drivers/scsi/device_handler/scsi_dh_alua.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Generic SCSI-3 ALUA SCSI Device Handler
   4  *
   5  * Copyright (C) 2007-2010 Hannes Reinecke, SUSE Linux Products GmbH.
   6  * All rights reserved.
   7  */
   8 #include <linux/slab.h>
   9 #include <linux/delay.h>
  10 #include <linux/module.h>
  11 #include <asm/unaligned.h>
  12 #include <scsi/scsi.h>
  13 #include <scsi/scsi_proto.h>
  14 #include <scsi/scsi_dbg.h>
  15 #include <scsi/scsi_eh.h>
  16 #include <scsi/scsi_dh.h>
  17
  18 #define ALUA_DH_NAME "alua"
  19 #define ALUA_DH_VER "2.0"
  20
  21 #define TPGS_SUPPORT_NONE               0x00
  22 #define TPGS_SUPPORT_OPTIMIZED          0x01
  23 #define TPGS_SUPPORT_NONOPTIMIZED       0x02
  24 #define TPGS_SUPPORT_STANDBY            0x04
  25 #define TPGS_SUPPORT_UNAVAILABLE        0x08
  26 #define TPGS_SUPPORT_LBA_DEPENDENT      0x10
  27 #define TPGS_SUPPORT_OFFLINE            0x40
  28 #define TPGS_SUPPORT_TRANSITION         0x80
  29 #define TPGS_SUPPORT_ALL                0xdf
  30
  31 #define RTPG_FMT_MASK                   0x70
  32 #define RTPG_FMT_EXT_HDR                0x10
  33
  34 #define TPGS_MODE_UNINITIALIZED          -1
  35 #define TPGS_MODE_NONE                  0x0
  36 #define TPGS_MODE_IMPLICIT              0x1
  37 #define TPGS_MODE_EXPLICIT              0x2
  38
  39 #define ALUA_RTPG_SIZE                  128
  40 #define ALUA_FAILOVER_TIMEOUT           60
  41 #define ALUA_FAILOVER_RETRIES           5
  42 #define ALUA_RTPG_DELAY_MSECS           5
  43 #define ALUA_RTPG_RETRY_DELAY           2
  44
  45 /* device handler flags */
  46 #define ALUA_OPTIMIZE_STPG              0x01
  47 #define ALUA_RTPG_EXT_HDR_UNSUPP        0x02
  48 /* State machine flags */
  49 #define ALUA_PG_RUN_RTPG                0x10
  50 #define ALUA_PG_RUN_STPG                0x20
  51 #define ALUA_PG_RUNNING                 0x40
  52
  53 static uint optimize_stpg;
  54 module_param(optimize_stpg, uint, S_IRUGO|S_IWUSR);
  55 MODULE_PARM_DESC(optimize_stpg, "Allow use of a non-optimized path, rather than sending a STPG, when implicit TPGS is supported (0=No,1=Yes). Default is 0.");
  56
  57 static LIST_HEAD(port_group_list);
  58 static DEFINE_SPINLOCK(port_group_lock);
  59 static struct workqueue_struct *kaluad_wq;
  60
  61 struct alua_port_group {
  62         struct kref             kref;
  63         struct rcu_head         rcu;
  64         struct list_head        node;
  65         struct list_head        dh_list;
  66         unsigned char           device_id_str[256];
  67         int                     device_id_len;
  68         int                     group_id;
  69         int                     tpgs;
  70         int                     state;
  71         int                     pref;
  72         int                     valid_states;
  73         unsigned                flags; /* used for optimizing STPG */
  74         unsigned char           transition_tmo;
  75         unsigned long           expiry;
  76         unsigned long           interval;
  77         struct delayed_work     rtpg_work;
  78         spinlock_t              lock;
  79         struct list_head        rtpg_list;
  80         struct scsi_device      *rtpg_sdev;
  81 };
  82
  83 struct alua_dh_data {
  84         struct list_head        node;
  85         struct alua_port_group __rcu *pg;
  86         int                     group_id;
  87         spinlock_t              pg_lock;
  88         struct scsi_device      *sdev;
  89         int                     init_error;
  90         struct mutex            init_mutex;
  91 };
  92
  93 struct alua_queue_data {
  94         struct list_head        entry;
  95         activate_complete       callback_fn;
  96         void                    *callback_data;
  97 };
  98
  99 #define ALUA_POLICY_SWITCH_CURRENT      0
 100 #define ALUA_POLICY_SWITCH_ALL          1
 101
 102 static void alua_rtpg_work(struct work_struct *work);
 103 static bool alua_rtpg_queue(struct alua_port_group *pg,
 104                             struct scsi_device *sdev,
 105                             struct alua_queue_data *qdata, bool force);
 106 static void alua_check(struct scsi_device *sdev, bool force);
 107
 108 static void release_port_group(struct kref *kref)
 109 {
 110         struct alua_port_group *pg;
 111
 112         pg = container_of(kref, struct alua_port_group, kref);
 113         if (pg->rtpg_sdev)
 114                 flush_delayed_work(&pg->rtpg_work);
 115         spin_lock(&port_group_lock);
 116         list_del(&pg->node);
 117         spin_unlock(&port_group_lock);
 118         kfree_rcu(pg, rcu);
 119 }
 120
 121 /*
 122  * submit_rtpg - Issue a REPORT TARGET GROUP STATES command
 123  * @sdev: sdev the command should be sent to
 124  */
 125 static int submit_rtpg(struct scsi_device *sdev, unsigned char *buff,
 126                        int bufflen, struct scsi_sense_hdr *sshdr, int flags)
 127 {
 128         u8 cdb[MAX_COMMAND_SIZE];
 129         int req_flags = REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
 130                 REQ_FAILFAST_DRIVER;
 131
 132         /* Prepare the command. */
 133         memset(cdb, 0x0, MAX_COMMAND_SIZE);
 134         cdb[0] = MAINTENANCE_IN;
 135         if (!(flags & ALUA_RTPG_EXT_HDR_UNSUPP))
 136                 cdb[1] = MI_REPORT_TARGET_PGS | MI_EXT_HDR_PARAM_FMT;
 137         else
 138                 cdb[1] = MI_REPORT_TARGET_PGS;
 139         put_unaligned_be32(bufflen, &cdb[6]);
 140
 141         return scsi_execute(sdev, cdb, DMA_FROM_DEVICE, buff, bufflen, NULL,
 142                         sshdr, ALUA_FAILOVER_TIMEOUT * HZ,
 143                         ALUA_FAILOVER_RETRIES, req_flags, 0, NULL);
 144 }
 145
 146 /*
 147  * submit_stpg - Issue a SET TARGET PORT GROUP command
 148  *
 149  * Currently we're only setting the current target port group state
 150  * to 'active/optimized' and let the array firmware figure out
 151  * the states of the remaining groups.
