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/watchdog.h>
  46 #include <linux/notifier.h>
  47 #include <linux/reboot.h>
  48 #include <linux/init.h>
  49 #include <linux/jiffies.h>
  50 #include <linux/kernel.h>
  51
  52 #define TIMER_MARGIN    60              /* Default is 60 seconds */
  53 static unsigned int soft_margin = TIMER_MARGIN; /* in seconds */
  54 module_param(soft_margin, uint, 0);
  55 MODULE_PARM_DESC(soft_margin,
  56         "Watchdog soft_margin in seconds. (0 < soft_margin < 65536, default="
  57                                         __MODULE_STRING(TIMER_MARGIN) ")");
  58
  59 static bool nowayout = WATCHDOG_NOWAYOUT;
  60 module_param(nowayout, bool, 0);
  61 MODULE_PARM_DESC(nowayout,
  62                 "Watchdog cannot be stopped once started (default="
  63                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  64
  65 static int soft_noboot;
  66 module_param(soft_noboot, int, 0);
  67 MODULE_PARM_DESC(soft_noboot,
  68         "Softdog action, set to 1 to ignore reboots, 0 to reboot (default=0)");
  69
  70 static int soft_panic;
  71 module_param(soft_panic, int, 0);
  72 MODULE_PARM_DESC(soft_panic,
  73         "Softdog action, set to 1 to panic, 0 to reboot (default=0)");
  74
  75 /*
  76  *      Our timer
  77  */
  78
  79 static void watchdog_fire(unsigned long);
  80
  81 static struct timer_list watchdog_ticktock =
  82                 TIMER_INITIALIZER(watchdog_fire, 0, 0);
  83
  84 /*
  85  *      If the timer expires..
  86  */
  87
  88 static void watchdog_fire(unsigned long data)
  89 {
  90         if (soft_noboot)
  91                 pr_crit("Triggered - Reboot ignored\n");
  92         else if (soft_panic) {
  93                 pr_crit("Initiating panic\n");
  94                 panic("Software Watchdog Timer expired");
  95         } else {
  96                 pr_crit("Initiating system reboot\n");
  97                 emergency_restart();
  98                 pr_crit("Reboot didn't ?????\n");
  99         }
 100 }
 101
 102 /*
 103  *      Softdog operations
 104  */
 105
 106 static int softdog_ping(struct watchdog_device *w)
 107 {
 108         mod_timer(&watchdog_ticktock, jiffies+(w->timeout*HZ));
 109         return 0;
 110 }
 111
 112 static int softdog_stop(struct watchdog_device *w)
 113 {
 114         del_timer(&watchdog_ticktock);
 115         return 0;
 116 }
 117
 118 static int softdog_set_timeout(struct watchdog_device *w, unsigned int t)
 119 {
 120         w->timeout = t;
 121         return 0;
 122 }
 123
 124 /*
 125  *      Notifier for system down
 126  */
 127
 128 static int softdog_notify_sys(struct notifier_block *this, unsigned long code,
 129         void *unused)
 130 {
 131         if (code == SYS_DOWN || code == SYS_HALT)
 132                 /* Turn the WDT off */
 133                 softdog_stop(NULL);
 134         return NOTIFY_DONE;
 135 }
 136
 137 /*
 138  *      Kernel Interfaces
 139  */
 140
 141 static struct notifier_block softdog_notifier = {
 142         .notifier_call  = softdog_notify_sys,
 143 };
 144
 145 static struct watchdog_info softdog_info = {
 146         .identity = "Software Watchdog",
 147         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 148 };
 149
 150 static struct watchdog_ops softdog_ops = {
 151         .owner = THIS_MODULE,
 152         .start = softdog_ping,
 153         .stop = softdog_stop,
 154         .set_timeout = softdog_set_timeout,
 155 };
 156
 157 static struct watchdog_device softdog_dev = {
 158         .info = &softdog_info,
 159         .ops = &softdog_ops,
 160         .min_timeout = 1,
 161         .max_timeout = 0xFFFF
 162 };
 163
 164 static int __init watchdog_init(void)
 165 {
 166         int ret;
 167
 168         /* Check that the soft_margin value is within it's range;
 169            if not reset to the default */
 170         if (soft_margin < 1 || soft_margin > 65535) {
 171                 pr_info("soft_margin must be 0 < soft_margin < 65536, using %d\n",
 172                         TIMER_MARGIN);
 173                 return -EINVAL;
 174         }
 175         softdog_dev.timeout = soft_margin;
 176
 177         watchdog_set_nowayout(&softdog_dev, nowayout);
 178
 179         ret = register_reboot_notifier(&softdog_notifier);
 180         if (ret) {
 181                 pr_err("cannot register reboot notifier (err=%d)\n", ret);
 182                 return ret;
 183         }
 184
 185         ret = watchdog_register_device(&softdog_dev);
 186         if (ret) {
 187                 unregister_reboot_notifier(&softdog_notifier);
 188                 return ret;
 189         }
 190
 191         pr_info("Software Watchdog Timer: 0.08 initialized. soft_noboot=%d soft_margin=%d sec soft_panic=%d (nowayout=%d)\n",
 192                 soft_noboot, soft_margin, soft_panic, nowayout);
 193
 194         return 0;
 195 }
 196
 197 static void __exit watchdog_exit(void)
 198 {
 199         watchdog_unregister_device(&softdog_dev);
 200         unregister_reboot_notifier(&softdog_notifier);
 201 }
 202
 203 module_init(watchdog_init);
 204 module_exit(watchdog_exit);
 205
 206 MODULE_AUTHOR("Alan Cox");
 207 MODULE_DESCRIPTION("Software Watchdog Device Driver");
 208 MODULE_LICENSE("GPL");