1// SPDX-License-Identifier: GPL-2.0-or-later 2/* 3 * Generic SCSI-3 ALUA SCSI Device Handler 4 * 5 * Copyright (C) 2007-2010 Hannes Reinecke, SUSE Linux Products GmbH. 6 * All rights reserved. 7 */ 8#include <linux/slab.h> 9#include <linux/delay.h> 10#include <linux/module.h> 11#include <asm/unaligned.h> 12#include <scsi/scsi.h> 13#include <scsi/scsi_proto.h> 14#include <scsi/scsi_dbg.h> 15#include <scsi/scsi_eh.h> 16#include <scsi/scsi_dh.h> 17 18#define ALUA_DH_NAME "alua" 19#define ALUA_DH_VER "2.0" 20 21#define TPGS_SUPPORT_NONE 0x00 22#define TPGS_SUPPORT_OPTIMIZED 0x01 23#define TPGS_SUPPORT_NONOPTIMIZED 0x02 24#define TPGS_SUPPORT_STANDBY 0x04 25#define TPGS_SUPPORT_UNAVAILABLE 0x08 26#define TPGS_SUPPORT_LBA_DEPENDENT 0x10 27#define TPGS_SUPPORT_OFFLINE 0x40 28#define TPGS_SUPPORT_TRANSITION 0x80 29#define TPGS_SUPPORT_ALL 0xdf 30 31#define RTPG_FMT_MASK 0x70 32#define RTPG_FMT_EXT_HDR 0x10 33 34#define TPGS_MODE_UNINITIALIZED -1 35#define TPGS_MODE_NONE 0x0 36#define TPGS_MODE_IMPLICIT 0x1 37#define TPGS_MODE_EXPLICIT 0x2 38 39#define ALUA_RTPG_SIZE 128 40#define ALUA_FAILOVER_TIMEOUT 60 41#define ALUA_FAILOVER_RETRIES 5 42#define ALUA_RTPG_DELAY_MSECS 5 43#define ALUA_RTPG_RETRY_DELAY 2 44 45/* device handler flags */ 46#define ALUA_OPTIMIZE_STPG 0x01 47#define ALUA_RTPG_EXT_HDR_UNSUPP 0x02 48/* State machine flags */ 49#define ALUA_PG_RUN_RTPG 0x10 50#define ALUA_PG_RUN_STPG 0x20 51#define ALUA_PG_RUNNING 0x40 52 53static uint optimize_stpg; 54module_param(optimize_stpg, uint, S_IRUGO|S_IWUSR); 55MODULE_PARM_DESC(optimize_stpg, "Allow use of a non-optimized path, rather than sending a STPG, when implicit TPGS is supported (0=No,1=Yes). Default is 0."); 56 57static LIST_HEAD(port_group_list); 58static DEFINE_SPINLOCK(port_group_lock); 59static struct workqueue_struct *kaluad_wq; 60 61struct alua_port_group { 62 struct kref kref; 63 struct rcu_head rcu; 64 struct list_head node; 65 struct list_head dh_list; 66 unsigned char device_id_str[256]; 67 int device_id_len; 68 int group_id; 69 int tpgs; 70 int state; 71 int pref; 72 int valid_states; 73 unsigned flags; /* used for optimizing STPG */ 74 unsigned char transition_tmo; 75 unsigned long expiry; 76 unsigned long interval; 77 struct delayed_work rtpg_work; 78 spinlock_t lock; 79 struct list_head rtpg_list; 80 struct scsi_device *rtpg_sdev; 81}; 82 83struct alua_dh_data { 84 struct list_head node; 85 struct alua_port_group __rcu *pg; 86 int group_id; 87 spinlock_t pg_lock; 88 struct scsi_device *sdev; 89 int init_error; 90 struct mutex init_mutex; 91 bool disabled; 92}; 93 94struct alua_queue_data { 95 struct list_head entry; 96 activate_complete callback_fn; 97 void *callback_data; 98}; 99 100#define ALUA_POLICY_SWITCH_CURRENT 0 101#define ALUA_POLICY_SWITCH_ALL 1 102 103static void alua_rtpg_work(struct work_struct *work); 104static bool alua_rtpg_queue(struct alua_port_group *pg, 105 struct scsi_device *sdev, 106 struct alua_queue_data *qdata, bool force); 107static void alua_check(struct scsi_device *sdev, bool force); 108 109static void release_port_group(struct kref *kref) 110{ 111 struct alua_port_group *pg; 112 113 pg = container_of(kref, struct alua_port_group, kref); 114 if (pg->rtpg_sdev) 115 flush_delayed_work(&pg->rtpg_work); 116 spin_lock(&port_group_lock); 117 list_del(&pg->node); 118 spin_unlock(&port_group_lock); 119 kfree_rcu(pg, rcu); 120} 121 122/* 123 * submit_rtpg - Issue a REPORT TARGET GROUP STATES command 124 * @sdev: sdev the command should be sent to 125 */ 126static int submit_rtpg(struct scsi_device *sdev, unsigned char *buff, 127 int bufflen, struct scsi_sense_hdr *sshdr, int flags) 128{ 129 u8 cdb[MAX_COMMAND_SIZE]; 130 blk_opf_t opf = REQ_OP_DRV_IN | REQ_FAILFAST_DEV | 131 REQ_FAILFAST_TRANSPORT | REQ_FAILFAST_DRIVER; 132 const struct scsi_exec_args exec_args = { 133 .sshdr = sshdr, 134 }; 135 136 /* Prepare the command. */ 137 memset(cdb, 0x0, MAX_COMMAND_SIZE); 138 cdb[0] = MAINTENANCE_IN; 139 if (!(flags & ALUA_RTPG_EXT_HDR_UNSUPP)) 140 cdb[1] = MI_REPORT_TARGET_PGS | MI_EXT_HDR_PARAM_FMT; 141 else 142 cdb[1] = MI_REPORT_TARGET_PGS; 143 put_unaligned_be32(bufflen, &cdb[6]); 144 145 return scsi_execute_cmd(sdev, cdb, opf, buff, bufflen, 146 ALUA_FAILOVER_TIMEOUT * HZ, 147 ALUA_FAILOVER_RETRIES, &exec_args); 148} 149 150/* 151 * submit_stpg - Issue a SET TARGET PORT GROUP command 152 * 153 * Currently we're only setting the current target port group state 154 * to 'active/optimized' and let the array firmware figure out 155 * the states of the remaining groups. 