lkml.org 
[lkml]   [2012]   [Jul]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v5 2/4] kvm: KVM_EOIFD, an eventfd for EOIs
On Tue, Jul 17, 2012 at 07:59:16AM -0600, Alex Williamson wrote:
> 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?

We don't as there is no release, and using kref on source id does not
help: it just never gets invoked.

--
MST



\
 
 \ /
  Last update: 2012-07-17 16:41    [from the cache]
©2003-2011 Jasper Spaans