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"
   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("ECKD",
 383                                    1 /* PSF */  + 1 /* RSSD */ ,
 384                                    (sizeof(struct dasd_psf_prssd_data)),
 385                                    device);
 386         if (IS_ERR(cqr))
 387                 return PTR_ERR(cqr);
 388         cqr->startdev = device;
 389         cqr->memdev = device;
 390         clear_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
 391         cqr->retries = 10;
 392         cqr->expires = 20 * HZ;
 393
 394         /* Prepare for Read Subsystem Data */
 395         prssdp = (struct dasd_psf_prssd_data *) cqr->data;
 396         memset(prssdp, 0, sizeof(struct dasd_psf_prssd_data));
 397         prssdp->order = PSF_ORDER_PRSSD;
 398         prssdp->suborder = 0x0e;        /* Read unit address configuration */
 399         /* all other bytes of prssdp must be zero */
 400
 401         ccw = cqr->cpaddr;
 402         ccw->cmd_code = DASD_ECKD_CCW_PSF;
 403         ccw->count = sizeof(struct dasd_psf_prssd_data);
 404         ccw->flags |= CCW_FLAG_CC;
 405         ccw->cda = (__u32)(addr_t) prssdp;
 406
 407         /* Read Subsystem Data - feature codes */
 408         memset(lcu->uac, 0, sizeof(*(lcu->uac)));
 409
 410         ccw++;
 411         ccw->cmd_code = DASD_ECKD_CCW_RSSD;
 412         ccw->count = sizeof(*(lcu->uac));
 413         ccw->cda = (__u32)(addr_t) lcu->uac;
 414
 415         cqr->buildclk = get_clock();
 416         cqr->status = DASD_CQR_FILLED;
 417
 418         /* need to unset flag here to detect race with summary unit check */
 419         spin_lock_irqsave(&lcu->lock, flags);
 420         lcu->flags &= ~NEED_UAC_UPDATE;
 421         spin_unlock_irqrestore(&lcu->lock, flags);
 422
 423         do {
 424                 rc = dasd_sleep_on(cqr);
 425         } while (rc && (cqr->retries > 0));
 426         if (rc) {
 427                 spin_lock_irqsave(&lcu->lock, flags);
 428                 lcu->flags |= NEED_UAC_UPDATE;
 429                 spin_unlock_irqrestore(&lcu->lock, flags);
 430         }
 431         dasd_kfree_request(cqr, cqr->memdev);
 432         return rc;
 433 }
 434
 435 static int _lcu_update(struct dasd_device *refdev, struct alias_lcu *lcu)
 436 {
 437         unsigned long flags;
 438         struct alias_pav_group *pavgroup, *tempgroup;
 439         struct dasd_device *device, *tempdev;
 440         int i, rc;
 441         struct dasd_eckd_private *private;
 442
 443         spin_lock_irqsave(&lcu->lock, flags);
 444         list_for_each_entry_safe(pavgroup, tempgroup, &lcu->grouplist, group) {
 445                 list_for_each_entry_safe(device, tempdev, &pavgroup->baselist,
 446                                          alias_list) {
 447                         list_move(&device->alias_list, &lcu->active_devices);
 448                         private = (struct dasd_eckd_private *) device->private;
 449                         private->pavgroup = NULL;
 450                 }
 451                 list_for_each_entry_safe(device, tempdev, &pavgroup->aliaslist,
 452                                          alias_list) {
 453                         list_move(&device->alias_list, &lcu->active_devices);
 454                         private = (struct dasd_eckd_private *) device->private;
 455                         private->pavgroup = NULL;
 456                 }
 457                 list_del(&pavgroup->group);
 458                 kfree(pavgroup);
 459         }
 460         spin_unlock_irqrestore(&lcu->lock, flags);
 461
 462         rc = read_unit_address_configuration(refdev, lcu);
 463         if (rc)
 464                 return rc;
 465
 466         spin_lock_irqsave(&lcu->lock, flags);
 467         lcu->pav = NO_PAV;
 468         for (i = 0; i < MAX_DEVICES_PER_LCU; ++i) {
 469                 switch (lcu->uac->unit[i].ua_type) {
 470                 case UA_BASE_PAV_ALIAS:
 471                         lcu->pav = BASE_PAV;
 472                         break;
 473                 case UA_HYPER_PAV_ALIAS:
 474                         lcu->pav = HYPER_PAV;
 475                         break;
 476                 }
 477                 if (lcu->pav != NO_PAV)
 478                         break;
 479         }
 480
 481         list_for_each_entry_safe(device, tempdev, &lcu->active_devices,
 482                                  alias_list) {
 483                 _add_device_to_lcu(lcu, device);
 484         }
 485         spin_unlock_irqrestore(&lcu->lock, flags);
 486         return 0;
 487 }
 488
 489 static void lcu_update_work(struct work_struct *work)
 490 {
 491         struct alias_lcu *lcu;
 492         struct read_uac_work_data *ruac_data;
 493         struct dasd_device *device;
