From nobody Sat Oct 11 05:52:54 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 B74303148DA for ; Thu, 18 Sep 2025 17:15:09 +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=1758215711; cv=none; b=Tg7eP79pRShF4MjLY88uMTOmWih5WaHE5BElixMckPGYB6wjoTBJUSKjz/a2HNHDiAcSX2Ue0DSpd0CmugxxcjXf/uGjL8895C3u3eWyAOj529MdvO13vZ3aorBzdbCQlGXwLEh/KgD3MquD1wR1RP2QxBfwG/L7CLd0TthSogE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758215711; c=relaxed/simple; bh=tAjYju49qLgXKjidfuks9AApLyUOdj1R5DUObAhkE2o=; h=From:To:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:content-type; b=n9CqsnmBhcZNshtsbEZ1xzssF3ThcwlmKiKE4GuiSSOQ7GGn6iWjZZ8exUS39N7j7NigdR9DCVEubMi0O+nQoeHuGfRUdoyjh8z31FWwaixiYBmudkkjqJ+MX9h9Oj6Caixgx+zi840DK+1Pu170Macm0QKdWAbScpAO4C0Nu74= 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=SozmHuCu; 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="SozmHuCu" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1758215708; 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=D+CckTl3ss84+JVzGPFjpsmjO/xblXYY18EunPs9Idc=; b=SozmHuCuooeXu5VgwNkbi6n1AhhSO9RDC/lgiELoQqn+VL1Dlclyp+EvvG3/IEk2hBgXzJ Sy8PefwReff1JkzHhaglj2KraZptOKUjhQqjg+yz6+X6MQD+N1v9rR72DXcWe68WtVKj3K yBrwrxDAZiUE1418u7CKz+8CUnHdDBQ= 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-201-UN7r_sW4ND21j3n6GsYjJw-1; Thu, 18 Sep 2025 13:15:07 -0400 X-MC-Unique: UN7r_sW4ND21j3n6GsYjJw-1 X-Mimecast-MFC-AGG-ID: UN7r_sW4ND21j3n6GsYjJw_1758215706 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (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 3AE93195608A for ; Thu, 18 Sep 2025 17:15:06 +0000 (UTC) Received: from gerbillo.redhat.com (unknown [10.44.32.207]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 61EC430002C5 for ; Thu, 18 Sep 2025 17:15:05 +0000 (UTC) From: Paolo Abeni To: mptcp@lists.linux.dev Subject: [PATCH mptcp-next v2 01/12] mptcp: leverage skb deferral free Date: Thu, 18 Sep 2025 19:14:43 +0200 Message-ID: <93b5f3f52220e59b5d22611b6fc0858353890105.1758214563.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 3.4.1 on 10.30.177.4 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: 60-aa39766ebop1dQFRhRR8MKmvUT2FcnqZ0lu3sUdg_1758215706 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8"; x-default="true" Usage of the skb deferral API is straight-forward; with multiple subflows actives this allow moving part of the received application load into multiple CPUs. Also fix a typo in the related comment. Signed-off-by: Paolo Abeni Reviewed-by: Geliang Tang Reviewed-by: Matthieu Baerts (NGI0) Tested-by: Geliang Tang --- net/mptcp/protocol.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 7933291e991ce..9d95d24781509 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -1943,12 +1943,13 @@ static int __mptcp_recvmsg_mskq(struct sock *sk, } =20 if (!(flags & MSG_PEEK)) { - /* avoid the indirect call, we know the destructor is sock_wfree */ + /* avoid the indirect call, we know the destructor is sock_rfree */ skb->destructor =3D NULL; + skb->sk =3D NULL; atomic_sub(skb->truesize, &sk->sk_rmem_alloc); sk_mem_uncharge(sk, skb->truesize); __skb_unlink(skb, &sk->sk_receive_queue); - __kfree_skb(skb); + skb_attempt_defer_free(skb); msk->bytes_consumed +=3D count; } =20 --=20 2.51.0 From nobody Sat Oct 11 05:52:54 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 F0D7F314A6C for ; 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Thu, 18 Sep 2025 13:15:08 -0400 X-MC-Unique: hW1aS_lzO-mGnmU1sLjmLg-1 X-Mimecast-MFC-AGG-ID: hW1aS_lzO-mGnmU1sLjmLg_1758215707 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (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-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 879E118002C0 for ; Thu, 18 Sep 2025 17:15:07 +0000 (UTC) Received: from gerbillo.redhat.com (unknown [10.44.32.207]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id B3E0F30002C5 for ; Thu, 18 Sep 2025 17:15:06 +0000 (UTC) From: Paolo Abeni To: mptcp@lists.linux.dev Subject: [PATCH mptcp-next v2 02/12] tcp: make tcp_rcvbuf_grow() accessible to mptcp code Date: Thu, 18 Sep 2025 19:14:44 +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 3.4.1 on 10.30.177.4 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: t-P0Fmjqo3S4tIvxesncMH_OZmH7rhMi2QFPlBBhvX4_1758215707 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8"; x-default="true" To leverage the auto-tuning improvements brought by commit 2da35e4b4df9 ("Merge branch 'tcp-receive-side-improvements'"), the MPTCP stack need to access the mentioned helper. Signed-off-by: Paolo Abeni Acked-by: Matthieu Baerts (NGI0) Reviewed-by: Geliang Tang Tested-by: Geliang Tang --- include/net/tcp.h | 1 + net/ipv4/tcp_input.c | 2 +- 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index e25340459ce4a..db2a4e05147fa 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -356,6 +356,7 @@ void tcp_delack_timer_handler(struct sock *sk); int tcp_ioctl(struct sock *sk, int cmd, int *karg); enum skb_drop_reason tcp_rcv_state_process(struct sock *sk, struct sk_buff= *skb); void tcp_rcv_established(struct sock *sk, struct sk_buff *skb); +void tcp_rcvbuf_grow(struct sock *sk); void tcp_rcv_space_adjust(struct sock *sk); int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp); void