root/drivers/xen/xenbus/xenbus_probe.c

DEFINITIONS

1. match_device
2. xenbus_match
3. free_otherend_details
4. free_otherend_watch
5. talk_to_otherend
6. watch_otherend
7. xenbus_read_otherend_details
8. xenbus_otherend_changed
9. xenbus_dev_probe
10. xenbus_dev_remove
11. xenbus_dev_shutdown
12. xenbus_register_driver_common
13. xenbus_unregister_driver
14. cmp_dev
15. xenbus_device_find
16. cleanup_dev
17. xenbus_cleanup_devices
18. xenbus_dev_release
19. nodename_show
20. devtype_show
21. modalias_show
22. state_show
23. xenbus_probe_node
24. xenbus_probe_device_type
25. xenbus_probe_devices
26. char_count
27. strsep_len
28. xenbus_dev_changed
29. xenbus_dev_suspend
30. xenbus_dev_resume
31. xenbus_dev_cancel
32. register_xenstore_notifier
33. unregister_xenstore_notifier
34. xenbus_probe
35. xenbus_probe_initcall
36. xenstored_local_init
37. xenbus_resume_cb
38. xenbus_init

   1 /******************************************************************************
   2  * Talks to Xen Store to figure out what devices we have.
   3  *
   4  * Copyright (C) 2005 Rusty Russell, IBM Corporation
   5  * Copyright (C) 2005 Mike Wray, Hewlett-Packard
   6  * Copyright (C) 2005, 2006 XenSource Ltd
   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 
  33 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  34 
  35 #define DPRINTK(fmt, args...)                           \
  36         pr_debug("xenbus_probe (%s:%d) " fmt ".\n",     \
  37                  __func__, __LINE__, ##args)
  38 
  39 #include <linux/kernel.h>
  40 #include <linux/err.h>
  41 #include <linux/string.h>
  42 #include <linux/ctype.h>
  43 #include <linux/fcntl.h>
  44 #include <linux/mm.h>
  45 #include <linux/proc_fs.h>
  46 #include <linux/notifier.h>
  47 #include <linux/kthread.h>
  48 #include <linux/mutex.h>
  49 #include <linux/io.h>
  50 #include <linux/slab.h>
  51 #include <linux/module.h>
  52 
  53 #include <asm/page.h>
  54 #include <asm/pgtable.h>
  55 #include <asm/xen/hypervisor.h>
  56 
  57 #include <xen/xen.h>
  58 #include <xen/xenbus.h>
  59 #include <xen/events.h>
  60 #include <xen/xen-ops.h>
  61 #include <xen/page.h>
  62 
  63 #include <xen/hvm.h>
  64 
  65 #include "xenbus.h"
  66 
  67 
  68 int xen_store_evtchn;
  69 EXPORT_SYMBOL_GPL(xen_store_evtchn);
  70 
  71 struct xenstore_domain_interface *xen_store_interface;
  72 EXPORT_SYMBOL_GPL(xen_store_interface);
  73 
  74 enum xenstore_init xen_store_domain_type;
  75 EXPORT_SYMBOL_GPL(xen_store_domain_type);
  76 
  77 static unsigned long xen_store_gfn;
  78 
  79 static BLOCKING_NOTIFIER_HEAD(xenstore_chain);
  80 
  81 /* If something in array of ids matches this device, return it. */
  82 static const struct xenbus_device_id *
  83 match_device(const struct xenbus_device_id *arr, struct xenbus_device *dev)
  84 {
  85         for (; *arr->devicetype != '\0'; arr++) {
  86                 if (!strcmp(arr->devicetype, dev->devicetype))
  87                         return arr;
  88         }
  89         return NULL;
  90 }
  91 
  92 int xenbus_match(struct device *_dev, struct device_driver *_drv)
  93 {
  94         struct xenbus_driver *drv = to_xenbus_driver(_drv);
  95 
  96         if (!drv->ids)
  97                 return 0;
  98 
  99         return match_device(drv->ids, to_xenbus_device(_dev)) != NULL;
 100 }
 101 EXPORT_SYMBOL_GPL(xenbus_match);
 102 
 103 
 104 static void free_otherend_details(struct xenbus_device *dev)
 105 {
 106         kfree(dev->otherend);
 107         dev->otherend = NULL;