 152  */
 153 static int submit_stpg(struct scsi_device *sdev, int group_id,
 154                        struct scsi_sense_hdr *sshdr)
 155 {
 156         u8 cdb[MAX_COMMAND_SIZE];
 157         unsigned char stpg_data[8];
 158         int stpg_len = 8;
 159         int req_flags = REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
 160                 REQ_FAILFAST_DRIVER;
 161
 162         /* Prepare the data buffer */
 163         memset(stpg_data, 0, stpg_len);
 164         stpg_data[4] = SCSI_ACCESS_STATE_OPTIMAL;
 165         put_unaligned_be16(group_id, &stpg_data[6]);
 166
 167         /* Prepare the command. */
 168         memset(cdb, 0x0, MAX_COMMAND_SIZE);
 169         cdb[0] = MAINTENANCE_OUT;
 170         cdb[1] = MO_SET_TARGET_PGS;
 171         put_unaligned_be32(stpg_len, &cdb[6]);
 172
 173         return scsi_execute(sdev, cdb, DMA_TO_DEVICE, stpg_data, stpg_len, NULL,
 174                         sshdr, ALUA_FAILOVER_TIMEOUT * HZ,
 175                         ALUA_FAILOVER_RETRIES, req_flags, 0, NULL);
 176 }
 177
 178 static struct alua_port_group *alua_find_get_pg(char *id_str, size_t id_size,
 179                                                 int group_id)
 180 {
 181         struct alua_port_group *pg;
 182
 183         if (!id_str || !id_size || !strlen(id_str))
 184                 return NULL;
 185
 186         list_for_each_entry(pg, &port_group_list, node) {
 187                 if (pg->group_id != group_id)
 188                         continue;
 189                 if (!pg->device_id_len || pg->device_id_len != id_size)
 190                         continue;
 191                 if (strncmp(pg->device_id_str, id_str, id_size))
 192                         continue;
 193                 if (!kref_get_unless_zero(&pg->kref))
 194                         continue;
 195                 return pg;
 196         }
 197
 198         return NULL;
 199 }
 200
 201 /*
 202  * alua_alloc_pg - Allocate a new port_group structure
 203  * @sdev: scsi device
 204  * @group_id: port group id
 205  * @tpgs: target port group settings
 206  *
 207  * Allocate a new port_group structure for a given
 208  * device.
 209  */
 210 static struct alua_port_group *alua_alloc_pg(struct scsi_device *sdev,
 211                                              int group_id, int tpgs)
 212 {
 213         struct alua_port_group *pg, *tmp_pg;
 214
 215         pg = kzalloc(sizeof(struct alua_port_group), GFP_KERNEL);
 216         if (!pg)
 217                 return ERR_PTR(-ENOMEM);
 218
 219         pg->device_id_len = scsi_vpd_lun_id(sdev, pg->device_id_str,
 220                                             sizeof(pg->device_id_str));
 221         if (pg->device_id_len <= 0) {
 222                 /*
 223                  * TPGS supported but no device identification found.
 224                  * Generate private device identification.
 225                  */
 226                 sdev_printk(KERN_INFO, sdev,
 227                             "%s: No device descriptors found\n",
 228                             ALUA_DH_NAME);
 229                 pg->device_id_str[0] = '\0';
 230                 pg->device_id_len = 0;
 231         }
 232         pg->group_id = group_id;
 233         pg->tpgs = tpgs;
 234         pg->state = SCSI_ACCESS_STATE_OPTIMAL;
 235         pg->valid_states = TPGS_SUPPORT_ALL;
 236         if (optimize_stpg)
 237                 pg->flags |= ALUA_OPTIMIZE_STPG;
 238         kref_init(&pg->kref);
 239         INIT_DELAYED_WORK(&pg->rtpg_work, alua_rtpg_work);
 240         INIT_LIST_HEAD(&pg->rtpg_list);
 241         INIT_LIST_HEAD(&pg->node);
 242         INIT_LIST_HEAD(&pg->dh_list);
 243         spin_lock_init(&pg->lock);
 244
 245         spin_lock(&port_group_lock);
 246         tmp_pg = alua_find_get_pg(pg->device_id_str, pg->device_id_len,
 247                                   group_id);
 248         if (tmp_pg) {
 249                 spin_unlock(&port_group_lock);
 250                 kfree(pg);
 251                 return tmp_pg;
 252         }
 253
 254         list_add(&pg->node, &port_group_list);
 255         spin_unlock(&port_group_lock);
 256
 257         return pg;
 258 }
 259
 260 /*
 261  * alua_check_tpgs - Evaluate TPGS setting
 262  * @sdev: device to be checked
 263  *
 264  * Examine the TPGS setting of the sdev to find out if ALUA
 265  * is supported.
 266  */
 267 static int alua_check_tpgs(struct scsi_device *sdev)
 268 {
 269         int tpgs = TPGS_MODE_NONE;
 270
 271         /*
 272          * ALUA support for non-disk devices is fraught with
 273          * difficulties, so disable it for now.
 274          */
 275         if (sdev->type != TYPE_DISK) {
 276                 sdev_printk(KERN_INFO, sdev,
 277                             "%s: disable for non-disk devices\n",
 278                             ALUA_DH_NAME);
 279                 return tpgs;
 280         }
 281
 282         tpgs = scsi_device_tpgs(sdev);
 283         switch (tpgs) {
 284         case TPGS_MODE_EXPLICIT|TPGS_MODE_IMPLICIT:
 285                 sdev_printk(KERN_INFO, sdev,
 286                             "%s: supports implicit and explicit TPGS\n",
 287                             ALUA_DH_NAME);
 288                 break;
 289         case TPGS_MODE_EXPLICIT:
 290                 sdev_printk(KERN_INFO, sdev, "%s: supports explicit TPGS\n",
 291                             ALUA_DH_NAME);
 292                 break;
 293         case TPGS_MODE_IMPLICIT:
 294                 sdev_printk(KERN_INFO, sdev, "%s: supports implicit TPGS\n",
 295                             ALUA_DH_NAME);
 296                 break;
 297         case TPGS_MODE_NONE:
 298                 sdev_printk(KERN_INFO, sdev, "%s: not supported\n",
 299                             ALUA_DH_NAME);
 300                 break;
 301         default:
 302                 sdev_printk(KERN_INFO, sdev,
 303                             "%s: unsupported TPGS setting %d\n",
 304                             ALUA_DH_NAME, tpgs);
 305                 tpgs = TPGS_MODE_NONE;
 306                 break;
 307         }
 308
 309         return tpgs;
 310 }
 311
 312 /*
 313  * alua_check_vpd - Evaluate INQUIRY vpd page 0x83
 314  * @sdev: device to be checked
 315  *
 316  * Extract the relative target port and the target port group
 317  * descriptor from the list of identificators.
