drivers/s390/block/dasd_alias.c

   1 /*
   2  * PAV alias management for the DASD ECKD discipline
   3  *
   4  * Copyright IBM Corp. 2007
   5  * Author(s): Stefan Weinhuber <wein@de.ibm.com>
   6  */
   7
   8 #define KMSG_COMPONENT "dasd-eckd"
   9
  10 #include <linux/list.h>
  11 #include <linux/slab.h>
  12 #include <asm/ebcdic.h>
  13 #include "dasd_int.h"
  14 #include "dasd_eckd.h"
  15
  16 #ifdef PRINTK_HEADER
  17 #undef PRINTK_HEADER
  18 #endif                          /* PRINTK_HEADER */
  19 #define PRINTK_HEADER "dasd(eckd):"
  20
  21
  22 /*
  23  * General concept of alias management:
  24  * - PAV and DASD alias management is specific to the eckd discipline.
  25  * - A device is connected to an lcu as long as the device exists.
  26  *   dasd_alias_make_device_known_to_lcu will be called wenn the
  27  *   device is checked by the eckd discipline and
  28  *   dasd_alias_disconnect_device_from_lcu will be called
  29  *   before the device is deleted.
  30  * - The dasd_alias_add_device / dasd_alias_remove_device
  31  *   functions mark the point when a device is 'ready for service'.
  32  * - A summary unit check is a rare occasion, but it is mandatory to
  33  *   support it. It requires some complex recovery actions before the
  34  *   devices can be used again (see dasd_alias_handle_summary_unit_check).
  35  * - dasd_alias_get_start_dev will find an alias device that can be used
  36  *   instead of the base device and does some (very simple) load balancing.
  37  *   This is the function that gets called for each I/O, so when improving
  38  *   something, this function should get faster or better, the rest has just
  39  *   to be correct.
  40  */
  41
  42
  43 static void summary_unit_check_handling_work(struct work_struct *);
  44 static void lcu_update_work(struct work_struct *);
  45 static int _schedule_lcu_update(struct alias_lcu *, struct dasd_device *);
  46
  47 static struct alias_root aliastree = {
  48         .serverlist = LIST_HEAD_INIT(aliastree.serverlist),
  49         .lock = __SPIN_LOCK_UNLOCKED(aliastree.lock),
  50 };
  51
  52 static struct alias_server *_find_server(struct dasd_uid *uid)
  53 {
  54         struct alias_server *pos;
  55         list_for_each_entry(pos, &aliastree.serverlist, server) {
  56                 if (!strncmp(pos->uid.vendor, uid->vendor,
  57                              sizeof(uid->vendor))
  58                     && !strncmp(pos->uid.serial, uid->serial,
  59                                 sizeof(uid->serial)))
  60                         return pos;
  61         }
  62         return NULL;
  63 }
  64
  65 static struct alias_lcu *_find_lcu(struct alias_server *server,
  66                                    struct dasd_uid *uid)
  67 {
  68         struct alias_lcu *pos;
  69         list_for_each_entry(pos, &server->lculist, lcu) {
  70                 if (pos->uid.ssid == uid->ssid)
  71                         return pos;
  72         }
  73         return NULL;
  74 }
  75
  76 static struct alias_pav_group *_find_group(struct alias_lcu *lcu,
  77                                            struct dasd_uid *uid)
  78 {
  79         struct alias_pav_group *pos;
  80         __u8 search_unit_addr;
  81
  82         /* for hyper pav there is only one group */
  83         if (lcu->pav == HYPER_PAV) {
  84                 if (list_empty(&lcu->grouplist))
  85                         return NULL;
  86                 else
  87                         return list_first_entry(&lcu->grouplist,
  88                                                 struct alias_pav_group, group);
  89         }
  90
  91         /* for base pav we have to find the group that matches the base */
  92         if (uid->type == UA_BASE_DEVICE)
  93                 search_unit_addr = uid->real_unit_addr;
  94         else
  95                 search_unit_addr = uid->base_unit_addr;
  96         list_for_each_entry(pos, &lcu->grouplist, group) {
  97                 if (pos->uid.base_unit_addr == search_unit_addr &&
  98                     !strncmp(pos->uid.vduit, uid->vduit, sizeof(uid->vduit)))
  99                         return pos;
 100         }
 101         return NULL;
 102 }
 103
 104 static struct alias_server *_allocate_server(struct dasd_uid *uid)
 105 {
 106         struct alias_server *server;
 107
 108         server = kzalloc(sizeof(*server), GFP_KERNEL);
 109         if (!server)
 110                 return ERR_PTR(-ENOMEM);
 111         memcpy(server->uid.vendor, uid->vendor, sizeof(uid->vendor));
 112         memcpy(server->uid.serial, uid->serial, sizeof(uid->serial));
 113         INIT_LIST_HEAD(&server->server);
 114         INIT_LIST_HEAD(&server->lculist);
 115         return server;
 116 }
 117