 108 }
 109 
 110 
 111 static void free_otherend_watch(struct xenbus_device *dev)
 112 {
 113         if (dev->otherend_watch.node) {
 114                 unregister_xenbus_watch(&dev->otherend_watch);
 115                 kfree(dev->otherend_watch.node);
 116                 dev->otherend_watch.node = NULL;
 117         }
 118 }
 119 
 120 
 121 static int talk_to_otherend(struct xenbus_device *dev)
 122 {
 123         struct xenbus_driver *drv = to_xenbus_driver(dev->dev.driver);
 124 
 125         free_otherend_watch(dev);
 126         free_otherend_details(dev);
 127 
 128         return drv->read_otherend_details(dev);
 129 }
 130 
 131 
 132 
 133 static int watch_otherend(struct xenbus_device *dev)
 134 {
 135         struct xen_bus_type *bus =
 136                 container_of(dev->dev.bus, struct xen_bus_type, bus);
 137 
 138         return xenbus_watch_pathfmt(dev, &dev->otherend_watch,
 139                                     bus->otherend_changed,
 140                                     "%s/%s", dev->otherend, "state");
 141 }
 142 
 143 
 144 int xenbus_read_otherend_details(struct xenbus_device *xendev,
 145                                  char *id_node, char *path_node)
 146 {
 147         int err = xenbus_gather(XBT_NIL, xendev->nodename,
 148                                 id_node, "%i", &xendev->otherend_id,
 149                                 path_node, NULL, &xendev->otherend,
 150                                 NULL);
 151         if (err) {
 152                 xenbus_dev_fatal(xendev, err,
 153                                  "reading other end details from %s",
 154                                  xendev->nodename);
 155                 return err;
 156         }
 157         if (strlen(xendev->otherend) == 0 ||
 158             !xenbus_exists(XBT_NIL, xendev->otherend, "")) {
 159                 xenbus_dev_fatal(xendev, -ENOENT,
 160                                  "unable to read other end from %s.  "
 161                                  "missing or inaccessible.",
 162                                  xendev->nodename);
 163                 free_otherend_details(xendev);
 164                 return -ENOENT;
 165         }
 166 
 167         return 0;
 168 }
 169 EXPORT_SYMBOL_GPL(xenbus_read_otherend_details);
 170 
 171 void xenbus_otherend_changed(struct xenbus_watch *watch,
 172                              const char *path, const char *token,
 173                              int ignore_on_shutdown)
 174 {
 175         struct xenbus_device *dev =
 176                 container_of(watch, struct xenbus_device, otherend_watch);
 177         struct xenbus_driver *drv = to_xenbus_driver(dev->dev.driver);
 178         enum xenbus_state state;
 179 
 180         /* Protect us against watches firing on old details when the otherend
 181            details change, say immediately after a resume. */
 182         if (!dev->otherend ||
 183             strncmp(dev->otherend, path, strlen(dev->otherend))) {
 184                 dev_dbg(&dev->dev, "Ignoring watch at %s\n", path);
 185                 return;
 186         }
 187 
 188         state = xenbus_read_driver_state(dev->otherend);
 189 
 190         dev_dbg(&dev->dev, "state is %d, (%s), %s, %s\n",
 191                 state, xenbus_strstate(state), dev->otherend_watch.node, path);
 192 
 193         /*
 194          * Ignore xenbus transitions during shutdown. This prevents us doing
 195          * work that can fail e.g., when the rootfs is gone.
