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         list_del_init(&device->alias_list);
 262         /* make sure that the workers don't use this device */
 263         if (device == lcu->suc_data.device) {
 264                 spin_unlock_irqrestore(&lcu->lock, flags);
 265                 cancel_work_sync(&lcu->suc_data.worker);
 266                 spin_lock_irqsave(&lcu->lock, flags);
 267                 if (device == lcu->suc_data.device) {
 268                         dasd_put_device(device);
 269                         lcu->suc_data.device = NULL;
 270                 }
 271         }
 272         was_pending = 0;
 273         if (device == lcu->ruac_data.device) {
 274                 spin_unlock_irqrestore(&lcu->lock, flags);
 275                 was_pending = 1;
 276                 cancel_delayed_work_sync(&lcu->ruac_data.dwork);
 277                 spin_lock_irqsave(&lcu->lock, flags);
 278                 if (device == lcu->ruac_data.device) {
 279                         dasd_put_device(device);
 280                         lcu->ruac_data.device = NULL;
 281                 }
 282         }
 283         private->lcu = NULL;
 284         spin_unlock_irqrestore(&lcu->lock, flags);
 285
 286         spin_lock_irqsave(&aliastree.lock, flags);
 287         spin_lock(&lcu->lock);
 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         sense = dasd_get_sense(&cqr->irb);
 400         if (!sense)
 401                 return 0;
 402
 403         reason = sense[0];
 404         msg_format = (sense[7] & 0xF0);
 405         msg_no = (sense[7] & 0x0F);
 406
 407         /* command reject, Format 0 MSG 4 - invalid parameter */
 408         if ((reason == 0x80) && (msg_format == 0x00) && (msg_no == 0x04))
 409                 return 1;
 410
 411         return 0;
 412 }
 413
 414 static int read_unit_address_configuration(struct dasd_device *device,
 415                                            struct alias_lcu *lcu)
 416 {
 417         struct dasd_psf_prssd_data *prssdp;
 418         struct dasd_ccw_req *cqr;
 419         struct ccw1 *ccw;
 420         int rc;
 421         unsigned long flags;
 422
 423         cqr = dasd_kmalloc_request(DASD_ECKD_MAGIC, 1 /* PSF */ + 1 /* RSSD */,
 424                                    (sizeof(struct dasd_psf_prssd_data)),
 425                                    device);
 426         if (IS_ERR(cqr))
 427                 return PTR_ERR(cqr);
 428         cqr->startdev = device;
 429         cqr->memdev = device;
 430         clear_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
 431         cqr->retries = 10;
 432         cqr->expires = 20 * HZ;
 433
 434         /* Prepare for Read Subsystem Data */
 435         prssdp = (struct dasd_psf_prssd_data *) cqr->data;
 436         memset(prssdp, 0, sizeof(struct dasd_psf_prssd_data));
 437         prssdp->order = PSF_ORDER_PRSSD;
 438         prssdp->suborder = 0x0e;        /* Read unit address configuration */
 439         /* all other bytes of prssdp must be zero */
 440
 441         ccw = cqr->cpaddr;
 442         ccw->cmd_code = DASD_ECKD_CCW_PSF;
 443         ccw->count = sizeof(struct dasd_psf_prssd_data);
 444         ccw->flags |= CCW_FLAG_CC;
 445         ccw->cda = (__u32)(addr_t) prssdp;
 446
 447         /* Read Subsystem Data - feature codes */
 448         memset(lcu->uac, 0, sizeof(*(lcu->uac)));
 449
 450         ccw++;
 451         ccw->cmd_code = DASD_ECKD_CCW_RSSD;
 452         ccw->count = sizeof(*(lcu->uac));
 453         ccw->cda = (__u32)(addr_t) lcu->uac;
 454
 455         cqr->buildclk = get_tod_clock();
 456         cqr->status = DASD_CQR_FILLED;
 457
 458         /* need to unset flag here to detect race with summary unit check */
 459         spin_lock_irqsave(&lcu->lock, flags);
 460         lcu->flags &= ~NEED_UAC_UPDATE;
 461         spin_unlock_irqrestore(&lcu->lock, flags);
 462
 463         do {
 464                 rc = dasd_sleep_on(cqr);
 465                 if (rc && suborder_not_supported(cqr))
 466                         return -EOPNOTSUPP;
 467         } while (rc && (cqr->retries > 0));
 468         if (rc) {
 469                 spin_lock_irqsave(&lcu->lock, flags);
 470                 lcu->flags |= NEED_UAC_UPDATE;
 471                 spin_unlock_irqrestore(&lcu->lock, flags);
 472         }
 473         dasd_kfree_request(cqr, cqr->memdev);
 474         return rc;
 475 }
 476
 477 static int _lcu_update(struct dasd_device *refdev, struct alias_lcu *lcu)
 478 {
 479         unsigned long flags;
 480         struct alias_pav_group *pavgroup, *tempgroup;
 481         struct dasd_device *device, *tempdev;
