drivers/s390/block/dasd_alias.c

   1 /*
   2  * PAV alias management for the DASD ECKD discipline
   3  *
   4  * Copyright IBM Corporation, 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         int is_lcu_known;
 193         struct dasd_uid *uid;
 194
 195         private = (struct dasd_eckd_private *) device->private;
 196         uid = &private->uid;
 197         spin_lock_irqsave(&aliastree.lock, flags);
 198         is_lcu_known = 1;
 199         server = _find_server(uid);
 200         if (!server) {
 201                 spin_unlock_irqrestore(&aliastree.lock, flags);
 202                 newserver = _allocate_server(uid);
 203                 if (IS_ERR(newserver))
 204                         return PTR_ERR(newserver);
 205                 spin_lock_irqsave(&aliastree.lock, flags);
 206                 server = _find_server(uid);
 207                 if (!server) {
 208                         list_add(&newserver->server, &aliastree.serverlist);
 209                         server = newserver;
 210                         is_lcu_known = 0;
 211                 } else {
 212                         /* someone was faster */
 213                         _free_server(newserver);
 214                 }
 215         }
 216
 217         lcu = _find_lcu(server, uid);
 218         if (!lcu) {
 219                 spin_unlock_irqrestore(&aliastree.lock, flags);
 220                 newlcu = _allocate_lcu(uid);
 221                 if (IS_ERR(newlcu))
 222                         return PTR_ERR(newlcu);
 223                 spin_lock_irqsave(&aliastree.lock, flags);
 224                 lcu = _find_lcu(server, uid);
 225                 if (!lcu) {
 226                         list_add(&newlcu->lcu, &server->lculist);
 227                         lcu = newlcu;
 228                         is_lcu_known = 0;
 229                 } else {
 230                         /* someone was faster */
 231                         _free_lcu(newlcu);
 232                 }
 233                 is_lcu_known = 0;
 234         }
 235         spin_lock(&lcu->lock);
 236         list_add(&device->alias_list, &lcu->inactive_devices);
 237         private->lcu = lcu;
 238         spin_unlock(&lcu->lock);
 239         spin_unlock_irqrestore(&aliastree.lock, flags);
 240
 241         return is_lcu_known;
 242 }
 243
 244 /*
 245  * The first device to be registered on an LCU will have to do
 246  * some additional setup steps to configure that LCU on the
 247  * storage server. All further devices should wait with their
 248  * initialization until the first device is done.
 249  * To synchronize this work, the first device will call
 250  * dasd_alias_lcu_setup_complete when it is done, and all
 251  * other devices will wait for it with dasd_alias_wait_for_lcu_setup.
 252  */
 253 void dasd_alias_lcu_setup_complete(struct dasd_device *device)
 254 {
 255         struct dasd_eckd_private *private;
 256         unsigned long flags;
 257         struct alias_server *server;
 258         struct alias_lcu *lcu;
 259         struct dasd_uid *uid;
 260
 261         private = (struct dasd_eckd_private *) device->private;
 262         uid = &private->uid;
 263         lcu = NULL;
 264         spin_lock_irqsave(&aliastree.lock, flags);
 265         server = _find_server(uid);
 266         if (server)
 267                 lcu = _find_lcu(server, uid);
 268         spin_unlock_irqrestore(&aliastree.lock, flags);
 269         if (!lcu) {
 270                 DBF_EVENT_DEVID(DBF_ERR, device->cdev,
 271                                 "could not find lcu for %04x %02x",
 272                                 uid->ssid, uid->real_unit_addr);
 273                 WARN_ON(1);
 274                 return;
 275         }
 276         complete_all(&lcu->lcu_setup);
 277 }
 278
 279 void dasd_alias_wait_for_lcu_setup(struct dasd_device *device)
 280 {
 281         struct dasd_eckd_private *private;
 282         unsigned long flags;
 283         struct alias_server *server;
 284         struct alias_lcu *lcu;
 285         struct dasd_uid *uid;
 286
 287         private = (struct dasd_eckd_private *) device->private;
 288         uid = &private->uid;
 289         lcu = NULL;
 290         spin_lock_irqsave(&aliastree.lock, flags);
 291         server = _find_server(uid);
 292         if (server)
 293                 lcu = _find_lcu(server, uid);
 294         spin_unlock_irqrestore(&aliastree.lock, flags);
 295         if (!lcu) {
 296                 DBF_EVENT_DEVID(DBF_ERR, device->cdev,
 297                                 "could not find lcu for %04x %02x",
 298                                 uid->ssid, uid->real_unit_addr);
 299                 WARN_ON(1);
 300                 return;
 301         }
 302         wait_for_completion(&lcu->lcu_setup);
 303 }
 304
 305 /*
 306  * This function removes a device from the scope of alias management.
