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;
 189         unsigned long flags;
 190         struct alias_server *server, *newserver;
 191         struct alias_lcu *lcu, *newlcu;
 192         struct dasd_uid uid;
 193
 194         private = (struct dasd_eckd_private *) device->private;
 195
 196         device->discipline->get_uid(device, &uid);
 197         spin_lock_irqsave(&aliastree.lock, flags);
 198         server = _find_server(&uid);
 199         if (!server) {
 200                 spin_unlock_irqrestore(&aliastree.lock, flags);
 201                 newserver = _allocate_server(&uid);
 202                 if (IS_ERR(newserver))
 203                         return PTR_ERR(newserver);
 204                 spin_lock_irqsave(&aliastree.lock, flags);
 205                 server = _find_server(&uid);
 206                 if (!server) {
 207                         list_add(&newserver->server, &aliastree.serverlist);
 208                         server = newserver;
 209                 } else {
 210                         /* someone was faster */
 211                         _free_server(newserver);
 212                 }
 213         }
 214
 215         lcu = _find_lcu(server, &uid);
 216         if (!lcu) {
 217                 spin_unlock_irqrestore(&aliastree.lock, flags);
 218                 newlcu = _allocate_lcu(&uid);
 219                 if (IS_ERR(newlcu))
 220                         return PTR_ERR(newlcu);
 221                 spin_lock_irqsave(&aliastree.lock, flags);
 222                 lcu = _find_lcu(server, &uid);
 223                 if (!lcu) {
 224                         list_add(&newlcu->lcu, &server->lculist);
 225                         lcu = newlcu;
 226                 } else {
 227                         /* someone was faster */
 228                         _free_lcu(newlcu);
 229                 }
 230         }
 231         spin_lock(&lcu->lock);
 232         list_add(&device->alias_list, &lcu->inactive_devices);
 233         private->lcu = lcu;
 234         spin_unlock(&lcu->lock);
 235         spin_unlock_irqrestore(&aliastree.lock, flags);
 236
 237         return 0;
 238 }
 239
 240 /*
 241  * This function removes a device from the scope of alias management.
 242  * The complicated part is to make sure that it is not in use by
 243  * any of the workers. If necessary cancel the work.
 244  */
 245 void dasd_alias_disconnect_device_from_lcu(struct dasd_device *device)
 246 {
 247         struct dasd_eckd_private *private;
 248         unsigned long flags;
 249         struct alias_lcu *lcu;
 250         struct alias_server *server;
 251         int was_pending;
 252         struct dasd_uid uid;
 253
 254         private = (struct dasd_eckd_private *) device->private;
 255         lcu = private->lcu;
 256         /* nothing to do if already disconnected */
 257         if (!lcu)
 258                 return;
 259         device->discipline->get_uid(device, &uid);
 260         spin_lock_irqsave(&lcu->lock, flags);
 261         /* make sure that the workers don't use this device */
 262         if (device == lcu->suc_data.device) {
 263                 spin_unlock_irqrestore(&lcu->lock, flags);
 264                 cancel_work_sync(&lcu->suc_data.worker);
 265                 spin_lock_irqsave(&lcu->lock, flags);
 266                 if (device == lcu->suc_data.device) {
 267                         dasd_put_device(device);
 268                         lcu->suc_data.device = NULL;
 269                 }
 270         }
 271         was_pending = 0;
 272         if (device == lcu->ruac_data.device) {
 273                 spin_unlock_irqrestore(&lcu->lock, flags);
 274                 was_pending = 1;
 275                 cancel_delayed_work_sync(&lcu->ruac_data.dwork);
 276                 spin_lock_irqsave(&lcu->lock, flags);
 277                 if (device == lcu->ruac_data.device) {
 278                         dasd_put_device(device);
 279                         lcu->ruac_data.device = NULL;
 280                 }
 281         }
 282         private->lcu = NULL;
 283         spin_unlock_irqrestore(&lcu->lock, flags);
 284
 285         spin_lock_irqsave(&aliastree.lock, flags);
 286         spin_lock(&lcu->lock);
 287         list_del_init(&device->alias_list);
 288         if (list_empty(&lcu->grouplist) &&
 289             list_empty(&lcu->active_devices) &&
 290             list_empty(&lcu->inactive_devices)) {
 291                 list_del(&lcu->lcu);
 292                 spin_unlock(&lcu->lock);
 293                 _free_lcu(lcu);
 294                 lcu = NULL;
 295         } else {
 296                 if (was_pending)
 297                         _schedule_lcu_update(lcu, NULL);
 298                 spin_unlock(&lcu->lock);
 299         }
 300         server = _find_server(&uid);
 301         if (server && list_empty(&server->lculist)) {
 302                 list_del(&server->server);
 303                 _free_server(server);
 304         }
 305         spin_unlock_irqrestore(&aliastree.lock, flags);
 306 }
 307
 308 /*
 309  * This function assumes that the unit address configuration stored
 310  * in the lcu is up to date and will update the device uid before
 311  * adding it to a pav group.