 118 static void _free_server(struct alias_server *server)
 119 {
 120         kfree(server);
 121 }
 122
 123 static struct alias_lcu *_allocate_lcu(struct dasd_uid *uid)
 124 {
 125         struct alias_lcu *lcu;
 126
 127         lcu = kzalloc(sizeof(*lcu), GFP_KERNEL);
 128         if (!lcu)
 129                 return ERR_PTR(-ENOMEM);
 130         lcu->uac = kzalloc(sizeof(*(lcu->uac)), GFP_KERNEL | GFP_DMA);
 131         if (!lcu->uac)
 132                 goto out_err1;
 133         lcu->rsu_cqr = kzalloc(sizeof(*lcu->rsu_cqr), GFP_KERNEL | GFP_DMA);
 134         if (!lcu->rsu_cqr)
 135                 goto out_err2;
 136         lcu->rsu_cqr->cpaddr = kzalloc(sizeof(struct ccw1),
 137                                        GFP_KERNEL | GFP_DMA);
 138         if (!lcu->rsu_cqr->cpaddr)
 139                 goto out_err3;
 140         lcu->rsu_cqr->data = kzalloc(16, GFP_KERNEL | GFP_DMA);
 141         if (!lcu->rsu_cqr->data)
 142                 goto out_err4;
 143
 144         memcpy(lcu->uid.vendor, uid->vendor, sizeof(uid->vendor));
 145         memcpy(lcu->uid.serial, uid->serial, sizeof(uid->serial));
 146         lcu->uid.ssid = uid->ssid;
 147         lcu->pav = NO_PAV;
 148         lcu->flags = NEED_UAC_UPDATE | UPDATE_PENDING;
 149         INIT_LIST_HEAD(&lcu->lcu);
 150         INIT_LIST_HEAD(&lcu->inactive_devices);
 151         INIT_LIST_HEAD(&lcu->active_devices);
 152         INIT_LIST_HEAD(&lcu->grouplist);
 153         INIT_WORK(&lcu->suc_data.worker, summary_unit_check_handling_work);
 154         INIT_DELAYED_WORK(&lcu->ruac_data.dwork, lcu_update_work);
 155         spin_lock_init(&lcu->lock);
 156         init_completion(&lcu->lcu_setup);
 157         return lcu;
 158
 159 out_err4:
 160         kfree(lcu->rsu_cqr->cpaddr);
 161 out_err3:
 162         kfree(lcu->rsu_cqr);
 163 out_err2:
 164         kfree(lcu->uac);
 165 out_err1:
 166         kfree(lcu);
 167         return ERR_PTR(-ENOMEM);
 168 }
 169
 170 static void _free_lcu(struct alias_lcu *lcu)
 171 {
 172         kfree(lcu->rsu_cqr->data);
 173         kfree(lcu->rsu_cqr->cpaddr);
 174         kfree(lcu->rsu_cqr);
 175         kfree(lcu->uac);
 176         kfree(lcu);
 177 }
 178
 179 /*
 180  * This is the function that will allocate all the server and lcu data,
 181  * so this function must be called first for a new device.
 182  * If the return value is 1, the lcu was already known before, if it
 183  * is 0, this is a new lcu.
 184  * Negative return code indicates that something went wrong (e.g. -ENOMEM)
 185  */
 186 int dasd_alias_make_device_known_to_lcu(struct dasd_device *device)
 187 {
 188         struct dasd_eckd_private *private = device->private;
 189         unsigned long flags;
 190         struct alias_server *server, *newserver;
 191         struct alias_lcu *lcu, *newlcu;
 192         struct dasd_uid uid;
 193
 194         device->discipline->get_uid(device, &uid);
 195         spin_lock_irqsave(&aliastree.lock, flags);
 196         server = _find_server(&uid);
 197         if (!server) {
 198                 spin_unlock_irqrestore(&aliastree.lock, flags);
 199                 newserver = _allocate_server(&uid);
 200                 if (IS_ERR(newserver))
 201                         return PTR_ERR(newserver);
 202                 spin_lock_irqsave(&aliastree.lock, flags);
 203                 server = _find_server(&uid);
 204                 if (!server) {
 205                         list_add(&newserver->server, &aliastree.serverlist);
 206                         server = newserver;
 207                 } else {
 208                         /* someone was faster */
 209                         _free_server(newserver);
 210                 }
 211         }
 212
 213         lcu = _find_lcu(server, &uid);
 214         if (!lcu) {
 215                 spin_unlock_irqrestore(&aliastree.lock, flags);
 216                 newlcu = _allocate_lcu(&uid);
 217                 if (IS_ERR(newlcu))
 218                         return PTR_ERR(newlcu);
 219                 spin_lock_irqsave(&aliastree.lock, flags);
 220                 lcu = _find_lcu(server, &uid);
 221                 if (!lcu) {
 222                         list_add(&newlcu->lcu, &server->lculist);
 223                         lcu = newlcu;
 224                 } else {
 225                         /* someone was faster */
 226                         _free_lcu(newlcu);
 227                 }
 228         }
 229         spin_lock(&lcu->lock);
 230         list_add(&device->alias_list, &lcu->inactive_devices);
 231         private->lcu = lcu;
 232         spin_unlock(&lcu->lock);
 233         spin_unlock_irqrestore(&aliastree.lock, flags);
 234
 235         return 0;
 236 }
 237
 238 /*
 239  * This function removes a device from the scope of alias management.
