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
 197         device->discipline->get_uid(device, &uid);
 198         spin_lock_irqsave(&aliastree.lock, flags);
 199         is_lcu_known = 1;
 200         server = _find_server(&uid);
 201         if (!server) {
 202                 spin_unlock_irqrestore(&aliastree.lock, flags);
 203                 newserver = _allocate_server(&uid);
 204                 if (IS_ERR(newserver))
 205                         return PTR_ERR(newserver);
 206                 spin_lock_irqsave(&aliastree.lock, flags);
 207                 server = _find_server(&uid);
 208                 if (!server) {
 209                         list_add(&newserver->server, &aliastree.serverlist);
 210                         server = newserver;
 211                         is_lcu_known = 0;
 212                 } else {
 213                         /* someone was faster */
 214                         _free_server(newserver);
 215                 }
 216         }
 217
 218         lcu = _find_lcu(server, &uid);
 219         if (!lcu) {
 220                 spin_unlock_irqrestore(&aliastree.lock, flags);
 221                 newlcu = _allocate_lcu(&uid);
 222                 if (IS_ERR(newlcu))
 223                         return PTR_ERR(newlcu);
 224                 spin_lock_irqsave(&aliastree.lock, flags);
 225                 lcu = _find_lcu(server, &uid);
 226                 if (!lcu) {
 227                         list_add(&newlcu->lcu, &server->lculist);
 228                         lcu = newlcu;
 229                         is_lcu_known = 0;
 230                 } else {
 231                         /* someone was faster */
 232                         _free_lcu(newlcu);
 233                 }
 234                 is_lcu_known = 0;
 235         }
 236         spin_lock(&lcu->lock);
 237         list_add(&device->alias_list, &lcu->inactive_devices);
 238         private->lcu = lcu;
 239         spin_unlock(&lcu->lock);
 240         spin_unlock_irqrestore(&aliastree.lock, flags);
 241
 242         return is_lcu_known;
 243 }
 244
 245 /*
 246  * The first device to be registered on an LCU will have to do
 247  * some additional setup steps to configure that LCU on the
 248  * storage server. All further devices should wait with their
 249  * initialization until the first device is done.
 250  * To synchronize this work, the first device will call
 251  * dasd_alias_lcu_setup_complete when it is done, and all
 252  * other devices will wait for it with dasd_alias_wait_for_lcu_setup.
 253  */
 254 void dasd_alias_lcu_setup_complete(struct dasd_device *device)
 255 {
 256         struct dasd_eckd_private *private;
 257         unsigned long flags;
 258         struct alias_server *server;
 259         struct alias_lcu *lcu;
 260         struct dasd_uid uid;
 261
 262         private = (struct dasd_eckd_private *) device->private;
 263         device->discipline->get_uid(device, &uid);
 264         lcu = NULL;
 265         spin_lock_irqsave(&aliastree.lock, flags);
 266         server = _find_server(&uid);
 267         if (server)
 268                 lcu = _find_lcu(server, &uid);
 269         spin_unlock_irqrestore(&aliastree.lock, flags);
 270         if (!lcu) {
 271                 DBF_EVENT_DEVID(DBF_ERR, device->cdev,
 272                                 "could not find lcu for %04x %02x",
 273                                 uid.ssid, uid.real_unit_addr);
 274                 WARN_ON(1);
 275                 return;
 276         }
 277         complete_all(&lcu->lcu_setup);
 278 }
 279
 280 void dasd_alias_wait_for_lcu_setup(struct dasd_device *device)
 281 {
 282         struct dasd_eckd_private *private;
 283         unsigned long flags;
 284         struct alias_server *server;
 285         struct alias_lcu *lcu;
 286         struct dasd_uid uid;
 287
 288         private = (struct dasd_eckd_private *) device->private;
 289         device->discipline->get_uid(device, &uid);
 290         lcu = NULL;
 291         spin_lock_irqsave(&aliastree.lock, flags);
 292         server = _find_server(&uid);
 293         if (server)
 294                 lcu = _find_lcu(server, &uid);
 295         spin_unlock_irqrestore(&aliastree.lock, flags);
 296         if (!lcu) {
 297                 DBF_EVENT_DEVID(DBF_ERR, device->cdev,
 298                                 "could not find lcu for %04x %02x",
 299                                 uid.ssid, uid.real_unit_addr);
 300                 WARN_ON(1);
 301                 return;
 302         }
 303         wait_for_completion(&lcu->lcu_setup);
 304 }
 305
 306 /*
 307  * This function removes a device from the scope of alias management.
