drivers/scsi/device_handler/scsi_dh_alua.c

   1 /*
   2  * Generic SCSI-3 ALUA SCSI Device Handler
   3  *
   4  * Copyright (C) 2007-2010 Hannes Reinecke, SUSE Linux Products GmbH.
   5  * All rights reserved.
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  20  *
  21  */
  22 #include <linux/slab.h>
  23 #include <linux/delay.h>
  24 #include <linux/module.h>
  25 #include <asm/unaligned.h>
  26 #include <scsi/scsi.h>
  27 #include <scsi/scsi_proto.h>
  28 #include <scsi/scsi_dbg.h>
  29 #include <scsi/scsi_eh.h>
  30 #include <scsi/scsi_dh.h>
  31
  32 #define ALUA_DH_NAME "alua"
  33 #define ALUA_DH_VER "2.0"
  34
  35 #define TPGS_SUPPORT_NONE               0x00
  36 #define TPGS_SUPPORT_OPTIMIZED          0x01
  37 #define TPGS_SUPPORT_NONOPTIMIZED       0x02
  38 #define TPGS_SUPPORT_STANDBY            0x04
  39 #define TPGS_SUPPORT_UNAVAILABLE        0x08
  40 #define TPGS_SUPPORT_LBA_DEPENDENT      0x10
  41 #define TPGS_SUPPORT_OFFLINE            0x40
  42 #define TPGS_SUPPORT_TRANSITION         0x80
  43
  44 #define RTPG_FMT_MASK                   0x70
  45 #define RTPG_FMT_EXT_HDR                0x10
  46
  47 #define TPGS_MODE_UNINITIALIZED          -1
  48 #define TPGS_MODE_NONE                  0x0
  49 #define TPGS_MODE_IMPLICIT              0x1
  50 #define TPGS_MODE_EXPLICIT              0x2
  51
  52 #define ALUA_RTPG_SIZE                  128
  53 #define ALUA_FAILOVER_TIMEOUT           60
  54 #define ALUA_FAILOVER_RETRIES           5
  55 #define ALUA_RTPG_DELAY_MSECS           5
  56 #define ALUA_RTPG_RETRY_DELAY           2
  57
  58 /* device handler flags */
  59 #define ALUA_OPTIMIZE_STPG              0x01
  60 #define ALUA_RTPG_EXT_HDR_UNSUPP        0x02
  61 #define ALUA_SYNC_STPG                  0x04
  62 /* State machine flags */
  63 #define ALUA_PG_RUN_RTPG                0x10
  64 #define ALUA_PG_RUN_STPG                0x20
  65 #define ALUA_PG_RUNNING                 0x40
  66
  67 static uint optimize_stpg;
  68 module_param(optimize_stpg, uint, S_IRUGO|S_IWUSR);
  69 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.");
  70
  71 static LIST_HEAD(port_group_list);
  72 static DEFINE_SPINLOCK(port_group_lock);
  73 static struct workqueue_struct *kaluad_wq;
  74 static struct workqueue_struct *kaluad_sync_wq;
  75
  76 struct alua_port_group {
  77         struct kref             kref;
  78         struct rcu_head         rcu;
  79         struct list_head        node;
  80         struct list_head        dh_list;
  81         unsigned char           device_id_str[256];
  82         int                     device_id_len;
  83         int                     group_id;
  84         int                     tpgs;
  85         int                     state;
  86         int                     pref;
  87         unsigned                flags; /* used for optimizing STPG */
  88         unsigned char           transition_tmo;
  89         unsigned long           expiry;
  90         unsigned long           interval;
  91         struct delayed_work     rtpg_work;
  92         spinlock_t              lock;
  93         struct list_head        rtpg_list;
  94         struct scsi_device      *rtpg_sdev;
  95 };
  96
  97 struct alua_dh_data {
  98         struct list_head        node;
  99         struct alua_port_group  *pg;
 100         int                     group_id;
 101         spinlock_t              pg_lock;
 102         struct scsi_device      *sdev;
 103         int                     init_error;
 104         struct mutex            init_mutex;
 105 };
 106
 107 struct alua_queue_data {
 108         struct list_head        entry;
 109         activate_complete       callback_fn;
 110         void                    *callback_data;
 111 };
 112
 113 #define ALUA_POLICY_SWITCH_CURRENT      0
 114 #define ALUA_POLICY_SWITCH_ALL          1
 115
 116 static void alua_rtpg_work(struct work_struct *work);
 117 static bool alua_rtpg_queue(struct alua_port_group *pg,
 118                             struct scsi_device *sdev,
 119                             struct alua_queue_data *qdata, bool force);
 120 static void alua_check(struct scsi_device *sdev, bool force);
 121
 122 static void release_port_group(struct kref *kref)
 123 {
 124         struct alua_port_group *pg;
 125
 126         pg = container_of(kref, struct alua_port_group, kref);
 127         if (pg->rtpg_sdev)
 128                 flush_delayed_work(&pg->rtpg_work);
 129         spin_lock(&port_group_lock);
 130         list_del(&pg->node);
 131         spin_unlock(&port_group_lock);
 132         kfree_rcu(pg, rcu);
 133 }
 134
 135 /*
 136  * submit_rtpg - Issue a REPORT TARGET GROUP STATES command
 137  * @sdev: sdev the command should be sent to
 138  */
 139 static int submit_rtpg(struct scsi_device *sdev, unsigned char *buff,
 140                        int bufflen, struct scsi_sense_hdr *sshdr, int flags)
 141 {
 142         u8 cdb[COMMAND_SIZE(MAINTENANCE_IN)];
 143         int req_flags = REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
 144                 REQ_FAILFAST_DRIVER;
 145
 146         /* Prepare the command. */
 147         memset(cdb, 0x0, COMMAND_SIZE(MAINTENANCE_IN));
 148         cdb[0] = MAINTENANCE_IN;
 149         if (!(flags & ALUA_RTPG_EXT_HDR_UNSUPP))
 150                 cdb[1] = MI_REPORT_TARGET_PGS | MI_EXT_HDR_PARAM_FMT;
 151         else
 152                 cdb[1] = MI_REPORT_TARGET_PGS;
 153         put_unaligned_be32(bufflen, &cdb[6]);
 154
 155         return scsi_execute_req_flags(sdev, cdb, DMA_FROM_DEVICE,
 156                                       buff, bufflen, sshdr,
 157                                       ALUA_FAILOVER_TIMEOUT * HZ,
 158                                       ALUA_FAILOVER_RETRIES, NULL, req_flags);
 159 }
 160
 161 /*
 162  * submit_stpg - Issue a SET TARGET PORT GROUP command
 163  *
 164  * Currently we're only setting the current target port group state
 165  * to 'active/optimized' and let the array firmware figure out
 166  * the states of the remaining groups.
