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1/*
2 * watchdog_dev.c
3 *
4 * (c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>,
5 * All Rights Reserved.
6 *
7 * (c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>.
8 *
9 *
10 * This source code is part of the generic code that can be used
11 * by all the watchdog timer drivers.
12 *
13 * This part of the generic code takes care of the following
14 * misc device: /dev/watchdog.
15 *
16 * Based on source code of the following authors:
17 * Matt Domsch <Matt_Domsch@dell.com>,
18 * Rob Radez <rob@osinvestor.com>,
19 * Rusty Lynch <rusty@linux.co.intel.com>
20 * Satyam Sharma <satyam@infradead.org>
21 * Randy Dunlap <randy.dunlap@oracle.com>
22 *
23 * This program is free software; you can redistribute it and/or
24 * modify it under the terms of the GNU General Public License
25 * as published by the Free Software Foundation; either version
26 * 2 of the License, or (at your option) any later version.
27 *
28 * Neither Alan Cox, CymruNet Ltd., Wim Van Sebroeck nor Iguana vzw.
29 * admit liability nor provide warranty for any of this software.
30 * This material is provided "AS-IS" and at no charge.
31 */
32
33#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
34
35#include <linux/module.h> /* For module stuff/... */
36#include <linux/types.h> /* For standard types (like size_t) */
37#include <linux/errno.h> /* For the -ENODEV/... values */
38#include <linux/kernel.h> /* For printk/panic/... */
39#include <linux/fs.h> /* For file operations */
40#include <linux/watchdog.h> /* For watchdog specific items */
41#include <linux/miscdevice.h> /* For handling misc devices */
42#include <linux/init.h> /* For __init/__exit/... */
43#include <linux/uaccess.h> /* For copy_to_user/put_user/... */
44
45/* make sure we only register one /dev/watchdog device */
46static unsigned long watchdog_dev_busy;
47/* the watchdog device behind /dev/watchdog */
48static struct watchdog_device *wdd;
49
50/*
51 * watchdog_ping: ping the watchdog.
52 * @wddev: the watchdog device to ping
53 *
54 * If the watchdog has no own ping operation then it needs to be
55 * restarted via the start operation. This wrapper function does
56 * exactly that.
57 * We only ping when the watchdog device is running.
58 */
59
60static int watchdog_ping(struct watchdog_device *wddev)
61{
62 if (test_bit(WDOG_ACTIVE, &wddev->status)) {
63 if (wddev->ops->ping)
64 return wddev->ops->ping(wddev); /* ping the watchdog */
65 else
66 return wddev->ops->start(wddev); /* restart watchdog */
67 }
68 return 0;
69}
70
71/*
72 * watchdog_start: wrapper to start the watchdog.
73 * @wddev: the watchdog device to start
74 *
75 * Start the watchdog if it is not active and mark it active.
76 * This function returns zero on success or a negative errno code for
77 * failure.
78 */
79
80static int watchdog_start(struct watchdog_device *wddev)
81{
82 int err;
83
84 if (!test_bit(WDOG_ACTIVE, &wddev->status)) {
85 err = wddev->ops->start(wddev);
86 if (err < 0)
87 return err;
88
89 set_bit(WDOG_ACTIVE, &wddev->status);
90 }
91 return 0;
92}
93
94/*
95 * watchdog_stop: wrapper to stop the watchdog.
96 * @wddev: the watchdog device to stop
97 *
98 * Stop the watchdog if it is still active and unmark it active.
99 * This function returns zero on success or a negative errno code for
100 * failure.
101 * If the 'nowayout' feature was set, the watchdog cannot be stopped.
102 */
103
104static int watchdog_stop(struct watchdog_device *wddev)
105{
106 int err = -EBUSY;
107
108 if (test_bit(WDOG_NO_WAY_OUT, &wddev->status)) {
109 pr_info("%s: nowayout prevents watchdog to be stopped!\n",
110 wddev->info->identity);
111 return err;
112 }
113
114 if (test_bit(WDOG_ACTIVE, &wddev->status)) {
115 err = wddev->ops->stop(wddev);
116 if (err < 0)
117 return err;
118
119 clear_bit(WDOG_ACTIVE, &wddev->status);
120 }
121 return 0;
122}
123
124/*
125 * watchdog_write: writes to the watchdog.
126 * @file: file from VFS
127 * @data: user address of data
128 * @len: length of data
129 * @ppos: pointer to the file offset
130 *
131 * A write to a watchdog device is defined as a keepalive ping.
132 * Writing the magic 'V' sequence allows the next close to turn
133 * off the watchdog (if 'nowayout' is not set).
134 */
135
136static ssize_t watchdog_write(struct file *file, const char __user *data,
137 size_t len, loff_t *ppos)
138{
139 size_t i;
140 char c;
141
142 if (len == 0)
143 return 0;
144
145 /*
146 * Note: just in case someone wrote the magic character
147 * five months ago...
148 */
149 clear_bit(WDOG_ALLOW_RELEASE, &wdd->status);
150
151 /* scan to see whether or not we got the magic character */
152 for (i = 0; i != len; i++) {
153 if (get_user(c, data + i))
154 return -EFAULT;
155 if (c == 'V')
156 set_bit(WDOG_ALLOW_RELEASE, &wdd->status);
157 }
158
159 /* someone wrote to us, so we send the watchdog a keepalive ping */
160 watchdog_ping(wdd);
161
162 return len;
163}
164
165/*
166 * watchdog_ioctl: handle the different ioctl's for the watchdog device.
167 * @file: file handle to the device
168 * @cmd: watchdog command
169 * @arg: argument pointer
170 *
171 * The watchdog API defines a common set of functions for all watchdogs
172 * according to their available features.
