Re: [Xen-devel] [PATCH] Make bind_interdomain_evtchn_to_irq() public

[Juergen Gross]

On 08/13/2014 11:29 AM, David Vrabel wrote:
> On 12/08/14 14:43, jgross@xxxxxxxx wrote:
> > From: Juergen Gross <jgross@xxxxxxxx>
> >
> > bind_interdomain_evtchn_to_irq() is currently a private function. It is used
> > only by bind_interdomain_evtchn_to_irqhandler() to register an irq-handler for
> > an event channel.
> >
> > By making it public it is possible to use e.g. threaded interrupts with
> > interdomain event channels.
>
> Can you give an example of using this?  Maybe we want a
> bind_interdomain_evtchn_to_threaded_irqhandler() instead? Or add a flags
> field to the existing function.

Instead of

static int scsiback_schedule(void *data)
{
       struct vscsibk_info *info = (struct vscsibk_info *)data;

       while (!kthread_should_stop()) {
               wait_event_interruptible(info->wq,
                       info->waiting_reqs || kthread_should_stop());

               info->waiting_reqs = 0;
               smp_mb();       /* waiting_reqs used by other thread */

               switch (scsiback_do_cmd_fn(info)) {
               case 1:
                       info->waiting_reqs = 1;
               default:
                       break;
               }
               cond_resched();
       }
       return 0;
}

static void scsiback_notify_work(struct vscsibk_info *info)
{
       info->waiting_reqs = 1;
       wake_up(&info->wq);
}

static irqreturn_t scsiback_intr(int irq, void *dev_id)
{
       scsiback_notify_work((struct vscsibk_info *)dev_id);
       return IRQ_HANDLED;
}

static int scsiback_init_sring(struct vscsibk_info *info, grant_ref_t 
ring_ref,
                       evtchn_port_t evtchn)
{
...
       bind_interdomain_evtchn_to_irqhandler(
                       info->domid, evtchn,
                       scsiback_intr, 0, "vscsiif-backend", info);

...
       info->kthread = kthread_run(scsiback_schedule, info, name);
...
}


I only need the following:

static irqreturn_t scsiback_irq_fn(int irq, void *dev_id)
{
        struct vscsibk_info *info = dev_id;

        while (scsiback_do_cmd_fn(info))
                cond_resched();

        return IRQ_HANDLED;
}

static int scsiback_init_sring(struct vscsibk_info *info, grant_ref_t 
ring_ref,
                        evtchn_port_t evtchn)
{
...
        irq = bind_interdomain_evtchn_to_irq(info->domid, evtchn);
        request_threaded_irq(irq, NULL, scsiback_irq_fn,
                             IRQF_ONESHOT, "vscsiif-backend", info)
...
}


So yes, it could be done via a flag, too.

Juergen
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