"Michael S. Tsirkin" <m...@redhat.com> writes:
> On Mon, Jul 20, 2020 at 05:07:08PM +0200, Markus Armbruster wrote:
>> What is the intended purpose of object_property_set_link() in
>>
>> static void virtio_rng_pci_realize(VirtIOPCIProxy *vpci_dev, Error
>> **errp)
>> {
>> VirtIORngPCI *vrng = VIRTIO_RNG_PCI(vpci_dev);
>> DeviceState *vdev = DEVICE(&vrng->vdev);
>>
>> if (!qdev_realize(vdev, BUS(&vpci_dev->bus), errp)) {
>> return;
>> }
>>
>> object_property_set_link(OBJECT(vrng), "rng",
>> OBJECT(vrng->vdev.conf.rng),
>> NULL);
>> }
>>
>> ?
>>
>> I'm asking because the function *always* fails. I believe it's been
>> failing for years.
>>
>> Similar code in the CCW buddy. Also virtio-crypto-pci and
>> virtio-crypto-ccw link "cryptodev".
>>
>> I tried moving it before qdev_realize(), where it doesn't fail. But
>> then *I* fail, namely at finding any effect in QOM.
>
> I suspect that's because there's already a link with that name
> created by virtio core. Is that right?
Looks like it, in virtio_rng_device_realize():
if (vrng->conf.rng == NULL) {
... make up @default_backend ...
object_property_set_link(OBJECT(dev), "rng", default_backend,
&error_abort);
}
The object_property_set_link actually sets vrng->vdev.conf.rng (but it
takes quite some digging to see that; MICAHI[*] at work).
For virtio-crypto, the link is vcrypto->vdev.conf.cryptodev.
virtio_crypto_pci_realize() first checks its already set:
if (vcrypto->vdev.conf.cryptodev == NULL) {
error_setg(errp, "'cryptodev' parameter expects a valid object");
return;
}
>> If it's really useless, I'll send a patch to drop it.
All four are useless; will send patches.
>> If it has a use, tell me more, so I can test my patch to move it.
Thanks!
[*] Make It Complicated And Hide It.