173 */
174
175static long watchdog_ioctl(struct file *file, unsigned int cmd,
176 unsigned long arg)
177{
178 void __user *argp = (void __user *)arg;
179 int __user *p = argp;
180 unsigned int val;
181 int err;
182
183 if (wdd->ops->ioctl) {
184 err = wdd->ops->ioctl(wdd, cmd, arg);
185 if (err != -ENOIOCTLCMD)
186 return err;
187 }
188
189 switch (cmd) {
190 case WDIOC_GETSUPPORT:
191 return copy_to_user(argp, wdd->info,
192 sizeof(struct watchdog_info)) ? -EFAULT : 0;
193 case WDIOC_GETSTATUS:
194 val = wdd->ops->status ? wdd->ops->status(wdd) : 0;
195 return put_user(val, p);
196 case WDIOC_GETBOOTSTATUS:
197 return put_user(wdd->bootstatus, p);
198 case WDIOC_SETOPTIONS:
199 if (get_user(val, p))
200 return -EFAULT;
201 if (val & WDIOS_DISABLECARD) {
202 err = watchdog_stop(wdd);
203 if (err < 0)
204 return err;
205 }
206 if (val & WDIOS_ENABLECARD) {
207 err = watchdog_start(wdd);
208 if (err < 0)
209 return err;
210 }
211 return 0;
212 case WDIOC_KEEPALIVE:
213 if (!(wdd->info->options & WDIOF_KEEPALIVEPING))
214 return -EOPNOTSUPP;
215 watchdog_ping(wdd);
216 return 0;
217 case WDIOC_SETTIMEOUT:
218 if ((wdd->ops->set_timeout == NULL) ||
219 !(wdd->info->options & WDIOF_SETTIMEOUT))
220 return -EOPNOTSUPP;
221 if (get_user(val, p))
222 return -EFAULT;
223 if ((wdd->max_timeout != 0) &&
224 (val < wdd->min_timeout || val > wdd->max_timeout))
225 return -EINVAL;
226 err = wdd->ops->set_timeout(wdd, val);
227 if (err < 0)
228 return err;
229 wdd->timeout = val;
230 /* If the watchdog is active then we send a keepalive ping
231 * to make sure that the watchdog keep's running (and if
232 * possible that it takes the new timeout) */
233 watchdog_ping(wdd);
234 /* Fall */
235 case WDIOC_GETTIMEOUT:
236 /* timeout == 0 means that we don't know the timeout */
237 if (wdd->timeout == 0)
238 return -EOPNOTSUPP;
239 return put_user(wdd->timeout, p);
240 default:
241 return -ENOTTY;
242 }
243}
244
245/*
246 * watchdog_open: open the /dev/watchdog device.
247 * @inode: inode of device
248 * @file: file handle to device
249 *
250 * When the /dev/watchdog device gets opened, we start the watchdog.
251 * Watch out: the /dev/watchdog device is single open, so we make sure
252 * it can only be opened once.
253 */
254
255static int watchdog_open(struct inode *inode, struct file *file)
256{
257 int err = -EBUSY;
258
259 /* the watchdog is single open! */
260 if (test_and_set_bit(WDOG_DEV_OPEN, &wdd->status))
261 return -EBUSY;
262
263 /*
264 * If the /dev/watchdog device is open, we don't want the module
265 * to be unloaded.
266 */
267 if (!try_module_get(wdd->ops->owner))
268 goto out;
269
270 err = watchdog_start(wdd);
271 if (err < 0)
272 goto out_mod;
273
274 /* dev/watchdog is a virtual (and thus non-seekable) filesystem */
275 return nonseekable_open(inode, file);
276
277out_mod:
278 module_put(wdd->ops->owner);
279out:
280 clear_bit(WDOG_DEV_OPEN, &wdd->status);
281 return err;
282}
283
284/*
285 * watchdog_release: release the /dev/watchdog device.
286 * @inode: inode of device
287 * @file: file handle to device
288 *
289 * This is the code for when /dev/watchdog gets closed. We will only
290 * stop the watchdog when we have received the magic char (and nowayout
291 * was not set), else the watchdog will keep running.
292 */
293
294static int watchdog_release(struct inode *inode, struct file *file)
295{
296 int err = -EBUSY;
297
298 /*
299 * We only stop the watchdog if we received the magic character
300 * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
301 * watchdog_stop will fail.
302 */
303 if (test_and_clear_bit(WDOG_ALLOW_RELEASE, &wdd->status) ||
304 !(wdd->info->options & WDIOF_MAGICCLOSE))
305 err = watchdog_stop(wdd);
306
307 /* If the watchdog was not stopped, send a keepalive ping */
308 if (err < 0) {
309 pr_crit("%s: watchdog did not stop!\n", wdd->info->identity);
310 watchdog_ping(wdd);
311 }
312
313 /* Allow the owner module to be unloaded again */
314 module_put(wdd->ops->owner);
315
316 /* make sure that /dev/watchdog can be re-opened */
317 clear_bit(WDOG_DEV_OPEN, &wdd->status);
318
319 return 0;
320}
321
322static const struct file_operations watchdog_fops = {
323 .owner = THIS_MODULE,
324 .write = watchdog_write,
325 .unlocked_ioctl = watchdog_ioctl,
326 .open = watchdog_open,
327 .release = watchdog_release,
328};
329
330static struct miscdevice watchdog_miscdev = {
331 .minor = WATCHDOG_MINOR,
332 .name = "watchdog",
333 .fops = &watchdog_fops,
334};
335
336/*
337 * watchdog_dev_register:
338 * @watchdog: watchdog device
339 *
340 * Register a watchdog device as /dev/watchdog. /dev/watchdog
341 * is actually a miscdevice and thus we set it up like that.
342 */
343
344int watchdog_dev_register(struct watchdog_device *watchdog)
345{
346 int err;
347
348 /* Only one device can register for /dev/watchdog */
349 if (test_and_set_bit(0, &watchdog_dev_busy)) {
350 pr_err("only one watchdog can use /dev/watchdog.\n");
351 return -EBUSY;
352 }
353
354 wdd = watchdog;
355
356 err = misc_register(&watchdog_miscdev);
357 if (err != 0) {
358 pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",
359 watchdog->info->identity, WATCHDOG_MINOR, err);
360 goto out;
361 }
362
363 return 0;
364
365out:
366 wdd = NULL;
367 clear_bit(0, &watchdog_dev_busy);
368 return err;
369}
370
371/*
372 * watchdog_dev_unregister:
373 * @watchdog: watchdog device
374 *
375 * Deregister the /dev/watchdog device.
