tracing: Add hist trigger onchange() handler test case

#!/bin/sh

# SPDX-License-Identifier: GPL-2.0

# description: event trigger - test inter-event histogram trigger onchange action

fail() { #msg

    echo $1

    exit_fail

}

if [ ! -f set_event ]; then

    echo "event tracing is not supported"

    exit_unsupported

fi

grep -q "onchange(var)" README || exit_unsupported # version issue

echo "Test onchange action"

echo 'hist:keys=comm:newprio=prio:onchange($newprio).save(comm,prio) if comm=="ping"' >> /sys/kernel/debug/tracing/events/sched/sched_waking/trigger

ping $LOCALHOST -c 3

nice -n 1 ping $LOCALHOST -c 3

if ! grep -q "changed:" events/sched/sched_waking/hist; then

    fail "Failed to create onchange action inter-event histogram"

fi

exit 0