From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jiri Pirko <jiri@resnulli.us>
Subject: Re: [patch net-next v4 03/12] net: sched: introduce chain object to
 uapi
Date: Thu, 26 Jul 2018 09:38:39 +0200
Message-ID: <20180726073839.GB2222@nanopsycho>
References: <20180723072312.4153-1-jiri@resnulli.us>
 <20180723072312.4153-4-jiri@resnulli.us>
 <CAM_iQpU41g_aSd7wbRk5r+hbVRdoDYnLWANjOJtZYgf4qfx0_w@mail.gmail.com>
 <CAM_iQpXxOOAw06tGiCmkWrMkU4xoNO8cwTP349vU8AGj--OXVQ@mail.gmail.com>
 <20180725064645.GA2164@nanopsycho>
 <CAM_iQpU8EQ+GDPROek7f12oJJeXB5Jp2sUaBSKP4hPBSLNN1dg@mail.gmail.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Cc: Linux Kernel Network Developers <netdev@vger.kernel.org>,
        David Miller <davem@davemloft.net>,
        Jamal Hadi Salim <jhs@mojatatu.com>,
        Jakub Kicinski <jakub.kicinski@netronome.com>,
        Simon Horman <simon.horman@netronome.com>,
        john.hurley@netronome.com, David Ahern <dsahern@gmail.com>,
        mlxsw@mellanox.com, sridhar.samudrala@intel.com
To: Cong Wang <xiyou.wangcong@gmail.com>
Return-path: <netdev-owner@vger.kernel.org>
Received: from mail-wr1-f67.google.com ([209.85.221.67]:44072 "EHLO
        mail-wr1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1726734AbeGZI4n (ORCPT
        <rfc822;netdev@vger.kernel.org>); Thu, 26 Jul 2018 04:56:43 -0400
Received: by mail-wr1-f67.google.com with SMTP id r16-v6so661972wrt.11
        for <netdev@vger.kernel.org>; Thu, 26 Jul 2018 00:41:08 -0700 (PDT)
Content-Disposition: inline
In-Reply-To: <CAM_iQpU8EQ+GDPROek7f12oJJeXB5Jp2sUaBSKP4hPBSLNN1dg@mail.gmail.com>
Sender: netdev-owner@vger.kernel.org
List-ID: <netdev.vger.kernel.org>

Wed, Jul 25, 2018 at 06:40:44PM CEST, xiyou.wangcong@gmail.com wrote:
>On Tue, Jul 24, 2018 at 11:49 PM Jiri Pirko <jiri@resnulli.us> wrote:
>>
>> Wed, Jul 25, 2018 at 01:20:08AM CEST, xiyou.wangcong@gmail.com wrote:
>> >So, you only send out notification when the last refcnt is gone.
>> >
>> >If the chain that is being deleted by a user is still used by an action,
>> >you return 0 or -EPERM?
>>
>> 0 and the chain stays there until the action is removed. Hmm, do you thing
>> that -EPERM should be returned in that case? The thing is, we have to
>> flush the chain in order to see the action references are there. We would
>> have to have 2 ref counters, one for filter, one for actions.
>> What do you think?
>
>_If_ RTM_DELCHAIN does decrease the chain refcnt, then it is
>broken:
>
># tc chain add X... (refcnt == 1)
># tc action add ... goto chain X (refcnt==2)
># tc chain del X ... (refcnt== 1)
># tc chain del X ... (refcnt==0)
>
>RTM_DELCHAIN should just test if refcnt is 1, if it is, delete it,
>otherwise return -EPERM. This is how we handle tc standalone
>actions, see tcf_idr_delete_index().
>
>Yes, you might need two refcnt's here.

Okay. Sounds good. I'm on it.