376 */
377
378int watchdog_dev_unregister(struct watchdog_device *watchdog)
379{
380 /* Check that a watchdog device was registered in the past */
381 if (!test_bit(0, &watchdog_dev_busy) || !wdd)
382 return -ENODEV;
383
384 /* We can only unregister the watchdog device that was registered */
385 if (watchdog != wdd) {
386 pr_err("%s: watchdog was not registered as /dev/watchdog.\n",
387 watchdog->info->identity);
388 return -ENODEV;
389 }
390
391 misc_deregister(&watchdog_miscdev);
392 wdd = NULL;
393 clear_bit(0, &watchdog_dev_busy);
394 return 0;
395}
1/*
2 * watchdog_dev.c
3 *
4 * (c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>,
5 * All Rights Reserved.
6 *
7 * (c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>.
8 *
9 *
10 * This source code is part of the generic code that can be used
11 * by all the watchdog timer drivers.
12 *
13 * This part of the generic code takes care of the following
14 * misc device: /dev/watchdog.
15 *
16 * Based on source code of the following authors:
17 * Matt Domsch <Matt_Domsch@dell.com>,
18 * Rob Radez <rob@osinvestor.com>,
19 * Rusty Lynch <rusty@linux.co.intel.com>
20 * Satyam Sharma <satyam@infradead.org>
21 * Randy Dunlap <randy.dunlap@oracle.com>
22 *
23 * This program is free software; you can redistribute it and/or
24 * modify it under the terms of the GNU General Public License
25 * as published by the Free Software Foundation; either version
26 * 2 of the License, or (at your option) any later version.
27 *
28 * Neither Alan Cox, CymruNet Ltd., Wim Van Sebroeck nor Iguana vzw.
29 * admit liability nor provide warranty for any of this software.
30 * This material is provided "AS-IS" and at no charge.
31 */
32
33#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
34
35#include <linux/cdev.h> /* For character device */
36#include <linux/errno.h> /* For the -ENODEV/... values */
37#include <linux/fs.h> /* For file operations */
38#include <linux/init.h> /* For __init/__exit/... */
39#include <linux/jiffies.h> /* For timeout functions */
40#include <linux/kernel.h> /* For printk/panic/... */
41#include <linux/kref.h> /* For data references */
42#include <linux/miscdevice.h> /* For handling misc devices */
43#include <linux/module.h> /* For module stuff/... */
44#include <linux/mutex.h> /* For mutexes */
45#include <linux/slab.h> /* For memory functions */
46#include <linux/types.h> /* For standard types (like size_t) */
47#include <linux/watchdog.h> /* For watchdog specific items */
48#include <linux/workqueue.h> /* For workqueue */
49#include <linux/uaccess.h> /* For copy_to_user/put_user/... */
50
51#include "watchdog_core.h"
52#include "watchdog_pretimeout.h"
53
54/*
55 * struct watchdog_core_data - watchdog core internal data
56 * @kref: Reference count.
57 * @cdev: The watchdog's Character device.
58 * @wdd: Pointer to watchdog device.
59 * @lock: Lock for watchdog core.
60 * @status: Watchdog core internal status bits.
61 */
62struct watchdog_core_data {
63 struct kref kref;
64 struct cdev cdev;
65 struct watchdog_device *wdd;
66 struct mutex lock;
67 unsigned long last_keepalive;
68 unsigned long last_hw_keepalive;
69 struct delayed_work work;
70 unsigned long status; /* Internal status bits */
71#define _WDOG_DEV_OPEN 0 /* Opened ? */
72#define _WDOG_ALLOW_RELEASE 1 /* Did we receive the magic char ? */
73#define _WDOG_KEEPALIVE 2 /* Did we receive a keepalive ? */
74};
75
76/* the dev_t structure to store the dynamically allocated watchdog devices */
77static dev_t watchdog_devt;
78/* Reference to watchdog device behind /dev/watchdog */
79static struct watchdog_core_data *old_wd_data;
80
81static struct workqueue_struct *watchdog_wq;
82
83static inline bool watchdog_need_worker(struct watchdog_device *wdd)
84{
85 /* All variables in milli-seconds */
86 unsigned int hm = wdd->max_hw_heartbeat_ms;
87 unsigned int t = wdd->timeout * 1000;
88
89 /*
90 * A worker to generate heartbeat requests is needed if all of the
91 * following conditions are true.
92 * - Userspace activated the watchdog.
93 * - The driver provided a value for the maximum hardware timeout, and
94 * thus is aware that the framework supports generating heartbeat
95 * requests.
96 * - Userspace requests a longer timeout than the hardware can handle.
97 *
98 * Alternatively, if userspace has not opened the watchdog
99 * device, we take care of feeding the watchdog if it is
100 * running.
101 */
102 return (hm && watchdog_active(wdd) && t > hm) ||
103 (t && !watchdog_active(wdd) && watchdog_hw_running(wdd));
104}
105
106static long watchdog_next_keepalive(struct watchdog_device *wdd)
107{
108 struct watchdog_core_data *wd_data = wdd->wd_data;
109 unsigned int timeout_ms = wdd->timeout * 1000;
110 unsigned long keepalive_interval;
111 unsigned long last_heartbeat;
112 unsigned long virt_timeout;
113 unsigned int hw_heartbeat_ms;
114
115 virt_timeout = wd_data->last_keepalive + msecs_to_jiffies(timeout_ms);
116 hw_heartbeat_ms = min_not_zero(timeout_ms, wdd->max_hw_heartbeat_ms);
117 keepalive_interval = msecs_to_jiffies(hw_heartbeat_ms / 2);
118
119 if (!watchdog_active(wdd))
120 return keepalive_interval;
121
122 /*
123 * To ensure that the watchdog times out wdd->timeout seconds
124 * after the most recent ping from userspace, the last
125 * worker ping has to come in hw_heartbeat_ms before this timeout.
