Re: [PATCH v2 3/4] net/virtio: avoid passing NULL to qdev_set_parent_bus

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

On Wed, Nov 20, 2019 at 03:38:58PM +0100, Jens Freimann wrote:
> Make sure we don't pass NULL to qdev_set_parent_bus(). Also simplify
> code a bit and fix a typo.
> This fixes CID 1407224.
> 
> Fixes: 9711cd0dfc3f ("net/virtio: add failover support")
> Signed-off-by: Jens Freimann <jfreimann@redhat.com>

patch itself is ok I think

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

but some questions on the commit log

> ---
>  hw/net/virtio-net.c | 42 +++++++++++++++++++++++++-----------------
>  1 file changed, 25 insertions(+), 17 deletions(-)
> 
> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index ac4d19109e..78f1e4e87c 100644
> --- a/hw/net/virtio-net.c
> +++ b/hw/net/virtio-net.c
> @@ -2805,25 +2805,33 @@ static bool failover_replug_primary(VirtIONet *n, Error **errp)
>          n->primary_device_opts = qemu_opts_from_qdict(
>                  qemu_find_opts("device"),
>                  n->primary_device_dict, errp);
> -    }
> -    if (n->primary_device_opts) {
> -        if (n->primary_dev) {
> -            n->primary_bus = n->primary_dev->parent_bus;
> -        }
> -        qdev_set_parent_bus(n->primary_dev, n->primary_bus);
> -        n->primary_should_be_hidden = false;
> -        qemu_opt_set_bool(n->primary_device_opts,
> -                "partially_hotplugged", true, errp);
> -        hotplug_ctrl = qdev_get_hotplug_handler(n->primary_dev);
> -        if (hotplug_ctrl) {
> -            hotplug_handler_pre_plug(hotplug_ctrl, n->primary_dev, errp);
> -            hotplug_handler_plug(hotplug_ctrl, n->primary_dev, errp);
> +        if (!n->primary_device_opts) {
> +            error_setg(errp, "virtio_net: couldn't find primary device opts");
> +            goto out;
>          }
> -        if (!n->primary_dev) {
> +    }
> +    if (!n->primary_dev) {
>              error_setg(errp, "virtio_net: couldn't find primary device");
> -        }
> +            goto out;
>      }
> -    return *errp != NULL;
> +
> +    n->primary_bus = n->primary_dev->parent_bus;
> +    if (!n->primary_bus) {
> +        error_setg(errp, "virtio_net: couldn't find primary bus");
> +        goto out;
> +    }
> +    qdev_set_parent_bus(n->primary_dev, n->primary_bus);
> +    n->primary_should_be_hidden = false;
> +    qemu_opt_set_bool(n->primary_device_opts,
> +                      "partially_hotplugged", true, errp);
> +    hotplug_ctrl = qdev_get_hotplug_handler(n->primary_dev);
> +    if (hotplug_ctrl) {
> +        hotplug_handler_pre_plug(hotplug_ctrl, n->primary_dev, errp);
> +        hotplug_handler_plug(hotplug_ctrl, n->primary_dev, errp);
> +    }
> +
> +out:
> +    return *errp == NULL;
>  }
>  
>  static void virtio_net_handle_migration_primary(VirtIONet *n,

So the logic actually was inverted here? Then ... how did this work?
and how was it tested?
Also, pls mention the change in the commit log.

> @@ -2852,7 +2860,7 @@ static void virtio_net_handle_migration_primary(VirtIONet *n,
>              warn_report("couldn't unplug primary device");
>          }
>      } else if (migration_has_failed(s)) {
> -        /* We already unplugged the device let's plugged it back */
> +        /* We already unplugged the device let's plug it back */
>          if (!failover_replug_primary(n, &err)) {
>              if (err) {
>                  error_report_err(err);
> -- 
> 2.21.0