tcp_twsk_destructor(struct sock *sk); diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index b2793e749cfd9..ad09995a1aaec 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -701,7 +701,7 @@ static inline void tcp_rcv_rtt_measure_ts(struct sock *= sk, } } =20 -static void tcp_rcvbuf_grow(struct sock *sk) +void tcp_rcvbuf_grow(struct sock *sk) { const struct net *net =3D sock_net(sk); 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Thu, 18 Sep 2025 17:15:08 +0000 (UTC) Received: from gerbillo.redhat.com (unknown [10.44.32.207]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 0B85530002C5 for ; Thu, 18 Sep 2025 17:15:07 +0000 (UTC) From: Paolo Abeni To: mptcp@lists.linux.dev Subject: [PATCH mptcp-next v2 03/12] mptcp: rcvbuf auto-tuning improvement Date: Thu, 18 Sep 2025 19:14:45 +0200 Message-ID: <41db4ac9e54972274efd501dc110c5820def3412.1758214563.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 3.4.1 on 10.30.177.4 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: bk5BgiFz6C_uvec6Vx0o1We_36dhfGiE0WcMdYeY95Y_1758215708 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8"; x-default="true" Apply to the MPTCP auto-tuning the same improvements introduced for the TCP protocol by the merge commit 2da35e4b4df9 ("Merge branch 'tcp-receive-side-improvements'"). The main difference is that TCP subflow and the main MPTCP socket need to account separately for OoO: MPTCP does not care for TCP-level OoO and vice versa, as a consequence do not reflect MPTCP-level rcvbuf increase due to OoO packets at the subflow level. This refeactor additionally allow dropping the msk receive buffer update at receive time, as the latter only intended to cope with subflow receive buffer increase due to OoO packets. Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/487 Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/559 Signed-off-by: Paolo Abeni Reviewed-by: Geliang Tang Reviewed-by: Matthieu Baerts (NGI0) Tested-by: Geliang Tang --- v1 -> v2: - fix unused variable - reword the commit message --- net/mptcp/protocol.c | 92 ++++++++++++++++++++------------------------ net/mptcp/protocol.h | 4 +- 2 files changed, 44 insertions(+), 52 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 9d95d24781509..162abafe3f320 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -179,6 +179,30 @@ static bool mptcp_ooo_try_coalesce(struct mptcp_sock *= msk, struct sk_buff *to, return mptcp_try_coalesce((struct sock *)msk, to, from); } =20 +static bool mptcp_rcvbuf_grow(struct sock *sk) +{ + struct mptcp_sock *msk =3D mptcp_sk(sk); + int rcvwin, rcvbuf; + + if (!READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_moderate_rcvbuf) || + (sk->sk_userlocks & SOCK_RCVBUF_LOCK)) + return false; + + rcvwin =3D ((u64)msk->rcvq_space.space << 1); + + if (!RB_EMPTY_ROOT(&msk->out_of_order_queue)) + rcvwin +=3D MPTCP_SKB_CB(msk->ooo_last_skb)->end_seq - msk->ack_seq; + + rcvbuf =3D min_t(u64, mptcp_space_from_win(sk, rcvwin), + READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_rmem[2])); + + if (rcvbuf > sk->sk_rcvbuf) { + WRITE_ONCE(sk->sk_rcvbuf, rcvbuf); + return true; + } + return false; +} + /* "inspired" by tcp_data_queue_ofo(), main differences: * - use mptcp seqs * - don't cope with sacks @@ -292,6 +316,9 @@ static void mptcp_data_queue_ofo(struct mptcp_sock *msk= , struct sk_buff *skb) end: skb_condense(skb); skb_set_owner_r(skb, sk); + /* do not grow rcvbuf for not-yet-accepted or orphaned sockets. */ + if (sk->sk_socket) + mptcp_rcvbuf_grow(sk); } =20 static bool __mptcp_move_skb(struct mptcp_sock *msk, struct sock *ssk, @@ -784,18 +811,10 @@ static bool move_skbs_to_msk(struct mptcp_sock *msk, = struct sock *ssk) return moved; } =20 -static void __mptcp_rcvbuf_update(struct sock *sk, struct sock *ssk) -{ - if (unlikely(ssk->sk_rcvbuf > sk->sk_rcvbuf)) - WRITE_ONCE(sk->sk_rcvbuf, ssk->sk_rcvbuf); -} - static void __mptcp_data_ready(struct sock *sk, struct sock *ssk) { struct mptcp_sock *msk =3D mptcp_sk(sk); =20 - __mptcp_rcvbuf_update(sk, ssk); - /* Wake-up the reader only for in-sequence data */ if (move_skbs_to_msk(msk, ssk) && mptcp_epollin_ready(sk)) sk->sk_data_ready(sk); @@ -2014,48 +2033,26 @@ static void mptcp_rcv_space_adjust(struct mptcp_soc= k *msk, int copied) if (msk->rcvq_space.copied <=3D msk->rcvq_space.space) goto new_measure; =20 - if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_moderate_rcvbuf) && - !(sk->sk_userlocks & SOCK_RCVBUF_LOCK)) { - u64 rcvwin, grow; - int rcvbuf; - - rcvwin =3D ((u64)msk->rcvq_space.copied << 1) + 16 * advmss; - - grow =3D rcvwin * (msk->rcvq_space.copied - msk->rcvq_space.space); - - do_div(grow, msk->rcvq_space.space); - rcvwin +=3D (grow << 1); - - rcvbuf =3D min_t(u64, mptcp_space_from_win(sk, rcvwin), - READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_rmem[2])); - - if (rcvbuf > sk->sk_rcvbuf) { - u32 window_clamp; - - window_clamp =3D mptcp_win_from_space(sk, rcvbuf); - WRITE_ONCE(sk->sk_rcvbuf, rcvbuf); + msk->rcvq_space.space =3D msk->rcvq_space.copied; + if (mptcp_rcvbuf_grow(sk)) { =20 - /* Make subflows follow along. If we do not do this, we - * get drops at subflow level if skbs can't be moved to - * the mptcp rx queue fast enough (announced rcv_win can - * exceed ssk->sk_rcvbuf). - */ - mptcp_for_each_subflow(msk, subflow) { - struct sock *ssk; - bool slow; + /* Make subflows follow along. If we do not do this, we + * get drops at subflow level if skbs can't be moved to + * the mptcp rx queue fast enough (announced rcv_win can + * exceed ssk->sk_rcvbuf). + */ + mptcp_for_each_subflow(msk, subflow) { + struct sock *ssk; + bool slow; =20 - ssk =3D mptcp_subflow_tcp_sock(subflow); - slow =3D lock_sock_fast(ssk); - WRITE_ONCE(ssk->sk_rcvbuf, rcvbuf); - WRITE_ONCE(tcp_sk(ssk)->window_clamp, window_clamp); - if (tcp_can_send_ack(ssk)) - tcp_cleanup_rbuf(ssk, 1); - unlock_sock_fast(ssk, slow); - } + ssk =3D mptcp_subflow_tcp_sock(subflow); + slow =3D lock_sock_fast(ssk); + tcp_sk(ssk)->rcvq_space.space =3D msk->rcvq_space.copied; + tcp_rcvbuf_grow(ssk); + unlock_sock_fast(ssk, slow); } } =20 - msk->rcvq_space.space =3D msk->rcvq_space.copied; new_measure: msk->rcvq_space.copied =3D 0; msk->rcvq_space.time =3D mstamp; @@ -2084,11 +2081,6 @@ static bool __mptcp_move_skbs(struct sock *sk) if (list_empty(&msk->conn_list)) return false; =20 - /* verify we can move any data from the subflow, eventually updating */ - if (!(sk->sk_userlocks & SOCK_RCVBUF_LOCK)) - mptcp_for_each_subflow(msk, subflow) - __mptcp_rcvbuf_update(sk, subflow->tcp_sock); - subflow =3D list_first_entry(&msk->conn_list, struct mptcp_subflow_context, node); for (;;) { diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index 9b5a248bad404..6ac58e92a1aa3 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -342,8 +342,8 @@ struct mptcp_sock { struct mptcp_pm_data pm; struct mptcp_sched_ops *sched; struct { - u32 space; /* bytes copied in last measurement window */ - u32 copied; /* bytes copied in this measurement window */ + int space; /* bytes copied in last measurement window */ + int copied; /* bytes copied in this measurement window */ u64 time; /* start time of measurement window */ u64 rtt_us; /* last maximum rtt of subflows */ } rcvq_space; --=20 2.51.0 From nobody Sat Oct 11 05:52:54 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 F2B97316197 for ; 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Date: Thu, 18 Sep 2025 19:14:46 +0200 Message-ID: <81224b133af708289f5d62ad5960b4bb2c0b95dc.1758214564.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 3.4.1 on 10.30.177.4 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: DNBt3YjDlDkfLJOaU_TUfFVfqjdXsXCsTCznWMRjtKo_1758215710 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8"; x-default="true" Factor out all the skb initialization step in a new helper and use it. Note that this change moves the MPTCP CB initialization earlier: we can do such step as soon as the skb leaves the subflow socket receive queues. Signed-off-by: Paolo Abeni Reviewed-by: Matthieu Baerts (NGI0) --- v1 -> v2: - drop subflow argument from mptcp_init_skb() - change msk args to sock arg in __mptcp_move_skb() --- net/mptcp/protocol.c | 46 ++++++++++++++++++++++++-------------------- 1 file changed, 25 insertions(+), 21 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 162abafe3f320..048056b29a92d 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -321,27 +321,11 @@ static void mptcp_data_queue_ofo(struct mptcp_sock *m= sk, struct sk_buff *skb) mptcp_rcvbuf_grow(sk); } =20 -static bool __mptcp_move_skb(struct mptcp_sock *msk, struct sock *ssk, - struct sk_buff *skb, unsigned int offset, - size_t copy_len) +static void mptcp_init_skb(struct sock *ssk, + struct sk_buff *skb, int offset, int copy_len) { - struct mptcp_subflow_context *subflow =3D mptcp_subflow_ctx(ssk); - struct sock *sk =3D (struct sock *)msk; - struct sk_buff *tail; - bool has_rxtstamp; - - __skb_unlink(skb, &ssk->sk_receive_queue); - - skb_ext_reset(skb); - skb_orphan(skb); - - /* try to fetch required memory from subflow */ - if (!sk_rmem_schedule(sk, skb, skb->truesize)) { - MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_RCVPRUNED); - goto drop; - } - - has_rxtstamp =3D TCP_SKB_CB(skb)->has_rxtstamp; + const struct mptcp_subflow_context *subflow =3D mptcp_subflow_ctx(ssk); + bool has_rxtstamp =3D TCP_SKB_CB(skb)->has_rxtstamp; =20 /* the skb map_seq accounts for the skb offset: * mptcp_subflow_get_mapped_dsn() is based on the current tp->copied_seq @@ -353,6 +337,24 @@ static bool __mptcp_move_skb(struct mptcp_sock *msk, s= truct sock *ssk, 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); + + skb_ext_reset(skb); + skb_dst_drop(skb); +} + +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; 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charset="utf-8"; x-default="true" Since commit b7535cfed223 ("mptcp: drop legacy code around RX EOF"), sk_shutdown can't change during the main recvmsg loop, we can drop the related race breaker. Signed-off-by: Paolo Abeni Reviewed-by: Geliang Tang Reviewed-by: Matthieu Baerts (NGI0) Tested-by: Geliang Tang --- net/mptcp/protocol.