From nobody Thu Nov 27 15:25:57 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 A0DBA331A5D for ; Fri, 31 Oct 2025 17:29:28 +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=1761931770; cv=none; b=iGk1tasvjDEs2mq/anXOwyr4Gng+EY/DuSCSgsDYNMRZCqw2flqNNmpWFsrZZLOG/zbCSCdo1nPnGZtt1u7yWBxrnDz30UfyEC8/qoitcEXK+2qoZTtoWq+eevvNXO7kHmdOtMtgyzKZjMULsGRzU0gp1+mdg+HP3fRtUSM3tyI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761931770; c=relaxed/simple; bh=925QRmMF6Zjz3ppGM+y/mr/CYMs8bBov2XZYNg/czbE=; h=From:To:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:content-type; b=JfkGtAt4mdL2sOEAlmg34JEaXdE8LvF12t90oSxr5CZtTptlOBlU2iJCw2HI3LOStKc8OGVH88IoBvn0eH4I5d35f5zSVFRii0q0vtEMMQbuUIieLSaRaxwb2qTFG8p6kGLvpdFog4AoHUF7GBayemoJj/uznXwLPkHEvgYe/pU= 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=ZlpDqO84; 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="ZlpDqO84" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1761931767; 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=NwQsmS8ps/tg21yZh4cDIXl+G364XMwnREcj2nybW0Q=; b=ZlpDqO84BM1SUUcpodMFMaJJ63MSxwUEeflwma42hBmAp66HD94xpWwTflc9f85ctvsmJO IhZwxgm6fXMdXGb1XmUp3pd9FKxwmIUowLl2lIOxY1GyqONa4YO06++Nw26wNYchS7/OKC ZzawaWNTs3oJGX+nI9cL5CkWMP6P/Iw= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-539-qggaT7cRM423RddxRJ-3Vw-1; Fri, 31 Oct 2025 13:29:23 -0400 X-MC-Unique: qggaT7cRM423RddxRJ-3Vw-1 X-Mimecast-MFC-AGG-ID: qggaT7cRM423RddxRJ-3Vw_1761931762 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 B44841800345 for ; Fri, 31 Oct 2025 17:29:22 +0000 (UTC) Received: from gerbillo.redhat.com (unknown [10.45.224.247]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id B937330001A6 for ; Fri, 31 Oct 2025 17:29:21 +0000 (UTC) From: Paolo Abeni To: mptcp@lists.linux.dev Subject: [PATCH mptcp-next 2/4] mptcp: fix receive space time initialization. Date: Fri, 31 Oct 2025 18:29:08 +0100 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: 2otR9WievFTUZ1aaBHYS8ONrid5yzZUmzGkaIcFHVVM_1761931762 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8"; x-default="true" MPTCP initialize the receive buffer stamp in mptcp_rcv_space_init(), using the provided subflow stamp. Such helper is invoked in several places, with a catch-up call in mptcp_rcv_space_adjust(). For passive sockets, MPTCP ends-up accesses the subflow stamp before its initialization, leading to quite randomic timing for the first receive buffer auto-tune event. Fix the issue using a fresh stamp. Drop the all the mptcp_rcv_space_init() invocations except the catch-up one: they add unneeded complexity for no good reason. As a side effect, this avoid using a zero value for imsk->rcvq_space.time, that made the first receive buffer auto-tune even quite randomic. This will also make the next patch cleaner. Fixes: 013e3179dbd2 ("mptcp: fix rcv space initialization") Signed-off-by: Paolo Abeni --- net/mptcp/protocol.c | 40 ++++++++++++++++++++-------------------- net/mptcp/protocol.h | 6 +++++- net/mptcp/subflow.c | 2 -- 3 files changed, 25 insertions(+), 23 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index d16ad1a85411..e17abab7bab6 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -2047,6 +2047,21 @@ static int __mptcp_recvmsg_mskq(struct sock *sk, str= uct msghdr *msg, return copied; } =20 +static void