Re: [PATCH v5 2/4] kvm: KVM_EOIFD, an eventfd for EOIs
From: Alex Williamson <hidden>
Date: 2012-07-17 13:59:21
Also in:
lkml
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:quoted
+ 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?