netdev - Re: [PATCH net-next] net, cls: allow for deleting all filters for given parent

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Date:	Mon, 06 Jun 2016 22:32:48 +0200
From:	Daniel Borkmann <daniel@...earbox.net>
To:	Cong Wang <xiyou.wangcong@...il.com>
CC:	David Miller <davem@...emloft.net>,
	Alexei Starovoitov <alexei.starovoitov@...il.com>,
	john fastabend <john.fastabend@...il.com>,
	Jamal Hadi Salim <jhs@...atatu.com>,
	Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next] net, cls: allow for deleting all filters for
 given parent

On 06/06/2016 09:52 PM, Cong Wang wrote:
> On Mon, Jun 6, 2016 at 12:25 PM, Daniel Borkmann <daniel@...earbox.net> wrote:
>> On 06/06/2016 07:12 PM, Cong Wang wrote:
>>>
>>> On Sat, Jun 4, 2016 at 9:24 AM, Daniel Borkmann <daniel@...earbox.net>
>>> wrote:
>>>>
>>>> +       if (n->nlmsg_type == RTM_DELTFILTER && prio == 0) {
>>>> +               tcf_destroy_chain(chain);
>>>> +               err = 0;
>>>> +               goto errout;
>>>> +       }
>>>
>>> We need to notify users we removed which filters, right?
>>
>> As far as I know, most such use cases that listen on this are bypasses
>> that mirror kernel configs from user space ... but well, sure, I can add
>> a notification if people care. Would do this as a separate patch.
>
> This is fundamental for libnl to update caches.

I see, makes sense then. Thanks!

> I don't understand why it should be separated, since notification is
> not a feature, we already have notifications in other paths.
>
>> Looking into this, I would probably make this a single notification that
>> denotes this 'wild-card' removal for that parent instead of calling
>> tfilter_notify() for each filter separately (which allocs skb, dumps it,
>> etc), qdisc del doesn't loop through it either, so probably fine this way.
>
> Makes sense.
>
> Thanks.
>