diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 8aa5321..f90ca16 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -328,7 +328,7 @@
 unsigned long trace_flags = TRACE_ITER_PRINT_PARENT | TRACE_ITER_PRINTK |
 	TRACE_ITER_ANNOTATE | TRACE_ITER_CONTEXT_INFO | TRACE_ITER_SLEEP_TIME |
 	TRACE_ITER_GRAPH_TIME | TRACE_ITER_RECORD_CMD | TRACE_ITER_OVERWRITE |
-	TRACE_ITER_IRQ_INFO | TRACE_ITER_MARKERS;
+	TRACE_ITER_IRQ_INFO | TRACE_ITER_MARKERS | TRACE_ITER_FUNCTION;
 
 /**
  * tracing_on - enable tracing buffers
@@ -635,6 +635,7 @@
 	"disable_on_free",
 	"irq-info",
 	"markers",
+	"function-trace",
 	NULL
 };
 
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 0e430b4..5cc5236 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -867,6 +867,7 @@
 	TRACE_ITER_STOP_ON_FREE		= 0x400000,
 	TRACE_ITER_IRQ_INFO		= 0x800000,
 	TRACE_ITER_MARKERS		= 0x1000000,
+	TRACE_ITER_FUNCTION		= 0x2000000,
 };
 
 /*
diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index 5aa40ab..b19d065 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -33,6 +33,7 @@
 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);
@@ -528,15 +529,60 @@
 }
 #endif /* CONFIG_PREEMPT_TRACER */
 
-static int start_irqsoff_tracer(struct trace_array *tr, int graph)
+static int register_irqsoff_function(int graph, int set)
 {
-	int ret = 0;
+	int ret;
 
-	if (!graph)
-		ret = register_ftrace_function(&trace_ops);
-	else
+	/* 'set' is set if TRACE_ITER_FUNCTION is about to be set */
+	if (function_enabled || (!set && !(trace_flags & TRACE_ITER_FUNCTION)))
+		return 0;
+
+	if (graph)
 		ret = register_ftrace_graph(&irqsoff_graph_return,
 					    &irqsoff_graph_entry);
+	else
+		ret = register_ftrace_function(&trace_ops);
+
+	if (!ret)
+		function_enabled = true;
+
+	return ret;
+}
+
+static void unregister_irqsoff_function(int graph)
+{
+	if (!function_enabled)
+		return;
+
+	if (graph)
+		unregister_ftrace_graph();
+	else
+		unregister_ftrace_function(&trace_ops);
+
+	function_enabled = false;
+}
+
+static void irqsoff_function_set(int set)
+{
+	if (set)
+		register_irqsoff_function(is_graph(), 1);
+	else
+		unregister_irqsoff_function(is_graph());
+}
+
+static int irqsoff_flag_changed(struct tracer *tracer, u32 mask, int set)
+{
+	if (mask & TRACE_ITER_FUNCTION)
+		irqsoff_function_set(set);
+
+	return trace_keep_overwrite(tracer, mask, set);
+}
+
+static int start_irqsoff_tracer(struct trace_array *tr, int graph)
+{
+	int ret;
+
+	ret = register_irqsoff_function(graph, 0);
 
 	if (!ret && tracing_is_enabled())
 		tracer_enabled = 1;
@@ -550,10 +596,7 @@
 {
 	tracer_enabled = 0;
 
-	if (!graph)
-		unregister_ftrace_function(&trace_ops);
-	else
-		unregister_ftrace_graph();
+	unregister_irqsoff_function(graph);
 }
 
