selftests/ftrace: Add "requires:" list support

Introduce "requires:" list to check required ftrace interface
for each test. This will simplify the interface checking code
and unify the error message. Another good point is, it can
skip the ftrace initializing.

Note that this requires list must be written as a shell
comment.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/selftests/ftrace/ftracetest

@@ -267,6 +267,11 @@ testcase() { # testfile
   prlog -n "[$CASENO]$INSTANCE$desc"
 }
 
+checkreq() { # testfile
+  requires=`grep "^#[ \t]*requires:" $1 | cut -f2- -d:`
+  check_requires $requires
+}
+
 test_on_instance() { # testfile
   grep -q "^#[ \t]*flags:.*instance" $1
 }
@@ -356,7 +361,8 @@ trap 'SIG_RESULT=$XFAIL' $SIG_XFAIL
 
 __run_test() { # testfile
   # setup PID and PPID, $$ is not updated.
-  (cd $TRACING_DIR; read PID _ < /proc/self/stat; set -e; set -x; initialize_ftrace; . $1)
+  (cd $TRACING_DIR; read PID _ < /proc/self/stat; set -e; set -x;
+   checkreq $1; initialize_ftrace; . $1)
   [ $? -ne 0 ] && kill -s $SIG_FAIL $SIG_PID
 }
 

tools/testing/selftests/ftrace/test.d/functions

@@ -113,6 +113,15 @@ initialize_ftrace() { # Reset ftrace to initial-state
     enable_tracing
 }
 
+check_requires() { # Check required files
+    for i in $* ; do
+        if [ ! -e $i ]; then
+            echo "Required feature interface $i doesn't exist."
+            exit_unsupported
+        fi
+    done
+}
+
 LOCALHOST=127.0.0.1
 
 yield() {

tools/testing/selftests/ftrace/test.d/template

 #!/bin/sh
 # SPDX-License-Identifier: GPL-2.0
 # description: %HERE DESCRIBE WHAT THIS DOES%
+# requires: %HERE LIST THE REQUIRED FILES%
 # you have to add ".tc" extention for your testcase file
 # Note that all tests are run with "errexit" option.