git.itanic.dy.fi Git - linux-stable/blob - 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         /* 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         list_del_init(&device->alias_list);
 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         /*
 387          * intrc values ENODEV, ENOLINK and EPERM
 388          * will be optained from sleep_on to indicate that no
 389          * IO operation can be started
 390          */
 391         if (cqr->intrc == -ENODEV)
 392                 return 1;
 393
 394         if (cqr->intrc == -ENOLINK)
 395                 return 1;
 396
 397         if (cqr->intrc == -EPERM)
 398                 return 1;
 399
 400         sense = dasd_get_sense(&cqr->irb);
 401         if (!sense)
 402                 return 0;
 403
 404         reason = sense[0];
 405         msg_format = (sense[7] & 0xF0);
 406         msg_no = (sense[7] & 0x0F);
 407
 408         /* command reject, Format 0 MSG 4 - invalid parameter */
 409         if ((reason == 0x80) && (msg_format == 0x00) && (msg_no == 0x04))
 410                 return 1;
 411
 412         return 0;
 413 }
 414
 415 static int read_unit_address_configuration(struct dasd_device *device,
 416                                            struct alias_lcu *lcu)
 417 {
 418         struct dasd_psf_prssd_data *prssdp;
 419         struct dasd_ccw_req *cqr;
 420         struct ccw1 *ccw;
 421         int rc;
 422         unsigned long flags;
 423
 424         cqr = dasd_smalloc_request(DASD_ECKD_MAGIC, 1 /* PSF */ + 1 /* RSSD */,
 425                                    (sizeof(struct dasd_psf_prssd_data)),
 426                                    device, NULL);
 427         if (IS_ERR(cqr))
 428                 return PTR_ERR(cqr);
 429         cqr->startdev = device;
 430         cqr->memdev = device;
 431         clear_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
 432         cqr->retries = 10;
 433         cqr->expires = 20 * HZ;
 434
 435         /* Prepare for Read Subsystem Data */
 436         prssdp = (struct dasd_psf_prssd_data *) cqr->data;
 437         memset(prssdp, 0, sizeof(struct dasd_psf_prssd_data));
 438         prssdp->order = PSF_ORDER_PRSSD;
 439         prssdp->suborder = 0x0e;        /* Read unit address configuration */
 440         /* all other bytes of prssdp must be zero */
 441
 442         ccw = cqr->cpaddr;
 443         ccw->cmd_code = DASD_ECKD_CCW_PSF;
 444         ccw->count = sizeof(struct dasd_psf_prssd_data);
 445         ccw->flags |= CCW_FLAG_CC;
 446         ccw->cda = (__u32)(addr_t) prssdp;
 447
 448         /* Read Subsystem Data - feature codes */
 449         memset(lcu->uac, 0, sizeof(*(lcu->uac)));
 450
 451         ccw++;
 452         ccw->cmd_code = DASD_ECKD_CCW_RSSD;
 453         ccw->count = sizeof(*(lcu->uac));
 454         ccw->cda = (__u32)(addr_t) lcu->uac;
 455
 456         cqr->buildclk = get_tod_clock();
 457         cqr->status = DASD_CQR_FILLED;
 458
 459         /* need to unset flag here to detect race with summary unit check */
 460         spin_lock_irqsave(&lcu->lock, flags);
 461         lcu->flags &= ~NEED_UAC_UPDATE;
 462         spin_unlock_irqrestore(&lcu->lock, flags);
 463
 464         rc = dasd_sleep_on(cqr);
 465         if (!rc)
 466                 goto out;
 467
 468         if (suborder_not_supported(cqr)) {
 469                 /* suborder not supported or device unusable for IO */
 470                 rc = -EOPNOTSUPP;
 471         } else {
 472                 /* IO failed but should be retried */
 473                 spin_lock_irqsave(&lcu->lock, flags);
 474                 lcu->flags |= NEED_UAC_UPDATE;
 475                 spin_unlock_irqrestore(&lcu->lock, flags);
 476         }
 477 out:
 478         dasd_sfree_request(cqr, cqr->memdev);
 479         return rc;
 480 }
 481
 482 static int _lcu_update(struct dasd_device *refdev, struct alias_lcu *lcu)
 483 {
 484         unsigned long flags;
 485         struct alias_pav_group *pavgroup, *tempgroup;
 486         struct dasd_device *device, *tempdev;
 487         int i, rc;
 488         struct dasd_eckd_private *private;
 489
 490         spin_lock_irqsave(&lcu->lock, flags);
 491         list_for_each_entry_safe(pavgroup, tempgroup, &lcu->grouplist, group) {
 492                 list_for_each_entry_safe(device, tempdev, &pavgroup->baselist,
 493                                          alias_list) {
 494                         list_move(&device->alias_list, &lcu->active_devices);
