Our other backends return an actual error value upon failure. Do the
same for stolen objects, which currently just return NULL on failure.
Signed-off-by: NCQ Tang <cq.tang@intel.com>
Signed-off-by: NMatthew Auld <matthew.auld@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20191004170452.15410-2-matthew.auld@intel.com