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 E08C2220F37 for ; Sun, 26 Oct 2025 14:33:45 +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=1761489226; cv=none; b=FB0xX2AABE3ZbcPa0TW1V+2bwQPMKdipwFX0qiGGbEFjKcufjbe6MYvP+xUMrcv9mf2Eoh3X4XPcLTltNa77zWrgWCEtkAtvS6Gj4tX1v6kEtkqeECe7H7Ok39RFpVkd+NznMcfvIfuHrzltSbgnrf5PSOf0LW5xqYbJhDSDNbc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761489226; c=relaxed/simple; bh=nMtnF+BNERIjRFIUqXRKMLmP7zaofELPSnqU6c+MKF0=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=ANWJ5ELeKCERT/b245v81+FXcJt/bzs/FdftfD1Wbt405m94gVJ/LG/ZbJDddobadH5co5eBPw3W6wJehJ/KhFs1jG4w+jmAkQk2b2YgPosiTo/ArYfM3JWXgYPEu7kY8BRgdsKvf71kInnbumXM6PrF1jV71pYnWlrhKE9b0JQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=bxTc3VvR; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="bxTc3VvR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 58D74C4CEE7; Sun, 26 Oct 2025 14:33:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1761489225; bh=nMtnF+BNERIjRFIUqXRKMLmP7zaofELPSnqU6c+MKF0=; h=Subject:To:Cc:From:Date:From; b=bxTc3VvRolOcT6s5C1mtBn2tmZIrUy3Ql07fxr1VrT/D2dzMfhBokrxp+Uwd99jkG bPUm5kWm7j2J4Qmbt2SBJfmai5bcvSEO3vF7mJ2fu7AwGs+RoE7N+WedBgiUBIUpor gHhlrtGTTD4NiwNdiv2VtJS3SjcWnogi2O54zb14= Subject: FAILED: patch "[PATCH] mptcp: pm: in-kernel: C-flag: handle late ADD_ADDR" failed to apply to 6.1-stable tree To: matttbe@kernel.org,geliang@kernel.org,kuba@kernel.org Cc: From: Date: Sun, 26 Oct 2025 15:33:42 +0100 Message-ID: <2025102642-improper-revered-93ac@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x e84cb860ac3ce67ec6ecc364433fd5b412c448bc # git commit -s git send-email --to '' --in-reply-to '2025102642-improper-revered-93ac@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From e84cb860ac3ce67ec6ecc364433fd5b412c448bc Mon Sep 17 00:00:00 2001 From: "Matthieu Baerts (NGI0)" Date: Mon, 20 Oct 2025 22:53:26 +0200 Subject: [PATCH] mptcp: pm: in-kernel: C-flag: handle late ADD_ADDR The special C-flag case expects the ADD_ADDR to be received when switching to 'fully-established'. But for various reasons, the ADD_ADDR could be sent after the "4th ACK", and the special case doesn't work. On NIPA, the new test validating this special case for the C-flag failed a few times, e.g. 102 default limits, server deny join id 0 syn rx [FAIL] got 0 JOIN[s] syn rx expected 2 Server ns stats (...) MPTcpExtAddAddrTx 1 MPTcpExtEchoAdd 1 Client ns stats (...) MPTcpExtAddAddr 1 MPTcpExtEchoAddTx 1 synack rx [FAIL] got 0 JOIN[s] synack rx expected 2 ack rx [FAIL] got 0 JOIN[s] ack rx expected 2 join Rx [FAIL] see above syn tx [FAIL] got 0 JOIN[s] syn tx expected 2 join Tx [FAIL] see above I had a suspicion about what the issue could be: the ADD_ADDR might have been received after the switch to the 'fully-established' state. The issue was not easy to reproduce. The packet capture shown that the ADD_ADDR can indeed be sent with a delay, and the client would not try to establish subflows to it as expected. A simple fix is not to mark the endpoints as 'used' in the C-flag case, when looking at creating subflows to the remote initial IP address and port. In this case, there is no need to try. Note: newly added fullmesh endpoints will still continue to be used as expected, thanks to the conditions behind mptcp_pm_add_addr_c_flag_case. Fixes: 4b1ff850e0c1 ("mptcp: pm: in-kernel: usable client side with C-flag") Cc: stable@vger.kernel.org Reviewed-by: Geliang Tang Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20251020-net-mptcp-c-flag-late-add-addr-v1-1-8207030cb0e8@kernel.org Signed-off-by: Jakub Kicinski diff --git a/net/mptcp/pm_kernel.c b/net/mptcp/pm_kernel.c index e0f44dc232aa..2ae95476dba3 100644 --- a/net/mptcp/pm_kernel.c +++ b/net/mptcp/pm_kernel.c @@ -370,6 +370,10 @@ static void mptcp_pm_create_subflow_or_signal_addr(struct mptcp_sock *msk) } subflow: + /* No need to try establishing subflows to remote id0 if not allowed */ + if (mptcp_pm_add_addr_c_flag_case(msk)) + goto exit; + /* check if should create a new subflow */ while (msk->pm.local_addr_used < endp_subflow_max && msk->pm.extra_subflows < limit_extra_subflows) { @@ -401,6 +405,8 @@ static void mptcp_pm_create_subflow_or_signal_addr(struct mptcp_sock *msk) __mptcp_subflow_connect(sk, &local, &addrs[i]); spin_lock_bh(&msk->pm.lock); } + +exit: mptcp_pm_nl_check_work_pending(msk); }