selftests: mlxsw: Add a RED selftest

This tests that below the queue minimum length, there is no dropping /
marking, and above max, everything is dropped / marked.

The test is structured as a core file with topology and test code, and
three wrappers: one for RED used as a root Qdisc, and two for
testing (W)RED under PRIO and ETS.
Signed-off-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/drivers/net/mlxsw/sch_red_ets.sh

+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+ALL_TESTS="
+	ping_ipv4
+	ecn_test
+	red_test
+	mc_backlog_test
+"
+: ${QDISC:=ets}
+source sch_red_core.sh
+
+# do_ecn_test first build 2/3 of the requested backlog and expects no marking,
+# and then builds 3/2 of it and does expect marking. The values of $BACKLOG1 and
+# $BACKLOG2 are far enough not to overlap, so that we can assume that if we do
+# see (do not see) marking, it is actually due to the configuration of that one
+# TC, and not due to configuration of the other TC leaking over.
+BACKLOG1=200000
+BACKLOG2=500000
+
+install_qdisc()
+{
+	local -a args=("$@")
+
+	tc qdisc add dev $swp3 root handle 10: $QDISC \
+	   bands 8 priomap 7 6 5 4 3 2 1 0
+	tc qdisc add dev $swp3 parent 10:8 handle 108: red \
+	   limit 1000000 min $BACKLOG1 max $((BACKLOG1 + 1)) \
+	   probability 1.0 avpkt 8000 burst 38 "${args[@]}"
+	tc qdisc add dev $swp3 parent 10:7 handle 107: red \
+	   limit 1000000 min $BACKLOG2 max $((BACKLOG2 + 1)) \
+	   probability 1.0 avpkt 8000 burst 63 "${args[@]}"
+	sleep 1
+}
+
+uninstall_qdisc()
+{
+	tc qdisc del dev $swp3 parent 10:7
+	tc qdisc del dev $swp3 parent 10:8
+	tc qdisc del dev $swp3 root
+}
+
+ecn_test()
+{
+	install_qdisc ecn
+
+	do_ecn_test 10 $BACKLOG1
+	do_ecn_test 11 $BACKLOG2
+
+	uninstall_qdisc
+}
+
+red_test()
+{
+	install_qdisc
+
+	do_red_test 10 $BACKLOG1
+	do_red_test 11 $BACKLOG2
+
+	uninstall_qdisc
+}
+
+mc_backlog_test()
+{
+	install_qdisc
+
+	# Note that the backlog numbers here do not correspond to RED
+	# configuration, but are arbitrary.
+	do_mc_backlog_test 10 $BACKLOG1
+	do_mc_backlog_test 11 $BACKLOG2
+
+	uninstall_qdisc
+}
+
+trap cleanup EXIT
+
+setup_prepare
+setup_wait
+
+bail_on_lldpad
+tests_run
+
+exit $EXIT_STATUS

tools/testing/selftests/drivers/net/mlxsw/sch_red_prio.sh

+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+QDISC=prio
+source sch_red_ets.sh

tools/testing/selftests/drivers/net/mlxsw/sch_red_root.sh

+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+ALL_TESTS="
+	ping_ipv4
+	ecn_test
+	red_test
+	mc_backlog_test
+"
+source sch_red_core.sh
+
+BACKLOG=300000
+
+install_qdisc()
+{
+	local -a args=("$@")
+
+	tc qdisc add dev $swp3 root handle 108: red \
+	   limit 1000000 min $BACKLOG max $((BACKLOG + 1)) \
+	   probability 1.0 avpkt 8000 burst 38 "${args[@]}"
+	sleep 1
+}
+
+uninstall_qdisc()
+{
+	tc qdisc del dev $swp3 root
+}
+
+ecn_test()
+{
+	install_qdisc ecn
+	do_ecn_test 10 $BACKLOG
+	uninstall_qdisc
+}
+
+red_test()
+{
+	install_qdisc
+	do_red_test 10 $BACKLOG
+	uninstall_qdisc
+}
+
+mc_backlog_test()
+{
+	install_qdisc
+	# Note that the backlog value here does not correspond to RED
+	# configuration, but is arbitrary.
+	do_mc_backlog_test 10 $BACKLOG
+	uninstall_qdisc
+}
+
+trap cleanup EXIT
+
+setup_prepare
+setup_wait
+
+bail_on_lldpad
+tests_run
+
+exit $EXIT_STATUS

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

@@ -607,6 +607,16 @@ ethtool_stats_get()
 	ethtool -S $dev | grep "^ *$stat:" | head -n 1 | cut -d: -f2
 }
 
+qdisc_stats_get()
+{
+	local dev=$1; shift
+	local handle=$1; shift
+	local selector=$1; shift
+
+	tc -j -s qdisc show dev "$dev" \
+	    | jq '.[] | select(.handle == "'"$handle"'") | '"$selector"
+}
+
 humanize()
 {
 	local speed=$1; shift