drivers/s390/cio/ccwgroup.c

   1 /*
   2  *  bus driver for ccwgroup
   3  *
   4  *  Copyright IBM Corp. 2002, 2009
   5  *
   6  *  Author(s): Arnd Bergmann (arndb@de.ibm.com)
   7  *             Cornelia Huck (cornelia.huck@de.ibm.com)
   8  */
   9 #include <linux/module.h>
  10 #include <linux/errno.h>
  11 #include <linux/slab.h>
  12 #include <linux/list.h>
  13 #include <linux/device.h>
  14 #include <linux/init.h>
  15 #include <linux/ctype.h>
  16 #include <linux/dcache.h>
  17
  18 #include <asm/ccwdev.h>
  19 #include <asm/ccwgroup.h>
  20
  21 #define CCW_BUS_ID_SIZE         20
  22
  23 /* In Linux 2.4, we had a channel device layer called "chandev"
  24  * that did all sorts of obscure stuff for networking devices.
  25  * This is another driver that serves as a replacement for just
  26  * one of its functions, namely the translation of single subchannels
  27  * to devices that use multiple subchannels.
  28  */
  29
  30 /* a device matches a driver if all its slave devices match the same
  31  * entry of the driver */
  32 static int
  33 ccwgroup_bus_match (struct device * dev, struct device_driver * drv)
  34 {
  35         struct ccwgroup_device *gdev;
  36         struct ccwgroup_driver *gdrv;
  37
  38         gdev = to_ccwgroupdev(dev);
  39         gdrv = to_ccwgroupdrv(drv);
  40
  41         if (gdev->creator_id == gdrv->driver_id)
  42                 return 1;
  43
  44         return 0;
  45 }
  46 static int
  47 ccwgroup_uevent (struct device *dev, struct kobj_uevent_env *env)
  48 {
  49         /* TODO */
  50         return 0;
  51 }
  52
  53 static struct bus_type ccwgroup_bus_type;
  54
  55 static void
  56 __ccwgroup_remove_symlinks(struct ccwgroup_device *gdev)
  57 {
  58         int i;
  59         char str[8];
  60
  61         for (i = 0; i < gdev->count; i++) {
  62                 sprintf(str, "cdev%d", i);
  63                 sysfs_remove_link(&gdev->dev.kobj, str);
  64                 sysfs_remove_link(&gdev->cdev[i]->dev.kobj, "group_device");
  65         }
  66
  67 }
  68
  69 /*
  70  * Remove references from ccw devices to ccw group device and from
  71  * ccw group device to ccw devices.
  72  */
  73 static void __ccwgroup_remove_cdev_refs(struct ccwgroup_device *gdev)
  74 {
  75         struct ccw_device *cdev;
  76         int i;
  77
  78         for (i = 0; i < gdev->count; i++) {
  79                 cdev = gdev->cdev[i];
  80                 if (!cdev)
  81                         continue;
  82                 spin_lock_irq(cdev->ccwlock);
  83                 dev_set_drvdata(&cdev->dev, NULL);
  84                 spin_unlock_irq(cdev->ccwlock);
  85                 gdev->cdev[i] = NULL;
  86                 put_device(&cdev->dev);
  87         }
  88 }
  89
  90 /*
  91  * Provide an 'ungroup' attribute so the user can remove group devices no
  92  * longer needed or accidentially created. Saves memory :)
  93  */
  94 static void ccwgroup_ungroup_callback(struct device *dev)
  95 {
  96         struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
  97
  98         mutex_lock(&gdev->reg_mutex);
  99         if (device_is_registered(&gdev->dev)) {
 100                 __ccwgroup_remove_symlinks(gdev);
 101                 device_unregister(dev);
 102                 __ccwgroup_remove_cdev_refs(gdev);
 103         }
 104         mutex_unlock(&gdev->reg_mutex);
 105 }
 106
 107 static ssize_t
 108 ccwgroup_ungroup_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 109 {
 110         struct ccwgroup_device *gdev;
 111         int rc;
 112
 113         gdev = to_ccwgroupdev(dev);
 114
 115         /* Prevent concurrent online/offline processing and ungrouping. */
 116         if (atomic_cmpxchg(&gdev->onoff, 0, 1) != 0)
 117                 return -EAGAIN;
 118         if (gdev->state != CCWGROUP_OFFLINE) {
 119                 rc = -EINVAL;
 120                 goto out;
 121         }
 122         /* Note that we cannot unregister the device from one of its
 123          * attribute methods, so we have to use this roundabout approach.
