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         return lcu;
 156
 157 out_err4:
 158         kfree(lcu->rsu_cqr->cpaddr);
 159 out_err3:
 160         kfree(lcu->rsu_cqr);
 161 out_err2:
 162         kfree(lcu->uac);
 163 out_err1:
 164         kfree(lcu);
 165         return ERR_PTR(-ENOMEM);
 166 }
 167
 168 static void _free_lcu(struct alias_lcu *lcu)
 169 {
 170         kfree(lcu->rsu_cqr->data);
 171         kfree(lcu->rsu_cqr->cpaddr);
 172         kfree(lcu->rsu_cqr);
 173         kfree(lcu->uac);
 174         kfree(lcu);
 175 }
 176
 177 /*
 178  * This is the function that will allocate all the server and lcu data,
 179  * so this function must be called first for a new device.
 180  * If the return value is 1, the lcu was already known before, if it
 181  * is 0, this is a new lcu.
 182  * Negative return code indicates that something went wrong (e.g. -ENOMEM)
 183  */
 184 int dasd_alias_make_device_known_to_lcu(struct dasd_device *device)
 185 {
 186         struct dasd_eckd_private *private;
 187         unsigned long flags;
 188         struct alias_server *server, *newserver;
 189         struct alias_lcu *lcu, *newlcu;
 190         int is_lcu_known;
 191         struct dasd_uid *uid;
 192
 193         private = (struct dasd_eckd_private *) device->private;
 194         uid = &private->uid;
 195         spin_lock_irqsave(&aliastree.lock, flags);
 196         is_lcu_known = 1;
 197         server = _find_server(uid);
 198         if (!server) {
 199                 spin_unlock_irqrestore(&aliastree.lock, flags);
 200                 newserver = _allocate_server(uid);
 201                 if (IS_ERR(newserver))
 202                         return PTR_ERR(newserver);
 203                 spin_lock_irqsave(&aliastree.lock, flags);
 204                 server = _find_server(uid);
 205                 if (!server) {
 206                         list_add(&newserver->server, &aliastree.serverlist);
 207                         server = newserver;
 208                         is_lcu_known = 0;
 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(lcu);
 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                         is_lcu_known = 0;
 227                 } else {
 228                         /* someone was faster */
 229                         _free_lcu(newlcu);
 230                 }
 231                 is_lcu_known = 0;
 232         }
 233         spin_lock(&lcu->lock);
 234         list_add(&device->alias_list, &lcu->inactive_devices);
 235         private->lcu = lcu;
 236         spin_unlock(&lcu->lock);
 237         spin_unlock_irqrestore(&aliastree.lock, flags);
 238
 239         return is_lcu_known;
 240 }
 241
 242 /*
 243  * This function removes a device from the scope of alias management.
 244  * The complicated part is to make sure that it is not in use by
 245  * any of the workers. If necessary cancel the work.
 246  */
 247 void dasd_alias_disconnect_device_from_lcu(struct dasd_device *device)
 248 {
 249         struct dasd_eckd_private *private;
 250         unsigned long flags;
 251         struct alias_lcu *lcu;
 252         struct alias_server *server;
 253         int was_pending;
 254
 255         private = (struct dasd_eckd_private *) device->private;
 256         lcu = private->lcu;
 257         spin_lock_irqsave(&lcu->lock, flags);
 258         list_del_init(&device->alias_list);
 259         /* make sure that the workers don't use this device */
 260         if (device == lcu->suc_data.device) {
 261                 spin_unlock_irqrestore(&lcu->lock, flags);
 262                 cancel_work_sync(&lcu->suc_data.worker);
 263                 spin_lock_irqsave(&lcu->lock, flags);
 264                 if (device == lcu->suc_data.device)
 265                         lcu->suc_data.device = NULL;
 266         }
 267         was_pending = 0;
 268         if (device == lcu->ruac_data.device) {
 269                 spin_unlock_irqrestore(&lcu->lock, flags);
 270                 was_pending = 1;
 271                 cancel_delayed_work_sync(&lcu->ruac_data.dwork);
 272                 spin_lock_irqsave(&lcu->lock, flags);
 273                 if (device == lcu->ruac_data.device)
 274                         lcu->ruac_data.device = NULL;
 275         }
 276         private->lcu = NULL;
 277         spin_unlock_irqrestore(&lcu->lock, flags);
 278
 279         spin_lock_irqsave(&aliastree.lock, flags);
 280         spin_lock(&lcu->lock);
 281         if (list_empty(&lcu->grouplist) &&
 282             list_empty(&lcu->active_devices) &&
 283             list_empty(&lcu->inactive_devices)) {
 284                 list_del(&lcu->lcu);
 285                 spin_unlock(&lcu->lock);
 286                 _free_lcu(lcu);
 287                 lcu = NULL;
 288         } else {
 289                 if (was_pending)
 290                         _schedule_lcu_update(lcu, NULL);
 291                 spin_unlock(&lcu->lock);
 292         }
 293         server = _find_server(&private->uid);
 294         if (server && list_empty(&server->lculist)) {
 295                 list_del(&server->server);
 296                 _free_server(server);
 297         }
 298         spin_unlock_irqrestore(&aliastree.lock, flags);
 299 }
 300
 301 /*
 302  * This function assumes that the unit address configuration stored
 303  * in the lcu is up to date and will update the device uid before
 304  * adding it to a pav group.
