tracing: Do not create function tracer options when not compiled in

When the function tracer is not compiled in, do not create the option files
for it.

Fix up both the sched_wakeup and irqsoff tracers to handle the change.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

kernel/trace/trace.c

@@ -490,11 +490,11 @@ static inline void ftrace_trace_stack(struct ring_buffer *buffer,
 
 /* trace_flags holds trace_options default values */
 unsigned long trace_flags =
-	FUNCTION_GRAPH_DEFAULT_FLAGS |
+	FUNCTION_DEFAULT_FLAGS | FUNCTION_GRAPH_DEFAULT_FLAGS |
 	TRACE_ITER_PRINT_PARENT | TRACE_ITER_PRINTK |
 	TRACE_ITER_ANNOTATE | TRACE_ITER_CONTEXT_INFO |
 	TRACE_ITER_RECORD_CMD | TRACE_ITER_OVERWRITE |
-	TRACE_ITER_IRQ_INFO | TRACE_ITER_MARKERS | TRACE_ITER_FUNCTION
+	TRACE_ITER_IRQ_INFO | TRACE_ITER_MARKERS
 	;
 
 static void tracer_tracing_on(struct trace_array *tr)

kernel/trace/trace.h

@@ -902,6 +902,15 @@ extern int trace_get_user(struct trace_parser *parser, const char __user *ubuf,
 # define BRANCH_FLAGS
 #endif
 
+#ifdef CONFIG_FUNCTION_TRACER
+# define FUNCTION_FLAGS						\
+		C(FUNCTION,		"function-trace"),
+# define FUNCTION_DEFAULT_FLAGS		TRACE_ITER_FUNCTION
+#else
+# define FUNCTION_FLAGS
+# define FUNCTION_DEFAULT_FLAGS		0UL
+#endif
+
 /*
  * trace_iterator_flags is an enumeration that defines bit
  * positions into trace_flags that controls the output.
@@ -931,7 +940,7 @@ extern int trace_get_user(struct trace_parser *parser, const char __user *ubuf,
 		C(STOP_ON_FREE,		"disable_on_free"),	\
 		C(IRQ_INFO,		"irq-info"),		\
 		C(MARKERS,		"markers"),		\
-		C(FUNCTION,		"function-trace"),	\
+		FUNCTION_FLAGS					\
 		FGRAPH_FLAGS					\
 		BRANCH_FLAGS
 

kernel/trace/trace_irqsoff.c

@@ -31,7 +31,6 @@ enum {
 static int trace_type __read_mostly;
 
 static int save_flags;
-static bool function_enabled;
 
 static void stop_irqsoff_tracer(struct trace_array *tr, int graph);
 static int start_irqsoff_tracer(struct trace_array *tr, int graph);
@@ -249,21 +248,23 @@ __trace_function(struct trace_array *tr,
 #else
 #define __trace_function trace_function
 
+#ifdef CONFIG_FUNCTION_TRACER
 static int irqsoff_graph_entry(struct ftrace_graph_ent *trace)
 {
 	return -1;
 }
+#endif
 
 static enum print_line_t irqsoff_print_line(struct trace_iterator *iter)
 {
 	return TRACE_TYPE_UNHANDLED;
 }
 
-static void irqsoff_graph_return(struct ftrace_graph_ret *trace) { }
 static void irqsoff_trace_open(struct trace_iterator *iter) { }
 static void irqsoff_trace_close(struct trace_iterator *iter) { }
 
 #ifdef CONFIG_FUNCTION_TRACER
+static void irqsoff_graph_return(struct ftrace_graph_ret *trace) { }
 static void irqsoff_print_header(struct seq_file *s)
 {
 	trace_default_header(s);
@@ -507,6 +508,9 @@ void trace_preempt_off(unsigned long a0, unsigned long a1)
 }
 #endif /* CONFIG_PREEMPT_TRACER */
 
+#ifdef CONFIG_FUNCTION_TRACER
+static bool function_enabled;
+
 static int register_irqsoff_function(struct trace_array *tr, int graph, int set)
 {
 	int ret;
@@ -540,21 +544,35 @@ static void unregister_irqsoff_function(struct trace_array *tr, int graph)
 	function_enabled = false;
 }
 