 124          */
 125         rc = device_schedule_callback(dev, ccwgroup_ungroup_callback);
 126 out:
 127         if (rc) {
 128                 if (rc != -EAGAIN)
 129                         /* Release onoff "lock" when ungrouping failed. */
 130                         atomic_set(&gdev->onoff, 0);
 131                 return rc;
 132         }
 133         return count;
 134 }
 135
 136 static DEVICE_ATTR(ungroup, 0200, NULL, ccwgroup_ungroup_store);
 137
 138 static void
 139 ccwgroup_release (struct device *dev)
 140 {
 141         kfree(to_ccwgroupdev(dev));
 142 }
 143
 144 static int
 145 __ccwgroup_create_symlinks(struct ccwgroup_device *gdev)
 146 {
 147         char str[8];
 148         int i, rc;
 149
 150         for (i = 0; i < gdev->count; i++) {
 151                 rc = sysfs_create_link(&gdev->cdev[i]->dev.kobj, &gdev->dev.kobj,
 152                                        "group_device");
 153                 if (rc) {
 154                         for (--i; i >= 0; i--)
 155                                 sysfs_remove_link(&gdev->cdev[i]->dev.kobj,
 156                                                   "group_device");
 157                         return rc;
 158                 }
 159         }
 160         for (i = 0; i < gdev->count; i++) {
 161                 sprintf(str, "cdev%d", i);
 162                 rc = sysfs_create_link(&gdev->dev.kobj, &gdev->cdev[i]->dev.kobj,
 163                                        str);
 164                 if (rc) {
 165                         for (--i; i >= 0; i--) {
 166                                 sprintf(str, "cdev%d", i);
 167                                 sysfs_remove_link(&gdev->dev.kobj, str);
 168                         }
 169                         for (i = 0; i < gdev->count; i++)
 170                                 sysfs_remove_link(&gdev->cdev[i]->dev.kobj,
 171                                                   "group_device");
 172                         return rc;
 173                 }
 174         }
 175         return 0;
 176 }
 177
 178 static int __get_next_bus_id(const char **buf, char *bus_id)
 179 {
 180         int rc, len;
 181         char *start, *end;
 182
 183         start = (char *)*buf;
 184         end = strchr(start, ',');
 185         if (!end) {
 186                 /* Last entry. Strip trailing newline, if applicable. */
 187                 end = strchr(start, '\n');
 188                 if (end)
 189                         *end = '\0';
 190                 len = strlen(start) + 1;
 191         } else {
 192                 len = end - start + 1;
 193                 end++;
 194         }
 195         if (len < CCW_BUS_ID_SIZE) {
 196                 strlcpy(bus_id, start, len);
 197                 rc = 0;
 198         } else
 199                 rc = -EINVAL;
 200         *buf = end;
 201         return rc;
 202 }
 203
 204 static int __is_valid_bus_id(char bus_id[CCW_BUS_ID_SIZE])
 205 {
 206         int cssid, ssid, devno;
 207
 208         /* Must be of form %x.%x.%04x */
 209         if (sscanf(bus_id, "%x.%1x.%04x", &cssid, &ssid, &devno) != 3)
 210                 return 0;
 211         return 1;
 212 }
 213
 214 /**
 215  * ccwgroup_create_from_string() - create and register a ccw group device
 216  * @root: parent device for the new device
 217  * @creator_id: identifier of creating driver
 218  * @cdrv: ccw driver of slave devices
 219  * @num_devices: number of slave devices
 220  * @buf: buffer containing comma separated bus ids of slave devices
 221  *
 222  * Create and register a new ccw group device as a child of @root. Slave
 223  * devices are obtained from the list of bus ids given in @buf and must all
 224  * belong to @cdrv.
 225  * Returns:
 226  *  %0 on success and an error code on failure.
