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 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
35 | |
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> |
46 | #include <linux/reboot.h> |
47 | #include <linux/rwsem.h> |
48 | #include <linux/mutex.h> |
49 | #include <asm/xen/hypervisor.h> |
50 | #include <xen/xenbus.h> |
51 | #include <xen/xen.h> |
52 | #include "xenbus.h" |
53 | |
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 | */ |
62 | |
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; |
71 | |
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); |
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 | |
85 | /* Protect watch (de)register against save/restore. */ |
86 | static DECLARE_RWSEM(xs_watch_rwsem); |
87 | |
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 | |
98 | static void xs_suspend_enter(void) |
99 | { |
100 | spin_lock(lock: &xs_state_lock); |
101 | xs_suspend_active++; |
102 | spin_unlock(lock: &xs_state_lock); |
103 | wait_event(xs_state_exit_wq, xs_state_users == 0); |
104 | } |
105 | |
106 | static void xs_suspend_exit(void) |
107 | { |
108 | xb_dev_generation_id++; |
109 | spin_lock(lock: &xs_state_lock); |
110 | xs_suspend_active--; |
111 | spin_unlock(lock: &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(lock: &xs_state_lock); |
122 | |
123 | while (!xs_state_users && xs_suspend_active) { |
124 | spin_unlock(lock: &xs_state_lock); |
125 | wait_event(xs_state_enter_wq, xs_suspend_active == 0); |
126 | spin_lock(lock: &xs_state_lock); |
127 | } |
128 | |
129 | if (req->type == XS_TRANSACTION_START && !req->user_req) |
130 | xs_state_users++; |
131 | xs_state_users++; |
132 | rq_id = xs_request_id++; |
133 | |
134 | spin_unlock(lock: &xs_state_lock); |
135 | |
136 | return rq_id; |
137 | } |
138 | |
139 | void xs_request_exit(struct xb_req_data *req) |
140 | { |
141 | spin_lock(lock: &xs_state_lock); |
142 | xs_state_users--; |
143 | if ((req->type == XS_TRANSACTION_START && req->msg.type == XS_ERROR) || |
144 | (req->type == XS_TRANSACTION_END && !req->user_req && |
145 | !WARN_ON_ONCE(req->msg.type == XS_ERROR && |
146 | !strcmp(req->body, "ENOENT" )))) |
147 | xs_state_users--; |
148 | spin_unlock(lock: &xs_state_lock); |
149 | |
150 | if (xs_suspend_active && !xs_state_users) |
151 | wake_up(&xs_state_exit_wq); |
152 | } |
153 | |
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) { |
160 | pr_warn("xen store gave: unknown error %s\n" , |
161 | errorstring); |
162 | return EINVAL; |
163 | } |
164 | } |
165 | return xsd_errors[i].errnum; |
166 | } |
167 | |
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 | } |
191 | |
192 | static bool test_reply(struct xb_req_data *req) |
193 | { |
194 | if (req->state == xb_req_state_got_reply || !xenbus_ok()) { |
195 | /* read req->state before all other fields */ |
196 | virt_rmb(); |
197 | return true; |
198 | } |
199 | |
200 | /* Make sure to reread req->state each time. */ |
201 | barrier(); |
202 | |
203 | return false; |
204 | } |
205 | |
206 | static void *read_reply(struct xb_req_data *req) |
207 | { |
208 | do { |
209 | wait_event(req->wq, test_reply(req)); |
210 | |
211 | if (!xenbus_ok()) |
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(error: -EIO); |
219 | if (req->err) |
220 | return ERR_PTR(error: req->err); |
221 | |
222 | } while (req->state != xb_req_state_got_reply); |
223 | |
224 | return req->body; |
225 | } |
226 | |
227 | static void xs_send(struct xb_req_data *req, struct xsd_sockmsg *msg) |
228 | { |
229 | bool notify; |
230 | |
231 | req->msg = *msg; |
232 | req->err = 0; |
233 | req->state = xb_req_state_queued; |
234 | init_waitqueue_head(&req->wq); |
235 | |
236 | /* Save the caller req_id and restore it later in the reply */ |
237 | req->caller_req_id = req->msg.req_id; |
238 | req->msg.req_id = xs_request_enter(req); |
239 | |
240 | mutex_lock(&xb_write_mutex); |
241 | list_add_tail(new: &req->list, head: &xb_write_list); |
242 | notify = list_is_singular(head: &xb_write_list); |
243 | mutex_unlock(lock: &xb_write_mutex); |
