proc/sysctl: add shared variables for range check

In the sysctl code the proc_dointvec_minmax() function is often used to
validate the user supplied value between an allowed range. This
function uses the extra1 and extra2 members from struct ctl_table as
minimum and maximum allowed value.

On sysctl handler declaration, in every source file there are some
readonly variables containing just an integer which address is assigned
to the extra1 and extra2 members, so the sysctl range is enforced.

The special values 0, 1 and INT_MAX are very often used as range
boundary, leading duplication of variables like zero=0, one=1,
int_max=INT_MAX in different source files:

$ git grep -E '\.extra[12].*&(zero|one|int_max)' |wc -l
248

Add a const int array containing the most commonly used values, some
macros to refer more easily to the correct array member, and use them
instead of creating a local one for every object file.

This is the bloat-o-meter output comparing the old and new binary
compiled with the default Fedora config:

# scripts/bloat-o-meter -d vmlinux.o.old vmlinux.o
add/remove: 2/2 grow/shrink: 0/2 up/down: 24/-188 (-164)
Data old new delta
sysctl_vals - 12 +12
__kstrtab_sysctl_vals - 12 +12
max 14 10 -4
int_max 16 - -16
one 68 - -68
zero 128 28 -100
Total: Before=20583249, After=20583085, chg -0.00%

[[e-mail]: tipc: remove two unused variables]
Link: http://lkml.kernel.org/r/[e-mail]
[[e-mail]: fix net/ipv6/sysctl_net_ipv6.c]
[[e-mail]: proc/sysctl: make firmware loader table conditional]
Link: http://lkml.kernel.org/r/[e-mail]
[[e-mail]: fix fs/eventpoll.c]
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Matteo Croce <[e-mail]>
Signed-off-by: Arnd Bergmann <[e-mail]>
Acked-by: Kees Cook <[e-mail]>
Reviewed-by: Aaron Tomlin <[e-mail]>
Cc: Matthew Wilcox <[e-mail]>
Cc: Stephen Rothwell <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

arch/s390/appldata/appldata_base.c

···
 			   void __user *buffer, size_t *lenp, loff_t *ppos)
 {
 	int timer_active = appldata_timer_active;
-	int zero = 0;
-	int one = 1;
 	int rc;
 	struct ctl_table ctl_entry = {
 		.procname	= ctl->procname,
 		.data		= &timer_active,
 		.maxlen		= sizeof(int),
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	};
 
 	rc = proc_douintvec_minmax(&ctl_entry, write, buffer, lenp, ppos);
···
 			   void __user *buffer, size_t *lenp, loff_t *ppos)
 {
 	int interval = appldata_interval;
-	int one = 1;
 	int rc;
 	struct ctl_table ctl_entry = {
 		.procname	= ctl->procname,
 		.data		= &interval,
 		.maxlen		= sizeof(int),
-		.extra1		= &one,
+		.extra1		= SYSCTL_ONE,
 	};
 
 	rc = proc_dointvec_minmax(&ctl_entry, write, buffer, lenp, ppos);
···
 	struct list_head *lh;
 	int rc, found;
 	int active;
-	int zero = 0;
-	int one = 1;
 	struct ctl_table ctl_entry = {
 		.data		= &active,
 		.maxlen		= sizeof(int),
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	};
 
 	found = 0;

arch/s390/kernel/topology.c

···
 {
 	int enabled = topology_is_enabled();
 	int new_mode;
-	int zero = 0;
-	int one = 1;
 	int rc;
 	struct ctl_table ctl_entry = {
 		.procname	= ctl->procname,
 		.data		= &enabled,
 		.maxlen		= sizeof(int),
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	};
 
 	rc = proc_douintvec_minmax(&ctl_entry, write, buffer, lenp, ppos);

arch/x86/entry/vdso/vdso32-setup.c

···
 /* Register vsyscall32 into the ABI table */
 #include <linux/sysctl.h>
 
-static const int zero;
-static const int one = 1;
-
 static struct ctl_table abi_table2[] = {
 	{
 		.procname	= "vsyscall32",
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= (int *)&zero,
-		.extra2		= (int *)&one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 	{}
 };

arch/x86/kernel/itmt.c

···
 	return ret;
 }
 
-static unsigned int zero;
-static unsigned int one = 1;
 static struct ctl_table itmt_kern_table[] = {
 	{
 		.procname	= "sched_itmt_enabled",
···
 		.maxlen		= sizeof(unsigned int),
 		.mode		= 0644,
 		.proc_handler	= sched_itmt_update_handler,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 	{}
 };

drivers/base/firmware_loader/fallback_table.c

···
  * firmware fallback configuration table
  */
 
-static unsigned int zero;
-static unsigned int one = 1;
-
 struct firmware_fallback_config fw_fallback_config = {
 	.force_sysfs_fallback = IS_ENABLED(CONFIG_FW_LOADER_USER_HELPER_FALLBACK),
 	.loading_timeout = 60,
···
 };
 EXPORT_SYMBOL_GPL(fw_fallback_config);
 
+#ifdef CONFIG_SYSCTL
 struct ctl_table firmware_config_table[] = {
 	{
 		.procname	= "force_sysfs_fallback",
···
 		.maxlen         = sizeof(unsigned int),
 		.mode           = 0644,
 		.proc_handler   = proc_douintvec_minmax,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 	{
 		.procname	= "ignore_sysfs_fallback",
···
 		.maxlen         = sizeof(unsigned int),
 		.mode           = 0644,
 		.proc_handler   = proc_douintvec_minmax,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 	{ }
 };
 EXPORT_SYMBOL_GPL(firmware_config_table);
+#endif

drivers/gpu/drm/i915/i915_perf.c

···
 #define POLL_PERIOD (NSEC_PER_SEC / POLL_FREQUENCY)
 
