Re: [PATCH net-next 0/9] DSA changes for multiple CPU ports (part 4)

On Fri, 2 Sep 2022 10:31:46 +0000
Vladimir Oltean [off-list ref] wrote:

On Tue, Aug 30, 2022 at 10:59:23PM +0300, Vladimir Oltean wrote:

quoted

This series represents the final part of that effort. We have:

- the introduction of new UAPI in the form of IFLA_DSA_MASTER  

Call for opinions: when I resend this, should I keep rtnl_link_ops,
or should I do what Marek attempted to do, and make the existing iflink
between a user port and its master writable from user space?
https://lore.kernel.org/netdev/20190824024251.4542-4-marek.behun@nic.cz/ (local)

I'm not sure if we have that many more use cases for rtnl_link_ops..
at some point I was thinking we could change the way in which dsa_loop
probes, and allow dynamic creation of such interfaces using RTM_NEWLINK;
but looking closer at that, it's a bit more complicated, since we'd need
to attach dsa_loop user ports to a virtual switch, and probe all ports
at the same time rather than one by one.

My opinion is that it would be better to add new DSA specific netlink
operations instead of using the existing iflink as I did in the that
patch.

I think that DSA should have it's own IP subcommands. Using the
standard, already existing API, is not sufficient for more complex
configurations/DSA routing settings. Consider DSA where there are
multiple switches and the switches are connected via multiple ports:

+----------+   +---------------+   +---------+
|     eth0 <---> sw0p0   sw0p2 <---> sw1p0
| cpu      |   |               |   |        ....
|     eth1 <---> sw0p1   s20p3 <---> sw1p1
+----------+   +---------------+   +---------+

The routing is more complicated in this scenario. The old API is not
sufficient.

Marek