 196          */
 197         if (system_state > SYSTEM_RUNNING) {
 198                 if (ignore_on_shutdown && (state == XenbusStateClosing))
 199                         xenbus_frontend_closed(dev);
 200                 return;
 201         }
 202 
 203         if (drv->otherend_changed)
 204                 drv->otherend_changed(dev, state);
 205 }
 206 EXPORT_SYMBOL_GPL(xenbus_otherend_changed);
 207 
 208 int xenbus_dev_probe(struct device *_dev)
 209 {
 210         struct xenbus_device *dev = to_xenbus_device(_dev);
 211         struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
 212         const struct xenbus_device_id *id;
 213         int err;
 214 
 215         DPRINTK("%s", dev->nodename);
 216 
 217         if (!drv->probe) {
 218                 err = -ENODEV;
 219                 goto fail;
 220         }
 221 
 222         id = match_device(drv->ids, dev);
 223         if (!id) {
 224                 err = -ENODEV;
 225                 goto fail;
 226         }
 227 
 228         err = talk_to_otherend(dev);
 229         if (err) {
 230                 dev_warn(&dev->dev, "talk_to_otherend on %s failed.\n",
 231                          dev->nodename);
 232                 return err;
 233         }
 234 
 235         err = drv->probe(dev, id);
 236         if (err)
 237                 goto fail;
 238 
 239         err = watch_otherend(dev);
 240         if (err) {
 241                 dev_warn(&dev->dev, "watch_otherend on %s failed.\n",
 242                        dev->nodename);
 243                 return err;
 244         }
 245 
 246         return 0;
 247 fail:
 248         xenbus_dev_error(dev, err, "xenbus_dev_probe on %s", dev->nodename);
 249         xenbus_switch_state(dev, XenbusStateClosed);
 250         return err;
 251 }
 252 EXPORT_SYMBOL_GPL(xenbus_dev_probe);
 253 
 254 int xenbus_dev_remove(struct device *_dev)
 255 {
 256         struct xenbus_device *dev = to_xenbus_device(_dev);
 257         struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
 258 
 259         DPRINTK("%s", dev->nodename);
 260 
 261         free_otherend_watch(dev);
 262 
 263         if (drv->remove)
 264                 drv->remove(dev);
 265 
 266         free_otherend_details(dev);
 267 
 268         xenbus_switch_state(dev, XenbusStateClosed);
 269         return 0;
 270 }
 271 EXPORT_SYMBOL_GPL(xenbus_dev_remove);
 272 
 273 void xenbus_dev_shutdown(struct device *_dev)
 274 {
 275         struct xenbus_device *dev = to_xenbus_device(_dev);
 276         unsigned long timeout = 5*HZ;
 277 
 278         DPRINTK("%s", dev->nodename);
 279 
 280         get_device(&dev->dev);
 281         if (dev->state != XenbusStateConnected) {
 282                 pr_info("%s: %s: %s != Connected, skipping\n",
 283                         __func__, dev->nodename, xenbus_strstate(dev->state));
 284                 goto out;
 285         }
 286         xenbus_switch_state(dev, XenbusStateClosing);
 287         timeout = wait_for_completion_timeout(&dev->down, timeout);
 288         if (!timeout)
 289                 pr_info("%s: %s timeout closing device\n",
 290                         __func__, dev->nodename);
 291  out:
 292         put_device(&dev->dev);
 293 }
 294 EXPORT_SYMBOL_GPL(xenbus_dev_shutdown);
 295 
 296 int xenbus_register_driver_common(struct xenbus_driver *drv,
 297                                   struct xen_bus_type *bus,
 298                                   struct module *owner, const char *mod_name)
 299 {
 300         drv->driver.name = drv->name ? drv->name : drv->ids[0].devicetype;
 301         drv->driver.bus = &bus->bus;
 302         drv->driver.owner = owner;
 303         drv->driver.mod_name = mod_name;
 304 
 305         return driver_register(&drv->driver);
 306 }
 307 EXPORT_SYMBOL_GPL(xenbus_register_driver_common);
 308 
 309 void xenbus_unregister_driver(struct xenbus_driver *drv)
 310 {
 311         driver_unregister(&drv->driver);
 312 }
 313 EXPORT_SYMBOL_GPL(xenbus_unregister_driver);
 314 
 315 struct xb_find_info {
 316         struct xenbus_device *dev;
 317         const char *nodename;
 318 };
 319 
 320 static int cmp_dev(struct device *dev, void *data)
 321 {
 322         struct xenbus_device *xendev = to_xenbus_device(dev);
 323         struct xb_find_info *info = data;
