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>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index eaacd3a..2a595cf 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2987,6 +2987,11 @@
 	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.