scsi_lib.c revision e9dd2b6837e26fe202708cce5ea4bb4ee3e3482e
1/* 2 * scsi_lib.c Copyright (C) 1999 Eric Youngdale 3 * 4 * SCSI queueing library. 5 * Initial versions: Eric Youngdale (eric@andante.org). 6 * Based upon conversations with large numbers 7 * of people at Linux Expo. 8 */ 9 10#include <linux/bio.h> 11#include <linux/bitops.h> 12#include <linux/blkdev.h> 13#include <linux/completion.h> 14#include <linux/kernel.h> 15#include <linux/mempool.h> 16#include <linux/slab.h> 17#include <linux/init.h> 18#include <linux/pci.h> 19#include <linux/delay.h> 20#include <linux/hardirq.h> 21#include <linux/scatterlist.h> 22 23#include <scsi/scsi.h> 24#include <scsi/scsi_cmnd.h> 25#include <scsi/scsi_dbg.h> 26#include <scsi/scsi_device.h> 27#include <scsi/scsi_driver.h> 28#include <scsi/scsi_eh.h> 29#include <scsi/scsi_host.h> 30 31#include "scsi_priv.h" 32#include "scsi_logging.h" 33 34 35#define SG_MEMPOOL_NR ARRAY_SIZE(scsi_sg_pools) 36#define SG_MEMPOOL_SIZE 2 37 38struct scsi_host_sg_pool { 39 size_t size; 40 char *name; 41 struct kmem_cache *slab; 42 mempool_t *pool; 43}; 44 45#define SP(x) { x, "sgpool-" __stringify(x) } 46#if (SCSI_MAX_SG_SEGMENTS < 32) 47#error SCSI_MAX_SG_SEGMENTS is too small (must be 32 or greater) 48#endif 49static struct scsi_host_sg_pool scsi_sg_pools[] = { 50 SP(8), 51 SP(16), 52#if (SCSI_MAX_SG_SEGMENTS > 32) 53 SP(32), 54#if (SCSI_MAX_SG_SEGMENTS > 64) 55 SP(64), 56#if (SCSI_MAX_SG_SEGMENTS > 128) 57 SP(128), 58#if (SCSI_MAX_SG_SEGMENTS > 256) 59#error SCSI_MAX_SG_SEGMENTS is too large (256 MAX) 60#endif 61#endif 62#endif 63#endif 64 SP(SCSI_MAX_SG_SEGMENTS) 65}; 66#undef SP 67 68struct kmem_cache *scsi_sdb_cache; 69 70static void scsi_run_queue(struct request_queue *q); 71 72/* 73 * Function: scsi_unprep_request() 74 * 75 * Purpose: Remove all preparation done for a request, including its 76 * associated scsi_cmnd, so that it can be requeued. 77 * 78 * Arguments: req - request to unprepare 79 * 80 * Lock status: Assumed that no locks are held upon entry. 81 * 82 * Returns: Nothing. 83 */ 84static void scsi_unprep_request(struct request *req) 85{ 86 struct scsi_cmnd *cmd = req->special; 87 88 blk_unprep_request(req); 89 req->special = NULL; 90 91 scsi_put_command(cmd); 92} 93 94/** 95 * __scsi_queue_insert - private queue insertion 96 * @cmd: The SCSI command being requeued 97 * @reason: The reason for the requeue 98 * @unbusy: Whether the queue should be unbusied 99 * 100 * This is a private queue insertion. The public interface 101 * scsi_queue_insert() always assumes the queue should be unbusied 102 * because it's always called before the completion. This function is 103 * for a requeue after completion, which should only occur in this 104 * file. 105 */ 106static int __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, int unbusy) 107{ 108 struct Scsi_Host *host = cmd->device->host; 109 struct scsi_device *device = cmd->device; 110 struct scsi_target *starget = scsi_target(device); 111 struct request_queue *q = device->request_queue; 112 unsigned long flags; 113 114 SCSI_LOG_MLQUEUE(1, 115 printk("Inserting command %p into mlqueue\n", cmd)); 116 117 /* 118 * Set the appropriate busy bit for the device/host. 119 * 120 * If the host/device isn't busy, assume that something actually 121 * completed, and that we should be able to queue a command now. 122 * 123 * Note that the prior mid-layer assumption that any host could 124 * always queue at least one command is now broken. The mid-layer 125 * will implement a user specifiable stall (see 126 * scsi_host.max_host_blocked and scsi_device.max_device_blocked) 127 * if a command is requeued with no other commands outstanding 128 * either for the device or for the host. 129 */ 130 switch (reason) { 131 case SCSI_MLQUEUE_HOST_BUSY: 132 host->host_blocked = host->max_host_blocked; 133 break; 134 case SCSI_MLQUEUE_DEVICE_BUSY: 135 device->device_blocked = device->max_device_blocked; 136 break; 137 case SCSI_MLQUEUE_TARGET_BUSY: 138 starget->target_blocked = starget->max_target_blocked; 139 break; 140 } 141 142 /* 143 * Decrement the counters, since these commands are no longer 144 * active on the host/device. 145 */ 146 if (unbusy) 147 scsi_device_unbusy(device); 148 149 /* 150 * Requeue this command. It will go before all other commands 151 * that are already in the queue. 152 * 153 * NOTE: there is magic here about the way the queue is plugged if 154 * we have no outstanding commands. 155 * 156 * Although we *don't* plug the queue, we call the request 157 * function. The SCSI request function detects the blocked condition 158 * and plugs the queue appropriately. 159 */ 160 spin_lock_irqsave(q->queue_lock, flags); 161 blk_requeue_request(q, cmd->request); 162 spin_unlock_irqrestore(q->queue_lock, flags); 163 164 scsi_run_queue(q); 165 166 return 0; 167} 168 169/* 170 * Function: scsi_queue_insert() 171 * 172 * Purpose: Insert a command in the midlevel queue. 173 * 174 * Arguments: cmd - command that we are adding to queue. 175 * reason - why we are inserting command to queue. 176 * 177 * Lock status: Assumed that lock is not held upon entry. 178 * 179 * Returns: Nothing. 180 * 181 * Notes: We do this for one of two cases. Either the host is busy 182 * and it cannot accept any more commands for the time being, 183 * or the device returned QUEUE_FULL and can accept no more 184 * commands. 185 * Notes: This could be called either from an interrupt context or a 186 * normal process context. 187 */ 188int scsi_queue_insert(struct scsi_cmnd *cmd, int reason) 189{ 190 return __scsi_queue_insert(cmd, reason, 1); 191} 192/** 193 * scsi_execute - insert request and wait for the result 194 * @sdev: scsi device 195 * @cmd: scsi command 196 * @data_direction: data direction 197 * @buffer: data buffer 198 * @bufflen: len of buffer 199 * @sense: optional sense buffer 200 * @timeout: request timeout in seconds 201 * @retries: number of times to retry request 202 * @flags: or into request flags; 203 * @resid: optional residual length 204 * 205 * returns the req->errors value which is the scsi_cmnd result 206 * field. 