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 #define TPGS_SUPPORT_ALL                0xdf
  44
  45 #define RTPG_FMT_MASK                   0x70
  46 #define RTPG_FMT_EXT_HDR                0x10
  47
  48 #define TPGS_MODE_UNINITIALIZED          -1
  49 #define TPGS_MODE_NONE                  0x0
  50 #define TPGS_MODE_IMPLICIT              0x1
  51 #define TPGS_MODE_EXPLICIT              0x2
  52
  53 #define ALUA_RTPG_SIZE                  128
  54 #define ALUA_FAILOVER_TIMEOUT           60
  55 #define ALUA_FAILOVER_RETRIES           5
  56 #define ALUA_RTPG_DELAY_MSECS           5
  57 #define ALUA_RTPG_RETRY_DELAY           2
  58
  59 /* device handler flags */
  60 #define ALUA_OPTIMIZE_STPG              0x01
  61 #define ALUA_RTPG_EXT_HDR_UNSUPP        0x02
  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
  75 struct alua_port_group {
  76         struct kref             kref;
  77         struct rcu_head         rcu;
  78         struct list_head        node;
  79         struct list_head        dh_list;
  80         unsigned char           device_id_str[256];
  81         int                     device_id_len;
  82         int                     group_id;
  83         int                     tpgs;
  84         int                     state;
  85         int                     pref;
  86         int                     valid_states;
  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 __rcu *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[MAX_COMMAND_SIZE];
 143         int req_flags = REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
 144                 REQ_FAILFAST_DRIVER;
 145
 146         /* Prepare the command. */
 147         memset(cdb, 0x0, MAX_COMMAND_SIZE);
 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(sdev, cdb, DMA_FROM_DEVICE, buff, bufflen, NULL,
 156                         sshdr, ALUA_FAILOVER_TIMEOUT * HZ,
 157                         ALUA_FAILOVER_RETRIES, req_flags, 0, NULL);
 158 }
 159
 160 /*
 161  * submit_stpg - Issue a SET TARGET PORT GROUP command
 162  *
 163  * Currently we're only setting the current target port group state
 164  * to 'active/optimized' and let the array firmware figure out
 165  * the states of the remaining groups.
 166  */
 167 static int submit_stpg(struct scsi_device *sdev, int group_id,
 168                        struct scsi_sense_hdr *sshdr)
 169 {
 170         u8 cdb[MAX_COMMAND_SIZE];
 171         unsigned char stpg_data[8];
 172         int stpg_len = 8;
 173         int req_flags = REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
 174                 REQ_FAILFAST_DRIVER;
 175
 176         /* Prepare the data buffer */
 177         memset(stpg_data, 0, stpg_len);
 178         stpg_data[4] = SCSI_ACCESS_STATE_OPTIMAL;
 179         put_unaligned_be16(group_id, &stpg_data[6]);
 180
 181         /* Prepare the command. */
 182         memset(cdb, 0x0, MAX_COMMAND_SIZE);
 183         cdb[0] = MAINTENANCE_OUT;
 184         cdb[1] = MO_SET_TARGET_PGS;
 185         put_unaligned_be32(stpg_len, &cdb[6]);
 186
 187         return scsi_execute(sdev, cdb, DMA_TO_DEVICE, stpg_data, stpg_len, NULL,
 188                         sshdr, ALUA_FAILOVER_TIMEOUT * HZ,
 189                         ALUA_FAILOVER_RETRIES, req_flags, 0, NULL);
 190 }
 191
 192 static struct alua_port_group *alua_find_get_pg(char *id_str, size_t id_size,
 193                                                 int group_id)
 194 {
 195         struct alua_port_group *pg;
 196
 197         if (!id_str || !id_size || !strlen(id_str))
 198                 return NULL;
 199
 200         list_for_each_entry(pg, &port_group_list, node) {
 201                 if (pg->group_id != group_id)
 202                         continue;
 203                 if (!pg->device_id_len || pg->device_id_len != id_size)
 204                         continue;
 205                 if (strncmp(pg->device_id_str, id_str, id_size))
 206                         continue;
 207                 if (!kref_get_unless_zero(&pg->kref))
 208                         continue;
 209                 return pg;
 210         }
 211
 212         return NULL;
 213 }
 214
 215 /*
 216  * alua_alloc_pg - Allocate a new port_group structure
 217  * @sdev: scsi device
 218  * @group_id: port group id
 219  * @tpgs: target port group settings
 220  *
 221  * Allocate a new port_group structure for a given
 222  * device.
 223  */
 224 static struct alua_port_group *alua_alloc_pg(struct scsi_device *sdev,
 225                                              int group_id, int tpgs)
 226 {
 227         struct alua_port_group *pg, *tmp_pg;
 228
 229         pg = kzalloc(sizeof(struct alua_port_group), GFP_KERNEL);
 230         if (!pg)
 231                 return ERR_PTR(-ENOMEM);
 232
 233         pg->device_id_len = scsi_vpd_lun_id(sdev, pg->device_id_str,
 234                                             sizeof(pg->device_id_str));
 235         if (pg->device_id_len <= 0) {
 236                 /*
 237                  * TPGS supported but no device identification found.
 238                  * Generate private device identification.
