[PATCH v6] kernel/time: move timer sysctls to its own file

[tangmeng <tangmeng@xxxxxxxxxxxxx>]

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.

So move the timer_migration sysctls to its own file.

Signed-off-by: tangmeng <tangmeng@xxxxxxxxxxxxx>
---
 include/linux/timer.h |  8 -------
 kernel/sysctl.c       | 11 ---------
 kernel/time/timer.c   | 54 ++++++++++++++++++++++++++++++++-----------
 3 files changed, 40 insertions(+), 33 deletions(-)

diff --git a/include/linux/timer.h b/include/linux/timer.h
index fda13c9d1256..648f00105f58 100644
--- a/include/linux/timer.h
+++ b/include/linux/timer.h
@@ -196,14 +196,6 @@ extern void init_timers(void);
 struct hrtimer;
 extern enum hrtimer_restart it_real_fn(struct hrtimer *);
 
-#if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON)
-struct ctl_table;
-
-extern unsigned int sysctl_timer_migration;
-int timer_migration_handler(struct ctl_table *table, int write,
-			    void *buffer, size_t *lenp, loff_t *ppos);
-#endif
-
 unsigned long __round_jiffies(unsigned long j, int cpu);
 unsigned long __round_jiffies_relative(unsigned long j, int cpu);
 unsigned long round_jiffies(unsigned long j);
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 083be6af29d7..740c34f20235 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2656,17 +2656,6 @@ static struct ctl_table kern_table[] = {
 		.extra1		= SYSCTL_ZERO,
 		.extra2		= SYSCTL_ONE,
 	},
-#if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON)
-	{
-		.procname	= "timer_migration",
-		.data		= &sysctl_timer_migration,
-		.maxlen		= sizeof(unsigned int),
-		.mode		= 0644,
-		.proc_handler	= timer_migration_handler,
-		.extra1		= SYSCTL_ZERO,
-		.extra2		= SYSCTL_ONE,
-	},
-#endif
 #ifdef CONFIG_BPF_SYSCALL
 	{
 		.procname	= "unprivileged_bpf_disabled",
diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 85f1021ad459..c4f0045139cb 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -44,6 +44,9 @@
 #include <linux/slab.h>
 #include <linux/compat.h>
 #include <linux/random.h>
+#ifdef CONFIG_SYSCTL
+#include <linux/sysctl.h>
+#endif
 
 #include <linux/uaccess.h>
 #include <asm/unistd.h>
@@ -223,7 +226,8 @@ static void timer_update_keys(struct work_struct *work);
 static DECLARE_WORK(timer_update_work, timer_update_keys);
 
 #ifdef CONFIG_SMP
-unsigned int sysctl_timer_migration = 1;
+struct ctl_table;
+static unsigned int sysctl_timer_migration = 1;
 
 DEFINE_STATIC_KEY_FALSE(timers_migration_enabled);
 
@@ -234,6 +238,41 @@ static void timers_update_migration(void)
 	else
 		static_branch_disable(&timers_migration_enabled);
 }
+
+#ifdef CONFIG_SYSCTL
+static int timer_migration_handler(struct ctl_table *table, int write,
+			    void *buffer, size_t *lenp, loff_t *ppos)
+{
+	int ret;
+
+	mutex_lock(&timer_keys_mutex);
+	ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+	if (!ret && write)
+		timers_update_migration();
+	mutex_unlock(&timer_keys_mutex);
+	return ret;
+}
+
+static struct ctl_table timer_sysctl[] = {
+	{
+		.procname       = "timer_migration",
+		.data           = &sysctl_timer_migration,
+		.maxlen         = sizeof(unsigned int),
+		.mode           = 0644,
+		.proc_handler   = timer_migration_handler,
+		.extra1         = SYSCTL_ZERO,
+		.extra2         = SYSCTL_ONE,
+	},
+	{}
+};
+
+static int __init timer_sysctl_init(void)
+{
+	register_sysctl("kernel", timer_sysctl);
+	return 0;
+}
+device_initcall(timer_sysctl_init);
+#endif /* CONFIG_SYSCTL */
 #else
 static inline void timers_update_migration(void) { }
 #endif /* !CONFIG_SMP */
@@ -251,19 +290,6 @@ void timers_update_nohz(void)
 	schedule_work(&timer_update_work);
 }
 
-int timer_migration_handler(struct ctl_table *table, int write,
-			    void *buffer, size_t *lenp, loff_t *ppos)
-{
-	int ret;
-
-	mutex_lock(&timer_keys_mutex);
-	ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
-	if (!ret && write)
-		timers_update_migration();
-	mutex_unlock(&timer_keys_mutex);
-	return ret;
-}
-
 static inline bool is_timers_nohz_active(void)
 {
 	return static_branch_unlikely(&timers_nohz_active);
-- 
2.20.1