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1da177e4 LT |
1 | /* |
2 | * SoftDog 0.07: A Software Watchdog Device | |
3 | * | |
29fa0586 | 4 | * (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>, All Rights Reserved. |
1da177e4 LT |
5 | * |
6 | * This program is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU General Public License | |
8 | * as published by the Free Software Foundation; either version | |
9 | * 2 of the License, or (at your option) any later version. | |
10 | * | |
11 | * Neither Alan Cox nor CymruNet Ltd. admit liability nor provide | |
12 | * warranty for any of this software. This material is provided | |
13 | * "AS-IS" and at no charge. | |
14 | * | |
15 | * (c) Copyright 1995 Alan Cox <alan@lxorguk.ukuu.org.uk> | |
16 | * | |
17 | * Software only watchdog driver. Unlike its big brother the WDT501P | |
18 | * driver this won't always recover a failed machine. | |
19 | * | |
20 | * 03/96: Angelo Haritsis <ah@doc.ic.ac.uk> : | |
21 | * Modularised. | |
22 | * Added soft_margin; use upon insmod to change the timer delay. | |
23 | * NB: uses same minor as wdt (WATCHDOG_MINOR); we could use separate | |
24 | * minors. | |
25 | * | |
26 | * 19980911 Alan Cox | |
27 | * Made SMP safe for 2.3.x | |
28 | * | |
29 | * 20011127 Joel Becker (jlbec@evilplan.org> | |
30 | * Added soft_noboot; Allows testing the softdog trigger without | |
31 | * requiring a recompile. | |
32 | * Added WDIOC_GETTIMEOUT and WDIOC_SETTIMOUT. | |
33 | * | |
34 | * 20020530 Joel Becker <joel.becker@oracle.com> | |
35 | * Added Matt Domsch's nowayout module option. | |
36 | */ | |
37 | ||
38 | #include <linux/module.h> | |
39 | #include <linux/moduleparam.h> | |
1da177e4 LT |
40 | #include <linux/types.h> |
41 | #include <linux/timer.h> | |
42 | #include <linux/miscdevice.h> | |
43 | #include <linux/watchdog.h> | |
44 | #include <linux/fs.h> | |
45 | #include <linux/notifier.h> | |
46 | #include <linux/reboot.h> | |
47 | #include <linux/init.h> | |
4e57b681 | 48 | #include <linux/jiffies.h> |
f92d3749 | 49 | #include <linux/uaccess.h> |
1da177e4 LT |
50 | |
51 | #define PFX "SoftDog: " | |
52 | ||
53 | #define TIMER_MARGIN 60 /* Default is 60 seconds */ | |
54 | static int soft_margin = TIMER_MARGIN; /* in seconds */ | |
55 | module_param(soft_margin, int, 0); | |
f92d3749 AC |
56 | MODULE_PARM_DESC(soft_margin, |
57 | "Watchdog soft_margin in seconds. (0 < soft_margin < 65536, default=" | |
58 | __MODULE_STRING(TIMER_MARGIN) ")"); | |
1da177e4 | 59 | |
4bfdf378 | 60 | static int nowayout = WATCHDOG_NOWAYOUT; |
1da177e4 | 61 | module_param(nowayout, int, 0); |
f92d3749 AC |
62 | MODULE_PARM_DESC(nowayout, |
63 | "Watchdog cannot be stopped once started (default=" | |
64 | __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); | |
1da177e4 LT |
65 | |
66 | #ifdef ONLY_TESTING | |
67 | static int soft_noboot = 1; | |
68 | #else | |
69 | static int soft_noboot = 0; | |
70 | #endif /* ONLY_TESTING */ | |
71 | ||
72 | module_param(soft_noboot, int, 0); | |
73 | MODULE_PARM_DESC(soft_noboot, "Softdog action, set to 1 to ignore reboots, 0 to reboot (default depends on ONLY_TESTING)"); | |
74 | ||
75 | /* | |
76 | * Our timer | |
77 | */ | |
78 | ||
79 | static void watchdog_fire(unsigned long); | |
80 | ||
81 | static struct timer_list watchdog_ticktock = | |
82 | TIMER_INITIALIZER(watchdog_fire, 0, 0); | |
1cc77248 | 83 | static unsigned long driver_open, orphan_timer; |
1da177e4 LT |
84 | static char expect_close; |
85 | ||
86 | ||
87 | /* | |
88 | * If the timer expires.. | |
