3 files changed, 34 insertions, 6 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 9531fdd..e97c29a 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -853,6 +853,7 @@ static void __trace_function_return(struct trace_array *tr,
 	entry->parent_ip	= trace->ret;
 	entry->rettime		= trace->rettime;
 	entry->calltime		= trace->calltime;
+	entry->overrun		= trace->overrun;
 	ring_buffer_unlock_commit(global_trace.buffer, event, irq_flags);
 }
 #endif
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 9d22618..2cb12fd 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -60,6 +60,7 @@ struct ftrace_ret_entry {
 	unsigned long		parent_ip;
 	unsigned long long	calltime;
 	unsigned long long	rettime;
+	unsigned long		overrun;
 };
 extern struct tracer boot_tracer;
 
diff --git a/kernel/trace/trace_functions_return.c b/kernel/trace/trace_functions_return.c
index a68564a..e00d645 100644
--- a/kernel/trace/trace_functions_return.c
+++ b/kernel/trace/trace_functions_return.c
@@ -14,6 +14,19 @@
 #include "trace.h"
 
 
+#define TRACE_RETURN_PRINT_OVERRUN	0x1
+static struct tracer_opt trace_opts[] = {
+	/* Display overruns or not */
+	{ TRACER_OPT(overrun, TRACE_RETURN_PRINT_OVERRUN) },
+	{ } /* Empty entry */
+};
+
+static struct tracer_flags tracer_flags = {
+	.val = 0, /* Don't display overruns by default */
+	.opts = trace_opts
+};
+
+
 static int return_trace_init(struct trace_array *tr)
 {
 	int cpu;
@@ -42,26 +55,39 @@ print_return_function(struct trace_iterator *iter)
 		ret = trace_seq_printf(s, "%pF -> ", (void *)field->parent_ip);
 		if (!ret)
 			return TRACE_TYPE_PARTIAL_LINE;
+
 		ret = seq_print_ip_sym(s, field->ip,
 					trace_flags & TRACE_ITER_SYM_MASK);
 		if (!ret)
 			return TRACE_TYPE_PARTIAL_LINE;
-		ret = trace_seq_printf(s, " (%llu ns)\n",
+
+		ret = trace_seq_printf(s, " (%llu ns)",
 					field->rettime - field->calltime);
 		if (!ret)
 			return TRACE_TYPE_PARTIAL_LINE;
-		else
-			return TRACE_TYPE_HANDLED;
+
+		if (tracer_flags.val & TRACE_RETURN_PRINT_OVERRUN) {
+			ret = trace_seq_printf(s, " (Overruns: %lu)",
+						field->overrun);
+			if (!ret)
+				return TRACE_TYPE_PARTIAL_LINE;
+		}
+
+		ret = trace_seq_printf(s, "\n");
+		if (!ret)
+			return TRACE_TYPE_PARTIAL_LINE;
+
+		return TRACE_TYPE_HANDLED;
 	}
 	return TRACE_TYPE_UNHANDLED;
 }
 
-static struct tracer return_trace __read_mostly =
-{
+static struct tracer return_trace __read_mostly = {
 	.name	     = "return",
 	.init	     = return_trace_init,
 	.reset	     = return_trace_reset,
-	.print_line = print_return_function
+	.print_line = print_return_function,
+	.flags		= &tracer_flags,
 };
 
 static __init int init_return_trace(void)