 324 
 325         if (!strcmp(xendev->nodename, info->nodename)) {
 326                 info->dev = xendev;
 327                 get_device(dev);
 328                 return 1;
 329         }
 330         return 0;
 331 }
 332 
 333 static struct xenbus_device *xenbus_device_find(const char *nodename,
 334                                                 struct bus_type *bus)
 335 {
 336         struct xb_find_info info = { .dev = NULL, .nodename = nodename };
 337 
 338         bus_for_each_dev(bus, NULL, &info, cmp_dev);
 339         return info.dev;
 340 }
 341 
 342 static int cleanup_dev(struct device *dev, void *data)
 343 {
 344         struct xenbus_device *xendev = to_xenbus_device(dev);
 345         struct xb_find_info *info = data;
 346         int len = strlen(info->nodename);
 347 
 348         DPRINTK("%s", info->nodename);
 349 
 350         /* Match the info->nodename path, or any subdirectory of that path. */
 351         if (strncmp(xendev->nodename, info->nodename, len))
 352                 return 0;
 353 
 354         /* If the node name is longer, ensure it really is a subdirectory. */
 355         if ((strlen(xendev->nodename) > len) && (xendev->nodename[len] != '/'))
 356                 return 0;
 357 
 358         info->dev = xendev;
 359         get_device(dev);
 360         return 1;
 361 }
 362 
 363 static void xenbus_cleanup_devices(const char *path, struct bus_type *bus)
 364 {
 365         struct xb_find_info info = { .nodename = path };
 366 
 367         do {
 368                 info.dev = NULL;
 369                 bus_for_each_dev(bus, NULL, &info, cleanup_dev);
 370                 if (info.dev) {
 371                         device_unregister(&info.dev->dev);
 372                         put_device(&info.dev->dev);
 373                 }
 374         } while (info.dev);
 375 }
 376 
 377 static void xenbus_dev_release(struct device *dev)
 378 {
 379         if (dev)
 380                 kfree(to_xenbus_device(dev));
 381 }
 382 
 383 static ssize_t nodename_show(struct device *dev,
 384                              struct device_attribute *attr, char *buf)
 385 {
 386         return sprintf(buf, "%s\n", to_xenbus_device(dev)->nodename);
 387 }
 388 static DEVICE_ATTR_RO(nodename);
 389 
 390 static ssize_t devtype_show(struct device *dev,
 391                             struct device_attribute *attr, char *buf)
 392 {
 393         return sprintf(buf, "%s\n", to_xenbus_device(dev)->devicetype);
 394 }
 395 static DEVICE_ATTR_RO(devtype);
 396 
 397 static ssize_t modalias_show(struct device *dev,
 398                              struct device_attribute *attr, char *buf)
 399 {
 400         return sprintf(buf, "%s:%s\n", dev->bus->name,
 401                        to_xenbus_device(dev)->devicetype);
 402 }
 403 static DEVICE_ATTR_RO(modalias);
 404 
 405 static ssize_t state_show(struct device *dev,
 406                             struct device_attribute *attr, char *buf)
 407 {
 408         return sprintf(buf, "%s\n",
 409                         xenbus_strstate(to_xenbus_device(dev)->state));
 410 }
 411 static DEVICE_ATTR_RO(state);
 412 
 413 static struct attribute *xenbus_dev_attrs[] = {
 414         &dev_attr_nodename.attr,
 415         &dev_attr_devtype.attr,
 416         &dev_attr_modalias.attr,
 417         &dev_attr_state.attr,
 418         NULL,
 419 };
 420 
 421 static const struct attribute_group xenbus_dev_group = {
 422         .attrs = xenbus_dev_attrs,
 423 };
 424 
 425 const struct attribute_group *xenbus_dev_groups[] = {
 426         &xenbus_dev_group,
 427         NULL,
 428 };
 429 EXPORT_SYMBOL_GPL(xenbus_dev_groups);
 430 
 431 int xenbus_probe_node(struct xen_bus_type *bus,
 432                       const char *type,
 433                       const char *nodename)
 434 {
 435         char devname[XEN_BUS_ID_SIZE];
 436         int err;
 437         struct xenbus_device *xendev;
 438         size_t stringlen;
 439         char *tmpstring;
 440 
 441         enum xenbus_state state = xenbus_read_driver_state(nodename);
 442 
 443         if (state != XenbusStateInitialising) {
 444                 /* Device is not new, so ignore it.  This can happen if a
 445                    device is going away after switching to Closed.  */
 446                 return 0;
