[WATCHDOG] softdog-timer-running-oops.patch
[linux-3.10.git] / drivers / char / watchdog / softdog.c
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
59 static int nowayout = WATCHDOG_NOWAYOUT;
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 driver_open, orphan_timer;
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 (test_and_clear_bit(0, &orphan_timer))
91                 module_put(THIS_MODULE);
92
93         if (soft_noboot)
94                 printk(KERN_CRIT PFX "Triggered - Reboot ignored.\n");
95         else
96         {
97                 printk(KERN_CRIT PFX "Initiating system reboot.\n");
98                 emergency_restart();
99                 printk(KERN_CRIT PFX "Reboot didn't ?????\n");
100         }
101 }
102
103 /*
104  *      Softdog operations
105  */
106
107 static int softdog_keepalive(void)
108 {
109         mod_timer(&watchdog_ticktock, jiffies+(soft_margin*HZ));
110         return 0;
111 }
112
113 static int softdog_stop(void)
114 {
115         del_timer(&watchdog_ticktock);
116         return 0;
117 }
118
119 static int softdog_set_heartbeat(int t)
120 {
121         if ((t < 0x0001) || (t > 0xFFFF))
122                 return -EINVAL;
123
124         soft_margin = t;
125         return 0;
126 }
127
128 /*
129  *      /dev/watchdog handling
130  */
131
132 static int softdog_open(struct inode *inode, struct file *file)
133 {
134         if (test_and_set_bit(0, &driver_open))
135                 return -EBUSY;
136         if (!test_and_clear_bit(0, &orphan_timer))
137                 __module_get(THIS_MODULE);
138         /*
139          *      Activate timer
140          */
141         softdog_keepalive();
142         return nonseekable_open(inode, file);
143 }
144
145 static int softdog_release(struct inode *inode, struct file *file)
146 {
147         /*
148          *      Shut off the timer.
149          *      Lock it in if it's a module and we set nowayout
150          */
151         if (expect_close == 42) {
152                 softdog_stop();
153                 module_put(THIS_MODULE);
154         } else {
155                 printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n");
156                 set_bit(0, &orphan_timer);
157                 softdog_keepalive();
158         }
159         clear_bit(0, &driver_open);
160         expect_close = 0;
161         return 0;
162 }
163
164 static ssize_t softdog_write(struct file *file, const char __user *data, size_t len, loff_t *ppos)
165 {
166         /*
167          *      Refresh the timer.
168          */
169         if(len) {
170                 if (!nowayout) {
171                         size_t i;
172
173                         /* In case it was set long ago */
174                         expect_close = 0;
175
176                         for (i = 0; i != len; i++) {
177                                 char c;
178
179                                 if (get_user(c, data + i))
180                                         return -EFAULT;
181                                 if (c == 'V')
182                                         expect_close = 42;
183                         }
184                 }
185                 softdog_keepalive();
186         }
187         return len;
188 }
189
190 static int softdog_ioctl(struct inode *inode, struct file *file,
191         unsigned int cmd, unsigned long arg)
192 {
193         void __user *argp = (void __user *)arg;
194         int __user *p = argp;
195         int new_margin;
196         static struct watchdog_info ident = {
197                 .options =              WDIOF_SETTIMEOUT |
198                                         WDIOF_KEEPALIVEPING |
199                                         WDIOF_MAGICCLOSE,
200                 .firmware_version =     0,
201                 .identity =             "Software Watchdog",
202         };
203         switch (cmd) {
204                 default:
205                         return -ENOIOCTLCMD;
206                 case WDIOC_GETSUPPORT:
207                         return copy_to_user(argp, &ident,
208                                 sizeof(ident)) ? -EFAULT : 0;
209                 case WDIOC_GETSTATUS:
210                 case WDIOC_GETBOOTSTATUS:
211                         return put_user(0, p);
212                 case WDIOC_KEEPALIVE:
213                         softdog_keepalive();
214                         return 0;
215                 case WDIOC_SETTIMEOUT:
216                         if (get_user(new_margin, p))
217                                 return -EFAULT;
218                         if (softdog_set_heartbeat(new_margin))
219                                 return -EINVAL;
220                         softdog_keepalive();
221                         /* Fall */
222                 case WDIOC_GETTIMEOUT:
223                         return put_user(soft_margin, p);
224         }
225 }
226
227 /*
228  *      Notifier for system down
229  */
230
231 static int softdog_notify_sys(struct notifier_block *this, unsigned long code,
232         void *unused)
233 {
234         if(code==SYS_DOWN || code==SYS_HALT) {
235                 /* Turn the WDT off */
236                 softdog_stop();
237         }
238         return NOTIFY_DONE;
239 }
240
241 /*
242  *      Kernel Interfaces
243  */
244
245 static struct file_operations softdog_fops = {
246         .owner          = THIS_MODULE,
247         .llseek         = no_llseek,
248         .write          = softdog_write,
249         .ioctl          = softdog_ioctl,
250         .open           = softdog_open,
251         .release        = softdog_release,
252 };
253
254 static struct miscdevice softdog_miscdev = {
255         .minor          = WATCHDOG_MINOR,
256         .name           = "watchdog",
257         .fops           = &softdog_fops,
258 };
259
260 static struct notifier_block softdog_notifier = {
261         .notifier_call  = softdog_notify_sys,
262 };
263
264 static char banner[] __initdata = KERN_INFO "Software Watchdog Timer: 0.07 initialized. soft_noboot=%d soft_margin=%d sec (nowayout= %d)\n";
265
266 static int __init watchdog_init(void)
267 {
268         int ret;
269
270         /* Check that the soft_margin value is within it's range ; if not reset to the default */
271         if (softdog_set_heartbeat(soft_margin)) {
272                 softdog_set_heartbeat(TIMER_MARGIN);
273                 printk(KERN_INFO PFX "soft_margin value must be 0<soft_margin<65536, using %d\n",
274                         TIMER_MARGIN);
275         }
276
277         ret = register_reboot_notifier(&softdog_notifier);
278         if (ret) {
279                 printk (KERN_ERR PFX "cannot register reboot notifier (err=%d)\n",
280                         ret);
281                 return ret;
282         }
283
284         ret = misc_register(&softdog_miscdev);
285         if (ret) {
286                 printk (KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
287                         WATCHDOG_MINOR, ret);
288                 unregister_reboot_notifier(&softdog_notifier);
289                 return ret;
290         }
291
292         printk(banner, soft_noboot, soft_margin, nowayout);
293
294         return 0;
295 }
296
297 static void __exit watchdog_exit(void)
298 {
299         misc_deregister(&softdog_miscdev);
300         unregister_reboot_notifier(&softdog_notifier);
301 }
302
303 module_init(watchdog_init);
304 module_exit(watchdog_exit);
305
306 MODULE_AUTHOR("Alan Cox");
307 MODULE_DESCRIPTION("Software Watchdog Device Driver");
308 MODULE_LICENSE("GPL");
309 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);