drivers/s390/block/dasd_alias.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * PAV alias management for the DASD ECKD discipline
   4  *
   5  * Copyright IBM Corp. 2007
   6  * Author(s): Stefan Weinhuber <wein@de.ibm.com>
   7  */
   8
   9 #define KMSG_COMPONENT "dasd-eckd"
  10
  11 #include <linux/list.h>
  12 #include <linux/slab.h>
  13 #include <asm/ebcdic.h>
  14 #include "dasd_int.h"
  15 #include "dasd_eckd.h"
  16
  17 #ifdef PRINTK_HEADER
  18 #undef PRINTK_HEADER
  19 #endif                          /* PRINTK_HEADER */
  20 #define PRINTK_HEADER "dasd(eckd):"
  21
  22
  23 /*
  24  * General concept of alias management:
  25  * - PAV and DASD alias management is specific to the eckd discipline.
  26  * - A device is connected to an lcu as long as the device exists.
  27  *   dasd_alias_make_device_known_to_lcu will be called wenn the
  28  *   device is checked by the eckd discipline and
  29  *   dasd_alias_disconnect_device_from_lcu will be called
  30  *   before the device is deleted.
  31  * - The dasd_alias_add_device / dasd_alias_remove_device
  32  *   functions mark the point when a device is 'ready for service'.
  33  * - A summary unit check is a rare occasion, but it is mandatory to
  34  *   support it. It requires some complex recovery actions before the
  35  *   devices can be used again (see dasd_alias_handle_summary_unit_check).
  36  * - dasd_alias_get_start_dev will find an alias device that can be used
  37  *   instead of the base device and does some (very simple) load balancing.
  38  *   This is the function that gets called for each I/O, so when improving
  39  *   something, this function should get faster or better, the rest has just
  40  *   to be correct.
  41  */
  42
  43
  44 static void summary_unit_check_handling_work(struct work_struct *);
  45 static void lcu_update_work(struct work_struct *);
  46 static int _schedule_lcu_update(struct alias_lcu *, struct dasd_device *);
  47
  48 static struct alias_root aliastree = {
  49         .serverlist = LIST_HEAD_INIT(aliastree.serverlist),
  50         .lock = __SPIN_LOCK_UNLOCKED(aliastree.lock),
  51 };
  52
  53 static struct alias_server *_find_server(struct dasd_uid *uid)
  54 {
  55         struct alias_server *pos;
  56         list_for_each_entry(pos, &aliastree.serverlist, server) {
  57                 if (!strncmp(pos->uid.vendor, uid->vendor,
  58                              sizeof(uid->vendor))
  59                     && !strncmp(pos->uid.serial, uid->serial,
  60                                 sizeof(uid->serial)))
  61                         return pos;
  62         }
  63         return NULL;
  64 }
  65
  66 static struct alias_lcu *_find_lcu(struct alias_server *server,
  67                                    struct dasd_uid *uid)
  68 {
  69         struct alias_lcu *pos;
  70         list_for_each_entry(pos, &server->lculist, lcu) {
  71                 if (pos->uid.ssid == uid->ssid)
  72                         return pos;
  73         }
  74         return NULL;
  75 }
  76
  77 static struct alias_pav_group *_find_group(struct alias_lcu *lcu,
  78                                            struct dasd_uid *uid)
  79 {
  80         struct alias_pav_group *pos;
  81         __u8 search_unit_addr;
  82
  83         /* for hyper pav there is only one group */
  84         if (lcu->pav == HYPER_PAV) {
  85                 if (list_empty(&lcu->grouplist))
  86                         return NULL;
  87                 else
  88                         return list_first_entry(&lcu->grouplist,
