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