244 | |
245 | if (notify) |
246 | wake_up(&xb_waitq); |
247 | } |
248 | |
249 | static void *xs_wait_for_reply(struct xb_req_data *req, struct xsd_sockmsg *msg) |
250 | { |
251 | void *ret; |
252 | |
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(objp: req); |
266 | mutex_unlock(lock: &xb_write_mutex); |
267 | |
268 | return ret; |
269 | } |
270 | |
271 | static void xs_wake_up(struct xb_req_data *req) |
272 | { |
273 | wake_up(&req->wq); |
274 | } |
275 | |
276 | int xenbus_dev_request_and_reply(struct xsd_sockmsg *msg, void *par) |
277 | { |
278 | struct xb_req_data *req; |
279 | struct kvec *vec; |
280 | |
281 | req = kmalloc(size: sizeof(*req) + sizeof(*vec), GFP_KERNEL); |
282 | if (!req) |
283 | return -ENOMEM; |
284 | |
285 | vec = (struct kvec *)(req + 1); |
286 | vec->iov_len = msg->len; |
287 | vec->iov_base = msg + 1; |
288 | |
289 | req->vec = vec; |
290 | req->num_vecs = 1; |
291 | req->cb = xenbus_dev_queue_reply; |
292 | req->par = par; |
293 | req->user_req = true; |
294 | |
295 | xs_send(req, msg); |
296 | |
297 | return 0; |
298 | } |
299 | EXPORT_SYMBOL(xenbus_dev_request_and_reply); |
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 | { |
308 | struct xb_req_data *req; |
309 | struct xsd_sockmsg msg; |
310 | void *ret = NULL; |
311 | unsigned int i; |
312 | int err; |
313 | |
314 | req = kmalloc(size: sizeof(*req), GFP_NOIO | __GFP_HIGH); |
315 | if (!req) |
316 | return ERR_PTR(error: -ENOMEM); |
317 | |
318 | req->vec = iovec; |
319 | req->num_vecs = num_vecs; |
320 | req->cb = xs_wake_up; |
321 | req->user_req = false; |
322 | |
323 | msg.req_id = 0; |
324 | msg.tx_id = t.id; |
325 | msg.type = type; |
326 | msg.len = 0; |
327 | for (i = 0; i < num_vecs; i++) |
328 | msg.len += iovec[i].iov_len; |
329 | |
330 | xs_send(req, msg: &msg); |
331 | |
332 | ret = xs_wait_for_reply(req, msg: &msg); |
333 | if (len) |
334 | *len = msg.len; |
335 | |
336 | if (IS_ERR(ptr: ret)) |
337 | return ret; |
338 | |
339 | if (msg.type == XS_ERROR) { |
340 | err = get_error(errorstring: ret); |
341 | kfree(objp: ret); |
342 | return ERR_PTR(error: -err); |
343 | } |
344 | |
345 | if (msg.type != type) { |
346 | pr_warn_ratelimited("unexpected type [%d], expected [%d]\n" , |
347 | msg.type, type); |
348 | kfree(objp: ret); |
349 | return ERR_PTR(error: -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: &iovec, num_vecs: 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(ptr: reply)) |
371 | return PTR_ERR(ptr: reply); |
372 | kfree(objp: 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) |
393 | buffer = kasprintf(GFP_NOIO | __GFP_HIGH, fmt: "%s" , dir); |
394 | else |
395 | buffer = kasprintf(GFP_NOIO | __GFP_HIGH, fmt: "%s/%s" , dir, name); |
396 | return (!buffer) ? ERR_PTR(error: -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. */ |
407 | ret = kmalloc(size: *num * sizeof(char *) + len, GFP_NOIO | __GFP_HIGH); |
408 | if (!ret) { |
409 | kfree(objp: strings); |
410 | return ERR_PTR(error: -ENOMEM); |
411 | } |
412 | memcpy(&ret[*num], strings, len); |
413 | kfree(objp: 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, name: node); |
429 | if (IS_ERR(ptr: path)) |
430 | return (char **)path; |
431 | |
432 | strings = xs_single(t, type: XS_DIRECTORY, string: path, len: &len); |
433 | kfree(objp: path); |
434 | if (IS_ERR(ptr: strings)) |
435 | return (char **)strings; |
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(ptr: d)) |
450 | return 0; |
451 | kfree(objp: 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, name: node); |
467 | if (IS_ERR(ptr: path)) |
468 | return (void *)path; |
469 | |
470 | ret = xs_single(t, type: XS_READ, string: path, len); |
471 | kfree(objp: 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, name: node); |
487 | if (IS_ERR(ptr: path)) |
488 | return PTR_ERR(ptr: 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(reply: xs_talkv(t, type: XS_WRITE, iovec, ARRAY_SIZE(iovec), NULL)); |
496 | kfree(objp: 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, name: node); |
509 | if (IS_ERR(ptr: path)) |