  89                                                 struct alias_pav_group, group);
  90         }
  91
  92         /* for base pav we have to find the group that matches the base */
  93         if (uid->type == UA_BASE_DEVICE)
  94                 search_unit_addr = uid->real_unit_addr;
  95         else
  96                 search_unit_addr = uid->base_unit_addr;
  97         list_for_each_entry(pos, &lcu->grouplist, group) {
  98                 if (pos->uid.base_unit_addr == search_unit_addr &&
  99                     !strncmp(pos->uid.vduit, uid->vduit, sizeof(uid->vduit)))
 100                         return pos;
 101         }
 102         return NULL;
 103 }
 104
 105 static struct alias_server *_allocate_server(struct dasd_uid *uid)
 106 {
 107         struct alias_server *server;
 108
 109         server = kzalloc(sizeof(*server), GFP_KERNEL);
 110         if (!server)
 111                 return ERR_PTR(-ENOMEM);
 112         memcpy(server->uid.vendor, uid->vendor, sizeof(uid->vendor));
 113         memcpy(server->uid.serial, uid->serial, sizeof(uid->serial));
 114         INIT_LIST_HEAD(&server->server);
 115         INIT_LIST_HEAD(&server->lculist);
 116         return server;
 117 }
 118
 119 static void _free_server(struct alias_server *server)
 120 {
 121         kfree(server);
 122 }
 123
 124 static struct alias_lcu *_allocate_lcu(struct dasd_uid *uid)
 125 {
 126         struct alias_lcu *lcu;
 127
 128         lcu = kzalloc(sizeof(*lcu), GFP_KERNEL);
 129         if (!lcu)
 130                 return ERR_PTR(-ENOMEM);
 131         lcu->uac = kzalloc(sizeof(*(lcu->uac)), GFP_KERNEL | GFP_DMA);
 132         if (!lcu->uac)
 133                 goto out_err1;
 134         lcu->rsu_cqr = kzalloc(sizeof(*lcu->rsu_cqr), GFP_KERNEL | GFP_DMA);
 135         if (!lcu->rsu_cqr)
 136                 goto out_err2;
 137         lcu->rsu_cqr->cpaddr = kzalloc(sizeof(struct ccw1),
 138                                        GFP_KERNEL | GFP_DMA);
 139         if (!lcu->rsu_cqr->cpaddr)
 140                 goto out_err3;
 141         lcu->rsu_cqr->data = kzalloc(16, GFP_KERNEL | GFP_DMA);
 142         if (!lcu->rsu_cqr->data)
 143                 goto out_err4;
 144
 145         memcpy(lcu->uid.vendor, uid->vendor, sizeof(uid->vendor));
 146         memcpy(lcu->uid.serial, uid->serial, sizeof(uid->serial));
 147         lcu->uid.ssid = uid->ssid;
 148         lcu->pav = NO_PAV;
 149         lcu->flags = NEED_UAC_UPDATE | UPDATE_PENDING;
 150         INIT_LIST_HEAD(&lcu->lcu);
 151         INIT_LIST_HEAD(&lcu->inactive_devices);
 152         INIT_LIST_HEAD(&lcu->active_devices);
 153         INIT_LIST_HEAD(&lcu->grouplist);
 154         INIT_WORK(&lcu->suc_data.worker, summary_unit_check_handling_work);
 155         INIT_DELAYED_WORK(&lcu->ruac_data.dwork, lcu_update_work);
 156         spin_lock_init(&lcu->lock);
 157         init_completion(&lcu->lcu_setup);
 158         return lcu;
 159
 160 out_err4:
 161         kfree(lcu->rsu_cqr->cpaddr);
 162 out_err3:
 163         kfree(lcu->rsu_cqr);
 164 out_err2:
 165         kfree(lcu->uac);
 166 out_err1:
 167         kfree(lcu);
 168         return ERR_PTR(-ENOMEM);
 169 }
 170
 171 static void _free_lcu(struct alias_lcu *lcu)
 172 {
 173         kfree(lcu->rsu_cqr->data);
 174         kfree(lcu->rsu_cqr->cpaddr);
 175         kfree(lcu->rsu_cqr);
 176         kfree(lcu->uac);
 177         kfree(lcu);
 178 }
 179
 180 /*
 181  * This is the function that will allocate all the server and lcu data,
 182  * so this function must be called first for a new device.