 static void __irqsoff_tracer_init(struct trace_array *tr)
@@ -615,7 +658,7 @@
 	.print_line     = irqsoff_print_line,
 	.flags		= &tracer_flags,
 	.set_flag	= irqsoff_set_flag,
-	.flag_changed	= trace_keep_overwrite,
+	.flag_changed	= irqsoff_flag_changed,
 #ifdef CONFIG_FTRACE_SELFTEST
 	.selftest    = trace_selftest_startup_irqsoff,
 #endif
@@ -649,7 +692,7 @@
 	.print_line     = irqsoff_print_line,
 	.flags		= &tracer_flags,
 	.set_flag	= irqsoff_set_flag,
-	.flag_changed	= trace_keep_overwrite,
+	.flag_changed	= irqsoff_flag_changed,
 #ifdef CONFIG_FTRACE_SELFTEST
 	.selftest    = trace_selftest_startup_preemptoff,
 #endif
@@ -685,7 +728,7 @@
 	.print_line     = irqsoff_print_line,
 	.flags		= &tracer_flags,
 	.set_flag	= irqsoff_set_flag,
-	.flag_changed	= trace_keep_overwrite,
+	.flag_changed	= irqsoff_flag_changed,
 #ifdef CONFIG_FTRACE_SELFTEST
 	.selftest    = trace_selftest_startup_preemptirqsoff,
 #endif
diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index c16f8cd..fee77e1 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -37,6 +37,7 @@
 static void wakeup_graph_return(struct ftrace_graph_ret *trace);
 
 static int save_flags;
+static bool function_enabled;
 
 #define TRACE_DISPLAY_GRAPH     1
 
@@ -134,15 +135,60 @@
 };
 #endif /* CONFIG_FUNCTION_TRACER */
 
+static int register_wakeup_function(int graph, int set)
+{
+	int ret;
+
+	/* 'set' is set if TRACE_ITER_FUNCTION is about to be set */
+	if (function_enabled || (!set && !(trace_flags & TRACE_ITER_FUNCTION)))
+		return 0;
+
+	if (graph)
+		ret = register_ftrace_graph(&wakeup_graph_return,
+					    &wakeup_graph_entry);
+	else
+		ret = register_ftrace_function(&trace_ops);
+
+	if (!ret)
+		function_enabled = true;
+
+	return ret;
+}
+
+static void unregister_wakeup_function(int graph)
+{
+	if (!function_enabled)
+		return;
+
+	if (graph)
+		unregister_ftrace_graph();
+	else
+		unregister_ftrace_function(&trace_ops);
+
+	function_enabled = false;
+}
+
+static void wakeup_function_set(int set)
+{
+	if (set)
+		register_wakeup_function(is_graph(), 1);
+	else
+		unregister_wakeup_function(is_graph());
+}
+
+static int wakeup_flag_changed(struct tracer *tracer, u32 mask, int set)
+{
+	if (mask & TRACE_ITER_FUNCTION)
+		wakeup_function_set(set);
+
+	return trace_keep_overwrite(tracer, mask, set);
+}
+
 static int start_func_tracer(int graph)
 {
 	int ret;
 
-	if (!graph)
-		ret = register_ftrace_function(&trace_ops);
-	else
-		ret = register_ftrace_graph(&wakeup_graph_return,
-					    &wakeup_graph_entry);
+	ret = register_wakeup_function(graph, 0);
 
 	if (!ret && tracing_is_enabled())
 		tracer_enabled = 1;
@@ -156,10 +202,7 @@
 {
 	tracer_enabled = 0;
 
-	if (!graph)
-		unregister_ftrace_function(&trace_ops);
-	else
-		unregister_ftrace_graph();
+	unregister_wakeup_function(graph);
 }
 
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
@@ -600,7 +643,7 @@
 	.print_line	= wakeup_print_line,
 	.flags		= &tracer_flags,
 	.set_flag	= wakeup_set_flag,
-	.flag_changed	= trace_keep_overwrite,
+	.flag_changed	= wakeup_flag_changed,
 #ifdef CONFIG_FTRACE_SELFTEST
 	.selftest    = trace_selftest_startup_wakeup,
 #endif
@@ -622,7 +665,7 @@
 	.print_line	= wakeup_print_line,
 	.flags		= &tracer_flags,
 	.set_flag	= wakeup_set_flag,
-	.flag_changed	= trace_keep_overwrite,
+	.flag_changed	= wakeup_flag_changed,
 #ifdef CONFIG_FTRACE_SELFTEST
 	.selftest    = trace_selftest_startup_wakeup,
 #endif