Commit | Line | Data |
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1107ba88 AZ |
1 | /* |
2 | * Driver giving user-space access to the kernel's xenbus connection | |
3 | * to xenstore. | |
4 | * | |
5 | * Copyright (c) 2005, Christian Limpach | |
6 | * Copyright (c) 2005, Rusty Russell, IBM Corporation | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or | |
9 | * modify it under the terms of the GNU General Public License version 2 | |
10 | * as published by the Free Software Foundation; or, when distributed | |
11 | * separately from the Linux kernel or incorporated into other | |
12 | * software packages, subject to the following license: | |
13 | * | |
14 | * Permission is hereby granted, free of charge, to any person obtaining a copy | |
15 | * of this source file (the "Software"), to deal in the Software without | |
16 | * restriction, including without limitation the rights to use, copy, modify, | |
17 | * merge, publish, distribute, sublicense, and/or sell copies of the Software, | |
18 | * and to permit persons to whom the Software is furnished to do so, subject to | |
19 | * the following conditions: | |
20 | * | |
21 | * The above copyright notice and this permission notice shall be included in | |
22 | * all copies or substantial portions of the Software. | |
23 | * | |
24 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | |
25 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | |
26 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | |
27 | * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | |
28 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING | |
29 | * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS | |
30 | * IN THE SOFTWARE. | |
31 | * | |
32 | * Changes: | |
33 | * 2008-10-07 Alex Zeffertt Replaced /proc/xen/xenbus with xenfs filesystem | |
34 | * and /proc/xen compatibility mount point. | |
35 | * Turned xenfs into a loadable module. | |
36 | */ | |
37 | ||
38 | #include <linux/kernel.h> | |
39 | #include <linux/errno.h> | |
40 | #include <linux/uio.h> | |
41 | #include <linux/notifier.h> | |
42 | #include <linux/wait.h> | |
43 | #include <linux/fs.h> | |
44 | #include <linux/poll.h> | |
45 | #include <linux/mutex.h> | |
a99bbaf5 | 46 | #include <linux/sched.h> |
1107ba88 AZ |
47 | #include <linux/spinlock.h> |
48 | #include <linux/mount.h> | |
49 | #include <linux/pagemap.h> | |
50 | #include <linux/uaccess.h> | |
51 | #include <linux/init.h> | |
52 | #include <linux/namei.h> | |
53 | #include <linux/string.h> | |
5a0e3ad6 | 54 | #include <linux/slab.h> |
2fb3683e BB |
55 | #include <linux/miscdevice.h> |
56 | #include <linux/module.h> | |
1107ba88 | 57 | |
2fb3683e | 58 | #include "xenbus_comms.h" |
1107ba88 AZ |
59 | |
60 | #include <xen/xenbus.h> | |
61 | #include <asm/xen/hypervisor.h> | |
62 | ||
2fb3683e BB |
63 | MODULE_LICENSE("GPL"); |
64 | ||
1107ba88 AZ |
65 | /* |
66 | * An element of a list of outstanding transactions, for which we're | |
67 | * still waiting a reply. | |
68 | */ | |
69 | struct xenbus_transaction_holder { | |
70 | struct list_head list; | |
71 | struct xenbus_transaction handle; | |
72 | }; | |
73 | ||
74 | /* | |
75 | * A buffer of data on the queue. | |
76 | */ | |
77 | struct read_buffer { | |
78 | struct list_head list; | |
79 | unsigned int cons; | |
80 | unsigned int len; | |
81 | char msg[]; | |
