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4bac07c9 JF |
1 | /****************************************************************************** |
2 | * xenbus_xs.c | |
3 | * | |
4 | * This is the kernel equivalent of the "xs" library. We don't need everything | |
5 | * and we use xenbus_comms for communication. | |
6 | * | |
7 | * Copyright (C) 2005 Rusty Russell, IBM Corporation | |
8 | * | |
9 | * This program is free software; you can redistribute it and/or | |
10 | * modify it under the terms of the GNU General Public License version 2 | |
11 | * as published by the Free Software Foundation; or, when distributed | |
12 | * separately from the Linux kernel or incorporated into other | |
13 | * software packages, subject to the following license: | |
14 | * | |
15 | * Permission is hereby granted, free of charge, to any person obtaining a copy | |
16 | * of this source file (the "Software"), to deal in the Software without | |
17 | * restriction, including without limitation the rights to use, copy, modify, | |
18 | * merge, publish, distribute, sublicense, and/or sell copies of the Software, | |
19 | * and to permit persons to whom the Software is furnished to do so, subject to | |
20 | * the following conditions: | |
21 | * | |
22 | * The above copyright notice and this permission notice shall be included in | |
23 | * all copies or substantial portions of the Software. | |
24 | * | |
25 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | |
26 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | |
27 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | |
28 | * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | |
29 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING | |
30 | * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS | |
31 | * IN THE SOFTWARE. | |
32 | */ | |
33 | ||
34 | #include <linux/unistd.h> | |
35 | #include <linux/errno.h> | |
36 | #include <linux/types.h> | |
37 | #include <linux/uio.h> | |
38 | #include <linux/kernel.h> | |
39 | #include <linux/string.h> | |
40 | #include <linux/err.h> | |
41 | #include <linux/slab.h> | |
42 | #include <linux/fcntl.h> | |
43 | #include <linux/kthread.h> | |
44 | #include <linux/rwsem.h> | |
45 | #include <linux/module.h> | |
46 | #include <linux/mutex.h> | |
47 | #include <xen/xenbus.h> | |
48 | #include "xenbus_comms.h" | |
49 | ||
50 | struct xs_stored_msg { | |
51 | struct list_head list; | |
52 | ||
53 | struct xsd_sockmsg hdr; | |
54 | ||
55 | union { | |
56 | /* Queued replies. */ | |
57 | struct { | |
58 | char *body; | |
59 | } reply; | |
60 | ||
61 | /* Queued watch events. */ | |
62 | struct { | |
63 | struct xenbus_watch *handle; | |
64 | char **vec; | |
65 | unsigned int vec_size; | |
66 | } watch; | |
67 | } u; | |
68 | }; | |
69 | ||
70 | struct xs_handle { | |
71 | /* A list of replies. Currently only one will ever be outstanding. */ | |
72 | struct list_head reply_list; | |
73 | spinlock_t reply_lock; | |
74 | wait_queue_head_t reply_waitq; | |
75 | ||
76 | /* | |
77 | * Mutex ordering: transaction_mutex -> watch_mutex -> request_mutex. | |
78 | * response_mutex is never taken simultaneously with the other three. | |
79 | */ | |
80 | ||
81 | /* One request at a time. */ | |
82 | struct mutex request_mutex; | |
83 | ||
84 | /* Protect xenbus reader thread against save/restore. */ | |
85 | struct mutex response_mutex; | |
86 | ||