 /* for sysctl proc_dointvec_minmax of dev.i915.perf_stream_paranoid */
-static int zero;
-static int one = 1;
 static u32 i915_perf_stream_paranoid = true;
 
 /* The maximum exponent the hardware accepts is 63 (essentially it selects one
···
 	 .maxlen = sizeof(i915_perf_stream_paranoid),
 	 .mode = 0644,
 	 .proc_handler = proc_dointvec_minmax,
-	 .extra1 = &zero,
-	 .extra2 = &one,
+	 .extra1 = SYSCTL_ZERO,
+	 .extra2 = SYSCTL_ONE,
 	 },
 	{
 	 .procname = "oa_max_sample_rate",
···
 	 .maxlen = sizeof(i915_oa_max_sample_rate),
 	 .mode = 0644,
 	 .proc_handler = proc_dointvec_minmax,
-	 .extra1 = &zero,
+	 .extra1 = SYSCTL_ZERO,
 	 .extra2 = &oa_sample_rate_hard_limit,
 	 },
 	{}

drivers/hv/vmbus_drv.c

···
 };
 
 static struct ctl_table_header *hv_ctl_table_hdr;
-static int zero;
-static int one = 1;
 
 /*
  * sysctl option to allow the user to control whether kmsg data should be
···
 		.maxlen         = sizeof(int),
 		.mode           = 0644,
 		.proc_handler   = proc_dointvec_minmax,
-		.extra1		= &zero,
-		.extra2		= &one
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE
 	},
 	{}
 };

drivers/tty/tty_ldisc.c

···
 	tty->ldisc = NULL;
 }
 
-static int zero;
-static int one = 1;
 static struct ctl_table tty_table[] = {
 	{
 		.procname	= "ldisc_autoload",
···
 		.maxlen		= sizeof(tty_ldisc_autoload),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 	{ }
 };

drivers/xen/balloon.c

···
 
 #ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
 
-static int zero;
-static int one = 1;
-
 static struct ctl_table balloon_table[] = {
 	{
 		.procname	= "hotplug_unpopulated",
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1         = &zero,
-		.extra2         = &one,
+		.extra1         = SYSCTL_ZERO,
+		.extra2         = SYSCTL_ONE,
 	},
 	{ }
 };

fs/eventpoll.c

···
 
 #include <linux/sysctl.h>
 
-static long zero;
+static long long_zero;
 static long long_max = LONG_MAX;
 
 struct ctl_table epoll_table[] = {
···
 		.maxlen		= sizeof(max_user_watches),
 		.mode		= 0644,
 		.proc_handler	= proc_doulongvec_minmax,
-		.extra1		= &zero,
+		.extra1		= &long_zero,
 		.extra2		= &long_max,
 	},
 	{ }

fs/notify/inotify/inotify_user.c

···
 
 #include <linux/sysctl.h>
 
-static int zero;
-
 struct ctl_table inotify_table[] = {
 	{
 		.procname	= "max_user_instances",
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 	},
 	{
 		.procname	= "max_user_watches",
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 	},
 	{
 		.procname	= "max_queued_events",
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero
+		.extra1		= SYSCTL_ZERO
 	},
 	{ }
 };

fs/proc/proc_sysctl.c

···
 static const struct file_operations proc_sys_dir_file_operations;
 static const struct inode_operations proc_sys_dir_operations;
 
+/* shared constants to be used in various sysctls */
+const int sysctl_vals[] = { 0, 1, INT_MAX };
+EXPORT_SYMBOL(sysctl_vals);
+
 /* Support for permanently empty directories */
 
 struct ctl_table sysctl_mount_point[] = {

include/linux/sysctl.h

···
 struct ctl_table_header;
 struct ctl_dir;
 
+/* Keep the same order as in fs/proc/proc_sysctl.c */
+#define SYSCTL_ZERO	((void *)&sysctl_vals[0])
+#define SYSCTL_ONE	((void *)&sysctl_vals[1])
+#define SYSCTL_INT_MAX	((void *)&sysctl_vals[2])
+
+extern const int sysctl_vals[];
+
 typedef int proc_handler (struct ctl_table *ctl, int write,
 			  void __user *buffer, size_t *lenp, loff_t *ppos);
 