 494         unsigned long flags;
 495         int rc;
 496
 497         ruac_data = container_of(work, struct read_uac_work_data, dwork.work);
 498         lcu = container_of(ruac_data, struct alias_lcu, ruac_data);
 499         device = ruac_data->device;
 500         rc = _lcu_update(device, lcu);
 501         /*
 502          * Need to check flags again, as there could have been another
 503          * prepare_update or a new device a new device while we were still
 504          * processing the data
 505          */
 506         spin_lock_irqsave(&lcu->lock, flags);
 507         if (rc || (lcu->flags & NEED_UAC_UPDATE)) {
 508                 DBF_DEV_EVENT(DBF_WARNING, device, "could not update"
 509                             " alias data in lcu (rc = %d), retry later", rc);
 510                 schedule_delayed_work(&lcu->ruac_data.dwork, 30*HZ);
 511         } else {
 512                 lcu->ruac_data.device = NULL;
 513                 lcu->flags &= ~UPDATE_PENDING;
 514         }
 515         spin_unlock_irqrestore(&lcu->lock, flags);
 516 }
 517
 518 static int _schedule_lcu_update(struct alias_lcu *lcu,
 519                                 struct dasd_device *device)
 520 {
 521         struct dasd_device *usedev = NULL;
 522         struct alias_pav_group *group;
 523
 524         lcu->flags |= NEED_UAC_UPDATE;
 525         if (lcu->ruac_data.device) {
 526                 /* already scheduled or running */
 527                 return 0;
 528         }
 529         if (device && !list_empty(&device->alias_list))
 530                 usedev = device;
 531
 532         if (!usedev && !list_empty(&lcu->grouplist)) {
 533                 group = list_first_entry(&lcu->grouplist,
 534                                          struct alias_pav_group, group);
 535                 if (!list_empty(&group->baselist))
 536                         usedev = list_first_entry(&group->baselist,
 537                                                   struct dasd_device,
 538                                                   alias_list);
 539                 else if (!list_empty(&group->aliaslist))
 540                         usedev = list_first_entry(&group->aliaslist,
 541                                                   struct dasd_device,
 542                                                   alias_list);
 543         }
 544         if (!usedev && !list_empty(&lcu->active_devices)) {
 545                 usedev = list_first_entry(&lcu->active_devices,
 546                                           struct dasd_device, alias_list);
 547         }
 548         /*
 549          * if we haven't found a proper device yet, give up for now, the next
 550          * device that will be set active will trigger an lcu update
 551          */
 552         if (!usedev)
 553                 return -EINVAL;
 554         lcu->ruac_data.device = usedev;
 555         schedule_delayed_work(&lcu->ruac_data.dwork, 0);
 556         return 0;
 557 }
 558
 559 int dasd_alias_add_device(struct dasd_device *device)
 560 {
 561         struct dasd_eckd_private *private;
 562         struct alias_lcu *lcu;
 563         unsigned long flags;
 564         int rc;
 565
 566         private = (struct dasd_eckd_private *) device->private;
 567         lcu = private->lcu;
 568         rc = 0;
 569         spin_lock_irqsave(&lcu->lock, flags);
 570         if (!(lcu->flags & UPDATE_PENDING)) {
 571                 rc = _add_device_to_lcu(lcu, device);
 572                 if (rc)
 573                         lcu->flags |= UPDATE_PENDING;
 574         }
 575         if (lcu->flags & UPDATE_PENDING) {
 576                 list_move(&device->alias_list, &lcu->active_devices);
 577                 _schedule_lcu_update(lcu, device);
 578         }
 579         spin_unlock_irqrestore(&lcu->lock, flags);
 580         return rc;
 581 }
 582
 583 int dasd_alias_remove_device(struct dasd_device *device)
 584 {
 585         struct dasd_eckd_private *private;
 586         struct alias_lcu *lcu;
 587         unsigned long flags;
 588
 589         private = (struct dasd_eckd_private *) device->private;
 590         lcu = private->lcu;
 591         spin_lock_irqsave(&lcu->lock, flags);
 592         _remove_device_from_lcu(lcu, device);
 593         spin_unlock_irqrestore(&lcu->lock, flags);
 594         return 0;
 595 }
 596
 597 struct dasd_device *dasd_alias_get_start_dev(struct dasd_device *base_device)
 598 {
 599
 600         struct dasd_device *alias_device;
 601         struct alias_pav_group *group;
 602         struct alias_lcu *lcu;
 603         struct dasd_eckd_private *private, *alias_priv;
 604         unsigned long flags;
 605
 606         private = (struct dasd_eckd_private *) base_device->private;
 607         group = private->pavgroup;
 608         lcu = private->lcu;
