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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 | ||
283c0972 JP |
34 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
35 | ||
4bac07c9 JF |
36 | #include <linux/unistd.h> |
37 | #include <linux/errno.h> | |
38 | #include <linux/types.h> | |
39 | #include <linux/uio.h> | |
40 | #include <linux/kernel.h> | |
41 | #include <linux/string.h> | |
42 | #include <linux/err.h> | |
43 | #include <linux/slab.h> | |
44 | #include <linux/fcntl.h> | |
45 | #include <linux/kthread.h> | |
fd8aa909 | 46 | #include <linux/reboot.h> |
4bac07c9 | 47 | #include <linux/rwsem.h> |
4bac07c9 | 48 | #include <linux/mutex.h> |
ecc635f9 | 49 | #include <asm/xen/hypervisor.h> |
4bac07c9 | 50 | #include <xen/xenbus.h> |
5b25d89e | 51 | #include <xen/xen.h> |
332f791d | 52 | #include "xenbus.h" |
4bac07c9 | 53 | |
fd8aa909 JG |
54 | /* |
55 | * Framework to protect suspend/resume handling against normal Xenstore | |
56 | * message handling: | |
57 | * During suspend/resume there must be no open transaction and no pending | |
58 | * Xenstore request. | |
59 | * New watch events happening in this time can be ignored by firing all watches | |
60 | * after resume. | |
61 | */ | |
4bac07c9 | 62 | |
fd8aa909 JG |
63 | /* Lock protecting enter/exit critical region. */ |
64 | static DEFINE_SPINLOCK(xs_state_lock); | |
65 | /* Number of users in critical region (protected by xs_state_lock). */ | |
66 | static unsigned int xs_state_users; | |
67 | /* Suspend handler waiting or already active (protected by xs_state_lock)? */ | |
68 | static int xs_suspend_active; | |
69 | /* Unique Xenstore request id (protected by xs_state_lock). */ | |
70 | static uint32_t xs_request_id; | |
4bac07c9 | 71 | |
fd8aa909 JG |
72 | /* Wait queue for all callers waiting for critical region to become usable. */ |
73 | static DECLARE_WAIT_QUEUE_HEAD(xs_state_enter_wq); | |
74 | /* Wait queue for suspend handling waiting for critical region being empty. */ | |
75 | static DECLARE_WAIT_QUEUE_HEAD(xs_state_exit_wq); | |
4bac07c9 JF |
76 | |
77 | /* List of registered watches, and a lock to protect it. */ | |
78 | static LIST_HEAD(watches); | |
79 | static DEFINE_SPINLOCK(watches_lock); | |
80 | ||
81 | /* List of pending watch callback events, and a lock to protect it. */ | |
82 | static LIST_HEAD(watch_events); | |
83 | static DEFINE_SPINLOCK(watch_events_lock); | |
84 | ||
fd8aa909 JG |
85 | /* Protect watch (de)register against save/restore. */ |
86 | static DECLARE_RWSEM(xs_watch_rwsem); | |
87 | ||
4bac07c9 JF |
88 | /* |
89 | * Details of the xenwatch callback kernel thread. The thread waits on the | |
90 | * watch_events_waitq for work to do (queued on watch_events list). When it | |
91 | * wakes up it acquires the xenwatch_mutex before reading the list and | |
92 | * carrying out work. | |
93 | */ | |
94 | static pid_t xenwatch_pid; | |
95 | static DEFINE_MUTEX(xenwatch_mutex); | |
96 | static DECLARE_WAIT_QUEUE_HEAD(watch_events_waitq); | |
97 | ||
fd8aa909 JG |
98 | static void xs_suspend_enter(void) |
99 | { | |
100 | spin_lock(&xs_state_lock); | |
101 | xs_suspend_active++; | |
102 | spin_unlock(&xs_state_lock); | |
103 | wait_event(xs_state_exit_wq, xs_state_users == 0); | |
104 | } | |
105 | ||
106 | static void xs_suspend_exit(void) | |
107 | { | |
d10e0cc1 | 108 | xb_dev_generation_id++; |
fd8aa909 JG |
109 | spin_lock(&xs_state_lock); |
110 | xs_suspend_active--; | |
111 | spin_unlock(&xs_state_lock); | |
112 | wake_up_all(&xs_state_enter_wq); | |
113 | } | |
114 | ||
115 | static uint32_t xs_request_enter(struct xb_req_data *req) | |
116 | { | |
117 | uint32_t rq_id; | |
118 | ||
119 | req->type = req->msg.type; | |
120 | ||
121 | spin_lock(&xs_state_lock); | |
122 | ||
123 | while (!xs_state_users && xs_suspend_active) { | |
124 | spin_unlock(&xs_state_lock); | |
