[Qemu-devel] [PATCH v2 0/7] virtio-blk: use alias properties in transport devices

[Stefan Hajnoczi <stefanha@redhat.com>]

v2:
  * Add qdev_alias_all_properties() instead of virtio-blk-specific function [Paolo]
  * Explain refcount handling in doc comment [Paolo]
  * Fix "property" duplicate typo [Peter Crosthwaite]
  * Add "the same object or" to clarify commit description [Igor]

Thanks for the feedback on the RFC.  This time around the alias property is
implemented at the QOM property level instead of at the qdev property level.

Note that this series only addresses virtio-blk.  In later series we can
convert virtio net, scsi, rng, and serial.

The virtio transport/device split is broken as follows:

1. The virtio-blk device is never finalized because the transport devices
   (virtio-blk-pci and friends) leak the refcount.

2. If we fix the refcount leak then we double-free the 'serial' string property
   upon hot unplug since its char* is copied into the virtio-blk device which
   has an identical 'serial' qdev property.

This series solves both of these problems as follows:

1. Introduce a QOM alias property that lets the transport device forward
   property accesses into the virtio device (the child).

2. Use alias properties in transport devices, instead of keeping a duplicate
   copy of the VirtIOBlkConf struct.

3. Fix the virtio-blk device refcount leak.  It's now safe to do this since the
   double-free has been resolved.

Tested that hotplug/hotunplug of virtio-blk-pci still works.

Stefan Hajnoczi (7):
  qom: add object_property_add_alias()
  virtio-blk: avoid qdev property definition duplication
  virtio-blk: move x-data-plane qdev property to virtio-blk.h
  virtio-blk: use aliases instead of duplicate qdev properties
  virtio-blk: drop virtio_blk_set_conf()
  virtio: fix virtio-blk child refcount in transports
  virtio-blk: move qdev properties into virtio-blk.c

 hw/block/virtio-blk.c          | 18 +++++++++------
 hw/core/qdev.c                 | 19 +++++++++++++++
 hw/s390x/s390-virtio-bus.c     | 10 ++------
 hw/s390x/s390-virtio-bus.h     |  1 -
 hw/s390x/virtio-ccw.c          |  7 ++----
 hw/s390x/virtio-ccw.h          |  1 -
 hw/virtio/virtio-pci.c         |  7 ++----
 hw/virtio/virtio-pci.h         |  1 -
 include/hw/qdev-properties.h   |  2 ++
 include/hw/virtio/virtio-blk.h | 19 ---------------
 include/qom/object.h           | 20 ++++++++++++++++
 qom/object.c                   | 52 ++++++++++++++++++++++++++++++++++++++++++
 12 files changed, 110 insertions(+), 47 deletions(-)

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1.9.0