 609         if (!group || !lcu)
 610                 return NULL;
 611         if (lcu->pav == NO_PAV ||
 612             lcu->flags & (NEED_UAC_UPDATE | UPDATE_PENDING))
 613                 return NULL;
 614
 615         spin_lock_irqsave(&lcu->lock, flags);
 616         alias_device = group->next;
 617         if (!alias_device) {
 618                 if (list_empty(&group->aliaslist)) {
 619                         spin_unlock_irqrestore(&lcu->lock, flags);
 620                         return NULL;
 621                 } else {
 622                         alias_device = list_first_entry(&group->aliaslist,
 623                                                         struct dasd_device,
 624                                                         alias_list);
 625                 }
 626         }
 627         if (list_is_last(&alias_device->alias_list, &group->aliaslist))
 628                 group->next = list_first_entry(&group->aliaslist,
 629                                                struct dasd_device, alias_list);
 630         else
 631                 group->next = list_first_entry(&alias_device->alias_list,
 632                                                struct dasd_device, alias_list);
 633         spin_unlock_irqrestore(&lcu->lock, flags);
 634         alias_priv = (struct dasd_eckd_private *) alias_device->private;
 635         if ((alias_priv->count < private->count) && !alias_device->stopped)
 636                 return alias_device;
 637         else
 638                 return NULL;
 639 }
 640
 641 /*
 642  * Summary unit check handling depends on the way alias devices
 643  * are handled so it is done here rather then in dasd_eckd.c
 644  */
 645 static int reset_summary_unit_check(struct alias_lcu *lcu,
 646                                     struct dasd_device *device,
 647                                     char reason)
 648 {
 649         struct dasd_ccw_req *cqr;
 650         int rc = 0;
 651         struct ccw1 *ccw;
 652
 653         cqr = lcu->rsu_cqr;
 654         strncpy((char *) &cqr->magic, "ECKD", 4);
 655         ASCEBC((char *) &cqr->magic, 4);
 656         ccw = cqr->cpaddr;
 657         ccw->cmd_code = DASD_ECKD_CCW_RSCK;
 658         ccw->flags = 0 ;
 659         ccw->count = 16;
 660         ccw->cda = (__u32)(addr_t) cqr->data;
 661         ((char *)cqr->data)[0] = reason;
 662
 663         clear_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
 664         cqr->retries = 255;     /* set retry counter to enable basic ERP */
 665         cqr->startdev = device;
 666         cqr->memdev = device;
 667         cqr->block = NULL;
 668         cqr->expires = 5 * HZ;
 669         cqr->buildclk = get_clock();
 670         cqr->status = DASD_CQR_FILLED;
 671
 672         rc = dasd_sleep_on_immediatly(cqr);
 673         return rc;
 674 }
 675
 676 static void _restart_all_base_devices_on_lcu(struct alias_lcu *lcu)
 677 {
 678         struct alias_pav_group *pavgroup;
 679         struct dasd_device *device;
 680         struct dasd_eckd_private *private;
 681
 682         /* active and inactive list can contain alias as well as base devices */
 683         list_for_each_entry(device, &lcu->active_devices, alias_list) {
 684                 private = (struct dasd_eckd_private *) device->private;
 685                 if (private->uid.type != UA_BASE_DEVICE)
 686                         continue;
 687                 dasd_schedule_block_bh(device->block);
 688                 dasd_schedule_device_bh(device);
 689         }
 690         list_for_each_entry(device, &lcu->inactive_devices, alias_list) {
 691                 private = (struct dasd_eckd_private *) device->private;
 692                 if (private->uid.type != UA_BASE_DEVICE)
 693                         continue;
 694                 dasd_schedule_block_bh(device->block);
 695                 dasd_schedule_device_bh(device);
 696         }
 697         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 698                 list_for_each_entry(device, &pavgroup->baselist, alias_list) {
 699                         dasd_schedule_block_bh(device->block);
 700                         dasd_schedule_device_bh(device);
 701                 }
 702         }
 703 }
 704
 705 static void flush_all_alias_devices_on_lcu(struct alias_lcu *lcu)
 706 {
 707         struct alias_pav_group *pavgroup;
 708         struct dasd_device *device, *temp;
 709         struct dasd_eckd_private *private;
 710         int rc;
 711         unsigned long flags;
 712         LIST_HEAD(active);
 713
 714         /*
 715          * Problem here ist that dasd_flush_device_queue may wait
 716          * for termination of a request to complete. We can't keep
 717          * the lcu lock during that time, so we must assume that
 718          * the lists may have changed.
