From nobody Sat Sep 5 05:49:24 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 68BDC43F8B1 for ; Thu, 27 Aug 2026 10:57:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787828271; cv=none; b=B6zfvVWxhX93Qb0H9llNdJ4L8plRyJC8cQaz2UVbMtfPnXUpsuHQQOYbR38DF3D7YZRRdCYgifalNtSWV6PFf00u26InfHJgXlwzYU2t+EZm4+P8Mhv5smeTLUSt5lYUT3iaPNDAIv4E6/xUMVkTJFcvkSl7J15yxhTEkN6uJV4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787828271; c=relaxed/simple; bh=S4CvDOwW6qufRcZhm6R6YIINhppRUkT6TYEBCiBphGs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=toGgVmPJpFgClyna/dGo4P1EKPuTolh6IETOqMax0WDrnBvuG1CHJDPYxnLQo7SprF9XbQWyV+Qtwbt6yUCaclBUEeQCD3E2BBISVhC2e+Ot4XMAk5j6zPWM86Fal4++4ifma8aaLwRu4j/dGQLKb2r8NYgByzyaS//r1EPu/K4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bS3vTFZt; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="bS3vTFZt" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 844A31F00A3A; Thu, 27 Aug 2026 10:57:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787828268; bh=OoDMCyfCiJm6MtDYSaoELBRrPu/bkdYymZb3xqUa/KI=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=bS3vTFZtzu74btjkYEolQbtiR7X+ycZGyUqUQ+Sb5q/ckoH+FttEiTIBoM45MYenD vLHELJehIk12RMmnKPwG0DNnh3WaONciJL6tgBJGYkwYSBEsMIjP8F8rlEeY4G/7p/ eq07grW22iyjJcdQw/6jctdl2Vfwl9ZO6rmQH1akpMihOUJIrFzLMKOvdSbKheElMG zZ8B6daCIteQ0MNvijnI4f4DrgFvslilqnoEtgo1ei4XFg2LGWQUOiyhscJnicNdP/ b4gyKJo6fXi18mh2LNYtDcRyXzmtN8T122fwpKoR/tkNpwaq43AobsZyO38UTgz1Kh cl20bUBUjcyYg== From: Geliang Tang To: mptcp@lists.linux.dev Cc: Geliang Tang Subject: [PATCH mptcp-next v9 01/11] mptcp: use atomic64_t for locklessly accessed u64 fields Date: Thu, 27 Aug 2026 18:57:25 +0800 Message-ID: X-Mailer: git-send-email 2.53.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Geliang Tang Several u64 fields in struct mptcp_sock are accessed locklessly and could suffer from torn reads on 32-bit architectures: - ack_seq: updated in process context without mptcp_data_lock() and read concurrently in softirq via mptcp_write_options() - write_seq, snd_nxt: sequence numbers accessed from multiple contexts - bytes_received, bytes_consumed: byte counters for flow control - snd_una, wnd_end: send window tracking fields On 32-bit architectures, 64-bit READ_ONCE/WRITE_ONCE compiles to two 32-bit accesses, so a torn read could produce corrupted values. Convert these fields from u64 to atomic64_t to guarantee tear-free accesses on all architectures. Also cache atomic64_read() in local variables where the same field is read multiple times within a function to avoid inconsistent repeated reads (e.g., in __mptcp_move_skb(), __mptcp_ofo_queue(), __mptcp_retrans(), __mptcp_clean_una(), mptcp_check_send_data_fin(), mptcp_update_post_push(), and mptcp_sk_clone_init()). Signed-off-by: Geliang Tang --- include/trace/events/mptcp.h | 7 +- net/mptcp/fastopen.c | 4 +- net/mptcp/options.c | 26 +++--- net/mptcp/protocol.c | 151 ++++++++++++++++++++--------------- net/mptcp/protocol.h | 24 +++--- net/mptcp/sockopt.c | 8 +- net/mptcp/subflow.c | 18 +++-- 7 files changed, 134 insertions(+), 104 deletions(-) diff --git a/include/trace/events/mptcp.h b/include/trace/events/mptcp.h index 22882bd03459..b3660cc94601 100644 --- a/include/trace/events/mptcp.h +++ b/include/trace/events/mptcp.h @@ -215,7 +215,9 @@ TRACE_EVENT(mptcp_rcvbuf_grow, struct inet_sock *inet =3D inet_sk(sk); bool ofo_empty; __be32 *p32; + u64 ack_seq; =20 + ack_seq =3D atomic64_read(&msk->ack_seq); __entry->time =3D time; __entry->rtt_us =3D mptcp_rtt_us_est(msk) >> 3; __entry->copied =3D msk->rcvq_space.copied; @@ -224,11 +226,10 @@ TRACE_EVENT(mptcp_rcvbuf_grow, ofo_empty =3D RB_EMPTY_ROOT(&msk->out_of_order_queue); __entry->ooo_space =3D ofo_empty ? 0 : MPTCP_SKB_CB(msk->ooo_last_skb)->end_seq - - msk->ack_seq; + ack_seq; =20 __entry->rcvbuf =3D sk->sk_rcvbuf; - __entry->rcv_wnd =3D atomic64_read(&msk->rcv_wnd_sent) - - msk->ack_seq; + __entry->rcv_wnd =3D atomic64_read(&msk->rcv_wnd_sent) - ack_seq; __entry->scaling_ratio =3D msk->scaling_ratio; __entry->sport =3D ntohs(inet->inet_sport); __entry->dport =3D ntohs(inet->inet_dport); diff --git a/net/mptcp/fastopen.c b/net/mptcp/fastopen.c index f717750906ff..0012690a2202 100644 --- a/net/mptcp/fastopen.c +++ b/net/mptcp/fastopen.c @@ -9,6 +9,7 @@ void mptcp_fastopen_subflow_synack_set_params(struct mptcp_subflow_context= *subflow, struct request_sock *req) { + struct mptcp_sock *msk; struct sock *sk, *ssk; struct sk_buff *skb; struct tcp_sock *tp; @@ -54,10 +55,11 @@ void mptcp_fastopen_subflow_synack_set_params(struct mp= tcp_subflow_context *subf mptcp_data_lock(sk); DEBUG_NET_WARN_ON_ONCE(sock_owned_by_user_nocheck(sk)); =20 + msk =3D mptcp_sk(sk); mptcp_borrow_fwdmem(sk, skb); skb_set_owner_r(skb, sk); __skb_queue_tail(&sk->sk_receive_queue, skb); - mptcp_sk(sk)->bytes_received +=3D skb->len; + atomic64_add(skb->len, &msk->bytes_received); =20 sk->sk_data_ready(sk); =20 diff --git a/net/mptcp/options.c b/net/mptcp/options.c index f87707110c75..b33bf445c0ba 100644 --- a/net/mptcp/options.c +++ b/net/mptcp/options.c @@ -600,7 +600,8 @@ static void mptcp_write_data_fin(struct mptcp_subflow_c= ontext *subflow, /* The write_seq value has already been incremented, so the actual * sequence number for the DATA_FIN is one less. */ - u64 data_fin_tx_seq =3D READ_ONCE(mptcp_sk(subflow->conn)->write_seq) - 1; + u64 data_fin_tx_seq =3D + atomic64_read(&mptcp_sk(subflow->conn)->write_seq) - 1; =20 if (!ext->use_map || !skb->len) { /* RFC6824 requires a DSS mapping with specific values @@ -1086,8 +1087,8 @@ u64 __mptcp_expand_seq(u64 old_seq, u64 cur_seq) =20 static void __mptcp_snd_una_update(struct mptcp_sock *msk, u64 new_snd_una) { - msk->bytes_acked +=3D new_snd_una - msk->snd_una; - WRITE_ONCE(msk->snd_una, new_snd_una); + msk->bytes_acked +=3D new_snd_una - atomic64_read(&msk->snd_una); + atomic64_set(&msk->snd_una, new_snd_una); } =20 static void rwin_update(struct mptcp_sock *msk, struct sock *ssk, @@ -1120,7 +1121,7 @@ static void ack_update_msk(struct mptcp_sock *msk, struct sock *ssk, struct mptcp_options_received *mp_opt) { - u64 new_wnd_end, new_snd_una, snd_nxt =3D READ_ONCE(msk->snd_nxt); + u64 new_wnd_end, new_snd_una, snd_nxt =3D atomic64_read(&msk->snd_nxt); struct sock *sk =3D (struct sock *)msk; u64 old_snd_una; =20 @@ -1130,7 +1131,7 @@ static void ack_update_msk(struct mptcp_sock *msk, * wrongly expanding to a future ack sequence number, which is way * more dangerous than missing an ack */ - old_snd_una =3D msk->snd_una; + old_snd_una =3D atomic64_read(&msk->snd_una); new_snd_una =3D mptcp_expand_seq(old_snd_una, mp_opt->data_ack, mp_opt->a= ck64); =20 /* ACK for data not even sent yet? Ignore.*/ @@ -1139,11 +1140,11 @@ static void ack_update_msk(struct mptcp_sock *msk, =20 new_wnd_end =3D new_snd_una + tcp_sk(ssk)->snd_wnd; =20 - if (after64(new_wnd_end, msk->wnd_end)) - WRITE_ONCE(msk->wnd_end, new_wnd_end); + if (after64(new_wnd_end, atomic64_read(&msk->wnd_end))) + atomic64_set(&msk->wnd_end, new_wnd_end); =20 /* this assumes mptcp_incoming_options() is invoked after tcp_ack() */ - if (after64(msk->wnd_end, snd_nxt)) + if (after64(atomic64_read(&msk->wnd_end), snd_nxt)) __mptcp_check_push(sk, ssk); =20 if (after64(new_snd_una, old_snd_una)) { @@ -1155,7 +1156,7 @@ static void ack_update_msk(struct mptcp_sock *msk, =20 trace_ack_update_msk(mp_opt->data_ack, old_snd_una, new_snd_una, - new_wnd_end, READ_ONCE(msk->wnd_end)); + new_wnd_end, atomic64_read(&msk->wnd_end)); } =20 bool mptcp_update_rcv_data_fin(struct mptcp_sock *msk, u64 data_fin_seq, b= ool use_64bit) @@ -1169,7 +1170,8 @@ bool mptcp_update_rcv_data_fin(struct mptcp_sock *msk= , u64 data_fin_seq, bool us return false; =20 WRITE_ONCE(msk->rcv_data_fin_seq, - mptcp_expand_seq(READ_ONCE(msk->ack_seq), data_fin_seq, use_64bit)); + mptcp_expand_seq(atomic64_read(&msk->ack_seq), + data_fin_seq, use_64bit)); WRITE_ONCE(msk->rcv_data_fin, 1); =20 return true; @@ -1242,7 +1244,7 @@ bool mptcp_incoming_options(struct sock *sk, struct s= k_buff *skb) /* on fallback we just need to ignore the msk-level snd_una, as * this is really plain TCP */ - __mptcp_snd_una_update(msk, READ_ONCE(msk->snd_nxt)); + __mptcp_snd_una_update(msk, atomic64_read(&msk->snd_nxt)); =20 __mptcp_data_acked(subflow->conn); mptcp_data_unlock(subflow->conn); @@ -1539,7 +1541,7 @@ void mptcp_write_options(struct tcphdr *th, __be32 *p= tr, struct tcp_sock *tp, */ subflow =3D mptcp_subflow_ctx(ssk); msk =3D mptcp_sk(subflow->conn); - ack_seq =3D READ_ONCE(msk->ack_seq); + ack_seq =3D atomic64_read(&msk->ack_seq); if (mpext->ack64) { put_unaligned_be64(ack_seq, ptr); ptr +=3D 2; diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index f22d64ab1c53..26b49480941c 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -59,7 +59,7 @@ static struct net_device *mptcp_napi_dev; /* Returns end sequence number of the receiver's advertised window */ u64 mptcp_wnd_end(const struct mptcp_sock *msk) { - return READ_ONCE(msk->wnd_end); + return atomic64_read(&msk->wnd_end); } =20 static const struct proto_ops *mptcp_fallback_tcp_ops(const struct sock *s= k) @@ -451,10 +451,12 @@ static bool __mptcp_move_skb(struct sock *sk, struct = sk_buff *skb) u64 copy_len =3D MPTCP_SKB_CB(skb)->end_seq - MPTCP_SKB_CB(skb)->map_seq; struct mptcp_sock *msk =3D mptcp_sk(sk); struct sk_buff *tail; + u64 ack_seq; =20 mptcp_borrow_fwdmem(sk, skb); =20 - if (MPTCP_SKB_CB(skb)->map_seq =3D=3D msk->ack_seq) { + ack_seq =3D atomic64_read(&msk->ack_seq); + if (MPTCP_SKB_CB(skb)->map_seq =3D=3D ack_seq) { /* in sequence */ insert: if (!mptcp_try_rmem_schedule(sk, skb)) { @@ -463,8 +465,8 @@ static bool __mptcp_move_skb(struct sock *sk, struct sk= _buff *skb) return false; } =20 - msk->bytes_received +=3D copy_len; - WRITE_ONCE(msk->ack_seq, msk->ack_seq + copy_len); + atomic64_add(copy_len, &msk->bytes_received); + atomic64_add(copy_len, &msk->ack_seq); tail =3D skb_peek_tail(&sk->sk_receive_queue); if (tail && mptcp_try_coalesce(sk, tail, skb)) return true; @@ -472,17 +474,17 @@ static bool __mptcp_move_skb(struct sock *sk, struct = sk_buff *skb) skb_set_owner_r(skb, sk); __skb_queue_tail(&sk->sk_receive_queue, skb); return true; - } else if (after64(MPTCP_SKB_CB(skb)->map_seq, msk->ack_seq)) { + } else if (after64(MPTCP_SKB_CB(skb)->map_seq, ack_seq)) { mptcp_data_queue_ofo(msk, skb); return false; } =20 /* Partial packet */ - if (after64(MPTCP_SKB_CB(skb)->end_seq, msk->ack_seq)) { - copy_len =3D MPTCP_SKB_CB(skb)->end_seq - msk->ack_seq; - MPTCP_SKB_CB(skb)->offset +=3D msk->ack_seq - + if (after64(MPTCP_SKB_CB(skb)->end_seq, ack_seq)) { + copy_len =3D MPTCP_SKB_CB(skb)->end_seq - ack_seq; + MPTCP_SKB_CB(skb)->offset +=3D ack_seq - MPTCP_SKB_CB(skb)->map_seq; - MPTCP_SKB_CB(skb)->map_seq +=3D msk->ack_seq - + MPTCP_SKB_CB(skb)->map_seq +=3D ack_seq - MPTCP_SKB_CB(skb)->map_seq; goto insert; } @@ -533,7 +535,7 @@ static bool mptcp_pending_data_fin_ack(struct sock *sk) =20 return ((1 << sk->sk_state) & (TCPF_FIN_WAIT1 | TCPF_CLOSING | TCPF_LAST_ACK)) && - msk->write_seq =3D=3D READ_ONCE(msk->snd_una); + atomic64_read(&msk->write_seq) =3D=3D atomic64_read(&msk->snd_una); } =20 static void mptcp_check_data_fin_ack(struct sock *sk) @@ -569,7 +571,7 @@ static bool mptcp_pending_data_fin(struct sock *sk, u64= *seq) (TCPF_ESTABLISHED | TCPF_FIN_WAIT1 | TCPF_FIN_WAIT2))) { u64 rcv_data_fin_seq =3D READ_ONCE(msk->rcv_data_fin_seq); =20 - if (READ_ONCE(msk->ack_seq) =3D=3D rcv_data_fin_seq) { + if (atomic64_read(&msk->ack_seq) =3D=3D rcv_data_fin_seq) { if (seq) *seq =3D rcv_data_fin_seq; =20 @@ -710,7 +712,7 @@ static void mptcp_check_data_fin(struct sock *sk) */ =20 if (mptcp_pending_data_fin(sk, &rcv_data_fin_seq)) { - WRITE_ONCE(msk->ack_seq, msk->ack_seq + 1); + atomic64_inc(&msk->ack_seq); WRITE_ONCE(msk->rcv_data_fin, 0); =20 WRITE_ONCE(sk->sk_shutdown, sk->sk_shutdown | RCV_SHUTDOWN); @@ -879,22 +881,22 @@ static bool __mptcp_ofo_queue(struct mptcp_sock *msk) { struct sock *sk =3D (struct sock *)msk; struct sk_buff *skb, *tail; + u64 end_seq, ack_seq; bool moved =3D false; struct rb_node *p; - u64 end_seq; =20 p =3D rb_first(&msk->out_of_order_queue); pr_debug("msk=3D%p empty=3D%d\n", msk, RB_EMPTY_ROOT(&msk->out_of_order_q= ueue)); while (p) { + ack_seq =3D atomic64_read(&msk->ack_seq); skb =3D rb_to_skb(p); - if (after64(MPTCP_SKB_CB(skb)->map_seq, msk->ack_seq)) + if (after64(MPTCP_SKB_CB(skb)->map_seq, ack_seq)) break; =20 p =3D rb_next(p); rb_erase(&skb->rbnode, &msk->out_of_order_queue); =20 - if (unlikely(!after64(MPTCP_SKB_CB(skb)->end_seq, - msk->ack_seq))) { + if (unlikely(!after64(MPTCP_SKB_CB(skb)->end_seq, ack_seq))) { mptcp_drop(sk, skb); MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_DUPDATA); continue; @@ -903,18 +905,18 @@ static bool __mptcp_ofo_queue(struct mptcp_sock *msk) end_seq =3D MPTCP_SKB_CB(skb)->end_seq; tail =3D skb_peek_tail(&sk->sk_receive_queue); if (!tail || !mptcp_ooo_try_coalesce(msk, tail, skb)) { - int delta =3D msk->ack_seq - MPTCP_SKB_CB(skb)->map_seq; + int delta =3D ack_seq - MPTCP_SKB_CB(skb)->map_seq; =20 /* skip overlapping data, if any */ pr_debug("uncoalesced seq=3D%llx ack seq=3D%llx delta=3D%d\n", - MPTCP_SKB_CB(skb)->map_seq, msk->ack_seq, + MPTCP_SKB_CB(skb)->map_seq, ack_seq, delta); MPTCP_SKB_CB(skb)->offset +=3D delta; MPTCP_SKB_CB(skb)->map_seq +=3D delta; __skb_queue_tail(&sk->sk_receive_queue, skb); } - msk->bytes_received +=3D end_seq - msk->ack_seq; - WRITE_ONCE(msk->ack_seq, end_seq); + atomic64_add(end_seq - ack_seq, &msk->bytes_received); + atomic64_set(&msk->ack_seq, end_seq); moved =3D true; } return moved; @@ -1072,7 +1074,7 @@ void mptcp_data_ready(struct sock *sk, struct sock *s= sk) =20 static void mptcp_subflow_joined(struct mptcp_sock *msk, struct sock *ssk) { - mptcp_subflow_ctx(ssk)->map_seq =3D READ_ONCE(msk->ack_seq); + mptcp_subflow_ctx(ssk)->map_seq =3D atomic64_read(&msk->ack_seq); msk->allow_infinite_fallback =3D false; mptcp_event(MPTCP_EVENT_SUB_ESTABLISHED, msk, ssk, GFP_ATOMIC); } @@ -1178,7 +1180,7 @@ static bool mptcp_frag_can_collapse_to(const struct m= ptcp_sock *msk, pfrag->page =3D=3D df->page && pfrag->size - pfrag->offset > 0 && pfrag->offset =3D=3D (df->offset + df->data_len) && - df->data_seq + df->data_len =3D=3D msk->write_seq; + df->data_seq + df->data_len =3D=3D atomic64_read(&msk->write_seq); } =20 static void dfrag_uncharge(struct sock *sk, int len) @@ -1201,9 +1203,11 @@ static void __mptcp_clean_una(struct sock *sk) { struct mptcp_sock *msk =3D mptcp_sk(sk); struct mptcp_data_frag *dtmp, *dfrag; - u64 snd_una; + u64 snd_una, snd_nxt, write_seq; =20 - snd_una =3D msk->snd_una; + snd_una =3D atomic64_read(&msk->snd_una); + snd_nxt =3D atomic64_read(&msk->snd_nxt); + write_seq =3D atomic64_read(&msk->write_seq); list_for_each_entry_safe(dfrag, dtmp, &msk->rtx_queue, list) { if (after64(dfrag->data_seq + dfrag->data_len, snd_una)) break; @@ -1241,11 +1245,11 @@ static void __mptcp_clean_una(struct sock *sk) } =20 /* all retransmitted data acked, recovery completed */ - if (unlikely(msk->recovery) && after64(msk->snd_una, msk->recovery_snd_nx= t)) + if (unlikely(msk->recovery) && after64(snd_una, msk->recovery_snd_nxt)) msk->recovery =3D false; =20 out: - if (snd_una =3D=3D msk->snd_nxt && snd_una =3D=3D msk->write_seq) { + if (snd_una =3D=3D snd_nxt && snd_una =3D=3D write_seq) { if (mptcp_rtx_timer_pending(sk) && !mptcp_data_fin_enabled(msk)) mptcp_stop_rtx_timer(sk); } else { @@ -1305,7 +1309,7 @@ mptcp_carve_data_frag(const struct mptcp_sock *msk, s= truct page_frag *pfrag, =20 dfrag =3D (struct mptcp_data_frag *)(page_to_virt(pfrag->page) + offset); dfrag->data_len =3D 0; - dfrag->data_seq =3D msk->write_seq; + dfrag->data_seq =3D atomic64_read(&msk->write_seq); dfrag->overhead =3D offset - orig_offset + sizeof(struct mptcp_data_frag); dfrag->offset =3D offset + sizeof(struct mptcp_data_frag); dfrag->already_sent =3D 0; @@ -1499,13 +1503,13 @@ static int mptcp_sendmsg_frag(struct sock *sk, stru= ct sock *ssk, /* Zero window and all data acked? Probe. */ copy =3D mptcp_check_allowed_size(msk, ssk, data_seq, copy); if (copy =3D=3D 0) { - u64 snd_una =3D READ_ONCE(msk->snd_una); + u64 snd_una =3D atomic64_read(&msk->snd_una); =20 /* No need for zero probe if there are any data pending * either at the msk or ssk level; skb is the current write * queue tail and can be empty at this point. */ - if (snd_una !=3D msk->snd_nxt || skb->len || + if (snd_una !=3D atomic64_read(&msk->snd_nxt) || skb->len || skb !=3D tcp_send_head(ssk)) { tcp_remove_empty_skb(ssk); return 0; @@ -1686,7 +1690,8 @@ struct sock *mptcp_subflow_get_send(struct mptcp_sock= *msk) if (!ssk || !sk_stream_memory_free(ssk)) return NULL; =20 - burst =3D min(MPTCP_SEND_BURST_SIZE, mptcp_wnd_end(msk) - msk->snd_nxt); + burst =3D min(MPTCP_SEND_BURST_SIZE, + mptcp_wnd_end(msk) - atomic64_read(&msk->snd_nxt)); wmem =3D READ_ONCE(ssk->sk_wmem_queued); if (!burst) return ssk; @@ -1709,6 +1714,7 @@ static void mptcp_update_post_push(struct mptcp_sock = *msk, struct mptcp_data_frag *dfrag, u32 sent) { + u64 snd_nxt =3D atomic64_read(&msk->snd_nxt); u64 snd_nxt_new =3D dfrag->data_seq; =20 dfrag->already_sent +=3D sent; @@ -1726,9 +1732,9 @@ static void mptcp_update_post_push(struct mptcp_sock = *msk, * that has been handed to the subflow for transmission * and skip update in case it was old dfrag. */ - if (likely(after64(snd_nxt_new, msk->snd_nxt))) { - msk->bytes_sent +=3D snd_nxt_new - msk->snd_nxt; - WRITE_ONCE(msk->snd_nxt, snd_nxt_new); + if (likely(after64(snd_nxt_new, snd_nxt))) { + msk->bytes_sent +=3D snd_nxt_new - snd_nxt; + atomic64_set(&msk->snd_nxt, snd_nxt_new); } } =20 @@ -1915,7 +1921,8 @@ static void __mptcp_subflow_push_pending(struct sock = *sk, struct sock *ssk, bool mptcp_reset_rtx_timer(sk); =20 if (msk->snd_data_fin_enable && - msk->snd_nxt + 1 =3D=3D msk->write_seq) + atomic64_read(&msk->snd_nxt) + 1 =3D=3D + atomic64_read(&msk->write_seq)) mptcp_schedule_work(sk); } } @@ -2009,7 +2016,8 @@ static u32 mptcp_send_limit(const struct sock *sk) if (limit =3D=3D UINT_MAX) return UINT_MAX; =20 - not_sent =3D msk->write_seq - msk->snd_nxt; + not_sent =3D atomic64_read(&msk->write_seq) - + atomic64_read(&msk->snd_nxt); if (not_sent >=3D limit) return 0; =20 @@ -2121,7 +2129,7 @@ static int mptcp_sendmsg(struct sock *sk, struct msgh= dr *msg, size_t len) dfrag->data_len +=3D psize; frag_truesize +=3D psize; pfrag->offset +=3D frag_truesize; - WRITE_ONCE(msk->write_seq, msk->write_seq + psize); + atomic64_add(psize, &msk->write_seq); =20 /* charge data on mptcp pending queue to the msk socket * Note: we charge such data both to sk and ssk @@ -2231,7 +2239,7 @@ static int __mptcp_recvmsg_mskq(struct sock *sk, stru= ct msghdr *msg, copied +=3D count; =20 if (!(flags & MSG_PEEK)) { - msk->bytes_consumed +=3D count; + atomic64_add(count, &msk->bytes_consumed); if (count < data_len) { MPTCP_SKB_CB(skb)->offset +=3D count; MPTCP_SKB_CB(skb)->map_seq +=3D count; @@ -2393,10 +2401,12 @@ static unsigned int mptcp_inq_hint(const struct soc= k *sk) { const struct mptcp_sock *msk =3D mptcp_sk(sk); const struct sk_buff *skb; + u64 hint_val, ack_seq; =20 skb =3D skb_peek(&sk->sk_receive_queue); if (skb) { - u64 hint_val =3D READ_ONCE(msk->ack_seq) - MPTCP_SKB_CB(skb)->map_seq; + ack_seq =3D atomic64_read(&msk->ack_seq); + hint_val =3D ack_seq - MPTCP_SKB_CB(skb)->map_seq; =20 if (hint_val >=3D INT_MAX) return INT_MAX; @@ -2609,7 +2619,7 @@ bool __mptcp_retransmit_pending_data(struct sock *sk) return false; } =20 - msk->recovery_snd_nxt =3D msk->snd_nxt; + msk->recovery_snd_nxt =3D atomic64_read(&msk->snd_nxt); msk->recovery =3D true; mptcp_data_unlock(sk); =20 @@ -2969,7 +2979,7 @@ static void __mptcp_retrans(struct sock *sk) /* Get an updated and consistent rtx queue status. */ mptcp_data_lock(sk); __mptcp_clean_una_wakeup(sk); - retrans_seq =3D msk->snd_una; + retrans_seq =3D atomic64_read(&msk->snd_una); dfrag =3D mptcp_rtx_head(sk); need_retrans =3D !!dfrag; mptcp_data_unlock(sk); @@ -2999,8 +3009,8 @@ static void __mptcp_retrans(struct sock *sk) =20 /* With csum enabled, retransmission can send new data. */ sent_seq =3D dfrag->already_sent + dfrag->data_seq; - if (after64(sent_seq, msk->snd_nxt)) - WRITE_ONCE(msk->snd_nxt, sent_seq); + if (after64(sent_seq, atomic64_read(&msk->snd_nxt))) + atomic64_set(&msk->snd_nxt, sent_seq); =20 /* Attempt the next fragment only if the current one is * completely retransmitted. @@ -3017,15 +3027,16 @@ static void __mptcp_retrans(struct sock *sk) * across loop iterations, if so start again from RTX head. */ mptcp_data_lock(sk); - already_acked =3D !before64(msk->snd_una, dfrag->data_seq + + already_acked =3D !before64(atomic64_read(&msk->snd_una), + dfrag->data_seq + dfrag->already_sent); if (already_acked) { __mptcp_clean_una_wakeup(sk); - retrans_seq =3D msk->snd_una; + retrans_seq =3D atomic64_read(&msk->snd_una); dfrag =3D mptcp_rtx_head(sk); need_retrans =3D !!dfrag; - } else if (after64(msk->snd_una, retrans_seq)) { - retrans_seq =3D msk->snd_una; + } else if (after64(atomic64_read(&msk->snd_una), retrans_seq)) { + retrans_seq =3D atomic64_read(&msk->snd_una); } mptcp_data_unlock(sk); } @@ -3314,6 +3325,8 @@ void mptcp_cancel_work(struct sock *sk) =20 void mptcp_subflow_shutdown(struct sock *sk, struct sock *ssk, int how) { + struct mptcp_sock *msk =3D mptcp_sk(sk); + lock_sock(ssk); =20 switch (ssk->sk_state) { @@ -3325,7 +3338,7 @@ void mptcp_subflow_shutdown(struct sock *sk, struct s= ock *ssk, int how) WARN_ON_ONCE(tcp_disconnect(ssk, O_NONBLOCK)); break; default: - if (__mptcp_check_fallback(mptcp_sk(sk))) { + if (__mptcp_check_fallback(msk)) { pr_debug("Fallback\n"); ssk->sk_shutdown |=3D how; tcp_shutdown(ssk, how); @@ -3333,7 +3346,8 @@ void mptcp_subflow_shutdown(struct sock *sk, struct s= ock *ssk, int how) /* simulate the data_fin ack reception to let the state * machine move forward */ - WRITE_ONCE(mptcp_sk(sk)->snd_una, mptcp_sk(sk)->snd_nxt); + atomic64_set(&msk->snd_una, + atomic64_read(&msk->snd_nxt)); mptcp_schedule_work(sk); } else { pr_debug("Sending DATA_FIN on subflow %p\n", ssk); @@ -3404,19 +3418,23 @@ static void mptcp_check_send_data_fin(struct sock *= sk) { struct mptcp_subflow_context *subflow; struct mptcp_sock *msk =3D mptcp_sk(sk); + u64 snd_nxt, write_seq; + + snd_nxt =3D atomic64_read(&msk->snd_nxt); + write_seq =3D atomic64_read(&msk->write_seq); =20 pr_debug("msk=3D%p snd_data_fin_enable=3D%d pending=3D%d snd_nxt=3D%llu w= rite_seq=3D%llu\n", msk, msk->snd_data_fin_enable, !!mptcp_send_head(sk), - msk->snd_nxt, msk->write_seq); + snd_nxt, write_seq); =20 /* we still need to enqueue subflows or not really shutting down, * skip this */ - if (!msk->snd_data_fin_enable || msk->snd_nxt + 1 !=3D msk->write_seq || + if (!msk->snd_data_fin_enable || snd_nxt + 1 !