/* * sysctl.c: General linux system control interface * * Begun 24 March 1995, Stephen Tweedie * Added /proc support, Dec 1995 * Added bdflush entry and intvec min/max checking, 2/23/96, Tom Dyas. * Added hooks for /proc/sys/net (minor, minor patch), 96/4/1, Mike Shaver. * Added kernel/java-{interpreter,appletviewer}, 96/5/10, Mike Shaver. * Dynamic registration fixes, Stephen Tweedie. * Added kswapd-interval, ctrl-alt-del, printk stuff, 1/8/97, Chris Horn. * Made sysctl support optional via CONFIG_SYSCTL, 1/10/97, Chris *  Horn. * Added proc_doulongvec_ms_jiffies_minmax, 09/08/99, Carlos H. Bauer. * Added proc_doulongvec_minmax, 09/08/99, Carlos H. Bauer. * Changed linked lists to use list.h instead of lists.h, 02/24/00, Bill *  Wendling. * The list_for_each() macro wasn't appropriate for the sysctl loop. *  Removed it and replaced it with older style, 03/23/00, Bill Wendling */ #include <linux/module.h>#include <linux/mm.h>#include <linux/swap.h>#include <linux/slab.h>#include <linux/sysctl.h>#include <linux/signal.h>#include <linux/proc_fs.h>#include <linux/security.h>#include <linux/ctype.h>#include <linux/kmemcheck.h>#include <linux/fs.h>#include <linux/init.h>#include <linux/kernel.h>#include <linux/kobject.h>#include <linux/net.h>#include <linux/sysrq.h>#include <linux/highuid.h>#include <linux/writeback.h>#include <linux/ratelimit.h>#include <linux/compaction.h>#include <linux/hugetlb.h>#include <linux/initrd.h>#include <linux/key.h>#include <linux/times.h>#include <linux/limits.h>#include <linux/dcache.h>#include <linux/dnotify.h>#include <linux/syscalls.h>#include <linux/vmstat.h>#include <linux/nfs_fs.h>#include <linux/acpi.h>#include <linux/reboot.h>#include <linux/ftrace.h>#include <linux/perf_event.h>#include <linux/kprobes.h>#include <linux/pipe_fs_i.h>#include <linux/oom.h> #include <asm/uaccess.h>#include <asm/processor.h> #ifdef CONFIG_X86#include <asm/nmi.h>#include <asm/stacktrace.h>#include <asm/io.h>#endif#ifdef CONFIG_BSD_PROCESS_ACCT#include <linux/acct.h>#endif#ifdef CONFIG_RT_MUTEXES#include <linux/rtmutex.h>#endif#if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_LOCK_STAT)#include <linux/lockdep.h>#endif#ifdef CONFIG_CHR_DEV_SG#include <scsi/sg.h>#endif #ifdef CONFIG_LOCKUP_DETECTOR#include <linux/nmi.h>#endif  #if defined(CONFIG_SYSCTL) /* External variables not in a header file. */extern int sysctl_overcommit_memory;extern int sysctl_overcommit_ratio;extern int max_threads;extern int core_uses_pid;extern int suid_dumpable;extern char core_pattern[];extern unsigned int core_pipe_limit;extern int pid_max;extern int min_free_kbytes;extern int pid_max_min, pid_max_max;extern int sysctl_drop_caches;extern int percpu_pagelist_fraction;extern int compat_log;extern int latencytop_enabled;extern int sysctl_nr_open_min, sysctl_nr_open_max;#ifndef CONFIG_MMUextern int sysctl_nr_trim_pages;#endif#ifdef CONFIG_BLOCKextern int blk_iopoll_enabled;#endif /* Constants used for minimum and  maximum */#ifdef CONFIG_LOCKUP_DETECTORstatic int sixty = 60;static int neg_one = -1;#endif static int zero;static int __maybe_unused one = 1;static int __maybe_unused two = 2;static unsigned long one_ul = 1;static int one_hundred = 100;#ifdef CONFIG_PRINTKstatic int ten_thousand = 10000;#endif /* this is needed for the proc_doulongvec_minmax of vm_dirty_bytes */static 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 int min_percpu_pagelist_fract = 8; static int ngroups_max = NGROUPS_MAX; #ifdef CONFIG_INOTIFY_USER#include <linux/inotify.h>#endif#ifdef CONFIG_SPARC#include <asm/system.h>#endif #ifdef CONFIG_SPARC64extern int sysctl_tsb_ratio;#endif #ifdef __hppa__extern int pwrsw_enabled;extern int unaligned_enabled;#endif #ifdef CONFIG_S390#ifdef CONFIG_MATHEMUextern int sysctl_ieee_emulation_warnings;#endifextern int sysctl_userprocess_debug;extern int spin_retry;#endif #ifdef CONFIG_IA64extern int no_unaligned_warning;extern int unaligned_dump_stack;#endif #ifdef CONFIG_PROC_SYSCTLstatic int proc_do_cad_pid(struct ctl_table *table, int write,		  void __user *buffer, size_t *lenp, loff_t *ppos);static int proc_taint(struct ctl_table *table, int write,			       void __user *buffer, size_t *lenp, loff_t *ppos);#endif #ifdef CONFIG_MAGIC_SYSRQstatic int __sysrq_enabled; /* Note: sysrq code ises it's own private copy */ static int sysrq_sysctl_handler(ctl_table *table, int write,				void __user *buffer, size_t *lenp,				loff_t *ppos){	int error; 	error = proc_dointvec(table, write, buffer, lenp, ppos);	if (error)		return error; 	if (write)		sysrq_toggle_support(__sysrq_enabled); 	return 0;} #endif static struct ctl_table root_table[];static struct ctl_table_root sysctl_table_root;static struct ctl_table_header root_table_header = {	.count = 1,	.ctl_table = root_table,	.ctl_entry = LIST_HEAD_INIT(sysctl_table_root.default_set.list),	.root = &sysctl_table_root,	.set = &sysctl_table_root.default_set,};static struct ctl_table_root sysctl_table_root = {	.root_list = LIST_HEAD_INIT(sysctl_table_root.root_list),	.default_set.list = LIST_HEAD_INIT(root_table_header.ctl_entry),}; static struct ctl_table kern_table[];static struct ctl_table vm_table[];static struct ctl_table fs_table[];static struct ctl_table debug_table[];static struct ctl_table dev_table[];extern struct ctl_table random_table[];#ifdef CONFIG_EPOLLextern struct ctl_table epoll_table[];#endif #ifdef HAVE_ARCH_PICK_MMAP_LAYOUTint sysctl_legacy_va_layout;#endif /* The default sysctl tables: */ static struct ctl_table root_table[] = {	{		.procname	= "kernel",		.mode		= 0555,		.child		= kern_table,	},	{		.procname	= "vm",		.mode		= 0555,		.child		= vm_table,	},	{		.procname	= "fs",		.mode		= 0555,		.child		= fs_table,	},	{		.procname	= "debug",		.mode		= 0555,		.child		= debug_table,	},	{		.procname	= "dev",		.mode		= 0555,		.child		= dev_table,	},/* * NOTE: do not add new entries to this table unless you have read * Documentation/sysctl/ctl_unnumbered.txt */	{ }}; #ifdef CONFIG_SCHED_DEBUGstatic int min_sched_granularity_ns = 100000;		/* 100 usecs */static int max_sched_granularity_ns = NSEC_PER_SEC;	/* 1 second */static int min_wakeup_granularity_ns;			/* 0 usecs */static int max_wakeup_granularity_ns = NSEC_PER_SEC;	/* 1 second */static int min_sched_tunable_scaling = SCHED_TUNABLESCALING_NONE;static int max_sched_tunable_scaling = SCHED_TUNABLESCALING_END-1;static int min_sched_shares_ratelimit = 100000; /* 100 usec */static int max_sched_shares_ratelimit = NSEC_PER_SEC; /* 1 second */#endif #ifdef CONFIG_COMPACTIONstatic int min_extfrag_threshold;static int max_extfrag_threshold = 1000;#endif static struct ctl_table kern_table[] = {	{		.procname	= "sched_child_runs_first",		.data		= &sysctl_sched_child_runs_first,		.maxlen		= sizeof(unsigned int),		.