drivers/xen/xenbus/xenbus_probe.c

   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 DPRINTK(fmt, args...)                           \
  34         pr_debug("xenbus_probe (%s:%d) " fmt ".\n",     \
  35                  __func__, __LINE__, ##args)
  36
  37 #include <linux/kernel.h>
  38 #include <linux/err.h>
  39 #include <linux/string.h>
  40 #include <linux/ctype.h>
  41 #include <linux/fcntl.h>
  42 #include <linux/mm.h>
  43 #include <linux/notifier.h>
  44 #include <linux/kthread.h>
  45 #include <linux/mutex.h>
  46 #include <linux/io.h>
  47
  48 #include <asm/page.h>
  49 #include <asm/pgtable.h>
  50 #include <asm/xen/hypervisor.h>
  51 #include <xen/xenbus.h>
  52 #include <xen/events.h>
  53 #include <xen/page.h>
  54
  55 #include "xenbus_comms.h"
  56 #include "xenbus_probe.h"
  57
  58 int xen_store_evtchn;
  59 struct xenstore_domain_interface *xen_store_interface;
  60 static unsigned long xen_store_mfn;
  61
  62 static BLOCKING_NOTIFIER_HEAD(xenstore_chain);
  63
  64 static void wait_for_devices(struct xenbus_driver *xendrv);
  65
  66 static int xenbus_probe_frontend(const char *type, const char *name);
  67
  68 static void xenbus_dev_shutdown(struct device *_dev);
  69
  70 /* If something in array of ids matches this device, return it. */
  71 static const struct xenbus_device_id *
  72 match_device(const struct xenbus_device_id *arr, struct xenbus_device *dev)
  73 {
  74         for (; *arr->devicetype != '\0'; arr++) {
  75                 if (!strcmp(arr->devicetype, dev->devicetype))
  76                         return arr;
  77         }
  78         return NULL;
  79 }
  80
  81 int xenbus_match(struct device *_dev, struct device_driver *_drv)
  82 {
  83         struct xenbus_driver *drv = to_xenbus_driver(_drv);
  84
  85         if (!drv->ids)
  86                 return 0;
  87
  88         return match_device(drv->ids, to_xenbus_device(_dev)) != NULL;
  89 }
  90
  91 /* device/<type>/<id> => <type>-<id> */
  92 static int frontend_bus_id(char bus_id[BUS_ID_SIZE], const char *nodename)
  93 {
  94         nodename = strchr(nodename, '/');
  95         if (!nodename || strlen(nodename + 1) >= BUS_ID_SIZE) {
  96                 printk(KERN_WARNING "XENBUS: bad frontend %s\n", nodename);
  97                 return -EINVAL;
  98         }
  99
 100         strlcpy(bus_id, nodename + 1, BUS_ID_SIZE);
 101         if (!strchr(bus_id, '/')) {
 102                 printk(KERN_WARNING "XENBUS: bus_id %s no slash\n", bus_id);
 103                 return -EINVAL;
 104         }
 105         *strchr(bus_id, '/') = '-';
 106         return 0;
 107 }
 108
 109
 110 static void free_otherend_details(struct xenbus_device *dev)
 111 {
 112         kfree(dev->otherend);
 113         dev->otherend = NULL;
 114 }
 115
 116
 117 static void free_otherend_watch(struct xenbus_device *dev)
 118 {
 119         if (dev->otherend_watch.node) {
 120                 unregister_xenbus_watch(&dev->otherend_watch);
 121                 kfree(dev->otherend_watch.node);
 122                 dev->otherend_watch.node = NULL;
 123         }
 124 }
 125
 126
 127 int read_otherend_details(struct xenbus_device *xendev,
 128                                  char *id_node, char *path_node)
 129 {
 130         int err = xenbus_gather(XBT_NIL, xendev->nodename,
 131                                 id_node, "%i", &xendev->otherend_id,
 132                                 path_node, NULL, &xendev->otherend,
 133                                 NULL);
 134         if (err) {
 135                 xenbus_dev_fatal(xendev, err,
 136                                  "reading other end details from %s",
 137                                  xendev->nodename);