 447         }
 448 
 449         stringlen = strlen(nodename) + 1 + strlen(type) + 1;
 450         xendev = kzalloc(sizeof(*xendev) + stringlen, GFP_KERNEL);
 451         if (!xendev)
 452                 return -ENOMEM;
 453 
 454         xendev->state = XenbusStateInitialising;
 455 
 456         /* Copy the strings into the extra space. */
 457 
 458         tmpstring = (char *)(xendev + 1);
 459         strcpy(tmpstring, nodename);
 460         xendev->nodename = tmpstring;
 461 
 462         tmpstring += strlen(tmpstring) + 1;
 463         strcpy(tmpstring, type);
 464         xendev->devicetype = tmpstring;
 465         init_completion(&xendev->down);
 466 
 467         xendev->dev.bus = &bus->bus;
 468         xendev->dev.release = xenbus_dev_release;
 469 
 470         err = bus->get_bus_id(devname, xendev->nodename);
 471         if (err)
 472                 goto fail;
 473 
 474         dev_set_name(&xendev->dev, "%s", devname);
 475 
 476         /* Register with generic device framework. */
 477         err = device_register(&xendev->dev);
 478         if (err) {
 479                 put_device(&xendev->dev);
 480                 xendev = NULL;
 481                 goto fail;
 482         }
 483 
 484         return 0;
 485 fail:
 486         kfree(xendev);
 487         return err;
 488 }
 489 EXPORT_SYMBOL_GPL(xenbus_probe_node);
 490 
 491 static int xenbus_probe_device_type(struct xen_bus_type *bus, const char *type)
 492 {
 493         int err = 0;
 494         char **dir;
 495         unsigned int dir_n = 0;
 496         int i;
 497 
 498         dir = xenbus_directory(XBT_NIL, bus->root, type, &dir_n);
 499         if (IS_ERR(dir))
 500                 return PTR_ERR(dir);
 501 
 502         for (i = 0; i < dir_n; i++) {
 503                 err = bus->probe(bus, type, dir[i]);
 504                 if (err)
 505                         break;
 506         }
 507 
 508         kfree(dir);
 509         return err;
 510 }
 511 
 512 int xenbus_probe_devices(struct xen_bus_type *bus)
 513 {
 514         int err = 0;
 515         char **dir;
 516         unsigned int i, dir_n;
 517 
 518         dir = xenbus_directory(XBT_NIL, bus->root, "", &dir_n);
 519         if (IS_ERR(dir))
 520                 return PTR_ERR(dir);
 521 
 522         for (i = 0; i < dir_n; i++) {
 523                 err = xenbus_probe_device_type(bus, dir[i]);
 524                 if (err)
 525                         break;
 526         }
 527 
 528         kfree(dir);
 529         return err;
 530 }
 531 EXPORT_SYMBOL_GPL(xenbus_probe_devices);
 532 
 533 static unsigned int char_count(const char *str, char c)
 534 {
 535         unsigned int i, ret = 0;
 536 
 537         for (i = 0; str[i]; i++)
 538                 if (str[i] == c)
 539                         ret++;
 540         return ret;
 541 }
 542 
 543 static int strsep_len(const char *str, char c, unsigned int len)
 544 {
 545         unsigned int i;
 546 
 547         for (i = 0; str[i]; i++)
 548                 if (str[i] == c) {
 549                         if (len == 0)
 550                                 return i;
 551                         len--;
 552                 }
 553         return (len == 0) ? i : -ERANGE;
 554 }
 555 
 556 void xenbus_dev_changed(const char *node, struct xen_bus_type *bus)
 557 {
 558         int exists, rootlen;
 559         struct xenbus_device *dev;
 560         char type[XEN_BUS_ID_SIZE];
 561         const char *p, *root;
 562 
 563         if (char_count(node, '/') < 2)
 564                 return;
 565 
 566         exists = xenbus_exists(XBT_NIL, node, "");
 567         if (!exists) {
 568                 xenbus_cleanup_devices(node, &bus->bus);
 569                 return;
 570         }
 571 
 572         /* backend/<type>/... or device/<type>/... */
 573         p = strchr(node, '/') + 1;
 574         snprintf(type, XEN_BUS_ID_SIZE, "%.*s", (int)strcspn(p, "/"), p);
 575         type[XEN_BUS_ID_SIZE-1] = '\0';
 576 
 577         rootlen = strsep_len(node, '/', bus->levels);
 578         if (rootlen < 0)
 579                 return;
 580         root = kasprintf(GFP_KERNEL, "%.*s", rootlen, node);
 581         if (!root)
 582                 return;
 583 
 584         dev = xenbus_device_find(root, &bus->bus);
 585         if (!dev)
