#!/bin/bash

find_debugfs() {
    debugfs=`cat /proc/mounts | while read mount dir type opts a b; do
	if [ $mount == "debugfs" ]; then
	    echo $dir;
	    break
	fi
    done`
    if [ -z "$debugfs" ]; then
	if ! mount -t debugfs nodev /sys/kernel/debug; then
	    echo "FAILED to mount debugfs"
	    exit -1
	fi
	echo "/sys/kernel/debug"
    else
	echo $debugfs
    fi
}

debugfs=`find_debugfs`
TRACEDIR="$debugfs/tracing"
EVENTDIR=$TRACEDIR/events
EVENT=$EVENTDIR/sched/sched_switch
EVENT_ENABLE=$EVENT/enable
TRIGGER_FILE=$EVENT/trigger
TRACE_FILE=$TRACEDIR/trace
TRACING_ON=$TRACEDIR/tracing_on

# set -x

if [ ! -f $TRIGGER_FILE ]; then
    echo "triggers are not set for this kernel"
    exit 0
fi

function cnt_trace() {
	    grep -v '^#' $TRACE_FILE | wc -l
}

function clear_triggers() {
    grep -v '^#' $TRIGGER_FILE | while read t; do
	tr=`echo $t | sed -e s'/:.*//'`
	if [ $tr == "enable_event" -o $tr == "disable_event" ]; then
	    tr=`echo $t | sed -e s'/\([^:]*:[^:]*:[^:]*\):.*/\1/'`
	fi
	echo "!$tr" > $TRIGGER_FILE
    done
}

function check_events() {
    events=$1
    stack=$2
    count=$3

    if [ $events -eq 1 ]; then
	if ! grep -q 'sched_switch:' $TRACE_FILE ; then
	    echo "Expected event but it wasn't there"
	    exit -1
	fi
    else
	if grep -q 'sched_switch:' $TRACE_FILE ; then
	    echo "Expected no events but events were found"
	    exit -1
	fi
    fi

    if [ $stack -eq 1 ]; then
	if [ $count -eq 0 ]; then
	    # unlimited, find the sleep call
	    if ! grep -q '^ => .*sleep' $TRACE_FILE; then
		echo "Could not find sleep call"
		exit -1
	    fi
	else
	    # count the stack traces
	    cnt=`grep '<stack trace>' $TRACE_FILE | wc -l`;
	    if [ $cnt -ne $count ]; then
		echo "Expected $count hits but only see $cnt"
		exit -1
	    fi
	fi
    else
	if grep -q '^ =>' $TRACE_FILE; then
	    echo "Found stack trace when not enabled"
	    exit -1
	fi
    fi
}

function do_reset() {
    clear_triggers
    echo nop > $TRACEDIR/current_tracer || exit -1
    echo 0 > $TRACEDIR/events/enable || exit -1
    echo > $TRACE_FILE || exit -1
    echo 1 > $TRACING_ON || exit -1
}

#set -x

echo '** CLEAR TRACE'
do_reset

# check stacktrace available
if ! grep -q stacktrace $TRIGGER_FILE; then
    echo "stacktrace trigger not available"
    exit 0
fi

cnt=`cnt_trace`
if [ $cnt -ne 0 ]; then
    echo "Found junk in trace file, exiting"
    exit -1
fi

echo "Enable only events"

echo 1 > $EVENT_ENABLE
sleep 1
echo 0 > $TRACING_ON

check_events 1 0 0
do_reset

echo "Enable only stack trace"

echo 0 > $TRACING_ON
echo stacktrace > $TRIGGER_FILE

echo 1 > $TRACING_ON
sleep 1
echo 0 > $TRACING_ON

check_events 0 1 0
do_reset


echo "Enable both stack trace and events"

echo 0 > $TRACING_ON
echo stacktrace > $TRIGGER_FILE
echo 1 > $EVENT_ENABLE

echo 1 > $TRACING_ON
sleep 1
echo 0 > $TRACING_ON

check_events 1 1 0
do_reset

for i in 1 2 3; do
    if [ $i -gt 1 ]; then
	s='s'
    else
	s=''
    fi
    echo "Enable stack trace only $i time$s"

    echo 1 > $TRACING_ON
    echo stacktrace:$i > $TRIGGER_FILE
    echo 1 > $EVENT_ENABLE

    sleep 1
    echo 0 > $TRACING_ON

    check_events 1 1 $i
    do_reset
done


echo '** SUCCESS'

exit 0