87 | /* Protect transactions against save/restore. */ | |
88 | struct rw_semaphore transaction_mutex; | |
89 | ||
90 | /* Protect watch (de)register against save/restore. */ | |
91 | struct rw_semaphore watch_mutex; | |
92 | }; | |
93 | ||
94 | static struct xs_handle xs_state; | |
95 | ||
96 | /* List of registered watches, and a lock to protect it. */ | |
97 | static LIST_HEAD(watches); | |
98 | static DEFINE_SPINLOCK(watches_lock); | |
99 | ||
100 | /* List of pending watch callback events, and a lock to protect it. */ | |
101 | static LIST_HEAD(watch_events); | |
102 | static DEFINE_SPINLOCK(watch_events_lock); | |
103 | ||
104 | /* | |
105 | * Details of the xenwatch callback kernel thread. The thread waits on the | |
106 | * watch_events_waitq for work to do (queued on watch_events list). When it | |
107 | * wakes up it acquires the xenwatch_mutex before reading the list and | |
108 | * carrying out work. | |
109 | */ | |
110 | static pid_t xenwatch_pid; | |
111 | static DEFINE_MUTEX(xenwatch_mutex); | |
112 | static DECLARE_WAIT_QUEUE_HEAD(watch_events_waitq); | |
113 | ||
114 | static int get_error(const char *errorstring) | |
115 | { | |
116 | unsigned int i; | |
117 | ||
118 | for (i = 0; strcmp(errorstring, xsd_errors[i].errstring) != 0; i++) { | |
119 | if (i == ARRAY_SIZE(xsd_errors) - 1) { | |
120 | printk(KERN_WARNING | |
121 | "XENBUS xen store gave: unknown error %s", | |
122 | errorstring); | |
123 | return EINVAL; | |
124 | } | |
125 | } | |
126 | return xsd_errors[i].errnum; | |
127 | } | |
128 | ||
129 | static void *read_reply(enum xsd_sockmsg_type *type, unsigned int *len) | |
130 | { | |
131 | struct xs_stored_msg *msg; | |
132 | char *body; | |
133 | ||
134 | spin_lock(&xs_state.reply_lock); | |
135 | ||
136 | while (list_empty(&xs_state.reply_list)) { | |
137 | spin_unlock(&xs_state.reply_lock); | |
138 | /* XXX FIXME: Avoid synchronous wait for response here. */ | |
139 | wait_event(xs_state.reply_waitq, | |
140 | !list_empty(&xs_state.reply_list)); | |
141 | spin_lock(&xs_state.reply_lock); | |
142 | } | |
143 | ||
144 | msg = list_entry(xs_state.reply_list.next, | |
145 | struct xs_stored_msg, list); | |
146 | list_del(&msg->list); | |
147 | ||
148 | spin_unlock(&xs_state.reply_lock); | |
149 | ||
150 | *type = msg->hdr.type; | |
151 | if (len) | |
152 | *len = msg->hdr.len; | |
153 | body = msg->u.reply.body; | |
154 | ||
155 | kfree(msg); | |
156 | ||
157 | return body; | |
158 | } | |
159 | ||
160 | void *xenbus_dev_request_and_reply(struct xsd_sockmsg *msg) | |
161 | { | |
162 | void *ret; | |
163 | struct xsd_sockmsg req_msg = *msg; | |
164 | int err; | |
165 | ||
166 | if (req_msg.type == XS_TRANSACTION_START) | |
167 | down_read(&xs_state.transaction_mutex); | |
168 | ||
169 | mutex_lock(&xs_state.request_mutex); | |
170 | ||
171 | err = xb_write(msg, sizeof(*msg) + msg->len); | |
172 | if (err) { | |
173 | msg->type = XS_ERROR; | |
174 | ret = ERR_PTR(err); | |
175 | } else | |
176 | ret = read_reply(&msg->type, &msg->len); | |
177 | ||
178 | mutex_unlock(&xs_state.request_mutex); | |
179 | ||
180 | if ((msg->type == XS_TRANSACTION_END) || | |
181 | ((req_msg.type == XS_TRANSACTION_START) && | |
182 | (msg->type == XS_ERROR))) | |
183 | up_read(&xs_state.transaction_mutex); | |
184 | ||
185 | return ret; | |
186 | } | |
187 | ||
188 | /* Send message to xs, get kmalloc'ed reply. ERR_PTR() on error. */ | |
