Runqueues are currently almost everywhere being read unlocked in drm/sched. At XDC 2025, the assembled developers were unsure whether that's legal and whether it can be fixed. Someone should find out.
Add a todo entry for the unlocked runqueue reader problem. Signed-off-by: Philipp Stanner <[email protected]> --- Documentation/gpu/todo.rst | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst index 084e148e78c1..fc8bafd593d8 100644 --- a/Documentation/gpu/todo.rst +++ b/Documentation/gpu/todo.rst @@ -909,6 +909,20 @@ Contact: Christian König <[email protected]> Level: Advanced +Add locking for runqueues +------------------------- + +There is an old FIXME by Sima in include/drm/gpu_scheduler.h. It details that +struct drm_sched_rq is read at many places without any locks, not even with a +READ_ONCE. At XDC 2025 no one could really tell why that is the case, whether +locks are needed and whether they could be added. (But for real, that should +probably be locked!). Check whether it's possible to add locks everywhere, and +do so if yes. + +Contact: Philipp Stanner <[email protected]> + +Level: Intermediate + Outside DRM =========== -- 2.49.0
