From: Gang Yan <yangang@kylinos.cn>

It adds a hook in mptcp_connect, which enables setting socket options
automatically before the connect.

- Patch 1-2 have been reviewed by Paolo before, and ready for merge [1][2].
- Patch 3 let mptcp_setsockopt to take cover all the sockopt levels for
  msk.
- Patch 4 introduces a helper and a hook like tcp does.
- Patch 5 adds a self-test case for bpf_setsockopt in mptcp.

For now, I only used AI to help with grammar optimization of the commit
messages.

[1] https://patchwork.kernel.org/project/mptcp/patch/20260522-sockopt_lock-v5-2-108629a46e98@kylinos.cn/
[2] https://patchwork.kernel.org/project/mptcp/patch/20260522-sockopt_lock-v5-4-108629a46e98@kylinos.cn/

Gang Yan (5):
  mptcp: use sockopt_lock/release_sock in sockopt
  mptcp: reject sockopt requiring ssks' lock in BPF context
  mptcp: enable bpf_setsockopt on the master socket
  mptcp: add TCP_CONNECT_CB sock_ops hook
  selftests: bpf: verify mptcp bpf_setsockopt from TCP_CONNECT_CB

 include/net/mptcp.h                           |   9 ++
 net/core/filter.c                             |   6 +
 net/mptcp/protocol.c                          |   6 +
 net/mptcp/protocol.h                          |  30 +++++
 net/mptcp/sockopt.c                           | 111 +++++++++++-------
 .../testing/selftests/bpf/prog_tests/mptcp.c  |  61 ++++++++++
 .../selftests/bpf/progs/mptcp_setsockopt.c    |  32 +++++
 7 files changed, 213 insertions(+), 42 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/progs/mptcp_setsockopt.c

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2.43.0