ipc/ipc_sysctl.c

···
 #define proc_ipc_sem_dointvec	   NULL
 #endif
 
-static int zero;
-static int one = 1;
-static int int_max = INT_MAX;
 int ipc_mni = IPCMNI;
 int ipc_mni_shift = IPCMNI_SHIFT;
 int ipc_min_cycle = RADIX_TREE_MAP_SIZE;
···
 		.maxlen		= sizeof(init_ipc_ns.shm_ctlmni),
 		.mode		= 0644,
 		.proc_handler	= proc_ipc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &ipc_mni,
 	},
 	{
···
 		.maxlen		= sizeof(init_ipc_ns.shm_rmid_forced),
 		.mode		= 0644,
 		.proc_handler	= proc_ipc_dointvec_minmax_orphans,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 	{
 		.procname	= "msgmax",
···
 		.maxlen		= sizeof(init_ipc_ns.msg_ctlmax),
 		.mode		= 0644,
 		.proc_handler	= proc_ipc_dointvec_minmax,
-		.extra1		= &zero,
-		.extra2		= &int_max,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_INT_MAX,
 	},
 	{
 		.procname	= "msgmni",
···
 		.maxlen		= sizeof(init_ipc_ns.msg_ctlmni),
 		.mode		= 0644,
 		.proc_handler	= proc_ipc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &ipc_mni,
 	},
 	{
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_ipc_auto_msgmni,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 	{
 		.procname	=  "msgmnb",
···
 		.maxlen		= sizeof(init_ipc_ns.msg_ctlmnb),
 		.mode		= 0644,
 		.proc_handler	= proc_ipc_dointvec_minmax,
-		.extra1		= &zero,
-		.extra2		= &int_max,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_INT_MAX,
 	},
 	{
 		.procname	= "sem",
···
 		.maxlen		= sizeof(init_ipc_ns.ids[IPC_SEM_IDS].next_id),
 		.mode		= 0644,
 		.proc_handler	= proc_ipc_dointvec_minmax,
-		.extra1		= &zero,
-		.extra2		= &int_max,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_INT_MAX,
 	},
 	{
 		.procname	= "msg_next_id",
···
 		.maxlen		= sizeof(init_ipc_ns.ids[IPC_MSG_IDS].next_id),
 		.mode		= 0644,
 		.proc_handler	= proc_ipc_dointvec_minmax,
-		.extra1		= &zero,
-		.extra2		= &int_max,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_INT_MAX,
 	},
 	{
 		.procname	= "shm_next_id",
···
 		.maxlen		= sizeof(init_ipc_ns.ids[IPC_SHM_IDS].next_id),
 		.mode		= 0644,
 		.proc_handler	= proc_ipc_dointvec_minmax,
-		.extra1		= &zero,
-		.extra2		= &int_max,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_INT_MAX,
 	},
 #endif
 	{}

kernel/pid_namespace.c

···
 }
 
 extern int pid_max;
-static int zero = 0;
 static struct ctl_table pid_ns_ctl_table[] = {
 	{
 		.procname = "ns_last_pid",
 		.maxlen = sizeof(int),
 		.mode = 0666, /* permissions are checked in the handler */
 		.proc_handler = pid_ns_ctl_handler,
-		.extra1 = &zero,
+		.extra1 = SYSCTL_ZERO,
 		.extra2 = &pid_max,
 	},
 	{ }

