rcu: Define RCU-sched API in terms of RCU for Tree RCU PREEMPT builds

Now that RCU-preempt knows about preemption disabling, its implementation
of synchronize_rcu() works for synchronize_sched(), and likewise for the
other RCU-sched update-side API members.  This commit therefore confines
the RCU-sched update-side code to CONFIG_PREEMPT=n builds, and defines
RCU-sched's update-side API members in terms of those of RCU-preempt.

This means that any given build of the Linux kernel has only one
update-side flavor of RCU, namely RCU-preempt for CONFIG_PREEMPT=y builds
and RCU-sched for CONFIG_PREEMPT=n builds.  This in turn means that kernels
built with CONFIG_RCU_NOCB_CPU=y have only one rcuo kthread per CPU.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Andi Kleen <ak@linux.intel.com>

1 files changed, 6 insertions, 1 deletions

diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index f7a41323aa54..0c44720f0e84 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -45,14 +45,19 @@ static inline void rcu_virt_note_context_switch(int cpu)
 	rcu_note_context_switch(false);
 }
 
+void synchronize_rcu(void);
 static inline void synchronize_rcu_bh(void)
 {
 	synchronize_rcu();
 }
 
-void synchronize_sched_expedited(void);
 void synchronize_rcu_expedited(void);
 
+static inline void synchronize_sched_expedited(void)
+{
+	synchronize_rcu_expedited();
+}
+
 void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func);
 
 /**