207 */ 208int scsi_execute(struct scsi_device *sdev, const unsigned char *cmd, 209 int data_direction, void *buffer, unsigned bufflen, 210 unsigned char *sense, int timeout, int retries, int flags, 211 int *resid) 212{ 213 struct request *req; 214 int write = (data_direction == DMA_TO_DEVICE); 215 int ret = DRIVER_ERROR << 24; 216 217 req = blk_get_request(sdev->request_queue, write, __GFP_WAIT); 218 219 if (bufflen && blk_rq_map_kern(sdev->request_queue, req, 220 buffer, bufflen, __GFP_WAIT)) 221 goto out; 222 223 req->cmd_len = COMMAND_SIZE(cmd[0]); 224 memcpy(req->cmd, cmd, req->cmd_len); 225 req->sense = sense; 226 req->sense_len = 0; 227 req->retries = retries; 228 req->timeout = timeout; 229 req->cmd_type = REQ_TYPE_BLOCK_PC; 230 req->cmd_flags |= flags | REQ_QUIET | REQ_PREEMPT; 231 232 /* 233 * head injection *required* here otherwise quiesce won't work 234 */ 235 blk_execute_rq(req->q, NULL, req, 1); 236 237 /* 238 * Some devices (USB mass-storage in particular) may transfer 239 * garbage data together with a residue indicating that the data 240 * is invalid. Prevent the garbage from being misinterpreted 241 * and prevent security leaks by zeroing out the excess data. 242 */ 243 if (unlikely(req->resid_len > 0 && req->resid_len <= bufflen)) 244 memset(buffer + (bufflen - req->resid_len), 0, req->resid_len); 245 246 if (resid) 247 *resid = req->resid_len; 248 ret = req->errors; 249 out: 250 blk_put_request(req); 251 252 return ret; 253} 254EXPORT_SYMBOL(scsi_execute); 255 256 257int scsi_execute_req(struct scsi_device *sdev, const unsigned char *cmd, 258 int data_direction, void *buffer, unsigned bufflen, 259 struct scsi_sense_hdr *sshdr, int timeout, int retries, 260 int *resid) 261{ 262 char *sense = NULL; 263 int result; 264 265 if (sshdr) { 266 sense = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_NOIO); 267 if (!sense) 268 return DRIVER_ERROR << 24; 269 } 270 result = scsi_execute(sdev, cmd, data_direction, buffer, bufflen, 271 sense, timeout, retries, 0, resid); 272 if (sshdr) 273 scsi_normalize_sense(sense, SCSI_SENSE_BUFFERSIZE, sshdr); 274 275 kfree(sense); 276 return result; 277} 278EXPORT_SYMBOL(scsi_execute_req); 279 280/* 281 * Function: scsi_init_cmd_errh() 282 * 283 * Purpose: Initialize cmd fields related to error handling. 284 * 285 * Arguments: cmd - command that is ready to be queued. 286 * 287 * Notes: This function has the job of initializing a number of 288 * fields related to error handling. Typically this will 289 * be called once for each command, as required. 290 */ 291static void scsi_init_cmd_errh(struct scsi_cmnd *cmd) 292{ 293 cmd->serial_number = 0; 294 scsi_set_resid(cmd, 0); 295 memset(cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE); 296 if (cmd->cmd_len == 0) 297 cmd->cmd_len = scsi_command_size(cmd->cmnd); 298} 299 300void scsi_device_unbusy(struct scsi_device *sdev) 301{ 302 struct Scsi_Host *shost = sdev->host; 303 struct scsi_target *starget = scsi_target(sdev); 304 unsigned long flags; 305 306 spin_lock_irqsave(shost->host_lock, flags); 307 shost->host_busy--; 308 starget->target_busy--; 309 if (unlikely(scsi_host_in_recovery(shost) && 310 (shost->host_failed || shost->host_eh_scheduled))) 311 scsi_eh_wakeup(shost); 312 spin_unlock(shost->host_lock); 313 spin_lock(sdev->request_queue->queue_lock); 314 sdev->device_busy--; 315 spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags); 316} 317 318/* 319 * Called for single_lun devices on IO completion. Clear starget_sdev_user, 320 * and call blk_run_queue for all the scsi_devices on the target - 321 * including current_sdev first. 322 * 323 * Called with *no* scsi locks held. 324 */ 325static void scsi_single_lun_run(struct scsi_device *current_sdev) 326{ 327 struct Scsi_Host *shost = current_sdev->host; 328 struct scsi_device *sdev, *tmp; 329 struct scsi_target *starget = scsi_target(current_sdev); 330 unsigned long flags; 331 332 spin_lock_irqsave(shost->host_lock, flags); 333 starget->starget_sdev_user = NULL; 334 spin_unlock_irqrestore(shost->host_lock, flags); 335 336 /* 337 * Call blk_run_queue for all LUNs on the target, starting with 338 * current_sdev. We race with others (to set starget_sdev_user), 339 * but in most cases, we will be first. Ideally, each LU on the 340 * target would get some limited time or requests on the target. 341 */ 342 blk_run_queue(current_sdev->request_queue); 343 344 spin_lock_irqsave(shost->host_lock, flags); 345 if (starget->starget_sdev_user) 346 goto out; 347 list_for_each_entry_safe(sdev, tmp, &starget->devices, 348 same_target_siblings) { 349 if (sdev == current_sdev) 350 continue; 351 if (scsi_device_get(sdev)) 352 continue; 353 354 spin_unlock_irqrestore(shost->host_lock, flags); 355 blk_run_queue(sdev->request_queue); 356 spin_lock_irqsave(shost->host_lock, flags); 357 358 scsi_device_put(sdev); 359 } 360 out: 361 spin_unlock_irqrestore(shost->host_lock, flags); 362} 363 364static inline int scsi_device_is_busy(struct scsi_device *sdev) 365{ 366 if (sdev->device_busy >= sdev->queue_depth || sdev->device_blocked) 367 return 1; 368 369 return 0; 370} 371 372static inline int scsi_target_is_busy(struct scsi_target *starget) 373{ 374 return ((starget->can_queue > 0 && 375 starget->target_busy >= starget->can_queue) || 376 starget->target_blocked); 377} 378 379static inline int scsi_host_is_busy(struct Scsi_Host *shost) 380{ 381 if ((shost->can_queue > 0 && shost->host_busy >= shost->can_queue) || 382 shost->host_blocked || shost->host_self_blocked) 383 return 1; 384 385 return 0; 386} 387 388/* 389 * Function: scsi_run_queue() 390 * 391 * Purpose: Select a proper request queue to serve next 392 * 393 * Arguments: q - last request's queue 394 * 395 * Returns: Nothing 396 * 397 * Notes: The previous command was completely finished, start 398 * a new one if possible. 