Re: RCU question

[Manfred Spraul]

Zwane Mwaikambo wrote:

> On Fri, 10 Dec 2004, George Anzinger wrote:
>
>  
>
> > That is ok.  Either we have interrupts off and no softirqs are pending and we
> > proceed to the "hlt" (where the interrupt will be taken), or softirqs are
> > pending, we turn interrupts on, do the softirq, turn interrupts off and try
> > again.  Unless some tasklet (RCU?) never "gives up" or we will exit the while
> > with interrupts off and move on to the "hlt".  Or did I miss something?
> >    
>
> But the point is that you cannot execute hlt with interrupts disabled.
>  
The trick is the sti instruction: It enables interrupt processing after 
the following instruction.

Thus
   sti
   hlt

cannot race - it atomically enables interrupts and waits.

--
   Manfred

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