tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
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
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 */
34static unsigned int soft_margin = TIMER_MARGIN; /* in seconds */
35module_param(soft_margin, uint, 0);
36MODULE_PARM_DESC(soft_margin,
37 "Watchdog soft_margin in seconds. (0 < soft_margin < 65536, default="
38 __MODULE_STRING(TIMER_MARGIN) ")");
39
40static bool nowayout = WATCHDOG_NOWAYOUT;
41module_param(nowayout, bool, 0);
42MODULE_PARM_DESC(nowayout,
43 "Watchdog cannot be stopped once started (default="
44 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
45
46static int soft_noboot;
47module_param(soft_noboot, int, 0);
48MODULE_PARM_DESC(soft_noboot,
49 "Softdog action, set to 1 to ignore reboots, 0 to reboot (default=0)");
50
51static int soft_panic;
52module_param(soft_panic, int, 0);
53MODULE_PARM_DESC(soft_panic,
54 "Softdog action, set to 1 to panic, 0 to reboot (default=0)");
55
56static struct hrtimer softdog_ticktock;
57static struct hrtimer softdog_preticktock;
58
59static 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
76static struct watchdog_device softdog_dev;
77
78static enum hrtimer_restart softdog_pretimeout(struct hrtimer *timer)
79{
80 watchdog_notify_pretimeout(&softdog_dev);
81
82 return HRTIMER_NORESTART;
83}
84
85static 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
104static 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
115static struct watchdog_info softdog_info = {
116 .identity = "Software Watchdog",
117 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
118};
119
120static const struct watchdog_ops softdog_ops = {
121 .owner = THIS_MODULE,
122 .start = softdog_ping,
123 .stop = softdog_stop,
124};
125
126static 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
134static 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}
161module_init(softdog_init);
162
163static void __exit softdog_exit(void)
164{
165 watchdog_unregister_device(&softdog_dev);
166}
167module_exit(softdog_exit);
168
169MODULE_AUTHOR("Alan Cox");
170MODULE_DESCRIPTION("Software Watchdog Device Driver");
171MODULE_LICENSE("GPL");