Re: [PATCH RFC iproute2-next] iplink: allow to change iplink value

[Vladimir Oltean]

On Sun, Apr 11, 2021 at 10:04:11AM -0700, Stephen Hemminger wrote:
> On Sat, 10 Apr 2021 15:34:50 +0200
> Ansuel Smith <ansuelsmth@xxxxxxxxx> wrote:
> 
> > Allow to change the interface to which a given interface is linked to.
> > This is useful in the case of multi-CPU port DSA, for changing the CPU
> > port of a given user port.
> > 
> > Signed-off-by: Marek Behún <marek.behun@xxxxxx>
> > Cc: David Ahern <dsahern@xxxxxxxxx>
> > Cc: Stephen Hemminger <stephen@xxxxxxxxxxxxxxxxxx>
> 
> This may work for DSA but it won't work for all the device types vlan/macsec/... that
> now use the link attribute.  It looks like the change link handling for those
> device types just ignores the link attribute (maybe ok). But before supporting this
> as an API, it would be better if all the other drivers that use IFLA_LINK
> had error checks in their change link handling.
> 
> Please add error checks in kernel first.

Would it be better to expose this as a netlink attribute specific to
DSA, instead of iflink which as you point out has uses for other virtual
interfaces like veth, and the semantics there are not quite the same?