From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 4B91B823DD; Thu, 12 Mar 2026 11:01:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773313292; cv=none; b=Fh4EwCRoTl1XLCS4JbS6L8Wz66U1+lPqr5cltyLJ8n5WOYJBl/UTFEZZ9Q3MQJWIGQAq2AHZ2Xnbnm22k/+8uQ6aVALbDwDSIs3WhTzSUEEyuLcRZjM3k75m/h83LL/4RexAtAMtZZj7Ex3ZM8ftjXJpWjw5ZXQ0myaw8OW9V1A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773313292; c=relaxed/simple; bh=+Ulv+PCYekiAEop42YtuVmuhDO5Wmf5GGZG23pHYKps=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=SEcJF27GIEhBbEk1m4R2vjVQjXkNCrfLd6MRMF+nVAaE4l6bNcdQeqnT2R3yqdLzMO1cKnytbxQ+3f4bCKWanmH7zbLbfmIvTmpupZcN2bWE4NJGy3F6nCJj2Y9XGK3RrIBnEWseAEaSFmUf8E1t0Yr5ODM3FjZGDNuZR/JarAw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=p+SGG5FR; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="p+SGG5FR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 591C6C4CEF7; Thu, 12 Mar 2026 11:01:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773313291; bh=+Ulv+PCYekiAEop42YtuVmuhDO5Wmf5GGZG23pHYKps=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=p+SGG5FRxlZ4uxcoqLLyxtMOuhYboEMc3iKZe+NZ8LRsukrNgN6+d6B5uyGWLC71y 6fTSEq9NXVq3wpguq2DWqJbiAEl+bm3Jb6GCwCngidmv9YWRzV4yTyfBYE1t84CUrT dL+kXjY7gaKtBULPEUKubNEGW+tXF8GwO8s/fHtvRyORxb0E9ASZGbnAuAQa1CRKZ5 MTaMHrNlASOYf8pr6ZITrsyx9OBXcSzOdoD/ex/srzXYQi/TRepcLBm6QBZKS6erBv AjyZpp2Jx7u79jhe5J5Nav83z/FZxx8qk1Nxz9AT7lz/s3u/pzZxETib+jNHEZt9eg HtCi9k+LloE1w== Message-ID: Date: Thu, 12 Mar 2026 12:01:21 +0100 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Beta Subject: Re: [PATCH net-next v3 2/6] mptcp: keep rcv_mwnd_seq in sync with subflow rcv_wnd Content-Language: fr To: Simon Baatz Cc: netdev@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, mptcp@lists.linux.dev, Eric Dumazet , Neal Cardwell , Kuniyuki Iwashima , "David S. Miller" , Jakub Kicinski , Paolo Abeni , Simon Horman , Jonathan Corbet , Shuah Khan , David Ahern , Jon Maloy , Jason Xing , mfreemon@cloudflare.com, Shuah Khan , Stefano Brivio , Mat Martineau , Geliang Tang References: <20260309-tcp_rfc7323_retract_wnd_rfc-v3-0-4c7f96b1ec69@gmail.com> <20260309-tcp_rfc7323_retract_wnd_rfc-v3-2-4c7f96b1ec69@gmail.com> <334053df-9824-4bfe-b37c-8711d0a5a9bd@kernel.org> From: Matthieu Baerts Autocrypt: addr=matttbe@kernel.org; keydata= xsFNBFXj+ekBEADxVr99p2guPcqHFeI/JcFxls6KibzyZD5TQTyfuYlzEp7C7A9swoK5iCvf YBNdx5Xl74NLSgx6y/1NiMQGuKeu+2BmtnkiGxBNanfXcnl4L4Lzz+iXBvvbtCbynnnqDDqU c7SPFMpMesgpcu1xFt0F6bcxE+0ojRtSCZ5HDElKlHJNYtD1uwY4UYVGWUGCF/+cY1YLmtfb WdNb/SFo+Mp0HItfBC12qtDIXYvbfNUGVnA5jXeWMEyYhSNktLnpDL2gBUCsdbkov5VjiOX7 