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1 | /* |
2 | * SoftDog 0.07: 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 | #include <linux/module.h> |
40 | #include <linux/moduleparam.h> |
41 | #include <linux/types.h> |
42 | #include <linux/timer.h> |
43 | #include <linux/miscdevice.h> |
44 | #include <linux/watchdog.h> |
45 | #include <linux/fs.h> |
46 | #include <linux/notifier.h> |
47 | #include <linux/reboot.h> |
48 | #include <linux/init.h> |
49 | #include <linux/jiffies.h> |
50 | #include <linux/uaccess.h> |
51 | |
52 | #define PFX "SoftDog: " |
53 | |
54 | #define TIMER_MARGIN 60 /* Default is 60 seconds */ |
55 | static int soft_margin = TIMER_MARGIN; /* in seconds */ |
56 | module_param(soft_margin, int, 0); |
57 | MODULE_PARM_DESC(soft_margin, |
58 | "Watchdog soft_margin in seconds. (0 < soft_margin < 65536, default=" |
59 | __MODULE_STRING(TIMER_MARGIN) ")"); |
60 | |
61 | static int nowayout = WATCHDOG_NOWAYOUT; |
62 | module_param(nowayout, int, 0); |
63 | MODULE_PARM_DESC(nowayout, |
64 | "Watchdog cannot be stopped once started (default=" |
65 | __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); |
66 | |
67 | #ifdef ONLY_TESTING |
68 | static int soft_noboot = 1; |
69 | #else |
70 | static int soft_noboot = 0; |
71 | #endif /* ONLY_TESTING */ |
72 | |
73 | module_param(soft_noboot, int, 0); |
74 | MODULE_PARM_DESC(soft_noboot, |
75 | "Softdog action, set to 1 to ignore reboots, 0 to reboot " |
76 | "(default depends on ONLY_TESTING)"); |
77 | |
78 | /* |
79 | * Our timer |
80 | */ |
81 | |
82 | static void watchdog_fire(unsigned long); |
83 | |
84 | static struct timer_list watchdog_ticktock = |
85 | TIMER_INITIALIZER(watchdog_fire, 0, 0); |
86 | static unsigned long driver_open, orphan_timer; |
87 | static char expect_close; |
88 | |
89 | |
90 | /* |
91 | * If the timer expires.. |
92 | */ |
93 | |
94 | static void watchdog_fire(unsigned long data) |
95 | { |
96 | if (test_and_clear_bit(0, &orphan_timer)) |
97 | module_put(THIS_MODULE); |
98 | |
99 | if (soft_noboot) |
100 | printk(KERN_CRIT PFX "Triggered - Reboot ignored.\n"); |
101 | else { |
102 | printk(KERN_CRIT PFX "Initiating system reboot.\n"); |
103 | emergency_restart(); |
104 | printk(KERN_CRIT PFX "Reboot didn't ?????\n"); |
105 | } |
106 | } |
107 | |
108 | /* |
109 | * Softdog operations |
110 | */ |
111 | |
112 | static int softdog_keepalive(void) |
113 | { |
114 | mod_timer(&watchdog_ticktock, jiffies+(soft_margin*HZ)); |
115 | return 0; |
116 | } |
117 | |
118 | static int softdog_stop(void) |
119 | { |
120 | del_timer(&watchdog_ticktock); |
121 | return 0; |
122 | } |
123 | |
124 | static int softdog_set_heartbeat(int t) |
125 | { |
126 | if ((t < 0x0001) || (t > 0xFFFF)) |
127 | return -EINVAL; |
128 | |
129 | soft_margin = t; |
130 | return 0; |
131 | } |
132 | |
133 | /* |
134 | * /dev/watchdog handling |
135 | */ |
136 | |
137 | static int softdog_open(struct inode *inode, struct file *file) |
138 | { |
139 | if (test_and_set_bit(0, &driver_open)) |
140 | return -EBUSY; |
141 | if (!test_and_clear_bit(0, &orphan_timer)) |
142 | __module_get(THIS_MODULE); |
143 | /* |
144 | * Activate timer |
145 | */ |
146 | softdog_keepalive(); |
147 | return nonseekable_open(inode, file); |
148 | } |
149 | |
150 | static int softdog_release(struct inode *inode, struct file *file) |
151 | { |
152 | /* |
153 | * Shut off the timer. |
154 | * Lock it in if it's a module and we set nowayout |
155 | */ |
156 | if (expect_close == 42) { |
157 | softdog_stop(); |
158 | module_put(THIS_MODULE); |
159 | } else { |
160 | printk(KERN_CRIT PFX |
161 | "Unexpected close, not stopping watchdog!\n"); |
162 | set_bit(0, &orphan_timer); |
163 | softdog_keepalive(); |
164 | } |
165 | clear_bit(0, &driver_open); |
166 | expect_close = 0; |
167 | return 0; |
168 | } |
169 | |
170 | static ssize_t softdog_write(struct file *file, const char __user *data, |
171 | size_t len, loff_t *ppos) |
172 | { |
173 | /* |
174 | * Refresh the timer. |
175 | */ |
176 | if (len) { |
177 | if (!nowayout) { |
178 | size_t i; |