 307  * The complicated part is to make sure that it is not in use by
 308  * any of the workers. If necessary cancel the work.
 309  */
 310 void dasd_alias_disconnect_device_from_lcu(struct dasd_device *device)
 311 {
 312         struct dasd_eckd_private *private;
 313         unsigned long flags;
 314         struct alias_lcu *lcu;
 315         struct alias_server *server;
 316         int was_pending;
 317
 318         private = (struct dasd_eckd_private *) device->private;
 319         lcu = private->lcu;
 320         spin_lock_irqsave(&lcu->lock, flags);
 321         list_del_init(&device->alias_list);
 322         /* make sure that the workers don't use this device */
 323         if (device == lcu->suc_data.device) {
 324                 spin_unlock_irqrestore(&lcu->lock, flags);
 325                 cancel_work_sync(&lcu->suc_data.worker);
 326                 spin_lock_irqsave(&lcu->lock, flags);
 327                 if (device == lcu->suc_data.device)
 328                         lcu->suc_data.device = NULL;
 329         }
 330         was_pending = 0;
 331         if (device == lcu->ruac_data.device) {
 332                 spin_unlock_irqrestore(&lcu->lock, flags);
 333                 was_pending = 1;
 334                 cancel_delayed_work_sync(&lcu->ruac_data.dwork);
 335                 spin_lock_irqsave(&lcu->lock, flags);
 336                 if (device == lcu->ruac_data.device)
 337                         lcu->ruac_data.device = NULL;
 338         }
 339         private->lcu = NULL;
 340         spin_unlock_irqrestore(&lcu->lock, flags);
 341
 342         spin_lock_irqsave(&aliastree.lock, flags);
 343         spin_lock(&lcu->lock);
 344         if (list_empty(&lcu->grouplist) &&
 345             list_empty(&lcu->active_devices) &&
 346             list_empty(&lcu->inactive_devices)) {
 347                 list_del(&lcu->lcu);
 348                 spin_unlock(&lcu->lock);
 349                 _free_lcu(lcu);
 350                 lcu = NULL;
 351         } else {
 352                 if (was_pending)
 353                         _schedule_lcu_update(lcu, NULL);
 354                 spin_unlock(&lcu->lock);
 355         }
 356         server = _find_server(&private->uid);
 357         if (server && list_empty(&server->lculist)) {
 358                 list_del(&server->server);
 359                 _free_server(server);
 360         }
 361         spin_unlock_irqrestore(&aliastree.lock, flags);
 362 }
 363
 364 /*
 365  * This function assumes that the unit address configuration stored
 366  * in the lcu is up to date and will update the device uid before
 367  * adding it to a pav group.
