tracing: Do not try to recreated toplevel set_ftrace_* files

With the restructing of the function tracer working with instances, the "top level" buffer is a bit special, as the function tracing is mapped to the same set of filters. This is done by using a "global_ops" descriptor and having the "set_ftrace_filter" and "set_ftrace_notrace" map to it. When an instance is created, it creates the same files but its for the local instance and not the global_ops. The issues is that the local instance creation shares some code with the global instance one and we end up trying to create th top level "set_ftrace_*" files twice, and on boot up, we get an error like this: Could not create debugfs 'set_ftrace_filter' entry Could not create debugfs 'set_ftrace_notrace' entry The reason they failed to be created was because they were created twice, and the second time gives this error as you can not create the same file twice. Reported-by: Borislav Petkov <bp@alien8.de> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

tracing: Do not try to recreated toplevel set_ftrace_* files
With the restructing of the function tracer working with instances, the "top level" buffer is a bit special, as the function tracing is mapped to the same set of filters. This is done by using a "global_ops" descriptor and having the "set_ftrace_filter" and "set_ftrace_notrace" map to it. When an instance is created, it creates the same files but its for the local instance and not the global_ops. The issues is that the local instance creation shares some code with the global instance one and we end up trying to create th top level "set_ftrace_*" files twice, and on boot up, we get an error like this: Could not create debugfs 'set_ftrace_filter' entry Could not create debugfs 'set_ftrace_notrace' entry The reason they failed to be created was because they were created twice, and the second time gives this error as you can not create the same file twice. Reported-by: Borislav Petkov <bp@alien8.de> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Steven Rostedt (Red Hat) · Steven Rostedt
1 parent 17a280ea81
Showing 1 changed file with 10 additions and 6 deletions Side-by-side Diff
kernel/trace/trace_functions.c
@@ -58,12 +58,16 @@
 {
 	int ret;
  
-	/* The top level array uses the "global_ops". */
-	if (!(tr->flags & TRACE_ARRAY_FL_GLOBAL)) {
-		ret = allocate_ftrace_ops(tr);
-		if (ret)
-			return ret;
-	}
+	/*
+	 * The top level array uses the "global_ops", and the files are
+	 * created on boot up.
+	 */
+	if (tr->flags & TRACE_ARRAY_FL_GLOBAL)
+		return 0;
+
+	ret = allocate_ftrace_ops(tr);
+	if (ret)
+		return ret;
  
 	ftrace_create_filter_files(tr->ops, parent);
...	...	@@ -58,12 +58,16 @@
58	58	{
59	59	int ret;
60	60
61		- /* The top level array uses the "global_ops". */
62		- if (!(tr->flags & TRACE_ARRAY_FL_GLOBAL)) {
63		- ret = allocate_ftrace_ops(tr);
64		- if (ret)
65		- return ret;
66		- }
	61	+ /*
	62	+ * The top level array uses the "global_ops", and the files are
	63	+ * created on boot up.
	64	+ */
	65	+ if (tr->flags & TRACE_ARRAY_FL_GLOBAL)
	66	+ return 0;
	67	+
	68	+ ret = allocate_ftrace_ops(tr);
	69	+ if (ret)
	70	+ return ret;
67	71
68	72	ftrace_create_filter_files(tr->ops, parent);
69	73