CRTkX0UgNWRjyFZwThaZADEvAOo12M5uSBk7h07yJ97gqvBtcx45IsJwfUJE4hy8qZqsA62A nTRflBvp647IXAiCcwWsEgE5AXKwA3aL6dcpVR17JXJ6nwHHnslVi8WesiqzUI9sbO/hXeXw TDSB+YhErbNOxvHqCzZEnGAAFf6ges26fRVyuU119AzO40sjdLV0l6LE7GshddyazWZf0iac nEhX9NKxGnuhMu5SXmo2poIQttJuYAvTVUNwQVEx/0yY5xmiuyqvXa+XT7NKJkOZSiAPlNt6 VffjgOP62S7M9wDShUghN3F7CPOrrRsOHWO/l6I/qJdUMW+MHSFYPfYiFXoLUZyPvNVCYSgs 3oQaFhHapq1f345XBtfG3fOYp1K2wTXd4ThFraTLl8PHxCn4ywARAQABzSRNYXR0aGlldSBC YWVydHMgPG1hdHR0YmVAa2VybmVsLm9yZz7CwZEEEwEIADsCGwMFCwkIBwIGFQoJCAsCBBYC AwECHgECF4AWIQToy4X3aHcFem4n93r2t4JPQmmgcwUCZUDpDAIZAQAKCRD2t4JPQmmgcz33 EACjROM3nj9FGclR5AlyPUbAq/txEX7E0EFQCDtdLPrjBcLAoaYJIQUV8IDCcPjZMJy2ADp7 /zSwYba2rE2C9vRgjXZJNt21mySvKnnkPbNQGkNRl3TZAinO1Ddq3fp2c/GmYaW1NWFSfOmw MvB5CJaN0UK5l0/drnaA6Hxsu62V5UnpvxWgexqDuo0wfpEeP1PEqMNzyiVPvJ8bJxgM8qoC cpXLp1Rq/jq7pbUycY8GeYw2j+FVZJHlhL0w0Zm9CFHThHxRAm1tsIPc+oTorx7haXP+nN0J iqBXVAxLK2KxrHtMygim50xk2QpUotWYfZpRRv8dMygEPIB3f1Vi5JMwP4M47NZNdpqVkHrm jvcNuLfDgf/vqUvuXs2eA2/BkIHcOuAAbsvreX1WX1rTHmx5ud3OhsWQQRVL2rt+0p1DpROI 3Ob8F78W5rKr4HYvjX2Inpy3WahAm7FzUY184OyfPO/2zadKCqg8n01mWA9PXxs84bFEV2mP VzC5j6K8U3RNA6cb9bpE5bzXut6T2gxj6j+7TsgMQFhbyH/tZgpDjWvAiPZHb3sV29t8XaOF BwzqiI2AEkiWMySiHwCCMsIH9WUH7r7vpwROko89Tk+InpEbiphPjd7qAkyJ+tNIEWd1+MlX ZPtOaFLVHhLQ3PLFLkrU3+Yi3tXqpvLE3gO3LM7BTQRV4/npARAA5+u/Sx1n9anIqcgHpA7l 5SUCP1e/qF7n5DK8LiM10gYglgY0XHOBi0S7vHppH8hrtpizx+7t5DBdPJgVtR6SilyK0/mp 9nWHDhc9rwU3KmHYgFFsnX58eEmZxz2qsIY8juFor5r7kpcM5dRR9aB+HjlOOJJgyDxcJTwM 1ey4L/79P72wuXRhMibN14SX6TZzf+/XIOrM6TsULVJEIv1+NdczQbs6pBTpEK/G2apME7vf mjTsZU26Ezn+LDMX16lHTmIJi7Hlh7eifCGGM+g/AlDV6aWKFS+sBbwy+YoS0Zc3Yz8zrdbi Kzn3kbKd+99//mysSVsHaekQYyVvO0KD2KPKBs1S/ImrBb6XecqxGy/y/3HWHdngGEY2v2IP Qox7mAPznyKyXEfG+0rrVseZSEssKmY01IsgwwbmN9ZcqUKYNhjv67WMX7tNwiVbSrGLZoqf Xlgw4aAdnIMQyTW8nE6hH/Iwqay4S2str4HZtWwyWLitk7N+e+vxuK5qto4AxtB7VdimvKUs x6kQO5F3YWcC3vCXCgPwyV8133+fIR2L81R1L1q3swaEuh95vWj6iskxeNWSTyFAVKYYVskG V+OTtB71P1XCnb6AJCW9cKpC25+zxQqD2Zy0dK3u2RuKErajKBa/YWzuSaKAOkneFxG3LJIv Hl7iqPF+JDCjB5sAEQEAAcLBXwQYAQIACQUCVeP56QIbDAAKCRD2t4JPQmmgc5VnD/9YgbCr HR1FbMbm7td54UrYvZV/i7m3dIQNXK2e+Cbv5PXf19ce3XluaE+wA8D+vnIW5mbAAiojt3Mb 6p0WJS3QzbObzHNgAp3zy/L4lXwc6WW5vnpWAzqXFHP8D9PTpqvBALbXqL06smP47JqbyQxj Xf7D2rrPeIqbYmVY9da1KzMOVf3gReazYa89zZSdVkMojfWsbq05zwYU+SCWS3NiyF6QghbW voxbFwX1i/0xRwJiX9NNbRj1huVKQuS4W7rbWA87TrVQPXUAdkyd7FRYICNW+0gddysIwPoa KrLfx3Ba6Rpx0JznbrVOtXlihjl4KV8mtOPjYDY9u+8x412xXnlGl6AC4HLu2F3ECkamY4G6 UxejX+E6vW6Xe4n7H+rEX5UFgPRdYkS1TA/X3nMen9bouxNsvIJv7C6adZmMHqu/2azX7S7I