 167  */
 168 static int submit_stpg(struct scsi_device *sdev, int group_id,
 169                        struct scsi_sense_hdr *sshdr)
 170 {
 171         u8 cdb[COMMAND_SIZE(MAINTENANCE_OUT)];
 172         unsigned char stpg_data[8];
 173         int stpg_len = 8;
 174         int req_flags = REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
 175                 REQ_FAILFAST_DRIVER;
 176
 177         /* Prepare the data buffer */
 178         memset(stpg_data, 0, stpg_len);
 179         stpg_data[4] = SCSI_ACCESS_STATE_OPTIMAL;
 180         put_unaligned_be16(group_id, &stpg_data[6]);
 181
 182         /* Prepare the command. */
 183         memset(cdb, 0x0, COMMAND_SIZE(MAINTENANCE_OUT));
 184         cdb[0] = MAINTENANCE_OUT;
 185         cdb[1] = MO_SET_TARGET_PGS;
 186         put_unaligned_be32(stpg_len, &cdb[6]);
 187
 188         return scsi_execute_req_flags(sdev, cdb, DMA_TO_DEVICE,
 189                                       stpg_data, stpg_len,
 190                                       sshdr, ALUA_FAILOVER_TIMEOUT * HZ,
 191                                       ALUA_FAILOVER_RETRIES, NULL, req_flags);
 192 }
 193
 194 static struct alua_port_group *alua_find_get_pg(char *id_str, size_t id_size,
 195                                                 int group_id)
 196 {
 197         struct alua_port_group *pg;
 198
 199         if (!id_str || !id_size || !strlen(id_str))
 200                 return NULL;
 201
 202         list_for_each_entry(pg, &port_group_list, node) {
 203                 if (pg->group_id != group_id)
 204                         continue;
 205                 if (!pg->device_id_len || pg->device_id_len != id_size)
 206                         continue;
 207                 if (strncmp(pg->device_id_str, id_str, id_size))
 208                         continue;
 209                 if (!kref_get_unless_zero(&pg->kref))
 210                         continue;
 211                 return pg;
 212         }
 213
 214         return NULL;
 215 }
 216
 217 /*
 218  * alua_alloc_pg - Allocate a new port_group structure
 219  * @sdev: scsi device
 220  * @h: alua device_handler data
 221  * @group_id: port group id
 222  *
 223  * Allocate a new port_group structure for a given
 224  * device.
 225  */
 226 static struct alua_port_group *alua_alloc_pg(struct scsi_device *sdev,
 227                                              int group_id, int tpgs)
 228 {
 229         struct alua_port_group *pg, *tmp_pg;
 230
 231         pg = kzalloc(sizeof(struct alua_port_group), GFP_KERNEL);
 232         if (!pg)
 233                 return ERR_PTR(-ENOMEM);
 234
 235         pg->device_id_len = scsi_vpd_lun_id(sdev, pg->device_id_str,
 236                                             sizeof(pg->device_id_str));
 237         if (pg->device_id_len <= 0) {
 238                 /*
 239                  * TPGS supported but no device identification found.
 240                  * Generate private device identification.
 241                  */
 242                 sdev_printk(KERN_INFO, sdev,
 243                             "%s: No device descriptors found\n",
 244                             ALUA_DH_NAME);
 245                 pg->device_id_str[0] = '\0';
 246                 pg->device_id_len = 0;
 247         }
 248         pg->group_id = group_id;
 249         pg->tpgs = tpgs;
 250         pg->state = SCSI_ACCESS_STATE_OPTIMAL;
 251         if (optimize_stpg)
 252                 pg->flags |= ALUA_OPTIMIZE_STPG;
 253         kref_init(&pg->kref);
 254         INIT_DELAYED_WORK(&pg->rtpg_work, alua_rtpg_work);
 255         INIT_LIST_HEAD(&pg->rtpg_list);
 256         INIT_LIST_HEAD(&pg->node);
 257         INIT_LIST_HEAD(&pg->dh_list);
 258         spin_lock_init(&pg->lock);
 259
 260         spin_lock(&port_group_lock);
 261         tmp_pg = alua_find_get_pg(pg->device_id_str, pg->device_id_len,
 262                                   group_id);
 263         if (tmp_pg) {
 264                 spin_unlock(&port_group_lock);
 265                 kfree(pg);
 266                 return tmp_pg;
 267         }
 268
 269         list_add(&pg->node, &port_group_list);
 270         spin_unlock(&port_group_lock);
 271
 272         return pg;
 273 }
 274
 275 /*
 276  * alua_check_tpgs - Evaluate TPGS setting
 277  * @sdev: device to be checked
 278  *
 279  * Examine the TPGS setting of the sdev to find out if ALUA
 280  * is supported.
 281  */
 282 static int alua_check_tpgs(struct scsi_device *sdev)
 283 {
 284         int tpgs = TPGS_MODE_NONE;
 285
 286         /*
 287          * ALUA support for non-disk devices is fraught with
 288          * difficulties, so disable it for now.