 368  */
 369 static int _add_device_to_lcu(struct alias_lcu *lcu,
 370                               struct dasd_device *device)
 371 {
 372
 373         struct dasd_eckd_private *private;
 374         struct alias_pav_group *group;
 375         struct dasd_uid *uid;
 376
 377         private = (struct dasd_eckd_private *) device->private;
 378         uid = &private->uid;
 379         uid->type = lcu->uac->unit[uid->real_unit_addr].ua_type;
 380         uid->base_unit_addr = lcu->uac->unit[uid->real_unit_addr].base_ua;
 381         dasd_set_uid(device->cdev, &private->uid);
 382
 383         /* if we have no PAV anyway, we don't need to bother with PAV groups */
 384         if (lcu->pav == NO_PAV) {
 385                 list_move(&device->alias_list, &lcu->active_devices);
 386                 return 0;
 387         }
 388
 389         group = _find_group(lcu, uid);
 390         if (!group) {
 391                 group = kzalloc(sizeof(*group), GFP_ATOMIC);
 392                 if (!group)
 393                         return -ENOMEM;
 394                 memcpy(group->uid.vendor, uid->vendor, sizeof(uid->vendor));
 395                 memcpy(group->uid.serial, uid->serial, sizeof(uid->serial));
 396                 group->uid.ssid = uid->ssid;
 397                 if (uid->type == UA_BASE_DEVICE)
 398                         group->uid.base_unit_addr = uid->real_unit_addr;
 399                 else
 400                         group->uid.base_unit_addr = uid->base_unit_addr;
 401                 memcpy(group->uid.vduit, uid->vduit, sizeof(uid->vduit));
 402                 INIT_LIST_HEAD(&group->group);
 403                 INIT_LIST_HEAD(&group->baselist);
 404                 INIT_LIST_HEAD(&group->aliaslist);
 405                 list_add(&group->group, &lcu->grouplist);
 406         }
 407         if (uid->type == UA_BASE_DEVICE)
 408                 list_move(&device->alias_list, &group->baselist);
 409         else
 410                 list_move(&device->alias_list, &group->aliaslist);
 411         private->pavgroup = group;
 412         return 0;
 413 };
 414
 415 static void _remove_device_from_lcu(struct alias_lcu *lcu,
 416                                     struct dasd_device *device)
 417 {
 418         struct dasd_eckd_private *private;
 419         struct alias_pav_group *group;
 420
 421         private = (struct dasd_eckd_private *) device->private;
 422         list_move(&device->alias_list, &lcu->inactive_devices);
 423         group = private->pavgroup;
 424         if (!group)
 425                 return;
 426         private->pavgroup = NULL;
 427         if (list_empty(&group->baselist) && list_empty(&group->aliaslist)) {
 428                 list_del(&group->group);
 429                 kfree(group);
 430                 return;
 431         }
 432         if (group->next == device)
 433                 group->next = NULL;
 434 };
 435
 436 static int read_unit_address_configuration(struct dasd_device *device,
 437                                            struct alias_lcu *lcu)
 438 {
 439         struct dasd_psf_prssd_data *prssdp;
 440         struct dasd_ccw_req *cqr;
 441         struct ccw1 *ccw;
 442         int rc;
 443         unsigned long flags;
 444
 445         cqr = dasd_kmalloc_request(DASD_ECKD_MAGIC, 1 /* PSF */ + 1 /* RSSD */,
 446                                    (sizeof(struct dasd_psf_prssd_data)),
 447                                    device);
 448         if (IS_ERR(cqr))
 449                 return PTR_ERR(cqr);
 450         cqr->startdev = device;
 451         cqr->memdev = device;
 452         clear_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
 453         cqr->retries = 10;
 454         cqr->expires = 20 * HZ;
 455
 456         /* Prepare for Read Subsystem Data */
 457         prssdp = (struct dasd_psf_prssd_data *) cqr->data;
 458         memset(prssdp, 0, sizeof(struct dasd_psf_prssd_data));
 459         prssdp->order = PSF_ORDER_PRSSD;
 460         prssdp->suborder = 0x0e;        /* Read unit address configuration */
 461         /* all other bytes of prssdp must be zero */
 462
 463         ccw = cqr->cpaddr;
 464         ccw->cmd_code = DASD_ECKD_CCW_PSF;
 465         ccw->count = sizeof(struct dasd_psf_prssd_data);
 466         ccw->flags |= CCW_FLAG_CC;
 467         ccw->cda = (__u32)(addr_t) prssdp;
 468
 469         /* Read Subsystem Data - feature codes */
