tracing/ftrace: factorize the tracing files creation

Impact: cleanup

Most of the tracing files creation follow the same pattern:

ret = debugfs_create_file(...)
if (!ret)
	pr_warning("Couldn't create ... entry\n")

Unify it!

Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1238109938-11840-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 960cbf4..74a1180 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -2845,14 +2845,11 @@
 static __init int rb_init_debugfs(void)
 {
 	struct dentry *d_tracer;
-	struct dentry *entry;
 
 	d_tracer = tracing_init_dentry();
 
-	entry = debugfs_create_file("tracing_on", 0644, d_tracer,
-				    &ring_buffer_flags, &rb_simple_fops);
-	if (!entry)
-		pr_warning("Could not create debugfs 'tracing_on' entry\n");
+	trace_create_file("tracing_on", 0644, d_tracer,
+			    &ring_buffer_flags, &rb_simple_fops);
 
 	return 0;
 }