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Message-ID: <CAEf4BzaMsixmrrgGv6Qr68Ytq8k9W+WP6m4Vdb1wDhDFBKStgw@mail.gmail.com>
Date: Tue, 30 Mar 2021 13:39:27 -0700
From: Andrii Nakryiko <andrii.nakryiko@...il.com>
To: Kumar Kartikeya Dwivedi <memxor@...il.com>
Cc: bpf <bpf@...r.kernel.org>,
Jesper Dangaard Brouer <brouer@...hat.com>,
Toke Høiland-Jørgensen <toke@...hat.com>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Andrii Nakryiko <andrii@...nel.org>,
Martin KaFai Lau <kafai@...com>,
Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
John Fastabend <john.fastabend@...il.com>,
KP Singh <kpsingh@...nel.org>, Shuah Khan <shuah@...nel.org>,
"David S. Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>,
Jesper Dangaard Brouer <hawk@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
open list <linux-kernel@...r.kernel.org>,
Networking <netdev@...r.kernel.org>,
"open list:KERNEL SELFTEST FRAMEWORK"
<linux-kselftest@...r.kernel.org>
Subject: Re: [PATCH bpf-next 3/5] libbpf: add low level TC-BPF API
On Sun, Mar 28, 2021 at 1:11 AM Kumar Kartikeya Dwivedi
<memxor@...il.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?
>
> --
> Kartikeya
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