82 | }; | |
83 | ||
84 | struct xenbus_file_priv { | |
85 | /* | |
86 | * msgbuffer_mutex is held while partial requests are built up | |
87 | * and complete requests are acted on. It therefore protects | |
88 | * the "transactions" and "watches" lists, and the partial | |
89 | * request length and buffer. | |
90 | * | |
91 | * reply_mutex protects the reply being built up to return to | |
92 | * usermode. It nests inside msgbuffer_mutex but may be held | |
93 | * alone during a watch callback. | |
94 | */ | |
95 | struct mutex msgbuffer_mutex; | |
96 | ||
97 | /* In-progress transactions */ | |
98 | struct list_head transactions; | |
99 | ||
100 | /* Active watches. */ | |
101 | struct list_head watches; | |
102 | ||
103 | /* Partial request. */ | |
104 | unsigned int len; | |
105 | union { | |
106 | struct xsd_sockmsg msg; | |
107 | char buffer[PAGE_SIZE]; | |
108 | } u; | |
109 | ||
110 | /* Response queue. */ | |
111 | struct mutex reply_mutex; | |
112 | struct list_head read_buffers; | |
113 | wait_queue_head_t read_waitq; | |
114 | ||
115 | }; | |
116 | ||
117 | /* Read out any raw xenbus messages queued up. */ | |
118 | static ssize_t xenbus_file_read(struct file *filp, | |
119 | char __user *ubuf, | |
120 | size_t len, loff_t *ppos) | |
121 | { | |
122 | struct xenbus_file_priv *u = filp->private_data; | |
123 | struct read_buffer *rb; | |
124 | unsigned i; | |
125 | int ret; | |
126 | ||
127 | mutex_lock(&u->reply_mutex); | |
7808121b | 128 | again: |
1107ba88 AZ |
129 | while (list_empty(&u->read_buffers)) { |
130 | mutex_unlock(&u->reply_mutex); | |
6280f190 PB |
131 | if (filp->f_flags & O_NONBLOCK) |
132 | return -EAGAIN; | |
133 | ||
1107ba88 AZ |
134 | ret = wait_event_interruptible(u->read_waitq, |
135 | !list_empty(&u->read_buffers)); | |
136 | if (ret) | |
137 | return ret; | |
138 | mutex_lock(&u->reply_mutex); | |
139 | } | |
140 | ||
141 | rb = list_entry(u->read_buffers.next, struct read_buffer, list); | |
142 | i = 0; | |
143 | while (i < len) { | |
144 | unsigned sz = min((unsigned)len - i, rb->len - rb->cons); | |
145 | ||
146 | ret = copy_to_user(ubuf + i, &rb->msg[rb->cons], sz); | |
147 | ||
148 | i += sz - ret; | |
149 | rb->cons += sz - ret; | |
150 | ||
fb27cfbc | 151 | if (ret != 0) { |
1107ba88 AZ |
152 | if (i == 0) |
153 | i = -EFAULT; | |
154 | goto out; | |
155 | } | |
156 | ||
157 | /* Clear out buffer if it has been consumed */ | |
158 | if (rb->cons == rb->len) { | |
159 | list_del(&rb->list); | |
160 | kfree(rb); | |
161 | if (list_empty(&u->read_buffers)) | |
162 | break; | |
163 | rb = list_entry(u->read_buffers.next, | |
164 | struct read_buffer, list); | |
165 | } | |
166 | } | |
7808121b DDG |
167 | if (i == 0) |
168 | goto again; | |
1107ba88 AZ |
169 | |
170 | out: | |
171 | mutex_unlock(&u->reply_mutex); | |
172 | return i; | |
173 | } | |
174 | ||
175 | /* | |
176 | * Add a buffer to the queue. Caller must hold the appropriate lock | |
177 | * if the queue is not local. (Commonly the caller will build up | |
178 | * multiple queued buffers on a temporary local list, and then add it | |
179 | * to the appropriate list under lock once all the buffers have een | |
180 | * successfully allocated.) | |
181 | */ | |
182 | static int queue_reply(struct list_head *queue, const void *data, size_t len) | |
183 | { | |
184 | struct read_buffer *rb; | |