 239                  */
 240                 sdev_printk(KERN_INFO, sdev,
 241                             "%s: No device descriptors found\n",
 242                             ALUA_DH_NAME);
 243                 pg->device_id_str[0] = '\0';
 244                 pg->device_id_len = 0;
 245         }
 246         pg->group_id = group_id;
 247         pg->tpgs = tpgs;
 248         pg->state = SCSI_ACCESS_STATE_OPTIMAL;
 249         pg->valid_states = TPGS_SUPPORT_ALL;
 250         if (optimize_stpg)
 251                 pg->flags |= ALUA_OPTIMIZE_STPG;
 252         kref_init(&pg->kref);
 253         INIT_DELAYED_WORK(&pg->rtpg_work, alua_rtpg_work);
 254         INIT_LIST_HEAD(&pg->rtpg_list);
 255         INIT_LIST_HEAD(&pg->node);
 256         INIT_LIST_HEAD(&pg->dh_list);
 257         spin_lock_init(&pg->lock);
 258
 259         spin_lock(&port_group_lock);
 260         tmp_pg = alua_find_get_pg(pg->device_id_str, pg->device_id_len,
 261                                   group_id);
 262         if (tmp_pg) {
 263                 spin_unlock(&port_group_lock);
 264                 kfree(pg);
 265                 return tmp_pg;
 266         }
 267
 268         list_add(&pg->node, &port_group_list);
 269         spin_unlock(&port_group_lock);
 270
 271         return pg;
 272 }
 273
 274 /*
 275  * alua_check_tpgs - Evaluate TPGS setting
 276  * @sdev: device to be checked
 277  *
 278  * Examine the TPGS setting of the sdev to find out if ALUA
 279  * is supported.
 280  */
 281 static int alua_check_tpgs(struct scsi_device *sdev)
 282 {
 283         int tpgs = TPGS_MODE_NONE;
 284
 285         /*
 286          * ALUA support for non-disk devices is fraught with
 287          * difficulties, so disable it for now.
 288          */
 289         if (sdev->type != TYPE_DISK) {
 290                 sdev_printk(KERN_INFO, sdev,
 291                             "%s: disable for non-disk devices\n",
 292                             ALUA_DH_NAME);
 293                 return tpgs;
 294         }
 295
 296         tpgs = scsi_device_tpgs(sdev);
 297         switch (tpgs) {
 298         case TPGS_MODE_EXPLICIT|TPGS_MODE_IMPLICIT:
 299                 sdev_printk(KERN_INFO, sdev,
 300                             "%s: supports implicit and explicit TPGS\n",
 301                             ALUA_DH_NAME);
 302                 break;
 303         case TPGS_MODE_EXPLICIT:
 304                 sdev_printk(KERN_INFO, sdev, "%s: supports explicit TPGS\n",
 305                             ALUA_DH_NAME);
 306                 break;
 307         case TPGS_MODE_IMPLICIT:
 308                 sdev_printk(KERN_INFO, sdev, "%s: supports implicit TPGS\n",
 309                             ALUA_DH_NAME);
 310                 break;
 311         case TPGS_MODE_NONE:
 312                 sdev_printk(KERN_INFO, sdev, "%s: not supported\n",
 313                             ALUA_DH_NAME);
 314                 break;
 315         default:
 316                 sdev_printk(KERN_INFO, sdev,
 317                             "%s: unsupported TPGS setting %d\n",
 318                             ALUA_DH_NAME, tpgs);
 319                 tpgs = TPGS_MODE_NONE;
 320                 break;
 321         }
 322
 323         return tpgs;
 324 }
 325
 326 /*
 327  * alua_check_vpd - Evaluate INQUIRY vpd page 0x83
 328  * @sdev: device to be checked
 329  *
 330  * Extract the relative target port and the target port group
 331  * descriptor from the list of identificators.
 332  */
 333 static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h,
 334                           int tpgs)
 335 {
 336         int rel_port = -1, group_id;
 337         struct alua_port_group *pg, *old_pg = NULL;
 338         bool pg_updated = false;
 339         unsigned long flags;
 340
 341         group_id = scsi_vpd_tpg_id(sdev, &rel_port);
 342         if (group_id < 0) {
 343                 /*
 344                  * Internal error; TPGS supported but required
 345                  * VPD identification descriptors not present.
