tracing: do not update tracing_max_latency when tracer is stopped

The state of the function pair tracing_stop()/tracing_start() is
correctly considered when tracer data are updated. However, the global
and externally accessible variable tracing_max_latency is always updated
- even when tracing is stopped.

The update should only occur, if tracing was not stopped.

Signed-off-by: Carsten Emde <C.Emde@osadl.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 4 insertions, 2 deletions

diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index 06f8ea9e4b9..3aa7eaa2114 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -157,8 +157,10 @@ check_critical_timing(struct trace_array *tr,
 
         data->critical_end = parent_ip;
 
-        tracing_max_latency = delta;
-        update_max_tr_single(tr, current, cpu);
+        if (likely(!is_tracing_stopped())) {
+                tracing_max_latency = delta;
+                update_max_tr_single(tr, current, cpu);
+        }
 
         max_sequence++;