Re: [PATCH] drm/syncobj: make lockdep complain on WAIT_FOR_SUBMIT v2

On Mon, Jan 18, 2021 at 07:03:34PM +0100, Christian König wrote:

diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c index 6e74e6745eca..f51458615158 100644 --- a/drivers/gpu/drm/drm_syncobj.c +++ b/drivers/gpu/drm/drm_syncobj.c @@ -387,6 +387,13 @@ int drm_syncobj_find_fence(struct drm_file *file_private, if (!syncobj) return -ENOENT;

• /* Waiting for userspace with locks help is illegal cause that can

• * trivial deadlock with page faults for example. Make lockdep complain
  

• * about it early on.
  

• */
  

Egads, the cursed comment style is spreading :/

• if (flags & DRM_SYNCOBJ_WAIT_FLAGS_WAIT_FOR_SUBMIT)

• lockdep_assert_none_held_once();
  

Should this not be part of drm_syncobj_fence_add_wait() instead? Also, do you want to sprinkle might_sleep() around ?

*fence = drm_syncobj_fence_get(syncobj); drm_syncobj_put(syncobj);

diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h