126 */
127 last_heartbeat = virt_timeout - msecs_to_jiffies(hw_heartbeat_ms);
128 return min_t(long, last_heartbeat - jiffies, keepalive_interval);
129}
130
131static inline void watchdog_update_worker(struct watchdog_device *wdd)
132{
133 struct watchdog_core_data *wd_data = wdd->wd_data;
134
135 if (watchdog_need_worker(wdd)) {
136 long t = watchdog_next_keepalive(wdd);
137
138 if (t > 0)
139 mod_delayed_work(watchdog_wq, &wd_data->work, t);
140 } else {
141 cancel_delayed_work(&wd_data->work);
142 }
143}
144
145static int __watchdog_ping(struct watchdog_device *wdd)
146{
147 struct watchdog_core_data *wd_data = wdd->wd_data;
148 unsigned long earliest_keepalive = wd_data->last_hw_keepalive +
149 msecs_to_jiffies(wdd->min_hw_heartbeat_ms);
150 int err;
151
152 if (time_is_after_jiffies(earliest_keepalive)) {
153 mod_delayed_work(watchdog_wq, &wd_data->work,
154 earliest_keepalive - jiffies);
155 return 0;
156 }
157
158 wd_data->last_hw_keepalive = jiffies;
159
160 if (wdd->ops->ping)
161 err = wdd->ops->ping(wdd); /* ping the watchdog */
162 else
163 err = wdd->ops->start(wdd); /* restart watchdog */
164
165 watchdog_update_worker(wdd);
166
167 return err;
168}
169
170/*
171 * watchdog_ping: ping the watchdog.
172 * @wdd: the watchdog device to ping
173 *
174 * The caller must hold wd_data->lock.
175 *
176 * If the watchdog has no own ping operation then it needs to be
177 * restarted via the start operation. This wrapper function does
178 * exactly that.
179 * We only ping when the watchdog device is running.
180 */
181
182static int watchdog_ping(struct watchdog_device *wdd)
183{
184 struct watchdog_core_data *wd_data = wdd->wd_data;
185
186 if (!watchdog_active(wdd) && !watchdog_hw_running(wdd))
187 return 0;
188
189 set_bit(_WDOG_KEEPALIVE, &wd_data->status);
190
191 wd_data->last_keepalive = jiffies;
192 return __watchdog_ping(wdd);
193}
194
195static void watchdog_ping_work(struct work_struct *work)
196{
197 struct watchdog_core_data *wd_data;
198 struct watchdog_device *wdd;
199
200 wd_data = container_of(to_delayed_work(work), struct watchdog_core_data,
201 work);
202
203 mutex_lock(&wd_data->lock);
204 wdd = wd_data->wdd;
205 if (wdd && (watchdog_active(wdd) || watchdog_hw_running(wdd)))
206 __watchdog_ping(wdd);
207 mutex_unlock(&wd_data->lock);
208}
209
210/*
211 * watchdog_start: wrapper to start the watchdog.
212 * @wdd: the watchdog device to start
213 *
214 * The caller must hold wd_data->lock.
215 *
216 * Start the watchdog if it is not active and mark it active.
217 * This function returns zero on success or a negative errno code for
218 * failure.
219 */
220
221static int watchdog_start(struct watchdog_device *wdd)
222{
223 struct watchdog_core_data *wd_data = wdd->wd_data;
224 unsigned long started_at;
225 int err;
226
227 if (watchdog_active(wdd))
228 return 0;
229
230 set_bit(_WDOG_KEEPALIVE, &wd_data->status);
231
232 started_at = jiffies;
233 if (watchdog_hw_running(wdd) && wdd->ops->ping)
234 err = wdd->ops->ping(wdd);
235 else
236 err = wdd->ops->start(wdd);
237 if (err == 0) {
238 set_bit(WDOG_ACTIVE, &wdd->status);
239 wd_data->last_keepalive = started_at;
240 watchdog_update_worker(wdd);
241 }
242
243 return err;
244}
245
246/*
247 * watchdog_stop: wrapper to stop the watchdog.
248 * @wdd: the watchdog device to stop
249 *
250 * The caller must hold wd_data->lock.
251 *
252 * Stop the watchdog if it is still active and unmark it active.
253 * This function returns zero on success or a negative errno code for
254 * failure.
255 * If the 'nowayout' feature was set, the watchdog cannot be stopped.
256 */
257
258static int watchdog_stop(struct watchdog_device *wdd)
259{
260 int err = 0;
261
262 if (!watchdog_active(wdd))
263 return 0;
264
265 if (test_bit(WDOG_NO_WAY_OUT, &wdd->status)) {
266 pr_info("watchdog%d: nowayout prevents watchdog being stopped!\n",
267 wdd->id);
268 return -EBUSY;
269 }
270
271 if (wdd->ops->stop) {
272 clear_bit(WDOG_HW_RUNNING, &wdd->status);
273 err = wdd->ops->stop(wdd);
274 } else {
275 set_bit(WDOG_HW_RUNNING, &wdd->status);
276 }
277
278 if (err == 0) {
279 clear_bit(WDOG_ACTIVE, &wdd->status);
280 watchdog_update_worker(wdd);
281 }
282
283 return err;
284}
285
286/*
287 * watchdog_get_status: wrapper to get the watchdog status
288 * @wdd: the watchdog device to get the status from
289 *
290 * The caller must hold wd_data->lock.
291 *
292 * Get the watchdog's status flags.
293 */
294
295static unsigned int watchdog_get_status(struct watchdog_device *wdd)
296{
297 struct watchdog_core_data *wd_data = wdd->wd_data;
298 unsigned int status;
299
300 if (wdd->ops->status)
301 status = wdd->ops->status(wdd);
302 else
303 status = wdd->bootstatus & (WDIOF_CARDRESET |
304 WDIOF_OVERHEAT |
305 WDIOF_FANFAULT |
306 WDIOF_EXTERN1 |
307 WDIOF_EXTERN2 |
308 WDIOF_POWERUNDER |
309 WDIOF_POWEROVER);
310
311 if (test_bit(_WDOG_ALLOW_RELEASE, &wd_data->status))
312 status |= WDIOF_MAGICCLOSE;
313
314 if (test_and_clear_bit(_WDOG_KEEPALIVE, &wd_data->status))
315 status |= WDIOF_KEEPALIVEPING;
316
317 return status;
318}
319
320/*
321 * watchdog_set_timeout: set the watchdog timer timeout
322 * @wdd: the watchdog device to set the timeout for
323 * @timeout: timeout to set in seconds
324 *
325 * The caller must hold wd_data->lock.