 289          */
 290         if (sdev->type != TYPE_DISK) {
 291                 sdev_printk(KERN_INFO, sdev,
 292                             "%s: disable for non-disk devices\n",
 293                             ALUA_DH_NAME);
 294                 return tpgs;
 295         }
 296
 297         tpgs = scsi_device_tpgs(sdev);
 298         switch (tpgs) {
 299         case TPGS_MODE_EXPLICIT|TPGS_MODE_IMPLICIT:
 300                 sdev_printk(KERN_INFO, sdev,
 301                             "%s: supports implicit and explicit TPGS\n",
 302                             ALUA_DH_NAME);
 303                 break;
 304         case TPGS_MODE_EXPLICIT:
 305                 sdev_printk(KERN_INFO, sdev, "%s: supports explicit TPGS\n",
 306                             ALUA_DH_NAME);
 307                 break;
 308         case TPGS_MODE_IMPLICIT:
 309                 sdev_printk(KERN_INFO, sdev, "%s: supports implicit TPGS\n",
 310                             ALUA_DH_NAME);
 311                 break;
 312         case TPGS_MODE_NONE:
 313                 sdev_printk(KERN_INFO, sdev, "%s: not supported\n",
 314                             ALUA_DH_NAME);
 315                 break;
 316         default:
 317                 sdev_printk(KERN_INFO, sdev,
 318                             "%s: unsupported TPGS setting %d\n",
 319                             ALUA_DH_NAME, tpgs);
 320                 tpgs = TPGS_MODE_NONE;
 321                 break;
 322         }
 323
 324         return tpgs;
 325 }
 326
 327 /*
 328  * alua_check_vpd - Evaluate INQUIRY vpd page 0x83
 329  * @sdev: device to be checked
 330  *
 331  * Extract the relative target port and the target port group
 332  * descriptor from the list of identificators.
 333  */
 334 static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h,
 335                           int tpgs)
 336 {
 337         int rel_port = -1, group_id;
 338         struct alua_port_group *pg, *old_pg = NULL;
 339         bool pg_updated = false;
 340         unsigned long flags;
 341
 342         group_id = scsi_vpd_tpg_id(sdev, &rel_port);
 343         if (group_id < 0) {
 344                 /*
 345                  * Internal error; TPGS supported but required
 346                  * VPD identification descriptors not present.
 347                  * Disable ALUA support
 348                  */
 349                 sdev_printk(KERN_INFO, sdev,
 350                             "%s: No target port descriptors found\n",
 351                             ALUA_DH_NAME);
 352                 return SCSI_DH_DEV_UNSUPP;
 353         }
 354
 355         pg = alua_alloc_pg(sdev, group_id, tpgs);
 356         if (IS_ERR(pg)) {
 357                 if (PTR_ERR(pg) == -ENOMEM)
 358                         return SCSI_DH_NOMEM;
 359                 return SCSI_DH_DEV_UNSUPP;
 360         }
 361         if (pg->device_id_len)
 362                 sdev_printk(KERN_INFO, sdev,
 363                             "%s: device %s port group %x rel port %x\n",
 364                             ALUA_DH_NAME, pg->device_id_str,
 365                             group_id, rel_port);
 366         else
 367                 sdev_printk(KERN_INFO, sdev,
 368                             "%s: port group %x rel port %x\n",
 369                             ALUA_DH_NAME, group_id, rel_port);
 370
 371         /* Check for existing port group references */
 372         spin_lock(&h->pg_lock);
 373         old_pg = h->pg;
 374         if (old_pg != pg) {
 375                 /* port group has changed. Update to new port group */
 376                 if (h->pg) {
 377                         spin_lock_irqsave(&old_pg->lock, flags);
 378                         list_del_rcu(&h->node);
 379                         spin_unlock_irqrestore(&old_pg->lock, flags);
 380                 }
 381                 rcu_assign_pointer(h->pg, pg);
 382                 pg_updated = true;
 383         }
 384
 385         spin_lock_irqsave(&pg->lock, flags);
 386         if (sdev->synchronous_alua)
 387                 pg->flags |= ALUA_SYNC_STPG;
 388         if (pg_updated)
 389                 list_add_rcu(&h->node, &pg->dh_list);
 390         spin_unlock_irqrestore(&pg->lock, flags);
 391
 392         alua_rtpg_queue(h->pg, sdev, NULL, true);
 393         spin_unlock(&h->pg_lock);
 394
 395         if (old_pg)
 396                 kref_put(&old_pg->kref, release_port_group);
 397
 398         return SCSI_DH_OK;
 399 }
 400
 401 static char print_alua_state(unsigned char state)
 402 {
 403         switch (state) {
 404         case SCSI_ACCESS_STATE_OPTIMAL:
 405                 return 'A';
 406         case SCSI_ACCESS_STATE_ACTIVE:
 407                 return 'N';
 408         case SCSI_ACCESS_STATE_STANDBY:
 409                 return 'S';
 410         case SCSI_ACCESS_STATE_UNAVAILABLE:
 411                 return 'U';
 412         case SCSI_ACCESS_STATE_LBA:
 413                 return 'L';
 414         case SCSI_ACCESS_STATE_OFFLINE:
 415                 return 'O';
 416         case SCSI_ACCESS_STATE_TRANSITIONING:
 417                 return 'T';
 418         default:
 419                 return 'X';
 420         }
 421 }
 422
 423 static int alua_check_sense(struct scsi_device *sdev,
 424                             struct scsi_sense_hdr *sense_hdr)
 425 {
 426         switch (sense_hdr->sense_key) {
 427         case NOT_READY:
 428                 if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0a) {
 429                         /*
 430                          * LUN Not Accessible - ALUA state transition
 431                          */
 432                         alua_check(sdev, false);
 433                         return NEEDS_RETRY;
 434                 }
 435                 break;
 436         case UNIT_ATTENTION:
 437                 if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00) {
 438                         /*
 439                          * Power On, Reset, or Bus Device Reset.
 440                          * Might have obscured a state transition,
 441                          * so schedule a recheck.
 442                          */
 443                         alua_check(sdev, true);
 444                         return ADD_TO_MLQUEUE;
 445                 }
 446                 if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x04)
 447                         /*
 448                          * Device internal reset
 449                          */
 450                         return ADD_TO_MLQUEUE;
 451                 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x01)
 452                         /*
 453                          * Mode Parameters Changed
 454                          */
 455                         return ADD_TO_MLQUEUE;
 456                 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x06) {
 457                         /*
 458                          * ALUA state changed
 459                          */
 460                         alua_check(sdev, true);
 461                         return ADD_TO_MLQUEUE;
 462                 }
 463                 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x07) {
 464                         /*
 465                          * Implicit ALUA state transition failed
 466                          */
 467                         alua_check(sdev, true);
 468                         return ADD_TO_MLQUEUE;
 469                 }
 470                 if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x03)
 471                         /*
 472                          * Inquiry data has changed
 473                          */
 474                         return ADD_TO_MLQUEUE;
 475                 if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x0e)
 476                         /*
 477                          * REPORTED_LUNS_DATA_HAS_CHANGED is reported
 478                          * when switching controllers on targets like
 479                          * Intel Multi-Flex. We can just retry.