 482         int i, rc;
 483         struct dasd_eckd_private *private;
 484
 485         spin_lock_irqsave(&lcu->lock, flags);
 486         list_for_each_entry_safe(pavgroup, tempgroup, &lcu->grouplist, group) {
 487                 list_for_each_entry_safe(device, tempdev, &pavgroup->baselist,
 488                                          alias_list) {
 489                         list_move(&device->alias_list, &lcu->active_devices);
 490                         private = (struct dasd_eckd_private *) device->private;
 491                         private->pavgroup = NULL;
 492                 }
 493                 list_for_each_entry_safe(device, tempdev, &pavgroup->aliaslist,
 494                                          alias_list) {
 495                         list_move(&device->alias_list, &lcu->active_devices);
 496                         private = (struct dasd_eckd_private *) device->private;
 497                         private->pavgroup = NULL;
 498                 }
 499                 list_del(&pavgroup->group);
 500                 kfree(pavgroup);
 501         }
 502         spin_unlock_irqrestore(&lcu->lock, flags);
 503
 504         rc = read_unit_address_configuration(refdev, lcu);
 505         if (rc)
 506                 return rc;
 507
 508         /* need to take cdev lock before lcu lock */
 509         spin_lock_irqsave_nested(get_ccwdev_lock(refdev->cdev), flags,
 510                                  CDEV_NESTED_FIRST);
 511         spin_lock(&lcu->lock);
 512         lcu->pav = NO_PAV;
 513         for (i = 0; i < MAX_DEVICES_PER_LCU; ++i) {
 514                 switch (lcu->uac->unit[i].ua_type) {
 515                 case UA_BASE_PAV_ALIAS:
 516                         lcu->pav = BASE_PAV;
 517                         break;
 518                 case UA_HYPER_PAV_ALIAS:
 519                         lcu->pav = HYPER_PAV;
 520                         break;
 521                 }
 522                 if (lcu->pav != NO_PAV)
 523                         break;
 524         }
 525
 526         list_for_each_entry_safe(device, tempdev, &lcu->active_devices,
 527                                  alias_list) {
 528                 _add_device_to_lcu(lcu, device, refdev);
 529         }
 530         spin_unlock(&lcu->lock);
 531         spin_unlock_irqrestore(get_ccwdev_lock(refdev->cdev), flags);
 532         return 0;
 533 }
 534
 535 static void lcu_update_work(struct work_struct *work)
 536 {
 537         struct alias_lcu *lcu;
 538         struct read_uac_work_data *ruac_data;
 539         struct dasd_device *device;
 540         unsigned long flags;
 541         int rc;
 542
 543         ruac_data = container_of(work, struct read_uac_work_data, dwork.work);
 544         lcu = container_of(ruac_data, struct alias_lcu, ruac_data);
 545         device = ruac_data->device;
 546         rc = _lcu_update(device, lcu);
 547         /*
 548          * Need to check flags again, as there could have been another
 549          * prepare_update or a new device a new device while we were still
 550          * processing the data
 551          */
 552         spin_lock_irqsave(&lcu->lock, flags);
 553         if ((rc && (rc != -EOPNOTSUPP)) || (lcu->flags & NEED_UAC_UPDATE)) {
 554                 DBF_DEV_EVENT(DBF_WARNING, device, "could not update"
 555                             " alias data in lcu (rc = %d), retry later", rc);
 556                 if (!schedule_delayed_work(&lcu->ruac_data.dwork, 30*HZ))
 557                         dasd_put_device(device);
 558         } else {
 559                 dasd_put_device(device);
 560                 lcu->ruac_data.device = NULL;
 561                 lcu->flags &= ~UPDATE_PENDING;
 562         }
 563         spin_unlock_irqrestore(&lcu->lock, flags);
 564 }
 565
 566 static int _schedule_lcu_update(struct alias_lcu *lcu,
 567                                 struct dasd_device *device)
 568 {
 569         struct dasd_device *usedev = NULL;
 570         struct alias_pav_group *group;
 571
 572         lcu->flags |= NEED_UAC_UPDATE;
 573         if (lcu->ruac_data.device) {
 574                 /* already scheduled or running */
 575                 return 0;
 576         }
 577         if (device && !list_empty(&device->alias_list))
 578                 usedev = device;
 579
 580         if (!usedev && !list_empty(&lcu->grouplist)) {
 581                 group = list_first_entry(&lcu->grouplist,
 582                                          struct alias_pav_group, group);
 583                 if (!list_empty(&group->baselist))
 584                         usedev = list_first_entry(&group->baselist,