 312  */
 313
 314 static int _add_device_to_lcu(struct alias_lcu *lcu,
 315                               struct dasd_device *device,
 316                               struct dasd_device *pos)
 317 {
 318
 319         struct dasd_eckd_private *private;
 320         struct alias_pav_group *group;
 321         struct dasd_uid uid;
 322         unsigned long flags;
 323
 324         private = (struct dasd_eckd_private *) device->private;
 325
 326         /* only lock if not already locked */
 327         if (device != pos)
 328                 spin_lock_irqsave_nested(get_ccwdev_lock(device->cdev), flags,
 329                                          CDEV_NESTED_SECOND);
 330         private->uid.type = lcu->uac->unit[private->uid.real_unit_addr].ua_type;
 331         private->uid.base_unit_addr =
 332                 lcu->uac->unit[private->uid.real_unit_addr].base_ua;
 333         uid = private->uid;
 334
 335         if (device != pos)
 336                 spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 337
 338         /* if we have no PAV anyway, we don't need to bother with PAV groups */
 339         if (lcu->pav == NO_PAV) {
 340                 list_move(&device->alias_list, &lcu->active_devices);
 341                 return 0;
 342         }
 343
 344         group = _find_group(lcu, &uid);
 345         if (!group) {
 346                 group = kzalloc(sizeof(*group), GFP_ATOMIC);
 347                 if (!group)
 348                         return -ENOMEM;
 349                 memcpy(group->uid.vendor, uid.vendor, sizeof(uid.vendor));
 350                 memcpy(group->uid.serial, uid.serial, sizeof(uid.serial));
 351                 group->uid.ssid = uid.ssid;
 352                 if (uid.type == UA_BASE_DEVICE)
 353                         group->uid.base_unit_addr = uid.real_unit_addr;
 354                 else
 355                         group->uid.base_unit_addr = uid.base_unit_addr;
 356                 memcpy(group->uid.vduit, uid.vduit, sizeof(uid.vduit));
 357                 INIT_LIST_HEAD(&group->group);
 358                 INIT_LIST_HEAD(&group->baselist);
 359                 INIT_LIST_HEAD(&group->aliaslist);
 360                 list_add(&group->group, &lcu->grouplist);
 361         }
 362         if (uid.type == UA_BASE_DEVICE)
 363                 list_move(&device->alias_list, &group->baselist);
 364         else
 365                 list_move(&device->alias_list, &group->aliaslist);
 366         private->pavgroup = group;
 367         return 0;
 368 };
 369
 370 static void _remove_device_from_lcu(struct alias_lcu *lcu,
 371                                     struct dasd_device *device)
 372 {
 373         struct dasd_eckd_private *private;
 374         struct alias_pav_group *group;
 375
 376         private = (struct dasd_eckd_private *) device->private;
 377         list_move(&device->alias_list, &lcu->inactive_devices);
 378         group = private->pavgroup;
 379         if (!group)
 380                 return;
 381         private->pavgroup = NULL;
 382         if (list_empty(&group->baselist) && list_empty(&group->aliaslist)) {
 383                 list_del(&group->group);
 384                 kfree(group);
 385                 return;
 386         }
 387         if (group->next == device)
 388                 group->next = NULL;
 389 };
 390
 391 static int
 392 suborder_not_supported(struct dasd_ccw_req *cqr)
 393 {
 394         char *sense;
 395         char reason;
 396         char msg_format;
 397         char msg_no;
 398
 399         /*
 400          * intrc values ENODEV, ENOLINK and EPERM
 401          * will be optained from sleep_on to indicate that no
 402          * IO operation can be started
 403          */
 404         if (cqr->intrc == -ENODEV)
 405                 return 1;
 406
 407         if (cqr->intrc == -ENOLINK)
 408                 return 1;
 409
 410         if (cqr->intrc == -EPERM)
 411                 return 1;
 412
 413         sense = dasd_get_sense(&cqr->irb);
 414         if (!sense)
 415                 return 0;
 416
 417         reason = sense[0];
 418         msg_format = (sense[7] & 0xF0);
 419         msg_no = (sense[7] & 0x0F);
 420
 421         /* command reject, Format 0 MSG 4 - invalid parameter */
 422         if ((reason == 0x80) && (msg_format == 0x00) && (msg_no == 0x04))