 346                  * Disable ALUA support
 347                  */
 348                 sdev_printk(KERN_INFO, sdev,
 349                             "%s: No target port descriptors found\n",
 350                             ALUA_DH_NAME);
 351                 return SCSI_DH_DEV_UNSUPP;
 352         }
 353
 354         pg = alua_alloc_pg(sdev, group_id, tpgs);
 355         if (IS_ERR(pg)) {
 356                 if (PTR_ERR(pg) == -ENOMEM)
 357                         return SCSI_DH_NOMEM;
 358                 return SCSI_DH_DEV_UNSUPP;
 359         }
 360         if (pg->device_id_len)
 361                 sdev_printk(KERN_INFO, sdev,
 362                             "%s: device %s port group %x rel port %x\n",
 363                             ALUA_DH_NAME, pg->device_id_str,
 364                             group_id, rel_port);
 365         else
 366                 sdev_printk(KERN_INFO, sdev,
 367                             "%s: port group %x rel port %x\n",
 368                             ALUA_DH_NAME, group_id, rel_port);
 369
 370         /* Check for existing port group references */
 371         spin_lock(&h->pg_lock);
 372         old_pg = rcu_dereference_protected(h->pg, lockdep_is_held(&h->pg_lock));
 373         if (old_pg != pg) {
 374                 /* port group has changed. Update to new port group */
 375                 if (h->pg) {
 376                         spin_lock_irqsave(&old_pg->lock, flags);
 377                         list_del_rcu(&h->node);
 378                         spin_unlock_irqrestore(&old_pg->lock, flags);
 379                 }
 380                 rcu_assign_pointer(h->pg, pg);
 381                 pg_updated = true;
 382         }
 383
 384         spin_lock_irqsave(&pg->lock, flags);
 385         if (pg_updated)
 386                 list_add_rcu(&h->node, &pg->dh_list);
 387         spin_unlock_irqrestore(&pg->lock, flags);
 388
 389         alua_rtpg_queue(rcu_dereference_protected(h->pg,
 390                                                   lockdep_is_held(&h->pg_lock)),
 391                         sdev, NULL, true);
 392         spin_unlock(&h->pg_lock);
 393
 394         if (old_pg)
 395                 kref_put(&old_pg->kref, release_port_group);
 396
 397         return SCSI_DH_OK;
 398 }
 399
 400 static char print_alua_state(unsigned char state)
 401 {
 402         switch (state) {
 403         case SCSI_ACCESS_STATE_OPTIMAL:
 404                 return 'A';
 405         case SCSI_ACCESS_STATE_ACTIVE:
 406                 return 'N';
 407         case SCSI_ACCESS_STATE_STANDBY:
 408                 return 'S';
 409         case SCSI_ACCESS_STATE_UNAVAILABLE:
 410                 return 'U';
 411         case SCSI_ACCESS_STATE_LBA:
 412                 return 'L';
 413         case SCSI_ACCESS_STATE_OFFLINE:
 414                 return 'O';
 415         case SCSI_ACCESS_STATE_TRANSITIONING:
 416                 return 'T';
 417         default:
 418                 return 'X';
 419         }
 420 }
 421
 422 static int alua_check_sense(struct scsi_device *sdev,
 423                             struct scsi_sense_hdr *sense_hdr)
 424 {
 425         switch (sense_hdr->sense_key) {
 426         case NOT_READY:
 427                 if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0a) {
 428                         /*
 429                          * LUN Not Accessible - ALUA state transition
 430                          */
 431                         alua_check(sdev, false);
 432                         return NEEDS_RETRY;
 433                 }
 434                 break;
 435         case UNIT_ATTENTION:
 436                 if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00) {
 437                         /*
 438                          * Power On, Reset, or Bus Device Reset.
 439                          * Might have obscured a state transition,
 440                          * so schedule a recheck.
 441                          */
 442                         alua_check(sdev, true);
 443                         return ADD_TO_MLQUEUE;
 444                 }
 445                 if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x04)
 446                         /*
 447                          * Device internal reset
 448                          */
 449                         return ADD_TO_MLQUEUE;
 450                 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x01)
 451                         /*
 452                          * Mode Parameters Changed
 453                          */
 454                         return ADD_TO_MLQUEUE;
 455                 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x06) {
 456                         /*
 457                          * ALUA state changed
 458                          */
 459                         alua_check(sdev, true);
 460                         return ADD_TO_MLQUEUE;
 461                 }
 462                 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x07) {
 463                         /*
 464                          * Implicit ALUA state transition failed
 465                          */
 466                         alua_check(sdev, true);
 467                         return ADD_TO_MLQUEUE;
 468                 }
 469                 if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x03)
 470                         /*
 471                          * Inquiry data has changed
 472                          */
 473                         return ADD_TO_MLQUEUE;
 474                 if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x0e)
 475                         /*
 476                          * REPORTED_LUNS_DATA_HAS_CHANGED is reported
 477                          * when switching controllers on targets like
 478                          * Intel Multi-Flex. We can just retry.
 479                          */
 480                         return ADD_TO_MLQUEUE;
 481                 break;
 482         }
 483
 484         return SCSI_RETURN_NOT_HANDLED;
 485 }
 486
 487 /*
 488  * alua_tur - Send a TEST UNIT READY
 489  * @sdev: device to which the TEST UNIT READY command should be send
 490  *
 491  * Send a TEST UNIT READY to @sdev to figure out the device state
 492  * Returns SCSI_DH_RETRY if the sense code is NOT READY/ALUA TRANSITIONING,
 493  * SCSI_DH_OK if no error occurred, and SCSI_DH_IO otherwise.
 494  */
 495 static int alua_tur(struct scsi_device *sdev)
 496 {
 497         struct scsi_sense_hdr sense_hdr;
 498         int retval;
 499
 500         retval = scsi_test_unit_ready(sdev, ALUA_FAILOVER_TIMEOUT * HZ,
 501                                       ALUA_FAILOVER_RETRIES, &sense_hdr);
 502         if (sense_hdr.sense_key == NOT_READY &&
 503             sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a)
 504                 return SCSI_DH_RETRY;
 505         else if (retval)
 506                 return SCSI_DH_IO;
 507         else
 508                 return SCSI_DH_OK;
 509 }
 510
 511 /*
 512  * alua_rtpg - Evaluate REPORT TARGET GROUP STATES
 513  * @sdev: the device to be evaluated.
 514  *
 515  * Evaluate the Target Port Group State.
 516  * Returns SCSI_DH_DEV_OFFLINED if the path is
 517  * found to be unusable.
