From: "Toke Høiland-Jørgensen" <toke@redhat.com>
To: Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii.nakryiko@gmail.com>,
Kumar Kartikeya Dwivedi <memxor@gmail.com>
Cc: bpf <bpf@vger.kernel.org>,
Jesper Dangaard Brouer <brouer@redhat.com>,
Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
Yonghong Song <yhs@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@kernel.org>, Shuah Khan <shuah@kernel.org>,
"David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Jesper Dangaard Brouer <hawk@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
open list <linux-kernel@vger.kernel.org>,
Networking <netdev@vger.kernel.org>,
"open list:KERNEL SELFTEST FRAMEWORK"
<linux-kselftest@vger.kernel.org>
Subject: Re: [PATCH bpf-next 3/5] libbpf: add low level TC-BPF API
Date: Wed, 31 Mar 2021 11:51:45 +0200 [thread overview]
Message-ID: <878s63r6q6.fsf@toke.dk> (raw)
In-Reply-To: <48b99ccc-8ef6-4ba9-00f9-d7e71ae4fb5d@iogearbox.net>
Daniel Borkmann <daniel@iogearbox.net> writes:
> On 3/30/21 10:39 PM, Andrii Nakryiko wrote:
>> On Sun, Mar 28, 2021 at 1:11 AM Kumar Kartikeya Dwivedi
>> <memxor@gmail.com> wrote:
>>> On Sun, Mar 28, 2021 at 10:12:40AM IST, Andrii Nakryiko wrote:
>>>> Is there some succinct but complete enough documentation/tutorial/etc
>>>> that I can reasonably read to understand kernel APIs provided by TC
>>>> (w.r.t. BPF, of course). I'm trying to wrap my head around this and
>>>> whether API makes sense or not. Please share links, if you have some.
>>>
>>> Hi Andrii,
>>>
>>> Unfortunately for the kernel API part, I couldn't find any when I was working
>>> on this. So I had to read the iproute2 tc code (tc_filter.c, f_bpf.c,
>>> m_action.c, m_bpf.c) and the kernel side bits (cls_api.c, cls_bpf.c, act_api.c,
>>> act_bpf.c) to grok anything I didn't understand. There's also similar code in
>>> libnl (lib/route/{act,cls}.c).
>>>
>>> Other than that, these resources were useful (perhaps you already went through
>>> some/all of them):
>>>
>>> https://docs.cilium.io/en/latest/bpf/#tc-traffic-control
>>> https://qmonnet.github.io/whirl-offload/2020/04/11/tc-bpf-direct-action/
>>> tc(8), and tc-bpf(8) man pages
>>>
>>> I hope this is helpful!
>>
>> Thanks! I'll take a look. Sorry, I'm a bit behind with all the stuff,
>> trying to catch up.
>>
>> I was just wondering if it would be more natural instead of having
>> _dev _block variants and having to specify __u32 ifindex, __u32
>> parent_id, __u32 protocol, to have some struct specifying TC
>> "destination"? Maybe not, but I thought I'd bring this up early. So
>> you'd have just bpf_tc_cls_attach(), and you'd so something like
>>
>> bpf_tc_cls_attach(prog_fd, TC_DEV(ifindex, parent_id, protocol))
>>
>> or
>>
>> bpf_tc_cls_attach(prog_fd, TC_BLOCK(block_idx, protocol))
>>
>> ? Or it's taking it too far?
>>
>> But even if not, I think detaching can be unified between _dev and
>> _block, can't it?
>
> Do we even need the _block variant? I would rather prefer to take the chance
> and make it as simple as possible, and only iff really needed extend with
> other APIs, for example:
>
> bpf_tc_attach(prog_fd, ifindex, {INGRESS,EGRESS});
>
> Internally, this will create the sch_clsact qdisc & cls_bpf filter instance
> iff not present yet, and attach to a default prio 1 handle 1, and _always_ in
> direct-action mode. This is /as simple as it gets/ and we don't need to bother
> users with more complex tc/cls_bpf internals unless desired. For example,
> extended APIs could add prio/parent so that multi-prog can be attached to a
> single cls_bpf instance, but even that could be a second step, imho.
While I'm all for simplifying where possible, the question becomes at
what level? I.e., we initially figured we'd expose (most of) the netlink
API in the low-level API (patch 3 in the series) and then have the
bpf_program__* level API be the simple "just attach" one...
