From db365e5b2e30a6a04b4876ddb6a66c6319896b0a Mon Sep 17 00:00:00 2001
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Mon, 24 Jun 2019 18:29:13 +0200
Subject: [PATCH 458/518] rcu: Don't allow to change rcu_normal_after_boot on
 RT

[ Upstream commit c6c058c10577815a2491ce661876cff00a4c3b15 ]

On RT rcu_normal_after_boot is enabled by default.
Don't allow to disable it on RT because the "expedited rcu" would
introduce latency spikes.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
---
 kernel/rcu/update.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index 2006a09680aaa..307592810f6bc 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -67,7 +67,9 @@ module_param(rcu_expedited, int, 0);
 extern int rcu_normal; /* from sysctl */
 module_param(rcu_normal, int, 0);
 static int rcu_normal_after_boot = IS_ENABLED(CONFIG_PREEMPT_RT_FULL);
+#ifndef CONFIG_PREEMPT_RT_FULL
 module_param(rcu_normal_after_boot, int, 0);
+#endif
 #endif /* #ifndef CONFIG_TINY_RCU */
 
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
-- 
2.41.0