kernel/sysctl.c

···
 #endif
 
 static int __maybe_unused neg_one = -1;
-
-static int zero;
-static int __maybe_unused one = 1;
 static int __maybe_unused two = 2;
 static int __maybe_unused four = 4;
 static unsigned long zero_ul;
···
 		.maxlen		= sizeof(unsigned int),
 		.mode		= 0644,
 		.proc_handler	= sysctl_schedstats,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 #endif /* CONFIG_SCHEDSTATS */
 #endif /* CONFIG_SMP */
···
 		.maxlen		= sizeof(unsigned int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &one,
+		.extra1		= SYSCTL_ONE,
 	},
 	{
 		.procname	= "numa_balancing",
···
 		.maxlen		= sizeof(unsigned int),
 		.mode		= 0644,
 		.proc_handler	= sysctl_numa_balancing,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 #endif /* CONFIG_NUMA_BALANCING */
 #endif /* CONFIG_SCHED_DEBUG */
···
 		.maxlen		= sizeof(unsigned int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 #endif
 #ifdef CONFIG_CFS_BANDWIDTH
···
 		.maxlen		= sizeof(unsigned int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &one,
+		.extra1		= SYSCTL_ONE,
 	},
 #endif
 #if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL)
···
 		.maxlen		= sizeof(unsigned int),
 		.mode		= 0644,
 		.proc_handler	= sched_energy_aware_handler,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 #endif
 #ifdef CONFIG_PROVE_LOCKING
···
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
 		.extra1		= &neg_one,
-		.extra2		= &one,
+		.extra2		= SYSCTL_ONE,
 	},
 #endif
 #ifdef CONFIG_LATENCYTOP
···
 		.mode		= 0644,
 		/* only handle a transition from default "0" to "1" */
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &one,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ONE,
+		.extra2		= SYSCTL_ONE,
 	},
 #endif
 #ifdef CONFIG_MODULES
···
 		.mode		= 0644,
 		/* only handle a transition from default "0" to "1" */
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &one,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ONE,
+		.extra2		= SYSCTL_ONE,
 	},
 #endif
 #ifdef CONFIG_UEVENT_HELPER
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &ten_thousand,
 	},
 	{
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax_sysadmin,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 	{
 		.procname	= "kptr_restrict",
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax_sysadmin,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &two,
 	},
 #endif
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler   = proc_watchdog,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 	{
 		.procname	= "watchdog_thresh",
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_watchdog_thresh,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &sixty,
 	},
 	{
···
 		.maxlen		= sizeof(int),
 		.mode		= NMI_WATCHDOG_SYSCTL_PERM,
 		.proc_handler   = proc_nmi_watchdog,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 	{
 		.procname	= "watchdog_cpumask",
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler   = proc_soft_watchdog,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 	{
 		.procname	= "softlockup_panic",
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 #ifdef CONFIG_SMP
 	{
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 #endif /* CONFIG_SMP */
 #endif
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 #ifdef CONFIG_SMP
 	{
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 #endif /* CONFIG_SMP */
 #endif
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 	{
 		.procname	= "hung_task_check_count",
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 	},
 	{
 		.procname	= "hung_task_timeout_secs",
···
 		.maxlen		= sizeof(sysctl_perf_event_sample_rate),
 		.mode		= 0644,
 		.proc_handler	= perf_proc_update_handler,
-		.extra1		= &one,
+		.extra1		= SYSCTL_ONE,
 	},
 	{
 		.procname	= "perf_cpu_time_max_percent",
···
 		.maxlen		= sizeof(sysctl_perf_cpu_time_max_percent),
 		.mode		= 0644,
 		.proc_handler	= perf_cpu_time_max_percent_handler,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &one_hundred,
 	},
 	{
···
 		.maxlen		= sizeof(sysctl_perf_event_max_stack),
 		.mode		= 0644,
 		.proc_handler	= perf_event_max_stack_handler,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &six_hundred_forty_kb,
 	},
 	{
···
 		.maxlen		= sizeof(sysctl_perf_event_max_contexts_per_stack),
 		.mode		= 0644,
 		.proc_handler	= perf_event_max_stack_handler,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &one_thousand,
 	},
 #endif
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 #if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON)
 	{
···
 		.maxlen		= sizeof(unsigned int),
 		.mode		= 0644,
 		.proc_handler	= timer_migration_handler,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 #endif
 #ifdef CONFIG_BPF_SYSCALL
···
 		.mode		= 0644,
 		/* only handle a transition from default "0" to "1" */
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &one,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ONE,
+		.extra2		= SYSCTL_ONE,
 	},
 	{
 		.procname	= "bpf_stats_enabled",
···
 		.maxlen		= sizeof(sysctl_panic_on_rcu_stall),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 #endif
 #ifdef CONFIG_STACKLEAK_RUNTIME_DISABLE
···
 		.maxlen		= sizeof(int),
 		.mode		= 0600,
 		.proc_handler	= stack_erasing_sysctl,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 #endif
 	{ }
···
 		.maxlen		= sizeof(sysctl_overcommit_memory),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &two,
 	},
 	{
···
 		.maxlen		= sizeof(sysctl_panic_on_oom),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &two,
 	},
 	{
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 	},
 	{
 		.procname	= "dirty_background_ratio",
···
 		.maxlen		= sizeof(dirty_background_ratio),
 		.mode		= 0644,
 		.proc_handler	= dirty_background_ratio_handler,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &one_hundred,
 	},
 	{
···
 		.maxlen		= sizeof(vm_dirty_ratio),
 		.mode		= 0644,
 		.proc_handler	= dirty_ratio_handler,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &one_hundred,
 	},
 	{
···
 		.maxlen		= sizeof(dirty_expire_interval),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 	},
 	{
 		.procname	= "dirtytime_expire_seconds",
···
 		.maxlen		= sizeof(dirtytime_expire_interval),
 		.mode		= 0644,
 		.proc_handler	= dirtytime_interval_handler,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 	},
 	{
 		.procname	= "swappiness",
···
 		.maxlen		= sizeof(vm_swappiness),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &one_hundred,
 	},
 #ifdef CONFIG_HUGETLB_PAGE
···
 		.maxlen			= sizeof(int),
 		.mode			= 0644,
 		.proc_handler	= sysctl_vm_numa_stat_handler,
-		.extra1			= &zero,
-		.extra2			= &one,
+		.extra1			= SYSCTL_ZERO,
+		.extra2			= SYSCTL_ONE,
 	},
 #endif
 	 {
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= drop_caches_sysctl_handler,
-		.extra1		= &one,
+		.extra1		= SYSCTL_ONE,
 		.extra2		= &four,
 	},
 #ifdef CONFIG_COMPACTION
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 
 #endif /* CONFIG_COMPACTION */
···
 		.maxlen		= sizeof(min_free_kbytes),
 		.mode		= 0644,
 		.proc_handler	= min_free_kbytes_sysctl_handler,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 	},
 	{
 		.procname	= "watermark_boost_factor",
···
 		.maxlen		= sizeof(watermark_boost_factor),
 		.mode		= 0644,
 		.proc_handler	= watermark_boost_factor_sysctl_handler,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 	},
 	{
 		.procname	= "watermark_scale_factor",
···
 		.maxlen		= sizeof(watermark_scale_factor),
 		.mode		= 0644,
 		.proc_handler	= watermark_scale_factor_sysctl_handler,
-		.extra1		= &one,
+		.extra1		= SYSCTL_ONE,
 		.extra2		= &one_thousand,
 	},
 	{
···
 		.maxlen		= sizeof(percpu_pagelist_fraction),
 		.mode		= 0644,
 		.proc_handler	= percpu_pagelist_fraction_sysctl_handler,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 	},
 #ifdef CONFIG_MMU
 	{
···
 		.maxlen		= sizeof(sysctl_max_map_count),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 	},
 #else
 	{
···
 		.maxlen		= sizeof(sysctl_nr_trim_pages),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 	},
 #endif
 	{
···
 		.maxlen		= sizeof(block_dump),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 	},
 	{
 		.procname	= "vfs_cache_pressure",
···
 		.maxlen		= sizeof(sysctl_vfs_cache_pressure),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 	},
 #ifdef HAVE_ARCH_PICK_MMAP_LAYOUT
 	{
···
 		.maxlen		= sizeof(sysctl_legacy_va_layout),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 	},
 #endif
 #ifdef CONFIG_NUMA
···
 		.maxlen		= sizeof(node_reclaim_mode),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 	},
 	{
 		.procname	= "min_unmapped_ratio",
···
 		.maxlen		= sizeof(sysctl_min_unmapped_ratio),
 		.mode		= 0644,
 		.proc_handler	= sysctl_min_unmapped_ratio_sysctl_handler,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &one_hundred,
 	},
 	{
···
 		.maxlen		= sizeof(sysctl_min_slab_ratio),
 		.mode		= 0644,
 		.proc_handler	= sysctl_min_slab_ratio_sysctl_handler,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &one_hundred,
 	},
 #endif
···
 #endif
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 	},
 #endif
 #ifdef CONFIG_HIGHMEM
···
 		.maxlen		= sizeof(vm_highmem_is_dirtyable),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 #endif
 #ifdef CONFIG_MEMORY_FAILURE
···
 		.maxlen		= sizeof(sysctl_memory_failure_early_kill),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 	{
 		.procname	= "memory_failure_recovery",
···
 		.maxlen		= sizeof(sysctl_memory_failure_recovery),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 #endif
 	{
···
 		.maxlen		= sizeof(sysctl_unprivileged_userfaultfd),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 #endif
 	{ }
···
 		.maxlen		= sizeof(int),
 		.mode		= 0600,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 	{
 		.procname	= "protected_hardlinks",
···
 		.maxlen		= sizeof(int),
 		.mode		= 0600,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 	{
 		.procname	= "protected_fifos",
···
 		.maxlen		= sizeof(int),
 		.mode		= 0600,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &two,
 	},
 	{
···
 		.maxlen		= sizeof(int),
 		.mode		= 0600,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &two,
 	},
 	{
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax_coredump,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &two,
 	},
 #if defined(CONFIG_BINFMT_MISC) || defined(CONFIG_BINFMT_MISC_MODULE)
···
 		.maxlen		= sizeof(unsigned int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &one,
+		.extra1		= SYSCTL_ONE,
 	},
 	{ }
 };
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_kprobes_optimization_handler,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 #endif
 	{ }
···
 		.data   = &val,
 		.maxlen = sizeof(val),
 		.mode   = table->mode,
-		.extra1 = &zero,
-		.extra2 = &one,
+		.extra1 = SYSCTL_ZERO,
+		.extra2 = SYSCTL_ONE,
 	};
 