 586                 xenbus_probe_node(bus, type, root);
 587         else
 588                 put_device(&dev->dev);
 589 
 590         kfree(root);
 591 }
 592 EXPORT_SYMBOL_GPL(xenbus_dev_changed);
 593 
 594 int xenbus_dev_suspend(struct device *dev)
 595 {
 596         int err = 0;
 597         struct xenbus_driver *drv;
 598         struct xenbus_device *xdev
 599                 = container_of(dev, struct xenbus_device, dev);
 600 
 601         DPRINTK("%s", xdev->nodename);
 602 
 603         if (dev->driver == NULL)
 604                 return 0;
 605         drv = to_xenbus_driver(dev->driver);
 606         if (drv->suspend)
 607                 err = drv->suspend(xdev);
 608         if (err)
 609                 pr_warn("suspend %s failed: %i\n", dev_name(dev), err);
 610         return 0;
 611 }
 612 EXPORT_SYMBOL_GPL(xenbus_dev_suspend);
 613 
 614 int xenbus_dev_resume(struct device *dev)
 615 {
 616         int err;
 617         struct xenbus_driver *drv;
 618         struct xenbus_device *xdev
 619                 = container_of(dev, struct xenbus_device, dev);
 620 
 621         DPRINTK("%s", xdev->nodename);
 622 
 623         if (dev->driver == NULL)
 624                 return 0;
 625         drv = to_xenbus_driver(dev->driver);
 626         err = talk_to_otherend(xdev);
 627         if (err) {
 628                 pr_warn("resume (talk_to_otherend) %s failed: %i\n",
 629                         dev_name(dev), err);
 630                 return err;
 631         }
 632 
 633         xdev->state = XenbusStateInitialising;
 634 
 635         if (drv->resume) {
 636                 err = drv->resume(xdev);
 637                 if (err) {
 638                         pr_warn("resume %s failed: %i\n", dev_name(dev), err);
 639                         return err;
 640                 }
 641         }
 642 
 643         err = watch_otherend(xdev);
 644         if (err) {
 645                 pr_warn("resume (watch_otherend) %s failed: %d.\n",
 646                         dev_name(dev), err);
 647                 return err;
 648         }
 649 
 650         return 0;
 651 }
 652 EXPORT_SYMBOL_GPL(xenbus_dev_resume);
 653 
 654 int xenbus_dev_cancel(struct device *dev)
 655 {
 656         /* Do nothing */
 657         DPRINTK("cancel");
 658         return 0;
 659 }
 660 EXPORT_SYMBOL_GPL(xenbus_dev_cancel);
 661 
 662 /* A flag to determine if xenstored is 'ready' (i.e. has started) */
 663 int xenstored_ready;
 664 
 665 
 666 int register_xenstore_notifier(struct notifier_block *nb)
 667 {
 668         int ret = 0;
 669 
 670         if (xenstored_ready > 0)
 671                 ret = nb->notifier_call(nb, 0, NULL);
 672         else
 673                 blocking_notifier_chain_register(&xenstore_chain, nb);
 674 
 675         return ret;
 676 }
 677 EXPORT_SYMBOL_GPL(register_xenstore_notifier);
 678 
 679 void unregister_xenstore_notifier(struct notifier_block *nb)
 680 {
 681         blocking_notifier_chain_unregister(&xenstore_chain, nb);
 682 }
 683 EXPORT_SYMBOL_GPL(unregister_xenstore_notifier);
 684 
 685 void xenbus_probe(struct work_struct *unused)
 686 {
 687         xenstored_ready = 1;
 688 
 689         /* Notify others that xenstore is up */
 690         blocking_notifier_call_chain(&xenstore_chain, 0, NULL);
 691 }
 692 EXPORT_SYMBOL_GPL(xenbus_probe);
 693 
 694 static int __init xenbus_probe_initcall(void)
 695 {
 696         if (!xen_domain())
 697                 return -ENODEV;
 698 
 699         if (xen_initial_domain() || xen_hvm_domain())
 700                 return 0;
 701 
 702         xenbus_probe(NULL);
 703         return 0;
 704 }
 705 
 706 device_initcall(xenbus_probe_initcall);
 707 
 708 /* Set up event channel for xenstored which is run as a local process
 709  * (this is normally used only in dom0)
 710  */
 711 static int __init xenstored_local_init(void)
 712 {
 713         int err = -ENOMEM;
 714         unsigned long page = 0;
 715         struct evtchn_alloc_unbound alloc_unbound;
 716 
 717         /* Allocate Xenstore page */
 718         page = get_zeroed_page(GFP_KERNEL);
 719         if (!page)
 720                 goto out_err;
 721 
 722         xen_store_gfn = virt_to_gfn((void *)page);
 723 
 724         /* Next allocate a local port which xenstored can bind to */
