netdev - Re: [RFC PATCH bpf-next] bpf: Introduce bpf

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Message-ID: <CAADnVQJTJzxzig=1vvAUMXELUoOwm2vXq0ahP4mfhBWGsCm9QA@mail.gmail.com>
Date:   Wed, 2 Jun 2021 11:26:40 -0700
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Kumar Kartikeya Dwivedi <memxor@...il.com>
Cc:     Martin KaFai Lau <kafai@...com>,
        Toke Høiland-Jørgensen <toke@...hat.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        David Miller <davem@...emloft.net>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        John Fastabend <john.fastabend@...il.com>,
        Lorenz Bauer <lmb@...udflare.com>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>,
        bpf <bpf@...r.kernel.org>, kernel-team <kernel-team@...com>
Subject: Re: [RFC PATCH bpf-next] bpf: Introduce bpf_timer

On Wed, Jun 2, 2021 at 11:14 AM Kumar Kartikeya Dwivedi
<memxor@...il.com> wrote:
>
> On Wed, Jun 02, 2021 at 11:24:36PM IST, Martin KaFai Lau wrote:
> > On Wed, Jun 02, 2021 at 10:48:02AM +0200, Toke Høiland-Jørgensen wrote:
> > > Alexei Starovoitov <alexei.starovoitov@...il.com> writes:
> > >
> > > >> > In general the garbage collection in any form doesn't scale.
> > > >> > The conntrack logic doesn't need it. The cillium conntrack is a great
> > > >> > example of how to implement a conntrack without GC.
> > > >>
> > > >> That is simply not a conntrack. We expire connections based on
> > > >> its time, not based on the size of the map where it residents.
> > > >
> > > > Sounds like your goal is to replicate existing kernel conntrack
> > > > as bpf program by doing exactly the same algorithm and repeating
> > > > the same mistakes. Then add kernel conntrack functions to allow list
> > > > of kfuncs (unstable helpers) and call them from your bpf progs.
> > >
> > > FYI, we're working on exactly this (exposing kernel conntrack to BPF).
> > > Hoping to have something to show for our efforts before too long, but
> > > it's still in a bit of an early stage...
> > Just curious, what conntrack functions will be made callable to BPF?
>
> Initially we're planning to expose the equivalent of nf_conntrack_in and
> nf_conntrack_confirm to XDP and TC programs (so XDP one works without an skb,
> and TC one works with an skb), to map these to higher level lookup/insert.

To make sure we're on the same page...
I still strongly prefer to avoid exposing conntrack via stable helpers.
Pls use kfunc and unstable interface.