tracing: expand the ring buffers when an event is activated

[deliverable/linux.git] / kernel / trace / trace.c

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 0c1dc1850858b444e39c7368c399c2ccc2a119f5..35ee63ae41224627bee4a5bcd4cee8e4a8c67fa5 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2357,6 +2357,26 @@ static int tracing_resize_ring_buffer(unsigned long size)
        return ret;
 }
 
+/**
+ * tracing_update_buffers - used by tracing facility to expand ring buffers
+ *
+ * To save on memory when the tracing is never used on a system with it
+ * configured in. The ring buffers are set to a minimum size. But once
+ * a user starts to use the tracing facility, then they need to grow
+ * to their default size.
+ *
+ * This function is to be called when a tracer is about to be used.
+ */
+int tracing_update_buffers(void)
+{
+       int ret = 0;
+
+       if (!ring_buffer_expanded)
+               ret = tracing_resize_ring_buffer(trace_buf_size);
+
+       return ret;
+}
+
 struct trace_option_dentry;
 
 static struct trace_option_dentry *