Re: [PATCH bpf-next v5 0/9] Introduce unstable CT lookup helpers

On Thu, Dec 30, 2021 at 08:06:56AM 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 (local)

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.

Changelog:
----------

PR [0] and [1] are needed to make BPF CI green for this set.

[0]: https://github.com/kernel-patches/vmtest/pull/53
[1]: https://github.com/libbpf/libbpf/pull/429

[...]

--
Kartikeya