kernel/delayacct: move delayacct sysctls to its own file

kernel/sysctl.c is a kitchen sink where everyone leaves their dirty
dishes, this makes it very difficult to maintain.

To help with this maintenance let's start by moving sysctls to places
where they actually belong.  The proc sysctl maintainers do not want to
know what sysctl knobs you wish to add for your own piece of code, we
just care about the core logic.

All filesystem syctls now get reviewed by fs folks. This commit
follows the commit of fs, move the delayacct sysctl to its own file,
kernel/delayacct.c.

Signed-off-by: tangmeng <tangmeng@uniontech.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

include/linux/delayacct.h

@@ -61,9 +61,6 @@ extern int delayacct_on;	/* Delay accounting turned on/off */
 extern struct kmem_cache *delayacct_cache;
 extern void delayacct_init(void);
 
-extern int sysctl_delayacct(struct ctl_table *table, int write, void *buffer,
-			    size_t *lenp, loff_t *ppos);
-
 extern void __delayacct_tsk_init(struct task_struct *);
 extern void __delayacct_tsk_exit(struct task_struct *);
 extern void __delayacct_blkio_start(void);

kernel/delayacct.c

@@ -44,7 +44,7 @@ void delayacct_init(void)
 }
 
 #ifdef CONFIG_PROC_SYSCTL
-int sysctl_delayacct(struct ctl_table *table, int write, void *buffer,
+static int sysctl_delayacct(struct ctl_table *table, int write, void *buffer,
 		     size_t *lenp, loff_t *ppos)
 {
 	int state = delayacct_on;
@@ -63,6 +63,26 @@ int sysctl_delayacct(struct ctl_table *table, int write, void *buffer,
 		set_delayacct(state);
 	return err;
 }
+
+static struct ctl_table kern_delayacct_table[] = {
+	{
+		.procname       = "task_delayacct",
+		.data           = NULL,
+		.maxlen         = sizeof(unsigned int),
+		.mode           = 0644,
+		.proc_handler   = sysctl_delayacct,
+		.extra1         = SYSCTL_ZERO,
+		.extra2         = SYSCTL_ONE,
+	},
+	{ }
+};
+
+static __init int kernel_delayacct_sysctls_init(void)
+{
+	register_sysctl_init("kernel", kern_delayacct_table);
+	return 0;
+}
+late_initcall(kernel_delayacct_sysctls_init);
 #endif
 
 void __delayacct_tsk_init(struct task_struct *tsk)

kernel/sysctl.c

@@ -67,7 +67,6 @@
 #include <linux/userfaultfd_k.h>
 #include <linux/latencytop.h>
 #include <linux/pid.h>
-#include <linux/delayacct.h>
 
 #include "../lib/kstrtox.h"
 
@@ -1651,17 +1650,6 @@ int proc_do_static_key(struct ctl_table *table, int write,
 }
 
 static struct ctl_table kern_table[] = {
-#ifdef CONFIG_TASK_DELAY_ACCT
-	{
-		.procname	= "task_delayacct",
-		.data		= NULL,
-		.maxlen		= sizeof(unsigned int),
-		.mode		= 0644,
-		.proc_handler	= sysctl_delayacct,
-		.extra1		= SYSCTL_ZERO,
-		.extra2		= SYSCTL_ONE,
-	},
-#endif /* CONFIG_TASK_DELAY_ACCT */
 #ifdef CONFIG_NUMA_BALANCING
 	{
 		.procname	= "numa_balancing",