 183  * If the return value is 1, the lcu was already known before, if it
 184  * is 0, this is a new lcu.
 185  * Negative return code indicates that something went wrong (e.g. -ENOMEM)
 186  */
 187 int dasd_alias_make_device_known_to_lcu(struct dasd_device *device)
 188 {
 189         struct dasd_eckd_private *private = device->private;
 190         unsigned long flags;
 191         struct alias_server *server, *newserver;
 192         struct alias_lcu *lcu, *newlcu;
 193         struct dasd_uid uid;
 194
 195         device->discipline->get_uid(device, &uid);
 196         spin_lock_irqsave(&aliastree.lock, flags);
 197         server = _find_server(&uid);
 198         if (!server) {
 199                 spin_unlock_irqrestore(&aliastree.lock, flags);
 200                 newserver = _allocate_server(&uid);
 201                 if (IS_ERR(newserver))
 202                         return PTR_ERR(newserver);
 203                 spin_lock_irqsave(&aliastree.lock, flags);
 204                 server = _find_server(&uid);
 205                 if (!server) {
 206                         list_add(&newserver->server, &aliastree.serverlist);
 207                         server = newserver;
 208                 } else {
 209                         /* someone was faster */
 210                         _free_server(newserver);
 211                 }
 212         }
 213
 214         lcu = _find_lcu(server, &uid);
 215         if (!lcu) {
 216                 spin_unlock_irqrestore(&aliastree.lock, flags);
 217                 newlcu = _allocate_lcu(&uid);
 218                 if (IS_ERR(newlcu))
 219                         return PTR_ERR(newlcu);
 220                 spin_lock_irqsave(&aliastree.lock, flags);
 221                 lcu = _find_lcu(server, &uid);
 222                 if (!lcu) {
 223                         list_add(&newlcu->lcu, &server->lculist);
 224                         lcu = newlcu;
 225                 } else {
 226                         /* someone was faster */
 227                         _free_lcu(newlcu);
 228                 }
 229         }
 230         spin_lock(&lcu->lock);
 231         list_add(&device->alias_list, &lcu->inactive_devices);
 232         private->lcu = lcu;
 233         spin_unlock(&lcu->lock);
 234         spin_unlock_irqrestore(&aliastree.lock, flags);
 235
 236         return 0;
 237 }
 238
 239 /*
 240  * This function removes a device from the scope of alias management.
 241  * The complicated part is to make sure that it is not in use by
 242  * any of the workers. If necessary cancel the work.
 243  */
 244 void dasd_alias_disconnect_device_from_lcu(struct dasd_device *device)
 245 {
 246         struct dasd_eckd_private *private = device->private;
 247         unsigned long flags;
 248         struct alias_lcu *lcu;
 249         struct alias_server *server;
 250         int was_pending;
 251         struct dasd_uid uid;
 252
 253         lcu = private->lcu;
 254         /* nothing to do if already disconnected */
 255         if (!lcu)
 256                 return;
 257         device->discipline->get_uid(device, &uid);
 258         spin_lock_irqsave(&lcu->lock, flags);
 259         list_del_init(&device->alias_list);
 260         /* make sure that the workers don't use this device */
 261         if (device == lcu->suc_data.device) {
 262                 spin_unlock_irqrestore(&lcu->lock, flags);
 263                 cancel_work_sync(&lcu->suc_data.worker);
 264                 spin_lock_irqsave(&lcu->lock, flags);
 265                 if (device == lcu->suc_data.device) {
 266                         dasd_put_device(device);
 267                         lcu->suc_data.device = NULL;
 268                 }
 269         }
 270         was_pending = 0;
 271         if (device == lcu->ruac_data.device) {
 272                 spin_unlock_irqrestore(&lcu->lock, flags);
 273                 was_pending = 1;
 274                 cancel_delayed_work_sync(&lcu->ruac_data.dwork);
 275                 spin_lock_irqsave(&lcu->lock, flags);
