[PATCH 5.15.y 0/2] mptcp: fix recent failed backports (20250822)

[PATCH 5.15.y 0/2] mptcp: fix recent failed backports (20250822)

[Matthieu Baerts (NGI0)]

Greg recently reported the following patches could not be applied
without conflicts in this tree:

 - f5ce0714623c ("mptcp: disable add_addr retransmission when timeout is 0")
 - 452690be7de2 ("selftests: mptcp: pm: check flush doesn't reset limits")

Conflicts have been resolved, and documented in each patch.

Geliang Tang (1):
  mptcp: disable add_addr retransmission when timeout is 0

Matthieu Baerts (NGI0) (1):
  selftests: mptcp: pm: check flush doesn't reset limits

 Documentation/networking/mptcp-sysctl.rst       |  2 ++
 net/mptcp/pm_netlink.c                          | 13 ++++++++++---
 tools/testing/selftests/net/mptcp/pm_netlink.sh |  1 +
 3 files changed, 13 insertions(+), 3 deletions(-)

-- 
2.50.0

[PATCH 5.15.y 1/2] mptcp: disable add_addr retransmission when timeout is 0

[Matthieu Baerts (NGI0)]

From: Geliang Tang <tanggeliang@kylinos.cn>

commit f5ce0714623cffd00bf2a83e890d09c609b7f50a upstream.

When add_addr_timeout was set to 0, this caused the ADD_ADDR to be
retransmitted immediately, which looks like a buggy behaviour. Instead,
interpret 0 as "no retransmissions needed".

The documentation is updated to explicitly state that setting the timeout
to 0 disables retransmission.

Fixes: 93f323b9cccc ("mptcp: add a new sysctl add_addr_timeout")
Cc: stable@vger.kernel.org
Suggested-by: Matthieu Baerts <matttbe@kernel.org>
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20250815-net-mptcp-misc-fixes-6-17-rc2-v1-5-521fe9957892@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
[ Before commit e4c28e3d5c09 ("mptcp: pm: move generic PM helpers to
  pm.c"), mptcp_pm_alloc_anno_list() was in pm_netlink.c. The same patch
  can be applied there with one small conflict, because the upstream
  parent commit, adding one label in the context, is not needed in this
  version. ]
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
 Documentation/networking/mptcp-sysctl.rst |  2 ++
 net/mptcp/pm_netlink.c                    | 13 ++++++++++---
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/Documentation/networking/mptcp-sysctl.rst b/Documentation/networking/mptcp-sysctl.rst
index b0d4da71e68e..e72ebaa14004 100644
--- a/Documentation/networking/mptcp-sysctl.rst
+++ b/Documentation/networking/mptcp-sysctl.rst
@@ -20,6 +20,8 @@ add_addr_timeout - INTEGER (seconds)
 	resent to an MPTCP peer that has not acknowledged a previous
 	ADD_ADDR message.
 
+	Do not retransmit if set to 0.
+
 	The default value matches TCP_RTO_MAX. This is a per-namespace
 	sysctl.
 
diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index 7d32b4c4ed93..f9839980fcaf 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -316,6 +316,7 @@ static void mptcp_pm_add_timer(struct timer_list *timer)
 	struct mptcp_pm_add_entry *entry = from_timer(entry, timer, add_timer);
 	struct mptcp_sock *msk = entry->sock;
 	struct sock *sk = (struct sock *)msk;
+	unsigned int timeout;
 
 	pr_debug("msk=%p\n", msk);
 
@@ -333,6 +334,10 @@ static void mptcp_pm_add_timer(struct timer_list *timer)
 		goto out;
 	}
 
+	timeout = mptcp_get_add_addr_timeout(sock_net(sk));
+	if (!timeout)
+		goto out;
+
 	spin_lock_bh(&msk->pm.lock);
 
 	if (!mptcp_pm_should_add_signal_addr(msk)) {
@@ -344,7 +349,7 @@ static void mptcp_pm_add_timer(struct timer_list *timer)
 
 	if (entry->retrans_times < ADD_ADDR_RETRANS_MAX)
 		sk_reset_timer(sk, timer,
-			       jiffies + mptcp_get_add_addr_timeout(sock_net(sk)));
+			       jiffies + timeout);
 
 	spin_unlock_bh(&msk->pm.lock);
 
@@ -386,6 +391,7 @@ static bool mptcp_pm_alloc_anno_list(struct mptcp_sock *msk,
 	struct mptcp_pm_add_entry *add_entry = NULL;
 	struct sock *sk = (struct sock *)msk;
 	struct net *net = sock_net(sk);
+	unsigned int timeout;
 
 	lockdep_assert_held(&msk->pm.lock);
 
@@ -403,8 +409,9 @@ static bool mptcp_pm_alloc_anno_list(struct mptcp_sock *msk,
 	add_entry->retrans_times = 0;
 
 	timer_setup(&add_entry->add_timer, mptcp_pm_add_timer, 0);
-	sk_reset_timer(sk, &add_entry->add_timer,
-		       jiffies + mptcp_get_add_addr_timeout(net));
+	timeout = mptcp_get_add_addr_timeout(net);
+	if (timeout)
+		sk_reset_timer(sk, &add_entry->add_timer, jiffies + timeout);
 
 	return true;
 }
-- 
2.50.0

[PATCH 5.15.y 2/2] selftests: mptcp: pm: check flush doesn't reset limits

[Matthieu Baerts (NGI0)]

commit 452690be7de2f91cc0de68cb9e95252875b33503 upstream.

This modification is linked to the parent commit where the received
ADD_ADDR limit was accidentally reset when the endpoints were flushed.

To validate that, the test is now flushing endpoints after having set
new limits, and before checking them.

The 'Fixes' tag here below is the same as the one from the previous
commit: this patch here is not fixing anything wrong in the selftests,
but it validates the previous fix for an issue introduced by this commit
ID.

Fixes: 01cacb00b35c ("mptcp: add netlink-based PM")
Cc: stable@vger.kernel.org
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-v1-3-521fe9957892@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
[ Conflicts in pm_netlink.sh, because some refactoring have been done
  later on: commit 3188309c8ceb ("selftests: mptcp: netlink:
  add 'limits' helpers") and commit c99d57d0007a ("selftests: mptcp: use
  pm_nl endpoint ops") are not in this version. The same operation can
  still be done at the same place, without using the new helper. ]
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
 tools/testing/selftests/net/mptcp/pm_netlink.sh | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/testing/selftests/net/mptcp/pm_netlink.sh b/tools/testing/selftests/net/mptcp/pm_netlink.sh
index 306372b1526a..68e05bd3526e 100755
--- a/tools/testing/selftests/net/mptcp/pm_netlink.sh
+++ b/tools/testing/selftests/net/mptcp/pm_netlink.sh
@@ -131,6 +131,7 @@ ip netns exec $ns1 ./pm_nl_ctl limits 1 9
 check "ip netns exec $ns1 ./pm_nl_ctl limits" "$default_limits" "subflows above hard limit"
 
 ip netns exec $ns1 ./pm_nl_ctl limits 8 8
+ip netns exec $ns1 ./pm_nl_ctl flush
 check "ip netns exec $ns1 ./pm_nl_ctl limits" "accept 8
 subflows 8" "set limits"
 
-- 
2.50.0