Re: x86: Inconsistent xAPIC synchronization in arch_irq_work_raise?

From: Peter Zijlstra
Date: Thu Jan 23 2014 - 14:12:11 EST

On Thu, Jan 23, 2014 at 07:51:40PM +0100, Jan Kiszka wrote:
> Next we have x86's arch_irq_work_raise which does wait-write-wait,
> either by chance or in order to work around a missing atomicity of
> wait+write somewhere else. Preemption is off, interrupts remain on.

Note that arch_irq_work_raise() is 'special' in that its used from NMI
context, so no amount of interrupts disabling will serialize things.
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