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    SubjectRe: [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@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?

    >
    > --
    > Kartikeya

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