=3D write_seq || mptcp_send_head(sk)) return; =20 - WRITE_ONCE(msk->snd_nxt, msk->write_seq); + atomic64_set(&msk->snd_nxt, write_seq); =20 mptcp_for_each_subflow(msk, subflow) { struct sock *tcp_sk =3D mptcp_subflow_tcp_sock(subflow); @@ -3434,7 +3452,7 @@ static void __mptcp_wr_shutdown(struct sock *sk) !!mptcp_send_head(sk)); =20 /* will be ignored by fallback sockets */ - WRITE_ONCE(msk->write_seq, msk->write_seq + 1); + atomic64_add(1, &msk->write_seq); WRITE_ONCE(msk->snd_data_fin_enable, 1); =20 mptcp_check_send_data_fin(sk); @@ -3668,9 +3686,9 @@ static int mptcp_disconnect(struct sock *sk, int flag= s) WRITE_ONCE(msk->csum_enabled, mptcp_is_checksum_enabled(sock_net(sk))); mptcp_pm_data_reset(msk); mptcp_ca_reset(sk); - msk->bytes_consumed =3D 0; + atomic64_set(&msk->bytes_consumed, 0); msk->bytes_acked =3D 0; - msk->bytes_received =3D 0; + atomic64_set(&msk->bytes_received, 0); msk->bytes_sent =3D 0; msk->bytes_retrans =3D 0; msk->rcvspace_init =3D 0; @@ -3678,7 +3696,7 @@ static int mptcp_disconnect(struct sock *sk, int flag= s) mptcp_init_rtt_est(msk); =20 /* for fallback's sake */ - WRITE_ONCE(msk->ack_seq, 0); + atomic64_set(&msk->ack_seq, 0); atomic64_set(&msk->rcv_wnd_sent, 0); =20 WRITE_ONCE(sk->sk_shutdown, 0); @@ -3742,6 +3760,7 @@ struct sock *mptcp_sk_clone_init(const struct sock *s= k, struct mptcp_subflow_request_sock *subflow_req =3D mptcp_subflow_rsk(req); struct sock *nsk =3D sk_clone_lock(sk, GFP_ATOMIC); struct mptcp_subflow_context *subflow; + u64 seq =3D subflow_req->idsn + 1; struct mptcp_sock *msk; =20 if (!nsk) @@ -3769,10 +3788,10 @@ struct sock *mptcp_sk_clone_init(const struct sock = *sk, if (mp_opt->suboptions & OPTION_MPTCP_CSUMREQD) WRITE_ONCE(msk->csum_enabled, true); =20 - WRITE_ONCE(msk->write_seq, subflow_req->idsn + 1); - WRITE_ONCE(msk->snd_nxt, msk->write_seq); - WRITE_ONCE(msk->snd_una, msk->write_seq); - WRITE_ONCE(msk->wnd_end, msk->snd_nxt + tcp_sk(ssk)->snd_wnd); + atomic64_set(&msk->write_seq, seq); + atomic64_set(&msk->snd_nxt, seq); + atomic64_set(&msk->snd_una, seq); + atomic64_set(&msk->wnd_end, seq + tcp_sk(ssk)->snd_wnd); msk->setsockopt_seq =3D mptcp_sk(sk)->setsockopt_seq; mptcp_init_sched(msk, mptcp_sk(sk)->sched); =20 @@ -4120,7 +4139,7 @@ static int mptcp_ioctl_outq(const struct mptcp_sock *= msk, u64 v) if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) return 0; =20 - delta =3D msk->write_seq - v; + delta =3D atomic64_read(&msk->write_seq) - v; if (__mptcp_check_fallback(msk) && msk->first) { struct tcp_sock *tp =3D tcp_sk(msk->first); =20 @@ -4156,12 +4175,12 @@ static int mptcp_ioctl(struct sock *sk, int cmd, in= t *karg) break; case SIOCOUTQ: slow =3D lock_sock_fast(sk); - *karg =3D mptcp_ioctl_outq(msk, READ_ONCE(msk->snd_una)); + *karg =3D mptcp_ioctl_outq(msk, atomic64_read(&msk->snd_una)); unlock_sock_fast(sk, slow); break; case SIOCOUTQNSD: slow =3D lock_sock_fast(sk); - *karg =3D mptcp_ioctl_outq(msk, msk->snd_nxt); + *karg =3D mptcp_ioctl_outq(msk, atomic64_read(&msk->snd_nxt)); unlock_sock_fast(sk, slow); break; default: @@ -4201,9 +4220,9 @@ static int mptcp_connect(struct sock *sk, struct sock= addr_unsized *uaddr, MPTCP_MIB_TOKENFALLBACKINIT); } =20 - WRITE_ONCE(msk->write_seq, subflow->idsn); - WRITE_ONCE(msk->snd_nxt, subflow->idsn); - WRITE_ONCE(msk->snd_una, subflow->idsn); + atomic64_set(&msk->write_seq, subflow->idsn); + atomic64_set(&msk->snd_nxt, subflow->idsn); + atomic64_set(&msk->snd_una, subflow->idsn); if (likely(!__mptcp_check_fallback(msk))) MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPCAPABLEACTIVE); =20 @@ -4607,7 +4626,7 @@ static int __mptcp_read_sock(struct sock *sk, read_de= scriptor_t *desc, =20 copied +=3D count; =20 - msk->bytes_consumed +=3D count; + atomic64_add(count, &msk->bytes_consumed); if (count < data_len) { MPTCP_SKB_CB(skb)->offset +=3D count; MPTCP_SKB_CB(skb)->map_seq +=3D count; diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index 3d250e8204d5..29405d045291 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -288,15 +288,15 @@ struct mptcp_sock { * lockless access read */ u64 remote_key; /* same as above */ - u64 write_seq; + atomic64_t write_seq; u64 bytes_sent; - u64 snd_nxt; - u64 bytes_received; - u64 ack_seq; + atomic64_t snd_nxt; + atomic64_t bytes_received; + atomic64_t ack_seq; atomic64_t rcv_wnd_sent; u64 rcv_data_fin_seq; u64 bytes_retrans; - u64 bytes_consumed; + atomic64_t bytes_consumed; int snd_burst; int old_wspace; u64 recovery_snd_nxt; /* in recovery mode accept up to this seq; @@ -304,8 +304,8 @@ struct mptcp_sock { * protection */ u64 bytes_acked; - u64 snd_una; - u64 wnd_end; + atomic64_t snd_una; + atomic64_t wnd_end; u32 last_data_sent; u32 last_data_recv; u32 last_ack_recv; @@ -488,7 +488,7 @@ static inline struct mptcp_data_frag *mptcp_rtx_head(st= ruct sock *sk) { struct mptcp_sock *msk =3D mptcp_sk(sk); =20 - if (msk->snd_una =3D=3D msk->snd_nxt) + if (atomic64_read(&msk->snd_una) =3D=3D atomic64_read(&msk->snd_nxt)) return NULL; =20 return list_first_entry_or_null(&msk->rtx_queue, struct mptcp_data_frag, = list); @@ -866,7 +866,8 @@ int mptcp_sched_get_retrans(struct mptcp_sock *msk); =20 static inline u64 mptcp_data_avail(const struct mptcp_sock *msk) { - return READ_ONCE(msk->bytes_received) - READ_ONCE(msk->bytes_consumed); + return atomic64_read(&msk->bytes_received) - + atomic64_read(&msk->bytes_consumed); } =20 static inline bool mptcp_epollin_ready(const struct sock *sk) @@ -989,7 +990,7 @@ bool mptcp_update_rcv_data_fin(struct mptcp_sock *msk, = u64 data_fin_seq, bool us static inline bool mptcp_data_fin_enabled(const struct mptcp_sock *msk) { return READ_ONCE(msk->snd_data_fin_enable) && - READ_ONCE(msk->write_seq) =3D=3D READ_ONCE(msk->snd_nxt); + atomic64_read(&msk->write_seq) =3D=3D atomic64_read(&msk->snd_nxt); } =20 static inline u32 mptcp_notsent_lowat(const struct sock *sk) @@ -1006,7 +1007,8 @@ static inline bool mptcp_stream_memory_free(const str= uct sock *sk, int wake) const struct mptcp_sock *msk =3D mptcp_sk(sk); u32 notsent_bytes; =20 - notsent_bytes =3D READ_ONCE(msk->write_seq) - READ_ONCE(msk->snd_nxt); + notsent_bytes =3D atomic64_read(&msk->write_seq) - + atomic64_read(&msk->snd_nxt); return (notsent_bytes << wake) < mptcp_notsent_lowat(sk); } =20 diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c index 922f6ae5c80c..ed221b36fd25 100644 --- a/net/mptcp/sockopt.c +++ b/net/mptcp/sockopt.c @@ -1086,10 +1086,10 @@ void mptcp_diag_fill_info(struct mptcp_sock *msk, s= truct mptcp_info *info) slow =3D lock_sock_fast(sk); info->mptcpi_csum_enabled =3D READ_ONCE(msk->csum_enabled); info->mptcpi_token =3D msk->token; - info->mptcpi_write_seq =3D msk->write_seq; + info->mptcpi_write_seq =3D atomic64_read(&msk->write_seq); info->mptcpi_retransmits =3D inet_csk(sk)->icsk_retransmits; info->mptcpi_bytes_sent =3D msk->bytes_sent; - info->mptcpi_bytes_received =3D msk->bytes_received; + info->mptcpi_bytes_received =3D atomic64_read(&msk->bytes_received); info->mptcpi_bytes_retrans =3D msk->bytes_retrans; info->mptcpi_subflows_total =3D info->mptcpi_extra_subflows + __mptcp_has_initial_subflow(msk); @@ -1100,8 +1100,8 @@ void mptcp_diag_fill_info(struct mptcp_sock *msk, str= uct mptcp_info *info) =20 mptcp_data_lock(sk); info->mptcpi_last_ack_recv =3D jiffies_to_msecs(now - msk->last_ack_recv); - info->mptcpi_snd_una =3D msk->snd_una; - info->mptcpi_rcv_nxt =3D msk->ack_seq; + info->mptcpi_snd_una =3D atomic64_read(&msk->snd_una); + info->mptcpi_rcv_nxt =3D atomic64_read(&msk->ack_seq); info->mptcpi_bytes_acked =3D msk->bytes_acked; mptcp_data_unlock(sk); } diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index 2d7ccb01d234..8dc200d8d072 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -457,16 +457,18 @@ void __mptcp_sync_state(struct sock *sk, int state) struct mptcp_subflow_context *subflow; struct mptcp_sock *msk =3D mptcp_sk(sk); struct sock *ssk =3D msk->first; + u64 seq; =20 subflow =3D mptcp_subflow_ctx(ssk); + seq =3D subflow->idsn + 1; __mptcp_propagate_sndbuf(sk, ssk); =20 if (sk->sk_state =3D=3D TCP_SYN_SENT) { /* subflow->idsn is always available is TCP_SYN_SENT state, * even for the FASTOPEN scenarios */ - WRITE_ONCE(msk->write_seq, subflow->idsn + 1); - WRITE_ONCE(msk->snd_nxt, msk->write_seq); + atomic64_set(&msk->write_seq, seq); + atomic64_set(&msk->snd_nxt, seq); mptcp_set_state(sk, state); sk->sk_state_change(sk); } @@ -491,7 +493,7 @@ static void subflow_set_remote_key(struct mptcp_sock *m= sk, subflow->map_seq =3D subflow->iasn; =20 WRITE_ONCE(msk->remote_key, subflow->remote_key); - WRITE_ONCE(msk->ack_seq, subflow->iasn); + atomic64_set(&msk->ack_seq, subflow->iasn); WRITE_ONCE(msk->can_ack, true); atomic64_set(&msk->rcv_wnd_sent, subflow->iasn); } @@ -501,14 +503,15 @@ static void mptcp_propagate_state(struct sock *sk, st= ruct sock *ssk, const struct mptcp_options_received *mp_opt) { struct mptcp_sock *msk =3D mptcp_sk(sk); + u64 seq =3D subflow->idsn + 1; =20 mptcp_data_lock(sk); if (mp_opt) { /* Options are available only in the non fallback cases * avoid updating rx path fields otherwise */ - WRITE_ONCE(msk->snd_una, subflow->idsn + 1); - WRITE_ONCE(msk->wnd_end, subflow->idsn + 1 + tcp_sk(ssk)->snd_wnd); + atomic64_set(&msk->snd_una, seq); + atomic64_set(&msk->wnd_end, seq + tcp_sk(ssk)->snd_wnd); subflow_set_remote_key(msk, subflow, mp_opt); } =20 @@ -1198,7 +1201,8 @@ static enum mapping_status get_mapping_status(struct = sock *ssk, data_len--; } =20 - map_seq =3D mptcp_expand_seq(READ_ONCE(msk->ack_seq), mpext->data_seq, mp= ext->dsn64); + map_seq =3D mptcp_expand_seq(atomic64_read(&msk->ack_seq), + mpext->data_seq, mpext->dsn64); WRITE_ONCE(mptcp_sk(subflow->conn)->use_64bit_ack, !!mpext->dsn64); =20 if (subflow->map_valid) { @@ -1386,7 +1390,7 @@ static bool subflow_check_data_avail(struct sock *ssk) if (unlikely(!READ_ONCE(msk->can_ack))) goto fallback; =20 - old_ack =3D READ_ONCE(msk->ack_seq); + old_ack =3D atomic64_read(&msk->ack_seq); ack_seq =3D mptcp_subflow_get_mapped_dsn(subflow); pr_debug("msk ack_seq=3D%llx subflow ack_seq=3D%llx\n", old_ack, ack_seq); --=20 2.53.0 From nobody Sat Sep 5 05:49:24 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F0B0C32D7F1 for ; 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charset="utf-8" From: Paolo Abeni It's used to save an additional comparison for in-order skbs, but is also a barrier to remove CB offset. Remove the helper, let __mptcp_try_coalesce() always perform the sequence check and remove duplicate checks from the callers. Co-developed-by: Geliang Tang Signed-off-by: Geliang Tang Signed-off-by: Paolo Abeni --- net/mptcp/protocol.c | 21 ++++++--------------- 1 file changed, 6 insertions(+), 15 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 26b49480941c..39371a16b8bf 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -167,7 +167,8 @@ static bool __mptcp_try_coalesce(struct sock *sk, struc= t sk_buff *to, { int limit =3D READ_ONCE(sk->sk_rcvbuf); =20 - if (unlikely(MPTCP_SKB_CB(to)->cant_coalesce) || + if (MPTCP_SKB_CB(from)->map_seq !=3D MPTCP_SKB_CB(to)->end_seq || + unlikely(MPTCP_SKB_CB(to)->cant_coalesce) || MPTCP_SKB_CB(from)->offset || ((to->len + from->len) > (limit >> 3)) || !skb_try_coalesce(to, from, fragstolen, delta)) @@ -200,15 +201,6 @@ static bool mptcp_try_coalesce(struct sock *sk, struct= sk_buff *to, return true; } =20 -static bool mptcp_ooo_try_coalesce(struct mptcp_sock *msk, struct sk_buff = *to, - struct sk_buff *from) -{ - if (MPTCP_SKB_CB(from)->map_seq !