Re: [PATCH mptcp-net mptcp-next v4 00/15] mptcp: pm: drop TCP TS with ADD_ADDRv6 + port

[Matthieu Baerts <matttbe@kernel.org>]

Hi Mat,

On 30/05/2026 04:12, Mat Martineau wrote:
> On Fri, 29 May 2026, Matthieu Baerts (NGI0) wrote:
> 
>> 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.
>>
>> - Patch 1: fix for PREEMPT_RT kernels, for -net.
>>
>> - Patches 2-4: small cleanups to avoid computing ADD/RM_ADDR twice.
>>
>> - Patches 5-8: the new feature, controlled by a new sysctl knob.
>>
>> - Patch 9: extra checks in the selftests.
>>
>> - Patches 10-15: refactoring/cleanups: some of them were part of a
>>  previous patch: "mptcp: pm: clearer ADD_ADDR related helpers names"
>>  [1].
>>
>> Note that the mptcp/add_addr/add_addr6_port_ts_server.pkt packetdrill
>> test is supposed to fail with this series, until this PR is applied:
>>
>>  https://github.com/multipath-tcp/packetdrill/pull/198
>>
>> Link: https://lore.kernel.org/20260415-mptcp-inc-limits-v5-20-
>> e54c3bf80e4e@kernel.org [1]
>> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
>> ---
>> Changes in v4:
>> - Patches 2-4: uniform "size" type: signed for all suboptions. (Mat)
>> - Dropped previous patch 16.
>> - Link to v3: https://patch.msgid.link/20260520-mptcp-add-addr6-port-
>> ts-v3-0-bffa658a7678@kernel.org
> 
> Hi Matthieu -
> 
> Thank you for the updates in v4, all of my concerns are addressed and I
> agree that this approach to fitting ADD_ADDR headers w/ IPv6 seems like
> the best tradeoff.
> 
> I'll also give a +1 on the packetdrill PR.

Thank you! Merged!
> For the series:
> 
> Reviewed-by: Mat Martineau <martineau@kernel.org>

Thank you for the review! Now in our tree:

New patches for t/upstream-net and t/upstream:
- c619bf382586: mptcp: pm: avoid sleeping while holding rcu_read_lock
- Results: ba5ea3e35898..b744d5cbf545 (export-net)
- Results: 24c473fa6c91..0a3014718f01 (export)

Tests are now in progress:

- export-net:
https://github.com/multipath-tcp/mptcp_net-next/commit/8f01bd3c80a4051904fdb16bc4a7d2d56e01b102/checks

New patches for t/upstream:
- 140b3313d086: mptcp: options: suboptions sizes can be negative
- ecb59042f997: mptcp: pm: avoid computing rm_addr size twice
- e152c63b3234: mptcp: pm: avoid computing add_addr size twice
- 3e1f23bf6d20: mptcp: introduce add_addr_v6_port_drop_ts sysctl knob
- be190e710733: tcp: allow mptcp to drop TS for some packets
- 2bbbbbf511cf: mptcp: pm: drop TCP TS with ADD_ADDRv6 + port
- 12de239a0b82: selftests: mptcp: validate ADD_ADDRv6 + TS + port
- a701782ba7ce: selftests: mptcp: always check sent/dropped ADD_ADDRs
- f72cd39ee480: mptcp: pm: use for_each_subflow helper
- 29db124b818c: mptcp: pm: rename add_entry structure to add_addr
- 35e6e38f8cad: mptcp: pm: uniform announced addresses helpers
- 5b33e846c45a: mptcp: pm: remove add_ prefix from timer
- 1c5f13b9f12e: mptcp: pm: make mptcp_pm_add_addr_send_ack static
- 54551d64573b: mptcp: pm: avoid using del_timer directly
- Results: 0a3014718f01..75370a1de11f (export)

Tests are now in progress:

- export:
https://github.com/multipath-tcp/mptcp_net-next/commit/228692121494a157d7050d141422c9b49c19ca25/checks

Cheers,
Matt
-- 
Sponsored by the NGI0 Core fund.