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

[<arei.gonglei@huawei.com>]

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

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