=3D MPTCP_SKB_CB(to)->end_seq) - return false; - - return mptcp_try_coalesce((struct sock *)msk, to, from); -} - /* "inspired" by tcp_rcvbuf_grow(), main difference: * - mptcp does not maintain a msk-level window clamp * - returns true when the receive buffer is actually updated @@ -348,7 +340,7 @@ static void mptcp_data_queue_ofo(struct mptcp_sock *msk= , struct sk_buff *skb) /* with 2 subflows, adding at end of ooo queue is quite likely * Use of ooo_last_skb avoids the O(Log(N)) rbtree lookup. */ - if (mptcp_ooo_try_coalesce(msk, msk->ooo_last_skb, skb)) { + if (mptcp_try_coalesce(sk, msk->ooo_last_skb, skb)) { MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_OFOMERGE); MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_OFOQUEUETAIL); return; @@ -394,7 +386,7 @@ static void mptcp_data_queue_ofo(struct mptcp_sock *msk= , struct sk_buff *skb) MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_DUPDATA); goto merge_right; } - } else if (mptcp_ooo_try_coalesce(msk, skb1, skb)) { + } else if (mptcp_try_coalesce(sk, skb1, skb)) { MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_OFOMERGE); return; } @@ -779,8 +771,7 @@ static void __mptcp_add_backlog(struct sock *sk, if (!list_empty(&msk->backlog_list)) tail =3D list_last_entry(&msk->backlog_list, struct sk_buff, list); =20 - if (tail && MPTCP_SKB_CB(skb)->map_seq =3D=3D MPTCP_SKB_CB(tail)->end_seq= && - ssk =3D=3D tail->sk && + if (tail && ssk =3D=3D tail->sk && __mptcp_try_coalesce(sk, tail, skb, &fragstolen, &delta)) { skb->truesize -=3D delta; kfree_skb_partial(skb, fragstolen); @@ -904,7 +895,7 @@ static bool __mptcp_ofo_queue(struct mptcp_sock *msk) =20 end_seq =3D MPTCP_SKB_CB(skb)->end_seq; tail =3D skb_peek_tail(&sk->sk_receive_queue); - if (!tail || !mptcp_ooo_try_coalesce(msk, tail, skb)) { + if (!tail || !mptcp_try_coalesce(sk, tail, skb)) { int delta =3D ack_seq - MPTCP_SKB_CB(skb)->map_seq; =20 /* skip overlapping data, if any */ --=20 2.53.0 From nobody Sat Sep 5 05:49:24 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 06E22420484 for ; 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dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="MR7HrHja" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5D2281F000E9; Thu, 27 Aug 2026 10:57:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787828272; bh=njQ0DkGGt1ENAJGJ20ZRcFTW50PxNCQ8kmEeB2XQENk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=MR7HrHjaqbEXgwsMk6KJWISVClFtTBgtiCdtHIMabbBl9ZqTrWvk1aA1AAakEwVp/ h90UXTTMOBzpiWhrGEY3lzG9Ta4KymAXZx+ksQTcIaXKPQNNmuamNjV48QyTO7Onzb lnQhKzIYaKE2YTw533t0TRmZ3VDZ+0LsoUbjiikjedJx5M27pfCXdi5KF9ELYHa6h1 2eW+SFSkwleaVtX3hRchFd2IkrkO/mzkarRicqI5pAQorqGOXDoCirWY4knRvRaTFJ QaphTB9KPGLWSA67Bn43eHBOPkE7j5iX9YmadMFWKYpy/4wmuU/jkxaHCBffifCksj mrysLqGu/u9sg== From: Geliang Tang To: mptcp@lists.linux.dev Cc: Paolo Abeni , Geliang Tang Subject: [PATCH mptcp-next v9 03/11] mptcp: drop the cant_coalesce CB field Date: Thu, 27 Aug 2026 18:57:27 +0800 Message-ID: <244b45259a9c7f22e16fd95997d540340ec45a31.1787827525.git.tanggeliang@kylinos.cn> X-Mailer: git-send-email 2.53.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Paolo Abeni Such field is used to ensure in-sequence processing in case of fastopen. Instead let's perform synchronization of the fastopen skb sequence when the IASN becomes available with the 3rd ack. When the `cant_coalesce` field has been introduced, commit f03afb3aeb9d ("mptcp: drop __mptcp_fastopen_gen_msk_ackseq()") noted that updating the already queued skb for passive fastopen socket at 3rd ack time would be difficult and race prone. The main point is that such update don't need to be synchronously performed at 3rd ack time, but is sufficient to perform it before the next segment is introduced into the msk. To such extent, add an explicit test in __mptcp_move_skb(). Performance wise this trades a conditional in the fast path - in __mptcp_try_coalesce() - with a similar one in __mptcp_move_skb() and a couple more in slow paths. After this change the user-space will always observe consistent sequence numbers in the receive queue, even in the TFO dummy mapping case. There is still a potential race in mptcp_inq_hint() that will be addressed by a later patch in the series. Co-developed-by: Geliang Tang Signed-off-by: Geliang Tang Signed-off-by: Paolo Abeni --- net/mptcp/fastopen.c | 2 +- net/mptcp/protocol.c | 37 +++++++++++++++++++++++++++++++++++-- net/mptcp/protocol.h | 4 +++- net/mptcp/subflow.c | 10 ++++++++++ 4 files changed, 49 insertions(+), 4 deletions(-) diff --git a/net/mptcp/fastopen.c b/net/mptcp/fastopen.c index 0012690a2202..e72fb982614a 100644 --- a/net/mptcp/fastopen.c +++ b/net/mptcp/fastopen.c @@ -50,12 +50,12 @@ void mptcp_fastopen_subflow_synack_set_params(struct mp= tcp_subflow_context *subf MPTCP_SKB_CB(skb)->end_seq =3D 0; MPTCP_SKB_CB(skb)->offset =3D 0; MPTCP_SKB_CB(skb)->has_rxtstamp =3D has_rxtstamp; - MPTCP_SKB_CB(skb)->cant_coalesce =3D 1; =20 mptcp_data_lock(sk); DEBUG_NET_WARN_ON_ONCE(sock_owned_by_user_nocheck(sk)); =20 msk =3D mptcp_sk(sk); + msk->rcvd_dummy_seq =3D true; mptcp_borrow_fwdmem(sk, skb); skb_set_owner_r(skb, sk); __skb_queue_tail(&sk->sk_receive_queue, skb); diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 39371a16b8bf..7d1422518aad 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -168,7 +168,6 @@ static bool __mptcp_try_coalesce(struct sock *sk, struc= t sk_buff *to, int limit =3D READ_ONCE(sk->sk_rcvbuf); =20 if (MPTCP_SKB_CB(from)->map_seq !=3D MPTCP_SKB_CB(to)->end_seq || - unlikely(MPTCP_SKB_CB(to)->cant_coalesce) || MPTCP_SKB_CB(from)->offset || ((to->len + from->len) > (limit >> 3)) || !skb_try_coalesce(to, from, fragstolen, delta)) @@ -430,7 +429,6 @@ static void mptcp_init_skb(struct sock *ssk, struct sk_= buff *skb, int offset, MPTCP_SKB_CB(skb)->end_seq =3D MPTCP_SKB_CB(skb)->map_seq + copy_len; MPTCP_SKB_CB(skb)->offset =3D offset; MPTCP_SKB_CB(skb)->has_rxtstamp =3D has_rxtstamp; - MPTCP_SKB_CB(skb)->cant_coalesce =3D 0; =20 __skb_unlink(skb, &ssk->sk_receive_queue); =20 @@ -438,6 +436,28 @@ static void mptcp_init_skb(struct sock *ssk, struct sk= _buff *skb, int offset, skb_dst_drop(skb); } =20 +void __mptcp_sync_rcv_sequence(struct sock *sk) +{ + struct mptcp_sock *msk =3D mptcp_sk(sk); + struct sk_buff *skb; + u64 ack_seq; + u32 offset; + + if (likely(!msk->rcvd_dummy_seq)) + return; + + /* User space can have already received the TFO skb. */ + msk->rcvd_dummy_seq =3D false; + skb =3D skb_peek_tail(&sk->sk_receive_queue); + if (!skb) + return; + + ack_seq =3D atomic64_read(&msk->ack_seq); + offset =3D MPTCP_SKB_CB(skb)->offset; + MPTCP_SKB_CB(skb)->map_seq =3D ack_seq - skb->len + offset; + MPTCP_SKB_CB(skb)->end_seq =3D ack_seq; +} + static bool __mptcp_move_skb(struct sock *sk, struct sk_buff *skb) { u64 copy_len =3D MPTCP_SKB_CB(skb)->end_seq - MPTCP_SKB_CB(skb)->map_seq; @@ -447,6 +467,12 @@ static bool __mptcp_move_skb(struct sock *sk, struct s= k_buff *skb) =20 mptcp_borrow_fwdmem(sk, skb); =20 + /* Be sure to sync the eventual fastopen dummy mapping before any other + * skb lands into the msk. + */ + if (unlikely(msk->rcvd_dummy_seq)) + __mptcp_sync_rcv_sequence(sk); + ack_seq =3D atomic64_read(&msk->ack_seq); if (MPTCP_SKB_CB(skb)->map_seq =3D=3D ack_seq) { /* in sequence */ @@ -3914,6 +3940,13 @@ static void mptcp_release_cb(struct sock *sk) __mptcp_error_report(sk); if (__test_and_clear_bit(MPTCP_SYNC_SNDBUF, &msk->cb_flags)) __mptcp_sync_sndbuf(sk); + if (test_and_clear_bit(MPTCP_SYNC_SEQ, &msk->cb_flags)) { + /* Ensure we see the updated ack_seq after seeing + * the flag + */ + smp_rmb(); + __mptcp_sync_rcv_sequence(sk); + } } } =20 diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index 29405d045291..839b1a36fc60 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -126,13 +126,13 @@ #define MPTCP_FLUSH_JOIN_LIST 5 #define MPTCP_SYNC_STATE 6 #define MPTCP_SYNC_SNDBUF 7 +#define MPTCP_SYNC_SEQ 8 =20 struct mptcp_skb_cb { u64 map_seq; u64 end_seq; u32 offset; u8 has_rxtstamp; - u8 cant_coalesce; }; =20 #define MPTCP_SKB_CB(__skb) ((struct mptcp_skb_cb *)&((__skb)->cb[0])) @@ -313,6 +313,7 @@ struct mptcp_sock { u32 token; unsigned long flags; unsigned long cb_flags; + bool rcvd_dummy_seq; bool recovery; /* closing subflow write queue reinjected */ bool can_ack; bool fully_established; @@ -1174,6 +1175,7 @@ void mptcp_event_pm_listener(const struct sock *ssk, enum mptcp_event_type event); bool mptcp_userspace_pm_active(const struct mptcp_sock *msk); =20 +void __mptcp_sync_rcv_sequence(struct sock *sk); void mptcp_fastopen_subflow_synack_set_params(struct mptcp_subflow_context= *subflow, struct request_sock *req); int mptcp_pm_genl_fill_addr(struct sk_buff *msg, diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index 8dc200d8d072..a6f231c6b4bf 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -478,6 +478,8 @@ static void subflow_set_remote_key(struct mptcp_sock *m= sk, struct mptcp_subflow_context *subflow, const struct mptcp_options_received *mp_opt) { + struct sock *sk =3D (struct sock *)msk; + /* active MPC subflow will reach here multiple times: * at subflow_finish_connect() time and at 4th ack time */ @@ -496,6 +498,14 @@ static void subflow_set_remote_key(struct mptcp_sock *= msk, atomic64_set(&msk->ack_seq, subflow->iasn); WRITE_ONCE(msk->can_ack, true); atomic64_set(&msk->rcv_wnd_sent, subflow->iasn); + + if (!sock_owned_by_user(sk)) { + __mptcp_sync_rcv_sequence(sk); + } else { + /* Ensure ack_seq is visible before setting the flag */ + smp_wmb(); + set_bit(MPTCP_SYNC_SEQ, &msk->cb_flags); + } } =20 static void mptcp_propagate_state(struct sock *sk, struct sock *ssk, --=20 2.53.0 From nobody Sat Sep 5 05:49:24 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 509A242E430 for ; Thu, 27 Aug 2026 10:57:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787828277; cv=none; b=qBDBZ5O9LJ4rigf8aACUaQdIyecF/MM1POA5w3ADObBvQpIXTmRywdY3n2fzye02sUT/j63KPfWhdo5YBj58Zn42x2Qe86x2X9uE7vck5FeNKKTPFX+TDIhPYuffnQp7HExlytrbWEKw7yZM9ymCTWofdDExO38R65RFYZPETZo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787828277; c=relaxed/simple; bh=k3Rl7CxpUFXgtZb02EBQDpTyip8VCLfGN124D3z5qU8=; 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charset="utf-8" From: Paolo Abeni Instead, use a new msk-level field to track the bytes already consumed inside each skb, carrying the amount of bytes already copied to user-space, alike what TCP is already doing. The newly introduce `copied_seq` field is always accessed under the msk socket lock, delegating the synchronization with IASN to the msk release CB, when the socket is owned by the user-space at remote key reception time. Such synchronization preserves any partial progress (copy) made on the TFO packet. Note that the explicit synchronization in __mptcp_move_skb() is needed to ensure that the TFO skb in the receive queue got its map_seq synched before the next skb lands into the receive queue when spooling the backlog at mptcp_release_cb() time, as the release CB synchronization will happen later. Prior to this patch, the TFO skb dummy mapping was always ignored, now it affects the `copied_seq` initial update: be sure to extends the sign correctly of such mapping initialization time. Overall this simplify a bit the __mptcp_recvmsg_mskq(), mptcp_inq_hint() and the __mptcp_move_skb() code and will also make possible the next patch. Initialize MPTCP sequence space to 0 in mptcp_propagate_state() when mp_opt is NULL, ensuring SKB's map_seq starts from 0 to match msk->copied_seq and prevent offset calculation underflow in fallback mode. Co-developed-by: Geliang Tang Signed-off-by: Geliang Tang Signed-off-by: Paolo Abeni --- net/mptcp/fastopen.c | 9 ++-- net/mptcp/protocol.c | 115 +++++++++++++++++++++---------------------- net/mptcp/protocol.h | 9 +++- net/mptcp/subflow.c | 9 ++++ 4 files changed, 79 insertions(+), 63 deletions(-) diff --git a/net/mptcp/fastopen.c b/net/mptcp/fastopen.c index e72fb982614a..15febd359f66 100644 --- a/net/mptcp/fastopen.c +++ b/net/mptcp/fastopen.c @@ -45,10 +45,11 @@ void mptcp_fastopen_subflow_synack_set_params(struct mp= tcp_subflow_context *subf subflow->ssn_offset +=3D skb->len; has_rxtstamp =3D TCP_SKB_CB(skb)->has_rxtstamp; =20 - /* Only the sequence delta is relevant */ - MPTCP_SKB_CB(skb)->map_seq =3D -skb->len; + /* The TFO segment data sits before the IASN; before receiving + * the remote key, IASN is assumed being 0. + */ + MPTCP_SKB_CB(skb)->map_seq =3D -(u64)skb->len; MPTCP_SKB_CB(skb)->end_seq =3D 0; - MPTCP_SKB_CB(skb)->offset =3D 0; MPTCP_SKB_CB(skb)->has_rxtstamp =3D has_rxtstamp; =20 mptcp_data_lock(sk); @@ -56,6 +57,8 @@ void mptcp_fastopen_subflow_synack_set_params(struct mptc= p_subflow_context *subf =20 msk =3D mptcp_sk(sk); msk->rcvd_dummy_seq =3D true; + msk->copied_seq =3D MPTCP_SKB_CB(skb)->map_seq; + msk->tfo_skb_len =3D skb->len; mptcp_borrow_fwdmem(sk, skb); skb_set_owner_r(skb, sk); __skb_queue_tail(&sk->sk_receive_queue, skb); diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 7d1422518aad..4cf7ad97ae0a 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -29,7 +29,7 @@ #include "protocol.h" #include "mib.h" =20 -static unsigned int mptcp_inq_hint(const struct sock *sk); +static unsigned int mptcp_inq_hint(struct sock *sk); =20 #define CREATE_TRACE_POINTS #include @@ -168,7 +168,6 @@ static bool __mptcp_try_coalesce(struct sock *sk, struc= t sk_buff *to, int limit =3D READ_ONCE(sk->sk_rcvbuf); =20 if (MPTCP_SKB_CB(from)->map_seq !