selftests: net: fdb_notify: Add a test for FDB notifications

Check that only one notification is produced for various FDB edit
operations.

Regarding the ip_link_add() and ip_link_master() helpers. This pattern of
action plus corresponding defer is bound to come up often, and a dedicated
vocabulary to capture it will be handy. tunnel_create() and vlan_create()
from forwarding/lib.sh are somewhat opaque and perhaps too kitchen-sinky,
so I tried to go in the opposite direction with these ones, and wrapped
only the bare minimum to schedule a corresponding cleanup.

Signed-off-by: Petr Machata <[e-mail]>
Reviewed-by: Amit Cohen <[e-mail]>
Acked-by: Shuah Khan <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

tools/testing/selftests/net/Makefile

···
 TEST_PROGS += test_bridge_neigh_suppress.sh
 TEST_PROGS += test_vxlan_nolocalbypass.sh
 TEST_PROGS += test_bridge_backup_port.sh
-TEST_PROGS += fdb_flush.sh
+TEST_PROGS += fdb_flush.sh fdb_notify.sh
 TEST_PROGS += fq_band_pktlimit.sh
 TEST_PROGS += vlan_hw_filter.sh
 TEST_PROGS += bpf_offload.py

tools/testing/selftests/net/fdb_notify.sh

···
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+source lib.sh
+
+ALL_TESTS="
+	test_dup_bridge
+	test_dup_vxlan_self
+	test_dup_vxlan_master
+	test_dup_macvlan_self
+	test_dup_macvlan_master
+"
+
+do_test_dup()
+{
+	local op=$1; shift
+	local what=$1; shift
+	local tmpf
+
+	RET=0
+
+	tmpf=$(mktemp)
+	defer rm "$tmpf"
+
+	defer_scope_push
+		bridge monitor fdb &> "$tmpf" &
+		defer kill_process $!
+
+		sleep 0.5
+		bridge fdb "$op" 00:11:22:33:44:55 vlan 1 "$@"
+		sleep 0.5
+	defer_scope_pop
+
+	local count=$(grep -c -e 00:11:22:33:44:55 $tmpf)
+	((count == 1))
+	check_err $? "Got $count notifications, expected 1"
+
+	log_test "$what $op: Duplicate notifications"
+}
+
+test_dup_bridge()
+{
+	ip_link_add br up type bridge vlan_filtering 1
+	do_test_dup add "bridge" dev br self
+	do_test_dup del "bridge" dev br self
+}
+
+test_dup_vxlan_self()
+{
+	ip_link_add br up type bridge vlan_filtering 1
+	ip_link_add vx up type vxlan id 2000 dstport 4789
+	ip_link_master vx br
+
+	do_test_dup add "vxlan" dev vx self dst 192.0.2.1
+	do_test_dup del "vxlan" dev vx self dst 192.0.2.1
+}
+
+test_dup_vxlan_master()
+{
+	ip_link_add br up type bridge vlan_filtering 1
+	ip_link_add vx up type vxlan id 2000 dstport 4789
+	ip_link_master vx br
+
+	do_test_dup add "vxlan master" dev vx master
+	do_test_dup del "vxlan master" dev vx master
+}
+
+test_dup_macvlan_self()
+{
+	ip_link_add dd up type dummy
+	ip_link_add mv up link dd type macvlan mode passthru
+
+	do_test_dup add "macvlan self" dev mv self
+	do_test_dup del "macvlan self" dev mv self
+}
+
+test_dup_macvlan_master()
+{
+	ip_link_add br up type bridge vlan_filtering 1
+	ip_link_add dd up type dummy
+	ip_link_add mv up link dd type macvlan mode passthru
+	ip_link_master mv br
+
+	do_test_dup add "macvlan master" dev mv self
+	do_test_dup del "macvlan master" dev mv self
+}
+
+cleanup()
+{
+	defer_scopes_cleanup
+}
+
+trap cleanup EXIT
+tests_run
+
+exit $EXIT_STATUS

tools/testing/selftests/net/lib.sh

···
 	# Suppress noise from killing the process.
 	{ kill $pid && wait $pid; } 2>/dev/null
 }
+
+ip_link_add()
+{
+	local name=$1; shift
+
+	ip link add name "$name" "$@"
+	defer ip link del dev "$name"
+}
+
+ip_link_master()
+{
+	local member=$1; shift
+	local master=$1; shift
+
+	ip link set dev "$member" master "$master"
+	defer ip link set dev "$member" nomaster
+}