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 <asm/ebcdic.h>
  12 #include "dasd_int.h"
  13 #include "dasd_eckd.h"
  14
  15 #ifdef PRINTK_HEADER
  16 #undef PRINTK_HEADER
  17 #endif                          /* PRINTK_HEADER */
  18 #define PRINTK_HEADER "dasd(eckd):"
  19
  20
  21 /*
  22  * General concept of alias management:
  23  * - PAV and DASD alias management is specific to the eckd discipline.
  24  * - A device is connected to an lcu as long as the device exists.
  25  *   dasd_alias_make_device_known_to_lcu will be called wenn the
  26  *   device is checked by the eckd discipline and
  27  *   dasd_alias_disconnect_device_from_lcu will be called
  28  *   before the device is deleted.
  29  * - The dasd_alias_add_device / dasd_alias_remove_device
  30  *   functions mark the point when a device is 'ready for service'.
  31  * - A summary unit check is a rare occasion, but it is mandatory to
  32  *   support it. It requires some complex recovery actions before the
  33  *   devices can be used again (see dasd_alias_handle_summary_unit_check).
  34  * - dasd_alias_get_start_dev will find an alias device that can be used
  35  *   instead of the base device and does some (very simple) load balancing.
  36  *   This is the function that gets called for each I/O, so when improving
  37  *   something, this function should get faster or better, the rest has just
  38  *   to be correct.
  39  */
  40
  41
  42 static void summary_unit_check_handling_work(struct work_struct *);
  43 static void lcu_update_work(struct work_struct *);
  44 static int _schedule_lcu_update(struct alias_lcu *, struct dasd_device *);
  45
  46 static struct alias_root aliastree = {
  47         .serverlist = LIST_HEAD_INIT(aliastree.serverlist),
  48         .lock = __SPIN_LOCK_UNLOCKED(aliastree.lock),
  49 };
  50
  51 static struct alias_server *_find_server(struct dasd_uid *uid)
  52 {
  53         struct alias_server *pos;
  54         list_for_each_entry(pos, &aliastree.serverlist, server) {
  55                 if (!strncmp(pos->uid.vendor, uid->vendor,
  56                              sizeof(uid->vendor))
  57                     && !strncmp(pos->uid.serial, uid->serial,
  58                                 sizeof(uid->serial)))
  59                         return pos;
  60         };
  61         return NULL;
  62 }
  63
  64 static struct alias_lcu *_find_lcu(struct alias_server *server,
  65                                    struct dasd_uid *uid)
  66 {
  67         struct alias_lcu *pos;
  68         list_for_each_entry(pos, &server->lculist, lcu) {
  69                 if (pos->uid.ssid == uid->ssid)
  70                         return pos;
  71         };
  72         return NULL;
  73 }
  74
  75 static struct alias_pav_group *_find_group(struct alias_lcu *lcu,
  76                                            struct dasd_uid *uid)
  77 {
  78         struct alias_pav_group *pos;
  79         __u8 search_unit_addr;
  80
  81         /* for hyper pav there is only one group */
  82         if (lcu->pav == HYPER_PAV) {
  83                 if (list_empty(&lcu->grouplist))
  84                         return NULL;
  85                 else
  86                         return list_first_entry(&lcu->grouplist,
  87                                                 struct alias_pav_group, group);
  88         }
  89
  90         /* for base pav we have to find the group that matches the base */
  91         if (uid->type == UA_BASE_DEVICE)
  92                 search_unit_addr = uid->real_unit_addr;
  93         else
  94                 search_unit_addr = uid->base_unit_addr;
  95         list_for_each_entry(pos, &lcu->grouplist, group) {
  96                 if (pos->uid.base_unit_addr == search_unit_addr &&
  97                     !strncmp(pos->uid.vduit, uid->vduit, sizeof(uid->vduit)))
  98                         return pos;
  99         };
 100         return NULL;
 101 }
 102
 103 static struct alias_server *_allocate_server(struct dasd_uid *uid)
 104 {
 105         struct alias_server *server;
 106
 107         server = kzalloc(sizeof(*server), GFP_KERNEL);
 108         if (!server)
 109                 return ERR_PTR(-ENOMEM);
 110         memcpy(server->uid.vendor, uid->vendor, sizeof(uid->vendor));
 111         memcpy(server->uid.serial, uid->serial, sizeof(uid->serial));
 112         INIT_LIST_HEAD(&server->server);
 113         INIT_LIST_HEAD(&server->lculist);
 114         return server;
 115 }
 116
 117 static void _free_server(struct alias_server *server)
 118 {
 119         kfree(server);
 120 }
 121
 122 static struct alias_lcu *_allocate_lcu(struct dasd_uid *uid)
 123 {
 124         struct alias_lcu *lcu;
