fence_signal_locked — signal completion of a fence
| int fence_signal_locked ( | struct fence * fence ); | 
   Signal completion for software callbacks on a fence, this will unblock
   fence_wait calls and run all the callbacks added with
   fence_add_callback. Can be called multiple times, but since a fence
   can only go from unsignaled to signaled state, it will only be effective
   the first time.
   
Unlike fence_signal, this function must be called with fence->lock held.