189 | static void *xs_talkv(struct xenbus_transaction t, | |
190 | enum xsd_sockmsg_type type, | |
191 | const struct kvec *iovec, | |
192 | unsigned int num_vecs, | |
193 | unsigned int *len) | |
194 | { | |
195 | struct xsd_sockmsg msg; | |
196 | void *ret = NULL; | |
197 | unsigned int i; | |
198 | int err; | |
199 | ||
200 | msg.tx_id = t.id; | |
201 | msg.req_id = 0; | |
202 | msg.type = type; | |
203 | msg.len = 0; | |
204 | for (i = 0; i < num_vecs; i++) | |
205 | msg.len += iovec[i].iov_len; | |
206 | ||
207 | mutex_lock(&xs_state.request_mutex); | |
208 | ||
209 | err = xb_write(&msg, sizeof(msg)); | |
210 | if (err) { | |
211 | mutex_unlock(&xs_state.request_mutex); | |
212 | return ERR_PTR(err); | |
213 | } | |
214 | ||
215 | for (i = 0; i < num_vecs; i++) { | |
216 | err = xb_write(iovec[i].iov_base, iovec[i].iov_len); | |
217 | if (err) { | |
218 | mutex_unlock(&xs_state.request_mutex); | |
219 | return ERR_PTR(err); | |
220 | } | |
221 | } | |
222 | ||
223 | ret = read_reply(&msg.type, len); | |
224 | ||
225 | mutex_unlock(&xs_state.request_mutex); | |
226 | ||
227 | if (IS_ERR(ret)) | |
228 | return ret; | |
229 | ||
230 | if (msg.type == XS_ERROR) { | |
231 | err = get_error(ret); | |
232 | kfree(ret); | |
233 | return ERR_PTR(-err); | |
234 | } | |
235 | ||
236 | if (msg.type != type) { | |
237 | if (printk_ratelimit()) | |
238 | printk(KERN_WARNING | |
239 | "XENBUS unexpected type [%d], expected [%d]\n", | |
240 | msg.type, type); | |
241 | kfree(ret); | |
242 | return ERR_PTR(-EINVAL); | |
243 | } | |
244 | return ret; | |
245 | } | |
246 | ||
247 | /* Simplified version of xs_talkv: single message. */ | |
248 | static void *xs_single(struct xenbus_transaction t, | |
249 | enum xsd_sockmsg_type type, | |
250 | const char *string, | |
251 | unsigned int *len) | |
252 | { | |
253 | struct kvec iovec; | |
254 | ||
255 | iovec.iov_base = (void *)string; | |
256 | iovec.iov_len = strlen(string) + 1; | |
257 | return xs_talkv(t, type, &iovec, 1, len); | |
258 | } | |
259 | ||
260 | /* Many commands only need an ack, don't care what it says. */ | |
261 | static int xs_error(char *reply) | |
262 | { | |
263 | if (IS_ERR(reply)) | |
264 | return PTR_ERR(reply); | |
265 | kfree(reply); | |
266 | return 0; | |
267 | } | |
268 | ||
269 | static unsigned int count_strings(const char *strings, unsigned int len) | |
270 | { | |
271 | unsigned int num; | |
272 | const char *p; | |
273 | ||
274 | for (p = strings, num = 0; p < strings + len; p += strlen(p) + 1) | |
275 | num++; | |
276 | ||
277 | return num; | |
278 | } | |
279 | ||
280 | /* Return the path to dir with /name appended. Buffer must be kfree()'ed. */ | |
281 | static char *join(const char *dir, const char *name) | |
282 | { | |
283 | char *buffer; | |
284 | ||
285 | if (strlen(name) == 0) | |
286 | buffer = kasprintf(GFP_KERNEL, "%s", dir); | |
287 | else | |
288 | buffer = kasprintf(GFP_KERNEL, "%s/%s", dir, name); | |
289 | return (!buffer) ? ERR_PTR(-ENOMEM) : buffer; | |
290 | } | |
291 | ||
292 | static char **split(char *strings, unsigned int len, unsigned int *num) | |
293 | { | |
294 | char *p, **ret; | |
295 | ||
296 | /* Count the strings. */ | |
297 | *num = count_strings(strings, len); | |
298 | ||
299 | /* Transfer to one big alloc for easy freeing. */ | |
300 | ret = kmalloc(*num * sizeof(char *) + len, GFP_KERNEL); | |