 125
 126         lcu = kzalloc(sizeof(*lcu), GFP_KERNEL);
 127         if (!lcu)
 128                 return ERR_PTR(-ENOMEM);
 129         lcu->uac = kzalloc(sizeof(*(lcu->uac)), GFP_KERNEL | GFP_DMA);
 130         if (!lcu->uac)
 131                 goto out_err1;
 132         lcu->rsu_cqr = kzalloc(sizeof(*lcu->rsu_cqr), GFP_KERNEL | GFP_DMA);
 133         if (!lcu->rsu_cqr)
 134                 goto out_err2;
 135         lcu->rsu_cqr->cpaddr = kzalloc(sizeof(struct ccw1),
 136                                        GFP_KERNEL | GFP_DMA);
 137         if (!lcu->rsu_cqr->cpaddr)
 138                 goto out_err3;
 139         lcu->rsu_cqr->data = kzalloc(16, GFP_KERNEL | GFP_DMA);
 140         if (!lcu->rsu_cqr->data)
 141                 goto out_err4;
 142
 143         memcpy(lcu->uid.vendor, uid->vendor, sizeof(uid->vendor));
 144         memcpy(lcu->uid.serial, uid->serial, sizeof(uid->serial));
 145         lcu->uid.ssid = uid->ssid;
 146         lcu->pav = NO_PAV;
 147         lcu->flags = NEED_UAC_UPDATE | UPDATE_PENDING;
 148         INIT_LIST_HEAD(&lcu->lcu);
 149         INIT_LIST_HEAD(&lcu->inactive_devices);
 150         INIT_LIST_HEAD(&lcu->active_devices);
 151         INIT_LIST_HEAD(&lcu->grouplist);
 152         INIT_WORK(&lcu->suc_data.worker, summary_unit_check_handling_work);
 153         INIT_DELAYED_WORK(&lcu->ruac_data.dwork, lcu_update_work);
 154         spin_lock_init(&lcu->lock);
 155         init_completion(&lcu->lcu_setup);
 156         return lcu;
 157
 158 out_err4:
 159         kfree(lcu->rsu_cqr->cpaddr);
 160 out_err3:
 161         kfree(lcu->rsu_cqr);
 162 out_err2:
 163         kfree(lcu->uac);
 164 out_err1:
 165         kfree(lcu);
 166         return ERR_PTR(-ENOMEM);
 167 }
 168
 169 static void _free_lcu(struct alias_lcu *lcu)
 170 {
 171         kfree(lcu->rsu_cqr->data);
 172         kfree(lcu->rsu_cqr->cpaddr);
 173         kfree(lcu->rsu_cqr);
 174         kfree(lcu->uac);
 175         kfree(lcu);
 176 }
 177
 178 /*
 179  * This is the function that will allocate all the server and lcu data,
 180  * so this function must be called first for a new device.
 181  * If the return value is 1, the lcu was already known before, if it
 182  * is 0, this is a new lcu.
 183  * Negative return code indicates that something went wrong (e.g. -ENOMEM)
 184  */
 185 int dasd_alias_make_device_known_to_lcu(struct dasd_device *device)
 186 {
 187         struct dasd_eckd_private *private;
 188         unsigned long flags;
 189         struct alias_server *server, *newserver;
 190         struct alias_lcu *lcu, *newlcu;
 191         int is_lcu_known;
 192         struct dasd_uid *uid;
 193
 194         private = (struct dasd_eckd_private *) device->private;
 195         uid = &private->uid;
 196         spin_lock_irqsave(&aliastree.lock, flags);
 197         is_lcu_known = 1;
 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                         is_lcu_known = 0;
 210                 } else {
 211                         /* someone was faster */
 212                         _free_server(newserver);
 213                 }
 214         }
 215
 216         lcu = _find_lcu(server, uid);
 217         if (!lcu) {
 218                 spin_unlock_irqrestore(&aliastree.lock, flags);
 219                 newlcu = _allocate_lcu(uid);
 220                 if (IS_ERR(newlcu))
 221                         return PTR_ERR(newlcu);
 222                 spin_lock_irqsave(&aliastree.lock, flags);
 223                 lcu = _find_lcu(server, uid);
 224                 if (!lcu) {
 225                         list_add(&newlcu->lcu, &server->lculist);
 226                         lcu = newlcu;
 227                         is_lcu_known = 0;
 228                 } else {
 229                         /* someone was faster */
 230                         _free_lcu(newlcu);
 231                 }
 232                 is_lcu_known = 0;
 233         }
 234         spin_lock(&lcu->lock);
 235         list_add(&device->alias_list, &lcu->inactive_devices);
 236         private->lcu = lcu;
 237         spin_unlock(&lcu->lock);
 238         spin_unlock_irqrestore(&aliastree.lock, flags);
 239
 240         return is_lcu_known;
 241 }
 242
 243 /*
 244  * The first device to be registered on an LCU will have to do
 245  * some additional setup steps to configure that LCU on the
 246  * storage server. All further devices should wait with their
 247  * initialization until the first device is done.
 248  * To synchronize this work, the first device will call
 249  * dasd_alias_lcu_setup_complete when it is done, and all
 250  * other devices will wait for it with dasd_alias_wait_for_lcu_setup.