 585                                                   struct dasd_device,
 586                                                   alias_list);
 587                 else if (!list_empty(&group->aliaslist))
 588                         usedev = list_first_entry(&group->aliaslist,
 589                                                   struct dasd_device,
 590                                                   alias_list);
 591         }
 592         if (!usedev && !list_empty(&lcu->active_devices)) {
 593                 usedev = list_first_entry(&lcu->active_devices,
 594                                           struct dasd_device, alias_list);
 595         }
 596         /*
 597          * if we haven't found a proper device yet, give up for now, the next
 598          * device that will be set active will trigger an lcu update
 599          */
 600         if (!usedev)
 601                 return -EINVAL;
 602         dasd_get_device(usedev);
 603         lcu->ruac_data.device = usedev;
 604         if (!schedule_delayed_work(&lcu->ruac_data.dwork, 0))
 605                 dasd_put_device(usedev);
 606         return 0;
 607 }
 608
 609 int dasd_alias_add_device(struct dasd_device *device)
 610 {
 611         struct dasd_eckd_private *private;
 612         struct alias_lcu *lcu;
 613         unsigned long flags;
 614         int rc;
 615
 616         private = (struct dasd_eckd_private *) device->private;
 617         lcu = private->lcu;
 618         rc = 0;
 619
 620         /* need to take cdev lock before lcu lock */
 621         spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 622         spin_lock(&lcu->lock);
 623         if (!(lcu->flags & UPDATE_PENDING)) {
 624                 rc = _add_device_to_lcu(lcu, device, device);
 625                 if (rc)
 626                         lcu->flags |= UPDATE_PENDING;
 627         }
 628         if (lcu->flags & UPDATE_PENDING) {
 629                 list_move(&device->alias_list, &lcu->active_devices);
 630                 _schedule_lcu_update(lcu, device);
 631         }
 632         spin_unlock(&lcu->lock);
 633         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 634         return rc;
 635 }
 636
 637 int dasd_alias_update_add_device(struct dasd_device *device)
 638 {
 639         struct dasd_eckd_private *private;
 640         private = (struct dasd_eckd_private *) device->private;
 641         private->lcu->flags |= UPDATE_PENDING;
 642         return dasd_alias_add_device(device);
 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         /* nothing to do if already removed */
 654         if (!lcu)
 655                 return 0;
 656         spin_lock_irqsave(&lcu->lock, flags);
 657         _remove_device_from_lcu(lcu, device);
 658         spin_unlock_irqrestore(&lcu->lock, flags);
 659         return 0;
 660 }
 661
 662 struct dasd_device *dasd_alias_get_start_dev(struct dasd_device *base_device)
 663 {
 664
 665         struct dasd_device *alias_device;
 666         struct alias_pav_group *group;
 667         struct alias_lcu *lcu;
 668         struct dasd_eckd_private *private, *alias_priv;
 669         unsigned long flags;
 670
 671         private = (struct dasd_eckd_private *) base_device->private;
 672         group = private->pavgroup;
 673         lcu = private->lcu;
 674         if (!group || !lcu)
 675                 return NULL;
 676         if (lcu->pav == NO_PAV ||
 677             lcu->flags & (NEED_UAC_UPDATE | UPDATE_PENDING))
 678                 return NULL;
 679         if (unlikely(!(private->features.feature[8] & 0x01))) {
 680                 /*
 681                  * PAV enabled but prefix not, very unlikely
 682                  * seems to be a lost pathgroup
 683                  * use base device to do IO
 684                  */
 685                 DBF_DEV_EVENT(DBF_ERR, base_device, "%s",
 686                               "Prefix not enabled with PAV enabled\n");
 687                 return NULL;
 688         }
 689
 690         spin_lock_irqsave(&lcu->lock, flags);
 691         alias_device = group->next;
 692         if (!alias_device) {
 693                 if (list_empty(&group->aliaslist)) {
 694                         spin_unlock_irqrestore(&lcu->lock, flags);
 695                         return NULL;
 696                 } else {
 697                         alias_device = list_first_entry(&group->aliaslist,
 698                                                         struct dasd_device,
 699                                                         alias_list);
 700                 }
 701         }
 702         if (list_is_last(&alias_device->alias_list, &group->aliaslist))
