From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792720744; b=1W2DL6ZztW2oj+Sb2diVSyyPY/OIfxmPiVSWpfNO6ufP4RzuSmWUJJoLzYvhghma5UZW judsGVNj1/v31esW4TZjcUvWRTMeYhyYO/ZzB0feuYZmAKL1DTQhba3rl1BL3DipEVYGz kJYs4V1N5+8yuCfyBmPR3c0MFEwVktcJXIFCJhCNSqjb/xfVuTojbOLxFTY+utRj6wV+1 gxub/obkEPrYst/RvtvRCc+lb4tTGEHanqgld441grb+cxR64i6P945NpF5Egl+gO8jGY dLtXPfdgbWchKdppzWW9mOs6qiIeFpUE45kjfTNAC+YacDDEAjhZeiMHIbNDRZBAJvQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792720744; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Transfer-Encoding; bh=xqae1ij187chaofVibg+2/Vx7I0VDT0ILWq93Y5yqOU=; b=cuYc1QHDRW27fZP9PhIhfmFnMGPF9NXtp03ueNZrHqJC28+NwlvPHVpq+jLgvG22OhAr Hqtentk8WV3e38fRzaYaD2LiSLZ/XnT8BmDgPNlmplC3f6ygU/s4q/VKaYn9OxR4IEl1E wGQ6bLNl7WAO5qw6yzXrxok4lCCvxP4HPaZAUPxEGd7TbY+ENZ+RBCDd6sEIIXP3c1BIN x84B4U2MMYzFRwOPnnnrgf0+KE4UDjSTD9hMxCwqEZ0tLjlsvhMQrckuAUFqFtLluZRTi v3PdImHWwXUj4Ck1yrZlzGcVvnGT9tqzU5shxikhGnh7Sz3JQhj69EwAE/IjOf3haBA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=HHvcxPCD; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A7ACC606A319 for ; Fri, 23 Oct 2026 01:59:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=HHvcxPCD Received: by smtp.kernel.org (Postfix) with ESMTPSA id 696AD1F01825; Fri, 23 Oct 2026 01:59:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792720743; bh=xqae1ij187chaofVibg+2/Vx7I0VDT0ILWq93Y5yqOU=; h=From:To:Cc:Subject:Date; b=HHvcxPCDT1Msc9IuAhhZzuaRQnFlo1u9CPb23l/+qRlb5qt26E4PI8MkvGtLKNxwp mvsZnf+l/Rm6AgmCW5a8AVksbjo/9r4f61AHcpII/Wvfg/vhHDPP0aHcQq7BmEuWbK KtLmNRPQJYIyPTFTPYtJSzmg1bNNxsqLDi6MD278yRsXrHUMVMR9KFq8hok19th3Fl ArQ+6mYx/jb6uXs1x1TpWBmeUELsgMNHKCeNo4SXaLXy+3c/ntD/O5tvUTpCCTeS7K jUog8lh7z7KC/9RlnX2NBdQ8rq5UxoLa419Mx/UBq9NgH/L052uxSGQxjCyrAhY3ZU /i2D7ODjI1EYw== From: Geliang Tang To: mptcp@lists.linux.dev Cc: Geliang Tang Subject: [PATCH mptcp-next v15 00/11] Reduce the differences between TCP and MPTCP for TLS usage Date: Fri, 23 Oct 2026 09:58:41 +0800 Message-ID: X-Mailer: git-send-email 2.55.0 X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Geliang Tang v15: - Patch 2: drop mptcp_data_lock() in mptcp_inq_hint(), use READ_ONCE() and __test_and_clear_bit() instead. This issue is unrelated to this series and will be addressed in a separate patch later. - Patch 5: Guard mptcp_cleanup_rbuf() with read_copied > 0. Initialize/ reset msk->read_copied. Drop redundant mptcp_recv_skb() in __mptcp_read_sock(). - Patch 6: simplify memory ordering, drop smp_mb()/smp_rmb(), keep existing smp_mb__before_atomic(). Check SOCK_DONE inline. - Patch 9: drop tcp_sock_rate_check_app_limited() split, call tcp_rate_check_app_limited() directly as Paolo suggested. Add write_seq != snd_nxt early bail-out. - Patch 10: wrap assertion behind expect_all_features(). v14: - v13 can no longer be applied to the export branch, so it has been rebased here with the following corrections: - Patch 2: move locking in mptcp_inq_hint() to avoid races with ack_seq change from patch 3 to here. Update commit log. - Patch 3: add mptcp_data_lock() in __mptcp_move_skb() around copied_seq update. Remove local delta variable in __mptcp_ofo_queue(). Initialize msk->copied_seq to 0 in mptcp_propagate_state() fallback path. - Patch 4: add map_seq64 comparison in __mptcp_try_coalesce() for 64-bit sequence