Re: [PATCH v5 2/4] kvm: KVM_EOIFD, an eventfd for EOIs

From: Michael S. Tsirkin
Date: Tue Jul 17 2012 - 06:21:06 EST


On Mon, Jul 16, 2012 at 02:33:55PM -0600, Alex Williamson wrote:
> + if (args->flags & KVM_EOIFD_FLAG_LEVEL_IRQFD) {
> + struct _irqfd *irqfd = _irqfd_fdget_lock(kvm, args->irqfd);
> + if (IS_ERR(irqfd)) {
> + ret = PTR_ERR(irqfd);
> + goto fail;
> + }
> +
> + gsi = irqfd->gsi;
> + level_irqfd = eventfd_ctx_get(irqfd->eventfd);
> + source = _irq_source_get(irqfd->source);
> + _irqfd_put_unlock(irqfd);
> + if (!source) {
> + ret = -EINVAL;
> + goto fail;
> + }
> + } else {
> + ret = -EINVAL;
> + goto fail;
> + }
> +
> + INIT_LIST_HEAD(&eoifd->list);
> + eoifd->kvm = kvm;
> + eoifd->eventfd = eventfd;
> + eoifd->source = source;
> + eoifd->level_irqfd = level_irqfd;
> + eoifd->notifier.gsi = gsi;
> + eoifd->notifier.irq_acked = eoifd_event;

OK so this means eoifd keeps a reference to the irqfd.
And since this is the case, can't we drop the reference counting
around source ids now? Everything is referenced through irqfd.

--
MST
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