 138                 return err;
 139         }
 140         if (strlen(xendev->otherend) == 0 ||
 141             !xenbus_exists(XBT_NIL, xendev->otherend, "")) {
 142                 xenbus_dev_fatal(xendev, -ENOENT,
 143                                  "unable to read other end from %s.  "
 144                                  "missing or inaccessible.",
 145                                  xendev->nodename);
 146                 free_otherend_details(xendev);
 147                 return -ENOENT;
 148         }
 149
 150         return 0;
 151 }
 152
 153
 154 static int read_backend_details(struct xenbus_device *xendev)
 155 {
 156         return read_otherend_details(xendev, "backend-id", "backend");
 157 }
 158
 159
 160 /* Bus type for frontend drivers. */
 161 static struct xen_bus_type xenbus_frontend = {
 162         .root = "device",
 163         .levels = 2,            /* device/type/<id> */
 164         .get_bus_id = frontend_bus_id,
 165         .probe = xenbus_probe_frontend,
 166         .bus = {
 167                 .name     = "xen",
 168                 .match    = xenbus_match,
 169                 .probe    = xenbus_dev_probe,
 170                 .remove   = xenbus_dev_remove,
 171                 .shutdown = xenbus_dev_shutdown,
 172         },
 173 };
 174
 175 static void otherend_changed(struct xenbus_watch *watch,
 176                              const char **vec, unsigned int len)
 177 {
 178         struct xenbus_device *dev =
 179                 container_of(watch, struct xenbus_device, otherend_watch);
 180         struct xenbus_driver *drv = to_xenbus_driver(dev->dev.driver);
 181         enum xenbus_state state;
 182
 183         /* Protect us against watches firing on old details when the otherend
 184            details change, say immediately after a resume. */
 185         if (!dev->otherend ||
 186             strncmp(dev->otherend, vec[XS_WATCH_PATH],
 187                     strlen(dev->otherend))) {
 188                 dev_dbg(&dev->dev, "Ignoring watch at %s\n",
 189                         vec[XS_WATCH_PATH]);
 190                 return;
 191         }
 192
 193         state = xenbus_read_driver_state(dev->otherend);
 194
 195         dev_dbg(&dev->dev, "state is %d, (%s), %s, %s\n",
 196                 state, xenbus_strstate(state), dev->otherend_watch.node,
 197                 vec[XS_WATCH_PATH]);
 198
 199         /*
 200          * Ignore xenbus transitions during shutdown. This prevents us doing
 201          * work that can fail e.g., when the rootfs is gone.
 202          */
 203         if (system_state > SYSTEM_RUNNING) {
 204                 struct xen_bus_type *bus = bus;
 205                 bus = container_of(dev->dev.bus, struct xen_bus_type, bus);
 206                 /* If we're frontend, drive the state machine to Closed. */
 207                 /* This should cause the backend to release our resources. */
 208                 if ((bus == &xenbus_frontend) && (state == XenbusStateClosing))
 209                         xenbus_frontend_closed(dev);
 210                 return;
 211         }
 212
 213         if (drv->otherend_changed)
 214                 drv->otherend_changed(dev, state);
 215 }
 216
 217
 218 static int talk_to_otherend(struct xenbus_device *dev)
 219 {
 220         struct xenbus_driver *drv = to_xenbus_driver(dev->dev.driver);
 221
 222         free_otherend_watch(dev);
 223         free_otherend_details(dev);
 224
 225         return drv->read_otherend_details(dev);
 226 }
 227
 228
 229 static int watch_otherend(struct xenbus_device *dev)
 230 {
 231         return xenbus_watch_pathfmt(dev, &dev->otherend_watch, otherend_changed,
 232                                     "%s/%s", dev->otherend, "state");