 470         memset(lcu->uac, 0, sizeof(*(lcu->uac)));
 471
 472         ccw++;
 473         ccw->cmd_code = DASD_ECKD_CCW_RSSD;
 474         ccw->count = sizeof(*(lcu->uac));
 475         ccw->cda = (__u32)(addr_t) lcu->uac;
 476
 477         cqr->buildclk = get_clock();
 478         cqr->status = DASD_CQR_FILLED;
 479
 480         /* need to unset flag here to detect race with summary unit check */
 481         spin_lock_irqsave(&lcu->lock, flags);
 482         lcu->flags &= ~NEED_UAC_UPDATE;
 483         spin_unlock_irqrestore(&lcu->lock, flags);
 484
 485         do {
 486                 rc = dasd_sleep_on(cqr);
 487         } while (rc && (cqr->retries > 0));
 488         if (rc) {
 489                 spin_lock_irqsave(&lcu->lock, flags);
 490                 lcu->flags |= NEED_UAC_UPDATE;
 491                 spin_unlock_irqrestore(&lcu->lock, flags);
 492         }
 493         dasd_kfree_request(cqr, cqr->memdev);
 494         return rc;
 495 }
 496
 497 static int _lcu_update(struct dasd_device *refdev, struct alias_lcu *lcu)
 498 {
 499         unsigned long flags;
 500         struct alias_pav_group *pavgroup, *tempgroup;
 501         struct dasd_device *device, *tempdev;
 502         int i, rc;
 503         struct dasd_eckd_private *private;
 504
 505         spin_lock_irqsave(&lcu->lock, flags);
 506         list_for_each_entry_safe(pavgroup, tempgroup, &lcu->grouplist, group) {
 507                 list_for_each_entry_safe(device, tempdev, &pavgroup->baselist,
 508                                          alias_list) {
 509                         list_move(&device->alias_list, &lcu->active_devices);
 510                         private = (struct dasd_eckd_private *) device->private;
 511                         private->pavgroup = NULL;
 512                 }
 513                 list_for_each_entry_safe(device, tempdev, &pavgroup->aliaslist,
 514                                          alias_list) {
 515                         list_move(&device->alias_list, &lcu->active_devices);
 516                         private = (struct dasd_eckd_private *) device->private;
 517                         private->pavgroup = NULL;
 518                 }
 519                 list_del(&pavgroup->group);
 520                 kfree(pavgroup);
 521         }
 522         spin_unlock_irqrestore(&lcu->lock, flags);
 523
 524         rc = read_unit_address_configuration(refdev, lcu);
 525         if (rc)
 526                 return rc;
 527
 528         spin_lock_irqsave(&lcu->lock, flags);
 529         lcu->pav = NO_PAV;
 530         for (i = 0; i < MAX_DEVICES_PER_LCU; ++i) {
 531                 switch (lcu->uac->unit[i].ua_type) {
 532                 case UA_BASE_PAV_ALIAS:
 533                         lcu->pav = BASE_PAV;
 534                         break;
 535                 case UA_HYPER_PAV_ALIAS:
 536                         lcu->pav = HYPER_PAV;
 537                         break;
 538                 }
 539                 if (lcu->pav != NO_PAV)
 540                         break;
 541         }
 542
 543         list_for_each_entry_safe(device, tempdev, &lcu->active_devices,
 544                                  alias_list) {
 545                 _add_device_to_lcu(lcu, device);
 546         }
 547         spin_unlock_irqrestore(&lcu->lock, flags);
 548         return 0;
 549 }
 550
 551 static void lcu_update_work(struct work_struct *work)
 552 {
 553         struct alias_lcu *lcu;
 554         struct read_uac_work_data *ruac_data;
 555         struct dasd_device *device;
 556         unsigned long flags;
 557         int rc;
 558
 559         ruac_data = container_of(work, struct read_uac_work_data, dwork.work);
 560         lcu = container_of(ruac_data, struct alias_lcu, ruac_data);
 561         device = ruac_data->device;
 562         rc = _lcu_update(device, lcu);
 563         /*
 564          * Need to check flags again, as there could have been another
 565          * prepare_update or a new device a new device while we were still
 566          * processing the data
 567          */
 568         spin_lock_irqsave(&lcu->lock, flags);
 569         if (rc || (lcu->flags & NEED_UAC_UPDATE)) {
 570                 DBF_DEV_EVENT(DBF_WARNING, device, "could not update"
 571                             " alias data in lcu (rc = %d), retry later", rc);
 572                 schedule_delayed_work(&lcu->ruac_data.dwork, 30*HZ);
