Re: [Qemu-devel] [PATCH 00/11] virtio: cleanup and fix hot-unplug

[Michael S. Tsirkin]

On Tue, Oct 08, 2013 at 07:02:44PM +0200, Paolo Bonzini wrote:
> Il 20/09/2013 16:57, Paolo Bonzini ha scritto:
> > This series fixes hot-unplug of virtio devices, which can crash due to
> > dangling pointer accesses.
> > 
> > The current implementation supports guest-initiated hot-unplug via the
> > virtio_bus_destroy_device function, but not hot-unplugging the virtio
> > device by virtue of unplugging its parent container device.
> > 
> > The problem is that the callback for the bus implementation to cleanup
> > is placed in the wrong place; it is in virtio_bus_destroy_device, which
> > should be called by the bus, instead of being somewhere in device code.
> > We need to have the callback in device code (for example in dc->exit),
> > so that we invoke it on every unplug action, no matter who starts it.
> > 
> > Thus, the series cleans up plugging and unplugging of virtio devices
> > so that it does not need any help from the bus (patches 1-4).  It then
> > stops the virtio devices' overriding of dc->exit, moving their cleanup
> > code to the new exit callback in VirtioDeviceClass (patches 5-10).
> > Finally, patch 11 can make virtio-pci implement the device_unplugged
> > callback.
> > 
> > Something similar is probably needed in virtio-ccw too.  However,
> > virtio-ccw needs more surgery because it does not include a device_plugged
> > callback either, so I did not touch it.
> 
> Michael, I prepared a rebase of
> http://permalink.gmane.org/gmane.comp.emulators.qemu/225985 on top of
> these patches and sent it to Andreas.  My understanding is that he will
> send them to qemu-devel.
> 
> Let me know if you want to handle these patches yourself, or I can send
> a pull request for both directly with your Acked-bys.
> 
> As to review, I think it can be usefully split as follows:
> 
> - 4-10 for Andreas
> 
> - 3 for Alex
> 
> - 2 11 for you
> 
> - 1 for either you or Andreas
> 
> Paolo

OK so I can merge this but need Acks from Alex and Andreas, right?

> > 
> > Paolo Bonzini (11):
> >   virtio-bus: remove vdev field
> >   virtio-pci: remove vdev field
> >   virtio-ccw: remove vdev field
> >   virtio-bus: cleanup plug/unplug interface
> >   virtio-blk: switch exit callback to VirtioDeviceClass
> >   virtio-serial: switch exit callback to VirtioDeviceClass
> >   virtio-net: switch exit callback to VirtioDeviceClass
> >   virtio-scsi: switch exit callback to VirtioDeviceClass
> >   virtio-balloon: switch exit callback to VirtioDeviceClass
> >   virtio-rng: switch exit callback to VirtioDeviceClass
> >   virtio-pci: add device_unplugged callback
> > 
> >  hw/block/virtio-blk.c           |  10 ++--
> >  hw/char/virtio-serial-bus.c     |  10 ++--
> >  hw/net/virtio-net.c             |  11 ++--
> >  hw/s390x/virtio-ccw.c           |  80 +++++++++++++++------------
> >  hw/s390x/virtio-ccw.h           |   1 -
> >  hw/scsi/vhost-scsi.c            |  11 ++--
> >  hw/scsi/virtio-scsi.c           |  15 +++--
> >  hw/virtio/virtio-balloon.c      |  10 ++--
> >  hw/virtio/virtio-bus.c          |  81 +++++++++++++++------------
> >  hw/virtio/virtio-mmio.c         |   9 +--
> >  hw/virtio/virtio-pci.c          | 119 
> > ++++++++++++++++++++++++----------------
> >  hw/virtio/virtio-pci.h          |   1 -
> >  hw/virtio/virtio-rng.c          |  10 ++--
> >  hw/virtio/virtio.c              |   7 ++-
> >  include/hw/virtio/virtio-bus.h  |  22 +++++---
> >  include/hw/virtio/virtio-scsi.h |   2 +-
> >  include/hw/virtio/virtio.h      |   1 +
> >  17 files changed, 223 insertions(+), 177 deletions(-)
> >