 305  */
 306 static int _add_device_to_lcu(struct alias_lcu *lcu,
 307                               struct dasd_device *device)
 308 {
 309
 310         struct dasd_eckd_private *private;
 311         struct alias_pav_group *group;
 312         struct dasd_uid *uid;
 313
 314         private = (struct dasd_eckd_private *) device->private;
 315         uid = &private->uid;
 316         uid->type = lcu->uac->unit[uid->real_unit_addr].ua_type;
 317         uid->base_unit_addr = lcu->uac->unit[uid->real_unit_addr].base_ua;
 318         dasd_set_uid(device->cdev, &private->uid);
 319
 320         /* if we have no PAV anyway, we don't need to bother with PAV groups */
 321         if (lcu->pav == NO_PAV) {
 322                 list_move(&device->alias_list, &lcu->active_devices);
 323                 return 0;
 324         }
 325
 326         group = _find_group(lcu, uid);
 327         if (!group) {
 328                 group = kzalloc(sizeof(*group), GFP_ATOMIC);
 329                 if (!group)
 330                         return -ENOMEM;
 331                 memcpy(group->uid.vendor, uid->vendor, sizeof(uid->vendor));
 332                 memcpy(group->uid.serial, uid->serial, sizeof(uid->serial));
 333                 group->uid.ssid = uid->ssid;
 334                 if (uid->type == UA_BASE_DEVICE)
 335                         group->uid.base_unit_addr = uid->real_unit_addr;
 336                 else
 337                         group->uid.base_unit_addr = uid->base_unit_addr;
 338                 memcpy(group->uid.vduit, uid->vduit, sizeof(uid->vduit));
 339                 INIT_LIST_HEAD(&group->group);
 340                 INIT_LIST_HEAD(&group->baselist);
 341                 INIT_LIST_HEAD(&group->aliaslist);
 342                 list_add(&group->group, &lcu->grouplist);
 343         }
 344         if (uid->type == UA_BASE_DEVICE)
 345                 list_move(&device->alias_list, &group->baselist);
 346         else
 347                 list_move(&device->alias_list, &group->aliaslist);
 348         private->pavgroup = group;
 349         return 0;
 350 };
 351
 352 static void _remove_device_from_lcu(struct alias_lcu *lcu,
 353                                     struct dasd_device *device)
 354 {
 355         struct dasd_eckd_private *private;
 356         struct alias_pav_group *group;
 357
 358         private = (struct dasd_eckd_private *) device->private;
 359         list_move(&device->alias_list, &lcu->inactive_devices);
 360         group = private->pavgroup;
 361         if (!group)
 362                 return;
 363         private->pavgroup = NULL;
 364         if (list_empty(&group->baselist) && list_empty(&group->aliaslist)) {
 365                 list_del(&group->group);
 366                 kfree(group);
 367                 return;
 368         }
 369         if (group->next == device)
 370                 group->next = NULL;
 371 };
 372
 373 static int read_unit_address_configuration(struct dasd_device *device,
 374                                            struct alias_lcu *lcu)
 375 {
 376         struct dasd_psf_prssd_data *prssdp;
 377         struct dasd_ccw_req *cqr;
 378         struct ccw1 *ccw;
 379         int rc;
 380         unsigned long flags;
 381
 382         cqr = dasd_kmalloc_request(DASD_ECKD_MAGIC, 1 /* PSF */ + 1 /* RSSD */,
 383                                    (sizeof(struct dasd_psf_prssd_data)),
 384                                    device);
 385         if (IS_ERR(cqr))
 386                 return PTR_ERR(cqr);
 387         cqr->startdev = device;
 388         cqr->memdev = device;
 389         clear_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
 390         cqr->retries = 10;
 391         cqr->expires = 20 * HZ;
 392
 393         /* Prepare for Read Subsystem Data */
 394         prssdp = (struct dasd_psf_prssd_data *) cqr->data;
 395         memset(prssdp, 0, sizeof(struct dasd_psf_prssd_data));
 396         prssdp->order = PSF_ORDER_PRSSD;
