Currently, it is possible to add a "signal" MPTCP endpoint with a v6
address and a port, or to directly request to send an ADD_ADDR with a v6
address and a port, but such signalling option cannot be sent when TCP
timestamps is used due to a lack of option space. Instead of simply
dropping such ADD_ADDR, the TCP timestamps can be dropped only for this
packet.

- Patches 1-2: small cleanups to avoid computing ADD/RM_ADDR twice.

- Patches 3-4: the new feature, controlled by a new sysctl knob.

- Patch 5: extra checks in the selftests.

- Patches 6-12: refactoring/cleanups: some of them were part of a
  previous patch: "mptcp: pm: clearer ADD_ADDR related helpers names"
  [1].

Link: https://lore.kernel.org/20260415-mptcp-inc-limits-v5-20-e54c3bf80e4e@kernel.org [1]
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
Matthieu Baerts (NGI0) (12):
      mptcp: pm: avoid computing rm_addr size twice
      mptcp: pm: avoid computing add_addr size twice
      mptcp: pm: drop TCP TS with ADD_ADDRv6 + port
      selftests: mptcp: validate ADD_ADDRv6 + TS + port
      selftests: mptcp: always check sent/dropped ADD_ADDRs
      mptcp: pm: use for_each_subflow helper
      mptcp: pm: rename add_entry structure to add_addr
      mptcp: pm: uniform announced addresses helpers
      mptcp: pm: remove add_ prefix from timer
      mptcp: pm: make mptcp_pm_add_addr_send_ack static
      mptcp: pm: avoid using del_timer directly
      mptcp: pm: avoid confusing check_id in del_timer

 Documentation/networking/mptcp-sysctl.rst       |  13 ++
 include/net/mptcp.h                             |   3 +-
 net/ipv4/tcp_output.c                           |   6 +-
 net/mptcp/ctrl.c                                |  18 ++-
 net/mptcp/options.c                             |  33 ++---
 net/mptcp/pm.c                                  | 180 +++++++++++++++---------
 net/mptcp/pm_kernel.c                           |  22 +--
 net/mptcp/pm_userspace.c                        |   6 +-
 net/mptcp/protocol.h                            |  45 ++----
 net/mptcp/subflow.c                             |   4 +-
 tools/testing/selftests/net/mptcp/mptcp_join.sh |  83 +++++------
 11 files changed, 223 insertions(+), 190 deletions(-)
---
base-commit: 23350e342bf2604e09d89ef91d000aef684f593b
change-id: 20260508-mptcp-add-addr6-port-ts-371653e0f843

Best regards,
--  
Matthieu Baerts (NGI0) <matttbe@kernel.org>

Hi Matthieu,

Thank you for your modifications, that's great!

Our CI did some validations and here is its report:

- KVM Validation: normal (except selftest_mptcp_join): Unstable: 1 failed test(s): packetdrill_add_addr ⚠️ 
- KVM Validation: normal (only selftest_mptcp_join): Unstable: 1 failed test(s): selftest_mptcp_join ⚠️ 
- KVM Validation: debug (except selftest_mptcp_join): Unstable: 3 failed test(s): packetdrill_add_addr packetdrill_dss packetdrill_fastopen ⚠️ 
- KVM Validation: debug (only selftest_mptcp_join): Unstable: 1 failed test(s): selftest_mptcp_join ⚠️ 
- KVM Validation: btf-normal (only bpftest_all): Success! ✅
- KVM Validation: btf-debug (only bpftest_all): Success! ✅
- Task: https://github.com/multipath-tcp/mptcp_net-next/actions/runs/26035764291

Initiator: Patchew Applier
Commits: https://github.com/multipath-tcp/mptcp_net-next/commits/8c6b19eac4b4
Patchwork: https://patchwork.kernel.org/project/mptcp/list/?series=1096601


If there are some issues, you can reproduce them using the same environment as
the one used by the CI thanks to a docker image, e.g.:

    $ cd [kernel source code]
    $ docker run -v "${PWD}:${PWD}:rw" -w "${PWD}" --privileged --rm -it \
        --pull always mptcp/mptcp-upstream-virtme-docker:latest \
        auto-normal

For more details:

    https://github.com/multipath-tcp/mptcp-upstream-virtme-docker


Please note that despite all the efforts that have been already done to have a
stable tests suite when executed on a public CI like here, it is possible some
reported issues are not due to your modifications. Still, do not hesitate to
help us improve that ;-)

Cheers,
MPTCP GH Action bot
Bot operated by Matthieu Baerts (NGI0 Core)