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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> | |
41 | #include <linux/config.h> | |
42 | #include <linux/types.h> | |
43 | #include <linux/timer.h> | |
44 | #include <linux/miscdevice.h> | |
45 | #include <linux/watchdog.h> | |
46 | #include <linux/fs.h> | |
47 | #include <linux/notifier.h> | |
48 | #include <linux/reboot.h> | |
49 | #include <linux/init.h> | |
50 | #include <asm/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, "Watchdog soft_margin in seconds. (0<soft_margin<65536, default=" __MODULE_STRING(TIMER_MARGIN) ")"); | |
58 | ||
4bfdf378 | 59 | static int nowayout = WATCHDOG_NOWAYOUT; |
1da177e4 LT |
60 | module_param(nowayout, int, 0); |
61 | MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)"); | |
62 | ||
63 | #ifdef ONLY_TESTING | |
64 | static int soft_noboot = 1; | |
65 | #else | |
66 | static int soft_noboot = 0; | |
67 | #endif /* ONLY_TESTING */ | |
68 | ||
69 | module_param(soft_noboot, int, 0); | |
70 | MODULE_PARM_DESC(soft_noboot, "Softdog action, set to 1 to ignore reboots, 0 to reboot (default depends on ONLY_TESTING)"); | |
71 | ||
72 | /* | |
73 | * Our timer | |
74 | */ | |
75 | ||
76 | static void watchdog_fire(unsigned long); | |
77 | ||
78 | static struct timer_list watchdog_ticktock = | |
79 | TIMER_INITIALIZER(watchdog_fire, 0, 0); | |
80 | static unsigned long timer_alive; | |
81 | static char expect_close; | |
82 | ||
83 | ||
84 | /* | |
85 | * If the timer expires.. | |
86 | */ | |
87 | ||
88 | static void watchdog_fire(unsigned long data) | |
89 | { | |
90 | if (soft_noboot) | |
91 | printk(KERN_CRIT PFX "Triggered - Reboot ignored.\n"); | |
92 | else | |
93 | { | |
94 | printk(KERN_CRIT PFX "Initiating system reboot.\n"); | |
479d0f41 | 95 | emergency_restart(); |
1da177e4 LT |
96 | printk(KERN_CRIT PFX "Reboot didn't ?????\n"); |
97 | } | |
98 | } | |
99 | ||
100 | /* | |
101 | * Softdog operations | |
102 | */ | |
103 | ||
104 | static int softdog_keepalive(void) | |
105 | { | |
106 | mod_timer(&watchdog_ticktock, jiffies+(soft_margin*HZ)); | |
107 | return 0; | |
108 | } | |
109 | ||
110 | static int softdog_stop(void) | |
111 | { | |
112 | del_timer(&watchdog_ticktock); | |
113 | return 0; | |
114 | } | |
115 | ||
116 | static int softdog_set_heartbeat(int t) | |
117 | { | |
118 | if ((t < 0x0001) || (t > 0xFFFF)) | |
119 | return -EINVAL; | |
120 | ||
121 | soft_margin = t; | |
122 | return 0; | |
123 | } | |
124 | ||
125 | /* | |
126 | * /dev/watchdog handling | |
127 | */ | |
128 | ||
129 | static int softdog_open(struct inode *inode, struct file *file) | |
130 | { | |
131 | if(test_and_set_bit(0, &timer_alive)) | |
132 | return -EBUSY; | |
133 | if (nowayout) | |
134 | __module_get(THIS_MODULE); | |
135 | /* | |
136 | * Activate timer | |
137 | */ | |
138 | softdog_keepalive(); | |
139 | return nonseekable_open(inode, file); | |
140 | } | |
141 | ||
142 | static int softdog_release(struct inode *inode, struct file *file) | |
143 | { | |
144 | /* | |
145 | * Shut off the timer. | |
146 | * Lock it in if it's a module and we set nowayout | |
147 | */ | |
148 | if (expect_close == 42) { | |
149 | softdog_stop(); | |
150 | } else { | |
151 | printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n"); | |
152 | softdog_keepalive(); | |
153 | } | |
154 | clear_bit(0, &timer_alive); | |
155 | expect_close = 0; | |
156 | return 0; | |
157 | } | |
158 | ||
159 | static ssize_t softdog_write(struct file *file, const char __user *data, size_t len, loff_t *ppos) | |
160 | { | |
161 | /* | |
162 | * Refresh the timer. | |
163 | */ | |
164 | if(len) { | |
165 | if (!nowayout) { | |
166 | size_t i; | |
167 | ||
168 | /* In case it was set long ago */ | |
169 | expect_close = 0; | |
170 | ||
171 | for (i = 0; i != len; i++) { | |
172 | char c; | |
173 | ||
174 | if (get_user(c, data + i)) | |
175 | return -EFAULT; | |
176 | if (c == 'V') | |
177 | expect_close = 42; | |
178 | } | |