=3D MPTCP_SKB_CB(to)->end_seq || - MPTCP_SKB_CB(from)->offset || ((to->len + from->len) > (limit >> 3)) || !skb_try_coalesce(to, from, fragstolen, delta)) return false; @@ -415,8 +414,7 @@ static void mptcp_data_queue_ofo(struct mptcp_sock *msk= , struct sk_buff *skb) skb_set_owner_r(skb, sk); } =20 -static void mptcp_init_skb(struct sock *ssk, struct sk_buff *skb, int offs= et, - int copy_len) +static void mptcp_init_skb(struct sock *ssk, struct sk_buff *skb, int offs= et) { struct mptcp_subflow_context *subflow =3D mptcp_subflow_ctx(ssk); bool has_rxtstamp =3D TCP_SKB_CB(skb)->has_rxtstamp; @@ -425,9 +423,9 @@ static void mptcp_init_skb(struct sock *ssk, struct sk_= buff *skb, int offset, * mptcp_subflow_get_mapped_dsn() is based on the current tp->copied_seq * value */ - MPTCP_SKB_CB(skb)->map_seq =3D mptcp_subflow_get_mapped_dsn(subflow); - MPTCP_SKB_CB(skb)->end_seq =3D MPTCP_SKB_CB(skb)->map_seq + copy_len; - MPTCP_SKB_CB(skb)->offset =3D offset; + MPTCP_SKB_CB(skb)->map_seq =3D mptcp_subflow_get_mapped_dsn(subflow) - + offset; + MPTCP_SKB_CB(skb)->end_seq =3D MPTCP_SKB_CB(skb)->map_seq + skb->len; MPTCP_SKB_CB(skb)->has_rxtstamp =3D has_rxtstamp; =20 __skb_unlink(skb, &ssk->sk_receive_queue); @@ -440,8 +438,6 @@ void __mptcp_sync_rcv_sequence(struct sock *sk) { struct mptcp_sock *msk =3D mptcp_sk(sk); struct sk_buff *skb; - u64 ack_seq; - u32 offset; =20 if (likely(!msk->rcvd_dummy_seq)) return; @@ -452,10 +448,8 @@ void __mptcp_sync_rcv_sequence(struct sock *sk) if (!skb) return; =20 - ack_seq =3D atomic64_read(&msk->ack_seq); - offset =3D MPTCP_SKB_CB(skb)->offset; - MPTCP_SKB_CB(skb)->map_seq =3D ack_seq - skb->len + offset; - MPTCP_SKB_CB(skb)->end_seq =3D ack_seq; + MPTCP_SKB_CB(skb)->map_seq =3D mptcp_iasn(msk) - skb->len; + MPTCP_SKB_CB(skb)->end_seq =3D MPTCP_SKB_CB(skb)->map_seq + skb->len; } =20 static bool __mptcp_move_skb(struct sock *sk, struct sk_buff *skb) @@ -467,6 +461,12 @@ static bool __mptcp_move_skb(struct sock *sk, struct s= k_buff *skb) =20 mptcp_borrow_fwdmem(sk, skb); =20 + if (test_and_clear_bit(MPTCP_SYNC_SEQ, &msk->cb_flags)) { + /* Ensure we see the updated ack_seq after seeing the flag */ + smp_rmb(); + msk->copied_seq +=3D mptcp_iasn(msk); + } + /* Be sure to sync the eventual fastopen dummy mapping before any other * skb lands into the msk. */ @@ -500,10 +500,6 @@ static bool __mptcp_move_skb(struct sock *sk, struct s= k_buff *skb) /* Partial packet */ if (after64(MPTCP_SKB_CB(skb)->end_seq, ack_seq)) { copy_len =3D MPTCP_SKB_CB(skb)->end_seq - ack_seq; - MPTCP_SKB_CB(skb)->offset +=3D ack_seq - - MPTCP_SKB_CB(skb)->map_seq; - MPTCP_SKB_CB(skb)->map_seq +=3D ack_seq - - MPTCP_SKB_CB(skb)->map_seq; goto insert; } =20 @@ -861,7 +857,7 @@ static bool __mptcp_move_skbs_from_subflow(struct mptcp= _sock *msk, if (offset < skb->len) { size_t len =3D skb->len - offset; =20 - mptcp_init_skb(ssk, skb, offset, len); + mptcp_init_skb(ssk, skb, offset); =20 if (own_msk) { mptcp_subflow_lend_fwdmem(subflow, skb); @@ -928,8 +924,6 @@ static bool __mptcp_ofo_queue(struct mptcp_sock *msk) pr_debug("uncoalesced seq=3D%llx ack seq=3D%llx delta=3D%d\n", MPTCP_SKB_CB(skb)->map_seq, ack_seq, delta); - MPTCP_SKB_CB(skb)->offset +=3D delta; - MPTCP_SKB_CB(skb)->map_seq +=3D delta; __skb_queue_tail(&sk->sk_receive_queue, skb); } atomic64_add(end_seq - ack_seq, &msk->bytes_received); @@ -2209,33 +2203,24 @@ static void mptcp_eat_recv_skb(struct sock *sk, str= uct sk_buff *skb) } =20 static int __mptcp_recvmsg_mskq(struct sock *sk, struct msghdr *msg, - size_t len, int flags, int copied_total, + size_t len, int flags, u64 *seq, struct scm_timestamping_internal *tss, int *cmsg_flags, struct sk_buff **last) { struct mptcp_sock *msk =3D mptcp_sk(sk); struct sk_buff *skb, *tmp; - int total_data_len =3D 0; int copied =3D 0; =20 skb_queue_walk_safe(&sk->sk_receive_queue, skb, tmp) { - u32 delta, offset =3D MPTCP_SKB_CB(skb)->offset; + u64 offset =3D *seq - MPTCP_SKB_CB(skb)->map_seq; u32 data_len =3D skb->len - offset; u32 count; int err; =20 - if (flags & MSG_PEEK) { - /* skip already peeked skbs */ - if (total_data_len + data_len <=3D copied_total) { - total_data_len +=3D data_len; - *last =3D skb; - continue; - } - - /* skip the already peeked data in the current skb */ - delta =3D copied_total - total_data_len; - offset +=3D delta; - data_len -=3D delta; + /* Skip the already peeked data. */ + if (offset >=3D skb->len) { + *last =3D skb; + continue; } =20 count =3D min_t(size_t, len - copied, data_len); @@ -2254,14 +2239,12 @@ static int __mptcp_recvmsg_mskq(struct sock *sk, st= ruct msghdr *msg, } =20 copied +=3D count; + *seq +=3D count; =20 if (!(flags & MSG_PEEK)) { atomic64_add(count, &msk->bytes_consumed); - if (count < data_len) { - MPTCP_SKB_CB(skb)->offset +=3D count; - MPTCP_SKB_CB(skb)->map_seq +=3D count; + if (count < data_len) break; - } =20 mptcp_eat_recv_skb(sk, skb); } else { @@ -2414,27 +2397,27 @@ static bool mptcp_move_skbs(struct sock *sk) return enqueued; } =20 -static unsigned int mptcp_inq_hint(const struct sock *sk) +static unsigned int mptcp_inq_hint(struct sock *sk) { const struct mptcp_sock *msk =3D mptcp_sk(sk); - const struct sk_buff *skb; u64 hint_val, ack_seq; =20 - skb =3D skb_peek(&sk->sk_receive_queue); - if (skb) { - ack_seq =3D atomic64_read(&msk->ack_seq); - hint_val =3D ack_seq - MPTCP_SKB_CB(skb)->map_seq; - - if (hint_val >=3D INT_MAX) - return INT_MAX; + if (test_bit(MPTCP_SYNC_SEQ, &msk->cb_flags)) + return 0; =20 - return (unsigned int)hint_val; - } + /* Avoid races vs ack_seq updates. */ + mptcp_data_lock(sk); + ack_seq =3D atomic64_read(&msk->ack_seq); + hint_val =3D ack_seq - msk->copied_seq; + mptcp_data_unlock(sk); + if (hint_val >=3D INT_MAX) + return INT_MAX; =20 - if (sk->sk_state =3D=3D TCP_CLOSE || (sk->sk_shutdown & RCV_SHUTDOWN)) + if (!hint_val && + (sk->sk_state =3D=3D TCP_CLOSE || (sk->sk_shutdown & RCV_SHUTDOWN))) return 1; =20 - return 0; + return (unsigned int)hint_val; } =20 static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, @@ -2443,6 +2426,7 @@ static int mptcp_recvmsg(struct sock *sk, struct msgh= dr *msg, size_t len, struct mptcp_sock *msk =3D mptcp_sk(sk); struct scm_timestamping_internal tss; int copied =3D 0, cmsg_flags =3D 0; + u64 peek_seq, *seq; int target; long timeo; =20 @@ -2461,6 +2445,11 @@ static int mptcp_recvmsg(struct sock *sk, struct msg= hdr *msg, size_t len, =20 len =3D min_t(size_t, len, INT_MAX); target =3D sock_rcvlowat(sk, flags & MSG_WAITALL, len); + seq =3D &msk->copied_seq; + if (flags & MSG_PEEK) { + peek_seq =3D msk->copied_seq; + seq =3D &peek_seq; + } =20 if (unlikely(msk->recvmsg_inq)) cmsg_flags =3D MPTCP_CMSG_INQ; @@ -2470,7 +2459,7 @@ static int mptcp_recvmsg(struct sock *sk, struct msgh= dr *msg, size_t len, int err, bytes_read; =20 bytes_read =3D __mptcp_recvmsg_mskq(sk, msg, len - copied, flags, - copied, &tss, &cmsg_flags, + seq, &tss, &cmsg_flags, &last); if (unlikely(bytes_read < 0)) { if (!copied) @@ -2480,8 +2469,11 @@ static int mptcp_recvmsg(struct sock *sk, struct msg= hdr *msg, size_t len, =20 copied +=3D bytes_read; =20 - if (!list_empty(&msk->backlog_list) && mptcp_move_skbs(sk)) + if (!list_empty(&msk->backlog_list) && mptcp_move_skbs(sk)) { + if (flags & MSG_PEEK) + peek_seq =3D msk->copied_seq + copied; continue; + } =20 /* only the MPTCP socket status is relevant here. The exit * conditions mirror closely tcp_recvmsg() @@ -2525,6 +2517,10 @@ static int mptcp_recvmsg(struct sock *sk, struct msg= hdr *msg, size_t len, err =3D copied ? : err; goto out_err; } + + /* Recompute peek offset after eventual seq resync. */ + if (flags & MSG_PEEK) + peek_seq =3D msk->copied_seq + copied; } =20 mptcp_cleanup_rbuf(msk, copied); @@ -3710,11 +3706,13 @@ static int mptcp_disconnect(struct sock *sk, int fl= ags) msk->bytes_retrans =3D 0; msk->rcvspace_init =3D 0; msk->fastclosing =3D 0; + msk->tfo_skb_len =3D 0; mptcp_init_rtt_est(msk); =20 /* for fallback's sake */ atomic64_set(&msk->ack_seq, 0); atomic64_set(&msk->rcv_wnd_sent, 0); + msk->copied_seq =3D 0; =20 WRITE_ONCE(sk->sk_shutdown, 0); sk_error_report(sk); @@ -3945,6 +3943,7 @@ static void mptcp_release_cb(struct sock *sk) * the flag */ smp_rmb(); + msk->copied_seq +=3D mptcp_iasn(msk); __mptcp_sync_rcv_sequence(sk); } } @@ -4609,7 +4608,7 @@ static struct sk_buff *mptcp_recv_skb(struct sock *sk= , u32 *off) mptcp_move_skbs(sk); =20 while ((skb =3D skb_peek(&sk->sk_receive_queue)) !=3D NULL) { - offset =3D MPTCP_SKB_CB(skb)->offset; + offset =3D msk->copied_seq - MPTCP_SKB_CB(skb)->map_seq; if (offset < skb->len) { *off =3D offset; return skb; @@ -4651,11 +4650,9 @@ static int __mptcp_read_sock(struct sock *sk, read_d= escriptor_t *desc, copied +=3D count; =20 atomic64_add(count, &msk->bytes_consumed); - if (count < data_len) { - MPTCP_SKB_CB(skb)->offset +=3D count; - MPTCP_SKB_CB(skb)->map_seq +=3D count; + msk->copied_seq +=3D count; + if (count < data_len) break; - } =20 mptcp_eat_recv_skb(sk, skb); if (!desc->count) diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index 839b1a36fc60..1a0ba1ba3e87 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -131,7 +131,6 @@ struct mptcp_skb_cb { u64 map_seq; u64 end_seq; - u32 offset; u8 has_rxtstamp; }; =20 @@ -292,6 +291,7 @@ struct mptcp_sock { u64 bytes_sent; atomic64_t snd_nxt; atomic64_t bytes_received; + u64 copied_seq; atomic64_t ack_seq; atomic64_t rcv_wnd_sent; u64 rcv_data_fin_seq; @@ -311,6 +311,7 @@ struct mptcp_sock { u32 last_ack_recv; unsigned long timer_ival; u32 token; + u32 tfo_skb_len; unsigned long flags; unsigned long cb_flags; bool rcvd_dummy_seq; @@ -865,6 +866,12 @@ struct sock *mptcp_subflow_get_retrans(struct mptcp_so= ck *msk); int mptcp_sched_get_send(struct mptcp_sock *msk); int mptcp_sched_get_retrans(struct mptcp_sock *msk); =20 +static inline u64 mptcp_iasn(const struct mptcp_sock *msk) +{ + return atomic64_read(&msk->ack_seq) - + atomic64_read(&msk->bytes_received) + msk->tfo_skb_len; +} + static inline u64 mptcp_data_avail(const struct mptcp_sock *msk) { return atomic64_read(&msk->bytes_received) - diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index a6f231c6b4bf..37594143fdc0 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -500,6 +500,8 @@ static void subflow_set_remote_key(struct mptcp_sock *m= sk, atomic64_set(&msk->rcv_wnd_sent, subflow->iasn); =20 if (!sock_owned_by_user(sk)) { + /* User space could have already read partially the TFO skb */ + msk->copied_seq +=3D subflow->iasn; __mptcp_sync_rcv_sequence(sk); } else { /* Ensure ack_seq is visible before setting the flag */ @@ -523,6 +525,13 @@ static void mptcp_propagate_state(struct sock *sk, str= uct sock *ssk, atomic64_set(&msk->snd_una, seq); atomic64_set(&msk->wnd_end, seq + tcp_sk(ssk)->snd_wnd); subflow_set_remote_key(msk, subflow, mp_opt); + } else { + /* Fallback: initialize sequence space to 0 (no remote key) */ + subflow->map_seq =3D 0; + /* ensure mptcp_subflow_get_map_offset() returns 0 */ + subflow->map_subflow_seq =3D tcp_sk(ssk)->copied_seq - + subflow->ssn_offset; + atomic64_set(&msk->ack_seq, 0); } =20 if (!sock_owned_by_user(sk)) { --=20 2.53.0 From nobody Sat Sep 5 05:49:24 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6A4E8440A1F for ; Thu, 27 Aug 2026 10:57:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; 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Thu, 27 Aug 2026 10:57:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787828277; bh=vwrnq/ki1yzQPJ//btWpjAVS6RE1jhiiyRaOEHb+pjg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=llU6OgPIYrC8R3HEyyCmjh7y4L23BsaBaNwu50QEKYpsSQeeXFJ9eKboed/C0iGA7 SmkhMxFaZiWBTTvw54uWE5b81yFG71hUn/pTsjzcP3XxeFC5qoqWs7yeCR6uDiNy4S VphcnT8xT58DCNZKKWR0Am9Rdav7aN3Wk/Nc1Zjy99QfEGwsthCyuSOrKlJbWVGgU2 HGE/ihIlgYpGIUgtYVhROKl09u4onyQg5Z7hQXINlNzaAZhus7mSbnZRVZ5TNFFSkr k+0/0MHyKoGDGuE1GxmBVsuyUNg+HKE5cQF6ikz8CexcgCa07HZfmw27POmhc7sejJ fd3EbTf0apgBQ== From: Geliang Tang To: mptcp@lists.linux.dev Cc: Paolo Abeni , Geliang Tang Subject: [PATCH mptcp-next v9 05/11] mptcp: sync mptcp skb cb layout with tcp one Date: Thu, 27 Aug 2026 18:57:29 +0800 Message-ID: <6daf67eb21d99b11d8e08a5d9388353eb6a71782.1787827525.git.tanggeliang@kylinos.cn> X-Mailer: git-send-email 2.53.