 725         alloc_unbound.dom        = DOMID_SELF;
 726         alloc_unbound.remote_dom = DOMID_SELF;
 727 
 728         err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
 729                                           &alloc_unbound);
 730         if (err == -ENOSYS)
 731                 goto out_err;
 732 
 733         BUG_ON(err);
 734         xen_store_evtchn = alloc_unbound.port;
 735 
 736         return 0;
 737 
 738  out_err:
 739         if (page != 0)
 740                 free_page(page);
 741         return err;
 742 }
 743 
 744 static int xenbus_resume_cb(struct notifier_block *nb,
 745                             unsigned long action, void *data)
 746 {
 747         int err = 0;
 748 
 749         if (xen_hvm_domain()) {
 750                 uint64_t v = 0;
 751 
 752                 err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
 753                 if (!err && v)
 754                         xen_store_evtchn = v;
 755                 else
 756                         pr_warn("Cannot update xenstore event channel: %d\n",
 757                                 err);
 758         } else
 759                 xen_store_evtchn = xen_start_info->store_evtchn;
 760 
 761         return err;
 762 }
 763 
 764 static struct notifier_block xenbus_resume_nb = {
 765         .notifier_call = xenbus_resume_cb,
 766 };
 767 
 768 static int __init xenbus_init(void)
 769 {
 770         int err = 0;
 771         uint64_t v = 0;
 772         xen_store_domain_type = XS_UNKNOWN;
 773 
 774         if (!xen_domain())
 775                 return -ENODEV;
 776 
 777         xenbus_ring_ops_init();
 778 
 779         if (xen_pv_domain())
 780                 xen_store_domain_type = XS_PV;
 781         if (xen_hvm_domain())
 782                 xen_store_domain_type = XS_HVM;
 783         if (xen_hvm_domain() && xen_initial_domain())
 784                 xen_store_domain_type = XS_LOCAL;
 785         if (xen_pv_domain() && !xen_start_info->store_evtchn)
 786                 xen_store_domain_type = XS_LOCAL;
 787         if (xen_pv_domain() && xen_start_info->store_evtchn)
 788                 xenstored_ready = 1;
 789 
 790         switch (xen_store_domain_type) {
 791         case XS_LOCAL:
 792                 err = xenstored_local_init();
 793                 if (err)
 794                         goto out_error;
 795                 xen_store_interface = gfn_to_virt(xen_store_gfn);
 796                 break;
 797         case XS_PV:
 798                 xen_store_evtchn = xen_start_info->store_evtchn;
 799                 xen_store_gfn = xen_start_info->store_mfn;
 800                 xen_store_interface = gfn_to_virt(xen_store_gfn);
 801                 break;
 802         case XS_HVM:
 803                 err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
 804                 if (err)
 805                         goto out_error;
 806                 xen_store_evtchn = (int)v;
 807                 err = hvm_get_parameter(HVM_PARAM_STORE_PFN, &v);
 808                 if (err)
 809                         goto out_error;
 810                 xen_store_gfn = (unsigned long)v;
 811                 xen_store_interface =
 812                         xen_remap(xen_store_gfn << XEN_PAGE_SHIFT,
 813                                   XEN_PAGE_SIZE);
 814                 break;
 815         default:
 816                 pr_warn("Xenstore state unknown\n");
 817                 break;
 818         }
 819 
 820         /* Initialize the interface to xenstore. */
 821         err = xs_init();
 822         if (err) {
 823                 pr_warn("Error initializing xenstore comms: %i\n", err);
 824                 goto out_error;
 825         }
 826 
 827         if ((xen_store_domain_type != XS_LOCAL) &&
 828             (xen_store_domain_type != XS_UNKNOWN))
 829                 xen_resume_notifier_register(&xenbus_resume_nb);
 830 
 831 #ifdef CONFIG_XEN_COMPAT_XENFS
 832         /*
 833          * Create xenfs mountpoint in /proc for compatibility with
 834          * utilities that expect to find "xenbus" under "/proc/xen".
 835          */
 836         proc_create_mount_point("xen");
 837 #endif
 838 
 839 out_error:
 840         return err;
 841 }
 842 
 843 postcore_initcall(xenbus_init);
 844 
 845 MODULE_LICENSE("GPL");