 397         prssdp->suborder = 0x0e;        /* Read unit address configuration */
 398         /* all other bytes of prssdp must be zero */
 399
 400         ccw = cqr->cpaddr;
 401         ccw->cmd_code = DASD_ECKD_CCW_PSF;
 402         ccw->count = sizeof(struct dasd_psf_prssd_data);
 403         ccw->flags |= CCW_FLAG_CC;
 404         ccw->cda = (__u32)(addr_t) prssdp;
 405
 406         /* Read Subsystem Data - feature codes */
 407         memset(lcu->uac, 0, sizeof(*(lcu->uac)));
 408
 409         ccw++;
 410         ccw->cmd_code = DASD_ECKD_CCW_RSSD;
 411         ccw->count = sizeof(*(lcu->uac));
 412         ccw->cda = (__u32)(addr_t) lcu->uac;
 413
 414         cqr->buildclk = get_clock();
 415         cqr->status = DASD_CQR_FILLED;
 416
 417         /* need to unset flag here to detect race with summary unit check */
 418         spin_lock_irqsave(&lcu->lock, flags);
 419         lcu->flags &= ~NEED_UAC_UPDATE;
 420         spin_unlock_irqrestore(&lcu->lock, flags);
 421
 422         do {
 423                 rc = dasd_sleep_on(cqr);
 424         } while (rc && (cqr->retries > 0));
 425         if (rc) {
 426                 spin_lock_irqsave(&lcu->lock, flags);
 427                 lcu->flags |= NEED_UAC_UPDATE;
 428                 spin_unlock_irqrestore(&lcu->lock, flags);
 429         }
 430         dasd_kfree_request(cqr, cqr->memdev);
 431         return rc;
 432 }
 433
 434 static int _lcu_update(struct dasd_device *refdev, struct alias_lcu *lcu)
 435 {
 436         unsigned long flags;
 437         struct alias_pav_group *pavgroup, *tempgroup;
 438         struct dasd_device *device, *tempdev;
 439         int i, rc;
 440         struct dasd_eckd_private *private;
 441
 442         spin_lock_irqsave(&lcu->lock, flags);
 443         list_for_each_entry_safe(pavgroup, tempgroup, &lcu->grouplist, group) {
 444                 list_for_each_entry_safe(device, tempdev, &pavgroup->baselist,
 445                                          alias_list) {
 446                         list_move(&device->alias_list, &lcu->active_devices);
 447                         private = (struct dasd_eckd_private *) device->private;
 448                         private->pavgroup = NULL;
 449                 }
 450                 list_for_each_entry_safe(device, tempdev, &pavgroup->aliaslist,
 451                                          alias_list) {
 452                         list_move(&device->alias_list, &lcu->active_devices);
 453                         private = (struct dasd_eckd_private *) device->private;
 454                         private->pavgroup = NULL;
 455                 }
 456                 list_del(&pavgroup->group);
 457                 kfree(pavgroup);
 458         }
 459         spin_unlock_irqrestore(&lcu->lock, flags);
 460
 461         rc = read_unit_address_configuration(refdev, lcu);
 462         if (rc)
 463                 return rc;
 464
 465         spin_lock_irqsave(&lcu->lock, flags);
 466         lcu->pav = NO_PAV;
 467         for (i = 0; i < MAX_DEVICES_PER_LCU; ++i) {
 468                 switch (lcu->uac->unit[i].ua_type) {
 469                 case UA_BASE_PAV_ALIAS:
 470                         lcu->pav = BASE_PAV;
 471                         break;
 472                 case UA_HYPER_PAV_ALIAS:
 473                         lcu->pav = HYPER_PAV;
 474                         break;
 475                 }
 476                 if (lcu->pav != NO_PAV)
 477                         break;
 478         }
 479
 480         list_for_each_entry_safe(device, tempdev, &lcu->active_devices,
 481                                  alias_list) {
 482                 _add_device_to_lcu(lcu, device);
 483         }
 484         spin_unlock_irqrestore(&lcu->lock, flags);
 485         return 0;
 486 }
 487
 488 static void lcu_update_work(struct work_struct *work)
 489 {
 490         struct alias_lcu *lcu;
 491         struct read_uac_work_data *ruac_data;
 492         struct dasd_device *device;
 493         unsigned long flags;