 318  */
 319 static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h,
 320                           int tpgs)
 321 {
 322         int rel_port = -1, group_id;
 323         struct alua_port_group *pg, *old_pg = NULL;
 324         bool pg_updated = false;
 325         unsigned long flags;
 326
 327         group_id = scsi_vpd_tpg_id(sdev, &rel_port);
 328         if (group_id < 0) {
 329                 /*
 330                  * Internal error; TPGS supported but required
 331                  * VPD identification descriptors not present.
 332                  * Disable ALUA support
 333                  */
 334                 sdev_printk(KERN_INFO, sdev,
 335                             "%s: No target port descriptors found\n",
 336                             ALUA_DH_NAME);
 337                 return SCSI_DH_DEV_UNSUPP;
 338         }
 339
 340         pg = alua_alloc_pg(sdev, group_id, tpgs);
 341         if (IS_ERR(pg)) {
 342                 if (PTR_ERR(pg) == -ENOMEM)
 343                         return SCSI_DH_NOMEM;
 344                 return SCSI_DH_DEV_UNSUPP;
 345         }
 346         if (pg->device_id_len)
 347                 sdev_printk(KERN_INFO, sdev,
 348                             "%s: device %s port group %x rel port %x\n",
 349                             ALUA_DH_NAME, pg->device_id_str,
 350                             group_id, rel_port);
 351         else
 352                 sdev_printk(KERN_INFO, sdev,
 353                             "%s: port group %x rel port %x\n",
 354                             ALUA_DH_NAME, group_id, rel_port);
 355
 356         /* Check for existing port group references */
 357         spin_lock(&h->pg_lock);
 358         old_pg = rcu_dereference_protected(h->pg, lockdep_is_held(&h->pg_lock));
 359         if (old_pg != pg) {
 360                 /* port group has changed. Update to new port group */
 361                 if (h->pg) {
 362                         spin_lock_irqsave(&old_pg->lock, flags);
 363                         list_del_rcu(&h->node);
 364                         spin_unlock_irqrestore(&old_pg->lock, flags);
 365                 }
 366                 rcu_assign_pointer(h->pg, pg);
 367                 pg_updated = true;
 368         }
 369
 370         spin_lock_irqsave(&pg->lock, flags);
 371         if (pg_updated)
 372                 list_add_rcu(&h->node, &pg->dh_list);
 373         spin_unlock_irqrestore(&pg->lock, flags);
 374
 375         alua_rtpg_queue(rcu_dereference_protected(h->pg,
 376                                                   lockdep_is_held(&h->pg_lock)),
 377                         sdev, NULL, true);
 378         spin_unlock(&h->pg_lock);
 379
 380         if (old_pg)
 381                 kref_put(&old_pg->kref, release_port_group);
 382
 383         return SCSI_DH_OK;
 384 }
 385
 386 static char print_alua_state(unsigned char state)
 387 {
 388         switch (state) {
 389         case SCSI_ACCESS_STATE_OPTIMAL:
 390                 return 'A';
 391         case SCSI_ACCESS_STATE_ACTIVE:
 392                 return 'N';
 393         case SCSI_ACCESS_STATE_STANDBY:
 394                 return 'S';
 395         case SCSI_ACCESS_STATE_UNAVAILABLE:
 396                 return 'U';
 397         case SCSI_ACCESS_STATE_LBA:
 398                 return 'L';
 399         case SCSI_ACCESS_STATE_OFFLINE:
 400                 return 'O';
 401         case SCSI_ACCESS_STATE_TRANSITIONING:
 402                 return 'T';
 403         default:
 404                 return 'X';
 405         }
 406 }
 407
 408 static enum scsi_disposition alua_check_sense(struct scsi_device *sdev,
 409                                               struct scsi_sense_hdr *sense_hdr)
 410 {
 411         struct alua_dh_data *h = sdev->handler_data;
 412         struct alua_port_group *pg;
 413
 414         switch (sense_hdr->sense_key) {
 415         case NOT_READY:
 416                 if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0a) {
 417                         /*
 418                          * LUN Not Accessible - ALUA state transition
 419                          */
 420                         rcu_read_lock();
 421                         pg = rcu_dereference(h->pg);
 422                         if (pg)
 423                                 pg->state = SCSI_ACCESS_STATE_TRANSITIONING;
 424                         rcu_read_unlock();
 425                         alua_check(sdev, false);
 426                         return NEEDS_RETRY;
 427                 }
 428                 break;
 429         case UNIT_ATTENTION:
 430                 if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00) {
 431                         /*
 432                          * Power On, Reset, or Bus Device Reset.
 433                          * Might have obscured a state transition,
 434                          * so schedule a recheck.
 435                          */
 436                         alua_check(sdev, true);
 437                         return ADD_TO_MLQUEUE;
 438                 }
 439                 if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x04)
 440                         /*
 441                          * Device internal reset
 442                          */
 443                         return ADD_TO_MLQUEUE;
 444                 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x01)
 445                         /*
 446                          * Mode Parameters Changed
 447                          */
 448                         return ADD_TO_MLQUEUE;
 449                 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x06) {
 450                         /*
 451                          * ALUA state changed
 452                          */
 453                         alua_check(sdev, true);
 454                         return ADD_TO_MLQUEUE;
 455                 }
 456                 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x07) {
 457                         /*
 458                          * Implicit ALUA state transition failed
 459                          */
 460                         alua_check(sdev, true);
 461                         return ADD_TO_MLQUEUE;
 462                 }
 463                 if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x03)
 464                         /*
 465                          * Inquiry data has changed
 466                          */
 467                         return ADD_TO_MLQUEUE;
 468                 if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x0e)
 469                         /*
 470                          * REPORTED_LUNS_DATA_HAS_CHANGED is reported
 471                          * when switching controllers on targets like
 472                          * Intel Multi-Flex. We can just retry.
