DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT can't be used when a reservation
object lock is help or otherwise we can deadlock with page faults.
Make lockdep complain badly about that.
Signed-off-by: Christian König <christian.koenig@xxxxxxx>
---
drivers/gpu/drm/drm_syncobj.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
index 6e74e6745eca..6228e9cd089a 100644
--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -387,6 +387,20 @@ int drm_syncobj_find_fence(struct drm_file *file_private,
if (!syncobj)
return -ENOENT;
+ if (flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT &&
+ IS_ENABLED(CONFIG_LOCKDEP)) {
+ struct dma_resv robj;
+
+ /* Waiting for userspace with a reservation lock help is illegal
+ * cause that can deadlock with page faults. Make lockdep
+ * complain about it early on.
+ */
+ dma_resv_init(&robj);
+ dma_resv_lock(&robj, NULL);
+ dma_resv_unlock(&robj);
+ dma_resv_fini(&robj);
+ }
+
*fence = drm_syncobj_fence_get(syncobj);
drm_syncobj_put(syncobj);
--
2.25.1
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