[Intel-gfx] [PATCH] drm/i915/guc: Cancel GuC engine busyness worker synchronously

[Umesh Nerlige Ramappa]

The worker is canceled in gt_park path, but earlier it was assumed that
gt_park path cannot sleep and the cancel is asynchronous. This caused a
race with suspend flow where the worker runs after suspend and causes an
unclaimed register access warning. Cancel the worker synchronously since
the gt_park is indeed allowed to sleep.

v2: Fix author name and sign-off mismatch

Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa at intel.com>
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/4419
Fixes: 77cdd054dd2c ("drm/i915/pmu: Connect engine busyness stats from GuC to pmu")
---
 drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
index 0d56b615bf78..e6275380b253 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -1438,7 +1438,12 @@ void intel_guc_busyness_park(struct intel_gt *gt)
 	if (!guc_submission_initialized(guc))
 		return;
 
-	cancel_delayed_work(&guc->timestamp.work);
+	/*
+	 * There is a race with suspend flow where the worker runs after suspend
+	 * and causes an unclaimed register access warning. Cancel the worker
+	 * synchronously here.
+	 */
+	cancel_delayed_work_sync(&guc->timestamp.work);
 
 	/*
 	 * Before parking, we should sample engine busyness stats if we need to.
-- 
2.25.1