Just one more thing.

On 07/26/2010 06:05 PM, Tejun Heo wrote:

* Placing try_to_freeze() could be a bit annoying.  It shouldn't be
  executed when there's a work to flush.

* Similar issue exists for kthread_stop().  The kthread shouldn't exit
  while there's a work to flush (please note that kthread_worker
  interface allows detaching / attaching worker kthread during
  operation, so it should remain in consistent state with regard to
  flushing).

Thanks.

-- 
tejun