This is a simple ipvtap test to test handling
IP-address add/remove on ipvlan interface.

It creates a veth-interface and then creates several
network-namespace with ipvlan0 interface in it linked to veth.

Then it starts to add/remove addresses on ipvlan0 interfaces
in several threads.

At finish, it checks that there is no duplicated addresses.

Signed-off-by: Dmitry Skorodumov <skorodumov.dmitry@huawei.com>
---
v4:
  - Removed unneeded modprobe
  - Number of threads is 8, if KSFT_MACHINE_SLOW==yes.
    It is needed, since on debug-build test may take more than 15 minutes.
  - Now veth is created in own namespace
  - Added comment about why test adds/removes random ip

 tools/testing/selftests/net/Makefile       |   1 +
 tools/testing/selftests/net/config         |   2 +
 tools/testing/selftests/net/ipvtap_test.sh | 166 +++++++++++++++++++++
 3 files changed, 169 insertions(+)
 create mode 100755 tools/testing/selftests/net/ipvtap_test.sh

diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile
index b66ba04f19d9..45c4ea381bc3 100644
--- a/tools/testing/selftests/net/Makefile
+++ b/tools/testing/selftests/net/Makefile
@@ -48,6 +48,7 @@ TEST_PROGS := \
 	ipv6_flowlabel.sh \
 	ipv6_force_forwarding.sh \
 	ipv6_route_update_soft_lockup.sh \
+	ipvtap_test.sh \
 	l2_tos_ttl_inherit.sh \
 	l2tp.sh \
 	link_netns.py \
diff --git a/tools/testing/selftests/net/config b/tools/testing/selftests/net/config
index 1e1f253118f5..5702ab8fa5ad 100644
--- a/tools/testing/selftests/net/config
+++ b/tools/testing/selftests/net/config
@@ -48,6 +48,7 @@ CONFIG_IPV6_SEG6_LWTUNNEL=y
 CONFIG_IPV6_SIT=y
 CONFIG_IPV6_VTI=y
 CONFIG_IPVLAN=m
+CONFIG_IPVTAP=m
 CONFIG_KALLSYMS=y
 CONFIG_L2TP=m
 CONFIG_L2TP_ETH=m
@@ -122,6 +123,7 @@ CONFIG_TEST_BPF=m
 CONFIG_TLS=m
 CONFIG_TRACEPOINTS=y
 CONFIG_TUN=y
+CONFIG_TAP=m
 CONFIG_USER_NS=y
 CONFIG_VETH=y
 CONFIG_VLAN_8021Q=y
diff --git a/tools/testing/selftests/net/ipvtap_test.sh b/tools/testing/selftests/net/ipvtap_test.sh
new file mode 100755
index 000000000000..b4e18fc7ada0
--- /dev/null
+++ b/tools/testing/selftests/net/ipvtap_test.sh
@@ -0,0 +1,167 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# Simple tests for ipvtap
+
+
+#
+# The testing environment looks this way:
+#
+# |------HNS-------|     |------PHY-------|
+# |      veth<----------------->veth      |
+# |------|--|------|     |----------------|
+#        |  |
+#        |  |            |-----TST0-------|
+#        |  |------------|----ipvlan      |
+#        |               |----------------|
+#        |
+#        |               |-----TST1-------|
+#        |---------------|----ipvlan      |
+#                        |----------------|
+#
+
+ALL_TESTS="
+	test_ip_set
+"
+
+source lib.sh
+
+DEBUG=0
+
+VETH_HOST=vethtst.h
+VETH_PHY=vethtst.p
+
+NS_COUNT=32
