selftests: ftrace: Add a selftest to test event enable/disable func trigger

This adds a test to enable and disable trace events via the function
triggers. It tests enabling and disabling the sched:sched_switch event via
the the event_enable and event_disable function triggers attached to the
schedule() kernel function.

The test does the following:

 o disable all events

 o disables or enables the sched_switch event

 o writes schedule:event_enable/disable:sched:sched_switch into set_ftrace_filter

 o 5 times it checks to make sure:

    . Writes 0/1 into the sched_switch/enable

    . Checks that the sched_switch/enable goes back to 1/0

 o Resets the events

 o writes schedule:event_enable/disable:sched:sched_switch:3 into set_ftrace_filter

 o Does a loop of 3 to see that sched_switch/enable file gets updated

 o Makes sure the sched_switch/enable stops getting updated
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tools/testing/selftests/ftrace/test.d/ftrace/func_event_triggers.tc

+#!/bin/sh
+# description: ftrace - test for function event triggers
+#
+# Ftrace allows to add triggers to functions, such as enabling or disabling
+# tracing, enabling or disabling trace events, or recording a stack trace
+# within the ring buffer.
+#
+# This test is designed to test event triggers
+#
+
+# The triggers are set within the set_ftrace_filter file
+if [ ! -f set_ftrace_filter ]; then
+    echo "set_ftrace_filter not found? Is dynamic ftrace not set?"
+    exit_unsupported
+fi
+
+do_reset() {
+    reset_ftrace_filter
+    reset_tracer
+    disable_events
+    clear_trace
+    enable_tracing
+}
+
+fail() { # mesg
+    do_reset
+    echo $1
+    exit $FAIL
+}
+
+SLEEP_TIME=".1"
+
+do_reset
+
+echo "Testing function probes with events:"
+
+EVENT="sched:sched_switch"
+EVENT_ENABLE="events/sched/sched_switch/enable"
+
+cnt_trace() {
+    grep -v '^#' trace | wc -l
+}
+
+test_event_enabled() {
+    val=$1
+
+    e=`cat $EVENT_ENABLE`
+    if [ "$e" != $val ]; then
+	echo "Expected $val but found $e"
+	exit -1
+    fi
+}
+
+run_enable_disable() {
+    enable=$1			# enable
+    Enable=$2			# Enable
+    check_disable=$3		# 0
+    check_enable_star=$4	# 1*
+    check_disable_star=$5	# 0*
+
+    cnt=`cnt_trace`
+    if [ $cnt -ne 0 ]; then
+	fail "Found junk in trace file"
+    fi
+
+    echo "$Enable event all the time"
+
+    echo $check_disable > $EVENT_ENABLE
+    sleep $SLEEP_TIME
+
+    test_event_enabled $check_disable
+
+    echo "schedule:${enable}_event:$EVENT" > set_ftrace_filter
+
+    echo " make sure it works 5 times"
+
+    for i in `seq 5`; do
+	sleep $SLEEP_TIME
+	echo "  test $i"
+	test_event_enabled $check_enable_star
+
+	echo $check_disable > $EVENT_ENABLE
+    done
+    sleep $SLEEP_TIME
+    echo " make sure it's still works"
+    test_event_enabled $check_enable_star
+
+    reset_ftrace_filter
+
+    echo " make sure it only works 3 times"
+
+    echo $check_disable > $EVENT_ENABLE
+    sleep $SLEEP_TIME
+
+    echo "schedule:${enable}_event:$EVENT:3" > set_ftrace_filter
+
+    for i in `seq 3`; do
+	sleep $SLEEP_TIME
+	echo "  test $i"
+	test_event_enabled $check_enable_star
+
+	echo $check_disable > $EVENT_ENABLE
+    done
+
+    sleep $SLEEP_TIME
+    echo " make sure it stop working"
+    test_event_enabled $check_disable_star
+
+    do_reset
+}
+
+run_enable_disable enable Enable 0 "1*" "0*"
+run_enable_disable disable Disable 1 "0*" "1*"