rcu: Shrink TINY_RCU by moving exit_rcu()

Now that TINY_PREEMPT_RCU is no more, exit_rcu() is always an empty
function.  But if TINY_RCU is going to have an empty function, it should
be in include/linux/rcutiny.h, where it does not bloat the kernel.
This commit therefore moves exit_rcu() out of kernel/rcupdate.c to
kernel/rcutree_plugin.h, and places a static inline empty function in
include/linux/rcutiny.h in order to shrink TINY_RCU a bit.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>

3 files changed, 6 insertions, 2 deletions

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 257b50f9d2dc..4b14bdc911d7 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -240,8 +240,6 @@ static inline void rcu_user_hooks_switch(struct task_struct *prev,
                                          struct task_struct *next) { }
 #endif /* CONFIG_RCU_USER_QS */
 
-extern void exit_rcu(void);
-
 /**
  * RCU_NONIDLE - Indicate idle-loop code that needs RCU readers
  * @a: Code that RCU needs to pay attention to.
diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
index 51230b63be93..e31005ee339e 100644
--- a/include/linux/rcutiny.h
+++ b/include/linux/rcutiny.h
@@ -119,6 +119,10 @@ static inline void rcu_cpu_stall_reset(void)
 {
 }
 
+static inline void exit_rcu(void)
+{
+}
+
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 extern int rcu_scheduler_active __read_mostly;
 extern void rcu_scheduler_starting(void);
diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index 3f1aa8f98666..226169d1bd2b 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -85,6 +85,8 @@ extern void rcu_force_quiescent_state(void);
 extern void rcu_bh_force_quiescent_state(void);
 extern void rcu_sched_force_quiescent_state(void);
 
+extern void exit_rcu(void);
+
 extern void rcu_scheduler_starting(void);
 extern int rcu_scheduler_active __read_mostly;