 251  */
 252 void dasd_alias_lcu_setup_complete(struct dasd_device *device)
 253 {
 254         struct dasd_eckd_private *private;
 255         unsigned long flags;
 256         struct alias_server *server;
 257         struct alias_lcu *lcu;
 258         struct dasd_uid *uid;
 259
 260         private = (struct dasd_eckd_private *) device->private;
 261         uid = &private->uid;
 262         lcu = NULL;
 263         spin_lock_irqsave(&aliastree.lock, flags);
 264         server = _find_server(uid);
 265         if (server)
 266                 lcu = _find_lcu(server, uid);
 267         spin_unlock_irqrestore(&aliastree.lock, flags);
 268         if (!lcu) {
 269                 DBF_EVENT_DEVID(DBF_ERR, device->cdev,
 270                                 "could not find lcu for %04x %02x",
 271                                 uid->ssid, uid->real_unit_addr);
 272                 WARN_ON(1);
 273                 return;
 274         }
 275         complete_all(&lcu->lcu_setup);
 276 }
 277
 278 void dasd_alias_wait_for_lcu_setup(struct dasd_device *device)
 279 {
 280         struct dasd_eckd_private *private;
 281         unsigned long flags;
 282         struct alias_server *server;
 283         struct alias_lcu *lcu;
 284         struct dasd_uid *uid;
 285
 286         private = (struct dasd_eckd_private *) device->private;
 287         uid = &private->uid;
 288         lcu = NULL;
 289         spin_lock_irqsave(&aliastree.lock, flags);
 290         server = _find_server(uid);
 291         if (server)
 292                 lcu = _find_lcu(server, uid);
 293         spin_unlock_irqrestore(&aliastree.lock, flags);
 294         if (!lcu) {
 295                 DBF_EVENT_DEVID(DBF_ERR, device->cdev,
 296                                 "could not find lcu for %04x %02x",
 297                                 uid->ssid, uid->real_unit_addr);
 298                 WARN_ON(1);
 299                 return;
 300         }
 301         wait_for_completion(&lcu->lcu_setup);
 302 }
 303
 304 /*
 305  * This function removes a device from the scope of alias management.
 306  * The complicated part is to make sure that it is not in use by
 307  * any of the workers. If necessary cancel the work.
 308  */
 309 void dasd_alias_disconnect_device_from_lcu(struct dasd_device *device)
 310 {
 311         struct dasd_eckd_private *private;
 312         unsigned long flags;
 313         struct alias_lcu *lcu;
 314         struct alias_server *server;
 315         int was_pending;
 316
 317         private = (struct dasd_eckd_private *) device->private;
 318         lcu = private->lcu;
 319         spin_lock_irqsave(&lcu->lock, flags);
 320         list_del_init(&device->alias_list);
 321         /* make sure that the workers don't use this device */
 322         if (device == lcu->suc_data.device) {
 323                 spin_unlock_irqrestore(&lcu->lock, flags);
 324                 cancel_work_sync(&lcu->suc_data.worker);
 325                 spin_lock_irqsave(&lcu->lock, flags);
 326                 if (device == lcu->suc_data.device)
 327                         lcu->suc_data.device = NULL;
 328         }
 329         was_pending = 0;
 330         if (device == lcu->ruac_data.device) {
 331                 spin_unlock_irqrestore(&lcu->lock, flags);
 332                 was_pending = 1;
 333                 cancel_delayed_work_sync(&lcu->ruac_data.dwork);
 334                 spin_lock_irqsave(&lcu->lock, flags);
 335                 if (device == lcu->ruac_data.device)
 336                         lcu->ruac_data.device = NULL;
 337         }
 338         private->lcu = NULL;
 339         spin_unlock_irqrestore(&lcu->lock, flags);
 340
 341         spin_lock_irqsave(&aliastree.lock, flags);
 342         spin_lock(&lcu->lock);
 343         if (list_empty(&lcu->grouplist) &&
 344             list_empty(&lcu->active_devices) &&
 345             list_empty(&lcu->inactive_devices)) {
 346                 list_del(&lcu->lcu);
 347                 spin_unlock(&lcu->lock);
 348                 _free_lcu(lcu);
 349                 lcu = NULL;
 350         } else {
 351                 if (was_pending)
 352                         _schedule_lcu_update(lcu, NULL);
 353                 spin_unlock(&lcu->lock);
 354         }
 355         server = _find_server(&private->uid);
 356         if (server && list_empty(&server->lculist)) {
 357                 list_del(&server->server);
 358                 _free_server(server);
 359         }
 360         spin_unlock_irqrestore(&aliastree.lock, flags);
 361 }
 362
 363 /*
 364  * This function assumes that the unit address configuration stored
 365  * in the lcu is up to date and will update the device uid before
 366  * adding it to a pav group.