vrxxySzOw9GxjoVTuzWMKWpDGP8n71IFeOot8JuPZtJ8omz+DZel+WCNZMVdVNLPOd5frqOv mpz0VhFAlNTjU1Vy0CnuxX3AM51J8dpdNyG0S8rADh6C8AKCDOfUstpq28/6oTaQv7QZdge0 JY6dglzGKnCi/zsmp2+1w559frz4+IC7j/igvJGX4KDDKUs0mlld8J2u2sBXv7CGxdzQoHaz lzVbFe7fduHbABmYz9cefQpO7wDE/Q== Organization: NGI0 Core In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Simon, On 11/03/2026 23:08, Simon Baatz wrote: > On Wed, Mar 11, 2026 at 07:27:34PM +0100, Matthieu Baerts wrote: >> On 09/03/2026 09:02, Simon Baatz via B4 Relay wrote: >>> From: Simon Baatz >>> >>> MPTCP shares a receive window across subflows and applies it at the >>> subflow level by adjusting each subflow's rcv_wnd when needed. With >>> the new TCP tracking of the maximum advertised window sequence, >>> rcv_mwnd_seq must stay consistent with these subflow-level rcv_wnd >>> adjustments. >> >> Thank you for these modifications! >> >>> Signed-off-by: Simon Baatz >>> --- >>> net/mptcp/options.c | 6 ++++-- >>> 1 file changed, 4 insertions(+), 2 deletions(-) >>> >>> diff --git a/net/mptcp/options.c b/net/mptcp/options.c >>> index 43df4293f58bfbd8a8df6bf24b9f15e0f9e238f6..8a1c5698983cff3082d68290626dd8f1e044527f 100644 >>> --- a/net/mptcp/options.c >>> +++ b/net/mptcp/options.c >> >> (...) >> >>> @@ -1338,8 +1339,9 @@ static void mptcp_set_rwin(struct tcp_sock *tp, struct tcphdr *th) >>> */ >>> rcv_wnd_new = rcv_wnd_old; >>> win = rcv_wnd_old - ack_seq; >>> - tp->rcv_wnd = min_t(u64, win, U32_MAX); >>> - new_win = tp->rcv_wnd; >>> + new_win = min_t(u64, win, U32_MAX); >>> + tp->rcv_wnd = new_win; >> >> Out of curiosity, why did you change the two lines above? >> (even if it makes sense, the diff is a bit confusing, and the commit >> message doesn't mention this :) ) > > I wanted to keep tcp_update_max_rcv_wnd_seq() calls close to the > respective update sites (same pattern everywhere). Thanks, I now understand the reason. > In the original form > > tp->rcv_wnd = min_t(u64, win, U32_MAX); > tcp_update_max_rcv_wnd_seq(tp); > new_win = tp->rcv_wnd; > > the ordering suggests that tcp_update_max_rcv_wnd_seq() might modify > tp->rcv_wnd. Note that if tp->rcv_mwnd_seq always needs to be modified when tp->rcv_wnd and/or tp->rcv_wup are modified, maybe a single helper could be called to modify all of them, so it might be less likely to forget about modifying tp->rcv_mwnd_seq as well in the future. But probably it might be unlikely to have new places where tp->rcv_wnd and/or tp->rcv_wup need to be modified like here with MPTCP. So probably fine like that. Cheers, Matt -- Sponsored by the NGI0 Core fund.