 473                          */
 474                         return ADD_TO_MLQUEUE;
 475                 break;
 476         }
 477
 478         return SCSI_RETURN_NOT_HANDLED;
 479 }
 480
 481 /*
 482  * alua_tur - Send a TEST UNIT READY
 483  * @sdev: device to which the TEST UNIT READY command should be send
 484  *
 485  * Send a TEST UNIT READY to @sdev to figure out the device state
 486  * Returns SCSI_DH_RETRY if the sense code is NOT READY/ALUA TRANSITIONING,
 487  * SCSI_DH_OK if no error occurred, and SCSI_DH_IO otherwise.
 488  */
 489 static int alua_tur(struct scsi_device *sdev)
 490 {
 491         struct scsi_sense_hdr sense_hdr;
 492         int retval;
 493
 494         retval = scsi_test_unit_ready(sdev, ALUA_FAILOVER_TIMEOUT * HZ,
 495                                       ALUA_FAILOVER_RETRIES, &sense_hdr);
 496         if (sense_hdr.sense_key == NOT_READY &&
 497             sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a)
 498                 return SCSI_DH_RETRY;
 499         else if (retval)
 500                 return SCSI_DH_IO;
 501         else
 502                 return SCSI_DH_OK;
 503 }
 504
 505 /*
 506  * alua_rtpg - Evaluate REPORT TARGET GROUP STATES
 507  * @sdev: the device to be evaluated.
 508  *
 509  * Evaluate the Target Port Group State.
 510  * Returns SCSI_DH_DEV_OFFLINED if the path is
 511  * found to be unusable.
 512  */
 513 static int alua_rtpg(struct scsi_device *sdev, struct alua_port_group *pg)
 514 {
 515         struct scsi_sense_hdr sense_hdr;
 516         struct alua_port_group *tmp_pg;
 517         int len, k, off, bufflen = ALUA_RTPG_SIZE;
 518         int group_id_old, state_old, pref_old, valid_states_old;
 519         unsigned char *desc, *buff;
 520         unsigned err, retval;
 521         unsigned int tpg_desc_tbl_off;
 522         unsigned char orig_transition_tmo;
 523         unsigned long flags;
 524         bool transitioning_sense = false;
 525
 526         group_id_old = pg->group_id;
 527         state_old = pg->state;
 528         pref_old = pg->pref;
 529         valid_states_old = pg->valid_states;
 530
 531         if (!pg->expiry) {
 532                 unsigned long transition_tmo = ALUA_FAILOVER_TIMEOUT * HZ;
 533
 534                 if (pg->transition_tmo)
 535                         transition_tmo = pg->transition_tmo * HZ;
 536
 537                 pg->expiry = round_jiffies_up(jiffies + transition_tmo);
 538         }
 539
 540         buff = kzalloc(bufflen, GFP_KERNEL);
 541         if (!buff)
 542                 return SCSI_DH_DEV_TEMP_BUSY;
 543
 544  retry:
 545         err = 0;
 546         retval = submit_rtpg(sdev, buff, bufflen, &sense_hdr, pg->flags);
 547
 548         if (retval) {
 549                 /*
 550                  * Some (broken) implementations have a habit of returning
 551                  * an error during things like firmware update etc.
 552                  * But if the target only supports active/optimized there's
 553                  * not much we can do; it's not that we can switch paths
 554                  * or anything.
 555                  * So ignore any errors to avoid spurious failures during
 556                  * path failover.
 557                  */
 558                 if ((pg->valid_states & ~TPGS_SUPPORT_OPTIMIZED) == 0) {
 559                         sdev_printk(KERN_INFO, sdev,
 560                                     "%s: ignoring rtpg result %d\n",
 561                                     ALUA_DH_NAME, retval);
 562                         kfree(buff);
 563                         return SCSI_DH_OK;
 564                 }
 565                 if (!scsi_sense_valid(&sense_hdr)) {
 566                         sdev_printk(KERN_INFO, sdev,
 567                                     "%s: rtpg failed, result %d\n",
 568                                     ALUA_DH_NAME, retval);
 569                         kfree(buff);
 570                         if (driver_byte(retval) == DRIVER_ERROR)
 571                                 return SCSI_DH_DEV_TEMP_BUSY;
 572                         return SCSI_DH_IO;
 573                 }
 574
 575                 /*
 576                  * submit_rtpg() has failed on existing arrays
 577                  * when requesting extended header info, and
 578                  * the array doesn't support extended headers,
 579                  * even though it shouldn't according to T10.
 580                  * The retry without rtpg_ext_hdr_req set
 581                  * handles this.
 582                  * Note:  some arrays return a sense key of ILLEGAL_REQUEST
 583                  * with ASC 00h if they don't support the extended header.
 584                  */
 585                 if (!(pg->flags & ALUA_RTPG_EXT_HDR_UNSUPP) &&
 586                     sense_hdr.sense_key == ILLEGAL_REQUEST) {
 587                         pg->flags |= ALUA_RTPG_EXT_HDR_UNSUPP;
 588                         goto retry;
 589                 }
 590                 /*
 591                  * If the array returns with 'ALUA state transition'
 592                  * sense code here it cannot return RTPG data during
 593                  * transition. So set the state to 'transitioning' directly.
 594                  */
 595                 if (sense_hdr.sense_key == NOT_READY &&
 596                     sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a) {
 597                         transitioning_sense = true;
 598                         goto skip_rtpg;
 599                 }
 600                 /*
 601                  * Retry on any other UNIT ATTENTION occurred.