 	if (write && !capable(CAP_SYS_ADMIN))

kernel/ucount.c

···
 	.permissions = set_permissions,
 };
 
-static int zero = 0;
-static int int_max = INT_MAX;
 #define UCOUNT_ENTRY(name)				\
 	{						\
 		.procname	= name,			\
 		.maxlen		= sizeof(int),		\
 		.mode		= 0644,			\
 		.proc_handler	= proc_dointvec_minmax,	\
-		.extra1		= &zero,		\
-		.extra2		= &int_max,		\
+		.extra1		= SYSCTL_ZERO,		\
+		.extra2		= SYSCTL_INT_MAX,	\
 	}
 static struct ctl_table user_table[] = {
 	UCOUNT_ENTRY("max_user_namespaces"),

net/core/neighbour.c

···
 EXPORT_SYMBOL(neigh_app_ns);
 
 #ifdef CONFIG_SYSCTL
-static int zero;
-static int int_max = INT_MAX;
 static int unres_qlen_max = INT_MAX / SKB_TRUESIZE(ETH_FRAME_LEN);
 
 static int proc_unres_qlen(struct ctl_table *ctl, int write,
···
 	int size, ret;
 	struct ctl_table tmp = *ctl;
 
-	tmp.extra1 = &zero;
+	tmp.extra1 = SYSCTL_ZERO;
 	tmp.extra2 = &unres_qlen_max;
 	tmp.data = &size;
 
···
 	struct ctl_table tmp = *ctl;
 	int ret;
 
-	tmp.extra1 = &zero;
-	tmp.extra2 = &int_max;
+	tmp.extra1 = SYSCTL_ZERO;
+	tmp.extra2 = SYSCTL_INT_MAX;
 
 	ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
 	neigh_proc_update(ctl, write);
···
 			.procname	= "gc_thresh1",
 			.maxlen		= sizeof(int),
 			.mode		= 0644,
-			.extra1 	= &zero,
-			.extra2		= &int_max,
+			.extra1		= SYSCTL_ZERO,
+			.extra2		= SYSCTL_INT_MAX,
 			.proc_handler	= proc_dointvec_minmax,
 		},
 		[NEIGH_VAR_GC_THRESH2] = {
 			.procname	= "gc_thresh2",
 			.maxlen		= sizeof(int),
 			.mode		= 0644,
-			.extra1 	= &zero,
-			.extra2		= &int_max,
+			.extra1		= SYSCTL_ZERO,
+			.extra2		= SYSCTL_INT_MAX,
 			.proc_handler	= proc_dointvec_minmax,
 		},
 		[NEIGH_VAR_GC_THRESH3] = {
 			.procname	= "gc_thresh3",
 			.maxlen		= sizeof(int),
 			.mode		= 0644,
-			.extra1 	= &zero,
-			.extra2		= &int_max,
+			.extra1		= SYSCTL_ZERO,
+			.extra2		= SYSCTL_INT_MAX,
 			.proc_handler	= proc_dointvec_minmax,
 		},
 		{},