156 */ 157static int submit_stpg(struct scsi_device *sdev, int group_id, 158 struct scsi_sense_hdr *sshdr) 159{ 160 u8 cdb[MAX_COMMAND_SIZE]; 161 unsigned char stpg_data[8]; 162 int stpg_len = 8; 163 blk_opf_t opf = REQ_OP_DRV_OUT | REQ_FAILFAST_DEV | 164 REQ_FAILFAST_TRANSPORT | REQ_FAILFAST_DRIVER; 165 const struct scsi_exec_args exec_args = { 166 .sshdr = sshdr, 167 }; 168 169 /* Prepare the data buffer */ 170 memset(stpg_data, 0, stpg_len); 171 stpg_data[4] = SCSI_ACCESS_STATE_OPTIMAL; 172 put_unaligned_be16(group_id, &stpg_data[6]); 173 174 /* Prepare the command. */ 175 memset(cdb, 0x0, MAX_COMMAND_SIZE); 176 cdb[0] = MAINTENANCE_OUT; 177 cdb[1] = MO_SET_TARGET_PGS; 178 put_unaligned_be32(stpg_len, &cdb[6]); 179 180 return scsi_execute_cmd(sdev, cdb, opf, stpg_data, 181 stpg_len, ALUA_FAILOVER_TIMEOUT * HZ, 182 ALUA_FAILOVER_RETRIES, &exec_args); 183} 184 185static struct alua_port_group *alua_find_get_pg(char *id_str, size_t id_size, 186 int group_id) 187{ 188 struct alua_port_group *pg; 189 190 if (!id_str || !id_size || !strlen(id_str)) 191 return NULL; 192 193 list_for_each_entry(pg, &port_group_list, node) { 194 if (pg->group_id != group_id) 195 continue; 196 if (!pg->device_id_len || pg->device_id_len != id_size) 197 continue; 198 if (strncmp(pg->device_id_str, id_str, id_size)) 199 continue; 200 if (!kref_get_unless_zero(&pg->kref)) 201 continue; 202 return pg; 203 } 204 205 return NULL; 206} 207 208/* 209 * alua_alloc_pg - Allocate a new port_group structure 210 * @sdev: scsi device 211 * @group_id: port group id 212 * @tpgs: target port group settings 213 * 214 * Allocate a new port_group structure for a given 215 * device. 216 */ 217static struct alua_port_group *alua_alloc_pg(struct scsi_device *sdev, 218 int group_id, int tpgs) 219{ 220 struct alua_port_group *pg, *tmp_pg; 221 222 pg = kzalloc(sizeof(struct alua_port_group), GFP_KERNEL); 223 if (!pg) 224 return ERR_PTR(-ENOMEM); 225 226 pg->device_id_len = scsi_vpd_lun_id(sdev, pg->device_id_str, 227 sizeof(pg->device_id_str)); 228 if (pg->device_id_len <= 0) { 229 /* 230 * TPGS supported but no device identification found. 231 * Generate private device identification. 232 */ 233 sdev_printk(KERN_INFO, sdev, 234 "%s: No device descriptors found\n", 235 ALUA_DH_NAME); 236 pg->device_id_str[0] = '\0'; 237 pg->device_id_len = 0; 238 } 239 pg->group_id = group_id; 240 pg->tpgs = tpgs; 241 pg->state = SCSI_ACCESS_STATE_OPTIMAL; 242 pg->valid_states = TPGS_SUPPORT_ALL; 243 if (optimize_stpg) 244 pg->flags |= ALUA_OPTIMIZE_STPG; 245 kref_init(&pg->kref); 246 INIT_DELAYED_WORK(&pg->rtpg_work, alua_rtpg_work); 247 INIT_LIST_HEAD(&pg->rtpg_list); 248 INIT_LIST_HEAD(&pg->node); 249 INIT_LIST_HEAD(&pg->dh_list); 250 spin_lock_init(&pg->lock); 251 252 spin_lock(&port_group_lock); 253 tmp_pg = alua_find_get_pg(pg->device_id_str, pg->device_id_len, 254 group_id); 255 if (tmp_pg) { 256 spin_unlock(&port_group_lock); 257 kfree(pg); 258 return tmp_pg; 259 } 260 261 list_add(&pg->node, &port_group_list); 262 spin_unlock(&port_group_lock); 263 264 return pg; 265} 266 267/* 268 * alua_check_tpgs - Evaluate TPGS setting 269 * @sdev: device to be checked 270 * 271 * Examine the TPGS setting of the sdev to find out if ALUA 272 * is supported. 273 */ 274static int alua_check_tpgs(struct scsi_device *sdev) 275{ 276 int tpgs = TPGS_MODE_NONE; 277 278 /* 279 * ALUA support for non-disk devices is fraught with 280 * difficulties, so disable it for now. 281 */ 282 if (sdev->type != TYPE_DISK) { 283 sdev_printk(KERN_INFO, sdev, 284 "%s: disable for non-disk devices\n", 285 ALUA_DH_NAME); 286 return tpgs; 287 } 288 289 tpgs = scsi_device_tpgs(sdev); 290 switch (tpgs) { 291 case TPGS_MODE_EXPLICIT|TPGS_MODE_IMPLICIT: 292 sdev_printk(KERN_INFO, sdev, 293 "%s: supports implicit and explicit TPGS\n", 294 ALUA_DH_NAME); 295 break; 296 case TPGS_MODE_EXPLICIT: 297 sdev_printk(KERN_INFO, sdev, "%s: supports explicit TPGS\n", 298 ALUA_DH_NAME); 299 break; 300 case TPGS_MODE_IMPLICIT: 301 sdev_printk(KERN_INFO, sdev, "%s: supports implicit TPGS\n", 302 ALUA_DH_NAME); 303 break; 304 case TPGS_MODE_NONE: 305 sdev_printk(KERN_INFO, sdev, "%s: not supported\n", 306 ALUA_DH_NAME); 307 break; 308 default: 309 sdev_printk(KERN_INFO, sdev, 310 "%s: unsupported TPGS setting %d\n", 311 ALUA_DH_NAME, tpgs); 312 tpgs = TPGS_MODE_NONE; 313 break; 314 } 315 316 return tpgs; 317} 318 319/* 320 * alua_check_vpd - Evaluate INQUIRY vpd page 0x83 321 * @sdev: device to be checked 322 * 323 * Extract the relative target port and the target port group 324 * descriptor from the list of identificators. 