 423                 return 1;
 424
 425         return 0;
 426 }
 427
 428 static int read_unit_address_configuration(struct dasd_device *device,
 429                                            struct alias_lcu *lcu)
 430 {
 431         struct dasd_psf_prssd_data *prssdp;
 432         struct dasd_ccw_req *cqr;
 433         struct ccw1 *ccw;
 434         int rc;
 435         unsigned long flags;
 436
 437         cqr = dasd_kmalloc_request(DASD_ECKD_MAGIC, 1 /* PSF */ + 1 /* RSSD */,
 438                                    (sizeof(struct dasd_psf_prssd_data)),
 439                                    device);
 440         if (IS_ERR(cqr))
 441                 return PTR_ERR(cqr);
 442         cqr->startdev = device;
 443         cqr->memdev = device;
 444         clear_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
 445         cqr->retries = 10;
 446         cqr->expires = 20 * HZ;
 447
 448         /* Prepare for Read Subsystem Data */
 449         prssdp = (struct dasd_psf_prssd_data *) cqr->data;
 450         memset(prssdp, 0, sizeof(struct dasd_psf_prssd_data));
 451         prssdp->order = PSF_ORDER_PRSSD;
 452         prssdp->suborder = 0x0e;        /* Read unit address configuration */
 453         /* all other bytes of prssdp must be zero */
 454
 455         ccw = cqr->cpaddr;
 456         ccw->cmd_code = DASD_ECKD_CCW_PSF;
 457         ccw->count = sizeof(struct dasd_psf_prssd_data);
 458         ccw->flags |= CCW_FLAG_CC;
 459         ccw->cda = (__u32)(addr_t) prssdp;
 460
 461         /* Read Subsystem Data - feature codes */
 462         memset(lcu->uac, 0, sizeof(*(lcu->uac)));
 463
 464         ccw++;
 465         ccw->cmd_code = DASD_ECKD_CCW_RSSD;
 466         ccw->count = sizeof(*(lcu->uac));
 467         ccw->cda = (__u32)(addr_t) lcu->uac;
 468
 469         cqr->buildclk = get_tod_clock();
 470         cqr->status = DASD_CQR_FILLED;
 471
 472         /* need to unset flag here to detect race with summary unit check */
 473         spin_lock_irqsave(&lcu->lock, flags);
 474         lcu->flags &= ~NEED_UAC_UPDATE;
 475         spin_unlock_irqrestore(&lcu->lock, flags);
 476
 477         rc = dasd_sleep_on(cqr);
 478         if (!rc)
 479                 goto out;
 480
 481         if (suborder_not_supported(cqr)) {
 482                 /* suborder not supported or device unusable for IO */
 483                 rc = -EOPNOTSUPP;
 484         } else {
 485                 /* IO failed but should be retried */
 486                 spin_lock_irqsave(&lcu->lock, flags);
 487                 lcu->flags |= NEED_UAC_UPDATE;
 488                 spin_unlock_irqrestore(&lcu->lock, flags);
 489         }
 490 out:
 491         dasd_kfree_request(cqr, cqr->memdev);
 492         return rc;
 493 }
 494
 495 static int _lcu_update(struct dasd_device *refdev, struct alias_lcu *lcu)
 496 {
 497         unsigned long flags;
 498         struct alias_pav_group *pavgroup, *tempgroup;
 499         struct dasd_device *device, *tempdev;
 500         int i, rc;
 501         struct dasd_eckd_private *private;
 502
 503         spin_lock_irqsave(&lcu->lock, flags);
 504         list_for_each_entry_safe(pavgroup, tempgroup, &lcu->grouplist, group) {
 505                 list_for_each_entry_safe(device, tempdev, &pavgroup->baselist,
 506                                          alias_list) {
 507                         list_move(&device->alias_list, &lcu->active_devices);
 508                         private = (struct dasd_eckd_private *) device->private;
 509                         private->pavgroup = NULL;
 510                 }
 511                 list_for_each_entry_safe(device, tempdev, &pavgroup->aliaslist,
 512                                          alias_list) {
 513                         list_move(&device->alias_list, &lcu->active_devices);
 514                         private = (struct dasd_eckd_private *) device->private;
 515                         private->pavgroup = NULL;
 516                 }
 517                 list_del(&pavgroup->group);
 518                 kfree(pavgroup);
 519         }
 520         spin_unlock_irqrestore(&lcu->lock, flags);
 521
 522         rc = read_unit_address_configuration(refdev, lcu);
 523         if (rc)
 524                 return rc;
 525
 526         /* need to take cdev lock before lcu lock */
