git.oblomov.eu Git - linux-2.6/blob - 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 #include <linux/list.h>
   9 #include <asm/ebcdic.h>
  10 #include "dasd_int.h"
  11 #include "dasd_eckd.h"
  12
  13 #ifdef PRINTK_HEADER
  14 #undef PRINTK_HEADER
  15 #endif                          /* PRINTK_HEADER */
  16 #define PRINTK_HEADER "dasd(eckd):"
  17
  18
  19 /*
  20  * General concept of alias management:
  21  * - PAV and DASD alias management is specific to the eckd discipline.
  22  * - A device is connected to an lcu as long as the device exists.
  23  *   dasd_alias_make_device_known_to_lcu will be called wenn the
  24  *   device is checked by the eckd discipline and
  25  *   dasd_alias_disconnect_device_from_lcu will be called
  26  *   before the device is deleted.
  27  * - The dasd_alias_add_device / dasd_alias_remove_device
  28  *   functions mark the point when a device is 'ready for service'.
  29  * - A summary unit check is a rare occasion, but it is mandatory to
  30  *   support it. It requires some complex recovery actions before the
  31  *   devices can be used again (see dasd_alias_handle_summary_unit_check).
  32  * - dasd_alias_get_start_dev will find an alias device that can be used
  33  *   instead of the base device and does some (very simple) load balancing.
  34  *   This is the function that gets called for each I/O, so when improving
  35  *   something, this function should get faster or better, the rest has just
  36  *   to be correct.
  37  */
  38
  39
  40 static void summary_unit_check_handling_work(struct work_struct *);
  41 static void lcu_update_work(struct work_struct *);
  42 static int _schedule_lcu_update(struct alias_lcu *, struct dasd_device *);
  43
  44 static struct alias_root aliastree = {
  45         .serverlist = LIST_HEAD_INIT(aliastree.serverlist),
  46         .lock = __SPIN_LOCK_UNLOCKED(aliastree.lock),
  47 };
  48
  49 static struct alias_server *_find_server(struct dasd_uid *uid)
  50 {
  51         struct alias_server *pos;
  52         list_for_each_entry(pos, &aliastree.serverlist, server) {
  53                 if (!strncmp(pos->uid.vendor, uid->vendor,
  54                              sizeof(uid->vendor))
  55                     && !strncmp(pos->uid.serial, uid->serial,
  56                                 sizeof(uid->serial)))
  57                         return pos;
  58         };
  59         return NULL;
  60 }
  61
  62 static struct alias_lcu *_find_lcu(struct alias_server *server,
  63                                    struct dasd_uid *uid)
  64 {
  65         struct alias_lcu *pos;
  66         list_for_each_entry(pos, &server->lculist, lcu) {
  67                 if (pos->uid.ssid == uid->ssid)
  68                         return pos;
  69         };
  70         return NULL;
  71 }
  72
  73 static struct alias_pav_group *_find_group(struct alias_lcu *lcu,
  74                                            struct dasd_uid *uid)
  75 {
  76         struct alias_pav_group *pos;
  77         __u8 search_unit_addr;
  78
  79         /* for hyper pav there is only one group */
  80         if (lcu->pav == HYPER_PAV) {
  81                 if (list_empty(&lcu->grouplist))
  82                         return NULL;
  83                 else
  84                         return list_first_entry(&lcu->grouplist,
  85                                                 struct alias_pav_group, group);
  86         }
  87
  88         /* for base pav we have to find the group that matches the base */
  89         if (uid->type == UA_BASE_DEVICE)
  90                 search_unit_addr = uid->real_unit_addr;
  91         else
  92                 search_unit_addr = uid->base_unit_addr;
  93         list_for_each_entry(pos, &lcu->grouplist, group) {
  94                 if (pos->uid.base_unit_addr == search_unit_addr)
  95                         return pos;
  96         };
  97         return NULL;
  98 }
  99
 100 static struct alias_server *_allocate_server(struct dasd_uid *uid)
 101 {
 102         struct alias_server *server;
 103
 104         server = kzalloc(sizeof(*server), GFP_KERNEL);
 105         if (!server)
 106                 return ERR_PTR(-ENOMEM);
 107         memcpy(server->uid.vendor, uid->vendor, sizeof(uid->vendor));
 108         memcpy(server->uid.serial, uid->serial, sizeof(uid->serial));
 109         INIT_LIST_HEAD(&server->server);
 110         INIT_LIST_HEAD(&server->lculist);
 111         return server;
 112 }
 113
 114 static void _free_server(struct alias_server *server)
 115 {
 116         kfree(server);
 117 }
 118
 119 static struct alias_lcu *_allocate_lcu(struct dasd_uid *uid)
 120 {
 121         struct alias_lcu *lcu;
 122
 123         lcu = kzalloc(sizeof(*lcu), GFP_KERNEL);