125 | wait_event(xs_state_enter_wq, xs_suspend_active == 0); | |
126 | spin_lock(&xs_state_lock); | |
127 | } | |
128 | ||
d10e0cc1 | 129 | if (req->type == XS_TRANSACTION_START && !req->user_req) |
fd8aa909 JG |
130 | xs_state_users++; |
131 | xs_state_users++; | |
132 | rq_id = xs_request_id++; | |
133 | ||
134 | spin_unlock(&xs_state_lock); | |
135 | ||
136 | return rq_id; | |
137 | } | |
138 | ||
139 | void xs_request_exit(struct xb_req_data *req) | |
140 | { | |
141 | spin_lock(&xs_state_lock); | |
142 | xs_state_users--; | |
143 | if ((req->type == XS_TRANSACTION_START && req->msg.type == XS_ERROR) || | |
d10e0cc1 | 144 | (req->type == XS_TRANSACTION_END && !req->user_req && |
b93008d1 SG |
145 | !WARN_ON_ONCE(req->msg.type == XS_ERROR && |
146 | !strcmp(req->body, "ENOENT")))) | |
fd8aa909 JG |
147 | xs_state_users--; |
148 | spin_unlock(&xs_state_lock); | |
149 | ||
150 | if (xs_suspend_active && !xs_state_users) | |
151 | wake_up(&xs_state_exit_wq); | |
152 | } | |
153 | ||
4bac07c9 JF |
154 | static int get_error(const char *errorstring) |
155 | { | |
156 | unsigned int i; | |
157 | ||
158 | for (i = 0; strcmp(errorstring, xsd_errors[i].errstring) != 0; i++) { | |
159 | if (i == ARRAY_SIZE(xsd_errors) - 1) { | |
283c0972 JP |
160 | pr_warn("xen store gave: unknown error %s\n", |
161 | errorstring); | |
4bac07c9 JF |
162 | return EINVAL; |
163 | } | |
164 | } | |
165 | return xsd_errors[i].errnum; | |
166 | } | |
167 | ||
027bd7e8 KRW |
168 | static bool xenbus_ok(void) |
169 | { | |
170 | switch (xen_store_domain_type) { | |
171 | case XS_LOCAL: | |
172 | switch (system_state) { | |
173 | case SYSTEM_POWER_OFF: | |
174 | case SYSTEM_RESTART: | |
175 | case SYSTEM_HALT: | |
176 | return false; | |
177 | default: | |
178 | break; | |
179 | } | |
180 | return true; | |
181 | case XS_PV: | |
182 | case XS_HVM: | |
183 | /* FIXME: Could check that the remote domain is alive, | |
184 | * but it is normally initial domain. */ | |
185 | return true; | |
186 | default: | |
187 | break; | |
188 | } | |
189 | return false; | |
190 | } | |
fd8aa909 JG |
191 | |
192 | static bool test_reply(struct xb_req_data *req) | |
4bac07c9 | 193 | { |
1b6a51e8 DZ |
194 | if (req->state == xb_req_state_got_reply || !xenbus_ok()) { |
195 | /* read req->state before all other fields */ | |
196 | virt_rmb(); | |
fd8aa909 | 197 | return true; |
1b6a51e8 | 198 | } |
4bac07c9 | 199 | |
fd8aa909 JG |
200 | /* Make sure to reread req->state each time. */ |
201 | barrier(); | |
4bac07c9 | 202 | |
fd8aa909 JG |
203 | return false; |
204 | } | |
205 | ||
206 | static void *read_reply(struct xb_req_data *req) | |
207 | { | |
1b6a51e8 | 208 | do { |
fd8aa909 JG |
209 | wait_event(req->wq, test_reply(req)); |
210 | ||
211 | if (!xenbus_ok()) | |
027bd7e8 KRW |
212 | /* |
213 | * If we are in the process of being shut-down there is | |
214 | * no point of trying to contact XenBus - it is either | |
215 | * killed (xenstored application) or the other domain | |
216 | * has been killed or is unreachable. | |
217 | */ | |
218 | return ERR_PTR(-EIO); | |
fd8aa909 JG |
219 | if (req->err) |
220 | return ERR_PTR(req->err); | |
221 | ||
1b6a51e8 | 222 | } while (req->state != xb_req_state_got_reply); |
4bac07c9 | 223 | |
fd8aa909 JG |
224 | return req->body; |
225 | } | |
4bac07c9 | 226 | |
fd8aa909 JG |
227 | static void xs_send(struct xb_req_data *req, struct xsd_sockmsg *msg) |
228 | { | |
229 | bool notify; | |
4bac07c9 | 230 | |
fd8aa909 JG |
231 | req->msg = *msg; |
232 | req->err = 0; | |
233 | req->state = xb_req_state_queued; | |
234 | init_waitqueue_head(&req->wq); | |
4bac07c9 | 235 | |
29fee6ee JM |
236 | /* Save the caller req_id and restore it later in the reply */ |
237 | req->caller_req_id = req->msg.req_id; | |
fd8aa909 | 238 | req->msg.req_id = xs_request_enter(req); |
4bac07c9 | 239 | |
fd8aa909 JG |
240 | mutex_lock(&xb_write_mutex); |