 308  * The complicated part is to make sure that it is not in use by
 309  * any of the workers. If necessary cancel the work.
 310  */
 311 void dasd_alias_disconnect_device_from_lcu(struct dasd_device *device)
 312 {
 313         struct dasd_eckd_private *private;
 314         unsigned long flags;
 315         struct alias_lcu *lcu;
 316         struct alias_server *server;
 317         int was_pending;
 318         struct dasd_uid uid;
 319
 320         private = (struct dasd_eckd_private *) device->private;
 321         lcu = private->lcu;
 322         /* nothing to do if already disconnected */
 323         if (!lcu)
 324                 return;
 325         device->discipline->get_uid(device, &uid);
 326         spin_lock_irqsave(&lcu->lock, flags);
 327         list_del_init(&device->alias_list);
 328         /* make sure that the workers don't use this device */
 329         if (device == lcu->suc_data.device) {
 330                 spin_unlock_irqrestore(&lcu->lock, flags);
 331                 cancel_work_sync(&lcu->suc_data.worker);
 332                 spin_lock_irqsave(&lcu->lock, flags);
 333                 if (device == lcu->suc_data.device)
 334                         lcu->suc_data.device = NULL;
 335         }
 336         was_pending = 0;
 337         if (device == lcu->ruac_data.device) {
 338                 spin_unlock_irqrestore(&lcu->lock, flags);
 339                 was_pending = 1;
 340                 cancel_delayed_work_sync(&lcu->ruac_data.dwork);
 341                 spin_lock_irqsave(&lcu->lock, flags);
 342                 if (device == lcu->ruac_data.device)
 343                         lcu->ruac_data.device = NULL;
 344         }
 345         private->lcu = NULL;
 346         spin_unlock_irqrestore(&lcu->lock, flags);
 347
 348         spin_lock_irqsave(&aliastree.lock, flags);
 349         spin_lock(&lcu->lock);
 350         if (list_empty(&lcu->grouplist) &&
 351             list_empty(&lcu->active_devices) &&
 352             list_empty(&lcu->inactive_devices)) {
 353                 list_del(&lcu->lcu);
 354                 spin_unlock(&lcu->lock);
 355                 _free_lcu(lcu);
 356                 lcu = NULL;
 357         } else {
 358                 if (was_pending)
 359                         _schedule_lcu_update(lcu, NULL);
 360                 spin_unlock(&lcu->lock);
 361         }
 362         server = _find_server(&uid);
 363         if (server && list_empty(&server->lculist)) {
 364                 list_del(&server->server);
 365                 _free_server(server);
 366         }
 367         spin_unlock_irqrestore(&aliastree.lock, flags);
 368 }
 369
 370 /*
 371  * This function assumes that the unit address configuration stored
 372  * in the lcu is up to date and will update the device uid before
 373  * adding it to a pav group.
