[Intel-gfx] [PATCH v5] drm/i915: Avoid circular locking dependency when flush delayed work on gt reset

[Zhanjun Dong]

This attempts to avoid circular locking dependency between flush delayed
work and intel_gt_reset.
When intel_gt_reset was called, task will hold a lock.
To cacel delayed work here, the _sync version will also acquire a lock,
which might trigger the possible cirular locking dependency warning.
When intel_gt_reset called, reset_in_progress flag will be set, add code
to check the flag, call async verion if reset is in progress.

Signed-off-by: Zhanjun Dong <zhanjun.dong at intel.com>
Cc: John Harrison <John.C.Harrison at Intel.com>
Cc: Andi Shyti <andi.shyti at linux.intel.com>
Cc: Daniel Vetter <daniel at ffwll.ch>
---
 drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c | 11 ++++++++++-
 1 file changed, 10 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 a0e3ef1c65d2..600388c849f7 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -1359,7 +1359,16 @@ static void guc_enable_busyness_worker(struct intel_guc *guc)
 
 static void guc_cancel_busyness_worker(struct intel_guc *guc)
 {
-	cancel_delayed_work_sync(&guc->timestamp.work);
+	/*
+	 * When intel_gt_reset was called, task will hold a lock.
+	 * To cacel delayed work here, the _sync version will also acquire a lock, which might
+	 * trigger the possible cirular locking dependency warning.
+	 * Check the reset_in_progress flag, call async verion if reset is in progress.
+	 */
+	if (guc_to_gt(guc)->uc.reset_in_progress)
+		cancel_delayed_work(&guc->timestamp.work);
+	else
+		cancel_delayed_work_sync(&guc->timestamp.work);
 }
 
 static void __reset_guc_busyness_stats(struct intel_guc *guc)
-- 
2.34.1