301 | if (!ret) { | |
302 | kfree(strings); | |
303 | return ERR_PTR(-ENOMEM); | |
304 | } | |
305 | memcpy(&ret[*num], strings, len); | |
306 | kfree(strings); | |
307 | ||
308 | strings = (char *)&ret[*num]; | |
309 | for (p = strings, *num = 0; p < strings + len; p += strlen(p) + 1) | |
310 | ret[(*num)++] = p; | |
311 | ||
312 | return ret; | |
313 | } | |
314 | ||
315 | char **xenbus_directory(struct xenbus_transaction t, | |
316 | const char *dir, const char *node, unsigned int *num) | |
317 | { | |
318 | char *strings, *path; | |
319 | unsigned int len; | |
320 | ||
321 | path = join(dir, node); | |
322 | if (IS_ERR(path)) | |
323 | return (char **)path; | |
324 | ||
325 | strings = xs_single(t, XS_DIRECTORY, path, &len); | |
326 | kfree(path); | |
327 | if (IS_ERR(strings)) | |
328 | return (char **)strings; | |
329 | ||
330 | return split(strings, len, num); | |
331 | } | |
332 | EXPORT_SYMBOL_GPL(xenbus_directory); | |
333 | ||
334 | /* Check if a path exists. Return 1 if it does. */ | |
335 | int xenbus_exists(struct xenbus_transaction t, | |
336 | const char *dir, const char *node) | |
337 | { | |
338 | char **d; | |
339 | int dir_n; | |
340 | ||
341 | d = xenbus_directory(t, dir, node, &dir_n); | |
342 | if (IS_ERR(d)) | |
343 | return 0; | |
344 | kfree(d); | |
345 | return 1; | |
346 | } | |
347 | EXPORT_SYMBOL_GPL(xenbus_exists); | |
348 | ||
349 | /* Get the value of a single file. | |
350 | * Returns a kmalloced value: call free() on it after use. | |
351 | * len indicates length in bytes. | |
352 | */ | |
353 | void *xenbus_read(struct xenbus_transaction t, | |
354 | const char *dir, const char *node, unsigned int *len) | |
355 | { | |
356 | char *path; | |
357 | void *ret; | |
358 | ||
359 | path = join(dir, node); | |
360 | if (IS_ERR(path)) | |
361 | return (void *)path; | |
362 | ||
363 | ret = xs_single(t, XS_READ, path, len); | |
364 | kfree(path); | |
365 | return ret; | |
366 | } | |
367 | EXPORT_SYMBOL_GPL(xenbus_read); | |
368 | ||
369 | /* Write the value of a single file. | |
370 | * Returns -err on failure. | |
371 | */ | |
372 | int xenbus_write(struct xenbus_transaction t, | |
373 | const char *dir, const char *node, const char *string) | |
374 | { | |
375 | const char *path; | |
376 | struct kvec iovec[2]; | |
377 | int ret; | |
378 | ||
379 | path = join(dir, node); | |
380 | if (IS_ERR(path)) | |
381 | return PTR_ERR(path); | |
382 | ||
383 | iovec[0].iov_base = (void *)path; | |
384 | iovec[0].iov_len = strlen(path) + 1; | |
385 | iovec[1].iov_base = (void *)string; | |
386 | iovec[1].iov_len = strlen(string); | |
387 | ||
388 | ret = xs_error(xs_talkv(t, XS_WRITE, iovec, ARRAY_SIZE(iovec), NULL)); | |
389 | kfree(path); | |
390 | return ret; | |
391 | } | |
392 | EXPORT_SYMBOL_GPL(xenbus_write); | |
393 | ||
394 | /* Create a new directory. */ | |
395 | int xenbus_mkdir(struct xenbus_transaction t, | |
396 | const char *dir, const char *node) | |
397 | { | |
398 | char *path; | |
399 | int ret; | |
400 | ||
401 | path = join(dir, node); | |
402 | if (IS_ERR(path)) | |
403 | return PTR_ERR(path); | |
404 | ||
405 | ret = xs_error(xs_single(t, XS_MKDIR, path, NULL)); | |
406 | kfree(path); | |
407 | return ret; | |
408 | } | |
409 | EXPORT_SYMBOL_GPL(xenbus_mkdir); | |
410 | ||
411 | /* Destroy a file or directory (directories must be empty). */ | |