325 */ 326static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h, 327 int tpgs) 328{ 329 int rel_port = -1, group_id; 330 struct alua_port_group *pg, *old_pg = NULL; 331 bool pg_updated = false; 332 unsigned long flags; 333 334 group_id = scsi_vpd_tpg_id(sdev, &rel_port); 335 if (group_id < 0) { 336 /* 337 * Internal error; TPGS supported but required 338 * VPD identification descriptors not present. 339 * Disable ALUA support 340 */ 341 sdev_printk(KERN_INFO, sdev, 342 "%s: No target port descriptors found\n", 343 ALUA_DH_NAME); 344 return SCSI_DH_DEV_UNSUPP; 345 } 346 347 pg = alua_alloc_pg(sdev, group_id, tpgs); 348 if (IS_ERR(pg)) { 349 if (PTR_ERR(pg) == -ENOMEM) 350 return SCSI_DH_NOMEM; 351 return SCSI_DH_DEV_UNSUPP; 352 } 353 if (pg->device_id_len) 354 sdev_printk(KERN_INFO, sdev, 355 "%s: device %s port group %x rel port %x\n", 356 ALUA_DH_NAME, pg->device_id_str, 357 group_id, rel_port); 358 else 359 sdev_printk(KERN_INFO, sdev, 360 "%s: port group %x rel port %x\n", 361 ALUA_DH_NAME, group_id, rel_port); 362 363 kref_get(&pg->kref); 364 365 /* Check for existing port group references */ 366 spin_lock(&h->pg_lock); 367 old_pg = rcu_dereference_protected(h->pg, lockdep_is_held(&h->pg_lock)); 368 if (old_pg != pg) { 369 /* port group has changed. Update to new port group */ 370 if (h->pg) { 371 spin_lock_irqsave(&old_pg->lock, flags); 372 list_del_rcu(&h->node); 373 spin_unlock_irqrestore(&old_pg->lock, flags); 374 } 375 rcu_assign_pointer(h->pg, pg); 376 pg_updated = true; 377 } 378 379 spin_lock_irqsave(&pg->lock, flags); 380 if (pg_updated) 381 list_add_rcu(&h->node, &pg->dh_list); 382 spin_unlock_irqrestore(&pg->lock, flags); 383 384 spin_unlock(&h->pg_lock); 385 386 alua_rtpg_queue(pg, sdev, NULL, true); 387 kref_put(&pg->kref, release_port_group); 388 389 if (old_pg) 390 kref_put(&old_pg->kref, release_port_group); 391 392 return SCSI_DH_OK; 393} 394 395static char print_alua_state(unsigned char state) 396{ 397 switch (state) { 398 case SCSI_ACCESS_STATE_OPTIMAL: 399 return 'A'; 400 case SCSI_ACCESS_STATE_ACTIVE: 401 return 'N'; 402 case SCSI_ACCESS_STATE_STANDBY: 403 return 'S'; 404 case SCSI_ACCESS_STATE_UNAVAILABLE: 405 return 'U'; 406 case SCSI_ACCESS_STATE_LBA: 407 return 'L'; 408 case SCSI_ACCESS_STATE_OFFLINE: 409 return 'O'; 410 case SCSI_ACCESS_STATE_TRANSITIONING: 411 return 'T'; 412 default: 413 return 'X'; 414 } 415} 416 417static enum scsi_disposition alua_check_sense(struct scsi_device *sdev, 418 struct scsi_sense_hdr *sense_hdr) 419{ 420 struct alua_dh_data *h = sdev->handler_data; 421 struct alua_port_group *pg; 422 423 switch (sense_hdr->sense_key) { 424 case NOT_READY: 425 if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0a) { 426 /* 427 * LUN Not Accessible - ALUA state transition 428 */ 429 rcu_read_lock(); 430 pg = rcu_dereference(h->pg); 431 if (pg) 432 pg->state = SCSI_ACCESS_STATE_TRANSITIONING; 433 rcu_read_unlock(); 434 alua_check(sdev, false); 435 return NEEDS_RETRY; 436 } 437 break; 438 case UNIT_ATTENTION: 439 if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00) { 440 /* 441 * Power On, Reset, or Bus Device Reset. 442 * Might have obscured a state transition, 443 * so schedule a recheck. 444 */ 445 alua_check(sdev, true); 446 return ADD_TO_MLQUEUE; 447 } 448 if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x04) 449 /* 450 * Device internal reset 451 */ 452 return ADD_TO_MLQUEUE; 453 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x01) 454 /* 455 * Mode Parameters Changed 456 */ 457 return ADD_TO_MLQUEUE; 458 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x06) { 459 /* 460 * ALUA state changed 461 */ 462 alua_check(sdev, true); 463 return ADD_TO_MLQUEUE; 464 } 465 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x07) { 466 /* 467 * Implicit ALUA state transition failed 468 */ 469 alua_check(sdev, true); 470 return ADD_TO_MLQUEUE; 471 } 472 if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x03) 473 /* 474 * Inquiry data has changed 475 */ 476 return ADD_TO_MLQUEUE; 477 if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x0e) 478 /* 479 * REPORTED_LUNS_DATA_HAS_CHANGED is reported 480 * when switching controllers on targets like 481 * Intel Multi-Flex. We can just retry. 482 */ 483 return ADD_TO_MLQUEUE; 484 break; 485 } 486 487 return SCSI_RETURN_NOT_HANDLED; 488} 489 490/* 491 * alua_tur - Send a TEST UNIT READY 492 * @sdev: device to which the TEST UNIT READY command should be send 493 * 494 * Send a TEST UNIT READY to @sdev to figure out the device state 495 * Returns SCSI_DH_RETRY if the sense code is NOT READY/ALUA TRANSITIONING, 496 * SCSI_DH_OK if no error occurred, and SCSI_DH_IO otherwise. 