Messages in this thread | | | Date | Fri, 25 Apr 2008 13:08:22 +0200 | From | Pavel Machek <> | Subject | Re: [PATCH 1/11] Add generic helpers for arch IPI function calls |
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Hi!
>> Something like this will close the window to right up until the point >> where the other CPUs have 'almost' called halt(). >> >> diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c >> index 5398385..94ec9bf 100644 >> --- a/arch/x86/kernel/smp.c >> +++ b/arch/x86/kernel/smp.c >> @@ -155,8 +155,9 @@ static void stop_this_cpu(void *dummy) >> /* >> * Remove this CPU: >> */ >> - cpu_clear(smp_processor_id(), cpu_online_map); >> disable_local_APIC(); >> + cpu_clear(smp_processor_id(), cpu_online_map); >> + smp_wmb(); >> if (hlt_works(smp_processor_id())) >> for (;;) halt(); >> for (;;); >> @@ -175,6 +176,12 @@ static void native_smp_send_stop(void) >> local_irq_save(flags); >> smp_call_function(stop_this_cpu, NULL, 0, 0); >> + >> + while (cpus_weight(cpu_online_map) > 1) { >> + cpu_relax(); >> + smp_rmb(); >> + } >> + >> disable_local_APIC(); >> local_irq_restore(flags); >> } > .. > > Yup, that looks like it oughta work consistently. > Now we just need to hear from some of the folks who > have danced around this code in the past. > > (added Pavel & Rafael to Cc:).
I can't see anything wrong with this one, but I'm not smp expert... Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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