From: Jamal Hadi Salim <jhs@mojatatu•com>
To: Cong Wang <xiyou.wangcong@gmail•com>
Cc: Linux Kernel Network Developers <netdev@vger•kernel.org>,
"David S. Miller" <davem@davemloft•net>,
Cong Wang <cwang@twopensource•com>
Subject: Re: [Patch net] sched, cls: check if we could overwrite actions when changing a filter
Date: Wed, 23 Apr 2014 07:30:27 -0400 [thread overview]
Message-ID: <5357A453.6030901@mojatatu.com> (raw)
In-Reply-To: <CAM_iQpVM-djLiz9Z9Bhz9zac88m8b6t1S-SRUkRxYhOaW_xJvQ@mail.gmail.com>
On 04/21/14 19:28, Cong Wang wrote:
> On Sat, Apr 19, 2014 at 4:10 AM, Jamal Hadi Salim <jhs@mojatatu•com> wrote:
>> On 04/18/14 13:18, Cong Wang wrote:
>> RTNL is one dimension. The other is the datapath processing.
>> You need to make sure that packets still flow correctly during the
>> change over.
>
> Sure, since we grab tcf_tree_lock() before changing actions in
> tcf_exts_change(), I think this is guaranteed too.
>
Maybe - I thought there were recent changes to tcf_tree_lock that
eased the restriction. Youd need to make sure.
>> Well - then go nuts and put out a patch.
>> Replace _all or none_ is a reasonable approach.
>>
>>
>
> Great! We both agree on this.
>
> Looking at the current code, we first initialize a list of actions
> and then replace them as a whole by splicing the lists with
> tcf_tree_lock held, so this is already done. IOW, this patch
> is enough.
>
> Or am I missing anything?
>
I dont see what you are seeing. However, some quick tests will prove it.
Example go from 1->3 actions and backwards 3->1 actions.
I.e create a policy with (handwave) 3 actions and replace it with
another that has only one action. Do this while you are sending a
ping exercising this policy.
I can see how yours with 1->0 and 0->1 will work.
cheers,
jamal
next prev parent reply other threads:[~2014-04-23 11:30 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-15 23:46 [Patch net] sched, cls: check if we could overwrite actions when changing a filter Cong Wang
2014-04-16 12:30 ` Jamal Hadi Salim
2014-04-16 21:10 ` Cong Wang
2014-04-17 11:50 ` Jamal Hadi Salim
2014-04-17 20:48 ` Cong Wang
2014-04-18 14:26 ` Jamal Hadi Salim
2014-04-18 17:18 ` Cong Wang
2014-04-19 11:10 ` Jamal Hadi Salim
2014-04-21 23:28 ` Cong Wang
2014-04-23 11:30 ` Jamal Hadi Salim [this message]
2014-04-24 21:12 ` Cong Wang
2014-04-25 15:48 ` Jamal Hadi Salim
2014-04-25 20:41 ` Cong Wang
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