 367  */
 368 static int _add_device_to_lcu(struct alias_lcu *lcu,
 369                               struct dasd_device *device)
 370 {
 371
 372         struct dasd_eckd_private *private;
 373         struct alias_pav_group *group;
 374         struct dasd_uid *uid;
 375
 376         private = (struct dasd_eckd_private *) device->private;
 377         uid = &private->uid;
 378         uid->type = lcu->uac->unit[uid->real_unit_addr].ua_type;
 379         uid->base_unit_addr = lcu->uac->unit[uid->real_unit_addr].base_ua;
 380         dasd_set_uid(device->cdev, &private->uid);
 381
 382         /* if we have no PAV anyway, we don't need to bother with PAV groups */
 383         if (lcu->pav == NO_PAV) {
 384                 list_move(&device->alias_list, &lcu->active_devices);
 385                 return 0;
 386         }
 387
 388         group = _find_group(lcu, uid);
 389         if (!group) {
 390                 group = kzalloc(sizeof(*group), GFP_ATOMIC);
 391                 if (!group)
 392                         return -ENOMEM;
 393                 memcpy(group->uid.vendor, uid->vendor, sizeof(uid->vendor));
 394                 memcpy(group->uid.serial, uid->serial, sizeof(uid->serial));
 395                 group->uid.ssid = uid->ssid;
 396                 if (uid->type == UA_BASE_DEVICE)
 397                         group->uid.base_unit_addr = uid->real_unit_addr;
 398                 else
 399                         group->uid.base_unit_addr = uid->base_unit_addr;
 400                 memcpy(group->uid.vduit, uid->vduit, sizeof(uid->vduit));
 401                 INIT_LIST_HEAD(&group->group);
 402                 INIT_LIST_HEAD(&group->baselist);
 403                 INIT_LIST_HEAD(&group->aliaslist);
 404                 list_add(&group->group, &lcu->grouplist);
 405         }
 406         if (uid->type == UA_BASE_DEVICE)
 407                 list_move(&device->alias_list, &group->baselist);
 408         else
 409                 list_move(&device->alias_list, &group->aliaslist);
 410         private->pavgroup = group;
 411         return 0;
 412 };
 413
 414 static void _remove_device_from_lcu(struct alias_lcu *lcu,
 415                                     struct dasd_device *device)
 416 {
 417         struct dasd_eckd_private *private;
 418         struct alias_pav_group *group;
 419
 420         private = (struct dasd_eckd_private *) device->private;
 421         list_move(&device->alias_list, &lcu->inactive_devices);
 422         group = private->pavgroup;
 423         if (!group)
 424                 return;
 425         private->pavgroup = NULL;
 426         if (list_empty(&group->baselist) && list_empty(&group->aliaslist)) {
 427                 list_del(&group->group);
 428                 kfree(group);
 429                 return;
 430         }
 431         if (group->next == device)
 432                 group->next = NULL;
 433 };
 434
 435 static int read_unit_address_configuration(struct dasd_device *device,
 436                                            struct alias_lcu *lcu)
 437 {
 438         struct dasd_psf_prssd_data *prssdp;
 439         struct dasd_ccw_req *cqr;
 440         struct ccw1 *ccw;
 441         int rc;
 442         unsigned long flags;
 443
 444         cqr = dasd_kmalloc_request(DASD_ECKD_MAGIC, 1 /* PSF */ + 1 /* RSSD */,
 445                                    (sizeof(struct dasd_psf_prssd_data)),
 446                                    device);
 447         if (IS_ERR(cqr))
 448                 return PTR_ERR(cqr);
 449         cqr->startdev = device;
 450         cqr->memdev = device;
 451         clear_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
 452         cqr->retries = 10;
 453         cqr->expires = 20 * HZ;
 454
 455         /* Prepare for Read Subsystem Data */
 456         prssdp = (struct dasd_psf_prssd_data *) cqr->data;
 457         memset(prssdp, 0, sizeof(struct dasd_psf_prssd_data));
 458         prssdp->order = PSF_ORDER_PRSSD;
 459         prssdp->suborder = 0x0e;        /* Read unit address configuration */
 460         /* all other bytes of prssdp must be zero */
 461
 462         ccw = cqr->cpaddr;
 463         ccw->cmd_code = DASD_ECKD_CCW_PSF;
 464         ccw->count = sizeof(struct dasd_psf_prssd_data);
 465         ccw->flags |= CCW_FLAG_CC;
 466         ccw->cda = (__u32)(addr_t) prssdp;
 467
 468         /* Read Subsystem Data - feature codes */
 469         memset(lcu->uac, 0, sizeof(*(lcu->uac)));
 470
 471         ccw++;
 472         ccw->cmd_code = DASD_ECKD_CCW_RSSD;
 473         ccw->count = sizeof(*(lcu->uac));
 474         ccw->cda = (__u32)(addr_t) lcu->uac;
 475
 476         cqr->buildclk = get_clock();
 477         cqr->status = DASD_CQR_FILLED;
 478
 479         /* need to unset flag here to detect race with summary unit check */
 480         spin_lock_irqsave(&lcu->lock, flags);
 481         lcu->flags &= ~NEED_UAC_UPDATE;
 482         spin_unlock_irqrestore(&lcu->lock, flags);
 483
 484         do {
