Messages in this thread | | | Date | Fri, 20 Feb 2015 12:03:03 -0800 | Subject | Re: smp_call_function_single lockups | From | Linus Torvalds <> |
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On Fri, Feb 20, 2015 at 11:41 AM, Ingo Molnar <mingo@kernel.org> wrote: > > I'm not so sure about that aspect: I think disabling IRQs > might be necessary with some APICs (if lower levels don't > disable IRQs), to make sure the 'local APIC busy' bit isn't > set:
Right. But afaik not for the x2apic case, which this is. The x2apic doesn't even have a busy bit, and sending the ipi is a single write,
I agree that when doing other apic implementations, we may need to guarantee atomicity for things like "wait for apic idle, then send the ipi".
Linus
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