 495                         private = device->private;
 496                         private->pavgroup = NULL;
 497                 }
 498                 list_for_each_entry_safe(device, tempdev, &pavgroup->aliaslist,
 499                                          alias_list) {
 500                         list_move(&device->alias_list, &lcu->active_devices);
 501                         private = device->private;
 502                         private->pavgroup = NULL;
 503                 }
 504                 list_del(&pavgroup->group);
 505                 kfree(pavgroup);
 506         }
 507         spin_unlock_irqrestore(&lcu->lock, flags);
 508
 509         rc = read_unit_address_configuration(refdev, lcu);
 510         if (rc)
 511                 return rc;
 512
 513         spin_lock_irqsave(&lcu->lock, flags);
 514         /*
 515          * there is another update needed skip the remaining handling
 516          * the data might already be outdated
 517          * but especially do not add the device to an LCU with pending
 518          * update
 519          */
 520         if (lcu->flags & NEED_UAC_UPDATE)
 521                 goto out;
 522         lcu->pav = NO_PAV;
 523         for (i = 0; i < MAX_DEVICES_PER_LCU; ++i) {
 524                 switch (lcu->uac->unit[i].ua_type) {
 525                 case UA_BASE_PAV_ALIAS:
 526                         lcu->pav = BASE_PAV;
 527                         break;
 528                 case UA_HYPER_PAV_ALIAS:
 529                         lcu->pav = HYPER_PAV;
 530                         break;
 531                 }
 532                 if (lcu->pav != NO_PAV)
 533                         break;
 534         }
 535
 536         list_for_each_entry_safe(device, tempdev, &lcu->active_devices,
 537                                  alias_list) {
 538                 _add_device_to_lcu(lcu, device, refdev);
 539         }
 540 out:
 541         spin_unlock_irqrestore(&lcu->lock, flags);
 542         return 0;
 543 }
 544
 545 static void lcu_update_work(struct work_struct *work)
 546 {
 547         struct alias_lcu *lcu;
 548         struct read_uac_work_data *ruac_data;
 549         struct dasd_device *device;
 550         unsigned long flags;
 551         int rc;
 552
 553         ruac_data = container_of(work, struct read_uac_work_data, dwork.work);
 554         lcu = container_of(ruac_data, struct alias_lcu, ruac_data);
 555         device = ruac_data->device;
 556         rc = _lcu_update(device, lcu);
 557         /*
 558          * Need to check flags again, as there could have been another
 559          * prepare_update or a new device a new device while we were still
 560          * processing the data
 561          */
 562         spin_lock_irqsave(&lcu->lock, flags);
 563         if ((rc && (rc != -EOPNOTSUPP)) || (lcu->flags & NEED_UAC_UPDATE)) {
 564                 DBF_DEV_EVENT(DBF_WARNING, device, "could not update"
 565                             " alias data in lcu (rc = %d), retry later", rc);
 566                 if (!schedule_delayed_work(&lcu->ruac_data.dwork, 30*HZ))
 567                         dasd_put_device(device);
 568         } else {
 569                 dasd_put_device(device);
 570                 lcu->ruac_data.device = NULL;
 571                 lcu->flags &= ~UPDATE_PENDING;
 572         }
 573         spin_unlock_irqrestore(&lcu->lock, flags);
 574 }
 575
 576 static int _schedule_lcu_update(struct alias_lcu *lcu,
 577                                 struct dasd_device *device)
 578 {
 579         struct dasd_device *usedev = NULL;
 580         struct alias_pav_group *group;
 581
 582         lcu->flags |= NEED_UAC_UPDATE;
 583         if (lcu->ruac_data.device) {
 584                 /* already scheduled or running */
 585                 return 0;
 586         }
 587         if (device && !list_empty(&device->alias_list))
 588                 usedev = device;
 589
 590         if (!usedev && !list_empty(&lcu->grouplist)) {
 591                 group = list_first_entry(&lcu->grouplist,
 592                                          struct alias_pav_group, group);
 593                 if (!list_empty(&group->baselist))
 594                         usedev = list_first_entry(&group->baselist,
 595                                                   struct dasd_device,
 596                                                   alias_list);
 597                 else if (!list_empty(&group->aliaslist))