 233 }
 234
 235
 236 int xenbus_dev_probe(struct device *_dev)
 237 {
 238         struct xenbus_device *dev = to_xenbus_device(_dev);
 239         struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
 240         const struct xenbus_device_id *id;
 241         int err;
 242
 243         DPRINTK("%s", dev->nodename);
 244
 245         if (!drv->probe) {
 246                 err = -ENODEV;
 247                 goto fail;
 248         }
 249
 250         id = match_device(drv->ids, dev);
 251         if (!id) {
 252                 err = -ENODEV;
 253                 goto fail;
 254         }
 255
 256         err = talk_to_otherend(dev);
 257         if (err) {
 258                 dev_warn(&dev->dev, "talk_to_otherend on %s failed.\n",
 259                          dev->nodename);
 260                 return err;
 261         }
 262
 263         err = drv->probe(dev, id);
 264         if (err)
 265                 goto fail;
 266
 267         err = watch_otherend(dev);
 268         if (err) {
 269                 dev_warn(&dev->dev, "watch_otherend on %s failed.\n",
 270                        dev->nodename);
 271                 return err;
 272         }
 273
 274         return 0;
 275 fail:
 276         xenbus_dev_error(dev, err, "xenbus_dev_probe on %s", dev->nodename);
 277         xenbus_switch_state(dev, XenbusStateClosed);
 278         return -ENODEV;
 279 }
 280
 281 int xenbus_dev_remove(struct device *_dev)
 282 {
 283         struct xenbus_device *dev = to_xenbus_device(_dev);
 284         struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
 285
 286         DPRINTK("%s", dev->nodename);
 287
 288         free_otherend_watch(dev);
 289         free_otherend_details(dev);
 290
 291         if (drv->remove)
 292                 drv->remove(dev);
 293
 294         xenbus_switch_state(dev, XenbusStateClosed);
 295         return 0;
 296 }
 297
 298 static void xenbus_dev_shutdown(struct device *_dev)
 299 {
 300         struct xenbus_device *dev = to_xenbus_device(_dev);
 301         unsigned long timeout = 5*HZ;
 302
 303         DPRINTK("%s", dev->nodename);
 304
 305         get_device(&dev->dev);
 306         if (dev->state != XenbusStateConnected) {
 307                 printk(KERN_INFO "%s: %s: %s != Connected, skipping\n", __func__,
 308                        dev->nodename, xenbus_strstate(dev->state));
 309                 goto out;
 310         }
 311         xenbus_switch_state(dev, XenbusStateClosing);
 312         timeout = wait_for_completion_timeout(&dev->down, timeout);
 313         if (!timeout)
 314                 printk(KERN_INFO "%s: %s timeout closing device\n",
 315                        __func__, dev->nodename);
 316  out:
 317         put_device(&dev->dev);
 318 }
 319
 320 int xenbus_register_driver_common(struct xenbus_driver *drv,
 321                                   struct xen_bus_type *bus,
 322                                   struct module *owner,
 323                                   const char *mod_name)
 324 {
 325         drv->driver.name = drv->name;
 326         drv->driver.bus = &bus->bus;
 327         drv->driver.owner = owner;
 328         drv->driver.mod_name = mod_name;
 329
 330         return driver_register(&drv->driver);
 331 }
 332
 333 int __xenbus_register_frontend(struct xenbus_driver *drv,
 334                                struct module *owner, const char *mod_name)
 335 {
 336         int ret;
 337
 338         drv->read_otherend_details = read_backend_details;
 339
 340         ret = xenbus_register_driver_common(drv, &xenbus_frontend,
 341                                             owner, mod_name);
 342         if (ret)
 343                 return ret;
 344