 602                  */
 603                 if (sense_hdr.sense_key == UNIT_ATTENTION)
 604                         err = SCSI_DH_RETRY;
 605                 if (err == SCSI_DH_RETRY &&
 606                     pg->expiry != 0 && time_before(jiffies, pg->expiry)) {
 607                         sdev_printk(KERN_ERR, sdev, "%s: rtpg retry\n",
 608                                     ALUA_DH_NAME);
 609                         scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
 610                         kfree(buff);
 611                         return err;
 612                 }
 613                 sdev_printk(KERN_ERR, sdev, "%s: rtpg failed\n",
 614                             ALUA_DH_NAME);
 615                 scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
 616                 kfree(buff);
 617                 pg->expiry = 0;
 618                 return SCSI_DH_IO;
 619         }
 620
 621         len = get_unaligned_be32(&buff[0]) + 4;
 622
 623         if (len > bufflen) {
 624                 /* Resubmit with the correct length */
 625                 kfree(buff);
 626                 bufflen = len;
 627                 buff = kmalloc(bufflen, GFP_KERNEL);
 628                 if (!buff) {
 629                         sdev_printk(KERN_WARNING, sdev,
 630                                     "%s: kmalloc buffer failed\n",__func__);
 631                         /* Temporary failure, bypass */
 632                         pg->expiry = 0;
 633                         return SCSI_DH_DEV_TEMP_BUSY;
 634                 }
 635                 goto retry;
 636         }
 637
 638         orig_transition_tmo = pg->transition_tmo;
 639         if ((buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR && buff[5] != 0)
 640                 pg->transition_tmo = buff[5];
 641         else
 642                 pg->transition_tmo = ALUA_FAILOVER_TIMEOUT;
 643
 644         if (orig_transition_tmo != pg->transition_tmo) {
 645                 sdev_printk(KERN_INFO, sdev,
 646                             "%s: transition timeout set to %d seconds\n",
 647                             ALUA_DH_NAME, pg->transition_tmo);
 648                 pg->expiry = jiffies + pg->transition_tmo * HZ;
 649         }
 650
 651         if ((buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR)
 652                 tpg_desc_tbl_off = 8;
 653         else
 654                 tpg_desc_tbl_off = 4;
 655
 656         for (k = tpg_desc_tbl_off, desc = buff + tpg_desc_tbl_off;
 657              k < len;
 658              k += off, desc += off) {
 659                 u16 group_id = get_unaligned_be16(&desc[2]);
 660
 661                 spin_lock_irqsave(&port_group_lock, flags);
 662                 tmp_pg = alua_find_get_pg(pg->device_id_str, pg->device_id_len,
 663                                           group_id);
 664                 spin_unlock_irqrestore(&port_group_lock, flags);
 665                 if (tmp_pg) {
 666                         if (spin_trylock_irqsave(&tmp_pg->lock, flags)) {
 667                                 if ((tmp_pg == pg) ||
 668                                     !(tmp_pg->flags & ALUA_PG_RUNNING)) {
 669                                         struct alua_dh_data *h;
 670
 671                                         tmp_pg->state = desc[0] & 0x0f;
 672                                         tmp_pg->pref = desc[0] >> 7;
 673                                         rcu_read_lock();
 674                                         list_for_each_entry_rcu(h,
 675                                                 &tmp_pg->dh_list, node) {
 676                                                 if (!h->sdev)
 677                                                         continue;
 678                                                 h->sdev->access_state = desc[0];
 679                                         }
 680                                         rcu_read_unlock();
 681                                 }
 682                                 if (tmp_pg == pg)
 683                                         tmp_pg->valid_states = desc[1];
 684                                 spin_unlock_irqrestore(&tmp_pg->lock, flags);
 685                         }
 686                         kref_put(&tmp_pg->kref, release_port_group);
 687                 }
 688                 off = 8 + (desc[7] * 4);
 689         }
 690
 691  skip_rtpg:
 692         spin_lock_irqsave(&pg->lock, flags);
 693         if (transitioning_sense)
 694                 pg->state = SCSI_ACCESS_STATE_TRANSITIONING;
 695
 696         if (group_id_old != pg->group_id || state_old != pg->state ||
 697                 pref_old != pg->pref || valid_states_old != pg->valid_states)
 698                 sdev_printk(KERN_INFO, sdev,
 699                         "%s: port group %02x state %c %s supports %c%c%c%c%c%c%c\n",
 700                         ALUA_DH_NAME, pg->group_id, print_alua_state(pg->state),
 701                         pg->pref ? "preferred" : "non-preferred",
 702                         pg->valid_states&TPGS_SUPPORT_TRANSITION?'T':'t',
 703                         pg->valid_states&TPGS_SUPPORT_OFFLINE?'O':'o',
 704                         pg->valid_states&TPGS_SUPPORT_LBA_DEPENDENT?'L':'l',
 705                         pg->valid_states&TPGS_SUPPORT_UNAVAILABLE?'U':'u',
 706                         pg->valid_states&TPGS_SUPPORT_STANDBY?'S':'s',
 707                         pg->valid_states&TPGS_SUPPORT_NONOPTIMIZED?'N':'n',
 708                         pg->valid_states&TPGS_SUPPORT_OPTIMIZED?'A':'a');
 709
 710         switch (pg->state) {
 711         case SCSI_ACCESS_STATE_TRANSITIONING:
 712                 if (time_before(jiffies, pg->expiry)) {
 713                         /* State transition, retry */
 714                         pg->interval = ALUA_RTPG_RETRY_DELAY;
 715                         err = SCSI_DH_RETRY;
 716                 } else {
 717                         struct alua_dh_data *h;
 718
 719                         /* Transitioning time exceeded, set port to standby */
 720                         err = SCSI_DH_IO;
 721                         pg->state = SCSI_ACCESS_STATE_STANDBY;
 722                         pg->expiry = 0;
 723                         rcu_read_lock();
 724                         list_for_each_entry_rcu(h, &pg->dh_list, node) {
 725                                 if (!h->sdev)
 726                                         continue;
 727                                 h->sdev->access_state =
 728                                         (pg->state & SCSI_ACCESS_STATE_MASK);
 729                                 if (pg->pref)
 730                                         h->sdev->access_state |=
 731                                                 SCSI_ACCESS_STATE_PREFERRED;
 732                         }
 733                         rcu_read_unlock();
 734                 }
 735                 break;
 736         case SCSI_ACCESS_STATE_OFFLINE:
 737                 /* Path unusable */
 738                 err = SCSI_DH_DEV_OFFLINED;
 739                 pg->expiry = 0;
 740                 break;
 741         default:
 742                 /* Useable path if active */
 743                 err = SCSI_DH_OK;
 744                 pg->expiry = 0;
 745                 break;
 746         }
 747         spin_unlock_irqrestore(&pg->lock, flags);
 748         kfree(buff);
 749         return err;
 750 }
 751
 752 /*
 753  * alua_stpg - Issue a SET TARGET PORT GROUP command
 754  *
 755  * Issue a SET TARGET PORT GROUP command and evaluate the
 756  * response. Returns SCSI_DH_RETRY per default to trigger
 757  * a re-evaluation of the target group state or SCSI_DH_OK
 758  * if no further action needs to be taken.
