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 .set_timeout = softdog_set_timeout, 156 }; 157 158 static struct watchdog_device softdog_dev = { 159 .info = &softdog_info, 160 .ops = &softdog_ops, 161 .min_timeout = 1, 162 .max_timeout = 0xFFFF 163 }; 164 165 static int __init watchdog_init(void) 166 { 167 int ret; 168 169 /* Check that the soft_margin value is within it's range; 170 if not reset to the default */ 171 if (soft_margin < 1 || soft_margin > 65535) { 172 pr_info("soft_margin must be 0 < soft_margin < 65536, using %d\n", 173 TIMER_MARGIN); 174 return -EINVAL; 175 } 176 softdog_dev.timeout = soft_margin; 177 178 watchdog_set_nowayout(&softdog_dev, nowayout); 179 180 ret = register_reboot_notifier(&softdog_notifier); 181 if (ret) { 182 pr_err("cannot register reboot notifier (err=%d)\n", ret); 183 return ret; 184 } 185 186 ret = watchdog_register_device(&softdog_dev); 187 if (ret) { 188 unregister_reboot_notifier(&softdog_notifier); 189 return ret; 190 } 191 192 pr_info("Software Watchdog Timer: 0.08 initialized. soft_noboot=%d soft_margin=%d sec soft_panic=%d (nowayout=%d)\n", 193 soft_noboot, soft_margin, soft_panic, nowayout); 194 195 return 0; 196 } 197 198 static void __exit watchdog_exit(void) 199 { 200 watchdog_unregister_device(&softdog_dev); 201 unregister_reboot_notifier(&softdog_notifier); 202 } 203 204 module_init(watchdog_init); 205 module_exit(watchdog_exit); 206 207 MODULE_AUTHOR("Alan Cox"); 208 MODULE_DESCRIPTION("Software Watchdog Device Driver"); 209 MODULE_LICENSE("GPL"); 210