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From: Petr Machata <petrm@mellanox.com>
To: Jakub Kicinski <kuba@kernel.org>
Cc: Ido Schimmel <idosch@idosch.org>,
	netdev@vger.kernel.org, davem@davemloft.net, jiri@mellanox.com,
	jhs@mojatatu.com, xiyou.wangcong@gmail.com, mlxsw@mellanox.com,
	Ido Schimmel <idosch@mellanox.com>
Subject: Re: [PATCH net-next 2/6] net: sched: Add centralized RED flag checking
Date: Wed, 11 Mar 2020 00:53:29 +0100	[thread overview]
Message-ID: <87lfo7ydfq.fsf@mellanox.com> (raw)
In-Reply-To: <20200310160052.72e7e09b@kicinski-fedora-PC1C0HJN>


Jakub Kicinski <kuba@kernel.org> writes:

> On Tue, 10 Mar 2020 23:23:23 +0100 Petr Machata wrote:
>> Jakub Kicinski <kuba@kernel.org> 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? 
>
> They are both uABI changes, so both.
>
>> 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.
>
> Yes, but some (e.g. TC subsystem) didn't really care much about those
> rules until more recently.
>
> The alternative to validation/adding flag in place is obviously to add 
> a new netlink attribute which would be validated from the start. Can you
> give it a try and see how ugly it gets?

Yeah, I'll give it a stab tomorrow.

  reply	other threads:[~2020-03-10 23:53 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-09 18:34 [PATCH net-next 0/6] RED: Introduce an ECN tail-dropping mode Ido Schimmel
2020-03-09 18:34 ` [PATCH net-next 1/6] selftests: qdiscs: Add TDC test for RED Ido Schimmel
2020-03-10 15:40   ` Roman Mashak
2020-03-10 16:56     ` Petr Machata
2020-03-10 17:28       ` Roman Mashak
2020-03-09 18:34 ` [PATCH net-next 2/6] net: sched: Add centralized RED flag checking Ido Schimmel
2020-03-09 22:18   ` Jakub Kicinski
2020-03-10  9:48     ` Petr Machata
2020-03-10 19:53       ` Jakub Kicinski
2020-03-10 22:23         ` Petr Machata
2020-03-10 23:00           ` Jakub Kicinski
2020-03-10 23:53             ` Petr Machata [this message]
2020-03-09 18:35 ` [PATCH net-next 3/6] net: sched: RED: Introduce an ECN tail-dropping mode Ido Schimmel
2020-03-09 22:12   ` Jakub Kicinski
2020-03-10  9:48     ` Petr Machata
2020-03-09 18:35 ` [PATCH net-next 4/6] mlxsw: spectrum_qdisc: Offload RED " Ido Schimmel
2020-03-09 18:35 ` [PATCH net-next 5/6] selftests: qdiscs: RED: Add taildrop tests Ido Schimmel
2020-03-09 18:35 ` [PATCH net-next 6/6] selftests: mlxsw: RED: Test RED ECN taildrop offload Ido Schimmel

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