497 */ 498static int alua_tur(struct scsi_device *sdev) 499{ 500 struct scsi_sense_hdr sense_hdr; 501 int retval; 502 503 retval = scsi_test_unit_ready(sdev, ALUA_FAILOVER_TIMEOUT * HZ, 504 ALUA_FAILOVER_RETRIES, &sense_hdr); 505 if (sense_hdr.sense_key == NOT_READY && 506 sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a) 507 return SCSI_DH_RETRY; 508 else if (retval) 509 return SCSI_DH_IO; 510 else 511 return SCSI_DH_OK; 512} 513 514/* 515 * alua_rtpg - Evaluate REPORT TARGET GROUP STATES 516 * @sdev: the device to be evaluated. 517 * 518 * Evaluate the Target Port Group State. 519 * Returns SCSI_DH_DEV_OFFLINED if the path is 520 * found to be unusable. 521 */ 522static int alua_rtpg(struct scsi_device *sdev, struct alua_port_group *pg) 523{ 524 struct scsi_sense_hdr sense_hdr; 525 struct alua_port_group *tmp_pg; 526 int len, k, off, bufflen = ALUA_RTPG_SIZE; 527 int group_id_old, state_old, pref_old, valid_states_old; 528 unsigned char *desc, *buff; 529 unsigned err; 530 int retval; 531 unsigned int tpg_desc_tbl_off; 532 unsigned char orig_transition_tmo; 533 unsigned long flags; 534 bool transitioning_sense = false; 535 536 group_id_old = pg->group_id; 537 state_old = pg->state; 538 pref_old = pg->pref; 539 valid_states_old = pg->valid_states; 540 541 if (!pg->expiry) { 542 unsigned long transition_tmo = ALUA_FAILOVER_TIMEOUT * HZ; 543 544 if (pg->transition_tmo) 545 transition_tmo = pg->transition_tmo * HZ; 546 547 pg->expiry = round_jiffies_up(jiffies + transition_tmo); 548 } 549 550 buff = kzalloc(bufflen, GFP_KERNEL); 551 if (!buff) 552 return SCSI_DH_DEV_TEMP_BUSY; 553 554 retry: 555 err = 0; 556 retval = submit_rtpg(sdev, buff, bufflen, &sense_hdr, pg->flags); 557 558 if (retval) { 559 /* 560 * Some (broken) implementations have a habit of returning 561 * an error during things like firmware update etc. 562 * But if the target only supports active/optimized there's 563 * not much we can do; it's not that we can switch paths 564 * or anything. 565 * So ignore any errors to avoid spurious failures during 566 * path failover. 567 */ 568 if ((pg->valid_states & ~TPGS_SUPPORT_OPTIMIZED) == 0) { 569 sdev_printk(KERN_INFO, sdev, 570 "%s: ignoring rtpg result %d\n", 571 ALUA_DH_NAME, retval); 572 kfree(buff); 573 return SCSI_DH_OK; 574 } 575 if (retval < 0 || !scsi_sense_valid(&sense_hdr)) { 576 sdev_printk(KERN_INFO, sdev, 577 "%s: rtpg failed, result %d\n", 578 ALUA_DH_NAME, retval); 579 kfree(buff); 580 if (retval < 0) 581 return SCSI_DH_DEV_TEMP_BUSY; 582 if (host_byte(retval) == DID_NO_CONNECT) 583 return SCSI_DH_RES_TEMP_UNAVAIL; 584 return SCSI_DH_IO; 585 } 586 587 /* 588 * submit_rtpg() has failed on existing arrays 589 * when requesting extended header info, and 590 * the array doesn't support extended headers, 591 * even though it shouldn't according to T10. 592 * The retry without rtpg_ext_hdr_req set 593 * handles this. 594 * Note: some arrays return a sense key of ILLEGAL_REQUEST 595 * with ASC 00h if they don't support the extended header. 596 */ 597 if (!(pg->flags & ALUA_RTPG_EXT_HDR_UNSUPP) && 598 sense_hdr.sense_key == ILLEGAL_REQUEST) { 599 pg->flags |= ALUA_RTPG_EXT_HDR_UNSUPP; 600 goto retry; 601 } 602 /* 603 * If the array returns with 'ALUA state transition' 604 * sense code here it cannot return RTPG data during 605 * transition. So set the state to 'transitioning' directly. 606 */ 607 if (sense_hdr.sense_key == NOT_READY && 608 sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a) { 609 transitioning_sense = true; 610 goto skip_rtpg; 611 } 612 /* 613 * Retry on any other UNIT ATTENTION occurred. 614 */ 615 if (sense_hdr.sense_key == UNIT_ATTENTION) 616 err = SCSI_DH_RETRY; 617 if (err == SCSI_DH_RETRY && 618 pg->expiry != 0 && time_before(jiffies, pg->expiry)) { 619 sdev_printk(KERN_ERR, sdev, "%s: rtpg retry\n", 620 ALUA_DH_NAME); 621 scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr); 622 kfree(buff); 623 return err; 624 } 625 sdev_printk(KERN_ERR, sdev, "%s: rtpg failed\n", 626 ALUA_DH_NAME); 627 scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr); 628 kfree(buff); 629 pg->expiry = 0; 630 return SCSI_DH_IO; 631 } 632 633 len = get_unaligned_be32(&buff[0]) + 4; 634 635 if (len > bufflen) { 636 /* Resubmit with the correct length */ 637 kfree(buff); 638 bufflen = len; 639 buff = kmalloc(bufflen, GFP_KERNEL); 640 if (!buff) { 641 sdev_printk(KERN_WARNING, sdev, 642 "%s: kmalloc buffer failed\n",__func__); 643 /* Temporary failure, bypass */ 644 pg->expiry = 0; 645 return SCSI_DH_DEV_TEMP_BUSY; 646 } 647 goto retry; 648 } 649 650 orig_transition_tmo = pg->transition_tmo; 651 if ((buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR && buff[5] != 0) 652 pg->transition_tmo = buff[5]; 653 else 654 pg->transition_tmo = ALUA_FAILOVER_TIMEOUT; 655 656 if (orig_transition_tmo != pg->transition_tmo) { 657 sdev_printk(KERN_INFO, sdev, 