selftests: forwarding: Add an skbedit priority selftest

Add a test that runs traffic through a port such that skbedit priority
action acts on it during forwarding. Test that at egress, it is classified
correctly according to the new priority at a PRIO qdisc.
Signed-off-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+# This test sends traffic from H1 to H2. Either on ingress of $swp1, or on
+# egress of $swp2, the traffic is acted upon by an action skbedit priority. The
+# new priority should be taken into account when classifying traffic on the PRIO
+# qdisc at $swp2. The test verifies that for different priority values, the
+# traffic ends up in expected PRIO band.
+#
+# +----------------------+                             +----------------------+
+# | H1                   |                             |                   H2 |
+# |    + $h1             |                             |            $h2 +     |
+# |    | 192.0.2.1/28    |                             |   192.0.2.2/28 |     |
+# +----|-----------------+                             +----------------|-----+
+#      |                                                                |
+# +----|----------------------------------------------------------------|-----+
+# | SW |                                                                |     |
+# |  +-|----------------------------------------------------------------|-+   |
+# |  | + $swp1                       BR                           $swp2 + |   |
+# |  |                                                             PRIO   |   |
+# |  +--------------------------------------------------------------------+   |
+# +---------------------------------------------------------------------------+
+
+ALL_TESTS="
+	ping_ipv4
+	test_ingress
+	test_egress
+"
+
+NUM_NETIFS=4
+source lib.sh
+
+: ${HIT_TIMEOUT:=2000} # ms
+
+h1_create()
+{
+	simple_if_init $h1 192.0.2.1/28
+}
+
+h1_destroy()
+{
+	simple_if_fini $h1 192.0.2.1/28
+}
+
+h2_create()
+{
+	simple_if_init $h2 192.0.2.2/28
+}
+
+h2_destroy()
+{
+	simple_if_fini $h2 192.0.2.2/28
+}
+
+switch_create()
+{
+	ip link add name br1 up type bridge vlan_filtering 1
+	ip link set dev $swp1 master br1
+	ip link set dev $swp1 up
+	ip link set dev $swp2 master br1
+	ip link set dev $swp2 up
+
+	tc qdisc add dev $swp1 clsact
+	tc qdisc add dev $swp2 clsact
+	tc qdisc add dev $swp2 root handle 10: \
+	   prio bands 8 priomap 7 6 5 4 3 2 1 0
+}
+
+switch_destroy()
+{
+	tc qdisc del dev $swp2 root
+	tc qdisc del dev $swp2 clsact
+	tc qdisc del dev $swp1 clsact
+
+	ip link set dev $swp2 nomaster
+	ip link set dev $swp1 nomaster
+	ip link del dev br1
+}
+
+setup_prepare()
+{
+	h1=${NETIFS[p1]}
+	swp1=${NETIFS[p2]}
+
+	swp2=${NETIFS[p3]}
+	h2=${NETIFS[p4]}
+
+	h2mac=$(mac_get $h2)
+
+	vrf_prepare
+	h1_create
+	h2_create
+	switch_create
+}
+
+cleanup()
+{
+	pre_cleanup
+
+	switch_destroy
+	h2_destroy
+	h1_destroy
+	vrf_cleanup
+}
+
+ping_ipv4()
+{
+	ping_test $h1 192.0.2.2
+}
+
+test_skbedit_priority_one()
+{
+	local locus=$1; shift
+	local prio=$1; shift
+	local classid=$1; shift
+
+	RET=0
+
+	tc filter add $locus handle 101 pref 1 \
+	   flower action skbedit priority $prio
+
+	local pkt0=$(qdisc_parent_stats_get $swp2 $classid .packets)
+	$MZ $h1 -t udp "sp=54321,dp=12345" -c 10 -d 20msec -p 100 \
+	    -a own -b $h2mac -A 192.0.2.1 -B 192.0.2.2 -q
+	local pkt1
+	pkt1=$(busywait "$HIT_TIMEOUT" until_counter_is ">= $((pkt0 + 10))" \
+			qdisc_parent_stats_get $swp2 $classid .packets)
+
+	check_err $? "Expected to get 10 packets on class $classid, but got
+$((pkt1 - pkt0))."
+	log_test "$locus skbedit priority $prio -> classid $classid"
+
+	tc filter del $locus pref 1
+}
+
+test_ingress()
+{
+	local prio
+
+	for prio in {0..7}; do
+		test_skbedit_priority_one "dev $swp1 ingress" \
+					  $prio 10:$((8 - prio))
+	done
+}
+
+test_egress()
+{
+	local prio
+
+	for prio in {0..7}; do
+		test_skbedit_priority_one "dev $swp2 egress" \
+					  $prio 10:$((8 - prio))
+	done
+}
+
+trap cleanup EXIT
+
+setup_prepare
+setup_wait
+
+tests_run
+
+exit $EXIT_STATUS