 374  */
 375
 376 static int _add_device_to_lcu(struct alias_lcu *lcu,
 377                               struct dasd_device *device,
 378                               struct dasd_device *pos)
 379 {
 380
 381         struct dasd_eckd_private *private;
 382         struct alias_pav_group *group;
 383         struct dasd_uid uid;
 384         unsigned long flags;
 385
 386         private = (struct dasd_eckd_private *) device->private;
 387
 388         /* only lock if not already locked */
 389         if (device != pos)
 390                 spin_lock_irqsave_nested(get_ccwdev_lock(device->cdev), flags,
 391                                          CDEV_NESTED_SECOND);
 392         private->uid.type = lcu->uac->unit[private->uid.real_unit_addr].ua_type;
 393         private->uid.base_unit_addr =
 394                 lcu->uac->unit[private->uid.real_unit_addr].base_ua;
 395         uid = private->uid;
 396
 397         if (device != pos)
 398                 spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 399
 400         /* if we have no PAV anyway, we don't need to bother with PAV groups */
 401         if (lcu->pav == NO_PAV) {
 402                 list_move(&device->alias_list, &lcu->active_devices);
 403                 return 0;
 404         }
 405
 406         group = _find_group(lcu, &uid);
 407         if (!group) {
 408                 group = kzalloc(sizeof(*group), GFP_ATOMIC);
 409                 if (!group)
 410                         return -ENOMEM;
 411                 memcpy(group->uid.vendor, uid.vendor, sizeof(uid.vendor));
 412                 memcpy(group->uid.serial, uid.serial, sizeof(uid.serial));
 413                 group->uid.ssid = uid.ssid;
 414                 if (uid.type == UA_BASE_DEVICE)
 415                         group->uid.base_unit_addr = uid.real_unit_addr;
 416                 else
 417                         group->uid.base_unit_addr = uid.base_unit_addr;
 418                 memcpy(group->uid.vduit, uid.vduit, sizeof(uid.vduit));
 419                 INIT_LIST_HEAD(&group->group);
 420                 INIT_LIST_HEAD(&group->baselist);
 421                 INIT_LIST_HEAD(&group->aliaslist);
 422                 list_add(&group->group, &lcu->grouplist);
 423         }
 424         if (uid.type == UA_BASE_DEVICE)
 425                 list_move(&device->alias_list, &group->baselist);
 426         else
 427                 list_move(&device->alias_list, &group->aliaslist);
 428         private->pavgroup = group;
 429         return 0;
 430 };
 431
 432 static void _remove_device_from_lcu(struct alias_lcu *lcu,
 433                                     struct dasd_device *device)
 434 {
 435         struct dasd_eckd_private *private;
 436         struct alias_pav_group *group;
 437
 438         private = (struct dasd_eckd_private *) device->private;
 439         list_move(&device->alias_list, &lcu->inactive_devices);
 440         group = private->pavgroup;
 441         if (!group)
 442                 return;
 443         private->pavgroup = NULL;
 444         if (list_empty(&group->baselist) && list_empty(&group->aliaslist)) {
 445                 list_del(&group->group);
 446                 kfree(group);
 447                 return;
 448         }
 449         if (group->next == device)
 450                 group->next = NULL;
 451 };
 452
 453 static int read_unit_address_configuration(struct dasd_device *device,
 454                                            struct alias_lcu *lcu)
 455 {
 456         struct dasd_psf_prssd_data *prssdp;
 457         struct dasd_ccw_req *cqr;
 458         struct ccw1 *ccw;
 459         int rc;
 460         unsigned long flags;
 461
 462         cqr = dasd_kmalloc_request(DASD_ECKD_MAGIC, 1 /* PSF */ + 1 /* RSSD */,
 463                                    (sizeof(struct dasd_psf_prssd_data)),
 464                                    device);
 465         if (IS_ERR(cqr))
 466                 return PTR_ERR(cqr);
 467         cqr->startdev = device;
 468         cqr->memdev = device;
 469         clear_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
 470         cqr->retries = 10;
 471         cqr->expires = 20 * HZ;
 472
 473         /* Prepare for Read Subsystem Data */
 474         prssdp = (struct dasd_psf_prssd_data *) cqr->data;
 475         memset(prssdp, 0, sizeof(struct dasd_psf_prssd_data));
 476         prssdp->order = PSF_ORDER_PRSSD;
 477         prssdp->suborder = 0x0e;        /* Read unit address configuration */
 478         /* all other bytes of prssdp must be zero */
 479
 480         ccw = cqr->cpaddr;
 481         ccw->cmd_code = DASD_ECKD_CCW_PSF;
 482         ccw->count = sizeof(struct dasd_psf_prssd_data);
 483         ccw->flags |= CCW_FLAG_CC;
 484         ccw->cda = (__u32)(addr_t) prssdp;
 485
 486         /* Read Subsystem Data - feature codes */
 487         memset(lcu->uac, 0, sizeof(*(lcu->uac)));