 480                          */
 481                         return ADD_TO_MLQUEUE;
 482                 break;
 483         }
 484
 485         return SCSI_RETURN_NOT_HANDLED;
 486 }
 487
 488 /*
 489  * alua_tur - Send a TEST UNIT READY
 490  * @sdev: device to which the TEST UNIT READY command should be send
 491  *
 492  * Send a TEST UNIT READY to @sdev to figure out the device state
 493  * Returns SCSI_DH_RETRY if the sense code is NOT READY/ALUA TRANSITIONING,
 494  * SCSI_DH_OK if no error occurred, and SCSI_DH_IO otherwise.
 495  */
 496 static int alua_tur(struct scsi_device *sdev)
 497 {
 498         struct scsi_sense_hdr sense_hdr;
 499         int retval;
 500
 501         retval = scsi_test_unit_ready(sdev, ALUA_FAILOVER_TIMEOUT * HZ,
 502                                       ALUA_FAILOVER_RETRIES, &sense_hdr);
 503         if (sense_hdr.sense_key == NOT_READY &&
 504             sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a)
 505                 return SCSI_DH_RETRY;
 506         else if (retval)
 507                 return SCSI_DH_IO;
 508         else
 509                 return SCSI_DH_OK;
 510 }
 511
 512 /*
 513  * alua_rtpg - Evaluate REPORT TARGET GROUP STATES
 514  * @sdev: the device to be evaluated.
 515  *
 516  * Evaluate the Target Port Group State.
 517  * Returns SCSI_DH_DEV_OFFLINED if the path is
 518  * found to be unusable.
 519  */
 520 static int alua_rtpg(struct scsi_device *sdev, struct alua_port_group *pg)
 521 {
 522         struct scsi_sense_hdr sense_hdr;
 523         struct alua_port_group *tmp_pg;
 524         int len, k, off, valid_states = 0, bufflen = ALUA_RTPG_SIZE;
 525         unsigned char *desc, *buff;
 526         unsigned err, retval;
 527         unsigned int tpg_desc_tbl_off;
 528         unsigned char orig_transition_tmo;
 529         unsigned long flags;
 530         bool transitioning_sense = false;
 531
 532         if (!pg->expiry) {
 533                 unsigned long transition_tmo = ALUA_FAILOVER_TIMEOUT * HZ;
 534
 535                 if (pg->transition_tmo)
 536                         transition_tmo = pg->transition_tmo * HZ;
 537
 538                 pg->expiry = round_jiffies_up(jiffies + transition_tmo);
 539         }
 540
 541         buff = kzalloc(bufflen, GFP_KERNEL);
 542         if (!buff)
 543                 return SCSI_DH_DEV_TEMP_BUSY;
 544
 545  retry:
 546         err = 0;
 547         retval = submit_rtpg(sdev, buff, bufflen, &sense_hdr, pg->flags);
 548
 549         if (retval) {
 550                 if (!scsi_sense_valid(&sense_hdr)) {
 551                         sdev_printk(KERN_INFO, sdev,
 552                                     "%s: rtpg failed, result %d\n",
 553                                     ALUA_DH_NAME, retval);
 554                         kfree(buff);
 555                         if (driver_byte(retval) == DRIVER_ERROR)
 556                                 return SCSI_DH_DEV_TEMP_BUSY;
 557                         return SCSI_DH_IO;
 558                 }
 559
 560                 /*
 561                  * submit_rtpg() has failed on existing arrays
 562                  * when requesting extended header info, and
 563                  * the array doesn't support extended headers,
 564                  * even though it shouldn't according to T10.
 565                  * The retry without rtpg_ext_hdr_req set
 566                  * handles this.
 567                  * Note:  some arrays return a sense key of ILLEGAL_REQUEST
 568                  * with ASC 00h if they don't support the extended header.
 569                  */
 570                 if (!(pg->flags & ALUA_RTPG_EXT_HDR_UNSUPP) &&
 571                     sense_hdr.sense_key == ILLEGAL_REQUEST) {
 572                         pg->flags |= ALUA_RTPG_EXT_HDR_UNSUPP;
 573                         goto retry;
 574                 }
 575                 /*
 576                  * If the array returns with 'ALUA state transition'
 577                  * sense code here it cannot return RTPG data during
 578                  * transition. So set the state to 'transitioning' directly.
 579                  */
 580                 if (sense_hdr.sense_key == NOT_READY &&
 581                     sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a) {
 582                         transitioning_sense = true;
 583                         goto skip_rtpg;
 584                 }
 585                 /*
 586                  * Retry on any other UNIT ATTENTION occurred.
