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"); 187