/*
   * sysctl.h: General linux system control interface
   *
   * Begun 24 March 1995, Stephen Tweedie
   *
   ****************************************************************
   ****************************************************************
   **

   **  WARNING:

   **  The values in this file are exported to user space via 

   **  the sysctl() binary interface.  Do *NOT* change the
   **  numbering of any existing values here, and do not change
   **  any numbers within any one set of values.  If you have to

   **  redefine an existing interface, use a new number for it.

   **  The kernel will then return -ENOTDIR to any application using
   **  the old binary interface.
   **

   ****************************************************************
   ****************************************************************
   */

  #ifndef _LINUX_SYSCTL_H
  #define _LINUX_SYSCTL_H

  #include <linux/list.h>

  #include <linux/rcupdate.h>

  #include <linux/wait.h>

  #include <linux/rbtree.h>

  #include <uapi/linux/sysctl.h>

  /* For the /proc/sys support */

  struct ctl_table;

  struct nsproxy;

  struct ctl_table_root;

  struct ctl_table_header;

  struct ctl_dir;

  typedef int proc_handler (struct ctl_table *ctl, int write,

  			  void __user *buffer, size_t *lenp, loff_t *ppos);

  extern int proc_dostring(struct ctl_table *, int,

  			 void __user *, size_t *, loff_t *);

  extern int proc_dointvec(struct ctl_table *, int,

  			 void __user *, size_t *, loff_t *);

  extern int proc_dointvec_minmax(struct ctl_table *, int,

  				void __user *, size_t *, loff_t *);

  extern int proc_dointvec_jiffies(struct ctl_table *, int,

  				 void __user *, size_t *, loff_t *);

  extern int proc_dointvec_userhz_jiffies(struct ctl_table *, int,

  					void __user *, size_t *, loff_t *);

  extern int proc_dointvec_ms_jiffies(struct ctl_table *, int,

  				    void __user *, size_t *, loff_t *);

  extern int proc_doulongvec_minmax(struct ctl_table *, int,

  				  void __user *, size_t *, loff_t *);

  extern int proc_doulongvec_ms_jiffies_minmax(struct ctl_table *table, int,

  				      void __user *, size_t *, loff_t *);

  extern int proc_do_large_bitmap(struct ctl_table *, int,
  				void __user *, size_t *, loff_t *);

  /*
   * Register a set of sysctl names by calling register_sysctl_table

   * with an initialised array of struct ctl_table's.  An entry with 
   * NULL procname terminates the table.  table->de will be

   * set up by the registration and need not be initialised in advance.

   *
   * sysctl names can be mirrored automatically under /proc/sys.  The
   * procname supplied controls /proc naming.
   *
   * The table's mode will be honoured both for sys_sysctl(2) and
   * proc-fs access.
   *
   * Leaf nodes in the sysctl tree will be represented by a single file
   * under /proc; non-leaf nodes will be represented by directories.  A
   * null procname disables /proc mirroring at this node.

   *

   * sysctl(2) can automatically manage read and write requests through
   * the sysctl table.  The data and maxlen fields of the ctl_table
   * struct enable minimal validation of the values being written to be
   * performed, and the mode field allows minimal authentication.
   * 

   * There must be a proc_handler routine for any terminal nodes
   * mirrored under /proc/sys (non-terminals are handled by a built-in
   * directory handler).  Several default handlers are available to
   * cover common cases.
   */

  /* Support for userspace poll() to watch for changes */
  struct ctl_table_poll {
  	atomic_t event;
  	wait_queue_head_t wait;
  };
  
  static inline void *proc_sys_poll_event(struct ctl_table_poll *poll)
  {
  	return (void *)(unsigned long)atomic_read(&poll->event);
  }

  #define __CTL_TABLE_POLL_INITIALIZER(name) {				\
  	.event = ATOMIC_INIT(0),					\
  	.wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.wait) }
  
  #define DEFINE_CTL_TABLE_POLL(name)					\
  	struct ctl_table_poll name = __CTL_TABLE_POLL_INITIALIZER(name)

  /* A sysctl table is an array of struct ctl_table: */
  struct ctl_table 
  {

  	const char *procname;		/* Text ID for /proc/sys, or zero */
  	void *data;
  	int maxlen;

  	umode_t mode;

  	struct ctl_table *child;	/* Deprecated */

  	proc_handler *proc_handler;	/* Callback for text formatting */

  	struct ctl_table_poll *poll;

  	void *extra1;
  	void *extra2;
  };

  struct ctl_node {
  	struct rb_node node;
  	struct ctl_table_header *header;
  };

  /* struct ctl_table_header is used to maintain dynamic lists of

     struct ctl_table trees. */

  struct ctl_table_header
  {

  	union {
  		struct {
  			struct ctl_table *ctl_table;

  			int used;
  			int count;

  			int nreg;

  		};
  		struct rcu_head rcu;
  	};

  	struct completion *unregistering;

  	struct ctl_table *ctl_table_arg;

  	struct ctl_table_root *root;

  	struct ctl_table_set *set;

  	struct ctl_dir *parent;

  	struct ctl_node *node;

  };
  
  struct ctl_dir {
  	/* Header must be at the start of ctl_dir */
  	struct ctl_table_header header;

  	struct rb_root root;

  };

  struct ctl_table_set {

  	int (*is_seen)(struct ctl_table_set *);

  	struct ctl_dir dir;

  };
  
  struct ctl_table_root {

  	struct ctl_table_set default_set;
  	struct ctl_table_set *(*lookup)(struct ctl_table_root *root,
  					   struct nsproxy *namespaces);

  	int (*permissions)(struct ctl_table_header *head, struct ctl_table *table);

  };

  /* struct ctl_path describes where in the hierarchy a table is added */
  struct ctl_path {
  	const char *procname;

  };

  #ifdef CONFIG_SYSCTL
  
  void proc_sys_poll_notify(struct ctl_table_poll *poll);
  
  extern void setup_sysctl_set(struct ctl_table_set *p,

  	struct ctl_table_root *root,

  	int (*is_seen)(struct ctl_table_set *));

  extern void retire_sysctl_set(struct ctl_table_set *set);

  void register_sysctl_root(struct ctl_table_root *root);

  struct ctl_table_header *__register_sysctl_table(

  	struct ctl_table_set *set,

  	const char *path, struct ctl_table *table);

  struct ctl_table_header *__register_sysctl_paths(

  	struct ctl_table_set *set,

  	const struct ctl_path *path, struct ctl_table *table);

  struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table);

  struct ctl_table_header *register_sysctl_table(struct ctl_table * table);

  struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
  						struct ctl_table *table);

  void unregister_sysctl_table(struct ctl_table_header * table);

  extern int sysctl_init(void);

  
  extern struct ctl_table sysctl_mount_point[];

  #else /* CONFIG_SYSCTL */
  static inline struct ctl_table_header *register_sysctl_table(struct ctl_table * table)
  {
  	return NULL;
  }
  
  static inline struct ctl_table_header *register_sysctl_paths(
  			const struct ctl_path *path, struct ctl_table *table)
  {
  	return NULL;
  }
  
  static inline void unregister_sysctl_table(struct ctl_table_header * table)
  {
  }
  
  static inline void setup_sysctl_set(struct ctl_table_set *p,

  	struct ctl_table_root *root,

  	int (*is_seen)(struct ctl_table_set *))
  {
  }

  #endif /* CONFIG_SYSCTL */

  int sysctl_max_threads(struct ctl_table *table, int write,
  		       void __user *buffer, size_t *lenp, loff_t *ppos);

  #endif /* _LINUX_SYSCTL_H */