241 | list_add_tail(&req->list, &xb_write_list); | |
242 | notify = list_is_singular(&xb_write_list); | |
243 | mutex_unlock(&xb_write_mutex); | |
4bac07c9 | 244 | |
fd8aa909 JG |
245 | if (notify) |
246 | wake_up(&xb_waitq); | |
4c31a781 IC |
247 | } |
248 | ||
fd8aa909 | 249 | static void *xs_wait_for_reply(struct xb_req_data *req, struct xsd_sockmsg *msg) |
4c31a781 | 250 | { |
fd8aa909 | 251 | void *ret; |
4c31a781 | 252 | |
fd8aa909 JG |
253 | ret = read_reply(req); |
254 | ||
255 | xs_request_exit(req); | |
256 | ||
257 | msg->type = req->msg.type; | |
258 | msg->len = req->msg.len; | |
259 | ||
260 | mutex_lock(&xb_write_mutex); | |
261 | if (req->state == xb_req_state_queued || | |
262 | req->state == xb_req_state_wait_reply) | |
263 | req->state = xb_req_state_aborted; | |
264 | else | |
265 | kfree(req); | |
266 | mutex_unlock(&xb_write_mutex); | |
267 | ||
268 | return ret; | |
4c31a781 IC |
269 | } |
270 | ||
fd8aa909 | 271 | static void xs_wake_up(struct xb_req_data *req) |
4c31a781 | 272 | { |
fd8aa909 | 273 | wake_up(&req->wq); |
4c31a781 IC |
274 | } |
275 | ||
fd8aa909 | 276 | int xenbus_dev_request_and_reply(struct xsd_sockmsg *msg, void *par) |
4bac07c9 | 277 | { |
fd8aa909 JG |
278 | struct xb_req_data *req; |
279 | struct kvec *vec; | |
4bac07c9 | 280 | |
fd8aa909 JG |
281 | req = kmalloc(sizeof(*req) + sizeof(*vec), GFP_KERNEL); |
282 | if (!req) | |
283 | return -ENOMEM; | |
4bac07c9 | 284 | |
fd8aa909 JG |
285 | vec = (struct kvec *)(req + 1); |
286 | vec->iov_len = msg->len; | |
287 | vec->iov_base = msg + 1; | |
4bac07c9 | 288 | |
fd8aa909 JG |
289 | req->vec = vec; |
290 | req->num_vecs = 1; | |
291 | req->cb = xenbus_dev_queue_reply; | |
292 | req->par = par; | |
d10e0cc1 | 293 | req->user_req = true; |
4bac07c9 | 294 | |
fd8aa909 | 295 | xs_send(req, msg); |
4bac07c9 | 296 | |
fd8aa909 | 297 | return 0; |
4bac07c9 | 298 | } |
1107ba88 | 299 | EXPORT_SYMBOL(xenbus_dev_request_and_reply); |
4bac07c9 JF |
300 | |
301 | /* Send message to xs, get kmalloc'ed reply. ERR_PTR() on error. */ | |
302 | static void *xs_talkv(struct xenbus_transaction t, | |
303 | enum xsd_sockmsg_type type, | |
304 | const struct kvec *iovec, | |
305 | unsigned int num_vecs, | |
306 | unsigned int *len) | |
307 | { | |
fd8aa909 | 308 | struct xb_req_data *req; |
4bac07c9 JF |
309 | struct xsd_sockmsg msg; |
310 | void *ret = NULL; | |
311 | unsigned int i; | |
312 | int err; | |
313 | ||
fd8aa909 JG |
314 | req = kmalloc(sizeof(*req), GFP_NOIO | __GFP_HIGH); |
315 | if (!req) | |
316 | return ERR_PTR(-ENOMEM); | |
317 | ||
318 | req->vec = iovec; | |
319 | req->num_vecs = num_vecs; | |
320 | req->cb = xs_wake_up; | |
d10e0cc1 | 321 | req->user_req = false; |
fd8aa909 | 322 | |
29fee6ee | 323 | msg.req_id = 0; |
4bac07c9 | 324 | msg.tx_id = t.id; |
4bac07c9 JF |
325 | msg.type = type; |
326 | msg.len = 0; | |
327 | for (i = 0; i < num_vecs; i++) | |
328 | msg.len += iovec[i].iov_len; | |
329 | ||
fd8aa909 | 330 | xs_send(req, &msg); |
4bac07c9 | 331 | |
fd8aa909 JG |
332 | ret = xs_wait_for_reply(req, &msg); |
333 | if (len) | |
334 | *len = msg.len; | |
4bac07c9 JF |
335 | |
336 | if (IS_ERR(ret)) | |
337 | return ret; | |
338 | ||
339 | if (msg.type == XS_ERROR) { | |
340 | err = get_error(ret); | |
341 | kfree(ret); | |
342 | return ERR_PTR(-err); | |
343 | } | |
344 | ||
345 | if (msg.type != type) { | |
283c0972 JP |
346 | pr_warn_ratelimited("unexpected type [%d], expected [%d]\n", |
347 | msg.type, type); | |
4bac07c9 JF |
348 | kfree(ret); |
349 | return ERR_PTR(-EINVAL); | |
350 | } | |
351 | return ret; | |
352 | } | |
353 | ||
354 | /* Simplified version of xs_talkv: single message. */ | |
355 | static void *xs_single(struct xenbus_transaction t, | |
356 | enum xsd_sockmsg_type type, | |
357 | const char *string, | |
358 | unsigned int *len) | |
359 | { | |
360 | struct kvec iovec; | |
361 | ||