 587                  */
 588                 if (sense_hdr.sense_key == UNIT_ATTENTION)
 589                         err = SCSI_DH_RETRY;
 590                 if (err == SCSI_DH_RETRY &&
 591                     pg->expiry != 0 && time_before(jiffies, pg->expiry)) {
 592                         sdev_printk(KERN_ERR, sdev, "%s: rtpg retry\n",
 593                                     ALUA_DH_NAME);
 594                         scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
 595                         kfree(buff);
 596                         return err;
 597                 }
 598                 sdev_printk(KERN_ERR, sdev, "%s: rtpg failed\n",
 599                             ALUA_DH_NAME);
 600                 scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
 601                 kfree(buff);
 602                 pg->expiry = 0;
 603                 return SCSI_DH_IO;
 604         }
 605
 606         len = get_unaligned_be32(&buff[0]) + 4;
 607
 608         if (len > bufflen) {
 609                 /* Resubmit with the correct length */
 610                 kfree(buff);
 611                 bufflen = len;
 612                 buff = kmalloc(bufflen, GFP_KERNEL);
 613                 if (!buff) {
 614                         sdev_printk(KERN_WARNING, sdev,
 615                                     "%s: kmalloc buffer failed\n",__func__);
 616                         /* Temporary failure, bypass */
 617                         pg->expiry = 0;
 618                         return SCSI_DH_DEV_TEMP_BUSY;
 619                 }
 620                 goto retry;
 621         }
 622
 623         orig_transition_tmo = pg->transition_tmo;
 624         if ((buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR && buff[5] != 0)
 625                 pg->transition_tmo = buff[5];
 626         else
 627                 pg->transition_tmo = ALUA_FAILOVER_TIMEOUT;
 628
 629         if (orig_transition_tmo != pg->transition_tmo) {
 630                 sdev_printk(KERN_INFO, sdev,
 631                             "%s: transition timeout set to %d seconds\n",
 632                             ALUA_DH_NAME, pg->transition_tmo);
 633                 pg->expiry = jiffies + pg->transition_tmo * HZ;
 634         }
 635
 636         if ((buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR)
 637                 tpg_desc_tbl_off = 8;
 638         else
 639                 tpg_desc_tbl_off = 4;
 640
 641         for (k = tpg_desc_tbl_off, desc = buff + tpg_desc_tbl_off;
 642              k < len;
 643              k += off, desc += off) {
 644                 u16 group_id = get_unaligned_be16(&desc[2]);
 645
 646                 spin_lock_irqsave(&port_group_lock, flags);
 647                 tmp_pg = alua_find_get_pg(pg->device_id_str, pg->device_id_len,
 648                                           group_id);
 649                 spin_unlock_irqrestore(&port_group_lock, flags);
 650                 if (tmp_pg) {
 651                         if (spin_trylock_irqsave(&tmp_pg->lock, flags)) {
 652                                 if ((tmp_pg == pg) ||
 653                                     !(tmp_pg->flags & ALUA_PG_RUNNING)) {
 654                                         struct alua_dh_data *h;
 655
 656                                         tmp_pg->state = desc[0] & 0x0f;
 657                                         tmp_pg->pref = desc[0] >> 7;
 658                                         rcu_read_lock();
 659                                         list_for_each_entry_rcu(h,
 660                                                 &tmp_pg->dh_list, node) {
 661                                                 if (!h->sdev)
 662                                                         continue;
 663                                                 h->sdev->access_state = desc[0];
 664                                         }
 665                                         rcu_read_unlock();
 666                                 }
 667                                 if (tmp_pg == pg)
 668                                         valid_states = desc[1];
 669                                 spin_unlock_irqrestore(&tmp_pg->lock, flags);
 670                         }
 671                         kref_put(&tmp_pg->kref, release_port_group);
 672                 }
 673                 off = 8 + (desc[7] * 4);
 674         }
 675
 676  skip_rtpg:
 677         spin_lock_irqsave(&pg->lock, flags);
 678         if (transitioning_sense)
 679                 pg->state = SCSI_ACCESS_STATE_TRANSITIONING;
 680
 681         sdev_printk(KERN_INFO, sdev,
 682                     "%s: port group %02x state %c %s supports %c%c%c%c%c%c%c\n",
 683                     ALUA_DH_NAME, pg->group_id, print_alua_state(pg->state),
 684                     pg->pref ? "preferred" : "non-preferred",
 685                     valid_states&TPGS_SUPPORT_TRANSITION?'T':'t',
 686                     valid_states&TPGS_SUPPORT_OFFLINE?'O':'o',
 687                     valid_states&TPGS_SUPPORT_LBA_DEPENDENT?'L':'l',
 688                     valid_states&TPGS_SUPPORT_UNAVAILABLE?'U':'u',
 689                     valid_states&TPGS_SUPPORT_STANDBY?'S':'s',
 690                     valid_states&TPGS_SUPPORT_NONOPTIMIZED?'N':'n',
 691                     valid_states&TPGS_SUPPORT_OPTIMIZED?'A':'a');
 692
 693         switch (pg->state) {
 694         case SCSI_ACCESS_STATE_TRANSITIONING:
 695                 if (time_before(jiffies, pg->expiry)) {
 696                         /* State transition, retry */
 697                         pg->interval = ALUA_RTPG_RETRY_DELAY;
 698                         err = SCSI_DH_RETRY;
 699                 } else {
 700                         struct alua_dh_data *h;
 701
 702                         /* Transitioning time exceeded, set port to standby */
 703                         err = SCSI_DH_IO;
 704                         pg->state = SCSI_ACCESS_STATE_STANDBY;
 705                         pg->expiry = 0;
 706                         rcu_read_lock();
 707                         list_for_each_entry_rcu(h, &pg->dh_list, node) {
 708                                 if (!h->sdev)
 709                                         continue;
 710                                 h->sdev->access_state =
 711                                         (pg->state & SCSI_ACCESS_STATE_MASK);
 712                                 if (pg->pref)
 713                                         h->sdev->access_state |=
 714                                                 SCSI_ACCESS_STATE_PREFERRED;
 715                         }
 716                         rcu_read_unlock();
 717                 }
 718                 break;
 719         case SCSI_ACCESS_STATE_OFFLINE:
 720                 /* Path unusable */
 721                 err = SCSI_DH_DEV_OFFLINED;
 722                 pg->expiry = 0;
 723                 break;
 724         default:
 725                 /* Useable path if active */
 726                 err = SCSI_DH_OK;
 727                 pg->expiry = 0;
 728                 break;
 729         }
 730         spin_unlock_irqrestore(&pg->lock, flags);
 731         kfree(buff);
 732         return err;
 733 }
 734
 735 /*
 736  * alua_stpg - Issue a SET TARGET PORT GROUP command
 737  *
 738  * Issue a SET TARGET PORT GROUP command and evaluate the
 739  * response. Returns SCSI_DH_RETRY per default to trigger
 740  * a re-evaluation of the target group state or SCSI_DH_OK
 741  * if no further action needs to be taken.