 494         int rc;
 495
 496         ruac_data = container_of(work, struct read_uac_work_data, dwork.work);
 497         lcu = container_of(ruac_data, struct alias_lcu, ruac_data);
 498         device = ruac_data->device;
 499         rc = _lcu_update(device, lcu);
 500         /*
 501          * Need to check flags again, as there could have been another
 502          * prepare_update or a new device a new device while we were still
 503          * processing the data
 504          */
 505         spin_lock_irqsave(&lcu->lock, flags);
 506         if (rc || (lcu->flags & NEED_UAC_UPDATE)) {
 507                 DBF_DEV_EVENT(DBF_WARNING, device, "could not update"
 508                             " alias data in lcu (rc = %d), retry later", rc);
 509                 schedule_delayed_work(&lcu->ruac_data.dwork, 30*HZ);
 510         } else {
 511                 lcu->ruac_data.device = NULL;
 512                 lcu->flags &= ~UPDATE_PENDING;
 513         }
 514         spin_unlock_irqrestore(&lcu->lock, flags);
 515 }
 516
 517 static int _schedule_lcu_update(struct alias_lcu *lcu,
 518                                 struct dasd_device *device)
 519 {
 520         struct dasd_device *usedev = NULL;
 521         struct alias_pav_group *group;
 522
 523         lcu->flags |= NEED_UAC_UPDATE;
 524         if (lcu->ruac_data.device) {
 525                 /* already scheduled or running */
 526                 return 0;
 527         }
 528         if (device && !list_empty(&device->alias_list))
 529                 usedev = device;
 530
 531         if (!usedev && !list_empty(&lcu->grouplist)) {
 532                 group = list_first_entry(&lcu->grouplist,
 533                                          struct alias_pav_group, group);
 534                 if (!list_empty(&group->baselist))
 535                         usedev = list_first_entry(&group->baselist,
 536                                                   struct dasd_device,
 537                                                   alias_list);
 538                 else if (!list_empty(&group->aliaslist))
 539                         usedev = list_first_entry(&group->aliaslist,
 540                                                   struct dasd_device,
 541                                                   alias_list);
 542         }
 543         if (!usedev && !list_empty(&lcu->active_devices)) {
 544                 usedev = list_first_entry(&lcu->active_devices,
 545                                           struct dasd_device, alias_list);
 546         }
 547         /*
 548          * if we haven't found a proper device yet, give up for now, the next
 549          * device that will be set active will trigger an lcu update
 550          */
 551         if (!usedev)
 552                 return -EINVAL;
 553         lcu->ruac_data.device = usedev;
 554         schedule_delayed_work(&lcu->ruac_data.dwork, 0);
 555         return 0;
 556 }
 557
 558 int dasd_alias_add_device(struct dasd_device *device)
 559 {
 560         struct dasd_eckd_private *private;
 561         struct alias_lcu *lcu;
 562         unsigned long flags;
 563         int rc;
 564
 565         private = (struct dasd_eckd_private *) device->private;
 566         lcu = private->lcu;
 567         rc = 0;
 568         spin_lock_irqsave(&lcu->lock, flags);
 569         if (!(lcu->flags & UPDATE_PENDING)) {
 570                 rc = _add_device_to_lcu(lcu, device);
 571                 if (rc)
 572                         lcu->flags |= UPDATE_PENDING;
 573         }
 574         if (lcu->flags & UPDATE_PENDING) {
 575                 list_move(&device->alias_list, &lcu->active_devices);
 576                 _schedule_lcu_update(lcu, device);
 577         }
 578         spin_unlock_irqrestore(&lcu->lock, flags);
 579         return rc;
 580 }
 581
 582 int dasd_alias_remove_device(struct dasd_device *device)
 583 {
 584         struct dasd_eckd_private *private;
 585         struct alias_lcu *lcu;