 345         /* If this driver is loaded as a module wait for devices to attach. */
 346         wait_for_devices(drv);
 347
 348         return 0;
 349 }
 350 EXPORT_SYMBOL_GPL(__xenbus_register_frontend);
 351
 352 void xenbus_unregister_driver(struct xenbus_driver *drv)
 353 {
 354         driver_unregister(&drv->driver);
 355 }
 356 EXPORT_SYMBOL_GPL(xenbus_unregister_driver);
 357
 358 struct xb_find_info
 359 {
 360         struct xenbus_device *dev;
 361         const char *nodename;
 362 };
 363
 364 static int cmp_dev(struct device *dev, void *data)
 365 {
 366         struct xenbus_device *xendev = to_xenbus_device(dev);
 367         struct xb_find_info *info = data;
 368
 369         if (!strcmp(xendev->nodename, info->nodename)) {
 370                 info->dev = xendev;
 371                 get_device(dev);
 372                 return 1;
 373         }
 374         return 0;
 375 }
 376
 377 struct xenbus_device *xenbus_device_find(const char *nodename,
 378                                          struct bus_type *bus)
 379 {
 380         struct xb_find_info info = { .dev = NULL, .nodename = nodename };
 381
 382         bus_for_each_dev(bus, NULL, &info, cmp_dev);
 383         return info.dev;
 384 }
 385
 386 static int cleanup_dev(struct device *dev, void *data)
 387 {
 388         struct xenbus_device *xendev = to_xenbus_device(dev);
 389         struct xb_find_info *info = data;
 390         int len = strlen(info->nodename);
 391
 392         DPRINTK("%s", info->nodename);
 393
 394         /* Match the info->nodename path, or any subdirectory of that path. */
 395         if (strncmp(xendev->nodename, info->nodename, len))
 396                 return 0;
 397
 398         /* If the node name is longer, ensure it really is a subdirectory. */
 399         if ((strlen(xendev->nodename) > len) && (xendev->nodename[len] != '/'))
 400                 return 0;
 401
 402         info->dev = xendev;
 403         get_device(dev);
 404         return 1;
 405 }
 406
 407 static void xenbus_cleanup_devices(const char *path, struct bus_type *bus)
 408 {
 409         struct xb_find_info info = { .nodename = path };
 410
 411         do {
 412                 info.dev = NULL;
 413                 bus_for_each_dev(bus, NULL, &info, cleanup_dev);
 414                 if (info.dev) {
 415                         device_unregister(&info.dev->dev);
 416                         put_device(&info.dev->dev);
 417                 }
 418         } while (info.dev);
 419 }
 420
 421 static void xenbus_dev_release(struct device *dev)
 422 {
 423         if (dev)
 424                 kfree(to_xenbus_device(dev));
 425 }
 426
 427 static ssize_t xendev_show_nodename(struct device *dev,
 428                                     struct device_attribute *attr, char *buf)
 429 {
 430         return sprintf(buf, "%s\n", to_xenbus_device(dev)->nodename);
 431 }
 432 DEVICE_ATTR(nodename, S_IRUSR | S_IRGRP | S_IROTH, xendev_show_nodename, NULL);
 433
 434 static ssize_t xendev_show_devtype(struct device *dev,
 435                                    struct device_attribute *attr, char *buf)
 436 {
 437         return sprintf(buf, "%s\n", to_xenbus_device(dev)->devicetype);
 438 }
 439 DEVICE_ATTR(devtype, S_IRUSR | S_IRGRP | S_IROTH, xendev_show_devtype, NULL);
 440
 441
 442 int xenbus_probe_node(struct xen_bus_type *bus,
 443                       const char *type,
 444                       const char *nodename)
 445 {
 446         int err;
 447         struct xenbus_device *xendev;
 448         size_t stringlen;
 449         char *tmpstring;
 450
 451         enum xenbus_state state = xenbus_read_driver_state(nodename);
 452
 453         if (state != XenbusStateInitialising) {
