This small patchset is about avoid infinite recursion in TCP header option callbacks
and bpf-tcp-cc callbacks via TCP_NODELAY setsockopt.

v4:
 - Fix the test case for TCP header option callbacks (Martin and Jiayuan)
 - Reject TCP_NODELAY in bpf-tcp-cc callbacks (AI and Martin)
 - Add a test case for bpf-tcp-cc

v3:
 - Remove CONFIG_INET check and add comment (Martin and Jiayuan)
 - Fix the test case (Martin)
 https://lore.kernel.org/bpf/20260417092035.2299913-1-kafai.wan@linux.dev/

v2:
 - Reject TCP_NODELAY in bpf_sock_ops_setsockopt() (AI and Martin)
 https://lore.kernel.org/bpf/20260416112308.1820332-1-kafai.wan@linux.dev/

v1:
 https://lore.kernel.org/bpf/20260414112310.1285783-1-kafai.wan@linux.dev/

---
KaFai Wan (4):
  bpf: Reject TCP_NODELAY in TCP header option callbacks
  bpf: Reject TCP_NODELAY in bpf-tcp-cc
  selftests/bpf: Test TCP_NODELAY in TCP hdr opt callbacks
  selftests/bpf: Verify bpf-tcp-cc rejects TCP_NODELAY

 include/linux/bpf.h                           |  1 +
 net/core/filter.c                             | 30 +++++++++++++++++++
 net/ipv4/bpf_tcp_ca.c                         |  2 +-
 .../selftests/bpf/prog_tests/bpf_tcp_ca.c     |  4 +++
 .../bpf/prog_tests/tcp_hdr_options.c          |  6 ++++
 tools/testing/selftests/bpf/progs/bpf_cubic.c | 12 ++++++++
 .../bpf/progs/test_misc_tcp_hdr_options.c     | 15 +++++++++-
 7 files changed, 68 insertions(+), 2 deletions(-)

-- 
2.43.0