tracing: Create cmdline tracer options on tracing fs init

The options for cmdline tracers are not created if the debugfs system is not ready yet. If tracing has started before debugfs is up, then the option files for the tracer are not created. Create them when creating the tracing directory if the current tracer requires option files. Signed-off-by: Steven Rostedt <[email protected]>
josf · Feb 3, 2015 · 09d23a1 · 09d23a1
1 parent 0f67f04
commit 09d23a1
Showing 1 changed file with 21 additions and 9 deletions.
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
@@ -4105,9 +4105,24 @@ static void tracing_set_nop(struct trace_array *tr)
 	tr->current_trace = &nop_trace;
 }
 
-static int tracing_set_tracer(struct trace_array *tr, const char *buf)
+static void update_tracer_options(struct trace_array *tr, struct tracer *t)
 {
 	static struct trace_option_dentry *topts;
+
+	/* Only enable if the directory has been created already. */
+	if (!tr->dir)
+		return;
+
+	/* Currently, only the top instance has options */
+	if (!(tr->flags & TRACE_ARRAY_FL_GLOBAL))
+		return;
+
+	destroy_trace_option_files(topts);
+	topts = create_trace_option_files(tr, t);
+}
+
+static int tracing_set_tracer(struct trace_array *tr, const char *buf)
+{
 	struct tracer *t;
 #ifdef CONFIG_TRACER_MAX_TRACE
 	bool had_max_tr;
@@ -4172,14 +4187,7 @@ static int tracing_set_tracer(struct trace_array *tr, const char *buf)
 		free_snapshot(tr);
 	}
 #endif
-	/*
-	 * Only enable if the directory has been created already.
-	 * Currently, only the top instance has options
-	 */
-	if (tr->dir && tr->flags & TRACE_ARRAY_FL_GLOBAL) {
-		destroy_trace_option_files(topts);
-		topts = create_trace_option_files(tr, t);
-	}
+	update_tracer_options(tr, t);
 
 #ifdef CONFIG_TRACER_MAX_TRACE
 	if (t->use_max_tr && !had_max_tr) {
@@ -6578,6 +6586,10 @@ static __init int tracer_init_debugfs(void)
 
 	create_trace_options_dir(&global_trace);
 
+	/* If the tracer was started via cmdline, create options for it here */
+	if (global_trace.current_trace != &nop_trace)
+		update_tracer_options(&global_trace, global_trace.current_trace);
+
 	return 0;
 }