trace: stop all recording to ring buffer on ftrace_dump

Impact: limit ftrace dump output

Currently ftrace_dump only calls ftrace_kill that is a fast way
to prevent the function tracer functions from being called (just sets
a flag and clears the function to call, nothing else). It is better
to also turn off any recording to the ring buffers as well.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 408c03f..dcb757f 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3110,6 +3110,7 @@
 	dump_ran = 1;
 
 	/* No turning back! */
+	tracing_off();
 	ftrace_kill();
 
 	for_each_tracing_cpu(cpu) {