 586         unsigned long flags;
 587
 588         private = (struct dasd_eckd_private *) device->private;
 589         lcu = private->lcu;
 590         spin_lock_irqsave(&lcu->lock, flags);
 591         _remove_device_from_lcu(lcu, device);
 592         spin_unlock_irqrestore(&lcu->lock, flags);
 593         return 0;
 594 }
 595
 596 struct dasd_device *dasd_alias_get_start_dev(struct dasd_device *base_device)
 597 {
 598
 599         struct dasd_device *alias_device;
 600         struct alias_pav_group *group;
 601         struct alias_lcu *lcu;
 602         struct dasd_eckd_private *private, *alias_priv;
 603         unsigned long flags;
 604
 605         private = (struct dasd_eckd_private *) base_device->private;
 606         group = private->pavgroup;
 607         lcu = private->lcu;
 608         if (!group || !lcu)
 609                 return NULL;
 610         if (lcu->pav == NO_PAV ||
 611             lcu->flags & (NEED_UAC_UPDATE | UPDATE_PENDING))
 612                 return NULL;
 613
 614         spin_lock_irqsave(&lcu->lock, flags);
 615         alias_device = group->next;
 616         if (!alias_device) {
 617                 if (list_empty(&group->aliaslist)) {
 618                         spin_unlock_irqrestore(&lcu->lock, flags);
 619                         return NULL;
 620                 } else {
 621                         alias_device = list_first_entry(&group->aliaslist,
 622                                                         struct dasd_device,
 623                                                         alias_list);
 624                 }
 625         }
 626         if (list_is_last(&alias_device->alias_list, &group->aliaslist))
 627                 group->next = list_first_entry(&group->aliaslist,
 628                                                struct dasd_device, alias_list);
 629         else
 630                 group->next = list_first_entry(&alias_device->alias_list,
 631                                                struct dasd_device, alias_list);
 632         spin_unlock_irqrestore(&lcu->lock, flags);
 633         alias_priv = (struct dasd_eckd_private *) alias_device->private;
 634         if ((alias_priv->count < private->count) && !alias_device->stopped)
 635                 return alias_device;
 636         else
 637                 return NULL;
 638 }
 639
 640 /*
 641  * Summary unit check handling depends on the way alias devices
 642  * are handled so it is done here rather then in dasd_eckd.c
 643  */
 644 static int reset_summary_unit_check(struct alias_lcu *lcu,
 645                                     struct dasd_device *device,
 646                                     char reason)
 647 {
 648         struct dasd_ccw_req *cqr;
 649         int rc = 0;
 650         struct ccw1 *ccw;
 651
 652         cqr = lcu->rsu_cqr;
 653         strncpy((char *) &cqr->magic, "ECKD", 4);
 654         ASCEBC((char *) &cqr->magic, 4);
 655         ccw = cqr->cpaddr;
 656         ccw->cmd_code = DASD_ECKD_CCW_RSCK;
 657         ccw->flags = 0 ;
 658         ccw->count = 16;
 659         ccw->cda = (__u32)(addr_t) cqr->data;
 660         ((char *)cqr->data)[0] = reason;
 661
 662         clear_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
 663         cqr->retries = 255;     /* set retry counter to enable basic ERP */
 664         cqr->startdev = device;
 665         cqr->memdev = device;
 666         cqr->block = NULL;
 667         cqr->expires = 5 * HZ;
 668         cqr->buildclk = get_clock();
 669         cqr->status = DASD_CQR_FILLED;
 670
 671         rc = dasd_sleep_on_immediatly(cqr);
 672         return rc;
 673 }
 674
 675 static void _restart_all_base_devices_on_lcu(struct alias_lcu *lcu)
 676 {
 677         struct alias_pav_group *pavgroup;
 678         struct dasd_device *device;
 679         struct dasd_eckd_private *private;
 680
 681         /* active and inactive list can contain alias as well as base devices */
 682         list_for_each_entry(device, &lcu->active_devices, alias_list) {