 485                 rc = dasd_sleep_on(cqr);
 486         } while (rc && (cqr->retries > 0));
 487         if (rc) {
 488                 spin_lock_irqsave(&lcu->lock, flags);
 489                 lcu->flags |= NEED_UAC_UPDATE;
 490                 spin_unlock_irqrestore(&lcu->lock, flags);
 491         }
 492         dasd_kfree_request(cqr, cqr->memdev);
 493         return rc;
 494 }
 495
 496 static int _lcu_update(struct dasd_device *refdev, struct alias_lcu *lcu)
 497 {
 498         unsigned long flags;
 499         struct alias_pav_group *pavgroup, *tempgroup;
 500         struct dasd_device *device, *tempdev;
 501         int i, rc;
 502         struct dasd_eckd_private *private;
 503
 504         spin_lock_irqsave(&lcu->lock, flags);
 505         list_for_each_entry_safe(pavgroup, tempgroup, &lcu->grouplist, group) {
 506                 list_for_each_entry_safe(device, tempdev, &pavgroup->baselist,
 507                                          alias_list) {
 508                         list_move(&device->alias_list, &lcu->active_devices);
 509                         private = (struct dasd_eckd_private *) device->private;
 510                         private->pavgroup = NULL;
 511                 }
 512                 list_for_each_entry_safe(device, tempdev, &pavgroup->aliaslist,
 513                                          alias_list) {
 514                         list_move(&device->alias_list, &lcu->active_devices);
 515                         private = (struct dasd_eckd_private *) device->private;
 516                         private->pavgroup = NULL;
 517                 }
 518                 list_del(&pavgroup->group);
 519                 kfree(pavgroup);
 520         }
 521         spin_unlock_irqrestore(&lcu->lock, flags);
 522
 523         rc = read_unit_address_configuration(refdev, lcu);
 524         if (rc)
 525                 return rc;
 526
 527         spin_lock_irqsave(&lcu->lock, flags);
 528         lcu->pav = NO_PAV;
 529         for (i = 0; i < MAX_DEVICES_PER_LCU; ++i) {
 530                 switch (lcu->uac->unit[i].ua_type) {
 531                 case UA_BASE_PAV_ALIAS:
 532                         lcu->pav = BASE_PAV;
 533                         break;
 534                 case UA_HYPER_PAV_ALIAS:
 535                         lcu->pav = HYPER_PAV;
 536                         break;
 537                 }
 538                 if (lcu->pav != NO_PAV)
 539                         break;
 540         }
 541
 542         list_for_each_entry_safe(device, tempdev, &lcu->active_devices,
 543                                  alias_list) {
 544                 _add_device_to_lcu(lcu, device);
 545         }
 546         spin_unlock_irqrestore(&lcu->lock, flags);
 547         return 0;
 548 }
 549
 550 static void lcu_update_work(struct work_struct *work)
 551 {
 552         struct alias_lcu *lcu;
 553         struct read_uac_work_data *ruac_data;
 554         struct dasd_device *device;
 555         unsigned long flags;
 556         int rc;
 557
 558         ruac_data = container_of(work, struct read_uac_work_data, dwork.work);
 559         lcu = container_of(ruac_data, struct alias_lcu, ruac_data);
 560         device = ruac_data->device;
 561         rc = _lcu_update(device, lcu);
 562         /*
 563          * Need to check flags again, as there could have been another
 564          * prepare_update or a new device a new device while we were still
 565          * processing the data
 566          */
 567         spin_lock_irqsave(&lcu->lock, flags);
 568         if (rc || (lcu->flags & NEED_UAC_UPDATE)) {
 569                 DBF_DEV_EVENT(DBF_WARNING, device, "could not update"
 570                             " alias data in lcu (rc = %d), retry later", rc);
 571                 schedule_delayed_work(&lcu->ruac_data.dwork, 30*HZ);
 572         } else {
 573                 lcu->ruac_data.device = NULL;
 574                 lcu->flags &= ~UPDATE_PENDING;
 575         }
 576         spin_unlock_irqrestore(&lcu->lock, flags);
 577 }
 578
 579 static int _schedule_lcu_update(struct alias_lcu *lcu,
 580                                 struct dasd_device *device)
 581 {
 582         struct dasd_device *usedev = NULL;
 583         struct alias_pav_group *group;
 584
 585         lcu->flags |= NEED_UAC_UPDATE;
 586         if (lcu->ruac_data.device) {
 587                 /* already scheduled or running */
 588                 return 0;
 589         }
 590         if (device && !list_empty(&device->alias_list))
 591                 usedev = device;
 592
 593         if (!usedev && !list_empty(&lcu->grouplist)) {
 594                 group = list_first_entry(&lcu->grouplist,
 595                                          struct alias_pav_group, group);
 596                 if (!list_empty(&group->baselist))
 597                         usedev = list_first_entry(&group->baselist,
 598                                                   struct dasd_device,
 599                                                   alias_list);
