From: Daniel Borkmann <daniel@iogearbox.net>
To: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Cc: "Andrii Nakryiko" <andrii.nakryiko@gmail.com>,
bpf <bpf@vger.kernel.org>,
"Jesper Dangaard Brouer" <brouer@redhat.com>,
"Toke Høiland-Jørgensen" <toke@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: Fri, 2 Apr 2021 02:19:29 +0200 [thread overview]
Message-ID: <5d59b5ee-a21e-1860-e2e5-d03f89306fd8@iogearbox.net> (raw)
In-Reply-To: <20210331094400.ldznoctli6fljz64@apollo>
On 3/31/21 11:44 AM, Kumar Kartikeya Dwivedi wrote:
> On Wed, Mar 31, 2021 at 02:55:47AM IST, Daniel Borkmann wrote:
>> 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:
>
> The block variant can be dropped, I'll use the TC_BLOCK/TC_DEV alternative which
> sets parent_id/ifindex properly.
>
>> 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.
>
> I am not opposed to clsact qdisc setup if INGRESS/EGRESS is supplied (not sure
> how others feel about it).
What speaks against it? It would be 100% clear from API side where the prog is
being attached. Same as with tc cmdline where you specify 'ingress'/'egress'.
> We could make direct_action mode default, and similarly choose prio
To be honest, I wouldn't even support a mode from the lib/API side where direct_action
is not set. It should always be forced to true. Everything else is rather broken
setup-wise, imho, since it won't scale. We added direct_action a bit later to the
kernel than original cls_bpf, but if I would do it again today, I'd make it the
only available option. I don't see a reasonable use-case where you have it to false.
> as 1 by default instead of letting the kernel do it. Then you can just pass in
> NULL for bpf_tc_cls_opts and be close to what you're proposing. For protocol we
> can choose ETH_P_ALL by default too if the user doesn't set it.
Same here with ETH_P_ALL, I'm not sure anyone uses anything other than ETH_P_ALL,
so yes, that should be default.
> With these modifications, the equivalent would look like
> bpf_tc_cls_attach(prog_fd, TC_DEV(ifindex, INGRESS), NULL, &id);
Few things compared to bpf_tc_attach(prog_fd, ifindex, {INGRESS,EGRESS}):
1) nit, but why even 'cls' in the name. I think we shouldn't expose such old-days
tc semantics to a user. Just bpf_tc_attach() is cleaner/simpler to understand.
2) What's the 'TC_DEV(ifindex, INGRESS)' macro doing exactly? Looks unnecessary,
why not regular args to the API?
3) Exposed bpf_tc_attach() API could internally call a bpf_tc_attach_opts() API
with preset defaults, and the latter could have all the custom bits if the user
needs to go beyond the simple API, so from your bpf_tc_cls_attach() I'd also
drop the NULL.
4) For the simple API I'd likely also drop the id (you could have a query API if
needed).
> So as long as the user doesn't care about other details, they can just pass opts
> as NULL.
next prev parent reply other threads:[~2021-04-02 0:20 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 [this message]
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
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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