[Intel-gfx] [PATCH] drm/i915: Assert breadcrumbs are correctly ordered in the signal handler

[Chris Wilson]

Inside the signal handler, we expect the requests to be ordered by their
breadcrumb such that no later request may be complete if we find an
earlier incomplete. Add an assert to check that the next breadcrumb
should not be logically before the current.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/gt/intel_breadcrumbs.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c
index 3cbffd400b1b..a6ffb25f72a2 100644
--- a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c
+++ b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c
@@ -99,6 +99,12 @@ void intel_engine_breadcrumbs_irq(struct intel_engine_cs *engine)
 			struct i915_request *rq =
 				list_entry(pos, typeof(*rq), signal_link);
 
+			GEM_BUG_ON(next != &ce->signals &&
+				   i915_seqno_passed(rq->fence.seqno,
+						     list_entry(next,
+								typeof(*rq),
+								signal_link)->fence.seqno));
+
 			if (!__request_completed(rq))
 				break;
 
-- 
2.20.1