 276                 if (device == lcu->ruac_data.device) {
 277                         dasd_put_device(device);
 278                         lcu->ruac_data.device = NULL;
 279                 }
 280         }
 281         private->lcu = NULL;
 282         spin_unlock_irqrestore(&lcu->lock, flags);
 283
 284         spin_lock_irqsave(&aliastree.lock, flags);
 285         spin_lock(&lcu->lock);
 286         if (list_empty(&lcu->grouplist) &&
 287             list_empty(&lcu->active_devices) &&
 288             list_empty(&lcu->inactive_devices)) {
 289                 list_del(&lcu->lcu);
 290                 spin_unlock(&lcu->lock);
 291                 _free_lcu(lcu);
 292                 lcu = NULL;
 293         } else {
 294                 if (was_pending)
 295                         _schedule_lcu_update(lcu, NULL);
 296                 spin_unlock(&lcu->lock);
 297         }
 298         server = _find_server(&uid);
 299         if (server && list_empty(&server->lculist)) {
 300                 list_del(&server->server);
 301                 _free_server(server);
 302         }
 303         spin_unlock_irqrestore(&aliastree.lock, flags);
 304 }
 305
 306 /*
 307  * This function assumes that the unit address configuration stored
 308  * in the lcu is up to date and will update the device uid before
 309  * adding it to a pav group.
 310  */
 311
 312 static int _add_device_to_lcu(struct alias_lcu *lcu,
 313                               struct dasd_device *device,
 314                               struct dasd_device *pos)
 315 {
 316
 317         struct dasd_eckd_private *private = device->private;
 318         struct alias_pav_group *group;
 319         struct dasd_uid uid;
 320
 321         spin_lock(get_ccwdev_lock(device->cdev));
 322         private->uid.type = lcu->uac->unit[private->uid.real_unit_addr].ua_type;
 323         private->uid.base_unit_addr =
 324                 lcu->uac->unit[private->uid.real_unit_addr].base_ua;
 325         uid = private->uid;
 326         spin_unlock(get_ccwdev_lock(device->cdev));
 327         /* if we have no PAV anyway, we don't need to bother with PAV groups */
 328         if (lcu->pav == NO_PAV) {
 329                 list_move(&device->alias_list, &lcu->active_devices);
 330                 return 0;
 331         }
 332         group = _find_group(lcu, &uid);
 333         if (!group) {
 334                 group = kzalloc(sizeof(*group), GFP_ATOMIC);
 335                 if (!group)
 336                         return -ENOMEM;
 337                 memcpy(group->uid.vendor, uid.vendor, sizeof(uid.vendor));
 338                 memcpy(group->uid.serial, uid.serial, sizeof(uid.serial));
 339                 group->uid.ssid = uid.ssid;
 340                 if (uid.type == UA_BASE_DEVICE)
 341                         group->uid.base_unit_addr = uid.real_unit_addr;
 342                 else
 343                         group->uid.base_unit_addr = uid.base_unit_addr;
 344                 memcpy(group->uid.vduit, uid.vduit, sizeof(uid.vduit));
 345                 INIT_LIST_HEAD(&group->group);
 346                 INIT_LIST_HEAD(&group->baselist);
 347                 INIT_LIST_HEAD(&group->aliaslist);
 348                 list_add(&group->group, &lcu->grouplist);
 349         }
 350         if (uid.type == UA_BASE_DEVICE)
 351                 list_move(&device->alias_list, &group->baselist);
 352         else
 353                 list_move(&device->alias_list, &group->aliaslist);
 354         private->pavgroup = group;
 355         return 0;
 356 };
 357
 358 static void _remove_device_from_lcu(struct alias_lcu *lcu,
 359                                     struct dasd_device *device)
 360 {
 361         struct dasd_eckd_private *private = device->private;
 362         struct alias_pav_group *group;
 363
 364         list_move(&device->alias_list, &lcu->inactive_devices);
 365         group = private->pavgroup;
 366         if (!group)
 367                 return;
 368         private->pavgroup = NULL;
 369         if (list_empty(&group->baselist) && list_empty(&group->aliaslist)) {
