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1da177e4 LT |
1 | /* |
2 | * SoftDog 0.07: A Software Watchdog Device | |
3 | * | |
4 | * (c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved. | |
5 | * http://www.redhat.com | |
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> | |
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 TS |
49 | #include <linux/jiffies.h> |
50 | ||
1da177e4 LT |
51 | #include <asm/uaccess.h> |
52 | ||
53 | #define PFX "SoftDog: " | |
54 | ||
55 | #define TIMER_MARGIN 60 /* Default is 60 seconds */ | |
56 | static int soft_margin = TIMER_MARGIN; /* in seconds */ | |
57 | module_param(soft_margin, int, 0); | |
58 | MODULE_PARM_DESC(soft_margin, "Watchdog soft_margin in seconds. (0<soft_margin<65536, default=" __MODULE_STRING(TIMER_MARGIN) ")"); | |
59 | ||
4bfdf378 | 60 | static int nowayout = WATCHDOG_NOWAYOUT; |
1da177e4 | 61 | module_param(nowayout, int, 0); |
bffda5c8 | 62 | MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); |
1da177e4 LT |
63 | |
64 | #ifdef ONLY_TESTING | |
65 | static int soft_noboot = 1; | |
66 | #else | |
67 | static int soft_noboot = 0; | |
68 | #endif /* ONLY_TESTING */ | |
69 | ||
70 | module_param(soft_noboot, int, 0); | |
71 | MODULE_PARM_DESC(soft_noboot, "Softdog action, set to 1 to ignore reboots, 0 to reboot (default depends on ONLY_TESTING)"); | |
72 | ||
73 | /* | |
74 | * Our timer | |
75 | */ | |
76 | ||
77 | static void watchdog_fire(unsigned long); | |
78 | ||
79 | static struct timer_list watchdog_ticktock = | |
80 | TIMER_INITIALIZER(watchdog_fire, 0, 0); | |
1cc77248 | 81 | static unsigned long driver_open, orphan_timer; |
1da177e4 LT |
82 | static char expect_close; |
83 | ||
84 | ||
85 | /* | |
86 | * If the timer expires.. | |
87 | */ | |
88 | ||
89 | static void watchdog_fire(unsigned long data) | |
90 | { | |
1cc77248 CE |
91 | if (test_and_clear_bit(0, &orphan_timer)) |
92 | module_put(THIS_MODULE); | |
93 | ||
1da177e4 LT |
94 | if (soft_noboot) |
95 | printk(KERN_CRIT PFX "Triggered - Reboot ignored.\n"); | |
96 | else | |
97 | { | |
98 | printk(KERN_CRIT PFX "Initiating system reboot.\n"); | |
479d0f41 | 99 | emergency_restart(); |
1da177e4 LT |
100 | printk(KERN_CRIT PFX "Reboot didn't ?????\n"); |
101 | } | |
102 | } | |
103 | ||
104 | /* | |
105 | * Softdog operations | |
106 | */ | |
107 | ||
108 | static int softdog_keepalive(void) | |
109 | { | |
110 | mod_timer(&watchdog_ticktock, jiffies+(soft_margin*HZ)); | |
111 | return 0; | |
112 | } | |
113 | ||
114 | static int softdog_stop(void) | |
115 | { | |
116 | del_timer(&watchdog_ticktock); | |
117 | return 0; | |
118 | } | |
119 | ||
120 | static int softdog_set_heartbeat(int t) | |
121 | { | |
122 | if ((t < 0x0001) || (t > 0xFFFF)) | |
123 | return -EINVAL; | |
124 | ||
125 | soft_margin = t; | |
126 | return 0; | |
127 | } | |
128 | ||
129 | /* | |
130 | * /dev/watchdog handling | |
131 | */ | |
132 | ||
133 | static int softdog_open(struct inode *inode, struct file *file) | |
134 | { | |
1cc77248 | 135 | if (test_and_set_bit(0, &driver_open)) |
1da177e4 | 136 | return -EBUSY; |
1cc77248 | 137 | if (!test_and_clear_bit(0, &orphan_timer)) |
1da177e4 LT |
138 | __module_get(THIS_MODULE); |
139 | /* | |
140 | * Activate timer | |
141 | */ | |
142 | softdog_keepalive(); | |
143 | return nonseekable_open(inode, file); | |
144 | } | |
145 | ||
146 | static int softdog_release(struct inode *inode, struct file *file) | |
147 | { | |
148 | /* | |
149 | * Shut off the timer. | |
150 | * Lock it in if it's a module and we set nowayout | |
151 | */ | |
152 | if (expect_close == 42) { | |
153 | softdog_stop(); | |
1cc77248 | 154 | module_put(THIS_MODULE); |
1da177e4 LT |
155 | } else { |
156 | printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n"); | |
1cc77248 | 157 | set_bit(0, &orphan_timer); |
1da177e4 LT |
158 | softdog_keepalive(); |
159 | } | |
1cc77248 | 160 | clear_bit(0, &driver_open); |
1da177e4 LT |
161 | expect_close = 0; |
162 | return 0; | |
163 | } | |
164 | ||
