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d0173278 | 1 | // SPDX-License-Identifier: GPL-2.0+ |
1da177e4 | 2 | /* |
a5132caf | 3 | * SoftDog: A Software Watchdog Device |
1da177e4 | 4 | * |
143a2e54 WVS |
5 | * (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>, |
6 | * All Rights Reserved. | |
1da177e4 | 7 | * |
1da177e4 LT |
8 | * Neither Alan Cox nor CymruNet Ltd. admit liability nor provide |
9 | * warranty for any of this software. This material is provided | |
10 | * "AS-IS" and at no charge. | |
11 | * | |
12 | * (c) Copyright 1995 Alan Cox <alan@lxorguk.ukuu.org.uk> | |
13 | * | |
14 | * Software only watchdog driver. Unlike its big brother the WDT501P | |
15 | * driver this won't always recover a failed machine. | |
1da177e4 LT |
16 | */ |
17 | ||
27c766aa JP |
18 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
19 | ||
8d5755b3 | 20 | #include <linux/hrtimer.h> |
e65c5825 | 21 | #include <linux/init.h> |
e65c5825 | 22 | #include <linux/kernel.h> |
36a8947c | 23 | #include <linux/kthread.h> |
1da177e4 LT |
24 | #include <linux/module.h> |
25 | #include <linux/moduleparam.h> | |
e65c5825 | 26 | #include <linux/reboot.h> |
e65c5825 | 27 | #include <linux/types.h> |
1da177e4 | 28 | #include <linux/watchdog.h> |
36a8947c | 29 | #include <linux/workqueue.h> |
1da177e4 | 30 | |
1da177e4 | 31 | #define TIMER_MARGIN 60 /* Default is 60 seconds */ |
a5132caf AC |
32 | static unsigned int soft_margin = TIMER_MARGIN; /* in seconds */ |
33 | module_param(soft_margin, uint, 0); | |
f92d3749 AC |
34 | MODULE_PARM_DESC(soft_margin, |
35 | "Watchdog soft_margin in seconds. (0 < soft_margin < 65536, default=" | |
36 | __MODULE_STRING(TIMER_MARGIN) ")"); | |
1da177e4 | 37 | |
86a1e189 WVS |
38 | static bool nowayout = WATCHDOG_NOWAYOUT; |
39 | module_param(nowayout, bool, 0); | |
f92d3749 AC |
40 | MODULE_PARM_DESC(nowayout, |
41 | "Watchdog cannot be stopped once started (default=" | |
42 | __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); | |
1da177e4 | 43 | |
5f5e1909 | 44 | static int soft_noboot; |
1da177e4 | 45 | module_param(soft_noboot, int, 0); |
a77dba7e | 46 | MODULE_PARM_DESC(soft_noboot, |
a5132caf | 47 | "Softdog action, set to 1 to ignore reboots, 0 to reboot (default=0)"); |
1da177e4 | 48 | |
7fff4beb AJ |
49 | static int soft_panic; |
50 | module_param(soft_panic, int, 0); | |
51 | MODULE_PARM_DESC(soft_panic, | |
52 | "Softdog action, set to 1 to panic, 0 to reboot (default=0)"); | |
53 | ||
36a8947c WL |
54 | static char *soft_reboot_cmd; |
55 | module_param(soft_reboot_cmd, charp, 0000); | |
56 | MODULE_PARM_DESC(soft_reboot_cmd, | |
57 | "Set reboot command. Emergency reboot takes place if unset"); | |
58 | ||
59 | static bool soft_active_on_boot; | |
60 | module_param(soft_active_on_boot, bool, 0000); | |
61 | MODULE_PARM_DESC(soft_active_on_boot, | |
62 | "Set to true to active Softdog on boot (default=false)"); | |
63 | ||
8d5755b3 NC |
64 | static struct hrtimer softdog_ticktock; |
65 | static struct hrtimer softdog_preticktock; | |
66 | ||
36a8947c WL |
67 | static int reboot_kthread_fn(void *data) |
68 | { | |
