From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 1FC153D75D2 for ; Mon, 9 Mar 2026 15:24:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773069864; cv=none; b=U8V3RdNq6YEhnxb+6gB+0O/FWnyOHskLBqJS2lsxkv0Ag/cgMYXvSK3ESgeSHFFioQsILSNbjrouuhAj85Aq3hTYStv0UZytOevN92n9hVQvdQwY8pXUlX7ysK7wOXfT9Lao5Npdto9q+/ohXMuZCSF6maTWGtxD7o4NckNV+Og= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773069864; c=relaxed/simple; bh=DpC95LEZ3PbFopiij8oraOckRlN1070hXVE25r0nDno=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=B3/09x08r9RgpemrjQW0H/1GKkC8grNe1QTMTQ1YO35S8c4btFYwfvo/Sj01iPVZLqZ2C4dyLhiXC9y+WPvAo/1uXgALwfV1RQeUY5QSim7h8Ozd6W9LvNEUc1H/ke6axsAwiJXIk/vW8l4gUrr2iWFbqEaE0kWTmY5POU3S9s0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=nPMdMG6u; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="nPMdMG6u" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0F8ECC4CEF7; Mon, 9 Mar 2026 15:24:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773069863; bh=DpC95LEZ3PbFopiij8oraOckRlN1070hXVE25r0nDno=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nPMdMG6u8xWaCiSaW+MFOd3241WxkDYn4932WkjxrukMU2HLJ94COkNiOg1PlQfaf O5Q2jFTnE1XvwPtA5dyH6S6xXw0gxPN71KiL6z/N1N9Fcroy4WjV6qOiTMecTE7lBw xbkWuZ5w0xD+506llGnq3L3x8C4lkMZoPLGEs8ZhayXgNOdvbq/uXibpp9Qdx5k1oJ vha/NySDmdIcBi7OmDbehMrpw6wp0BuEMEyTT3D4Zw3xkWfHNKUQycf5sJjI2JnJgY 2b2Qjlr6BdIJQ04b3WzxuDo/jOEWl5igOIjHswT96uqJSD5smpv213psDcLg+Gf0kI j4UOozFuri3Ug== From: Sasha Levin To: stable@vger.kernel.org Cc: "Matthieu Baerts (NGI0)" , Frank Lorenz , Mat Martineau , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.1.y] mptcp: pm: avoid sending RM_ADDR over same subflow Date: Mon, 9 Mar 2026 11:24:20 -0400 Message-ID: <20260309152420.1280295-1-sashal@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <2026030906-bullish-enjoying-edba@gregkh> References: <2026030906-bullish-enjoying-edba@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: "Matthieu Baerts (NGI0)" [ Upstream commit fb8d0bccb221080630efcd9660c9f9349e53cc9e ] RM_ADDR are sent over an active subflow, the first one in the subflows list. There is then a high chance the initial subflow is picked. With the in-kernel PM, when an endpoint is removed, a RM_ADDR is sent, then linked subflows are closed. This is done for each active MPTCP connection. MPTCP endpoints are likely removed because the attached network is no longer available or usable. In this case, it is better to avoid sending this RM_ADDR over the subflow that is going to be removed, but prefer sending it over another active and non stale subflow, if any. This modification avoids situations where the other end is not notified when a subflow is no longer usable: typically when the endpoint linked to the initial subflow is removed, especially on the server side. Fixes: 8dd5efb1f91b ("mptcp: send ack for rm_addr") Cc: stable@vger.kernel.org Reported-by: Frank Lorenz Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/612 Reviewed-by: Mat Martineau Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20260303-net-mptcp-misc-fixes-7-0-rc2-v1-2-4b5462b6f016@kernel.org Signed-off-by: Jakub Kicinski [ adapted to _nl-prefixed function names in pm_netlink.c and omitted stale subflow fallback ] Signed-off-by: Sasha Levin --- net/mptcp/pm.c | 2 +- net/mptcp/pm_netlink.c | 43 +++++++++++++++++++++++++++++++++++++----- net/mptcp/protocol.h | 2 ++ 3 files changed, 41 insertions(+), 6 deletions(-) diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c index f1a8ae7a5af4f..c5131529e1587 100644 --- a/net/mptcp/pm.c +++ b/net/mptcp/pm.c @@ -55,7 +55,7 @@ int mptcp_pm_remove_addr(struct mptcp_sock *msk, const struct mptcp_rm_list *rm_ msk->pm.rm_list_tx = *rm_list; rm_addr |= BIT(MPTCP_RM_ADDR_SIGNAL); WRITE_ONCE(msk->pm.addr_signal, rm_addr); - mptcp_pm_nl_addr_send_ack(msk); + mptcp_pm_nl_addr_send_ack_avoid_list(msk, rm_list); return 0; } diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c index 293ec3448f52c..f3b1e9f685898 100644 --- a/net/mptcp/pm_netlink.c +++ b/net/mptcp/pm_netlink.c @@ -850,9 +850,23 @@ bool mptcp_pm_nl_is_init_remote_addr(struct mptcp_sock *msk, return mptcp_addresses_equal(&mpc_remote, remote, remote->port); } -void mptcp_pm_nl_addr_send_ack(struct mptcp_sock *msk) +static bool subflow_in_rm_list(const struct mptcp_subflow_context *subflow, + const struct mptcp_rm_list *rm_list) { - struct mptcp_subflow_context *subflow; + u8 i, id = subflow_get_local_id(subflow); + + for (i = 0; i < rm_list->nr; i++) { + if (rm_list->ids[i] == id) + return true; + } + + return false; +} + +void mptcp_pm_nl_addr_send_ack_avoid_list(struct mptcp_sock *msk, + const struct mptcp_rm_list *rm_list) +{ + struct mptcp_subflow_context *subflow, *same_id = NULL; msk_owned_by_me(msk); lockdep_assert_held(&msk->pm.lock); @@ -862,11 +876,30 @@ void mptcp_pm_nl_addr_send_ack(struct mptcp_sock *msk) return; mptcp_for_each_subflow(msk, subflow) { - if (__mptcp_subflow_active(subflow)) { - mptcp_pm_send_ack(msk, subflow, false, false); - break; + if (!__mptcp_subflow_active(subflow)) + continue; + + if (unlikely(rm_list && + subflow_in_rm_list(subflow, rm_list))) { + if (!same_id) + same_id = subflow; + } else { + goto send_ack; } } + + if (same_id) + subflow = same_id; + else + return; + +send_ack: + mptcp_pm_send_ack(msk, subflow, false, false); +} + +void mptcp_pm_nl_addr_send_ack(struct mptcp_sock *msk) +{ + mptcp_pm_nl_addr_send_ack_avoid_list(msk, NULL); } int mptcp_pm_nl_mp_prio_send_ack(struct mptcp_sock *msk, diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index dd5070d57d740..329071f6b9e17 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -818,6 +818,8 @@ void mptcp_pm_add_addr_send_ack(struct mptcp_sock *msk); bool mptcp_pm_nl_is_init_remote_addr(struct mptcp_sock *msk, const struct mptcp_addr_info *remote); void mptcp_pm_nl_addr_send_ack(struct mptcp_sock *msk); +void mptcp_pm_nl_addr_send_ack_avoid_list(struct mptcp_sock *msk, + const struct mptcp_rm_list *rm_list); void mptcp_pm_rm_addr_received(struct mptcp_sock *msk, const struct mptcp_rm_list *rm_list); void mptcp_pm_mp_prio_received(struct sock *sk, u8 bkup); -- 2.51.0