326 */
327
328static int watchdog_set_timeout(struct watchdog_device *wdd,
329 unsigned int timeout)
330{
331 int err = 0;
332
333 if (!(wdd->info->options & WDIOF_SETTIMEOUT))
334 return -EOPNOTSUPP;
335
336 if (watchdog_timeout_invalid(wdd, timeout))
337 return -EINVAL;
338
339 if (wdd->ops->set_timeout) {
340 err = wdd->ops->set_timeout(wdd, timeout);
341 } else {
342 wdd->timeout = timeout;
343 /* Disable pretimeout if it doesn't fit the new timeout */
344 if (wdd->pretimeout >= wdd->timeout)
345 wdd->pretimeout = 0;
346 }
347
348 watchdog_update_worker(wdd);
349
350 return err;
351}
352
353/*
354 * watchdog_set_pretimeout: set the watchdog timer pretimeout
355 * @wdd: the watchdog device to set the timeout for
356 * @timeout: pretimeout to set in seconds
357 */
358
359static int watchdog_set_pretimeout(struct watchdog_device *wdd,
360 unsigned int timeout)
361{
362 int err = 0;
363
364 if (!(wdd->info->options & WDIOF_PRETIMEOUT))
365 return -EOPNOTSUPP;
366
367 if (watchdog_pretimeout_invalid(wdd, timeout))
368 return -EINVAL;
369
370 if (wdd->ops->set_pretimeout)
371 err = wdd->ops->set_pretimeout(wdd, timeout);
372 else
373 wdd->pretimeout = timeout;
374
375 return err;
376}
377
378/*
379 * watchdog_get_timeleft: wrapper to get the time left before a reboot
380 * @wdd: the watchdog device to get the remaining time from
381 * @timeleft: the time that's left
382 *
383 * The caller must hold wd_data->lock.
384 *
385 * Get the time before a watchdog will reboot (if not pinged).
386 */
387
388static int watchdog_get_timeleft(struct watchdog_device *wdd,
389 unsigned int *timeleft)
390{
391 *timeleft = 0;
392
393 if (!wdd->ops->get_timeleft)
394 return -EOPNOTSUPP;
395
396 *timeleft = wdd->ops->get_timeleft(wdd);
397
398 return 0;
399}
400
401#ifdef CONFIG_WATCHDOG_SYSFS
402static ssize_t nowayout_show(struct device *dev, struct device_attribute *attr,
403 char *buf)
404{
405 struct watchdog_device *wdd = dev_get_drvdata(dev);
406
407 return sprintf(buf, "%d\n", !!test_bit(WDOG_NO_WAY_OUT, &wdd->status));
408}
409static DEVICE_ATTR_RO(nowayout);
410
411static ssize_t status_show(struct device *dev, struct device_attribute *attr,
412 char *buf)
413{
414 struct watchdog_device *wdd = dev_get_drvdata(dev);
415 struct watchdog_core_data *wd_data = wdd->wd_data;
416 unsigned int status;
417
418 mutex_lock(&wd_data->lock);
419 status = watchdog_get_status(wdd);
420 mutex_unlock(&wd_data->lock);
421
422 return sprintf(buf, "0x%x\n", status);
423}
424static DEVICE_ATTR_RO(status);
425
426static ssize_t bootstatus_show(struct device *dev,
427 struct device_attribute *attr, char *buf)
428{
429 struct watchdog_device *wdd = dev_get_drvdata(dev);
430
431 return sprintf(buf, "%u\n", wdd->bootstatus);
432}
433static DEVICE_ATTR_RO(bootstatus);
434
435static ssize_t timeleft_show(struct device *dev, struct device_attribute *attr,
436 char *buf)
437{
438 struct watchdog_device *wdd = dev_get_drvdata(dev);
439 struct watchdog_core_data *wd_data = wdd->wd_data;
440 ssize_t status;
441 unsigned int val;
442
443 mutex_lock(&wd_data->lock);
444 status = watchdog_get_timeleft(wdd, &val);
445 mutex_unlock(&wd_data->lock);
446 if (!status)
447 status = sprintf(buf, "%u\n", val);
448
449 return status;
450}
451static DEVICE_ATTR_RO(timeleft);
452
453static ssize_t timeout_show(struct device *dev, struct device_attribute *attr,
454 char *buf)
455{
456 struct watchdog_device *wdd = dev_get_drvdata(dev);
457
458 return sprintf(buf, "%u\n", wdd->timeout);
459}
460static DEVICE_ATTR_RO(timeout);
461
462static ssize_t pretimeout_show(struct device *dev,
463 struct device_attribute *attr, char *buf)
464{
465 struct watchdog_device *wdd = dev_get_drvdata(dev);
466
467 return sprintf(buf, "%u\n", wdd->pretimeout);
468}
469static DEVICE_ATTR_RO(pretimeout);
470
471static ssize_t identity_show(struct device *dev, struct device_attribute *attr,
472 char *buf)
473{
474 struct watchdog_device *wdd = dev_get_drvdata(dev);
475
476 return sprintf(buf, "%s\n", wdd->info->identity);
477}
478static DEVICE_ATTR_RO(identity);
479
480static ssize_t state_show(struct device *dev, struct device_attribute *attr,
481 char *buf)
482{
483 struct watchdog_device *wdd = dev_get_drvdata(dev);
484
485 if (watchdog_active(wdd))
486 return sprintf(buf, "active\n");
487
488 return sprintf(buf, "inactive\n");
489}
490static DEVICE_ATTR_RO(state);
491
492static ssize_t pretimeout_available_governors_show(struct device *dev,
493 struct device_attribute *attr, char *buf)
494{
495 return watchdog_pretimeout_available_governors_get(buf);
496}
497static DEVICE_ATTR_RO(pretimeout_available_governors);
498
499static ssize_t pretimeout_governor_show(struct device *dev,
500 struct device_attribute *attr,
501 char *buf)
502{
503 struct watchdog_device *wdd = dev_get_drvdata(dev);
504
505 return watchdog_pretimeout_governor_get(wdd, buf);
506}
507
508static ssize_t pretimeout_governor_store(struct device *dev,
509 struct device_attribute *attr,
510 const char *buf, size_t count)
511{
512 struct watchdog_device *wdd = dev_get_drvdata(dev);
513 int ret = watchdog_pretimeout_governor_set(wdd, buf);
514
515 if (!ret)
516 ret = count;
517
518 return ret;
519}
520static DEVICE_ATTR_RW(pretimeout_governor);
521
522static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr,
523 int n)
524{
525 struct device *dev = container_of(kobj, struct device, kobj);
526 struct watchdog_device *wdd = dev_get_drvdata(dev);
527 umode_t mode = attr->mode;
528
529 if (attr == &dev_attr_timeleft.attr && !wdd->ops->get_timeleft)
530 mode = 0;