 454                 /* Device is not new, so ignore it.  This can happen if a
 455                    device is going away after switching to Closed.  */
 456                 return 0;
 457         }
 458
 459         stringlen = strlen(nodename) + 1 + strlen(type) + 1;
 460         xendev = kzalloc(sizeof(*xendev) + stringlen, GFP_KERNEL);
 461         if (!xendev)
 462                 return -ENOMEM;
 463
 464         xendev->state = XenbusStateInitialising;
 465
 466         /* Copy the strings into the extra space. */
 467
 468         tmpstring = (char *)(xendev + 1);
 469         strcpy(tmpstring, nodename);
 470         xendev->nodename = tmpstring;
 471
 472         tmpstring += strlen(tmpstring) + 1;
 473         strcpy(tmpstring, type);
 474         xendev->devicetype = tmpstring;
 475         init_completion(&xendev->down);
 476
 477         xendev->dev.bus = &bus->bus;
 478         xendev->dev.release = xenbus_dev_release;
 479
 480         err = bus->get_bus_id(xendev->dev.bus_id, xendev->nodename);
 481         if (err)
 482                 goto fail;
 483
 484         /* Register with generic device framework. */
 485         err = device_register(&xendev->dev);
 486         if (err)
 487                 goto fail;
 488
 489         err = device_create_file(&xendev->dev, &dev_attr_nodename);
 490         if (err)
 491                 goto fail_unregister;
 492
 493         err = device_create_file(&xendev->dev, &dev_attr_devtype);
 494         if (err)
 495                 goto fail_remove_file;
 496
 497         return 0;
 498 fail_remove_file:
 499         device_remove_file(&xendev->dev, &dev_attr_nodename);
 500 fail_unregister:
 501         device_unregister(&xendev->dev);
 502 fail:
 503         kfree(xendev);
 504         return err;
 505 }
 506
 507 /* device/<typename>/<name> */
 508 static int xenbus_probe_frontend(const char *type, const char *name)
 509 {
 510         char *nodename;
 511         int err;
 512
 513         nodename = kasprintf(GFP_KERNEL, "%s/%s/%s",
 514                              xenbus_frontend.root, type, name);
 515         if (!nodename)
 516                 return -ENOMEM;
 517
 518         DPRINTK("%s", nodename);
 519
 520         err = xenbus_probe_node(&xenbus_frontend, type, nodename);
 521         kfree(nodename);
 522         return err;
 523 }
 524
 525 static int xenbus_probe_device_type(struct xen_bus_type *bus, const char *type)
 526 {
 527         int err = 0;
 528         char **dir;
 529         unsigned int dir_n = 0;
 530         int i;
 531
 532         dir = xenbus_directory(XBT_NIL, bus->root, type, &dir_n);
 533         if (IS_ERR(dir))
 534                 return PTR_ERR(dir);
 535
 536         for (i = 0; i < dir_n; i++) {
 537                 err = bus->probe(type, dir[i]);
 538                 if (err)
 539                         break;
 540         }
 541         kfree(dir);
 542         return err;
 543 }
 544
 545 int xenbus_probe_devices(struct xen_bus_type *bus)
 546 {
 547         int err = 0;
 548         char **dir;
 549         unsigned int i, dir_n;
 550
 551         dir = xenbus_directory(XBT_NIL, bus->root, "", &dir_n);
 552         if (IS_ERR(dir))
 553                 return PTR_ERR(dir);
 554
 555         for (i = 0; i < dir_n; i++) {
 556                 err = xenbus_probe_device_type(bus, dir[i]);
 557                 if (err)
 558                         break;
 559         }
 560         kfree(dir);
 561         return err;
 562 }
 563
 564 static unsigned int char_count(const char *str, char c)
 565 {
 566         unsigned int i, ret = 0;
 567
 568         for (i = 0; str[i]; i++)
 569                 if (str[i] == c)
 570                         ret++;
 571         return ret;
 572 }