399 */ 400static void scsi_run_queue(struct request_queue *q) 401{ 402 struct scsi_device *sdev = q->queuedata; 403 struct Scsi_Host *shost = sdev->host; 404 LIST_HEAD(starved_list); 405 unsigned long flags; 406 407 if (scsi_target(sdev)->single_lun) 408 scsi_single_lun_run(sdev); 409 410 spin_lock_irqsave(shost->host_lock, flags); 411 list_splice_init(&shost->starved_list, &starved_list); 412 413 while (!list_empty(&starved_list)) { 414 int flagset; 415 416 /* 417 * As long as shost is accepting commands and we have 418 * starved queues, call blk_run_queue. scsi_request_fn 419 * drops the queue_lock and can add us back to the 420 * starved_list. 421 * 422 * host_lock protects the starved_list and starved_entry. 423 * scsi_request_fn must get the host_lock before checking 424 * or modifying starved_list or starved_entry. 425 */ 426 if (scsi_host_is_busy(shost)) 427 break; 428 429 sdev = list_entry(starved_list.next, 430 struct scsi_device, starved_entry); 431 list_del_init(&sdev->starved_entry); 432 if (scsi_target_is_busy(scsi_target(sdev))) { 433 list_move_tail(&sdev->starved_entry, 434 &shost->starved_list); 435 continue; 436 } 437 438 spin_unlock(shost->host_lock); 439 440 spin_lock(sdev->request_queue->queue_lock); 441 flagset = test_bit(QUEUE_FLAG_REENTER, &q->queue_flags) && 442 !test_bit(QUEUE_FLAG_REENTER, 443 &sdev->request_queue->queue_flags); 444 if (flagset) 445 queue_flag_set(QUEUE_FLAG_REENTER, sdev->request_queue); 446 __blk_run_queue(sdev->request_queue); 447 if (flagset) 448 queue_flag_clear(QUEUE_FLAG_REENTER, sdev->request_queue); 449 spin_unlock(sdev->request_queue->queue_lock); 450 451 spin_lock(shost->host_lock); 452 } 453 /* put any unprocessed entries back */ 454 list_splice(&starved_list, &shost->starved_list); 455 spin_unlock_irqrestore(shost->host_lock, flags); 456 457 blk_run_queue(q); 458} 459 460/* 461 * Function: scsi_requeue_command() 462 * 463 * Purpose: Handle post-processing of completed commands. 464 * 465 * Arguments: q - queue to operate on 466 * cmd - command that may need to be requeued. 467 * 468 * Returns: Nothing 469 * 470 * Notes: After command completion, there may be blocks left 471 * over which weren't finished by the previous command 472 * this can be for a number of reasons - the main one is 473 * I/O errors in the middle of the request, in which case 474 * we need to request the blocks that come after the bad 475 * sector. 476 * Notes: Upon return, cmd is a stale pointer. 477 */ 478static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd) 479{ 480 struct request *req = cmd->request; 481 unsigned long flags; 482 483 spin_lock_irqsave(q->queue_lock, flags); 484 scsi_unprep_request(req); 485 blk_requeue_request(q, req); 486 spin_unlock_irqrestore(q->queue_lock, flags); 487 488 scsi_run_queue(q); 489} 490 491void scsi_next_command(struct scsi_cmnd *cmd) 492{ 493 struct scsi_device *sdev = cmd->device; 494 struct request_queue *q = sdev->request_queue; 495 496 /* need to hold a reference on the device before we let go of the cmd */ 497 get_device(&sdev->sdev_gendev); 498 499 scsi_put_command(cmd); 500 scsi_run_queue(q); 501 502 /* ok to remove device now */ 503 put_device(&sdev->sdev_gendev); 504} 505 506void scsi_run_host_queues(struct Scsi_Host *shost) 507{ 508 struct scsi_device *sdev; 509 510 shost_for_each_device(sdev, shost) 511 scsi_run_queue(sdev->request_queue); 512} 513 514static void __scsi_release_buffers(struct scsi_cmnd *, int); 515 516/* 517 * Function: scsi_end_request() 518 * 519 * Purpose: Post-processing of completed commands (usually invoked at end 520 * of upper level post-processing and scsi_io_completion). 521 * 522 * Arguments: cmd - command that is complete. 523 * error - 0 if I/O indicates success, < 0 for I/O error. 524 * bytes - number of bytes of completed I/O 525 * requeue - indicates whether we should requeue leftovers. 526 * 527 * Lock status: Assumed that lock is not held upon entry. 528 * 529 * Returns: cmd if requeue required, NULL otherwise. 530 * 531 * Notes: This is called for block device requests in order to 532 * mark some number of sectors as complete. 533 * 534 * We are guaranteeing that the request queue will be goosed 535 * at some point during this call. 536 * Notes: If cmd was requeued, upon return it will be a stale pointer. 537 */ 538static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int error, 539 int bytes, int requeue) 540{ 541 struct request_queue *q = cmd->device->request_queue; 542 struct request *req = cmd->request; 543 544 /* 545 * If there are blocks left over at the end, set up the command 546 * to queue the remainder of them. 547 */ 548 if (blk_end_request(req, error, bytes)) { 549 /* kill remainder if no retrys */ 550 if (error && scsi_noretry_cmd(cmd)) 551 blk_end_request_all(req, error); 552 else { 553 if (requeue) { 554 /* 555 * Bleah. Leftovers again. Stick the 556 * leftovers in the front of the 557 * queue, and goose the queue again. 558 */ 559 scsi_release_buffers(cmd); 560 scsi_requeue_command(q, cmd); 561 cmd = NULL; 562 } 563 return cmd; 564 } 565 } 566 567 /* 568 * This will goose the queue request function at the end, so we don't 569 * need to worry about launching another command. 570 */ 571 __scsi_release_buffers(cmd, 0); 572 scsi_next_command(cmd); 573 return NULL; 574} 575 576static inline unsigned int scsi_sgtable_index(unsigned short nents) 577{ 578 unsigned int index; 579 580 BUG_ON(nents > SCSI_MAX_SG_SEGMENTS); 581 582 if (nents <= 8) 583 index = 0; 584 else 585 index = get_count_order(nents) - 3; 586 587 return index; 588} 589 590static void scsi_sg_free(struct scatterlist *sgl, unsigned int nents) 591{ 592 struct scsi_host_sg_pool *sgp; 593 594 sgp = scsi_sg_pools + scsi_sgtable_index(nents); 595 mempool_free(sgl, sgp->pool); 596} 597 598static struct scatterlist *scsi_sg_alloc(unsigned int nents, gfp_t gfp_mask) 599{ 600 struct scsi_host_sg_pool *sgp; 601 602 sgp = scsi_sg_pools + scsi_sgtable_index(nents); 603 return mempool_alloc(sgp->pool, gfp_mask); 604} 605 606static int scsi_alloc_sgtable(struct scsi_data_buffer *sdb, int nents, 607 gfp_t gfp_mask) 608{ 609 int ret; 610 611 BUG_ON(!nents); 612 613 ret = __sg_alloc_table(&sdb->table, nents, SCSI_MAX_SG_SEGMENTS, 614 gfp_mask, scsi_sg_alloc); 615 if (unlikely(ret)) 616 __sg_free_table(&sdb->table, SCSI_MAX_SG_SEGMENTS, 617 scsi_sg_free); 618 619 return ret; 620} 621 622static void scsi_free_sgtable(struct scsi_data_buffer *sdb) 623{ 624 __sg_free_table(&sdb->table, SCSI_MAX_SG_SEGMENTS, scsi_sg_free); 625} 626 627static void __scsi_release_buffers(struct scsi_cmnd *cmd, int do_bidi_check) 628{ 629 630 if (cmd->sdb.table.nents) 631 scsi_free_sgtable(&cmd->sdb); 632 633 memset(&cmd->sdb, 0, sizeof(cmd->sdb)); 634 635 if (do_bidi_check && scsi_bidi_cmnd(cmd)) { 636 struct scsi_data_buffer *bidi_sdb = 637 cmd->request->next_rq->special; 638 scsi_free_sgtable(bidi_sdb); 639 kmem_cache_free(scsi_sdb_cache, bidi_sdb); 640 cmd->request->next_rq->special = NULL; 641 } 642 643 if (scsi_prot_sg_count(cmd)) 644 scsi_free_sgtable(cmd->prot_sdb); 645} 646 647/* 648 * Function: scsi_release_buffers() 649 * 650 * Purpose: Completion processing for block device I/O requests. 