This test extends "delete and re-add" to validate the previous commit:
when the endpoint linked to the initial subflow (ID 0) is re-added
multiple times, it was no longer being used, because the internal linked
counters are not decremented for this special endpoint: it is not an
additional endpoint.

Here, the "del/add id 0" steps are done 3 times to unsure this case is
validated.

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: 3ad14f54bd74 ("mptcp: more accurate MPC endpoint tracking")
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
v2:
- Re-create the ID 0 endpoint 3 times, in a loop
---
 tools/testing/selftests/net/mptcp/mptcp_join.sh | 25 ++++++++++++++-----------
 1 file changed, 14 insertions(+), 11 deletions(-)

diff --git a/tools/testing/selftests/net/mptcp/mptcp_join.sh b/tools/testing/selftests/net/mptcp/mptcp_join.sh
index 0494610694df..7867a6ab0646 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_join.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_join.sh
@@ -3684,21 +3684,24 @@ endpoint_tests()
 		chk_subflow_nr "after no reject" 3
 		chk_mptcp_info subflows 2 subflows 2
 
-		pm_nl_del_endpoint $ns2 1 10.0.1.2
-		sleep 0.5
-		chk_subflow_nr "after delete id 0" 2
-		chk_mptcp_info subflows 2 subflows 2 # only decr for additional sf
+		local i
+		for i in $(seq 3); do
+			pm_nl_del_endpoint $ns2 1 10.0.1.2
+			sleep 0.5
+			chk_subflow_nr "after delete id 0 ($i)" 2
+			chk_mptcp_info subflows 2 subflows 2 # only decr for additional sf
 
-		pm_nl_add_endpoint $ns2 10.0.1.2 id 1 dev ns2eth1 flags subflow
-		wait_mpj $ns2
-		chk_subflow_nr "after re-add id 0" 3
-		chk_mptcp_info subflows 3 subflows 3
+			pm_nl_add_endpoint $ns2 10.0.1.2 id 1 dev ns2eth1 flags subflow
+			wait_mpj $ns2
+			chk_subflow_nr "after re-add id 0 ($i)" 3
+			chk_mptcp_info subflows 3 subflows 3
+		done
 
 		mptcp_lib_kill_wait $tests_pid
 
-		join_syn_tx=5 \
-			chk_join_nr 4 4 4
-		chk_rm_nr 2 2
+		join_syn_tx=7 \
+			chk_join_nr 6 6 6
+		chk_rm_nr 4 4
 	fi
 
 	# remove and re-add

-- 
2.45.2