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 048056b29a92d..19b5b925e2acc 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -2202,14 +2202,8 @@ static int mptcp_recvmsg(struct sock *sk, struct msg= hdr *msg, size_t len, break; } =20 - if (sk->sk_shutdown & RCV_SHUTDOWN) { - /* race breaker: the shutdown could be after the - * previous receive queue check - */ - if (__mptcp_move_skbs(sk)) - continue; + if (sk->sk_shutdown & RCV_SHUTDOWN) break; - } =20 if (sk->sk_state =3D=3D TCP_CLOSE) { copied =3D -ENOTCONN; --=20 2.51.0 From nobody Sat Oct 11 05:52:54 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 6656C3161A8 for ; Thu, 18 Sep 2025 17:15:16 +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=1758215717; cv=none; b=VWYVOpY7oUROXJa06v8ZCQp+rNSjxaMI8C/6Vs6ho2D2AVtNYwgxJeBDatIQQ9OUY3GF3ssjQnuicIqsIDLrEibvVDRp0do2MJe4lcYg0hQAAoqka51F1tZ6iUIIFRjx7Et+y9m5NPG7aEeygWgdmaUdXRmvleSsS3MO9zzftmM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758215717; c=relaxed/simple; bh=hP1K+FS3uEgLCSZe+MVPitH+2UFfd1nO7jq0RAzOzTo=; h=From:To:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:content-type; b=Em6VV5D2ihNiYuWWRApe5LYPLamjVt7tW2hQppPseVVSv1UWekd2ou7klzFascWiFHgq/wswe2PXR+6Cdw/iqBMGcmhUDxGdlvY40mdYD1wrXlGcPncMIZG+LbzTgBF88o6zKvg3c+5P1RJ7GFDI6YGGE+S8bcTM9om5hWRD+VE= 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=gSZJ7e0I; 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="gSZJ7e0I" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1758215715; 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=WwnpdFKsJh3rygT4cCoNMmNOreqzkefWCjkQplxWBhw=; b=gSZJ7e0IYXae8l5donv6NPVSYcmgWZJCFw6rXJasHAKtePltxPvhzpxh3JeJty15mNspFV eXIYzqMR+clFJsTy7aCCmesYWmaRgt/CWv6Hf+2KuCQGJDAAPCql0m8DA5ultmfkKOjMl3 qVvRXOcrZ1Hidt3EE9XobOdPebeWGrE= Received: from mx-prod-mc-01.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-681-7sGvA8-oMTChGCu8W4a6bQ-1; Thu, 18 Sep 2025 13:15:13 -0400 X-MC-Unique: 7sGvA8-oMTChGCu8W4a6bQ-1 X-Mimecast-MFC-AGG-ID: 7sGvA8-oMTChGCu8W4a6bQ_1758215713 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (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-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id F0B671956089 for ; Thu, 18 Sep 2025 17:15:12 +0000 (UTC) Received: from gerbillo.redhat.com (unknown [10.44.32.207]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 2923730002C5 for ; Thu, 18 Sep 2025 17:15:11 +0000 (UTC) From: Paolo Abeni To: mptcp@lists.linux.dev Subject: [PATCH mptcp-next v2 06/12] mptcp: factor out a basic skb coalesce helper Date: Thu, 18 Sep 2025 19:14:48 +0200 Message-ID: <0be52a39543e405a7812399646499b6f3c0cacde.1758214564.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 3.4.1 on 10.30.177.4 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: Og3yCWN00ZxxceM4hr1rBfeBAFRTvhiqCpeAIjHo6u4_1758215713 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8"; x-default="true" The upcoming patch will introduced backlog processing for MPTCP socket, and we want to leverage coalescing in such data path. Factor out the relevant bits not touching memory accounting to deal with such use-case. Signed-off-by: Paolo Abeni Reviewed-by: Matthieu Baerts (NGI0) --- net/mptcp/protocol.c | 24 ++++++++++++++++++------ 1 file changed, 18 insertions(+), 6 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 19b5b925e2acc..66ad9a38a6082 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -142,22 +142,34 @@ static void mptcp_drop(struct sock *sk, struct sk_buf= f *skb) __kfree_skb(skb); } =20 -static bool mptcp_try_coalesce(struct sock *sk, struct sk_buff *to, - struct sk_buff *from) +static int __mptcp_try_coalesce(struct sock *sk, struct sk_buff *to, + struct sk_buff *from, bool *fragstolen) { - bool fragstolen; + int limit =3D READ_ONCE(sk->sk_rcvbuf); int delta; =20 if (unlikely(MPTCP_SKB_CB(to)->cant_coalesce) || MPTCP_SKB_CB(from)->offset || - ((to->len + from->len) > (sk->sk_rcvbuf >> 3)) || - !skb_try_coalesce(to, from, &fragstolen, &delta)) - return false; + ((to->len + from->len) > (limit >> 3)) || + !skb_try_coalesce(to, from, fragstolen, &delta)) + return 0; =20 pr_debug("colesced seq %llx into %llx new len %d new end seq %llx\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; + return delta; +} + +static bool mptcp_try_coalesce(struct sock *sk, struct sk_buff *to, + struct sk_buff *from) +{ + bool fragstolen; + int delta; + + delta =3D __mptcp_try_coalesce(sk, to, from, &fragstolen); + if (!delta) + return false; =20 /* note the fwd memory can reach a negative value after accounting * for the delta, but the later skb free will restore a non --=20 2.51.0 From nobody Sat Oct 11 05:52:54 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 056513168E1 for ; Thu, 18 Sep 2025 17:15:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; 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charset="utf-8"; x-default="true" Such function is called only by __mptcp_data_ready(), which in turn is always invoked when msk is not owned by the user: we can drop the redundant, related check. Additionally mptcp needs to propagate the socket error only for current subflow. Signed-off-by: Paolo Abeni Reviewed-by: Geliang Tang Reviewed-by: Matthieu Baerts (NGI0) Tested-by: Geliang Tang --- net/mptcp/protocol.