 124         if (!lcu)
 125                 return ERR_PTR(-ENOMEM);
 126         lcu->uac = kzalloc(sizeof(*(lcu->uac)), GFP_KERNEL | GFP_DMA);
 127         if (!lcu->uac)
 128                 goto out_err1;
 129         lcu->rsu_cqr = kzalloc(sizeof(*lcu->rsu_cqr), GFP_KERNEL | GFP_DMA);
 130         if (!lcu->rsu_cqr)
 131                 goto out_err2;
 132         lcu->rsu_cqr->cpaddr = kzalloc(sizeof(struct ccw1),
 133                                        GFP_KERNEL | GFP_DMA);
 134         if (!lcu->rsu_cqr->cpaddr)
 135                 goto out_err3;
 136         lcu->rsu_cqr->data = kzalloc(16, GFP_KERNEL | GFP_DMA);
 137         if (!lcu->rsu_cqr->data)
 138                 goto out_err4;
 139
 140         memcpy(lcu->uid.vendor, uid->vendor, sizeof(uid->vendor));
 141         memcpy(lcu->uid.serial, uid->serial, sizeof(uid->serial));
 142         lcu->uid.ssid = uid->ssid;
 143         lcu->pav = NO_PAV;
 144         lcu->flags = NEED_UAC_UPDATE | UPDATE_PENDING;
 145         INIT_LIST_HEAD(&lcu->lcu);
 146         INIT_LIST_HEAD(&lcu->inactive_devices);
 147         INIT_LIST_HEAD(&lcu->active_devices);
 148         INIT_LIST_HEAD(&lcu->grouplist);
 149         INIT_WORK(&lcu->suc_data.worker, summary_unit_check_handling_work);
 150         INIT_DELAYED_WORK(&lcu->ruac_data.dwork, lcu_update_work);
 151         spin_lock_init(&lcu->lock);
 152         return lcu;
 153
 154 out_err4:
 155         kfree(lcu->rsu_cqr->cpaddr);
 156 out_err3:
 157         kfree(lcu->rsu_cqr);
 158 out_err2:
 159         kfree(lcu->uac);
 160 out_err1:
 161         kfree(lcu);
 162         return ERR_PTR(-ENOMEM);
 163 }
 164
 165 static void _free_lcu(struct alias_lcu *lcu)
 166 {
 167         kfree(lcu->rsu_cqr->data);
 168         kfree(lcu->rsu_cqr->cpaddr);
 169         kfree(lcu->rsu_cqr);
 170         kfree(lcu->uac);
 171         kfree(lcu);
 172 }
 173
 174 /*
 175  * This is the function that will allocate all the server and lcu data,
 176  * so this function must be called first for a new device.
 177  * If the return value is 1, the lcu was already known before, if it
 178  * is 0, this is a new lcu.
 179  * Negative return code indicates that something went wrong (e.g. -ENOMEM)
 180  */
 181 int dasd_alias_make_device_known_to_lcu(struct dasd_device *device)
 182 {
 183         struct dasd_eckd_private *private;
 184         unsigned long flags;
 185         struct alias_server *server, *newserver;
 186         struct alias_lcu *lcu, *newlcu;
 187         int is_lcu_known;
 188         struct dasd_uid *uid;
 189
 190         private = (struct dasd_eckd_private *) device->private;
 191         uid = &private->uid;
 192         spin_lock_irqsave(&aliastree.lock, flags);
 193         is_lcu_known = 1;
 194         server = _find_server(uid);
 195         if (!server) {
 196                 spin_unlock_irqrestore(&aliastree.lock, flags);
 197                 newserver = _allocate_server(uid);
 198                 if (IS_ERR(newserver))
 199                         return PTR_ERR(newserver);
 200                 spin_lock_irqsave(&aliastree.lock, flags);
 201                 server = _find_server(uid);
 202                 if (!server) {
 203                         list_add(&newserver->server, &aliastree.serverlist);
 204                         server = newserver;
 205                         is_lcu_known = 0;
 206                 } else {
 207                         /* someone was faster */
 208                         _free_server(newserver);
 209                 }
 210         }
 211
 212         lcu = _find_lcu(server, uid);
 213         if (!lcu) {
 214                 spin_unlock_irqrestore(&aliastree.lock, flags);
 215                 newlcu = _allocate_lcu(uid);
 216                 if (IS_ERR(newlcu))
 217                         return PTR_ERR(lcu);
 218                 spin_lock_irqsave(&aliastree.lock, flags);
 219                 lcu = _find_lcu(server, uid);
 220                 if (!lcu) {
 221                         list_add(&newlcu->lcu, &server->lculist);
 222                         lcu = newlcu;
 223                         is_lcu_known = 0;
 224                 } else {
 225                         /* someone was faster */
 226                         _free_lcu(newlcu);
 227                 }
 228                 is_lcu_known = 0;
 229         }
 230         spin_lock(&lcu->lock);
 231         list_add(&device->alias_list, &lcu->inactive_devices);
 232         private->lcu = lcu;
 233         spin_unlock(&lcu->lock);
 234         spin_unlock_irqrestore(&aliastree.lock, flags);
 235
 236         return is_lcu_known;
 237 }
 238
 239 /*
 240  * This function removes a device from the scope of alias management.
