tracing/function-graph-tracer: provide a selftest for the function graph tracer

Making it more easy to do a basic regression test for this tracer.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

3 files changed, 55 insertions, 0 deletions

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index b9838f4a6929..a011ec062225 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -500,6 +500,8 @@ extern int DYN_FTRACE_TEST_NAME(void);
 #ifdef CONFIG_FTRACE_STARTUP_TEST
 extern int trace_selftest_startup_function(struct tracer *trace,
                                            struct trace_array *tr);
+extern int trace_selftest_startup_function_graph(struct tracer *trace,
+                                                 struct trace_array *tr);
 extern int trace_selftest_startup_irqsoff(struct tracer *trace,
                                           struct trace_array *tr);
 extern int trace_selftest_startup_preemptoff(struct tracer *trace,
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 222f97d336a6..88f8d9d80a93 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -750,6 +750,9 @@ static struct tracer graph_trace __read_mostly = {
         .print_line     = print_graph_function,
         .print_header   = print_graph_headers,
         .flags          = &tracer_flags,
+#ifdef CONFIG_FTRACE_SELFTEST
+        .selftest       = trace_selftest_startup_function_graph,
+#endif
 };
 
 static __init int init_graph_trace(void)
diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c
index 445700e51f6d..0c9aa1457e51 100644
--- a/kernel/trace/trace_selftest.c
+++ b/kernel/trace/trace_selftest.c
@@ -13,6 +13,8 @@ static inline int trace_valid_entry(struct trace_entry *entry)
         case TRACE_PRINT:
         case TRACE_SPECIAL:
         case TRACE_BRANCH:
+        case TRACE_GRAPH_ENT:
+        case TRACE_GRAPH_RET:
                 return 1;
         }
         return 0;
@@ -227,6 +229,54 @@ trace_selftest_startup_function(struct tracer *trace, struct trace_array *tr)
 }
 #endif /* CONFIG_FUNCTION_TRACER */
 
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+/*
+ * Pretty much the same than for the function tracer from which the selftest
+ * has been borrowed.
+ */
+int
+trace_selftest_startup_function_graph(struct tracer *trace,
+                                        struct trace_array *tr)
+{
+        int ret;
+        unsigned long count;
+
+        ret = tracer_init(trace, tr);
+        if (ret) {
+                warn_failed_init_tracer(trace, ret);
+                goto out;
+        }
+
+        /* Sleep for a 1/10 of a second */
+        msleep(100);
+
+        tracing_stop();
+
+        /* check the trace buffer */
+        ret = trace_test_buffer(tr, &count);
+
+        trace->reset(tr);
+        tracing_start();
+
+        if (!ret && !count) {
+                printk(KERN_CONT ".. no entries found ..");
+                ret = -1;
+                goto out;
+        }
+
+        /* Don't test dynamic tracing, the function tracer already did */
+
+out:
+        /* Stop it if we failed */
+        if (ret)
+                ftrace_graph_stop();
+
+        return ret;
+}
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
+
+
 #ifdef CONFIG_IRQSOFF_TRACER
 int
 trace_selftest_startup_irqsoff(struct tracer *trace, struct trace_array *tr)