mptcp_rcv_space_init(struct mptcp_sock *msk, const struct sock= *ssk) +{ + const struct tcp_sock *tp =3D tcp_sk(ssk); + + msk->rcvspace_init =3D 1; + msk->rcvq_space.copied =3D 0; + msk->rcvq_space.rtt_us =3D 0; + + /* initial rcv_space offering made to peer */ + msk->rcvq_space.space =3D min_t(u32, tp->rcv_wnd, + TCP_INIT_CWND * tp->advmss); + if (msk->rcvq_space.space =3D=3D 0) + msk->rcvq_space.space =3D TCP_INIT_CWND * TCP_MSS_DEFAULT; +} + /* receive buffer autotuning. See tcp_rcv_space_adjust for more informati= on. * * Only difference: Use highest rtt estimate of the subflows in use. @@ -2069,8 +2084,8 @@ static void mptcp_rcv_space_adjust(struct mptcp_sock = *msk, int copied) =20 msk->rcvq_space.copied +=3D copied; =20 - mstamp =3D div_u64(tcp_clock_ns(), NSEC_PER_USEC); - time =3D tcp_stamp_us_delta(mstamp, msk->rcvq_space.time); + mstamp =3D mptcp_stamp(); + time =3D tcp_stamp_us_delta(mstamp, READ_ONCE(msk->rcvq_space.time)); =20 rtt_us =3D msk->rcvq_space.rtt_us; if (rtt_us && time < (rtt_us >> 3)) @@ -3487,7 +3502,7 @@ struct sock *mptcp_sk_clone_init(const struct sock *s= k, mptcp_copy_inaddrs(nsk, ssk); __mptcp_propagate_sndbuf(nsk, ssk); =20 - mptcp_rcv_space_init(msk, ssk); + msk->rcvq_space.time =3D mptcp_stamp(); =20 if (mp_opt->suboptions & OPTION_MPTCP_MPC_ACK) __mptcp_subflow_fully_established(msk, subflow, mp_opt); @@ -3497,23 +3512,6 @@ struct sock *mptcp_sk_clone_init(const struct sock *= sk, return nsk; } =20 -void mptcp_rcv_space_init(struct mptcp_sock *msk, const struct sock *ssk) -{ - const struct tcp_sock *tp =3D tcp_sk(ssk); - - msk->rcvspace_init =3D 1; - msk->rcvq_space.copied =3D 0; - msk->rcvq_space.rtt_us =3D 0; - - msk->rcvq_space.time =3D tp->tcp_mstamp; - - /* initial rcv_space offering made to peer */ - msk->rcvq_space.space =3D min_t(u32, tp->rcv_wnd, - TCP_INIT_CWND * tp->advmss); - if (msk->rcvq_space.space =3D=3D 0) - msk->rcvq_space.space =3D TCP_INIT_CWND * TCP_MSS_DEFAULT; -} - static void mptcp_destroy(struct sock *sk) { struct mptcp_sock *msk =3D mptcp_sk(sk); @@ -3703,6 +3701,8 @@ void mptcp_finish_connect(struct sock *ssk) */ WRITE_ONCE(msk->local_key, subflow->local_key); =20 + WRITE_ONCE(msk->rcvq_space.time, mptcp_stamp()); + mptcp_pm_new_connection(msk, ssk, 0); } =20 diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index 84f2c51d776c..1f67d8468dfb 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -908,7 +908,11 @@ static inline bool mptcp_is_fully_established(struct s= ock *sk) READ_ONCE(mptcp_sk(sk)->fully_established); } =20 -void mptcp_rcv_space_init(struct mptcp_sock *msk, const struct sock *ssk); +static inline u64 mptcp_stamp(void) +{ + return div_u64(tcp_clock_ns(), NSEC_PER_USEC); +} + void mptcp_data_ready(struct sock *sk, struct sock *ssk); bool mptcp_finish_join(struct sock *sk); bool mptcp_schedule_work(struct sock *sk); diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index ac8616e7521e..b64ab7649908 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -462,8 +462,6 @@ void __mptcp_sync_state(struct sock *sk, int state) =20 subflow =3D mptcp_subflow_ctx(ssk); __mptcp_propagate_sndbuf(sk, ssk); - if (!msk->rcvspace_init) - mptcp_rcv_space_init(msk, ssk); =20 if (sk->sk_state =3D=3D TCP_SYN_SENT) { /* subflow->idsn is always available is TCP_SYN_SENT state, --=20 2.51.0