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key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id E4D171944A8C for ; Wed, 9 Jul 2025 15:13:05 +0000 (UTC) Received: from gerbillo.redhat.com (unknown [10.44.33.4]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 023F919560A0 for ; Wed, 9 Jul 2025 15:13:04 +0000 (UTC) From: Paolo Abeni To: mptcp@lists.linux.dev Subject: [PATCH v3 mptcp-net 1/5] mptcp: make fallback action and fallback decision atomic Date: Wed, 9 Jul 2025 17:12:50 +0200 Message-ID: <2cc6457002f97221dd59b49841efc2816dcc1617.1752073685.git.pabeni@redhat.com> In-Reply-To: References: Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: LR2ESUzMKXlXMVWeaP9ExG-uR1dLhu9uykaFBBLccEg_1752073986 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8"; x-default="true" Syzkaller reported the following splat: WARNING: CPU: 1 PID: 7704 at net/mptcp/protocol.h:1223 __mptcp_do_fallback = net/mptcp/protocol.h:1223 [inline] WARNING: CPU: 1 PID: 7704 at net/mptcp/protocol.h:1223 mptcp_do_fallback ne= t/mptcp/protocol.h:1244 [inline] WARNING: CPU: 1 PID: 7704 at net/mptcp/protocol.h:1223 check_fully_establis= hed net/mptcp/options.c:982 [inline] WARNING: CPU: 1 PID: 7704 at net/mptcp/protocol.h:1223 mptcp_incoming_optio= ns+0x21a8/0x2510 net/mptcp/options.c:1153 Modules linked in: CPU: 1 UID: 0 PID: 7704 Comm: syz.3.1419 Not tainted 6.16.0-rc3-gbd5ce2324d= ba #20 PREEMPT(voluntary) Hardware name: QEMU Ubuntu 24.04 PC (i440FX + PIIX, 1996), BIOS 1.16.3-debi= an-1.16.3-2 04/01/2014 RIP: 0010:__mptcp_do_fallback net/mptcp/protocol.h:1223 [inline] RIP: 0010:mptcp_do_fallback net/mptcp/protocol.h:1244 [inline] RIP: 0010:check_fully_established net/mptcp/options.c:982 [inline] RIP: 0010:mptcp_incoming_options+0x21a8/0x2510 net/mptcp/options.c:1153 Code: 24 18 e8 bb 2a 00 fd e9 1b df ff ff e8 b1 21 0f 00 e8 ec 5f c4 fc 44 = 0f b7 ac 24 b0 00 00 00 e9 54 f1 ff ff e8 d9 5f c4 fc 90 <0f> 0b 90 e9 b8 f= 4 ff ff e8 8b 2a 00 fd e9 8d e6 ff ff e8 81 2a 00 RSP: 0018:ffff8880a3f08448 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff8880180a8000 RCX: ffffffff84afcf45 RDX: ffff888090223700 RSI: ffffffff84afdaa7 RDI: 0000000000000001 RBP: ffff888017955780 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffff8880180a8910 R14: ffff8880a3e9d058 R15: 0000000000000000 FS: 00005555791b8500(0000) GS:ffff88811c495000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000110c2800b7 CR3: 0000000058e44000 CR4: 0000000000350ef0 Call Trace: tcp_reset+0x26f/0x2b0 net/ipv4/tcp_input.c:4432 tcp_validate_incoming+0x1057/0x1b60 net/ipv4/tcp_input.c:5975 tcp_rcv_established+0x5b5/0x21f0 net/ipv4/tcp_input.c:6166 tcp_v4_do_rcv+0x5dc/0xa70 net/ipv4/tcp_ipv4.c:1925 tcp_v4_rcv+0x3473/0x44a0 net/ipv4/tcp_ipv4.c:2363 ip_protocol_deliver_rcu+0xba/0x480 net/ipv4/ip_input.c:205 ip_local_deliver_finish+0x2f1/0x500 net/ipv4/ip_input.c:233 NF_HOOK include/linux/netfilter.h:317 [inline] NF_HOOK include/linux/netfilter.h:311 [inline] ip_local_deliver+0x1be/0x560 net/ipv4/ip_input.c:254 dst_input include/net/dst.h:469 [inline] ip_rcv_finish net/ipv4/ip_input.c:447 [inline] NF_HOOK include/linux/netfilter.h:317 [inline] NF_HOOK include/linux/netfilter.h:311 [inline] ip_rcv+0x514/0x810 net/ipv4/ip_input.c:567 __netif_receive_skb_one_core+0x197/0x1e0 net/core/dev.c:5975 __netif_receive_skb+0x1f/0x120 net/core/dev.c:6088 process_backlog+0x301/0x1360 net/core/dev.c:6440 __napi_poll.constprop.0+0xba/0x550 net/core/dev.c:7453 napi_poll net/core/dev.c:7517 [inline] net_rx_action+0xb44/0x1010 net/core/dev.c:7644 handle_softirqs+0x1d0/0x770 kernel/softirq.c:579 do_softirq+0x3f/0x90 kernel/softirq.c:480 __local_bh_enable_ip+0xed/0x110 kernel/softirq.c:407 local_bh_enable include/linux/bottom_half.h:33 [inline] inet_csk_listen_stop+0x2c5/0x1070 net/ipv4/inet_connection_sock.c:1524 mptcp_check_listen_stop.part.0+0x1cc/0x220 net/mptcp/protocol.c:2985 mptcp_check_listen_stop net/mptcp/mib.h:118 [inline] __mptcp_close+0x9b9/0xbd0 net/mptcp/protocol.c:3000 mptcp_close+0x2f/0x140 net/mptcp/protocol.c:3066 inet_release+0xed/0x200 net/ipv4/af_inet.c:435 inet6_release+0x4f/0x70 net/ipv6/af_inet6.c:487 __sock_release+0xb3/0x270 net/socket.c:649 sock_close+0x1c/0x30 net/socket.c:1439 __fput+0x402/0xb70 fs/file_table.c:465 task_work_run+0x150/0x240 kernel/task_work.c:227 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] exit_to_user_mode_loop+0xd4/0xe0 kernel/entry/common.c:114 exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline] do_syscall_64+0x245/0x360 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fc92f8a36ad Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 = 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff f= f 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffcf52802d8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4 RAX: 0000000000000000 RBX: 00007ffcf52803a8 RCX: 00007fc92f8a36ad RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003 RBP: 00007fc92fae7ba0 R08: 0000000000000001 R09: 0000002800000000 R10: 00007fc92f700000 R11: 0000000000000246 R12: 00007fc92fae5fac R13: 00007fc92fae5fa0 R14: 0000000000026d00 R15: 0000000000026c51 irq event stamp: 4068 hardirqs last enabled at (4076): [] __up_console_sem+0x7= 6/0x80 kernel/printk/printk.c:344 hardirqs last disabled at (4085): [] __up_console_sem+0x5= b/0x80 kernel/printk/printk.c:342 softirqs last enabled at (3096): [] local_bh_enable incl= ude/linux/bottom_half.h:33 [inline] softirqs last enabled at (3096): [] inet_csk_listen_stop= +0x2c0/0x1070 net/ipv4/inet_connection_sock.c:1524 softirqs last disabled at (3097): [] do_softirq+0x3f/0x90= kernel/softirq.c:480 Since we need to track the 'fallback is possible' condition and the fallback status separately, there are a few possible races open between the check and the actual fallback action. Add a spinlock to protect the fallback related information and use it close all the possible related races. While at it also remove the too-early clearing of allow_infinite_fallback in __mptcp_subflow_connect(): the field will be correctly cleared by subflow_finish_connect() if/ when the connection will complete successfully. If fallback is not possible, as per RFC, reset the current subflow. Since the fallback operation can now fail and return value should be checked, rename the helper accordingly. Reported by: Matthieu Baerts Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/570 Reported-by: syzbot+5cf807c20386d699b524@syzkaller.appspotmail.com Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/555 Fixes: 0530020a7c8f ("mptcp: track and update contiguous data status") Signed-off-by: Paolo Abeni --- v2 -> v3: - fix return vale check in check_fully_established() - add WARN when hitting 'impossible' fallback failures. - drop empty line - mptcp_do_fallback -> mptcp_try_fallback v1 -> v2: - remove unneeded and racing allow_infinite_fallback in __mptcp_subflow_connect() - really close race in subflow_check_data_avail() Sharing earlier to feed syzkaller. Hopefully a follow-up on mptcp-net-next will cleanup a bit the fallback handling, I tried to minimize the delta for backport's sake --- net/mptcp/options.c | 3 ++- net/mptcp/protocol.c | 40 +++++++++++++++++++++++++++++++++++----- net/mptcp/protocol.h | 23 ++++++++++++++++------- net/mptcp/subflow.c | 11 +++++------ 4 files changed, 58 insertions(+), 19 deletions(-) diff --git a/net/mptcp/options.c b/net/mptcp/options.c index 56fd7bcb786c..9288a8d1235e 100644 --- a/net/mptcp/options.c +++ b/net/mptcp/options.c @@ -978,8 +978,9 @@ static bool check_fully_established(struct mptcp_sock *= msk, struct sock *ssk, if (subflow->mp_join) goto reset; subflow->mp_capable =3D 0; + if (!mptcp_try_fallback(ssk)) + goto reset; pr_fallback(msk); - mptcp_do_fallback(ssk); return false; } =20 diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 1de42dc4e8ea..4ddf3a1e0085 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -560,10 +560,9 @@ static bool mptcp_check_data_fin(struct sock *sk) =20 static void mptcp_dss_corruption(struct mptcp_sock *msk, struct sock *ssk) { - if (READ_ONCE(msk->allow_infinite_fallback)) { + if (mptcp_try_fallback(ssk)) { MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSCORRUPTIONFALLBACK); - mptcp_do_fallback(ssk); } else { MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSCORRUPTIONRESET); mptcp_subflow_reset(ssk); @@ -803,6 +802,14 @@ static bool __mptcp_finish_join(struct mptcp_sock *msk= , struct sock *ssk) if (sk->sk_state !