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 4705435FF6C; Sat, 19 Sep 2026 20:13:08 +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=1789848789; cv=none; b=jAxj759jB8qC0H6Ees+OtIJJyZcuuT7N82qgB7bpVCIKYVgSvPjzvVzLgu1wm4m6Ph6heyOMfjzFylsIV/YdR8QJfQfF/YWEVqShGxYGdlGnNAaq00foIXVe1p+8k369zH29o7sgsMyU1ajXNNGyju074xMc1yooyRgjKQIhAfc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789848789; c=relaxed/simple; bh=1WO0zlFUIqFs0tdWGgmmVfyB4GET1GmoOqkiokHSxEk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=T+IaM+qC1EgEBHLPbfhCGYT4p1Ij0lHwOi1z3DXil3Z2WhnyusBgsLNXVc2tKQ+MG/RayZu/NHim+CaVXmaEYYaCNWrVKkfLab4OUiTvjQQ3/T8sozYt422Y1yzlRyDiBAznjbKr/KCZCBBVanHDm4de8RDZwX0GOg7Ntrk8sjA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Uo5QZ/ut; 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="Uo5QZ/ut" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 68AC21F000FF; Sat, 19 Sep 2026 20:13:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789848787; bh=xouwOPrkxaEpY908u6h7kOvFvIViEUzdFPGLnhTu4Z4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Uo5QZ/utd/AyfGw2HJJZaGPNke1/pgV0oIzf0hgBbeyjCjhmO1VKLHzDYc058CYLj EThM52aPVU8MuiADdu9rrTzgOiFvOXv5UsMDI6DzujaS/ZB9xLT+PRxkxvzU47re4D IAFwp/Q1paL0hs88PiH6TRNcq0oBa7zInG4jGOmYCRMjQcExjGtKuesyEZOE6mWCRQ g4a0T3gBoYbqDkNxj5Kk4m0nuw/KtcGWlnNLweYi5HxAX1Hc2pf4TIJytKUY6C5lgD O4yEQR91TSe74OcUawoKP04czr6zPSqSe4wxCbjEzcus1hDSSjChtM9EVAZeRhC9iN /mMEGJx+KFHQQ== From: "Matthieu Baerts (NGI0)" To: mptcp@lists.linux.dev, stable@vger.kernel.org, gregkh@linuxfoundation.org Cc: Paolo Abeni , sashal@kernel.org, Xinyang Ge , "Matthieu Baerts (NGI0)" , Jakub Kicinski Subject: [PATCH 6.1.y 2/3] mptcp: avoid unneeded actions on subflow reset Date: Sat, 19 Sep 2026 22:12:55 +0200 Message-ID: <20260919201252.2025112-7-matttbe@kernel.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260919201252.2025112-5-matttbe@kernel.org> References: <20260919201252.2025112-5-matttbe@kernel.org> Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=4385; i=matttbe@kernel.org; h=from:subject; bh=XcstLkYZhMf+PhHW4AP7Sz2v6ws0XodyjpnN+Xr9kRY=; b=owGbwMvMwCVWo/Th0Gd3rumMp9WSGLLWvTnRes7UNvizyP/GhWLCd37UHMyufnCB1yjKs9S1Q vTYgb0uHaUsDGJcDLJiiizSbZH5M59X8ZZ4+VnAzGFlAhnCwMUpABNhqmdk+KTG+VKT6wjD6f/T upn5OU/w/pMwff6CobElytTkwfFsfob/zmuYpPgPFjW2nO4+EbFba0Or+Przj3fuPX153RFlltM 6HAA= X-Developer-Key: i=matttbe@kernel.org; a=openpgp; fpr=E8CB85F76877057A6E27F77AF6B7824F4269A073 Content-Transfer-Encoding: 8bit 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-v2-1-0cf5c72667c8@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 = true" can be moved along without consequences. 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. ] Signed-off-by: Matthieu Baerts (NGI0) --- net/mptcp/protocol.c | 6 +++--- net/mptcp/protocol.h | 3 ++- net/mptcp/subflow.c | 11 +++++++++++ 3 files changed, 16 insertions(+), 4 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 2ce20884d730..ab83cf46a8c3 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -754,13 +754,13 @@ static bool __mptcp_move_skbs_from_subflow(struct mptcp_sock *msk, mptcp_dss_corruption(msk, ssk); } } else { + sk_eat_skb(ssk, skb); + done = true; + if (unlikely(!fin)) { DEBUG_NET_WARN_ON_ONCE(1); mptcp_dss_corruption(msk, ssk); } - - sk_eat_skb(ssk, skb); - done = true; } WRITE_ONCE(tp->copied_seq, seq); diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index e835028fc4e5..1de257b86839 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -492,7 +492,8 @@ 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 : 9; + resetting : 1, /* subflow is resetting */ + __unused : 8; enum mptcp_data_avail data_avail; bool pm_listener; /* a listener managed by the kernel PM? */ u32 remote_nonce; diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index 07cdb162b709..cc62681d6ea8 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -379,6 +379,10 @@ void mptcp_subflow_reset(struct sock *ssk) /* must hold: tcp_done() could drop last reference on parent */ sock_hold(sk); + subflow->resetting = 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)) @@ -1710,6 +1714,13 @@ static void subflow_state_change(struct sock *sk) __subflow_state_change(sk); + /* 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; + /* as recvmsg() does not acquire the subflow socket for ssk selection * a fin packet carrying a DSS can be unnoticed if we don't trigger * the data available machinery here. -- 2.55.0