 719          * Idea: first gather all active alias devices in a separate list,
 720          * then flush the first element of this list unlocked, and afterwards
 721          * check if it is still on the list before moving it to the
 722          * active_devices list.
 723          */
 724
 725         spin_lock_irqsave(&lcu->lock, flags);
 726         list_for_each_entry_safe(device, temp, &lcu->active_devices,
 727                                  alias_list) {
 728                 private = (struct dasd_eckd_private *) device->private;
 729                 if (private->uid.type == UA_BASE_DEVICE)
 730                         continue;
 731                 list_move(&device->alias_list, &active);
 732         }
 733
 734         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 735                 list_splice_init(&pavgroup->aliaslist, &active);
 736         }
 737         while (!list_empty(&active)) {
 738                 device = list_first_entry(&active, struct dasd_device,
 739                                           alias_list);
 740                 spin_unlock_irqrestore(&lcu->lock, flags);
 741                 rc = dasd_flush_device_queue(device);
 742                 spin_lock_irqsave(&lcu->lock, flags);
 743                 /*
 744                  * only move device around if it wasn't moved away while we
 745                  * were waiting for the flush
 746                  */
 747                 if (device == list_first_entry(&active,
 748                                                struct dasd_device, alias_list))
 749                         list_move(&device->alias_list, &lcu->active_devices);
 750         }
 751         spin_unlock_irqrestore(&lcu->lock, flags);
 752 }
 753
 754 static void __stop_device_on_lcu(struct dasd_device *device,
 755                                  struct dasd_device *pos)
 756 {
 757         /* If pos == device then device is already locked! */
 758         if (pos == device) {
 759                 pos->stopped |= DASD_STOPPED_SU;
 760                 return;
 761         }
 762         spin_lock(get_ccwdev_lock(pos->cdev));
 763         pos->stopped |= DASD_STOPPED_SU;
 764         spin_unlock(get_ccwdev_lock(pos->cdev));
 765 }
 766
 767 /*
 768  * This function is called in interrupt context, so the
 769  * cdev lock for device is already locked!