 527         spin_lock_irqsave_nested(get_ccwdev_lock(refdev->cdev), flags,
 528                                  CDEV_NESTED_FIRST);
 529         spin_lock(&lcu->lock);
 530         lcu->pav = NO_PAV;
 531         for (i = 0; i < MAX_DEVICES_PER_LCU; ++i) {
 532                 switch (lcu->uac->unit[i].ua_type) {
 533                 case UA_BASE_PAV_ALIAS:
 534                         lcu->pav = BASE_PAV;
 535                         break;
 536                 case UA_HYPER_PAV_ALIAS:
 537                         lcu->pav = HYPER_PAV;
 538                         break;
 539                 }
 540                 if (lcu->pav != NO_PAV)
 541                         break;
 542         }
 543
 544         list_for_each_entry_safe(device, tempdev, &lcu->active_devices,
 545                                  alias_list) {
 546                 _add_device_to_lcu(lcu, device, refdev);
 547         }
 548         spin_unlock(&lcu->lock);
 549         spin_unlock_irqrestore(get_ccwdev_lock(refdev->cdev), flags);
 550         return 0;
 551 }
 552
 553 static void lcu_update_work(struct work_struct *work)
 554 {
 555         struct alias_lcu *lcu;
 556         struct read_uac_work_data *ruac_data;
 557         struct dasd_device *device;
 558         unsigned long flags;
 559         int rc;
 560
 561         ruac_data = container_of(work, struct read_uac_work_data, dwork.work);
 562         lcu = container_of(ruac_data, struct alias_lcu, ruac_data);
 563         device = ruac_data->device;
 564         rc = _lcu_update(device, lcu);
 565         /*
 566          * Need to check flags again, as there could have been another
 567          * prepare_update or a new device a new device while we were still
 568          * processing the data
 569          */
 570         spin_lock_irqsave(&lcu->lock, flags);
 571         if ((rc && (rc != -EOPNOTSUPP)) || (lcu->flags & NEED_UAC_UPDATE)) {
 572                 DBF_DEV_EVENT(DBF_WARNING, device, "could not update"
 573                             " alias data in lcu (rc = %d), retry later", rc);
 574                 if (!schedule_delayed_work(&lcu->ruac_data.dwork, 30*HZ))
 575                         dasd_put_device(device);
 576         } else {
 577                 dasd_put_device(device);
 578                 lcu->ruac_data.device = NULL;
 579                 lcu->flags &= ~UPDATE_PENDING;
 580         }
 581         spin_unlock_irqrestore(&lcu->lock, flags);
 582 }
 583
 584 static int _schedule_lcu_update(struct alias_lcu *lcu,
 585                                 struct dasd_device *device)
 586 {
 587         struct dasd_device *usedev = NULL;
 588         struct alias_pav_group *group;
 589
 590         lcu->flags |= NEED_UAC_UPDATE;
 591         if (lcu->ruac_data.device) {
 592                 /* already scheduled or running */
 593                 return 0;
 594         }
 595         if (device && !list_empty(&device->alias_list))
 596                 usedev = device;
 597
 598         if (!usedev && !list_empty(&lcu->grouplist)) {
 599                 group = list_first_entry(&lcu->grouplist,
 600                                          struct alias_pav_group, group);
 601                 if (!list_empty(&group->baselist))
 602                         usedev = list_first_entry(&group->baselist,
 603                                                   struct dasd_device,
 604                                                   alias_list);
 605                 else if (!list_empty(&group->aliaslist))
 606                         usedev = list_first_entry(&group->aliaslist,
 607                                                   struct dasd_device,
 608                                                   alias_list);
 609         }
 610         if (!usedev && !list_empty(&lcu->active_devices)) {
 611                 usedev = list_first_entry(&lcu->active_devices,
 612                                           struct dasd_device, alias_list);
 613         }
 614         /*
 615          * if we haven't found a proper device yet, give up for now, the next
 616          * device that will be set active will trigger an lcu update
 617          */
 618         if (!usedev)
 619                 return -EINVAL;
 620         dasd_get_device(usedev);
 621         lcu->ruac_data.device = usedev;