 598                         usedev = list_first_entry(&group->aliaslist,
 599                                                   struct dasd_device,
 600                                                   alias_list);
 601         }
 602         if (!usedev && !list_empty(&lcu->active_devices)) {
 603                 usedev = list_first_entry(&lcu->active_devices,
 604                                           struct dasd_device, alias_list);
 605         }
 606         /*
 607          * if we haven't found a proper device yet, give up for now, the next
 608          * device that will be set active will trigger an lcu update
 609          */
 610         if (!usedev)
 611                 return -EINVAL;
 612         dasd_get_device(usedev);
 613         lcu->ruac_data.device = usedev;
 614         if (!schedule_delayed_work(&lcu->ruac_data.dwork, 0))
 615                 dasd_put_device(usedev);
 616         return 0;
 617 }
 618
 619 int dasd_alias_add_device(struct dasd_device *device)
 620 {
 621         struct dasd_eckd_private *private = device->private;
 622         __u8 uaddr = private->uid.real_unit_addr;
 623         struct alias_lcu *lcu = private->lcu;
 624         unsigned long flags;
 625         int rc;
 626
 627         rc = 0;
 628         spin_lock_irqsave(&lcu->lock, flags);
 629         /*
 630          * Check if device and lcu type differ. If so, the uac data may be
 631          * outdated and needs to be updated.
 632          */
 633         if (private->uid.type !=  lcu->uac->unit[uaddr].ua_type) {
 634                 lcu->flags |= UPDATE_PENDING;
 635                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
 636                               "uid type mismatch - trigger rescan");
 637         }
 638         if (!(lcu->flags & UPDATE_PENDING)) {
 639                 rc = _add_device_to_lcu(lcu, device, device);
 640                 if (rc)
 641                         lcu->flags |= UPDATE_PENDING;
 642         }
 643         if (lcu->flags & UPDATE_PENDING) {
 644                 list_move(&device->alias_list, &lcu->active_devices);
 645                 private->pavgroup = NULL;
 646                 _schedule_lcu_update(lcu, device);
 647         }
 648         spin_unlock_irqrestore(&lcu->lock, flags);
 649         return rc;
 650 }
 651
 652 int dasd_alias_update_add_device(struct dasd_device *device)
 653 {
 654         struct dasd_eckd_private *private = device->private;
 655
 656         private->lcu->flags |= UPDATE_PENDING;
 657         return dasd_alias_add_device(device);
 658 }
 659
 660 int dasd_alias_remove_device(struct dasd_device *device)
 661 {
 662         struct dasd_eckd_private *private = device->private;
 663         struct alias_lcu *lcu = private->lcu;
 664         unsigned long flags;
 665
 666         /* nothing to do if already removed */
 667         if (!lcu)
 668                 return 0;
 669         spin_lock_irqsave(&lcu->lock, flags);
 670         _remove_device_from_lcu(lcu, device);
 671         spin_unlock_irqrestore(&lcu->lock, flags);
 672         return 0;
 673 }
 674
 675 struct dasd_device *dasd_alias_get_start_dev(struct dasd_device *base_device)
 676 {
 677         struct dasd_eckd_private *alias_priv, *private = base_device->private;
 678         struct alias_lcu *lcu = private->lcu;
 679         struct dasd_device *alias_device;
 680         struct alias_pav_group *group;
 681         unsigned long flags;
 682
 683         if (!lcu)
 684                 return NULL;
 685         if (lcu->pav == NO_PAV ||
 686             lcu->flags & (NEED_UAC_UPDATE | UPDATE_PENDING))
 687                 return NULL;
 688         if (unlikely(!(private->features.feature[8] & 0x01))) {
 689                 /*
 690                  * PAV enabled but prefix not, very unlikely
 691                  * seems to be a lost pathgroup
 692                  * use base device to do IO
 693                  */
 694                 DBF_DEV_EVENT(DBF_ERR, base_device, "%s",
 695                               "Prefix not enabled with PAV enabled\n");
 696                 return NULL;
 697         }
 698
 699         spin_lock_irqsave(&lcu->lock, flags);
 700         group = private->pavgroup;
 701         if (!group) {
 702                 spin_unlock_irqrestore(&lcu->lock, flags);
 703                 return NULL;
 704         }
 705         alias_device = group->next;
 706         if (!alias_device) {
