From: Geliang Tang <tanggeliang@kylinos.cn>

v10:
 - rename bpf prog to "mptcp_bpf_iters.c" and change it as
   "cgroup/getsockopt" type. Since another bpf_iter "mptcp_address",
   to traverse all address entries on userspace_pm_local_addr_list of
   an MPTCP socket for implementing the MPTCP BPF path manager, will be
   added in the next set. The test program for "mptcp_address" bpf_iter
   will be added into this "mptcp_bpf_iters.c" file too and also defined
   as "cgroup/getsockopt" type.
 - change all bpf kfunc static as Matt suggested.
 - drop mptcp_subflow_active and mptcp_subflow_set_scheduled from the
   test program as Matt suggested.

v9:
 - rename bpf prog to "mptcp_bpf_iters_subflow.c"
 - drop the helper bpf_mptcp_sk(), it's not used in this test.

v8:
 - Make the test prog in patch 4 more like a bpf packet scheduler.
 - Export more mptcp helpers into BPF in patch 1.

v7:
 - As Martin recently replied, mptcp_stubflow bpf_iter can still be
used in tracing. So go back to the tracing selftest.

v6:
 - add KF_TRUSTED_ARGS flag in patch 2 (Andrii, Martin), then acquire
and release helpers (patch 3) are needed to be implemented.
 - test mptcp_subflow bpf_iter in "cgroup/getsockopt" (patch 5),
instead of testing them in "tracing" (Martin).

v5:
 - update patch 1 as Andrii suggested: if msk is NULL, initialize
kit->msk to NULL in _new() and check it in _next().

v4:
 - squash patch 1/5 and 3/5 in v3 together as Matt suggested.
 - a new squash-to patch to drop mptcp_subflow_active declaration in
   bpf_burst.

v3:
 - drop bpf_iter__mptcp_subflow, __diag_push, __diag_pop and
 __diag_ignore_all
 - drop declarations for bpf kfuncs

v2:
 - update patch 1 as Martin and Andrii suggested.
 - fix warnings and errors reported by MPTCP CI.

This patch set adds a mptcp_subflow type bpf_iter, and self tests.

Geliang Tang (9):
  bpf: Register mptcp common kfunc set
  bpf: Add mptcp_subflow bpf_iter
  bpf: Acquire and release mptcp socket
  selftests/bpf: Add mptcp_subflow bpf_iter test prog
  selftests/bpf: More endpoints for endpoint_init
  selftests/bpf: Add mptcp_subflow bpf_iter subtest
  Squash to "selftests/bpf: Add bpf scheduler test"
  Revert "bpf: Export more bpf_burst related functions"
  Squash to "bpf: Add bpf_mptcp_sched_kfunc_set"

 net/mptcp/bpf.c                               |  93 ++++++++++++-
 net/mptcp/protocol.h                          |   1 -
 .../testing/selftests/bpf/bpf_experimental.h  |   7 +
 .../testing/selftests/bpf/prog_tests/mptcp.c  | 126 +++++++++++++++++-
 tools/testing/selftests/bpf/progs/mptcp_bpf.h |   8 ++
 .../selftests/bpf/progs/mptcp_bpf_iters.c     |  60 +++++++++
 6 files changed, 283 insertions(+), 12 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/progs/mptcp_bpf_iters.c

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2.43.0