658 "%s: transition timeout set to %d seconds\n", 659 ALUA_DH_NAME, pg->transition_tmo); 660 pg->expiry = jiffies + pg->transition_tmo * HZ; 661 } 662 663 if ((buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR) 664 tpg_desc_tbl_off = 8; 665 else 666 tpg_desc_tbl_off = 4; 667 668 for (k = tpg_desc_tbl_off, desc = buff + tpg_desc_tbl_off; 669 k < len; 670 k += off, desc += off) { 671 u16 group_id = get_unaligned_be16(&desc[2]); 672 673 spin_lock_irqsave(&port_group_lock, flags); 674 tmp_pg = alua_find_get_pg(pg->device_id_str, pg->device_id_len, 675 group_id); 676 spin_unlock_irqrestore(&port_group_lock, flags); 677 if (tmp_pg) { 678 if (spin_trylock_irqsave(&tmp_pg->lock, flags)) { 679 if ((tmp_pg == pg) || 680 !(tmp_pg->flags & ALUA_PG_RUNNING)) { 681 struct alua_dh_data *h; 682 683 tmp_pg->state = desc[0] & 0x0f; 684 tmp_pg->pref = desc[0] >> 7; 685 rcu_read_lock(); 686 list_for_each_entry_rcu(h, 687 &tmp_pg->dh_list, node) { 688 if (!h->sdev) 689 continue; 690 h->sdev->access_state = desc[0]; 691 } 692 rcu_read_unlock(); 693 } 694 if (tmp_pg == pg) 695 tmp_pg->valid_states = desc[1]; 696 spin_unlock_irqrestore(&tmp_pg->lock, flags); 697 } 698 kref_put(&tmp_pg->kref, release_port_group); 699 } 700 off = 8 + (desc[7] * 4); 701 } 702 703 skip_rtpg: 704 spin_lock_irqsave(&pg->lock, flags); 705 if (transitioning_sense) 706 pg->state = SCSI_ACCESS_STATE_TRANSITIONING; 707 708 if (group_id_old != pg->group_id || state_old != pg->state || 709 pref_old != pg->pref || valid_states_old != pg->valid_states) 710 sdev_printk(KERN_INFO, sdev, 711 "%s: port group %02x state %c %s supports %c%c%c%c%c%c%c\n", 712 ALUA_DH_NAME, pg->group_id, print_alua_state(pg->state), 713 pg->pref ? "preferred" : "non-preferred", 714 pg->valid_states&TPGS_SUPPORT_TRANSITION?'T':'t', 715 pg->valid_states&TPGS_SUPPORT_OFFLINE?'O':'o', 716 pg->valid_states&TPGS_SUPPORT_LBA_DEPENDENT?'L':'l', 717 pg->valid_states&TPGS_SUPPORT_UNAVAILABLE?'U':'u', 718 pg->valid_states&TPGS_SUPPORT_STANDBY?'S':'s', 719 pg->valid_states&TPGS_SUPPORT_NONOPTIMIZED?'N':'n', 720 pg->valid_states&TPGS_SUPPORT_OPTIMIZED?'A':'a'); 721 722 switch (pg->state) { 723 case SCSI_ACCESS_STATE_TRANSITIONING: 724 if (time_before(jiffies, pg->expiry)) { 725 /* State transition, retry */ 726 pg->interval = ALUA_RTPG_RETRY_DELAY; 727 err = SCSI_DH_RETRY; 728 } else { 729 struct alua_dh_data *h; 730 731 /* Transitioning time exceeded, set port to standby */ 732 err = SCSI_DH_IO; 733 pg->state = SCSI_ACCESS_STATE_STANDBY; 734 pg->expiry = 0; 735 rcu_read_lock(); 736 list_for_each_entry_rcu(h, &pg->dh_list, node) { 737 if (!h->sdev) 738 continue; 739 h->sdev->access_state = 740 (pg->state & SCSI_ACCESS_STATE_MASK); 741 if (pg->pref) 742 h->sdev->access_state |= 743 SCSI_ACCESS_STATE_PREFERRED; 744 } 745 rcu_read_unlock(); 746 } 747 break; 748 case SCSI_ACCESS_STATE_OFFLINE: 749 /* Path unusable */ 750 err = SCSI_DH_DEV_OFFLINED; 751 pg->expiry = 0; 752 break; 753 default: 754 /* Useable path if active */ 755 err = SCSI_DH_OK; 756 pg->expiry = 0; 757 break; 758 } 759 spin_unlock_irqrestore(&pg->lock, flags); 760 kfree(buff); 761 return err; 762} 763 764/* 765 * alua_stpg - Issue a SET TARGET PORT GROUP command 766 * 767 * Issue a SET TARGET PORT GROUP command and evaluate the 768 * response. Returns SCSI_DH_RETRY per default to trigger 769 * a re-evaluation of the target group state or SCSI_DH_OK 770 * if no further action needs to be taken. 771 */ 772static unsigned alua_stpg(struct scsi_device *sdev, struct alua_port_group *pg) 773{ 774 int retval; 775 struct scsi_sense_hdr sense_hdr; 776 777 if (!(pg->tpgs & TPGS_MODE_EXPLICIT)) { 778 /* Only implicit ALUA supported, retry */ 779 return SCSI_DH_RETRY; 780 } 781 switch (pg->state) { 782 case SCSI_ACCESS_STATE_OPTIMAL: 783 return SCSI_DH_OK; 784 case SCSI_ACCESS_STATE_ACTIVE: 785 if ((pg->flags & ALUA_OPTIMIZE_STPG) && 786 !pg->pref && 787 (pg->tpgs & TPGS_MODE_IMPLICIT)) 788 return SCSI_DH_OK; 789 break; 790 case SCSI_ACCESS_STATE_STANDBY: 791 case SCSI_ACCESS_STATE_UNAVAILABLE: 792 break; 793 case SCSI_ACCESS_STATE_OFFLINE: 794 return SCSI_DH_IO; 795 case SCSI_ACCESS_STATE_TRANSITIONING: 796 break; 797 default: 798 sdev_printk(KERN_INFO, sdev, 799 "%s: stpg failed, unhandled TPGS state %d", 800 ALUA_DH_NAME, pg->state); 801 return SCSI_DH_NOSYS; 802 } 803 retval = submit_stpg(sdev, pg->group_id, &sense_hdr); 804 805 if (retval) { 806 if (retval < 0 || !scsi_sense_valid(&sense_hdr)) { 807 sdev_printk(KERN_INFO, sdev, 808 "%s: stpg failed, result %d", 809 ALUA_DH_NAME, retval); 810 if (retval < 0) 811 return SCSI_DH_DEV_TEMP_BUSY; 812 } else { 813 sdev_printk(KERN_INFO, sdev, "%s: stpg failed\n", 