 488
 489         ccw++;
 490         ccw->cmd_code = DASD_ECKD_CCW_RSSD;
 491         ccw->count = sizeof(*(lcu->uac));
 492         ccw->cda = (__u32)(addr_t) lcu->uac;
 493
 494         cqr->buildclk = get_clock();
 495         cqr->status = DASD_CQR_FILLED;
 496
 497         /* need to unset flag here to detect race with summary unit check */
 498         spin_lock_irqsave(&lcu->lock, flags);
 499         lcu->flags &= ~NEED_UAC_UPDATE;
 500         spin_unlock_irqrestore(&lcu->lock, flags);
 501
 502         do {
 503                 rc = dasd_sleep_on(cqr);
 504         } while (rc && (cqr->retries > 0));
 505         if (rc) {
 506                 spin_lock_irqsave(&lcu->lock, flags);
 507                 lcu->flags |= NEED_UAC_UPDATE;
 508                 spin_unlock_irqrestore(&lcu->lock, flags);
 509         }
 510         dasd_kfree_request(cqr, cqr->memdev);
 511         return rc;
 512 }
 513
 514 static int _lcu_update(struct dasd_device *refdev, struct alias_lcu *lcu)
 515 {
 516         unsigned long flags;
 517         struct alias_pav_group *pavgroup, *tempgroup;
 518         struct dasd_device *device, *tempdev;
 519         int i, rc;
 520         struct dasd_eckd_private *private;
 521
 522         spin_lock_irqsave(&lcu->lock, flags);
 523         list_for_each_entry_safe(pavgroup, tempgroup, &lcu->grouplist, group) {
 524                 list_for_each_entry_safe(device, tempdev, &pavgroup->baselist,
 525                                          alias_list) {
 526                         list_move(&device->alias_list, &lcu->active_devices);
 527                         private = (struct dasd_eckd_private *) device->private;
 528                         private->pavgroup = NULL;
 529                 }
 530                 list_for_each_entry_safe(device, tempdev, &pavgroup->aliaslist,
 531                                          alias_list) {
 532                         list_move(&device->alias_list, &lcu->active_devices);
 533                         private = (struct dasd_eckd_private *) device->private;
 534                         private->pavgroup = NULL;
 535                 }
 536                 list_del(&pavgroup->group);
 537                 kfree(pavgroup);
 538         }
 539         spin_unlock_irqrestore(&lcu->lock, flags);
 540
 541         rc = read_unit_address_configuration(refdev, lcu);
 542         if (rc)
 543                 return rc;
 544
 545         /* need to take cdev lock before lcu lock */
 546         spin_lock_irqsave_nested(get_ccwdev_lock(refdev->cdev), flags,
 547                                  CDEV_NESTED_FIRST);
 548         spin_lock(&lcu->lock);
 549         lcu->pav = NO_PAV;
 550         for (i = 0; i < MAX_DEVICES_PER_LCU; ++i) {
 551                 switch (lcu->uac->unit[i].ua_type) {
 552                 case UA_BASE_PAV_ALIAS:
 553                         lcu->pav = BASE_PAV;
 554                         break;
 555                 case UA_HYPER_PAV_ALIAS:
 556                         lcu->pav = HYPER_PAV;
 557                         break;
 558                 }
 559                 if (lcu->pav != NO_PAV)
 560                         break;
 561         }
 562
 563         list_for_each_entry_safe(device, tempdev, &lcu->active_devices,
 564                                  alias_list) {
 565                 _add_device_to_lcu(lcu, device, refdev);
 566         }
 567         spin_unlock(&lcu->lock);
 568         spin_unlock_irqrestore(get_ccwdev_lock(refdev->cdev), flags);
 569         return 0;
 570 }
 571
 572 static void lcu_update_work(struct work_struct *work)
 573 {
 574         struct alias_lcu *lcu;
 575         struct read_uac_work_data *ruac_data;
 576         struct dasd_device *device;
 577         unsigned long flags;
 578         int rc;
 579
 580         ruac_data = container_of(work, struct read_uac_work_data, dwork.work);
 581         lcu = container_of(ruac_data, struct alias_lcu, ruac_data);
 582         device = ruac_data->device;
 583         rc = _lcu_update(device, lcu);
 584         /*
 585          * Need to check flags again, as there could have been another
 586          * prepare_update or a new device a new device while we were still
 587          * processing the data
 588          */
 589         spin_lock_irqsave(&lcu->lock, flags);
 590         if (rc || (lcu->flags & NEED_UAC_UPDATE)) {
 591                 DBF_DEV_EVENT(DBF_WARNING, device, "could not update"
 592                             " alias data in lcu (rc = %d), retry later", rc);
 593                 schedule_delayed_work(&lcu->ruac_data.dwork, 30*HZ);
 594         } else {
 595                 lcu->ruac_data.device = NULL;
 596                 lcu->flags &= ~UPDATE_PENDING;
 597         }
 598         spin_unlock_irqrestore(&lcu->lock, flags);
 599 }
 600
 601 static int _schedule_lcu_update(struct alias_lcu *lcu,