 573
 574 static int strsep_len(const char *str, char c, unsigned int len)
 575 {
 576         unsigned int i;
 577
 578         for (i = 0; str[i]; i++)
 579                 if (str[i] == c) {
 580                         if (len == 0)
 581                                 return i;
 582                         len--;
 583                 }
 584         return (len == 0) ? i : -ERANGE;
 585 }
 586
 587 void xenbus_dev_changed(const char *node, struct xen_bus_type *bus)
 588 {
 589         int exists, rootlen;
 590         struct xenbus_device *dev;
 591         char type[BUS_ID_SIZE];
 592         const char *p, *root;
 593
 594         if (char_count(node, '/') < 2)
 595                 return;
 596
 597         exists = xenbus_exists(XBT_NIL, node, "");
 598         if (!exists) {
 599                 xenbus_cleanup_devices(node, &bus->bus);
 600                 return;
 601         }
 602
 603         /* backend/<type>/... or device/<type>/... */
 604         p = strchr(node, '/') + 1;
 605         snprintf(type, BUS_ID_SIZE, "%.*s", (int)strcspn(p, "/"), p);
 606         type[BUS_ID_SIZE-1] = '\0';
 607
 608         rootlen = strsep_len(node, '/', bus->levels);
 609         if (rootlen < 0)
 610                 return;
 611         root = kasprintf(GFP_KERNEL, "%.*s", rootlen, node);
 612         if (!root)
 613                 return;
 614
 615         dev = xenbus_device_find(root, &bus->bus);
 616         if (!dev)
 617                 xenbus_probe_node(bus, type, root);
 618         else
 619                 put_device(&dev->dev);
 620
 621         kfree(root);
 622 }
 623
 624 static void frontend_changed(struct xenbus_watch *watch,
 625                              const char **vec, unsigned int len)
 626 {
 627         DPRINTK("");
 628
 629         xenbus_dev_changed(vec[XS_WATCH_PATH], &xenbus_frontend);
 630 }
 631
 632 /* We watch for devices appearing and vanishing. */
 633 static struct xenbus_watch fe_watch = {
 634         .node = "device",
 635         .callback = frontend_changed,
 636 };
 637
 638 static int suspend_dev(struct device *dev, void *data)
 639 {
 640         int err = 0;
 641         struct xenbus_driver *drv;
 642         struct xenbus_device *xdev;
 643
 644         DPRINTK("");
 645
 646         if (dev->driver == NULL)
 647                 return 0;
 648         drv = to_xenbus_driver(dev->driver);
 649         xdev = container_of(dev, struct xenbus_device, dev);
 650         if (drv->suspend)
 651                 err = drv->suspend(xdev);
 652         if (err)
 653                 printk(KERN_WARNING
 654                        "xenbus: suspend %s failed: %i\n", dev->bus_id, err);
 655         return 0;
 656 }
 657
 658 static int suspend_cancel_dev(struct device *dev, void *data)
 659 {
 660         int err = 0;
 661         struct xenbus_driver *drv;
 662         struct xenbus_device *xdev;
 663
 664         DPRINTK("");
 665
 666         if (dev->driver == NULL)
 667                 return 0;
 668         drv = to_xenbus_driver(dev->driver);
 669         xdev = container_of(dev, struct xenbus_device, dev);
 670         if (drv->suspend_cancel)
 671                 err = drv->suspend_cancel(xdev);
 672         if (err)
 673                 printk(KERN_WARNING
 674                        "xenbus: suspend_cancel %s failed: %i\n",
 675                        dev->bus_id, err);
 676         return 0;
 677 }
 678
 679 static int resume_dev(struct device *dev, void *data)
 680 {
 681         int err;
 682         struct xenbus_driver *drv;
 683         struct xenbus_device *xdev;
 684
 685         DPRINTK("");
 686
 687         if (dev->driver == NULL)
 688                 return 0;
 689
 690         drv = to_xenbus_driver(dev->driver);