362 | iovec.iov_base = (void *)string; | |
363 | iovec.iov_len = strlen(string) + 1; | |
364 | return xs_talkv(t, type, &iovec, 1, len); | |
365 | } | |
366 | ||
367 | /* Many commands only need an ack, don't care what it says. */ | |
368 | static int xs_error(char *reply) | |
369 | { | |
370 | if (IS_ERR(reply)) | |
371 | return PTR_ERR(reply); | |
372 | kfree(reply); | |
373 | return 0; | |
374 | } | |
375 | ||
376 | static unsigned int count_strings(const char *strings, unsigned int len) | |
377 | { | |
378 | unsigned int num; | |
379 | const char *p; | |
380 | ||
381 | for (p = strings, num = 0; p < strings + len; p += strlen(p) + 1) | |
382 | num++; | |
383 | ||
384 | return num; | |
385 | } | |
386 | ||
387 | /* Return the path to dir with /name appended. Buffer must be kfree()'ed. */ | |
388 | static char *join(const char *dir, const char *name) | |
389 | { | |
390 | char *buffer; | |
391 | ||
392 | if (strlen(name) == 0) | |
a144ff09 | 393 | buffer = kasprintf(GFP_NOIO | __GFP_HIGH, "%s", dir); |
4bac07c9 | 394 | else |
a144ff09 | 395 | buffer = kasprintf(GFP_NOIO | __GFP_HIGH, "%s/%s", dir, name); |
4bac07c9 JF |
396 | return (!buffer) ? ERR_PTR(-ENOMEM) : buffer; |
397 | } | |
398 | ||
399 | static char **split(char *strings, unsigned int len, unsigned int *num) | |
400 | { | |
401 | char *p, **ret; | |
402 | ||
403 | /* Count the strings. */ | |
404 | *num = count_strings(strings, len); | |
405 | ||
406 | /* Transfer to one big alloc for easy freeing. */ | |
a144ff09 | 407 | ret = kmalloc(*num * sizeof(char *) + len, GFP_NOIO | __GFP_HIGH); |
4bac07c9 JF |
408 | if (!ret) { |
409 | kfree(strings); | |
410 | return ERR_PTR(-ENOMEM); | |
411 | } | |
412 | memcpy(&ret[*num], strings, len); | |
413 | kfree(strings); | |
414 | ||
415 | strings = (char *)&ret[*num]; | |
416 | for (p = strings, *num = 0; p < strings + len; p += strlen(p) + 1) | |
417 | ret[(*num)++] = p; | |
418 | ||
419 | return ret; | |
420 | } | |
421 | ||
422 | char **xenbus_directory(struct xenbus_transaction t, | |
423 | const char *dir, const char *node, unsigned int *num) | |
424 | { | |
425 | char *strings, *path; | |
426 | unsigned int len; | |
427 | ||
428 | path = join(dir, node); | |
429 | if (IS_ERR(path)) | |
3adc73ef | 430 | return ERR_CAST(path); |
4bac07c9 JF |
431 | |
432 | strings = xs_single(t, XS_DIRECTORY, path, &len); | |
433 | kfree(path); | |
434 | if (IS_ERR(strings)) | |
3adc73ef | 435 | return ERR_CAST(strings); |
4bac07c9 JF |
436 | |
437 | return split(strings, len, num); | |
438 | } | |
439 | EXPORT_SYMBOL_GPL(xenbus_directory); | |
440 | ||
441 | /* Check if a path exists. Return 1 if it does. */ | |
442 | int xenbus_exists(struct xenbus_transaction t, | |
443 | const char *dir, const char *node) | |
444 | { | |
445 | char **d; | |
446 | int dir_n; | |
447 | ||
448 | d = xenbus_directory(t, dir, node, &dir_n); | |
449 | if (IS_ERR(d)) | |
450 | return 0; | |
451 | kfree(d); | |
452 | return 1; | |
453 | } | |
454 | EXPORT_SYMBOL_GPL(xenbus_exists); | |
455 | ||
456 | /* Get the value of a single file. | |
457 | * Returns a kmalloced value: call free() on it after use. | |
458 | * len indicates length in bytes. | |
459 | */ | |
460 | void *xenbus_read(struct xenbus_transaction t, | |
461 | const char *dir, const char *node, unsigned int *len) | |
462 | { | |
463 | char *path; | |
464 | void *ret; | |
465 | ||
466 | path = join(dir, node); | |
467 | if (IS_ERR(path)) | |
3adc73ef | 468 | return ERR_CAST(path); |
4bac07c9 JF |
469 | |
470 | ret = xs_single(t, XS_READ, path, len); | |
471 | kfree(path); | |
472 | return ret; | |
473 | } | |
474 | EXPORT_SYMBOL_GPL(xenbus_read); | |
475 | ||
476 | /* Write the value of a single file. | |
477 | * Returns -err on failure. | |
478 | */ | |
479 | int xenbus_write(struct xenbus_transaction t, | |
480 | const char *dir, const char *node, const char *string) | |
