sysctl: Add const decoration for static boundary value variables

When proc_dointvec_minmax() or proc_doulongvec_minmax() are used we are
using the extra1 and extra2 parameters on the sysctl table only for
a lower and upper boundary, these extra1 and extra2 arguments are
then used for read-only operations then. This applies to helpers which
end up also calling these helpers as well.

Use const to make this clear.

Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

1 files changed, 89 insertions, 27 deletions

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 1cd6e45dba6d3..0b7110fb10a92 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -107,27 +107,26 @@
 
 /* Constants used for minimum and  maximum */
 
-static unsigned long zero_ul;
-static unsigned long one_ul = 1;
-static unsigned long long_max = LONG_MAX;
+static const unsigned long zero_ul;
+static const unsigned long one_ul = 1;
+static const unsigned long long_max = LONG_MAX;
 #ifdef CONFIG_PRINTK
-static int ten_thousand = 10000;
+static const int ten_thousand = 10000;
 #endif
 #ifdef CONFIG_PERF_EVENTS
-static int six_hundred_forty_kb = 640 * 1024;
+static const int six_hundred_forty_kb = 640 * 1024;
 #endif
 
 /* this is needed for the proc_doulongvec_minmax of vm_dirty_bytes */
-static unsigned long dirty_bytes_min = 2 * PAGE_SIZE;
+static const unsigned long dirty_bytes_min = 2 * PAGE_SIZE;
 
 /* this is needed for the proc_dointvec_minmax for [fs_]overflow UID and GID */
-static int maxolduid = 65535;
-static int minolduid;
+static const int maxolduid = 65535;
+static const int minolduid;
 
 static const int ngroups_max = NGROUPS_MAX;
 static const int cap_last_cap = CAP_LAST_CAP;
 
-
 #ifdef CONFIG_INOTIFY_USER
 #include <linux/inotify.h>
 #endif
@@ -170,9 +169,20 @@ static enum sysctl_writes_mode sysctl_writes_strict = SYSCTL_WRITES_STRICT;
 int sysctl_legacy_va_layout;
 #endif
 
+#ifdef CONFIG_SCHED_DEBUG
+static const int min_sched_granularity_ns = 100000;		/* 100 usecs */
+static const int max_sched_granularity_ns = NSEC_PER_SEC;	/* 1 second */
+static const int min_wakeup_granularity_ns;			/* 0 usecs */
+static const int max_wakeup_granularity_ns = NSEC_PER_SEC;	/* 1 second */
+#ifdef CONFIG_SMP
+static const int min_sched_tunable_scaling = SCHED_TUNABLESCALING_NONE;
+static const int max_sched_tunable_scaling = SCHED_TUNABLESCALING_END - 1;
+#endif /* CONFIG_SMP */
+#endif /* CONFIG_SCHED_DEBUG */
+
 #ifdef CONFIG_COMPACTION
-static int min_extfrag_threshold;
-static int max_extfrag_threshold = 1000;
+static const int min_extfrag_threshold;
+static const int max_extfrag_threshold = 1000;
 #endif
 
