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

[Jens Freimann]

On Wed, Nov 20, 2019 at 10:04:01AM -0500, Michael S. Tsirkin wrote:
> 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 <address@hidden>
>
> patch itself is ok I think
>
> Reviewed-by: Michael S. Tsirkin <address@hidden>
>
> 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?

It did not work and I missed the error in my test output. I tested it
now manually by migrating and then cancelling. Device was added back
to source VM successfully.

Will sent new version with better patch description.

Thanks!

regards
Jens