 573         } else {
 574                 lcu->ruac_data.device = NULL;
 575                 lcu->flags &= ~UPDATE_PENDING;
 576         }
 577         spin_unlock_irqrestore(&lcu->lock, flags);
 578 }
 579
 580 static int _schedule_lcu_update(struct alias_lcu *lcu,
 581                                 struct dasd_device *device)
 582 {
 583         struct dasd_device *usedev = NULL;
 584         struct alias_pav_group *group;
 585
 586         lcu->flags |= NEED_UAC_UPDATE;
 587         if (lcu->ruac_data.device) {
 588                 /* already scheduled or running */
 589                 return 0;
 590         }
 591         if (device && !list_empty(&device->alias_list))
 592                 usedev = device;
 593
 594         if (!usedev && !list_empty(&lcu->grouplist)) {
 595                 group = list_first_entry(&lcu->grouplist,
 596                                          struct alias_pav_group, group);
 597                 if (!list_empty(&group->baselist))
 598                         usedev = list_first_entry(&group->baselist,
 599                                                   struct dasd_device,
 600                                                   alias_list);
 601                 else if (!list_empty(&group->aliaslist))
 602                         usedev = list_first_entry(&group->aliaslist,
 603                                                   struct dasd_device,
 604                                                   alias_list);
 605         }
 606         if (!usedev && !list_empty(&lcu->active_devices)) {
 607                 usedev = list_first_entry(&lcu->active_devices,
 608                                           struct dasd_device, alias_list);
 609         }
 610         /*
 611          * if we haven't found a proper device yet, give up for now, the next
 612          * device that will be set active will trigger an lcu update
 613          */
 614         if (!usedev)
 615                 return -EINVAL;
 616         lcu->ruac_data.device = usedev;
 617         schedule_delayed_work(&lcu->ruac_data.dwork, 0);
 618         return 0;
 619 }
 620
 621 int dasd_alias_add_device(struct dasd_device *device)
 622 {
 623         struct dasd_eckd_private *private;
 624         struct alias_lcu *lcu;
 625         unsigned long flags;
 626         int rc;
 627
 628         private = (struct dasd_eckd_private *) device->private;
 629         lcu = private->lcu;
 630         rc = 0;
 631         spin_lock_irqsave(&lcu->lock, flags);
 632         if (!(lcu->flags & UPDATE_PENDING)) {
 633                 rc = _add_device_to_lcu(lcu, device);
 634                 if (rc)
 635                         lcu->flags |= UPDATE_PENDING;
 636         }
 637         if (lcu->flags & UPDATE_PENDING) {
 638                 list_move(&device->alias_list, &lcu->active_devices);
 639                 _schedule_lcu_update(lcu, device);
 640         }
 641         spin_unlock_irqrestore(&lcu->lock, flags);
 642         return rc;
 643 }
 644
 645 int dasd_alias_remove_device(struct dasd_device *device)
 646 {
 647         struct dasd_eckd_private *private;
 648         struct alias_lcu *lcu;
 649         unsigned long flags;
 650
 651         private = (struct dasd_eckd_private *) device->private;
 652         lcu = private->lcu;
 653         spin_lock_irqsave(&lcu->lock, flags);
 654         _remove_device_from_lcu(lcu, device);
 655         spin_unlock_irqrestore(&lcu->lock, flags);
 656         return 0;
 657 }
 658
 659 struct dasd_device *dasd_alias_get_start_dev(struct dasd_device *base_device)
 660 {
 661
 662         struct dasd_device *alias_device;
 663         struct alias_pav_group *group;
 664         struct alias_lcu *lcu;
 665         struct dasd_eckd_private *private, *alias_priv;
 666         unsigned long flags;
 667
 668         private = (struct dasd_eckd_private *) base_device->private;
 669         group = private->pavgroup;
 670         lcu = private->lcu;
 671         if (!group || !lcu)
 672                 return NULL;
 673         if (lcu->pav == NO_PAV ||
 674             lcu->flags & (NEED_UAC_UPDATE | UPDATE_PENDING))
 675                 return NULL;
 676
 677         spin_lock_irqsave(&lcu->lock, flags);
 678         alias_device = group->next;
 679         if (!alias_device) {
 680                 if (list_empty(&group->aliaslist)) {