481 | { | |
482 | const char *path; | |
483 | struct kvec iovec[2]; | |
484 | int ret; | |
485 | ||
486 | path = join(dir, node); | |
487 | if (IS_ERR(path)) | |
488 | return PTR_ERR(path); | |
489 | ||
490 | iovec[0].iov_base = (void *)path; | |
491 | iovec[0].iov_len = strlen(path) + 1; | |
492 | iovec[1].iov_base = (void *)string; | |
493 | iovec[1].iov_len = strlen(string); | |
494 | ||
495 | ret = xs_error(xs_talkv(t, XS_WRITE, iovec, ARRAY_SIZE(iovec), NULL)); | |
496 | kfree(path); | |
497 | return ret; | |
498 | } | |
499 | EXPORT_SYMBOL_GPL(xenbus_write); | |
500 | ||
501 | /* Create a new directory. */ | |
502 | int xenbus_mkdir(struct xenbus_transaction t, | |
503 | const char *dir, const char *node) | |
504 | { | |
505 | char *path; | |
506 | int ret; | |
507 | ||
508 | path = join(dir, node); | |
509 | if (IS_ERR(path)) | |
510 | return PTR_ERR(path); | |
511 | ||
512 | ret = xs_error(xs_single(t, XS_MKDIR, path, NULL)); | |
513 | kfree(path); | |
514 | return ret; | |
515 | } | |
516 | EXPORT_SYMBOL_GPL(xenbus_mkdir); | |
517 | ||
518 | /* Destroy a file or directory (directories must be empty). */ | |
519 | int xenbus_rm(struct xenbus_transaction t, const char *dir, const char *node) | |
520 | { | |
521 | char *path; | |
522 | int ret; | |
523 | ||
524 | path = join(dir, node); | |
525 | if (IS_ERR(path)) | |
526 | return PTR_ERR(path); | |
527 | ||
528 | ret = xs_error(xs_single(t, XS_RM, path, NULL)); | |
529 | kfree(path); | |
530 | return ret; | |
531 | } | |
532 | EXPORT_SYMBOL_GPL(xenbus_rm); | |
533 | ||
534 | /* Start a transaction: changes by others will not be seen during this | |
535 | * transaction, and changes will not be visible to others until end. | |
536 | */ | |
537 | int xenbus_transaction_start(struct xenbus_transaction *t) | |
538 | { | |
539 | char *id_str; | |
540 | ||
4bac07c9 | 541 | id_str = xs_single(XBT_NIL, XS_TRANSACTION_START, "", NULL); |
fd8aa909 | 542 | if (IS_ERR(id_str)) |
4bac07c9 | 543 | return PTR_ERR(id_str); |
4bac07c9 JF |
544 | |
545 | t->id = simple_strtoul(id_str, NULL, 0); | |
546 | kfree(id_str); | |
547 | return 0; | |
548 | } | |
549 | EXPORT_SYMBOL_GPL(xenbus_transaction_start); | |
550 | ||
551 | /* End a transaction. | |
552 | * If abandon is true, transaction is discarded instead of committed. | |
553 | */ | |
554 | int xenbus_transaction_end(struct xenbus_transaction t, int abort) | |
555 | { | |
556 | char abortstr[2]; | |
4bac07c9 JF |
557 | |
558 | if (abort) | |
559 | strcpy(abortstr, "F"); | |
560 | else | |
561 | strcpy(abortstr, "T"); | |
562 | ||
fd8aa909 | 563 | return xs_error(xs_single(t, XS_TRANSACTION_END, abortstr, NULL)); |
4bac07c9 JF |
564 | } |
565 | EXPORT_SYMBOL_GPL(xenbus_transaction_end); | |
566 | ||
567 | /* Single read and scanf: returns -errno or num scanned. */ | |
568 | int xenbus_scanf(struct xenbus_transaction t, | |
569 | const char *dir, const char *node, const char *fmt, ...) | |
570 | { | |
571 | va_list ap; | |
572 | int ret; | |
573 | char *val; | |
574 | ||
575 | val = xenbus_read(t, dir, node, NULL); | |
576 | if (IS_ERR(val)) | |
577 | return PTR_ERR(val); | |
578 | ||
579 | va_start(ap, fmt); | |
580 | ret = vsscanf(val, fmt, ap); | |
581 | va_end(ap); | |
582 | kfree(val); | |
583 | /* Distinctive errno. */ | |
584 | if (ret == 0) | |
585 | return -ERANGE; | |
586 | return ret; | |
587 | } | |
588 | EXPORT_SYMBOL_GPL(xenbus_scanf); | |
589 | ||
9c53a179 JG |
590 | /* Read an (optional) unsigned value. */ |
591 | unsigned int xenbus_read_unsigned(const char *dir, const char *node, | |
592 | unsigned int default_val) | |
593 | { | |
594 | unsigned int val; | |
595 | int ret; | |
596 | ||
597 | ret = xenbus_scanf(XBT_NIL, dir, node, "%u", &val); | |
598 | if (ret <= 0) | |
599 | val = default_val; | |
600 | ||
601 | return val; | |
602 | } | |
603 | EXPORT_SYMBOL_GPL(xenbus_read_unsigned); | |