531 else if (attr == &dev_attr_pretimeout.attr &&
532 !(wdd->info->options & WDIOF_PRETIMEOUT))
533 mode = 0;
534 else if ((attr == &dev_attr_pretimeout_governor.attr ||
535 attr == &dev_attr_pretimeout_available_governors.attr) &&
536 (!(wdd->info->options & WDIOF_PRETIMEOUT) ||
537 !IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_GOV)))
538 mode = 0;
539
540 return mode;
541}
542static struct attribute *wdt_attrs[] = {
543 &dev_attr_state.attr,
544 &dev_attr_identity.attr,
545 &dev_attr_timeout.attr,
546 &dev_attr_pretimeout.attr,
547 &dev_attr_timeleft.attr,
548 &dev_attr_bootstatus.attr,
549 &dev_attr_status.attr,
550 &dev_attr_nowayout.attr,
551 &dev_attr_pretimeout_governor.attr,
552 &dev_attr_pretimeout_available_governors.attr,
553 NULL,
554};
555
556static const struct attribute_group wdt_group = {
557 .attrs = wdt_attrs,
558 .is_visible = wdt_is_visible,
559};
560__ATTRIBUTE_GROUPS(wdt);
561#else
562#define wdt_groups NULL
563#endif
564
565/*
566 * watchdog_ioctl_op: call the watchdog drivers ioctl op if defined
567 * @wdd: the watchdog device to do the ioctl on
568 * @cmd: watchdog command
569 * @arg: argument pointer
570 *
571 * The caller must hold wd_data->lock.
572 */
573
574static int watchdog_ioctl_op(struct watchdog_device *wdd, unsigned int cmd,
575 unsigned long arg)
576{
577 if (!wdd->ops->ioctl)
578 return -ENOIOCTLCMD;
579
580 return wdd->ops->ioctl(wdd, cmd, arg);
581}
582
583/*
584 * watchdog_write: writes to the watchdog.
585 * @file: file from VFS
586 * @data: user address of data
587 * @len: length of data
588 * @ppos: pointer to the file offset
589 *
590 * A write to a watchdog device is defined as a keepalive ping.
591 * Writing the magic 'V' sequence allows the next close to turn
592 * off the watchdog (if 'nowayout' is not set).
593 */
594
595static ssize_t watchdog_write(struct file *file, const char __user *data,
596 size_t len, loff_t *ppos)
597{
598 struct watchdog_core_data *wd_data = file->private_data;
599 struct watchdog_device *wdd;
600 int err;
601 size_t i;
602 char c;
603
604 if (len == 0)
605 return 0;
606
607 /*
608 * Note: just in case someone wrote the magic character
609 * five months ago...
610 */
611 clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
612
613 /* scan to see whether or not we got the magic character */
614 for (i = 0; i != len; i++) {
615 if (get_user(c, data + i))
616 return -EFAULT;
617 if (c == 'V')
618 set_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
619 }
620
621 /* someone wrote to us, so we send the watchdog a keepalive ping */
622
623 err = -ENODEV;
624 mutex_lock(&wd_data->lock);
625 wdd = wd_data->wdd;
626 if (wdd)
627 err = watchdog_ping(wdd);
628 mutex_unlock(&wd_data->lock);
629
630 if (err < 0)
631 return err;
632
633 return len;
634}
635
636/*
637 * watchdog_ioctl: handle the different ioctl's for the watchdog device.
638 * @file: file handle to the device
639 * @cmd: watchdog command
640 * @arg: argument pointer
641 *
642 * The watchdog API defines a common set of functions for all watchdogs
643 * according to their available features.
644 */
645
646static long watchdog_ioctl(struct file *file, unsigned int cmd,
647 unsigned long arg)
648{
649 struct watchdog_core_data *wd_data = file->private_data;
650 void __user *argp = (void __user *)arg;
651 struct watchdog_device *wdd;
652 int __user *p = argp;
653 unsigned int val;
654 int err;
655
656 mutex_lock(&wd_data->lock);
657
658 wdd = wd_data->wdd;
659 if (!wdd) {
660 err = -ENODEV;
661 goto out_ioctl;
662 }
663
664 err = watchdog_ioctl_op(wdd, cmd, arg);
665 if (err != -ENOIOCTLCMD)
666 goto out_ioctl;
667
668 switch (cmd) {
669 case WDIOC_GETSUPPORT:
670 err = copy_to_user(argp, wdd->info,
671 sizeof(struct watchdog_info)) ? -EFAULT : 0;
672 break;
673 case WDIOC_GETSTATUS:
674 val = watchdog_get_status(wdd);
675 err = put_user(val, p);
676 break;
677 case WDIOC_GETBOOTSTATUS:
678 err = put_user(wdd->bootstatus, p);
679 break;
680 case WDIOC_SETOPTIONS:
681 if (get_user(val, p)) {
682 err = -EFAULT;
683 break;
684 }
685 if (val & WDIOS_DISABLECARD) {
686 err = watchdog_stop(wdd);
687 if (err < 0)
688 break;
689 }
690 if (val & WDIOS_ENABLECARD)
691 err = watchdog_start(wdd);
692 break;
693 case WDIOC_KEEPALIVE:
694 if (!(wdd->info->options & WDIOF_KEEPALIVEPING)) {
695 err = -EOPNOTSUPP;
696 break;
697 }
698 err = watchdog_ping(wdd);
699 break;
700 case WDIOC_SETTIMEOUT:
701 if (get_user(val, p)) {
702 err = -EFAULT;
703 break;
704 }
705 err = watchdog_set_timeout(wdd, val);
706 if (err < 0)
707 break;
708 /* If the watchdog is active then we send a keepalive ping
709 * to make sure that the watchdog keep's running (and if
710 * possible that it takes the new timeout) */
711 err = watchdog_ping(wdd);
712 if (err < 0)
713 break;
714 /* Fall */
715 case WDIOC_GETTIMEOUT:
716 /* timeout == 0 means that we don't know the timeout */
717 if (wdd->timeout == 0) {
718 err = -EOPNOTSUPP;
719 break;
720 }
721 err = put_user(wdd->timeout, p);
722 break;
723 case WDIOC_GETTIMELEFT:
724 err = watchdog_get_timeleft(wdd, &val);
725 if (err < 0)
726 break;
727 err = put_user(val, p);
728 break;
729 case WDIOC_SETPRETIMEOUT:
730 if (get_user(val, p)) {
731 err = -EFAULT;
732 break;
733 }
734 err = watchdog_set_pretimeout(wdd, val);
735 break;
736 case WDIOC_GETPRETIMEOUT:
737 err = put_user(wdd->pretimeout, p);
738 break;
739 default:
740 err = -ENOTTY;
741 break;
742 }
743
744out_ioctl:
745 mutex_unlock(&wd_data->lock);
746 return err;
747}
748
749/*
750 * watchdog_open: open the /dev/watchdog* devices.