 518  */
 519 static int alua_rtpg(struct scsi_device *sdev, struct alua_port_group *pg)
 520 {
 521         struct scsi_sense_hdr sense_hdr;
 522         struct alua_port_group *tmp_pg;
 523         int len, k, off, bufflen = ALUA_RTPG_SIZE;
 524         unsigned char *desc, *buff;
 525         unsigned err, retval;
 526         unsigned int tpg_desc_tbl_off;
 527         unsigned char orig_transition_tmo;
 528         unsigned long flags;
 529         bool transitioning_sense = false;
 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                  */
 583                 if (!(pg->flags & ALUA_RTPG_EXT_HDR_UNSUPP) &&
 584                     sense_hdr.sense_key == ILLEGAL_REQUEST &&
 585                     sense_hdr.asc == 0x24 && sense_hdr.ascq == 0) {
 586                         pg->flags |= ALUA_RTPG_EXT_HDR_UNSUPP;
 587                         goto retry;
 588                 }
 589                 /*
 590                  * If the array returns with 'ALUA state transition'
 591                  * sense code here it cannot return RTPG data during
 592                  * transition. So set the state to 'transitioning' directly.
 593                  */
 594                 if (sense_hdr.sense_key == NOT_READY &&
 595                     sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a) {
 596                         transitioning_sense = true;
 597                         goto skip_rtpg;
 598                 }
 599                 /*
 600                  * Retry on any other UNIT ATTENTION occurred.
 601                  */
 602                 if (sense_hdr.sense_key == UNIT_ATTENTION)
 603                         err = SCSI_DH_RETRY;
 604                 if (err == SCSI_DH_RETRY &&
 605                     pg->expiry != 0 && time_before(jiffies, pg->expiry)) {
 606                         sdev_printk(KERN_ERR, sdev, "%s: rtpg retry\n",
 607                                     ALUA_DH_NAME);
 608                         scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
 609                         kfree(buff);
 610                         return err;
 611                 }
 612                 sdev_printk(KERN_ERR, sdev, "%s: rtpg failed\n",
 613                             ALUA_DH_NAME);
 614                 scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
 615                 kfree(buff);
 616                 pg->expiry = 0;
 617                 return SCSI_DH_IO;
 618         }
 619
 620         len = get_unaligned_be32(&buff[0]) + 4;
 621
 622         if (len > bufflen) {
 623                 /* Resubmit with the correct length */
 624                 kfree(buff);
 625                 bufflen = len;
 626                 buff = kmalloc(bufflen, GFP_KERNEL);
 627                 if (!buff) {
 628                         sdev_printk(KERN_WARNING, sdev,
 629                                     "%s: kmalloc buffer failed\n",__func__);
 630                         /* Temporary failure, bypass */
 631                         pg->expiry = 0;
 632                         return SCSI_DH_DEV_TEMP_BUSY;
 633                 }
 634                 goto retry;
 635         }
 636
 637         orig_transition_tmo = pg->transition_tmo;
 638         if ((buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR && buff[5] != 0)
 639                 pg->transition_tmo = buff[5];
 640         else
 641                 pg->transition_tmo = ALUA_FAILOVER_TIMEOUT;
 642
 643         if (orig_transition_tmo != pg->transition_tmo) {
 644                 sdev_printk(KERN_INFO, sdev,
 645                             "%s: transition timeout set to %d seconds\n",
 646                             ALUA_DH_NAME, pg->transition_tmo);
 647                 pg->expiry = jiffies + pg->transition_tmo * HZ;
 648         }
 649
 650         if ((buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR)
 651                 tpg_desc_tbl_off = 8;
 652         else
 653                 tpg_desc_tbl_off = 4;
 654
 655         for (k = tpg_desc_tbl_off, desc = buff + tpg_desc_tbl_off;
 656              k < len;
 657              k += off, desc += off) {
 658                 u16 group_id = get_unaligned_be16(&desc[2]);
 659
 660                 spin_lock_irqsave(&port_group_lock, flags);
 661                 tmp_pg = alua_find_get_pg(pg->device_id_str, pg->device_id_len,
 662                                           group_id);
 663                 spin_unlock_irqrestore(&port_group_lock, flags);
 664                 if (tmp_pg) {
 665                         if (spin_trylock_irqsave(&tmp_pg->lock, flags)) {
 666                                 if ((tmp_pg == pg) ||
 667                                     !(tmp_pg->flags & ALUA_PG_RUNNING)) {
 668                                         struct alua_dh_data *h;
 669
 670                                         tmp_pg->state = desc[0] & 0x0f;
 671                                         tmp_pg->pref = desc[0] >> 7;
 672                                         rcu_read_lock();
 673                                         list_for_each_entry_rcu(h,
 674                                                 &tmp_pg->dh_list, node) {
 675                                                 /* h->sdev should always be valid */
 676                                                 BUG_ON(!h->sdev);
