tracing: Check return value of tracing_init_dentry()

Check return value and bail out if it's NULL.

Link: http://lkml.kernel.org/r/[email protected]

Cc: Frederic Weisbecker <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: [email protected]
Signed-off-by: Namhyung Kim <[email protected]>
Signed-off-by: Steven Rostedt <[email protected]>

kernel/trace/trace.c

@@ -5953,6 +5953,8 @@ static __init int tracer_init_debugfs(void)
 	trace_access_lock_init();
 
 	d_tracer = tracing_init_dentry();
+	if (!d_tracer)
+		return 0;
 
 	init_tracer_debugfs(&global_trace, d_tracer);
 

kernel/trace/trace_stack.c

@@ -431,6 +431,8 @@ static __init int stack_trace_init(void)
 	struct dentry *d_tracer;
 
 	d_tracer = tracing_init_dentry();
+	if (!d_tracer)
+		return 0;
 
 	trace_create_file("stack_max_size", 0644, d_tracer,
 			&max_stack_size, &stack_max_size_fops);

kernel/trace/trace_stat.c

@@ -307,6 +307,8 @@ static int tracing_stat_init(void)
 	struct dentry *d_tracing;
 
 	d_tracing = tracing_init_dentry();
+	if (!d_tracing)
+		return 0;
 
 	stat_dir = debugfs_create_dir("trace_stat", d_tracing);
 	if (!stat_dir)