Subject: Re: [PATCH net-next 1/1] net sched qdisc: pass netlink message flags in event notification

From: Roman Mashak <[email-masked]>
Date: Mon, 30 Oct 2017 17:17:09 -0400

Cong Wang <[email-masked]> writes:

> On Mon, Oct 30, 2017 at 11:07 AM, Roman Mashak <[email-masked]> wrote:
>> Cong Wang <[email-masked]> writes:
>>
>>> On Sat, Oct 28, 2017 at 8:36 PM, Roman Mashak <[email-masked]> wrote:
>>>> Cong Wang <[email-masked]> 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?