[PATCH 37/67] drm/i915/gt: Free stale request on destroying the virtual engine

[Chris Wilson]

Since preempt-to-busy, we may unsubmit a request while it is still on
the HW and completes asynchronously. That means it may be retired and in
the process destroy the virtual engine (as the user has closed their
context), but that engine may still be holding onto the unsubmitted
compelted request. Therefore we need to potentially cleanup the old
request on destroying the virtual engine.

Fixes: 22b7a426bbe1 ("drm/i915/execlists: Preempt-to-busy")
References: 6d06779e8672 ("drm/i915: Load balancing across a virtual engine")
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
Cc: <stable at vger.kernel.org> # v5.4+
---
 drivers/gpu/drm/i915/gt/intel_lrc.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
index 98f018f20125..a2c6f2d7d1c7 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -5329,10 +5329,15 @@ static void virtual_context_destroy(struct kref *kref)
 		container_of(kref, typeof(*ve), context.ref);
 	unsigned int n;
 
-	GEM_BUG_ON(!list_empty(virtual_queue(ve)));
-	GEM_BUG_ON(ve->request);
 	GEM_BUG_ON(ve->context.inflight);
 
+	if (ve->request) {
+		GEM_BUG_ON(!i915_request_completed(ve->request));
+		i915_request_submit(ve->request);
+		i915_request_put(ve->request);
+	}
+	GEM_BUG_ON(!list_empty(virtual_queue(ve)));
+
 	for (n = 0; n < ve->num_siblings; n++) {
 		struct intel_engine_cs *sibling = ve->siblings[n];
 		struct rb_node *node = &ve->nodes[sibling->id].rb;
-- 
2.20.1