hung_task: Move hung_task sysctl interface to hung_task.c

Move hung_task sysctl interface to hung_task.c.
Use register_sysctl() to register the sysctl interface to avoid
merge conflicts when different features modify sysctl.c at the same time.

Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

3 files changed, 79 insertions, 76 deletions

diff --git a/include/linux/sched/sysctl.h b/include/linux/sched/sysctl.h
index 304f431178fd9..c19dd5a2c05c6 100644
--- a/include/linux/sched/sysctl.h
+++ b/include/linux/sched/sysctl.h
@@ -7,20 +7,8 @@
 struct ctl_table;
 
 #ifdef CONFIG_DETECT_HUNG_TASK
-
-#ifdef CONFIG_SMP
-extern unsigned int sysctl_hung_task_all_cpu_backtrace;
-#else
-#define sysctl_hung_task_all_cpu_backtrace 0
-#endif /* CONFIG_SMP */
-
-extern int	     sysctl_hung_task_check_count;
-extern unsigned int  sysctl_hung_task_panic;
+/* used for hung_task and block/ */
 extern unsigned long sysctl_hung_task_timeout_secs;
-extern unsigned long sysctl_hung_task_check_interval_secs;
-extern int sysctl_hung_task_warnings;
-int proc_dohung_task_timeout_secs(struct ctl_table *table, int write,
-		void *buffer, size_t *lenp, loff_t *ppos);
 #else
 /* Avoid need for ifdefs elsewhere in the code */
 enum { sysctl_hung_task_timeout_secs = 0 };
diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index 8cc07e7f29aa1..edccc9a09a62f 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -64,6 +64,9 @@ static struct task_struct *watchdog_task;
  * Defaults to 0, can be changed via sysctl.
  */
 unsigned int __read_mostly sysctl_hung_task_all_cpu_backtrace;
+#else
+/* Avoid need for ifdefs elsewhere in the code */
+enum { sysctl_hung_task_timeout_secs = 0 };
 #endif /* CONFIG_SMP */
 
 /*
@@ -266,11 +269,13 @@ static long hung_timeout_jiffies(unsigned long last_checked,
 		MAX_SCHEDULE_TIMEOUT;
 }
 
+#ifdef CONFIG_SYSCTL
 /*
  * Process updating of timeout sysctl
  */
-int proc_dohung_task_timeout_secs(struct ctl_table *table, int write,
-				  void *buffer, size_t *lenp, loff_t *ppos)
+static int proc_dohung_task_timeout_secs(struct ctl_table *table, int write,
+				  void __user *buffer,
+				  size_t *lenp, loff_t *ppos)
 {
 	int ret;
 
@@ -285,6 +290,76 @@ int proc_dohung_task_timeout_secs(struct ctl_table *table, int write,
 	return ret;
 }
 
+/*
+ * This is needed for proc_doulongvec_minmax of sysctl_hung_task_timeout_secs
+ * and hung_task_check_interval_secs
+ */
+static const unsigned long hung_task_timeout_max = (LONG_MAX / HZ);
+static struct ctl_table hung_task_sysctls[] = {
+#ifdef CONFIG_SMP
+	{
+		.procname	= "hung_task_all_cpu_backtrace",
+		.data		= &sysctl_hung_task_all_cpu_backtrace,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
+	},
+#endif /* CONFIG_SMP */
+	{
+		.procname	= "hung_task_panic",
+		.data		= &sysctl_hung_task_panic,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
+	},
+	{
+		.procname	= "hung_task_check_count",
+		.data		= &sysctl_hung_task_check_count,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= SYSCTL_ZERO,
+	},
+	{
+		.procname	= "hung_task_timeout_secs",
+		.data		= &sysctl_hung_task_timeout_secs,
+		.maxlen		= sizeof(unsigned long),
+		.mode		= 0644,
+		.proc_handler	= proc_dohung_task_timeout_secs,
+		.extra2		= (void *)&hung_task_timeout_max,
+	},
+	{
+		.procname	= "hung_task_check_interval_secs",
+		.data		= &sysctl_hung_task_check_interval_secs,
+		.maxlen		= sizeof(unsigned long),
+		.mode		= 0644,
+		.proc_handler	= proc_dohung_task_timeout_secs,
+		.extra2		= (void *)&hung_task_timeout_max,
+	},
+	{
+		.procname	= "hung_task_warnings",
+		.data		= &sysctl_hung_task_warnings,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= SYSCTL_NEG_ONE,
+	},
+	{}
+};
+
+static void __init hung_task_sysctl_init(void)
+{
+	register_sysctl_init("kernel", hung_task_sysctls, "hung_task_sysctls");
+}
+#else
+#define hung_task_sysctl_init() do { } while (0)
+#endif /* CONFIG_SYSCTL */
+
+
 static atomic_t reset_hung_task = ATOMIC_INIT(0);
 