 600                 else if (!list_empty(&group->aliaslist))
 601                         usedev = list_first_entry(&group->aliaslist,
 602                                                   struct dasd_device,
 603                                                   alias_list);
 604         }
 605         if (!usedev && !list_empty(&lcu->active_devices)) {
 606                 usedev = list_first_entry(&lcu->active_devices,
 607                                           struct dasd_device, alias_list);
 608         }
 609         /*
 610          * if we haven't found a proper device yet, give up for now, the next
 611          * device that will be set active will trigger an lcu update
 612          */
 613         if (!usedev)
 614                 return -EINVAL;
 615         lcu->ruac_data.device = usedev;
 616         schedule_delayed_work(&lcu->ruac_data.dwork, 0);
 617         return 0;
 618 }
 619
 620 int dasd_alias_add_device(struct dasd_device *device)
 621 {
 622         struct dasd_eckd_private *private;
 623         struct alias_lcu *lcu;
 624         unsigned long flags;
 625         int rc;
 626
 627         private = (struct dasd_eckd_private *) device->private;
 628         lcu = private->lcu;
 629         rc = 0;
 630         spin_lock_irqsave(&lcu->lock, flags);
 631         if (!(lcu->flags & UPDATE_PENDING)) {
 632                 rc = _add_device_to_lcu(lcu, device);
 633                 if (rc)
 634                         lcu->flags |= UPDATE_PENDING;
 635         }
 636         if (lcu->flags & UPDATE_PENDING) {
 637                 list_move(&device->alias_list, &lcu->active_devices);
 638                 _schedule_lcu_update(lcu, device);
 639         }
 640         spin_unlock_irqrestore(&lcu->lock, flags);
 641         return rc;
 642 }
 643
 644 int dasd_alias_remove_device(struct dasd_device *device)
 645 {
 646         struct dasd_eckd_private *private;
 647         struct alias_lcu *lcu;
 648         unsigned long flags;
 649
 650         private = (struct dasd_eckd_private *) device->private;
 651         lcu = private->lcu;
 652         spin_lock_irqsave(&lcu->lock, flags);
 653         _remove_device_from_lcu(lcu, device);
 654         spin_unlock_irqrestore(&lcu->lock, flags);
 655         return 0;
 656 }
 657
 658 struct dasd_device *dasd_alias_get_start_dev(struct dasd_device *base_device)
 659 {
 660
 661         struct dasd_device *alias_device;
 662         struct alias_pav_group *group;
 663         struct alias_lcu *lcu;
 664         struct dasd_eckd_private *private, *alias_priv;
 665         unsigned long flags;
 666
 667         private = (struct dasd_eckd_private *) base_device->private;
 668         group = private->pavgroup;
 669         lcu = private->lcu;
 670         if (!group || !lcu)
 671                 return NULL;
 672         if (lcu->pav == NO_PAV ||
 673             lcu->flags & (NEED_UAC_UPDATE | UPDATE_PENDING))
 674                 return NULL;
 675
 676         spin_lock_irqsave(&lcu->lock, flags);
 677         alias_device = group->next;
 678         if (!alias_device) {
 679                 if (list_empty(&group->aliaslist)) {
 680                         spin_unlock_irqrestore(&lcu->lock, flags);
 681                         return NULL;
 682                 } else {
 683                         alias_device = list_first_entry(&group->aliaslist,
 684                                                         struct dasd_device,
 685                                                         alias_list);
 686                 }
 687         }
 688         if (list_is_last(&alias_device->alias_list, &group->aliaslist))
 689                 group->next = list_first_entry(&group->aliaslist,
 690                                                struct dasd_device, alias_list);
 691         else
 692                 group->next = list_first_entry(&alias_device->alias_list,
 693                                                struct dasd_device, alias_list);
 694         spin_unlock_irqrestore(&lcu->lock, flags);
 695         alias_priv = (struct dasd_eckd_private *) alias_device->private;
 696         if ((alias_priv->count < private->count) && !alias_device->stopped)
 697                 return alias_device;
 698         else
 699                 return NULL;
 700 }
 701
 702 /*
 703  * Summary unit check handling depends on the way alias devices
 704  * are handled so it is done here rather then in dasd_eckd.c
 705  */
 706 static int reset_summary_unit_check(struct alias_lcu *lcu,
 707                                     struct dasd_device *device,
 708                                     char reason)
 709 {
 710         struct dasd_ccw_req *cqr;
 711         int rc = 0;
 712         struct ccw1 *ccw;
 713
 714         cqr = lcu->rsu_cqr;
 715         strncpy((char *) &cqr->magic, "ECKD", 4);
 716         ASCEBC((char *) &cqr->magic, 4);
 717         ccw = cqr->cpaddr;
 718         ccw->cmd_code = DASD_ECKD_CCW_RSCK;
