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* [PATCH mptcp-net v5 0/2] mptcp: pm: in-kernel: fullmesh: re-add of the initial subflow endp
@ 2026-10-21  7:03 Abdul Wasey
  2026-10-21  7:03 ` [PATCH mptcp-net v5 1/2] mptcp: pm: in-kernel: fullmesh: skip closed subflows Abdul Wasey
                   ` (2 more replies)
  0 siblings, 3 replies; 6+ messages in thread
From: Abdul Wasey @ 2026-10-21  7:03 UTC (permalink / raw)
  To: mptcp; +Cc: Matthieu Baerts, Mat Martineau, Geliang Tang, Paolo Abeni

With fullmesh endpoints, removing and re-adding the endpoint used by the
initial subflow never creates a new subflow from it: the closed initial
subflow stays in the conn_list, and makes the PM think the remote ID 0
is already used, or picks its reset remote address. If the initial
subflow was the only one, no address is left for the remote ID 0 at all.

Patch 1 fixes that, patch 2 adds tests for it.

Found with a router flapping one of its links: the link carrying the
initial subflow never rejoined the existing connections. Tested on top
of export-net: the new tests fail without patch 1, except the one adding
another endpoint, which already worked and guards against breaking it.
The whole mptcp_join.sh passes with patch 1. Patch 2 uses iptables like
the other tests there: when merged with net-next, it will need the same
conversion to nftables as the others.

Changes in v5:
- Patch 1: when no subflow is left to take the remote ID 0 address from,
  use the remote address of the MPTCP socket, as fill_remote_addr()
  does. Without it, v4 also broke adding another endpoint after the
  removal of the initial one, when it was the only subflow (Sashiko on
  netdev).
- Patch 2: add two tests for the initial subflow alone: re-adding its
  endpoint, and adding another endpoint.
- v4: https://lore.kernel.org/mptcp/20261019190558.465270-1-w453y.me@gmail.com/

Changes in v4:
- Patch 2: only check the joins when the iptables rule has been added
  (Sashiko).
- v3: https://lore.kernel.org/mptcp/20261019185512.458313-1-w453y.me@gmail.com/

Changes in v3:
- Patch 2: use iptables instead of init_nftables(), which is only in
  net-next (Sashiko).
- v2: https://lore.kernel.org/mptcp/20261019180306.382039-1-w453y.me@gmail.com/

Changes in v2:
- Patch 1: also skip the subflows in TCP_CLOSE: the initial subflow can
  be disconnected and its context reset, clearing the 'closing' flag and
  zeroing its remote address (Sashiko).
- Patch 2: validate this case too, by resetting the initial subflow
  before removing its endpoint.
- v1: https://lore.kernel.org/mptcp/20261019170751.200446-1-w453y.me@gmail.com/

Abdul Wasey (2):
  mptcp: pm: in-kernel: fullmesh: skip closed subflows
  selftests: mptcp: join: re-add the initial subflow endp with fullmesh

 net/mptcp/pm_kernel.c                         |  33 +++++-
 .../testing/selftests/net/mptcp/mptcp_join.sh | 108 ++++++++++++++++++
 2 files changed, 140 insertions(+), 1 deletion(-)

-- 
2.43.0


^ permalink raw reply	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2026-10-22 20:10 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-10-21  7:03 [PATCH mptcp-net v5 0/2] mptcp: pm: in-kernel: fullmesh: re-add of the initial subflow endp Abdul Wasey
2026-10-21  7:03 ` [PATCH mptcp-net v5 1/2] mptcp: pm: in-kernel: fullmesh: skip closed subflows Abdul Wasey
2026-10-22 20:10   ` netdev-bot+sashiko
2026-10-21  7:03 ` [PATCH mptcp-net v5 2/2] selftests: mptcp: join: re-add the initial subflow endp with fullmesh Abdul Wasey
2026-10-22 20:10   ` netdev-bot+sashiko
2026-10-21 13:21 ` [PATCH mptcp-net v5 0/2] mptcp: pm: in-kernel: fullmesh: re-add of the initial subflow endp MPTCP CI

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