179 | } | |
180 | softdog_keepalive(); | |
181 | } | |
182 | return len; | |
183 | } | |
184 | ||
185 | static int softdog_ioctl(struct inode *inode, struct file *file, | |
186 | unsigned int cmd, unsigned long arg) | |
187 | { | |
188 | void __user *argp = (void __user *)arg; | |
189 | int __user *p = argp; | |
190 | int new_margin; | |
191 | static struct watchdog_info ident = { | |
192 | .options = WDIOF_SETTIMEOUT | | |
193 | WDIOF_KEEPALIVEPING | | |
194 | WDIOF_MAGICCLOSE, | |
195 | .firmware_version = 0, | |
196 | .identity = "Software Watchdog", | |
197 | }; | |
198 | switch (cmd) { | |
199 | default: | |
200 | return -ENOIOCTLCMD; | |
201 | case WDIOC_GETSUPPORT: | |
202 | return copy_to_user(argp, &ident, | |
203 | sizeof(ident)) ? -EFAULT : 0; | |
204 | case WDIOC_GETSTATUS: | |
205 | case WDIOC_GETBOOTSTATUS: | |
206 | return put_user(0, p); | |
207 | case WDIOC_KEEPALIVE: | |
208 | softdog_keepalive(); | |
209 | return 0; | |
210 | case WDIOC_SETTIMEOUT: | |
211 | if (get_user(new_margin, p)) | |
212 | return -EFAULT; | |
213 | if (softdog_set_heartbeat(new_margin)) | |
214 | return -EINVAL; | |
215 | softdog_keepalive(); | |
216 | /* Fall */ | |
217 | case WDIOC_GETTIMEOUT: | |
218 | return put_user(soft_margin, p); | |
219 | } | |
220 | } | |
221 | ||
222 | /* | |
223 | * Notifier for system down | |
224 | */ | |
225 | ||
226 | static int softdog_notify_sys(struct notifier_block *this, unsigned long code, | |
227 | void *unused) | |
228 | { | |
229 | if(code==SYS_DOWN || code==SYS_HALT) { | |
230 | /* Turn the WDT off */ | |
231 | softdog_stop(); | |
232 | } | |
233 | return NOTIFY_DONE; | |
234 | } | |
235 | ||
236 | /* | |
237 | * Kernel Interfaces | |
238 | */ | |
239 | ||
240 | static struct file_operations softdog_fops = { | |
241 | .owner = THIS_MODULE, | |
242 | .llseek = no_llseek, | |
243 | .write = softdog_write, | |
244 | .ioctl = softdog_ioctl, | |
245 | .open = softdog_open, | |
246 | .release = softdog_release, | |
247 | }; | |
248 | ||
249 | static struct miscdevice softdog_miscdev = { | |
250 | .minor = WATCHDOG_MINOR, | |
251 | .name = "watchdog", | |
252 | .fops = &softdog_fops, | |
253 | }; | |
254 | ||
255 | static struct notifier_block softdog_notifier = { | |
256 | .notifier_call = softdog_notify_sys, | |
257 | }; | |
258 | ||
259 | static char banner[] __initdata = KERN_INFO "Software Watchdog Timer: 0.07 initialized. soft_noboot=%d soft_margin=%d sec (nowayout= %d)\n"; | |
260 | ||
261 | static int __init watchdog_init(void) | |
262 | { | |
263 | int ret; | |
264 | ||
265 | /* Check that the soft_margin value is within it's range ; if not reset to the default */ | |
266 | if (softdog_set_heartbeat(soft_margin)) { | |
267 | softdog_set_heartbeat(TIMER_MARGIN); | |
268 | printk(KERN_INFO PFX "soft_margin value must be 0<soft_margin<65536, using %d\n", | |
269 | TIMER_MARGIN); | |
270 | } | |
271 | ||
272 | ret = register_reboot_notifier(&softdog_notifier); | |
273 | if (ret) { | |
274 | printk (KERN_ERR PFX "cannot register reboot notifier (err=%d)\n", | |
275 | ret); | |
276 | return ret; | |
277 | } | |
278 | ||
279 | ret = misc_register(&softdog_miscdev); | |
280 | if (ret) { | |
281 | printk (KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n", | |
282 | WATCHDOG_MINOR, ret); | |
283 | unregister_reboot_notifier(&softdog_notifier); | |
284 | return ret; | |
285 | } | |
286 | ||
287 | printk(banner, soft_noboot, soft_margin, nowayout); | |
288 | ||
289 | return 0; | |
290 | } | |
291 | ||
292 | static void __exit watchdog_exit(void) | |
293 | { | |
294 | misc_deregister(&softdog_miscdev); | |
295 | unregister_reboot_notifier(&softdog_notifier); | |
296 | } | |
297 | ||
298 | module_init(watchdog_init); | |
299 | module_exit(watchdog_exit); | |
300 | ||
301 | MODULE_AUTHOR("Alan Cox"); | |
302 | MODULE_DESCRIPTION("Software Watchdog Device Driver"); | |
303 | MODULE_LICENSE("GPL"); | |
304 | MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); |