814 ALUA_DH_NAME); 815 scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr); 816 } 817 } 818 /* Retry RTPG */ 819 return SCSI_DH_RETRY; 820} 821 822/* 823 * The caller must call scsi_device_put() on the returned pointer if it is not 824 * NULL. 825 */ 826static struct scsi_device * __must_check 827alua_rtpg_select_sdev(struct alua_port_group *pg) 828{ 829 struct alua_dh_data *h; 830 struct scsi_device *sdev = NULL, *prev_sdev; 831 832 lockdep_assert_held(&pg->lock); 833 if (WARN_ON(!pg->rtpg_sdev)) 834 return NULL; 835 836 /* 837 * RCU protection isn't necessary for dh_list here 838 * as we hold pg->lock, but for access to h->pg. 839 */ 840 rcu_read_lock(); 841 list_for_each_entry_rcu(h, &pg->dh_list, node) { 842 if (!h->sdev) 843 continue; 844 if (h->sdev == pg->rtpg_sdev) { 845 h->disabled = true; 846 continue; 847 } 848 if (rcu_dereference(h->pg) == pg && 849 !h->disabled && 850 !scsi_device_get(h->sdev)) { 851 sdev = h->sdev; 852 break; 853 } 854 } 855 rcu_read_unlock(); 856 857 if (!sdev) { 858 pr_warn("%s: no device found for rtpg\n", 859 (pg->device_id_len ? 860 (char *)pg->device_id_str : "(nameless PG)")); 861 return NULL; 862 } 863 864 sdev_printk(KERN_INFO, sdev, "rtpg retry on different device\n"); 865 866 prev_sdev = pg->rtpg_sdev; 867 pg->rtpg_sdev = sdev; 868 869 return prev_sdev; 870} 871 872static void alua_rtpg_work(struct work_struct *work) 873{ 874 struct alua_port_group *pg = 875 container_of(work, struct alua_port_group, rtpg_work.work); 876 struct scsi_device *sdev, *prev_sdev = NULL; 877 LIST_HEAD(qdata_list); 878 int err = SCSI_DH_OK; 879 struct alua_queue_data *qdata, *tmp; 880 struct alua_dh_data *h; 881 unsigned long flags; 882 883 spin_lock_irqsave(&pg->lock, flags); 884 sdev = pg->rtpg_sdev; 885 if (!sdev) { 886 WARN_ON(pg->flags & ALUA_PG_RUN_RTPG); 887 WARN_ON(pg->flags & ALUA_PG_RUN_STPG); 888 spin_unlock_irqrestore(&pg->lock, flags); 889 kref_put(&pg->kref, release_port_group); 890 return; 891 } 892 pg->flags |= ALUA_PG_RUNNING; 893 if (pg->flags & ALUA_PG_RUN_RTPG) { 894 int state = pg->state; 895 896 pg->flags &= ~ALUA_PG_RUN_RTPG; 897 spin_unlock_irqrestore(&pg->lock, flags); 898 if (state == SCSI_ACCESS_STATE_TRANSITIONING) { 899 if (alua_tur(sdev) == SCSI_DH_RETRY) { 900 spin_lock_irqsave(&pg->lock, flags); 901 pg->flags &= ~ALUA_PG_RUNNING; 902 pg->flags |= ALUA_PG_RUN_RTPG; 903 if (!pg->interval) 904 pg->interval = ALUA_RTPG_RETRY_DELAY; 905 spin_unlock_irqrestore(&pg->lock, flags); 906 queue_delayed_work(kaluad_wq, &pg->rtpg_work, 907 pg->interval * HZ); 908 return; 909 } 910 /* Send RTPG on failure or if TUR indicates SUCCESS */ 911 } 912 err = alua_rtpg(sdev, pg); 913 spin_lock_irqsave(&pg->lock, flags); 914 915 /* If RTPG failed on the current device, try using another */ 916 if (err == SCSI_DH_RES_TEMP_UNAVAIL && 917 (prev_sdev = alua_rtpg_select_sdev(pg))) 918 err = SCSI_DH_IMM_RETRY; 919 920 if (err == SCSI_DH_RETRY || err == SCSI_DH_IMM_RETRY || 921 pg->flags & ALUA_PG_RUN_RTPG) { 922 pg->flags &= ~ALUA_PG_RUNNING; 923 if (err == SCSI_DH_IMM_RETRY) 924 pg->interval = 0; 925 else if (!pg->interval && !(pg->flags & ALUA_PG_RUN_RTPG)) 926 pg->interval = ALUA_RTPG_RETRY_DELAY; 927 pg->flags |= ALUA_PG_RUN_RTPG; 928 spin_unlock_irqrestore(&pg->lock, flags); 929 goto queue_rtpg; 930 } 931 if (err != SCSI_DH_OK) 932 pg->flags &= ~ALUA_PG_RUN_STPG; 933 } 934 if (pg->flags & ALUA_PG_RUN_STPG) { 935 pg->flags &= ~ALUA_PG_RUN_STPG; 936 spin_unlock_irqrestore(&pg->lock, flags); 937 err = alua_stpg(sdev, pg); 938 spin_lock_irqsave(&pg->lock, flags); 939 if (err == SCSI_DH_RETRY || pg->flags & ALUA_PG_RUN_RTPG) { 940 pg->flags |= ALUA_PG_RUN_RTPG; 941 pg->interval = 0; 942 pg->flags &= ~ALUA_PG_RUNNING; 943 spin_unlock_irqrestore(&pg->lock, flags); 944 goto queue_rtpg; 945 } 946 } 947 948 list_splice_init(&pg->rtpg_list, &qdata_list); 949 /* 950 * We went through an RTPG, for good or bad. 951 * Re-enable all devices for the next attempt. 952 */ 953 list_for_each_entry(h, &pg->dh_list, node) 954 h->disabled = false; 955 pg->rtpg_sdev = NULL; 956 spin_unlock_irqrestore(&pg->lock, flags); 957 958 if (prev_sdev) 959 scsi_device_put(prev_sdev); 960 961 list_for_each_entry_safe(qdata, tmp, &qdata_list, entry) { 962 list_del(&qdata->entry); 963 if (qdata->callback_fn) 964 qdata->callback_fn(qdata->callback_data, err); 965 kfree(qdata); 966 } 967 spin_lock_irqsave(&pg->lock, flags); 968 pg->flags &= ~ALUA_PG_RUNNING; 969 spin_unlock_irqrestore(&pg->lock, flags); 970 scsi_device_put(sdev); 971 kref_put(&pg->kref, release_port_group); 972 return; 973 974queue_rtpg: 975 if (prev_sdev) 976 scsi_device_put(prev_sdev); 977 queue_delayed_work(kaluad_wq, &pg->rtpg_work, pg->interval * HZ); 978} 979 980/** 981 * alua_rtpg_queue() - cause RTPG to be submitted asynchronously 982 * @pg: ALUA port group associated with @sdev. 983 * @sdev: SCSI device for which to submit an RTPG. 984 * @qdata: Information about the callback to invoke after the RTPG. 985 * @force: Whether or not to submit an RTPG if a work item that will submit an 986 * RTPG already has been scheduled. 