 742  */
 743 static unsigned alua_stpg(struct scsi_device *sdev, struct alua_port_group *pg)
 744 {
 745         int retval;
 746         struct scsi_sense_hdr sense_hdr;
 747
 748         if (!(pg->tpgs & TPGS_MODE_EXPLICIT)) {
 749                 /* Only implicit ALUA supported, retry */
 750                 return SCSI_DH_RETRY;
 751         }
 752         switch (pg->state) {
 753         case SCSI_ACCESS_STATE_OPTIMAL:
 754                 return SCSI_DH_OK;
 755         case SCSI_ACCESS_STATE_ACTIVE:
 756                 if ((pg->flags & ALUA_OPTIMIZE_STPG) &&
 757                     !pg->pref &&
 758                     (pg->tpgs & TPGS_MODE_IMPLICIT))
 759                         return SCSI_DH_OK;
 760                 break;
 761         case SCSI_ACCESS_STATE_STANDBY:
 762         case SCSI_ACCESS_STATE_UNAVAILABLE:
 763                 break;
 764         case SCSI_ACCESS_STATE_OFFLINE:
 765                 return SCSI_DH_IO;
 766         case SCSI_ACCESS_STATE_TRANSITIONING:
 767                 break;
 768         default:
 769                 sdev_printk(KERN_INFO, sdev,
 770                             "%s: stpg failed, unhandled TPGS state %d",
 771                             ALUA_DH_NAME, pg->state);
 772                 return SCSI_DH_NOSYS;
 773         }
 774         retval = submit_stpg(sdev, pg->group_id, &sense_hdr);
 775
 776         if (retval) {
 777                 if (!scsi_sense_valid(&sense_hdr)) {
 778                         sdev_printk(KERN_INFO, sdev,
 779                                     "%s: stpg failed, result %d",
 780                                     ALUA_DH_NAME, retval);
 781                         if (driver_byte(retval) == DRIVER_ERROR)
 782                                 return SCSI_DH_DEV_TEMP_BUSY;
 783                 } else {
 784                         sdev_printk(KERN_INFO, sdev, "%s: stpg failed\n",
 785                                     ALUA_DH_NAME);
 786                         scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
 787                 }
 788         }
 789         /* Retry RTPG */
 790         return SCSI_DH_RETRY;
 791 }
 792
 793 static void alua_rtpg_work(struct work_struct *work)
 794 {
 795         struct alua_port_group *pg =
 796                 container_of(work, struct alua_port_group, rtpg_work.work);
 797         struct scsi_device *sdev;
 798         LIST_HEAD(qdata_list);
 799         int err = SCSI_DH_OK;
 800         struct alua_queue_data *qdata, *tmp;
 801         unsigned long flags;
 802         struct workqueue_struct *alua_wq = kaluad_wq;
 803
 804         spin_lock_irqsave(&pg->lock, flags);
 805         sdev = pg->rtpg_sdev;
 806         if (!sdev) {
 807                 WARN_ON(pg->flags & ALUA_PG_RUN_RTPG);
 808                 WARN_ON(pg->flags & ALUA_PG_RUN_STPG);
 809                 spin_unlock_irqrestore(&pg->lock, flags);
 810                 kref_put(&pg->kref, release_port_group);
 811                 return;
 812         }
 813         if (pg->flags & ALUA_SYNC_STPG)
 814                 alua_wq = kaluad_sync_wq;
 815         pg->flags |= ALUA_PG_RUNNING;
 816         if (pg->flags & ALUA_PG_RUN_RTPG) {
 817                 int state = pg->state;
 818
 819                 pg->flags &= ~ALUA_PG_RUN_RTPG;
 820                 spin_unlock_irqrestore(&pg->lock, flags);
 821                 if (state == SCSI_ACCESS_STATE_TRANSITIONING) {
 822                         if (alua_tur(sdev) == SCSI_DH_RETRY) {
 823                                 spin_lock_irqsave(&pg->lock, flags);
 824                                 pg->flags &= ~ALUA_PG_RUNNING;
 825                                 pg->flags |= ALUA_PG_RUN_RTPG;
 826                                 if (!pg->interval)
 827                                         pg->interval = ALUA_RTPG_RETRY_DELAY;
 828                                 spin_unlock_irqrestore(&pg->lock, flags);
 829                                 queue_delayed_work(alua_wq, &pg->rtpg_work,
 830                                                    pg->interval * HZ);
 831                                 return;
 832                         }
 833                         /* Send RTPG on failure or if TUR indicates SUCCESS */
 834                 }
 835                 err = alua_rtpg(sdev, pg);
 836                 spin_lock_irqsave(&pg->lock, flags);
 837                 if (err == SCSI_DH_RETRY || pg->flags & ALUA_PG_RUN_RTPG) {
 838                         pg->flags &= ~ALUA_PG_RUNNING;
 839                         if (!pg->interval && !(pg->flags & ALUA_PG_RUN_RTPG))
 840                                 pg->interval = ALUA_RTPG_RETRY_DELAY;
 841                         pg->flags |= ALUA_PG_RUN_RTPG;
 842                         spin_unlock_irqrestore(&pg->lock, flags);
 843                         queue_delayed_work(alua_wq, &pg->rtpg_work,
 844                                            pg->interval * HZ);
 845                         return;
 846                 }
 847                 if (err != SCSI_DH_OK)
 848                         pg->flags &= ~ALUA_PG_RUN_STPG;
 849         }
 850         if (pg->flags & ALUA_PG_RUN_STPG) {
 851                 pg->flags &= ~ALUA_PG_RUN_STPG;
 852                 spin_unlock_irqrestore(&pg->lock, flags);
 853                 err = alua_stpg(sdev, pg);
 854                 spin_lock_irqsave(&pg->lock, flags);
 855                 if (err == SCSI_DH_RETRY || pg->flags & ALUA_PG_RUN_RTPG) {
 856                         pg->flags |= ALUA_PG_RUN_RTPG;
 857                         pg->interval = 0;
 858                         pg->flags &= ~ALUA_PG_RUNNING;
 859                         spin_unlock_irqrestore(&pg->lock, flags);
 860                         queue_delayed_work(alua_wq, &pg->rtpg_work,
 861                                            pg->interval * HZ);
 862                         return;
 863                 }
 864         }
 865
 866         list_splice_init(&pg->rtpg_list, &qdata_list);
 867         pg->rtpg_sdev = NULL;
 868         spin_unlock_irqrestore(&pg->lock, flags);
 869
 870         list_for_each_entry_safe(qdata, tmp, &qdata_list, entry) {
 871                 list_del(&qdata->entry);
 872                 if (qdata->callback_fn)
 873                         qdata->callback_fn(qdata->callback_data, err);
 874                 kfree(qdata);
 875         }
 876         spin_lock_irqsave(&pg->lock, flags);
 877         pg->flags &= ~ALUA_PG_RUNNING;
 878         spin_unlock_irqrestore(&pg->lock, flags);
 879         scsi_device_put(sdev);
 880         kref_put(&pg->kref, release_port_group);
 881 }
 882
 883 /**
 884  * alua_rtpg_queue() - cause RTPG to be submitted asynchronously
 885  *
 886  * Returns true if and only if alua_rtpg_work() will be called asynchronously.
