tracing: Add disable_on_free option

Add a trace option to disable tracing on free. When this option is
set, a write into the free_buffer file will not only shrink the
ring buffer down to zero, but it will also disable tracing.

Cc: Vaibhav Nagarnaik <vnagarnaik@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 229f859..742f545 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -609,6 +609,7 @@
 	TRACE_ITER_GRAPH_TIME		= 0x80000,
 	TRACE_ITER_RECORD_CMD		= 0x100000,
 	TRACE_ITER_OVERWRITE		= 0x200000,
+	TRACE_ITER_STOP_ON_FREE		= 0x400000,
 };
 
 /*