 759  */
 760 static unsigned alua_stpg(struct scsi_device *sdev, struct alua_port_group *pg)
 761 {
 762         int retval;
 763         struct scsi_sense_hdr sense_hdr;
 764
 765         if (!(pg->tpgs & TPGS_MODE_EXPLICIT)) {
 766                 /* Only implicit ALUA supported, retry */
 767                 return SCSI_DH_RETRY;
 768         }
 769         switch (pg->state) {
 770         case SCSI_ACCESS_STATE_OPTIMAL:
 771                 return SCSI_DH_OK;
 772         case SCSI_ACCESS_STATE_ACTIVE:
 773                 if ((pg->flags & ALUA_OPTIMIZE_STPG) &&
 774                     !pg->pref &&
 775                     (pg->tpgs & TPGS_MODE_IMPLICIT))
 776                         return SCSI_DH_OK;
 777                 break;
 778         case SCSI_ACCESS_STATE_STANDBY:
 779         case SCSI_ACCESS_STATE_UNAVAILABLE:
 780                 break;
 781         case SCSI_ACCESS_STATE_OFFLINE:
 782                 return SCSI_DH_IO;
 783         case SCSI_ACCESS_STATE_TRANSITIONING:
 784                 break;
 785         default:
 786                 sdev_printk(KERN_INFO, sdev,
 787                             "%s: stpg failed, unhandled TPGS state %d",
 788                             ALUA_DH_NAME, pg->state);
 789                 return SCSI_DH_NOSYS;
 790         }
 791         retval = submit_stpg(sdev, pg->group_id, &sense_hdr);
 792
 793         if (retval) {
 794                 if (!scsi_sense_valid(&sense_hdr)) {
 795                         sdev_printk(KERN_INFO, sdev,
 796                                     "%s: stpg failed, result %d",
 797                                     ALUA_DH_NAME, retval);
 798                         if (driver_byte(retval) == DRIVER_ERROR)
 799                                 return SCSI_DH_DEV_TEMP_BUSY;
 800                 } else {
 801                         sdev_printk(KERN_INFO, sdev, "%s: stpg failed\n",
 802                                     ALUA_DH_NAME);
 803                         scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
 804                 }
 805         }
 806         /* Retry RTPG */
 807         return SCSI_DH_RETRY;
 808 }
 809
 810 static void alua_rtpg_work(struct work_struct *work)
 811 {
 812         struct alua_port_group *pg =
 813                 container_of(work, struct alua_port_group, rtpg_work.work);
 814         struct scsi_device *sdev;
 815         LIST_HEAD(qdata_list);
 816         int err = SCSI_DH_OK;
 817         struct alua_queue_data *qdata, *tmp;
 818         unsigned long flags;
 819
 820         spin_lock_irqsave(&pg->lock, flags);
 821         sdev = pg->rtpg_sdev;
 822         if (!sdev) {
 823                 WARN_ON(pg->flags & ALUA_PG_RUN_RTPG);
 824                 WARN_ON(pg->flags & ALUA_PG_RUN_STPG);
 825                 spin_unlock_irqrestore(&pg->lock, flags);
 826                 kref_put(&pg->kref, release_port_group);
 827                 return;
 828         }
 829         pg->flags |= ALUA_PG_RUNNING;
 830         if (pg->flags & ALUA_PG_RUN_RTPG) {
 831                 int state = pg->state;
 832
 833                 pg->flags &= ~ALUA_PG_RUN_RTPG;
 834                 spin_unlock_irqrestore(&pg->lock, flags);
 835                 if (state == SCSI_ACCESS_STATE_TRANSITIONING) {
 836                         if (alua_tur(sdev) == SCSI_DH_RETRY) {
 837                                 spin_lock_irqsave(&pg->lock, flags);
 838                                 pg->flags &= ~ALUA_PG_RUNNING;
 839                                 pg->flags |= ALUA_PG_RUN_RTPG;
 840                                 if (!pg->interval)
 841                                         pg->interval = ALUA_RTPG_RETRY_DELAY;
 842                                 spin_unlock_irqrestore(&pg->lock, flags);
 843                                 queue_delayed_work(kaluad_wq, &pg->rtpg_work,
 844                                                    pg->interval * HZ);
 845                                 return;
 846                         }
 847                         /* Send RTPG on failure or if TUR indicates SUCCESS */
 848                 }
 849                 err = alua_rtpg(sdev, pg);
 850                 spin_lock_irqsave(&pg->lock, flags);
 851                 if (err == SCSI_DH_RETRY || pg->flags & ALUA_PG_RUN_RTPG) {
 852                         pg->flags &= ~ALUA_PG_RUNNING;
 853                         if (!pg->interval && !(pg->flags & ALUA_PG_RUN_RTPG))
 854                                 pg->interval = ALUA_RTPG_RETRY_DELAY;
 855                         pg->flags |= ALUA_PG_RUN_RTPG;
 856                         spin_unlock_irqrestore(&pg->lock, flags);
 857                         queue_delayed_work(kaluad_wq, &pg->rtpg_work,
 858                                            pg->interval * HZ);
 859                         return;
 860                 }
 861                 if (err != SCSI_DH_OK)
 862                         pg->flags &= ~ALUA_PG_RUN_STPG;
 863         }
 864         if (pg->flags & ALUA_PG_RUN_STPG) {
 865                 pg->flags &= ~ALUA_PG_RUN_STPG;
 866                 spin_unlock_irqrestore(&pg->lock, flags);
 867                 err = alua_stpg(sdev, pg);
 868                 spin_lock_irqsave(&pg->lock, flags);
 869                 if (err == SCSI_DH_RETRY || pg->flags & ALUA_PG_RUN_RTPG) {
 870                         pg->flags |= ALUA_PG_RUN_RTPG;
 871                         pg->interval = 0;
 872                         pg->flags &= ~ALUA_PG_RUNNING;
 873                         spin_unlock_irqrestore(&pg->lock, flags);
 874                         queue_delayed_work(kaluad_wq, &pg->rtpg_work,
 875                                            pg->interval * HZ);
 876                         return;
 877                 }
 878         }
 879
 880         list_splice_init(&pg->rtpg_list, &qdata_list);
 881         pg->rtpg_sdev = NULL;
 882         spin_unlock_irqrestore(&pg->lock, flags);
 883
 884         list_for_each_entry_safe(qdata, tmp, &qdata_list, entry) {
 885                 list_del(&qdata->entry);
 886                 if (qdata->callback_fn)
 887                         qdata->callback_fn(qdata->callback_data, err);
 888                 kfree(qdata);
 889         }
 890         spin_lock_irqsave(&pg->lock, flags);
 891         pg->flags &= ~ALUA_PG_RUNNING;
 892         spin_unlock_irqrestore(&pg->lock, flags);
 893         scsi_device_put(sdev);
 894         kref_put(&pg->kref, release_port_group);
 895 }
 896
 897 /**
 898  * alua_rtpg_queue() - cause RTPG to be submitted asynchronously
 899  * @pg: ALUA port group associated with @sdev.