 241  * The complicated part is to make sure that it is not in use by
 242  * any of the workers. If necessary cancel the work.
 243  */
 244 void dasd_alias_disconnect_device_from_lcu(struct dasd_device *device)
 245 {
 246         struct dasd_eckd_private *private;
 247         unsigned long flags;
 248         struct alias_lcu *lcu;
 249         struct alias_server *server;
 250         int was_pending;
 251
 252         private = (struct dasd_eckd_private *) device->private;
 253         lcu = private->lcu;
 254         spin_lock_irqsave(&lcu->lock, flags);
 255         list_del_init(&device->alias_list);
 256         /* make sure that the workers don't use this device */
 257         if (device == lcu->suc_data.device) {
 258                 spin_unlock_irqrestore(&lcu->lock, flags);
 259                 cancel_work_sync(&lcu->suc_data.worker);
 260                 spin_lock_irqsave(&lcu->lock, flags);
 261                 if (device == lcu->suc_data.device)
 262                         lcu->suc_data.device = NULL;
 263         }
 264         was_pending = 0;
 265         if (device == lcu->ruac_data.device) {
 266                 spin_unlock_irqrestore(&lcu->lock, flags);
 267                 was_pending = 1;
 268                 cancel_delayed_work_sync(&lcu->ruac_data.dwork);
 269                 spin_lock_irqsave(&lcu->lock, flags);
 270                 if (device == lcu->ruac_data.device)
 271                         lcu->ruac_data.device = NULL;
 272         }
 273         private->lcu = NULL;
 274         spin_unlock_irqrestore(&lcu->lock, flags);
 275
 276         spin_lock_irqsave(&aliastree.lock, flags);
 277         spin_lock(&lcu->lock);
 278         if (list_empty(&lcu->grouplist) &&
 279             list_empty(&lcu->active_devices) &&
 280             list_empty(&lcu->inactive_devices)) {
 281                 list_del(&lcu->lcu);
 282                 spin_unlock(&lcu->lock);
 283                 _free_lcu(lcu);
 284                 lcu = NULL;
 285         } else {
 286                 if (was_pending)
 287                         _schedule_lcu_update(lcu, NULL);
 288                 spin_unlock(&lcu->lock);
 289         }
 290         server = _find_server(&private->uid);
 291         if (server && list_empty(&server->lculist)) {
 292                 list_del(&server->server);
 293                 _free_server(server);
 294         }
 295         spin_unlock_irqrestore(&aliastree.lock, flags);
 296 }
 297
 298 /*
 299  * This function assumes that the unit address configuration stored
 300  * in the lcu is up to date and will update the device uid before
 301  * adding it to a pav group.