 677                                                 h->sdev->access_state = desc[0];
 678                                         }
 679                                         rcu_read_unlock();
 680                                 }
 681                                 if (tmp_pg == pg)
 682                                         tmp_pg->valid_states = desc[1];
 683                                 spin_unlock_irqrestore(&tmp_pg->lock, flags);
 684                         }
 685                         kref_put(&tmp_pg->kref, release_port_group);
 686                 }
 687                 off = 8 + (desc[7] * 4);
 688         }
 689
 690  skip_rtpg:
 691         spin_lock_irqsave(&pg->lock, flags);
 692         if (transitioning_sense)
 693                 pg->state = SCSI_ACCESS_STATE_TRANSITIONING;
 694
 695         sdev_printk(KERN_INFO, sdev,
 696                     "%s: port group %02x state %c %s supports %c%c%c%c%c%c%c\n",
 697                     ALUA_DH_NAME, pg->group_id, print_alua_state(pg->state),
 698                     pg->pref ? "preferred" : "non-preferred",
 699                     pg->valid_states&TPGS_SUPPORT_TRANSITION?'T':'t',
 700                     pg->valid_states&TPGS_SUPPORT_OFFLINE?'O':'o',
 701                     pg->valid_states&TPGS_SUPPORT_LBA_DEPENDENT?'L':'l',
 702                     pg->valid_states&TPGS_SUPPORT_UNAVAILABLE?'U':'u',
 703                     pg->valid_states&TPGS_SUPPORT_STANDBY?'S':'s',
 704                     pg->valid_states&TPGS_SUPPORT_NONOPTIMIZED?'N':'n',
 705                     pg->valid_states&TPGS_SUPPORT_OPTIMIZED?'A':'a');
 706
 707         switch (pg->state) {
 708         case SCSI_ACCESS_STATE_TRANSITIONING:
 709                 if (time_before(jiffies, pg->expiry)) {
 710                         /* State transition, retry */
 711                         pg->interval = ALUA_RTPG_RETRY_DELAY;
 712                         err = SCSI_DH_RETRY;
 713                 } else {
 714                         struct alua_dh_data *h;
 715
 716                         /* Transitioning time exceeded, set port to standby */
 717                         err = SCSI_DH_IO;
 718                         pg->state = SCSI_ACCESS_STATE_STANDBY;
 719                         pg->expiry = 0;
 720                         rcu_read_lock();
 721                         list_for_each_entry_rcu(h, &pg->dh_list, node) {
 722                                 BUG_ON(!h->sdev);
 723                                 h->sdev->access_state =
 724                                         (pg->state & SCSI_ACCESS_STATE_MASK);
 725                                 if (pg->pref)
 726                                         h->sdev->access_state |=
 727                                                 SCSI_ACCESS_STATE_PREFERRED;
 728                         }
 729                         rcu_read_unlock();
 730                 }
 731                 break;
 732         case SCSI_ACCESS_STATE_OFFLINE:
 733                 /* Path unusable */
 734                 err = SCSI_DH_DEV_OFFLINED;
 735                 pg->expiry = 0;
 736                 break;
 737         default:
 738                 /* Useable path if active */
 739                 err = SCSI_DH_OK;
 740                 pg->expiry = 0;
 741                 break;
 742         }
 743         spin_unlock_irqrestore(&pg->lock, flags);
 744         kfree(buff);
 745         return err;
 746 }
 747
 748 /*
 749  * alua_stpg - Issue a SET TARGET PORT GROUP command
 750  *
 751  * Issue a SET TARGET PORT GROUP command and evaluate the
 752  * response. Returns SCSI_DH_RETRY per default to trigger
 753  * a re-evaluation of the target group state or SCSI_DH_OK
 754  * if no further action needs to be taken.
 755  */
 756 static unsigned alua_stpg(struct scsi_device *sdev, struct alua_port_group *pg)
 757 {
 758         int retval;
 759         struct scsi_sense_hdr sense_hdr;
 760
 761         if (!(pg->tpgs & TPGS_MODE_EXPLICIT)) {
 762                 /* Only implicit ALUA supported, retry */
 763                 return SCSI_DH_RETRY;
 764         }
 765         switch (pg->state) {
 766         case SCSI_ACCESS_STATE_OPTIMAL:
 767                 return SCSI_DH_OK;
 768         case SCSI_ACCESS_STATE_ACTIVE:
 769                 if ((pg->flags & ALUA_OPTIMIZE_STPG) &&
 770                     !pg->pref &&
 771                     (pg->tpgs & TPGS_MODE_IMPLICIT))
 772                         return SCSI_DH_OK;
 773                 break;
 774         case SCSI_ACCESS_STATE_STANDBY:
 775         case SCSI_ACCESS_STATE_UNAVAILABLE:
 776                 break;
 777         case SCSI_ACCESS_STATE_OFFLINE:
 778                 return SCSI_DH_IO;
 779         case SCSI_ACCESS_STATE_TRANSITIONING:
 780                 break;
 781         default:
 782                 sdev_printk(KERN_INFO, sdev,
 783                             "%s: stpg failed, unhandled TPGS state %d",
 784                             ALUA_DH_NAME, pg->state);
 785                 return SCSI_DH_NOSYS;
 786         }
 787         retval = submit_stpg(sdev, pg->group_id, &sense_hdr);
 788
 789         if (retval) {
 790                 if (!scsi_sense_valid(&sense_hdr)) {
 791                         sdev_printk(KERN_INFO, sdev,
 792                                     "%s: stpg failed, result %d",
 793                                     ALUA_DH_NAME, retval);
