From nobody Fri Sep 25 10:03:26 2026 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 B19E332B13E; Sun, 20 Sep 2026 07:39:42 +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=1789889984; cv=none; b=d8s8PwOhWB/WNRghyf6YnttGGwPgFhQnZfa0fKsEx5cvd0XjsKZOeUehKTFRPmEalYEPWj4NKMD4ZNesa+BuZ6N1CBq/xA6dfl5XnoJTii5XFEvGXwZjz47am5XLH7KmlvxMJU6oWywGoQGRwHZwB1SxRDS2l9DSoC1ClewcY5U= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789889984; c=relaxed/simple; bh=BqjzRFHwfU8ciKhSx2/9BTZ2rzxOHDkYAfxkoTCv38U=; h=Subject:To:Cc:From:Date:In-Reply-To:Message-ID:MIME-Version: Content-Type; b=QEbJZCPVdjDYECjjNB5H1JH7NuzUy9BCsJ305KBfxuaue1sOX5Zy0YMvv3/Bb8OXIDp+7HSY3BrkkvZFCHVi9Ec2vZbgFwDEByzMHSSxJhEsyY0b2Iq6BYT9vlitI/dglwwvooP+wA+n/cqKQLpNhIII3vxdRkrcGAdcUBZB0Ak= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=I38Wo65r; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="I38Wo65r" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CCA5A1F000FF; Sun, 20 Sep 2026 07:39:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789889982; bh=SNOiDOy6sS18SW6ZAKPmtd/xf/XKmMm/99VMx6RgOhg=; h=Subject:To:Cc:From:Date:In-Reply-To; b=I38Wo65rLf18IwYJGdaNCk03TUCL42r81DQW9ERj+ZaujSfZ299tuKmHZsIg3fzcR HISgBVzdu5OHuEAWLBc/LZS9fHvxpwOm5t/eL5bqwsQlIqmTuMWAqSbQiaRiHKZ96W s00509c/nYuh7qLtxFz5ARYI5ixOBw5r2d7NFegs= Subject: Patch "mptcp: avoid unneeded actions on subflow reset" has been added to the 5.15-stable tree To: gregkh@linuxfoundation.org,kuba@kernel.org,matttbe@kernel.org,mptcp@lists.linux.dev,pabeni@redhat.com,sashal@kernel.org,xinyang@anthropic.com Cc: From: Date: Sun, 20 Sep 2026 09:36:32 +0200 In-Reply-To: <20260919202918.2074632-5-matttbe@kernel.org> Message-ID: <2026092032-serve-virtual-7788@gregkh> Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-stable: commit X-Patchwork-Hint: ignore Content-Type: text/plain; charset="utf-8" This is a note to let you know that I've just added the patch titled mptcp: avoid unneeded actions on subflow reset to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=3Dlinux/kernel/git/stable/stable-queue.git= ;a=3Dsummary The filename of the patch is: mptcp-avoid-unneeded-actions-on-subflow-reset.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. From stable+bounces-338612-greg=3Dkroah.com@vger.kernel.org Sat Sep 19 22:2= 9:39 2026 From: "Matthieu Baerts (NGI0)" Date: Sat, 19 Sep 2026 22:29:20 +0200 Subject: mptcp: avoid unneeded actions on subflow reset To: mptcp@lists.linux.dev, stable@vger.kernel.org, gregkh@linuxfoundation.o= rg Cc: Paolo Abeni , sashal@kernel.org, Xinyang Ge , "Matthieu Baerts (NGI0)" , Jakub Kicin= ski Message-ID: <20260919202918.2074632-5-matttbe@kernel.org> From: Paolo Abeni commit 2b0f561f21b27c40c91ea4975268a06092bd7e9c upstream. Once in a blue moon, the mptcp receive path can recursively call mptcp_data_ready() via state change under unlucky error conditions, and then try to hold the data lock again. Break the recursion loop explicitly checking for the exceptional condition. Add a new flag instead of using an existing one like 'closing', to exit early in subflow_state_change(), and explicitly flush the RX queue at reset time. This avoids unneeded processing to check for available data -- calling get_mapping_status() and more on a dying subflow -- but also in error reporting and worker scheduling. Note that we must consume the currently peeked skb before invoking mptcp_dss_corruption to avoid consuming it again after the eventual reset has freed it. Fixes: e32d262c89e2 ("mptcp: handle consistently DSS