 302  */
 303 static int _add_device_to_lcu(struct alias_lcu *lcu,
 304                               struct dasd_device *device)
 305 {
 306
 307         struct dasd_eckd_private *private;
 308         struct alias_pav_group *group;
 309         struct dasd_uid *uid;
 310
 311         private = (struct dasd_eckd_private *) device->private;
 312         uid = &private->uid;
 313         uid->type = lcu->uac->unit[uid->real_unit_addr].ua_type;
 314         uid->base_unit_addr = lcu->uac->unit[uid->real_unit_addr].base_ua;
 315         dasd_set_uid(device->cdev, &private->uid);
 316
 317         /* if we have no PAV anyway, we don't need to bother with PAV groups */
 318         if (lcu->pav == NO_PAV) {
 319                 list_move(&device->alias_list, &lcu->active_devices);
 320                 return 0;
 321         }
 322
 323         group = _find_group(lcu, uid);
 324         if (!group) {
 325                 group = kzalloc(sizeof(*group), GFP_ATOMIC);
 326                 if (!group)
 327                         return -ENOMEM;
 328                 memcpy(group->uid.vendor, uid->vendor, sizeof(uid->vendor));
 329                 memcpy(group->uid.serial, uid->serial, sizeof(uid->serial));
 330                 group->uid.ssid = uid->ssid;
 331                 if (uid->type == UA_BASE_DEVICE)
 332                         group->uid.base_unit_addr = uid->real_unit_addr;
 333                 else
 334                         group->uid.base_unit_addr = uid->base_unit_addr;
 335                 INIT_LIST_HEAD(&group->group);
 336                 INIT_LIST_HEAD(&group->baselist);
 337                 INIT_LIST_HEAD(&group->aliaslist);
 338                 list_add(&group->group, &lcu->grouplist);
 339         }
 340         if (uid->type == UA_BASE_DEVICE)
 341                 list_move(&device->alias_list, &group->baselist);
 342         else
 343                 list_move(&device->alias_list, &group->aliaslist);
 344         private->pavgroup = group;
 345         return 0;
 346 };
 347
 348 static void _remove_device_from_lcu(struct alias_lcu *lcu,
 349                                     struct dasd_device *device)
 350 {
 351         struct dasd_eckd_private *private;
 352         struct alias_pav_group *group;
 353
 354         private = (struct dasd_eckd_private *) device->private;
 355         list_move(&device->alias_list, &lcu->inactive_devices);
 356         group = private->pavgroup;
 357         if (!group)
 358                 return;
 359         private->pavgroup = NULL;
 360         if (list_empty(&group->baselist) && list_empty(&group->aliaslist)) {
 361                 list_del(&group->group);
 362                 kfree(group);
 363                 return;
 364         }
 365         if (group->next == device)
 366                 group->next = NULL;
 367 };
 368
 369 static int read_unit_address_configuration(struct dasd_device *device,
 370                                            struct alias_lcu *lcu)
 371 {
 372         struct dasd_psf_prssd_data *prssdp;
 373         struct dasd_ccw_req *cqr;
 374         struct ccw1 *ccw;
 375         int rc;
 376         unsigned long flags;
 377
 378         cqr = dasd_kmalloc_request("ECKD",
 379                                    1 /* PSF */  + 1 /* RSSD */ ,
 380                                    (sizeof(struct dasd_psf_prssd_data)),
 381                                    device);
 382         if (IS_ERR(cqr))
 383                 return PTR_ERR(cqr);
 384         cqr->startdev = device;
 385         cqr->memdev = device;
 386         clear_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
 387         cqr->retries = 10;
 388         cqr->expires = 20 * HZ;
 389
 390         /* Prepare for Read Subsystem Data */
 391         prssdp = (struct dasd_psf_prssd_data *) cqr->data;
 392         memset(prssdp, 0, sizeof(struct dasd_psf_prssd_data));
 393         prssdp->order = PSF_ORDER_PRSSD;
 394         prssdp->suborder = 0x0e;        /* Read unit address configuration */
 395         /* all other bytes of prssdp must be zero */
 396
 397         ccw = cqr->cpaddr;
 398         ccw->cmd_code = DASD_ECKD_CCW_PSF;
 399         ccw->count = sizeof(struct dasd_psf_prssd_data);
 400         ccw->flags |= CCW_FLAG_CC;
 401         ccw->cda = (__u32)(addr_t) prssdp;
 402
 403         /* Read Subsystem Data - feature codes */
 404         memset(lcu->uac, 0, sizeof(*(lcu->uac)));
 405
 406         ccw++;
 407         ccw->cmd_code = DASD_ECKD_CCW_RSSD;
 408         ccw->count = sizeof(*(lcu->uac));
 409         ccw->cda = (__u32)(addr_t) lcu->uac;
 410
 411         cqr->buildclk = get_clock();
 412         cqr->status = DASD_CQR_FILLED;
 413
 414         /* need to unset flag here to detect race with summary unit check */
 415         spin_lock_irqsave(&lcu->lock, flags);
 416         lcu->flags &= ~NEED_UAC_UPDATE;
 417         spin_unlock_irqrestore(&lcu->lock, flags);
 418
 419         do {
 420                 rc = dasd_sleep_on(cqr);
