[PATCH 2/2] rcu-tasks: add RCU-tasks self tests

["Uladzislau Rezki (Sony)" <urezki@xxxxxxxxx>]

Add self tests for checking of RCU-tasks API functionality.
It covers:
    - wait API functions;
    - invoking/completion call_rcu_tasks*().

Self-tests are run when CONFIG_PROVE_RCU kernel parameter is set.

Signed-off-by: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx>
---
 kernel/rcu/tasks.h | 44 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index 67a162949763..9407772780c1 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -1225,6 +1225,16 @@ void show_rcu_tasks_gp_kthreads(void)
 }
 #endif /* #ifndef CONFIG_TINY_RCU */
 
+static struct rcu_head rhp;
+static int rcu_execurted_test_counter;
+static int rcu_run_test_counter;
+
+static void test_rcu_tasks_callback(struct rcu_head *r)
+{
+	pr_info("RCU-tasks test callback executed %d\n",
+		++rcu_execurted_test_counter);
+}
+
 void __init rcu_init_tasks_generic(void)
 {
 #ifdef CONFIG_TASKS_RCU
@@ -1238,7 +1248,41 @@ void __init rcu_init_tasks_generic(void)
 #ifdef CONFIG_TASKS_TRACE_RCU
 	rcu_spawn_tasks_trace_kthread();
 #endif
+
+	if (IS_ENABLED(CONFIG_PROVE_RCU)) {
+		pr_info("Running RCU-tasks wait API self tests\n");
+#ifdef CONFIG_TASKS_RCU
+		rcu_run_test_counter++;
+		call_rcu_tasks(&rhp, test_rcu_tasks_callback);
+		synchronize_rcu_tasks();
+#endif
+
+#ifdef CONFIG_TASKS_RUDE_RCU
+		rcu_run_test_counter++;
+		call_rcu_tasks_trace(&rhp, test_rcu_tasks_callback);
+		synchronize_rcu_tasks_rude();
+#endif
+
+#ifdef CONFIG_TASKS_TRACE_RCU
+		rcu_run_test_counter++;
+		call_rcu_tasks_trace(&rhp, test_rcu_tasks_callback);
+		synchronize_rcu_tasks_trace();
+#endif
+	}
+}
+
+static int rcu_tasks_verify_self_tests(void)
+{
+	int ret = 0;
+
+	if (rcu_run_test_counter != rcu_execurted_test_counter) {
+		WARN_ON(1);
+		ret = -1;
+	}
+
+	return ret;
 }
+late_initcall(rcu_tasks_verify_self_tests);
 
 #else /* #ifdef CONFIG_TASKS_RCU_GENERIC */
 static inline void rcu_tasks_bootup_oddness(void) {}
-- 
2.20.1