651 * 652 * Arguments: cmd - command that we are bailing. 653 * 654 * Lock status: Assumed that no lock is held upon entry. 655 * 656 * Returns: Nothing 657 * 658 * Notes: In the event that an upper level driver rejects a 659 * command, we must release resources allocated during 660 * the __init_io() function. Primarily this would involve 661 * the scatter-gather table, and potentially any bounce 662 * buffers. 663 */ 664void scsi_release_buffers(struct scsi_cmnd *cmd) 665{ 666 __scsi_release_buffers(cmd, 1); 667} 668EXPORT_SYMBOL(scsi_release_buffers); 669 670/* 671 * Function: scsi_io_completion() 672 * 673 * Purpose: Completion processing for block device I/O requests. 674 * 675 * Arguments: cmd - command that is finished. 676 * 677 * Lock status: Assumed that no lock is held upon entry. 678 * 679 * Returns: Nothing 680 * 681 * Notes: This function is matched in terms of capabilities to 682 * the function that created the scatter-gather list. 683 * In other words, if there are no bounce buffers 684 * (the normal case for most drivers), we don't need 685 * the logic to deal with cleaning up afterwards. 686 * 687 * We must call scsi_end_request(). This will finish off 688 * the specified number of sectors. If we are done, the 689 * command block will be released and the queue function 690 * will be goosed. If we are not done then we have to 691 * figure out what to do next: 692 * 693 * a) We can call scsi_requeue_command(). The request 694 * will be unprepared and put back on the queue. Then 695 * a new command will be created for it. This should 696 * be used if we made forward progress, or if we want 697 * to switch from READ(10) to READ(6) for example. 698 * 699 * b) We can call scsi_queue_insert(). The request will 700 * be put back on the queue and retried using the same 701 * command as before, possibly after a delay. 702 * 703 * c) We can call blk_end_request() with -EIO to fail 704 * the remainder of the request. 705 */ 706void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes) 707{ 708 int result = cmd->result; 709 struct request_queue *q = cmd->device->request_queue; 710 struct request *req = cmd->request; 711 int error = 0; 712 struct scsi_sense_hdr sshdr; 713 int sense_valid = 0; 714 int sense_deferred = 0; 715 enum {ACTION_FAIL, ACTION_REPREP, ACTION_RETRY, 716 ACTION_DELAYED_RETRY} action; 717 char *description = NULL; 718 719 if (result) { 720 sense_valid = scsi_command_normalize_sense(cmd, &sshdr); 721 if (sense_valid) 722 sense_deferred = scsi_sense_is_deferred(&sshdr); 723 } 724 725 if (req->cmd_type == REQ_TYPE_BLOCK_PC) { /* SG_IO ioctl from block level */ 726 req->errors = result; 727 if (result) { 728 if (sense_valid && req->sense) { 729 /* 730 * SG_IO wants current and deferred errors 731 */ 732 int len = 8 + cmd->sense_buffer[7]; 733 734 if (len > SCSI_SENSE_BUFFERSIZE) 735 len = SCSI_SENSE_BUFFERSIZE; 736 memcpy(req->sense, cmd->sense_buffer, len); 737 req->sense_len = len; 738 } 739 if (!sense_deferred) 740 error = -EIO; 741 } 742 743 req->resid_len = scsi_get_resid(cmd); 744 745 if (scsi_bidi_cmnd(cmd)) { 746 /* 747 * Bidi commands Must be complete as a whole, 748 * both sides at once. 749 */ 750 req->next_rq->resid_len = scsi_in(cmd)->resid; 751 752 scsi_release_buffers(cmd); 753 blk_end_request_all(req, 0); 754 755 scsi_next_command(cmd); 756 return; 757 } 758 } 759 760 /* no bidi support for !REQ_TYPE_BLOCK_PC yet */ 761 BUG_ON(blk_bidi_rq(req)); 762 763 /* 764 * Next deal with any sectors which we were able to correctly 765 * handle. 766 */ 767 SCSI_LOG_HLCOMPLETE(1, printk("%u sectors total, " 768 "%d bytes done.\n", 769 blk_rq_sectors(req), good_bytes)); 770 771 /* 772 * Recovered errors need reporting, but they're always treated 773 * as success, so fiddle the result code here. For BLOCK_PC 774 * we already took a copy of the original into rq->errors which 775 * is what gets returned to the user 776 */ 777 if (sense_valid && (sshdr.sense_key == RECOVERED_ERROR)) { 778 /* if ATA PASS-THROUGH INFORMATION AVAILABLE skip 779 * print since caller wants ATA registers. Only occurs on 780 * SCSI ATA PASS_THROUGH commands when CK_COND=1 781 */ 782 if ((sshdr.asc == 0x0) && (sshdr.ascq == 0x1d)) 783 ; 784 else if (!(req->cmd_flags & REQ_QUIET)) 785 scsi_print_sense("", cmd); 786 result = 0; 787 /* BLOCK_PC may have set error */ 788 error = 0; 789 } 790 791 /* 792 * A number of bytes were successfully read. If there 793 * are leftovers and there is some kind of error 794 * (result != 0), retry the rest. 795 */ 796 if (scsi_end_request(cmd, error, good_bytes, result == 0) == NULL) 797 return; 798 799 error = -EIO; 800 801 if (host_byte(result) == DID_RESET) { 802 /* Third party bus reset or reset for error recovery 803 * reasons. Just retry the command and see what 804 * happens. 805 */ 806 action = ACTION_RETRY; 807 } else if (sense_valid && !sense_deferred) { 808 switch (sshdr.sense_key) { 809 case UNIT_ATTENTION: 810 if (cmd->device->removable) { 811 /* Detected disc change. Set a bit 812 * and quietly refuse further access. 813 */ 814 cmd->device->changed = 1; 815 description = "Media Changed"; 816 action = ACTION_FAIL; 817 } else { 818 /* Must have been a power glitch, or a 819 * bus reset. Could not have been a 820 * media change, so we just retry the 821 * command and see what happens. 