 227  * Context:
 228  *  non-atomic
 229  */
 230 int ccwgroup_create_from_string(struct device *root, unsigned int creator_id,
 231                                 struct ccw_driver *cdrv, int num_devices,
 232                                 const char *buf)
 233 {
 234         struct ccwgroup_device *gdev;
 235         int rc, i;
 236         char tmp_bus_id[CCW_BUS_ID_SIZE];
 237         const char *curr_buf;
 238
 239         gdev = kzalloc(sizeof(*gdev) + num_devices * sizeof(gdev->cdev[0]),
 240                        GFP_KERNEL);
 241         if (!gdev)
 242                 return -ENOMEM;
 243
 244         atomic_set(&gdev->onoff, 0);
 245         mutex_init(&gdev->reg_mutex);
 246         mutex_lock(&gdev->reg_mutex);
 247         gdev->creator_id = creator_id;
 248         gdev->count = num_devices;
 249         gdev->dev.bus = &ccwgroup_bus_type;
 250         gdev->dev.parent = root;
 251         gdev->dev.release = ccwgroup_release;
 252         device_initialize(&gdev->dev);
 253
 254         curr_buf = buf;
 255         for (i = 0; i < num_devices && curr_buf; i++) {
 256                 rc = __get_next_bus_id(&curr_buf, tmp_bus_id);
 257                 if (rc != 0)
 258                         goto error;
 259                 if (!__is_valid_bus_id(tmp_bus_id)) {
 260                         rc = -EINVAL;
 261                         goto error;
 262                 }
 263                 gdev->cdev[i] = get_ccwdev_by_busid(cdrv, tmp_bus_id);
 264                 /*
 265                  * All devices have to be of the same type in
 266                  * order to be grouped.
 267                  */
 268                 if (!gdev->cdev[i]
 269                     || gdev->cdev[i]->id.driver_info !=
 270                     gdev->cdev[0]->id.driver_info) {
 271                         rc = -EINVAL;
 272                         goto error;
 273                 }
 274                 /* Don't allow a device to belong to more than one group. */
 275                 spin_lock_irq(gdev->cdev[i]->ccwlock);
 276                 if (dev_get_drvdata(&gdev->cdev[i]->dev)) {
 277                         spin_unlock_irq(gdev->cdev[i]->ccwlock);
 278                         rc = -EINVAL;
 279                         goto error;
 280                 }
 281                 dev_set_drvdata(&gdev->cdev[i]->dev, gdev);
 282                 spin_unlock_irq(gdev->cdev[i]->ccwlock);
 283         }
 284         /* Check for sufficient number of bus ids. */
 285         if (i < num_devices && !curr_buf) {
 286                 rc = -EINVAL;
 287                 goto error;
 288         }
 289         /* Check for trailing stuff. */
 290         if (i == num_devices && strlen(curr_buf) > 0) {
 291                 rc = -EINVAL;
 292                 goto error;
 293         }
 294
 295         dev_set_name(&gdev->dev, "%s", dev_name(&gdev->cdev[0]->dev));
 296
 297         rc = device_add(&gdev->dev);
 298         if (rc)
 299                 goto error;
 300         get_device(&gdev->dev);
 301         rc = device_create_file(&gdev->dev, &dev_attr_ungroup);
 302
 303         if (rc) {
 304                 device_unregister(&gdev->dev);
 305                 goto error;
 306         }
 307
 308         rc = __ccwgroup_create_symlinks(gdev);
 309         if (!rc) {
 310                 mutex_unlock(&gdev->reg_mutex);
 311                 put_device(&gdev->dev);
 312                 return 0;
 313         }
 314         device_remove_file(&gdev->dev, &dev_attr_ungroup);
 315         device_unregister(&gdev->dev);
 316 error:
 317         for (i = 0; i < num_devices; i++)
 318                 if (gdev->cdev[i]) {
 319                         spin_lock_irq(gdev->cdev[i]->ccwlock);
 320                         if (dev_get_drvdata(&gdev->cdev[i]->dev) == gdev)
 321                                 dev_set_drvdata(&gdev->cdev[i]->dev, NULL);
 322                         spin_unlock_irq(gdev->cdev[i]->ccwlock);
 323                         put_device(&gdev->cdev[i]->dev);
 324                         gdev->cdev[i] = NULL;
 325                 }
 326         mutex_unlock(&gdev->reg_mutex);
 327         put_device(&gdev->dev);
 328         return rc;
 329 }
 330 EXPORT_SYMBOL(ccwgroup_create_from_string);
 331
 332 static int ccwgroup_notifier(struct notifier_block *nb, unsigned long action,
