netdev - Re: [Patch net-next] net_sched: add reverse binding for tc class

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Date:   Wed, 30 Aug 2017 15:01:06 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     Daniel Borkmann <daniel@...earbox.net>
Cc:     Linux Kernel Network Developers <netdev@...r.kernel.org>,
        Jamal Hadi Salim <jhs@...atatu.com>
Subject: Re: [Patch net-next] net_sched: add reverse binding for tc class

On Wed, Aug 30, 2017 at 2:48 PM, Daniel Borkmann <daniel@...earbox.net> wrote:
> On 08/30/2017 11:30 PM, Cong Wang wrote:
> [...]
>>
>> Note, we still can NOT totally get rid of those class lookup in
>> ->enqueue() because cgroup and flow filters have no way to determine
>> the classid at setup time, they still have to go through dynamic lookup.
>
> [...]
>>
>> ---
>>   include/net/sch_generic.h |  1 +
>>   net/sched/cls_basic.c     |  9 +++++++
>>   net/sched/cls_bpf.c       |  9 +++++++
>
>
> Same is for cls_bpf as well, so bind_class wouldn't work there
> either as we could return dynamic classids. bind_class cannot
> be added here, too.

I think you are probably right, but the following code is
misleading there:

        if (tb[TCA_BPF_CLASSID]) {
                prog->res.classid = nla_get_u32(tb[TCA_BPF_CLASSID]);
                tcf_bind_filter(tp, &prog->res, base);
        }

If the classid is dynamic, why this tb[TCA_BPF_CLASSID]?