[PATCH mptcp-next RFC v4 0/2] mptcp: fallback to TCP on MP_FAIL with a single subflow

[Chenguang Zhao <chenguang.zhao@linux.dev>]

From: Chenguang Zhao <zhaochenguang@kylinos.cn>

As suggested by Paolo, on MP_FAIL reception bound the MP_FAIL
reply and the infinite mapping in the same ACK.

Patch1:
 Add MPFailFallback MIB.

Patch2:
 Makes a pure ACK able to carry an infinite mapping: when
 send_infinite_map is set, mptcp_established_options_dss() fills
 a DSS map with data_len=0 even without a data skb. After the ACK
 that carries both the MP_FAIL reply and that mapping is sent,
 mptcp_try_fallback() is called immediately so the connection leaves
 MPTCP mode without waiting for a later data transmit.

Chenguang Zhao (2):
  mptcp: add MPFailFallback MIB
  mptcp: send MP_FAIL and infinite mapping on the same ACK

 net/mptcp/mib.c      |  1 +
 net/mptcp/mib.h      |  1 +
 net/mptcp/options.c  | 33 ++++++++++++++++++++++++++++++++-
 net/mptcp/pm.c       |  5 +++++
 net/mptcp/protocol.c |  8 +-------
 5 files changed, 40 insertions(+), 8 deletions(-)

--
v3:
 https://lore.kernel.org/all/20260812054653.43799-1-chenguang.zhao@linux.dev/

v2:
 https://lore.kernel.org/all/20260715061830.1057851-1-chenguang.zhao@linux.dev/

v1:
 https://lore.kernel.org/all/20260713064134.914507-1-chenguang.zhao@linux.dev/
-- 
2.25.1