On Tue, Dec 08, 2015 at 04:54:57PM +0100, Greg Kurz wrote:
> Since commit 4652f1640e029e1f2433fa77ba6af285 "virtio-9p: add savevm
> handlers",
> if the user hot-unplugs a quiescent 9p device and live migrates, the source
> QEMU crashes before migration completetion... This happens because virtio-9p
> devices have a realize handler which calls virtio_init() and
> register_savevm().
> Both calls store pointers to the device internals, that get dereferenced
> during
> migration even if the device got unplugged.
>
> This patch simply adds an unrealize handler to perform minimal cleanup and
> avoid the crash. Hot unplug of non-quiescent 9p devices is still not supported
> in QEMU, and not supported by linux guests either.
>
> Signed-off-by: Greg Kurz <gk...@linux.vnet.ibm.com>
Reviewed-by: Michael S. Tsirkin <m...@redhat.com>
> ---
> hw/9pfs/virtio-9p-device.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/hw/9pfs/virtio-9p-device.c b/hw/9pfs/virtio-9p-device.c
> index 944b5f5e9fcc..b42d3b30a027 100644
> --- a/hw/9pfs/virtio-9p-device.c
> +++ b/hw/9pfs/virtio-9p-device.c
> @@ -145,6 +145,17 @@ out:
> v9fs_path_free(&path);
> }
>
> +static void virtio_9p_device_unrealize(DeviceState *dev, Error **errp)
> +{
> + VirtIODevice *vdev = VIRTIO_DEVICE(dev);
> + V9fsState *s = VIRTIO_9P(dev);
> +
> + virtio_cleanup(vdev);
> + unregister_savevm(dev, "virtio-9p", s);
> + g_free(s->ctx.fs_root);
> + g_free(s->tag);
> +}
> +
> /* virtio-9p device */
>
> static Property virtio_9p_properties[] = {
> @@ -161,6 +172,7 @@ static void virtio_9p_class_init(ObjectClass *klass, void
> *data)
> dc->props = virtio_9p_properties;
> set_bit(DEVICE_CATEGORY_STORAGE, dc->categories);
> vdc->realize = virtio_9p_device_realize;
> + vdc->unrealize = virtio_9p_device_unrealize;
> vdc->get_features = virtio_9p_get_features;
> vdc->get_config = virtio_9p_get_config;
> }