412 | int xenbus_rm(struct xenbus_transaction t, const char *dir, const char *node) | |
413 | { | |
414 | char *path; | |
415 | int ret; | |
416 | ||
417 | path = join(dir, node); | |
418 | if (IS_ERR(path)) | |
419 | return PTR_ERR(path); | |
420 | ||
421 | ret = xs_error(xs_single(t, XS_RM, path, NULL)); | |
422 | kfree(path); | |
423 | return ret; | |
424 | } | |
425 | EXPORT_SYMBOL_GPL(xenbus_rm); | |
426 | ||
427 | /* Start a transaction: changes by others will not be seen during this | |
428 | * transaction, and changes will not be visible to others until end. | |
429 | */ | |
430 | int xenbus_transaction_start(struct xenbus_transaction *t) | |
431 | { | |
432 | char *id_str; | |
433 | ||
434 | down_read(&xs_state.transaction_mutex); | |
435 | ||
436 | id_str = xs_single(XBT_NIL, XS_TRANSACTION_START, "", NULL); | |
437 | if (IS_ERR(id_str)) { | |
438 | up_read(&xs_state.transaction_mutex); | |
439 | return PTR_ERR(id_str); | |
440 | } | |
441 | ||
442 | t->id = simple_strtoul(id_str, NULL, 0); | |
443 | kfree(id_str); | |
444 | return 0; | |
445 | } | |
446 | EXPORT_SYMBOL_GPL(xenbus_transaction_start); | |
447 | ||
448 | /* End a transaction. | |
449 | * If abandon is true, transaction is discarded instead of committed. | |
450 | */ | |
451 | int xenbus_transaction_end(struct xenbus_transaction t, int abort) | |
452 | { | |
453 | char abortstr[2]; | |
454 | int err; | |
455 | ||
456 | if (abort) | |
457 | strcpy(abortstr, "F"); | |
458 | else | |
459 | strcpy(abortstr, "T"); | |
460 | ||
461 | err = xs_error(xs_single(t, XS_TRANSACTION_END, abortstr, NULL)); | |
462 | ||
463 | up_read(&xs_state.transaction_mutex); | |
464 | ||
465 | return err; | |
466 | } | |
467 | EXPORT_SYMBOL_GPL(xenbus_transaction_end); | |
468 | ||
469 | /* Single read and scanf: returns -errno or num scanned. */ | |
470 | int xenbus_scanf(struct xenbus_transaction t, | |
471 | const char *dir, const char *node, const char *fmt, ...) | |
472 | { | |
473 | va_list ap; | |
474 | int ret; | |
475 | char *val; | |
476 | ||
477 | val = xenbus_read(t, dir, node, NULL); | |
478 | if (IS_ERR(val)) | |
479 | return PTR_ERR(val); | |
480 | ||
481 | va_start(ap, fmt); | |
482 | ret = vsscanf(val, fmt, ap); | |
483 | va_end(ap); | |
484 | kfree(val); | |
485 | /* Distinctive errno. */ | |
486 | if (ret == 0) | |
487 | return -ERANGE; | |
488 | return ret; | |
489 | } | |
490 | EXPORT_SYMBOL_GPL(xenbus_scanf); | |
491 | ||
492 | /* Single printf and write: returns -errno or 0. */ | |
493 | int xenbus_printf(struct xenbus_transaction t, | |
494 | const char *dir, const char *node, const char *fmt, ...) | |
495 | { | |
496 | va_list ap; | |
497 | int ret; | |
498 | #define PRINTF_BUFFER_SIZE 4096 | |
499 | char *printf_buffer; | |
500 | ||
501 | printf_buffer = kmalloc(PRINTF_BUFFER_SIZE, GFP_KERNEL); | |
502 | if (printf_buffer == NULL) | |
503 | return -ENOMEM; | |
504 | ||
505 | va_start(ap, fmt); | |
506 | ret = vsnprintf(printf_buffer, PRINTF_BUFFER_SIZE, fmt, ap); | |
507 | va_end(ap); | |
508 | ||
509 | BUG_ON(ret > PRINTF_BUFFER_SIZE-1); | |
510 | ret = xenbus_write(t, dir, node, printf_buffer); | |
511 | ||
512 | kfree(printf_buffer); | |
513 | ||
514 | return ret; | |
515 | } | |
516 | EXPORT_SYMBOL_GPL(xenbus_printf); | |
517 | ||
518 | /* Takes tuples of names, scanf-style args, and void **, NULL terminated. */ | |
519 | int xenbus_gather(struct xenbus_transaction t, const char *dir, ...) | |