 421         } while (rc && (cqr->retries > 0));
 422         if (rc) {
 423                 spin_lock_irqsave(&lcu->lock, flags);
 424                 lcu->flags |= NEED_UAC_UPDATE;
 425                 spin_unlock_irqrestore(&lcu->lock, flags);
 426         }
 427         dasd_kfree_request(cqr, cqr->memdev);
 428         return rc;
 429 }
 430
 431 static int _lcu_update(struct dasd_device *refdev, struct alias_lcu *lcu)
 432 {
 433         unsigned long flags;
 434         struct alias_pav_group *pavgroup, *tempgroup;
 435         struct dasd_device *device, *tempdev;
 436         int i, rc;
 437         struct dasd_eckd_private *private;
 438
 439         spin_lock_irqsave(&lcu->lock, flags);
 440         list_for_each_entry_safe(pavgroup, tempgroup, &lcu->grouplist, group) {
 441                 list_for_each_entry_safe(device, tempdev, &pavgroup->baselist,
 442                                          alias_list) {
 443                         list_move(&device->alias_list, &lcu->active_devices);
 444                         private = (struct dasd_eckd_private *) device->private;
 445                         private->pavgroup = NULL;
 446                 }
 447                 list_for_each_entry_safe(device, tempdev, &pavgroup->aliaslist,
 448                                          alias_list) {
 449                         list_move(&device->alias_list, &lcu->active_devices);
 450                         private = (struct dasd_eckd_private *) device->private;
 451                         private->pavgroup = NULL;
 452                 }
 453                 list_del(&pavgroup->group);
 454                 kfree(pavgroup);
 455         }
 456         spin_unlock_irqrestore(&lcu->lock, flags);
 457
 458         rc = read_unit_address_configuration(refdev, lcu);
 459         if (rc)
 460                 return rc;
 461
 462         spin_lock_irqsave(&lcu->lock, flags);
 463         lcu->pav = NO_PAV;
 464         for (i = 0; i < MAX_DEVICES_PER_LCU; ++i) {
 465                 switch (lcu->uac->unit[i].ua_type) {
 466                 case UA_BASE_PAV_ALIAS:
 467                         lcu->pav = BASE_PAV;
 468                         break;
 469                 case UA_HYPER_PAV_ALIAS:
 470                         lcu->pav = HYPER_PAV;
 471                         break;
 472                 }
 473                 if (lcu->pav != NO_PAV)
 474                         break;
 475         }
 476
 477         list_for_each_entry_safe(device, tempdev, &lcu->active_devices,
 478                                  alias_list) {
 479                 _add_device_to_lcu(lcu, device);
 480         }
 481         spin_unlock_irqrestore(&lcu->lock, flags);
 482         return 0;
 483 }
 484
 485 static void lcu_update_work(struct work_struct *work)
 486 {
 487         struct alias_lcu *lcu;
 488         struct read_uac_work_data *ruac_data;
 489         struct dasd_device *device;
 490         unsigned long flags;
 491         int rc;
 492
 493         ruac_data = container_of(work, struct read_uac_work_data, dwork.work);
 494         lcu = container_of(ruac_data, struct alias_lcu, ruac_data);
 495         device = ruac_data->device;
 496         rc = _lcu_update(device, lcu);
 497         /*
 498          * Need to check flags again, as there could have been another
 499          * prepare_update or a new device a new device while we were still
 500          * processing the data
 501          */
 502         spin_lock_irqsave(&lcu->lock, flags);
 503         if (rc || (lcu->flags & NEED_UAC_UPDATE)) {
 504                 DEV_MESSAGE(KERN_WARNING, device, "could not update"
 505                             " alias data in lcu (rc = %d), retry later", rc);
 506                 schedule_delayed_work(&lcu->ruac_data.dwork, 30*HZ);
 507         } else {
 508                 lcu->ruac_data.device = NULL;
 509                 lcu->flags &= ~UPDATE_PENDING;
 510         }
 511         spin_unlock_irqrestore(&lcu->lock, flags);
 512 }
 513
 514 static int _schedule_lcu_update(struct alias_lcu *lcu,
 515                                 struct dasd_device *device)
 516 {
 517         struct dasd_device *usedev = NULL;
 518         struct alias_pav_group *group;
 519
 520         lcu->flags |= NEED_UAC_UPDATE;
 521         if (lcu->ruac_data.device) {
 522                 /* already scheduled or running */
 523                 return 0;
 524         }
 525         if (device && !list_empty(&device->alias_list))
 526                 usedev = device;
 527
 528         if (!usedev && !list_empty(&lcu->grouplist)) {
 529                 group = list_first_entry(&lcu->grouplist,
 530                                          struct alias_pav_group, group);
 531                 if (!list_empty(&group->baselist))
 532                         usedev = list_first_entry(&group->baselist,
 533                                                   struct dasd_device,