185 | ||
186 | if (len == 0) | |
187 | return 0; | |
188 | ||
189 | rb = kmalloc(sizeof(*rb) + len, GFP_KERNEL); | |
190 | if (rb == NULL) | |
191 | return -ENOMEM; | |
192 | ||
193 | rb->cons = 0; | |
194 | rb->len = len; | |
195 | ||
196 | memcpy(rb->msg, data, len); | |
197 | ||
198 | list_add_tail(&rb->list, queue); | |
199 | return 0; | |
200 | } | |
201 | ||
202 | /* | |
203 | * Free all the read_buffer s on a list. | |
204 | * Caller must have sole reference to list. | |
205 | */ | |
206 | static void queue_cleanup(struct list_head *list) | |
207 | { | |
208 | struct read_buffer *rb; | |
209 | ||
210 | while (!list_empty(list)) { | |
211 | rb = list_entry(list->next, struct read_buffer, list); | |
212 | list_del(list->next); | |
213 | kfree(rb); | |
214 | } | |
215 | } | |
216 | ||
217 | struct watch_adapter { | |
218 | struct list_head list; | |
219 | struct xenbus_watch watch; | |
220 | struct xenbus_file_priv *dev_data; | |
221 | char *token; | |
222 | }; | |
223 | ||
224 | static void free_watch_adapter(struct watch_adapter *watch) | |
225 | { | |
226 | kfree(watch->watch.node); | |
227 | kfree(watch->token); | |
228 | kfree(watch); | |
229 | } | |
230 | ||
231 | static struct watch_adapter *alloc_watch_adapter(const char *path, | |
232 | const char *token) | |
233 | { | |
234 | struct watch_adapter *watch; | |
235 | ||
236 | watch = kzalloc(sizeof(*watch), GFP_KERNEL); | |
237 | if (watch == NULL) | |
238 | goto out_fail; | |
239 | ||
240 | watch->watch.node = kstrdup(path, GFP_KERNEL); | |
241 | if (watch->watch.node == NULL) | |
242 | goto out_free; | |
243 | ||
244 | watch->token = kstrdup(token, GFP_KERNEL); | |
245 | if (watch->token == NULL) | |
246 | goto out_free; | |
247 | ||
248 | return watch; | |
249 | ||
250 | out_free: | |
251 | free_watch_adapter(watch); | |
252 | ||
253 | out_fail: | |
254 | return NULL; | |
255 | } | |
256 | ||
257 | static void watch_fired(struct xenbus_watch *watch, | |
258 | const char **vec, | |
259 | unsigned int len) | |
260 | { | |
261 | struct watch_adapter *adap; | |
262 | struct xsd_sockmsg hdr; | |
263 | const char *path, *token; | |
264 | int path_len, tok_len, body_len, data_len = 0; | |
265 | int ret; | |
266 | LIST_HEAD(staging_q); | |
267 | ||
268 | adap = container_of(watch, struct watch_adapter, watch); | |
269 | ||
270 | path = vec[XS_WATCH_PATH]; | |
271 | token = adap->token; | |
272 | ||
273 | path_len = strlen(path) + 1; | |
274 | tok_len = strlen(token) + 1; | |
275 | if (len > 2) | |
276 | data_len = vec[len] - vec[2] + 1; | |
277 | body_len = path_len + tok_len + data_len; | |
278 | ||
279 | hdr.type = XS_WATCH_EVENT; | |
280 | hdr.len = body_len; | |
281 | ||
282 | mutex_lock(&adap->dev_data->reply_mutex); | |
283 | ||
284 | ret = queue_reply(&staging_q, &hdr, sizeof(hdr)); | |
285 | if (!ret) | |
286 | ret = queue_reply(&staging_q, path, path_len); | |
287 | if (!ret) | |
288 | ret = queue_reply(&staging_q, token, tok_len); | |
289 | if (!ret && len > 2) | |
290 | ret = queue_reply(&staging_q, vec[2], data_len); | |
291 | ||
292 | if (!ret) { | |
293 | /* success: pass reply list onto watcher */ | |
294 | list_splice_tail(&staging_q, &adap->dev_data->read_buffers); | |
295 | wake_up(&adap->dev_data->read_waitq); | |
296 | } else | |
297 | queue_cleanup(&staging_q); | |
298 | ||
