From: Jiri Pirko <jiri@resnulli.us>
To: Cong Wang <xiyou.wangcong@gmail.com>
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
Subject: Re: [patch net-next v4 03/12] net: sched: introduce chain object to uapi
Date: Thu, 26 Jul 2018 14:27:45 +0200 [thread overview]
Message-ID: <20180726122745.GH2222@nanopsycho> (raw)
In-Reply-To: <20180726100614.GF2222@nanopsycho>
Thu, Jul 26, 2018 at 12:06:14PM CEST, jiri@resnulli.us wrote:
>Thu, Jul 26, 2018 at 09:38:39AM CEST, jiri@resnulli.us wrote:
>>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.
>
>Actually, I found an issue. The action to "goto chain" might be attached
>to a filter in the same chain. That is completely legitimate usage.
>When I do:
># tc chain del X
>I expect the chain to be flushed and removed. If there is an action
>there with "goto" to the same chain, the command should be successful.
>However, I don't see any easy way to find out if the chain is referenced
>only by actions used by filters in the same chain :/
>
>Thoughts?
I'm now working on a patch that would treat empty chains implicitly
created or deleted by user that only are referenced by action as a
zombie ones. They won't be visible on dump. User won't know about them,
they would only serve as a place holder for "goto chain" actions.
I think it is reasonable. What do you think.
Will send the RFC in few hours.
>
next prev parent reply other threads:[~2018-07-26 13:46 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-23 7:23 [patch net-next v4 00/12] sched: introduce chain templates support with offloading to mlxsw Jiri Pirko
2018-07-23 7:23 ` [patch net-next v4 01/12] net: sched: push ops lookup bits into tcf_proto_lookup_ops() Jiri Pirko
2018-07-23 7:23 ` [patch net-next v4 02/12] net: sched: Avoid implicit chain 0 creation Jiri Pirko
2018-07-23 7:23 ` [patch net-next v4 03/12] net: sched: introduce chain object to uapi Jiri Pirko
2018-07-24 22:30 ` Cong Wang
2018-07-24 23:20 ` Cong Wang
2018-07-25 6:46 ` Jiri Pirko
2018-07-25 16:40 ` Cong Wang
2018-07-26 7:38 ` Jiri Pirko
2018-07-26 10:06 ` Jiri Pirko
2018-07-26 12:27 ` Jiri Pirko [this message]
2018-07-23 7:23 ` [patch net-next v4 04/12] net: sched: introduce chain templates Jiri Pirko
2018-07-23 7:23 ` [patch net-next v4 05/12] net: sched: cls_flower: move key/mask dumping into a separate function Jiri Pirko
2018-07-23 7:23 ` [patch net-next v4 06/12] net: sched: cls_flower: change fl_init_dissector to accept mask and dissector Jiri Pirko
2018-07-23 7:23 ` [patch net-next v4 07/12] net: sched: cls_flower: implement chain templates Jiri Pirko
2018-07-23 7:23 ` [patch net-next v4 08/12] net: sched: cls_flower: propagate chain teplate creation and destruction to drivers Jiri Pirko
2018-07-23 7:23 ` [patch net-next v4 09/12] mlxsw: spectrum: Implement chain template hinting Jiri Pirko
2018-07-23 7:24 ` [patch net-next v4 10/12] selftests: forwarding: move shblock tc support check to a separate helper Jiri Pirko
2018-07-23 7:24 ` [patch net-next v4 11/12] selftests: forwarding: add tests for TC chains creation adn destruction Jiri Pirko
2018-07-23 7:24 ` [patch net-next v4 12/12] selftests: forwarding: add tests for TC chain templates Jiri Pirko
2018-07-23 7:24 ` [patch iproute2/net-next v4] tc: introduce support for " Jiri Pirko
2018-07-25 17:03 ` David Ahern
2018-07-23 16:28 ` [patch net-next v4 00/12] sched: introduce chain templates support with offloading to mlxsw David Miller
2018-07-23 23:36 ` Jakub Kicinski
2018-07-24 3:45 ` David Miller
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