From: Philipp Stanner Date: Fri, 7 Nov 2025 13:57:01 +0000 (+0100) Subject: drm/todo: Add entry for unlocked drm/sched rq readers X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=439be5c580e553c8777d5533db5892e773f81d40;p=thirdparty%2Fkernel%2Flinux.git 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 Signed-off-by: Philipp Stanner Link: https://patch.msgid.link/20251107135701.244659-4-phasta@kernel.org --- diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst index 572a5611dd0ca..22487ac1b0112 100644 --- a/Documentation/gpu/todo.rst +++ b/Documentation/gpu/todo.rst @@ -909,6 +909,20 @@ Contact: Christian König 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 + +Level: Intermediate + Outside DRM ===========