299 | mutex_unlock(&adap->dev_data->reply_mutex); | |
300 | } | |
301 | ||
302 | static int xenbus_write_transaction(unsigned msg_type, | |
303 | struct xenbus_file_priv *u) | |
304 | { | |
e88a0faa | 305 | int rc; |
1107ba88 AZ |
306 | void *reply; |
307 | struct xenbus_transaction_holder *trans = NULL; | |
308 | LIST_HEAD(staging_q); | |
309 | ||
310 | if (msg_type == XS_TRANSACTION_START) { | |
311 | trans = kmalloc(sizeof(*trans), GFP_KERNEL); | |
312 | if (!trans) { | |
313 | rc = -ENOMEM; | |
314 | goto out; | |
315 | } | |
316 | } | |
317 | ||
318 | reply = xenbus_dev_request_and_reply(&u->u.msg); | |
319 | if (IS_ERR(reply)) { | |
320 | kfree(trans); | |
321 | rc = PTR_ERR(reply); | |
322 | goto out; | |
323 | } | |
324 | ||
325 | if (msg_type == XS_TRANSACTION_START) { | |
326 | trans->handle.id = simple_strtoul(reply, NULL, 0); | |
327 | ||
328 | list_add(&trans->list, &u->transactions); | |
329 | } else if (msg_type == XS_TRANSACTION_END) { | |
330 | list_for_each_entry(trans, &u->transactions, list) | |
331 | if (trans->handle.id == u->u.msg.tx_id) | |
332 | break; | |
333 | BUG_ON(&trans->list == &u->transactions); | |
334 | list_del(&trans->list); | |
335 | ||
336 | kfree(trans); | |
337 | } | |
338 | ||
339 | mutex_lock(&u->reply_mutex); | |
e88a0faa IC |
340 | rc = queue_reply(&staging_q, &u->u.msg, sizeof(u->u.msg)); |
341 | if (!rc) | |
342 | rc = queue_reply(&staging_q, reply, u->u.msg.len); | |
343 | if (!rc) { | |
1107ba88 AZ |
344 | list_splice_tail(&staging_q, &u->read_buffers); |
345 | wake_up(&u->read_waitq); | |
346 | } else { | |
347 | queue_cleanup(&staging_q); | |
1107ba88 AZ |
348 | } |
349 | mutex_unlock(&u->reply_mutex); | |
350 | ||
351 | kfree(reply); | |
352 | ||
353 | out: | |
354 | return rc; | |
355 | } | |
356 | ||
357 | static int xenbus_write_watch(unsigned msg_type, struct xenbus_file_priv *u) | |
358 | { | |
359 | struct watch_adapter *watch, *tmp_watch; | |
360 | char *path, *token; | |
361 | int err, rc; | |
362 | LIST_HEAD(staging_q); | |
363 | ||
364 | path = u->u.buffer + sizeof(u->u.msg); | |
365 | token = memchr(path, 0, u->u.msg.len); | |
366 | if (token == NULL) { | |
367 | rc = -EILSEQ; | |
368 | goto out; | |
369 | } | |
370 | token++; | |
371 | ||
372 | if (msg_type == XS_WATCH) { | |
373 | watch = alloc_watch_adapter(path, token); | |
374 | if (watch == NULL) { | |
375 | rc = -ENOMEM; | |
376 | goto out; | |
377 | } | |
378 | ||
379 | watch->watch.callback = watch_fired; | |
380 | watch->dev_data = u; | |
381 | ||
382 | err = register_xenbus_watch(&watch->watch); | |
383 | if (err) { | |
384 | free_watch_adapter(watch); | |
385 | rc = err; | |
386 | goto out; | |
387 | } | |
388 | list_add(&watch->list, &u->watches); | |
389 | } else { | |
390 | list_for_each_entry_safe(watch, tmp_watch, &u->watches, list) { | |
391 | if (!strcmp(watch->token, token) && | |
392 | !strcmp(watch->watch.node, path)) { | |
393 | unregister_xenbus_watch(&watch->watch); | |
394 | list_del(&watch->list); | |
395 | free_watch_adapter(watch); | |
396 | break; | |
397 | } | |
398 | } | |
399 | } | |
400 | ||
401 | /* Success. Synthesize a reply to say all is OK. */ | |
402 | { | |
403 | struct { | |
404 | struct xsd_sockmsg hdr; | |
405 | char body[3]; | |
406 | } __packed reply = { | |
407 | { | |
408 | .type = msg_type, | |
409 | .len = sizeof(reply.body) | |
410 | }, | |
411 | "OK" | |
