netdev - Re: [patch net-next] net: sched: don't dump chains only held by actions

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Date:   Tue, 31 Jul 2018 08:32:58 +0200
From:   Jiri Pirko <jiri@...nulli.us>
To:     Cong Wang <xiyou.wangcong@...il.com>
Cc:     Linux Kernel Network Developers <netdev@...r.kernel.org>,
        David Miller <davem@...emloft.net>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>,
        mlxsw@...lanox.com
Subject: Re: [patch net-next] net: sched: don't dump chains only held by
 actions

Mon, Jul 30, 2018 at 08:19:56PM CEST, xiyou.wangcong@...il.com wrote:
>On Sun, Jul 29, 2018 at 12:54 AM Jiri Pirko <jiri@...nulli.us> wrote:
>>
>> Sat, Jul 28, 2018 at 07:39:36PM CEST, xiyou.wangcong@...il.com wrote:
>> >On Sat, Jul 28, 2018 at 10:20 AM Cong Wang <xiyou.wangcong@...il.com> wrote:
>> >>
>> >> On Fri, Jul 27, 2018 at 12:47 AM Jiri Pirko <jiri@...nulli.us> wrote:
>> >> >
>> >> > From: Jiri Pirko <jiri@...lanox.com>
>> >> >
>> >> > In case a chain is empty and not explicitly created by a user,
>> >> > such chain should not exist. The only exception is if there is
>> >> > an action "goto chain" pointing to it. In that case, don't show the
>> >> > chain in the dump. Track the chain references held by actions and
>> >> > use them to find out if a chain should or should not be shown
>> >> > in chain dump.
>> >> >
>> >> > Signed-off-by: Jiri Pirko <jiri@...lanox.com>
>> >>
>> >> Looks reasonable to me.
>> >>
>> >> Acked-by: Cong Wang <xiyou.wangcong@...il.com>
>> >
>> >Hold on...
>> >
>> >If you increase the refcnt for a zombie chain on NEWCHAIN path,
>> >then it would become a non-zombie, this makes sense. However,
>> >if the action_refcnt gets increased again when another action uses it,
>> >it become a zombie again because refcnt==action_refcnt??
>>
>> No. action always increases both refcnt and action_refcnt
>
>Hmm, then the name zombie is confusing, with your definition all
>chains implicitly created by actions are zombies, unless touched
>by user explicitly. Please find a better name.

Okay. Perhaps chain_inactive?

>
>Also, tcf_chain_get_by_act() could send out RTM_NEWCHAIN too,
>which is confusing too as it is still a "zombie".

Will check.