Re: [Qemu-devel] [PATCH v3 00/12] virtio: fix virtio child recount in transports

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Sep 30, 2014 at 05:49:32PM +0800, arei.gonglei@huawei.com wrote:
> From: Gonglei <arei.gonglei@huawei.com>
> 
> virtio-$device-{pci, s390, ccw} all duplicate the
> qdev properties of their virtio child. This approach does
> not work well with string or pointer properties since we
> must be careful about leaking or double-freeing them.
> 
> Use the QOM alias property to forward property accesses to the
> VirtIO$dev 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.
> 
> Changes since v2:
>  - fix some typos about commit message in PATCH 12 (Cornelia/Paolo)
>  - add 'Reviewed-by' tag

For series:

Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

Paolo, pls feel free to apply this in your tree.

> Thanks for review!
> 
> Changs since v1:
>  - add the same handling for virtio-9p-pci device in PATCH 10 and PATCH 11.
>  - add a wrapper function for better code sharing 
>    in PATCH 12 (Cornelia/Michael/Paolo)
> 
> 
> 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 v4 0/5] add description field in ObjectProperty and PropertyInfo struct
>  http://lists.nongnu.org/archive/html/qemu-devel/2014-09/msg05740.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!
> 
> 
> Gonglei (12):
>   virtio-net: use aliases instead of duplicate qdev properties
>   virtio-net: 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
>   virtio-9p: use aliases instead of duplicate qdev properties
>   virtio-9p: fix virtio-9p child refcount in transports
>   virtio: add a wrapper for virtio-backend initialization
> 
>  hw/s390x/s390-virtio-bus.c | 38 ++++++++++++++++++--------------------
>  hw/s390x/virtio-ccw.c      | 40 +++++++++++++++++++---------------------
>  hw/virtio/virtio-pci.c     | 46 ++++++++++++++++++++++------------------------
>  hw/virtio/virtio.c         | 11 +++++++++++
>  include/hw/virtio/virtio.h |  3 +++
>  5 files changed, 73 insertions(+), 65 deletions(-)
> 
> -- 
> 1.7.12.4
>