Re: [patch 3/8] x86/apic: Provide apic_ack_irq()

[Dou Liyang]

Hi Thomas,

At 06/05/2018 07:41 PM, Thomas Gleixner wrote:
> On Tue, 5 Jun 2018, Dou Liyang wrote:
> > > +{
> > > +	if (unlikely(irqd_is_setaffinity_pending(irqd)))
> >
> > Affinity pending is also judged in
> >
> > > +		irq_move_irq(irqd);
> >
> > If we can remove the if(...) statement here
>
> That requires to fix all call sites in ia64 and that's why I didn't.  But

I didn't express clearly, I meant remove the if(...) statement from
apic_ack_irq(), it doesn't require to fix the call sites in ia64.

+void apic_ack_irq(struct irq_data *irqd)
+{
+	irq_move_irq(irqd);
+	ack_APIC_irq();
+}

BTW, If apic_ack_irq() can accept _any_ irq_dataÂwhen hierarchical
irqdomains are enabled[1]? If it is true, If there is a situation in
the original code that we should avoid:

 If the top-level irq_data has the IRQD_SETAFFINITY_PENDING state, but
  non-top-level irq_data state not, when using non-top-level irq_data in
  apic_ack_irq(), we may skip the irq_move_irq() which we should call.

[1] commit 77ed42f18edd("genirq: Prevent crash in irq_move_irq()")

> we can make irq_move_irq() an inline function and have the check in the
> inline.

I don't know why do we need to make irq_move_irq() an inline function.

And, yes, irq_move_irq() has already had the check

        ...
  	if (likely(!irqd_is_setaffinity_pending(idata)))
		return;
        ...

Thanks,
	dou