 370                 list_del(&group->group);
 371                 kfree(group);
 372                 return;
 373         }
 374         if (group->next == device)
 375                 group->next = NULL;
 376 };
 377
 378 static int
 379 suborder_not_supported(struct dasd_ccw_req *cqr)
 380 {
 381         char *sense;
 382         char reason;
 383         char msg_format;
 384         char msg_no;
 385
 386         sense = dasd_get_sense(&cqr->irb);
 387         if (!sense)
 388                 return 0;
 389
 390         reason = sense[0];
 391         msg_format = (sense[7] & 0xF0);
 392         msg_no = (sense[7] & 0x0F);
 393
 394         /* command reject, Format 0 MSG 4 - invalid parameter */
 395         if ((reason == 0x80) && (msg_format == 0x00) && (msg_no == 0x04))
 396                 return 1;
 397
 398         return 0;
 399 }
 400
 401 static int read_unit_address_configuration(struct dasd_device *device,
 402                                            struct alias_lcu *lcu)
 403 {
 404         struct dasd_psf_prssd_data *prssdp;
 405         struct dasd_ccw_req *cqr;
 406         struct ccw1 *ccw;
 407         int rc;
 408         unsigned long flags;
 409
 410         cqr = dasd_kmalloc_request(DASD_ECKD_MAGIC, 1 /* PSF */ + 1 /* RSSD */,
 411                                    (sizeof(struct dasd_psf_prssd_data)),
 412                                    device);
 413         if (IS_ERR(cqr))
 414                 return PTR_ERR(cqr);
 415         cqr->startdev = device;
 416         cqr->memdev = device;
 417         clear_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
 418         cqr->retries = 10;
 419         cqr->expires = 20 * HZ;
 420
 421         /* Prepare for Read Subsystem Data */
 422         prssdp = (struct dasd_psf_prssd_data *) cqr->data;
 423         memset(prssdp, 0, sizeof(struct dasd_psf_prssd_data));
 424         prssdp->order = PSF_ORDER_PRSSD;
 425         prssdp->suborder = 0x0e;        /* Read unit address configuration */
 426         /* all other bytes of prssdp must be zero */
 427
 428         ccw = cqr->cpaddr;
 429         ccw->cmd_code = DASD_ECKD_CCW_PSF;
 430         ccw->count = sizeof(struct dasd_psf_prssd_data);
 431         ccw->flags |= CCW_FLAG_CC;
 432         ccw->cda = (__u32)(addr_t) prssdp;
 433
 434         /* Read Subsystem Data - feature codes */
 435         memset(lcu->uac, 0, sizeof(*(lcu->uac)));
 436
 437         ccw++;
 438         ccw->cmd_code = DASD_ECKD_CCW_RSSD;
 439         ccw->count = sizeof(*(lcu->uac));
 440         ccw->cda = (__u32)(addr_t) lcu->uac;
 441
 442         cqr->buildclk = get_tod_clock();
 443         cqr->status = DASD_CQR_FILLED;
 444
 445         /* need to unset flag here to detect race with summary unit check */
 446         spin_lock_irqsave(&lcu->lock, flags);
 447         lcu->flags &= ~NEED_UAC_UPDATE;
 448         spin_unlock_irqrestore(&lcu->lock, flags);
 449
 450         do {
 451                 rc = dasd_sleep_on(cqr);
 452                 if (rc && suborder_not_supported(cqr))
 453                         return -EOPNOTSUPP;
 454         } while (rc && (cqr->retries > 0));
 455         if (rc) {
 456                 spin_lock_irqsave(&lcu->lock, flags);
 457                 lcu->flags |= NEED_UAC_UPDATE;
 458                 spin_unlock_irqrestore(&lcu->lock, flags);
 459         }
 460         dasd_kfree_request(cqr, cqr->memdev);
 461         return rc;
 462 }
 463
 464 static int _lcu_update(struct dasd_device *refdev, struct alias_lcu *lcu)
 465 {
 466         unsigned long flags;
 467         struct alias_pav_group *pavgroup, *tempgroup;
 468         struct dasd_device *device, *tempdev;
 469         int i, rc;
 470         struct dasd_eckd_private *private;
 471
 472         spin_lock_irqsave(&lcu->lock, flags);
 473         list_for_each_entry_safe(pavgroup, tempgroup, &lcu->grouplist, group) {
 474                 list_for_each_entry_safe(device, tempdev, &pavgroup->baselist,
 475                                          alias_list) {