751 * @inode: inode of device
752 * @file: file handle to device
753 *
754 * When the /dev/watchdog* device gets opened, we start the watchdog.
755 * Watch out: the /dev/watchdog device is single open, so we make sure
756 * it can only be opened once.
757 */
758
759static int watchdog_open(struct inode *inode, struct file *file)
760{
761 struct watchdog_core_data *wd_data;
762 struct watchdog_device *wdd;
763 int err;
764
765 /* Get the corresponding watchdog device */
766 if (imajor(inode) == MISC_MAJOR)
767 wd_data = old_wd_data;
768 else
769 wd_data = container_of(inode->i_cdev, struct watchdog_core_data,
770 cdev);
771
772 /* the watchdog is single open! */
773 if (test_and_set_bit(_WDOG_DEV_OPEN, &wd_data->status))
774 return -EBUSY;
775
776 wdd = wd_data->wdd;
777
778 /*
779 * If the /dev/watchdog device is open, we don't want the module
780 * to be unloaded.
781 */
782 if (!watchdog_hw_running(wdd) && !try_module_get(wdd->ops->owner)) {
783 err = -EBUSY;
784 goto out_clear;
785 }
786
787 err = watchdog_start(wdd);
788 if (err < 0)
789 goto out_mod;
790
791 file->private_data = wd_data;
792
793 if (!watchdog_hw_running(wdd))
794 kref_get(&wd_data->kref);
795
796 /* dev/watchdog is a virtual (and thus non-seekable) filesystem */
797 return nonseekable_open(inode, file);
798
799out_mod:
800 module_put(wd_data->wdd->ops->owner);
801out_clear:
802 clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
803 return err;
804}
805
806static void watchdog_core_data_release(struct kref *kref)
807{
808 struct watchdog_core_data *wd_data;
809
810 wd_data = container_of(kref, struct watchdog_core_data, kref);
811
812 kfree(wd_data);
813}
814
815/*
816 * watchdog_release: release the watchdog device.
817 * @inode: inode of device
818 * @file: file handle to device
819 *
820 * This is the code for when /dev/watchdog gets closed. We will only
821 * stop the watchdog when we have received the magic char (and nowayout
822 * was not set), else the watchdog will keep running.
823 */
824
825static int watchdog_release(struct inode *inode, struct file *file)
826{
827 struct watchdog_core_data *wd_data = file->private_data;
828 struct watchdog_device *wdd;
829 int err = -EBUSY;
830 bool running;
831
832 mutex_lock(&wd_data->lock);
833
834 wdd = wd_data->wdd;
835 if (!wdd)
836 goto done;
837
838 /*
839 * We only stop the watchdog if we received the magic character
840 * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
841 * watchdog_stop will fail.
842 */
843 if (!test_bit(WDOG_ACTIVE, &wdd->status))
844 err = 0;
845 else if (test_and_clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status) ||
846 !(wdd->info->options & WDIOF_MAGICCLOSE))
847 err = watchdog_stop(wdd);
848
849 /* If the watchdog was not stopped, send a keepalive ping */
850 if (err < 0) {
851 pr_crit("watchdog%d: watchdog did not stop!\n", wdd->id);
852 watchdog_ping(wdd);
853 }
854
855 watchdog_update_worker(wdd);
856
857 /* make sure that /dev/watchdog can be re-opened */
858 clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
859
860done:
861 running = wdd && watchdog_hw_running(wdd);
862 mutex_unlock(&wd_data->lock);
863 /*
864 * Allow the owner module to be unloaded again unless the watchdog
865 * is still running. If the watchdog is still running, it can not
866 * be stopped, and its driver must not be unloaded.
867 */
868 if (!running) {
869 module_put(wd_data->cdev.owner);
870 kref_put(&wd_data->kref, watchdog_core_data_release);
871 }
872 return 0;
873}
874
875static const struct file_operations watchdog_fops = {
876 .owner = THIS_MODULE,
877 .write = watchdog_write,
878 .unlocked_ioctl = watchdog_ioctl,
879 .open = watchdog_open,
880 .release = watchdog_release,
881};
882
883static struct miscdevice watchdog_miscdev = {
884 .minor = WATCHDOG_MINOR,
885 .name = "watchdog",
886 .fops = &watchdog_fops,
887};
888
889/*
890 * watchdog_cdev_register: register watchdog character device
891 * @wdd: watchdog device
892 * @devno: character device number
893 *
894 * Register a watchdog character device including handling the legacy
895 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
896 * thus we set it up like that.
