sched: move autogroup sysctls into its own file

move autogroup sysctls to autogroup.c and use the new
register_sysctl_init() to register the sysctl interface.

Signed-off-by: Zhen Ni <[e-mail]>
Signed-off-by: Peter Zijlstra (Intel) <[e-mail]>
Link: https://lkml.kernel.org/r/[e-mail]

include/linux/sched/sysctl.h

···
 extern unsigned int sysctl_sched_cfs_bandwidth_slice;
 #endif
 
-#ifdef CONFIG_SCHED_AUTOGROUP
-extern unsigned int sysctl_sched_autogroup_enabled;
-#endif
-
 extern int sysctl_sched_rr_timeslice;
 extern int sched_rr_timeslice;
 

kernel/sched/autogroup.c

···
 static struct autogroup autogroup_default;
 static atomic_t autogroup_seq_nr;
 
+#ifdef CONFIG_SYSCTL
+static struct ctl_table sched_autogroup_sysctls[] = {
+	{
+		.procname       = "sched_autogroup_enabled",
+		.data           = &sysctl_sched_autogroup_enabled,
+		.maxlen         = sizeof(unsigned int),
+		.mode           = 0644,
+		.proc_handler   = proc_dointvec_minmax,
+		.extra1         = SYSCTL_ZERO,
+		.extra2         = SYSCTL_ONE,
+	},
+	{}
+};
+
+static void __init sched_autogroup_sysctl_init(void)
+{
+	register_sysctl_init("kernel", sched_autogroup_sysctls);
+}
+#else
+#define sched_autogroup_sysctl_init() do { } while (0)
+#endif
+
 void __init autogroup_init(struct task_struct *init_task)
 {
 	autogroup_default.tg = &root_task_group;
···
 static int __init setup_autogroup(char *str)
 {
 	sysctl_sched_autogroup_enabled = 0;
+	sched_autogroup_sysctl_init();
 
 	return 1;
 }

kernel/sched/autogroup.h

···
 static inline struct task_group *
 autogroup_task_group(struct task_struct *p, struct task_group *tg)
 {
+	extern unsigned int sysctl_sched_autogroup_enabled;
 	int enabled = READ_ONCE(sysctl_sched_autogroup_enabled);
 
 	if (enabled && task_wants_autogroup(p, tg))

kernel/sysctl.c

···
 		.proc_handler	= sysctl_sched_uclamp_handler,
 	},
 #endif
-#ifdef CONFIG_SCHED_AUTOGROUP
-	{
-		.procname	= "sched_autogroup_enabled",
-		.data		= &sysctl_sched_autogroup_enabled,
-		.maxlen		= sizeof(unsigned int),
-		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= SYSCTL_ZERO,
-		.extra2		= SYSCTL_ONE,
-	},
-#endif
 #ifdef CONFIG_CFS_BANDWIDTH
 	{
 		.procname	= "sched_cfs_bandwidth_slice_us",