tracing/ftrace: make nop tracer reset previous entries

If nop tracer is selected, some old entries from the previous tracer
could still be enqueued. Tracing have to be reset.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Steven Noonan <steven@uplinklabs.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 4 insertions, 0 deletions

diff --git a/kernel/trace/trace_nop.c b/kernel/trace/trace_nop.c
index dafaefb84038..9fb02c17ad0c 100644
--- a/kernel/trace/trace_nop.c
+++ b/kernel/trace/trace_nop.c
@@ -26,8 +26,12 @@ static void stop_nop_trace(struct trace_array *tr)
 
 static void nop_trace_init(struct trace_array *tr)
 {
+        int cpu;
         ctx_trace = tr;
 
+        for_each_online_cpu(cpu)
+                tracing_reset(tr->data[cpu]);
+
         if (tr->ctrl)
                 start_nop_trace(tr);
 }