drivers/watchdog/softdog.c

   1 /*
   2  *      SoftDog:        A Software Watchdog Device
   3  *
   4  *      (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
   5  *                                                      All Rights Reserved.
   6  *
   7  *      This program is free software; you can redistribute it and/or
   8  *      modify it under the terms of the GNU General Public License
   9  *      as published by the Free Software Foundation; either version
  10  *      2 of the License, or (at your option) any later version.
  11  *
  12  *      Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
  13  *      warranty for any of this software. This material is provided
  14  *      "AS-IS" and at no charge.
  15  *
  16  *      (c) Copyright 1995    Alan Cox <alan@lxorguk.ukuu.org.uk>
  17  *
  18  *      Software only watchdog driver. Unlike its big brother the WDT501P
  19  *      driver this won't always recover a failed machine.
  20  *
  21  *  03/96: Angelo Haritsis <ah@doc.ic.ac.uk> :
  22  *      Modularised.
  23  *      Added soft_margin; use upon insmod to change the timer delay.
  24  *      NB: uses same minor as wdt (WATCHDOG_MINOR); we could use separate
  25  *          minors.
  26  *
  27  *  19980911 Alan Cox
  28  *      Made SMP safe for 2.3.x
  29  *
  30  *  20011127 Joel Becker (jlbec@evilplan.org>
  31  *      Added soft_noboot; Allows testing the softdog trigger without
  32  *      requiring a recompile.
  33  *      Added WDIOC_GETTIMEOUT and WDIOC_SETTIMOUT.
  34  *
  35  *  20020530 Joel Becker <joel.becker@oracle.com>
  36  *      Added Matt Domsch's nowayout module option.
  37  */
  38
  39 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  40
  41 #include <linux/module.h>
  42 #include <linux/moduleparam.h>
  43 #include <linux/types.h>
  44 #include <linux/timer.h>
  45 #include <linux/miscdevice.h>
  46 #include <linux/watchdog.h>
  47 #include <linux/notifier.h>
  48 #include <linux/reboot.h>
  49 #include <linux/init.h>
  50 #include <linux/jiffies.h>
  51 #include <linux/kernel.h>
  52
  53 #define TIMER_MARGIN    60              /* Default is 60 seconds */
  54 static unsigned int soft_margin = TIMER_MARGIN; /* in seconds */
  55 module_param(soft_margin, uint, 0);
  56 MODULE_PARM_DESC(soft_margin,
  57         "Watchdog soft_margin in seconds. (0 < soft_margin < 65536, default="
  58                                         __MODULE_STRING(TIMER_MARGIN) ")");
  59
  60 static bool nowayout = WATCHDOG_NOWAYOUT;
  61 module_param(nowayout, bool, 0);
  62 MODULE_PARM_DESC(nowayout,
  63                 "Watchdog cannot be stopped once started (default="
  64                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  65
  66 static int soft_noboot = 0;
  67 module_param(soft_noboot, int, 0);
  68 MODULE_PARM_DESC(soft_noboot,
  69         "Softdog action, set to 1 to ignore reboots, 0 to reboot (default=0)");
  70
  71 static int soft_panic;
  72 module_param(soft_panic, int, 0);
  73 MODULE_PARM_DESC(soft_panic,
  74         "Softdog action, set to 1 to panic, 0 to reboot (default=0)");
  75
  76 /*
  77  *      Our timer
  78  */
  79
  80 static void watchdog_fire(unsigned long);
  81
  82 static struct timer_list watchdog_ticktock =
  83                 TIMER_INITIALIZER(watchdog_fire, 0, 0);
  84
  85 /*
  86  *      If the timer expires..
  87  */
  88
  89 static void watchdog_fire(unsigned long data)
  90 {
  91         if (soft_noboot)
  92                 pr_crit("Triggered - Reboot ignored\n");
  93         else if (soft_panic) {
  94                 pr_crit("Initiating panic\n");
  95                 panic("Software Watchdog Timer expired");
  96         } else {
  97                 pr_crit("Initiating system reboot\n");
  98                 emergency_restart();
  99                 pr_crit("Reboot didn't ?????\n");
 100         }
 101 }
 102
 103 /*
 104  *      Softdog operations
 105  */
 106
 107 static int softdog_ping(struct watchdog_device *w)
 108 {
 109         mod_timer(&watchdog_ticktock, jiffies+(w->timeout*HZ));
 110         return 0;
 111 }
 112
 113 static int softdog_stop(struct watchdog_device *w)
 114 {
 115         del_timer(&watchdog_ticktock);
 116         return 0;
 117 }
 118
 119 static int softdog_set_timeout(struct watchdog_device *w, unsigned int t)
 120 {
 121         w->timeout = t;
 122         return 0;
 123 }
 124
 125 /*
 126  *      Notifier for system down
 127  */
 128
 129 static int softdog_notify_sys(struct notifier_block *this, unsigned long code,
 130         void *unused)
 131 {
 132         if (code == SYS_DOWN || code == SYS_HALT)
 133                 /* Turn the WDT off */
 134                 softdog_stop(NULL);
 135         return NOTIFY_DONE;
 136 }
 137
 138 /*
 139  *      Kernel Interfaces
 140  */
 141
 142 static struct notifier_block softdog_notifier = {
 143         .notifier_call  = softdog_notify_sys,
 144 };
 145
 146 static struct watchdog_info softdog_info = {
 147         .identity = "Software Watchdog",
 148         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 149 };
 150
 151 static struct watchdog_ops softdog_ops = {
 152         .owner = THIS_MODULE,
 153         .start = softdog_ping,
 154         .stop = softdog_stop,
 155         .ping = softdog_ping,
 156         .set_timeout = softdog_set_timeout,
 157 };
 158
 159 static struct watchdog_device softdog_dev = {
 160         .info = &softdog_info,
 161         .ops = &softdog_ops,
 162         .min_timeout = 1,
 163         .max_timeout = 0xFFFF
 164 };
 165
 166 static int __init watchdog_init(void)
 167 {
 168         int ret;
 169
 170         /* Check that the soft_margin value is within it's range;
 171            if not reset to the default */
 172         if (soft_margin < 1 || soft_margin > 65535) {
 173                 pr_info("soft_margin must be 0 < soft_margin < 65536, using %d\n",
 174                         TIMER_MARGIN);
 175                 return -EINVAL;
 176         }
 177         softdog_dev.timeout = soft_margin;
 178
 179         watchdog_set_nowayout(&softdog_dev, nowayout);
 180
 181         ret = register_reboot_notifier(&softdog_notifier);
 182         if (ret) {
 183                 pr_err("cannot register reboot notifier (err=%d)\n", ret);
 184                 return ret;
 185         }
 186
 187         ret = watchdog_register_device(&softdog_dev);
 188         if (ret) {
 189                 unregister_reboot_notifier(&softdog_notifier);
 190                 return ret;
 191         }
 192
 193         pr_info("Software Watchdog Timer: 0.08 initialized. soft_noboot=%d soft_margin=%d sec soft_panic=%d (nowayout=%d)\n",
 194                 soft_noboot, soft_margin, soft_panic, nowayout);
 195
 196         return 0;
 197 }
 198
 199 static void __exit watchdog_exit(void)
 200 {
 201         watchdog_unregister_device(&softdog_dev);
 202         unregister_reboot_notifier(&softdog_notifier);
 203 }
 204
 205 module_init(watchdog_init);
 206 module_exit(watchdog_exit);
 207
 208 MODULE_AUTHOR("Alan Cox");
 209 MODULE_DESCRIPTION("Software Watchdog Device Driver");
 210 MODULE_LICENSE("GPL");
 211 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);