897 */
898
899static int watchdog_cdev_register(struct watchdog_device *wdd, dev_t devno)
900{
901 struct watchdog_core_data *wd_data;
902 int err;
903
904 wd_data = kzalloc(sizeof(struct watchdog_core_data), GFP_KERNEL);
905 if (!wd_data)
906 return -ENOMEM;
907 kref_init(&wd_data->kref);
908 mutex_init(&wd_data->lock);
909
910 wd_data->wdd = wdd;
911 wdd->wd_data = wd_data;
912
913 if (!watchdog_wq)
914 return -ENODEV;
915
916 INIT_DELAYED_WORK(&wd_data->work, watchdog_ping_work);
917
918 if (wdd->id == 0) {
919 old_wd_data = wd_data;
920 watchdog_miscdev.parent = wdd->parent;
921 err = misc_register(&watchdog_miscdev);
922 if (err != 0) {
923 pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",
924 wdd->info->identity, WATCHDOG_MINOR, err);
925 if (err == -EBUSY)
926 pr_err("%s: a legacy watchdog module is probably present.\n",
927 wdd->info->identity);
928 old_wd_data = NULL;
929 kfree(wd_data);
930 return err;
931 }
932 }
933
934 /* Fill in the data structures */
935 cdev_init(&wd_data->cdev, &watchdog_fops);
936 wd_data->cdev.owner = wdd->ops->owner;
937
938 /* Add the device */
939 err = cdev_add(&wd_data->cdev, devno, 1);
940 if (err) {
941 pr_err("watchdog%d unable to add device %d:%d\n",
942 wdd->id, MAJOR(watchdog_devt), wdd->id);
943 if (wdd->id == 0) {
944 misc_deregister(&watchdog_miscdev);
945 old_wd_data = NULL;
946 kref_put(&wd_data->kref, watchdog_core_data_release);
947 }
948 return err;
949 }
950
951 /* Record time of most recent heartbeat as 'just before now'. */
952 wd_data->last_hw_keepalive = jiffies - 1;
953
954 /*
955 * If the watchdog is running, prevent its driver from being unloaded,
956 * and schedule an immediate ping.
957 */
958 if (watchdog_hw_running(wdd)) {
959 __module_get(wdd->ops->owner);
960 kref_get(&wd_data->kref);
961 queue_delayed_work(watchdog_wq, &wd_data->work, 0);
962 }
963
964 return 0;
965}
966
967/*
968 * watchdog_cdev_unregister: unregister watchdog character device
969 * @watchdog: watchdog device
970 *
971 * Unregister watchdog character device and if needed the legacy
972 * /dev/watchdog device.
973 */
974
975static void watchdog_cdev_unregister(struct watchdog_device *wdd)
976{
977 struct watchdog_core_data *wd_data = wdd->wd_data;
978
979 cdev_del(&wd_data->cdev);
980 if (wdd->id == 0) {
981 misc_deregister(&watchdog_miscdev);
982 old_wd_data = NULL;
983 }
984
985 mutex_lock(&wd_data->lock);
986 wd_data->wdd = NULL;
987 wdd->wd_data = NULL;
988 mutex_unlock(&wd_data->lock);
989
990 cancel_delayed_work_sync(&wd_data->work);
991
992 kref_put(&wd_data->kref, watchdog_core_data_release);
993}
994
995static struct class watchdog_class = {
996 .name = "watchdog",
997 .owner = THIS_MODULE,
998 .dev_groups = wdt_groups,
999};
1000
1001/*
1002 * watchdog_dev_register: register a watchdog device
1003 * @wdd: watchdog device
1004 *
1005 * Register a watchdog device including handling the legacy
1006 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
1007 * thus we set it up like that.
1008 */
1009
1010int watchdog_dev_register(struct watchdog_device *wdd)
1011{
1012 struct device *dev;
1013 dev_t devno;
1014 int ret;
1015
1016 devno = MKDEV(MAJOR(watchdog_devt), wdd->id);
1017
1018 ret = watchdog_cdev_register(wdd, devno);
1019 if (ret)
1020 return ret;
1021
1022 dev = device_create_with_groups(&watchdog_class, wdd->parent,
1023 devno, wdd, wdd->groups,
1024 "watchdog%d", wdd->id);
1025 if (IS_ERR(dev)) {
1026 watchdog_cdev_unregister(wdd);
1027 return PTR_ERR(dev);
1028 }
1029
1030 ret = watchdog_register_pretimeout(wdd);
1031 if (ret) {
1032 device_destroy(&watchdog_class, devno);
1033 watchdog_cdev_unregister(wdd);
1034 }
1035
1036 return ret;
1037}
1038
1039/*
1040 * watchdog_dev_unregister: unregister a watchdog device
1041 * @watchdog: watchdog device
1042 *
1043 * Unregister watchdog device and if needed the legacy
1044 * /dev/watchdog device.
1045 */
1046
1047void watchdog_dev_unregister(struct watchdog_device *wdd)
1048{
1049 watchdog_unregister_pretimeout(wdd);
1050 device_destroy(&watchdog_class, wdd->wd_data->cdev.dev);
1051 watchdog_cdev_unregister(wdd);
1052}
1053
1054/*
1055 * watchdog_dev_init: init dev part of watchdog core
1056 *
1057 * Allocate a range of chardev nodes to use for watchdog devices
1058 */
1059
1060int __init watchdog_dev_init(void)
1061{
1062 int err;
1063
1064 watchdog_wq = alloc_workqueue("watchdogd",
1065 WQ_HIGHPRI | WQ_MEM_RECLAIM, 0);
1066 if (!watchdog_wq) {
1067 pr_err("Failed to create watchdog workqueue\n");
1068 return -ENOMEM;
1069 }
1070
1071 err = class_register(&watchdog_class);
1072 if (err < 0) {
1073 pr_err("couldn't register class\n");
1074 goto err_register;
1075 }
1076
1077 err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");
1078 if (err < 0) {
1079 pr_err("watchdog: unable to allocate char dev region\n");
1080 goto err_alloc;
1081 }
1082
1083 return 0;
1084
1085err_alloc:
1086 class_unregister(&watchdog_class);
1087err_register:
1088 destroy_workqueue(watchdog_wq);
1089 return err;
1090}
1091
1092/*
1093 * watchdog_dev_exit: exit dev part of watchdog core
1094 *
1095 * Release the range of chardev nodes used for watchdog devices
1096 */
1097
1098void __exit watchdog_dev_exit(void)
1099{
1100 unregister_chrdev_region(watchdog_devt, MAX_DOGS);
1101 class_unregister(&watchdog_class);
1102 destroy_workqueue(watchdog_wq);
1103}