 691         xdev = container_of(dev, struct xenbus_device, dev);
 692
 693         err = talk_to_otherend(xdev);
 694         if (err) {
 695                 printk(KERN_WARNING
 696                        "xenbus: resume (talk_to_otherend) %s failed: %i\n",
 697                        dev->bus_id, err);
 698                 return err;
 699         }
 700
 701         xdev->state = XenbusStateInitialising;
 702
 703         if (drv->resume) {
 704                 err = drv->resume(xdev);
 705                 if (err) {
 706                         printk(KERN_WARNING
 707                                "xenbus: resume %s failed: %i\n",
 708                                dev->bus_id, err);
 709                         return err;
 710                 }
 711         }
 712
 713         err = watch_otherend(xdev);
 714         if (err) {
 715                 printk(KERN_WARNING
 716                        "xenbus_probe: resume (watch_otherend) %s failed: "
 717                        "%d.\n", dev->bus_id, err);
 718                 return err;
 719         }
 720
 721         return 0;
 722 }
 723
 724 void xenbus_suspend(void)
 725 {
 726         DPRINTK("");
 727
 728         bus_for_each_dev(&xenbus_frontend.bus, NULL, NULL, suspend_dev);
 729         xenbus_backend_suspend(suspend_dev);
 730         xs_suspend();
 731 }
 732 EXPORT_SYMBOL_GPL(xenbus_suspend);
 733
 734 void xenbus_resume(void)
 735 {
 736         xb_init_comms();
 737         xs_resume();
 738         bus_for_each_dev(&xenbus_frontend.bus, NULL, NULL, resume_dev);
 739         xenbus_backend_resume(resume_dev);
 740 }
 741 EXPORT_SYMBOL_GPL(xenbus_resume);
 742
 743 void xenbus_suspend_cancel(void)
 744 {
 745         xs_suspend_cancel();
 746         bus_for_each_dev(&xenbus_frontend.bus, NULL, NULL, suspend_cancel_dev);
 747         xenbus_backend_resume(suspend_cancel_dev);
 748 }
 749 EXPORT_SYMBOL_GPL(xenbus_suspend_cancel);
 750
 751 /* A flag to determine if xenstored is 'ready' (i.e. has started) */
 752 int xenstored_ready = 0;
 753
 754
 755 int register_xenstore_notifier(struct notifier_block *nb)
 756 {
 757         int ret = 0;
 758
 759         if (xenstored_ready > 0)
 760                 ret = nb->notifier_call(nb, 0, NULL);
 761         else
 762                 blocking_notifier_chain_register(&xenstore_chain, nb);
 763
 764         return ret;
 765 }
 766 EXPORT_SYMBOL_GPL(register_xenstore_notifier);
 767
 768 void unregister_xenstore_notifier(struct notifier_block *nb)
 769 {
 770         blocking_notifier_chain_unregister(&xenstore_chain, nb);
 771 }
 772 EXPORT_SYMBOL_GPL(unregister_xenstore_notifier);
 773
 774 void xenbus_probe(struct work_struct *unused)
 775 {
 776         BUG_ON((xenstored_ready <= 0));
 777
 778         /* Enumerate devices in xenstore and watch for changes. */
 779         xenbus_probe_devices(&xenbus_frontend);
 780         register_xenbus_watch(&fe_watch);
 781         xenbus_backend_probe_and_watch();
 782
 783         /* Notify others that xenstore is up */
 784         blocking_notifier_call_chain(&xenstore_chain, 0, NULL);
 785 }
 786
 787 static int __init xenbus_probe_init(void)
 788 {
 789         int err = 0;
 790
 791         DPRINTK("");
 792
 793         err = -ENODEV;
 794         if (!is_running_on_xen())
 795                 goto out_error;
 796
 797         /* Register ourselves with the kernel bus subsystem */
 798         err = bus_register(&xenbus_frontend.bus);
 799         if (err)
 800                 goto out_error;
 801
 802         err = xenbus_backend_bus_register();
 803         if (err)
 804                 goto out_unreg_front;
 805
 806         /*
 807          * Domain0 doesn't have a store_evtchn or store_mfn yet.