604 | ||
4bac07c9 JF |
605 | /* Single printf and write: returns -errno or 0. */ |
606 | int xenbus_printf(struct xenbus_transaction t, | |
607 | const char *dir, const char *node, const char *fmt, ...) | |
608 | { | |
609 | va_list ap; | |
610 | int ret; | |
a800651e | 611 | char *buf; |
4bac07c9 JF |
612 | |
613 | va_start(ap, fmt); | |
a800651e | 614 | buf = kvasprintf(GFP_NOIO | __GFP_HIGH, fmt, ap); |
4bac07c9 JF |
615 | va_end(ap); |
616 | ||
a800651e IC |
617 | if (!buf) |
618 | return -ENOMEM; | |
619 | ||
620 | ret = xenbus_write(t, dir, node, buf); | |
4bac07c9 | 621 | |
a800651e | 622 | kfree(buf); |
4bac07c9 JF |
623 | |
624 | return ret; | |
625 | } | |
626 | EXPORT_SYMBOL_GPL(xenbus_printf); | |
627 | ||
628 | /* Takes tuples of names, scanf-style args, and void **, NULL terminated. */ | |
629 | int xenbus_gather(struct xenbus_transaction t, const char *dir, ...) | |
630 | { | |
631 | va_list ap; | |
632 | const char *name; | |
633 | int ret = 0; | |
634 | ||
635 | va_start(ap, dir); | |
636 | while (ret == 0 && (name = va_arg(ap, char *)) != NULL) { | |
637 | const char *fmt = va_arg(ap, char *); | |
638 | void *result = va_arg(ap, void *); | |
639 | char *p; | |
640 | ||
641 | p = xenbus_read(t, dir, name, NULL); | |
642 | if (IS_ERR(p)) { | |
643 | ret = PTR_ERR(p); | |
644 | break; | |
645 | } | |
646 | if (fmt) { | |
647 | if (sscanf(p, fmt, result) == 0) | |
648 | ret = -EINVAL; | |
649 | kfree(p); | |
650 | } else | |
651 | *(char **)result = p; | |
652 | } | |
653 | va_end(ap); | |
654 | return ret; | |
655 | } | |
656 | EXPORT_SYMBOL_GPL(xenbus_gather); | |
657 | ||
658 | static int xs_watch(const char *path, const char *token) | |
659 | { | |
660 | struct kvec iov[2]; | |
661 | ||
662 | iov[0].iov_base = (void *)path; | |
663 | iov[0].iov_len = strlen(path) + 1; | |
664 | iov[1].iov_base = (void *)token; | |
665 | iov[1].iov_len = strlen(token) + 1; | |
666 | ||
667 | return xs_error(xs_talkv(XBT_NIL, XS_WATCH, iov, | |
668 | ARRAY_SIZE(iov), NULL)); | |
669 | } | |
670 | ||
671 | static int xs_unwatch(const char *path, const char *token) | |
672 | { | |
673 | struct kvec iov[2]; | |
674 | ||
675 | iov[0].iov_base = (char *)path; | |
676 | iov[0].iov_len = strlen(path) + 1; | |
677 | iov[1].iov_base = (char *)token; | |
678 | iov[1].iov_len = strlen(token) + 1; | |
679 | ||
680 | return xs_error(xs_talkv(XBT_NIL, XS_UNWATCH, iov, | |
681 | ARRAY_SIZE(iov), NULL)); | |
682 | } | |
683 | ||
684 | static struct xenbus_watch *find_watch(const char *token) | |
685 | { | |
686 | struct xenbus_watch *i, *cmp; | |
687 | ||
688 | cmp = (void *)simple_strtoul(token, NULL, 16); | |
689 | ||
690 | list_for_each_entry(i, &watches, list) | |
691 | if (i == cmp) | |
692 | return i; | |
693 | ||
694 | return NULL; | |
695 | } | |
fd8aa909 JG |
696 | |
697 | int xs_watch_msg(struct xs_watch_event *event) | |
698 | { | |
699 | if (count_strings(event->body, event->len) != 2) { | |
700 | kfree(event); | |
701 | return -EINVAL; | |
702 | } | |
703 | event->path = (const char *)event->body; | |
704 | event->token = (const char *)strchr(event->body, '\0') + 1; | |
705 | ||
706 | spin_lock(&watches_lock); | |
707 | event->handle = find_watch(event->token); | |
fed1755b SP |
708 | if (event->handle != NULL && |
709 | (!event->handle->will_handle || | |
710 | event->handle->will_handle(event->handle, | |
711 | event->path, event->token))) { | |
fd8aa909 JG |
712 | spin_lock(&watch_events_lock); |
713 | list_add_tail(&event->list, &watch_events); | |
3dc86ca6 | 714 | event->handle->nr_pending++; |
fd8aa909 JG |
715 | wake_up(&watch_events_waitq); |
716 | spin_unlock(&watch_events_lock); | |
717 | } else | |
718 | kfree(event); | |
719 | spin_unlock(&watches_lock); | |
720 | ||
721 | return 0; | |
722 | } | |
723 | ||
cb6b6df1 KRW |
724 | /* |
725 | * Certain older XenBus toolstack cannot handle reading values that are | |