 794                         if (driver_byte(retval) == DRIVER_ERROR)
 795                                 return SCSI_DH_DEV_TEMP_BUSY;
 796                 } else {
 797                         sdev_printk(KERN_INFO, sdev, "%s: stpg failed\n",
 798                                     ALUA_DH_NAME);
 799                         scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
 800                 }
 801         }
 802         /* Retry RTPG */
 803         return SCSI_DH_RETRY;
 804 }
 805
 806 static void alua_rtpg_work(struct work_struct *work)
 807 {
 808         struct alua_port_group *pg =
 809                 container_of(work, struct alua_port_group, rtpg_work.work);
 810         struct scsi_device *sdev;
 811         LIST_HEAD(qdata_list);
 812         int err = SCSI_DH_OK;
 813         struct alua_queue_data *qdata, *tmp;
 814         unsigned long flags;
 815
 816         spin_lock_irqsave(&pg->lock, flags);
 817         sdev = pg->rtpg_sdev;
 818         if (!sdev) {
 819                 WARN_ON(pg->flags & ALUA_PG_RUN_RTPG);
 820                 WARN_ON(pg->flags & ALUA_PG_RUN_STPG);
 821                 spin_unlock_irqrestore(&pg->lock, flags);
 822                 kref_put(&pg->kref, release_port_group);
 823                 return;
 824         }
 825         pg->flags |= ALUA_PG_RUNNING;
 826         if (pg->flags & ALUA_PG_RUN_RTPG) {
 827                 int state = pg->state;
 828
 829                 pg->flags &= ~ALUA_PG_RUN_RTPG;
 830                 spin_unlock_irqrestore(&pg->lock, flags);
 831                 if (state == SCSI_ACCESS_STATE_TRANSITIONING) {
 832                         if (alua_tur(sdev) == SCSI_DH_RETRY) {
 833                                 spin_lock_irqsave(&pg->lock, flags);
 834                                 pg->flags &= ~ALUA_PG_RUNNING;
 835                                 pg->flags |= ALUA_PG_RUN_RTPG;
 836                                 if (!pg->interval)
 837                                         pg->interval = ALUA_RTPG_RETRY_DELAY;
 838                                 spin_unlock_irqrestore(&pg->lock, flags);
 839                                 queue_delayed_work(kaluad_wq, &pg->rtpg_work,
 840                                                    pg->interval * HZ);
 841                                 return;
 842                         }
 843                         /* Send RTPG on failure or if TUR indicates SUCCESS */
 844                 }
 845                 err = alua_rtpg(sdev, pg);
 846                 spin_lock_irqsave(&pg->lock, flags);
 847                 if (err == SCSI_DH_RETRY || pg->flags & ALUA_PG_RUN_RTPG) {
 848                         pg->flags &= ~ALUA_PG_RUNNING;
 849                         if (!pg->interval && !(pg->flags & ALUA_PG_RUN_RTPG))
 850                                 pg->interval = ALUA_RTPG_RETRY_DELAY;
 851                         pg->flags |= ALUA_PG_RUN_RTPG;
 852                         spin_unlock_irqrestore(&pg->lock, flags);
 853                         queue_delayed_work(kaluad_wq, &pg->rtpg_work,
 854                                            pg->interval * HZ);
 855                         return;
 856                 }
 857                 if (err != SCSI_DH_OK)
 858                         pg->flags &= ~ALUA_PG_RUN_STPG;
 859         }
 860         if (pg->flags & ALUA_PG_RUN_STPG) {
 861                 pg->flags &= ~ALUA_PG_RUN_STPG;
 862                 spin_unlock_irqrestore(&pg->lock, flags);
 863                 err = alua_stpg(sdev, pg);
 864                 spin_lock_irqsave(&pg->lock, flags);
 865                 if (err == SCSI_DH_RETRY || pg->flags & ALUA_PG_RUN_RTPG) {
 866                         pg->flags |= ALUA_PG_RUN_RTPG;
 867                         pg->interval = 0;
 868                         pg->flags &= ~ALUA_PG_RUNNING;
 869                         spin_unlock_irqrestore(&pg->lock, flags);
 870                         queue_delayed_work(kaluad_wq, &pg->rtpg_work,
 871                                            pg->interval * HZ);
 872                         return;
 873                 }
 874         }
 875
 876         list_splice_init(&pg->rtpg_list, &qdata_list);
 877         pg->rtpg_sdev = NULL;
 878         spin_unlock_irqrestore(&pg->lock, flags);
 879
 880         list_for_each_entry_safe(qdata, tmp, &qdata_list, entry) {
 881                 list_del(&qdata->entry);
 882                 if (qdata->callback_fn)
 883                         qdata->callback_fn(qdata->callback_data, err);
 884                 kfree(qdata);
 885         }
 886         spin_lock_irqsave(&pg->lock, flags);
 887         pg->flags &= ~ALUA_PG_RUNNING;
 888         spin_unlock_irqrestore(&pg->lock, flags);
 889         scsi_device_put(sdev);
 890         kref_put(&pg->kref, release_port_group);
 891 }
 892
 893 /**
 894  * alua_rtpg_queue() - cause RTPG to be submitted asynchronously
 895  * @pg: ALUA port group associated with @sdev.
 896  * @sdev: SCSI device for which to submit an RTPG.
 897  * @qdata: Information about the callback to invoke after the RTPG.
 898  * @force: Whether or not to submit an RTPG if a work item that will submit an
 899  *         RTPG already has been scheduled.
 900  *
 901  * Returns true if and only if alua_rtpg_work() will be called asynchronously.
 902  * That function is responsible for calling @qdata->fn().
