netdev - Re: [PATCH v3 3/6] bpf: add BPF_PROG_ATTACH and BPF_PROG

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Message-ID: <450b6b76-f83b-82d4-7a02-8cc8156236ba@zonque.org>
Date:   Mon, 5 Sep 2016 20:43:05 +0200
From:   Daniel Mack <daniel@...que.org>
To:     Alexei Starovoitov <ast@...com>,
        Daniel Borkmann <daniel@...earbox.net>, htejun@...com
Cc:     davem@...emloft.net, kafai@...com, fw@...len.de,
        pablo@...filter.org, harald@...hat.com, netdev@...r.kernel.org,
        sargun@...gun.me
Subject: Re: [PATCH v3 3/6] bpf: add BPF_PROG_ATTACH and BPF_PROG_DETACH
 commands

On 09/05/2016 08:32 PM, Alexei Starovoitov wrote:
> On 9/5/16 10:09 AM, Daniel Borkmann wrote:
>> On 09/05/2016 04:09 PM, Daniel Mack wrote:

>>> I really don't think it's worth sparing 8 bytes here and then do the
>>> binary compat dance after flags are added, for no real gain.
>>
>> Sure, but there's not much of a dance needed, see for example how map_flags
>> were added some time ago. So, iff there's really no foreseeable use-case in
>> sight and since we have this flexibility in place already, then I don't
>> quite
>> follow why it's needed, if there's zero pain to add it later on. I would
>> understand it of course, if it cannot be handled later on anymore.
> 
> I agree with Daniel B. Since flags are completely unused right now,
> there is no plan to use it for anything in the coming months and
> even worse they make annoying hole in the struct, let's not
> add them. We can safely do that later. CHECK_ATTR() allows us to
> do it easily. It's not like syscall where flags are must have,
> since we cannot add it later. Here it's done trivially.

Okay then. If you both agree, I won't interfere :)


Daniel