 622         if (!schedule_delayed_work(&lcu->ruac_data.dwork, 0))
 623                 dasd_put_device(usedev);
 624         return 0;
 625 }
 626
 627 int dasd_alias_add_device(struct dasd_device *device)
 628 {
 629         struct dasd_eckd_private *private;
 630         struct alias_lcu *lcu;
 631         unsigned long flags;
 632         int rc;
 633
 634         private = (struct dasd_eckd_private *) device->private;
 635         lcu = private->lcu;
 636         rc = 0;
 637
 638         /* need to take cdev lock before lcu lock */
 639         spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 640         spin_lock(&lcu->lock);
 641         if (!(lcu->flags & UPDATE_PENDING)) {
 642                 rc = _add_device_to_lcu(lcu, device, device);
 643                 if (rc)
 644                         lcu->flags |= UPDATE_PENDING;
 645         }
 646         if (lcu->flags & UPDATE_PENDING) {
 647                 list_move(&device->alias_list, &lcu->active_devices);
 648                 private->pavgroup = NULL;
 649                 _schedule_lcu_update(lcu, device);
 650         }
 651         spin_unlock(&lcu->lock);
 652         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 653         return rc;
 654 }
 655
 656 int dasd_alias_update_add_device(struct dasd_device *device)
 657 {
 658         struct dasd_eckd_private *private;
 659         private = (struct dasd_eckd_private *) device->private;
 660         private->lcu->flags |= UPDATE_PENDING;
 661         return dasd_alias_add_device(device);
 662 }
 663
 664 int dasd_alias_remove_device(struct dasd_device *device)
 665 {
 666         struct dasd_eckd_private *private;
 667         struct alias_lcu *lcu;
 668         unsigned long flags;
 669
 670         private = (struct dasd_eckd_private *) device->private;
 671         lcu = private->lcu;
 672         /* nothing to do if already removed */
 673         if (!lcu)
 674                 return 0;
 675         spin_lock_irqsave(&lcu->lock, flags);
 676         _remove_device_from_lcu(lcu, device);
 677         spin_unlock_irqrestore(&lcu->lock, flags);
 678         return 0;
 679 }
 680
 681 struct dasd_device *dasd_alias_get_start_dev(struct dasd_device *base_device)
 682 {
 683
 684         struct dasd_device *alias_device;
 685         struct alias_pav_group *group;
 686         struct alias_lcu *lcu;
 687         struct dasd_eckd_private *private, *alias_priv;
 688         unsigned long flags;
 689
 690         private = (struct dasd_eckd_private *) base_device->private;
 691         group = private->pavgroup;
 692         lcu = private->lcu;
 693         if (!group || !lcu)
 694                 return NULL;
 695         if (lcu->pav == NO_PAV ||
 696             lcu->flags & (NEED_UAC_UPDATE | UPDATE_PENDING))
 697                 return NULL;
 698         if (unlikely(!(private->features.feature[8] & 0x01))) {
 699                 /*
 700                  * PAV enabled but prefix not, very unlikely
 701                  * seems to be a lost pathgroup
 702                  * use base device to do IO
 703                  */
 704                 DBF_DEV_EVENT(DBF_ERR, base_device, "%s",
 705                               "Prefix not enabled with PAV enabled\n");
 706                 return NULL;
 707         }
 708
 709         spin_lock_irqsave(&lcu->lock, flags);
 710         alias_device = group->next;
 711         if (!alias_device) {
 712                 if (list_empty(&group->aliaslist)) {
 713                         spin_unlock_irqrestore(&lcu->lock, flags);
 714                         return NULL;
 715                 } else {
 716                         alias_device = list_first_entry(&group->aliaslist,
 717                                                         struct dasd_device,
 718                                                         alias_list);
 719                 }
 720         }
 721         if (list_is_last(&alias_device->alias_list, &group->aliaslist))
 722                 group->next = list_first_entry(&group->aliaslist,
 723                                                struct dasd_device, alias_list);
 724         else
 725                 group->next = list_first_entry(&alias_device->alias_list,
 726                                                struct dasd_device, alias_list);
 727         spin_unlock_irqrestore(&lcu->lock, flags);