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 66ad9a38a6082..02be42d3d11e6 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -810,12 +810,8 @@ static bool move_skbs_to_msk(struct mptcp_sock *msk, s= truct sock *ssk) =20 moved =3D __mptcp_move_skbs_from_subflow(msk, ssk); __mptcp_ofo_queue(msk); - if (unlikely(ssk->sk_err)) { - if (!sock_owned_by_user(sk)) - __mptcp_error_report(sk); - else - __set_bit(MPTCP_ERROR_REPORT, &msk->cb_flags); - } + if (unlikely(ssk->sk_err)) + __mptcp_subflow_error_report(sk, ssk); =20 /* If the moves have caught up with the DATA_FIN sequence number * it's time to ack the DATA_FIN and change socket state, but --=20 2.51.0 From nobody Sat Oct 11 05:52:54 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 119583161AC for ; 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charset="utf-8"; x-default="true" MPTCP currently generate a dummy data_fin for fallback socket when the fallback subflow has completed data reception using the current ack_seq. We are going to introduce backlog usage for the msk soon, even for fallback sockets: the above condition will be not be correct as it will ignore data_seq sitting in the backlog. Instead generate the dummy data_fin when the last data packet is extracted by the fallback subflow. The scenario with fallback socket receiving a reset while the receive queue empty is caught via the generic 'all subflows closed' timeout: ensure such timeout is zero for fallback sockets. Signed-off-by: Paolo Abeni --- net/mptcp/ctrl.c | 2 ++ net/mptcp/subflow.c | 16 ++++++++-------- 2 files changed, 10 insertions(+), 8 deletions(-) diff --git a/net/mptcp/ctrl.c b/net/mptcp/ctrl.c index fed40dae5583a..4f7795968abe2 100644 --- a/net/mptcp/ctrl.c +++ b/net/mptcp/ctrl.c @@ -74,6 +74,8 @@ unsigned int mptcp_stale_loss_cnt(const struct net *net) =20 unsigned int mptcp_close_timeout(const struct sock *sk) { + if (__mptcp_check_fallback(mptcp_sk(sk))) + return 0; if (sock_flag(sk, SOCK_DEAD)) return TCP_TIMEWAIT_LEN; return mptcp_get_pernet(sock_net(sk))->close_timeout; diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index e8325890a3223..9baf3e54e46f2 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -1297,14 +1297,6 @@ static void subflow_sched_work_if_closed(struct mptc= p_sock *msk, struct sock *ss =20 if (!test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags)) mptcp_schedule_work(sk); - - /* when the fallback subflow closes the rx side, trigger a 'dummy' - * ingress data fin, so that the msk state will follow along - */ - if (__mptcp_check_fallback(msk) && subflow_is_done(ssk) && - msk->first =3D=3D ssk && - mptcp_update_rcv_data_fin(msk, READ_ONCE(msk->ack_seq), true)) - mptcp_schedule_work(sk); 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Thu, 18 Sep 2025 13:15:17 -0400 X-MC-Unique: 1NoGOxuZPZmZtWCgd7Dbjg-1 X-Mimecast-MFC-AGG-ID: 1NoGOxuZPZmZtWCgd7Dbjg_1758215717 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (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-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id EC9CD1800290 for ; Thu, 18 Sep 2025 17:15:16 +0000 (UTC) Received: from gerbillo.redhat.com (unknown [10.44.32.207]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 230C030002C5 for ; Thu, 18 Sep 2025 17:15:15 +0000 (UTC) From: Paolo Abeni To: mptcp@lists.linux.dev Subject: [PATCH mptcp-next v2 09/12] mptcp: leverage the sk backlog for RX packet processing. Date: Thu, 18 Sep 2025 19:14:51 +0200 Message-ID: <0239ffcbcd9c77f6b4eaf0897583310cae950dc2.1758214564.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 3.4.1 on 10.30.177.4 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: uf4PEvt3zaWSPFbPt2s6piyaeFvDsf-tt83hQxxX4ZI_1758215717 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8"; x-default="true" This streamline the RX path implementation and improves the RX performances by reducing the subflow-level locking and the amount of work done under the msk socket lock; the implementation mirror closely the TCP backlog processing. Note that MPTCP needs now to traverse the existing subflow looking for data that was left there due to the msk receive buffer full, only after that recvmsg completely empties the receive queue. Signed-off-by: Paolo Abeni --- net/mptcp/protocol.c | 103 ++++++++++++++++++++++++++++++------------- net/mptcp/protocol.h | 2 +- 2 files changed, 73 insertions(+), 32 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 02be42d3d11e6..07326c1e6fbae 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -355,6 +355,27 @@ static void mptcp_init_skb(struct sock *ssk, skb_dst_drop(skb); } =20 +static void __mptcp_add_backlog(struct sock *sk, struct sock *ssk, + struct sk_buff *skb) +{ + struct sk_buff *tail =3D sk->sk_backlog.tail; + bool fragstolen; + int delta; + + if (tail && MPTCP_SKB_CB(skb)->map_seq =3D=3D MPTCP_SKB_CB(tail)->end_seq= ) { + delta =3D __mptcp_try_coalesce(sk, tail, skb, &fragstolen); + if (delta) { + sk->sk_backlog.len +=3D delta; + kfree_skb_partial(skb, fragstolen); + return; + } + } + + /* mptcp checks the limit before adding the skb to the backlog */ + __sk_add_backlog(sk, skb); + sk->sk_backlog.len +=3D skb->truesize; +} + 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; @@ -643,7 +664,7 @@ static void mptcp_dss_corruption(struct mptcp_sock *msk= , struct sock *ssk) } =20 static bool __mptcp_move_skbs_from_subflow(struct mptcp_sock *msk, - struct sock *ssk) + struct sock *ssk, bool own_msk) { struct mptcp_subflow_context *subflow =3D mptcp_subflow_ctx(ssk); struct sock *sk =3D (struct sock *)msk; @@ -654,12 +675,13 @@ static bool __mptcp_move_skbs_from_subflow(struct