Re: [PATCH mptcp-next v5 06/16] mptcp: implement psock_update_sk_prot for sockmap

[Matthieu Baerts <matttbe@kernel.org>]

On 13/09/2026 12:14, Geliang Tang wrote:
> From: Geliang Tang <tanggeliang@kylinos.cn>
> 
> This patch adds basic MPTCP support for BPF sockmap by implementing the
> psock_update_sk_prot callback (mptcp_bpf_update_proto). This allows MPTCP
> sockets to be added to sockmap and enables the sk_skb stream_verdict
> redirect path via the read_skb callback. Separate protocol structures are
> maintained for IPv4/IPv6 and BASE/TX/RX/TXRX configurations, mirroring
> tcp_bpf_update_proto(). The IPv6 variant is lazily rebuilt via
> mptcp_bpf_check_v6_needs_rebuild() when the underlying protocol ops change.
> 
> MPTCP delegates to the original protocol operations so that MPTCP-specific
> logic (multi-path scheduling in sendmsg, ordered reassembly in recvmsg) is
> preserved. recvmsg is overridden in all BPF configurations with
> mptcp_bpf_recvmsg, which checks the psock ingress queue first and falls
> back to mptcp_recvmsg via the shared __tcp_bpf_recvmsg() helper. sendmsg
> is overridden in the TX/TXRX configurations with mptcp_bpf_sendmsg, which
> processes sk_msg redirect before delegating to mptcp_sendmsg via
> __tcp_bpf_sendmsg().
> 
> Export mptcp_sendmsg, mptcp_recvmsg and mptcp_prot from protocol.c so they
> can be referenced by bpf.c.
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202512261144.DxrvwMS3-lkp@intel.com/
> Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/521
> Cc: Cong Wang <xiyou.wangcong@gmail.com>
> Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
> ---
>  include/net/tcp.h    |   5 ++
>  net/ipv4/tcp_bpf.c   |  29 +++++++---

Probably best to separate this change from the rest: TCP/BPF on one
side, then MPTCP/BPF (and eventually MPTCP only before, just to do the
exports.)

>  net/mptcp/bpf.c      | 129 +++++++++++++++++++++++++++++++++++++++++++
>  net/mptcp/protocol.c |  10 ++--
>  net/mptcp/protocol.h |  18 ++++++

Cheers,
Matt
-- 
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