 602                                 struct dasd_device *device)
 603 {
 604         struct dasd_device *usedev = NULL;
 605         struct alias_pav_group *group;
 606
 607         lcu->flags |= NEED_UAC_UPDATE;
 608         if (lcu->ruac_data.device) {
 609                 /* already scheduled or running */
 610                 return 0;
 611         }
 612         if (device && !list_empty(&device->alias_list))
 613                 usedev = device;
 614
 615         if (!usedev && !list_empty(&lcu->grouplist)) {
 616                 group = list_first_entry(&lcu->grouplist,
 617                                          struct alias_pav_group, group);
 618                 if (!list_empty(&group->baselist))
 619                         usedev = list_first_entry(&group->baselist,
 620                                                   struct dasd_device,
 621                                                   alias_list);
 622                 else if (!list_empty(&group->aliaslist))
 623                         usedev = list_first_entry(&group->aliaslist,
 624                                                   struct dasd_device,
 625                                                   alias_list);
 626         }
 627         if (!usedev && !list_empty(&lcu->active_devices)) {
 628                 usedev = list_first_entry(&lcu->active_devices,
 629                                           struct dasd_device, alias_list);
 630         }
 631         /*
 632          * if we haven't found a proper device yet, give up for now, the next
 633          * device that will be set active will trigger an lcu update
 634          */
 635         if (!usedev)
 636                 return -EINVAL;
 637         lcu->ruac_data.device = usedev;
 638         schedule_delayed_work(&lcu->ruac_data.dwork, 0);
 639         return 0;
 640 }
 641
 642 int dasd_alias_add_device(struct dasd_device *device)
 643 {
 644         struct dasd_eckd_private *private;
 645         struct alias_lcu *lcu;
 646         unsigned long flags;
 647         int rc;
 648
 649         private = (struct dasd_eckd_private *) device->private;
 650         lcu = private->lcu;
 651         rc = 0;
 652
 653         /* need to take cdev lock before lcu lock */
 654         spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 655         spin_lock(&lcu->lock);
 656         if (!(lcu->flags & UPDATE_PENDING)) {
 657                 rc = _add_device_to_lcu(lcu, device, device);
 658                 if (rc)
 659                         lcu->flags |= UPDATE_PENDING;
 660         }
 661         if (lcu->flags & UPDATE_PENDING) {
 662                 list_move(&device->alias_list, &lcu->active_devices);
 663                 _schedule_lcu_update(lcu, device);
 664         }
 665         spin_unlock(&lcu->lock);
 666         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 667         return rc;
 668 }
 669
 670 int dasd_alias_update_add_device(struct dasd_device *device)
 671 {
 672         struct dasd_eckd_private *private;
 673         private = (struct dasd_eckd_private *) device->private;
 674         private->lcu->flags |= UPDATE_PENDING;
 675         return dasd_alias_add_device(device);
 676 }
 677
 678 int dasd_alias_remove_device(struct dasd_device *device)
 679 {
 680         struct dasd_eckd_private *private;
 681         struct alias_lcu *lcu;
 682         unsigned long flags;
 683
 684         private = (struct dasd_eckd_private *) device->private;
 685         lcu = private->lcu;
 686         /* nothing to do if already removed */
 687         if (!lcu)
 688                 return 0;
 689         spin_lock_irqsave(&lcu->lock, flags);
 690         _remove_device_from_lcu(lcu, device);
 691         spin_unlock_irqrestore(&lcu->lock, flags);
 692         return 0;
 693 }
 694
 695 struct dasd_device *dasd_alias_get_start_dev(struct dasd_device *base_device)
 696 {
 697
 698         struct dasd_device *alias_device;
 699         struct alias_pav_group *group;
 700         struct alias_lcu *lcu;
 701         struct dasd_eckd_private *private, *alias_priv;
 702         unsigned long flags;
 703
 704         private = (struct dasd_eckd_private *) base_device->private;
 705         group = private->pavgroup;
 706         lcu = private->lcu;
 707         if (!group || !lcu)
 708                 return NULL;
 709         if (lcu->pav == NO_PAV ||
 710             lcu->flags & (NEED_UAC_UPDATE | UPDATE_PENDING))
 711                 return NULL;
 712
 713         spin_lock_irqsave(&lcu->lock, flags);
 714         alias_device = group->next;
 715         if (!alias_device) {
 716                 if (list_empty(&group->aliaslist)) {
 717                         spin_unlock_irqrestore(&lcu->lock, flags);
 718                         return NULL;
 719                 } else {
 720                         alias_device = list_first_entry(&group->aliaslist,