412 | }; | |
413 | ||
414 | mutex_lock(&u->reply_mutex); | |
415 | rc = queue_reply(&u->read_buffers, &reply, sizeof(reply)); | |
76ce7618 | 416 | wake_up(&u->read_waitq); |
1107ba88 AZ |
417 | mutex_unlock(&u->reply_mutex); |
418 | } | |
419 | ||
420 | out: | |
421 | return rc; | |
422 | } | |
423 | ||
424 | static ssize_t xenbus_file_write(struct file *filp, | |
425 | const char __user *ubuf, | |
426 | size_t len, loff_t *ppos) | |
427 | { | |
428 | struct xenbus_file_priv *u = filp->private_data; | |
429 | uint32_t msg_type; | |
430 | int rc = len; | |
431 | int ret; | |
432 | LIST_HEAD(staging_q); | |
433 | ||
434 | /* | |
435 | * We're expecting usermode to be writing properly formed | |
436 | * xenbus messages. If they write an incomplete message we | |
437 | * buffer it up. Once it is complete, we act on it. | |
438 | */ | |
439 | ||
440 | /* | |
441 | * Make sure concurrent writers can't stomp all over each | |
442 | * other's messages and make a mess of our partial message | |
443 | * buffer. We don't make any attemppt to stop multiple | |
444 | * writers from making a mess of each other's incomplete | |
445 | * messages; we're just trying to guarantee our own internal | |
446 | * consistency and make sure that single writes are handled | |
447 | * atomically. | |
448 | */ | |
449 | mutex_lock(&u->msgbuffer_mutex); | |
450 | ||
451 | /* Get this out of the way early to avoid confusion */ | |
452 | if (len == 0) | |
453 | goto out; | |
454 | ||
455 | /* Can't write a xenbus message larger we can buffer */ | |
456 | if ((len + u->len) > sizeof(u->u.buffer)) { | |
457 | /* On error, dump existing buffer */ | |
458 | u->len = 0; | |
459 | rc = -EINVAL; | |
460 | goto out; | |
461 | } | |
462 | ||
463 | ret = copy_from_user(u->u.buffer + u->len, ubuf, len); | |
464 | ||
fb27cfbc | 465 | if (ret != 0) { |
1107ba88 AZ |
466 | rc = -EFAULT; |
467 | goto out; | |
468 | } | |
469 | ||
470 | /* Deal with a partial copy. */ | |
471 | len -= ret; | |
472 | rc = len; | |
473 | ||
474 | u->len += len; | |
475 | ||
476 | /* Return if we haven't got a full message yet */ | |
477 | if (u->len < sizeof(u->u.msg)) | |
478 | goto out; /* not even the header yet */ | |
479 | ||
480 | /* If we're expecting a message that's larger than we can | |
481 | possibly send, dump what we have and return an error. */ | |
482 | if ((sizeof(u->u.msg) + u->u.msg.len) > sizeof(u->u.buffer)) { | |
483 | rc = -E2BIG; | |
484 | u->len = 0; | |
485 | goto out; | |
486 | } | |
487 | ||
488 | if (u->len < (sizeof(u->u.msg) + u->u.msg.len)) | |
489 | goto out; /* incomplete data portion */ | |
490 | ||
491 | /* | |
492 | * OK, now we have a complete message. Do something with it. | |
493 | */ | |
494 | ||
495 | msg_type = u->u.msg.type; | |
496 | ||
497 | switch (msg_type) { | |
1107ba88 AZ |
498 | case XS_WATCH: |
499 | case XS_UNWATCH: | |
500 | /* (Un)Ask for some path to be watched for changes */ | |
501 | ret = xenbus_write_watch(msg_type, u); | |
502 | break; | |
503 | ||
504 | default: | |
6d6df2e4 DO |
505 | /* Send out a transaction */ |
506 | ret = xenbus_write_transaction(msg_type, u); | |
1107ba88 AZ |
507 | break; |
508 | } | |
509 | if (ret != 0) | |
510 | rc = ret; | |
511 | ||
512 | /* Buffered message consumed */ | |
513 | u->len = 0; | |
514 | ||
515 | out: | |
516 | mutex_unlock(&u->msgbuffer_mutex); | |