 534                                                   alias_list);
 535                 else if (!list_empty(&group->aliaslist))
 536                         usedev = list_first_entry(&group->aliaslist,
 537                                                   struct dasd_device,
 538                                                   alias_list);
 539         }
 540         if (!usedev && !list_empty(&lcu->active_devices)) {
 541                 usedev = list_first_entry(&lcu->active_devices,
 542                                           struct dasd_device, alias_list);
 543         }
 544         /*
 545          * if we haven't found a proper device yet, give up for now, the next
 546          * device that will be set active will trigger an lcu update
 547          */
 548         if (!usedev)
 549                 return -EINVAL;
 550         lcu->ruac_data.device = usedev;
 551         schedule_delayed_work(&lcu->ruac_data.dwork, 0);
 552         return 0;
 553 }
 554
 555 int dasd_alias_add_device(struct dasd_device *device)
 556 {
 557         struct dasd_eckd_private *private;
 558         struct alias_lcu *lcu;
 559         unsigned long flags;
 560         int rc;
 561
 562         private = (struct dasd_eckd_private *) device->private;
 563         lcu = private->lcu;
 564         rc = 0;
 565         spin_lock_irqsave(&lcu->lock, flags);
 566         if (!(lcu->flags & UPDATE_PENDING)) {
 567                 rc = _add_device_to_lcu(lcu, device);
 568                 if (rc)
 569                         lcu->flags |= UPDATE_PENDING;
 570         }
 571         if (lcu->flags & UPDATE_PENDING) {
 572                 list_move(&device->alias_list, &lcu->active_devices);
 573                 _schedule_lcu_update(lcu, device);
 574         }
 575         spin_unlock_irqrestore(&lcu->lock, flags);
 576         return rc;
 577 }
 578
 579 int dasd_alias_remove_device(struct dasd_device *device)
 580 {
 581         struct dasd_eckd_private *private;
 582         struct alias_lcu *lcu;
 583         unsigned long flags;
 584
 585         private = (struct dasd_eckd_private *) device->private;
 586         lcu = private->lcu;
 587         spin_lock_irqsave(&lcu->lock, flags);
 588         _remove_device_from_lcu(lcu, device);
 589         spin_unlock_irqrestore(&lcu->lock, flags);
 590         return 0;
 591 }
 592
 593 struct dasd_device *dasd_alias_get_start_dev(struct dasd_device *base_device)
 594 {
 595
 596         struct dasd_device *alias_device;
 597         struct alias_pav_group *group;
 598         struct alias_lcu *lcu;
 599         struct dasd_eckd_private *private, *alias_priv;
 600         unsigned long flags;
 601
 602         private = (struct dasd_eckd_private *) base_device->private;
 603         group = private->pavgroup;
 604         lcu = private->lcu;
 605         if (!group || !lcu)
 606                 return NULL;
 607         if (lcu->pav == NO_PAV ||
 608             lcu->flags & (NEED_UAC_UPDATE | UPDATE_PENDING))
 609                 return NULL;
 610
 611         spin_lock_irqsave(&lcu->lock, flags);
 612         alias_device = group->next;
 613         if (!alias_device) {
 614                 if (list_empty(&group->aliaslist)) {
 615                         spin_unlock_irqrestore(&lcu->lock, flags);
 616                         return NULL;
 617                 } else {
 618                         alias_device = list_first_entry(&group->aliaslist,
 619                                                         struct dasd_device,
 620                                                         alias_list);
 621                 }
 622         }
 623         if (list_is_last(&alias_device->alias_list, &group->aliaslist))
 624                 group->next = list_first_entry(&group->aliaslist,
 625                                                struct dasd_device, alias_list);
 626         else
 627                 group->next = list_first_entry(&alias_device->alias_list,
 628                                                struct dasd_device, alias_list);
 629         spin_unlock_irqrestore(&lcu->lock, flags);
 630         alias_priv = (struct dasd_eckd_private *) alias_device->private;
 631         if ((alias_priv->count < private->count) && !alias_device->stopped)
 632                 return alias_device;
 633         else
 634                 return NULL;
 635 }
 636
 637 /*
 638  * Summary unit check handling depends on the way alias devices
 639  * are handled so it is done here rather then in dasd_eckd.c
 640  */
 641 static int reset_summary_unit_check(struct alias_lcu *lcu,
 642                                     struct dasd_device *device,
 643                                     char reason)
 644 {
 645         struct dasd_ccw_req *cqr;
 646         int rc = 0;
 647
 648         cqr = lcu->rsu_cqr;
 649         strncpy((char *) &cqr->magic, "ECKD", 4);
 650         ASCEBC((char *) &cqr->magic, 4);
 651         cqr->cpaddr->cmd_code = DASD_ECKD_CCW_RSCK;