 683                 private = (struct dasd_eckd_private *) device->private;
 684                 if (private->uid.type != UA_BASE_DEVICE)
 685                         continue;
 686                 dasd_schedule_block_bh(device->block);
 687                 dasd_schedule_device_bh(device);
 688         }
 689         list_for_each_entry(device, &lcu->inactive_devices, alias_list) {
 690                 private = (struct dasd_eckd_private *) device->private;
 691                 if (private->uid.type != UA_BASE_DEVICE)
 692                         continue;
 693                 dasd_schedule_block_bh(device->block);
 694                 dasd_schedule_device_bh(device);
 695         }
 696         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 697                 list_for_each_entry(device, &pavgroup->baselist, alias_list) {
 698                         dasd_schedule_block_bh(device->block);
 699                         dasd_schedule_device_bh(device);
 700                 }
 701         }
 702 }
 703
 704 static void flush_all_alias_devices_on_lcu(struct alias_lcu *lcu)
 705 {
 706         struct alias_pav_group *pavgroup;
 707         struct dasd_device *device, *temp;
 708         struct dasd_eckd_private *private;
 709         int rc;
 710         unsigned long flags;
 711         LIST_HEAD(active);
 712
 713         /*
 714          * Problem here ist that dasd_flush_device_queue may wait
 715          * for termination of a request to complete. We can't keep
 716          * the lcu lock during that time, so we must assume that
 717          * the lists may have changed.
 718          * Idea: first gather all active alias devices in a separate list,
 719          * then flush the first element of this list unlocked, and afterwards
 720          * check if it is still on the list before moving it to the
 721          * active_devices list.
 722          */
 723
 724         spin_lock_irqsave(&lcu->lock, flags);
 725         list_for_each_entry_safe(device, temp, &lcu->active_devices,
 726                                  alias_list) {
 727                 private = (struct dasd_eckd_private *) device->private;
 728                 if (private->uid.type == UA_BASE_DEVICE)
 729                         continue;
 730                 list_move(&device->alias_list, &active);
 731         }
 732
 733         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 734                 list_splice_init(&pavgroup->aliaslist, &active);
 735         }
 736         while (!list_empty(&active)) {
 737                 device = list_first_entry(&active, struct dasd_device,
 738                                           alias_list);
 739                 spin_unlock_irqrestore(&lcu->lock, flags);
 740                 rc = dasd_flush_device_queue(device);
 741                 spin_lock_irqsave(&lcu->lock, flags);
 742                 /*
 743                  * only move device around if it wasn't moved away while we
 744                  * were waiting for the flush
 745                  */
 746                 if (device == list_first_entry(&active,
 747                                                struct dasd_device, alias_list))
 748                         list_move(&device->alias_list, &lcu->active_devices);
 749         }
 750         spin_unlock_irqrestore(&lcu->lock, flags);
 751 }
 752
 753 static void __stop_device_on_lcu(struct dasd_device *device,
 754                                  struct dasd_device *pos)
 755 {
 756         /* If pos == device then device is already locked! */
 757         if (pos == device) {
 758                 pos->stopped |= DASD_STOPPED_SU;
 759                 return;
 760         }
 761         spin_lock(get_ccwdev_lock(pos->cdev));
 762         pos->stopped |= DASD_STOPPED_SU;
 763         spin_unlock(get_ccwdev_lock(pos->cdev));
 764 }
 765
 766 /*
 767  * This function is called in interrupt context, so the
 768  * cdev lock for device is already locked!
