drm/xe/guc: Synchronize Dead CT worker with unbind

Cancel and wait for any Dead CT worker to complete before continuing
with device unbinding. Else the worker will end up using resources freed
by the undind operation.

Cc: Zhanjun Dong <[email protected]>
Fixes: d2c5a5a ("drm/xe/guc: Dead CT helper")
Signed-off-by: Balasubramani Vivekanandan <[email protected]>
Reviewed-by: Stuart Summers <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Lucas De Marchi <[email protected]>
(cherry picked from commit 4926713)
Signed-off-by: Lucas De Marchi <[email protected]>

Author: baluvivek

drivers/gpu/drm/xe/xe_guc_ct.c

@@ -200,6 +200,9 @@ static void guc_ct_fini(struct drm_device *drm, void *arg)
 {
 	struct xe_guc_ct *ct = arg;
 
+#if IS_ENABLED(CONFIG_DRM_XE_DEBUG)
+	cancel_work_sync(&ct->dead.worker);
+#endif
 	ct_exit_safe_mode(ct);
 	destroy_workqueue(ct->g2h_wq);
 	xa_destroy(&ct->fence_lookup);