[PATCH] drm/xe: Make sure scheduler is ready before submission

[Tejas Upadhyay]

Async call to __guc_exec_queue_fini_async frees scheduler
while some scheduler submission would have already started.
To handle such small window race case, submission should only
start when scheduler is ready.

It will help to solve below which is not easily reproducible,
https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/4223

Signed-off-by: Tejas Upadhyay <tejas.upadhyay at intel.com>
---
 drivers/gpu/drm/xe/xe_gpu_scheduler.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/xe/xe_gpu_scheduler.c b/drivers/gpu/drm/xe/xe_gpu_scheduler.c
index 50361b4638f9..42ca3c4a299a 100644
--- a/drivers/gpu/drm/xe/xe_gpu_scheduler.c
+++ b/drivers/gpu/drm/xe/xe_gpu_scheduler.c
@@ -80,6 +80,14 @@ void xe_sched_fini(struct xe_gpu_scheduler *sched)
 
 void xe_sched_submission_start(struct xe_gpu_scheduler *sched)
 {
+	/* Async call to __guc_exec_queue_fini_async frees scheduler
+	 * while some scheduler submission would have already started.
+	 * To handle such small window race case, submission should only
+	 * start when scheduler is ready.
+	 */
+	if (!drm_sched_wqueue_ready(&sched->base))
+		return;
+
 	drm_sched_wqueue_start(&sched->base);
 	queue_work(sched->base.submit_wq, &sched->work_process_msg);
 }
-- 
2.34.1