 703                 group->next = list_first_entry(&group->aliaslist,
 704                                                struct dasd_device, alias_list);
 705         else
 706                 group->next = list_first_entry(&alias_device->alias_list,
 707                                                struct dasd_device, alias_list);
 708         spin_unlock_irqrestore(&lcu->lock, flags);
 709         alias_priv = (struct dasd_eckd_private *) alias_device->private;
 710         if ((alias_priv->count < private->count) && !alias_device->stopped)
 711                 return alias_device;
 712         else
 713                 return NULL;
 714 }
 715
 716 /*
 717  * Summary unit check handling depends on the way alias devices
 718  * are handled so it is done here rather then in dasd_eckd.c
 719  */
 720 static int reset_summary_unit_check(struct alias_lcu *lcu,
 721                                     struct dasd_device *device,
 722                                     char reason)
 723 {
 724         struct dasd_ccw_req *cqr;
 725         int rc = 0;
 726         struct ccw1 *ccw;
 727
 728         cqr = lcu->rsu_cqr;
 729         strncpy((char *) &cqr->magic, "ECKD", 4);
 730         ASCEBC((char *) &cqr->magic, 4);
 731         ccw = cqr->cpaddr;
 732         ccw->cmd_code = DASD_ECKD_CCW_RSCK;
 733         ccw->flags = CCW_FLAG_SLI;
 734         ccw->count = 16;
 735         ccw->cda = (__u32)(addr_t) cqr->data;
 736         ((char *)cqr->data)[0] = reason;
 737
 738         clear_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
 739         cqr->retries = 255;     /* set retry counter to enable basic ERP */
 740         cqr->startdev = device;
 741         cqr->memdev = device;
 742         cqr->block = NULL;
 743         cqr->expires = 5 * HZ;
 744         cqr->buildclk = get_tod_clock();
 745         cqr->status = DASD_CQR_FILLED;
 746
 747         rc = dasd_sleep_on_immediatly(cqr);
 748         return rc;
 749 }
 750
 751 static void _restart_all_base_devices_on_lcu(struct alias_lcu *lcu)
 752 {
 753         struct alias_pav_group *pavgroup;
 754         struct dasd_device *device;
 755         struct dasd_eckd_private *private;
 756         unsigned long flags;
 757
 758         /* active and inactive list can contain alias as well as base devices */
 759         list_for_each_entry(device, &lcu->active_devices, alias_list) {
 760                 private = (struct dasd_eckd_private *) device->private;
 761                 spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 762                 if (private->uid.type != UA_BASE_DEVICE) {
 763                         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev),
 764                                                flags);
 765                         continue;
 766                 }
 767                 spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 768                 dasd_schedule_block_bh(device->block);
 769                 dasd_schedule_device_bh(device);
 770         }
 771         list_for_each_entry(device, &lcu->inactive_devices, alias_list) {
 772                 private = (struct dasd_eckd_private *) device->private;
 773                 spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 774                 if (private->uid.type != UA_BASE_DEVICE) {
 775                         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev),
 776                                                flags);
 777                         continue;
 778                 }
 779                 spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 780                 dasd_schedule_block_bh(device->block);
 781                 dasd_schedule_device_bh(device);
 782         }
 783         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 784                 list_for_each_entry(device, &pavgroup->baselist, alias_list) {
 785                         dasd_schedule_block_bh(device->block);
 786                         dasd_schedule_device_bh(device);
 787                 }
 788         }
 789 }
 790
 791 static void flush_all_alias_devices_on_lcu(struct alias_lcu *lcu)
 792 {
 793         struct alias_pav_group *pavgroup;
 794         struct dasd_device *device, *temp;
 795         struct dasd_eckd_private *private;
 796         int rc;
 797         unsigned long flags;
 798         LIST_HEAD(active);
 799
 800         /*
 801          * Problem here ist that dasd_flush_device_queue may wait
 802          * for termination of a request to complete. We can't keep
 803          * the lcu lock during that time, so we must assume that
 804          * the lists may have changed.