69 | kernel_restart(soft_reboot_cmd); | |
70 | return -EPERM; /* Should not reach here */ | |
71 | } | |
72 | ||
73 | static void reboot_work_fn(struct work_struct *unused) | |
74 | { | |
75 | kthread_run(reboot_kthread_fn, NULL, "softdog_reboot"); | |
76 | } | |
77 | ||
8d5755b3 | 78 | static enum hrtimer_restart softdog_fire(struct hrtimer *timer) |
1da177e4 | 79 | { |
36a8947c WL |
80 | static bool soft_reboot_fired; |
81 | ||
5889f06b | 82 | module_put(THIS_MODULE); |
4a23e2bf | 83 | if (soft_noboot) { |
27c766aa | 84 | pr_crit("Triggered - Reboot ignored\n"); |
4a23e2bf | 85 | } else if (soft_panic) { |
27c766aa JP |
86 | pr_crit("Initiating panic\n"); |
87 | panic("Software Watchdog Timer expired"); | |
7fff4beb | 88 | } else { |
27c766aa | 89 | pr_crit("Initiating system reboot\n"); |
36a8947c WL |
90 | if (!soft_reboot_fired && soft_reboot_cmd != NULL) { |
91 | static DECLARE_WORK(reboot_work, reboot_work_fn); | |
92 | /* | |
93 | * The 'kernel_restart' is a 'might-sleep' operation. | |
94 | * Also, executing it in system-wide workqueues blocks | |
95 | * any driver from using the same workqueue in its | |
96 | * shutdown callback function. Thus, we should execute | |
97 | * the 'kernel_restart' in a standalone kernel thread. | |
98 | * But since starting a kernel thread is also a | |
99 | * 'might-sleep' operation, so the 'reboot_work' is | |
100 | * required as a launcher of the kernel thread. | |
101 | * | |
102 | * After request the reboot, restart the timer to | |
103 | * schedule an 'emergency_restart' reboot after | |
104 | * 'TIMER_MARGIN' seconds. It's because if the softdog | |
105 | * hangs, it might be because of scheduling issues. And | |
106 | * if that is the case, both 'schedule_work' and | |
107 | * 'kernel_restart' may possibly be malfunctional at the | |
108 | * same time. | |
109 | */ | |
110 | soft_reboot_fired = true; | |
111 | schedule_work(&reboot_work); | |
112 | hrtimer_add_expires_ns(timer, | |
113 | (u64)TIMER_MARGIN * NSEC_PER_SEC); | |
114 | ||
115 | return HRTIMER_RESTART; | |
116 | } | |
479d0f41 | 117 | emergency_restart(); |
27c766aa | 118 | pr_crit("Reboot didn't ?????\n"); |
1da177e4 | 119 | } |
1da177e4 | 120 | |
8d5755b3 NC |
121 | return HRTIMER_NORESTART; |
122 | } | |
44ba0f04 | 123 | |
2accf320 WS |
124 | static struct watchdog_device softdog_dev; |
125 | ||
8d5755b3 | 126 | static enum hrtimer_restart softdog_pretimeout(struct hrtimer *timer) |
2accf320 WS |
127 | { |
128 | watchdog_notify_pretimeout(&softdog_dev); | |
2accf320 | 129 | |
8d5755b3 NC |
130 | return HRTIMER_NORESTART; |
131 | } | |
2accf320 | 132 | |
a5132caf | 133 | static int softdog_ping(struct watchdog_device *w) |
1da177e4 | 134 | { |
8d5755b3 | 135 | if (!hrtimer_active(&softdog_ticktock)) |
5889f06b | 136 | __module_get(THIS_MODULE); |
8d5755b3 NC |
137 | hrtimer_start(&softdog_ticktock, ktime_set(w->timeout, 0), |
138 | HRTIMER_MODE_REL); | |
2accf320 | 139 | |
4cbc6902 WS |
140 | if (IS_ENABLED(CONFIG_SOFT_WATCHDOG_PRETIMEOUT)) { |
141 | if (w->pretimeout) | |
8d5755b3 NC |
142 | hrtimer_start(&softdog_preticktock, |
143 | ktime_set(w->timeout - w->pretimeout, 0), | |
