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

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Date:   Tue, 31 Jul 2018 10:48:08 +0200
From:   Jiri Pirko <jiri@...nulli.us>
To:     Jakub Kicinski <jakub.kicinski@...ronome.com>
Cc:     Cong Wang <xiyou.wangcong@...il.com>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>,
        David Miller <davem@...emloft.net>,
        Jamal Hadi Salim <jhs@...atatu.com>, mlxsw@...lanox.com
Subject: Re: [patch net-next] net: sched: don't dump chains only held by
 actions

Tue, Jul 31, 2018 at 10:01:46AM CEST, jakub.kicinski@...ronome.com wrote:
>On Tue, 31 Jul 2018 08:32:58 +0200, Jiri Pirko wrote:
>> 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?
>
>FWIW to me active brings to mind that it's handling traffic.  Brining in
>my suggestions from an off-list discussion:
>
>tcf_chain_act_refs_only() or tcf_chain_pure_act_target()

:/

>
>or maybe tcf_chain_has_no_filters() ?

That is not accurate, as explicitly created chain does not have any
filters too.

I think this is good:
tcf_chain_held_by_acts_only()