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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Mon, 24 Jun 2019 18:29:13 +0200
Subject: [PATCH 267/353] rcu: Don't allow to change rcu_normal_after_boot on
 RT
Origin: https://git.kernel.org/cgit/linux/kernel/git/rt/linux-stable-rt.git/commit?id=67bcea9091d3ff86f96550f5d264ce29bce86c49

[ 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: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/rcu/update.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index 16d8dba23329..ed75addd3ccd 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -69,7 +69,9 @@ 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