=3D TCP_ESTABLISHED) return false; =20 + spin_lock_bh(&msk->fallback_lock); + if (__mptcp_check_fallback(msk)) { + spin_unlock_bh(&msk->fallback_lock); + return false; + } + mptcp_subflow_joined(msk, ssk); + spin_unlock_bh(&msk->fallback_lock); + /* attach to msk socket only after we are sure we will deal with it * at close time */ @@ -811,7 +818,6 @@ static bool __mptcp_finish_join(struct mptcp_sock *msk,= struct sock *ssk) =20 mptcp_subflow_ctx(ssk)->subflow_id =3D msk->subflow_id++; mptcp_sockopt_sync_locked(msk, ssk); - mptcp_subflow_joined(msk, ssk); mptcp_stop_tout_timer(sk); __mptcp_propagate_sndbuf(sk, ssk); return true; @@ -1136,10 +1142,14 @@ static void mptcp_update_infinite_map(struct mptcp_= sock *msk, mpext->infinite_map =3D 1; mpext->data_len =3D 0; =20 + if (!mptcp_try_fallback(ssk)) { + mptcp_subflow_reset(ssk); + return; + } + MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_INFINITEMAPTX); mptcp_subflow_ctx(ssk)->send_infinite_map =3D 0; pr_fallback(msk); - mptcp_do_fallback(ssk); } =20 #define MPTCP_MAX_GSO_SIZE (GSO_LEGACY_MAX_SIZE - (MAX_TCP_HEADER + 1)) @@ -2543,9 +2553,9 @@ static void mptcp_check_fastclose(struct mptcp_sock *= msk) =20 static void __mptcp_retrans(struct sock *sk) { + struct mptcp_sendmsg_info info =3D { .data_lock_held =3D true, }; struct mptcp_sock *msk =3D mptcp_sk(sk); struct mptcp_subflow_context *subflow; - struct mptcp_sendmsg_info info =3D {}; struct mptcp_data_frag *dfrag; struct sock *ssk; int ret, err; @@ -2590,6 +2600,18 @@ static void __mptcp_retrans(struct sock *sk) info.sent =3D 0; info.limit =3D READ_ONCE(msk->csum_enabled) ? dfrag->data_len : dfrag->already_sent; + + /* + * make the whole retrans decision, xmit, disallow + * fallback atomic + */ + spin_lock_bh(&msk->fallback_lock); + if (__mptcp_check_fallback(msk)) { + spin_unlock_bh(&msk->fallback_lock); + release_sock(ssk); + return; + } + while (info.sent < info.limit) { ret =3D mptcp_sendmsg_frag(sk, ssk, dfrag, &info); if (ret <=3D 0) @@ -2605,6 +2627,7 @@ static void __mptcp_retrans(struct sock *sk) info.size_goal); WRITE_ONCE(msk->allow_infinite_fallback, false); } + spin_unlock_bh(&msk->fallback_lock); =20 release_sock(ssk); } @@ -2738,6 +2761,7 @@ static void __mptcp_init_sock(struct sock *sk) msk->last_ack_recv =3D tcp_jiffies32; =20 mptcp_pm_data_init(msk); + spin_lock_init(&msk->fallback_lock); =20 /* re-use the csk retrans timer for MPTCP-level retrans */ timer_setup(&msk->sk.icsk_retransmit_timer, mptcp_retransmit_timer, 0); @@ -3524,7 +3548,13 @@ bool mptcp_finish_join(struct sock *ssk) =20 /* active subflow, already present inside the conn_list */ if (!list_empty(&subflow->node)) { + spin_lock_bh(&msk->fallback_lock); + if (__mptcp_check_fallback(msk)) { + spin_unlock_bh(&msk->fallback_lock); + return false; + } mptcp_subflow_joined(msk, ssk); + spin_unlock_bh(&msk->fallback_lock); mptcp_propagate_sndbuf(parent, ssk); return true; } diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index e36ae88b10ad..61a9ff467501 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -352,6 +352,7 @@ struct mptcp_sock { u32 subflow_id; u32 setsockopt_seq; char ca_name[TCP_CA_NAME_MAX]; + spinlock_t fallback_lock; /* protects fallback && allow_infinite_fallback= */ }; =20 #define mptcp_data_lock(sk) spin_lock_bh(&(sk)->sk_lock.slock) @@ -1214,15 +1215,21 @@ static inline bool mptcp_check_fallback(const struc= t sock *sk) return __mptcp_check_fallback(msk); } =20 -static inline void __mptcp_do_fallback(struct mptcp_sock *msk) +static inline bool __mptcp_try_fallback(struct mptcp_sock *msk) { if (__mptcp_check_fallback(msk)) { pr_debug("TCP fallback already done (msk=3D%p)\n", msk); - return; + return true; } - if (WARN_ON_ONCE(!READ_ONCE(msk->allow_infinite_fallback))) - return; + spin_lock_bh(&msk->fallback_lock); + if (!msk->allow_infinite_fallback) { + spin_unlock_bh(&msk->fallback_lock); + return false; + } + set_bit(MPTCP_FALLBACK_DONE, &msk->flags); + spin_unlock_bh(&msk->fallback_lock); + return true; } =20 static inline bool __mptcp_has_initial_subflow(const struct mptcp_sock *ms= k) @@ -1234,14 +1241,15 @@ static inline bool __mptcp_has_initial_subflow(cons= t struct mptcp_sock *msk) TCPF_SYN_RECV | TCPF_LISTEN)); } =20 -static inline void mptcp_do_fallback(struct sock *ssk) +static inline bool mptcp_try_fallback(struct sock *ssk) { struct mptcp_subflow_context *subflow =3D mptcp_subflow_ctx(ssk); struct sock *sk =3D subflow->conn; struct mptcp_sock *msk; =20 msk =3D mptcp_sk(sk); - __mptcp_do_fallback(msk); + if (!__mptcp_try_fallback(msk)) + return false; if (READ_ONCE(msk->snd_data_fin_enable) && !(ssk->sk_shutdown & SEND_SHUT= DOWN)) { gfp_t saved_allocation =3D ssk->sk_allocation; =20 @@ -1253,6 +1261,7 @@ static inline void mptcp_do_fallback(struct sock *ssk) tcp_shutdown(ssk, SEND_SHUTDOWN); ssk->sk_allocation =3D saved_allocation; } + return true; } =20 #define pr_fallback(a) pr_debug("%s:fallback to TCP (msk=3D%p)\n", __func_= _, a) @@ -1262,7 +1271,7 @@ static inline void mptcp_subflow_early_fallback(struc= t mptcp_sock *msk, { pr_fallback(msk); subflow->request_mptcp =3D 0; - __mptcp_do_fallback(msk); + WARN_ON_ONCE(!