 721                                                         struct dasd_device,
 722                                                         alias_list);
 723                 }
 724         }
 725         if (list_is_last(&alias_device->alias_list, &group->aliaslist))
 726                 group->next = list_first_entry(&group->aliaslist,
 727                                                struct dasd_device, alias_list);
 728         else
 729                 group->next = list_first_entry(&alias_device->alias_list,
 730                                                struct dasd_device, alias_list);
 731         spin_unlock_irqrestore(&lcu->lock, flags);
 732         alias_priv = (struct dasd_eckd_private *) alias_device->private;
 733         if ((alias_priv->count < private->count) && !alias_device->stopped)
 734                 return alias_device;
 735         else
 736                 return NULL;
 737 }
 738
 739 /*
 740  * Summary unit check handling depends on the way alias devices
 741  * are handled so it is done here rather then in dasd_eckd.c
 742  */
 743 static int reset_summary_unit_check(struct alias_lcu *lcu,
 744                                     struct dasd_device *device,
 745                                     char reason)
 746 {
 747         struct dasd_ccw_req *cqr;
 748         int rc = 0;
 749         struct ccw1 *ccw;
 750
 751         cqr = lcu->rsu_cqr;
 752         strncpy((char *) &cqr->magic, "ECKD", 4);
 753         ASCEBC((char *) &cqr->magic, 4);
 754         ccw = cqr->cpaddr;
 755         ccw->cmd_code = DASD_ECKD_CCW_RSCK;
 756         ccw->flags = 0 ;
 757         ccw->count = 16;
 758         ccw->cda = (__u32)(addr_t) cqr->data;
 759         ((char *)cqr->data)[0] = reason;
 760
 761         clear_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
 762         cqr->retries = 255;     /* set retry counter to enable basic ERP */
 763         cqr->startdev = device;
 764         cqr->memdev = device;
 765         cqr->block = NULL;
 766         cqr->expires = 5 * HZ;
 767         cqr->buildclk = get_clock();
 768         cqr->status = DASD_CQR_FILLED;
 769
 770         rc = dasd_sleep_on_immediatly(cqr);
 771         return rc;
 772 }
 773
 774 static void _restart_all_base_devices_on_lcu(struct alias_lcu *lcu)
 775 {
 776         struct alias_pav_group *pavgroup;
 777         struct dasd_device *device;
 778         struct dasd_eckd_private *private;
 779         unsigned long flags;
 780
 781         /* active and inactive list can contain alias as well as base devices */
 782         list_for_each_entry(device, &lcu->active_devices, alias_list) {
 783                 private = (struct dasd_eckd_private *) device->private;
 784                 spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 785                 if (private->uid.type != UA_BASE_DEVICE) {
 786                         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev),
 787                                                flags);
 788                         continue;
 789                 }
 790                 spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 791                 dasd_schedule_block_bh(device->block);
 792                 dasd_schedule_device_bh(device);
 793         }
 794         list_for_each_entry(device, &lcu->inactive_devices, alias_list) {
 795                 private = (struct dasd_eckd_private *) device->private;
 796                 spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 797                 if (private->uid.type != UA_BASE_DEVICE) {
 798                         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev),
 799                                                flags);
 800                         continue;
 801                 }
 802                 spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 803                 dasd_schedule_block_bh(device->block);
 804                 dasd_schedule_device_bh(device);
 805         }
 806         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 807                 list_for_each_entry(device, &pavgroup->baselist, alias_list) {
 808                         dasd_schedule_block_bh(device->block);
 809                         dasd_schedule_device_bh(device);
 810                 }
 811         }
 812 }
 813
 814 static void flush_all_alias_devices_on_lcu(struct alias_lcu *lcu)
 815 {
 816         struct alias_pav_group *pavgroup;
 817         struct dasd_device *device, *temp;
 818         struct dasd_eckd_private *private;
 819         int rc;
 820         unsigned long flags;
 821         LIST_HEAD(active);
 822
 823         /*
 824          * Problem here ist that dasd_flush_device_queue may wait
 825          * for termination of a request to complete. We can't keep
 826          * the lcu lock during that time, so we must assume that
 827          * the lists may have changed.
