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 C076C21E091 for ; Sat, 11 Apr 2026 03:51:20 +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=1775879482; cv=none; b=U5VMrnD1+uCMGF2zNkxKFKj8vjzluVO7piBhiXlQD9VeUxpbLrmYFoBGWlfoBdE26tXrdBz0TIfBvSeyrJyX8Mz1UGoQWe1KiaO2FdVKzQS5514AUVv81SHm62rVgyO9d2C/qKjlo/auK4ktmixpmgSc0HPXcjQg3Z5VP1kuDU8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775879482; c=relaxed/simple; bh=zcw92UTzm5mmvfV3oN0nd40fdzf8AqDUFxmWvzsLCHc=; h=MIME-Version:Date:Content-Type:From:Message-ID:Subject:To: In-Reply-To:References; b=obPAPymq/jrX9E2X7jcEIDdtxHgOtfK1WPlHc3HcMMDJQ695KTRka2lThJ25ZA9sRpDtRfclw+bS/NM65x31I5UcvrXoSxuZL2A/e6ym3AfVQpVQQBdS1sOHzxRQJCE1MM6Ry8yhYUyLM6iCDoK34ZtuHVl8jebxNHFiHcmeb5s= 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=OROdvcC3; 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="OROdvcC3" Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1775879478; 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=2FByICIzCDiN3a+RvU5Q/aMGOVup11jitsFCoKsW8Mc=; b=OROdvcC3HnG9PBfWAGSMHltrcIDRkcCEVjhrU0VwCQCGNe0ShEGV5MGVwhS/sQetrwrMOn FHeLCGK+qCJ8RauUZ2cX9klS7n2bHgKJTU3MMdvPVe3fzoPSFWUi/ikpUPwEvnUwPJjuj1 2FN+qaZL03svhWPN63rMuuYodhUUoJA= Date: Sat, 11 Apr 2026 03:51:17 +0000 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: gang.yan@linux.dev Message-ID: TLS-Required: No Subject: Re: [PATCH mptcp-net v3 1/2] mptcp: sync the msk->sndbuf at accept() time To: "Paolo Abeni" , mptcp@lists.linux.dev In-Reply-To: <9b3a7675-cf38-4107-8c79-6ec7ccdbb2e4@redhat.com> References: <79d5862da1c7db353e27c56a26da78e6dd548659.1775551182.git.yangang@kylinos.cn> <9b3a7675-cf38-4107-8c79-6ec7ccdbb2e4@redhat.com> X-Migadu-Flow: FLOW_OUT April 10, 2026 at 5:04 PM, "Paolo Abeni" wrote: >=20 >=20On 4/7/26 10:45 AM, Gang Yan wrote: >=20 >=20>=20 >=20> From: Gang Yan > >=20=20 >=20> After an MPTCP connection is established, the sk_sndbuf of client'= s msk > > can be updated through 'subflow_finish_connect'. However, the newly > > accepted msk on the server side has a small sk_sndbuf than > > msk->first->sk_sndbuf: > >=20=20 >=20> ''' > > MPTCP: msk:00000000e55b09db, msk->sndbuf:20480, msk->first->sndbuf:2= 626560 > > ''' > >=20=20 >=20> This patch synchronizes the sk_sndbuf by triggering its update dur= ing > > accept. > >=20 >=20I finally could wrap my head around the root cause: tcp_child_process= () > -> tcp_init_transfer() -> tcp_sndbuf_expand() can and will grow the ssk > sndbuf _after_ tcp_check_req() -> subflow_syn_recv_sock() -> > mptcp_sk_clone_init() where __mptcp_propagate_sndbuf() is currently hoo= ked. >=20 >=20I think the latter __mptcp_propagate_sndbuf() invocation can be remov= ed, > and the commit message expanded to capture some of the above. >=20 >=20With the above included feel free to add: >=20 >=20Acked-by: Paolo Abeni Hi Paolo, Thanks for your suggestions. The v4 code will be sent soon. Cherrs, Gang >