breadcrumbs.c

@@ -247,6 +247,8 @@ void intel_engine_disarm_breadcrumbs(struct intel_engine_cs *engine)
 	spin_unlock(&b->irq_lock);
 
 	rbtree_postorder_for_each_entry_safe(wait, n, &b->waiters, node) {
+		GEM_BUG_ON(!i915_seqno_passed(intel_engine_get_seqno(engine),
+					      wait->seqno));
 		RB_CLEAR_NODE(&wait->node);
 		wake_up_process(wait->tsk);
 	}