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 EC0F721E097; Sat, 19 Sep 2026 19:46:10 +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=1789847172; cv=none; b=KdluIKafQaXRaBQ3gY6Y9rDIanBnYjbNmH4DGM6fOC8H6WCgNLfuU8kaCBDg1IfA3526KLUaaVtgXhyhFuesErH1od8Doq1QaJMu3k2bwNMDnsXD1x2FtNOR3vfBtemPrq2TUbB1YtukOSFfz0afrCseyrbknv2ifesZnEapeEQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789847172; c=relaxed/simple; bh=4nnvDODdQjHmfFhi/J35q4Ra6AqjS+EY1v/fdX73R8c=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=VDTRDx5IPuDizf7I8SmJ+vZ1UNESTAAWemEF5dBXtc62aMWOksIS+TM3qT7UEZmHlwGGxo9hqL4OzCdBDalBNxhUGv6KapnzD4PfiOhHvrkYLm6usdfEFKRtgNHdPQTq+R7z0nvAwGOL6el3bRCMK0QwLLSkFl8wIExnvNMTS2g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=VfSwt6RJ; 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="VfSwt6RJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 383871F000FF; Sat, 19 Sep 2026 19:46:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789847170; bh=VzL2RXag44aswm6H0CNJet9Iyu0WotGU/SiDa/pmvYo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=VfSwt6RJyN+M4JTcmiI/VDW5JWc/hjvsZn62fBxHsLB+F3imWeeXZk6LECaO30kFb 0U/+mDtb2o23in4kIHxO1SVPO3PQdjjlIFhorCVIUCPgrsl6Tjfp4DPTVAZdkky2w5 Y0OLh5osJpl1cyC0MGNHhUZP5O5ScOhwk7+Gl9iBmYIPW67hl1pYi2MZRpYBeMTz99 wLe0ZGpD2UJ8pfRBRCcmcMnitfmhWQc1ZAJpTiVsk+pufXtHyZenfpA11Jl4PQpyxq 7zQ5WKhINIEFEik8bfxb3aU2sZ5FOrDHPkku40NNU7CHxloIPces8IwD/uvHR75XHj OvXGc4RsVnpTw== 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 6.18.y 2/4] mptcp: avoid unneeded actions on subflow reset Date: Sat, 19 Sep 2026 21:39:51 +0200 Message-ID: <20260919193948.1927666-8-matttbe@kernel.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260919193948.1927666-6-matttbe@kernel.org> References: <20260919193948.1927666-6-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=3752; i=matttbe@kernel.org; h=from:subject; bh=TwEXo4sAWu8C2MWECnaVnk45GCdRUe7jQDtgvf6QFhA=; b=owGbwMvMwCVWo/Th0Gd3rumMp9WSGLLWPeUokGPiPCn+s9nz0KnQDZ/39SXP7ussn+Jz4v7JF UIscVV3OkpZGMS4GGTFFFmk2yLzZz6v4i3x8rOAmcPKBDKEgYtTACbi+4qR4a7jA4/yqRld06fU sLdbvZQu3HNn3450nzZe1TuxQXpB5YwMH3kzqirrzrl/uipynz1gg2btB8Oe3PnhEsdT+R3Un/J xAgA= 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 Signed-off-by: Matthieu Baerts (NGI0) --- net/mptcp/protocol.c | 4 ++-- net/mptcp/protocol.h | 3 ++- net/mptcp/subflow.c | 11 +++++++++++ 3 files changed, 15 insertions(+), 3 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index a9d8f63d3b2a..dee5fd3787b5 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -727,12 +727,12 @@ static bool __mptcp_move_skbs_from_subflow(struct mptcp_sock *msk, mptcp_dss_corruption(msk, ssk); } } else { + sk_eat_skb(ssk, skb); + if (unlikely(!fin)) { DEBUG_NET_WARN_ON_ONCE(1); mptcp_dss_corruption(msk, ssk); } - - sk_eat_skb(ssk, skb); } WRITE_ONCE(tp->copied_seq, seq); diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index 68f7c67d5f49..dc8920a6a90c 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -545,7 +545,8 @@ struct mptcp_subflow_context { is_mptfo : 1, /* subflow is doing TFO */ close_event_done : 1, /* has done the post-closed part */ mpc_drop : 1, /* the MPC option has been dropped in a rtx */ - __unused : 9; + resetting : 1, /* subflow is resetting */ + __unused : 8; bool data_avail; bool scheduled; bool pm_listener; /* a listener managed by the kernel PM? */ diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index 96794baac3e1..1932fcf9f925 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -441,6 +441,10 @@ 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); mptcp_send_active_reset_reason(ssk); tcp_done(ssk); if (!test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &mptcp_sk(sk)->flags)) @@ -1864,6 +1868,13 @@ 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