 728         alias_priv = (struct dasd_eckd_private *) alias_device->private;
 729         if ((alias_priv->count < private->count) && !alias_device->stopped &&
 730             !test_bit(DASD_FLAG_OFFLINE, &alias_device->flags))
 731                 return alias_device;
 732         else
 733                 return NULL;
 734 }
 735
 736 /*
 737  * Summary unit check handling depends on the way alias devices
 738  * are handled so it is done here rather then in dasd_eckd.c
 739  */
 740 static int reset_summary_unit_check(struct alias_lcu *lcu,
 741                                     struct dasd_device *device,
 742                                     char reason)
 743 {
 744         struct dasd_ccw_req *cqr;
 745         int rc = 0;
 746         struct ccw1 *ccw;
 747
 748         cqr = lcu->rsu_cqr;
 749         strncpy((char *) &cqr->magic, "ECKD", 4);
 750         ASCEBC((char *) &cqr->magic, 4);
 751         ccw = cqr->cpaddr;
 752         ccw->cmd_code = DASD_ECKD_CCW_RSCK;
 753         ccw->flags = CCW_FLAG_SLI;
 754         ccw->count = 16;
 755         ccw->cda = (__u32)(addr_t) cqr->data;
 756         ((char *)cqr->data)[0] = reason;
 757
 758         clear_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
 759         cqr->retries = 255;     /* set retry counter to enable basic ERP */
 760         cqr->startdev = device;
 761         cqr->memdev = device;
 762         cqr->block = NULL;
 763         cqr->expires = 5 * HZ;
 764         cqr->buildclk = get_tod_clock();
 765         cqr->status = DASD_CQR_FILLED;
 766
 767         rc = dasd_sleep_on_immediatly(cqr);
 768         return rc;
 769 }
 770
 771 static void _restart_all_base_devices_on_lcu(struct alias_lcu *lcu)
 772 {
 773         struct alias_pav_group *pavgroup;
 774         struct dasd_device *device;
 775         struct dasd_eckd_private *private;
 776         unsigned long flags;
 777
 778         /* active and inactive list can contain alias as well as base devices */
 779         list_for_each_entry(device, &lcu->active_devices, alias_list) {
 780                 private = (struct dasd_eckd_private *) device->private;
 781                 spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 782                 if (private->uid.type != UA_BASE_DEVICE) {
 783                         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev),
 784                                                flags);
 785                         continue;
 786                 }
 787                 spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 788                 dasd_schedule_block_bh(device->block);
 789                 dasd_schedule_device_bh(device);
 790         }
 791         list_for_each_entry(device, &lcu->inactive_devices, alias_list) {
 792                 private = (struct dasd_eckd_private *) device->private;
 793                 spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 794                 if (private->uid.type != UA_BASE_DEVICE) {
 795                         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev),
 796                                                flags);
 797                         continue;
 798                 }
 799                 spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 800                 dasd_schedule_block_bh(device->block);
 801                 dasd_schedule_device_bh(device);
 802         }
 803         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 804                 list_for_each_entry(device, &pavgroup->baselist, alias_list) {
 805                         dasd_schedule_block_bh(device->block);
 806                         dasd_schedule_device_bh(device);
 807                 }
 808         }
 809 }
 810
 811 static void flush_all_alias_devices_on_lcu(struct alias_lcu *lcu)
 812 {
 813         struct alias_pav_group *pavgroup;
 814         struct dasd_device *device, *temp;
 815         struct dasd_eckd_private *private;
 816         int rc;
 817         unsigned long flags;
 818         LIST_HEAD(active);
 819
 820         /*
 821          * Problem here ist that dasd_flush_device_queue may wait
 822          * for termination of a request to complete. We can't keep
 823          * the lcu lock during that time, so we must assume that
 824          * the lists may have changed.