 240  * The complicated part is to make sure that it is not in use by
 241  * any of the workers. If necessary cancel the work.
 242  */
 243 void dasd_alias_disconnect_device_from_lcu(struct dasd_device *device)
 244 {
 245         struct dasd_eckd_private *private = device->private;
 246         unsigned long flags;
 247         struct alias_lcu *lcu;
 248         struct alias_server *server;
 249         int was_pending;
 250         struct dasd_uid uid;
 251
 252         lcu = private->lcu;
 253         /* nothing to do if already disconnected */
 254         if (!lcu)
 255                 return;
 256         device->discipline->get_uid(device, &uid);
 257         spin_lock_irqsave(&lcu->lock, flags);
 258         list_del_init(&device->alias_list);
 259         /* make sure that the workers don't use this device */
 260         if (device == lcu->suc_data.device) {
 261                 spin_unlock_irqrestore(&lcu->lock, flags);
 262                 cancel_work_sync(&lcu->suc_data.worker);
 263                 spin_lock_irqsave(&lcu->lock, flags);
 264                 if (device == lcu->suc_data.device) {
 265                         dasd_put_device(device);
 266                         lcu->suc_data.device = NULL;
 267                 }
 268         }
 269         was_pending = 0;
 270         if (device == lcu->ruac_data.device) {
 271                 spin_unlock_irqrestore(&lcu->lock, flags);
 272                 was_pending = 1;
 273                 cancel_delayed_work_sync(&lcu->ruac_data.dwork);
 274                 spin_lock_irqsave(&lcu->lock, flags);
 275                 if (device == lcu->ruac_data.device) {
 276                         dasd_put_device(device);
 277                         lcu->ruac_data.device = NULL;
 278                 }
 279         }
 280         private->lcu = NULL;
 281         spin_unlock_irqrestore(&lcu->lock, flags);
 282
 283         spin_lock_irqsave(&aliastree.lock, flags);
 284         spin_lock(&lcu->lock);
 285         if (list_empty(&lcu->grouplist) &&
 286             list_empty(&lcu->active_devices) &&
 287             list_empty(&lcu->inactive_devices)) {
 288                 list_del(&lcu->lcu);
 289                 spin_unlock(&lcu->lock);
 290                 _free_lcu(lcu);
 291                 lcu = NULL;
 292         } else {
 293                 if (was_pending)
 294                         _schedule_lcu_update(lcu, NULL);
 295                 spin_unlock(&lcu->lock);
 296         }
 297         server = _find_server(&uid);
 298         if (server && list_empty(&server->lculist)) {
 299                 list_del(&server->server);
 300                 _free_server(server);
 301         }
 302         spin_unlock_irqrestore(&aliastree.lock, flags);
 303 }
 304
 305 /*
 306  * This function assumes that the unit address configuration stored
 307  * in the lcu is up to date and will update the device uid before
 308  * adding it to a pav group.
 309  */
 310
 311 static int _add_device_to_lcu(struct alias_lcu *lcu,
 312                               struct dasd_device *device,
 313                               struct dasd_device *pos)
 314 {
 315
 316         struct dasd_eckd_private *private = device->private;
 317         struct alias_pav_group *group;
 318         struct dasd_uid uid;
 319
 320         spin_lock(get_ccwdev_lock(device->cdev));
 321         private->uid.type = lcu->uac->unit[private->uid.real_unit_addr].ua_type;
 322         private->uid.base_unit_addr =
 323                 lcu->uac->unit[private->uid.real_unit_addr].base_ua;
 324         uid = private->uid;
 325         spin_unlock(get_ccwdev_lock(device->cdev));
 326         /* if we have no PAV anyway, we don't need to bother with PAV groups */
 327         if (lcu->pav == NO_PAV) {
 328                 list_move(&device->alias_list, &lcu->active_devices);
 329                 return 0;
 330         }
 331         group = _find_group(lcu, &uid);
 332         if (!group) {
 333                 group = kzalloc(sizeof(*group), GFP_ATOMIC);
 334                 if (!group)
 335                         return -ENOMEM;
 336                 memcpy(group->uid.vendor, uid.vendor, sizeof(uid.vendor));
 337                 memcpy(group->uid.serial, uid.serial, sizeof(uid.serial));
 338                 group->uid.ssid = uid.ssid;
 339                 if (uid.type == UA_BASE_DEVICE)
 340                         group->uid.base_unit_addr = uid.real_unit_addr;
 341                 else
 342                         group->uid.base_unit_addr = uid.base_unit_addr;
 343                 memcpy(group->uid.vduit, uid.vduit, sizeof(uid.vduit));
 344                 INIT_LIST_HEAD(&group->group);
 345                 INIT_LIST_HEAD(&group->baselist);
 346                 INIT_LIST_HEAD(&group->aliaslist);
 347                 list_add(&group->group, &lcu->grouplist);
 348         }
 349         if (uid.type == UA_BASE_DEVICE)
 350                 list_move(&device->alias_list, &group->baselist);
 351         else
 352                 list_move(&device->alias_list, &group->aliaslist);