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Paolo Abeni The MPTCP protocol uses a significantly different CB layout WRT TCP, as it includes different information and use 64 bits for the sequence numbers. As the msk-level rcvbuf buffer size is limited by the core socket code the INT_MAX; after validating the incoming skb vs the current receive window, we can safely use 32 bits for MPTCP-level sequence number. This allow updating the MPTCP CB layout so that fields with a corresponding TCP-level data use the same area inside the CB itself. Add build time check to ensure the latter invariant. Co-developed-by: Geliang Tang Signed-off-by: Geliang Tang Signed-off-by: Paolo Abeni --- net/mptcp/fastopen.c | 6 ++-- net/mptcp/protocol.c | 81 +++++++++++++++++++++++++++----------------- net/mptcp/protocol.h | 7 ++-- 3 files changed, 59 insertions(+), 35 deletions(-) diff --git a/net/mptcp/fastopen.c b/net/mptcp/fastopen.c index 15febd359f66..62dab62e00f9 100644 --- a/net/mptcp/fastopen.c +++ b/net/mptcp/fastopen.c @@ -48,8 +48,10 @@ void mptcp_fastopen_subflow_synack_set_params(struct mpt= cp_subflow_context *subf /* The TFO segment data sits before the IASN; before receiving * the remote key, IASN is assumed being 0. */ - MPTCP_SKB_CB(skb)->map_seq =3D -(u64)skb->len; + MPTCP_SKB_CB(skb)->map_seq64 =3D -(u64)skb->len; + MPTCP_SKB_CB(skb)->map_seq =3D MPTCP_SKB_CB(skb)->map_seq64; MPTCP_SKB_CB(skb)->end_seq =3D 0; + MPTCP_SKB_CB(skb)->flags =3D 0; MPTCP_SKB_CB(skb)->has_rxtstamp =3D has_rxtstamp; =20 mptcp_data_lock(sk); @@ -57,7 +59,7 @@ void mptcp_fastopen_subflow_synack_set_params(struct mptc= p_subflow_context *subf =20 msk =3D mptcp_sk(sk); msk->rcvd_dummy_seq =3D true; - msk->copied_seq =3D MPTCP_SKB_CB(skb)->map_seq; + msk->copied_seq =3D MPTCP_SKB_CB(skb)->map_seq64; msk->tfo_skb_len =3D skb->len; mptcp_borrow_fwdmem(sk, skb); skb_set_owner_r(skb, sk); diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 4cf7ad97ae0a..e53d5c184065 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -172,7 +172,7 @@ static bool __mptcp_try_coalesce(struct sock *sk, struc= t sk_buff *to, !skb_try_coalesce(to, from, fragstolen, delta)) return false; =20 - pr_debug("colesced seq %llx into %llx new len %d new end seq %llx\n", + pr_debug("colesced seq %x into %x new len %d new end seq %x\n", MPTCP_SKB_CB(from)->map_seq, MPTCP_SKB_CB(to)->map_seq, to->len, MPTCP_SKB_CB(from)->end_seq); MPTCP_SKB_CB(to)->end_seq =3D MPTCP_SKB_CB(from)->end_seq; @@ -254,8 +254,8 @@ static void mptcp_prune_ofo_queue(struct sock *sk, struct sk_buff *skb =3D rb_to_skb(node); =20 /* Stop pruning if the incoming skb would land in OoO tail. */ - if (after64(MPTCP_SKB_CB(in_skb)->map_seq, - MPTCP_SKB_CB(skb)->map_seq)) + if (after(MPTCP_SKB_CB(in_skb)->map_seq, + MPTCP_SKB_CB(skb)->map_seq)) break; =20 pruned =3D true; @@ -301,15 +301,19 @@ static void mptcp_data_queue_ofo(struct mptcp_sock *m= sk, struct sk_buff *skb) { struct sock *sk =3D (struct sock *)msk; struct rb_node **p, *parent; - u64 seq, end_seq, max_seq; + u64 end_seq, max_seq; struct sk_buff *skb1; + u32 seq; =20 seq =3D MPTCP_SKB_CB(skb)->map_seq; - end_seq =3D MPTCP_SKB_CB(skb)->end_seq; + end_seq =3D MPTCP_SKB_CB(skb)->map_seq64 + skb->len; max_seq =3D atomic64_read(&msk->rcv_wnd_sent); =20 - pr_debug("msk=3D%p seq=3D%llx limit=3D%llx empty=3D%d\n", msk, seq, max_s= eq, + pr_debug("msk=3D%p seq=3D%x limit=3D%llx empty=3D%d\n", msk, seq, max_seq, RB_EMPTY_ROOT(&msk->out_of_order_queue)); + /* Use the full sequence space to perform the admission checks, to + * protect vs possible wrap-arounds. + */ if (after64(end_seq, max_seq)) { /* out of window */ mptcp_drop(sk, skb); @@ -345,7 +349,7 @@ static void mptcp_data_queue_ofo(struct mptcp_sock *msk= , struct sk_buff *skb) } =20 /* Can avoid an rbtree lookup if we are adding skb after ooo_last_skb */ - if (!before64(seq, MPTCP_SKB_CB(msk->ooo_last_skb)->end_seq)) { + if (!before(seq, MPTCP_SKB_CB(msk->ooo_last_skb)->end_seq)) { MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_OFOQUEUETAIL); parent =3D &msk->ooo_last_skb->rbnode; p =3D &parent->rb_right; @@ -357,18 +361,18 @@ static void mptcp_data_queue_ofo(struct mptcp_sock *m= sk, struct sk_buff *skb) while (*p) { parent =3D *p; skb1 =3D rb_to_skb(parent); - if (before64(seq, MPTCP_SKB_CB(skb1)->map_seq)) { + if (before(seq, MPTCP_SKB_CB(skb1)->map_seq)) { p =3D &parent->rb_left; continue; } - if (before64(seq, MPTCP_SKB_CB(skb1)->end_seq)) { - if (!after64(end_seq, MPTCP_SKB_CB(skb1)->end_seq)) { + if (before(seq, MPTCP_SKB_CB(skb1)->end_seq)) { + if (!after(end_seq, MPTCP_SKB_CB(skb1)->end_seq)) { /* All the bits are present. Drop. */ mptcp_drop(sk, skb); MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_DUPDATA); return; } - if (after64(seq, MPTCP_SKB_CB(skb1)->map_seq)) { + if (after(seq, MPTCP_SKB_CB(skb1)->map_seq)) { /* partial overlap: * | skb | * | skb1 | @@ -399,7 +403,7 @@ static void mptcp_data_queue_ofo(struct mptcp_sock *msk= , struct sk_buff *skb) merge_right: /* Remove other segments covered by skb. */ while ((skb1 =3D skb_rb_next(skb)) !=3D NULL) { - if (before64(end_seq, MPTCP_SKB_CB(skb1)->end_seq)) + if (before((u32)end_seq, MPTCP_SKB_CB(skb1)->end_seq)) break; rb_erase(&skb1->rbnode, &msk->out_of_order_queue); mptcp_drop(sk, skb1); @@ -421,11 +425,13 @@ static void mptcp_init_skb(struct sock *ssk, struct s= k_buff *skb, int offset) =20 /* the skb map_seq accounts for the skb offset: * mptcp_subflow_get_mapped_dsn() is based on the current tp->copied_seq - * value + * value; note that end seq number is only available in 32bits format. */ - MPTCP_SKB_CB(skb)->map_seq =3D mptcp_subflow_get_mapped_dsn(subflow) - - offset; + MPTCP_SKB_CB(skb)->map_seq64 =3D mptcp_subflow_get_mapped_dsn(subflow) - + offset; + MPTCP_SKB_CB(skb)->map_seq =3D (u32)MPTCP_SKB_CB(skb)->map_seq64; MPTCP_SKB_CB(skb)->end_seq =3D MPTCP_SKB_CB(skb)->map_seq + skb->len; + MPTCP_SKB_CB(skb)->flags =3D 0; MPTCP_SKB_CB(skb)->has_rxtstamp =3D has_rxtstamp; =20 __skb_unlink(skb, &ssk->sk_receive_queue); @@ -448,13 +454,14 @@ void __mptcp_sync_rcv_sequence(struct sock *sk) if (!skb) return; =20 - MPTCP_SKB_CB(skb)->map_seq =3D mptcp_iasn(msk) - skb->len; + MPTCP_SKB_CB(skb)->map_seq64 =3D mptcp_iasn(msk) - skb->len; + MPTCP_SKB_CB(skb)->map_seq =3D (u32)MPTCP_SKB_CB(skb)->map_seq64; MPTCP_SKB_CB(skb)->end_seq =3D MPTCP_SKB_CB(skb)->map_seq + skb->len; } =20 static bool __mptcp_move_skb(struct sock *sk, struct sk_buff *skb) { - u64 copy_len =3D MPTCP_SKB_CB(skb)->end_seq - MPTCP_SKB_CB(skb)->map_seq; + u32 copy_len =3D MPTCP_SKB_CB(skb)->end_seq - MPTCP_SKB_CB(skb)->map_seq; struct mptcp_sock *msk =3D mptcp_sk(sk); struct sk_buff *tail; u64 ack_seq; @@ -474,7 +481,7 @@ static bool __mptcp_move_skb(struct sock *sk, struct sk= _buff *skb) __mptcp_sync_rcv_sequence(sk); =20 ack_seq =3D atomic64_read(&msk->ack_seq); - if (MPTCP_SKB_CB(skb)->map_seq =3D=3D ack_seq) { + if (MPTCP_SKB_CB(skb)->map_seq64 =3D=3D ack_seq) { /* in sequence */ insert: if (!mptcp_try_rmem_schedule(sk, skb)) { @@ -492,14 +499,14 @@ static bool __mptcp_move_skb(struct sock *sk, struct = sk_buff *skb) skb_set_owner_r(skb, sk); __skb_queue_tail(&sk->sk_receive_queue, skb); return true; - } else if (after64(MPTCP_SKB_CB(skb)->map_seq, ack_seq)) { + } else if (after64(MPTCP_SKB_CB(skb)->map_seq64, ack_seq)) { mptcp_data_queue_ofo(msk, skb); return false; } =20 /* Partial packet */ - if (after64(MPTCP_SKB_CB(skb)->end_seq, ack_seq)) { - copy_len =3D MPTCP_SKB_CB(skb)->end_seq - ack_seq; + if (after64(MPTCP_SKB_CB(skb)->map_seq64 + skb->len, ack_seq)) { + copy_len =3D MPTCP_SKB_CB(skb)->end_seq - (u32)ack_seq; goto insert; } =20 @@ -894,40 +901,40 @@ static bool __mptcp_ofo_queue(struct mptcp_sock *msk) { struct sock *sk =3D (struct sock *)msk; struct sk_buff *skb, *tail; - u64 end_seq, ack_seq; + u32 seq_delta, ack_seq; bool moved =3D false; struct rb_node *p; =20 p =3D rb_first(&msk->out_of_order_queue); pr_debug("msk=3D%p empty=3D%d\n", msk, RB_EMPTY_ROOT(&msk->out_of_order_q= ueue)); while (p) { - ack_seq =3D atomic64_read(&msk->ack_seq); + ack_seq =3D (u32)atomic64_read(&msk->ack_seq); skb =3D rb_to_skb(p); - if (after64(MPTCP_SKB_CB(skb)->map_seq, ack_seq)) + if (after(MPTCP_SKB_CB(skb)->map_seq, ack_seq)) break; =20 p =3D rb_next(p); rb_erase(&skb->rbnode, &msk->out_of_order_queue); =20 - if (unlikely(!after64(MPTCP_SKB_CB(skb)->end_seq, ack_seq))) { + if (unlikely(!after(MPTCP_SKB_CB(skb)->end_seq, ack_seq))) { mptcp_drop(sk, skb); MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_DUPDATA); continue; } =20 - end_seq =3D MPTCP_SKB_CB(skb)->end_seq; + seq_delta =3D MPTCP_SKB_CB(skb)->end_seq - ack_seq; tail =3D skb_peek_tail(&sk->sk_receive_queue); if (!tail || !mptcp_try_coalesce(sk, tail, skb)) { int delta =3D ack_seq - MPTCP_SKB_CB(skb)->map_seq; =20 /* skip overlapping data, if any */ - pr_debug("uncoalesced seq=3D%llx ack seq=3D%llx delta=3D%d\n", + pr_debug("uncoalesced seq=3D%x ack seq=3D%x delta=3D%d\n", MPTCP_SKB_CB(skb)->map_seq, ack_seq, delta); __skb_queue_tail(&sk->sk_receive_queue, skb); } - atomic64_add(end_seq - ack_seq, &msk->bytes_received); - atomic64_set(&msk->ack_seq, end_seq); + atomic64_add(seq_delta, &msk->bytes_received); + atomic64_add(seq_delta, &msk->ack_seq); moved =3D true; } return moved; @@ -2212,7 +2219,7 @@ static int __mptcp_recvmsg_mskq(struct sock *sk, stru= ct msghdr *msg, int copied =3D 0; =20 skb_queue_walk_safe(&sk->sk_receive_queue, skb, tmp) { - u64 offset =3D *seq - MPTCP_SKB_CB(skb)->map_seq; + u32 offset =3D (u32)(*seq) - MPTCP_SKB_CB(skb)->map_seq; u32 data_len =3D skb->len - offset; u32 count; int err; @@ -4608,7 +4615,7 @@ static struct sk_buff *mptcp_recv_skb(struct sock *sk= , u32 *off) mptcp_move_skbs(sk); =20 while ((skb =3D skb_peek(&sk->sk_receive_queue)) !=3D NULL) { - offset =3D msk->copied_seq - MPTCP_SKB_CB(skb)->map_seq; + offset =3D (u32)msk->copied_seq - MPTCP_SKB_CB(skb)->map_seq; if (offset < skb->len) { *off =3D offset; return skb; @@ -4859,11 +4866,23 @@ static int mptcp_napi_poll(struct napi_struct *napi= , int budget) return work_done; } =20 +#define CHK_CB_FIELD(mptcp_field, tcp_field) \ + ({ \ + BUILD_BUG_ON(offsetof(struct mptcp_skb_cb, mptcp_field) !=3D \ + offsetof(struct tcp_skb_cb, tcp_field)); \ + BUILD_BUG_ON(offsetofend(struct mptcp_skb_cb, mptcp_field) !