822 */ 823 action = ACTION_RETRY; 824 } 825 break; 826 case ILLEGAL_REQUEST: 827 /* If we had an ILLEGAL REQUEST returned, then 828 * we may have performed an unsupported 829 * command. The only thing this should be 830 * would be a ten byte read where only a six 831 * byte read was supported. Also, on a system 832 * where READ CAPACITY failed, we may have 833 * read past the end of the disk. 834 */ 835 if ((cmd->device->use_10_for_rw && 836 sshdr.asc == 0x20 && sshdr.ascq == 0x00) && 837 (cmd->cmnd[0] == READ_10 || 838 cmd->cmnd[0] == WRITE_10)) { 839 /* This will issue a new 6-byte command. */ 840 cmd->device->use_10_for_rw = 0; 841 action = ACTION_REPREP; 842 } else if (sshdr.asc == 0x10) /* DIX */ { 843 description = "Host Data Integrity Failure"; 844 action = ACTION_FAIL; 845 error = -EILSEQ; 846 } else 847 action = ACTION_FAIL; 848 break; 849 case ABORTED_COMMAND: 850 action = ACTION_FAIL; 851 if (sshdr.asc == 0x10) { /* DIF */ 852 description = "Target Data Integrity Failure"; 853 error = -EILSEQ; 854 } 855 break; 856 case NOT_READY: 857 /* If the device is in the process of becoming 858 * ready, or has a temporary blockage, retry. 859 */ 860 if (sshdr.asc == 0x04) { 861 switch (sshdr.ascq) { 862 case 0x01: /* becoming ready */ 863 case 0x04: /* format in progress */ 864 case 0x05: /* rebuild in progress */ 865 case 0x06: /* recalculation in progress */ 866 case 0x07: /* operation in progress */ 867 case 0x08: /* Long write in progress */ 868 case 0x09: /* self test in progress */ 869 case 0x14: /* space allocation in progress */ 870 action = ACTION_DELAYED_RETRY; 871 break; 872 default: 873 description = "Device not ready"; 874 action = ACTION_FAIL; 875 break; 876 } 877 } else { 878 description = "Device not ready"; 879 action = ACTION_FAIL; 880 } 881 break; 882 case VOLUME_OVERFLOW: 883 /* See SSC3rXX or current. */ 884 action = ACTION_FAIL; 885 break; 886 default: 887 description = "Unhandled sense code"; 888 action = ACTION_FAIL; 889 break; 890 } 891 } else { 892 description = "Unhandled error code"; 893 action = ACTION_FAIL; 894 } 895 896 switch (action) { 897 case ACTION_FAIL: 898 /* Give up and fail the remainder of the request */ 899 scsi_release_buffers(cmd); 900 if (!(req->cmd_flags & REQ_QUIET)) { 901 if (description) 902 scmd_printk(KERN_INFO, cmd, "%s\n", 903 description); 904 scsi_print_result(cmd); 905 if (driver_byte(result) & DRIVER_SENSE) 906 scsi_print_sense("", cmd); 907 scsi_print_command(cmd); 908 } 909 if (blk_end_request_err(req, error)) 910 scsi_requeue_command(q, cmd); 911 else 912 scsi_next_command(cmd); 913 break; 914 case ACTION_REPREP: 915 /* Unprep the request and put it back at the head of the queue. 916 * A new command will be prepared and issued. 917 */ 918 scsi_release_buffers(cmd); 919 scsi_requeue_command(q, cmd); 920 break; 921 case ACTION_RETRY: 922 /* Retry the same command immediately */ 923 __scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY, 0); 924 break; 925 case ACTION_DELAYED_RETRY: 926 /* Retry the same command after a delay */ 927 __scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY, 0); 928 break; 929 } 930} 931 932static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb, 933 gfp_t gfp_mask) 934{ 935 int count; 936 937 /* 938 * If sg table allocation fails, requeue request later. 939 */ 940 if (unlikely(scsi_alloc_sgtable(sdb, req->nr_phys_segments, 941 gfp_mask))) { 942 return BLKPREP_DEFER; 943 } 944 945 req->buffer = NULL; 946 947 /* 948 * Next, walk the list, and fill in the addresses and sizes of 949 * each segment. 950 */ 951 count = blk_rq_map_sg(req->q, req, sdb->table.sgl); 952 BUG_ON(count > sdb->table.nents); 953 sdb->table.nents = count; 954 sdb->length = blk_rq_bytes(req); 955 return BLKPREP_OK; 956} 957 958/* 959 * Function: scsi_init_io() 960 * 961 * Purpose: SCSI I/O initialize function. 962 * 963 * Arguments: cmd - Command descriptor we wish to initialize 964 * 965 * Returns: 0 on success 966 * BLKPREP_DEFER if the failure is retryable 967 * BLKPREP_KILL if the failure is fatal 968 */ 969int scsi_init_io(struct scsi_cmnd *cmd, gfp_t gfp_mask) 970{ 971 struct request *rq = cmd->request; 972 973 int error = scsi_init_sgtable(rq, &cmd->sdb, gfp_mask); 974 if (error) 975 goto err_exit; 976 977 if (blk_bidi_rq(rq)) { 978 struct scsi_data_buffer *bidi_sdb = kmem_cache_zalloc( 979 scsi_sdb_cache, GFP_ATOMIC); 980 if (!bidi_sdb) { 981 error = BLKPREP_DEFER; 982 goto err_exit; 983 } 984 985 rq->next_rq->special = bidi_sdb; 986 error = scsi_init_sgtable(rq->next_rq, bidi_sdb, GFP_ATOMIC); 987 if (error) 988 goto err_exit; 989 } 990 991 if (blk_integrity_rq(rq)) { 992 struct scsi_data_buffer *prot_sdb = cmd->prot_sdb; 993 int ivecs, count; 994 995 BUG_ON(prot_sdb == NULL); 996 ivecs = blk_rq_count_integrity_sg(rq->q, rq->bio); 997 998 if (scsi_alloc_sgtable(prot_sdb, ivecs, gfp_mask)) { 999 error = BLKPREP_DEFER; 1000 goto err_exit; 1001 } 1002 1003 count = blk_rq_map_integrity_sg(rq->q, rq->bio, 1004 prot_sdb->table.sgl); 1005 BUG_ON(unlikely(count > ivecs)); 1006 BUG_ON(unlikely(count > queue_max_integrity_segments(rq->q))); 1007 1008 cmd->prot_sdb = prot_sdb; 1009 cmd->prot_sdb->table.nents = count; 1010 } 1011 1012 return BLKPREP_OK ; 1013 1014err_exit: 1015 scsi_release_buffers(cmd); 1016 cmd->request->special = NULL; 1017 scsi_put_command(cmd); 1018 return error; 1019} 1020EXPORT_SYMBOL(scsi_init_io); 1021 1022static struct scsi_cmnd *scsi_get_cmd_from_req(struct scsi_device *sdev, 1023 struct request *req) 1024{ 1025 struct scsi_cmnd *cmd; 1026 1027 if (!req->special) { 1028 cmd = scsi_get_command(sdev, GFP_ATOMIC); 1029 if (unlikely(!cmd)) 1030 return NULL; 1031 req->special = cmd; 1032 } else { 1033 cmd = req->special; 1034 } 1035 1036 /* pull a tag out of the request if we have one */ 1037 cmd->tag = req->tag; 1038 cmd->request = req; 1039 1040 cmd->cmnd = req->cmd; 1041 1042 return cmd; 1043} 1044 1045int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req) 1046{ 1047 struct scsi_cmnd *cmd; 1048 int ret = scsi_prep_state_check(sdev, req); 1049 1050 if (ret != BLKPREP_OK) 1051 return ret; 1052 1053 cmd = scsi_get_cmd_from_req(sdev, req); 1054 if (unlikely(!cmd)) 1055 return BLKPREP_DEFER; 1056 1057 /* 1058 * BLOCK_PC requests may transfer data, in which case they must 1059 * a bio attached to them. Or they might contain a SCSI command 1060 * that does not transfer data, in which case they may optionally 1061 * submit a request without an attached bio. 1062 */ 1063 if (req->bio) { 1064 int ret; 1065 1066 BUG_ON(!req->nr_phys_segments); 1067 1068 ret = scsi_init_io(cmd, GFP_ATOMIC); 1069 if (unlikely(ret)) 1070 return ret; 1071 } else { 1072 BUG_ON(blk_rq_bytes(req)); 1073 1074 memset(&cmd->sdb, 0, sizeof(cmd->sdb)); 1075 req->buffer = NULL; 1076 } 1077 1078 cmd->cmd_len = req->cmd_len; 1079 if (!blk_rq_bytes(req)) 1080 cmd->sc_data_direction = DMA_NONE; 1081 else if (rq_data_dir(req) == WRITE) 1082 cmd->sc_data_direction = DMA_TO_DEVICE; 1083 else 1084 cmd->sc_data_direction = DMA_FROM_DEVICE; 1085 1086 cmd->transfersize = blk_rq_bytes(req); 1087 cmd->allowed = req->retries; 1088 return BLKPREP_OK; 1089} 1090EXPORT_SYMBOL(scsi_setup_blk_pc_cmnd); 1091 1092/* 1093 * Setup a REQ_TYPE_FS command. These are simple read/write request 1094 * from filesystems that still need to be translated to SCSI CDBs from 1095 * the ULD. 1096 */ 1097int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct request *req) 1098{ 1099 struct scsi_cmnd *cmd; 1100 int ret = scsi_prep_state_check(sdev, req); 1101 1102 if (ret != BLKPREP_OK) 1103 return ret; 1104 1105 if (unlikely(sdev->scsi_dh_data && sdev->scsi_dh_data->scsi_dh 1106 && sdev->scsi_dh_data->scsi_dh->prep_fn)) { 1107 ret = sdev->scsi_dh_data->scsi_dh->prep_fn(sdev, req); 1108 if (ret != BLKPREP_OK) 1109 return ret; 1110 } 1111 1112 /* 1113 * Filesystem requests must transfer data. 1114 */ 1115 BUG_ON(!req->nr_phys_segments); 1116 1117 cmd = scsi_get_cmd_from_req(sdev, req); 1118 if (unlikely(!cmd)) 1119 return BLKPREP_DEFER; 1120 1121 memset(cmd->cmnd, 0, BLK_MAX_CDB); 1122 return scsi_init_io(cmd, GFP_ATOMIC); 1123} 1124EXPORT_SYMBOL(scsi_setup_fs_cmnd); 1125 1126int scsi_prep_state_check(struct scsi_device *sdev, struct request *req) 1127{ 1128 int ret = BLKPREP_OK; 1129 1130 /* 1131 * If the device is not in running state we will reject some 1132 * or all commands. 1133 */ 1134 if (unlikely(sdev->sdev_state != SDEV_RUNNING)) { 1135 switch (sdev->sdev_state) { 1136 case SDEV_OFFLINE: 1137 /* 1138 * If the device is offline we refuse to process any 1139 * commands. The device must be brought online 1140 * before trying any recovery commands. 1141 */ 1142 sdev_printk(KERN_ERR, sdev, 1143 "rejecting I/O to offline device\n"); 1144 ret = BLKPREP_KILL; 1145 break; 1146 case SDEV_DEL: 1147 /* 1148 * If the device is fully deleted, we refuse to 1149 * process any commands as well. 1150 */ 1151 sdev_printk(KERN_ERR, sdev, 1152 "rejecting I/O to dead device\n"); 1153 ret = BLKPREP_KILL; 1154 break; 1155 case SDEV_QUIESCE: 1156 case SDEV_BLOCK: 1157 case SDEV_CREATED_BLOCK: 1158 /* 1159 * If the devices is blocked we defer normal commands. 1160 */ 1161 if (!(req->cmd_flags & REQ_PREEMPT)) 1162 ret = BLKPREP_DEFER; 1163 break; 1164 default: 1165 /* 1166 * For any other not fully online state we only allow 1167 * special commands. In particular any user initiated 1168 * command is not allowed. 1169 */ 1170 if (!(req->cmd_flags & REQ_PREEMPT)) 1171 ret = BLKPREP_KILL; 1172 break; 1173 } 1174 } 1175 return ret; 1176} 1177EXPORT_SYMBOL(scsi_prep_state_check); 1178 1179int scsi_prep_return(struct request_queue *q, struct request *req, int ret) 1180{ 1181 struct scsi_device *sdev = q->queuedata; 1182 1183 switch (ret) { 1184 case BLKPREP_KILL: 1185 req->errors = DID_NO_CONNECT << 16; 1186 /* release the command and kill it */ 1187 if (req->special) { 1188 struct scsi_cmnd *cmd = req->special; 1189 scsi_release_buffers(cmd); 1190 scsi_put_command(cmd); 1191 req->special = NULL; 1192 } 1193 break; 1194 case BLKPREP_DEFER: 1195 /* 1196 * If we defer, the blk_peek_request() returns NULL, but the 1197 * queue must be restarted, so we plug here if no returning 1198 * command will automatically do that. 1199 */ 1200 if (sdev->device_busy == 0) 1201 blk_plug_device(q); 1202 break; 1203 default: 1204 req->cmd_flags |= REQ_DONTPREP; 1205 } 1206 1207 return ret; 1208} 1209EXPORT_SYMBOL(scsi_prep_return); 1210 1211int scsi_prep_fn(struct request_queue *q, struct request *req) 1212{ 1213 struct scsi_device *sdev = q->queuedata; 1214 int ret = BLKPREP_KILL; 1215 1216 if (req->cmd_type == REQ_TYPE_BLOCK_PC) 1217 ret = scsi_setup_blk_pc_cmnd(sdev, req); 1218 return scsi_prep_return(q, req, ret); 1219} 1220EXPORT_SYMBOL(scsi_prep_fn); 1221 1222/* 1223 * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else 1224 * return 0. 1225 * 1226 * Called with the queue_lock held. 1227 */ 1228static inline int scsi_dev_queue_ready(struct request_queue *q, 1229 struct scsi_device *sdev) 1230{ 1231 if (sdev->device_busy == 0 && sdev->device_blocked) { 1232 /* 1233 * unblock after device_blocked iterates to zero 1234 */ 1235 if (--sdev->device_blocked == 0) { 1236 SCSI_LOG_MLQUEUE(3, 1237 sdev_printk(KERN_INFO, sdev, 1238 "unblocking device at zero depth\n")); 1239 } else { 1240 blk_plug_device(q); 1241 return 0; 1242 } 1243 } 1244 if (scsi_device_is_busy(sdev)) 1245 return 0; 1246 1247 return 1; 1248} 1249 1250 1251/* 1252 * scsi_target_queue_ready: checks if there we can send commands to target 1253 * @sdev: scsi device on starget to check. 