 719         ccw->flags = 0 ;
 720         ccw->count = 16;
 721         ccw->cda = (__u32)(addr_t) cqr->data;
 722         ((char *)cqr->data)[0] = reason;
 723
 724         clear_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
 725         cqr->retries = 255;     /* set retry counter to enable basic ERP */
 726         cqr->startdev = device;
 727         cqr->memdev = device;
 728         cqr->block = NULL;
 729         cqr->expires = 5 * HZ;
 730         cqr->buildclk = get_clock();
 731         cqr->status = DASD_CQR_FILLED;
 732
 733         rc = dasd_sleep_on_immediatly(cqr);
 734         return rc;
 735 }
 736
 737 static void _restart_all_base_devices_on_lcu(struct alias_lcu *lcu)
 738 {
 739         struct alias_pav_group *pavgroup;
 740         struct dasd_device *device;
 741         struct dasd_eckd_private *private;
 742
 743         /* active and inactive list can contain alias as well as base devices */
 744         list_for_each_entry(device, &lcu->active_devices, alias_list) {
 745                 private = (struct dasd_eckd_private *) device->private;
 746                 if (private->uid.type != UA_BASE_DEVICE)
 747                         continue;
 748                 dasd_schedule_block_bh(device->block);
 749                 dasd_schedule_device_bh(device);
 750         }
 751         list_for_each_entry(device, &lcu->inactive_devices, alias_list) {
 752                 private = (struct dasd_eckd_private *) device->private;
 753                 if (private->uid.type != UA_BASE_DEVICE)
 754                         continue;
 755                 dasd_schedule_block_bh(device->block);
 756                 dasd_schedule_device_bh(device);
 757         }
 758         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 759                 list_for_each_entry(device, &pavgroup->baselist, alias_list) {
 760                         dasd_schedule_block_bh(device->block);
 761                         dasd_schedule_device_bh(device);
 762                 }
 763         }
 764 }
 765
 766 static void flush_all_alias_devices_on_lcu(struct alias_lcu *lcu)
 767 {
 768         struct alias_pav_group *pavgroup;
 769         struct dasd_device *device, *temp;
 770         struct dasd_eckd_private *private;
 771         int rc;
 772         unsigned long flags;
 773         LIST_HEAD(active);
 774
 775         /*
 776          * Problem here ist that dasd_flush_device_queue may wait
 777          * for termination of a request to complete. We can't keep
 778          * the lcu lock during that time, so we must assume that
 779          * the lists may have changed.
 780          * Idea: first gather all active alias devices in a separate list,
 781          * then flush the first element of this list unlocked, and afterwards
 782          * check if it is still on the list before moving it to the
 783          * active_devices list.
 784          */
 785
 786         spin_lock_irqsave(&lcu->lock, flags);
 787         list_for_each_entry_safe(device, temp, &lcu->active_devices,
 788                                  alias_list) {
 789                 private = (struct dasd_eckd_private *) device->private;
 790                 if (private->uid.type == UA_BASE_DEVICE)
 791                         continue;
 792                 list_move(&device->alias_list, &active);
 793         }
 794
 795         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 796                 list_splice_init(&pavgroup->aliaslist, &active);
 797         }
 798         while (!list_empty(&active)) {
 799                 device = list_first_entry(&active, struct dasd_device,
 800                                           alias_list);
 801                 spin_unlock_irqrestore(&lcu->lock, flags);
 802                 rc = dasd_flush_device_queue(device);
 803                 spin_lock_irqsave(&lcu->lock, flags);
 804                 /*
 805                  * only move device around if it wasn't moved away while we
 806                  * were waiting for the flush
 807                  */
 808                 if (device == list_first_entry(&active,
 809                                                struct dasd_device, alias_list))
 810                         list_move(&device->alias_list, &lcu->active_devices);
 811         }
 812         spin_unlock_irqrestore(&lcu->lock, flags);
 813 }
 814
 815 static void __stop_device_on_lcu(struct dasd_device *device,
 816                                  struct dasd_device *pos)
 817 {
 818         /* If pos == device then device is already locked! */
 819         if (pos == device) {
 820                 dasd_device_set_stop_bits(pos, DASD_STOPPED_SU);
 821                 return;
 822         }
 823         spin_lock(get_ccwdev_lock(pos->cdev));
 824         dasd_device_set_stop_bits(pos, DASD_STOPPED_SU);
 825         spin_unlock(get_ccwdev_lock(pos->cdev));
 826 }
 827
 828 /*
 829  * This function is called in interrupt context, so the
 830  * cdev lock for device is already locked!