 828          * Idea: first gather all active alias devices in a separate list,
 829          * then flush the first element of this list unlocked, and afterwards
 830          * check if it is still on the list before moving it to the
 831          * active_devices list.
 832          */
 833
 834         spin_lock_irqsave(&lcu->lock, flags);
 835         list_for_each_entry_safe(device, temp, &lcu->active_devices,
 836                                  alias_list) {
 837                 private = (struct dasd_eckd_private *) device->private;
 838                 if (private->uid.type == UA_BASE_DEVICE)
 839                         continue;
 840                 list_move(&device->alias_list, &active);
 841         }
 842
 843         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 844                 list_splice_init(&pavgroup->aliaslist, &active);
 845         }
 846         while (!list_empty(&active)) {
 847                 device = list_first_entry(&active, struct dasd_device,
 848                                           alias_list);
 849                 spin_unlock_irqrestore(&lcu->lock, flags);
 850                 rc = dasd_flush_device_queue(device);
 851                 spin_lock_irqsave(&lcu->lock, flags);
 852                 /*
 853                  * only move device around if it wasn't moved away while we
 854                  * were waiting for the flush
 855                  */
 856                 if (device == list_first_entry(&active,
 857                                                struct dasd_device, alias_list))
 858                         list_move(&device->alias_list, &lcu->active_devices);
 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         spin_unlock_irqrestore(&lcu->lock, flags);
 961 }
 962
 963 /*
 964  * note: this will be called from int handler context (cdev locked)
 965  */
 966 void dasd_alias_handle_summary_unit_check(struct dasd_device *device,
 967                                           struct irb *irb)
 968 {
 969         struct alias_lcu *lcu;
 970         char reason;
 971         struct dasd_eckd_private *private;
 972         char *sense;
 973
 974         private = (struct dasd_eckd_private *) device->private;
 975
 976         sense = dasd_get_sense(irb);
 977         if (sense) {
 978                 reason = sense[8];
 979                 DBF_DEV_EVENT(DBF_NOTICE, device, "%s %x",
 980                             "eckd handle summary unit check: reason", reason);
 981         } else {
 982                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
 983                             "eckd handle summary unit check:"
 984                             " no reason code available");
 985                 return;
 986         }
 987
 988         lcu = private->lcu;
 989         if (!lcu) {
 990                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
 991                             "device not ready to handle summary"
 992                             " unit check (no lcu structure)");
 993                 return;
 994         }
 995         spin_lock(&lcu->lock);
 996         _stop_all_devices_on_lcu(lcu, device);
 997         /* prepare for lcu_update */
 998         private->lcu->flags |= NEED_UAC_UPDATE | UPDATE_PENDING;
 999         /* If this device is about to be removed just return and wait for
1000          * the next interrupt on a different device
1001          */
1002         if (list_empty(&device->alias_list)) {
1003                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
1004                             "device is in offline processing,"
1005                             " don't do summary unit check handling");
1006                 spin_unlock(&lcu->lock);
1007                 return;
1008         }
1009         if (lcu->suc_data.device) {
1010                 /* already scheduled or running */
1011                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
1012                             "previous instance of summary unit check worker"
1013                             " still pending");
1014                 spin_unlock(&lcu->lock);
1015                 return ;
1016         }
1017         lcu->suc_data.reason = reason;
1018         lcu->suc_data.device = device;
1019         spin_unlock(&lcu->lock);
1020         schedule_work(&lcu->suc_data.worker);
1021 };