[PATCH 23/24] drm/syncobj: Don't take locks in drm_syncobj_free

[Jason Ekstrand]

drm_syncobj_put() can potentially happen in weird places and, when we
call drm_syncobj_replace_fence(), it takes the syncobj lock which may
not be valid.  It's safer if we hand-roll the put and don't take any
locks.

Signed-off-by: Jason Ekstrand <jason at jlekstrand.net>
---
 drivers/gpu/drm/drm_syncobj.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
index fdd2ec87cdd14..a0e3b67e9546c 100644
--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -462,7 +462,9 @@ void drm_syncobj_free(struct kref *kref)
 	struct drm_syncobj *syncobj = container_of(kref,
 						   struct drm_syncobj,
 						   refcount);
-	drm_syncobj_replace_fence(syncobj, NULL);
+	dma_fence_put(rcu_dereference_protected(syncobj->fence,
+						lockdep_is_held(&syncobj->lock)));
+	WARN_ON(!list_empty(&syncobj->cb_list));
 	kfree(syncobj);
 }
 EXPORT_SYMBOL(drm_syncobj_free);
-- 
2.31.1