Re: [RFC PATCH 5/8] irq_work: Make self-IPIs optable

Peter Zijlstra
2012-10-22T10:42:34Z

On Sat, 2012-10-20 at 12:22 -0400, Frederic Weisbecker wrote:
> + if (empty) {
> + /*
> + * If an IPI is requested, raise it right away. Otherwise wait
> + * for the next tick unless it's stopped. Now if the arch uses
> + * some other obscure way than IPI to raise an irq work, just raise
> + * and don't think further.
> + */
> + if (ipi || !arch_irq_work_has_ipi() || tick_nohz_tick_stopped())
> + arch_irq_work_raise();
> + }
> preempt_enable();
> }

Doesn't this have a problem where we enqueue the first lazy and then one
with ipi? In that case it appears we won't send the IPI because the
queue wasn't empty.