consistency. - New patch 11: rename mptcp_check_readable to mptcp_stream_is_readable, and align with TCP by calling sk_is_readable() for KTLS support. - https://patchwork.kernel.org/project/mptcp/cover/cover.1790734083.git.tanggeliang@kylinos.cn/ v13: - use smp_mb instead of smp_mb__before_atomic in mptcp_check_data_fin. - https://patchwork.kernel.org/project/mptcp/cover/cover.1788245079.git.tanggeliang@kylinos.cn/ v12: - Move sock_set_flag(SOCK_DONE) to after smp_mb__before_atomic() in mptcp_check_data_fin() and reuse the existing barrier rather than adding a new smp_wmb(). - Sample SOCK_DONE before smp_rmb() in mptcp_inq_hint() and mptcp_inq(), so the smp_rmb() only orders SOCK_DONE read relative to the subsequent ack_seq/copied_seq reads. - https://patchwork.kernel.org/project/mptcp/cover/cover.1788171508.git.tanggeliang@kylinos.cn/ v11: - __mptcp_move_skb(): gate __mptcp_sync_rcv_sequence() on test_and_clear_bit(MPTCP_SYNC_SEQ) so the dummy mapping is only re-based after ack_seq = iasn. - a new patch to set and test SOCK_DONE. - use SOCK_DONE in mptcp_inq_hint() and mptcp_inq(). - https://patchwork.kernel.org/project/mptcp/cover/cover.1788099847.git.tanggeliang@kylinos.cn/ v10: - Drop "mptcp: use atomic64_t for locklessly accessed u64 fields" (v9 patch 1) and the squash to bpf_burst test (v9 patch 11). Series reduced from 11 to 9 patches. - Revert all atomic64_read()/atomic64_set() on msk->ack_seq back to plain reads and WRITE_ONCE() in patches 1-4. Remove the local u64 ack_seq variables that only existed to hold atomic64_read() results. - mptcp_inq_hint: move test_bit(MPTCP_SYNC_SEQ) inside mptcp_data_lock() to close the race between the flag check and the ack_seq read. Revert atomic64_read() to plain msk->ack_seq under the lock. - mptcp_inq (patch 6): use READ_ONCE() for both ack_seq and copied_seq instead of atomic64_read(). Add comment for the FIN subtraction, mirroring tcp_inq(). Update commit log. - https://patchwork.kernel.org/project/mptcp/cover/cover.1787888115.git.tanggeliang@kylinos.cn/ v9: - Extend atomic64_t conversion from only msk->ack_seq to all locklessly accessed u64 fields: write_seq, snd_nxt, snd_una, wnd_end, bytes_received, bytes_consumed. - Add mptcp_data_lock() in mptcp_inq_hint() to read ack_seq and copied_seq atomically. - Add read_copied field and drain it under mptcp_data_lock() in mptcp_read_complete() to fix the BH vs worker data race. - New patches: mptcp_inq/peek_len and sendmsg_locked proto_ops. - Squash to "selftests/bpf: Add bpf_burst scheduler & test". - https://patchwork.kernel.org/project/mptcp/cover/cover.1787827525.git.tanggeliang@kylinos.cn/ v8: - check MPTCP_SYNC_SEQ in mptcp_inq_hint: if (hint_val >= INT_MAX) { if (test_bit(MPTCP_SYNC_SEQ, &msk->cb_flags)) return 0; return INT_MAX; } - rename mptcp_sock_rate_check_app_limited to mptcp_rate_check_app_limited. - https://patchwork.kernel.org/project/mptcp/cover/cover.1787644449.git.tanggeliang@kylinos.cn/ v7: - Patch 1 is a new one to fix the existing issue Sashiko mentioned - using atomic64_t for msk->ack_seq. - Fix the map_subflow_seq setting in fallback mode in patch 4. - https://patchwork.kernel.org/project/mptcp/cover/cover.1787537436.git.tanggeliang@kylinos.cn/ v6: - Memory ordering for MPTCP_SYNC_SEQ: Add smp_wmb() before