When pm_netlink.sh is executed with '-i', 'ip mptcp' is used instead of
'pm_nl_ctl'. IPRoute2 doesn't support the 'unknown' flag, which has only
been added to 'pm_nl_ctl' for this specific check: to ensure that the
kernel ignores such unsupported flag.

No reason to add this flag to 'ip mptcp'. Then, this check should be
skipped when 'ip mptcp' is used.

Fixes: 29f4801e9c8d ("selftests: mptcp: pm: ensure unknown flags are ignored")
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
 tools/testing/selftests/net/mptcp/pm_netlink.sh | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/net/mptcp/pm_netlink.sh b/tools/testing/selftests/net/mptcp/pm_netlink.sh
index 123d9d7a0278..d844ee687a29 100755
--- a/tools/testing/selftests/net/mptcp/pm_netlink.sh
+++ b/tools/testing/selftests/net/mptcp/pm_netlink.sh
@@ -192,9 +192,13 @@ check "show_endpoints" \
 flush_endpoint
 check "show_endpoints" "" "flush addrs"
 
-add_endpoint 10.0.1.1 flags unknown
-check "show_endpoints" "$(format_endpoints "1,10.0.1.1")" "ignore unknown flags"
-flush_endpoint
+# "unknown" flag is only supported by pm_nl_ctl
+if ! mptcp_lib_is_ip_mptcp; then
+	add_endpoint 10.0.1.1 flags unknown
+	check "show_endpoints" "$(format_endpoints "1,10.0.1.1")" \
+	      "ignore unknown flags"
+	flush_endpoint
+fi
 
 set_limits 9 1 2>/dev/null
 check "get_limits" "${default_limits}" "rcv addrs above hard limit"

-- 
2.53.0