 681                         spin_unlock_irqrestore(&lcu->lock, flags);
 682                         return NULL;
 683                 } else {
 684                         alias_device = list_first_entry(&group->aliaslist,
 685                                                         struct dasd_device,
 686                                                         alias_list);
 687                 }
 688         }
 689         if (list_is_last(&alias_device->alias_list, &group->aliaslist))
 690                 group->next = list_first_entry(&group->aliaslist,
 691                                                struct dasd_device, alias_list);
 692         else
 693                 group->next = list_first_entry(&alias_device->alias_list,
 694                                                struct dasd_device, alias_list);
 695         spin_unlock_irqrestore(&lcu->lock, flags);
 696         alias_priv = (struct dasd_eckd_private *) alias_device->private;
 697         if ((alias_priv->count < private->count) && !alias_device->stopped)
 698                 return alias_device;
 699         else
 700                 return NULL;
 701 }
 702
 703 /*
 704  * Summary unit check handling depends on the way alias devices
 705  * are handled so it is done here rather then in dasd_eckd.c
 706  */
 707 static int reset_summary_unit_check(struct alias_lcu *lcu,
 708                                     struct dasd_device *device,
 709                                     char reason)
 710 {
 711         struct dasd_ccw_req *cqr;
 712         int rc = 0;
 713         struct ccw1 *ccw;
 714
 715         cqr = lcu->rsu_cqr;
 716         strncpy((char *) &cqr->magic, "ECKD", 4);
 717         ASCEBC((char *) &cqr->magic, 4);
 718         ccw = cqr->cpaddr;
 719         ccw->cmd_code = DASD_ECKD_CCW_RSCK;
 720         ccw->flags = 0 ;
 721         ccw->count = 16;
 722         ccw->cda = (__u32)(addr_t) cqr->data;
 723         ((char *)cqr->data)[0] = reason;
 724
 725         clear_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
 726         cqr->retries = 255;     /* set retry counter to enable basic ERP */
 727         cqr->startdev = device;
 728         cqr->memdev = device;
 729         cqr->block = NULL;
 730         cqr->expires = 5 * HZ;
 731         cqr->buildclk = get_clock();
 732         cqr->status = DASD_CQR_FILLED;
 733
 734         rc = dasd_sleep_on_immediatly(cqr);
 735         return rc;
 736 }
 737
 738 static void _restart_all_base_devices_on_lcu(struct alias_lcu *lcu)
 739 {
 740         struct alias_pav_group *pavgroup;
 741         struct dasd_device *device;
 742         struct dasd_eckd_private *private;
 743
 744         /* active and inactive list can contain alias as well as base devices */
 745         list_for_each_entry(device, &lcu->active_devices, alias_list) {
 746                 private = (struct dasd_eckd_private *) device->private;
 747                 if (private->uid.type != UA_BASE_DEVICE)
 748                         continue;
 749                 dasd_schedule_block_bh(device->block);
 750                 dasd_schedule_device_bh(device);
 751         }
 752         list_for_each_entry(device, &lcu->inactive_devices, alias_list) {
 753                 private = (struct dasd_eckd_private *) device->private;
 754                 if (private->uid.type != UA_BASE_DEVICE)
 755                         continue;
 756                 dasd_schedule_block_bh(device->block);
 757                 dasd_schedule_device_bh(device);
 758         }
 759         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 760                 list_for_each_entry(device, &pavgroup->baselist, alias_list) {
 761                         dasd_schedule_block_bh(device->block);
 762                         dasd_schedule_device_bh(device);
 763                 }
 764         }
 765 }
 766
 767 static void flush_all_alias_devices_on_lcu(struct alias_lcu *lcu)
 768 {
 769         struct alias_pav_group *pavgroup;
 770         struct dasd_device *device, *temp;
 771         struct dasd_eckd_private *private;
 772         int rc;
 773         unsigned long flags;
 774         LIST_HEAD(active);
 775
 776         /*
 777          * Problem here ist that dasd_flush_device_queue may wait
 778          * for termination of a request to complete. We can't keep
 779          * the lcu lock during that time, so we must assume that
 780          * the lists may have changed.
