linux/include/linux/sysctl.h
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   1/*
   2 * sysctl.h: General linux system control interface
   3 *
   4 * Begun 24 March 1995, Stephen Tweedie
   5 *
   6 ****************************************************************
   7 ****************************************************************
   8 **
   9 **  WARNING:
  10 **  The values in this file are exported to user space via 
  11 **  the sysctl() binary interface.  Do *NOT* change the
  12 **  numbering of any existing values here, and do not change
  13 **  any numbers within any one set of values.  If you have to
  14 **  redefine an existing interface, use a new number for it.
  15 **  The kernel will then return -ENOTDIR to any application using
  16 **  the old binary interface.
  17 **
  18 ****************************************************************
  19 ****************************************************************
  20 */
  21#ifndef _LINUX_SYSCTL_H
  22#define _LINUX_SYSCTL_H
  23
  24#include <linux/list.h>
  25#include <linux/rcupdate.h>
  26#include <linux/wait.h>
  27#include <linux/rbtree.h>
  28#include <uapi/linux/sysctl.h>
  29
  30/* For the /proc/sys support */
  31struct ctl_table;
  32struct nsproxy;
  33struct ctl_table_root;
  34struct ctl_table_header;
  35struct ctl_dir;
  36
  37typedef struct ctl_table ctl_table;
  38
  39typedef int proc_handler (struct ctl_table *ctl, int write,
  40                          void __user *buffer, size_t *lenp, loff_t *ppos);
  41
  42extern int proc_dostring(struct ctl_table *, int,
  43                         void __user *, size_t *, loff_t *);
  44extern int proc_dointvec(struct ctl_table *, int,
  45                         void __user *, size_t *, loff_t *);
  46extern int proc_dointvec_minmax(struct ctl_table *, int,
  47                                void __user *, size_t *, loff_t *);
  48extern int proc_dointvec_jiffies(struct ctl_table *, int,
  49                                 void __user *, size_t *, loff_t *);
  50extern int proc_dointvec_userhz_jiffies(struct ctl_table *, int,
  51                                        void __user *, size_t *, loff_t *);
  52extern int proc_dointvec_ms_jiffies(struct ctl_table *, int,
  53                                    void __user *, size_t *, loff_t *);
  54extern int proc_doulongvec_minmax(struct ctl_table *, int,
  55                                  void __user *, size_t *, loff_t *);
  56extern int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int,
  57                                      void __user *, size_t *, loff_t *);
  58extern int proc_do_large_bitmap(struct ctl_table *, int,
  59                                void __user *, size_t *, loff_t *);
  60
  61/*
  62 * Register a set of sysctl names by calling register_sysctl_table
  63 * with an initialised array of struct ctl_table's.  An entry with 
  64 * NULL procname terminates the table.  table->de will be
  65 * set up by the registration and need not be initialised in advance.
  66 *
  67 * sysctl names can be mirrored automatically under /proc/sys.  The
  68 * procname supplied controls /proc naming.
  69 *
  70 * The table's mode will be honoured both for sys_sysctl(2) and
  71 * proc-fs access.
  72 *
  73 * Leaf nodes in the sysctl tree will be represented by a single file
  74 * under /proc; non-leaf nodes will be represented by directories.  A
  75 * null procname disables /proc mirroring at this node.
  76 *
  77 * sysctl(2) can automatically manage read and write requests through
  78 * the sysctl table.  The data and maxlen fields of the ctl_table
  79 * struct enable minimal validation of the values being written to be
  80 * performed, and the mode field allows minimal authentication.
  81 * 
  82 * There must be a proc_handler routine for any terminal nodes
  83 * mirrored under /proc/sys (non-terminals are handled by a built-in
  84 * directory handler).  Several default handlers are available to
  85 * cover common cases.
