drm/i915: Skip allocating shadow batch for 0-length batches
Since
commit
17cabf571e50677d980e9ab2a43c5f11213003ae
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date: Wed Jan 14 11:20:57 2015 +0000
drm/i915: Trim the command parser allocations
we may then try to allocate a zero-sized object and attempt to extract
its pages. Understandably this fails.
Testcase: igt/gem_exec_nop #ivb,byt,hsw
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>