987 * 988 * Returns true if and only if alua_rtpg_work() will be called asynchronously. 989 * That function is responsible for calling @qdata->fn(). 990 * 991 * Context: may be called from atomic context (alua_check()) only if the caller 992 * holds an sdev reference. 993 */ 994static bool alua_rtpg_queue(struct alua_port_group *pg, 995 struct scsi_device *sdev, 996 struct alua_queue_data *qdata, bool force) 997{ 998 int start_queue = 0; 999 unsigned long flags; 1000 1001 if (WARN_ON_ONCE(!pg) || scsi_device_get(sdev)) 1002 return false; 1003 1004 spin_lock_irqsave(&pg->lock, flags); 1005 if (qdata) { 1006 list_add_tail(&qdata->entry, &pg->rtpg_list); 1007 pg->flags |= ALUA_PG_RUN_STPG; 1008 force = true; 1009 } 1010 if (pg->rtpg_sdev == NULL) { 1011 struct alua_dh_data *h = sdev->handler_data; 1012 1013 rcu_read_lock(); 1014 if (h && rcu_dereference(h->pg) == pg) { 1015 pg->interval = 0; 1016 pg->flags |= ALUA_PG_RUN_RTPG; 1017 kref_get(&pg->kref); 1018 pg->rtpg_sdev = sdev; 1019 start_queue = 1; 1020 } 1021 rcu_read_unlock(); 1022 } else if (!(pg->flags & ALUA_PG_RUN_RTPG) && force) { 1023 pg->flags |= ALUA_PG_RUN_RTPG; 1024 /* Do not queue if the worker is already running */ 1025 if (!(pg->flags & ALUA_PG_RUNNING)) { 1026 kref_get(&pg->kref); 1027 start_queue = 1; 1028 } 1029 } 1030 1031 spin_unlock_irqrestore(&pg->lock, flags); 1032 1033 if (start_queue) { 1034 if (queue_delayed_work(kaluad_wq, &pg->rtpg_work, 1035 msecs_to_jiffies(ALUA_RTPG_DELAY_MSECS))) 1036 sdev = NULL; 1037 else 1038 kref_put(&pg->kref, release_port_group); 1039 } 1040 if (sdev) 1041 scsi_device_put(sdev); 1042 1043 return true; 1044} 1045 1046/* 1047 * alua_initialize - Initialize ALUA state 1048 * @sdev: the device to be initialized 1049 * 1050 * For the prep_fn to work correctly we have 1051 * to initialize the ALUA state for the device. 1052 */ 1053static int alua_initialize(struct scsi_device *sdev, struct alua_dh_data *h) 1054{ 1055 int err = SCSI_DH_DEV_UNSUPP, tpgs; 1056 1057 mutex_lock(&h->init_mutex); 1058 h->disabled = false; 1059 tpgs = alua_check_tpgs(sdev); 1060 if (tpgs != TPGS_MODE_NONE) 1061 err = alua_check_vpd(sdev, h, tpgs); 1062 h->init_error = err; 1063 mutex_unlock(&h->init_mutex); 1064 return err; 1065} 1066/* 1067 * alua_set_params - set/unset the optimize flag 1068 * @sdev: device on the path to be activated 1069 * params - parameters in the following format 1070 * "no_of_params\0param1\0param2\0param3\0...\0" 1071 * For example, to set the flag pass the following parameters 1072 * from multipath.conf 1073 * hardware_handler "2 alua 1" 1074 */ 1075static int alua_set_params(struct scsi_device *sdev, const char *params) 1076{ 1077 struct alua_dh_data *h = sdev->handler_data; 1078 struct alua_port_group *pg = NULL; 1079 unsigned int optimize = 0, argc; 1080 const char *p = params; 1081 int result = SCSI_DH_OK; 1082 unsigned long flags; 1083 1084 if ((sscanf(params, "%u", &argc) != 1) || (argc != 1)) 1085 return -EINVAL; 1086 1087 while (*p++) 1088 ; 1089 if ((sscanf(p, "%u", &optimize) != 1) || (optimize > 1)) 1090 return -EINVAL; 1091 1092 rcu_read_lock(); 1093 pg = rcu_dereference(h->pg); 1094 if (!pg) { 1095 rcu_read_unlock(); 1096 return -ENXIO; 1097 } 1098 spin_lock_irqsave(&pg->lock, flags); 1099 if (optimize) 1100 pg->flags |= ALUA_OPTIMIZE_STPG; 1101 else 1102 pg->flags &= ~ALUA_OPTIMIZE_STPG; 1103 spin_unlock_irqrestore(&pg->lock, flags); 1104 rcu_read_unlock(); 1105 1106 return result; 1107} 1108 1109/* 1110 * alua_activate - activate a path 1111 * @sdev: device on the path to be activated 1112 * 1113 * We're currently switching the port group to be activated only and 1114 * let the array figure out the rest. 1115 * There may be other arrays which require us to switch all port groups 1116 * based on a certain policy. But until we actually encounter them it 1117 * should be okay. 1118 */ 1119static int alua_activate(struct scsi_device *sdev, 1120 activate_complete fn, void *data) 1121{ 1122 struct alua_dh_data *h = sdev->handler_data; 1123 int err = SCSI_DH_OK; 1124 struct alua_queue_data *qdata; 1125 struct alua_port_group *pg; 1126 1127 qdata = kzalloc(sizeof(*qdata), GFP_KERNEL); 1128 if (!qdata) { 1129 err = SCSI_DH_RES_TEMP_UNAVAIL; 1130 goto out; 1131 } 1132 