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1da177e4 LT |
1 | /* |
2 | * SoftDog 0.07: A Software Watchdog Device | |
3 | * | |
143a2e54 WVS |
4 | * (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>, |
5 | * All Rights Reserved. | |
1da177e4 LT |
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> | |
143a2e54 | 36 | * Added Matt Domsch's nowayout module option. |
1da177e4 LT |
37 | */ |
38 | ||
39 | #include <linux/module.h> | |
40 | #include <linux/moduleparam.h> | |
1da177e4 LT |
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> | |
4e57b681 | 49 | #include <linux/jiffies.h> |
f92d3749 | 50 | #include <linux/uaccess.h> |
1da177e4 LT |
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); | |
f92d3749 AC |
57 | MODULE_PARM_DESC(soft_margin, |
58 | "Watchdog soft_margin in seconds. (0 < soft_margin < 65536, default=" | |
59 | __MODULE_STRING(TIMER_MARGIN) ")"); | |
1da177e4 | 60 | |
4bfdf378 | 61 | static int nowayout = WATCHDOG_NOWAYOUT; |
1da177e4 | 62 | module_param(nowayout, int, 0); |
f92d3749 AC |
63 | MODULE_PARM_DESC(nowayout, |
64 | "Watchdog cannot be stopped once started (default=" | |
65 | __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); | |
1da177e4 LT |
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); | |
a77dba7e WVS |
74 | MODULE_PARM_DESC(soft_noboot, |
75 | "Softdog action, set to 1 to ignore reboots, 0 to reboot " | |
76 | "(default depends on ONLY_TESTING)"); | |
1da177e4 LT |
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); | |
1cc77248 | 86 | static unsigned long driver_open, orphan_timer; |
1da177e4 LT |
87 | static char expect_close; |
88 | ||
89 | ||
90 | /* | |
91 | * If the timer expires.. | |
92 | */ | |
93 | ||
94 | static void watchdog_fire(unsigned long data) | |
95 | { | |
1cc77248 CE |
96 | if (test_and_clear_bit(0, &orphan_timer)) |
97 | module_put(THIS_MODULE); | |
98 | ||
1da177e4 LT |
99 | if (soft_noboot) |
100 | printk(KERN_CRIT PFX "Triggered - Reboot ignored.\n"); | |
f92d3749 | 101 | else { |
1da177e4 | 102 | printk(KERN_CRIT PFX "Initiating system reboot.\n"); |
479d0f41 | 103 | emergency_restart(); |
1da177e4 LT |
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 | { | |
1cc77248 | 139 | if (test_and_set_bit(0, &driver_open)) |
1da177e4 | 140 | return -EBUSY; |
1cc77248 | 141 | if (!test_and_clear_bit(0, &orphan_timer)) |
1da177e4 LT |
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(); | |
1cc77248 | 158 | module_put(THIS_MODULE); |
1da177e4 | 159 | } else { |
f92d3749 AC |
160 | printk(KERN_CRIT PFX |
161 | "Unexpected close, not stopping watchdog!\n"); | |
1cc77248 | 162 | set_bit(0, &orphan_timer); |
1da177e4 LT |
163 | softdog_keepalive(); |
164 | } | |
1cc77248 | 165 | clear_bit(0, &driver_open); |
1da177e4 LT |
166 | expect_close = 0; |
167 | return 0; | |
168 | } | |
169 | ||
f92d3749 AC |
170 | static ssize_t softdog_write(struct file *file, const char __user *data, |
171 | size_t len, loff_t *ppos) | |
1da177e4 LT |
172 | { |
173 | /* | |
174 | * Refresh the timer. | |
175 | */ | |
f92d3749 | 176 | if (len) { |
1da177e4 LT |
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 | ||
f92d3749 AC |
197 | static long softdog_ioctl(struct file *file, unsigned int cmd, |
198 | unsigned long arg) | |
1da177e4 LT |
199 | { |
200 | void __user *argp = (void __user *)arg; | |
201 | int __user *p = argp; | |
202 | int new_margin; | |
f92d3749 | 203 | static const struct watchdog_info ident = { |
1da177e4 LT |
204 | .options = WDIOF_SETTIMEOUT | |
205 | WDIOF_KEEPALIVEPING | | |
206 | WDIOF_MAGICCLOSE, | |
207 | .firmware_version = 0, | |
208 | .identity = "Software Watchdog", | |
209 | }; | |
210 | switch (cmd) { | |
f92d3749 AC |
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); | |
0c06090c WVS |
228 | default: |
229 | return -ENOTTY; | |
1da177e4 LT |
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 | { | |
f92d3749 | 240 | if (code == SYS_DOWN || code == SYS_HALT) |
1da177e4 LT |
241 | /* Turn the WDT off */ |
242 | softdog_stop(); | |
1da177e4 LT |
243 | return NOTIFY_DONE; |
244 | } | |
245 | ||
246 | /* | |
247 | * Kernel Interfaces | |
248 | */ | |
249 | ||
62322d25 | 250 | static const struct file_operations softdog_fops = { |
1da177e4 LT |
251 | .owner = THIS_MODULE, |
252 | .llseek = no_llseek, | |
253 | .write = softdog_write, | |
f92d3749 | 254 | .unlocked_ioctl = softdog_ioctl, |
1da177e4 LT |
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 | ||
a77dba7e WVS |
269 | static char banner[] __initdata = KERN_INFO "Software Watchdog Timer: 0.07 " |
270 | "initialized. soft_noboot=%d soft_margin=%d sec (nowayout= %d)\n"; | |
1da177e4 LT |
271 | |
272 | static int __init watchdog_init(void) | |
273 | { | |
274 | int ret; | |
275 | ||
f92d3749 AC |
276 | /* Check that the soft_margin value is within it's range; |
277 | if not reset to the default */ | |
1da177e4 LT |
278 | if (softdog_set_heartbeat(soft_margin)) { |
279 | softdog_set_heartbeat(TIMER_MARGIN); | |
f92d3749 AC |
280 | printk(KERN_INFO PFX |
281 | "soft_margin must be 0 < soft_margin < 65536, using %d\n", | |
1da177e4 LT |
282 | TIMER_MARGIN); |
283 | } | |
284 | ||
285 | ret = register_reboot_notifier(&softdog_notifier); | |
286 | if (ret) { | |
f92d3749 AC |
287 | printk(KERN_ERR PFX |
288 | "cannot register reboot notifier (err=%d)\n", ret); | |
1da177e4 LT |
289 | return ret; |
290 | } | |
291 | ||
292 | ret = misc_register(&softdog_miscdev); | |
293 | if (ret) { | |
f92d3749 AC |
294 | printk(KERN_ERR PFX |
295 | "cannot register miscdev on minor=%d (err=%d)\n", | |
296 | WATCHDOG_MINOR, ret); | |
1da177e4 LT |
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); |