=3D \ + offsetofend(struct tcp_skb_cb, tcp_field)); \ + }) + void __init mptcp_proto_init(void) { struct mptcp_delegated_action *delegated; int cpu; =20 + CHK_CB_FIELD(map_seq, seq); + CHK_CB_FIELD(end_seq, end_seq); + CHK_CB_FIELD(flags, tcp_flags); + mptcp_prot.h.hashinfo =3D tcp_prot.h.hashinfo; =20 if (percpu_counter_init(&mptcp_sockets_allocated, 0, GFP_KERNEL)) diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index 1a0ba1ba3e87..a00cf6898463 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -129,9 +129,12 @@ #define MPTCP_SYNC_SEQ 8 =20 struct mptcp_skb_cb { - u64 map_seq; 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charset="utf-8" From: Paolo Abeni When MPTCP carries TLS, the data path runs under mptcp_data_lock(). Reaching sk->sk_data_ready(sk) synchronously ends up at tls_strp_check_rcv() -> mptcp_recv_skb() -> mptcp_move_skbs(), which calls mptcp_data_lock() on the same sk and recurses on sk_lock.slock. The TLS path is not the only constraint: before the mptcp_recv_skb() calls, the TLS code would also reach __mptcp_read_sock(), which calls mptcp_rcv_space_adjust() and mptcp_cleanup_rbuf(). Both require holding the msk socket lock in process context, while the mptcp/TLS caller is in BH scope. Fix this by deferring sk->sk_data_ready(sk) to mptcp_worker() via a new MPTCP_WORK_READ_COMPLETE bit, reusing the existing mptcp_schedule_work()/ mptcp_cancel_work() infrastructure. The wakeup bit is consumed after the SOCK_DEAD && TCP_CLOSE destroy branch, so a socket that reaches the destroy path drops the pending wakeup rather than running it post-free. Co-developed-by: Geliang Tang Signed-off-by: Geliang Tang Signed-off-by: Paolo Abeni --- net/mptcp/protocol.c | 32 ++++++++++++++++++++++++-------- net/mptcp/protocol.h | 2 ++ 2 files changed, 26 insertions(+), 8 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index e53d5c184065..cc8747162cca 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -3149,6 +3149,20 @@ static void mptcp_backlog_purge(struct sock *sk) sk_mem_reclaim(sk); } =20 +static void mptcp_read_complete(struct sock *sk) +{ + struct mptcp_sock *msk =3D mptcp_sk(sk); + int read_copied; + + mptcp_data_lock(sk); + read_copied =3D msk->read_copied; + msk->read_copied =3D 0; + mptcp_data_unlock(sk); + + mptcp_rcv_space_adjust(msk, read_copied); + mptcp_cleanup_rbuf(msk, read_copied); +} + static void mptcp_do_fastclose(struct sock *sk) { struct mptcp_subflow_context *subflow, *tmp; @@ -3225,6 +3239,9 @@ static void mptcp_worker(struct work_struct *work) if (test_and_clear_bit(MPTCP_WORK_RTX, &msk->flags)) __mptcp_retrans(sk); =20 + if (test_and_clear_bit(MPTCP_WORK_READ_COMPLETE, &msk->flags)) + mptcp_read_complete(sk); + fail_tout =3D msk->first ? READ_ONCE(mptcp_subflow_ctx(msk->first)->fail_= tout) : 0; if (fail_tout && time_after(jiffies, fail_tout)) mptcp_mp_fail_no_response(msk); @@ -4611,9 +4628,6 @@ static struct sk_buff *mptcp_recv_skb(struct sock *sk= , u32 *off) struct sk_buff *skb; u32 offset; =20 - if (!list_empty(&msk->backlog_list)) - mptcp_move_skbs(sk); - while ((skb =3D skb_peek(&sk->sk_receive_queue)) !=3D NULL) { offset =3D (u32)msk->copied_seq - MPTCP_SKB_CB(skb)->map_seq; if (offset < skb->len) { @@ -4628,6 +4642,7 @@ static struct sk_buff *mptcp_recv_skb(struct sock *sk= , u32 *off) /* * Note: * - It is assumed that the socket was locked by the caller. + * - Can be invoked in BH scope. */ static int __mptcp_read_sock(struct sock *sk, read_descriptor_t *desc, sk_read_actor_t recv_actor, bool noack) @@ -4637,8 +4652,6 @@ static int __mptcp_read_sock(struct sock *sk, read_de= scriptor_t *desc, int copied =3D 0; u32 offset; =20 - msk_owned_by_me(msk); - if (sk->sk_state =3D=3D TCP_LISTEN) return -ENOTCONN; while ((skb =3D mptcp_recv_skb(sk, &offset)) !=3D NULL) { @@ -4669,11 +4682,14 @@ static int __mptcp_read_sock(struct sock *sk, read_= descriptor_t *desc, if (noack) goto out; =20 - mptcp_rcv_space_adjust(msk, copied); - + /* The backlog flushing is only needed when some data is actually + * moved and will take place in the workers's release callback. + */ if (copied > 0) { mptcp_recv_skb(sk, &offset); - mptcp_cleanup_rbuf(msk, copied); + msk->read_copied +=3D copied; + set_bit(MPTCP_WORK_READ_COMPLETE, &msk->flags); + mptcp_schedule_work(sk); } out: return copied; diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index a00cf6898463..06fddbe742c8 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -117,6 +117,7 @@ #define MPTCP_FALLBACK_DONE 2 #define MPTCP_WORK_CLOSE_SUBFLOW 3 #define MPTCP_RTX_DISABLED 4 +#define MPTCP_WORK_READ_COMPLETE 5 =20 /* MPTCP socket release cb flags */ #define MPTCP_PUSH_PENDING 1 @@ -312,6 +313,7 @@ struct mptcp_sock { u32 last_data_sent; u32 last_data_recv; u32 last_ack_recv; + int read_copied; unsigned long timer_ival; u32 token; u32 tfo_skb_len; --=20 2.53.0 From nobody Sat Sep 5 05:49:24 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B96B6440632 for ; Thu, 27 Aug 2026 10:58:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787828284; cv=none; b=ihCVd4zAKxNqNvtDvhL25REbtwFIY5hHN5G2Su0273y9pIWSGTCHXpdULrRhYa6sSHiT537YMAobDXlMrPnymrXLy3S94uRqJuWTIy0xyA4flZzCqeFbShINE3F0GAfAXkHrwWpjjM2HAOVdR5eeLIfajFqIu9y6gubk7sYNRd0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787828284; c=relaxed/simple; bh=UsnK80bQxJ5CTpgzxMEMVTC0aOwOh0VuJFR5BF0el7M=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=KFkX0EPvHU+bcOMZ4n+zJ8p5jYjOHMEBH1EzM8tJldO9PxDQwFIUPA3hBLksf0wctc1qwPpekQJkiAkTTZ55tHEahlYLU/nwZ+A5d6d+knhzENwbR0mM/dg1pEV7q/3VirkG7PGSUbMDgIWXv5zzkDApH/F+Zc+pqB+3AB1se7E= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Qb1aqV+s; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Qb1aqV+s" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6588E1F00A3D; Thu, 27 Aug 2026 10:57:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787828280; bh=2QuhRmcTFWU1G0kzMePFR7sqAlX1+wct/Qya/fxafxk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Qb1aqV+sOk0GG2UNXpiIcvaiFEGIGCfg6w9fWkt7PhEGgx3Afxf9NjKha6tViB5H8 YC0f9AU5gjzciTEn3Oog7gRrNfcqGlAcdP3wZB51y9Q/yV/zdIoMq/HIAGGp4tVELA g9yVHqTsmKPiMbCFDczKlxFB59+673XBawzDTJOie2AkFwoGXMQ9Fs4bqHNEOvk4/H dlvNLKS6K5igIM5a3eJ6bcULcAwBAnrR3CuYRH0lRBe1acBX5kAlsZI9G3JaceTPmB 5TS/p/yP5DUIyiLeRZ01JTXnorBI3/ohUfKGvMmYEve9h8DVP2X0+YzJbIYzjvUZU6 vv2hbcwP1CL8w== From: Geliang Tang To: mptcp@lists.linux.dev Cc: Geliang Tang Subject: [PATCH mptcp-next v9 07/11] mptcp: implement peek_len for proto_ops Date: Thu, 27 Aug 2026 18:57:31 +0800 Message-ID: <72dfb12c36ea32e58f8f85f55c94101fca02702e.1787827525.git.tanggeliang@kylinos.cn> X-Mailer: git-send-email 2.53.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Geliang Tang Add mptcp_inq() to compute the number of readable bytes at the MPTCP level. It derives the count from mptcp_inq_hint(), returns 0 while the connection is still handshaking (TCP_SYN_SENT/TCP_SYN_RECV), and subtracts 1 once a FIN has been received, since the FIN consumes a sequence number but carries no data. This keeps the reported count in sync with the bytes actually queued, preventing upper layers from trying to read data that has not yet arrived. Wire mptcp_inq() into mptcp_peek_len() and assign .peek_len in both mptcp_stream_ops and mptcp_v6_stream_ops, so upper layers get the correct in-queue byte count for MPTCP connections. Signed-off-by: Geliang Tang --- net/mptcp/protocol.c | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index cc8747162cca..9b9ace7cb977 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -4814,6 +4814,37 @@ static ssize_t mptcp_splice_read(struct socket *sock= , loff_t *ppos, return ret; } =20 +static int mptcp_inq(struct sock *sk) +{ + const struct mptcp_sock *msk =3D mptcp_sk(sk); + int answ; + + if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) { + answ =3D 0; + } else if (test_bit(MPTCP_SYNC_SEQ, &msk->cb_flags)) { + answ =3D 0; + } else { + u64 hint_val; + + hint_val =3D atomic64_read(&msk->ack_seq) - msk->copied_seq; + if (hint_val >=3D INT_MAX) + hint_val =3D INT_MAX; + + answ =3D (unsigned int)hint_val; + if (answ && + (sk->sk_state =3D=3D TCP_CLOSE || + (sk->sk_shutdown & RCV_SHUTDOWN))) + answ--; + } + + return answ; +} + +static int mptcp_peek_len(struct socket *sock) +{ + return mptcp_inq(sock->sk); +} + static const struct proto_ops mptcp_stream_ops =3D { .family =3D PF_INET, .owner =3D THIS_MODULE, @@ -4836,6 +4867,7 @@ static const struct proto_ops mptcp_stream_ops =3D { .set_rcvlowat =3D mptcp_set_rcvlowat, .read_sock =3D mptcp_read_sock, .splice_read =3D mptcp_splice_read, + .peek_len =3D mptcp_peek_len, }; =20 static struct inet_protosw mptcp_protosw =3D { @@ -4960,6 +4992,7 @@ static const struct proto_ops mptcp_v6_stream_ops =3D= { .set_rcvlowat =3D mptcp_set_rcvlowat, .read_sock =3D mptcp_read_sock, .splice_read =3D mptcp_splice_read, + .peek_len =3D mptcp_peek_len, }; =20 static struct proto mptcp_v6_prot; --=20 2.53.0 From nobody Sat Sep 5 05:49:24 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DE86743CE45 for ; Thu, 27 Aug 2026 10:58:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787828284; cv=none; b=pTNHtuUVHmvCv/UVCfz79DqIh0WHYIXh4cukmEAr2S09YFyy0RXhJSyyV/XqriZWfVkFWl6FBWBIDWgx6ROee+SuTfQOmrtv+cEntQS5VshOsh2ZX6JUvZRC0+/iiLVtF3thhyGvtqYnqx8TRt3/xt/zdiv8RRM0Iue1mLOPopw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787828284; c=relaxed/simple; bh=ffVFTrUfsZlBu+7f57tIMw5vGEsy2p9qvpS+U7osgI8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=QNjVJ6NO9EWwJaaf9mojkooUsmhXnTKkXxelwtsr/PcN/shy193l63/P5mhMFhsn527cMgaKr42sscYGhETdFQAB4roYSLTOYTvDqG04vdfW8eBygT0GA/0hPfnvDOueK1Adtsto7L7sOzuX4qAotAuqJ6DGmQETRXrihapPTyI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=mtySw/3d; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="mtySw/3d" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CD3861F000E9; Thu, 27 Aug 2026 10:58:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787828281; bh=7e0Fxutby6gNuDFUFxt7zOiDw2DodIWhnSmrkueQN/0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=mtySw/3drcaZ9JC6yKkr8ZKzYVVXP7aOwXdyP2DBtYe3nZEgdyrXIHi7v82/wOh7/ nOfgPLcZQtE9hu48XvZh6wnKNKmXJinmoLOOYBQ1Hz1XksZHXvlEt/6YLU7BsKEOl3 BucJCpspURP6KvdKPTUHHFhXhWDs3WdfJdL4HKOYzwhyUZ5IIbeMQ6L24TsLU+mPWs V/p1yyt9N5yUBLRVRfbZNSdYN5OXGaRrClYamTAS+/N0F8xvlAtu8r0BR6aAUT1xnm XK1+F2Eus1rcLDGC1m8r+OdG0z43JpGPC4+jko1xQJmRHyj2Wqe13QWgOKe38WdFox 9UYpDu63SqDjQ== From: Geliang Tang To: mptcp@lists.linux.dev Cc: Geliang Tang Subject: [PATCH mptcp-next v9 08/11] mptcp: add sendmsg_locked to proto_ops Date: Thu, 27 Aug 2026 18:57:32 +0800 Message-ID: <53da6278a6f3eb694c0cb288045b79e23a659423.1787827525.git.tanggeliang@kylinos.cn> X-Mailer: git-send-email 2.53.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Geliang Tang MPTCP currently provides a standard sendmsg() implementation which acquires and releases the socket lock internally. However, certain upper layers need to call the sendmsg method while the socket lock is already held. Split the existing mptcp_sendmsg() into mptcp_sendmsg_locked() which assumes the caller holds the socket lock, and a tiny wrapper mptcp_sendmsg() that acquires the lock and calls the locked version. Expose .sendmsg_locked in both mptcp_stream_ops and mptcp_v6_stream_ops. Signed-off-by: Geliang Tang --- net/mptcp/protocol.