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

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Date:   Tue, 31 Jul 2018 01:01:46 -0700
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     Jiri Pirko <jiri@...nulli.us>
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

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() ?