rcu: need barrier() in UP synchronize_sched_expedited()

If synchronize_sched_expedited() is ever to be called from within
kernel/sched.c in a !SMP PREEMPT kernel, the !SMP implementation needs
a barrier().

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/kernel/sched.c b/kernel/sched.c
index 155a16d..fbaf312 100644 (file)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -8932,6 +8932,7 @@ struct cgroup_subsys cpuacct_subsys = {
 
 void synchronize_sched_expedited(void)
 {
+       barrier();
 }
 EXPORT_SYMBOL_GPL(synchronize_sched_expedited);