 333                              void *data);
 334
 335 static struct notifier_block ccwgroup_nb = {
 336         .notifier_call = ccwgroup_notifier
 337 };
 338
 339 static int __init init_ccwgroup(void)
 340 {
 341         int ret;
 342
 343         ret = bus_register(&ccwgroup_bus_type);
 344         if (ret)
 345                 return ret;
 346
 347         ret = bus_register_notifier(&ccwgroup_bus_type, &ccwgroup_nb);
 348         if (ret)
 349                 bus_unregister(&ccwgroup_bus_type);
 350
 351         return ret;
 352 }
 353
 354 static void __exit cleanup_ccwgroup(void)
 355 {
 356         bus_unregister_notifier(&ccwgroup_bus_type, &ccwgroup_nb);
 357         bus_unregister(&ccwgroup_bus_type);
 358 }
 359
 360 module_init(init_ccwgroup);
 361 module_exit(cleanup_ccwgroup);
 362
 363 /************************** driver stuff ******************************/
 364
 365 static int
 366 ccwgroup_set_online(struct ccwgroup_device *gdev)
 367 {
 368         struct ccwgroup_driver *gdrv;
 369         int ret;
 370
 371         if (atomic_cmpxchg(&gdev->onoff, 0, 1) != 0)
 372                 return -EAGAIN;
 373         if (gdev->state == CCWGROUP_ONLINE) {
 374                 ret = 0;
 375                 goto out;
 376         }
 377         if (!gdev->dev.driver) {
 378                 ret = -EINVAL;
 379                 goto out;
 380         }
 381         gdrv = to_ccwgroupdrv (gdev->dev.driver);
 382         if ((ret = gdrv->set_online ? gdrv->set_online(gdev) : 0))
 383                 goto out;
 384
 385         gdev->state = CCWGROUP_ONLINE;
 386  out:
 387         atomic_set(&gdev->onoff, 0);
 388         return ret;
 389 }
 390
 391 static int
 392 ccwgroup_set_offline(struct ccwgroup_device *gdev)
 393 {
 394         struct ccwgroup_driver *gdrv;
 395         int ret;
 396
 397         if (atomic_cmpxchg(&gdev->onoff, 0, 1) != 0)
 398                 return -EAGAIN;
 399         if (gdev->state == CCWGROUP_OFFLINE) {
 400                 ret = 0;
 401                 goto out;
 402         }
 403         if (!gdev->dev.driver) {
 404                 ret = -EINVAL;
 405                 goto out;
 406         }
 407         gdrv = to_ccwgroupdrv (gdev->dev.driver);
 408         if ((ret = gdrv->set_offline ? gdrv->set_offline(gdev) : 0))
 409                 goto out;
 410
 411         gdev->state = CCWGROUP_OFFLINE;
 412  out:
 413         atomic_set(&gdev->onoff, 0);
 414         return ret;
 415 }
 416
 417 static ssize_t
 418 ccwgroup_online_store (struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 419 {
 420         struct ccwgroup_device *gdev;
 421         struct ccwgroup_driver *gdrv;
 422         unsigned long value;
 423         int ret;
 424
 425         if (!dev->driver)
 426                 return -ENODEV;
 427
 428         gdev = to_ccwgroupdev(dev);
 429         gdrv = to_ccwgroupdrv(dev->driver);
 430
 431         if (!try_module_get(gdrv->driver.owner))
 432                 return -EINVAL;
 433
 434         ret = strict_strtoul(buf, 0, &value);
 435         if (ret)
 436                 goto out;
 437
 438         if (value == 1)
 439                 ret = ccwgroup_set_online(gdev);
 440         else if (value == 0)
 441                 ret = ccwgroup_set_offline(gdev);
 442         else
 443                 ret = -EINVAL;
 444 out:
 445         module_put(gdrv->driver.owner);
 446         return (ret == 0) ? count : ret;
 447 }
 448
 449 static ssize_t
 450 ccwgroup_online_show (struct device *dev, struct device_attribute *attr, char *buf)
 451 {
 452         int online;
 453
 454         online = (to_ccwgroupdev(dev)->state == CCWGROUP_ONLINE);
 455
 456         return sprintf(buf, online ? "1\n" : "0\n");
 457 }
 458
 459 static DEVICE_ATTR(online, 0644, ccwgroup_online_show, ccwgroup_online_store);
 460
 461 static int
 462 ccwgroup_probe (struct device *dev)
 463 {
 464         struct ccwgroup_device *gdev;
 465         struct ccwgroup_driver *gdrv;
 466
 467         int ret;
 468
 469         gdev = to_ccwgroupdev(dev);
 470         gdrv = to_ccwgroupdrv(dev->driver);
 471
 472         if ((ret = device_create_file(dev, &dev_attr_online)))
 473                 return ret;
 474
 475         ret = gdrv->probe ? gdrv->probe(gdev) : -ENODEV;
 476         if (ret)
 477                 device_remove_file(dev, &dev_attr_online);
