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/reboot.h>
  47 #include <linux/init.h>
  48 #include <linux/jiffies.h>
  49 #include <linux/kernel.h>
  50
  51 #define TIMER_MARGIN    60              /* Default is 60 seconds */
  52 static unsigned int soft_margin = TIMER_MARGIN; /* in seconds */
  53 module_param(soft_margin, uint, 0);
  54 MODULE_PARM_DESC(soft_margin,
  55         "Watchdog soft_margin in seconds. (0 < soft_margin < 65536, default="
  56                                         __MODULE_STRING(TIMER_MARGIN) ")");
  57
  58 static bool nowayout = WATCHDOG_NOWAYOUT;
  59 module_param(nowayout, bool, 0);
  60 MODULE_PARM_DESC(nowayout,
  61                 "Watchdog cannot be stopped once started (default="
  62                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  63
  64 static int soft_noboot;
  65 module_param(soft_noboot, int, 0);
  66 MODULE_PARM_DESC(soft_noboot,
  67         "Softdog action, set to 1 to ignore reboots, 0 to reboot (default=0)");
  68
  69 static int soft_panic;
  70 module_param(soft_panic, int, 0);
  71 MODULE_PARM_DESC(soft_panic,
  72         "Softdog action, set to 1 to panic, 0 to reboot (default=0)");
  73
  74 /*
  75  *      Our timer
  76  */
  77
  78 static void watchdog_fire(unsigned long);
  79
  80 static struct timer_list watchdog_ticktock =
  81                 TIMER_INITIALIZER(watchdog_fire, 0, 0);
  82
  83 /*
  84  *      If the timer expires..
  85  */
  86
  87 static void watchdog_fire(unsigned long data)
  88 {
  89         module_put(THIS_MODULE);
  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         if (!mod_timer(&watchdog_ticktock, jiffies+(w->timeout*HZ)))
 109                 __module_get(THIS_MODULE);
 110         return 0;
 111 }
 112
 113 static int softdog_stop(struct watchdog_device *w)
 114 {
 115         if (del_timer(&watchdog_ticktock))
 116                 module_put(THIS_MODULE);
 117
 118         return 0;
 119 }
 120
 121 static int softdog_set_timeout(struct watchdog_device *w, unsigned int t)
 122 {
 123         w->timeout = t;
 124         return 0;
 125 }
 126
 127 /*
 128  *      Kernel Interfaces
 129  */
 130
 131 static struct watchdog_info softdog_info = {
 132         .identity = "Software Watchdog",
 133         .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 134 };
 135
 136 static struct watchdog_ops softdog_ops = {
 137         .owner = THIS_MODULE,
 138         .start = softdog_ping,
 139         .stop = softdog_stop,
 140         .set_timeout = softdog_set_timeout,
 141 };
 142
 143 static struct watchdog_device softdog_dev = {
 144         .info = &softdog_info,
 145         .ops = &softdog_ops,
 146         .min_timeout = 1,
 147         .max_timeout = 0xFFFF
 148 };
 149
 150 static int __init watchdog_init(void)
 151 {
 152         int ret;
 153
 154         /* Check that the soft_margin value is within it's range;
 155            if not reset to the default */
 156         if (soft_margin < 1 || soft_margin > 65535) {
 157                 pr_info("soft_margin must be 0 < soft_margin < 65536, using %d\n",
 158                         TIMER_MARGIN);
 159                 return -EINVAL;
 160         }
 161         softdog_dev.timeout = soft_margin;
 162
 163         watchdog_set_nowayout(&softdog_dev, nowayout);
 164         watchdog_stop_on_reboot(&softdog_dev);
 165
 166         ret = watchdog_register_device(&softdog_dev);
 167         if (ret)
 168                 return ret;
 169
 170         pr_info("Software Watchdog Timer: 0.08 initialized. soft_noboot=%d soft_margin=%d sec soft_panic=%d (nowayout=%d)\n",
 171                 soft_noboot, soft_margin, soft_panic, nowayout);
 172
 173         return 0;
 174 }
 175
 176 static void __exit watchdog_exit(void)
 177 {
 178         watchdog_unregister_device(&softdog_dev);
 179 }
 180
 181 module_init(watchdog_init);
 182 module_exit(watchdog_exit);
 183
 184 MODULE_AUTHOR("Alan Cox");
 185 MODULE_DESCRIPTION("Software Watchdog Device Driver");
 186 MODULE_LICENSE("GPL");