mpt= cp_sock *msk, pr_debug("msk=3D%p ssk=3D%p\n", msk, ssk); tp =3D tcp_sk(ssk); do { + int mem =3D own_msk ? sk_rmem_alloc_get(sk) : sk->sk_backlog.len; u32 map_remaining, offset; u32 seq =3D tp->copied_seq; struct sk_buff *skb; bool fin; =20 - if (sk_rmem_alloc_get(sk) > sk->sk_rcvbuf) + if (mem > READ_ONCE(sk->sk_rcvbuf)) break; =20 /* try to move as much data as available */ @@ -689,7 +711,11 @@ static bool __mptcp_move_skbs_from_subflow(struct mptc= p_sock *msk, =20 mptcp_init_skb(ssk, skb, offset, len); skb_orphan(skb); - ret =3D __mptcp_move_skb(sk, skb) || ret; + + if (own_msk) + ret |=3D __mptcp_move_skb(sk, skb); + else + __mptcp_add_backlog(sk, ssk, skb); seq +=3D len; =20 if (unlikely(map_remaining < len)) { @@ -710,7 +736,7 @@ static bool __mptcp_move_skbs_from_subflow(struct mptcp= _sock *msk, =20 } while (more_data_avail); =20 - if (ret) + if (ret && own_msk) msk->last_data_recv =3D tcp_jiffies32; return ret; } @@ -808,7 +834,7 @@ static bool move_skbs_to_msk(struct mptcp_sock *msk, st= ruct sock *ssk) struct sock *sk =3D (struct sock *)msk; bool moved; =20 - moved =3D __mptcp_move_skbs_from_subflow(msk, ssk); + moved =3D __mptcp_move_skbs_from_subflow(msk, ssk, true); __mptcp_ofo_queue(msk); if (unlikely(ssk->sk_err)) __mptcp_subflow_error_report(sk, ssk); @@ -823,18 +849,10 @@ static bool move_skbs_to_msk(struct mptcp_sock *msk, = struct sock *ssk) return moved; } =20 -static void __mptcp_data_ready(struct sock *sk, struct sock *ssk) -{ - struct mptcp_sock *msk =3D mptcp_sk(sk); - - /* Wake-up the reader only for in-sequence data */ - if (move_skbs_to_msk(msk, ssk) && mptcp_epollin_ready(sk)) - sk->sk_data_ready(sk); -} - void mptcp_data_ready(struct sock *sk, struct sock *ssk) { struct mptcp_subflow_context *subflow =3D mptcp_subflow_ctx(ssk); + struct mptcp_sock *msk =3D mptcp_sk(sk); =20 /* The peer can send data while we are shutting down this * subflow at msk destruction time, but we must avoid enqueuing @@ -844,13 +862,33 @@ void mptcp_data_ready(struct sock *sk, struct sock *s= sk) return; =20 mptcp_data_lock(sk); - if (!sock_owned_by_user(sk)) - __mptcp_data_ready(sk, ssk); - else - __set_bit(MPTCP_DEQUEUE, &mptcp_sk(sk)->cb_flags); + if (!sock_owned_by_user(sk)) { + /* Wake-up the reader only for in-sequence data */ + if (move_skbs_to_msk(msk, ssk) && mptcp_epollin_ready(sk)) + sk->sk_data_ready(sk); + } else { + __mptcp_move_skbs_from_subflow(msk, ssk, false); + if (unlikely(ssk->sk_err)) + __set_bit(MPTCP_ERROR_REPORT, &msk->cb_flags); + } mptcp_data_unlock(sk); } =20 +static int mptcp_move_skb(struct sock *sk, struct sk_buff *skb) +{ + struct mptcp_sock *msk =3D mptcp_sk(sk); + + if (__mptcp_move_skb(sk, skb)) { + msk->last_data_recv =3D tcp_jiffies32; + __mptcp_ofo_queue(msk); + /* notify ack seq update */ + mptcp_cleanup_rbuf(msk, 0); + mptcp_check_data_fin(sk); + sk->sk_data_ready(sk); + } + return 0; +} + static void mptcp_subflow_joined(struct mptcp_sock *msk, struct sock *ssk) { mptcp_subflow_ctx(ssk)->map_seq =3D READ_ONCE(msk->ack_seq); @@ -2112,7 +2150,7 @@ static bool __mptcp_move_skbs(struct sock *sk) =20 ssk =3D mptcp_subflow_tcp_sock(subflow); slowpath =3D lock_sock_fast(ssk); - ret =3D __mptcp_move_skbs_from_subflow(msk, ssk) || ret; + ret =3D __mptcp_move_skbs_from_subflow(msk, ssk, true) || ret; if (unlikely(ssk->sk_err)) __mptcp_error_report(sk); unlock_sock_fast(ssk, slowpath); @@ -2188,8 +2226,12 @@ static int mptcp_recvmsg(struct sock *sk, struct msg= hdr *msg, size_t len, =20 copied +=3D bytes_read; =20 - if (skb_queue_empty(&sk->sk_receive_queue) && __mptcp_move_skbs(sk)) - continue; + if (skb_queue_empty(&sk->sk_receive_queue)) { + __sk_flush_backlog(sk); + if (!skb_queue_empty(&sk->sk_receive_queue) || + __mptcp_move_skbs(sk)) + continue; + } =20 /* only the MPTCP socket status is relevant here. The exit * conditions mirror closely tcp_recvmsg() @@ -2537,7 +2579,6 @@ static void __mptcp_close_subflow(struct sock *sk) =20 mptcp_close_ssk(sk, ssk, subflow); } - } =20 static bool mptcp_close_tout_expired(const struct sock *sk) @@ -3121,6 +3162,13 @@ bool __mptcp_close(struct sock *sk, long timeout) pr_debug("msk=3D%p state=3D%d\n", sk, sk->sk_state); mptcp_pm_connection_closed(msk); =20 + /* process the backlog; note that it never destroies the msk */ + local_bh_disable(); + bh_lock_sock(sk); + __release_sock(sk); + bh_unlock_sock(sk); + local_bh_enable(); + if (sk->sk_state =3D=3D TCP_CLOSE) { __mptcp_destroy_sock(sk); do_cancel_work =3D true; @@ -3421,8 +3469,7 @@ void __mptcp_check_push(struct sock *sk, struct sock = *ssk) =20 #define MPTCP_FLAGS_PROCESS_CTX_NEED (BIT(MPTCP_PUSH_PENDING) | \ BIT(MPTCP_RETRANSMIT) | \ - BIT(MPTCP_FLUSH_JOIN_LIST) | \ - BIT(MPTCP_DEQUEUE)) + BIT(MPTCP_FLUSH_JOIN_LIST)) =20 /* processes deferred events and flush wmem */ static void mptcp_release_cb(struct sock *sk) @@ -3456,11 +3503,6 @@ static void mptcp_release_cb(struct sock *sk) __mptcp_push_pending(sk, 0); if (flags & BIT(MPTCP_RETRANSMIT)) __mptcp_retrans(sk); - if ((flags & BIT(MPTCP_DEQUEUE)) && __mptcp_move_skbs(sk)) { - /* notify ack seq update */ - mptcp_cleanup_rbuf(msk, 0); - sk->sk_data_ready(sk); - } =20 cond_resched(); spin_lock_bh(&sk->sk_lock.slock); @@ -3696,8 +3738,6 @@ static int