 825          * Idea: first gather all active alias devices in a separate list,
 826          * then flush the first element of this list unlocked, and afterwards
 827          * check if it is still on the list before moving it to the
 828          * active_devices list.
 829          */
 830
 831         spin_lock_irqsave(&lcu->lock, flags);
 832         list_for_each_entry_safe(device, temp, &lcu->active_devices,
 833                                  alias_list) {
 834                 private = (struct dasd_eckd_private *) device->private;
 835                 if (private->uid.type == UA_BASE_DEVICE)
 836                         continue;
 837                 list_move(&device->alias_list, &active);
 838         }
 839
 840         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 841                 list_splice_init(&pavgroup->aliaslist, &active);
 842         }
 843         while (!list_empty(&active)) {
 844                 device = list_first_entry(&active, struct dasd_device,
 845                                           alias_list);
 846                 spin_unlock_irqrestore(&lcu->lock, flags);
 847                 rc = dasd_flush_device_queue(device);
 848                 spin_lock_irqsave(&lcu->lock, flags);
 849                 /*
 850                  * only move device around if it wasn't moved away while we
 851                  * were waiting for the flush
 852                  */
 853                 if (device == list_first_entry(&active,
 854                                                struct dasd_device, alias_list)) {
 855                         list_move(&device->alias_list, &lcu->active_devices);
 856                         private = (struct dasd_eckd_private *) device->private;
 857                         private->pavgroup = NULL;
 858                 }
 859         }
 860         spin_unlock_irqrestore(&lcu->lock, flags);
 861 }
 862
 863 static void __stop_device_on_lcu(struct dasd_device *device,
 864                                  struct dasd_device *pos)
 865 {
 866         /* If pos == device then device is already locked! */
 867         if (pos == device) {
 868                 dasd_device_set_stop_bits(pos, DASD_STOPPED_SU);
 869                 return;
 870         }
 871         spin_lock(get_ccwdev_lock(pos->cdev));
 872         dasd_device_set_stop_bits(pos, DASD_STOPPED_SU);
 873         spin_unlock(get_ccwdev_lock(pos->cdev));
 874 }
 875
 876 /*
 877  * This function is called in interrupt context, so the
 878  * cdev lock for device is already locked!
 879  */
 880 static void _stop_all_devices_on_lcu(struct alias_lcu *lcu,
 881                                      struct dasd_device *device)
 882 {
 883         struct alias_pav_group *pavgroup;
 884         struct dasd_device *pos;
 885
 886         list_for_each_entry(pos, &lcu->active_devices, alias_list)
 887                 __stop_device_on_lcu(device, pos);
 888         list_for_each_entry(pos, &lcu->inactive_devices, alias_list)
 889                 __stop_device_on_lcu(device, pos);
 890         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 891                 list_for_each_entry(pos, &pavgroup->baselist, alias_list)
 892                         __stop_device_on_lcu(device, pos);
 893                 list_for_each_entry(pos, &pavgroup->aliaslist, alias_list)
 894                         __stop_device_on_lcu(device, pos);
 895         }
 896 }
 897
 898 static void _unstop_all_devices_on_lcu(struct alias_lcu *lcu)
 899 {
 900         struct alias_pav_group *pavgroup;
 901         struct dasd_device *device;
 902         unsigned long flags;
 903
 904         list_for_each_entry(device, &lcu->active_devices, alias_list) {
 905                 spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 906                 dasd_device_remove_stop_bits(device, DASD_STOPPED_SU);
 907                 spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 908         }
 909
 910         list_for_each_entry(device, &lcu->inactive_devices, alias_list) {
 911                 spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 912                 dasd_device_remove_stop_bits(device, DASD_STOPPED_SU);
 913                 spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 914         }
 915
 916         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 917                 list_for_each_entry(device, &pavgroup->baselist, alias_list) {
 918                         spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 919                         dasd_device_remove_stop_bits(device, DASD_STOPPED_SU);
