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 301FC3D47A0; Wed, 30 Sep 2026 19:17:39 +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=1790795860; cv=none; b=kIbm9h2+qyTLDt6IaUtbCtd//QPn7Qftqu+NPP+E6O0LuXyIQrafXpmKqpzDebS6vKmmOHAo/tyqI1X3RWjQpQo8FJKjHX1sjahuak90syzw/uABqQnqR7+M30AQ53y2NsBuC0LRnDsdi3sSTjAHdQmgd8SpC4dgcS9dhmLVDhI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790795860; c=relaxed/simple; bh=QkZGKEYYchWg8r3Dq+YESo22oHvnim6q70z3U/gkAQc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=WYxeIYv1MGdT+4bAcz8ManKhn35D3LyUPCHkWxGvtNduVbvYTThE6aEwwStezufBLLQZVaV+D6Wv7SYaZTBh6qrzU4/0Vunjq09Xj1RTAAIZtTekT3f6nUo9ff+gdrKGewHWtVCCtHLpchHk8xmfZyTD/o1zU/r7Pnzd9Ls6kOQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=j6uojv+T; 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="j6uojv+T" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7464A1F000FF; Wed, 30 Sep 2026 19:17:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790795859; bh=C7IyPRL3xztcNkmCAb5hqkN8NwqL9LuNOan6GwYQugA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=j6uojv+TgwiqVcZV9X8p2+FincgdjjtlGjdJ+BPTSlj1nX/7rzG96E+wDhZN9wYuO 7/1PrAdlHkYrnXSpjJnvEgDugMzq1mim5Y3chlYeiZvqhIakm6k2RDWL11B87CACjY Ms63SPtrPg25DVh1nbFS7SWihzlJ5jXLjYSaoW9s= 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 6.6 0707/1193] mptcp: avoid unneeded actions on subflow reset Date: Wed, 30 Sep 2026 17:23:11 +0200 Message-ID: <20260930152449.957804532@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152434.301151190@linuxfoundation.org> References: <20260930152434.301151190@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 6.6-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 a conflict in protocol.h, because __unused is at a different number. Decrement the one from this version and add the new flag above.] 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 @@ -747,13 +747,13 @@ static bool __mptcp_move_skbs_from_subfl 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); --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -510,7 +510,8 @@ struct mptcp_subflow_context { valid_csum_seen : 1, /* at least one csum validated */ is_mptfo : 1, /* subflow is doing TFO */ close_event_done : 1, /* has done the post-closed part */ - __unused : 8; + resetting : 1, /* subflow is resetting */ + __unused : 7; bool data_avail; bool scheduled; bool pm_listener; /* a listener managed by the kernel PM? */ --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -421,6 +421,10 @@ 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)) @@ -1802,6 +1806,13 @@ 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; + /* 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.