We could simplify the low-level one further, of course, for instance by
getting rid of the block stuff entirely, but I don't see much value in
leaving out the support for prio/parent in the bpf_tc_cls_* - we'd have
to make the API extensible so it could be added later anyway, so why not
just include it from the get-go (especially as Kumar has already written
the code?)
-Toke
next prev parent reply other threads:[~2021-03-31 9:52 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-25 11:59 [PATCH bpf-next 0/5] libbpf: Add TC-BPF API Kumar Kartikeya Dwivedi
2021-03-25 11:59 ` [PATCH bpf-next 1/5] tools pkt_cls.h: sync with kernel sources Kumar Kartikeya Dwivedi
2021-03-26 23:25 ` Andrii Nakryiko
2021-03-27 3:54 ` Kumar Kartikeya Dwivedi
2021-03-27 3:58 ` Andrii Nakryiko
2021-03-25 12:00 ` [PATCH bpf-next 2/5] libbpf: add helpers for preparing netlink attributes Kumar Kartikeya Dwivedi
2021-03-26 23:52 ` Andrii Nakryiko
2021-03-25 12:00 ` [PATCH bpf-next 3/5] libbpf: add low level TC-BPF API Kumar Kartikeya Dwivedi
2021-03-28 4:42 ` Andrii Nakryiko
2021-03-28 8:11 ` Kumar Kartikeya Dwivedi
2021-03-30 20:39 ` Andrii Nakryiko
2021-03-30 21:11 ` Toke Høiland-Jørgensen
2021-03-31 9:32 ` Kumar Kartikeya Dwivedi
2021-03-30 21:25 ` Daniel Borkmann
2021-03-30 23:30 ` Alexei Starovoitov
2021-03-31 9:44 ` Kumar Kartikeya Dwivedi
2021-04-02 0:19 ` Daniel Borkmann
2021-04-02 15:27 ` Kumar Kartikeya Dwivedi
2021-04-02 18:32 ` Alexei Starovoitov
2021-04-02 19:08 ` Kumar Kartikeya Dwivedi
2021-04-03 17:47 ` Alexei Starovoitov
2021-04-05 17:27 ` Andrii Nakryiko
2021-04-06 10:06 ` Toke Høiland-Jørgensen
2021-04-14 0:47 ` Andrii Nakryiko
2021-04-14 10:58 ` Toke Høiland-Jørgensen
2021-04-14 22:22 ` Andrii Nakryiko
2021-04-14 22:51 ` Toke Høiland-Jørgensen
2021-04-14 23:19 ` Andrii Nakryiko
2021-04-14 23:32 ` Daniel Borkmann
2021-04-14 23:58 ` Andrii Nakryiko
2021-04-15 22:10 ` Daniel Borkmann
2021-04-15 22:22 ` Andrii Nakryiko
2021-04-15 23:10 ` Daniel Borkmann
2021-04-16 9:01 ` Toke Høiland-Jørgensen
2021-04-15 15:57 ` Toke Høiland-Jørgensen
2021-04-15 21:09 ` Andrii Nakryiko
2021-04-05 17:21 ` Andrii Nakryiko
2021-04-06 19:05 ` Kumar Kartikeya Dwivedi
2021-03-31 9:51 ` Toke Høiland-Jørgensen [this message]
2021-03-29 11:46 ` Vlad Buslov
2021-03-29 12:32 ` Toke Høiland-Jørgensen
2021-03-29 12:49 ` Vlad Buslov
2021-03-25 12:00 ` [PATCH bpf-next 4/5] libbpf: add high " Kumar Kartikeya Dwivedi
2021-03-25 12:00 ` [PATCH bpf-next 5/5] libbpf: add selftests for " Kumar Kartikeya Dwivedi
2021-03-27 2:15 ` Alexei Starovoitov
2021-03-27 15:17 ` Toke Høiland-Jørgensen
2021-03-29 1:26 ` Alexei Starovoitov
2021-03-29 1:45 ` Kumar Kartikeya Dwivedi
2021-03-28 4:32 ` Andrii Nakryiko
2021-03-29 1:40 ` Alexei Starovoitov
2021-03-29 2:38 ` Andrii Nakryiko
2021-03-30 3:28 ` Alexei Starovoitov
2021-03-30 20:28 ` Andrii Nakryiko
2021-03-30 23:27 ` Alexei Starovoitov
2021-03-29 9:56 ` Toke Høiland-Jørgensen
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