Re: [Xen-devel] [PATCH] x86/MSI: fix guest unmasking when handling IRQ via event channel

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 08/07/2015 11:55, Jan Beulich wrote:
> > > > On 08.07.15 at 11:07, <julien.grall@xxxxxxxxxx> wrote:
> > On 08/07/2015 09:56, Jan Beulich wrote:
> > > --- a/xen/include/asm-arm/irq.h
> > > +++ b/xen/include/asm-arm/irq.h
> > > @@ -47,6 +47,8 @@ int release_guest_irq(struct domain *d,
> > >
> > >    void arch_move_irqs(struct vcpu *v);
> > >
> > > +#define arch_evtchn_bind_pirq(d, pirq) ((void)((d) + (pirq)))
> > > +
> > This addition is here in order to ensure that d and pirq are evaluated,
> > right?
> Sure.
>
> > If so, I didn't find it obvious to understand. Why didn't you use a
> > static inline? Or maybe add a comment explicitly say this is not
> > implemented.
> A static inline could be used in this case, yes. But I see no
> significant advantages. As to the comment - it is implemented,
> it's just a no-op. And stating that it is a no-op would be
> redundant with it obviously being so by looking at it.
It's not so obvious as I asked about it.

The first thing I saw was (d) + (pirq) and I though : "Why do we want to 
add a domain with a pirq?". I only see after the (void) and it just 
because I remembered we talked about similar case a year ago.
Having a comment doesn't hurt and help the comprehension.

--
Julien Grall

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