+IP_ITERATIONS=1024
+[ "$KSFT_MACHINE_SLOW" = "yes" ] && NS_COUNT=8
+
+ns_run() {
+	ns=$1
+	shift
+	if [[ "$ns" == "global" ]]; then
+		"$@" >/dev/null
+	else
+		ip netns exec "$ns" "$@" >/dev/null
+	fi
+}
+
+test_ip_setup_env() {
+	setup_ns NS_PHY
+	setup_ns HST_NS
+
+	# setup simulated other-host (phy) and host itself
+	ns_run "$HST_NS" ip link add $VETH_HOST type veth peer name $VETH_PHY \
+		netns "$NS_PHY" >/dev/null
+	ns_run "$HST_NS" ip link set $VETH_HOST up
+	ns_run "$NS_PHY" ip link set $VETH_PHY up
+
+	for ((i=0; i<NS_COUNT; i++)); do
+		setup_ns ipvlan_ns_$i
+		ns="ipvlan_ns_$i"
+		if [ "$DEBUG" = "1" ]; then
+			echo "created NS ${!ns}"
+		fi
+		if ! ns_run "$HST_NS" ip link add netns ${!ns} ipvlan0 \
+		    link $VETH_HOST \
+		    type ipvtap mode l2 bridge; then
+			exit_error "FAIL: Failed to configure ipvlan link."
+		fi
+	done
+}
+
+test_ip_cleanup_env() {
+	ns_run "$HST_NS" ip link del $VETH_HOST
+	cleanup_all_ns
+}
+
+exit_error() {
+	echo "$1"
+	exit $ksft_fail
+}
+
+rnd() {
+	echo $(( RANDOM % 32 + 16 ))
+}
+
+test_ip_set_thread() {
+	# Here we are trying to create some IP conflicts between namespaces.
+	# If just add/remove IP, nothing interesting will happen.
+	# But if add random IP and then remove random IP,
+	# eventually conflicts start to apear.
+	ip link set ipvlan0 up
+	for ((i=0; i<IP_ITERATIONS; i++)); do
+		v=$(rnd)
+		ip a a "172.25.0.$v/24" dev ipvlan0 2>/dev/null
+		ip a a "fc00::$v/64" dev ipvlan0 2>/dev/null
+		v=$(rnd)
+		ip a d "172.25.0.$v/24" dev ipvlan0 2>/dev/null
+		ip a d "fc00::$v/64" dev ipvlan0 2>/dev/null
+	done
+}
+
+test_ip_set() {
+	RET=0
+
+	trap test_ip_cleanup_env EXIT
+
+	test_ip_setup_env
+
+	declare -A ns_pids
+	for ((i=0; i<NS_COUNT; i++)); do
+		ns="ipvlan_ns_$i"
+		ns_run ${!ns} bash -c "$0 test_ip_set_thread"&
+		ns_pids[$i]=$!
+	done
+
+	for ((i=0; i<NS_COUNT; i++)); do
+		wait "${ns_pids[$i]}"
+	done
+
+	declare -A all_ips
+	for ((i=0; i<NS_COUNT; i++)); do
+		ns="ipvlan_ns_$i"
+		ip_output=$(ip netns exec ${!ns} ip a l dev ipvlan0 | grep inet)
+		while IFS= read -r nsip_out; do
+			if [[ -z $nsip_out ]]; then
+				continue;
+			fi
+			nsip=$(awk '{print $2}' <<< "$nsip_out")
+			if [[ -v all_ips[$nsip] ]]; then
+				RET=$ksft_fail
+				log_test "conflict for $nsip"
+				return "$RET"
+			else
+				all_ips[$nsip]=$i
+			fi
+		done <<< "$ip_output"
+	done
+
+	if [ "$DEBUG" = "1" ]; then
+		for key in "${!all_ips[@]}"; do
+			echo "$key: ${all_ips[$key]}"
+		done
+	fi
+
+	trap - EXIT
+	test_ip_cleanup_env
+
+	log_test "test multithreaded ip set"
+}
+
+if [[ "$1" == "-d" ]]; then
+	DEBUG=1
+	shift
+fi
+
+if [[ "$1" == "-t" ]]; then
+	shift
+	TESTS="$*"
+fi
+
+if [[ "$1" == "test_ip_set_thread" ]]; then
+	test_ip_set_thread
+else
+	require_command ip
+
+	tests_run
+fi
-- 
2.43.0