tracing: Add helper function tracing_is_disabled()

This patch creates the function 'tracing_is_disabled', which
can be used outside of trace.c.

Link: http://lkml.kernel.org/r/1382141754-12155-1-git-send-email-geyslan@gmail.com

Signed-off-by: Geyslan G. Bem <geyslan@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

kernel/trace/trace.c

@@ -2987,6 +2987,11 @@ int tracing_open_generic(struct inode *inode, struct file *filp)
 	return 0;
 }
 
+bool tracing_is_disabled(void)
+{
+	return (tracing_disabled) ? true: false;
+}
+
 /*
  * Open and update trace_array ref count.
  * Must have the current trace_array passed to it.

kernel/trace/trace.h

@@ -514,6 +514,7 @@ void tracing_reset_online_cpus(struct trace_buffer *buf);
 void tracing_reset_current(int cpu);
 void tracing_reset_all_online_cpus(void);
 int tracing_open_generic(struct inode *inode, struct file *filp);
+bool tracing_is_disabled(void);
 struct dentry *trace_create_file(const char *name,
 				 umode_t mode,
 				 struct dentry *parent,