rcu: Stopgap fix for synchronize_rcu_expedited() for TREE_PREEMPT_RCU

For the short term, map synchronize_rcu_expedited() to
synchronize_rcu() for TREE_PREEMPT_RCU and to
synchronize_sched_expedited() for TREE_RCU.

Longer term, there needs to be a real expedited grace period for
TREE_PREEMPT_RCU, but candidate patches to date are considerably
more complex and intrusive.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
Cc: npiggin@suse.de
Cc: jens.axboe@oracle.com
LKML-Reference: <12555405592331-git-send-email->
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index 46e9ab3..9642c6b 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -76,11 +76,7 @@
 
 extern void call_rcu_sched(struct rcu_head *head,
 			   void (*func)(struct rcu_head *rcu));
-
-static inline void synchronize_rcu_expedited(void)
-{
-	synchronize_sched_expedited();
-}
+extern void synchronize_rcu_expedited(void);
 
 static inline void synchronize_rcu_bh_expedited(void)
 {