set_bit() in subflow_set_remote_key() and smp_rmb() after test_and_clear_bit() in __mptcp_move_skb() and mptcp_release_cb() to prevent data races on weakly-ordered architectures, ensuring ack_seq updates are visible before the flag is set and readers see the updated sequence after observing the flag. - Lockdep nested locking: Use lock_sock_fast_nested(ssk) instead of lock_sock_fast(ssk) in mptcp_sock_rate_check_app_limited() to suppress false positive recursive locking warnings when acquiring subflow socket locks while holding the parent MPTCP socket lock. - Receive window advertisement order: Swap mptcp_rcv_space_adjust() and mptcp_cleanup_rbuf() in mptcp_read_complete() to expand the receive buffer before evaluating window updates, ensuring ACKs advertise the new (larger) window size instead of delaying the advertisement until the next cycle. - https://patchwork.kernel.org/project/mptcp/cover/cover.1787446274.git.tanggeliang@kylinos.cn/ v5: - only patch 3 changed. - Fallback offset underflow: Initialize MPTCP sequence space to 0 in mptcp_propagate_state() when mp_opt == NULL, ensuring SKB's map_seq starts from 0 to match msk->copied_seq and prevent offset calculation underflow in fallback mode. - Stale peek_seq: Move peek_seq recomputation into the mptcp_move_skbs() continue path and add another recomputation after sk_wait_data(), ensuring peek_seq stays synchronized with msk->copied_seq updates from MPTCP_SYNC_SEQ processing in both paths. - https://patchwork.kernel.org/project/mptcp/cover/cover.1787368526.git.tanggeliang@kylinos.cn/ v4: - mptcp_recvmsg: move the peek_seq recompute from after sk_wait_data() to before the mptcp_move_skbs() continue check. mptcp_move_skbs() -> __mptcp_move_skb() may shift the head skb's map_seq to the IASN frame via __mptcp_sync_rcv_sequence(); if 'continue' then exits the loop, the recompute is skipped, and the next __mptcp_recvmsg_mskq() computes offset with peek_seq in the old frame minus map_seq in the new frame. The underflow makes the offset test fail and the skb is skipped (and mptcp_recv_skb() actually frees the TFO skb via mptcp_eat_recv_skb()). - Make all three MPTCP_SYNC_SEQ bit accesses atomic: - subflow_set_remote_key: __set_bit -> set_bit - __mptcp_move_skb: __test_and_clear_bit -> test_and_clear_bit - mptcp_release_cb: __test_and_clear_bit -> test_and_clear_bit The flag is set in BH under mptcp_data_lock() (msk slock held) and cleared in user context under lock_sock() slow path (only owned=1, slock not held). The non-atomic RMW on the two sides races, which can lose the IASN sync. - https://patchwork.kernel.org/project/mptcp/cover/cover.1787295147.git.tanggeliang@kylinos.cn/ v3: - Patch 2, handle "offset" in __mptcp_sync_rcv_sequence(). - Patch 3, update __mptcp_move_skb() in response to Sashiko comments: if (__test_and_clear_bit(MPTCP_SYNC_SEQ, &msk->cb_flags)) msk->copied_seq += mptcp_iasn(msk); - Patch 4, replace after64() to after() in mptcp_prune_ofo_queue(). The pre-existing issue raised by Sashiko regarding changing the type of ack_seq to atomic64_t is not addressed in this series. - https://patchwork.kernel.org/project/mptcp/cover/cover.1786445142.git.tanggeliang@kylinos.cn/ v2: - Patch 3, updated in response to Sashiko comments: if (unlikely(msk->rcvd_dummy_seq)) { msk->copied_seq += mptcp_iasn(msk); __mptcp_sync_rcv_sequence(sk); /* Release cb() would otherwise re-base copied_seq * again. */ test_and_clear_bit(MPTCP_SYNC_SEQ, &msk->cb_flags); } /* Skip the already peeked data. */ if (offset >= skb->len) { *last = skb; continue; } - Patch 5, replaced with Paolo's patch. - Patch 6, 7, new patches addressing app-limited conditions. - The patch "trim the duplicated skb head at receive enqueue" has been dropped, as it is no longer needed after Paolo updated the "mptcp: out-of-order queue pruning" series. - https://patchwork.kernel.org/project/mptcp/cover/cover.1786158416.git.tanggeliang@kylinos.cn/ v1: - https://patchwork.kernel.org/project/mptcp/cover/cover.1785150300.git.tanggeliang@kylinos.cn/ The goal of this series is to reduce the differences between TCP and MPTCP for TLS usage, in preparation for adding TLS over MPTCP support in the future. In previous versions [1], a struct tls_prot_ops was defined to represent the interface differences between TCP and MPTCP, which contained the following callbacks: struct sk_buff *(*recv_skb)(struct sock *sk, u32 *off); bool (*lock_is_held)(struct sock *sk); void (*read_done)(struct sock *sk, size_t len); u32 (*get_skb_seq)(struct sk_buff *skb); int (*skb_get_header)(const struct sk_buff *skb, int offset, void *to, int len); bool (*epollin_ready)(const struct sock *sk); void (*check_app_limited)(struct sock *sk); In reality, some of these callbacks are unnecessary. This series aims to eliminate the get_skb_seq(), skb_get_header(), and lock_is_held() callbacks. The first four patches come from Paolo's "mptcp: address stall under memory pressure" series v5 [2], with only minor cleanup from my side. They remove the CB offset field and sync the MPTCP skb CB layout with the TCP one, so that we can obtain the TCP or MPTCP sequence number in a unified way, e.g.: struct tls_skb_cb { u32 seq; }; #define TLS_SKB_CB(__skb) ((struct tls_skb_cb *)&((__skb)->cb[0])) This eliminates the need for a separate get_skb_seq() callback. Building on the removal of the CB offset field, I also added patch 5 that trims the duplicated skb head at receive enqueue. With that in place, KTLS can retrieve the record header via skb_copy_bits() directly, so there is no longer any need for a dedicated MPTCP helper like mptcp_skb_get_header(). The skb_get_header() callback can thus be removed. Patch 6 defers sk_data_ready to the worker, which avoids recursive locking when TLS calls back into MPTCP under mptcp_data_lock(). With this change, the lock_is_held() callback is no longer needed and can be removed. [1] https://patchwork.kernel.org/project/mptcp/cover/cover.1782123118.git.tanggeliang@kylinos.cn/ [2] https://patchwork.kernel.org/project/mptcp/cover/cover.1778446731.git.pabeni@redhat.com/ Gang Yan (1): mptcp: update mptcp_check_readable Geliang Tang (5): mptcp: align FIN handling with TCP via SOCK_DONE 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 Paolo Abeni (5): 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 net/mptcp/fastopen.c | 17 +- net/mptcp/protocol.c | 365 ++++++++++++------ net/mptcp/protocol.h | 21 +- net/mptcp/subflow.c | 23 ++ .../selftests/net/mptcp/mptcp_sockopt.c | 5 + 5 files changed, 309 insertions(+), 122 deletions(-) -- 2.55.0