[PATCH v2 6/9] sysctl: use const for typically used max/min proc sysctls

[Luis Chamberlain]

From: Xiaoming Ni <nixiaoming@xxxxxxxxxx>

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 min and max boundary, these extra1 and extra2 arguments are
then used for read-only operations. So make them const to reflect
this.

Signed-off-by: Xiaoming Ni <nixiaoming@xxxxxxxxxx>
[mcgrof: commit log love]
Signed-off-by: Luis Chamberlain <mcgrof@xxxxxxxxxx>
---
 kernel/sysctl.c | 53 ++++++++++++++++++++++++-------------------------
 1 file changed, 26 insertions(+), 27 deletions(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index b22149c46fa8..03bbd26d4df0 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
@@ -171,8 +170,8 @@ int sysctl_legacy_va_layout;
 #endif
 
 #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 */
@@ -2176,8 +2175,8 @@ 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 +2184,8 @@ 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 +2259,7 @@ 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 +2471,7 @@ 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 +2627,7 @@ 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 +2644,7 @@ 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 +2758,8 @@ 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 +3045,8 @@ 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 +3070,8 @@ 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 +3079,8 @@ 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
 	{
-- 
2.33.0