ftrace: Call trace_parser_clear() properly

I found a weird behavior:

  # echo 'fuse:*' > set_ftrace_filter
  bash: echo: write error: Invalid argument
  # cat set_ftrace_filter
  fuse_dev_fasync
  fuse_dev_poll
  fuse_copy_do

We should call trace_parser_clear() no matter ftrace_process_regex()
returns 0 or -errno, otherwise we will actually take the unaccepted
records from ftrace_regex_release().
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
LKML-Reference: <4B1DC4D2.3000406@cn.fujitsu.com>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>

kernel/trace/ftrace.c

@@ -2208,10 +2208,9 @@ ftrace_regex_write(struct file *file, const char __user *ubuf,
 	    !trace_parser_cont(parser)) {
 		ret = ftrace_process_regex(parser->buffer,
 					   parser->idx, enable);
+		trace_parser_clear(parser);
 		if (ret)
 			goto out_unlock;
-
-		trace_parser_clear(parser);
 	}
 
 	ret = read;