 903  */
 904 static bool alua_rtpg_queue(struct alua_port_group *pg,
 905                             struct scsi_device *sdev,
 906                             struct alua_queue_data *qdata, bool force)
 907 {
 908         int start_queue = 0;
 909         unsigned long flags;
 910         if (WARN_ON_ONCE(!pg) || scsi_device_get(sdev))
 911                 return false;
 912
 913         spin_lock_irqsave(&pg->lock, flags);
 914         if (qdata) {
 915                 list_add_tail(&qdata->entry, &pg->rtpg_list);
 916                 pg->flags |= ALUA_PG_RUN_STPG;
 917                 force = true;
 918         }
 919         if (pg->rtpg_sdev == NULL) {
 920                 pg->interval = 0;
 921                 pg->flags |= ALUA_PG_RUN_RTPG;
 922                 kref_get(&pg->kref);
 923                 pg->rtpg_sdev = sdev;
 924                 start_queue = 1;
 925         } else if (!(pg->flags & ALUA_PG_RUN_RTPG) && force) {
 926                 pg->flags |= ALUA_PG_RUN_RTPG;
 927                 /* Do not queue if the worker is already running */
 928                 if (!(pg->flags & ALUA_PG_RUNNING)) {
 929                         kref_get(&pg->kref);
 930                         start_queue = 1;
 931                 }
 932         }
 933
 934         spin_unlock_irqrestore(&pg->lock, flags);
 935
 936         if (start_queue) {
 937                 if (queue_delayed_work(kaluad_wq, &pg->rtpg_work,
 938                                 msecs_to_jiffies(ALUA_RTPG_DELAY_MSECS)))
 939                         sdev = NULL;
 940                 else
 941                         kref_put(&pg->kref, release_port_group);
 942         }
 943         if (sdev)
 944                 scsi_device_put(sdev);
 945
 946         return true;
 947 }
 948
 949 /*
 950  * alua_initialize - Initialize ALUA state
 951  * @sdev: the device to be initialized
 952  *
 953  * For the prep_fn to work correctly we have
 954  * to initialize the ALUA state for the device.
 955  */
 956 static int alua_initialize(struct scsi_device *sdev, struct alua_dh_data *h)
 957 {
 958         int err = SCSI_DH_DEV_UNSUPP, tpgs;
 959
 960         mutex_lock(&h->init_mutex);
 961         tpgs = alua_check_tpgs(sdev);
 962         if (tpgs != TPGS_MODE_NONE)
 963                 err = alua_check_vpd(sdev, h, tpgs);
 964         h->init_error = err;
 965         mutex_unlock(&h->init_mutex);
 966         return err;
 967 }
 968 /*
 969  * alua_set_params - set/unset the optimize flag
 970  * @sdev: device on the path to be activated
 971  * params - parameters in the following format
 972  *      "no_of_params\0param1\0param2\0param3\0...\0"
 973  * For example, to set the flag pass the following parameters
 974  * from multipath.conf
 975  *     hardware_handler        "2 alua 1"
 976  */
 977 static int alua_set_params(struct scsi_device *sdev, const char *params)
 978 {
 979         struct alua_dh_data *h = sdev->handler_data;
 980         struct alua_port_group *pg = NULL;
 981         unsigned int optimize = 0, argc;
 982         const char *p = params;
 983         int result = SCSI_DH_OK;
 984         unsigned long flags;
 985
 986         if ((sscanf(params, "%u", &argc) != 1) || (argc != 1))
 987                 return -EINVAL;
 988
 989         while (*p++)
 990                 ;
 991         if ((sscanf(p, "%u", &optimize) != 1) || (optimize > 1))
 992                 return -EINVAL;
 993
 994         rcu_read_lock();
 995         pg = rcu_dereference(h->pg);
 996         if (!pg) {
 997                 rcu_read_unlock();
 998                 return -ENXIO;
 999         }
1000         spin_lock_irqsave(&pg->lock, flags);
1001         if (optimize)
1002                 pg->flags |= ALUA_OPTIMIZE_STPG;
1003         else
1004                 pg->flags &= ~ALUA_OPTIMIZE_STPG;
1005         spin_unlock_irqrestore(&pg->lock, flags);
1006         rcu_read_unlock();
1007
1008         return result;
1009 }
1010
1011 /*
1012  * alua_activate - activate a path
1013  * @sdev: device on the path to be activated
1014  *
1015  * We're currently switching the port group to be activated only and
1016  * let the array figure out the rest.
1017  * There may be other arrays which require us to switch all port groups
1018  * based on a certain policy. But until we actually encounter them it
1019  * should be okay.
1020  */
1021 static int alua_activate(struct scsi_device *sdev,
1022                         activate_complete fn, void *data)
1023 {
1024         struct alua_dh_data *h = sdev->handler_data;
1025         int err = SCSI_DH_OK;
1026         struct alua_queue_data *qdata;
1027         struct alua_port_group *pg;
1028
1029         qdata = kzalloc(sizeof(*qdata), GFP_KERNEL);
1030         if (!qdata) {
1031                 err = SCSI_DH_RES_TEMP_UNAVAIL;
1032                 goto out;
1033         }
1034         qdata->callback_fn = fn;
1035         qdata->callback_data = data;
1036
1037         mutex_lock(&h->init_mutex);
1038         rcu_read_lock();
1039         pg = rcu_dereference(h->pg);
1040         if (!pg || !kref_get_unless_zero(&pg->kref)) {
1041                 rcu_read_unlock();
1042                 kfree(qdata);
1043                 err = h->init_error;
1044                 mutex_unlock(&h->init_mutex);
1045                 goto out;
1046         }
1047         rcu_read_unlock();
1048         mutex_unlock(&h->init_mutex);
1049
1050         if (alua_rtpg_queue(pg, sdev, qdata, true))
1051                 fn = NULL;
1052         else
1053                 err = SCSI_DH_DEV_OFFLINED;
1054         kref_put(&pg->kref, release_port_group);
1055 out:
1056         if (fn)
1057                 fn(data, err);
1058         return 0;
1059 }
1060
1061 /*
1062  * alua_check - check path status
1063  * @sdev: device on the path to be checked
1064  *
1065  * Check the device status
1066  */
1067 static void alua_check(struct scsi_device *sdev, bool force)
1068 {
1069         struct alua_dh_data *h = sdev->handler_data;
1070         struct alua_port_group *pg;
1071
1072         rcu_read_lock();
1073         pg = rcu_dereference(h->pg);
1074         if (!pg || !kref_get_unless_zero(&pg->kref)) {
1075                 rcu_read_unlock();
1076                 return;
1077         }
1078         rcu_read_unlock();
1079
1080         alua_rtpg_queue(pg, sdev, NULL, force);
1081         kref_put(&pg->kref, release_port_group);
1082 }
1083
1084 /*
1085  * alua_prep_fn - request callback
1086  *
1087  * Fail I/O to all paths not in state
1088  * active/optimized or active/non-optimized.