__mptcp_try_fallback(msk)); } =20 static inline bool mptcp_check_infinite_map(struct sk_buff *skb) diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index 15613d691bfe..a6a35985e551 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -544,9 +544,11 @@ static void subflow_finish_connect(struct sock *sk, co= nst struct sk_buff *skb) mptcp_get_options(skb, &mp_opt); if (subflow->request_mptcp) { if (!(mp_opt.suboptions & OPTION_MPTCP_MPC_SYNACK)) { + if (!mptcp_try_fallback(sk)) + goto do_reset; + MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPCAPABLEACTIVEFALLBACK); - mptcp_do_fallback(sk); pr_fallback(msk); goto fallback; } @@ -1395,7 +1397,7 @@ static bool subflow_check_data_avail(struct sock *ssk) return true; } =20 - if (!READ_ONCE(msk->allow_infinite_fallback)) { + if (!mptcp_try_fallback(ssk)) { /* fatal protocol error, close the socket. * subflow_error_report() will introduce the appropriate barriers */ @@ -1413,8 +1415,6 @@ static bool subflow_check_data_avail(struct sock *ssk) WRITE_ONCE(subflow->data_avail, false); return false; } - - mptcp_do_fallback(ssk); } =20 skb =3D skb_peek(&ssk->sk_receive_queue); @@ -1679,7 +1679,6 @@ int __mptcp_subflow_connect(struct sock *sk, const st= ruct mptcp_pm_local *local, /* discard the subflow socket */ mptcp_sock_graft(ssk, sk->sk_socket); iput(SOCK_INODE(sf)); - WRITE_ONCE(msk->allow_infinite_fallback, false); mptcp_stop_tout_timer(sk); return 0; =20 @@ -1851,7 +1850,7 @@ static void subflow_state_change(struct sock *sk) =20 msk =3D mptcp_sk(parent); if (subflow_simultaneous_connect(sk)) { - mptcp_do_fallback(sk); + WARN_ON_ONCE(!mptcp_try_fallback(sk)); pr_fallback(msk); subflow->conn_finished =3D 1; mptcp_propagate_state(parent, sk, subflow, NULL); --=20 2.50.0 From nobody Wed Sep 17 18:02:52 2025 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 93F412E8E03 for ; 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charset="utf-8"; x-default="true" We have races similar to the one addressed by the previous patch between subflow failing and additional subflow creation. They are just harder to trigger. The solution is similar. Use a separate flag to track the condition 'socket state prevent any additional subflow creation' protected by the fallback lock. The socket fallback makes such flag true, and also receiving or sending a MPTCP fail option. The field 'allow_infinite_fallback' is now always touched under the relevant lock, we can drop the ONCE annotation on write. Fixes: 478d770008b0 ("mptcp: send out MP_FAIL when data checksum fails") Signed-off-by: Paolo Abeni --- net/mptcp/pm.c | 8 +++++++- net/mptcp/protocol.c | 11 ++++++----- net/mptcp/protocol.h | 8 +++++++- net/mptcp/subflow.c | 19 ++++++++++++++----- 4 files changed, 34 insertions(+), 12 deletions(-) diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c index 25ce2d5135bc..687dbb59d084 100644 --- a/net/mptcp/pm.c +++ b/net/mptcp/pm.c @@ -765,8 +765,14 @@ void mptcp_pm_mp_fail_received(struct sock *sk, u64 fa= il_seq) =20 pr_debug("fail_seq=3D%llu\n", fail_seq); =20 - if (!READ_ONCE(msk->allow_infinite_fallback)) + /* After accepting the fail, we can't create any other subflows */ + spin_lock_bh(&msk->fallback_lock); + if (!msk->allow_infinite_fallback) { + spin_unlock_bh(&msk->fallback_lock); return; + } + msk->allow_subflows =3D false; + spin_unlock_bh(&msk->fallback_lock); =20 if (!subflow->fail_tout) { pr_debug("send MP_FAIL response and infinite map\n"); diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 4ddf3a1e0085..49498cdd17f0 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -791,7 +791,7 @@ void mptcp_data_ready(struct sock *sk, struct sock *ssk) static void mptcp_subflow_joined(struct mptcp_sock *msk, struct sock *ssk) { mptcp_subflow_ctx(ssk)->map_seq =3D READ_ONCE(msk->ack_seq); - WRITE_ONCE(msk->allow_infinite_fallback, false); + msk->allow_infinite_fallback =3D false; mptcp_event(MPTCP_EVENT_SUB_ESTABLISHED, msk, ssk, GFP_ATOMIC); } =20 @@ -803,7 +803,7 @@ static bool __mptcp_finish_join(struct mptcp_sock *msk,= struct sock *ssk) return false; =20 spin_lock_bh(&msk->fallback_lock); - if (__mptcp_check_fallback(msk)) { + if (!msk->allow_subflows) { spin_unlock_bh(&msk->fallback_lock); return false; } @@ -2625,7 +2625,7 @@ static void __mptcp_retrans(struct sock *sk) len =3D max(copied, len); tcp_push(ssk, 0, info.mss_now, tcp_sk(ssk)->nonagle, info.size_goal); - WRITE_ONCE(msk->allow_infinite_fallback, false); + msk->allow_infinite_fallback =3D false; } spin_unlock_bh(&msk->fallback_lock); =20 @@ -2753,7 +2753,8 @@ static void __mptcp_init_sock(struct sock *sk) WRITE_ONCE(msk->first, NULL); inet_csk(sk)->icsk_sync_mss =3D