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SubjectRe: RCU question
Manfred Spraul wrote:
> 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.

Exactly :)

--
George Anzinger george@mvista.com
High-res-timers: http://sourceforge.net/projects/high-res-timers/

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