 353         private->pavgroup = group;
 354         return 0;
 355 };
 356
 357 static void _remove_device_from_lcu(struct alias_lcu *lcu,
 358                                     struct dasd_device *device)
 359 {
 360         struct dasd_eckd_private *private = device->private;
 361         struct alias_pav_group *group;
 362
 363         list_move(&device->alias_list, &lcu->inactive_devices);
 364         group = private->pavgroup;
 365         if (!group)
 366                 return;
 367         private->pavgroup = NULL;
 368         if (list_empty(&group->baselist) && list_empty(&group->aliaslist)) {
 369                 list_del(&group->group);
 370                 kfree(group);
 371                 return;
 372         }
 373         if (group->next == device)
 374                 group->next = NULL;
 375 };
 376
 377 static int
 378 suborder_not_supported(struct dasd_ccw_req *cqr)
 379 {
 380         char *sense;
 381         char reason;
 382         char msg_format;
 383         char msg_no;
 384
 385         sense = dasd_get_sense(&cqr->irb);
 386         if (!sense)
 387                 return 0;
 388
 389         reason = sense[0];
 390         msg_format = (sense[7] & 0xF0);
 391         msg_no = (sense[7] & 0x0F);
 392
 393         /* command reject, Format 0 MSG 4 - invalid parameter */
 394         if ((reason == 0x80) && (msg_format == 0x00) && (msg_no == 0x04))
 395                 return 1;
 396
 397         return 0;
 398 }
 399
 400 static int read_unit_address_configuration(struct dasd_device *device,
 401                                            struct alias_lcu *lcu)
 402 {
 403         struct dasd_psf_prssd_data *prssdp;
 404         struct dasd_ccw_req *cqr;
 405         struct ccw1 *ccw;
 406         int rc;
 407         unsigned long flags;
 408
 409         cqr = dasd_kmalloc_request(DASD_ECKD_MAGIC, 1 /* PSF */ + 1 /* RSSD */,
 410                                    (sizeof(struct dasd_psf_prssd_data)),
 411                                    device);
 412         if (IS_ERR(cqr))
 413                 return PTR_ERR(cqr);
 414         cqr->startdev = device;
 415         cqr->memdev = device;
 416         clear_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
 417         cqr->retries = 10;
 418         cqr->expires = 20 * HZ;
 419
 420         /* Prepare for Read Subsystem Data */
 421         prssdp = (struct dasd_psf_prssd_data *) cqr->data;
 422         memset(prssdp, 0, sizeof(struct dasd_psf_prssd_data));
 423         prssdp->order = PSF_ORDER_PRSSD;
 424         prssdp->suborder = 0x0e;        /* Read unit address configuration */
 425         /* all other bytes of prssdp must be zero */
 426
 427         ccw = cqr->cpaddr;
 428         ccw->cmd_code = DASD_ECKD_CCW_PSF;
 429         ccw->count = sizeof(struct dasd_psf_prssd_data);
 430         ccw->flags |= CCW_FLAG_CC;
 431         ccw->cda = (__u32)(addr_t) prssdp;
 432
 433         /* Read Subsystem Data - feature codes */
 434         memset(lcu->uac, 0, sizeof(*(lcu->uac)));
 435
 436         ccw++;
 437         ccw->cmd_code = DASD_ECKD_CCW_RSSD;
 438         ccw->count = sizeof(*(lcu->uac));
 439         ccw->cda = (__u32)(addr_t) lcu->uac;
 440
 441         cqr->buildclk = get_tod_clock();
 442         cqr->status = DASD_CQR_FILLED;
 443
 444         /* need to unset flag here to detect race with summary unit check */
 445         spin_lock_irqsave(&lcu->lock, flags);
 446         lcu->flags &= ~NEED_UAC_UPDATE;
 447         spin_unlock_irqrestore(&lcu->lock, flags);
 448
 449         do {
 450                 rc = dasd_sleep_on(cqr);
 451                 if (rc && suborder_not_supported(cqr))
 452                         return -EOPNOTSUPP;
 453         } while (rc && (cqr->retries > 0));
 454         if (rc) {
 455                 spin_lock_irqsave(&lcu->lock, flags);
 456                 lcu->flags |= NEED_UAC_UPDATE;
 457                 spin_unlock_irqrestore(&lcu->lock, flags);
 458         }
 459         dasd_kfree_request(cqr, cqr->memdev);
 460         return rc;
 461 }
 462
 463 static int _lcu_update(struct dasd_device *refdev, struct alias_lcu *lcu)
 464 {
 465         unsigned long flags;
 466         struct alias_pav_group *pavgroup, *tempgroup;
 467         struct dasd_device *device, *tempdev;
 468         int i, rc;
 469         struct dasd_eckd_private *private;
 470
 471         spin_lock_irqsave(&lcu->lock, flags);
 472         list_for_each_entry_safe(pavgroup, tempgroup, &lcu->grouplist, group) {
 473                 list_for_each_entry_safe(device, tempdev, &pavgroup->baselist,
 474                                          alias_list) {
 475                         list_move(&device->alias_list, &lcu->active_devices);
 476                         private = device->private;
 477                         private->pavgroup = NULL;
 478                 }
 479                 list_for_each_entry_safe(device, tempdev, &pavgroup->aliaslist,
 480                                          alias_list) {
 481                         list_move(&device->alias_list, &lcu->active_devices);