 476                         list_move(&device->alias_list, &lcu->active_devices);
 477                         private = device->private;
 478                         private->pavgroup = NULL;
 479                 }
 480                 list_for_each_entry_safe(device, tempdev, &pavgroup->aliaslist,
 481                                          alias_list) {
 482                         list_move(&device->alias_list, &lcu->active_devices);
 483                         private = device->private;
 484                         private->pavgroup = NULL;
 485                 }
 486                 list_del(&pavgroup->group);
 487                 kfree(pavgroup);
 488         }
 489         spin_unlock_irqrestore(&lcu->lock, flags);
 490
 491         rc = read_unit_address_configuration(refdev, lcu);
 492         if (rc)
 493                 return rc;
 494
 495         spin_lock_irqsave(&lcu->lock, flags);
 496         lcu->pav = NO_PAV;
 497         for (i = 0; i < MAX_DEVICES_PER_LCU; ++i) {
 498                 switch (lcu->uac->unit[i].ua_type) {
 499                 case UA_BASE_PAV_ALIAS:
 500                         lcu->pav = BASE_PAV;
 501                         break;
 502                 case UA_HYPER_PAV_ALIAS:
 503                         lcu->pav = HYPER_PAV;
 504                         break;
 505                 }
 506                 if (lcu->pav != NO_PAV)
 507                         break;
 508         }
 509
 510         list_for_each_entry_safe(device, tempdev, &lcu->active_devices,
 511                                  alias_list) {
 512                 _add_device_to_lcu(lcu, device, refdev);
 513         }
 514         spin_unlock_irqrestore(&lcu->lock, flags);
 515         return 0;
 516 }
 517
 518 static void lcu_update_work(struct work_struct *work)
 519 {
 520         struct alias_lcu *lcu;
 521         struct read_uac_work_data *ruac_data;
 522         struct dasd_device *device;
 523         unsigned long flags;
 524         int rc;
 525
 526         ruac_data = container_of(work, struct read_uac_work_data, dwork.work);
 527         lcu = container_of(ruac_data, struct alias_lcu, ruac_data);
 528         device = ruac_data->device;
 529         rc = _lcu_update(device, lcu);
 530         /*
 531          * Need to check flags again, as there could have been another
 532          * prepare_update or a new device a new device while we were still
 533          * processing the data
 534          */
 535         spin_lock_irqsave(&lcu->lock, flags);
 536         if ((rc && (rc != -EOPNOTSUPP)) || (lcu->flags & NEED_UAC_UPDATE)) {
 537                 DBF_DEV_EVENT(DBF_WARNING, device, "could not update"
 538                             " alias data in lcu (rc = %d), retry later", rc);
 539                 if (!schedule_delayed_work(&lcu->ruac_data.dwork, 30*HZ))
 540                         dasd_put_device(device);
 541         } else {
 542                 dasd_put_device(device);
 543                 lcu->ruac_data.device = NULL;
 544                 lcu->flags &= ~UPDATE_PENDING;
 545         }
 546         spin_unlock_irqrestore(&lcu->lock, flags);
 547 }
 548
 549 static int _schedule_lcu_update(struct alias_lcu *lcu,
 550                                 struct dasd_device *device)
 551 {
 552         struct dasd_device *usedev = NULL;
 553         struct alias_pav_group *group;
 554
 555         lcu->flags |= NEED_UAC_UPDATE;
 556         if (lcu->ruac_data.device) {
 557                 /* already scheduled or running */
 558                 return 0;
 559         }
 560         if (device && !list_empty(&device->alias_list))
 561                 usedev = device;
 562
 563         if (!usedev && !list_empty(&lcu->grouplist)) {
 564                 group = list_first_entry(&lcu->grouplist,
 565                                          struct alias_pav_group, group);
 566                 if (!list_empty(&group->baselist))
 567                         usedev = list_first_entry(&group->baselist,
 568                                                   struct dasd_device,