-static int irqsoff_function_set(struct trace_array *tr, int set)
+static int irqsoff_function_set(struct trace_array *tr, u32 mask, int set)
 {
+	if (!(mask & TRACE_ITER_FUNCTION))
+		return 0;
+
 	if (set)
 		register_irqsoff_function(tr, is_graph(), 1);
 	else
 		unregister_irqsoff_function(tr, is_graph());
+	return 1;
+}
+#else
+static int register_irqsoff_function(struct trace_array *tr, int graph, int set)
+{
 	return 0;
 }
+static void unregister_irqsoff_function(struct trace_array *tr, int graph) { }
+static inline int irqsoff_function_set(struct trace_array *tr, u32 mask, int set)
+{
+	return 0;
+}
+#endif /* CONFIG_FUNCTION_TRACER */
 
 static int irqsoff_flag_changed(struct trace_array *tr, u32 mask, int set)
 {
 	struct tracer *tracer = tr->current_trace;
 
-	if (mask & TRACE_ITER_FUNCTION)
+	if (irqsoff_function_set(tr, mask, set))
-		return irqsoff_function_set(tr, set);
+		return 0;
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 	if (mask & TRACE_ITER_DISPLAY_GRAPH)

kernel/trace/trace_sched_wakeup.c

@@ -34,11 +34,8 @@ static arch_spinlock_t wakeup_lock =
 
 static void wakeup_reset(struct trace_array *tr);
 static void __wakeup_reset(struct trace_array *tr);
-static int wakeup_graph_entry(struct ftrace_graph_ent *trace);
-static void wakeup_graph_return(struct ftrace_graph_ret *trace);
 
 static int save_flags;
-static bool function_enabled;
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 static int wakeup_display_graph(struct trace_array *tr, int set);
@@ -46,7 +43,7 @@ static int wakeup_display_graph(struct trace_array *tr, int set);
 #else
 static inline int wakeup_display_graph(struct trace_array *tr, int set)
 {
-	return -EINVAL;
+	return 0;
 }
 # define is_graph() false
 #endif
@@ -54,6 +51,11 @@ static inline int wakeup_display_graph(struct trace_array *tr, int set)
 
 #ifdef CONFIG_FUNCTION_TRACER
 
+static int wakeup_graph_entry(struct ftrace_graph_ent *trace);
+static void wakeup_graph_return(struct ftrace_graph_ret *trace);
+
+static bool function_enabled;
+
 /*
  * Prologue for the wakeup function tracers.
  *
@@ -123,7 +125,6 @@ wakeup_tracer_call(unsigned long ip, unsigned long parent_ip,
 	atomic_dec(&data->disabled);
 	preempt_enable_notrace();
 }
-#endif /* CONFIG_FUNCTION_TRACER */
 
 static int register_wakeup_function(struct trace_array *tr, int graph, int set)
 {
@@ -158,21 +159,35 @@ static void unregister_wakeup_function(struct trace_array *tr, int graph)
 	function_enabled = false;
 }
 
-static int wakeup_function_set(struct trace_array *tr, int set)
+static int wakeup_function_set(struct trace_array *tr, u32 mask, int set)
 {
+	if (!(mask & TRACE_ITER_FUNCTION))
+		return 0;
+
 	if (set)
 		register_wakeup_function(tr, is_graph(), 1);
 	else
 		unregister_wakeup_function(tr, is_graph());
+	return 1;
+}
+#else
+static int register_wakeup_function(struct trace_array *tr, int graph, int set)
+{
 	return 0;
 }
+static void unregister_wakeup_function(struct trace_array *tr, int graph) { }
+static int wakeup_function_set(struct trace_array *tr, u32 mask, int set)
+{
+	return 0;
+}
+#endif /* CONFIG_FUNCTION_TRACER */
 
 static int wakeup_flag_changed(struct trace_array *tr, u32 mask, int set)
 {
 	struct tracer *tracer = tr->current_trace;
 
-	if (mask & TRACE_ITER_FUNCTION)
+	if (wakeup_function_set(tr, mask, set))
-		return wakeup_function_set(tr, set);
+		return 0;
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 	if (mask & TRACE_ITER_DISPLAY_GRAPH)
@@ -302,21 +317,20 @@ __trace_function(struct trace_array *tr,
 #else
 #define __trace_function trace_function
 
-static int wakeup_graph_entry(struct ftrace_graph_ent *trace)
-{
-	return -1;
-}
-
 static enum print_line_t wakeup_print_line(struct trace_iterator *iter)
 {
 	return TRACE_TYPE_UNHANDLED;
 }
 
-static void wakeup_graph_return(struct ftrace_graph_ret *trace) { }
 static void wakeup_trace_open(struct trace_iterator *iter) { }
 static void wakeup_trace_close(struct trace_iterator *iter) { }
 
 #ifdef CONFIG_FUNCTION_TRACER
+static int wakeup_graph_entry(struct ftrace_graph_ent *trace)
+{
+	return -1;
+}
+static void wakeup_graph_return(struct ftrace_graph_ret *trace) { }
 static void wakeup_print_header(struct seq_file *s)
 {
 	trace_default_header(s);