corruption") Cc: stable@vger.kernel.org Reported-by: Xinyang Ge Signed-off-by: Paolo Abeni Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20260917-net-mptcp-misc-fixes-7-3-rc4-v2-1-0= cf5c72667c8@kernel.org Signed-off-by: Jakub Kicinski [ Note: conflict in protocol.c, because commit e0ca4057e0ec ("mptcp: micro-optimize __mptcp_move_skb()") is not in this version, and is part of a consequent rx path refactor. The conflict is in the context, and is easy to resolve, "done =3D true" can be moved along without consequences. Also, the context is slightly different because there is no DEBUG_NET_WARN_ON_ONCE in this version, see the backport commit 12c1676d598e ("mptcp: handle consistently DSS corruption"). Also a conflict in protocol.h, because __unused is at a different number. Decrement the one from this version and add the new flag above. The context is also a bit different with data_avail being an enum, but that's without consequences here. Also a conflict in subflow.c, because commit 71154bbe4942 ("mptcp: fallback earlier on simult connection") was not needed in this version, and cause conflicts in the context, but that's without consequences here. ] Signed-off-by: Matthieu Baerts (NGI0) Signed-off-by: Greg Kroah-Hartman --- net/mptcp/protocol.c | 6 +++--- net/mptcp/protocol.h | 3 ++- net/mptcp/subflow.c | 11 +++++++++++ 3 files changed, 16 insertions(+), 4 deletions(-) --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -687,11 +687,11 @@ static bool __mptcp_move_skbs_from_subfl if (unlikely(map_remaining < len)) mptcp_dss_corruption(msk, ssk); } else { - if (unlikely(!fin)) - mptcp_dss_corruption(msk, ssk); - sk_eat_skb(ssk, skb); done =3D true; + + if (unlikely(!fin)) + mptcp_dss_corruption(msk, ssk); } =20 WRITE_ONCE(tp->copied_seq, seq); --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -447,7 +447,8 @@ struct mptcp_subflow_context { stale : 1, /* unable to snd/rcv data, do not use for xmit */ valid_csum_seen : 1, /* at least one csum validated */ close_event_done : 1, /* has done the post-closed part */ - __unused : 11; + resetting : 1, /* subflow is resetting */ + __unused : 10; enum mptcp_data_avail data_avail; bool pm_listener; /* a listener managed by the kernel PM? */ u32 remote_nonce; --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -373,6 +373,10 @@ void mptcp_subflow_reset(struct sock *ss /* must hold: tcp_done() could drop last reference on parent */ sock_hold(sk); =20 + subflow->resetting =3D 1; + + /* No need to delay the actual close for to-be discarded data. */ + __skb_queue_purge(&ssk->sk_receive_queue); tcp_send_active_reset(ssk, GFP_ATOMIC); tcp_done(ssk); if (!test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &mptcp_sk(sk)->flags)) @@ -1667,6 +1671,13 @@ static void subflow_state_change(struct =20 __subflow_state_change(sk); =20 + /* Rx queue processing is unneeded, error reporting will take place at + * __mptcp_close_ssk() time and subflow reset can't happen in case of + * fallback: subflow_sched_work_if_closed() would be a no-op. + */ + if (subflow->resetting) + return; + msk =3D mptcp_sk(parent); if (subflow_simultaneous_connect(sk)) { mptcp_propagate_sndbuf(parent, sk); Patches currently in stable-queue which might be from matttbe@kernel.org are queue-5.15/mptcp-syncookies-remember-the-request-backup-flag.patch queue-5.15/mptcp-close-race-between-scheduler-and-state-change.patch queue-5.15/mptcp-avoid-unneeded-actions-on-subflow-reset.patch queue-5.15/mptcp-options-handle-mpc-data-csum-reqd-no-csum.patch