510 | return PTR_ERR(ptr: path); |
511 | |
512 | ret = xs_error(reply: xs_single(t, type: XS_MKDIR, string: path, NULL)); |
513 | kfree(objp: 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, name: node); |
525 | if (IS_ERR(ptr: path)) |
526 | return PTR_ERR(ptr: path); |
527 | |
528 | ret = xs_error(reply: xs_single(t, type: XS_RM, string: path, NULL)); |
529 | kfree(objp: 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 | |
541 | id_str = xs_single(XBT_NIL, type: XS_TRANSACTION_START, string: "" , NULL); |
542 | if (IS_ERR(id_str)) |
543 | return PTR_ERR(id_str); |
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]; |
557 | |
558 | if (abort) |
559 | strcpy(p: abortstr, q: "F" ); |
560 | else |
561 | strcpy(p: abortstr, q: "T" ); |
562 | |
563 | return xs_error(reply: xs_single(t, type: XS_TRANSACTION_END, string: abortstr, NULL)); |
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(ptr: val)) |
577 | return PTR_ERR(ptr: val); |
578 | |
579 | va_start(ap, fmt); |
580 | ret = vsscanf(val, fmt, ap); |
581 | va_end(ap); |
582 | kfree(objp: val); |
583 | /* Distinctive errno. */ |
584 | if (ret == 0) |
585 | return -ERANGE; |
586 | return ret; |
587 | } |
588 | EXPORT_SYMBOL_GPL(xenbus_scanf); |
589 | |
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 | |
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; |
611 | char *buf; |
612 | |
613 | va_start(ap, fmt); |
614 | buf = kvasprintf(GFP_NOIO | __GFP_HIGH, fmt, args: ap); |
615 | va_end(ap); |
616 | |
617 | if (!buf) |
618 | return -ENOMEM; |
619 | |
620 | ret = xenbus_write(t, dir, node, buf); |
621 | |
622 | kfree(objp: buf); |
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(ptr: p)) { |
643 | ret = PTR_ERR(ptr: p); |
644 | break; |
645 | } |
646 | if (fmt) { |
647 | if (sscanf(p, fmt, result) == 0) |
648 | ret = -EINVAL; |
649 | kfree(objp: 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(reply: xs_talkv(XBT_NIL, type: XS_WATCH, iovec: 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(reply: xs_talkv(XBT_NIL, type: XS_UNWATCH, iovec: 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 | } |
696 | |
697 | int xs_watch_msg(struct xs_watch_event *event) |
698 | { |
699 | if (count_strings(strings: event->body, len: event->len) != 2) { |
700 | kfree(objp: 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(lock: &watches_lock); |
707 | event->handle = find_watch(token: event->token); |
708 | if (event->handle != NULL && |
709 | (!event->handle->will_handle || |
710 | event->handle->will_handle(event->handle, |
711 | event->path, event->token))) { |
712 | spin_lock(lock: &watch_events_lock); |
713 | list_add_tail(new: &event->list, head: &watch_events); |
714 | event->handle->nr_pending++; |
715 | wake_up(&watch_events_waitq); |
716 | spin_unlock(lock: &watch_events_lock); |
717 | } else |
718 | kfree(objp: event); |
719 | spin_unlock(lock: &watches_lock); |
720 | |
721 | return 0; |
722 | } |
723 | |
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 | */ |
730 | static bool xen_strict_xenbus_quirk(void) |
731 | { |
732 | #ifdef CONFIG_X86 |
733 | uint32_t eax, ebx, ecx, edx, base; |
734 | |
735 | base = xen_cpuid_base(); |
736 | cpuid(op: base + 1, eax: &eax, ebx: &ebx, ecx: &ecx, edx: &edx); |
737 | |
738 | if ((eax >> 16) < 4) |
739 | return true; |
740 | #endif |
741 | return false; |
742 | |
743 | } |
744 | static void xs_reset_watches(void) |
745 | { |
746 | int err; |
747 | |
748 | if (!xen_hvm_domain() || xen_initial_domain()) |
749 | return; |
750 | |
751 | if (xen_strict_xenbus_quirk()) |
752 | return; |
753 | |
754 | if (!xenbus_read_unsigned("control" , |
755 | "platform-feature-xs_reset_watches" , 0)) |
756 | return; |
757 | |
758 | err = xs_error(reply: xs_single(XBT_NIL, type: XS_RESET_WATCHES, string: "" , NULL)); |
759 | if (err && err != -EEXIST) |
760 | pr_warn("xs_reset_watches failed: %d\n" , err); |
761 | } |
762 | |
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(buf: token, fmt: "%lX" , (long)watch); |
771 | |
772 | watch->nr_pending = 0; |
773 | |
