drm/core: Fail atomic IOCTL with no CRTC state but with signaling.
authorAndrey Grodzovsky <Andrey.Grodzovsky@amd.com>
Tue, 20 Jun 2017 17:57:06 +0000 (13:57 -0400)
committerMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Wed, 28 Jun 2017 08:00:52 +0000 (10:00 +0200)
commit330c422a8ee88d77407f65494f3bbf141a8d9453
tree3de02eece569b112e8d1bac14ac82b56c4bc91c2
parentb740e76936c14354a9c5676a3eed839ea8472c41
drm/core: Fail atomic IOCTL with no CRTC state but with signaling.

Problem : While running IGT kms_atomic_transition test suite i encountered
a hang in drmHandleEvent immediately following  an atomic_commit.
After dumping the atomic state I relized that in this case there was
not even one CRTC attached to the state and only disabled
planes. This probably due to a commit which hadn't changed any property
which would require attaching crtc state. This means drmHandleEvent
will never wake up from read since without CRTC in atomic state
the event fd will not be signaled.

Fix: Protect against this issue by failing atomic_commit early in
drm_mode_atomic_commit where such probelm can be identified.

v2:
Fix typos and extra newlines.

Change-Id: I3ee28ffae35fd1e8bfe553146c44da53da02e6f8
Signed-off-by: Andrey Grodzovsky <Andrey.Grodzovsky@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1497981426-27203-1-git-send-email-Andrey.Grodzovsky@amd.com
drivers/gpu/drm/drm_atomic.c