 808          */
 809         if (is_initial_xendomain()) {
 810                 /* dom0 not yet supported */
 811         } else {
 812                 xenstored_ready = 1;
 813                 xen_store_evtchn = xen_start_info->store_evtchn;
 814                 xen_store_mfn = xen_start_info->store_mfn;
 815         }
 816         xen_store_interface = mfn_to_virt(xen_store_mfn);
 817
 818         /* Initialize the interface to xenstore. */
 819         err = xs_init();
 820         if (err) {
 821                 printk(KERN_WARNING
 822                        "XENBUS: Error initializing xenstore comms: %i\n", err);
 823                 goto out_unreg_back;
 824         }
 825
 826         if (!is_initial_xendomain())
 827                 xenbus_probe(NULL);
 828
 829         return 0;
 830
 831   out_unreg_back:
 832         xenbus_backend_bus_unregister();
 833
 834   out_unreg_front:
 835         bus_unregister(&xenbus_frontend.bus);
 836
 837   out_error:
 838         return err;
 839 }
 840
 841 postcore_initcall(xenbus_probe_init);
 842
 843 MODULE_LICENSE("GPL");
 844
 845 static int is_disconnected_device(struct device *dev, void *data)
 846 {
 847         struct xenbus_device *xendev = to_xenbus_device(dev);
 848         struct device_driver *drv = data;
 849
 850         /*
 851          * A device with no driver will never connect. We care only about
 852          * devices which should currently be in the process of connecting.
 853          */
 854         if (!dev->driver)
 855                 return 0;
 856
 857         /* Is this search limited to a particular driver? */
 858         if (drv && (dev->driver != drv))
 859                 return 0;
 860
 861         return (xendev->state != XenbusStateConnected);
 862 }
 863
 864 static int exists_disconnected_device(struct device_driver *drv)
 865 {
 866         return bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
 867                                 is_disconnected_device);
 868 }
 869
 870 static int print_device_status(struct device *dev, void *data)
 871 {
 872         struct xenbus_device *xendev = to_xenbus_device(dev);
 873         struct device_driver *drv = data;
 874
 875         /* Is this operation limited to a particular driver? */
 876         if (drv && (dev->driver != drv))
 877                 return 0;
 878
 879         if (!dev->driver) {
 880                 /* Information only: is this too noisy? */
 881                 printk(KERN_INFO "XENBUS: Device with no driver: %s\n",
 882                        xendev->nodename);
 883         } else if (xendev->state != XenbusStateConnected) {
 884                 printk(KERN_WARNING "XENBUS: Timeout connecting "
 885                        "to device: %s (state %d)\n",
 886                        xendev->nodename, xendev->state);
 887         }
 888
 889         return 0;
 890 }
 891
 892 /* We only wait for device setup after most initcalls have run. */
 893 static int ready_to_wait_for_devices;
 894
 895 /*
 896  * On a 10 second timeout, wait for all devices currently configured.  We need
 897  * to do this to guarantee that the filesystems and / or network devices
 898  * needed for boot are available, before we can allow the boot to proceed.
 899  *
 900  * This needs to be on a late_initcall, to happen after the frontend device
 901  * drivers have been initialised, but before the root fs is mounted.
 902  *
 903  * A possible improvement here would be to have the tools add a per-device
 904  * flag to the store entry, indicating whether it is needed at boot time.
 905  * This would allow people who knew what they were doing to accelerate their
 906  * boot slightly, but of course needs tools or manual intervention to set up
 907  * those flags correctly.
 908  */
 909 static void wait_for_devices(struct xenbus_driver *xendrv)
 910 {
 911         unsigned long timeout = jiffies + 10*HZ;
 912         struct device_driver *drv = xendrv ? &xendrv->driver : NULL;
 913
 914         if (!ready_to_wait_for_devices || !is_running_on_xen())
 915                 return;
 916
 917         while (exists_disconnected_device(drv)) {
 918                 if (time_after(jiffies, timeout))
 919                         break;
 920                 schedule_timeout_interruptible(HZ/10);
 921         }
 922
 923         bus_for_each_dev(&xenbus_frontend.bus, NULL, drv,
 924                          print_device_status);
 925 }
 926
 927 #ifndef MODULE
 928 static int __init boot_wait_for_devices(void)
 929 {
 930         ready_to_wait_for_devices = 1;
 931         wait_for_devices(NULL);
 932         return 0;
 933 }
 934
 935 late_initcall(boot_wait_for_devices);
 936 #endif