selftests: forwarding: mirror_gre_vlan_bridge_1q: Fix untagged test

The untagged egress test sets up mirroring to {,ip6}gretap such that the
underlay goes through a bridge. Then VLAN flags are manipulated to test
that the traffic leaves the bridge 802.1q-tagged or not, as appropriate.

However, when a neighbor expires at the time that the bridge VLAN is
configured as PVID and egress untagged, the following discovery process
can't finish, because the IP address on H3 is still at the VLAN-tagged
netdevice. This manifests by occasional failures where only several of
the 10 required packets get through.

Therefore, when reconfiguring the VLAN flags, move the IP address to the
appropriate device in the H3 VRF.

In addition to that, take this opportunity to embed an ASCII art diagram
to make the topology move obvious.
Signed-off-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/net/forwarding/mirror_gre_vlan_bridge_1q.sh

 #!/bin/bash
 # SPDX-License-Identifier: GPL-2.0
 
-# This test uses standard topology for testing gretap. See
-# mirror_gre_topo_lib.sh for more details.
-#
 # Test for "tc action mirred egress mirror" when the underlay route points at a
 # vlan device on top of a bridge device with vlan filtering (802.1q).
+#
+#   +---------------------+                             +---------------------+
+#   | H1                  |                             |                  H2 |
+#   |     + $h1           |                             |           $h2 +     |
+#   |     | 192.0.2.1/28  |                             |  192.0.2.2/28 |     |
+#   +-----|---------------+                             +---------------|-----+
+#         |                                                             |
+#   +-----|-------------------------------------------------------------|-----+
+#   | SW  o--> mirred egress mirror dev {gt4,gt6}                       |     |
+#   |     |                                                             |     |
+#   | +---|-------------------------------------------------------------|---+ |
+#   | |   + $swp1                    br1                          $swp2 +   | |
+#   | |                                                                     | |
+#   | |   + $swp3                                                           | |
+#   | +---|-----------------------------------------------------------------+ |
+#   |     |                        |                                          |
+#   |     |                        + br1.555                                  |
+#   |     |                          192.0.2.130/28                           |
+#   |     |                          2001:db8:2::2/64                         |
+#   |     |                                                                   |
+#   |     |                     + gt6 (ip6gretap)      + gt4 (gretap)         |
+#   |     |                     : loc=2001:db8:2::1    : loc=192.0.2.129      |
+#   |     |                     : rem=2001:db8:2::2    : rem=192.0.2.130      |
+#   |     |                     : ttl=100              : ttl=100              |
+#   |     |                     : tos=inherit          : tos=inherit          |
+#   |     |                     :                      :                      |
+#   +-----|---------------------:----------------------:----------------------+
+#         |                     :                      :
+#   +-----|---------------------:----------------------:----------------------+
+#   | H3  + $h3                 + h3-gt6 (ip6gretap)   + h3-gt4 (gretap)      |
+#   |     |                       loc=2001:db8:2::2      loc=192.0.2.130      |
+#   |     + $h3.555               rem=2001:db8:2::1      rem=192.0.2.129      |
+#   |       192.0.2.130/28        ttl=100                ttl=100              |
+#   |       2001:db8:2::2/64      tos=inherit            tos=inherit          |
+#   |                                                                         |
+#   +-------------------------------------------------------------------------+
 
 ALL_TESTS="
 	test_gretap
@@ -30,6 +63,15 @@ source mirror_gre_topo_lib.sh
 
 require_command $ARPING
 
+h3_addr_add_del()
+{
+	local add_del=$1; shift
+	local dev=$1; shift
+
+	ip addr $add_del dev $dev 192.0.2.130/28
+	ip addr $add_del dev $dev 2001:db8:2::2/64
+}
+
 setup_prepare()
 {
 	h1=${NETIFS[p1]}
@@ -55,7 +97,8 @@ setup_prepare()
 	ip route rep 192.0.2.130/32 dev br1.555
 	ip -6 route rep 2001:db8:2::2/128 dev br1.555
 
-	vlan_create $h3 555 v$h3 192.0.2.130/28 2001:db8:2::2/64
+	vlan_create $h3 555 v$h3
+	h3_addr_add_del add $h3.555
 
 	ip link set dev $swp3 master br1
 	bridge vlan add dev $swp3 vid 555
@@ -68,6 +111,8 @@ cleanup()
 
 	ip link set dev $swp2 nomaster
 	ip link set dev $swp3 nomaster
+
+	h3_addr_add_del del $h3.555
 	vlan_destroy $h3 555
 	vlan_destroy br1 555
 
@@ -182,13 +227,19 @@ test_span_gre_untagged_egress()
 	quick_test_span_gre_dir $tundev ingress
 	quick_test_span_vlan_dir $h3 555 ingress
 
+	h3_addr_add_del del $h3.555
 	bridge vlan add dev $swp3 vid 555 pvid untagged
-	sleep 1
+	h3_addr_add_del add $h3
+	sleep 5
+
 	quick_test_span_gre_dir $tundev ingress
 	fail_test_span_vlan_dir $h3 555 ingress
 
+	h3_addr_add_del del $h3
 	bridge vlan add dev $swp3 vid 555
-	sleep 1
+	h3_addr_add_del add $h3.555
+	sleep 5
+
 	quick_test_span_gre_dir $tundev ingress
 	quick_test_span_vlan_dir $h3 555 ingress