1254 * 1255 * Called with the host lock held. 1256 */ 1257static inline int scsi_target_queue_ready(struct Scsi_Host *shost, 1258 struct scsi_device *sdev) 1259{ 1260 struct scsi_target *starget = scsi_target(sdev); 1261 1262 if (starget->single_lun) { 1263 if (starget->starget_sdev_user && 1264 starget->starget_sdev_user != sdev) 1265 return 0; 1266 starget->starget_sdev_user = sdev; 1267 } 1268 1269 if (starget->target_busy == 0 && starget->target_blocked) { 1270 /* 1271 * unblock after target_blocked iterates to zero 1272 */ 1273 if (--starget->target_blocked == 0) { 1274 SCSI_LOG_MLQUEUE(3, starget_printk(KERN_INFO, starget, 1275 "unblocking target at zero depth\n")); 1276 } else 1277 return 0; 1278 } 1279 1280 if (scsi_target_is_busy(starget)) { 1281 if (list_empty(&sdev->starved_entry)) { 1282 list_add_tail(&sdev->starved_entry, 1283 &shost->starved_list); 1284 return 0; 1285 } 1286 } 1287 1288 /* We're OK to process the command, so we can't be starved */ 1289 if (!list_empty(&sdev->starved_entry)) 1290 list_del_init(&sdev->starved_entry); 1291 return 1; 1292} 1293 1294/* 1295 * scsi_host_queue_ready: if we can send requests to shost, return 1 else 1296 * return 0. We must end up running the queue again whenever 0 is 1297 * returned, else IO can hang. 1298 * 1299 * Called with host_lock held. 1300 */ 1301static inline int scsi_host_queue_ready(struct request_queue *q, 1302 struct Scsi_Host *shost, 1303 struct scsi_device *sdev) 1304{ 1305 if (scsi_host_in_recovery(shost)) 1306 return 0; 1307 if (shost->host_busy == 0 && shost->host_blocked) { 1308 /* 1309 * unblock after host_blocked iterates to zero 1310 */ 1311 if (--shost->host_blocked == 0) { 1312 SCSI_LOG_MLQUEUE(3, 1313 printk("scsi%d unblocking host at zero depth\n", 1314 shost->host_no)); 1315 } else { 1316 return 0; 1317 } 1318 } 1319 if (scsi_host_is_busy(shost)) { 1320 if (list_empty(&sdev->starved_entry)) 1321 list_add_tail(&sdev->starved_entry, &shost->starved_list); 1322 return 0; 1323 } 1324 1325 /* We're OK to process the command, so we can't be starved */ 1326 if (!list_empty(&sdev->starved_entry)) 1327 list_del_init(&sdev->starved_entry); 1328 1329 return 1; 1330} 1331 1332/* 1333 * Busy state exporting function for request stacking drivers. 1334 * 1335 * For efficiency, no lock is taken to check the busy state of 1336 * shost/starget/sdev, since the returned value is not guaranteed and 1337 * may be changed after request stacking drivers call the function, 1338 * regardless of taking lock or not. 1339 * 1340 * When scsi can't dispatch I/Os anymore and needs to kill I/Os 1341 * (e.g. !sdev), scsi needs to return 'not busy'. 1342 * Otherwise, request stacking drivers may hold requests forever. 1343 */ 1344static int scsi_lld_busy(struct request_queue *q) 1345{ 1346 struct scsi_device *sdev = q->queuedata; 1347 struct Scsi_Host *shost; 1348 struct scsi_target *starget; 1349 1350 if (!sdev) 1351 return 0; 1352 1353 shost = sdev->host; 1354 starget = scsi_target(sdev); 1355 1356 if (scsi_host_in_recovery(shost) || scsi_host_is_busy(shost) || 1357 scsi_target_is_busy(starget) || scsi_device_is_busy(sdev)) 1358 return 1; 1359 1360 return 0; 1361} 1362 1363/* 1364 * Kill a request for a dead device 1365 */ 1366static void scsi_kill_request(struct request *req, struct request_queue *q) 1367{ 1368 struct scsi_cmnd *cmd = req->special; 1369 struct scsi_device *sdev; 1370 struct scsi_target *starget; 1371 struct Scsi_Host *shost; 1372 1373 blk_start_request(req); 1374 1375 sdev = cmd->device; 1376 starget = scsi_target(sdev); 1377 shost = sdev->host; 1378 scsi_init_cmd_errh(cmd); 1379 cmd->result = DID_NO_CONNECT << 16; 1380 atomic_inc(&cmd->device->iorequest_cnt); 1381 1382 /* 1383 * SCSI request completion path will do scsi_device_unbusy(), 1384 * bump busy counts. To bump the counters, we need to dance 1385 * with the locks as normal issue path does. 1386 */ 1387 sdev->device_busy++; 1388 spin_unlock(sdev->request_queue->queue_lock); 1389 spin_lock(shost->host_lock); 1390 shost->host_busy++; 1391 starget->target_busy++; 1392 spin_unlock(shost->host_lock); 1393 spin_lock(sdev->request_queue->queue_lock); 1394 1395 blk_complete_request(req); 1396} 1397 1398static void scsi_softirq_done(struct request *rq) 1399{ 1400 struct scsi_cmnd *cmd = rq->special; 1401 unsigned long wait_for = (cmd->allowed + 1) * rq->timeout; 1402 int disposition; 1403 1404 INIT_LIST_HEAD(&cmd->eh_entry); 1405 1406 /* 1407 * Set the serial numbers back to zero 1408 */ 1409 cmd->serial_number = 0; 1410 1411 atomic_inc(&cmd->device->iodone_cnt); 1412 if (cmd->result) 1413 atomic_inc(&cmd->device->ioerr_cnt); 1414 1415 disposition = scsi_decide_disposition(cmd); 1416 if (disposition != SUCCESS && 1417 time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) { 1418 sdev_printk(KERN_ERR, cmd->device, 1419 "timing out command, waited %lus\n", 1420 wait_for/HZ); 1421 disposition = SUCCESS; 1422 } 1423 1424 scsi_log_completion(cmd, disposition); 1425 1426 switch (disposition) { 1427 case SUCCESS: 1428 scsi_finish_command(cmd); 1429 break; 1430 case NEEDS_RETRY: 1431 scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY); 1432 break; 1433 case ADD_TO_MLQUEUE: 1434 scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY); 1435 break; 1436 default: 1437 if (!scsi_eh_scmd_add(cmd, 0)) 1438 scsi_finish_command(cmd); 1439 } 1440} 1441 1442/* 1443 * Function: scsi_request_fn() 1444 * 1445 * Purpose: Main strategy routine for SCSI. 1446 * 1447 * Arguments: q - Pointer to actual queue. 1448 * 1449 * Returns: Nothing 1450 * 1451 * Lock status: IO request lock assumed to be held when called. 1452 */ 1453static void scsi_request_fn(struct request_queue *q) 1454{ 1455 struct scsi_device *sdev = q->queuedata; 1456 struct Scsi_Host *shost; 1457 struct scsi_cmnd *cmd; 1458 struct request *req; 1459 1460 if (!sdev) { 1461 printk("scsi: killing requests for dead queue\n"); 1462 while ((req = blk_peek_request(q)) != NULL) 1463 scsi_kill_request(req, q); 1464 return; 1465 } 1466 1467 if(!get_device(&sdev->sdev_gendev)) 1468 /* We must be tearing the block queue down already */ 1469 return; 1470 1471 /* 1472 * To start with, we keep looping until the queue is empty, or until 1473 * the host is no longer able to accept any more requests. 