 900  * @sdev: SCSI device for which to submit an RTPG.
 901  * @qdata: Information about the callback to invoke after the RTPG.
 902  * @force: Whether or not to submit an RTPG if a work item that will submit an
 903  *         RTPG already has been scheduled.
 904  *
 905  * Returns true if and only if alua_rtpg_work() will be called asynchronously.
 906  * That function is responsible for calling @qdata->fn().
 907  */
 908 static bool alua_rtpg_queue(struct alua_port_group *pg,
 909                             struct scsi_device *sdev,
 910                             struct alua_queue_data *qdata, bool force)
 911 {
 912         int start_queue = 0;
 913         unsigned long flags;
 914         if (WARN_ON_ONCE(!pg) || scsi_device_get(sdev))
 915                 return false;
 916
 917         spin_lock_irqsave(&pg->lock, flags);
 918         if (qdata) {
 919                 list_add_tail(&qdata->entry, &pg->rtpg_list);
 920                 pg->flags |= ALUA_PG_RUN_STPG;
 921                 force = true;
 922         }
 923         if (pg->rtpg_sdev == NULL) {
 924                 pg->interval = 0;
 925                 pg->flags |= ALUA_PG_RUN_RTPG;
 926                 kref_get(&pg->kref);
 927                 pg->rtpg_sdev = sdev;
 928                 start_queue = 1;
 929         } else if (!(pg->flags & ALUA_PG_RUN_RTPG) && force) {
 930                 pg->flags |= ALUA_PG_RUN_RTPG;
 931                 /* Do not queue if the worker is already running */
 932                 if (!(pg->flags & ALUA_PG_RUNNING)) {
 933                         kref_get(&pg->kref);
 934                         start_queue = 1;
 935                 }
 936         }
 937
 938         spin_unlock_irqrestore(&pg->lock, flags);
 939
 940         if (start_queue) {
 941                 if (queue_delayed_work(kaluad_wq, &pg->rtpg_work,
 942                                 msecs_to_jiffies(ALUA_RTPG_DELAY_MSECS)))
 943                         sdev = NULL;
 944                 else
 945                         kref_put(&pg->kref, release_port_group);
 946         }
 947         if (sdev)
 948                 scsi_device_put(sdev);
 949
 950         return true;
 951 }
 952
 953 /*
 954  * alua_initialize - Initialize ALUA state
 955  * @sdev: the device to be initialized
 956  *
 957  * For the prep_fn to work correctly we have
 958  * to initialize the ALUA state for the device.
 959  */
 960 static int alua_initialize(struct scsi_device *sdev, struct alua_dh_data *h)
 961 {
 962         int err = SCSI_DH_DEV_UNSUPP, tpgs;
 963
 964         mutex_lock(&h->init_mutex);
 965         tpgs = alua_check_tpgs(sdev);
 966         if (tpgs != TPGS_MODE_NONE)
 967                 err = alua_check_vpd(sdev, h, tpgs);
 968         h->init_error = err;
 969         mutex_unlock(&h->init_mutex);
 970         return err;
 971 }
 972 /*
 973  * alua_set_params - set/unset the optimize flag
 974  * @sdev: device on the path to be activated
 975  * params - parameters in the following format
 976  *      "no_of_params\0param1\0param2\0param3\0...\0"
 977  * For example, to set the flag pass the following parameters
 978  * from multipath.conf
 979  *     hardware_handler        "2 alua 1"
 980  */
 981 static int alua_set_params(struct scsi_device *sdev, const char *params)
 982 {
 983         struct alua_dh_data *h = sdev->handler_data;
 984         struct alua_port_group *pg = NULL;
 985         unsigned int optimize = 0, argc;
 986         const char *p = params;
 987         int result = SCSI_DH_OK;
 988         unsigned long flags;
 989
 990         if ((sscanf(params, "%u", &argc) != 1) || (argc != 1))
 991                 return -EINVAL;
 992
 993         while (*p++)
 994                 ;
 995         if ((sscanf(p, "%u", &optimize) != 1) || (optimize > 1))
 996                 return -EINVAL;
 997
 998         rcu_read_lock();
 999         pg = rcu_dereference(h->pg);
1000         if (!pg) {
1001                 rcu_read_unlock();
1002                 return -ENXIO;
1003         }
1004         spin_lock_irqsave(&pg->lock, flags);
1005         if (optimize)
1006                 pg->flags |= ALUA_OPTIMIZE_STPG;
1007         else
1008                 pg->flags &= ~ALUA_OPTIMIZE_STPG;
1009         spin_unlock_irqrestore(&pg->lock, flags);
1010         rcu_read_unlock();
1011
1012         return result;
1013 }
1014
1015 /*
1016  * alua_activate - activate a path
1017  * @sdev: device on the path to be activated
1018  *
1019  * We're currently switching the port group to be activated only and
1020  * let the array figure out the rest.
1021  * There may be other arrays which require us to switch all port groups
1022  * based on a certain policy. But until we actually encounter them it
1023  * should be okay.