 652         cqr->cpaddr->flags = 0 ;
 653         cqr->cpaddr->count = 16;
 654         cqr->cpaddr->cda = (__u32)(addr_t) cqr->data;
 655         ((char *)cqr->data)[0] = reason;
 656
 657         clear_bit(DASD_CQR_FLAGS_USE_ERP, &cqr->flags);
 658         cqr->retries = 255;     /* set retry counter to enable basic ERP */
 659         cqr->startdev = device;
 660         cqr->memdev = device;
 661         cqr->block = NULL;
 662         cqr->expires = 5 * HZ;
 663         cqr->buildclk = get_clock();
 664         cqr->status = DASD_CQR_FILLED;
 665
 666         rc = dasd_sleep_on_immediatly(cqr);
 667         return rc;
 668 }
 669
 670 static void _restart_all_base_devices_on_lcu(struct alias_lcu *lcu)
 671 {
 672         struct alias_pav_group *pavgroup;
 673         struct dasd_device *device;
 674         struct dasd_eckd_private *private;
 675
 676         /* active and inactive list can contain alias as well as base devices */
 677         list_for_each_entry(device, &lcu->active_devices, alias_list) {
 678                 private = (struct dasd_eckd_private *) device->private;
 679                 if (private->uid.type != UA_BASE_DEVICE)
 680                         continue;
 681                 dasd_schedule_block_bh(device->block);
 682                 dasd_schedule_device_bh(device);
 683         }
 684         list_for_each_entry(device, &lcu->inactive_devices, alias_list) {
 685                 private = (struct dasd_eckd_private *) device->private;
 686                 if (private->uid.type != UA_BASE_DEVICE)
 687                         continue;
 688                 dasd_schedule_block_bh(device->block);
 689                 dasd_schedule_device_bh(device);
 690         }
 691         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 692                 list_for_each_entry(device, &pavgroup->baselist, alias_list) {
 693                         dasd_schedule_block_bh(device->block);
 694                         dasd_schedule_device_bh(device);
 695                 }
 696         }
 697 }
 698
 699 static void flush_all_alias_devices_on_lcu(struct alias_lcu *lcu)
 700 {
 701         struct alias_pav_group *pavgroup;
 702         struct dasd_device *device, *temp;
 703         struct dasd_eckd_private *private;
 704         int rc;
 705         unsigned long flags;
 706         LIST_HEAD(active);
 707
 708         /*
 709          * Problem here ist that dasd_flush_device_queue may wait
 710          * for termination of a request to complete. We can't keep
 711          * the lcu lock during that time, so we must assume that
 712          * the lists may have changed.
 713          * Idea: first gather all active alias devices in a separate list,
 714          * then flush the first element of this list unlocked, and afterwards
 715          * check if it is still on the list before moving it to the
 716          * active_devices list.
 717          */
 718
 719         spin_lock_irqsave(&lcu->lock, flags);
 720         list_for_each_entry_safe(device, temp, &lcu->active_devices,
 721                                  alias_list) {
 722                 private = (struct dasd_eckd_private *) device->private;
 723                 if (private->uid.type == UA_BASE_DEVICE)
 724                         continue;
 725                 list_move(&device->alias_list, &active);
 726         }
 727
 728         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 729                 list_splice_init(&pavgroup->aliaslist, &active);
 730         }
 731         while (!list_empty(&active)) {
 732                 device = list_first_entry(&active, struct dasd_device,
 733                                           alias_list);
 734                 spin_unlock_irqrestore(&lcu->lock, flags);
 735                 rc = dasd_flush_device_queue(device);
 736                 spin_lock_irqsave(&lcu->lock, flags);
 737                 /*
 738                  * only move device around if it wasn't moved away while we
 739                  * were waiting for the flush
 740                  */
 741                 if (device == list_first_entry(&active,
 742                                                struct dasd_device, alias_list))
 743                         list_move(&device->alias_list, &lcu->active_devices);
 744         }
 745         spin_unlock_irqrestore(&lcu->lock, flags);
 746 }
 747
 748 static void __stop_device_on_lcu(struct dasd_device *device,
 749                                  struct dasd_device *pos)
 750 {
 751         /* If pos == device then device is already locked! */
 752         if (pos == device) {
 753                 pos->stopped |= DASD_STOPPED_SU;
 754                 return;
 755         }
 756         spin_lock(get_ccwdev_lock(pos->cdev));
 757         pos->stopped |= DASD_STOPPED_SU;
 758         spin_unlock(get_ccwdev_lock(pos->cdev));
 759 }
 760
 761 /*
 762  * This function is called in interrupt context, so the
 763  * cdev lock for device is already locked!
