linux-kernel - [PATCH 5.10] mptcp: pm: kernel: flush: do not reset ADD

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Message-ID: <20250910-nicety-alert-0e004251@mheyne-amazon>
Date: Wed, 10 Sep 2025 09:28:37 +0000
From: "Heyne, Maximilian" <mheyne@...zon.de>
CC: "Heyne, Maximilian" <mheyne@...zon.de>, "Matthieu Baerts (NGI0)"
	<matttbe@...nel.org>, "stable@...r.kernel.org" <stable@...r.kernel.org>,
	Thomas Dreibholz <dreibh@...ula.no>, Mat Martineau <martineau@...nel.org>,
	Jakub Kicinski <kuba@...nel.org>, Mat Martineau
	<mathew.j.martineau@...ux.intel.com>, Matthieu Baerts
	<matthieu.baerts@...sares.net>, "David S. Miller" <davem@...emloft.net>,
	Paolo Abeni <pabeni@...hat.com>, "netdev@...r.kernel.org"
	<netdev@...r.kernel.org>, "mptcp@...ts.01.org" <mptcp@...ts.01.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: [PATCH 5.10] mptcp: pm: kernel: flush: do not reset ADD_ADDR limit

From: "Matthieu Baerts (NGI0)" <matttbe@...nel.org>

commit 68fc0f4b0d25692940cdc85c68e366cae63e1757 upstream.

A flush of the MPTCP endpoints should not affect the MPTCP limits. In
other words, 'ip mptcp endpoint flush' should not change 'ip mptcp
limits'.

But it was the case: the MPTCP_PM_ATTR_RCV_ADD_ADDRS (add_addr_accepted)
limit was reset by accident. Removing the reset of this counter during a
flush fixes this issue.

Fixes: 01cacb00b35c ("mptcp: add netlink-based PM")
Cc: stable@...r.kernel.org
Reported-by: Thomas Dreibholz <dreibh@...ula.no>
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/579
Reviewed-by: Mat Martineau <martineau@...nel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@...nel.org>
Link: https://patch.msgid.link/20250815-net-mptcp-misc-fixes-6-17-rc2-v1-2-521fe9957892@kernel.org
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
[adjusted patch by removing WRITE_ONCE to take into account the missing
 commit 72603d207d59 ("mptcp: use WRITE_ONCE for the pernet *_max")]
Signed-off-by: Maximilian Heyne <mheyne@...zon.de>
---
For some reason only the corresponding selftest patch was backported and
it's now failing on 5.10 kernels. I tested that with this patch the
selftest is succeeding again.
---
 net/mptcp/pm_netlink.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index 32379fc706cac..c31a1dc69f835 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -869,7 +869,6 @@ static void __flush_addrs(struct pm_nl_pernet *pernet)
 static void __reset_counters(struct pm_nl_pernet *pernet)
 {
 	pernet->add_addr_signal_max = 0;
-	pernet->add_addr_accept_max = 0;
 	pernet->local_addr_max = 0;
 	pernet->addrs = 0;
 }
-- 
2.47.3




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