 #endif /* CONFIG_SYSCTL */
@@ -1759,6 +1769,58 @@ static struct ctl_table kern_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
 	},
+#ifdef CONFIG_SCHED_DEBUG
+	{
+		.procname	= "sched_min_granularity_ns",
+		.data		= &sysctl_sched_min_granularity,
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= sched_proc_update_handler,
+		.extra1		= (void *)&min_sched_granularity_ns,
+		.extra2		= (void *)&max_sched_granularity_ns,
+	},
+	{
+		.procname	= "sched_latency_ns",
+		.data		= &sysctl_sched_latency,
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= sched_proc_update_handler,
+		.extra1		= (void *)&min_sched_granularity_ns,
+		.extra2		= (void *)&max_sched_granularity_ns,
+	},
+	{
+		.procname	= "sched_wakeup_granularity_ns",
+		.data		= &sysctl_sched_wakeup_granularity,
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= sched_proc_update_handler,
+		.extra1		= (void *)&min_wakeup_granularity_ns,
+		.extra2		= (void *)&max_wakeup_granularity_ns,
+	},
+#ifdef CONFIG_SMP
+	{
+		.procname	= "sched_tunable_scaling",
+		.data		= &sysctl_sched_tunable_scaling,
+		.maxlen		= sizeof(enum sched_tunable_scaling),
+		.mode		= 0644,
+		.proc_handler	= sched_proc_update_handler,
+		.extra1		= (void *)&min_sched_tunable_scaling,
+		.extra2		= (void *)&max_sched_tunable_scaling,
+	},
+	{
+		.procname	= "sched_migration_cost_ns",
+		.data		= &sysctl_sched_migration_cost,
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
+	{
+		.procname	= "sched_nr_migrate",
+		.data		= &sysctl_sched_nr_migrate,
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
 #ifdef CONFIG_SCHEDSTATS
 	{
 		.procname	= "sched_schedstats",
@@ -2176,8 +2238,8 @@ static struct ctl_table kern_table[] = {
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &minolduid,
-		.extra2		= &maxolduid,
+		.extra1		= (void *)&minolduid,
+		.extra2		= (void *)&maxolduid,
 	},
 	{
 		.procname	= "overflowgid",
@@ -2185,8 +2247,8 @@ static struct ctl_table kern_table[] = {
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &minolduid,
-		.extra2		= &maxolduid,
+		.extra1		= (void *)&minolduid,
+		.extra2		= (void *)&maxolduid,
 	},
 #ifdef CONFIG_S390
 	{
@@ -2260,7 +2322,7 @@ static struct ctl_table kern_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
 		.extra1		= SYSCTL_ZERO,
-		.extra2		= &ten_thousand,
+		.extra2		= (void *)&ten_thousand,
 	},
 	{
 		.procname	= "printk_devkmsg",
@@ -2472,7 +2534,7 @@ static struct ctl_table kern_table[] = {
 		.mode		= 0644,
 		.proc_handler	= perf_event_max_stack_handler,
 		.extra1		= SYSCTL_ZERO,
-		.extra2		= &six_hundred_forty_kb,
+		.extra2		= (void *)&six_hundred_forty_kb,
 	},
 	{
 		.procname	= "perf_event_max_contexts_per_stack",
@@ -2628,7 +2690,7 @@ static struct ctl_table vm_table[] = {
 		.maxlen		= sizeof(dirty_background_bytes),
 		.mode		= 0644,
 		.proc_handler	= dirty_background_bytes_handler,
-		.extra1		= &one_ul,
+		.extra1		= (void *)&one_ul,
 	},
 	{
 		.procname	= "dirty_ratio",
@@ -2645,7 +2707,7 @@ static struct ctl_table vm_table[] = {
 		.maxlen		= sizeof(vm_dirty_bytes),
 		.mode		= 0644,
 		.proc_handler	= dirty_bytes_handler,
-		.extra1		= &dirty_bytes_min,
+		.extra1		= (void *)&dirty_bytes_min,
 	},
 	{
 		.procname	= "dirty_writeback_centisecs",
@@ -2759,8 +2821,8 @@ static struct ctl_table vm_table[] = {
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &min_extfrag_threshold,
-		.extra2		= &max_extfrag_threshold,
+		.extra1		= (void *)&min_extfrag_threshold,
+		.extra2		= (void *)&max_extfrag_threshold,
 	},
 	{
 		.procname	= "compact_unevictable_allowed",
@@ -3046,8 +3108,8 @@ static struct ctl_table fs_table[] = {
 		.maxlen		= sizeof(files_stat.max_files),
 		.mode		= 0644,
 		.proc_handler	= proc_doulongvec_minmax,
-		.extra1		= &zero_ul,
-		.extra2		= &long_max,
+		.extra1		= (void *)&zero_ul,
+		.extra2		= (void *)&long_max,
 	},
 	{
 		.procname	= "nr_open",
@@ -3071,8 +3133,8 @@ static struct ctl_table fs_table[] = {
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &minolduid,
-		.extra2		= &maxolduid,
+		.extra1		= (void *)&minolduid,
+		.extra2		= (void *)&maxolduid,
 	},
 	{
 		.procname	= "overflowgid",
@@ -3080,8 +3142,8 @@ static struct ctl_table fs_table[] = {
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &minolduid,
-		.extra2		= &maxolduid,
+		.extra1		= (void *)&minolduid,
+		.extra2		= (void *)&maxolduid,
 	},
 #ifdef CONFIG_FILE_LOCKING
 	{