From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 CCB45823DE for ; Mon, 1 Jun 2026 00:50:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780275039; cv=none; b=m+kpcAvkCd//2EWXIAgUD3z6ODebkWIkDcHtxSqhH+tgfbAtRiDavLiJQT47BlXu8hMBiYFrvdmy+/f2dTbqHSV1ZPZ/yz1KChGKbRx3v3mEx7lgruegCKfQQNZnFJe78phQt33VgT+UkM6l8WStDURP6ulYspkaIjhPQOGEgKk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780275039; c=relaxed/simple; bh=ALab0YfEDuB+7HmfWwC6YGIS3uf5Xr3n8uaQy4Ys1hg=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=EnzE5SAfhKhZgpZmMHfALqFStXlW4qCwlqeBqbNn9wboqMg7EDRVXl8TdLsbGozTMDFqPp/miWytL1WS1yxvQ8Lxrok6L6LALEDdjAWR848JnWAN5dmyRQg+BMCEyWLksEopKkAAvD1zoYMBCyWA56jhlB6/ndDuHPsBhz6BEU4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GMjZScGD; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="GMjZScGD" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CFC381F00893; Mon, 1 Jun 2026 00:50:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780275038; bh=JociplAlb0brmADuK6eAzOunhaiDYOcLqW2/nxIZUGg=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=GMjZScGDyj3haL7ksPp8Xkh+FGxUzBb59CEplRbRqlHrXJoLBjx68TQHq9+yoEADJ FY5uiJKwlzQ76PulNLOqPq59ptUXwzK22XfbQ9RhAvGVtxAGK6rGaxzc3tMOReXepV 85tbgW2IsN0JkJjIAJLhg9wr4SvjJYlgyuijzLb1tXsEexoXZsaA1cume1fBAnDpTa WVXHC9zzqlHxlG+t1LpDgbS/nnym+jG2XrG6ibWujd/0sNtmKsW66u5VnMJFNGV/rj qjjnXXf50O2RF21yksFEND/S56s1q4FKKhN8XJBdv5kGlptd5vffZoSUiCCsi8SAQI NI+WmxD46DS6g== Message-ID: Date: Mon, 1 Jun 2026 10:50:33 +1000 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Beta Subject: Re: [PATCH 7.0.y] mptcp: update window_clamp on subflows when SO_RCVBUF is set Content-Language: fr To: Sasha Levin Cc: Gang Yan , Paolo Abeni , stable@vger.kernel.org References: <2026052819-liberty-cramp-97fe@gregkh> <20260601003905.84041-1-sashal@kernel.org> From: Matthieu Baerts Autocrypt: addr=matttbe@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Sasha, On 01/06/2026 10:39, Sasha Levin wrote: > From: Gang Yan > > [ Upstream commit 3a543ae0e2092d5c2085d5f21f7a7dbafdffea3c ] > > Add __mptcp_subflow_set_rcvbuf() helper to write the subflow sk_rcvbuf, > but also to call the recently added tcp_set_rcvbuf() helper to update > window_clamp. This is needed because the window clap is updated when > scaling_ratio changes, in tcp_measure_rcv_mss(). Until scaling_ratio > changes, the subflow is stuck with the old window clamp which may be > based on a small initial buffer. > > Use this new helper in both mptcp_sol_socket_sync_intval() (setsockopt > path) and sync_socket_options() (new subflow creation path). > > Note that this patch depends on commit b025461303d8 ("tcp: update > window_clamp when SO_RCVBUF is set"): it fixes the issue on TCP side, > but the same fix is needed on MPTCP side as well. Thank you for the backport. I guess there is a conflict, because commit b025461303d8 ("tcp: update window_clamp when SO_RCVBUF is set") has not been backported to 7.0 (nor 6.18, 6.12 and 6.6). See the note above for more details. In other words, MPTCP is imitating TCP's behaviour. So no need to backport this patch if the fix on TCP side is not backported either. I think it would be better to take both the TCP fix (b025461303d8), and this one (3a543ae0e209). But maybe the TCP fix has not been backported on purpose? Cheers, Matt -- Sponsored by the NGI0 Core fund.