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 5C25765192; Wed, 30 Sep 2026 18:11:31 +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=1790791892; cv=none; b=PBPX54Kh3pPCLDJ1HPKMZ4SVuN7j/eGI9gXoUPe+bKFuW6Sw7WOMeKf7uBYeGqMBsL6WcQ5AD1KcpRA7LLZv9Y2bhESSEp5hI7Km4yFPOhBFTGgmbXuJtUL++P/aULn4531Ucwuf7AEtMk/4pUhd6xem54aod0eNLfNRQ4bhyk8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790791892; c=relaxed/simple; bh=yCmUa0wmg7EAP880rdt5tl2piGuCaoq4fwZHn6W58ZE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=exn1bdQ8aVR1878vWDPrAhMX6+yX7A2vYUvU9PuckJoxg/MVTvT5JLyrhBe6lHxXnM9X9kW/DAvAPr0K9Ns1hOuE7N/99v/ayENEpudn17GhG0VNY8uIh5FULUha33KLxsN3h5AD1VJkczBc9VuwcS5UoQzVntMza4eQnpcH5Yk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=zfhwQ1ID; 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="zfhwQ1ID" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B4F751F000FF; Wed, 30 Sep 2026 18:11:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790791891; bh=sSHoQUq6LVuXI30LujM3FM987YGxqEbC+BHIDG2pTkE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=zfhwQ1IDPauIU7XDlrJi5tqwoGgaL37YhQzvw9UMhQwaDPwVt05jzxp1N1J6Hf1X1 XMn+nhGS64fu1Qx4H0su/J2fnP6WVx96ycmMOtQV2/PEeZgbNwJI2JzurQiz4SVErq mfgyosRExDt8hFcasRZ0sAoWTdXVHaQwREYXDI+I= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Xinyang Ge , Paolo Abeni , "Matthieu Baerts (NGI0)" , Jakub Kicinski Subject: [PATCH 5.15 418/752] mptcp: avoid unneeded actions on subflow reset Date: Wed, 30 Sep 2026 17:24:48 +0200 Message-ID: <20260930152407.327072502@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152358.131179731@linuxfoundation.org> References: <20260930152358.131179731@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ 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, 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 = true; + + if (unlikely(!fin)) + mptcp_dss_corruption(msk, ssk); } 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); + 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)) @@ -1667,6 +1671,13 @@ static void subflow_state_change(struct __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; + msk = mptcp_sk(parent); if (subflow_simultaneous_connect(sk)) { mptcp_propagate_sndbuf(parent, sk);