 478
 479         return ret;
 480 }
 481
 482 static int
 483 ccwgroup_remove (struct device *dev)
 484 {
 485         struct ccwgroup_device *gdev;
 486         struct ccwgroup_driver *gdrv;
 487
 488         device_remove_file(dev, &dev_attr_online);
 489         device_remove_file(dev, &dev_attr_ungroup);
 490
 491         if (!dev->driver)
 492                 return 0;
 493
 494         gdev = to_ccwgroupdev(dev);
 495         gdrv = to_ccwgroupdrv(dev->driver);
 496
 497         if (gdrv->remove)
 498                 gdrv->remove(gdev);
 499
 500         return 0;
 501 }
 502
 503 static void ccwgroup_shutdown(struct device *dev)
 504 {
 505         struct ccwgroup_device *gdev;
 506         struct ccwgroup_driver *gdrv;
 507
 508         if (!dev->driver)
 509                 return;
 510
 511         gdev = to_ccwgroupdev(dev);
 512         gdrv = to_ccwgroupdrv(dev->driver);
 513
 514         if (gdrv->shutdown)
 515                 gdrv->shutdown(gdev);
 516 }
 517
 518 static int ccwgroup_pm_prepare(struct device *dev)
 519 {
 520         struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
 521         struct ccwgroup_driver *gdrv = to_ccwgroupdrv(gdev->dev.driver);
 522
 523         /* Fail while device is being set online/offline. */
 524         if (atomic_read(&gdev->onoff))
 525                 return -EAGAIN;
 526
 527         if (!gdev->dev.driver || gdev->state != CCWGROUP_ONLINE)
 528                 return 0;
 529
 530         return gdrv->prepare ? gdrv->prepare(gdev) : 0;
 531 }
 532
 533 static void ccwgroup_pm_complete(struct device *dev)
 534 {
 535         struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
 536         struct ccwgroup_driver *gdrv = to_ccwgroupdrv(dev->driver);
 537
 538         if (!gdev->dev.driver || gdev->state != CCWGROUP_ONLINE)
 539                 return;
 540
 541         if (gdrv->complete)
 542                 gdrv->complete(gdev);
 543 }
 544
 545 static int ccwgroup_pm_freeze(struct device *dev)
 546 {
 547         struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
 548         struct ccwgroup_driver *gdrv = to_ccwgroupdrv(gdev->dev.driver);
 549
 550         if (!gdev->dev.driver || gdev->state != CCWGROUP_ONLINE)
 551                 return 0;
 552
 553         return gdrv->freeze ? gdrv->freeze(gdev) : 0;
 554 }
 555
 556 static int ccwgroup_pm_thaw(struct device *dev)
 557 {
 558         struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
 559         struct ccwgroup_driver *gdrv = to_ccwgroupdrv(gdev->dev.driver);
 560
 561         if (!gdev->dev.driver || gdev->state != CCWGROUP_ONLINE)
 562                 return 0;
 563
 564         return gdrv->thaw ? gdrv->thaw(gdev) : 0;
 565 }
 566
 567 static int ccwgroup_pm_restore(struct device *dev)
 568 {
 569         struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
 570         struct ccwgroup_driver *gdrv = to_ccwgroupdrv(gdev->dev.driver);
 571
 572         if (!gdev->dev.driver || gdev->state != CCWGROUP_ONLINE)
 573                 return 0;
 574
 575         return gdrv->restore ? gdrv->restore(gdev) : 0;
 576 }
 577
 578 static const struct dev_pm_ops ccwgroup_pm_ops = {
 579         .prepare = ccwgroup_pm_prepare,
 580         .complete = ccwgroup_pm_complete,
 581         .freeze = ccwgroup_pm_freeze,
 582         .thaw = ccwgroup_pm_thaw,
 583         .restore = ccwgroup_pm_restore,
 584 };
 585
 586 static struct bus_type ccwgroup_bus_type = {
 587         .name   = "ccwgroup",
 588         .match  = ccwgroup_bus_match,
 589         .uevent = ccwgroup_uevent,
 590         .probe  = ccwgroup_probe,
 591         .remove = ccwgroup_remove,
 592         .shutdown = ccwgroup_shutdown,
 593         .pm = &ccwgroup_pm_ops,
 594 };
 595
 596
 597 static int ccwgroup_notifier(struct notifier_block *nb, unsigned long action,
 598                              void *data)
 599 {
 600         struct device *dev = data;
 601
 602         if (action == BUS_NOTIFY_UNBIND_DRIVER)
 603                 device_schedule_callback(dev, ccwgroup_ungroup_callback);
 604
 605         return NOTIFY_OK;
 606 }
 607
 608
 609 /**
 610  * ccwgroup_driver_register() - register a ccw group driver
 611  * @cdriver: driver to be registered
 612  *
 613  * This function is mainly a wrapper around driver_register().
