linux-old/include/linux/sysrq.h
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   1/* -*- linux-c -*-
   2 *
   3 *      $Id: sysrq.h,v 1.3 1997/07/17 11:54:33 mj Exp $
   4 *
   5 *      Linux Magic System Request Key Hacks
   6 *
   7 *      (c) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
   8 *
   9 *      (c) 2000 Crutcher Dunnavant <crutcher+kernel@datastacks.com>
  10 *      overhauled to use key registration
  11 *      based upon discusions in irc://irc.openprojects.net/#kernelnewbies
  12 */
  13#ifndef __LINUX_SYSRQ_H__
  14#define __LINUX_SYSRQ_H__
  15
  16#include <linux/config.h>
  17
  18struct pt_regs;
  19struct kbd_struct;
  20struct tty_struct;
  21
  22struct sysrq_key_op {
  23        void (*handler)(int, struct pt_regs *,
  24                        struct kbd_struct *, struct tty_struct *);
  25        char *help_msg;
  26        char *action_msg;
  27};
  28
  29#ifdef CONFIG_MAGIC_SYSRQ
  30
  31/* Generic SysRq interface -- you may call it from any device driver, supplying
  32 * ASCII code of the key, pointer to registers and kbd/tty structs (if they
  33 * are available -- else NULL's).
  34 */
  35
  36void handle_sysrq(int, struct pt_regs *,
  37                struct kbd_struct *, struct tty_struct *);
  38
  39
  40/* 
  41 * Nonlocking version of handle sysrq, used by sysrq handlers that need to
  42 * call sysrq handlers
  43 */
  44
  45void __handle_sysrq_nolock(int, struct pt_regs *,
  46                struct kbd_struct *, struct tty_struct *);
  47
  48
  49
  50/*
  51 * Sysrq registration manipulation functions
  52 */
  53
  54void __sysrq_lock_table (void);
  55void __sysrq_unlock_table (void);
  56struct sysrq_key_op *__sysrq_get_key_op (int key);
  57void __sysrq_put_key_op (int key, struct sysrq_key_op *op_p);
  58
  59extern __inline__ int
  60__sysrq_swap_key_ops_nolock(int key, struct sysrq_key_op *insert_op_p,
  61                                struct sysrq_key_op *remove_op_p)
  62{
  63        int retval;
  64        if (__sysrq_get_key_op(key) == remove_op_p) {
  65                __sysrq_put_key_op(key, insert_op_p);
  66                retval = 0;
  67        } else {
  68                retval = -1;
  69        }
  70        return retval;
  71}
  72
  73extern __inline__ int
  74__sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
  75                                struct sysrq_key_op *remove_op_p) {
  76        int retval;
  77        __sysrq_lock_table();
  78        retval = __sysrq_swap_key_ops_nolock(key, insert_op_p, remove_op_p);
  79        __sysrq_unlock_table();
  80        return retval;
  81}
  82        
  83static inline int register_sysrq_key(int key, struct sysrq_key_op *op_p)
  84{
  85        return __sysrq_swap_key_ops(key, op_p, NULL);
  86}
  87
  88static inline int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
  89{
  90        return __sysrq_swap_key_ops(key, NULL, op_p);
  91}
  92
  93#else
  94
  95static inline int __reterr(void)
  96{
  97        return -EINVAL;
  98}
  99
 100#define register_sysrq_key(ig,nore) __reterr()
 101#define unregister_sysrq_key(ig,nore) __reterr()
 102
 103#endif
 104
 105
 106/* Deferred actions */
 107
 108extern volatile int emergency_sync_scheduled;
 109
 110#define EMERG_SYNC 1
 111#define EMERG_REMOUNT 2
 112
 113void do_emergency_sync(void);
 114
 115#ifdef CONFIG_MAGIC_SYSRQ
 116#define CHECK_EMERGENCY_SYNC                    \
 117        if (emergency_sync_scheduled)           \
 118                do_emergency_sync();
 119#else
 120#define CHECK_EMERGENCY_SYNC
 121#endif
 122
 123#endif /* __LINUX_SYSRQ_H__ */
 124
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