net/core/sysctl_net_core.c

···
 #include <net/busy_poll.h>
 #include <net/pkt_sched.h>
 
-static int zero = 0;
-static int one = 1;
 static int two __maybe_unused = 2;
 static int min_sndbuf = SOCK_MIN_SNDBUF;
 static int min_rcvbuf = SOCK_MIN_RCVBUF;
···
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax_bpf_enable,
 # ifdef CONFIG_BPF_JIT_ALWAYS_ON
-		.extra1		= &one,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ONE,
+		.extra2		= SYSCTL_ONE,
 # else
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &two,
 # endif
 	},
···
 		.maxlen		= sizeof(int),
 		.mode		= 0600,
 		.proc_handler	= proc_dointvec_minmax_bpf_restricted,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &two,
 	},
 	{
···
 		.maxlen		= sizeof(int),
 		.mode		= 0600,
 		.proc_handler	= proc_dointvec_minmax_bpf_restricted,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 # endif
 	{
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
-		.extra2		= &one
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE
 	},
 #ifdef CONFIG_RPS
 	{
···
 		.maxlen		= sizeof(unsigned int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 	},
 	{
 		.procname	= "busy_read",
···
 		.maxlen		= sizeof(unsigned int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 	},
 #endif
 #ifdef CONFIG_NET_SCHED
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &one,
+		.extra1		= SYSCTL_ONE,
 		.extra2		= &max_skb_frags,
 	},
 	{
···
 		.maxlen		= sizeof(unsigned int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 	},
 	{
 		.procname	= "fb_tunnels_only_for_init_net",
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 	{
 		.procname	= "devconf_inherit_init_net",
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &two,
 	},
 	{
···
 		.data		= &init_net.core.sysctl_somaxconn,
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.proc_handler	= proc_dointvec_minmax
 	},
 	{ }

net/dccp/sysctl.c

···
 #endif
 
 /* Boundary values */
-static int		zero     = 0,
-			one      = 1,
-			u8_max   = 0xFF;
+static int		u8_max   = 0xFF;
 static unsigned long	seqw_min = DCCPF_SEQ_WMIN,
 			seqw_max = 0xFFFFFFFF;		/* maximum on 32 bit */
 
···
 		.maxlen		= sizeof(sysctl_dccp_rx_ccid),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &u8_max,		/* RFC 4340, 10. */
 	},
 	{
···
 		.maxlen		= sizeof(sysctl_dccp_tx_ccid),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &u8_max,		/* RFC 4340, 10. */
 	},
 	{
···
 		.maxlen		= sizeof(sysctl_dccp_request_retries),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &one,
+		.extra1		= SYSCTL_ONE,
 		.extra2		= &u8_max,
 	},
 	{
···
 		.maxlen		= sizeof(sysctl_dccp_retries1),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &u8_max,
 	},
 	{
···
 		.maxlen		= sizeof(sysctl_dccp_retries2),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &u8_max,
 	},
 	{
···
 		.maxlen		= sizeof(sysctl_dccp_tx_qlen),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 	},
 	{
 		.procname	= "sync_ratelimit",

net/ipv4/sysctl_net_ipv4.c

···
 #include <net/protocol.h>
 #include <net/netevent.h>
 
-static int zero;
-static int one = 1;
 static int two = 2;
 static int four = 4;
 static int thousand = 1000;
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 	},
 	{
 		.procname	= "icmp_msgs_burst",
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 	},
 	{
 		.procname	= "udp_mem",
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 #endif
 	{
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler   = ipv4_fwd_update_priority,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 	{
 		.procname	= "ip_nonlocal_bind",
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 #endif
 	{
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &one
+		.extra1		= SYSCTL_ONE
 	},
 #endif
 	{
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &two,
 	},
 	{
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_tfo_blackhole_detect_timeout,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 	},
 #ifdef CONFIG_IP_ROUTE_MULTIPATH
 	{
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 	{
 		.procname	= "fib_multipath_hash_policy",
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_fib_multipath_hash_policy,
-		.extra1		= &zero,
-		.extra2		= &two,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 #endif
 	{
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 #endif
 	{
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &four,
 	},
 	{
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &one,
+		.extra1		= SYSCTL_ONE,
 		.extra2		= &gso_max_segs,
 	},
 	{
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &one_day_secs
 	},
 	{
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 	{
 		.procname	= "tcp_invalid_ratelimit",
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &thousand,
 	},
 	{
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &thousand,
 	},
 	{
···
 		.maxlen		= sizeof(init_net.ipv4.sysctl_tcp_wmem),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &one,
+		.extra1		= SYSCTL_ONE,
 	},
 	{
 		.procname	= "tcp_rmem",
···
 		.maxlen		= sizeof(init_net.ipv4.sysctl_tcp_rmem),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &one,
+		.extra1		= SYSCTL_ONE,
 	},
 	{
 		.procname	= "tcp_comp_sack_delay_ns",
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &comp_sack_nr_max,
 	},
 	{
···
 		.maxlen		= sizeof(init_net.ipv4.sysctl_udp_rmem_min),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &one
+		.extra1		= SYSCTL_ONE
 	},
 	{
 		.procname	= "udp_wmem_min",
···
 		.maxlen		= sizeof(init_net.ipv4.sysctl_udp_wmem_min),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &one
+		.extra1		= SYSCTL_ONE
 	},
 	{ }
 };

net/ipv6/addrconf.c

···
 }
 
 static int minus_one = -1;
-static const int zero = 0;
-static const int one = 1;
 static const int two_five_five = 255;
 
 static const struct ctl_table addrconf_sysctl[] = {
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= (void *)&one,
+		.extra1		= (void *)SYSCTL_ONE,
 		.extra2		= (void *)&two_five_five,
 	},
 	{
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= (void *)&zero,
+		.extra1		= (void *)SYSCTL_ZERO,
 		.extra2		= (void *)&two_five_five,
 	},
 	{