 805          * Idea: first gather all active alias devices in a separate list,
 806          * then flush the first element of this list unlocked, and afterwards
 807          * check if it is still on the list before moving it to the
 808          * active_devices list.
 809          */
 810
 811         spin_lock_irqsave(&lcu->lock, flags);
 812         list_for_each_entry_safe(device, temp, &lcu->active_devices,
 813                                  alias_list) {
 814                 private = (struct dasd_eckd_private *) device->private;
 815                 if (private->uid.type == UA_BASE_DEVICE)
 816                         continue;
 817                 list_move(&device->alias_list, &active);
 818         }
 819
 820         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 821                 list_splice_init(&pavgroup->aliaslist, &active);
 822         }
 823         while (!list_empty(&active)) {
 824                 device = list_first_entry(&active, struct dasd_device,
 825                                           alias_list);
 826                 spin_unlock_irqrestore(&lcu->lock, flags);
 827                 rc = dasd_flush_device_queue(device);
 828                 spin_lock_irqsave(&lcu->lock, flags);
 829                 /*
 830                  * only move device around if it wasn't moved away while we
 831                  * were waiting for the flush
 832                  */
 833                 if (device == list_first_entry(&active,
 834                                                struct dasd_device, alias_list))
 835                         list_move(&device->alias_list, &lcu->active_devices);
 836         }
 837         spin_unlock_irqrestore(&lcu->lock, flags);
 838 }
 839
 840 static void __stop_device_on_lcu(struct dasd_device *device,
 841                                  struct dasd_device *pos)
 842 {
 843         /* If pos == device then device is already locked! */
 844         if (pos == device) {
 845                 dasd_device_set_stop_bits(pos, DASD_STOPPED_SU);
 846                 return;
 847         }
 848         spin_lock(get_ccwdev_lock(pos->cdev));
 849         dasd_device_set_stop_bits(pos, DASD_STOPPED_SU);
 850         spin_unlock(get_ccwdev_lock(pos->cdev));
 851 }
 852
 853 /*
 854  * This function is called in interrupt context, so the
 855  * cdev lock for device is already locked!
 856  */
 857 static void _stop_all_devices_on_lcu(struct alias_lcu *lcu,
 858                                      struct dasd_device *device)
 859 {
 860         struct alias_pav_group *pavgroup;
 861         struct dasd_device *pos;
 862
 863         list_for_each_entry(pos, &lcu->active_devices, alias_list)
 864                 __stop_device_on_lcu(device, pos);
 865         list_for_each_entry(pos, &lcu->inactive_devices, alias_list)
 866                 __stop_device_on_lcu(device, pos);
 867         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 868                 list_for_each_entry(pos, &pavgroup->baselist, alias_list)
 869                         __stop_device_on_lcu(device, pos);
 870                 list_for_each_entry(pos, &pavgroup->aliaslist, alias_list)
 871                         __stop_device_on_lcu(device, pos);
 872         }
 873 }
 874
 875 static void _unstop_all_devices_on_lcu(struct alias_lcu *lcu)
 876 {
 877         struct alias_pav_group *pavgroup;
 878         struct dasd_device *device;
 879         unsigned long flags;
 880
 881         list_for_each_entry(device, &lcu->active_devices, alias_list) {
 882                 spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 883                 dasd_device_remove_stop_bits(device, DASD_STOPPED_SU);
 884                 spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 885         }
 886
 887         list_for_each_entry(device, &lcu->inactive_devices, alias_list) {
 888                 spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 889                 dasd_device_remove_stop_bits(device, DASD_STOPPED_SU);
 890                 spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 891         }
 892
 893         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 894                 list_for_each_entry(device, &pavgroup->baselist, alias_list) {
 895                         spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 896                         dasd_device_remove_stop_bits(device, DASD_STOPPED_SU);
 897                         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev),
 898                                                flags);