 482                         private = device->private;
 483                         private->pavgroup = NULL;
 484                 }
 485                 list_del(&pavgroup->group);
 486                 kfree(pavgroup);
 487         }
 488         spin_unlock_irqrestore(&lcu->lock, flags);
 489
 490         rc = read_unit_address_configuration(refdev, lcu);
 491         if (rc)
 492                 return rc;
 493
 494         spin_lock_irqsave(&lcu->lock, flags);
 495         lcu->pav = NO_PAV;
 496         for (i = 0; i < MAX_DEVICES_PER_LCU; ++i) {
 497                 switch (lcu->uac->unit[i].ua_type) {
 498                 case UA_BASE_PAV_ALIAS:
 499                         lcu->pav = BASE_PAV;
 500                         break;
 501                 case UA_HYPER_PAV_ALIAS:
 502                         lcu->pav = HYPER_PAV;
 503                         break;
 504                 }
 505                 if (lcu->pav != NO_PAV)
 506                         break;
 507         }
 508
 509         list_for_each_entry_safe(device, tempdev, &lcu->active_devices,
 510                                  alias_list) {
 511                 _add_device_to_lcu(lcu, device, refdev);
 512         }
 513         spin_unlock_irqrestore(&lcu->lock, flags);
 514         return 0;
 515 }
 516
 517 static void lcu_update_work(struct work_struct *work)
 518 {
 519         struct alias_lcu *lcu;
 520         struct read_uac_work_data *ruac_data;
 521         struct dasd_device *device;
 522         unsigned long flags;
 523         int rc;
 524
 525         ruac_data = container_of(work, struct read_uac_work_data, dwork.work);
 526         lcu = container_of(ruac_data, struct alias_lcu, ruac_data);
 527         device = ruac_data->device;
 528         rc = _lcu_update(device, lcu);
 529         /*
 530          * Need to check flags again, as there could have been another
 531          * prepare_update or a new device a new device while we were still
 532          * processing the data
 533          */
 534         spin_lock_irqsave(&lcu->lock, flags);
 535         if ((rc && (rc != -EOPNOTSUPP)) || (lcu->flags & NEED_UAC_UPDATE)) {
 536                 DBF_DEV_EVENT(DBF_WARNING, device, "could not update"
 537                             " alias data in lcu (rc = %d), retry later", rc);
 538                 if (!schedule_delayed_work(&lcu->ruac_data.dwork, 30*HZ))
 539                         dasd_put_device(device);
 540         } else {
 541                 dasd_put_device(device);
 542                 lcu->ruac_data.device = NULL;
 543                 lcu->flags &= ~UPDATE_PENDING;
 544         }
 545         spin_unlock_irqrestore(&lcu->lock, flags);
 546 }
 547
 548 static int _schedule_lcu_update(struct alias_lcu *lcu,
 549                                 struct dasd_device *device)
 550 {
 551         struct dasd_device *usedev = NULL;
 552         struct alias_pav_group *group;
 553
 554         lcu->flags |= NEED_UAC_UPDATE;
 555         if (lcu->ruac_data.device) {
 556                 /* already scheduled or running */
 557                 return 0;
 558         }
 559         if (device && !list_empty(&device->alias_list))
 560                 usedev = device;
 561
 562         if (!usedev && !list_empty(&lcu->grouplist)) {
 563                 group = list_first_entry(&lcu->grouplist,
 564                                          struct alias_pav_group, group);
 565                 if (!list_empty(&group->baselist))
 566                         usedev = list_first_entry(&group->baselist,
 567                                                   struct dasd_device,
 568                                                   alias_list);
 569                 else if (!list_empty(&group->aliaslist))
 570                         usedev = list_first_entry(&group->aliaslist,
 571                                                   struct dasd_device,
 572                                                   alias_list);
 573         }
 574         if (!usedev && !list_empty(&lcu->active_devices)) {
 575                 usedev = list_first_entry(&lcu->active_devices,
 576                                           struct dasd_device, alias_list);
 577         }
 578         /*
 579          * if we haven't found a proper device yet, give up for now, the next
 580          * device that will be set active will trigger an lcu update
 581          */
 582         if (!usedev)
 583                 return -EINVAL;
 584         dasd_get_device(usedev);
 585         lcu->ruac_data.device = usedev;
 586         if (!schedule_delayed_work(&lcu->ruac_data.dwork, 0))
 587                 dasd_put_device(usedev);
 588         return 0;
 589 }
 590
 591 int dasd_alias_add_device(struct dasd_device *device)
 592 {
 593         struct dasd_eckd_private *private = device->private;
 594         struct alias_lcu *lcu;
 595         unsigned long flags;
 596         int rc;
 597
 598         lcu = private->lcu;
 599         rc = 0;
 600         spin_lock_irqsave(&lcu->lock, flags);
 601         if (!(lcu->flags & UPDATE_PENDING)) {
