Subject: Re: [PATCH net-next 2/6] net: sched: Add centralized RED flag checking

From: Petr Machata <[email-masked]>
Date: Tue, 10 Mar 2020 23:23:23 +0100

Jakub Kicinski <[email-masked]> writes:

> On Tue, 10 Mar 2020 10:48:24 +0100 Petr Machata wrote:
>> > The only flags which are validated today are the gRED per-vq ones, which
>> > are a recent addition and were validated from day one.
>>
>> Do you consider the validation as such to be a problem? Because that
>> would mean that the qdiscs that have not validated flags this way
>> basically cannot be extended ever ("a buggy userspace used to get a
>> quiet slicing of flags, and now they mean something").
>
> I just remember leaving it as is when I was working on GRED, because
> of the potential breakage. The uAPI policy is what it is, then again
> we probably lose more by making the code of these ancient Qdiscs ugly
> than we win :(
>
> I don't feel like I can ack it with clear conscience tho.

Just to make sure -- are you opposed to adding a new flag, or to
validation? At least the adaptative flag was added years after the
others in 2011. I wasn't paying much attention to kernel back then, but
I think the ABI rules are older than that.