netdev - Re: [PATCH bpf-next v4 00/10] Introduce unstable CT lookup helpers

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Message-ID: <20211217093612.wfsftv4kuqzotkmn@apollo.legion>
Date:   Fri, 17 Dec 2021 15:06:12 +0530
From:   Kumar Kartikeya Dwivedi <memxor@...il.com>
To:     bpf@...r.kernel.org, netdev@...r.kernel.org,
        netfilter-devel@...r.kernel.org
Cc:     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>,
        Maxim Mikityanskiy <maximmi@...dia.com>,
        Pablo Neira Ayuso <pablo@...filter.org>,
        Florian Westphal <fw@...len.de>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Toke Høiland-Jørgensen <toke@...hat.com>
Subject: Re: [PATCH bpf-next v4 00/10] Introduce unstable CT lookup helpers

On Fri, Dec 17, 2021 at 07:20:21AM IST, Kumar Kartikeya Dwivedi wrote:
> This series adds unstable conntrack lookup helpers using BPF kfunc support.  The
> patch adding the lookup helper is based off of Maxim's recent patch to aid in
> rebasing their series on top of this, all adjusted to work with module kfuncs [0].
>
>   [0]: https://lore.kernel.org/bpf/20211019144655.3483197-8-maximmi@nvidia.com
>
> To enable returning a reference to struct nf_conn, the verifier is extended to
> support reference tracking for PTR_TO_BTF_ID, and kfunc is extended with support
> for working as acquire/release functions, similar to existing BPF helpers. kfunc
> returning pointer (limited to PTR_TO_BTF_ID in the kernel) can also return a
> PTR_TO_BTF_ID_OR_NULL now, typically needed when acquiring a resource can fail.
> kfunc can also receive PTR_TO_CTX and PTR_TO_MEM (with some limitations) as
> arguments now. There is also support for passing a mem, len pair as argument
> to kfunc now. In such cases, passing pointer to unsized type (void) is also
> permitted.
>
> Please see individual commits for details.
>
> Note: BPF CI needs to add the following to config to test the set. I did update
> the selftests config in patch 8, but not sure if that is enough.
>
> 	CONFIG_NETFILTER=y
> 	CONFIG_NF_DEFRAG_IPV4=y
> 	CONFIG_NF_DEFRAG_IPV6=y
> 	CONFIG_NF_CONNTRACK=y
>

Hm, so this is not showing up in BPF CI, is it some mistake from my side? The
last couple of versions produced build time warnings in Patchwork, that I fixed,
which I suspected was the main cause.

There's still one coming from the last patch, but based on [0], I am not sure
whether I should be doing things any differently (and if I do fix it, it also
needs to be done for the functions added before). The warnings are from the 11
new kfuncs I added in net/bpf/test_run.c, for their missing declarations.

Comments?

[0]: https://lore.kernel.org/bpf/20200326235426.ei6ae2z5ek6uq3tt@ast-mbp

> [...]

--
Kartikeya