89 | */ | |
90 | ||
91 | static void watchdog_fire(unsigned long data) | |
92 | { | |
1cc77248 CE |
93 | if (test_and_clear_bit(0, &orphan_timer)) |
94 | module_put(THIS_MODULE); | |
95 | ||
1da177e4 LT |
96 | if (soft_noboot) |
97 | printk(KERN_CRIT PFX "Triggered - Reboot ignored.\n"); | |
f92d3749 | 98 | else { |
1da177e4 | 99 | printk(KERN_CRIT PFX "Initiating system reboot.\n"); |
479d0f41 | 100 | emergency_restart(); |
1da177e4 LT |
101 | printk(KERN_CRIT PFX "Reboot didn't ?????\n"); |
102 | } | |
103 | } | |
104 | ||
105 | /* | |
106 | * Softdog operations | |
107 | */ | |
108 | ||
109 | static int softdog_keepalive(void) | |
110 | { | |
111 | mod_timer(&watchdog_ticktock, jiffies+(soft_margin*HZ)); | |
112 | return 0; | |
113 | } | |
114 | ||
115 | static int softdog_stop(void) | |
116 | { | |
117 | del_timer(&watchdog_ticktock); | |
118 | return 0; | |
119 | } | |
120 | ||
121 | static int softdog_set_heartbeat(int t) | |
122 | { | |
123 | if ((t < 0x0001) || (t > 0xFFFF)) | |
124 | return -EINVAL; | |
125 | ||
126 | soft_margin = t; | |
127 | return 0; | |
128 | } | |
129 | ||
130 | /* | |
131 | * /dev/watchdog handling | |
132 | */ | |
133 | ||
134 | static int softdog_open(struct inode *inode, struct file *file) | |
135 | { | |
1cc77248 | 136 | if (test_and_set_bit(0, &driver_open)) |
1da177e4 | 137 | return -EBUSY; |
1cc77248 | 138 | if (!test_and_clear_bit(0, &orphan_timer)) |
1da177e4 LT |
139 | __module_get(THIS_MODULE); |
140 | /* | |
141 | * Activate timer | |
142 | */ | |
143 | softdog_keepalive(); | |
144 | return nonseekable_open(inode, file); | |
145 | } | |
146 | ||
147 | static int softdog_release(struct inode *inode, struct file *file) | |
148 | { | |
149 | /* | |
150 | * Shut off the timer. | |
151 | * Lock it in if it's a module and we set nowayout | |
152 | */ | |
153 | if (expect_close == 42) { | |
154 | softdog_stop(); | |
1cc77248 | 155 | module_put(THIS_MODULE); |
1da177e4 | 156 | } else { |
f92d3749 AC |
157 | printk(KERN_CRIT PFX |
158 | "Unexpected close, not stopping watchdog!\n"); | |
1cc77248 | 159 | set_bit(0, &orphan_timer); |
1da177e4 LT |
160 | softdog_keepalive(); |
161 | } | |
1cc77248 | 162 | clear_bit(0, &driver_open); |
1da177e4 LT |
163 | expect_close = 0; |
164 | return 0; | |
165 | } | |
166 | ||
f92d3749 AC |
167 | static ssize_t softdog_write(struct file *file, const char __user *data, |
168 | size_t len, loff_t *ppos) | |
1da177e4 LT |
169 | { |
170 | /* | |
171 | * Refresh the timer. | |
172 | */ | |
f92d3749 | 173 | if (len) { |
1da177e4 LT |
174 | if (!nowayout) { |
175 | size_t i; | |
176 | ||
177 | /* In case it was set long ago */ | |
178 | expect_close = 0; | |
179 | ||
180 | for (i = 0; i != len; i++) { | |
181 | char c; | |
182 | ||
183 | if (get_user(c, data + i)) | |
184 | return -EFAULT; | |
185 | if (c == 'V') | |
186 | expect_close = 42; | |
187 | } | |
188 | } | |
189 | softdog_keepalive(); | |
190 | } | |
191 | return len; | |
192 | } | |
193 | ||
f92d3749 AC |
194 | static long softdog_ioctl(struct file *file, unsigned int cmd, |
195 | unsigned long arg) | |
1da177e4 LT |
196 | { |
197 | void __user *argp = (void __user *)arg; | |
198 | int __user *p = argp; | |
199 | int new_margin; | |
f92d3749 | 200 | static const struct watchdog_info ident = { |
1da177e4 LT |
201 | .options = WDIOF_SETTIMEOUT | |
202 | WDIOF_KEEPALIVEPING | | |
203 | WDIOF_MAGICCLOSE, | |
204 | .firmware_version = 0, | |
205 | .identity = "Software Watchdog", | |
206 | }; | |
207 | switch (cmd) { | |
f92d3749 AC |
208 | case WDIOC_GETSUPPORT: |