144 | HRTIMER_MODE_REL); | |
4cbc6902 | 145 | else |
8d5755b3 | 146 | hrtimer_cancel(&softdog_preticktock); |
4cbc6902 | 147 | } |
2accf320 | 148 | |
1da177e4 LT |
149 | return 0; |
150 | } | |
151 | ||
a5132caf | 152 | static int softdog_stop(struct watchdog_device *w) |
1da177e4 | 153 | { |
8d5755b3 | 154 | if (hrtimer_cancel(&softdog_ticktock)) |
5889f06b LR |
155 | module_put(THIS_MODULE); |
156 | ||
4cbc6902 | 157 | if (IS_ENABLED(CONFIG_SOFT_WATCHDOG_PRETIMEOUT)) |
8d5755b3 | 158 | hrtimer_cancel(&softdog_preticktock); |
2accf320 | 159 | |
1da177e4 LT |
160 | return 0; |
161 | } | |
162 | ||
a5132caf AC |
163 | static struct watchdog_info softdog_info = { |
164 | .identity = "Software Watchdog", | |
4cbc6902 | 165 | .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE, |
1da177e4 LT |
166 | }; |
167 | ||
85f15cfc | 168 | static const struct watchdog_ops softdog_ops = { |
a5132caf AC |
169 | .owner = THIS_MODULE, |
170 | .start = softdog_ping, | |
171 | .stop = softdog_stop, | |
a5132caf AC |
172 | }; |
173 | ||
174 | static struct watchdog_device softdog_dev = { | |
175 | .info = &softdog_info, | |
176 | .ops = &softdog_ops, | |
177 | .min_timeout = 1, | |
e8cf96ab WS |
178 | .max_timeout = 65535, |
179 | .timeout = TIMER_MARGIN, | |
1da177e4 LT |
180 | }; |
181 | ||
0efc70b8 | 182 | static int __init softdog_init(void) |
1da177e4 LT |
183 | { |
184 | int ret; | |
185 | ||
e8cf96ab | 186 | watchdog_init_timeout(&softdog_dev, soft_margin, NULL); |
a5132caf | 187 | watchdog_set_nowayout(&softdog_dev, nowayout); |
84ebcc17 | 188 | watchdog_stop_on_reboot(&softdog_dev); |
1da177e4 | 189 | |
8d5755b3 NC |
190 | hrtimer_init(&softdog_ticktock, CLOCK_MONOTONIC, HRTIMER_MODE_REL); |
191 | softdog_ticktock.function = softdog_fire; | |
192 | ||
193 | if (IS_ENABLED(CONFIG_SOFT_WATCHDOG_PRETIMEOUT)) { | |
4cbc6902 | 194 | softdog_info.options |= WDIOF_PRETIMEOUT; |
8d5755b3 NC |
195 | hrtimer_init(&softdog_preticktock, CLOCK_MONOTONIC, |
196 | HRTIMER_MODE_REL); | |
197 | softdog_preticktock.function = softdog_pretimeout; | |
198 | } | |
4cbc6902 | 199 | |
36a8947c WL |
200 | if (soft_active_on_boot) |
201 | softdog_ping(&softdog_dev); | |
202 | ||
a5132caf | 203 | ret = watchdog_register_device(&softdog_dev); |
84ebcc17 | 204 | if (ret) |
1da177e4 | 205 | return ret; |
1da177e4 | 206 | |
e8cf96ab WS |
207 | pr_info("initialized. soft_noboot=%d soft_margin=%d sec soft_panic=%d (nowayout=%d)\n", |
208 | soft_noboot, softdog_dev.timeout, soft_panic, nowayout); | |
36a8947c WL |
209 | pr_info(" soft_reboot_cmd=%s soft_active_on_boot=%d\n", |
210 | soft_reboot_cmd ?: "<not set>", soft_active_on_boot); | |
1da177e4 LT |
211 | |
212 | return 0; | |
213 | } | |
0efc70b8 | 214 | module_init(softdog_init); |
1da177e4 | 215 | |
0efc70b8 | 216 | static void __exit softdog_exit(void) |
1da177e4 | 217 | { |
a5132caf | 218 | watchdog_unregister_device(&softdog_dev); |
1da177e4 | 219 | } |
0efc70b8 | 220 | module_exit(softdog_exit); |
1da177e4 LT |
221 | |
222 | MODULE_AUTHOR("Alan Cox"); | |
223 | MODULE_DESCRIPTION("Software Watchdog Device Driver"); | |
224 | MODULE_LICENSE("GPL"); |