mptcp_ioctl(struct sock *sk, int cmd, int = *karg) return -EINVAL; =20 lock_sock(sk); - if (__mptcp_move_skbs(sk)) - mptcp_cleanup_rbuf(msk, 0); *karg =3D mptcp_inq_hint(sk); release_sock(sk); break; @@ -3809,6 +3849,7 @@ static struct proto mptcp_prot =3D { .sendmsg =3D mptcp_sendmsg, .ioctl =3D mptcp_ioctl, .recvmsg =3D mptcp_recvmsg, + .backlog_rcv =3D mptcp_move_skb, .release_cb =3D mptcp_release_cb, .hash =3D mptcp_hash, .unhash =3D mptcp_unhash, diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index 6ac58e92a1aa3..7bfd4e0d21a8a 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -124,7 +124,6 @@ #define MPTCP_FLUSH_JOIN_LIST 5 #define MPTCP_SYNC_STATE 6 #define MPTCP_SYNC_SNDBUF 7 -#define MPTCP_DEQUEUE 8 =20 struct mptcp_skb_cb { u64 map_seq; 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Thu, 18 Sep 2025 17:15:18 +0000 (UTC) Received: from gerbillo.redhat.com (unknown [10.44.32.207]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 73A9A30002C5 for ; Thu, 18 Sep 2025 17:15:17 +0000 (UTC) From: Paolo Abeni To: mptcp@lists.linux.dev Subject: [PATCH mptcp-next v2 10/12] mptcp: prevernt __mptcp_move_skbs() interfering with the fastpath Date: Thu, 18 Sep 2025 19:14:52 +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 3.4.1 on 10.30.177.4 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: sRmS2nr5FrKPnvtgK70p0vRdSqyDK6oVebHk_k2KbEU_1758215718 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8"; x-default="true" skbs will be left waiting in the subflow only in exceptional cases, we want to avoid messing with the fast path by unintentionally processing in __mptcp_move_skbs() packets landed into the subflows after the last check. Use a separate flag to mark delayed skbs and only process subflow with such flag set. Also add new mibs to track the exceptional events. Signed-off-by: Paolo Abeni --- v1 -> v2: - rebased --- net/mptcp/mib.c | 2 ++ net/mptcp/mib.h | 4 ++++ net/mptcp/protocol.c | 40 ++++++++++++---------------------------- net/mptcp/protocol.h | 1 + 4 files changed, 19 insertions(+), 28 deletions(-) diff --git a/net/mptcp/mib.c b/net/mptcp/mib.c index 6003e47c770a7..ac5ccf81159de 100644 --- a/net/mptcp/mib.c +++ b/net/mptcp/mib.c @@ -85,6 +85,8 @@ static const struct snmp_mib mptcp_snmp_list[] =3D { SNMP_MIB_ITEM("DssFallback", MPTCP_MIB_DSSFALLBACK), SNMP_MIB_ITEM("SimultConnectFallback", MPTCP_MIB_SIMULTCONNFALLBACK), SNMP_MIB_ITEM("FallbackFailed", MPTCP_MIB_FALLBACKFAILED), + SNMP_MIB_ITEM("RcvDelayed", MPTCP_MIB_RCVDELAYED), + SNMP_MIB_ITEM("DelayedProcess", MPTCP_MIB_DELAYED_PROCESS), }; =20 /* mptcp_mib_alloc - allocate percpu mib counters diff --git a/net/mptcp/mib.h b/net/mptcp/mib.h index 309bac6fea325..f6d0eaea463e5 100644 --- a/net/mptcp/mib.h +++ b/net/mptcp/mib.h @@ -88,6 +88,10 @@ enum linux_mptcp_mib_field { MPTCP_MIB_DSSFALLBACK, /* Bad or missing DSS */ MPTCP_MIB_SIMULTCONNFALLBACK, /* Simultaneous connect */ MPTCP_MIB_FALLBACKFAILED, /* Can't fallback due to msk status */ + MPTCP_MIB_RCVDELAYED, /* Data move from subflow is delayed due to msk + * receive buffer full + */ + MPTCP_MIB_DELAYED_PROCESS, /* Delayed data moved in slowpath */ __MPTCP_MIB_MAX }; =20 diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 07326c1e6fbae..3c514b6be4eb9 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -676,13 +676,17 @@ static bool __mptcp_move_skbs_from_subflow(struct mpt= cp_sock *msk, tp =3D tcp_sk(ssk); do { int mem =3D own_msk ? sk_rmem_alloc_get(sk) : sk->sk_backlog.len; + bool over_limit =3D mem > READ_ONCE(sk->sk_rcvbuf); u32 map_remaining, offset; u32 seq =3D tp->copied_seq; struct sk_buff *skb; bool fin; =20 - if (mem > READ_ONCE(sk->sk_rcvbuf)) + WRITE_ONCE(subflow->data_delayed, over_limit); + if (subflow->data_delayed) { + MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_RCVDELAYED); break; + } =20 /* try to move as much data as available */ map_remaining =3D subflow->map_data_len - @@ -2108,32 +2112,13 @@ static void mptcp_rcv_space_adjust(struct mptcp_soc= k *msk, int copied) msk->rcvq_space.time =3D mstamp; } =20 -static struct mptcp_subflow_context * -__mptcp_first_ready_from(struct mptcp_sock *msk, - struct mptcp_subflow_context *subflow) -{ - struct mptcp_subflow_context *start_subflow =3D subflow; - - while (!READ_ONCE(subflow->data_avail)) { - subflow =3D mptcp_next_subflow(msk, subflow); - if (subflow =3D=3D start_subflow) - return NULL; - } - return subflow; -} - static bool __mptcp_move_skbs(struct sock *sk) { struct mptcp_subflow_context *subflow; struct mptcp_sock *msk =3D mptcp_sk(sk); bool ret =3D false; =20 - if (list_empty(&msk->conn_list)) - return false; - - subflow =3D list_first_entry(&msk->conn_list, - struct mptcp_subflow_context, node); - for (;;) { + mptcp_for_each_subflow(msk, subflow) { struct sock *ssk; bool slowpath; =20 @@ -2144,23 +2129,22 @@ static bool __mptcp_move_skbs(struct sock *sk) if (sk_rmem_alloc_get(sk) > sk->sk_rcvbuf) break; =20 - subflow =3D __mptcp_first_ready_from(msk, subflow); - if (!subflow) - break; + if (!subflow->data_delayed) + continue; =20 ssk =3D mptcp_subflow_tcp_sock(subflow); slowpath =3D lock_sock_fast(ssk); - ret =3D __mptcp_move_skbs_from_subflow(msk, ssk, true) || ret; + ret |=3D __mptcp_move_skbs_from_subflow(msk, ssk, true); 