On Tue, 2012-07-17 at 13:21 +0300, Michael S. Tsirkin wrote:
> 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.
Holding a reference and using it as a reference count are not the same
thing. What if another module holds a reference to this eventfd? How
do we do anything on release?
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