Linux Virtualization - Apr 2019 - [PATCH net v6] failover: allow name change on IFF_UP slave interfaces

On Wed,  3 Apr 2019 00:52:47 -0400
Si-Wei Liu <si-wei.liu at oracle.com> wrote:
>  
> +	if (unlikely(dev->flags & IFF_UP)) {
> +		struct netdev_notifier_change_info change_info = {
> +			.info.dev = dev,
> +		};
> +
> +		call_netdevice_notifiers_info(NETDEV_CHANGE,
> +					      &change_info.info);
> +	}
This notifier is not really necessary, there already is a CHANGENAME
that gets sent.

NETDEV_CHANGE is used in other cases to mean that the state (flags)
have changed.

On Fri, Apr 05, 2019 at 02:47:01PM -0700, Stephen Hemminger
wrote:
> On Wed,  3 Apr 2019 00:52:47 -0400
> Si-Wei Liu <si-wei.liu at oracle.com> wrote:
> 
> >  
> > +	if (unlikely(dev->flags & IFF_UP)) {
> > +		struct netdev_notifier_change_info change_info = {
> > +			.info.dev = dev,
> > +		};
> > +
> > +		call_netdevice_notifiers_info(NETDEV_CHANGE,
> > +					      &change_info.info);
> > +	}
> 
> This notifier is not really necessary, there already is a CHANGENAME
> that gets sent.
> NETDEV_CHANGE is used in other cases to mean that the state (flags)
> have changed.
The point is some existing scripts might not expect name
change to happen without a status change afterwards (since it was
impossible for so long). So this reports a change
to make sure scripts do not miss it.

On Fri, 5 Apr 2019 18:01:43 -0400
"Michael S. Tsirkin" <mst at redhat.com> wrote:
> > 
> > This notifier is not really necessary, there already is a CHANGENAME
> > that gets sent.
> > NETDEV_CHANGE is used in other cases to mean that the state (flags)
> > have changed.  
> 
> The point is some existing scripts might not expect name
> change to happen without a status change afterwards (since it was
> impossible for so long). So this reports a change
> to make sure scripts do not miss it.

I don't think it matters because if device named is changed and it
is down (!IFF_UP) then only CHANGENAME is sent. The NETDEV_CHANGE is
just noise to an application.