net/ipv6/route.c

···
 	return 0;
 }
 
-static int zero;
-static int one = 1;
-
 static struct ctl_table ipv6_route_table_template[] = {
 	{
 		.procname	=	"flush",
···
 		.maxlen		=	sizeof(int),
 		.mode		=	0644,
 		.proc_handler	=	proc_dointvec_minmax,
-		.extra1		=	&zero,
-		.extra2		=	&one,
+		.extra1		=	SYSCTL_ZERO,
+		.extra2		=	SYSCTL_ONE,
 	},
 	{ }
 };

net/ipv6/sysctl_net_ipv6.c

···
 #include <net/calipso.h>
 #endif
 
-static int zero;
-static int one = 1;
 static int flowlabel_reflect_max = 0x7;
 static int auto_flowlabels_min;
 static int auto_flowlabels_max = IP6_AUTO_FLOW_LABEL_MAX;
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &flowlabel_reflect_max,
 	},
 	{
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler   = proc_rt6_multipath_hash_policy,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 	{
 		.procname	= "seg6_flowlabel",
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &one
+		.extra1		= SYSCTL_ONE
 	},
 #ifdef CONFIG_NETLABEL
 	{

net/mpls/af_mpls.c

···
 
 #define MPLS_NEIGH_TABLE_UNSPEC (NEIGH_LINK_TABLE + 1)
 
-static int zero = 0;
-static int one = 1;
 static int label_limit = (1 << 20) - 1;
 static int ttl_max = 255;
 
···
 		.data		= &platform_labels,
 		.maxlen		= sizeof(int),
 		.mode		= table->mode,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &label_limit,
 	};
 
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
-		.extra2		= &one,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
 	},
 	{
 		.procname	= "default_ttl",
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &one,
+		.extra1		= SYSCTL_ONE,
 		.extra2		= &ttl_max,
 	},
 	{ }

net/netfilter/ipvs/ip_vs_ctl.c

···
 
 #ifdef CONFIG_SYSCTL
 
-static int zero;
 static int three = 3;
 
 static int
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &three,
 	},
 	{

net/rxrpc/sysctl.c

···
 #include "ar-internal.h"
 
 static struct ctl_table_header *rxrpc_sysctl_reg_table;
-static const unsigned int one = 1;
 static const unsigned int four = 4;
 static const unsigned int thirtytwo = 32;
 static const unsigned int n_65535 = 65535;
···
 		.maxlen		= sizeof(unsigned int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= (void *)&one,
+		.extra1		= (void *)SYSCTL_ONE,
 		.extra2		= (void *)&rxrpc_max_client_connections,
 	},
 	{
···
 		.maxlen		= sizeof(unsigned int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= (void *)&one,
+		.extra1		= (void *)SYSCTL_ONE,
 		.extra2		= (void *)&n_max_acks,
 	},
 	{
···
 		.maxlen		= sizeof(unsigned int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= (void *)&one,
+		.extra1		= (void *)SYSCTL_ONE,
 		.extra2		= (void *)&n_65535,
 	},
 	{
···
 		.maxlen		= sizeof(unsigned int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= (void *)&one,
+		.extra1		= (void *)SYSCTL_ONE,
 		.extra2		= (void *)&four,
 	},
 

net/sctp/sysctl.c

···
 #include <net/sctp/sctp.h>
 #include <linux/sysctl.h>
 
-static int zero = 0;
-static int one = 1;
 static int timer_max = 86400000; /* ms in one day */
-static int int_max = INT_MAX;
 static int sack_timer_min = 1;
 static int sack_timer_max = 500;
 static int addr_scope_max = SCTP_SCOPE_POLICY_MAX;
···
 		.maxlen		= sizeof(unsigned int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1         = &one,
+		.extra1         = SYSCTL_ONE,
 		.extra2         = &timer_max
 	},
 	{
···
 		.maxlen		= sizeof(unsigned int),
 		.mode		= 0644,
 		.proc_handler	= proc_sctp_do_rto_min,
-		.extra1         = &one,
+		.extra1         = SYSCTL_ONE,
 		.extra2         = &init_net.sctp.rto_max
 	},
 	{
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
-		.extra2		= &int_max
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_INT_MAX,
 	},
 	{
 		.procname	= "cookie_preserve_enable",
···
 		.maxlen		= sizeof(unsigned int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1         = &one,
+		.extra1         = SYSCTL_ONE,
 		.extra2         = &timer_max
 	},
 	{
···
 		.maxlen		= sizeof(unsigned int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1         = &one,
+		.extra1         = SYSCTL_ONE,
 		.extra2         = &timer_max
 	},
 	{
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &one,
-		.extra2		= &int_max
+		.extra1		= SYSCTL_ONE,
+		.extra2		= SYSCTL_INT_MAX,
 	},
 	{
 		.procname	= "path_max_retrans",
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &one,
-		.extra2		= &int_max
+		.extra1		= SYSCTL_ONE,
+		.extra2		= SYSCTL_INT_MAX,
 	},
 	{
 		.procname	= "max_init_retransmits",
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &one,
-		.extra2		= &int_max
+		.extra1		= SYSCTL_ONE,
+		.extra2		= SYSCTL_INT_MAX,
 	},
 	{
 		.procname	= "pf_retrans",
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
-		.extra2		= &int_max
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_INT_MAX,
 	},
 	{
 		.procname	= "sndbuf_policy",
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &addr_scope_max,
 	},
 	{
···
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= &proc_dointvec_minmax,
-		.extra1		= &one,
+		.extra1		= SYSCTL_ONE,
 		.extra2		= &rwnd_scale_max,
 	},
 	{