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charset="utf-8"; x-default="true" In the MPTCP receive path, we release the subflow allocated fwd memory just to allocate it again shortly after for the msk. That could increases the failures chances, especially during backlog processing, when other actions could consume the just released memory before the msk socket has a chance to do the rcv allocation. Replace the skb_orphan() call with an open-coded variant that explicitly borrows, with a PAGE_SIZE granularity, the fwd memory from the subflow socket instead of releasing it. During backlog processing the borrowed memory is accounted at release_cb time. Signed-off-by: Paolo Abeni --- v1 -> v2: - rebased - explain why skb_orphan is removed --- net/mptcp/protocol.c | 27 +++++++++++++++++++++------ net/mptcp/protocol.h | 1 + 2 files changed, 22 insertions(+), 6 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 3c514b6be4eb9..50c63c40d5bca 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -333,11 +333,12 @@ static void mptcp_data_queue_ofo(struct mptcp_sock *m= sk, struct sk_buff *skb) mptcp_rcvbuf_grow(sk); } =20 -static void mptcp_init_skb(struct sock *ssk, - struct sk_buff *skb, int offset, int copy_len) +static int mptcp_init_skb(struct sock *ssk, + struct sk_buff *skb, int offset, int copy_len) { const struct mptcp_subflow_context *subflow =3D mptcp_subflow_ctx(ssk); bool has_rxtstamp =3D TCP_SKB_CB(skb)->has_rxtstamp; + int borrowed; =20 /* the skb map_seq accounts for the skb offset: * mptcp_subflow_get_mapped_dsn() is based on the current tp->copied_seq @@ -353,6 +354,15 @@ static void mptcp_init_skb(struct sock *ssk, =20 skb_ext_reset(skb); skb_dst_drop(skb); + + /* "borrow" the fwd memory from the subflow, instead of reclaiming it */ + skb->destructor =3D NULL; + skb->sk =3D NULL; + atomic_sub(skb->truesize, &ssk->sk_rmem_alloc); + borrowed =3D ssk->sk_forward_alloc - sk_unused_reserved_mem(ssk); + borrowed &=3D ~(PAGE_SIZE - 1); + sk_forward_alloc_add(ssk, skb->truesize - borrowed); + return borrowed; } =20 static void __mptcp_add_backlog(struct sock *sk, struct sock *ssk, @@ -712,14 +722,17 @@ static bool __mptcp_move_skbs_from_subflow(struct mpt= cp_sock *msk, =20 if (offset < skb->len) { size_t len =3D skb->len - offset; + int bmem; =20 - mptcp_init_skb(ssk, skb, offset, len); - skb_orphan(skb); + bmem =3D mptcp_init_skb(ssk, skb, offset, len); =20 - if (own_msk) + if (own_msk) { + sk_forward_alloc_add(sk, bmem); ret |=3D __mptcp_move_skb(sk, skb); - else + } else { + msk->borrowed_fwd_mem +=3D bmem; __mptcp_add_backlog(sk, ssk, skb); + } seq +=3D len; =20 if (unlikely(map_remaining < len)) { @@ -3506,6 +3519,8 @@ static void mptcp_release_cb(struct sock *sk) if (__test_and_clear_bit(MPTCP_SYNC_SNDBUF, &msk->cb_flags)) __mptcp_sync_sndbuf(sk); 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Thu, 18 Sep 2025 13:15:23 -0400 X-MC-Unique: eE_B8Q0BNGeUcE5PBbrD5w-1 X-Mimecast-MFC-AGG-ID: eE_B8Q0BNGeUcE5PBbrD5w_1758215722 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (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-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 39DFB19560A1 for ; Thu, 18 Sep 2025 17:15:22 +0000 (UTC) Received: from gerbillo.redhat.com (unknown [10.44.32.207]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 6B1B330002C5 for ; Thu, 18 Sep 2025 17:15:21 +0000 (UTC) From: Paolo Abeni To: mptcp@lists.linux.dev Subject: [PATCH mptcp-next v2 12/12] mptcp: make fallback backlog aware Date: Thu, 18 Sep 2025 19:14:55 +0200 Message-ID: <969bb267528128e861970168da3264822be48b35.1758214564.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 3.4.1 on 10.30.177.4 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: XSjJX1_NMo_84yGnPAlD9oaz629GFF-6f2zAA8SdtHk_1758215722 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8"; x-default="true" MPTCP can't relay on ack_seq outside the msk socket log scope. With packets pending in the backlog, such value can be quite far from the actual dummy correct sequence map value. Fallback dummy mapping are in sequence by definition, generate the data seq from the subflow sequence. Signed-off-by: Paolo Abeni --- net/mptcp/subflow.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index 9baf3e54e46f2..8a64a1934d784 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -491,6 +491,9 @@ static void subflow_set_remote_key(struct mptcp_sock *m= sk, mptcp_crypto_key_sha(subflow->remote_key, NULL, &subflow->iasn); subflow->iasn++; =20 + /* for fallback's sake */ + subflow->map_seq =3D subflow->iasn; + WRITE_ONCE(msk->remote_key, subflow->remote_key); WRITE_ONCE(msk->ack_seq, subflow->iasn); WRITE_ONCE(msk->can_ack, true); @@ -1425,9 +1428,12 @@ static bool subflow_check_data_avail(struct sock *ss= k) =20 skb =3D skb_peek(&ssk->sk_receive_queue); subflow->map_valid =3D 1; - subflow->map_seq =3D READ_ONCE(msk->ack_seq); subflow->map_data_len =3D skb->len; subflow->map_subflow_seq =3D tcp_sk(ssk)->copied_seq - subflow->ssn_offse= t; + subflow->map_seq =3D __mptcp_expand_seq(subflow->map_seq, + subflow->iasn + + TCP_SKB_CB(skb)->seq - + subflow->ssn_offset - 1); WRITE_ONCE(subflow->data_avail, true); =20 /* last skb in closed fallback subflow: we are at data fin */ --=20 2.51.0