From: George Anzinger <george@mvista.com>
To: Manfred Spraul <manfred@colorfullife.com>
Cc: Zwane Mwaikambo <zwane@arm.linux.org.uk>,
Lee Revell <rlrevell@joe-job.com>,
dipankar@in.ibm.com, ganzinger@mvista.com,
lkml <linux-kernel@vger.kernel.org>
Subject: Re: RCU question
Date: Sat, 11 Dec 2004 08:52:02 -0800 [thread overview]
Message-ID: <41BB25B2.90303@mvista.com> (raw)
In-Reply-To: <41BB2108.70606@colorfullife.com>
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/
next prev parent reply other threads:[~2004-12-11 16:52 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-12-09 23:59 RCU question George Anzinger
2004-12-10 4:31 ` Dipankar Sarma
2004-12-10 19:42 ` George Anzinger
2004-12-10 20:40 ` Dipankar Sarma
2004-12-10 20:45 ` Lee Revell
2004-12-10 21:02 ` George Anzinger
2004-12-10 22:58 ` Zwane Mwaikambo
2004-12-11 2:22 ` George Anzinger
2004-12-11 2:45 ` Zwane Mwaikambo
2004-12-11 3:29 ` George Anzinger
2004-12-11 14:52 ` Zwane Mwaikambo
2004-12-11 16:32 ` Manfred Spraul
2004-12-11 16:52 ` George Anzinger [this message]
2004-12-12 2:53 ` Zwane Mwaikambo
2004-12-12 8:59 ` Manfred Spraul
2004-12-12 9:37 ` Andrea Arcangeli
2004-12-12 10:22 ` Manfred Spraul
2004-12-12 12:15 ` Andrea Arcangeli
2004-12-14 21:40 ` Lee Revell
2004-12-14 22:23 ` [patch, 2.6.10-rc3] safe_hlt() & NMIs Ingo Molnar
2004-12-14 22:47 ` Ingo Molnar
2004-12-14 23:09 ` Linus Torvalds
2004-12-15 8:52 ` Ingo Molnar
2004-12-15 15:44 ` Linus Torvalds
2004-12-15 16:35 ` Ingo Molnar
2004-12-16 0:37 ` Alan Cox
2004-12-16 1:58 ` Linus Torvalds
2004-12-16 14:51 ` Ingo Molnar
2004-12-16 15:08 ` Maciej W. Rozycki
2004-12-16 15:11 ` Ingo Molnar
2004-12-16 15:42 ` Maciej W. Rozycki
2004-12-16 15:54 ` Linus Torvalds
2004-12-16 2:10 ` Zwane Mwaikambo
2004-12-16 13:26 ` Alan Cox
2004-12-14 23:41 ` Andrea Arcangeli
2004-12-14 23:00 ` Linus Torvalds
2004-12-15 5:04 ` Andi Kleen
2004-12-15 6:27 ` Avi Kivity
2004-12-15 8:51 ` Ingo Molnar
2004-12-12 16:51 ` RCU question George Anzinger
2004-12-12 22:40 ` Manfred Spraul
2004-12-13 5:22 ` George Anzinger
2004-12-12 16:26 ` Zwane Mwaikambo
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