[RFC PATCH v3 0/3] Querying errors from drm_syncobj

[Yicong Hui <yiconghui@gmail.com>]

This patch series adds 2 new flags, DRM_SYNCOBJ_QUERY_FLAGS_ERROR and
DRM_SYNCOBJ_WAIT_FLAGS_ABORT_ON_ERROR for 3 ioctl operations
DRM_IOCTL_SYNCOBJ_QUERY, DRM_IOCTL_SYNCOBJ_WAIT and
DRM_IOCTL_SYNCOBJ_TIMELINE_WAIT to allow them to batch-request error
codes from multiple syncobjs and abort early upon error of any of them.

Based on discussions from Michel Dänzer and Christian König, and a
starter task from the DRM todo documentation.

See https://gitlab.gnome.org/GNOME/mutter/-/issues/4624 for discussions
on userspace implementation.

I have looked into adding sub test cases into syncobj_wait.c and
syncobj_timeline.c, igt-tests for this and I think I understand the 
process for writing tests and submitting them, however, these ioctls 
only trigger in the case that there is an error, but I am not sure what
is the best way to artifically trigger an error from userspace in order
to test that these ioctl flags work. What's the recommended way to 
approach this?

---
Changes:
v3:
* Fixed inline comments by converting to multi-line comments in
accordance to kernel style guidelines.
* No longer using a separate superfluous function to walk the fence
chain, and instead queries the last signaled fence in in the chain for
its error code
* Fixed types for error and handles array.
* Used dma_fence_get_status to query error instead of getting it
directly.

v2:
https://lore.kernel.org/dri-devel/20260220022631.2205037-1-yiconghui@gmail.com/T/#m6ab4f94a19c769193895d7728383f84e452cbbfa
* Went from adding a new ioctl to implementing flags for existing
ones.

v1:
* https://lore.kernel.org/all/20260213120836.81283-1-yiconghui@gmail.com/T/#mfdbc7f97e91ca5731b51b69c8cf8173cb0b2fb3e

Yicong Hui (3):
  drm/syncobj: Add flag DRM_SYNCOBJ_QUERY_FLAGS_ERROR to query errors
  drm/syncobj: Add DRM_SYNCOBJ_WAIT_FLAGS_ABORT_ON_ERROR ioctl flag
  drm/syncobj/doc: Remove starter task from todo list

 Documentation/gpu/todo.rst    | 16 ------------
 drivers/gpu/drm/drm_syncobj.c | 49 ++++++++++++++++++++++++++++++-----
 include/uapi/drm/drm.h        | 11 ++++++++
 3 files changed, 54 insertions(+), 22 deletions(-)

-- 
2.53.0