 920                         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev),
 921                                                flags);
 922                 }
 923                 list_for_each_entry(device, &pavgroup->aliaslist, alias_list) {
 924                         spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 925                         dasd_device_remove_stop_bits(device, DASD_STOPPED_SU);
 926                         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev),
 927                                                flags);
 928                 }
 929         }
 930 }
 931
 932 static void summary_unit_check_handling_work(struct work_struct *work)
 933 {
 934         struct alias_lcu *lcu;
 935         struct summary_unit_check_work_data *suc_data;
 936         unsigned long flags;
 937         struct dasd_device *device;
 938
 939         suc_data = container_of(work, struct summary_unit_check_work_data,
 940                                 worker);
 941         lcu = container_of(suc_data, struct alias_lcu, suc_data);
 942         device = suc_data->device;
 943
 944         /* 1. flush alias devices */
 945         flush_all_alias_devices_on_lcu(lcu);
 946
 947         /* 2. reset summary unit check */
 948         spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 949         dasd_device_remove_stop_bits(device,
 950                                      (DASD_STOPPED_SU | DASD_STOPPED_PENDING));
 951         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 952         reset_summary_unit_check(lcu, device, suc_data->reason);
 953
 954         spin_lock_irqsave(&lcu->lock, flags);
 955         _unstop_all_devices_on_lcu(lcu);
 956         _restart_all_base_devices_on_lcu(lcu);
 957         /* 3. read new alias configuration */
 958         _schedule_lcu_update(lcu, device);
 959         lcu->suc_data.device = NULL;
 960         dasd_put_device(device);
 961         spin_unlock_irqrestore(&lcu->lock, flags);
 962 }
 963
 964 /*
 965  * note: this will be called from int handler context (cdev locked)
 966  */
 967 void dasd_alias_handle_summary_unit_check(struct dasd_device *device,
 968                                           struct irb *irb)
 969 {
 970         struct alias_lcu *lcu;
 971         char reason;
 972         struct dasd_eckd_private *private;
 973         char *sense;
 974
 975         private = (struct dasd_eckd_private *) device->private;
 976
 977         sense = dasd_get_sense(irb);
 978         if (sense) {
 979                 reason = sense[8];
 980                 DBF_DEV_EVENT(DBF_NOTICE, device, "%s %x",
 981                             "eckd handle summary unit check: reason", reason);
 982         } else {
 983                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
 984                             "eckd handle summary unit check:"
 985                             " no reason code available");
 986                 return;
 987         }
 988
 989         lcu = private->lcu;
 990         if (!lcu) {
 991                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
 992                             "device not ready to handle summary"
 993                             " unit check (no lcu structure)");
 994                 return;
 995         }
 996         spin_lock(&lcu->lock);
 997         _stop_all_devices_on_lcu(lcu, device);
 998         /* prepare for lcu_update */
 999         private->lcu->flags |= NEED_UAC_UPDATE | UPDATE_PENDING;
1000         /* If this device is about to be removed just return and wait for
1001          * the next interrupt on a different device
1002          */
1003         if (list_empty(&device->alias_list)) {
1004                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
1005                             "device is in offline processing,"
1006                             " don't do summary unit check handling");
1007                 spin_unlock(&lcu->lock);
1008                 return;
1009         }
1010         if (lcu->suc_data.device) {
1011                 /* already scheduled or running */
1012                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
1013                             "previous instance of summary unit check worker"
1014                             " still pending");
1015                 spin_unlock(&lcu->lock);
1016                 return ;
1017         }
1018         lcu->suc_data.reason = reason;
1019         lcu->suc_data.device = device;
1020         dasd_get_device(device);
1021         spin_unlock(&lcu->lock);
1022         if (!schedule_work(&lcu->suc_data.worker))
1023                 dasd_put_device(device);
1024 };