ring-buffer: Check if buffer exists before polling

[firefly-linux-kernel-4.4.55.git] / kernel / trace / trace.h

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 20572ed88c5c3b791bef107aab7fbc1f3b0b44d1..aa0e736b72ac84d77a633ab8c83f8d1378883147 100644 (file)
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -224,6 +224,11 @@ enum {
 
 extern struct list_head ftrace_trace_arrays;
 
+extern struct mutex trace_types_lock;
+
+extern int trace_array_get(struct trace_array *tr);
+extern void trace_array_put(struct trace_array *tr);
+
 /*
  * The global tracer (top) should be the first trace array added,
  * but we check the flag anyway.
@@ -337,7 +342,7 @@ struct tracer {
        void                    (*stop)(struct trace_array *tr);
        void                    (*open)(struct trace_iterator *iter);
        void                    (*pipe_open)(struct trace_iterator *iter);
-       void                    (*wait_pipe)(struct trace_iterator *iter);
+       int                     (*wait_pipe)(struct trace_iterator *iter);
        void                    (*close)(struct trace_iterator *iter);
        void                    (*pipe_close)(struct trace_iterator *iter);
        ssize_t                 (*read)(struct trace_iterator *iter,
@@ -552,7 +557,7 @@ void trace_init_global_iter(struct trace_iterator *iter);
 
 void tracing_iter_reset(struct trace_iterator *iter, int cpu);
 
-void poll_wait_pipe(struct trace_iterator *iter);
+int poll_wait_pipe(struct trace_iterator *iter);
 
 void ftrace(struct trace_array *tr,
                            struct trace_array_cpu *data,