FAILED: patch "[PATCH] selftests: mptcp: join: fix local endp not being tracked" failed to apply to 6.1-stable tree

The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x c5d5ecf21fdd9ce91e6116feb3aa83cee73352cc
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026020339-impart-correct-2ff7@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From c5d5ecf21fdd9ce91e6116feb3aa83cee73352cc Mon Sep 17 00:00:00 2001
From: "Matthieu Baerts (NGI0)" <[email protected]>
Date: Tue, 27 Jan 2026 20:27:27 +0100
Subject: [PATCH] selftests: mptcp: join: fix local endp not being tracked

When running this mptcp_join.sh selftest on older kernel versions not supporting local endpoints tracking, this test fails because 3 MP_JOIN ACKs have been received, while only 2 were expected.

It is not clear why only 2 MP_JOIN ACKs were expected on old kernel versions, while 3 MP_JOIN SYN and SYN+ACK were expected. When testing on the v5.15.197 kernel, 3 MP_JOIN ACKs are seen, which is also what is expected in the selftests included in this kernel version, see commit f4480eaad489 ("selftests: mptcp: add missing join check").

Switch the expected MP_JOIN ACKs to 3. While at it, move this chk_join_nr helper out of the special condition for older kernel versions as it is now the same as with more recent ones. Also, invert the condition to be more logical: what's expected on newer kernel versions having such helper first.

index 3fc29201362a..e70d3420954f 100755
@@ -2329,17 +2329,16 @@ signal_address_tests()
 		ip netns exec $ns1 sysctl -q net.mptcp.add_addr_timeout=1
 		speed=slow \
 			run_tests $ns1 $ns2 10.0.1.1
+		chk_join_nr 3 3 3
 
 		# It is not directly linked to the commit introducing this
 		# symbol but for the parent one which is linked anyway.
-		if ! mptcp_lib_kallsyms_has "mptcp_pm_subflow_check_next$"; then
-			chk_join_nr 3 3 2
-			chk_add_nr 4 4
-		else
-			chk_join_nr 3 3 3
+		if mptcp_lib_kallsyms_has "mptcp_pm_subflow_check_next$"; then
 			# the server will not signal the address terminating
 			# the MPC subflow
 			chk_add_nr 3 3
+		else
+			chk_add_nr 4 4
 		fi
 	fi
 }