[PATCH 5.10] mptcp: pm: kernel: flush: do not reset ADD_ADDR limit

From: "Matthieu Baerts (NGI0)" <matttbe@kernel.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@vger.kernel.org
Reported-by: Thomas Dreibholz <redacted>
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/579
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.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@kernel.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 <redacted>
---
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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Tamara-Danz-Str. 13
10243 Berlin
Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss
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Ust-ID: DE 365 538 597

Hi Maximilian,

On 10/09/2025 11:28, Heyne, Maximilian wrote:

From: "Matthieu Baerts (NGI0)" <matttbe@kernel.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@vger.kernel.org
Reported-by: Thomas Dreibholz <redacted>
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/579
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.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@kernel.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 <redacted>
---
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.

Thank you for this backport. It looks good to me!

Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>


I was waiting for the FAILED notification for this patch before adapting
it for v5.10, but it looks like I never got it, see:

https://lore.kernel.org/017c0cd3-7391-4d53-9e3e-ebdea5fa26da@kernel.org

No problem, that was not critical, and we now have a fix :)

Cheers,
Matt
-- 
Sponsored by the NGI0 Core fund.

Hi Max,

I'm not responsible for net/mptcp/pm_netlink.c nor can I be found in git 
blame of that file.

Why did you send this patch to me and having all the relevant persons in CC?

Best regards,
Oliver

On 10.09.25 11:28, Heyne, Maximilian wrote:

On Wed, Sep 10, 2025 at 02:33:28PM +0200, Oliver Hartkopp wrote:

Hi Max,

I'm not responsible for net/mptcp/pm_netlink.c nor can I be found in git
blame of that file.

Why did you send this patch to me and having all the relevant persons in CC?

Hi Oliver,

I don't see your email address in the CC list of my patch. Did you get
this mail via some list maybe? To be explicit, I have used the following
command to send the mail:
  
  git send-email --cc-cmd "./scripts/get_maintainer.pl --norolestats 0001-mptcp-pm-kernel-flush-do-not-reset-ADD_ADDR-limit.patch" 0001-mptcp-pm-kernel-flush-do-not-reset-ADD_ADDR-limit.patch

This uses the get_maintainer.pl from the 5.10 tree though.

Regards,
Maximilian

Best regards,
Oliver

On 10.09.25 11:28, Heyne, Maximilian wrote:

quoted

From: "Matthieu Baerts (NGI0)" <matttbe@kernel.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@vger.kernel.org
Reported-by: Thomas Dreibholz <redacted>
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/579
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.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@kernel.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 <redacted>
---
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;
  }

Amazon Web Services Development Center Germany GmbH
Tamara-Danz-Str. 13
10243 Berlin
Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss
Eingetragen am Amtsgericht Charlottenburg unter HRB 257764 B
Sitz: Berlin
Ust-ID: DE 365 538 597