 770  */
 771 static void _stop_all_devices_on_lcu(struct alias_lcu *lcu,
 772                                      struct dasd_device *device)
 773 {
 774         struct alias_pav_group *pavgroup;
 775         struct dasd_device *pos;
 776
 777         list_for_each_entry(pos, &lcu->active_devices, alias_list)
 778                 __stop_device_on_lcu(device, pos);
 779         list_for_each_entry(pos, &lcu->inactive_devices, alias_list)
 780                 __stop_device_on_lcu(device, pos);
 781         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 782                 list_for_each_entry(pos, &pavgroup->baselist, alias_list)
 783                         __stop_device_on_lcu(device, pos);
 784                 list_for_each_entry(pos, &pavgroup->aliaslist, alias_list)
 785                         __stop_device_on_lcu(device, pos);
 786         }
 787 }
 788
 789 static void _unstop_all_devices_on_lcu(struct alias_lcu *lcu)
 790 {
 791         struct alias_pav_group *pavgroup;
 792         struct dasd_device *device;
 793         unsigned long flags;
 794
 795         list_for_each_entry(device, &lcu->active_devices, alias_list) {
 796                 spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 797                 device->stopped &= ~DASD_STOPPED_SU;
 798                 spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 799         }
 800
 801         list_for_each_entry(device, &lcu->inactive_devices, alias_list) {
 802                 spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 803                 device->stopped &= ~DASD_STOPPED_SU;
 804                 spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 805         }
 806
 807         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 808                 list_for_each_entry(device, &pavgroup->baselist, alias_list) {
 809                         spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 810                         device->stopped &= ~DASD_STOPPED_SU;
 811                         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev),
 812                                                flags);
 813                 }
 814                 list_for_each_entry(device, &pavgroup->aliaslist, alias_list) {
 815                         spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 816                         device->stopped &= ~DASD_STOPPED_SU;
 817                         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev),
 818                                                flags);
 819                 }
 820         }
 821 }
 822
 823 static void summary_unit_check_handling_work(struct work_struct *work)
 824 {
 825         struct alias_lcu *lcu;
 826         struct summary_unit_check_work_data *suc_data;
 827         unsigned long flags;
 828         struct dasd_device *device;
 829
 830         suc_data = container_of(work, struct summary_unit_check_work_data,
 831                                 worker);
 832         lcu = container_of(suc_data, struct alias_lcu, suc_data);
 833         device = suc_data->device;
 834
 835         /* 1. flush alias devices */
 836         flush_all_alias_devices_on_lcu(lcu);
 837
 838         /* 2. reset summary unit check */
 839         spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 840         device->stopped &= ~(DASD_STOPPED_SU | DASD_STOPPED_PENDING);
 841         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 842         reset_summary_unit_check(lcu, device, suc_data->reason);
 843
 844         spin_lock_irqsave(&lcu->lock, flags);
 845         _unstop_all_devices_on_lcu(lcu);
 846         _restart_all_base_devices_on_lcu(lcu);
 847         /* 3. read new alias configuration */
 848         _schedule_lcu_update(lcu, device);
 849         lcu->suc_data.device = NULL;
 850         spin_unlock_irqrestore(&lcu->lock, flags);
 851 }
 852
 853 /*
 854  * note: this will be called from int handler context (cdev locked)
 855  */
 856 void dasd_alias_handle_summary_unit_check(struct dasd_device *device,
 857                                           struct irb *irb)
 858 {
 859         struct alias_lcu *lcu;
 860         char reason;
 861         struct dasd_eckd_private *private;
 862         char *sense;
 863
 864         private = (struct dasd_eckd_private *) device->private;
 865
 866         sense = dasd_get_sense(irb);
 867         if (sense) {
 868                 reason = sense[8];
 869                 DBF_DEV_EVENT(DBF_NOTICE, device, "%s %x",
 870                             "eckd handle summary unit check: reason", reason);
 871         } else {
 872                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
 873                             "eckd handle summary unit check:"
 874                             " no reason code available");
 875                 return;
 876         }
 877
 878         lcu = private->lcu;
 879         if (!lcu) {
 880                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
 881                             "device not ready to handle summary"
 882                             " unit check (no lcu structure)");
 883                 return;
 884         }
 885         spin_lock(&lcu->lock);
 886         _stop_all_devices_on_lcu(lcu, device);
 887         /* prepare for lcu_update */
 888         private->lcu->flags |= NEED_UAC_UPDATE | UPDATE_PENDING;
 889         /* If this device is about to be removed just return and wait for
 890          * the next interrupt on a different device
 891          */
 892         if (list_empty(&device->alias_list)) {
 893                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
 894                             "device is in offline processing,"
 895                             " don't do summary unit check handling");
 896                 spin_unlock(&lcu->lock);
 897                 return;
 898         }
 899         if (lcu->suc_data.device) {
 900                 /* already scheduled or running */
 901                 DBF_DEV_EVENT(DBF_WARNING, device, "%s",
 902                             "previous instance of summary unit check worker"
 903                             " still pending");
 904                 spin_unlock(&lcu->lock);
 905                 return ;
 906         }
 907         lcu->suc_data.reason = reason;
 908         lcu->suc_data.device = device;
 909         spin_unlock(&lcu->lock);
 910         schedule_work(&lcu->suc_data.worker);
 911 };