qdata->callback_fn = fn; 1133 qdata->callback_data = data; 1134 1135 mutex_lock(&h->init_mutex); 1136 rcu_read_lock(); 1137 pg = rcu_dereference(h->pg); 1138 if (!pg || !kref_get_unless_zero(&pg->kref)) { 1139 rcu_read_unlock(); 1140 kfree(qdata); 1141 err = h->init_error; 1142 mutex_unlock(&h->init_mutex); 1143 goto out; 1144 } 1145 rcu_read_unlock(); 1146 mutex_unlock(&h->init_mutex); 1147 1148 if (alua_rtpg_queue(pg, sdev, qdata, true)) { 1149 fn = NULL; 1150 } else { 1151 kfree(qdata); 1152 err = SCSI_DH_DEV_OFFLINED; 1153 } 1154 kref_put(&pg->kref, release_port_group); 1155out: 1156 if (fn) 1157 fn(data, err); 1158 return 0; 1159} 1160 1161/* 1162 * alua_check - check path status 1163 * @sdev: device on the path to be checked 1164 * 1165 * Check the device status 1166 */ 1167static void alua_check(struct scsi_device *sdev, bool force) 1168{ 1169 struct alua_dh_data *h = sdev->handler_data; 1170 struct alua_port_group *pg; 1171 1172 rcu_read_lock(); 1173 pg = rcu_dereference(h->pg); 1174 if (!pg || !kref_get_unless_zero(&pg->kref)) { 1175 rcu_read_unlock(); 1176 return; 1177 } 1178 rcu_read_unlock(); 1179 alua_rtpg_queue(pg, sdev, NULL, force); 1180 kref_put(&pg->kref, release_port_group); 1181} 1182 1183/* 1184 * alua_prep_fn - request callback 1185 * 1186 * Fail I/O to all paths not in state 1187 * active/optimized or active/non-optimized. 1188 */ 1189static blk_status_t alua_prep_fn(struct scsi_device *sdev, struct request *req) 1190{ 1191 struct alua_dh_data *h = sdev->handler_data; 1192 struct alua_port_group *pg; 1193 unsigned char state = SCSI_ACCESS_STATE_OPTIMAL; 1194 1195 rcu_read_lock(); 1196 pg = rcu_dereference(h->pg); 1197 if (pg) 1198 state = pg->state; 1199 rcu_read_unlock(); 1200 1201 switch (state) { 1202 case SCSI_ACCESS_STATE_OPTIMAL: 1203 case SCSI_ACCESS_STATE_ACTIVE: 1204 case SCSI_ACCESS_STATE_LBA: 1205 case SCSI_ACCESS_STATE_TRANSITIONING: 1206 return BLK_STS_OK; 1207 default: 1208 req->rq_flags |= RQF_QUIET; 1209 return BLK_STS_IOERR; 1210 } 1211} 1212 1213static void alua_rescan(struct scsi_device *sdev) 1214{ 1215 struct alua_dh_data *h = sdev->handler_data; 1216 1217 alua_initialize(sdev, h); 1218} 1219 1220/* 1221 * alua_bus_attach - Attach device handler 1222 * @sdev: device to be attached to 1223 */ 1224static int alua_bus_attach(struct scsi_device *sdev) 1225{ 1226 struct alua_dh_data *h; 1227 int err; 1228 1229 h = kzalloc(sizeof(*h) , GFP_KERNEL); 1230 if (!h) 1231 return SCSI_DH_NOMEM; 1232 spin_lock_init(&h->pg_lock); 1233 rcu_assign_pointer(h->pg, NULL); 1234 h->init_error = SCSI_DH_OK; 1235 h->sdev = sdev; 1236 INIT_LIST_HEAD(&h->node); 1237 1238 mutex_init(&h->init_mutex); 1239 err = alua_initialize(sdev, h); 1240 if (err != SCSI_DH_OK && err != SCSI_DH_DEV_OFFLINED) 1241 goto failed; 1242 1243 sdev->handler_data = h; 1244 return SCSI_DH_OK; 1245failed: 1246 kfree(h); 1247 return err; 1248} 1249 1250/* 1251 * alua_bus_detach - Detach device handler 1252 * @sdev: device to be detached from 1253 */ 1254static void alua_bus_detach(struct scsi_device *sdev) 1255{ 1256 struct alua_dh_data *h = sdev->handler_data; 1257 struct alua_port_group *pg; 1258 1259 spin_lock(&h->pg_lock); 1260 pg = rcu_dereference_protected(h->pg, lockdep_is_held(&h->pg_lock)); 1261 rcu_assign_pointer(h->pg, NULL); 1262 spin_unlock(&h->pg_lock); 1263 if (pg) { 1264 spin_lock_irq(&pg->lock); 1265 list_del_rcu(&h->node); 1266 spin_unlock_irq(&pg->lock); 1267 kref_put(&pg->kref, release_port_group); 1268 } 1269 sdev->handler_data = NULL; 1270 synchronize_rcu(); 1271 kfree(h); 1272} 1273 1274static struct scsi_device_handler alua_dh = { 1275 .name = ALUA_DH_NAME, 1276 .module = THIS_MODULE, 1277 .attach = alua_bus_attach, 1278 .detach = alua_bus_detach, 1279 .prep_fn = alua_prep_fn, 1280 .check_sense = alua_check_sense, 1281 .activate = alua_activate, 1282 .rescan = alua_rescan, 1283 .set_params = alua_set_params, 1284}; 1285 1286static int __init alua_init(void) 1287{ 1288 int r; 1289 1290 kaluad_wq = alloc_workqueue("kaluad", WQ_MEM_RECLAIM, 0); 1291 if (!kaluad_wq) 1292 return -ENOMEM; 1293 1294 r = scsi_register_device_handler(&alua_dh); 1295 if (r != 0) { 1296 printk(KERN_ERR "%s: Failed to register scsi device handler", 1297 ALUA_DH_NAME); 1298 destroy_workqueue(kaluad_wq); 1299 } 1300 return r; 1301} 1302 1303static void __exit alua_exit(void) 1304{ 1305 scsi_unregister_device_handler(&alua_dh); 1306 destroy_workqueue(kaluad_wq); 1307} 1308 1309module_init(alua_init); 1310module_exit(alua_exit); 1311 1312MODULE_DESCRIPTION("DM Multipath ALUA support"); 1313MODULE_AUTHOR("Hannes Reinecke <hare@suse.de>"); 1314MODULE_LICENSE("GPL"); 1315MODULE_VERSION(ALUA_DH_VER); 1316