From: Sebastian Andrzej Siewior Date: Mon, 24 Jun 2019 18:29:13 +0200 Subject: [PATCH 272/290] 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=d907b0f62c7449b966af5924b51a0f409580d1b9 [ 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 Signed-off-by: Steven Rostedt (VMware) --- 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