netdev - Re: [PATCH net-next v3 5/5] act_mirred: use TC_ACT

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Message-ID: <39f8a66e-cf2c-13cd-9f92-cd61b60cb5e1@mojatatu.com>
Date:   Wed, 25 Jul 2018 07:50:51 -0400
From:   Jamal Hadi Salim <jhs@...atatu.com>
To:     Cong Wang <xiyou.wangcong@...il.com>,
        Paolo Abeni <pabeni@...hat.com>
Cc:     Linux Kernel Network Developers <netdev@...r.kernel.org>,
        Jiri Pirko <jiri@...nulli.us>,
        Daniel Borkmann <daniel@...earbox.net>,
        Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
        Eyal Birger <eyal.birger@...il.com>,
        David Miller <davem@...emloft.net>
Subject: Re: [PATCH net-next v3 5/5] act_mirred: use TC_ACT_REINJECT when
 possible

On 24/07/18 05:15 PM, Cong Wang wrote:
> On Tue, Jul 24, 2018 at 1:07 PM Paolo Abeni <pabeni@...hat.com> wrote:
>> +
>> +               /* let's the caller reinject the packet, if possible */
>> +               if (skb_at_tc_ingress(skb)) {
>> +                       res->ingress = want_ingress;
>> +                       res->qstats = this_cpu_ptr(m->common.cpu_qstats);
>> +                       return TC_ACT_REINJECT;
>> +               }
> 
> Looks good to me, but here we no longer return user-specified
> return value here, I am sure it is safe for TC_ACT_STOLEN, but
> I am not sure if it is safe for other values, like TC_ACT_RECLASSIFY.
> 
> Jamal, is there any use case of returning !TC_ACT_STOLEN for
> ingress redirections?

I cant think of one off top of my head.
There maybe a future use case where it is not so - maybe just allow
to return the user programmed action? that value will always be
TC_ACT_STOLEN if the rule was specified via iproute2/tc.

cheers,
jamal