165 | static ssize_t softdog_write(struct file *file, const char __user *data, size_t len, loff_t *ppos) | |
166 | { | |
167 | /* | |
168 | * Refresh the timer. | |
169 | */ | |
170 | if(len) { | |
171 | if (!nowayout) { | |
172 | size_t i; | |
173 | ||
174 | /* In case it was set long ago */ | |
175 | expect_close = 0; | |
176 | ||
177 | for (i = 0; i != len; i++) { | |
178 | char c; | |
179 | ||
180 | if (get_user(c, data + i)) | |
181 | return -EFAULT; | |
182 | if (c == 'V') | |
183 | expect_close = 42; | |
184 | } | |
185 | } | |
186 | softdog_keepalive(); | |
187 | } | |
188 | return len; | |
189 | } | |
190 | ||
191 | static int softdog_ioctl(struct inode *inode, struct file *file, | |
192 | unsigned int cmd, unsigned long arg) | |
193 | { | |
194 | void __user *argp = (void __user *)arg; | |
195 | int __user *p = argp; | |
196 | int new_margin; | |
197 | static struct watchdog_info ident = { | |
198 | .options = WDIOF_SETTIMEOUT | | |
199 | WDIOF_KEEPALIVEPING | | |
200 | WDIOF_MAGICCLOSE, | |
201 | .firmware_version = 0, | |
202 | .identity = "Software Watchdog", | |
203 | }; | |
204 | switch (cmd) { | |
205 | default: | |
795b89d2 | 206 | return -ENOTTY; |
1da177e4 LT |
207 | case WDIOC_GETSUPPORT: |
208 | return copy_to_user(argp, &ident, | |
209 | 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); | |
225 | } | |
226 | } | |
227 | ||
228 | /* | |
229 | * Notifier for system down | |
230 | */ | |
231 | ||
232 | static int softdog_notify_sys(struct notifier_block *this, unsigned long code, | |
233 | void *unused) | |
234 | { | |
235 | if(code==SYS_DOWN || code==SYS_HALT) { | |
236 | /* Turn the WDT off */ | |
237 | softdog_stop(); | |
238 | } | |
239 | return NOTIFY_DONE; | |
240 | } | |
241 | ||
242 | /* | |
243 | * Kernel Interfaces | |
244 | */ | |
245 | ||
62322d25 | 246 | static const struct file_operations softdog_fops = { |
1da177e4 LT |
247 | .owner = THIS_MODULE, |
248 | .llseek = no_llseek, | |
249 | .write = softdog_write, | |
250 | .ioctl = softdog_ioctl, | |
251 | .open = softdog_open, | |
252 | .release = softdog_release, | |
253 | }; | |
254 | ||
255 | static struct miscdevice softdog_miscdev = { | |
256 | .minor = WATCHDOG_MINOR, | |
257 | .name = "watchdog", | |
258 | .fops = &softdog_fops, | |
259 | }; | |
260 | ||
261 | static struct notifier_block softdog_notifier = { | |
262 | .notifier_call = softdog_notify_sys, | |
263 | }; | |
264 | ||
265 | static char banner[] __initdata = KERN_INFO "Software Watchdog Timer: 0.07 initialized. soft_noboot=%d soft_margin=%d sec (nowayout= %d)\n"; | |
266 | ||
267 | static int __init watchdog_init(void) | |
268 | { | |
269 | int ret; | |
270 | ||
271 | /* Check that the soft_margin value is within it's range ; if not reset to the default */ | |
272 | if (softdog_set_heartbeat(soft_margin)) { | |
273 | softdog_set_heartbeat(TIMER_MARGIN); | |
274 | printk(KERN_INFO PFX "soft_margin value must be 0<soft_margin<65536, using %d\n", | |
275 | TIMER_MARGIN); | |
276 | } | |
277 | ||
278 | ret = register_reboot_notifier(&softdog_notifier); | |
279 | if (ret) { | |
280 | printk (KERN_ERR PFX "cannot register reboot notifier (err=%d)\n", | |
281 | ret); | |
282 | return ret; | |
283 | } | |
284 | ||
285 | ret = misc_register(&softdog_miscdev); | |
286 | if (ret) { | |
287 | printk (KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n", | |
288 | WATCHDOG_MINOR, ret); | |
289 | unregister_reboot_notifier(&softdog_notifier); | |
290 | return ret; | |
291 | } | |
292 | ||
293 | printk(banner, soft_noboot, soft_margin, nowayout); | |
294 | ||
295 | return 0; | |
296 | } | |
297 | ||
298 | static void __exit watchdog_exit(void) | |
299 | { | |
300 | misc_deregister(&softdog_miscdev); | |
301 | unregister_reboot_notifier(&softdog_notifier); | |
302 | } | |
303 | ||
304 | module_init(watchdog_init); | |
305 | module_exit(watchdog_exit); | |
306 | ||
307 | MODULE_AUTHOR("Alan Cox"); | |
308 | MODULE_DESCRIPTION("Software Watchdog Device Driver"); | |
309 | MODULE_LICENSE("GPL"); | |
310 | MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); |