tracing: Prevent deleting instances when they are being read

Add a ref count to the trace_array structure and prevent removal
of instances that have open descriptors.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 1a456c291a07..f4931821a966 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -219,6 +219,7 @@ struct trace_array {
         struct list_head        systems;
         struct list_head        events;
         struct task_struct      *waiter;
+        int                     ref;
 };
 
 enum {