 899                 }
 900                 list_for_each_entry(device, &pavgroup->aliaslist, alias_list) {
 901                         spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 902                         dasd_device_remove_stop_bits(device, DASD_STOPPED_SU);
 903                         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev),
 904                                                flags);
 905                 }
 906         }
 907 }
 908
 909 static void summary_unit_check_handling_work(struct work_struct *work)
 910 {
 911         struct alias_lcu *lcu;
 912         struct summary_unit_check_work_data *suc_data;
 913         unsigned long flags;
 914         struct dasd_device *device;
 915
 916         suc_data = container_of(work, struct summary_unit_check_work_data,
 917                                 worker);
 918         lcu = container_of(suc_data, struct alias_lcu, suc_data);
 919         device = suc_data->device;
 920
 921         /* 1. flush alias devices */
 922         flush_all_alias_devices_on_lcu(lcu);
 923
 924         /* 2. reset summary unit check */
 925         spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 926         dasd_device_remove_stop_bits(device,
 927                                      (DASD_STOPPED_SU | DASD_STOPPED_PENDING));
 928         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 929         reset_summary_unit_check(lcu, device, suc_data->reason);
 930
 931         spin_lock_irqsave(&lcu->lock, flags);
 932         _unstop_all_devices_on_lcu(lcu);
 933         _restart_all_base_devices_on_lcu(lcu);
 934         /* 3. read new alias configuration */
 935         _schedule_lcu_update(lcu, device);
 936         lcu->suc_data.device = NULL;
 937         dasd_put_device(device);
 938         spin_unlock_irqrestore(&lcu->lock, flags);
 939 }
 940
 941 /*
 942  * note: this will be called from int handler context (cdev locked)
 943  */
 944 void dasd_alias_handle_summary_unit_check(struct dasd_device *device,
 945                                           struct irb *irb)
 946 {
 947         struct alias_lcu *lcu;
 948         char reason;
 949         struct dasd_eckd_private *private;
 950         char *sense;
 951
 952         private = (struct dasd_eckd_private *) device->private;
 953
 954         sense = dasd_get_sense(irb);
 955         if (sense) {
 956                 reason = sense[8];
 957                 DBF_DEV_EVENT(DBF_NOTICE, device, "%s %x",
 958                             "eckd handle summary unit check: reason", reason);
 959         } else {
 960                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
 961                             "eckd handle summary unit check:"
 962                             " no reason code available");
 963                 return;
 964         }
 965
 966         lcu = private->lcu;
 967         if (!lcu) {
 968                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
 969                             "device not ready to handle summary"
 970                             " unit check (no lcu structure)");
 971                 return;
 972         }
 973         spin_lock(&lcu->lock);
 974         _stop_all_devices_on_lcu(lcu, device);
 975         /* prepare for lcu_update */
 976         private->lcu->flags |= NEED_UAC_UPDATE | UPDATE_PENDING;
 977         /* If this device is about to be removed just return and wait for
 978          * the next interrupt on a different device
 979          */
 980         if (list_empty(&device->alias_list)) {
 981                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
 982                             "device is in offline processing,"
 983                             " don't do summary unit check handling");
 984                 spin_unlock(&lcu->lock);
 985                 return;
 986         }
 987         if (lcu->suc_data.device) {
 988                 /* already scheduled or running */
 989                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
 990                             "previous instance of summary unit check worker"
 991                             " still pending");
 992                 spin_unlock(&lcu->lock);
 993                 return ;
 994         }
 995         lcu->suc_data.reason = reason;
 996         lcu->suc_data.device = device;
 997         dasd_get_device(device);
 998         spin_unlock(&lcu->lock);
 999         if (!schedule_work(&lcu->suc_data.worker))
1000                 dasd_put_device(device);
1001 };