 781          * Idea: first gather all active alias devices in a separate list,
 782          * then flush the first element of this list unlocked, and afterwards
 783          * check if it is still on the list before moving it to the
 784          * active_devices list.
 785          */
 786
 787         spin_lock_irqsave(&lcu->lock, flags);
 788         list_for_each_entry_safe(device, temp, &lcu->active_devices,
 789                                  alias_list) {
 790                 private = (struct dasd_eckd_private *) device->private;
 791                 if (private->uid.type == UA_BASE_DEVICE)
 792                         continue;
 793                 list_move(&device->alias_list, &active);
 794         }
 795
 796         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 797                 list_splice_init(&pavgroup->aliaslist, &active);
 798         }
 799         while (!list_empty(&active)) {
 800                 device = list_first_entry(&active, struct dasd_device,
 801                                           alias_list);
 802                 spin_unlock_irqrestore(&lcu->lock, flags);
 803                 rc = dasd_flush_device_queue(device);
 804                 spin_lock_irqsave(&lcu->lock, flags);
 805                 /*
 806                  * only move device around if it wasn't moved away while we
 807                  * were waiting for the flush
 808                  */
 809                 if (device == list_first_entry(&active,
 810                                                struct dasd_device, alias_list))
 811                         list_move(&device->alias_list, &lcu->active_devices);
 812         }
 813         spin_unlock_irqrestore(&lcu->lock, flags);
 814 }
 815
 816 static void __stop_device_on_lcu(struct dasd_device *device,
 817                                  struct dasd_device *pos)
 818 {
 819         /* If pos == device then device is already locked! */
 820         if (pos == device) {
 821                 dasd_device_set_stop_bits(pos, DASD_STOPPED_SU);
 822                 return;
 823         }
 824         spin_lock(get_ccwdev_lock(pos->cdev));
 825         dasd_device_set_stop_bits(pos, DASD_STOPPED_SU);
 826         spin_unlock(get_ccwdev_lock(pos->cdev));
 827 }
 828
 829 /*
 830  * This function is called in interrupt context, so the
 831  * cdev lock for device is already locked!