 707                 if (list_empty(&group->aliaslist)) {
 708                         spin_unlock_irqrestore(&lcu->lock, flags);
 709                         return NULL;
 710                 } else {
 711                         alias_device = list_first_entry(&group->aliaslist,
 712                                                         struct dasd_device,
 713                                                         alias_list);
 714                 }
 715         }
 716         if (list_is_last(&alias_device->alias_list, &group->aliaslist))
 717                 group->next = list_first_entry(&group->aliaslist,
 718                                                struct dasd_device, alias_list);
 719         else
 720                 group->next = list_first_entry(&alias_device->alias_list,
 721                                                struct dasd_device, alias_list);
 722         spin_unlock_irqrestore(&lcu->lock, flags);
 723         alias_priv = alias_device->private;
 724         if ((alias_priv->count < private->count) && !alias_device->stopped &&
 725             !test_bit(DASD_FLAG_OFFLINE, &alias_device->flags))
 726                 return alias_device;
 727         else
 728                 return NULL;
 729 }
 730
 731 /*
 732  * Summary unit check handling depends on the way alias devices
 733  * are handled so it is done here rather then in dasd_eckd.c
 734  */
 735 static int reset_summary_unit_check(struct alias_lcu *lcu,
 736                                     struct dasd_device *device,
 737                                     char reason)
 738 {
 739         struct dasd_ccw_req *cqr;
 740         int rc = 0;
 741         struct ccw1 *ccw;
 742
 743         cqr = lcu->rsu_cqr;
 744         memcpy((char *) &cqr->magic, "ECKD", 4);
 745         ASCEBC((char *) &cqr->magic, 4);
 746         ccw = cqr->cpaddr;
 747         ccw->cmd_code = DASD_ECKD_CCW_RSCK;
 748         ccw->flags = CCW_FLAG_SLI;
 749         ccw->count = 16;
 750         ccw->cda = (__u32)(addr_t) cqr->data;
 751         ((char *)cqr->data)[0] = reason;
 752
 753         clear_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
 754         cqr->retries = 255;     /* set retry counter to enable basic ERP */
 755         cqr->startdev = device;
 756         cqr->memdev = device;
 757         cqr->block = NULL;
 758         cqr->expires = 5 * HZ;
 759         cqr->buildclk = get_tod_clock();
 760         cqr->status = DASD_CQR_FILLED;
 761
 762         rc = dasd_sleep_on_immediatly(cqr);
 763         return rc;
 764 }
 765
 766 static void _restart_all_base_devices_on_lcu(struct alias_lcu *lcu)
 767 {
 768         struct alias_pav_group *pavgroup;
 769         struct dasd_device *device;
 770         struct dasd_eckd_private *private;
 771
 772         /* active and inactive list can contain alias as well as base devices */
 773         list_for_each_entry(device, &lcu->active_devices, alias_list) {
 774                 private = device->private;
 775                 if (private->uid.type != UA_BASE_DEVICE)
 776                         continue;
 777                 dasd_schedule_block_bh(device->block);
 778                 dasd_schedule_device_bh(device);
 779         }
 780         list_for_each_entry(device, &lcu->inactive_devices, alias_list) {
 781                 private = device->private;
 782                 if (private->uid.type != UA_BASE_DEVICE)
 783                         continue;
 784                 dasd_schedule_block_bh(device->block);
 785                 dasd_schedule_device_bh(device);
 786         }
 787         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 788                 list_for_each_entry(device, &pavgroup->baselist, alias_list) {
 789                         dasd_schedule_block_bh(device->block);
 790                         dasd_schedule_device_bh(device);
 791                 }
 792         }
 793 }
 794
 795 static void flush_all_alias_devices_on_lcu(struct alias_lcu *lcu)
 796 {
 797         struct alias_pav_group *pavgroup;
 798         struct dasd_device *device, *temp;
 799         struct dasd_eckd_private *private;
 800         unsigned long flags;
 801         LIST_HEAD(active);
 802
 803         /*
 804          * Problem here ist that dasd_flush_device_queue may wait
 805          * for termination of a request to complete. We can't keep
 806          * the lcu lock during that time, so we must assume that
 807          * the lists may have changed.
