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/hrtimer.h> 25 #include <linux/init.h> 26 #include <linux/kernel.h> 27 #include <linux/module.h> 28 #include <linux/moduleparam.h> 29 #include <linux/reboot.h> 30 #include <linux/types.h> 31 #include <linux/watchdog.h> 32 33 #define TIMER_MARGIN 60 /* Default is 60 seconds */ 34 static unsigned int soft_margin = TIMER_MARGIN; /* in seconds */ 35 module_param(soft_margin, uint, 0); 36 MODULE_PARM_DESC(soft_margin, 37 "Watchdog soft_margin in seconds. (0 < soft_margin < 65536, default=" 38 __MODULE_STRING(TIMER_MARGIN) ")"); 39 40 static bool nowayout = WATCHDOG_NOWAYOUT; 41 module_param(nowayout, bool, 0); 42 MODULE_PARM_DESC(nowayout, 43 "Watchdog cannot be stopped once started (default=" 44 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 45 46 static int soft_noboot; 47 module_param(soft_noboot, int, 0); 48 MODULE_PARM_DESC(soft_noboot, 49 "Softdog action, set to 1 to ignore reboots, 0 to reboot (default=0)"); 50 51 static int soft_panic; 52 module_param(soft_panic, int, 0); 53 MODULE_PARM_DESC(soft_panic, 54 "Softdog action, set to 1 to panic, 0 to reboot (default=0)"); 55 56 static struct hrtimer softdog_ticktock; 57 static struct hrtimer softdog_preticktock; 58 59 static enum hrtimer_restart softdog_fire(struct hrtimer *timer) 60 { 61 module_put(THIS_MODULE); 62 if (soft_noboot) { 63 pr_crit("Triggered - Reboot ignored\n"); 64 } else if (soft_panic) { 65 pr_crit("Initiating panic\n"); 66 panic("Software Watchdog Timer expired"); 67 } else { 68 pr_crit("Initiating system reboot\n"); 69 emergency_restart(); 70 pr_crit("Reboot didn't ?????\n"); 71 } 72 73 return HRTIMER_NORESTART; 74 } 75 76 static struct watchdog_device softdog_dev; 77 78 static enum hrtimer_restart softdog_pretimeout(struct hrtimer *timer) 79 { 80 watchdog_notify_pretimeout(&softdog_dev); 81 82 return HRTIMER_NORESTART; 83 } 84 85 static int softdog_ping(struct watchdog_device *w) 86 { 87 if (!hrtimer_active(&softdog_ticktock)) 88 __module_get(THIS_MODULE); 89 hrtimer_start(&softdog_ticktock, ktime_set(w->timeout, 0), 90 HRTIMER_MODE_REL); 91 92 if (IS_ENABLED(CONFIG_SOFT_WATCHDOG_PRETIMEOUT)) { 93 if (w->pretimeout) 94 hrtimer_start(&softdog_preticktock, 95 ktime_set(w->timeout - w->pretimeout, 0), 96 HRTIMER_MODE_REL); 97 else 98 hrtimer_cancel(&softdog_preticktock); 99 } 100 101 return 0; 102 } 103 104 static int softdog_stop(struct watchdog_device *w) 105 { 106 if (hrtimer_cancel(&softdog_ticktock)) 107 module_put(THIS_MODULE); 108 109 if (IS_ENABLED(CONFIG_SOFT_WATCHDOG_PRETIMEOUT)) 110 hrtimer_cancel(&softdog_preticktock); 111 112 return 0; 113 } 114 115 static struct watchdog_info softdog_info = { 116 .identity = "Software Watchdog", 117 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE, 118 }; 119 120 static const struct watchdog_ops softdog_ops = { 121 .owner = THIS_MODULE, 122 .start = softdog_ping, 123 .stop = softdog_stop, 124 }; 125 126 static struct watchdog_device softdog_dev = { 127 .info = &softdog_info, 128 .ops = &softdog_ops, 129 .min_timeout = 1, 130 .max_timeout = 65535, 131 .timeout = TIMER_MARGIN, 132 }; 133 134 static int __init softdog_init(void) 135 { 136 int ret; 137 138 watchdog_init_timeout(&softdog_dev, soft_margin, NULL); 139 watchdog_set_nowayout(&softdog_dev, nowayout); 140 watchdog_stop_on_reboot(&softdog_dev); 141 142 hrtimer_init(&softdog_ticktock, CLOCK_MONOTONIC, HRTIMER_MODE_REL); 143 softdog_ticktock.function = softdog_fire; 144 145 if (IS_ENABLED(CONFIG_SOFT_WATCHDOG_PRETIMEOUT)) { 146 softdog_info.options |= WDIOF_PRETIMEOUT; 147 hrtimer_init(&softdog_preticktock, CLOCK_MONOTONIC, 148 HRTIMER_MODE_REL); 149 softdog_preticktock.function = softdog_pretimeout; 150 } 151 152 ret = watchdog_register_device(&softdog_dev); 153 if (ret) 154 return ret; 155 156 pr_info("initialized. soft_noboot=%d soft_margin=%d sec soft_panic=%d (nowayout=%d)\n", 157 soft_noboot, softdog_dev.timeout, soft_panic, nowayout); 158 159 return 0; 160 } 161 module_init(softdog_init); 162 163 static void __exit softdog_exit(void) 164 { 165 watchdog_unregister_device(&softdog_dev); 166 } 167 module_exit(softdog_exit); 168 169 MODULE_AUTHOR("Alan Cox"); 170 MODULE_DESCRIPTION("Software Watchdog Device Driver"); 171 MODULE_LICENSE("GPL"); 172