774 | down_read(sem: &xs_watch_rwsem); |
775 | |
776 | spin_lock(lock: &watches_lock); |
777 | BUG_ON(find_watch(token)); |
778 | list_add(new: &watch->list, head: &watches); |
779 | spin_unlock(lock: &watches_lock); |
780 | |
781 | err = xs_watch(path: watch->node, token); |
782 | |
783 | if (err) { |
784 | spin_lock(lock: &watches_lock); |
785 | list_del(entry: &watch->list); |
786 | spin_unlock(lock: &watches_lock); |
787 | } |
788 | |
789 | up_read(sem: &xs_watch_rwsem); |
790 | |
791 | return err; |
792 | } |
793 | EXPORT_SYMBOL_GPL(register_xenbus_watch); |
794 | |
795 | void unregister_xenbus_watch(struct xenbus_watch *watch) |
796 | { |
797 | struct xs_watch_event *event, *tmp; |
798 | char token[sizeof(watch) * 2 + 1]; |
799 | int err; |
800 | |
801 | sprintf(buf: token, fmt: "%lX" , (long)watch); |
802 | |
803 | down_read(sem: &xs_watch_rwsem); |
804 | |
805 | spin_lock(lock: &watches_lock); |
806 | BUG_ON(!find_watch(token)); |
807 | list_del(entry: &watch->list); |
808 | spin_unlock(lock: &watches_lock); |
809 | |
810 | err = xs_unwatch(path: watch->node, token); |
811 | if (err) |
812 | pr_warn("Failed to release watch %s: %i\n" , watch->node, err); |
813 | |
814 | up_read(sem: &xs_watch_rwsem); |
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(lock: &watch_events_lock); |
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(entry: &event->list); |
828 | kfree(objp: event); |
829 | } |
830 | watch->nr_pending = 0; |
831 | } |
832 | spin_unlock(lock: &watch_events_lock); |
833 | |
834 | if (current->pid != xenwatch_pid) |
835 | mutex_unlock(lock: &xenwatch_mutex); |
836 | } |
837 | EXPORT_SYMBOL_GPL(unregister_xenbus_watch); |
838 | |
839 | void xs_suspend(void) |
840 | { |
841 | xs_suspend_enter(); |
842 | |
843 | mutex_lock(&xs_response_mutex); |
844 | down_write(sem: &xs_watch_rwsem); |
845 | } |
846 | |
847 | void xs_resume(void) |
848 | { |
849 | struct xenbus_watch *watch; |
850 | char token[sizeof(watch) * 2 + 1]; |
851 | |
852 | xb_init_comms(); |
853 | |
854 | mutex_unlock(lock: &xs_response_mutex); |
855 | |
856 | xs_suspend_exit(); |
857 | |
858 | /* No need for watches_lock: the xs_watch_rwsem is sufficient. */ |
859 | list_for_each_entry(watch, &watches, list) { |
860 | sprintf(buf: token, fmt: "%lX" , (long)watch); |
861 | xs_watch(path: watch->node, token); |
862 | } |
863 | |
864 | up_write(sem: &xs_watch_rwsem); |
865 | } |
866 | |
867 | void xs_suspend_cancel(void) |
868 | { |
869 | up_write(sem: &xs_watch_rwsem); |
870 | mutex_unlock(lock: &xs_response_mutex); |
871 | |
872 | xs_suspend_exit(); |
873 | } |
874 | |
875 | static int xenwatch_thread(void *unused) |
876 | { |
877 | struct xs_watch_event *event; |
878 | |
879 | xenwatch_pid = current->pid; |
880 | |
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(lock: &watch_events_lock); |
891 | event = list_first_entry_or_null(&watch_events, |
892 | struct xs_watch_event, list); |
893 | if (event) { |
894 | list_del(entry: &event->list); |
895 | event->handle->nr_pending--; |
896 | } |
897 | spin_unlock(lock: &watch_events_lock); |
898 | |
899 | if (event) { |
900 | event->handle->callback(event->handle, event->path, |
901 | event->token); |
902 | kfree(objp: event); |
903 | } |
904 | |
905 | mutex_unlock(lock: &xenwatch_mutex); |
906 | } |
907 | |
908 | return 0; |
909 | } |
910 | |
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) |
920 | { |
921 | struct xb_req_data *req; |
922 | |
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(lock: &xb_write_mutex); |
929 | return NOTIFY_DONE; |
930 | } |
931 | |
932 | static struct notifier_block xs_reboot_nb = { |
933 | .notifier_call = xs_reboot_notify, |
934 | }; |
935 | |
936 | int xs_init(void) |
937 | { |
938 | int err; |
939 | struct task_struct *task; |
940 | |
941 | register_reboot_notifier(&xs_reboot_nb); |
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(ptr: task)) |
950 | return PTR_ERR(ptr: task); |
951 | |
952 | /* shutdown watches for kexec boot */ |
953 | xs_reset_watches(); |
954 | |
955 | return 0; |
956 | } |
957 | |