209 | return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0; | |
210 | case WDIOC_GETSTATUS: | |
211 | case WDIOC_GETBOOTSTATUS: | |
212 | return put_user(0, p); | |
213 | case WDIOC_KEEPALIVE: | |
214 | softdog_keepalive(); | |
215 | return 0; | |
216 | case WDIOC_SETTIMEOUT: | |
217 | if (get_user(new_margin, p)) | |
218 | return -EFAULT; | |
219 | if (softdog_set_heartbeat(new_margin)) | |
220 | return -EINVAL; | |
221 | softdog_keepalive(); | |
222 | /* Fall */ | |
223 | case WDIOC_GETTIMEOUT: | |
224 | return put_user(soft_margin, p); | |
0c06090c WVS |
225 | default: |
226 | return -ENOTTY; | |
1da177e4 LT |
227 | } |
228 | } | |
229 | ||
230 | /* | |
231 | * Notifier for system down | |
232 | */ | |
233 | ||
234 | static int softdog_notify_sys(struct notifier_block *this, unsigned long code, | |
235 | void *unused) | |
236 | { | |
f92d3749 | 237 | if (code == SYS_DOWN || code == SYS_HALT) |
1da177e4 LT |
238 | /* Turn the WDT off */ |
239 | softdog_stop(); | |
1da177e4 LT |
240 | return NOTIFY_DONE; |
241 | } | |
242 | ||
243 | /* | |
244 | * Kernel Interfaces | |
245 | */ | |
246 | ||
62322d25 | 247 | static const struct file_operations softdog_fops = { |
1da177e4 LT |
248 | .owner = THIS_MODULE, |
249 | .llseek = no_llseek, | |
250 | .write = softdog_write, | |
f92d3749 | 251 | .unlocked_ioctl = softdog_ioctl, |
1da177e4 LT |
252 | .open = softdog_open, |
253 | .release = softdog_release, | |
254 | }; | |
255 | ||
256 | static struct miscdevice softdog_miscdev = { | |
257 | .minor = WATCHDOG_MINOR, | |
258 | .name = "watchdog", | |
259 | .fops = &softdog_fops, | |
260 | }; | |
261 | ||
262 | static struct notifier_block softdog_notifier = { | |
263 | .notifier_call = softdog_notify_sys, | |
264 | }; | |
265 | ||
266 | static char banner[] __initdata = KERN_INFO "Software Watchdog Timer: 0.07 initialized. soft_noboot=%d soft_margin=%d sec (nowayout= %d)\n"; | |
267 | ||
268 | static int __init watchdog_init(void) | |
269 | { | |
270 | int ret; | |
271 | ||
f92d3749 AC |
272 | /* Check that the soft_margin value is within it's range; |
273 | if not reset to the default */ | |
1da177e4 LT |
274 | if (softdog_set_heartbeat(soft_margin)) { |
275 | softdog_set_heartbeat(TIMER_MARGIN); | |
f92d3749 AC |
276 | printk(KERN_INFO PFX |
277 | "soft_margin must be 0 < soft_margin < 65536, using %d\n", | |
1da177e4 LT |
278 | TIMER_MARGIN); |
279 | } | |
280 | ||
281 | ret = register_reboot_notifier(&softdog_notifier); | |
282 | if (ret) { | |
f92d3749 AC |
283 | printk(KERN_ERR PFX |
284 | "cannot register reboot notifier (err=%d)\n", ret); | |
1da177e4 LT |
285 | return ret; |
286 | } | |
287 | ||
288 | ret = misc_register(&softdog_miscdev); | |
289 | if (ret) { | |
f92d3749 AC |
290 | printk(KERN_ERR PFX |
291 | "cannot register miscdev on minor=%d (err=%d)\n", | |
292 | WATCHDOG_MINOR, ret); | |
1da177e4 LT |
293 | unregister_reboot_notifier(&softdog_notifier); |
294 | return ret; | |
295 | } | |
296 | ||
297 | printk(banner, soft_noboot, soft_margin, nowayout); | |
298 | ||
299 | return 0; | |
300 | } | |
301 | ||
302 | static void __exit watchdog_exit(void) | |
303 | { | |
304 | misc_deregister(&softdog_miscdev); | |
305 | unregister_reboot_notifier(&softdog_notifier); | |
306 | } | |
307 | ||
308 | module_init(watchdog_init); | |
309 | module_exit(watchdog_exit); | |
310 | ||
311 | MODULE_AUTHOR("Alan Cox"); | |
312 | MODULE_DESCRIPTION("Software Watchdog Device Driver"); | |
313 | MODULE_LICENSE("GPL"); | |
314 | MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); |