Both CONTEXT_TRACKING and CONTEXT_TRACKING_FORCE are currently defined
in kernel/rcu/kconfig, which might have made sense at some point, but
no longer does given that RCU refers to neither of these Kconfig options.

Therefore move them to kernel/time/Kconfig, where the rest of the
NO_HZ_FULL Kconfig options live.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: https://lkml.kernel.org/r/20181220170525.GA12579@linux.ibm.com

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

This commit updates comments and help text to account for the fact that
RCU-bh update-side functions are now simple wrappers for their RCU or
RCU-sched counterparts.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

The actual use of TASKS_RCU is only when PREEMPT, otherwise RCU-sched
is used instead.  This commit therefore makes synchronize_rcu_tasks()
and call_rcu_tasks() available always, but mapped to synchronize_sched()
and call_rcu_sched(), respectively, when !PREEMPT.  This approach also
allows some #ifdefs to be removed from rcutorture.

Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Ingo Molnar <mingo@kernel.org>

Tiny RCU's job is to be tiny, so this commit removes its RCU CPU
stall warning code.  After this, there is no longer any need for
rcu_sched_ctrlblk and rcu_bh_ctrlblk to be in tiny_plugin.h, so this
commit also moves them to tiny.c.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

RCU's Kconfig options are scattered, and there are enough of them
that it would be good for them to be more centralized.  This commit
therefore extracts RCU's Kconfig options from init/Kconfig into a new
kernel/rcu/Kconfig file.

Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>