tjh.dev
Linux kernel mirror (for testing)
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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/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 */
52static unsigned int soft_margin = TIMER_MARGIN; /* in seconds */
53module_param(soft_margin, uint, 0);
54MODULE_PARM_DESC(soft_margin,
55 "Watchdog soft_margin in seconds. (0 < soft_margin < 65536, default="
56 __MODULE_STRING(TIMER_MARGIN) ")");
57
58static bool nowayout = WATCHDOG_NOWAYOUT;
59module_param(nowayout, bool, 0);
60MODULE_PARM_DESC(nowayout,
61 "Watchdog cannot be stopped once started (default="
62 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
63
64static int soft_noboot;
65module_param(soft_noboot, int, 0);
66MODULE_PARM_DESC(soft_noboot,
67 "Softdog action, set to 1 to ignore reboots, 0 to reboot (default=0)");
68
69static int soft_panic;
70module_param(soft_panic, int, 0);
71MODULE_PARM_DESC(soft_panic,
72 "Softdog action, set to 1 to panic, 0 to reboot (default=0)");
73
74/*
75 * Our timer
76 */
77
78static void watchdog_fire(unsigned long);
79
80static struct timer_list watchdog_ticktock =
81 TIMER_INITIALIZER(watchdog_fire, 0, 0);
82
83/*
84 * If the timer expires..
85 */
86
87static 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
106static 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
113static 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
121static 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
131static struct watchdog_info softdog_info = {
132 .identity = "Software Watchdog",
133 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
134};
135
136static 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
143static struct watchdog_device softdog_dev = {
144 .info = &softdog_info,
145 .ops = &softdog_ops,
146 .min_timeout = 1,
147 .max_timeout = 0xFFFF
148};
149
150static 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
176static void __exit watchdog_exit(void)
177{
178 watchdog_unregister_device(&softdog_dev);
179}
180
181module_init(watchdog_init);
182module_exit(watchdog_exit);
183
184MODULE_AUTHOR("Alan Cox");
185MODULE_DESCRIPTION("Software Watchdog Device Driver");
186MODULE_LICENSE("GPL");