Re: [PATCH bpf-next 3/5] libbpf: add low level TC-BPF API

[Kumar Kartikeya Dwivedi]

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!

--
Kartikeya