diff --git a/tools/testing/selftests/net/lib.sh b/tools/testing/selftests/net/lib.sh
index 9155c914c064..915f319bcc8b 100644
--- a/tools/testing/selftests/net/lib.sh
+++ b/tools/testing/selftests/net/lib.sh
@@ -125,28 +125,36 @@ slowwait_for_counter()
 	slowwait "$timeout" until_counter_is ">= $((base + delta))" "$@"
 }
 
+remove_ns_list()
+{
+	local item=$1
+	local ns
+	local ns_list=("${NS_LIST[@]}")
+	NS_LIST=()
+
+	for ns in "${ns_list[@]}"; do
+		if [ "${ns}" != "${item}" ]; then
+			NS_LIST+=("${ns}")
+		fi
+	done
+}
+
 cleanup_ns()
 {
 	local ns=""
-	local errexit=0
 	local ret=0
 
-	# disable errexit temporary
-	if [[ $- =~ "e" ]]; then
-		errexit=1
-		set +e
-	fi
-
 	for ns in "$@"; do
 		[ -z "${ns}" ] && continue
-		ip netns delete "${ns}" &> /dev/null
+		ip netns delete "${ns}" &> /dev/null || true
 		if ! busywait $BUSYWAIT_TIMEOUT ip netns list \| grep -vq "^$ns$" &> /dev/null; then
 			echo "Warn: Failed to remove namespace $ns"
 			ret=1
+		else
+			remove_ns_list "${ns}"
 		fi
 	done
 
-	[ $errexit -eq 1 ] && set -e
 	return $ret
 }
 
@@ -159,29 +167,30 @@ cleanup_all_ns()
 # setup_ns local remote
 setup_ns()
 {
-	local ns=""
 	local ns_name=""
 	local ns_list=()
-	local ns_exist=
 	for ns_name in "$@"; do
-		# Some test may setup/remove same netns multi times
-		if unset ${ns_name} 2> /dev/null; then
-			ns="${ns_name,,}-$(mktemp -u XXXXXX)"
-			eval readonly ${ns_name}="$ns"
-			ns_exist=false
-		else
-			eval ns='$'${ns_name}
-			cleanup_ns "$ns"
-			ns_exist=true
+		# avoid conflicts with local var: internal error
+		if [ "${ns_name}" = "ns_name" ]; then
+			echo "Failed to setup namespace '${ns_name}': invalid name"
+			cleanup_ns "${ns_list[@]}"
+			exit $ksft_fail
 		fi
 
-		if ! ip netns add "$ns"; then
+		# Some test may setup/remove same netns multi times
+		if [ -z "${!ns_name}" ]; then
+			eval "${ns_name}=${ns_name,,}-$(mktemp -u XXXXXX)"
+		else
+			cleanup_ns "${!ns_name}"
+		fi
+
+		if ! ip netns add "${!ns_name}"; then
 			echo "Failed to create namespace $ns_name"
 			cleanup_ns "${ns_list[@]}"
 			return $ksft_skip
 		fi
-		ip -n "$ns" link set lo up
-		! $ns_exist && ns_list+=("$ns")
+		ip -n "${!ns_name}" link set lo up
+		ns_list+=("${!ns_name}")
 	done
 	NS_LIST+=("${ns_list[@]}")
 }
diff --git a/tools/testing/selftests/net/mptcp/mptcp_lib.sh b/tools/testing/selftests/net/mptcp/mptcp_lib.sh
index 6ffa9b7a3260..194c8fc2e55a 100644
--- a/tools/testing/selftests/net/mptcp/mptcp_lib.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_lib.sh
@@ -1,6 +1,9 @@
 #! /bin/bash
 # SPDX-License-Identifier: GPL-2.0
 
+. "$(dirname "${0}")/../lib.sh"
+. "$(dirname "${0}")/../net_helper.sh"
+
 readonly KSFT_PASS=0
 readonly KSFT_FAIL=1
 readonly KSFT_SKIP=4
@@ -361,20 +364,7 @@ mptcp_lib_check_transfer() {
 
 # $1: ns, $2: port
 mptcp_lib_wait_local_port_listen() {
-	local listener_ns="${1}"
-	local port="${2}"
-
-	local port_hex
-	port_hex="$(printf "%04X" "${port}")"
-
-	local _
-	for _ in $(seq 10); do
-		ip netns exec "${listener_ns}" cat /proc/net/tcp* | \
-			awk "BEGIN {rc=1} {if (\$2 ~ /:${port_hex}\$/ && \$4 ~ /0A/) \
-			     {rc=0; exit}} END {exit rc}" &&
-			break
-		sleep 0.1
-	done
+	wait_local_port_listen "${@}" "tcp"
 }
 
 mptcp_lib_check_output() {
@@ -438,17 +428,13 @@ mptcp_lib_check_tools() {
 }
 
 mptcp_lib_ns_init() {
-	local sec rndh
-
-	sec=$(date +%s)
-	rndh=$(printf %x "${sec}")-$(mktemp -u XXXXXX)
+	if ! setup_ns ${@}; then
+		mptcp_lib_pr_fail "Failed to setup namespace ${@}"
+		exit ${KSFT_FAIL}
+	fi
 
 	local netns
 	for netns in "${@}"; do
-		eval "${netns}=${netns}-${rndh}"
-
-		ip netns add "${!netns}" || exit ${KSFT_SKIP}
-		ip -net "${!netns}" link set lo up
 		ip netns exec "${!netns}" sysctl -q net.mptcp.enabled=1
 		ip netns exec "${!netns}" sysctl -q net.ipv4.conf.all.rp_filter=0
 		ip netns exec "${!netns}" sysctl -q net.ipv4.conf.default.rp_filter=0
@@ -456,9 +442,10 @@ mptcp_lib_ns_init() {
 }
 
 mptcp_lib_ns_exit() {
+	cleanup_ns "${@}"
+
 	local netns
 	for netns in "${@}"; do
-		ip netns del "${netns}"
 		rm -f /tmp/"${netns}".{nstat,out}
 	done
 }