 569                                                   alias_list);
 570                 else if (!list_empty(&group->aliaslist))
 571                         usedev = list_first_entry(&group->aliaslist,
 572                                                   struct dasd_device,
 573                                                   alias_list);
 574         }
 575         if (!usedev && !list_empty(&lcu->active_devices)) {
 576                 usedev = list_first_entry(&lcu->active_devices,
 577                                           struct dasd_device, alias_list);
 578         }
 579         /*
 580          * if we haven't found a proper device yet, give up for now, the next
 581          * device that will be set active will trigger an lcu update
 582          */
 583         if (!usedev)
 584                 return -EINVAL;
 585         dasd_get_device(usedev);
 586         lcu->ruac_data.device = usedev;
 587         if (!schedule_delayed_work(&lcu->ruac_data.dwork, 0))
 588                 dasd_put_device(usedev);
 589         return 0;
 590 }
 591
 592 int dasd_alias_add_device(struct dasd_device *device)
 593 {
 594         struct dasd_eckd_private *private = device->private;
 595         struct alias_lcu *lcu;
 596         unsigned long flags;
 597         int rc;
 598
 599         lcu = private->lcu;
 600         rc = 0;
 601         spin_lock_irqsave(&lcu->lock, flags);
 602         if (!(lcu->flags & UPDATE_PENDING)) {
 603                 rc = _add_device_to_lcu(lcu, device, device);
 604                 if (rc)
 605                         lcu->flags |= UPDATE_PENDING;
 606         }
 607         if (lcu->flags & UPDATE_PENDING) {
 608                 list_move(&device->alias_list, &lcu->active_devices);
 609                 _schedule_lcu_update(lcu, device);
 610         }
 611         spin_unlock_irqrestore(&lcu->lock, flags);
 612         return rc;
 613 }
 614
 615 int dasd_alias_update_add_device(struct dasd_device *device)
 616 {
 617         struct dasd_eckd_private *private = device->private;
 618
 619         private->lcu->flags |= UPDATE_PENDING;
 620         return dasd_alias_add_device(device);
 621 }
 622
 623 int dasd_alias_remove_device(struct dasd_device *device)
 624 {
 625         struct dasd_eckd_private *private = device->private;
 626         struct alias_lcu *lcu = private->lcu;
 627         unsigned long flags;
 628
 629         /* nothing to do if already removed */
 630         if (!lcu)
 631                 return 0;
 632         spin_lock_irqsave(&lcu->lock, flags);
 633         _remove_device_from_lcu(lcu, device);
 634         spin_unlock_irqrestore(&lcu->lock, flags);
 635         return 0;
 636 }
 637
 638 struct dasd_device *dasd_alias_get_start_dev(struct dasd_device *base_device)
 639 {
 640         struct dasd_eckd_private *alias_priv, *private = base_device->private;
 641         struct alias_pav_group *group = private->pavgroup;
 642         struct alias_lcu *lcu = private->lcu;
 643         struct dasd_device *alias_device;
 644         unsigned long flags;
 645
 646         if (!group || !lcu)
 647                 return NULL;
 648         if (lcu->pav == NO_PAV ||
 649             lcu->flags & (NEED_UAC_UPDATE | UPDATE_PENDING))
 650                 return NULL;
 651         if (unlikely(!(private->features.feature[8] & 0x01))) {
 652                 /*
 653                  * PAV enabled but prefix not, very unlikely
 654                  * seems to be a lost pathgroup
 655                  * use base device to do IO
 656                  */
 657                 DBF_DEV_EVENT(DBF_ERR, base_device, "%s",
 658                               "Prefix not enabled with PAV enabled\n");
 659                 return NULL;
 660         }
 661
 662         spin_lock_irqsave(&lcu->lock, flags);
 663         alias_device = group->next;
 664         if (!alias_device) {
 665                 if (list_empty(&group->aliaslist)) {
 666                         spin_unlock_irqrestore(&lcu->lock, flags);
 667                         return NULL;
 668                 } else {
