From: Geliang Tang <tanggeliang@kylinos.cn>

v6:
 - patch 2: add Fixes tag, and use '-net' prefix.
 - patch 3: remove poll() call, check SIOCINQ directly after accept().
 - patch 6: add READ_ONCE() for msk->flags and msk->cb_flags reads in
   mptcp_rate_check_app_limited() to annotate intentionally racy accesses.
 - update commit logs.

v5:
 - patch 2: new patch - rewrite mptcp_inq_hint() to use mptcp_data_avail()
   instead of ack_seq - map_seq, completely avoiding TFO overflow issues.
 - patch 3: new patch - add TFO SIOCINQ overflow detection in
   mptcp_connect test to catch INT_MAX returns on TFO connections.
 - patch 4: mptcp_inq() now returns INT_MAX instead of 0 when avail >=
   INT_MAX. Removed mptcp_inq_hint() changes (moved to patch 2).
 - patch 6: replace mptcp_rtx_head() check with MPTCP_WORK_RTX and
   MPTCP_RETRANSMIT flag checks in mptcp_rate_check_app_limited() to
   properly detect pending retransmissions without data race issues.
 - https://patchwork.kernel.org/project/mptcp/cover/cover.1793676064.git.tanggeliang@kylinos.cn/

v4:
 - patch 2: fix mptcp_inq_hint() to return 0 instead of INT_MAX on
   passive TFO overflow (ack_seq - map_seq >= INT_MAX).
 - patch 4: add mptcp_rtx_head(sk) to the early-return check in
   mptcp_rate_check_app_limited() so pending retransmissions also
   prevent false app-limited marking.
 - patch 5: update comment message.
 - https://patchwork.kernel.org/project/mptcp/cover/cover.1793588257.git.tanggeliang@kylinos.cn/

v3:
 - patch 2: drop DATA_FIN subtraction in mptcp_inq(), remove the
   intermediate 'answ' variable and return (unsigned int)avail
   directly. Update commit message accordingly.
 - https://patchwork.kernel.org/project/mptcp/cover/cover.1793324316.git.tanggeliang@kylinos.cn/

v2:
 - drop the patch "prevent dummy DATA_FIN on RST in fallback mode".
 - keep mptcp_inq_hint in mptcp_ioctl unchanged.
 - use mptcp_data_avail in mptcp_inq.
 - add msk_owned_by_me check in mptcp_sendmsg_locked.
 - https://patchwork.kernel.org/project/mptcp/cover/cover.1793258749.git.tanggeliang@kylinos.cn/

v1:
 - https://patchwork.kernel.org/project/mptcp/cover/cover.1792999988.git.tanggeliang@kylinos.cn/

This series was previously posted as part of "Reduce the differences
between TCP and MPTCP for TLS usage" v15. It creates the mptcp_inq()
and mptcp_sendmsg_locked() interfaces that are required for the upcoming
MPTCP kTLS and MPTCP sockmap implementations.

The series has been rebased and no longer depends on Paolo's CB layout
refactoring patches (mptcp: drop the mptcp_ooo_try_coalesce() helper,
mptcp: drop the cant_coalesce CB field, mptcp: remove CB offset field,
mptcp: sync mptcp skb cb layout with tcp one, mptcp: defer read_sock
cleanup to mptcp_worker). Those patches are more complex and will be
sent in a separate series.

Patch overview:

1. mptcp: update mptcp_check_readable
 - Align with TCP's sock_is_readable for better TLS compatibility

2. mptcp: prevent dummy DATA_FIN on RST in fallback mode
 - Fix semantic issue where RST on fallback connections would create
   dummy DATA_FIN, causing unnecessary state transitions
 - Add sk_err check to subflow_is_done() to distinguish abortive
   closes (RST) from clean closes (FIN)

3. mptcp: implement peek_len for proto_ops
 - Add mptcp_inq() to report readable bytes at MPTCP level
 - Wire into .peek_len proto_ops for both IPv4 and IPv6
 - Handle 32-bit torn reads by returning 0 instead of INT_MAX
 - Prepare for TLS strparser integration

4. mptcp: add sendmsg_locked to proto_ops
 - Split mptcp_sendmsg() into locked/unlocked variants
 - Expose .sendmsg_locked in proto_ops for TLS send path

5. mptcp: track app-limited state in mptcp_sendmsg
 - Add mptcp_rate_check_app_limited() to mark subflows as app-limited
 - Bail out when MPTCP has unsent data (write_seq != snd_nxt or
   mptcp_send_head() != NULL) to avoid false app-limited marking
 - Enable accurate delivery rate estimation for BBR

6. selftests: mptcp: sockopt: check app_limited
 - Add regression test for app-limited accounting
 - Verify tcpi_delivery_rate_app_limited == 1 after small transfers

Gang Yan (1):
  mptcp: update mptcp_check_readable

Geliang Tang (6):
  mptcp: fix TFO SIOCINQ overflow in mptcp_inq_hint
  selftests: mptcp: connect: check TFO SIOCINQ overflow
  mptcp: implement peek_len for proto_ops
  mptcp: add sendmsg_locked to proto_ops
  mptcp: track app-limited state in mptcp_sendmsg
  selftests: mptcp: sockopt: check app_limited

 net/mptcp/protocol.c                          | 96 +++++++++++++++----
 .../selftests/net/mptcp/mptcp_connect.c       | 11 +++
 .../selftests/net/mptcp/mptcp_sockopt.c       |  5 +
 3 files changed, 93 insertions(+), 19 deletions(-)

-- 
2.55.0