mptcp_sync_mss; WRITE_ONCE(msk->csum_enabled, mptcp_is_checksum_enabled(sock_net(sk))); - WRITE_ONCE(msk->allow_infinite_fallback, true); + msk->allow_infinite_fallback =3D true; + msk->allow_subflows =3D true; msk->recovery =3D false; msk->subflow_id =3D 1; msk->last_data_sent =3D tcp_jiffies32; @@ -3549,7 +3550,7 @@ bool mptcp_finish_join(struct sock *ssk) /* active subflow, already present inside the conn_list */ if (!list_empty(&subflow->node)) { spin_lock_bh(&msk->fallback_lock); - if (__mptcp_check_fallback(msk)) { + if (!msk->allow_subflows) { spin_unlock_bh(&msk->fallback_lock); return false; } diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index 61a9ff467501..c8b4ebe198dc 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -348,11 +348,16 @@ struct mptcp_sock { u64 rtt_us; /* last maximum rtt of subflows */ } rcvq_space; u8 scaling_ratio; + bool allow_subflows; =20 u32 subflow_id; u32 setsockopt_seq; char ca_name[TCP_CA_NAME_MAX]; - spinlock_t fallback_lock; /* protects fallback && allow_infinite_fallback= */ + + spinlock_t fallback_lock; /* protects fallback, + * allow_infinite_fallback and + * allow_join + */ }; =20 #define mptcp_data_lock(sk) spin_lock_bh(&(sk)->sk_lock.slock) @@ -1227,6 +1232,7 @@ static inline bool __mptcp_try_fallback(struct mptcp_= sock *msk) return false; } =20 + msk->allow_subflows =3D false; set_bit(MPTCP_FALLBACK_DONE, &msk->flags); spin_unlock_bh(&msk->fallback_lock); return true; diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index a6a35985e551..1802bc5435a1 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -1302,20 +1302,29 @@ static void subflow_sched_work_if_closed(struct mpt= cp_sock *msk, struct sock *ss mptcp_schedule_work(sk); } =20 -static void mptcp_subflow_fail(struct mptcp_sock *msk, struct sock *ssk) +static bool mptcp_subflow_fail(struct mptcp_sock *msk, struct sock *ssk) { struct mptcp_subflow_context *subflow =3D mptcp_subflow_ctx(ssk); unsigned long fail_tout; =20 + /* we are really failing, prevent any later subflow join */ + spin_lock_bh(&msk->fallback_lock); + if (!msk->allow_infinite_fallback) { + spin_unlock_bh(&msk->fallback_lock); + return false; + } + msk->allow_subflows =3D false; + spin_unlock_bh(&msk->fallback_lock); + /* graceful failure can happen only on the MPC subflow */ if (WARN_ON_ONCE(ssk !=3D READ_ONCE(msk->first))) - return; + return false; =20 /* since the close timeout take precedence on the fail one, * no need to start the latter when the first is already set */ if (sock_flag((struct sock *)msk, SOCK_DEAD)) - return; + return true; =20 /* we don't need extreme accuracy here, use a zero fail_tout as special * value meaning no fail timeout at all; @@ -1327,6 +1336,7 @@ static void mptcp_subflow_fail(struct mptcp_sock *msk= , struct sock *ssk) tcp_send_ack(ssk); =20 mptcp_reset_tout_timer(msk, subflow->fail_tout); + return true; } =20 static bool subflow_check_data_avail(struct sock *ssk) @@ -1387,12 +1397,11 @@ static bool subflow_check_data_avail(struct sock *s= sk) (subflow->mp_join || subflow->valid_csum_seen)) { subflow->send_mp_fail =3D 1; =20 - if (!READ_ONCE(msk->allow_infinite_fallback)) { + if (!mptcp_subflow_fail(msk, ssk)) { subflow->reset_transient =3D 0; subflow->reset_reason =3D MPTCP_RST_EMIDDLEBOX; goto reset; } - mptcp_subflow_fail(msk, ssk); WRITE_ONCE(subflow->data_avail, true); return true; 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charset="utf-8"; x-default="true" mptcp_disconnect() clears the fallback bit unconditionally, without touching the associated flags. The bit clear is safe, as no fallback operation can race with that - all subflow are already in TCP_CLOSE status thanks to the previous FASTCLOSE - but we need to consistently reset all the fallback related status. Also acquire the relevant lock, to avoid fouling static analyzers. Fixes: b29fcfb54cd7 ("mptcp: full disconnect implementation") Signed-off-by: Paolo Abeni --- v2 -> v3: - drop entirely the blocking section --- net/mptcp/protocol.