tracing: Improve message of empty set_ftrace_notrace file

When there's no entry in set_ftrace_notrace, it'll print nothing, but
it's better to print something like below like set_graph_notrace does:

  #### no functions disabled ####

Link: http://lkml.kernel.org/p/1402644246-4649-1-git-send-email-namhyung@kernel.org

Reported-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

kernel/trace/ftrace.c

@@ -2835,8 +2835,10 @@ static void *t_start(struct seq_file *m, loff_t *pos)
 	 * off, we can short cut and just print out that all
 	 * functions are enabled.
 	 */
-	if (iter->flags & FTRACE_ITER_FILTER &&
-	    ftrace_hash_empty(ops->filter_hash)) {
+	if ((iter->flags & FTRACE_ITER_FILTER &&
+	     ftrace_hash_empty(ops->filter_hash)) ||
+	    (iter->flags & FTRACE_ITER_NOTRACE &&
+	     ftrace_hash_empty(ops->notrace_hash))) {
 		if (*pos > 0)
 			return t_hash_start(m, pos);
 		iter->flags |= FTRACE_ITER_PRINTALL;
@@ -2881,7 +2883,10 @@ static int t_show(struct seq_file *m, void *v)
 		return t_hash_show(m, iter);
 
 	if (iter->flags & FTRACE_ITER_PRINTALL) {
-		seq_printf(m, "#### all functions enabled ####\n");
+		if (iter->flags & FTRACE_ITER_NOTRACE)
+			seq_printf(m, "#### no functions disabled ####\n");
+		else
+			seq_printf(m, "#### all functions enabled ####\n");
 		return 0;
 	}