 887  * That function is responsible for calling @qdata->fn().
 888  */
 889 static bool alua_rtpg_queue(struct alua_port_group *pg,
 890                             struct scsi_device *sdev,
 891                             struct alua_queue_data *qdata, bool force)
 892 {
 893         int start_queue = 0;
 894         unsigned long flags;
 895         struct workqueue_struct *alua_wq = kaluad_wq;
 896
 897         if (!pg || scsi_device_get(sdev))
 898                 return false;
 899
 900         spin_lock_irqsave(&pg->lock, flags);
 901         if (qdata) {
 902                 list_add_tail(&qdata->entry, &pg->rtpg_list);
 903                 pg->flags |= ALUA_PG_RUN_STPG;
 904                 force = true;
 905         }
 906         if (pg->rtpg_sdev == NULL) {
 907                 pg->interval = 0;
 908                 pg->flags |= ALUA_PG_RUN_RTPG;
 909                 kref_get(&pg->kref);
 910                 pg->rtpg_sdev = sdev;
 911                 start_queue = 1;
 912         } else if (!(pg->flags & ALUA_PG_RUN_RTPG) && force) {
 913                 pg->flags |= ALUA_PG_RUN_RTPG;
 914                 /* Do not queue if the worker is already running */
 915                 if (!(pg->flags & ALUA_PG_RUNNING)) {
 916                         kref_get(&pg->kref);
 917                         start_queue = 1;
 918                 }
 919         }
 920
 921         if (pg->flags & ALUA_SYNC_STPG)
 922                 alua_wq = kaluad_sync_wq;
 923         spin_unlock_irqrestore(&pg->lock, flags);
 924
 925         if (start_queue) {
 926                 if (queue_delayed_work(alua_wq, &pg->rtpg_work,
 927                                 msecs_to_jiffies(ALUA_RTPG_DELAY_MSECS)))
 928                         sdev = NULL;
 929                 else
 930                         kref_put(&pg->kref, release_port_group);
 931         }
 932         if (sdev)
 933                 scsi_device_put(sdev);
 934
 935         return true;
 936 }
 937
 938 /*
 939  * alua_initialize - Initialize ALUA state
 940  * @sdev: the device to be initialized
 941  *
 942  * For the prep_fn to work correctly we have
 943  * to initialize the ALUA state for the device.
 944  */
 945 static int alua_initialize(struct scsi_device *sdev, struct alua_dh_data *h)
 946 {
 947         int err = SCSI_DH_DEV_UNSUPP, tpgs;
 948
 949         mutex_lock(&h->init_mutex);
 950         tpgs = alua_check_tpgs(sdev);
 951         if (tpgs != TPGS_MODE_NONE)
 952                 err = alua_check_vpd(sdev, h, tpgs);
 953         h->init_error = err;
 954         mutex_unlock(&h->init_mutex);
 955         return err;
 956 }
 957 /*
 958  * alua_set_params - set/unset the optimize flag
 959  * @sdev: device on the path to be activated
 960  * params - parameters in the following format
 961  *      "no_of_params\0param1\0param2\0param3\0...\0"
 962  * For example, to set the flag pass the following parameters
 963  * from multipath.conf
 964  *     hardware_handler        "2 alua 1"
 965  */
 966 static int alua_set_params(struct scsi_device *sdev, const char *params)
 967 {
 968         struct alua_dh_data *h = sdev->handler_data;
 969         struct alua_port_group __rcu *pg = NULL;
 970         unsigned int optimize = 0, argc;
 971         const char *p = params;
 972         int result = SCSI_DH_OK;
 973         unsigned long flags;
 974
 975         if ((sscanf(params, "%u", &argc) != 1) || (argc != 1))
 976                 return -EINVAL;
 977
 978         while (*p++)
 979                 ;
 980         if ((sscanf(p, "%u", &optimize) != 1) || (optimize > 1))
 981                 return -EINVAL;
 982
 983         rcu_read_lock();
 984         pg = rcu_dereference(h->pg);
 985         if (!pg) {
 986                 rcu_read_unlock();
 987                 return -ENXIO;
 988         }
 989         spin_lock_irqsave(&pg->lock, flags);
 990         if (optimize)
 991                 pg->flags |= ALUA_OPTIMIZE_STPG;
 992         else
 993                 pg->flags &= ~ALUA_OPTIMIZE_STPG;
 994         spin_unlock_irqrestore(&pg->lock, flags);
 995         rcu_read_unlock();
 996
 997         return result;
 998 }
 999
1000 /*
1001  * alua_activate - activate a path
1002  * @sdev: device on the path to be activated
1003  *
1004  * We're currently switching the port group to be activated only and
1005  * let the array figure out the rest.
1006  * There may be other arrays which require us to switch all port groups
1007  * based on a certain policy. But until we actually encounter them it
1008  * should be okay.
1009  */
1010 static int alua_activate(struct scsi_device *sdev,
1011                         activate_complete fn, void *data)
1012 {
1013         struct alua_dh_data *h = sdev->handler_data;
1014         int err = SCSI_DH_OK;
1015         struct alua_queue_data *qdata;
1016         struct alua_port_group __rcu *pg;
1017
1018         qdata = kzalloc(sizeof(*qdata), GFP_KERNEL);
1019         if (!qdata) {
1020                 err = SCSI_DH_RES_TEMP_UNAVAIL;
1021                 goto out;
1022         }
1023         qdata->callback_fn = fn;
1024         qdata->callback_data = data;
1025
1026         mutex_lock(&h->init_mutex);
1027         rcu_read_lock();
1028         pg = rcu_dereference(h->pg);
1029         if (!pg || !kref_get_unless_zero(&pg->kref)) {
1030                 rcu_read_unlock();
1031                 kfree(qdata);
1032                 err = h->init_error;
1033                 mutex_unlock(&h->init_mutex);
1034                 goto out;
1035         }
1036         rcu_read_unlock();
1037         mutex_unlock(&h->init_mutex);
1038
1039         if (alua_rtpg_queue(pg, sdev, qdata, true))
1040                 fn = NULL;
1041         else
1042                 err = SCSI_DH_DEV_OFFLINED;
1043         kref_put(&pg->kref, release_port_group);
1044 out:
1045         if (fn)
1046                 fn(data, err);
1047         return 0;
1048 }
1049
1050 /*
1051  * alua_check - check path status
1052  * @sdev: device on the path to be checked
1053  *
1054  * Check the device status
1055  */
1056 static void alua_check(struct scsi_device *sdev, bool force)
1057 {
1058         struct alua_dh_data *h = sdev->handler_data;
1059         struct alua_port_group *pg;
1060
1061         rcu_read_lock();
1062         pg = rcu_dereference(h->pg);
1063         if (!pg || !kref_get_unless_zero(&pg->kref)) {
1064                 rcu_read_unlock();
1065                 return;
1066         }
1067         rcu_read_unlock();
1068
1069         alua_rtpg_queue(pg, sdev, NULL, force);
1070         kref_put(&pg->kref, release_port_group);
1071 }
1072
1073 /*
1074  * alua_prep_fn - request callback
1075  *
1076  * Fail I/O to all paths not in state
1077  * active/optimized or active/non-optimized.
