sched/cpuacct: Add cpuacct_init()

So we don't open-coded initialization of cpuacct in core.c.
Signed-off-by: NLi Zefan <lizefan@huawei.com>
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/51553687.1060906@huawei.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

kernel/sched/core.c

@@ -6936,12 +6936,8 @@ void __init sched_init(void)
 
 #endif /* CONFIG_CGROUP_SCHED */
 
-#ifdef CONFIG_CGROUP_CPUACCT
-	root_cpuacct.cpustat = &kernel_cpustat;
-	root_cpuacct.cpuusage = alloc_percpu(u64);
-	/* Too early, not expected to fail */
-	BUG_ON(!root_cpuacct.cpuusage);
-#endif
+	cpuacct_init();
+
 	for_each_possible_cpu(i) {
 		struct rq *rq;
 

kernel/sched/cpuacct.c

@@ -218,6 +218,13 @@ void cpuacct_charge(struct task_struct *tsk, u64 cputime)
 	rcu_read_unlock();
 }
 
+void __init cpuacct_init(void)
+{
+	root_cpuacct.cpustat = &kernel_cpustat;
+	root_cpuacct.cpuusage = alloc_percpu(u64);
+	BUG_ON(!root_cpuacct.cpuusage); /* Too early, not expected to fail */
+}
+
 struct cgroup_subsys cpuacct_subsys = {
 	.name = "cpuacct",
 	.css_alloc = cpuacct_css_alloc,

kernel/sched/cpuacct.h

@@ -41,10 +41,15 @@ static inline struct cpuacct *parent_ca(struct cpuacct *ca)
 	return cgroup_ca(ca->css.cgroup->parent);
 }
 
+extern void cpuacct_init(void);
 extern void cpuacct_charge(struct task_struct *tsk, u64 cputime);
 
 #else
 
+static inline void cpuacct_init(void)
+{
+}
+
 static inline void cpuacct_charge(struct task_struct *tsk, u64 cputime)
 {
 }