Resend of trivial bits from my scheduler tree...:

        - shift cpu by 1UL not 1 to match type
        - clarify various comments
        - remove the barrier from preempt_schedule.  This was here
          because I used to check need_resched before returning from
          preempt_schedule but we do not now (although should).  The
          barrier insured need_resched and preempt_count were in sync
          now and after an interrupt that could occur.