Re: Patch: linux-2.5.8-pre1/kernel/exit.c change caused BUG() atboot

[Andrew Morton]

Robert Love wrote:
> 
> ...
> This allows us to preempt tasks in any state, without problems or
> special cases.  It also wasn't too much overhead - compared to now,
> basically just:
> 
>         if (unlikely(current->preempt_count() & PREEMPT_ACTIVE))
>                 goto pick_next_task;
> 
> at the top of schedule().
> 

That's changing schedule().  Seems that I'd ruled out that
option prematurely.  As current->preempt_count() and PREEMPT_ACTIVE
can both evaluate to constant zero if CONFIG_PREEMPT=n, it can
be done ifdeflessly.

Everything happens inside rq->lock.  Looks solid to me.

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