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 49498cdd17f0..46bc5cc5a4d7 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -3142,7 +3142,16 @@ static int mptcp_disconnect(struct sock *sk, int fla= gs) * subflow */ mptcp_destroy_common(msk, MPTCP_CF_FASTCLOSE); + + /* The first subflow is already in TCP_CLOSE status, the following + * can't overlap with a fallback anymore + */ + spin_lock_bh(&msk->fallback_lock); + msk->allow_subflows =3D true; + msk->allow_infinite_fallback =3D true; WRITE_ONCE(msk->flags, 0); + spin_unlock_bh(&msk->fallback_lock); + msk->cb_flags =3D 0; msk->recovery =3D false; WRITE_ONCE(msk->can_ack, false); --=20 2.50.0 From nobody Wed Sep 17 18:02:52 2025 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 7B1D62E8E10 for ; Wed, 9 Jul 2025 15:13:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752073996; cv=none; b=PWA/gG0Yf4rNz65QK7brxYBctjygCG4yo+XFEba2Vif4vUxy2O30uLzQz/zfgX+wqjtk/KYtmIzQNPkvhLc4cFyTwqc3Pug8h2uh4+Rqrx08SwK5QyJkRh+hUQ+mF7KMUk40uX5DY9dATrGOKOQigKX+o21pe+4GjzEbspJ2KYg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752073996; c=relaxed/simple; bh=T69siRU5yowhaQHa5g386a5/S+7N641b/FTeoMA1kvM=; h=From:To:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:content-type; b=cqkXgUG8biXr9GuQqqdNH7s5+5cZQ1jJ77VxGumAM2vJ1+xnNp8W6JNGjLgFaecFRLSbcmCd4swHn0SeYpwml/lM3/evVDp3SClu7QFJHRRLT/iTDFWglLQYN3/gYYSuAKKoYUX3ARS+VkufI6xbCrE4xC8nRL2+cIetrRnlupE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=bFjCFHeR; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="bFjCFHeR" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1752073992; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Z275rNrhcqxfnDUmKNcVurp0j8kT+hi/ihUbjCI4Dew=; b=bFjCFHeR/SvAalDqhuQEbkoCkfJE2nrOb1oSToc8UP851eyZ2crIkBlzEIunbQxz8LXU7I k0oLQbPuHnoWZOFy83FvxytTqsr1JGhsNANwwWZmocUTXQs8hRmLqsapbp7cdN5QKTB+aP GD9k4q8E1c31cN1hdnB8zyUe8/170Z4= Received: from mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-435-qi7gDj48Nk2WFzYVdYU27A-1; Wed, 09 Jul 2025 11:13:11 -0400 X-MC-Unique: qi7gDj48Nk2WFzYVdYU27A-1 X-Mimecast-MFC-AGG-ID: qi7gDj48Nk2WFzYVdYU27A_1752073990 Received: from mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.15]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 1909719541A0 for ; Wed, 9 Jul 2025 15:13:10 +0000 (UTC) Received: from gerbillo.redhat.com (unknown [10.44.33.4]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 39B9E1956089 for ; Wed, 9 Jul 2025 15:13:08 +0000 (UTC) From: Paolo Abeni To: mptcp@lists.linux.dev Subject: [PATCH v3 mptcp-net 4/5] mptcp: track fallbacks accurately via mibs Date: Wed, 9 Jul 2025 17:12:53 +0200 Message-ID: In-Reply-To: References: Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: hknrpLH39y9rFxNokQfwdcVcPhnwNNrJq3a_k9KYxv4_1752073990 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8"; x-default="true" Add the mibs required to cover the few possible fallback causes still lacking suck info. Move the relevant mib increment into the fallback helper, so that no eventual future fallback operation will miss a paired mib increment. Additionally track failed fallback via its own mib, such mib is incremented only when a fallback mandated by the protocol fails - due to racing subflow creation. While at the above, rename an existing helper to reduce long lines problems all along. Signed-off-by: Paolo Abeni --- v2 -> v3: - a bunch of mibs rename --- net/mptcp/ctrl.c | 4 ++-- net/mptcp/mib.c | 5 +++++ net/mptcp/mib.h | 7 +++++++ net/mptcp/options.c | 4 +++- net/mptcp/protocol.c | 44 ++++++++++++++++++++++++++++++-------------- net/mptcp/protocol.h | 31 ++++++++----------------------- net/mptcp/subflow.c | 12 +++++++----- 7 files changed, 62 insertions(+), 45 deletions(-) diff --git a/net/mptcp/ctrl.c b/net/mptcp/ctrl.c index d9290c5bb6c7..fed40dae5583 100644 --- a/net/mptcp/ctrl.c +++ b/net/mptcp/ctrl.c @@ -533,9 +533,9 @@ void mptcp_active_detect_blackhole(struct sock *ssk, bo= ol expired) to_max =3D mptcp_get_pernet(net)->syn_retrans_before_tcp_fallback; =20 if (timeouts =3D=3D to_max || (timeouts < to_max && expired)) { - MPTCP_INC_STATS(net, MPTCP_MIB_MPCAPABLEACTIVEDROP); subflow->mpc_drop =3D 1; - mptcp_subflow_early_fallback(mptcp_sk(subflow->conn), subflow); + mptcp_early_fallback(mptcp_sk(subflow->conn), subflow, + MPTCP_MIB_MPCAPABLEACTIVEDROP); } } =20 diff --git a/net/mptcp/mib.c b/net/mptcp/mib.c index 0c24545f0e8d..ee51d14ba510 100644 --- a/net/mptcp/mib.c +++ b/net/mptcp/mib.c @@ -80,6 +80,11 @@ static const struct snmp_mib mptcp_snmp_list[] =3D { SNMP_MIB_ITEM("RcvWndConflict", MPTCP_MIB_RCVWNDCONFLICT), SNMP_MIB_ITEM("MPCurrEstab", MPTCP_MIB_CURRESTAB), SNMP_MIB_ITEM("Blackhole", MPTCP_MIB_BLACKHOLE), + SNMP_MIB_ITEM("DataFallback", MPTCP_MIB_MPCAPABLEDATAFALLBACK), + SNMP_MIB_ITEM("MD5sumFallback", MPTCP_MIB_MD5SIGFALLBACK), + SNMP_MIB_ITEM("DssFallback", MPTCP_MIB_DSSFALLBACK), + SNMP_MIB_ITEM("SimultFallback", MPTCP_MIB_SIMULTCONNFALLBACK), + SNMP_MIB_ITEM("FallbackFailed", MPTCP_MIB_FALLBACKFAILED), SNMP_MIB_SENTINEL }; =20 diff --git a/net/mptcp/mib.h b/net/mptcp/mib.h index 250c6b77977e..309bac6fea32 100644 --- a/net/mptcp/mib.h +++ b/net/mptcp/mib.h @@ -81,6 +81,13 @@ enum linux_mptcp_mib_field { MPTCP_MIB_RCVWNDCONFLICT, /* Conflict with while updating msk rcv wnd */ MPTCP_MIB_CURRESTAB, /* Current established MPTCP connections */ MPTCP_MIB_BLACKHOLE, /* A blackhole has been detected */ + MPTCP_MIB_MPCAPABLEDATAFALLBACK, /* Missing DSS/MPC+data on first + * established packet + */ + MPTCP_MIB_MD5SIGFALLBACK, /* Conflicting TCP option enabled */ + MPTCP_MIB_DSSFALLBACK, /* Bad or missing DSS */ + MPTCP_MIB_SIMULTCONNFALLBACK, /* Simultaneous connect */ + MPTCP_MIB_FALLBACKFAILED, /* Can't fallback due to msk status */ __MPTCP_MIB_MAX }; =20 diff --git a/net/mptcp/options.c b/net/mptcp/options.c index 9288a8d1235e..b49a8b3ffe00 100644 --- a/net/mptcp/options.c +++ b/net/mptcp/options.c @@ -978,8 +978,10 @@ static bool check_fully_established(struct mptcp_sock = *msk, struct sock *ssk, if (subflow->mp_join) goto reset; subflow->mp_capable =3D 0; - if (!mptcp_try_fallback(ssk)) + if (!mptcp_try_fallback(ssk, MPTCP_MIB_MPCAPABLEDATAFALLBACK)) { + MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_FALLBACKFAILED); goto reset; + } pr_fallback(msk); return false; } diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 46bc5cc5a4d7..54dc39fd1495 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -67,6 +67,26 @@ static const struct proto_ops *mptcp_fallback_tcp_ops(co= nst struct sock *sk) return &inet_stream_ops; } =20 +bool __mptcp_try_fallback(struct mptcp_sock *msk, int fb_mib) +{ + struct net *net =3D sock_net((struct sock *)msk); + + if (__mptcp_check_fallback(msk)) + return true; + + spin_lock_bh(&msk->fallback_lock); + if (!msk->allow_infinite_fallback) { + spin_unlock_bh(&msk->fallback_lock); + return false; + } + + msk->allow_subflows =3D false; + set_bit(MPTCP_FALLBACK_DONE, &msk->flags); + __MPTCP_INC_STATS(net, fb_mib); + spin_unlock_bh(&msk->fallback_lock); + return true; +} + static int __mptcp_socket_create(struct mptcp_sock *msk) { struct mptcp_subflow_context *subflow; @@ -560,10 +580,7 @@ static bool mptcp_check_data_fin(struct sock *sk) =20 static void mptcp_dss_corruption(struct mptcp_sock *msk, struct sock *ssk) { - if (mptcp_try_fallback(ssk)) { - MPTCP_INC_STATS(sock_net(ssk), - MPTCP_MIB_DSSCORRUPTIONFALLBACK); - } else { + if (!mptcp_try_fallback(ssk, MPTCP_MIB_DSSCORRUPTIONFALLBACK)) { MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSCORRUPTIONRESET); mptcp_subflow_reset(ssk); } @@ -1142,12 +1159,12 @@ static void mptcp_update_infinite_map(struct mptcp_= sock *msk, mpext->infinite_map =3D 1; mpext->data_len =3D 0; =20 - if (!mptcp_try_fallback(ssk)) { + if (!mptcp_try_fallback(ssk, MPTCP_MIB_INFINITEMAPTX)) { + MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_FALLBACKFAILED); mptcp_subflow_reset(ssk); return; } =20 - MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_INFINITEMAPTX); mptcp_subflow_ctx(ssk)->send_infinite_map =3D 0; pr_fallback(msk); } @@ -3688,16 +3705,15 @@ static int mptcp_connect(struct sock *sk, struct so= ckaddr *uaddr, int addr_len) * TCP option space. */ if (rcu_access_pointer(tcp_sk(ssk)->md5sig_info)) - mptcp_subflow_early_fallback(msk, subflow); + mptcp_early_fallback(msk, subflow, MPTCP_MIB_MD5SIGFALLBACK); #endif if (subflow->request_mptcp) { - if (mptcp_active_should_disable(sk)) { - MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_MPCAPABLEACTIVEDISABLED); - mptcp_subflow_early_fallback(msk, subflow); - } else if (mptcp_token_new_connect(ssk) < 0) { - MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_TOKENFALLBACKINIT); - mptcp_subflow_early_fallback(msk, subflow); - } + if (mptcp_active_should_disable(sk)) + mptcp_early_fallback(msk, subflow, + MPTCP_MIB_MPCAPABLEACTIVEDISABLED); + else if (mptcp_token_new_connect(ssk) < 0) + mptcp_early_fallback(msk, subflow, + MPTCP_MIB_TOKENFALLBACKINIT); } =20 WRITE_ONCE(msk->write_seq, subflow->idsn); diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index c8b4ebe198dc..74579743264f 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -1220,24 +1220,6 @@ static inline bool mptcp_check_fallback(const struct= sock *sk) return __mptcp_check_fallback(msk); } =20 -static inline bool __mptcp_try_fallback(struct mptcp_sock *msk) -{ - if (__mptcp_check_fallback(msk)) { - pr_debug("TCP fallback already done (msk=3D%p)\n", msk); - return true; - } - spin_lock_bh(&msk->fallback_lock); - if (!msk->allow_infinite_fallback) { - spin_unlock_bh(&msk->fallback_lock); - return false; - } - - msk->allow_subflows =3D false; - set_bit(MPTCP_FALLBACK_DONE, &msk->flags); - spin_unlock_bh(&msk->fallback_lock); - return true; -} - static inline bool __mptcp_has_initial_subflow(const struct mptcp_sock *ms= k) { struct sock *ssk =3D READ_ONCE(msk->first); @@ -1247,14 +1229,16 @@ static inline bool __mptcp_has_initial_subflow(cons= t struct mptcp_sock *msk) TCPF_SYN_RECV | TCPF_LISTEN)); } =20 -static inline bool mptcp_try_fallback(struct sock *ssk) +bool __mptcp_try_fallback(struct mptcp_sock *msk, int fb_mib); + +static inline bool mptcp_try_fallback(struct sock *ssk, int fb_mib) { struct mptcp_subflow_context *subflow =3D mptcp_subflow_ctx(ssk); struct sock *sk =3D subflow->conn; struct mptcp_sock *msk; =20 msk =3D mptcp_sk(sk); - if (!