This reverts commit 
0aedb1626566efd72b369c01992ee7413c82a0c5.
I messed things up while applying [1] to drm-intel-fixes. Rectify.
[1] http://mid.gmane.org/
1432827156-9605-1-git-send-email-ville.syrjala@linux.intel.com
Fixes: 0aedb1626566 ("drm/i915: Don't skip request retirement if the active list is empty")
Cc: stable@vger.kernel.org
Acked-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
 void
 i915_gem_retire_requests_ring(struct intel_engine_cs *ring)
 {
+       if (list_empty(&ring->request_list))
+               return;
+
        WARN_ON(i915_verify_lists(ring->dev));
 
        /* Retire requests first as we use it above for the early return.