drm/todo: Add entry for unlocked drm/sched rq readers

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.

Acked-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Philipp Stanner <phasta@kernel.org>
Link: https://patch.msgid.link/20251107135701.244659-4-phasta@kernel.org

diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst
index 572a5611dd0ca942dd9e6a9a9954b65f53222b97..22487ac1b01128e86d7b4768cfa4079c0156d2ad 100644 (file)
--- a/Documentation/gpu/todo.rst
+++ b/Documentation/gpu/todo.rst
@@ -909,6 +909,20 @@ Contact: Christian König <christian.koenig@amd.com>
 
 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 <phasta@kernel.org>
+
+Level: Intermediate
+
 Outside DRM
 ===========