From: Geliang Tang <tanggeliang@kylinos.cn>

NVMe over MPTCP relies on SO_LINGER, SO_PRIORITY, SO_REUSEADDR, TCP_SYNCNT,
TCP_NODELAY, IP_TOS, and SO_BINDTODEVICE. This series contains fixes to
make all of them work correctly, and adds tclass support for it.

v6:
 - Remove NVMe patches from this series.
 - Remove v4-mapped address patches from this series.
 - Squash "ipv6: extract and export ip6_sock_set_tclass helper" into
   "mptcp: sockopt: implement IPV6_TCLASS".
 - Patch 4: move tcp_sock_set_syncnt before __mptcp_setsockopt_set_val.

v5:
 - Include Gang Yan's TCP_MAXSEG cleanup.
 - Include two v4-mapped addr fixes.
 - Patch 9, set rcv_flowinfo to 0 for v4-mapped addr.
 - Patch 11, use rcv_flowinfo instead of np->tclass.
 - All comments from Sashiko on v4 regarding "CONFIG_IPV6=m" are false
   positives.
 - https://patchwork.kernel.org/project/mptcp/cover/cover.1786159812.git.tanggeliang@kylinos.cn/

v4:
 - patch 1: skip ssk->sk_bound_dev_if = local->ifindex when local->ifindex
   is 0, so __mptcp_subflow_connect() doesn't overwrite the inherited
   SO_BINDTODEVICE binding.
 - patch 4: assign tcp_sock_set_syncnt()'s return to ret so an invalid
   TCP_SYNCNT is propagated, not silently dropped.
 - patch 6: skip IPV6_TCLASS setsockopt/getsockopt paths on AF_INET
   sockets/subflows (inet6_sk is NULL there).
 - patch 7: treat IPv4-mapped IPv6 as AF_INET for the TOS/tclass path.
 - patch 9: gate ip6_sock_set_tclass() behind sk_family == AF_INET6 and
   IS_ENABLED(CONFIG_IPV6) to avoid IPv4 NULL-deref and link failure when
   CONFIG_IPV6 is off.
 - patch 10: gate tclass on sk_family, skip IPv6 branch for IPv4-mapped
   connections, wrap IPv6 in CONFIG_IPV6.
 - https://patchwork.kernel.org/project/mptcp/cover/cover.1785378180.git.tanggeliang@kylinos.cn/

v3:
 - include tclass patches.
 - I also included three NVMe patches here because they have dependencies.
 - https://patchwork.kernel.org/project/mptcp/cover/cover.1785238723.git.tanggeliang@kylinos.cn/

v2:
 - Drop "mptcp: don't reset dst when setting default 0 tos"
   and "selftests: mptcp: sockopt: cover LINGER, REUSEADDR,
   PRIORITY, NODELAY, SYNCNT": the 'if (val > 0)' guard
   blocked the legitimate "reset to 0" path, and the test
   only ran val_in=1, missing the SK_CAN_REUSE "any non-zero
   -> 1" normalization.
 - mptcp: bump setsockopt_seq for subflow-only socket options,
   so secondary subflows created via MP_JOIN re-sync
   sk_reuse / sk_reuseport / sk_bound_dev_if from msk.
 - mptcp: copy the subflow's TOS to the msk on accept
   (alongside the existing ssk->rcv_tos copy), so MP_JOIN'd
   subflows inherit the reflected outgoing TOS.
 - mptcp: propagate sk_reuseport to subflows via
   sync_socket_options, so secondary subflows inherit
   SO_REUSEPORT, not just SO_REUSEADDR.
 - mptcp: tighten TCP_SYNCNT bounds check
   ('val < 1 || val > MAX_TCP_SYNCNT'), so out-of-bounds
   values are rejected even when msk has no subflows yet
   (where __mptcp_setsockopt_set_val would otherwise return 0
   without invoking the set_val callback).
 - https://patchwork.kernel.org/project/mptcp/cover/cover.1785054808.git.tanggeliang@kylinos.cn/

v1:
 - https://patchwork.kernel.org/project/mptcp/cover/cover.1784985085.git.tanggeliang@kylinos.cn/

David 'equinox' Lamparter (1):
  mptcp: sockopt: implement IPV6_TCLASS

Gang Yan (1):
  mptcp: take TCP_MAXSEG handling into setsockopt_set_val

Geliang Tang (4):
  mptcp: handle TCP_MAXSEG getsockopt in common case
  mptcp: inherit sk_reuse and fix dev bind override
  mptcp: add TCP_SYNCNT setsockopt/getsockopt
  mptcp: copy subflow's tos/tclass to msk on accept

 include/net/ipv6.h       |  2 +
 net/ipv6/ipv6_sockglue.c | 23 +++++++----
 net/mptcp/protocol.c     | 16 ++++++++
 net/mptcp/sockopt.c      | 82 +++++++++++++++++++++++++++++++++++++---
 net/mptcp/subflow.c      |  4 +-
 5 files changed, 112 insertions(+), 15 deletions(-)

-- 
2.53.0

Hi Geliang,

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): Success! ✅
- KVM Validation: normal (only selftest_mptcp_join): Success! ✅
- KVM Validation: debug (except selftest_mptcp_join): Success! ✅
- KVM Validation: debug (only selftest_mptcp_join): Success! ✅
- 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/31994206151

Initiator: Patchew Applier
Commits: https://github.com/multipath-tcp/mptcp_net-next/commits/f3f2396df333
Patchwork: https://patchwork.kernel.org/project/mptcp/list/?series=1146924


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)

Hi Matt,

On Mon, 2026-08-17 at 05:11 +0000, MPTCP CI wrote:
> Hi Geliang,
> 
> 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): Success! ✅
> - KVM Validation: normal (only selftest_mptcp_join): Success! ✅
> - KVM Validation: debug (except selftest_mptcp_join): Success! ✅
> - KVM Validation: debug (only selftest_mptcp_join): Success! ✅
> - KVM Validation: btf-normal (only bpftest_all): Success! ✅
> - KVM Validation: btf-debug (only bpftest_all): Success! ✅

Sashiko has already reviewed this v6 and has no further comments. If
you have time, could you please take a look and review it as well?

Thanks,
-Geliang

> - Task:
> https://github.com/multipath-tcp/mptcp_net-next/actions/runs/31994206151
> 
> Initiator: Patchew Applier
> Commits:
> https://github.com/multipath-tcp/mptcp_net-next/commits/f3f2396df333
> Patchwork:
> https://patchwork.kernel.org/project/mptcp/list/?series=1146924
> 
> 
> 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)