520 | { | |
521 | va_list ap; | |
522 | const char *name; | |
523 | int ret = 0; | |
524 | ||
525 | va_start(ap, dir); | |
526 | while (ret == 0 && (name = va_arg(ap, char *)) != NULL) { | |
527 | const char *fmt = va_arg(ap, char *); | |
528 | void *result = va_arg(ap, void *); | |
529 | char *p; | |
530 | ||
531 | p = xenbus_read(t, dir, name, NULL); | |
532 | if (IS_ERR(p)) { | |
533 | ret = PTR_ERR(p); | |
534 | break; | |
535 | } | |
536 | if (fmt) { | |
537 | if (sscanf(p, fmt, result) == 0) | |
538 | ret = -EINVAL; | |
539 | kfree(p); | |
540 | } else | |
541 | *(char **)result = p; | |
542 | } | |
543 | va_end(ap); | |
544 | return ret; | |
545 | } | |
546 | EXPORT_SYMBOL_GPL(xenbus_gather); | |
547 | ||
548 | static int xs_watch(const char *path, const char *token) | |
549 | { | |
550 | struct kvec iov[2]; | |
551 | ||
552 | iov[0].iov_base = (void *)path; | |
553 | iov[0].iov_len = strlen(path) + 1; | |
554 | iov[1].iov_base = (void *)token; | |
555 | iov[1].iov_len = strlen(token) + 1; | |
556 | ||
557 | return xs_error(xs_talkv(XBT_NIL, XS_WATCH, iov, | |
558 | ARRAY_SIZE(iov), NULL)); | |
559 | } | |
560 | ||
561 | static int xs_unwatch(const char *path, const char *token) | |
562 | { | |
563 | struct kvec iov[2]; | |
564 | ||
565 | iov[0].iov_base = (char *)path; | |
566 | iov[0].iov_len = strlen(path) + 1; | |
567 | iov[1].iov_base = (char *)token; | |
568 | iov[1].iov_len = strlen(token) + 1; | |
569 | ||
570 | return xs_error(xs_talkv(XBT_NIL, XS_UNWATCH, iov, | |
571 | ARRAY_SIZE(iov), NULL)); | |
572 | } | |
573 | ||
574 | static struct xenbus_watch *find_watch(const char *token) | |
575 | { | |
576 | struct xenbus_watch *i, *cmp; | |
577 | ||
578 | cmp = (void *)simple_strtoul(token, NULL, 16); | |
579 | ||
580 | list_for_each_entry(i, &watches, list) | |
581 | if (i == cmp) | |
582 | return i; | |
583 | ||
584 | return NULL; | |
585 | } | |
586 | ||
587 | /* Register callback to watch this node. */ | |
588 | int register_xenbus_watch(struct xenbus_watch *watch) | |
589 | { | |
590 | /* Pointer in ascii is the token. */ | |
591 | char token[sizeof(watch) * 2 + 1]; | |
592 | int err; | |
593 | ||
594 | sprintf(token, "%lX", (long)watch); | |
595 | ||
596 | down_read(&xs_state.watch_mutex); | |
597 | ||
598 | spin_lock(&watches_lock); | |
599 | BUG_ON(find_watch(token)); | |
600 | list_add(&watch->list, &watches); | |
601 | spin_unlock(&watches_lock); | |
602 | ||
603 | err = xs_watch(watch->node, token); | |
604 | ||
605 | /* Ignore errors due to multiple registration. */ | |
606 | if ((err != 0) && (err != -EEXIST)) { | |
607 | spin_lock(&watches_lock); | |
608 | list_del(&watch->list); | |
609 | spin_unlock(&watches_lock); | |
610 | } | |
611 | ||
612 | up_read(&xs_state.watch_mutex); | |
613 | ||
614 | return err; | |
615 | } | |
616 | EXPORT_SYMBOL_GPL(register_xenbus_watch); | |
617 | ||
618 | void unregister_xenbus_watch(struct xenbus_watch *watch) | |
619 | { | |
620 | struct xs_stored_msg *msg, *tmp; | |
621 | char token[sizeof(watch) * 2 + 1]; | |
622 | int err; | |
623 | ||
624 | sprintf(token, "%lX", (long)watch); | |
625 | ||
626 | down_read(&xs_state.watch_mutex); | |
627 | ||
628 | spin_lock(&watches_lock); | |
629 | BUG_ON(!find_watch(token)); | |
630 | list_del(&watch->list); | |
631 | spin_unlock(&watches_lock); | |
632 | ||
633 | err = xs_unwatch(watch->node, token); | |