1089  */
1090 static int alua_prep_fn(struct scsi_device *sdev, struct request *req)
1091 {
1092         struct alua_dh_data *h = sdev->handler_data;
1093         struct alua_port_group *pg;
1094         unsigned char state = SCSI_ACCESS_STATE_OPTIMAL;
1095         int ret = BLKPREP_OK;
1096
1097         rcu_read_lock();
1098         pg = rcu_dereference(h->pg);
1099         if (pg)
1100                 state = pg->state;
1101         rcu_read_unlock();
1102         if (state == SCSI_ACCESS_STATE_TRANSITIONING)
1103                 ret = BLKPREP_DEFER;
1104         else if (state != SCSI_ACCESS_STATE_OPTIMAL &&
1105                  state != SCSI_ACCESS_STATE_ACTIVE &&
1106                  state != SCSI_ACCESS_STATE_LBA) {
1107                 ret = BLKPREP_KILL;
1108                 req->rq_flags |= RQF_QUIET;
1109         }
1110         return ret;
1111
1112 }
1113
1114 static void alua_rescan(struct scsi_device *sdev)
1115 {
1116         struct alua_dh_data *h = sdev->handler_data;
1117
1118         alua_initialize(sdev, h);
1119 }
1120
1121 /*
1122  * alua_bus_attach - Attach device handler
1123  * @sdev: device to be attached to
1124  */
1125 static int alua_bus_attach(struct scsi_device *sdev)
1126 {
1127         struct alua_dh_data *h;
1128         int err;
1129
1130         h = kzalloc(sizeof(*h) , GFP_KERNEL);
1131         if (!h)
1132                 return SCSI_DH_NOMEM;
1133         spin_lock_init(&h->pg_lock);
1134         rcu_assign_pointer(h->pg, NULL);
1135         h->init_error = SCSI_DH_OK;
1136         h->sdev = sdev;
1137         INIT_LIST_HEAD(&h->node);
1138
1139         mutex_init(&h->init_mutex);
1140         err = alua_initialize(sdev, h);
1141         if (err != SCSI_DH_OK && err != SCSI_DH_DEV_OFFLINED)
1142                 goto failed;
1143
1144         sdev->handler_data = h;
1145         return SCSI_DH_OK;
1146 failed:
1147         kfree(h);
1148         return err;
1149 }
1150
1151 /*
1152  * alua_bus_detach - Detach device handler
1153  * @sdev: device to be detached from
1154  */
1155 static void alua_bus_detach(struct scsi_device *sdev)
1156 {
1157         struct alua_dh_data *h = sdev->handler_data;
1158         struct alua_port_group *pg;
1159
1160         spin_lock(&h->pg_lock);
1161         pg = rcu_dereference_protected(h->pg, lockdep_is_held(&h->pg_lock));
1162         rcu_assign_pointer(h->pg, NULL);
1163         h->sdev = NULL;
1164         spin_unlock(&h->pg_lock);
1165         if (pg) {
1166                 spin_lock_irq(&pg->lock);
1167                 list_del_rcu(&h->node);
1168                 spin_unlock_irq(&pg->lock);
1169                 kref_put(&pg->kref, release_port_group);
1170         }
1171         sdev->handler_data = NULL;
1172         kfree(h);
1173 }
1174
1175 static struct scsi_device_handler alua_dh = {
1176         .name = ALUA_DH_NAME,
1177         .module = THIS_MODULE,
1178         .attach = alua_bus_attach,
1179         .detach = alua_bus_detach,
1180         .prep_fn = alua_prep_fn,
1181         .check_sense = alua_check_sense,
1182         .activate = alua_activate,
1183         .rescan = alua_rescan,
1184         .set_params = alua_set_params,
1185 };
1186
1187 static int __init alua_init(void)
1188 {
1189         int r;
1190
1191         kaluad_wq = alloc_workqueue("kaluad", WQ_MEM_RECLAIM, 0);
1192         if (!kaluad_wq)
1193                 return -ENOMEM;
1194
1195         r = scsi_register_device_handler(&alua_dh);
1196         if (r != 0) {
1197                 printk(KERN_ERR "%s: Failed to register scsi device handler",
1198                         ALUA_DH_NAME);
1199                 destroy_workqueue(kaluad_wq);
1200         }
1201         return r;
1202 }
1203
1204 static void __exit alua_exit(void)
1205 {
1206         scsi_unregister_device_handler(&alua_dh);
1207         destroy_workqueue(kaluad_wq);
1208 }
1209
1210 module_init(alua_init);
1211 module_exit(alua_exit);
1212
1213 MODULE_DESCRIPTION("DM Multipath ALUA support");
1214 MODULE_AUTHOR("Hannes Reinecke <hare@suse.de>");
1215 MODULE_LICENSE("GPL");
1216 MODULE_VERSION(ALUA_DH_VER);