 832  */
 833 static void _stop_all_devices_on_lcu(struct alias_lcu *lcu,
 834                                      struct dasd_device *device)
 835 {
 836         struct alias_pav_group *pavgroup;
 837         struct dasd_device *pos;
 838
 839         list_for_each_entry(pos, &lcu->active_devices, alias_list)
 840                 __stop_device_on_lcu(device, pos);
 841         list_for_each_entry(pos, &lcu->inactive_devices, alias_list)
 842                 __stop_device_on_lcu(device, pos);
 843         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 844                 list_for_each_entry(pos, &pavgroup->baselist, alias_list)
 845                         __stop_device_on_lcu(device, pos);
 846                 list_for_each_entry(pos, &pavgroup->aliaslist, alias_list)
 847                         __stop_device_on_lcu(device, pos);
 848         }
 849 }
 850
 851 static void _unstop_all_devices_on_lcu(struct alias_lcu *lcu)
 852 {
 853         struct alias_pav_group *pavgroup;
 854         struct dasd_device *device;
 855         unsigned long flags;
 856
 857         list_for_each_entry(device, &lcu->active_devices, alias_list) {
 858                 spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 859                 dasd_device_remove_stop_bits(device, DASD_STOPPED_SU);
 860                 spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 861         }
 862
 863         list_for_each_entry(device, &lcu->inactive_devices, alias_list) {
 864                 spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 865                 dasd_device_remove_stop_bits(device, DASD_STOPPED_SU);
 866                 spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 867         }
 868
 869         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 870                 list_for_each_entry(device, &pavgroup->baselist, alias_list) {
 871                         spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 872                         dasd_device_remove_stop_bits(device, DASD_STOPPED_SU);
 873                         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev),
 874                                                flags);
 875                 }
 876                 list_for_each_entry(device, &pavgroup->aliaslist, alias_list) {
 877                         spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 878                         dasd_device_remove_stop_bits(device, DASD_STOPPED_SU);
 879                         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev),
 880                                                flags);
 881                 }
 882         }
 883 }
 884
 885 static void summary_unit_check_handling_work(struct work_struct *work)
 886 {
 887         struct alias_lcu *lcu;
 888         struct summary_unit_check_work_data *suc_data;
 889         unsigned long flags;
 890         struct dasd_device *device;
 891
 892         suc_data = container_of(work, struct summary_unit_check_work_data,
 893                                 worker);
 894         lcu = container_of(suc_data, struct alias_lcu, suc_data);
 895         device = suc_data->device;
 896
 897         /* 1. flush alias devices */
 898         flush_all_alias_devices_on_lcu(lcu);
 899
 900         /* 2. reset summary unit check */
 901         spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 902         dasd_device_remove_stop_bits(device,
 903                                      (DASD_STOPPED_SU | DASD_STOPPED_PENDING));
 904         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 905         reset_summary_unit_check(lcu, device, suc_data->reason);
 906
 907         spin_lock_irqsave(&lcu->lock, flags);
 908         _unstop_all_devices_on_lcu(lcu);
 909         _restart_all_base_devices_on_lcu(lcu);
 910         /* 3. read new alias configuration */
 911         _schedule_lcu_update(lcu, device);
 912         lcu->suc_data.device = NULL;
 913         spin_unlock_irqrestore(&lcu->lock, flags);
 914 }
 915
 916 /*
 917  * note: this will be called from int handler context (cdev locked)
 918  */
 919 void dasd_alias_handle_summary_unit_check(struct dasd_device *device,
 920                                           struct irb *irb)
 921 {
 922         struct alias_lcu *lcu;
 923         char reason;
 924         struct dasd_eckd_private *private;
 925         char *sense;
 926
 927         private = (struct dasd_eckd_private *) device->private;
 928
 929         sense = dasd_get_sense(irb);
 930         if (sense) {
 931                 reason = sense[8];
 932                 DBF_DEV_EVENT(DBF_NOTICE, device, "%s %x",
 933                             "eckd handle summary unit check: reason", reason);
 934         } else {
 935                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
 936                             "eckd handle summary unit check:"
 937                             " no reason code available");
 938                 return;
 939         }
 940
 941         lcu = private->lcu;
 942         if (!lcu) {
 943                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
 944                             "device not ready to handle summary"
 945                             " unit check (no lcu structure)");
 946                 return;
 947         }
 948         spin_lock(&lcu->lock);
 949         _stop_all_devices_on_lcu(lcu, device);
 950         /* prepare for lcu_update */
 951         private->lcu->flags |= NEED_UAC_UPDATE | UPDATE_PENDING;
 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                 spin_unlock(&lcu->lock);
 960                 return;
 961         }
 962         if (lcu->suc_data.device) {
 963                 /* already scheduled or running */
 964                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
 965                             "previous instance of summary unit check worker"
 966                             " still pending");
 967                 spin_unlock(&lcu->lock);
 968                 return ;
 969         }
 970         lcu->suc_data.reason = reason;
 971         lcu->suc_data.device = device;
 972         spin_unlock(&lcu->lock);
 973         schedule_work(&lcu->suc_data.worker);
 974 };