 669                         alias_device = list_first_entry(&group->aliaslist,
 670                                                         struct dasd_device,
 671                                                         alias_list);
 672                 }
 673         }
 674         if (list_is_last(&alias_device->alias_list, &group->aliaslist))
 675                 group->next = list_first_entry(&group->aliaslist,
 676                                                struct dasd_device, alias_list);
 677         else
 678                 group->next = list_first_entry(&alias_device->alias_list,
 679                                                struct dasd_device, alias_list);
 680         spin_unlock_irqrestore(&lcu->lock, flags);
 681         alias_priv = alias_device->private;
 682         if ((alias_priv->count < private->count) && !alias_device->stopped &&
 683             !test_bit(DASD_FLAG_OFFLINE, &alias_device->flags))
 684                 return alias_device;
 685         else
 686                 return NULL;
 687 }
 688
 689 /*
 690  * Summary unit check handling depends on the way alias devices
 691  * are handled so it is done here rather then in dasd_eckd.c
 692  */
 693 static int reset_summary_unit_check(struct alias_lcu *lcu,
 694                                     struct dasd_device *device,
 695                                     char reason)
 696 {
 697         struct dasd_ccw_req *cqr;
 698         int rc = 0;
 699         struct ccw1 *ccw;
 700
 701         cqr = lcu->rsu_cqr;
 702         strncpy((char *) &cqr->magic, "ECKD", 4);
 703         ASCEBC((char *) &cqr->magic, 4);
 704         ccw = cqr->cpaddr;
 705         ccw->cmd_code = DASD_ECKD_CCW_RSCK;
 706         ccw->flags = CCW_FLAG_SLI;
 707         ccw->count = 16;
 708         ccw->cda = (__u32)(addr_t) cqr->data;
 709         ((char *)cqr->data)[0] = reason;
 710
 711         clear_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
 712         cqr->retries = 255;     /* set retry counter to enable basic ERP */
 713         cqr->startdev = device;
 714         cqr->memdev = device;
 715         cqr->block = NULL;
 716         cqr->expires = 5 * HZ;
 717         cqr->buildclk = get_tod_clock();
 718         cqr->status = DASD_CQR_FILLED;
 719
 720         rc = dasd_sleep_on_immediatly(cqr);
 721         return rc;
 722 }
 723
 724 static void _restart_all_base_devices_on_lcu(struct alias_lcu *lcu)
 725 {
 726         struct alias_pav_group *pavgroup;
 727         struct dasd_device *device;
 728         struct dasd_eckd_private *private;
 729
 730         /* active and inactive list can contain alias as well as base devices */
 731         list_for_each_entry(device, &lcu->active_devices, alias_list) {
 732                 private = device->private;
 733                 if (private->uid.type != UA_BASE_DEVICE)
 734                         continue;
 735                 dasd_schedule_block_bh(device->block);
 736                 dasd_schedule_device_bh(device);
 737         }
 738         list_for_each_entry(device, &lcu->inactive_devices, alias_list) {
 739                 private = device->private;
 740                 if (private->uid.type != UA_BASE_DEVICE)
 741                         continue;
 742                 dasd_schedule_block_bh(device->block);
 743                 dasd_schedule_device_bh(device);
 744         }
 745         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 746                 list_for_each_entry(device, &pavgroup->baselist, alias_list) {
 747                         dasd_schedule_block_bh(device->block);
 748                         dasd_schedule_device_bh(device);
 749                 }
 750         }
 751 }
 752
 753 static void flush_all_alias_devices_on_lcu(struct alias_lcu *lcu)
 754 {
 755         struct alias_pav_group *pavgroup;
 756         struct dasd_device *device, *temp;
 757         struct dasd_eckd_private *private;
 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                 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 };