 808          * Idea: first gather all active alias devices in a separate list,
 809          * then flush the first element of this list unlocked, and afterwards
 810          * check if it is still on the list before moving it to the
 811          * active_devices list.
 812          */
 813
 814         spin_lock_irqsave(&lcu->lock, flags);
 815         list_for_each_entry_safe(device, temp, &lcu->active_devices,
 816                                  alias_list) {
 817                 private = device->private;
 818                 if (private->uid.type == UA_BASE_DEVICE)
 819                         continue;
 820                 list_move(&device->alias_list, &active);
 821         }
 822
 823         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 824                 list_splice_init(&pavgroup->aliaslist, &active);
 825         }
 826         while (!list_empty(&active)) {
 827                 device = list_first_entry(&active, struct dasd_device,
 828                                           alias_list);
 829                 spin_unlock_irqrestore(&lcu->lock, flags);
 830                 dasd_flush_device_queue(device);
 831                 spin_lock_irqsave(&lcu->lock, flags);
 832                 /*
 833                  * only move device around if it wasn't moved away while we
 834                  * were waiting for the flush
 835                  */
 836                 if (device == list_first_entry(&active,
 837                                                struct dasd_device, alias_list)) {
 838                         list_move(&device->alias_list, &lcu->active_devices);
 839                         private = device->private;
 840                         private->pavgroup = NULL;
 841                 }
 842         }
 843         spin_unlock_irqrestore(&lcu->lock, flags);
 844 }
 845
 846 static void _stop_all_devices_on_lcu(struct alias_lcu *lcu)
 847 {
 848         struct alias_pav_group *pavgroup;
 849         struct dasd_device *device;
 850
 851         list_for_each_entry(device, &lcu->active_devices, alias_list) {
 852                 spin_lock(get_ccwdev_lock(device->cdev));
 853                 dasd_device_set_stop_bits(device, DASD_STOPPED_SU);
 854                 spin_unlock(get_ccwdev_lock(device->cdev));
 855         }
 856         list_for_each_entry(device, &lcu->inactive_devices, alias_list) {
 857                 spin_lock(get_ccwdev_lock(device->cdev));
 858                 dasd_device_set_stop_bits(device, DASD_STOPPED_SU);
 859                 spin_unlock(get_ccwdev_lock(device->cdev));
 860         }
 861         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 862                 list_for_each_entry(device, &pavgroup->baselist, alias_list) {
 863                         spin_lock(get_ccwdev_lock(device->cdev));
 864                         dasd_device_set_stop_bits(device, DASD_STOPPED_SU);
 865                         spin_unlock(get_ccwdev_lock(device->cdev));
 866                 }
 867                 list_for_each_entry(device, &pavgroup->aliaslist, alias_list) {
 868                         spin_lock(get_ccwdev_lock(device->cdev));
 869                         dasd_device_set_stop_bits(device, DASD_STOPPED_SU);
 870                         spin_unlock(get_ccwdev_lock(device->cdev));
 871                 }
 872         }
 873 }
 874
 875 static void _unstop_all_devices_on_lcu(struct alias_lcu *lcu)
 876 {
 877         struct alias_pav_group *pavgroup;
 878         struct dasd_device *device;
 879
 880         list_for_each_entry(device, &lcu->active_devices, alias_list) {
 881                 spin_lock(get_ccwdev_lock(device->cdev));
 882                 dasd_device_remove_stop_bits(device, DASD_STOPPED_SU);
 883                 spin_unlock(get_ccwdev_lock(device->cdev));
 884         }
 885         list_for_each_entry(device, &lcu->inactive_devices, alias_list) {
 886                 spin_lock(get_ccwdev_lock(device->cdev));
 887                 dasd_device_remove_stop_bits(device, DASD_STOPPED_SU);
 888                 spin_unlock(get_ccwdev_lock(device->cdev));
 889         }
 890         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 891                 list_for_each_entry(device, &pavgroup->baselist, alias_list) {
