Re: [PATCH v21 net-next 1/6] sched: Struct definition and parsing of dualpi2 qdisc

[Jakub Kicinski <kuba@kernel.org>]

On Tue, 8 Jul 2025 20:22:23 +0000 Chia-Yu Chang (Nokia) wrote:
> The original patch looks like below, and I see the option is
> mandatory otherwise it will return -EINVAL.
> 
> Is this what you mean in your comments or you mean other things?
> 
> +       if (!opt) {
> +               NL_SET_ERR_MSG_MOD(extack, "Dualpi2 options are reuqired");
> +               return -EINVAL;
> +       }

To speed this up a bit across timezones -- I'm pretty sure what Paolo
means is that you reject the situation where user provides no
[TCA_OPTIONS] at the netlink level. But if the user provides an empty 
one its fine.

So normal config looks something like eg (indent means nesting):

[TCA_KIND]
[TCA_OPTIONS]
  [TCA_DUALPI2_LIMIT]
  [TCA_DUALPI2_TARGET]

If there is no TCA_OPTIONS you'd error out:

[TCA_KIND]

But if TCA_OPTIONS is empty you dont:

[TCA_KIND]
[TCA_OPTIONS]

Just return 0 instead of an error if TCA_OPTIONS is not there.