net/sunrpc/xprtrdma/transport.c

···
 static unsigned int max_slot_table_size = RPCRDMA_MAX_SLOT_TABLE;
 static unsigned int min_inline_size = RPCRDMA_MIN_INLINE;
 static unsigned int max_inline_size = RPCRDMA_MAX_INLINE;
-static unsigned int zero;
 static unsigned int max_padding = PAGE_SIZE;
 static unsigned int min_memreg = RPCRDMA_BOUNCEBUFFERS;
 static unsigned int max_memreg = RPCRDMA_LAST - 1;
···
 		.maxlen		= sizeof(unsigned int),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1		= &zero,
+		.extra1		= SYSCTL_ZERO,
 		.extra2		= &max_padding,
 	},
 	{

net/tipc/sysctl.c

···
 
 #include <linux/sysctl.h>
 
-static int zero;
-static int one = 1;
 static struct ctl_table_header *tipc_ctl_hdr;
 
 static struct ctl_table tipc_table[] = {
···
 		.maxlen		= sizeof(sysctl_tipc_rmem),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1         = &one,
+		.extra1         = SYSCTL_ONE,
 	},
 	{
 		.procname	= "named_timeout",
···
 		.maxlen		= sizeof(sysctl_tipc_named_timeout),
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
-		.extra1         = &zero,
+		.extra1         = SYSCTL_ZERO,
 	},
 	{
 		.procname       = "sk_filter",

security/keys/sysctl.c

···
 #include <linux/sysctl.h>
 #include "internal.h"
 
-static const int zero, one = 1, max = INT_MAX;
-
 struct ctl_table key_sysctls[] = {
 	{
 		.procname = "maxkeys",
···
 		.maxlen = sizeof(unsigned),
 		.mode = 0644,
 		.proc_handler = proc_dointvec_minmax,
-		.extra1 = (void *) &one,
-		.extra2 = (void *) &max,
+		.extra1 = (void *) SYSCTL_ONE,
+		.extra2 = (void *) SYSCTL_INT_MAX,
 	},
 	{
 		.procname = "maxbytes",
···
 		.maxlen = sizeof(unsigned),
 		.mode = 0644,
 		.proc_handler = proc_dointvec_minmax,
-		.extra1 = (void *) &one,
-		.extra2 = (void *) &max,
+		.extra1 = (void *) SYSCTL_ONE,
+		.extra2 = (void *) SYSCTL_INT_MAX,
 	},
 	{
 		.procname = "root_maxkeys",
···
 		.maxlen = sizeof(unsigned),
 		.mode = 0644,
 		.proc_handler = proc_dointvec_minmax,
-		.extra1 = (void *) &one,
-		.extra2 = (void *) &max,
+		.extra1 = (void *) SYSCTL_ONE,
+		.extra2 = (void *) SYSCTL_INT_MAX,
 	},
 	{
 		.procname = "root_maxbytes",
···
 		.maxlen = sizeof(unsigned),
 		.mode = 0644,
 		.proc_handler = proc_dointvec_minmax,
-		.extra1 = (void *) &one,
-		.extra2 = (void *) &max,
+		.extra1 = (void *) SYSCTL_ONE,
+		.extra2 = (void *) SYSCTL_INT_MAX,
 	},
 	{
 		.procname = "gc_delay",
···
 		.maxlen = sizeof(unsigned),
 		.mode = 0644,
 		.proc_handler = proc_dointvec_minmax,
-		.extra1 = (void *) &zero,
-		.extra2 = (void *) &max,
+		.extra1 = (void *) SYSCTL_ZERO,
+		.extra2 = (void *) SYSCTL_INT_MAX,
 	},
 #ifdef CONFIG_PERSISTENT_KEYRINGS
 	{
···
 		.maxlen = sizeof(unsigned),
 		.mode = 0644,
 		.proc_handler = proc_dointvec_minmax,
-		.extra1 = (void *) &zero,
-		.extra2 = (void *) &max,
+		.extra1 = (void *) SYSCTL_ZERO,
+		.extra2 = (void *) SYSCTL_INT_MAX,
 	},
 #endif
 	{ }

security/loadpin/loadpin.c

···
 static DEFINE_SPINLOCK(pinned_root_spinlock);
 
 #ifdef CONFIG_SYSCTL
-static int zero;
-static int one = 1;
 
 static struct ctl_path loadpin_sysctl_path[] = {
 	{ .procname = "kernel", },
···
 		.maxlen         = sizeof(int),
 		.mode           = 0644,
 		.proc_handler   = proc_dointvec_minmax,
-		.extra1         = &zero,
-		.extra2         = &one,
+		.extra1         = SYSCTL_ZERO,
+		.extra2         = SYSCTL_ONE,
 	},
 	{ }
 };

security/yama/yama_lsm.c

···
 	return proc_dointvec_minmax(&table_copy, write, buffer, lenp, ppos);
 }
 
-static int zero;
 static int max_scope = YAMA_SCOPE_NO_ATTACH;
 
 static struct ctl_path yama_sysctl_path[] = {
···
 		.maxlen         = sizeof(int),
 		.mode           = 0644,
 		.proc_handler   = yama_dointvec_minmax,
-		.extra1         = &zero,
+		.extra1         = SYSCTL_ZERO,
 		.extra2         = &max_scope,
 	},
 	{ }