634 | if (err) | |
635 | printk(KERN_WARNING | |
636 | "XENBUS Failed to release watch %s: %i\n", | |
637 | watch->node, err); | |
638 | ||
639 | up_read(&xs_state.watch_mutex); | |
640 | ||
641 | /* Make sure there are no callbacks running currently (unless | |
642 | its us) */ | |
643 | if (current->pid != xenwatch_pid) | |
644 | mutex_lock(&xenwatch_mutex); | |
645 | ||
646 | /* Cancel pending watch events. */ | |
647 | spin_lock(&watch_events_lock); | |
648 | list_for_each_entry_safe(msg, tmp, &watch_events, list) { | |
649 | if (msg->u.watch.handle != watch) | |
650 | continue; | |
651 | list_del(&msg->list); | |
652 | kfree(msg->u.watch.vec); | |
653 | kfree(msg); | |
654 | } | |
655 | spin_unlock(&watch_events_lock); | |
656 | ||
657 | if (current->pid != xenwatch_pid) | |
658 | mutex_unlock(&xenwatch_mutex); | |
659 | } | |
660 | EXPORT_SYMBOL_GPL(unregister_xenbus_watch); | |
661 | ||
662 | void xs_suspend(void) | |
663 | { | |
664 | down_write(&xs_state.transaction_mutex); | |
665 | down_write(&xs_state.watch_mutex); | |
666 | mutex_lock(&xs_state.request_mutex); | |
667 | mutex_lock(&xs_state.response_mutex); | |
668 | } | |
669 | ||
670 | void xs_resume(void) | |
671 | { | |
672 | struct xenbus_watch *watch; | |
673 | char token[sizeof(watch) * 2 + 1]; | |
674 | ||
675 | mutex_unlock(&xs_state.response_mutex); | |
676 | mutex_unlock(&xs_state.request_mutex); | |
677 | up_write(&xs_state.transaction_mutex); | |
678 | ||
679 | /* No need for watches_lock: the watch_mutex is sufficient. */ | |
680 | list_for_each_entry(watch, &watches, list) { | |
681 | sprintf(token, "%lX", (long)watch); | |
682 | xs_watch(watch->node, token); | |
683 | } | |
684 | ||
685 | up_write(&xs_state.watch_mutex); | |
686 | } | |
687 | ||
688 | void xs_suspend_cancel(void) | |
689 | { | |
690 | mutex_unlock(&xs_state.response_mutex); | |
691 | mutex_unlock(&xs_state.request_mutex); | |
692 | up_write(&xs_state.watch_mutex); | |
693 | up_write(&xs_state.transaction_mutex); | |
694 | } | |
695 | ||
696 | static int xenwatch_thread(void *unused) | |
697 | { | |
698 | struct list_head *ent; | |
699 | struct xs_stored_msg *msg; | |
700 | ||
701 | for (;;) { | |
702 | wait_event_interruptible(watch_events_waitq, | |
703 | !list_empty(&watch_events)); | |
704 | ||
705 | if (kthread_should_stop()) | |
706 | break; | |
707 | ||
708 | mutex_lock(&xenwatch_mutex); | |
709 | ||
710 | spin_lock(&watch_events_lock); | |
711 | ent = watch_events.next; | |
712 | if (ent != &watch_events) | |
713 | list_del(ent); | |
714 | spin_unlock(&watch_events_lock); | |
715 | ||
716 | if (ent != &watch_events) { | |
717 | msg = list_entry(ent, struct xs_stored_msg, list); | |
718 | msg->u.watch.handle->callback( | |
719 | msg->u.watch.handle, | |
720 | (const char **)msg->u.watch.vec, | |
721 | msg->u.watch.vec_size); | |
722 | kfree(msg->u.watch.vec); | |
723 | kfree(msg); | |
724 | } | |
725 | ||
726 | mutex_unlock(&xenwatch_mutex); | |
727 | } | |
728 | ||
729 | return 0; | |
730 | } | |
731 | ||
732 | static int process_msg(void) | |
733 | { | |
734 | struct xs_stored_msg *msg; | |
735 | char *body; | |
736 | int err; | |
737 | ||
738 | /* | |
739 | * We must disallow save/restore while reading a xenstore message. | |
740 | * A partial read across s/r leaves us out of sync with xenstored. | |
741 | */ | |
742 | for (;;) { | |
743 | err = xb_wait_for_data_to_read(); | |