1024  */
1025 static int alua_activate(struct scsi_device *sdev,
1026                         activate_complete fn, void *data)
1027 {
1028         struct alua_dh_data *h = sdev->handler_data;
1029         int err = SCSI_DH_OK;
1030         struct alua_queue_data *qdata;
1031         struct alua_port_group *pg;
1032
1033         qdata = kzalloc(sizeof(*qdata), GFP_KERNEL);
1034         if (!qdata) {
1035                 err = SCSI_DH_RES_TEMP_UNAVAIL;
1036                 goto out;
1037         }
1038         qdata->callback_fn = fn;
1039         qdata->callback_data = data;
1040
1041         mutex_lock(&h->init_mutex);
1042         rcu_read_lock();
1043         pg = rcu_dereference(h->pg);
1044         if (!pg || !kref_get_unless_zero(&pg->kref)) {
1045                 rcu_read_unlock();
1046                 kfree(qdata);
1047                 err = h->init_error;
1048                 mutex_unlock(&h->init_mutex);
1049                 goto out;
1050         }
1051         rcu_read_unlock();
1052         mutex_unlock(&h->init_mutex);
1053
1054         if (alua_rtpg_queue(pg, sdev, qdata, true))
1055                 fn = NULL;
1056         else
1057                 err = SCSI_DH_DEV_OFFLINED;
1058         kref_put(&pg->kref, release_port_group);
1059 out:
1060         if (fn)
1061                 fn(data, err);
1062         return 0;
1063 }
1064
1065 /*
1066  * alua_check - check path status
1067  * @sdev: device on the path to be checked
1068  *
1069  * Check the device status
1070  */
1071 static void alua_check(struct scsi_device *sdev, bool force)
1072 {
1073         struct alua_dh_data *h = sdev->handler_data;
1074         struct alua_port_group *pg;
1075
1076         rcu_read_lock();
1077         pg = rcu_dereference(h->pg);
1078         if (!pg || !kref_get_unless_zero(&pg->kref)) {
1079                 rcu_read_unlock();
1080                 return;
1081         }
1082         rcu_read_unlock();
1083
1084         alua_rtpg_queue(pg, sdev, NULL, force);
1085         kref_put(&pg->kref, release_port_group);
1086 }
1087
1088 /*
1089  * alua_prep_fn - request callback
1090  *
1091  * Fail I/O to all paths not in state
1092  * active/optimized or active/non-optimized.
1093  */
1094 static blk_status_t alua_prep_fn(struct scsi_device *sdev, struct request *req)
1095 {
1096         struct alua_dh_data *h = sdev->handler_data;
1097         struct alua_port_group *pg;
1098         unsigned char state = SCSI_ACCESS_STATE_OPTIMAL;
1099
1100         rcu_read_lock();
1101         pg = rcu_dereference(h->pg);
1102         if (pg)
1103                 state = pg->state;
1104         rcu_read_unlock();
1105
1106         switch (state) {
1107         case SCSI_ACCESS_STATE_OPTIMAL:
1108         case SCSI_ACCESS_STATE_ACTIVE:
1109         case SCSI_ACCESS_STATE_LBA:
1110                 return BLK_STS_OK;
1111         case SCSI_ACCESS_STATE_TRANSITIONING:
1112                 return BLK_STS_AGAIN;
1113         default:
1114                 req->rq_flags |= RQF_QUIET;
1115                 return BLK_STS_IOERR;
1116         }
1117 }
1118
1119 static void alua_rescan(struct scsi_device *sdev)
1120 {
1121         struct alua_dh_data *h = sdev->handler_data;
1122
1123         alua_initialize(sdev, h);
1124 }
1125
1126 /*
1127  * alua_bus_attach - Attach device handler
1128  * @sdev: device to be attached to
1129  */
1130 static int alua_bus_attach(struct scsi_device *sdev)
1131 {
1132         struct alua_dh_data *h;
1133         int err;
1134
1135         h = kzalloc(sizeof(*h) , GFP_KERNEL);
1136         if (!h)
1137                 return SCSI_DH_NOMEM;
1138         spin_lock_init(&h->pg_lock);
1139         rcu_assign_pointer(h->pg, NULL);
1140         h->init_error = SCSI_DH_OK;
1141         h->sdev = sdev;
1142         INIT_LIST_HEAD(&h->node);
1143
1144         mutex_init(&h->init_mutex);
1145         err = alua_initialize(sdev, h);
1146         if (err != SCSI_DH_OK && err != SCSI_DH_DEV_OFFLINED)
1147                 goto failed;
1148
1149         sdev->handler_data = h;
1150         return SCSI_DH_OK;
1151 failed:
1152         kfree(h);
1153         return err;
1154 }
1155
1156 /*
1157  * alua_bus_detach - Detach device handler
1158  * @sdev: device to be detached from
1159  */
1160 static void alua_bus_detach(struct scsi_device *sdev)
1161 {
1162         struct alua_dh_data *h = sdev->handler_data;
1163         struct alua_port_group *pg;
1164
1165         spin_lock(&h->pg_lock);
1166         pg = rcu_dereference_protected(h->pg, lockdep_is_held(&h->pg_lock));
1167         rcu_assign_pointer(h->pg, NULL);
1168         spin_unlock(&h->pg_lock);
1169         if (pg) {
1170                 spin_lock_irq(&pg->lock);
1171                 list_del_rcu(&h->node);
1172                 spin_unlock_irq(&pg->lock);
1173                 kref_put(&pg->kref, release_port_group);
1174         }
1175         sdev->handler_data = NULL;
1176         synchronize_rcu();
1177         kfree(h);
1178 }
1179
1180 static struct scsi_device_handler alua_dh = {
1181         .name = ALUA_DH_NAME,
1182         .module = THIS_MODULE,
1183         .attach = alua_bus_attach,
1184         .detach = alua_bus_detach,
1185         .prep_fn = alua_prep_fn,
1186         .check_sense = alua_check_sense,
1187         .activate = alua_activate,
1188         .rescan = alua_rescan,
1189         .set_params = alua_set_params,
1190 };
1191
1192 static int __init alua_init(void)
1193 {
1194         int r;
1195
1196         kaluad_wq = alloc_workqueue("kaluad", WQ_MEM_RECLAIM, 0);
1197         if (!kaluad_wq)
1198                 return -ENOMEM;
1199
1200         r = scsi_register_device_handler(&alua_dh);
1201         if (r != 0) {
1202                 printk(KERN_ERR "%s: Failed to register scsi device handler",
1203                         ALUA_DH_NAME);
1204                 destroy_workqueue(kaluad_wq);
1205         }
1206         return r;
1207 }
1208
1209 static void __exit alua_exit(void)
1210 {
1211         scsi_unregister_device_handler(&alua_dh);
1212         destroy_workqueue(kaluad_wq);
1213 }
1214
1215 module_init(alua_init);
1216 module_exit(alua_exit);
1217
1218 MODULE_DESCRIPTION("DM Multipath ALUA support");
1219 MODULE_AUTHOR("Hannes Reinecke <hare@suse.de>");
1220 MODULE_LICENSE("GPL");
1221 MODULE_VERSION(ALUA_DH_VER);