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 = 0; 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"); 209