1078  */
1079 static int alua_prep_fn(struct scsi_device *sdev, struct request *req)
1080 {
1081         struct alua_dh_data *h = sdev->handler_data;
1082         struct alua_port_group __rcu *pg;
1083         unsigned char state = SCSI_ACCESS_STATE_OPTIMAL;
1084         int ret = BLKPREP_OK;
1085
1086         rcu_read_lock();
1087         pg = rcu_dereference(h->pg);
1088         if (pg)
1089                 state = pg->state;
1090         rcu_read_unlock();
1091         if (state == SCSI_ACCESS_STATE_TRANSITIONING)
1092                 ret = BLKPREP_DEFER;
1093         else if (state != SCSI_ACCESS_STATE_OPTIMAL &&
1094                  state != SCSI_ACCESS_STATE_ACTIVE &&
1095                  state != SCSI_ACCESS_STATE_LBA) {
1096                 ret = BLKPREP_KILL;
1097                 req->cmd_flags |= REQ_QUIET;
1098         }
1099         return ret;
1100
1101 }
1102
1103 static void alua_rescan(struct scsi_device *sdev)
1104 {
1105         struct alua_dh_data *h = sdev->handler_data;
1106
1107         alua_initialize(sdev, h);
1108 }
1109
1110 /*
1111  * alua_bus_attach - Attach device handler
1112  * @sdev: device to be attached to
1113  */
1114 static int alua_bus_attach(struct scsi_device *sdev)
1115 {
1116         struct alua_dh_data *h;
1117         int err, ret = -EINVAL;
1118
1119         h = kzalloc(sizeof(*h) , GFP_KERNEL);
1120         if (!h)
1121                 return -ENOMEM;
1122         spin_lock_init(&h->pg_lock);
1123         rcu_assign_pointer(h->pg, NULL);
1124         h->init_error = SCSI_DH_OK;
1125         h->sdev = sdev;
1126         INIT_LIST_HEAD(&h->node);
1127
1128         mutex_init(&h->init_mutex);
1129         err = alua_initialize(sdev, h);
1130         if (err == SCSI_DH_NOMEM)
1131                 ret = -ENOMEM;
1132         if (err != SCSI_DH_OK && err != SCSI_DH_DEV_OFFLINED)
1133                 goto failed;
1134
1135         sdev->handler_data = h;
1136         return 0;
1137 failed:
1138         kfree(h);
1139         return ret;
1140 }
1141
1142 /*
1143  * alua_bus_detach - Detach device handler
1144  * @sdev: device to be detached from
1145  */
1146 static void alua_bus_detach(struct scsi_device *sdev)
1147 {
1148         struct alua_dh_data *h = sdev->handler_data;
1149         struct alua_port_group *pg;
1150
1151         spin_lock(&h->pg_lock);
1152         pg = h->pg;
1153         rcu_assign_pointer(h->pg, NULL);
1154         spin_unlock(&h->pg_lock);
1155         if (pg) {
1156                 spin_lock_irq(&pg->lock);
1157                 list_del_rcu(&h->node);
1158                 spin_unlock_irq(&pg->lock);
1159                 kref_put(&pg->kref, release_port_group);
1160         }
1161         sdev->handler_data = NULL;
1162         synchronize_rcu();
1163         kfree(h);
1164 }
1165
1166 static struct scsi_device_handler alua_dh = {
1167         .name = ALUA_DH_NAME,
1168         .module = THIS_MODULE,
1169         .attach = alua_bus_attach,
1170         .detach = alua_bus_detach,
1171         .prep_fn = alua_prep_fn,
1172         .check_sense = alua_check_sense,
1173         .activate = alua_activate,
1174         .rescan = alua_rescan,
1175         .set_params = alua_set_params,
1176 };
1177
1178 static int __init alua_init(void)
1179 {
1180         int r;
1181
1182         kaluad_wq = alloc_workqueue("kaluad", WQ_MEM_RECLAIM, 0);
1183         if (!kaluad_wq) {
1184                 /* Temporary failure, bypass */
1185                 return SCSI_DH_DEV_TEMP_BUSY;
1186         }
1187         kaluad_sync_wq = create_workqueue("kaluad_sync");
1188         if (!kaluad_sync_wq) {
1189                 destroy_workqueue(kaluad_wq);
1190                 return SCSI_DH_DEV_TEMP_BUSY;
1191         }
1192         r = scsi_register_device_handler(&alua_dh);
1193         if (r != 0) {
1194                 printk(KERN_ERR "%s: Failed to register scsi device handler",
1195                         ALUA_DH_NAME);
1196                 destroy_workqueue(kaluad_sync_wq);
1197                 destroy_workqueue(kaluad_wq);
1198         }
1199         return r;
1200 }
1201
1202 static void __exit alua_exit(void)
1203 {
1204         scsi_unregister_device_handler(&alua_dh);
1205         destroy_workqueue(kaluad_sync_wq);
1206         destroy_workqueue(kaluad_wq);
1207 }
1208
1209 module_init(alua_init);
1210 module_exit(alua_exit);
1211
1212 MODULE_DESCRIPTION("DM Multipath ALUA support");
1213 MODULE_AUTHOR("Hannes Reinecke <hare@suse.de>");
1214 MODULE_LICENSE("GPL");
1215 MODULE_VERSION(ALUA_DH_VER);