6 files changed, 52 insertions, 9 deletions
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 0f271c4..4231a3d 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1602,6 +1602,23 @@ core_initcall(ftrace_dynamic_init);
 #endif /* CONFIG_DYNAMIC_FTRACE */
 
 /**
+ * ftrace_kill_atomic - kill ftrace from critical sections
+ *
+ * This function should be used by panic code. It stops ftrace
+ * but in a not so nice way. If you need to simply kill ftrace
+ * from a non-atomic section, use ftrace_kill.
+ */
+void ftrace_kill_atomic(void)
+{
+	ftrace_disabled = 1;
+	ftrace_enabled = 0;
+#ifdef CONFIG_DYNAMIC_FTRACE
+	ftraced_suspend = -1;
+#endif
+	clear_ftrace_function();
+}
+
+/**
  * ftrace_kill - totally shutdown ftrace
  *
  * This is a safety measure. If something was detected that seems
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index e46de64..868e121 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -96,6 +96,9 @@ static DEFINE_PER_CPU(struct trace_array_cpu, max_data);
 /* tracer_enabled is used to toggle activation of a tracer */
 static int			tracer_enabled = 1;
 
+/* function tracing enabled */
+int				ftrace_function_enabled;
+
 /*
  * trace_nr_entries is the number of entries that is allocated
  * for a buffer. Note, the number of entries is always rounded
@@ -134,6 +137,7 @@ static notrace void no_trace_init(struct trace_array *tr)
 {
 	int cpu;
 
+	ftrace_function_enabled = 0;
 	if(tr->ctrl)
 		for_each_online_cpu(cpu)
 			tracing_reset(tr->data[cpu]);
@@ -1027,7 +1031,7 @@ function_trace_call(unsigned long ip, unsigned long parent_ip)
 	long disabled;
 	int cpu;
 
-	if (unlikely(!tracer_enabled))
+	if (unlikely(!ftrace_function_enabled))
 		return;
 
 	if (skip_trace(ip))
@@ -1052,11 +1056,15 @@ static struct ftrace_ops trace_ops __read_mostly =
 
 void tracing_start_function_trace(void)
 {
+	ftrace_function_enabled = 0;
 	register_ftrace_function(&trace_ops);
+	if (tracer_enabled)
+		ftrace_function_enabled = 1;
 }
 
 void tracing_stop_function_trace(void)
 {
+	ftrace_function_enabled = 0;
 	unregister_ftrace_function(&trace_ops);
 }
 #endif
@@ -1383,7 +1391,7 @@ print_trace_header(struct seq_file *m, struct trace_iterator *iter)
 		   "server",
 #elif defined(CONFIG_PREEMPT_VOLUNTARY)
 		   "desktop",
-#elif defined(CONFIG_PREEMPT_DESKTOP)
+#elif defined(CONFIG_PREEMPT)
 		   "preempt",
 #else
 		   "unknown",
@@ -1892,8 +1900,10 @@ __tracing_open(struct inode *inode, struct file *file, int *ret)
 		m->private = iter;
 
 		/* stop the trace while dumping */
-		if (iter->tr->ctrl)
+		if (iter->tr->ctrl) {
 			tracer_enabled = 0;
+			ftrace_function_enabled = 0;
+		}
 
 		if (iter->trace && iter->trace->open)
 			iter->trace->open(iter);
@@ -1926,8 +1936,14 @@ int tracing_release(struct inode *inode, struct file *file)
 		iter->trace->close(iter);
 
 	/* reenable tracing if it was previously enabled */
-	if (iter->tr->ctrl)
+	if (iter->tr->ctrl) {
 		tracer_enabled = 1;
+		/*
+		 * It is safe to enable function tracing even if it
+		 * isn't used
+		 */
+		ftrace_function_enabled = 1;
+	}
 	mutex_unlock(&trace_types_lock);
 
 	seq_release(inode, file);
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 8cb215b..f69f867 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -223,8 +223,6 @@ void trace_function(struct trace_array *tr,
 		    unsigned long parent_ip,
 		    unsigned long flags);
 
-void tracing_start_function_trace(void);
-void tracing_stop_function_trace(void);
 void tracing_start_cmdline_record(void);
 void tracing_stop_cmdline_record(void);
 int register_tracer(struct tracer *type);
@@ -241,6 +239,14 @@ void update_max_tr_single(struct trace_array *tr,
 
 extern cycle_t ftrace_now(int cpu);
 
+#ifdef CONFIG_FTRACE
+void tracing_start_function_trace(void);
+void tracing_stop_function_trace(void);
+#else
+# define tracing_start_function_trace()		do { } while (0)
+# define tracing_stop_function_trace()		do { } while (0)
+#endif
+
 #ifdef CONFIG_CONTEXT_SWITCH_TRACER
 typedef void
 (*tracer_switch_func_t)(void *private,
diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
index 7ee7dcd..3121448 100644
--- a/kernel/trace/trace_functions.c
+++ b/kernel/trace/trace_functions.c
@@ -28,7 +28,10 @@ static void function_reset(struct trace_array *tr)
 
 static void start_function_trace(struct trace_array *tr)
 {
+	tr->cpu = get_cpu();
 	function_reset(tr);
+	put_cpu();
+
 	tracing_start_cmdline_record();
 	tracing_start_function_trace();
 }
diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_switch.c
index 93a6620..cb817a2 100644
--- a/kernel/trace/trace_sched_switch.c
+++ b/kernel/trace/trace_sched_switch.c
@@ -227,14 +227,14 @@ void tracing_stop_cmdline_record(void)
 static void start_sched_trace(struct trace_array *tr)
 {
 	sched_switch_reset(tr);
-	tracer_enabled = 1;
 	tracing_start_cmdline_record();
+	tracer_enabled = 1;
 }
 
 static void stop_sched_trace(struct trace_array *tr)
 {
-	tracing_stop_cmdline_record();
 	tracer_enabled = 0;
+	tracing_stop_cmdline_record();
 }
 
 static void sched_switch_trace_init(struct trace_array *tr)
diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index bf7e91c..3c8d61d 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -352,9 +352,10 @@ static void start_wakeup_tracer(struct trace_array *tr)
 	 */
 	smp_wmb();
 
-	tracer_enabled = 1;
 	register_ftrace_function(&trace_ops);
 
+	tracer_enabled = 1;
+
 	return;
 fail_deprobe_wake_new:
 	marker_probe_unregister("kernel_sched_wakeup_new",