[PATCH v6 2/4] drm/xe/xe_guc_submit: Fix exec queue stop race condition

[Jonathan Cavitt]

Reorder the xe_sched_tdr_queue_imm and set_exec_queue_banned calls in
guc_exec_queue_stop.  This prevents a possible race condition between
the two events in which it's possible for xe_sched_tdr_queue_imm to
wake the ufence waiter before the exec queue is banned, causing the
ufence waiter to miss the banned state.

Suggested-by: Matthew Brost <matthew.brost at intel.com>
Signed-off-by: Jonathan Cavitt <jonathan.cavitt at intel.com>
Reviewed-by: Matthew Brost <matthew.brost at intel.com>
Reviewed-by: Stuart Summers <stuart.summers at intel.com>
---

v2: Expand on cause of race condition

 drivers/gpu/drm/xe/xe_guc_submit.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/xe/xe_guc_submit.c b/drivers/gpu/drm/xe/xe_guc_submit.c
index ecd1085619b30..09331dc41ebdb 100644
--- a/drivers/gpu/drm/xe/xe_guc_submit.c
+++ b/drivers/gpu/drm/xe/xe_guc_submit.c
@@ -1428,8 +1428,8 @@ static void guc_exec_queue_stop(struct xe_guc *guc, struct xe_exec_queue *q)
 			    !xe_sched_job_completed(job)) ||
 			    xe_sched_invalidate_job(job, 2)) {
 				trace_xe_sched_job_ban(job);
-				xe_sched_tdr_queue_imm(&q->guc->sched);
 				set_exec_queue_banned(q);
+				xe_sched_tdr_queue_imm(&q->guc->sched);
 			}
 		}
 	}
-- 
2.25.1