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

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Message-ID: <20180729075146.GA2260@nanopsycho.orion>
Date:   Sun, 29 Jul 2018 09:51:46 +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

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