 602                 rc = _add_device_to_lcu(lcu, device, device);
 603                 if (rc)
 604                         lcu->flags |= UPDATE_PENDING;
 605         }
 606         if (lcu->flags & UPDATE_PENDING) {
 607                 list_move(&device->alias_list, &lcu->active_devices);
 608                 _schedule_lcu_update(lcu, device);
 609         }
 610         spin_unlock_irqrestore(&lcu->lock, flags);
 611         return rc;
 612 }
 613
 614 int dasd_alias_update_add_device(struct dasd_device *device)
 615 {
 616         struct dasd_eckd_private *private = device->private;
 617
 618         private->lcu->flags |= UPDATE_PENDING;
 619         return dasd_alias_add_device(device);
 620 }
 621
 622 int dasd_alias_remove_device(struct dasd_device *device)
 623 {
 624         struct dasd_eckd_private *private = device->private;
 625         struct alias_lcu *lcu = private->lcu;
 626         unsigned long flags;
 627
 628         /* nothing to do if already removed */
 629         if (!lcu)
 630                 return 0;
 631         spin_lock_irqsave(&lcu->lock, flags);
 632         _remove_device_from_lcu(lcu, device);
 633         spin_unlock_irqrestore(&lcu->lock, flags);
 634         return 0;
 635 }
 636
 637 struct dasd_device *dasd_alias_get_start_dev(struct dasd_device *base_device)
 638 {
 639         struct dasd_eckd_private *alias_priv, *private = base_device->private;
 640         struct alias_pav_group *group = private->pavgroup;
 641         struct alias_lcu *lcu = private->lcu;
 642         struct dasd_device *alias_device;
 643         unsigned long flags;
 644
 645         if (!group || !lcu)
 646                 return NULL;
 647         if (lcu->pav == NO_PAV ||
 648             lcu->flags & (NEED_UAC_UPDATE | UPDATE_PENDING))
 649                 return NULL;
 650         if (unlikely(!(private->features.feature[8] & 0x01))) {
 651                 /*
 652                  * PAV enabled but prefix not, very unlikely
 653                  * seems to be a lost pathgroup
 654                  * use base device to do IO
 655                  */
 656                 DBF_DEV_EVENT(DBF_ERR, base_device, "%s",
 657                               "Prefix not enabled with PAV enabled\n");
 658                 return NULL;
 659         }
 660
 661         spin_lock_irqsave(&lcu->lock, flags);
 662         alias_device = group->next;
 663         if (!alias_device) {
 664                 if (list_empty(&group->aliaslist)) {
 665                         spin_unlock_irqrestore(&lcu->lock, flags);
 666                         return NULL;
 667                 } else {
 668                         alias_device = list_first_entry(&group->aliaslist,
 669                                                         struct dasd_device,
 670                                                         alias_list);
 671                 }
 672         }
 673         if (list_is_last(&alias_device->alias_list, &group->aliaslist))
 674                 group->next = list_first_entry(&group->aliaslist,
 675                                                struct dasd_device, alias_list);
 676         else
 677                 group->next = list_first_entry(&alias_device->alias_list,
 678                                                struct dasd_device, alias_list);
 679         spin_unlock_irqrestore(&lcu->lock, flags);
 680         alias_priv = alias_device->private;
 681         if ((alias_priv->count < private->count) && !alias_device->stopped &&
 682             !test_bit(DASD_FLAG_OFFLINE, &alias_device->flags))
 683                 return alias_device;
 684         else
 685                 return NULL;
 686 }
 687
 688 /*
 689  * Summary unit check handling depends on the way alias devices
 690  * are handled so it is done here rather then in dasd_eckd.c
 691  */
 692 static int reset_summary_unit_check(struct alias_lcu *lcu,
 693                                     struct dasd_device *device,
 694                                     char reason)
 695 {
 696         struct dasd_ccw_req *cqr;
 697         int rc = 0;
 698         struct ccw1 *ccw;
 699
 700         cqr = lcu->rsu_cqr;
 701         strncpy((char *) &cqr->magic, "ECKD", 4);
 702         ASCEBC((char *) &cqr->magic, 4);
 703         ccw = cqr->cpaddr;
 704         ccw->cmd_code = DASD_ECKD_CCW_RSCK;
 705         ccw->flags = CCW_FLAG_SLI;
 706         ccw->count = 16;
 707         ccw->cda = (__u32)(addr_t) cqr->data;
 708         ((char *)cqr->data)[0] = reason;
 709
 710         clear_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
 711         cqr->retries = 255;     /* set retry counter to enable basic ERP */
 712         cqr->startdev = device;
 713         cqr->memdev = device;
 714         cqr->block = NULL;
 715         cqr->expires = 5 * HZ;
 716         cqr->buildclk = get_tod_clock();
 717         cqr->status = DASD_CQR_FILLED;
 718
 719         rc = dasd_sleep_on_immediatly(cqr);
 720         return rc;
 721 }
 722
 723 static void _restart_all_base_devices_on_lcu(struct alias_lcu *lcu)
 724 {
 725         struct alias_pav_group *pavgroup;
