RE: [RFC 12/17] irq: bypass: Extend skeleton for ARM forwarding control

Wu, Feng
2015-07-03T07:16:36Z

> -----Original Message-----
> From: Paolo Bonzini [mailto:pbonzini@redhat.com]
> Sent: Friday, July 03, 2015 3:06 PM
> To: Wu, Feng; Eric Auger; eric.auger@st.com;
> linux-arm-kernel@lists.infradead.org; kvmarm@lists.cs.columbia.edu;
> kvm@vger.kernel.org; christoffer.dall@linaro.org; marc.zyngier@arm.com;
> alex.williamson@redhat.com; avi.kivity@gmail.com; mtosatti@redhat.com;
> joro@8bytes.org; b.reynal@virtualopensystems.com
> Cc: linux-kernel@vger.kernel.org; patches@linaro.org
> Subject: Re: [RFC 12/17] irq: bypass: Extend skeleton for ARM forwarding
> control
>
>
>
> On 03/07/2015 09:00, Wu, Feng wrote:
> >>> > > struct irq_bypass_consumer {
> >>> > > struct list_head node;
> >>> > > void *token;
> >>> > > + unsigned irq; /*got from producer when registered*/
> >>> > > void (*add_producer)(struct irq_bypass_producer *,
> >>> > > struct irq_bypass_consumer *);
> >>> > > void (*del_producer)(struct irq_bypass_producer *,
> >>> > > struct irq_bypass_consumer *);
> >>> > > + void (*update)(struct irq_bypass_consumer *);
> >>> > > };
> >>> > >
> >>> > > 'update' is used to update the IRTE, while irq is initialized when
> >>> > > registered, which is used to find the right IRTE.
> >> >
> >> > Feel free to add "update" in your PI patches. I am not sure if "irq"
> >> > belongs here or in the containing struct. You can play with both and
> >> > submit the version that looks better to you.
> > Thanks for your review, Paolo. In my understanding, irq comes from
> > the producer side, while gsi belongs to the consumer, so we need
> > to get the irq from the producer somewhere. I am not sure adding
> > irq here is the good way, but what I need is in the 'update' function,
> > I have irq, gsi in hand. :)
>
> It's difficult to say without seeing the patches... The IRQ is stored
> in the producer already with Eric's changes. If you need to store the
> old IRQ value, because "update" needs to do something with it, then I
> think "irq" belongs in the container struct.
>
> Perhaps "update" needs to have a producer argument as well?

I also consider this method, basically, I will call 'update' in irqfd_update(),
but seems I need do extra things to get the producer structure (such as,
iterate the producer list to find the one with the same 'token') before
calling 'update' from consumer side. I am not sure it is worth doing
that way.

Thanks,
Feng

>
> Paolo