tracing: Add trace options for tracer options to instances

Add the tracer options to instances options directory as well. Only add the
options for tracers that are allowed to be enabled by an instance. But note,
that tracer options are global. That is, tracer options enabled in an
instance, also take affect at the top level and in other instances.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

kernel/trace/trace.c

@@ -4308,7 +4308,7 @@ int tracing_update_buffers(void)
 
 struct trace_option_dentry;
 
-static struct trace_option_dentry *
+static void
 create_trace_option_files(struct trace_array *tr, struct tracer *tracer);
 
 /*
@@ -4334,15 +4334,7 @@ static void add_tracer_options(struct trace_array *tr, struct tracer *t)
 	if (!tr->dir)
 		return;
 
-	/* Currently, only the top instance has options */
-	if (!(tr->flags & TRACE_ARRAY_FL_GLOBAL))
-		return;
-
-	/* Ignore if they were already created */
-	if (t->topts)
-		return;
-
-	t->topts = create_trace_option_files(tr, t);
+	create_trace_option_files(tr, t);
 }
 
 static int tracing_set_tracer(struct trace_array *tr, const char *buf)
@@ -6341,21 +6333,39 @@ create_trace_option_file(struct trace_array *tr,
 
 }
 
-static struct trace_option_dentry *
+static void
 create_trace_option_files(struct trace_array *tr, struct tracer *tracer)
 {
 	struct trace_option_dentry *topts;
+	struct trace_options *tr_topts;
 	struct tracer_flags *flags;
 	struct tracer_opt *opts;
 	int cnt;
+	int i;
 
 	if (!tracer)
-		return NULL;
+		return;
 
 	flags = tracer->flags;
 
 	if (!flags || !flags->opts)
-		return NULL;
+		return;
+
+	/*
+	 * If this is an instance, only create flags for tracers
+	 * the instance may have.
+	 */
+	if (!trace_ok_for_array(tracer, tr))
+		return;
+
+	for (i = 0; i < tr->nr_topts; i++) {
+		/*
+		 * Check if these flags have already been added.
+		 * Some tracers share flags.
+		 */
+		if (tr->topts[i].tracer->flags == tracer->flags)
+			return;
+	}
 
 	opts = flags->opts;
 
@@ -6364,7 +6374,19 @@ create_trace_option_files(struct trace_array *tr, struct tracer *tracer)
 
 	topts = kcalloc(cnt + 1, sizeof(*topts), GFP_KERNEL);
 	if (!topts)
-		return NULL;
+		return;
+
+	tr_topts = krealloc(tr->topts, sizeof(*tr->topts) * (tr->nr_topts + 1),
+			    GFP_KERNEL);
+	if (!tr_topts) {
+		kfree(topts);
+		return;
+	}
+
+	tr->topts = tr_topts;
+	tr->topts[tr->nr_topts].tracer = tracer;
+	tr->topts[tr->nr_topts].topts = topts;
+	tr->nr_topts++;
 
 	for (cnt = 0; opts[cnt].name; cnt++) {
 		create_trace_option_file(tr, &topts[cnt], flags,
@@ -6373,8 +6395,6 @@ create_trace_option_files(struct trace_array *tr, struct tracer *tracer)
 			  "Failed to create trace option: %s",
 			  opts[cnt].name);
 	}
-
-	return topts;
 }
 
 static struct dentry *
@@ -6552,6 +6572,21 @@ static void init_trace_flags_index(struct trace_array *tr)
 		tr->trace_flags_index[i] = i;
 }
 
+static void __update_tracer_options(struct trace_array *tr)
+{
+	struct tracer *t;
+
+	for (t = trace_types; t; t = t->next)
+		add_tracer_options(tr, t);
+}
+
+static void update_tracer_options(struct trace_array *tr)
+{
+	mutex_lock(&trace_types_lock);
+	__update_tracer_options(tr);
+	mutex_unlock(&trace_types_lock);
+}
+
 static int instance_mkdir(const char *name)
 {
 	struct trace_array *tr;
@@ -6605,6 +6640,7 @@ static int instance_mkdir(const char *name)
 
 	init_tracer_tracefs(tr, tr->dir);
 	init_trace_flags_index(tr);
+	__update_tracer_options(tr);
 
 	list_add(&tr->list, &ftrace_trace_arrays);
 
@@ -6630,6 +6666,7 @@ static int instance_rmdir(const char *name)
 	struct trace_array *tr;
 	int found = 0;
 	int ret;
+	int i;
 
 	mutex_lock(&trace_types_lock);
 
@@ -6655,6 +6692,11 @@ static int instance_rmdir(const char *name)
 	debugfs_remove_recursive(tr->dir);
 	free_trace_buffers(tr);
 
+	for (i = 0; i < tr->nr_topts; i++) {
+		kfree(tr->topts[i].topts);
+	}
+	kfree(tr->topts);
+
 	kfree(tr->name);
 	kfree(tr);
 
@@ -6877,7 +6919,6 @@ static struct notifier_block trace_module_nb = {
 static __init int tracer_init_tracefs(void)
 {
 	struct dentry *d_tracer;
-	struct tracer *t;
 
 	trace_access_lock_init();
 
@@ -6914,10 +6955,7 @@ static __init int tracer_init_tracefs(void)
 
 	create_trace_instances(d_tracer);
 
-	mutex_lock(&trace_types_lock);
-	for (t = trace_types; t; t = t->next)
-		add_tracer_options(&global_trace, t);
-	mutex_unlock(&trace_types_lock);
+	update_tracer_options(&global_trace);
 
 	return 0;
 }

kernel/trace/trace.h

@@ -159,6 +159,7 @@ struct trace_array_cpu {
 };
 
 struct tracer;
+struct trace_option_dentry;
 
 struct trace_buffer {
 	struct trace_array		*tr;
@@ -170,6 +171,11 @@ struct trace_buffer {
 
 #define TRACE_FLAGS_MAX_SIZE		32
 
+struct trace_options {
+	struct tracer			*tracer;
+	struct trace_option_dentry	*topts;
+};
+
 /*
  * The trace array - an array of per-CPU trace arrays. This is the
  * highest level data structure that individual tracers deal with.
@@ -218,6 +224,7 @@ struct trace_array {
 #endif
 	int			stop_count;
 	int			clock_id;
+	int			nr_topts;
 	struct tracer		*current_trace;
 	unsigned int		trace_flags;
 	unsigned char		trace_flags_index[TRACE_FLAGS_MAX_SIZE];
@@ -227,6 +234,7 @@ struct trace_array {
 	struct dentry		*options;
 	struct dentry		*percpu_dir;
 	struct dentry		*event_dir;
+	struct trace_options	*topts;
 	struct list_head	systems;
 	struct list_head	events;
 	cpumask_var_t		tracing_cpumask; /* only trace on set CPUs */
@@ -398,7 +406,6 @@ struct tracer {
 						u32 mask, int set);
 	struct tracer		*next;
 	struct tracer_flags	*flags;
-	struct trace_option_dentry *topts;
 	int			enabled;
 	int			ref;
 	bool			print_max;