 void reset_hung_task_detector(void)
@@ -354,6 +429,7 @@ static int __init hung_task_init(void)
 	pm_notifier(hungtask_pm_notify, 0);
 
 	watchdog_task = kthread_run(watchdog, NULL, "khungtaskd");
+	hung_task_sysctl_init();
 
 	return 0;
 }
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index d31991a35c31c..6192c966a995e 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -133,13 +133,6 @@ static int minolduid;
 static int ngroups_max = NGROUPS_MAX;
 static const int cap_last_cap = CAP_LAST_CAP;
 
-/*
- * This is needed for proc_doulongvec_minmax of sysctl_hung_task_timeout_secs
- * and hung_task_check_interval_secs
- */
-#ifdef CONFIG_DETECT_HUNG_TASK
-static unsigned long hung_task_timeout_max = (LONG_MAX/HZ);
-#endif
 
 #ifdef CONFIG_INOTIFY_USER
 #include <linux/inotify.h>
@@ -2507,60 +2500,6 @@ static struct ctl_table kern_table[] = {
 		.proc_handler	= proc_dointvec,
 	},
 #endif
-#ifdef CONFIG_DETECT_HUNG_TASK
-#ifdef CONFIG_SMP
-	{
-		.procname	= "hung_task_all_cpu_backtrace",
-		.data		= &sysctl_hung_task_all_cpu_backtrace,
-		.maxlen		= sizeof(int),
-		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= SYSCTL_ZERO,
-		.extra2		= SYSCTL_ONE,
-	},
-#endif /* CONFIG_SMP */
-	{
-		.procname	= "hung_task_panic",
-		.data		= &sysctl_hung_task_panic,
-		.maxlen		= sizeof(int),
-		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= SYSCTL_ZERO,
-		.extra2		= SYSCTL_ONE,
-	},
-	{
-		.procname	= "hung_task_check_count",
-		.data		= &sysctl_hung_task_check_count,
-		.maxlen		= sizeof(int),
-		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= SYSCTL_ZERO,
-	},
-	{
-		.procname	= "hung_task_timeout_secs",
-		.data		= &sysctl_hung_task_timeout_secs,
-		.maxlen		= sizeof(unsigned long),
-		.mode		= 0644,
-		.proc_handler	= proc_dohung_task_timeout_secs,
-		.extra2		= &hung_task_timeout_max,
-	},
-	{
-		.procname	= "hung_task_check_interval_secs",
-		.data		= &sysctl_hung_task_check_interval_secs,
-		.maxlen		= sizeof(unsigned long),
-		.mode		= 0644,
-		.proc_handler	= proc_dohung_task_timeout_secs,
-		.extra2		= &hung_task_timeout_max,
-	},
-	{
-		.procname	= "hung_task_warnings",
-		.data		= &sysctl_hung_task_warnings,
-		.maxlen		= sizeof(int),
-		.mode		= 0644,
-		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= SYSCTL_NEG_ONE,
-	},
-#endif
 #ifdef CONFIG_RT_MUTEXES
 	{
 		.procname	= "max_lock_depth",