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 9b9ace7cb977..98a1bfdfbdc4 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -2056,7 +2056,7 @@ static void mptcp_rps_record_subflows(const struct mp= tcp_sock *msk) } } =20 -static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) +static int mptcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_= t len) { struct mptcp_sock *msk =3D mptcp_sk(sk); struct page_frag *pfrag; @@ -2068,8 +2068,6 @@ static int mptcp_sendmsg(struct sock *sk, struct msgh= dr *msg, size_t len) msg->msg_flags &=3D MSG_MORE | MSG_DONTWAIT | MSG_NOSIGNAL | MSG_FASTOPEN | MSG_EOR; =20 - lock_sock(sk); - mptcp_rps_record_subflows(msk); =20 if (unlikely(inet_test_bit(DEFER_CONNECT, sk) || @@ -2185,7 +2183,6 @@ static int mptcp_sendmsg(struct sock *sk, struct msgh= dr *msg, size_t len) } =20 out: - release_sock(sk); return copied; =20 do_error: @@ -2196,6 +2193,17 @@ static int mptcp_sendmsg(struct sock *sk, struct msg= hdr *msg, size_t len) goto out; } =20 +static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) +{ + int ret; + + lock_sock(sk); + ret =3D mptcp_sendmsg_locked(sk, msg, len); + release_sock(sk); + + return ret; +} + static void mptcp_rcv_space_adjust(struct mptcp_sock *msk, int copied); =20 static void mptcp_eat_recv_skb(struct sock *sk, struct sk_buff *skb) @@ -4868,6 +4876,7 @@ static const struct proto_ops mptcp_stream_ops =3D { .read_sock =3D mptcp_read_sock, .splice_read =3D mptcp_splice_read, .peek_len =3D mptcp_peek_len, + .sendmsg_locked =3D mptcp_sendmsg_locked, }; =20 static struct inet_protosw mptcp_protosw =3D { @@ -4993,6 +5002,7 @@ static const struct proto_ops mptcp_v6_stream_ops =3D= { .read_sock =3D mptcp_read_sock, .splice_read =3D mptcp_splice_read, .peek_len =3D mptcp_peek_len, + .sendmsg_locked =3D mptcp_sendmsg_locked, }; =20 static struct proto mptcp_v6_prot; --=20 2.53.0 From nobody Sat Sep 5 05:49:24 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4229943BDD5 for ; Thu, 27 Aug 2026 10:58:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787828286; cv=none; b=IYo9ffHSazfBARHEa2YCQj87vc4rVJVIikBTugg97fN3SWTWrG1oSTaRNrTP21MPGwQQwGEYfXKM+Ibuafph8pt1w5uscrkJbsqX+G8N8zOie6U1ERdldAWVgmwHVSLHwASlpvUNfgrxCmXtM8kGuUduGkW9M+zg1hOiPbTokfE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787828286; c=relaxed/simple; bh=MVRqr5eduyTbgZGv4DSFYcxgu+x0eNZjRcvAgfGQw90=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=NFAyd9IUPu1iHMyPqfUryBS/wOyvSlLTem4Uhs932sDDf1cU+3qPoVymzqndnmDvCSPhtUiA4kPTIeJAhPnWTXPS0yZtAaFWZtWI61J6kTTee05rLzm7RevrBEjL0+kA7Vnm9KjjGTIE6K9kC1j5o96x73qB+q9AxZznZUOWzc4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=TNX2zOZ1; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="TNX2zOZ1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 38E371F00A3A; Thu, 27 Aug 2026 10:58:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787828283; bh=ioVkv3Eb2ZRoN7SZ+xBomX/eln2v1t7zTfZHwSwnWQo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=TNX2zOZ18UFZughCC2IMKdmIBvmKeqEbmcw4owRfHEcQrVgxLRIP7gWbjG4Pttk5e zLAZF5ro2Lq8GEHrdo37hBsvjfxBuWlt24LL24CFgeNamFzPHF6ogy/SZ6gYk0DjOX HycbCRywnaQ/CWdWhgMixFkRhL/BNZvUgqtZlVvAoXHFZErHGMDn45013BCeM4tiet RERXH7xSDIQYkqafAxA1ikG+FQ+70Cfet502xBZQkyCGGbkSflzqNV8DKT6lm4PQ22 iyjtrn9VQY1/IpN9q/OJCn6Bo5X3R/9nn1Zwr2Q1IQZYtTq+/lRtQXesHY1qi1aBO8 ZKVjjdRC1EOHQ== From: Geliang Tang To: mptcp@lists.linux.dev Cc: Geliang Tang Subject: [PATCH mptcp-next v9 09/11] mptcp: track app-limited state in mptcp_sendmsg Date: Thu, 27 Aug 2026 18:57:33 +0800 Message-ID: X-Mailer: git-send-email 2.53.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Geliang Tang The application-limited accounting in TCP is updated by tcp_rate_check_app_limited(), which currently takes a struct sock * and internally calls tcp_sk(). MPTCP needs to apply the same accounting to each subflow individually - every subflow is an independent TCP socket with its own tp->app_limited / delivered state - so wrapping the call as a struct sock * -> tcp_sk() helper is awkward at the call site. Split the existing function: keep the logic as tcp_sock_rate_check_app_limited(struct tcp_sock *tp), and turn tcp_rate_check_app_limited(struct sock *) into a thin wrapper so the exported API is unchanged for other TCP users. Then add mptcp_sock_rate_check_app_limited() that walks every subflow of the mptcp_sock and runs tcp_sock_rate_check_app_limited() under each subflow's socket lock. Invoke it from mptcp_sendmsg() right after the send-side setup, so the delivery-rate app_limited state stays in sync with what the application actually has to send across each subflow. With this in place, TCP_INFO.tcpi_delivery_rate_app_limited is reported correctly for MPTCP connections instead of being left at 0. Signed-off-by: Geliang Tang --- include/net/tcp.h | 1 + net/ipv4/tcp.c | 9 +++++++-- net/mptcp/protocol.c | 18 ++++++++++++++++++ 3 files changed, 26 insertions(+), 2 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index 670c20876f26..f5cbb5a8a288 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -849,6 +849,7 @@ static inline int tcp_bound_to_half_wnd(struct tcp_sock= *tp, int pktsize) =20 /* tcp.c */ void tcp_get_info(struct sock *, struct tcp_info *); +void tcp_sock_rate_check_app_limited(struct tcp_sock *tp); void tcp_rate_check_app_limited(struct sock *sk); =20 /* Read 'sendfile()'-style from a TCP socket */ diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 1452c40e22d4..f0f843fd1897 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -1096,9 +1096,9 @@ int tcp_sendmsg_fastopen(struct sock *sk, struct msgh= dr *msg, int *copied, } =20 /* If a gap is detected between sends, mark the socket application-limited= . */ -void tcp_rate_check_app_limited(struct sock *sk) +void tcp_sock_rate_check_app_limited(struct tcp_sock *tp) { - struct tcp_sock *tp =3D tcp_sk(sk); + struct sock *sk =3D (struct sock *)tp; =20 if (/* We have less than one packet to send. */ tp->write_seq - tp->snd_nxt < tp->mss_cache && @@ -1111,6 +1111,11 @@ void tcp_rate_check_app_limited(struct sock *sk) tp->app_limited =3D (tp->delivered + tcp_packets_in_flight(tp)) ? : 1; } + +void tcp_rate_check_app_limited(struct sock *sk) +{ + tcp_sock_rate_check_app_limited(tcp_sk(sk)); +} EXPORT_SYMBOL_GPL(tcp_rate_check_app_limited); =20 int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 98a1bfdfbdc4..07813765eeaa 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -2056,6 +2056,21 @@ static void mptcp_rps_record_subflows(const struct m= ptcp_sock *msk) } } =20 +static void mptcp_rate_check_app_limited(struct sock *sk) +{ + struct mptcp_sock *msk =3D mptcp_sk(sk); + struct mptcp_subflow_context *subflow; + + mptcp_for_each_subflow(msk, subflow) { + struct sock *ssk =3D mptcp_subflow_tcp_sock(subflow); + bool slow; + + slow =3D lock_sock_fast_nested(ssk); + tcp_sock_rate_check_app_limited(tcp_sk(ssk)); + unlock_sock_fast(ssk, slow); + } +} + static int mptcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_= t len) { struct mptcp_sock *msk =3D mptcp_sk(sk); @@ -2084,6 +2099,9 @@ static int mptcp_sendmsg_locked(struct sock *sk, stru= ct msghdr *msg, size_t len) =20 timeo =3D sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT); =20 + /* is sending application-limited? */ + mptcp_rate_check_app_limited(sk); + if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) { ret =3D sk_stream_wait_connect(sk, &timeo); if (ret) --=20 2.53.0 From nobody Sat Sep 5 05:49:24 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2E17444210C for ; Thu, 27 Aug 2026 10:58:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787828288; cv=none; b=QicSW2Z9c7wyp8CSgpNqeMRY+smDDq+ERIBkFqpdcOyBaiNgAJBqfLA5jGxz4VFI75BlUh2VWrAATk2YTqZJQ0dRshM865rrqQn9Ce8xwP4aKjO/++Z5fH+Efr2OWEFWmJb4T0f0ip9zNHD0UHlzyxIWlKRlcKpuSviqfN2amY8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787828288; c=relaxed/simple; bh=JxT3qeiSHuBS12KtGnTPLFRzVxKd0fvCXwqrRkI3nnM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=hwn67cN3IZMrPYx03QhtIeHNUiuSgDKn6RPKG2xDruSegDYWNzr9b8mlodNRYHyYXFSn/TWL2C0sUhCiK0X9RWK+IY1wLRnnpCSsYX113unQH50JNnDiaPl4aGfJmDXx3bzf6+6Oyo2RMy5+HqCFYdL4nAQ4B/SvDVmPTsnGQCg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fRYZ5EG0; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="fRYZ5EG0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 137121F00A3E; Thu, 27 Aug 2026 10:58:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787828284; bh=xNNDwMcimuhvgxiiYj/oGzahS6NB1VtBfCB7+LyvfjA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=fRYZ5EG0qIBY7qHaAGJ94pTrb8VBdrt1eXhpaOD2uY2WiJusMjFn8W6SpFjEA/t94 QgKyoBrLkuhnEASPIPnSO/PDQoUIJxX5yDExlqRA3mlv7gMyo7JMSIs5yXw8S3rHUG Qs8DsNkbYe9T7UxFByKOVdVmeikm58bkSQw9MkRuwYJBdK292c8AfXIGhTQPcmtaD3 eOIzgZsfynZ+8FceNvUoRcYnaBazYLXyj8ppCB9n+rNRr1D3Qn50oyDN6Dk2g3iRMm ybBHKBfYWU0Grg/AMcTPM9ohRI7guU0JHAPRUZcSs6Esf8gKNGGInKJfyJSlRPWObQ svw7Up+Fm3RCA== From: Geliang Tang To: mptcp@lists.linux.dev Cc: Geliang Tang Subject: [PATCH mptcp-next v9 10/11] selftests: mptcp: sockopt: check app_limited Date: Thu, 27 Aug 2026 18:57:34 +0800 Message-ID: X-Mailer: git-send-email 2.53.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Geliang Tang connect_one_server() in mptcp_sockopt exchanges only a few packets between the client and server, then closes the socket. After such a small transfer the application has nothing further to send, so the connection is, by definition, application-limited. Extend the TCP_INFO readback at the end of the function to assert s.tcp_info.tcpi_delivery_rate_app_limited =3D=3D 1. Without the preceding commit, mptcp_sendmsg() never updates the per-subflow app-limited state, and this field stays at 0 - the assertion would fail. With it in place, the value is forced to 1, turning this into a regression guard for the subflow-side application-limited accounting. Signed-off-by: Geliang Tang --- tools/testing/selftests/net/mptcp/mptcp_sockopt.c | 1 + 1 file changed, 1 insertion(+) diff --git a/tools/testing/selftests/net/mptcp/mptcp_sockopt.c b/tools/test= ing/selftests/net/mptcp/mptcp_sockopt.c index d68515b7903b..8d712bdb4325 100644 --- a/tools/testing/selftests/net/mptcp/mptcp_sockopt.c +++ b/tools/testing/selftests/net/mptcp/mptcp_sockopt.c @@ -640,6 +640,7 @@ static void connect_one_server(int fd, int pipefd) total +=3D 1; /* sequence advances due to FIN */ =20 assert(s.mptcpi_rcv_delta =3D=3D (uint64_t)total); + assert(s.tcp_info.tcpi_delivery_rate_app_limited =3D=3D 1); close(fd); } =20 --=20 2.53.0 From nobody Sat Sep 5 05:49:24 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A501843C05E for ; Thu, 27 Aug 2026 10:58:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787828290; cv=none; b=eP8vSm6Y+AXSG672vVh5BFloLqRcgykEawyUZJem1ygLsfDZa6wTqyyzP003xN3+casFH1QAD9P80832nlSdsMbpJ0okcXbu+XIFPIdIVdfyD94UjNmAfw9jK3KKMUaHZ5IEkLPaK3huegmRUXHptfj7IJme7l4zs4DWUPvaVGo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787828290; c=relaxed/simple; bh=sABakLxQbUEcKg2rxQjjNh927s0aRRIBwJGd27JHknY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=LT3XK0lcdwnkyz0lzcAkqCdEN6+AfrCEfsUozejJoC+DcV8xpqZfPdiDc3/81w78NFLBnCIuKDztGa4fvCkuLvU2DqiATFEFA//ELmxHEthTKDLRXXaOOedl+wxYQR14yGgLCwYIytPq+0GqXHgQG3n6bynJjAaR29v3Dc1lgfU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=NAuaJ9Dy; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="NAuaJ9Dy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 647151F00A3D; Thu, 27 Aug 2026 10:58:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787828286; bh=5+gN4VNEayXzHnVZOGpyoigB74UWLRtRyv1yFgYDVrI=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=NAuaJ9DyR3bwjiSbGHJ1uUoCcq6Rj0EpJfLnZZN3fTZzqhYakxaAoce+zr+eaROqf LWLEOkj9ONT9U1XnbjU2r5Z6bQSnYtcGZW/Ryeipeql7dmj3Y1EuZeOj0NkyXsTc6z FT2RQdb9Pxxcfbecr8COcTU33IkLvw9NqsXLrm6NsRsc5F337tQJPGcJPdA7aDUnCG DxeZDQ2YG5pq4TCyPptL7jr3Y+uTSbJdKqY+S60DzjBNXaWcJPAXDlX+Dttv2+B4fs gSMHRTS8qsjUKw/MRs96EvBjuDrJp83SVfNZcvmMrpeq6+Np2RyEkYBSXJy4E7ogSb k9WwxzbRvrpWg== From: Geliang Tang To: mptcp@lists.linux.dev Cc: Geliang Tang Subject: [PATCH mptcp-next v9 11/11] Squash to "selftests/bpf: Add bpf_burst scheduler & test" Date: Thu, 27 Aug 2026 18:57:35 +0800 Message-ID: <056ee1d2d313b38d6dfa20d44517ddeed34a63db.1787827525.git.tanggeliang@kylinos.cn> X-Mailer: git-send-email 2.53.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Geliang Tang msk->snd_nxt was converted to atomic64_t. Use READ_ONCE on the .counter field to read it safely in BPF context. Signed-off-by: Geliang Tang --- tools/testing/selftests/bpf/progs/mptcp_bpf_burst.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/bpf/progs/mptcp_bpf_burst.c b/tools/te= sting/selftests/bpf/progs/mptcp_bpf_burst.c index 3d512b0efe6f..a391f6563a61 100644 --- a/tools/testing/selftests/bpf/progs/mptcp_bpf_burst.c +++ b/tools/testing/selftests/bpf/progs/mptcp_bpf_burst.c @@ -108,7 +108,8 @@ int BPF_PROG(bpf_burst_get_send, struct mptcp_sock *msk) if (!subflow || !bpf_sk_stream_memory_free(subflow)) return -1; =20 - burst =3D min(MPTCP_SEND_BURST_SIZE, mptcp_wnd_end(msk) - msk->snd_nxt); + burst =3D min(MPTCP_SEND_BURST_SIZE, + mptcp_wnd_end(msk) - READ_ONCE(msk->snd_nxt.counter)); ssk =3D mptcp_subflow_tcp_sock(subflow); wmem =3D ssk->sk_wmem_queued; if (!burst) --=20 2.53.0