 892                         spin_lock(get_ccwdev_lock(device->cdev));
 893                         dasd_device_remove_stop_bits(device, DASD_STOPPED_SU);
 894                         spin_unlock(get_ccwdev_lock(device->cdev));
 895                 }
 896                 list_for_each_entry(device, &pavgroup->aliaslist, alias_list) {
 897                         spin_lock(get_ccwdev_lock(device->cdev));
 898                         dasd_device_remove_stop_bits(device, DASD_STOPPED_SU);
 899                         spin_unlock(get_ccwdev_lock(device->cdev));
 900                 }
 901         }
 902 }
 903
 904 static void summary_unit_check_handling_work(struct work_struct *work)
 905 {
 906         struct alias_lcu *lcu;
 907         struct summary_unit_check_work_data *suc_data;
 908         unsigned long flags;
 909         struct dasd_device *device;
 910
 911         suc_data = container_of(work, struct summary_unit_check_work_data,
 912                                 worker);
 913         lcu = container_of(suc_data, struct alias_lcu, suc_data);
 914         device = suc_data->device;
 915
 916         /* 1. flush alias devices */
 917         flush_all_alias_devices_on_lcu(lcu);
 918
 919         /* 2. reset summary unit check */
 920         spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 921         dasd_device_remove_stop_bits(device,
 922                                      (DASD_STOPPED_SU | DASD_STOPPED_PENDING));
 923         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 924         reset_summary_unit_check(lcu, device, suc_data->reason);
 925
 926         spin_lock_irqsave(&lcu->lock, flags);
 927         _unstop_all_devices_on_lcu(lcu);
 928         _restart_all_base_devices_on_lcu(lcu);
 929         /* 3. read new alias configuration */
 930         _schedule_lcu_update(lcu, device);
 931         lcu->suc_data.device = NULL;
 932         dasd_put_device(device);
 933         spin_unlock_irqrestore(&lcu->lock, flags);
 934 }
 935
 936 void dasd_alias_handle_summary_unit_check(struct work_struct *work)
 937 {
 938         struct dasd_device *device = container_of(work, struct dasd_device,
 939                                                   suc_work);
 940         struct dasd_eckd_private *private = device->private;
 941         struct alias_lcu *lcu;
 942         unsigned long flags;
 943
 944         lcu = private->lcu;
 945         if (!lcu) {
 946                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
 947                             "device not ready to handle summary"
 948                             " unit check (no lcu structure)");
 949                 goto out;
 950         }
 951         spin_lock_irqsave(&lcu->lock, flags);
 952         /* If this device is about to be removed just return and wait for
 953          * the next interrupt on a different device
 954          */
 955         if (list_empty(&device->alias_list)) {
 956                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
 957                             "device is in offline processing,"
 958                             " don't do summary unit check handling");
 959                 goto out_unlock;
 960         }
 961         if (lcu->suc_data.device) {
 962                 /* already scheduled or running */
 963                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
 964                             "previous instance of summary unit check worker"
 965                             " still pending");
 966                 goto out_unlock;
 967         }
 968         _stop_all_devices_on_lcu(lcu);
 969         /* prepare for lcu_update */
 970         lcu->flags |= NEED_UAC_UPDATE | UPDATE_PENDING;
 971         lcu->suc_data.reason = private->suc_reason;
 972         lcu->suc_data.device = device;
 973         dasd_get_device(device);
 974         if (!schedule_work(&lcu->suc_data.worker))
 975                 dasd_put_device(device);
 976 out_unlock:
 977         spin_unlock_irqrestore(&lcu->lock, flags);
 978 out:
 979         clear_bit(DASD_FLAG_SUC, &device->flags);
 980         dasd_put_device(device);
 981 };