selftests/ftrace: Add function filter on module testcase

#!/bin/sh

# SPDX-License-Identifier: GPL-2.0

# description: ftrace - function trace on module

[ ! -f set_ftrace_filter ] && exit_unsupported

: "mod: allows to filter a non exist function"

echo 'non_exist_func:mod:non_exist_module' > set_ftrace_filter

grep -q "non_exist_func" set_ftrace_filter

: "mod: on exist module"

echo '*:mod:trace_printk' > set_ftrace_filter

if ! modprobe trace-printk ; then

  echo "No trace-printk sample module - please make CONFIG_SAMPLE_TRACE_PRINTK=

m"

  exit_unresolved;

fi

: "Wildcard should be resolved after loading module"

grep -q "trace_printk_irq_work" set_ftrace_filter

: "After removing the filter becomes empty"

rmmod trace_printk

test `cat set_ftrace_filter | wc -l` -eq 0