__mptcp_try_fallback(msk)) + if (!__mptcp_try_fallback(msk, fb_mib)) return false; if (READ_ONCE(msk->snd_data_fin_enable) && !(ssk->sk_shutdown & SEND_SHUT= DOWN)) { gfp_t saved_allocation =3D ssk->sk_allocation; @@ -1272,12 +1256,13 @@ static inline bool mptcp_try_fallback(struct sock *= ssk) =20 #define pr_fallback(a) pr_debug("%s:fallback to TCP (msk=3D%p)\n", __func_= _, a) =20 -static inline void mptcp_subflow_early_fallback(struct mptcp_sock *msk, - struct mptcp_subflow_context *subflow) +static inline void mptcp_early_fallback(struct mptcp_sock *msk, + struct mptcp_subflow_context *subflow, + int fb_mib) { pr_fallback(msk); subflow->request_mptcp =3D 0; - WARN_ON_ONCE(!__mptcp_try_fallback(msk)); + WARN_ON_ONCE(!__mptcp_try_fallback(msk, fb_mib)); } =20 static inline bool mptcp_check_infinite_map(struct sk_buff *skb) diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index 1802bc5435a1..600e59bba363 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -544,11 +544,13 @@ static void subflow_finish_connect(struct sock *sk, c= onst struct sk_buff *skb) mptcp_get_options(skb, &mp_opt); if (subflow->request_mptcp) { if (!(mp_opt.suboptions & OPTION_MPTCP_MPC_SYNACK)) { - if (!mptcp_try_fallback(sk)) + if (!mptcp_try_fallback(sk, + MPTCP_MIB_MPCAPABLEACTIVEFALLBACK)) { + MPTCP_INC_STATS(sock_net(sk), + MPTCP_MIB_FALLBACKFAILED); 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charset="utf-8"; x-default="true" We can now track fully the fallback status of a given connection via the relevant mibs, the mentioned helper is redundant. Remove it completely. Signed-off-by: Paolo Abeni --- v2 -> v3: - dropped unused variable in subflow_state_change() --- net/mptcp/options.c | 1 - net/mptcp/protocol.c | 1 - net/mptcp/protocol.h | 3 --- net/mptcp/subflow.c | 4 ---- 4 files changed, 9 deletions(-) diff --git a/net/mptcp/options.c b/net/mptcp/options.c index b49a8b3ffe00..3c08beffbfea 100644 --- a/net/mptcp/options.c +++ b/net/mptcp/options.c @@ -982,7 +982,6 @@ static bool check_fully_established(struct mptcp_sock *= msk, struct sock *ssk, MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_FALLBACKFAILED); goto reset; } - pr_fallback(msk); return false; } =20 diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 54dc39fd1495..c46993bf9d8e 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -1166,7 +1166,6 @@ static void mptcp_update_infinite_map(struct mptcp_so= ck *msk, } =20 mptcp_subflow_ctx(ssk)->send_infinite_map =3D 0; - pr_fallback(msk); } =20 #define MPTCP_MAX_GSO_SIZE (GSO_LEGACY_MAX_SIZE - (MAX_TCP_HEADER + 1)) diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index 74579743264f..db50b216143a 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -1254,13 +1254,10 @@ static inline bool mptcp_try_fallback(struct sock *= ssk, int fb_mib) return true; } =20 -#define pr_fallback(a) pr_debug("%s:fallback to TCP (msk=3D%p)\n", __func_= _, a) - static inline void mptcp_early_fallback(struct mptcp_sock *msk, struct mptcp_subflow_context *subflow, int fb_mib) { - pr_fallback(msk); subflow->request_mptcp =3D 0; WARN_ON_ONCE(!__mptcp_try_fallback(msk, fb_mib)); } diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index 600e59bba363..3f1b62a9fe88 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -551,7 +551,6 @@ static void subflow_finish_connect(struct sock *sk, con= st struct sk_buff *skb) goto do_reset; } =20 - pr_fallback(msk); goto fallback; } =20 @@ -1855,14 +1854,11 @@ static void subflow_state_change(struct sock *sk) { struct mptcp_subflow_context *subflow =3D mptcp_subflow_ctx(sk); struct sock *parent =3D subflow->conn; - struct mptcp_sock *msk; =20 __subflow_state_change(sk); =20 - msk =3D mptcp_sk(parent); if (subflow_simultaneous_connect(sk)) { WARN_ON_ONCE(!mptcp_try_fallback(sk, MPTCP_MIB_SIMULTCONNFALLBACK)); - pr_fallback(msk); subflow->conn_finished =3D 1; mptcp_propagate_state(parent, sk, subflow, NULL); } --=20 2.50.0