 726         struct dasd_device *device;
 727         struct dasd_eckd_private *private;
 728
 729         /* active and inactive list can contain alias as well as base devices */
 730         list_for_each_entry(device, &lcu->active_devices, alias_list) {
 731                 private = device->private;
 732                 if (private->uid.type != UA_BASE_DEVICE)
 733                         continue;
 734                 dasd_schedule_block_bh(device->block);
 735                 dasd_schedule_device_bh(device);
 736         }
 737         list_for_each_entry(device, &lcu->inactive_devices, alias_list) {
 738                 private = device->private;
 739                 if (private->uid.type != UA_BASE_DEVICE)
 740                         continue;
 741                 dasd_schedule_block_bh(device->block);
 742                 dasd_schedule_device_bh(device);
 743         }
 744         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 745                 list_for_each_entry(device, &pavgroup->baselist, alias_list) {
 746                         dasd_schedule_block_bh(device->block);
 747                         dasd_schedule_device_bh(device);
 748                 }
 749         }
 750 }
 751
 752 static void flush_all_alias_devices_on_lcu(struct alias_lcu *lcu)
 753 {
 754         struct alias_pav_group *pavgroup;
 755         struct dasd_device *device, *temp;
 756         struct dasd_eckd_private *private;
 757         int rc;
 758         unsigned long flags;
 759         LIST_HEAD(active);
 760
 761         /*
 762          * Problem here ist that dasd_flush_device_queue may wait
 763          * for termination of a request to complete. We can't keep
 764          * the lcu lock during that time, so we must assume that
 765          * the lists may have changed.
 766          * Idea: first gather all active alias devices in a separate list,
 767          * then flush the first element of this list unlocked, and afterwards
 768          * check if it is still on the list before moving it to the
 769          * active_devices list.
 770          */
 771
 772         spin_lock_irqsave(&lcu->lock, flags);
 773         list_for_each_entry_safe(device, temp, &lcu->active_devices,
 774                                  alias_list) {
 775                 private = device->private;
 776                 if (private->uid.type == UA_BASE_DEVICE)
 777                         continue;
 778                 list_move(&device->alias_list, &active);
 779         }
 780
 781         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 782                 list_splice_init(&pavgroup->aliaslist, &active);
 783         }
 784         while (!list_empty(&active)) {
 785                 device = list_first_entry(&active, struct dasd_device,
 786                                           alias_list);
 787                 spin_unlock_irqrestore(&lcu->lock, flags);
 788                 rc = dasd_flush_device_queue(device);
 789                 spin_lock_irqsave(&lcu->lock, flags);
 790                 /*
 791                  * only move device around if it wasn't moved away while we
 792                  * were waiting for the flush
 793                  */
 794                 if (device == list_first_entry(&active,
 795                                                struct dasd_device, alias_list)) {
 796                         list_move(&device->alias_list, &lcu->active_devices);
 797                         private = device->private;
 798                         private->pavgroup = NULL;
 799                 }
 800         }
 801         spin_unlock_irqrestore(&lcu->lock, flags);
 802 }
 803
 804 static void _stop_all_devices_on_lcu(struct alias_lcu *lcu)
 805 {
 806         struct alias_pav_group *pavgroup;
 807         struct dasd_device *device;
 808
 809         list_for_each_entry(device, &lcu->active_devices, alias_list) {
 810                 spin_lock(get_ccwdev_lock(device->cdev));
 811                 dasd_device_set_stop_bits(device, DASD_STOPPED_SU);
 812                 spin_unlock(get_ccwdev_lock(device->cdev));
 813         }
 814         list_for_each_entry(device, &lcu->inactive_devices, alias_list) {
 815                 spin_lock(get_ccwdev_lock(device->cdev));
 816                 dasd_device_set_stop_bits(device, DASD_STOPPED_SU);
 817                 spin_unlock(get_ccwdev_lock(device->cdev));
 818         }
 819         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 820                 list_for_each_entry(device, &pavgroup->baselist, alias_list) {
 821                         spin_lock(get_ccwdev_lock(device->cdev));
 822                         dasd_device_set_stop_bits(device, DASD_STOPPED_SU);
 823                         spin_unlock(get_ccwdev_lock(device->cdev));
 824                 }
 825                 list_for_each_entry(device, &pavgroup->aliaslist, alias_list) {
 826                         spin_lock(get_ccwdev_lock(device->cdev));
 827                         dasd_device_set_stop_bits(device, DASD_STOPPED_SU);
 828                         spin_unlock(get_ccwdev_lock(device->cdev));