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		= &min_sched_granularity_ns,		.extra2		= &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		= &min_sched_granularity_ns,		.extra2		= &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		= &min_wakeup_granularity_ns,		.extra2		= &max_wakeup_granularity_ns,	},	{		.procname	= "sched_shares_ratelimit",		.data		= &sysctl_sched_shares_ratelimit,		.maxlen		= sizeof(unsigned int),		.mode		= 0644,		.proc_handler	= sched_proc_update_handler,		.extra1		= &min_sched_shares_ratelimit,		.extra2		= &max_sched_shares_ratelimit,	},	{		.procname	= "sched_tunable_scaling",		.data		= &sysctl_sched_tunable_scaling,		.maxlen		= sizeof(enum sched_tunable_scaling),		.mode		= 0644,		.proc_handler	= sched_proc_update_handler,		.extra1		= &min_sched_tunable_scaling,		.extra2		= &max_sched_tunable_scaling,	},	{		.procname	= "sched_shares_thresh",		.data		= &sysctl_sched_shares_thresh,		.maxlen		= sizeof(unsigned int),		.mode		= 0644,		.proc_handler	= proc_dointvec_minmax,		.extra1		= &zero,	},	{		.procname	= "sched_migration_cost",		.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,	},	{		.procname	= "sched_time_avg",		.data		= &sysctl_sched_time_avg,		.maxlen		= sizeof(unsigned int),		.mode		= 0644,		.proc_handler	= proc_dointvec,	},	{		.procname	= "timer_migration",		.data		= &sysctl_timer_migration,		.maxlen		= sizeof(unsigned int),		.mode		= 0644,		.proc_handler	= proc_dointvec_minmax,		.extra1		= &zero,		.extra2		= &one,	},#endif	{		.procname	= "sched_rt_period_us",		.data		= &sysctl_sched_rt_period,		.maxlen		= sizeof(unsigned int),		.mode		= 0644,		.proc_handler	= sched_rt_handler,	},	{		.procname	= "sched_rt_runtime_us",		.data		= &sysctl_sched_rt_runtime,		.maxlen		= sizeof(int),		.mode		= 0644,		.proc_handler	= sched_rt_handler,	},	{		.procname	= "sched_compat_yield",		.data		= &sysctl_sched_compat_yield,		.maxlen		= sizeof(unsigned int),		.mode		= 0644,		.proc_handler	= proc_dointvec,	},#ifdef CONFIG_PROVE_LOCKING	{		.procname	= "prove_locking",		.data		= &prove_locking,		.maxlen		= sizeof(int),		.mode		= 0644,		.proc_handler	= proc_dointvec,	},#endif#ifdef CONFIG_LOCK_STAT	{		.procname	= "lock_stat",		.data		= &lock_stat,		.maxlen		= sizeof(int),		.mode		= 0644,		.proc_handler	= proc_dointvec,	},#endif	{		.procname	= "panic",		.data		= &panic_timeout,		.maxlen		= sizeof(int),		.mode		= 0644,		.proc_handler	= proc_dointvec,	},	{		.procname	= "core_uses_pid",		.data		= &core_uses_pid,		.maxlen		= sizeof(int),		.mode		= 0644,		.proc_handler	= proc_dointvec,	},	{		.procname	= "core_pattern",		.data		= core_pattern,		.maxlen		= CORENAME_MAX_SIZE,		.mode		= 0644,		.proc_handler	= proc_dostring,	},	{		.procname	= "core_pipe_limit",		.data		= &core_pipe_limit,		.maxlen		= sizeof(unsigned int),		.mode		= 0644,		.proc_handler	= proc_dointvec,	},#ifdef CONFIG_PROC_SYSCTL	{		.procname	= "tainted",		.maxlen 	= sizeof(long),		.mode		= 0644,		.proc_handler	= proc_taint,	},#endif#ifdef CONFIG_LATENCYTOP	{		.procname	= "latencytop",		.data		= &latencytop_enabled,		.maxlen		= sizeof(int),		.mode		= 0644,		.proc_handler	= proc_dointvec,	},#endif#ifdef CONFIG_BLK_DEV_INITRD	{		.procname	= "real-root-dev",		.data		= &real_root_dev,		.maxlen		= sizeof(int),		.mode		= 0644,		.proc_handler	= proc_dointvec,	},#endif	{		.procname	= "print-fatal-signals",		.data		= &print_fatal_signals,		.maxlen		= sizeof(int),		.mode		= 0644,		.proc_handler	= proc_dointvec,	},#ifdef CONFIG_SPARC	{		.procname	= "reboot-cmd",		.data		= reboot_command,		.maxlen		= 256,		.mode		= 0644,		.proc_handler	= proc_dostring,	},	{		.procname	= "stop-a",		.data		= &stop_a_enabled,		.maxlen		= sizeof (int),		.mode		= 0644,		.proc_handler	= proc_dointvec,	},	{		.procname	= "scons-poweroff",		.data		= &scons_pwroff,		.maxlen		= sizeof (int),		.mode		= 0644,		.proc_handler	= proc_dointvec,	},#endif#ifdef CONFIG_SPARC64	{		.procname	= "tsb-ratio",		.data		= &sysctl_tsb_ratio,		.maxlen		= sizeof (int),		.mode		= 0644,		.proc_handler	= proc_dointvec,	},#endif#ifdef __hppa__	{		.procname	= "soft-power",		.data		= &pwrsw_enabled,		.maxlen		= sizeof (int),

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