Re: [KVM PATCH v10] kvm: add support for irqfd

Michael S. Tsirkin
2009-05-27T13:56:05Z

On Wed, May 20, 2009 at 10:30:49AM -0400, Gregory Haskins wrote:
> +static int
> +kvm_assign_irqfd(struct kvm *kvm, int fd, int gsi)
> +{
> + struct _irqfd *irqfd;
> + struct file *file = NULL;
> + int ret;
> +
> + irqfd = kzalloc(sizeof(*irqfd), GFP_KERNEL);
> + if (!irqfd)
> + return -ENOMEM;
> +
> + irqfd->kvm = kvm;
> + irqfd->gsi = gsi;
> + INIT_LIST_HEAD(&irqfd->list);
> + INIT_WORK(&irqfd->work, irqfd_inject);
> +
> + /*
> + * Embed the file* lifetime in the irqfd.
> + */
> + file = fget(fd);
> + if (IS_ERR(file)) {
> + ret = PTR_ERR(file);
> + goto fail;
> + }

So we get a reference to a file, and unless the user is nice to us, it
will only be dropped when kvm char device file is closed?
I think this will deadlock if the fd in question is the open kvm char device.

--
MST