 831  */
 832 static void _stop_all_devices_on_lcu(struct alias_lcu *lcu,
 833                                      struct dasd_device *device)
 834 {
 835         struct alias_pav_group *pavgroup;
 836         struct dasd_device *pos;
 837
 838         list_for_each_entry(pos, &lcu->active_devices, alias_list)
 839                 __stop_device_on_lcu(device, pos);
 840         list_for_each_entry(pos, &lcu->inactive_devices, alias_list)
 841                 __stop_device_on_lcu(device, pos);
 842         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 843                 list_for_each_entry(pos, &pavgroup->baselist, alias_list)
 844                         __stop_device_on_lcu(device, pos);
 845                 list_for_each_entry(pos, &pavgroup->aliaslist, alias_list)
 846                         __stop_device_on_lcu(device, pos);
 847         }
 848 }
 849
 850 static void _unstop_all_devices_on_lcu(struct alias_lcu *lcu)
 851 {
 852         struct alias_pav_group *pavgroup;
 853         struct dasd_device *device;
 854         unsigned long flags;
 855
 856         list_for_each_entry(device, &lcu->active_devices, alias_list) {
 857                 spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 858                 dasd_device_remove_stop_bits(device, DASD_STOPPED_SU);
 859                 spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 860         }
 861
 862         list_for_each_entry(device, &lcu->inactive_devices, alias_list) {
 863                 spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 864                 dasd_device_remove_stop_bits(device, DASD_STOPPED_SU);
 865                 spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 866         }
 867
 868         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 869                 list_for_each_entry(device, &pavgroup->baselist, alias_list) {
 870                         spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 871                         dasd_device_remove_stop_bits(device, DASD_STOPPED_SU);
 872                         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev),
 873                                                flags);
 874                 }
 875                 list_for_each_entry(device, &pavgroup->aliaslist, alias_list) {
 876                         spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 877                         dasd_device_remove_stop_bits(device, DASD_STOPPED_SU);
 878                         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev),
 879                                                flags);
 880                 }
 881         }
 882 }
 883
 884 static void summary_unit_check_handling_work(struct work_struct *work)
 885 {
 886         struct alias_lcu *lcu;
 887         struct summary_unit_check_work_data *suc_data;
 888         unsigned long flags;
 889         struct dasd_device *device;
 890
 891         suc_data = container_of(work, struct summary_unit_check_work_data,
 892                                 worker);
 893         lcu = container_of(suc_data, struct alias_lcu, suc_data);
 894         device = suc_data->device;
 895
 896         /* 1. flush alias devices */
 897         flush_all_alias_devices_on_lcu(lcu);
 898
 899         /* 2. reset summary unit check */
 900         spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 901         dasd_device_remove_stop_bits(device,
 902                                      (DASD_STOPPED_SU | DASD_STOPPED_PENDING));
 903         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 904         reset_summary_unit_check(lcu, device, suc_data->reason);
 905
 906         spin_lock_irqsave(&lcu->lock, flags);
 907         _unstop_all_devices_on_lcu(lcu);
 908         _restart_all_base_devices_on_lcu(lcu);
 909         /* 3. read new alias configuration */
 910         _schedule_lcu_update(lcu, device);
 911         lcu->suc_data.device = NULL;
 912         spin_unlock_irqrestore(&lcu->lock, flags);
 913 }
 914
 915 /*
 916  * note: this will be called from int handler context (cdev locked)
 917  */
 918 void dasd_alias_handle_summary_unit_check(struct dasd_device *device,
 919                                           struct irb *irb)
 920 {
 921         struct alias_lcu *lcu;
 922         char reason;
 923         struct dasd_eckd_private *private;
 924         char *sense;
 925
 926         private = (struct dasd_eckd_private *) device->private;
 927
 928         sense = dasd_get_sense(irb);
 929         if (sense) {
 930                 reason = sense[8];
 931                 DBF_DEV_EVENT(DBF_NOTICE, device, "%s %x",
 932                             "eckd handle summary unit check: reason", reason);
 933         } else {
 934                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
 935                             "eckd handle summary unit check:"
 936                             " no reason code available");
 937                 return;
 938         }
 939
 940         lcu = private->lcu;
 941         if (!lcu) {
 942                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
 943                             "device not ready to handle summary"
 944                             " unit check (no lcu structure)");
 945                 return;
 946         }
 947         spin_lock(&lcu->lock);
 948         _stop_all_devices_on_lcu(lcu, device);
 949         /* prepare for lcu_update */
 950         private->lcu->flags |= NEED_UAC_UPDATE | UPDATE_PENDING;
 951         /* If this device is about to be removed just return and wait for
 952          * the next interrupt on a different device
 953          */
 954         if (list_empty(&device->alias_list)) {
 955                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
 956                             "device is in offline processing,"
 957                             " don't do summary unit check handling");
 958                 spin_unlock(&lcu->lock);
 959                 return;
 960         }
 961         if (lcu->suc_data.device) {
 962                 /* already scheduled or running */
 963                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
 964                             "previous instance of summary unit check worker"
 965                             " still pending");
 966                 spin_unlock(&lcu->lock);
 967                 return ;
 968         }
 969         lcu->suc_data.reason = reason;
 970         lcu->suc_data.device = device;
 971         spin_unlock(&lcu->lock);
 972         schedule_work(&lcu->suc_data.worker);
 973 };