 764  */
 765 static void _stop_all_devices_on_lcu(struct alias_lcu *lcu,
 766                                      struct dasd_device *device)
 767 {
 768         struct alias_pav_group *pavgroup;
 769         struct dasd_device *pos;
 770
 771         list_for_each_entry(pos, &lcu->active_devices, alias_list)
 772                 __stop_device_on_lcu(device, pos);
 773         list_for_each_entry(pos, &lcu->inactive_devices, alias_list)
 774                 __stop_device_on_lcu(device, pos);
 775         list_for_each_entry(pavgroup, &lcu->grouplist, group) {
 776                 list_for_each_entry(pos, &pavgroup->baselist, alias_list)
 777                         __stop_device_on_lcu(device, pos);
 778                 list_for_each_entry(pos, &pavgroup->aliaslist, alias_list)
 779                         __stop_device_on_lcu(device, pos);
 780         }
 781 }
 782
 783 static void _unstop_all_devices_on_lcu(struct alias_lcu *lcu)
 784 {
 785         struct alias_pav_group *pavgroup;
 786         struct dasd_device *device;
 787         unsigned long flags;
 788
 789         list_for_each_entry(device, &lcu->active_devices, alias_list) {
 790                 spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 791                 device->stopped &= ~DASD_STOPPED_SU;
 792                 spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 793         }
 794
 795         list_for_each_entry(device, &lcu->inactive_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(pavgroup, &lcu->grouplist, group) {
 802                 list_for_each_entry(device, &pavgroup->baselist, alias_list) {
 803                         spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 804                         device->stopped &= ~DASD_STOPPED_SU;
 805                         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev),
 806                                                flags);
 807                 }
 808                 list_for_each_entry(device, &pavgroup->aliaslist, 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         }
 815 }
 816
 817 static void summary_unit_check_handling_work(struct work_struct *work)
 818 {
 819         struct alias_lcu *lcu;
 820         struct summary_unit_check_work_data *suc_data;
 821         unsigned long flags;
 822         struct dasd_device *device;
 823
 824         suc_data = container_of(work, struct summary_unit_check_work_data,
 825                                 worker);
 826         lcu = container_of(suc_data, struct alias_lcu, suc_data);
 827         device = suc_data->device;
 828
 829         /* 1. flush alias devices */
 830         flush_all_alias_devices_on_lcu(lcu);
 831
 832         /* 2. reset summary unit check */
 833         spin_lock_irqsave(get_ccwdev_lock(device->cdev), flags);
 834         device->stopped &= ~(DASD_STOPPED_SU | DASD_STOPPED_PENDING);
 835         spin_unlock_irqrestore(get_ccwdev_lock(device->cdev), flags);
 836         reset_summary_unit_check(lcu, device, suc_data->reason);
 837
 838         spin_lock_irqsave(&lcu->lock, flags);
 839         _unstop_all_devices_on_lcu(lcu);
 840         _restart_all_base_devices_on_lcu(lcu);
 841         /* 3. read new alias configuration */
 842         _schedule_lcu_update(lcu, device);
 843         lcu->suc_data.device = NULL;
 844         spin_unlock_irqrestore(&lcu->lock, flags);
 845 }
 846
 847 /*
 848  * note: this will be called from int handler context (cdev locked)
 849  */
 850 void dasd_alias_handle_summary_unit_check(struct dasd_device *device,
 851                                           struct irb *irb)
 852 {
 853         struct alias_lcu *lcu;
 854         char reason;
 855         struct dasd_eckd_private *private;
 856
 857         private = (struct dasd_eckd_private *) device->private;
 858
 859         reason = irb->ecw[8];
 860         DEV_MESSAGE(KERN_WARNING, device, "%s %x",
 861                     "eckd handle summary unit check: reason", reason);
 862
 863         lcu = private->lcu;
 864         if (!lcu) {
 865                 DEV_MESSAGE(KERN_WARNING, device, "%s",
 866                             "device not ready to handle summary"
 867                             " unit check (no lcu structure)");
 868                 return;
 869         }
 870         spin_lock(&lcu->lock);
 871         _stop_all_devices_on_lcu(lcu, device);
 872         /* prepare for lcu_update */
 873         private->lcu->flags |= NEED_UAC_UPDATE | UPDATE_PENDING;
 874         /* If this device is about to be removed just return and wait for
 875          * the next interrupt on a different device
 876          */
 877         if (list_empty(&device->alias_list)) {
 878                 DEV_MESSAGE(KERN_WARNING, device, "%s",
 879                             "device is in offline processing,"
 880                             " don't do summary unit check handling");
 881                 spin_unlock(&lcu->lock);
 882                 return;
 883         }
 884         if (lcu->suc_data.device) {
 885                 /* already scheduled or running */
 886                 DEV_MESSAGE(KERN_WARNING, device, "%s",
 887                             "previous instance of summary unit check worker"
 888                             " still pending");
 889                 spin_unlock(&lcu->lock);
 890                 return ;
 891         }
 892         lcu->suc_data.reason = reason;
 893         lcu->suc_data.device = device;
 894         spin_unlock(&lcu->lock);
 895         schedule_work(&lcu->suc_data.worker);
 896 };