From mboxrd@z Thu Jan  1 00:00:00 1970
From: Roman Mashak <mrv@mojatatu.com>
Subject: Re: [PATCH net-next 1/1] net sched qdisc: pass netlink message flags in event notification
Date: Mon, 30 Oct 2017 17:17:09 -0400
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Cc: David Miller <davem@davemloft.net>,
        Linux Kernel Network Developers <netdev@vger.kernel.org>,
        Jamal Hadi Salim <jhs@mojatatu.com>,
        Jiri Pirko <jiri@resnulli.us>
To: Cong Wang <xiyou.wangcong@gmail.com>
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Cong Wang <xiyou.wangcong@gmail.com> writes:

> On Mon, Oct 30, 2017 at 11:07 AM, Roman Mashak <mrv@mojatatu.com> wrote:
>> Cong Wang <xiyou.wangcong@gmail.com> writes:
>>
>>> On Sat, Oct 28, 2017 at 8:36 PM, Roman Mashak <mrv@mojatatu.com> wrote:
>>>> Cong Wang <xiyou.wangcong@gmail.com> writes:
>>>
>>> Hmm, I thought you use RTM_NEWQDISC+RTM_DELQDISC to
>>> determine it is replacement, no?
>>
>> Create is RTM_NEWQDISC and NLM_F_EXCL|NLM_F_CREATE, replacement is
>> RTM_NEWQDISC and NLM_F_REPLACE in netlink flags.
>
> Is there any reason we can't use RTM_NEWQDISC+RTM_DELQDISC
> rather than NLM_F_REPLACE to determine it is replacement?
>

I'm not sure this would be valid semantics for replace operation, look at
the rfc3549:

Additional flag bits for NEW requests
          NLM_F_REPLACE   Replace existing matching config object with
                          this request.

> Note, RTM_NEWQDISC+RTM_DELQDISC are put in a same
> message not two.

Hmm, could you clarify how do you expect to put two event IDs in nlmsg_type?