  86 */
  87
  88/* Support for userspace poll() to watch for changes */
  89struct ctl_table_poll {
  90        atomic_t event;
  91        wait_queue_head_t wait;
  92};
  93
  94static inline void *proc_sys_poll_event(struct ctl_table_poll *poll)
  95{
  96        return (void *)(unsigned long)atomic_read(&poll->event);
  97}
  98
  99#define __CTL_TABLE_POLL_INITIALIZER(name) {                            \
 100        .event = ATOMIC_INIT(0),                                        \
 101        .wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.wait) }
 102
 103#define DEFINE_CTL_TABLE_POLL(name)                                     \
 104        struct ctl_table_poll name = __CTL_TABLE_POLL_INITIALIZER(name)
 105
 106/* A sysctl table is an array of struct ctl_table: */
 107struct ctl_table 
 108{
 109        const char *procname;           /* Text ID for /proc/sys, or zero */
 110        void *data;
 111        int maxlen;
 112        umode_t mode;
 113        struct ctl_table *child;        /* Deprecated */
 114        proc_handler *proc_handler;     /* Callback for text formatting */
 115        struct ctl_table_poll *poll;
 116        void *extra1;
 117        void *extra2;
 118};
 119
 120struct ctl_node {
 121        struct rb_node node;
 122        struct ctl_table_header *header;
 123};
 124
 125/* struct ctl_table_header is used to maintain dynamic lists of
 126   struct ctl_table trees. */
 127struct ctl_table_header
 128{
 129        union {
 130                struct {
 131                        struct ctl_table *ctl_table;
 132                        int used;
 133                        int count;
 134                        int nreg;
 135                };
 136                struct rcu_head rcu;
 137        };
 138        struct completion *unregistering;
 139        struct ctl_table *ctl_table_arg;
 140        struct ctl_table_root *root;
 141        struct ctl_table_set *set;
 142        struct ctl_dir *parent;
 143        struct ctl_node *node;
 144};
 145
 146struct ctl_dir {
 147        /* Header must be at the start of ctl_dir */
 148        struct ctl_table_header header;
 149        struct rb_root root;
 150};
 151
 152struct ctl_table_set {
 153        int (*is_seen)(struct ctl_table_set *);
 154        struct ctl_dir dir;
 155};
 156
 157struct ctl_table_root {
 158        struct ctl_table_set default_set;
 159        struct ctl_table_set *(*lookup)(struct ctl_table_root *root,
 160                                           struct nsproxy *namespaces);
 161        int (*permissions)(struct ctl_table_header *head, struct ctl_table *table);
 162};
 163
 164/* struct ctl_path describes where in the hierarchy a table is added */
 165struct ctl_path {
 166        const char *procname;
 167};
 168
 169#ifdef CONFIG_SYSCTL
 170
 171void proc_sys_poll_notify(struct ctl_table_poll *poll);
 172
 173extern void setup_sysctl_set(struct ctl_table_set *p,
 174        struct ctl_table_root *root,
 175        int (*is_seen)(struct ctl_table_set *));
 176extern void retire_sysctl_set(struct ctl_table_set *set);
 177
 178void register_sysctl_root(struct ctl_table_root *root);
 179struct ctl_table_header *__register_sysctl_table(
 180        struct ctl_table_set *set,
 181        const char *path, struct ctl_table *table);
 182struct ctl_table_header *__register_sysctl_paths(
 183        struct ctl_table_set *set,
 184        const struct ctl_path *path, struct ctl_table *table);
 185struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table);
 186struct ctl_table_header *register_sysctl_table(struct ctl_table * table);
 187struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
 188                                                struct ctl_table *table);
 189
 190void unregister_sysctl_table(struct ctl_table_header * table);
 191
 192extern int sysctl_init(void);
 193#else /* CONFIG_SYSCTL */
 194static inline struct ctl_table_header *register_sysctl_table(struct ctl_table * table)
 195{
 196        return NULL;
 197}
 198
 199static inline struct ctl_table_header *register_sysctl_paths(
 200                        const struct ctl_path *path, struct ctl_table *table)
 201{
 202        return NULL;
 203}
 204
 205static inline void unregister_sysctl_table(struct ctl_table_header * table)
 206{
 207}
 208
 209static inline void setup_sysctl_set(struct ctl_table_set *p,
 210        struct ctl_table_root *root,
 211        int (*is_seen)(struct ctl_table_set *))
 212{
 213}
 214
 215#endif /* CONFIG_SYSCTL */
 216
 217#endif /* _LINUX_SYSCTL_H */
 218
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