While testing my development branch, without the fix for the pid use

after free bug, the selftest that Namhyung added triggers it. I figured
 it would be good to add the test for the bug after the fix, such that
 it does not exist without the fix.
 
 I added another patch that lets the test only test part of the pid
 filtering, and ignores the function-fork (filtering on children as well)
 if the function-fork feature does not exist. This feature is added by
 Namhyung just before he added this test. But since the test tests both
 with and without the feature, it would be good to let it not fail if
 the feature does not exist.
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Merge tag 'trace-v4.11-rc5-4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull ftrace testcase update from Steven Rostedt:
 "While testing my development branch, without the fix for the pid use
  after free bug, the selftest that Namhyung added triggers it. I
  figured it would be good to add the test for the bug after the fix,
  such that it does not exist without the fix.

  I added another patch that lets the test only test part of the pid
  filtering, and ignores the function-fork (filtering on children as
  well) if the function-fork feature does not exist. This feature is
  added by Namhyung just before he added this test. But since the test
  tests both with and without the feature, it would be good to let it
  not fail if the feature does not exist"

* tag 'trace-v4.11-rc5-4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  selftests: ftrace: Add check for function-fork before running pid filter test
  selftests: ftrace: Add a testcase for function PID filter

tools/testing/selftests/ftrace/test.d/ftrace/func-filter-pid.tc

@@ -0,0 +1,117 @@
+#!/bin/sh
+# description: ftrace - function pid filters
+
+# Make sure that function pid matching filter works.
+# Also test it on an instance directory
+
+if ! grep -q function available_tracers; then
+    echo "no function tracer configured"
+    exit_unsupported
+fi
+
+if [ ! -f set_ftrace_pid ]; then
+    echo "set_ftrace_pid not found? Is function tracer not set?"
+    exit_unsupported
+fi
+
+if [ ! -f set_ftrace_filter ]; then
+    echo "set_ftrace_filter not found? Is function tracer not set?"
+    exit_unsupported
+fi
+
+do_function_fork=1
+
+if [ ! -f options/function-fork ]; then
+    do_function_fork=0
+    echo "no option for function-fork found. Option will not be tested."
+fi
+
+read PID _ < /proc/self/stat
+
+if [ $do_function_fork -eq 1 ]; then
+    # default value of function-fork option
+    orig_value=`grep function-fork trace_options`
+fi
+
+do_reset() {
+    reset_tracer
+    clear_trace
+    enable_tracing
+    echo > set_ftrace_filter
+    echo > set_ftrace_pid
+
+    if [ $do_function_fork -eq 0 ]; then
+	return
+    fi
+
+    echo $orig_value > trace_options
+}
+
+fail() { # msg
+    do_reset
+    echo $1
+    exit $FAIL
+}
+
+yield() {
+    ping localhost -c 1 || sleep .001 || usleep 1 || sleep 1
+}
+
+do_test() {
+    disable_tracing
+
+    echo do_execve* > set_ftrace_filter
+    echo *do_fork >> set_ftrace_filter
+
+    echo $PID > set_ftrace_pid
+    echo function > current_tracer
+
+    if [ $do_function_fork -eq 1 ]; then
+	# don't allow children to be traced
+	echo nofunction-fork > trace_options
+    fi
+
+    enable_tracing
+    yield
+
+    count_pid=`cat trace | grep -v ^# | grep $PID | wc -l`
+    count_other=`cat trace | grep -v ^# | grep -v $PID | wc -l`
+
+    # count_other should be 0
+    if [ $count_pid -eq 0 -o $count_other -ne 0 ]; then
+	fail "PID filtering not working?"
+    fi
+
+    disable_tracing
+    clear_trace
+
+    if [ $do_function_fork -eq 0 ]; then
+	return
+    fi
+
+    # allow children to be traced
+    echo function-fork > trace_options
+
+    enable_tracing
+    yield
+
+    count_pid=`cat trace | grep -v ^# | grep $PID | wc -l`
+    count_other=`cat trace | grep -v ^# | grep -v $PID | wc -l`
+
+    # count_other should NOT be 0
+    if [ $count_pid -eq 0 -o $count_other -eq 0 ]; then
+	fail "PID filtering not following fork?"
+    fi
+}
+
+do_test
+
+mkdir instances/foo
+cd instances/foo
+do_test
+cd ../../
+rmdir instances/foo
+
+do_reset
+
+exit 0