 829                 }
 830         }
 831 }
 832
 833 static void _unstop_all_devices_on_lcu(struct alias_lcu *lcu)
 834 {
 835         struct alias_pav_group *pavgroup;
 836         struct dasd_device *device;
 837
 838         list_for_each_entry(device, &lcu->active_devices, alias_list) {
 839                 spin_lock(get_ccwdev_lock(device->cdev));
 840                 dasd_device_remove_stop_bits(device, DASD_STOPPED_SU);
 841                 spin_unlock(get_ccwdev_lock(device->cdev));
 842         }
 843         list_for_each_entry(device, &lcu->inactive_devices, alias_list) {
 844                 spin_lock(get_ccwdev_lock(device->cdev));
 845                 dasd_device_remove_stop_bits(device, DASD_STOPPED_SU);
 846                 spin_unlock(get_ccwdev_lock(device->cdev));
 847         }
 848         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 849                 list_for_each_entry(device, &pavgroup->baselist, alias_list) {
 850                         spin_lock(get_ccwdev_lock(device->cdev));
 851                         dasd_device_remove_stop_bits(device, DASD_STOPPED_SU);
 852                         spin_unlock(get_ccwdev_lock(device->cdev));
 853                 }
 854                 list_for_each_entry(device, &pavgroup->aliaslist, alias_list) {
 855                         spin_lock(get_ccwdev_lock(device->cdev));
 856                         dasd_device_remove_stop_bits(device, DASD_STOPPED_SU);
 857                         spin_unlock(get_ccwdev_lock(device->cdev));
 858                 }
 859         }
 860 }
 861
 862 static void summary_unit_check_handling_work(struct work_struct *work)
 863 {
 864         struct alias_lcu *lcu;
 865         struct summary_unit_check_work_data *suc_data;
 866         unsigned long flags;
 867         struct dasd_device *device;
 868
 869         suc_data = container_of(work, struct summary_unit_check_work_data,
 870                                 worker);
 871         lcu = container_of(suc_data, struct alias_lcu, suc_data);
 872         device = suc_data->device;
 873
 874         /* 1. flush alias devices */
 875         flush_all_alias_devices_on_lcu(lcu);
 876
 877         /* 2. reset summary unit check */
 878         spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 879         dasd_device_remove_stop_bits(device,
 880                                      (DASD_STOPPED_SU | DASD_STOPPED_PENDING));
 881         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 882         reset_summary_unit_check(lcu, device, suc_data->reason);
 883
 884         spin_lock_irqsave(&lcu->lock, flags);
 885         _unstop_all_devices_on_lcu(lcu);
 886         _restart_all_base_devices_on_lcu(lcu);
 887         /* 3. read new alias configuration */
 888         _schedule_lcu_update(lcu, device);
 889         lcu->suc_data.device = NULL;
 890         dasd_put_device(device);
 891         spin_unlock_irqrestore(&lcu->lock, flags);
 892 }
 893
 894 void dasd_alias_handle_summary_unit_check(struct work_struct *work)
 895 {
 896         struct dasd_device *device = container_of(work, struct dasd_device,
 897                                                   suc_work);
 898         struct dasd_eckd_private *private = device->private;
 899         struct alias_lcu *lcu;
 900         unsigned long flags;
 901
 902         lcu = private->lcu;
 903         if (!lcu) {
 904                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
 905                             "device not ready to handle summary"
 906                             " unit check (no lcu structure)");
 907                 goto out;
 908         }
 909         spin_lock_irqsave(&lcu->lock, flags);
 910         /* If this device is about to be removed just return and wait for
 911          * the next interrupt on a different device
 912          */
 913         if (list_empty(&device->alias_list)) {
 914                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
 915                             "device is in offline processing,"
 916                             " don't do summary unit check handling");
 917                 goto out_unlock;
 918         }
 919         if (lcu->suc_data.device) {
 920                 /* already scheduled or running */
 921                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
 922                             "previous instance of summary unit check worker"
 923                             " still pending");
 924                 goto out_unlock;
 925         }
 926         _stop_all_devices_on_lcu(lcu);
 927         /* prepare for lcu_update */
 928         lcu->flags |= NEED_UAC_UPDATE | UPDATE_PENDING;
 929         lcu->suc_data.reason = private->suc_reason;
 930         lcu->suc_data.device = device;
 931         dasd_get_device(device);
 932         if (!schedule_work(&lcu->suc_data.worker))
 933                 dasd_put_device(device);
 934 out_unlock:
 935         spin_unlock_irqrestore(&lcu->lock, flags);
 936 out:
 937         clear_bit(DASD_FLAG_SUC, &device->flags);
 938         dasd_put_device(device);
 939 };