 614  */
 615 int ccwgroup_driver_register(struct ccwgroup_driver *cdriver)
 616 {
 617         /* register our new driver with the core */
 618         cdriver->driver.bus = &ccwgroup_bus_type;
 619
 620         return driver_register(&cdriver->driver);
 621 }
 622
 623 static int
 624 __ccwgroup_match_all(struct device *dev, void *data)
 625 {
 626         return 1;
 627 }
 628
 629 /**
 630  * ccwgroup_driver_unregister() - deregister a ccw group driver
 631  * @cdriver: driver to be deregistered
 632  *
 633  * This function is mainly a wrapper around driver_unregister().
 634  */
 635 void ccwgroup_driver_unregister(struct ccwgroup_driver *cdriver)
 636 {
 637         struct device *dev;
 638
 639         /* We don't want ccwgroup devices to live longer than their driver. */
 640         get_driver(&cdriver->driver);
 641         while ((dev = driver_find_device(&cdriver->driver, NULL, NULL,
 642                                          __ccwgroup_match_all))) {
 643                 struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
 644
 645                 mutex_lock(&gdev->reg_mutex);
 646                 __ccwgroup_remove_symlinks(gdev);
 647                 device_unregister(dev);
 648                 __ccwgroup_remove_cdev_refs(gdev);
 649                 mutex_unlock(&gdev->reg_mutex);
 650                 put_device(dev);
 651         }
 652         put_driver(&cdriver->driver);
 653         driver_unregister(&cdriver->driver);
 654 }
 655
 656 /**
 657  * ccwgroup_probe_ccwdev() - probe function for slave devices
 658  * @cdev: ccw device to be probed
 659  *
 660  * This is a dummy probe function for ccw devices that are slave devices in
 661  * a ccw group device.
 662  * Returns:
 663  *  always %0
 664  */
 665 int ccwgroup_probe_ccwdev(struct ccw_device *cdev)
 666 {
 667         return 0;
 668 }
 669
 670 /**
 671  * ccwgroup_remove_ccwdev() - remove function for slave devices
 672  * @cdev: ccw device to be removed
 673  *
 674  * This is a remove function for ccw devices that are slave devices in a ccw
 675  * group device. It sets the ccw device offline and also deregisters the
 676  * embedding ccw group device.
 677  */
 678 void ccwgroup_remove_ccwdev(struct ccw_device *cdev)
 679 {
 680         struct ccwgroup_device *gdev;
 681
 682         /* Ignore offlining errors, device is gone anyway. */
 683         ccw_device_set_offline(cdev);
 684         /* If one of its devices is gone, the whole group is done for. */
 685         spin_lock_irq(cdev->ccwlock);
 686         gdev = dev_get_drvdata(&cdev->dev);
 687         if (!gdev) {
 688                 spin_unlock_irq(cdev->ccwlock);
 689                 return;
 690         }
 691         /* Get ccwgroup device reference for local processing. */
 692         get_device(&gdev->dev);
 693         spin_unlock_irq(cdev->ccwlock);
 694         /* Unregister group device. */
 695         mutex_lock(&gdev->reg_mutex);
 696         if (device_is_registered(&gdev->dev)) {
 697                 __ccwgroup_remove_symlinks(gdev);
 698                 device_unregister(&gdev->dev);
 699                 __ccwgroup_remove_cdev_refs(gdev);
 700         }
 701         mutex_unlock(&gdev->reg_mutex);
 702         /* Release ccwgroup device reference for local processing. */
 703         put_device(&gdev->dev);
 704 }
 705
 706 MODULE_LICENSE("GPL");
 707 EXPORT_SYMBOL(ccwgroup_driver_register);
 708 EXPORT_SYMBOL(ccwgroup_driver_unregister);
 709 EXPORT_SYMBOL(ccwgroup_probe_ccwdev);
 710 EXPORT_SYMBOL(ccwgroup_remove_ccwdev);