517 | return rc; | |
518 | } | |
519 | ||
520 | static int xenbus_file_open(struct inode *inode, struct file *filp) | |
521 | { | |
522 | struct xenbus_file_priv *u; | |
523 | ||
524 | if (xen_store_evtchn == 0) | |
525 | return -ENOENT; | |
526 | ||
527 | nonseekable_open(inode, filp); | |
528 | ||
529 | u = kzalloc(sizeof(*u), GFP_KERNEL); | |
530 | if (u == NULL) | |
531 | return -ENOMEM; | |
532 | ||
533 | INIT_LIST_HEAD(&u->transactions); | |
534 | INIT_LIST_HEAD(&u->watches); | |
535 | INIT_LIST_HEAD(&u->read_buffers); | |
536 | init_waitqueue_head(&u->read_waitq); | |
537 | ||
538 | mutex_init(&u->reply_mutex); | |
539 | mutex_init(&u->msgbuffer_mutex); | |
540 | ||
541 | filp->private_data = u; | |
542 | ||
543 | return 0; | |
544 | } | |
545 | ||
546 | static int xenbus_file_release(struct inode *inode, struct file *filp) | |
547 | { | |
548 | struct xenbus_file_priv *u = filp->private_data; | |
549 | struct xenbus_transaction_holder *trans, *tmp; | |
550 | struct watch_adapter *watch, *tmp_watch; | |
6a5b3bef | 551 | struct read_buffer *rb, *tmp_rb; |
1107ba88 AZ |
552 | |
553 | /* | |
554 | * No need for locking here because there are no other users, | |
555 | * by definition. | |
556 | */ | |
557 | ||
558 | list_for_each_entry_safe(trans, tmp, &u->transactions, list) { | |
559 | xenbus_transaction_end(trans->handle, 1); | |
560 | list_del(&trans->list); | |
561 | kfree(trans); | |
562 | } | |
563 | ||
564 | list_for_each_entry_safe(watch, tmp_watch, &u->watches, list) { | |
565 | unregister_xenbus_watch(&watch->watch); | |
566 | list_del(&watch->list); | |
567 | free_watch_adapter(watch); | |
568 | } | |
569 | ||
6a5b3bef DDG |
570 | list_for_each_entry_safe(rb, tmp_rb, &u->read_buffers, list) { |
571 | list_del(&rb->list); | |
572 | kfree(rb); | |
573 | } | |
1107ba88 AZ |
574 | kfree(u); |
575 | ||
576 | return 0; | |
577 | } | |
578 | ||
579 | static unsigned int xenbus_file_poll(struct file *file, poll_table *wait) | |
580 | { | |
581 | struct xenbus_file_priv *u = file->private_data; | |
582 | ||
583 | poll_wait(file, &u->read_waitq, wait); | |
584 | if (!list_empty(&u->read_buffers)) | |
585 | return POLLIN | POLLRDNORM; | |
586 | return 0; | |
587 | } | |
588 | ||
2fb3683e | 589 | const struct file_operations xen_xenbus_fops = { |
1107ba88 AZ |
590 | .read = xenbus_file_read, |
591 | .write = xenbus_file_write, | |
592 | .open = xenbus_file_open, | |
593 | .release = xenbus_file_release, | |
594 | .poll = xenbus_file_poll, | |
6038f373 | 595 | .llseek = no_llseek, |
1107ba88 | 596 | }; |
2fb3683e BB |
597 | EXPORT_SYMBOL_GPL(xen_xenbus_fops); |
598 | ||
599 | static struct miscdevice xenbus_dev = { | |
600 | .minor = MISC_DYNAMIC_MINOR, | |
601 | .name = "xen/xenbus", | |
602 | .fops = &xen_xenbus_fops, | |
603 | }; | |
604 | ||
605 | static int __init xenbus_init(void) | |
606 | { | |
607 | int err; | |
608 | ||
609 | if (!xen_domain()) | |
610 | return -ENODEV; | |
611 | ||
612 | err = misc_register(&xenbus_dev); | |
613 | if (err) | |
fe7acdbe | 614 | printk(KERN_ERR "Could not register xenbus frontend device\n"); |
2fb3683e BB |
615 | return err; |
616 | } | |
617 | ||
618 | static void __exit xenbus_exit(void) | |
619 | { | |
620 | misc_deregister(&xenbus_dev); | |
621 | } | |
622 | ||
623 | module_init(xenbus_init); | |
624 | module_exit(xenbus_exit); |