tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
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 */
54static unsigned int soft_margin = TIMER_MARGIN; /* in seconds */
55module_param(soft_margin, uint, 0);
56MODULE_PARM_DESC(soft_margin,
57 "Watchdog soft_margin in seconds. (0 < soft_margin < 65536, default="
58 __MODULE_STRING(TIMER_MARGIN) ")");
59
60static bool nowayout = WATCHDOG_NOWAYOUT;
61module_param(nowayout, bool, 0);
62MODULE_PARM_DESC(nowayout,
63 "Watchdog cannot be stopped once started (default="
64 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
65
66static int soft_noboot = 0;
67module_param(soft_noboot, int, 0);
68MODULE_PARM_DESC(soft_noboot,
69 "Softdog action, set to 1 to ignore reboots, 0 to reboot (default=0)");
70
71static int soft_panic;
72module_param(soft_panic, int, 0);
73MODULE_PARM_DESC(soft_panic,
74 "Softdog action, set to 1 to panic, 0 to reboot (default=0)");
75
76/*
77 * Our timer
78 */
79
80static void watchdog_fire(unsigned long);
81
82static struct timer_list watchdog_ticktock =
83 TIMER_INITIALIZER(watchdog_fire, 0, 0);
84
85/*
86 * If the timer expires..
87 */
88
89static 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
107static int softdog_ping(struct watchdog_device *w)
108{
109 mod_timer(&watchdog_ticktock, jiffies+(w->timeout*HZ));
110 return 0;
111}
112
113static int softdog_stop(struct watchdog_device *w)
114{
115 del_timer(&watchdog_ticktock);
116 return 0;
117}
118
119static 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
129static 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
142static struct notifier_block softdog_notifier = {
143 .notifier_call = softdog_notify_sys,
144};
145
146static struct watchdog_info softdog_info = {
147 .identity = "Software Watchdog",
148 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
149};
150
151static struct watchdog_ops softdog_ops = {
152 .owner = THIS_MODULE,
153 .start = softdog_ping,
154 .stop = softdog_stop,
155 .ping = softdog_ping,
156 .set_timeout = softdog_set_timeout,
157};
158
159static struct watchdog_device softdog_dev = {
160 .info = &softdog_info,
161 .ops = &softdog_ops,
162 .min_timeout = 1,
163 .max_timeout = 0xFFFF
164};
165
166static int __init watchdog_init(void)
167{
168 int ret;
169
170 /* Check that the soft_margin value is within it's range;
171 if not reset to the default */
172 if (soft_margin < 1 || soft_margin > 65535) {
173 pr_info("soft_margin must be 0 < soft_margin < 65536, using %d\n",
174 TIMER_MARGIN);
175 return -EINVAL;
176 }
177 softdog_dev.timeout = soft_margin;
178
179 watchdog_set_nowayout(&softdog_dev, nowayout);
180
181 ret = register_reboot_notifier(&softdog_notifier);
182 if (ret) {
183 pr_err("cannot register reboot notifier (err=%d)\n", ret);
184 return ret;
185 }
186
187 ret = watchdog_register_device(&softdog_dev);
188 if (ret) {
189 unregister_reboot_notifier(&softdog_notifier);
190 return ret;
191 }
192
193 pr_info("Software Watchdog Timer: 0.08 initialized. soft_noboot=%d soft_margin=%d sec soft_panic=%d (nowayout=%d)\n",
194 soft_noboot, soft_margin, soft_panic, nowayout);
195
196 return 0;
197}
198
199static void __exit watchdog_exit(void)
200{
201 watchdog_unregister_device(&softdog_dev);
202 unregister_reboot_notifier(&softdog_notifier);
203}
204
205module_init(watchdog_init);
206module_exit(watchdog_exit);
207
208MODULE_AUTHOR("Alan Cox");
209MODULE_DESCRIPTION("Software Watchdog Device Driver");
210MODULE_LICENSE("GPL");
211MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);