From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-184.mta0.migadu.com (out-184.mta0.migadu.com [91.218.175.184]) (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 41F5E1A01BE for ; Thu, 16 Apr 2026 12:29:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.184 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776342601; cv=none; b=FvqfoHAW3FO/l6jnNZ0wvl6Wq2V7uD2waNIHxP17xLM14vCeIEFVNvugWw+v5B1LlLibc9KUz3A20Sr4v/jJ2WKEnHhlHXMIt7pPBmFR3ktq+mfp06PGfnSVsBhloUhUczi4eXKyM934tqnniPj4Ajbx7yFgd4O/P1kHubPsjPs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776342601; c=relaxed/simple; bh=+zlTdHKPR4zwmeO3zRr60i3n2Qdd7f51lJ5i17AyGfE=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version:Content-Type; b=JdZXRqqFO22DOgwc87guHiph3o5driEZ4/ve4DS7JWbRcK0xHCxqn0X0P1WE/O3ESqoT7FP0lMoRwvW9HvLCrkA3O/Qg5Qm+6uUgjn3cIffNrEWys/pXjTbUh8dOdvnasVnWLaQ2aj+hj6H4BYIPYYPLCW7QD8SmoIUVEy9AgaA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=Yexl6Cea; arc=none smtp.client-ip=91.218.175.184 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="Yexl6Cea" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1776342596; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=gBFMYzUnAlghwSVoKDrnLUvzM3pNpjw5oWiMd8HcvrY=; b=Yexl6CeaF8OVWYTCN0Hc4trVw9eHMUJJzlRJrsK7qwl1msJX3xbAgYZ0xcTOIQ0XqtmHNI QMVZ7N3TcvJUDHCKH4FzY3lUrt4VelG5qrDLDd5OmjsS0oJPBVwg5m/JJWRLga62GBnKa7 gEUddGBWwtX9ijzpjQtjGGL8RI87cbM= From: Gang Yan To: mptcp@lists.linux.dev Cc: Gang Yan Subject: [PATCH mptcp-net] mptcp: update window_clamp on subflows when SO_RCVBUF is set Date: Thu, 16 Apr 2026 20:29:43 +0800 Message-ID: <20260416122945.324166-1-gang.yan@linux.dev> Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=y Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT From: Gang Yan Add __mptcp_subflow_set_rcvbuf() helper that calls the subflow's ops->set_rcvbuf to update window_clamp, in addition to writing sk_rcvbuf. Use it in both mptcp_sol_socket_sync_intval() (setsockopt path) and sync_socket_options() (new subflow creation path). Fixes: a2cbb1603943 ("tcp: Update window clamping condition") Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/619 Signed-off-by: Gang Yan --- Notes: Hi Matt: Note that I do not implement set_rcvbuf in mptcp_stream_ops for the following reasons: - The callback receives the MPTCP meta socket as 'sk', but tcp_set_rcvbuf() must be called on each TCP subflow to update window_clamp. A callback implementation would need to iterate all subflows, duplicating the work already done by mptcp_sol_socket_sync_intval(). - Subflows are grafted to the MPTCP socket via mptcp_sock_graft(), so ssk->sk_socket->ops points to mptcp_stream_ops, not inet_stream_ops. This means the TCP set_rcvbuf callback is not reachable through the subflow's ops either. - The existing subflow sync functions cover both the setsockopt path (mptcp_sol_socket_sync_intval) and new subflow creation path (sync_socket_options), making the proto_ops callback unnecessary. WDYT？ The packetdrill tests is also implemented: -Link: https://github.com/multipath-tcp/packetdrill/pull/194 Thanks Gang --- net/mptcp/sockopt.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c index de90a2897d2d..abe63392826b 100644 --- a/net/mptcp/sockopt.c +++ b/net/mptcp/sockopt.c @@ -67,6 +67,12 @@ static int mptcp_get_int_option(struct mptcp_sock *msk, sockptr_t optval, return 0; } +static inline void __mptcp_subflow_set_rcvbuf(struct sock *ssk, int val) +{ + WRITE_ONCE(ssk->sk_rcvbuf, val); + tcp_set_rcvbuf(ssk, val); +} + static void mptcp_sol_socket_sync_intval(struct mptcp_sock *msk, int optname, int val) { struct mptcp_subflow_context *subflow; @@ -100,7 +106,7 @@ static void mptcp_sol_socket_sync_intval(struct mptcp_sock *msk, int optname, in case SO_RCVBUF: case SO_RCVBUFFORCE: ssk->sk_userlocks |= SOCK_RCVBUF_LOCK; - WRITE_ONCE(ssk->sk_rcvbuf, sk->sk_rcvbuf); + __mptcp_subflow_set_rcvbuf(ssk, sk->sk_rcvbuf); break; case SO_MARK: if (READ_ONCE(ssk->sk_mark) != sk->sk_mark) { @@ -1556,7 +1562,7 @@ static void sync_socket_options(struct mptcp_sock *msk, struct sock *ssk) mptcp_subflow_ctx(ssk)->cached_sndbuf = sk->sk_sndbuf; } if (sk->sk_userlocks & SOCK_RCVBUF_LOCK) - WRITE_ONCE(ssk->sk_rcvbuf, sk->sk_rcvbuf); + __mptcp_subflow_set_rcvbuf(ssk, sk->sk_rcvbuf); } if (sock_flag(sk, SOCK_LINGER)) { -- 2.43.0