179 | |
180 | /* In case it was set long ago */ |
181 | expect_close = 0; |
182 | |
183 | for (i = 0; i != len; i++) { |
184 | char c; |
185 | |
186 | if (get_user(c, data + i)) |
187 | return -EFAULT; |
188 | if (c == 'V') |
189 | expect_close = 42; |
190 | } |
191 | } |
192 | softdog_keepalive(); |
193 | } |
194 | return len; |
195 | } |
196 | |
197 | static long softdog_ioctl(struct file *file, unsigned int cmd, |
198 | unsigned long arg) |
199 | { |
200 | void __user *argp = (void __user *)arg; |
201 | int __user *p = argp; |
202 | int new_margin; |
203 | static const struct watchdog_info ident = { |
204 | .options = WDIOF_SETTIMEOUT | |
205 | WDIOF_KEEPALIVEPING | |
206 | WDIOF_MAGICCLOSE, |
207 | .firmware_version = 0, |
208 | .identity = "Software Watchdog", |
209 | }; |
210 | switch (cmd) { |
211 | case WDIOC_GETSUPPORT: |
212 | return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0; |
213 | case WDIOC_GETSTATUS: |
214 | case WDIOC_GETBOOTSTATUS: |
215 | return put_user(0, p); |
216 | case WDIOC_KEEPALIVE: |
217 | softdog_keepalive(); |
218 | return 0; |
219 | case WDIOC_SETTIMEOUT: |
220 | if (get_user(new_margin, p)) |
221 | return -EFAULT; |
222 | if (softdog_set_heartbeat(new_margin)) |
223 | return -EINVAL; |
224 | softdog_keepalive(); |
225 | /* Fall */ |
226 | case WDIOC_GETTIMEOUT: |
227 | return put_user(soft_margin, p); |
228 | default: |
229 | return -ENOTTY; |
230 | } |
231 | } |
232 | |
233 | /* |
234 | * Notifier for system down |
235 | */ |
236 | |
237 | static int softdog_notify_sys(struct notifier_block *this, unsigned long code, |
238 | void *unused) |
239 | { |
240 | if (code == SYS_DOWN || code == SYS_HALT) |
241 | /* Turn the WDT off */ |
242 | softdog_stop(); |
243 | return NOTIFY_DONE; |
244 | } |
245 | |
246 | /* |
247 | * Kernel Interfaces |
248 | */ |
249 | |
250 | static const struct file_operations softdog_fops = { |
251 | .owner = THIS_MODULE, |
252 | .llseek = no_llseek, |
253 | .write = softdog_write, |
254 | .unlocked_ioctl = softdog_ioctl, |
255 | .open = softdog_open, |
256 | .release = softdog_release, |
257 | }; |
258 | |
259 | static struct miscdevice softdog_miscdev = { |
260 | .minor = WATCHDOG_MINOR, |
261 | .name = "watchdog", |
262 | .fops = &softdog_fops, |
263 | }; |
264 | |
265 | static struct notifier_block softdog_notifier = { |
266 | .notifier_call = softdog_notify_sys, |
267 | }; |
268 | |
269 | static char banner[] __initdata = KERN_INFO "Software Watchdog Timer: 0.07 " |
270 | "initialized. soft_noboot=%d soft_margin=%d sec (nowayout= %d)\n"; |
271 | |
272 | static int __init watchdog_init(void) |
273 | { |
274 | int ret; |
275 | |
276 | /* Check that the soft_margin value is within it's range; |
277 | if not reset to the default */ |
278 | if (softdog_set_heartbeat(soft_margin)) { |
279 | softdog_set_heartbeat(TIMER_MARGIN); |
280 | printk(KERN_INFO PFX |
281 | "soft_margin must be 0 < soft_margin < 65536, using %d\n", |
282 | TIMER_MARGIN); |
283 | } |
284 | |
285 | ret = register_reboot_notifier(&softdog_notifier); |
286 | if (ret) { |
287 | printk(KERN_ERR PFX |
288 | "cannot register reboot notifier (err=%d)\n", ret); |
289 | return ret; |
290 | } |
291 | |
292 | ret = misc_register(&softdog_miscdev); |
293 | if (ret) { |
294 | printk(KERN_ERR PFX |
295 | "cannot register miscdev on minor=%d (err=%d)\n", |
296 | WATCHDOG_MINOR, ret); |
297 | unregister_reboot_notifier(&softdog_notifier); |
298 | return ret; |
299 | } |
300 | |
301 | printk(banner, soft_noboot, soft_margin, nowayout); |
302 | |
303 | return 0; |
304 | } |
305 | |
306 | static void __exit watchdog_exit(void) |
307 | { |
308 | misc_deregister(&softdog_miscdev); |
309 | unregister_reboot_notifier(&softdog_notifier); |
310 | } |
311 | |
312 | module_init(watchdog_init); |
313 | module_exit(watchdog_exit); |
314 | |
315 | MODULE_AUTHOR("Alan Cox"); |
316 | MODULE_DESCRIPTION("Software Watchdog Device Driver"); |
317 | MODULE_LICENSE("GPL"); |
318 | MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); |
319 |
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