 769  */
 770 static void _stop_all_devices_on_lcu(struct alias_lcu *lcu,
 771                                      struct dasd_device *device)
 772 {
 773         struct alias_pav_group *pavgroup;
 774         struct dasd_device *pos;
 775
 776         list_for_each_entry(pos, &lcu->active_devices, alias_list)
 777                 __stop_device_on_lcu(device, pos);
 778         list_for_each_entry(pos, &lcu->inactive_devices, alias_list)
 779                 __stop_device_on_lcu(device, pos);
 780         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 781                 list_for_each_entry(pos, &pavgroup->baselist, alias_list)
 782                         __stop_device_on_lcu(device, pos);
 783                 list_for_each_entry(pos, &pavgroup->aliaslist, alias_list)
 784                         __stop_device_on_lcu(device, pos);
 785         }
 786 }
 787
 788 static void _unstop_all_devices_on_lcu(struct alias_lcu *lcu)
 789 {
 790         struct alias_pav_group *pavgroup;
 791         struct dasd_device *device;
 792         unsigned long flags;
 793
 794         list_for_each_entry(device, &lcu->active_devices, alias_list) {
 795                 spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 796                 device->stopped &= ~DASD_STOPPED_SU;
 797                 spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 798         }
 799
 800         list_for_each_entry(device, &lcu->inactive_devices, alias_list) {
 801                 spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 802                 device->stopped &= ~DASD_STOPPED_SU;
 803                 spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 804         }
 805
 806         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 807                 list_for_each_entry(device, &pavgroup->baselist, alias_list) {
 808                         spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 809                         device->stopped &= ~DASD_STOPPED_SU;
 810                         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev),
 811                                                flags);
 812                 }
 813                 list_for_each_entry(device, &pavgroup->aliaslist, alias_list) {
 814                         spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 815                         device->stopped &= ~DASD_STOPPED_SU;
 816                         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev),
 817                                                flags);
 818                 }
 819         }
 820 }
 821
 822 static void summary_unit_check_handling_work(struct work_struct *work)
 823 {
 824         struct alias_lcu *lcu;
 825         struct summary_unit_check_work_data *suc_data;
 826         unsigned long flags;
 827         struct dasd_device *device;
 828
 829         suc_data = container_of(work, struct summary_unit_check_work_data,
 830                                 worker);
 831         lcu = container_of(suc_data, struct alias_lcu, suc_data);
 832         device = suc_data->device;
 833
 834         /* 1. flush alias devices */
 835         flush_all_alias_devices_on_lcu(lcu);
 836
 837         /* 2. reset summary unit check */
 838         spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 839         device->stopped &= ~(DASD_STOPPED_SU | DASD_STOPPED_PENDING);
 840         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 841         reset_summary_unit_check(lcu, device, suc_data->reason);
 842
 843         spin_lock_irqsave(&lcu->lock, flags);
 844         _unstop_all_devices_on_lcu(lcu);
 845         _restart_all_base_devices_on_lcu(lcu);
 846         /* 3. read new alias configuration */
 847         _schedule_lcu_update(lcu, device);
 848         lcu->suc_data.device = NULL;
 849         spin_unlock_irqrestore(&lcu->lock, flags);
 850 }
 851
 852 /*
 853  * note: this will be called from int handler context (cdev locked)
 854  */
 855 void dasd_alias_handle_summary_unit_check(struct dasd_device *device,
 856                                           struct irb *irb)
 857 {
 858         struct alias_lcu *lcu;
 859         char reason;
 860         struct dasd_eckd_private *private;
 861         char *sense;
 862
 863         private = (struct dasd_eckd_private *) device->private;
 864
 865         sense = dasd_get_sense(irb);
 866         if (sense) {
 867                 reason = sense[8];
 868                 DBF_DEV_EVENT(DBF_NOTICE, device, "%s %x",
 869                             "eckd handle summary unit check: reason", reason);
 870         } else {
 871                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
 872                             "eckd handle summary unit check:"
 873                             " no reason code available");
 874                 return;
 875         }
 876
 877         lcu = private->lcu;
 878         if (!lcu) {
 879                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
 880                             "device not ready to handle summary"
 881                             " unit check (no lcu structure)");
 882                 return;
 883         }
 884         spin_lock(&lcu->lock);
 885         _stop_all_devices_on_lcu(lcu, device);
 886         /* prepare for lcu_update */
 887         private->lcu->flags |= NEED_UAC_UPDATE | UPDATE_PENDING;
 888         /* If this device is about to be removed just return and wait for
 889          * the next interrupt on a different device
 890          */
 891         if (list_empty(&device->alias_list)) {
 892                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
 893                             "device is in offline processing,"
 894                             " don't do summary unit check handling");
 895                 spin_unlock(&lcu->lock);
 896                 return;
 897         }
 898         if (lcu->suc_data.device) {
 899                 /* already scheduled or running */
 900                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
 901                             "previous instance of summary unit check worker"
 902                             " still pending");
 903                 spin_unlock(&lcu->lock);
 904                 return ;
 905         }
 906         lcu->suc_data.reason = reason;
 907         lcu->suc_data.device = device;
 908         spin_unlock(&lcu->lock);
 909         schedule_work(&lcu->suc_data.worker);
 910 };