726 | * not populated. Some Xen 3.4 installation are incapable of doing this | |
727 | * so if we are running on anything older than 4 do not attempt to read | |
728 | * control/platform-feature-xs_reset_watches. | |
729 | */ | |
e9d1aa05 | 730 | static bool xen_strict_xenbus_quirk(void) |
cb6b6df1 | 731 | { |
7644bdac | 732 | #ifdef CONFIG_X86 |
cb6b6df1 KRW |
733 | uint32_t eax, ebx, ecx, edx, base; |
734 | ||
735 | base = xen_cpuid_base(); | |
736 | cpuid(base + 1, &eax, &ebx, &ecx, &edx); | |
4bac07c9 | 737 | |
cb6b6df1 KRW |
738 | if ((eax >> 16) < 4) |
739 | return true; | |
7644bdac | 740 | #endif |
cb6b6df1 KRW |
741 | return false; |
742 | ||
743 | } | |
254d1a3f OH |
744 | static void xs_reset_watches(void) |
745 | { | |
999c9af9 | 746 | int err; |
254d1a3f | 747 | |
ecc635f9 | 748 | if (!xen_hvm_domain() || xen_initial_domain()) |
254d1a3f OH |
749 | return; |
750 | ||
cb6b6df1 KRW |
751 | if (xen_strict_xenbus_quirk()) |
752 | return; | |
753 | ||
999c9af9 JG |
754 | if (!xenbus_read_unsigned("control", |
755 | "platform-feature-xs_reset_watches", 0)) | |
254d1a3f OH |
756 | return; |
757 | ||
758 | err = xs_error(xs_single(XBT_NIL, XS_RESET_WATCHES, "", NULL)); | |
759 | if (err && err != -EEXIST) | |
283c0972 | 760 | pr_warn("xs_reset_watches failed: %d\n", err); |
254d1a3f OH |
761 | } |
762 | ||
4bac07c9 JF |
763 | /* Register callback to watch this node. */ |
764 | int register_xenbus_watch(struct xenbus_watch *watch) | |
765 | { | |
766 | /* Pointer in ascii is the token. */ | |
767 | char token[sizeof(watch) * 2 + 1]; | |
768 | int err; | |
769 | ||
770 | sprintf(token, "%lX", (long)watch); | |
771 | ||
3dc86ca6 SP |
772 | watch->nr_pending = 0; |
773 | ||
fd8aa909 | 774 | down_read(&xs_watch_rwsem); |
4bac07c9 JF |
775 | |
776 | spin_lock(&watches_lock); | |
777 | BUG_ON(find_watch(token)); | |
778 | list_add(&watch->list, &watches); | |
779 | spin_unlock(&watches_lock); | |
780 | ||
781 | err = xs_watch(watch->node, token); | |
782 | ||
c4c303c7 | 783 | if (err) { |
4bac07c9 JF |
784 | spin_lock(&watches_lock); |
785 | list_del(&watch->list); | |
786 | spin_unlock(&watches_lock); | |
787 | } | |
788 | ||
fd8aa909 | 789 | up_read(&xs_watch_rwsem); |
4bac07c9 JF |
790 | |
791 | return err; | |
792 | } | |
793 | EXPORT_SYMBOL_GPL(register_xenbus_watch); | |
794 | ||
795 | void unregister_xenbus_watch(struct xenbus_watch *watch) | |
796 | { | |
fd8aa909 | 797 | struct xs_watch_event *event, *tmp; |
4bac07c9 JF |
798 | char token[sizeof(watch) * 2 + 1]; |
799 | int err; | |
800 | ||
801 | sprintf(token, "%lX", (long)watch); | |
802 | ||
fd8aa909 | 803 | down_read(&xs_watch_rwsem); |
4bac07c9 JF |
804 | |
805 | spin_lock(&watches_lock); | |
806 | BUG_ON(!find_watch(token)); | |
807 | list_del(&watch->list); | |
808 | spin_unlock(&watches_lock); | |
809 | ||
810 | err = xs_unwatch(watch->node, token); | |
811 | if (err) | |
283c0972 | 812 | pr_warn("Failed to release watch %s: %i\n", watch->node, err); |
4bac07c9 | 813 | |
fd8aa909 | 814 | up_read(&xs_watch_rwsem); |
4bac07c9 JF |
815 | |
816 | /* Make sure there are no callbacks running currently (unless | |
817 | its us) */ | |
818 | if (current->pid != xenwatch_pid) | |
819 | mutex_lock(&xenwatch_mutex); | |
820 | ||
821 | /* Cancel pending watch events. */ | |
822 | spin_lock(&watch_events_lock); | |
3dc86ca6 SP |
823 | if (watch->nr_pending) { |
824 | list_for_each_entry_safe(event, tmp, &watch_events, list) { | |
825 | if (event->handle != watch) | |
826 | continue; | |
827 | list_del(&event->list); | |
828 | kfree(event); | |
829 | } | |
830 | watch->nr_pending = 0; | |
4bac07c9 JF |
831 | } |
832 | spin_unlock(&watch_events_lock); | |
833 | ||
834 | if (current->pid != xenwatch_pid) | |
835 | mutex_unlock(&xenwatch_mutex); | |
836 | } | |
837 | EXPORT_SYMBOL_GPL(unregister_xenbus_watch); | |
838 | ||
