Re: [PATCH net-next 2/9] net: bridge: offload initial and final port flags through switchdev

[Vladimir Oltean]

On Mon, Feb 08, 2021 at 01:37:03PM +0200, Nikolay Aleksandrov wrote:
> Hi Vladimir,
> I think this patch potentially breaks some use cases. There are a few problems, I'll
> start with the more serious one: before the ports would have a set of flags that were
> always set when joining, now due to how nbp_flags_change() handles flag setting some might
> not be set which would immediately change behaviour w.r.t software fwding. I'll use your
> example of BR_BCAST_FLOOD: a lot of drivers will return an error for it and any broadcast
> towards these ports will be dropped, we have mixed environments with software ports that
> sometimes have traffic (e.g. decapped ARP requests) software forwarded which will stop working.

Yes, you're right. The only solution I can think of is to add a "bool ignore_errors"
to nbp_flags_change, set to true from new_nbp and del_nbp, and to false from the
netlink code.

> The other lesser issue is with the style below, I mean these three calls for each flag are
> just ugly and look weird as you've also noted, since these APIs are internal can we do better?

Doing better would mean allowing nbp_flags_change() to have a bit mask with
potentially more brport flags set, and to call br_switchdev_set_port_flag in
a for_each_set_bit() loop?