On Fri, 26 Sep 2014 16:45:38 +0800
<arei.gong...@huawei.com> wrote:
> From: Gonglei <arei.gong...@huawei.com>
>
> virtio-$device-{pci, s390, ccw} all duplicate the
> qdev properties of their virtio child. This approach does
> not work well with string or pointer properties since we
> must be careful about leaking or double-freeing them.
>
> Use the QOM alias property to forward property accesses to the
> VirtIORNG child. This way no duplication is necessary.
>
> For their child, object_initialize() leaves the object with a refcount of 1.
> object_property_add_child() adds its own reference which is dropped
> again when the property is deleted.
>
> The upshot of this is that we always have a refcount >= 1. Upon hot
> unplug the virtio-$device child is not finalized!
>
> Drop our reference after the child property has been added to the
> parent.
>
> Attention please:
> As Michael's comments, the patches will introduce regresion about
> "-device FOO,help", which had been fixed by my other patch series:
> [PATCH v2 0/7] add description field in ObjectProperty and PropertyInfo
> struct
> http://lists.nongnu.org/archive/html/qemu-devel/2014-09/msg04908.html
>
> Acknowledgements:
> I copied Stefan's commit c5d49db message about virtio-blk which
> summarized reasons very well, I cannot agree more with him.
> Holp Stefan do not mind, thanks!
>
> Please review, Thanks a lot!
Do you have a git branch for quick testing?
> -Gonglei
>
> Gonglei (9):
> virtio-net: use aliases instead of duplicate qdev properties
> virtio: fix virtio-net child refcount in transports
> virtio/vhost scsi: use aliases instead of duplicate qdev properties
> virtio/vhost-scsi: fix virtio-scsi/vhost-scsi child refcount in
> transports
> virtio-serial: use aliases instead of duplicate qdev properties
> virtio-serial: fix virtio-serial child refcount in transports
> virtio-rng: use aliases instead of duplicate qdev properties
> virtio-rng: fix virtio-rng child refcount in transports
> virtio-balloon: fix virtio-balloon child refcount in transports
>
> hw/s390x/s390-virtio-bus.c | 16 ++++++++++------
> hw/s390x/virtio-ccw.c | 18 +++++++++++-------
> hw/virtio/virtio-pci.c | 18 +++++++++++-------
> 3 files changed, 32 insertions(+), 20 deletions(-)
One thing I noticed is that the various devices end up with similar
code in the end:
object_initialize(&dev->vdev, sizeof(dev->vdev), TYPE_WHATEVER);
object_property_add_child(obj, "virtio-backend", OBJECT(&dev->vdev), NULL);
object_unref(OBJECT(&dev->vdev));
qdev_alias_all_properties(DEVICE(&dev->vdev), obj);
Would it make sense to add a helper function for that?