744 | if (err) | |
745 | return err; | |
746 | mutex_lock(&xs_state.response_mutex); | |
747 | if (xb_data_to_read()) | |
748 | break; | |
749 | /* We raced with save/restore: pending data 'disappeared'. */ | |
750 | mutex_unlock(&xs_state.response_mutex); | |
751 | } | |
752 | ||
753 | ||
754 | msg = kmalloc(sizeof(*msg), GFP_KERNEL); | |
755 | if (msg == NULL) { | |
756 | err = -ENOMEM; | |
757 | goto out; | |
758 | } | |
759 | ||
760 | err = xb_read(&msg->hdr, sizeof(msg->hdr)); | |
761 | if (err) { | |
762 | kfree(msg); | |
763 | goto out; | |
764 | } | |
765 | ||
766 | body = kmalloc(msg->hdr.len + 1, GFP_KERNEL); | |
767 | if (body == NULL) { | |
768 | kfree(msg); | |
769 | err = -ENOMEM; | |
770 | goto out; | |
771 | } | |
772 | ||
773 | err = xb_read(body, msg->hdr.len); | |
774 | if (err) { | |
775 | kfree(body); | |
776 | kfree(msg); | |
777 | goto out; | |
778 | } | |
779 | body[msg->hdr.len] = '\0'; | |
780 | ||
781 | if (msg->hdr.type == XS_WATCH_EVENT) { | |
782 | msg->u.watch.vec = split(body, msg->hdr.len, | |
783 | &msg->u.watch.vec_size); | |
784 | if (IS_ERR(msg->u.watch.vec)) { | |
785 | kfree(msg); | |
786 | err = PTR_ERR(msg->u.watch.vec); | |
787 | goto out; | |
788 | } | |
789 | ||
790 | spin_lock(&watches_lock); | |
791 | msg->u.watch.handle = find_watch( | |
792 | msg->u.watch.vec[XS_WATCH_TOKEN]); | |
793 | if (msg->u.watch.handle != NULL) { | |
794 | spin_lock(&watch_events_lock); | |
795 | list_add_tail(&msg->list, &watch_events); | |
796 | wake_up(&watch_events_waitq); | |
797 | spin_unlock(&watch_events_lock); | |
798 | } else { | |
799 | kfree(msg->u.watch.vec); | |
800 | kfree(msg); | |
801 | } | |
802 | spin_unlock(&watches_lock); | |
803 | } else { | |
804 | msg->u.reply.body = body; | |
805 | spin_lock(&xs_state.reply_lock); | |
806 | list_add_tail(&msg->list, &xs_state.reply_list); | |
807 | spin_unlock(&xs_state.reply_lock); | |
808 | wake_up(&xs_state.reply_waitq); | |
809 | } | |
810 | ||
811 | out: | |
812 | mutex_unlock(&xs_state.response_mutex); | |
813 | return err; | |
814 | } | |
815 | ||
816 | static int xenbus_thread(void *unused) | |
817 | { | |
818 | int err; | |
819 | ||
820 | for (;;) { | |
821 | err = process_msg(); | |
822 | if (err) | |
823 | printk(KERN_WARNING "XENBUS error %d while reading " | |
824 | "message\n", err); | |
825 | if (kthread_should_stop()) | |
826 | break; | |
827 | } | |
828 | ||
829 | return 0; | |
830 | } | |
831 | ||
832 | int xs_init(void) | |
833 | { | |
834 | int err; | |
835 | struct task_struct *task; | |
836 | ||
837 | INIT_LIST_HEAD(&xs_state.reply_list); | |
838 | spin_lock_init(&xs_state.reply_lock); | |
839 | init_waitqueue_head(&xs_state.reply_waitq); | |
840 | ||
841 | mutex_init(&xs_state.request_mutex); | |
842 | mutex_init(&xs_state.response_mutex); | |
843 | init_rwsem(&xs_state.transaction_mutex); | |
844 | init_rwsem(&xs_state.watch_mutex); | |
845 | ||
846 | /* Initialize the shared memory rings to talk to xenstored */ | |
847 | err = xb_init_comms(); | |
848 | if (err) | |
849 | return err; | |
850 | ||
851 | task = kthread_run(xenwatch_thread, NULL, "xenwatch"); | |
852 | if (IS_ERR(task)) | |
853 | return PTR_ERR(task); | |
854 | xenwatch_pid = task->pid; | |
855 | ||
856 | task = kthread_run(xenbus_thread, NULL, "xenbus"); | |
857 | if (IS_ERR(task)) | |
858 | return PTR_ERR(task); | |
859 | ||
860 | return 0; | |
861 | } |