Re: RCU question

[Manfred Spraul]

Andrea Arcangeli wrote:

> On Sun, Dec 12, 2004 at 09:59:00AM +0100, Manfred Spraul wrote:
>  
>
> > It means that our NMI irq return path should check if it points to a hlt 
> > instruction and if yes, then increase the saved EIP by one before doing 
> > the iretd, right?
> >    
>
> I don't think we'll ever post any event through nmi, so it doesn't
> matter. We only care to be waken by real irqs, not nmi/smi. Idle loop is
> fine to ignore the actions of the nmi handlers and to hang into the
> "hlt".
>  
No, You misunderstood the problem:

sti
** NMI handler
** normal interrupt arrives, is queued by the cpu
** irqd from NMI handler
** cpu notices the normal interrupt, handles it.
** normal interrupt does a wakeup, schedules a tasklet, whatever
** irqd from normal interupt
hlt << cpu sleeps.

Thus: lost wakeup.

--
   Manfred
**
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