tracing: Move the tracing selftest code into its own function

Move the tracing startup selftest code into its own function and
when not enabled, always have that function succeed.

This makes the register_tracer() function much more readable.

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

kernel/trace/trace.c

@@ -818,6 +818,72 @@ static void default_wait_pipe(struct trace_iterator *iter)
 	ring_buffer_wait(iter->trace_buffer->buffer, iter->cpu_file);
 }
 
+#ifdef CONFIG_FTRACE_STARTUP_TEST
+static int run_tracer_selftest(struct tracer *type)
+{
+	struct trace_array *tr = &global_trace;
+	struct tracer *saved_tracer = tr->current_trace;
+	int ret;
+
+	if (!type->selftest || tracing_selftest_disabled)
+		return 0;
+
+	/*
+	 * Run a selftest on this tracer.
+	 * Here we reset the trace buffer, and set the current
+	 * tracer to be this tracer. The tracer can then run some
+	 * internal tracing to verify that everything is in order.
+	 * If we fail, we do not register this tracer.
+	 */
+	tracing_reset_online_cpus(&tr->trace_buffer);
+
+	tr->current_trace = type;
+
+#ifdef CONFIG_TRACER_MAX_TRACE
+	if (type->use_max_tr) {
+		/* If we expanded the buffers, make sure the max is expanded too */
+		if (ring_buffer_expanded)
+			ring_buffer_resize(tr->max_buffer.buffer, trace_buf_size,
+					   RING_BUFFER_ALL_CPUS);
+		tr->allocated_snapshot = true;
+	}
+#endif
+
+	/* the test is responsible for initializing and enabling */
+	pr_info("Testing tracer %s: ", type->name);
+	ret = type->selftest(type, tr);
+	/* the test is responsible for resetting too */
+	tr->current_trace = saved_tracer;
+	if (ret) {
+		printk(KERN_CONT "FAILED!\n");
+		/* Add the warning after printing 'FAILED' */
+		WARN_ON(1);
+		return -1;
+	}
+	/* Only reset on passing, to avoid touching corrupted buffers */
+	tracing_reset_online_cpus(&tr->trace_buffer);
+
+#ifdef CONFIG_TRACER_MAX_TRACE
+	if (type->use_max_tr) {
+		tr->allocated_snapshot = false;
+
+		/* Shrink the max buffer again */
+		if (ring_buffer_expanded)
+			ring_buffer_resize(tr->max_buffer.buffer, 1,
+					   RING_BUFFER_ALL_CPUS);
+	}
+#endif
+
+	printk(KERN_CONT "PASSED\n");
+	return 0;
+}
+#else
+static inline int run_tracer_selftest(struct tracer *type)
+{
+	return 0;
+}
+#endif /* CONFIG_FTRACE_STARTUP_TEST */
+
 /**
  * register_tracer - register a tracer with the ftrace system.
  * @type - the plugin for the tracer
@@ -863,61 +929,9 @@ int register_tracer(struct tracer *type)
 	if (!type->wait_pipe)
 		type->wait_pipe = default_wait_pipe;
 
-
-#ifdef CONFIG_FTRACE_STARTUP_TEST
-	if (type->selftest && !tracing_selftest_disabled) {
-		struct trace_array *tr = &global_trace;
-		struct tracer *saved_tracer = tr->current_trace;
-
-		/*
-		 * Run a selftest on this tracer.
-		 * Here we reset the trace buffer, and set the current
-		 * tracer to be this tracer. The tracer can then run some
-		 * internal tracing to verify that everything is in order.
-		 * If we fail, we do not register this tracer.
-		 */
-		tracing_reset_online_cpus(&tr->trace_buffer);
-
-		tr->current_trace = type;
-
-#ifdef CONFIG_TRACER_MAX_TRACE
-		if (type->use_max_tr) {
-			/* If we expanded the buffers, make sure the max is expanded too */
-			if (ring_buffer_expanded)
-				ring_buffer_resize(tr->max_buffer.buffer, trace_buf_size,
-						   RING_BUFFER_ALL_CPUS);
-			tr->allocated_snapshot = true;
-		}
-#endif
-
-		/* the test is responsible for initializing and enabling */
-		pr_info("Testing tracer %s: ", type->name);
-		ret = type->selftest(type, tr);
-		/* the test is responsible for resetting too */
-		tr->current_trace = saved_tracer;
-		if (ret) {
-			printk(KERN_CONT "FAILED!\n");
-			/* Add the warning after printing 'FAILED' */
-			WARN_ON(1);
-			goto out;
-		}
-		/* Only reset on passing, to avoid touching corrupted buffers */
-		tracing_reset_online_cpus(&tr->trace_buffer);
-
-#ifdef CONFIG_TRACER_MAX_TRACE
-		if (type->use_max_tr) {
-			tr->allocated_snapshot = false;
-
-			/* Shrink the max buffer again */
-			if (ring_buffer_expanded)
-				ring_buffer_resize(tr->max_buffer.buffer, 1,
-						   RING_BUFFER_ALL_CPUS);
-		}
-#endif
-
-		printk(KERN_CONT "PASSED\n");
-	}
-#endif
+	ret = run_tracer_selftest(type);
+	if (ret < 0)
+		goto out;
 
 	type->next = trace_types;
 	trace_types = type;