selftests: forwarding: ethtool_rmon: Add histogram counter test

Validate the operation of rx and tx histogram counters, if supported
by the interface, by sending batches of packets targeted for each
bucket.

Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com>
Tested-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/net/forwarding/Makefile

@@ -17,6 +17,7 @@ TEST_PROGS = bridge_fdb_learning_limit.sh \
 	dual_vxlan_bridge.sh \
 	ethtool_extended_state.sh \
 	ethtool_mm.sh \
+	ethtool_rmon.sh \
 	ethtool.sh \
 	gre_custom_multipath_hash.sh \
 	gre_inner_v4_multipath.sh \

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

@@ -0,0 +1,143 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+ALL_TESTS="
+	rmon_rx_histogram
+	rmon_tx_histogram
+"
+
+NUM_NETIFS=2
+source lib.sh
+
+ETH_FCS_LEN=4
+ETH_HLEN=$((6+6+2))
+
+declare -A netif_mtu
+
+ensure_mtu()
+{
+	local iface=$1; shift
+	local len=$1; shift
+	local current=$(ip -j link show dev $iface | jq -r '.[0].mtu')
+	local required=$((len - ETH_HLEN - ETH_FCS_LEN))
+
+	if [ $current -lt $required ]; then
+		ip link set dev $iface mtu $required || return 1
+	fi
+}
+
+bucket_test()
+{
+	local iface=$1; shift
+	local neigh=$1; shift
+	local set=$1; shift
+	local bucket=$1; shift
+	local len=$1; shift
+	local num_rx=10000
+	local num_tx=20000
+	local expected=
+	local before=
+	local after=
+	local delta=
+
+	# Mausezahn does not include FCS bytes in its length - but the
+	# histogram counters do
+	len=$((len - ETH_FCS_LEN))
+
+	before=$(ethtool --json -S $iface --groups rmon | \
+		jq -r ".[0].rmon[\"${set}-pktsNtoM\"][$bucket].val")
+
+	# Send 10k one way and 20k in the other, to detect counters
+	# mapped to the wrong direction
+	$MZ $neigh -q -c $num_rx -p $len -a own -b bcast -d 10us
+	$MZ $iface -q -c $num_tx -p $len -a own -b bcast -d 10us
+
+	after=$(ethtool --json -S $iface --groups rmon | \
+		jq -r ".[0].rmon[\"${set}-pktsNtoM\"][$bucket].val")
+
+	delta=$((after - before))
+
+	expected=$([ $set = rx ] && echo $num_rx || echo $num_tx)
+
+	# Allow some extra tolerance for other packets sent by the stack
+	[ $delta -ge $expected ] && [ $delta -le $((expected + 100)) ]
+}
+
+rmon_histogram()
+{
+	local iface=$1; shift
+	local neigh=$1; shift
+	local set=$1; shift
+	local nbuckets=0
+	local step=
+
+	RET=0
+
+	while read -r -a bucket; do
+		step="$set-pkts${bucket[0]}to${bucket[1]} on $iface"
+
+		for if in $iface $neigh; do
+			if ! ensure_mtu $if ${bucket[0]}; then
+				log_test_skip "$if does not support the required MTU for $step"
+				return
+			fi
+		done
+
+		if ! bucket_test $iface $neigh $set $nbuckets ${bucket[0]}; then
+			check_err 1 "$step failed"
+			return 1
+		fi
+		log_test "$step"
+		nbuckets=$((nbuckets + 1))
+	done < <(ethtool --json -S $iface --groups rmon | \
+		jq -r ".[0].rmon[\"${set}-pktsNtoM\"][]|[.low, .high]|@tsv" 2>/dev/null)
+
+	if [ $nbuckets -eq 0 ]; then
+		log_test_skip "$iface does not support $set histogram counters"
+		return
+	fi
+}
+
+rmon_rx_histogram()
+{
+	rmon_histogram $h1 $h2 rx
+	rmon_histogram $h2 $h1 rx
+}
+
+rmon_tx_histogram()
+{
+	rmon_histogram $h1 $h2 tx
+	rmon_histogram $h2 $h1 tx
+}
+
+setup_prepare()
+{
+	h1=${NETIFS[p1]}
+	h2=${NETIFS[p2]}
+
+	for iface in $h1 $h2; do
+		netif_mtu[$iface]=$(ip -j link show dev $iface | jq -r '.[0].mtu')
+		ip link set dev $iface up
+	done
+}
+
+cleanup()
+{
+	pre_cleanup
+
+	for iface in $h2 $h1; do
+		ip link set dev $iface \
+			mtu ${netif_mtu[$iface]} \
+			down
+	done
+}
+
+check_ethtool_counter_group_support
+trap cleanup EXIT
+
+setup_prepare
+setup_wait
+
+tests_run
+
+exit $EXIT_STATUS

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

@@ -146,6 +146,15 @@ check_ethtool_mm_support()
 	fi
 }
 
+check_ethtool_counter_group_support()
+{
+	ethtool --help 2>&1| grep -- '--all-groups' &> /dev/null
+	if [[ $? -ne 0 ]]; then
+		echo "SKIP: ethtool too old; it is missing standard counter group support"
+		exit $ksft_skip
+	fi
+}
+
 check_locked_port_support()
 {
 	if ! bridge -d link show | grep -q " locked"; then