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 22 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 23 24 #include <linux/init.h> 25 #include <linux/jiffies.h> 26 #include <linux/kernel.h> 27 #include <linux/module.h> 28 #include <linux/moduleparam.h> 29 #include <linux/reboot.h> 30 #include <linux/timer.h> 31 #include <linux/types.h> 32 #include <linux/watchdog.h> 33 34 #define TIMER_MARGIN 60 /* Default is 60 seconds */ 35 static unsigned int soft_margin = TIMER_MARGIN; /* in seconds */ 36 module_param(soft_margin, uint, 0); 37 MODULE_PARM_DESC(soft_margin, 38 "Watchdog soft_margin in seconds. (0 < soft_margin < 65536, default=" 39 __MODULE_STRING(TIMER_MARGIN) ")"); 40 41 static bool nowayout = WATCHDOG_NOWAYOUT; 42 module_param(nowayout, bool, 0); 43 MODULE_PARM_DESC(nowayout, 44 "Watchdog cannot be stopped once started (default=" 45 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 46 47 static int soft_noboot; 48 module_param(soft_noboot, int, 0); 49 MODULE_PARM_DESC(soft_noboot, 50 "Softdog action, set to 1 to ignore reboots, 0 to reboot (default=0)"); 51 52 static int soft_panic; 53 module_param(soft_panic, int, 0); 54 MODULE_PARM_DESC(soft_panic, 55 "Softdog action, set to 1 to panic, 0 to reboot (default=0)"); 56 57 static void softdog_fire(unsigned long data) 58 { 59 module_put(THIS_MODULE); 60 if (soft_noboot) { 61 pr_crit("Triggered - Reboot ignored\n"); 62 } else if (soft_panic) { 63 pr_crit("Initiating panic\n"); 64 panic("Software Watchdog Timer expired"); 65 } else { 66 pr_crit("Initiating system reboot\n"); 67 emergency_restart(); 68 pr_crit("Reboot didn't ?????\n"); 69 } 70 } 71 72 static struct timer_list softdog_ticktock = 73 TIMER_INITIALIZER(softdog_fire, 0, 0); 74 75 static struct watchdog_device softdog_dev; 76 77 static void softdog_pretimeout(unsigned long data) 78 { 79 watchdog_notify_pretimeout(&softdog_dev); 80 } 81 82 static struct timer_list softdog_preticktock = 83 TIMER_INITIALIZER(softdog_pretimeout, 0, 0); 84 85 static int softdog_ping(struct watchdog_device *w) 86 { 87 if (!mod_timer(&softdog_ticktock, jiffies + (w->timeout * HZ))) 88 __module_get(THIS_MODULE); 89 90 if (w->pretimeout) 91 mod_timer(&softdog_preticktock, jiffies + 92 (w->timeout - w->pretimeout) * HZ); 93 else 94 del_timer(&softdog_preticktock); 95 96 return 0; 97 } 98 99 static int softdog_stop(struct watchdog_device *w) 100 { 101 if (del_timer(&softdog_ticktock)) 102 module_put(THIS_MODULE); 103 104 del_timer(&softdog_preticktock); 105 106 return 0; 107 } 108 109 static struct watchdog_info softdog_info = { 110 .identity = "Software Watchdog", 111 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE | 112 WDIOF_PRETIMEOUT, 113 }; 114 115 static const struct watchdog_ops softdog_ops = { 116 .owner = THIS_MODULE, 117 .start = softdog_ping, 118 .stop = softdog_stop, 119 }; 120 121 static struct watchdog_device softdog_dev = { 122 .info = &softdog_info, 123 .ops = &softdog_ops, 124 .min_timeout = 1, 125 .max_timeout = 65535, 126 .timeout = TIMER_MARGIN, 127 }; 128 129 static int __init softdog_init(void) 130 { 131 int ret; 132 133 watchdog_init_timeout(&softdog_dev, soft_margin, NULL); 134 watchdog_set_nowayout(&softdog_dev, nowayout); 135 watchdog_stop_on_reboot(&softdog_dev); 136 137 ret = watchdog_register_device(&softdog_dev); 138 if (ret) 139 return ret; 140 141 pr_info("initialized. soft_noboot=%d soft_margin=%d sec soft_panic=%d (nowayout=%d)\n", 142 soft_noboot, softdog_dev.timeout, soft_panic, nowayout); 143 144 return 0; 145 } 146 module_init(softdog_init); 147 148 static void __exit softdog_exit(void) 149 { 150 watchdog_unregister_device(&softdog_dev); 151 } 152 module_exit(softdog_exit); 153 154 MODULE_AUTHOR("Alan Cox"); 155 MODULE_DESCRIPTION("Software Watchdog Device Driver"); 156 MODULE_LICENSE("GPL"); 157