839 | void xs_suspend(void) | |
840 | { | |
fd8aa909 JG |
841 | xs_suspend_enter(); |
842 | ||
fd8aa909 | 843 | mutex_lock(&xs_response_mutex); |
442466e0 | 844 | down_write(&xs_watch_rwsem); |
4bac07c9 JF |
845 | } |
846 | ||
847 | void xs_resume(void) | |
848 | { | |
849 | struct xenbus_watch *watch; | |
850 | char token[sizeof(watch) * 2 + 1]; | |
851 | ||
de5b31bd IC |
852 | xb_init_comms(); |
853 | ||
fd8aa909 JG |
854 | mutex_unlock(&xs_response_mutex); |
855 | ||
856 | xs_suspend_exit(); | |
4bac07c9 | 857 | |
fd8aa909 | 858 | /* No need for watches_lock: the xs_watch_rwsem is sufficient. */ |
4bac07c9 JF |
859 | list_for_each_entry(watch, &watches, list) { |
860 | sprintf(token, "%lX", (long)watch); | |
861 | xs_watch(watch->node, token); | |
862 | } | |
863 | ||
fd8aa909 | 864 | up_write(&xs_watch_rwsem); |
4bac07c9 JF |
865 | } |
866 | ||
867 | void xs_suspend_cancel(void) | |
868 | { | |
fd8aa909 | 869 | up_write(&xs_watch_rwsem); |
442466e0 | 870 | mutex_unlock(&xs_response_mutex); |
fd8aa909 JG |
871 | |
872 | xs_suspend_exit(); | |
4bac07c9 JF |
873 | } |
874 | ||
875 | static int xenwatch_thread(void *unused) | |
876 | { | |
fd8aa909 | 877 | struct xs_watch_event *event; |
4bac07c9 | 878 | |
529871bb JG |
879 | xenwatch_pid = current->pid; |
880 | ||
4bac07c9 JF |
881 | for (;;) { |
882 | wait_event_interruptible(watch_events_waitq, | |
883 | !list_empty(&watch_events)); | |
884 | ||
885 | if (kthread_should_stop()) | |
886 | break; | |
887 | ||
888 | mutex_lock(&xenwatch_mutex); | |
889 | ||
890 | spin_lock(&watch_events_lock); | |
3dc86ca6 SP |
891 | event = list_first_entry_or_null(&watch_events, |
892 | struct xs_watch_event, list); | |
893 | if (event) { | |
894 | list_del(&event->list); | |
895 | event->handle->nr_pending--; | |
896 | } | |
4bac07c9 JF |
897 | spin_unlock(&watch_events_lock); |
898 | ||
3dc86ca6 | 899 | if (event) { |
fd8aa909 JG |
900 | event->handle->callback(event->handle, event->path, |
901 | event->token); | |
902 | kfree(event); | |
4bac07c9 JF |
903 | } |
904 | ||
905 | mutex_unlock(&xenwatch_mutex); | |
906 | } | |
907 | ||
908 | return 0; | |
909 | } | |
910 | ||
fd8aa909 JG |
911 | /* |
912 | * Wake up all threads waiting for a xenstore reply. In case of shutdown all | |
913 | * pending replies will be marked as "aborted" in order to let the waiters | |
914 | * return in spite of xenstore possibly no longer being able to reply. This | |
915 | * will avoid blocking shutdown by a thread waiting for xenstore but being | |
916 | * necessary for shutdown processing to proceed. | |
917 | */ | |
918 | static int xs_reboot_notify(struct notifier_block *nb, | |
919 | unsigned long code, void *unused) | |
4bac07c9 | 920 | { |
fd8aa909 | 921 | struct xb_req_data *req; |
4bac07c9 | 922 | |
fd8aa909 JG |
923 | mutex_lock(&xb_write_mutex); |
924 | list_for_each_entry(req, &xs_reply_list, list) | |
925 | wake_up(&req->wq); | |
926 | list_for_each_entry(req, &xb_write_list, list) | |
927 | wake_up(&req->wq); | |
928 | mutex_unlock(&xb_write_mutex); | |
929 | return NOTIFY_DONE; | |
4bac07c9 JF |
930 | } |
931 | ||
fd8aa909 JG |
932 | static struct notifier_block xs_reboot_nb = { |
933 | .notifier_call = xs_reboot_notify, | |
934 | }; | |
4bac07c9 JF |
935 | |
936 | int xs_init(void) | |
937 | { | |
938 | int err; | |
939 | struct task_struct *task; | |
940 | ||
fd8aa909 | 941 | register_reboot_notifier(&xs_reboot_nb); |
4bac07c9 JF |
942 | |
943 | /* Initialize the shared memory rings to talk to xenstored */ | |
944 | err = xb_init_comms(); | |
945 | if (err) | |
946 | return err; | |
947 | ||
948 | task = kthread_run(xenwatch_thread, NULL, "xenwatch"); | |
949 | if (IS_ERR(task)) | |
950 | return PTR_ERR(task); | |
4bac07c9 | 951 | |
254d1a3f OH |
952 | /* shutdown watches for kexec boot */ |
953 | xs_reset_watches(); | |
954 | ||
4bac07c9 JF |
955 | return 0; |
956 | } |