1474 */ 1475 shost = sdev->host; 1476 while (!blk_queue_plugged(q)) { 1477 int rtn; 1478 /* 1479 * get next queueable request. We do this early to make sure 1480 * that the request is fully prepared even if we cannot 1481 * accept it. 1482 */ 1483 req = blk_peek_request(q); 1484 if (!req || !scsi_dev_queue_ready(q, sdev)) 1485 break; 1486 1487 if (unlikely(!scsi_device_online(sdev))) { 1488 sdev_printk(KERN_ERR, sdev, 1489 "rejecting I/O to offline device\n"); 1490 scsi_kill_request(req, q); 1491 continue; 1492 } 1493 1494 1495 /* 1496 * Remove the request from the request list. 1497 */ 1498 if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req))) 1499 blk_start_request(req); 1500 sdev->device_busy++; 1501 1502 spin_unlock(q->queue_lock); 1503 cmd = req->special; 1504 if (unlikely(cmd == NULL)) { 1505 printk(KERN_CRIT "impossible request in %s.\n" 1506 "please mail a stack trace to " 1507 "linux-scsi@vger.kernel.org\n", 1508 __func__); 1509 blk_dump_rq_flags(req, "foo"); 1510 BUG(); 1511 } 1512 spin_lock(shost->host_lock); 1513 1514 /* 1515 * We hit this when the driver is using a host wide 1516 * tag map. For device level tag maps the queue_depth check 1517 * in the device ready fn would prevent us from trying 1518 * to allocate a tag. Since the map is a shared host resource 1519 * we add the dev to the starved list so it eventually gets 1520 * a run when a tag is freed. 1521 */ 1522 if (blk_queue_tagged(q) && !blk_rq_tagged(req)) { 1523 if (list_empty(&sdev->starved_entry)) 1524 list_add_tail(&sdev->starved_entry, 1525 &shost->starved_list); 1526 goto not_ready; 1527 } 1528 1529 if (!scsi_target_queue_ready(shost, sdev)) 1530 goto not_ready; 1531 1532 if (!scsi_host_queue_ready(q, shost, sdev)) 1533 goto not_ready; 1534 1535 scsi_target(sdev)->target_busy++; 1536 shost->host_busy++; 1537 1538 /* 1539 * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will 1540 * take the lock again. 1541 */ 1542 spin_unlock_irq(shost->host_lock); 1543 1544 /* 1545 * Finally, initialize any error handling parameters, and set up 1546 * the timers for timeouts. 1547 */ 1548 scsi_init_cmd_errh(cmd); 1549 1550 /* 1551 * Dispatch the command to the low-level driver. 1552 */ 1553 rtn = scsi_dispatch_cmd(cmd); 1554 spin_lock_irq(q->queue_lock); 1555 if(rtn) { 1556 /* we're refusing the command; because of 1557 * the way locks get dropped, we need to 1558 * check here if plugging is required */ 1559 if(sdev->device_busy == 0) 1560 blk_plug_device(q); 1561 1562 break; 1563 } 1564 } 1565 1566 goto out; 1567 1568 not_ready: 1569 spin_unlock_irq(shost->host_lock); 1570 1571 /* 1572 * lock q, handle tag, requeue req, and decrement device_busy. We 1573 * must return with queue_lock held. 1574 * 1575 * Decrementing device_busy without checking it is OK, as all such 1576 * cases (host limits or settings) should run the queue at some 1577 * later time. 1578 */ 1579 spin_lock_irq(q->queue_lock); 1580 blk_requeue_request(q, req); 1581 sdev->device_busy--; 1582 if(sdev->device_busy == 0) 1583 blk_plug_device(q); 1584 out: 1585 /* must be careful here...if we trigger the ->remove() function 1586 * we cannot be holding the q lock */ 1587 spin_unlock_irq(q->queue_lock); 1588 put_device(&sdev->sdev_gendev); 1589 spin_lock_irq(q->queue_lock); 1590} 1591 1592u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost) 1593{ 1594 struct device *host_dev; 1595 u64 bounce_limit = 0xffffffff; 1596 1597 if (shost->unchecked_isa_dma) 1598 return BLK_BOUNCE_ISA; 1599 /* 1600 * Platforms with virtual-DMA translation 1601 * hardware have no practical limit. 1602 */ 1603 if (!PCI_DMA_BUS_IS_PHYS) 1604 return BLK_BOUNCE_ANY; 1605 1606 host_dev = scsi_get_device(shost); 1607 if (host_dev && host_dev->dma_mask) 1608 bounce_limit = *host_dev->dma_mask; 1609 1610 return bounce_limit; 1611} 1612EXPORT_SYMBOL(scsi_calculate_bounce_limit); 1613 1614struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost, 1615 request_fn_proc *request_fn) 1616{ 1617 struct request_queue *q; 1618 struct device *dev = shost->shost_gendev.parent; 1619 1620 q = blk_init_queue(request_fn, NULL); 1621 if (!q) 1622 return NULL; 1623 1624 /* 1625 * this limit is imposed by hardware restrictions 1626 */ 1627 blk_queue_max_segments(q, min_t(unsigned short, shost->sg_tablesize, 1628 SCSI_MAX_SG_CHAIN_SEGMENTS)); 1629 1630 if (scsi_host_prot_dma(shost)) { 1631 shost->sg_prot_tablesize = 1632 min_not_zero(shost->sg_prot_tablesize, 1633 (unsigned short)SCSI_MAX_PROT_SG_SEGMENTS); 1634 BUG_ON(shost->sg_prot_tablesize < shost->sg_tablesize); 1635 blk_queue_max_integrity_segments(q, shost->sg_prot_tablesize); 1636 } 1637 1638 blk_queue_max_hw_sectors(q, shost->max_sectors); 1639 blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost)); 1640 blk_queue_segment_boundary(q, shost->dma_boundary); 1641 dma_set_seg_boundary(dev, shost->dma_boundary); 1642 1643 blk_queue_max_segment_size(q, dma_get_max_seg_size(dev)); 1644 1645 /* New queue, no concurrency on queue_flags */ 1646 if (!shost->use_clustering) 1647 queue_flag_clear_unlocked(QUEUE_FLAG_CLUSTER, q); 1648 1649 /* 1650 * set a reasonable default alignment on word boundaries: the 1651 * host and device may alter it using 1652 * blk_queue_update_dma_alignment() later. 1653 */ 1654 blk_queue_dma_alignment(q, 0x03); 1655 1656 return q; 1657} 1658EXPORT_SYMBOL(__scsi_alloc_queue); 1659 1660struct request_queue *scsi_alloc_queue(struct scsi_device *sdev) 1661{ 1662 struct request_queue *q; 1663 1664 q = __scsi_alloc_queue(sdev->host, scsi_request_fn); 1665 if (!q) 1666 return NULL; 1667 1668 blk_queue_prep_rq(q, scsi_prep_fn); 1669 blk_queue_softirq_done(q, scsi_softirq_done); 1670 blk_queue_rq_timed_out(q, scsi_times_out); 1671 blk_queue_lld_busy(q, scsi_lld_busy); 1672 return q; 1673} 1674 1675void scsi_free_queue(struct request_queue *q) 1676{ 1677 blk_cleanup_queue(q); 1678} 1679 1680/* 1681 * Function: scsi_block_requests() 1682 * 1683 * Purpose: Utility function used by low-level drivers to prevent further 1684 * commands from being queued to the device. 1685 * 1686 * Arguments: shost - Host in question 1687 * 1688 * Returns: Nothing 1689 * 1690 * Lock status: No locks are assumed held. 1691 * 1692 * Notes: There is no timer nor any other means by which the requests 1693 * get unblocked other than the low-level driver calling 1694 * scsi_unblock_requests(). 1695 */ 1696void scsi_block_requests(struct Scsi_Host *shost) 1697{ 1698 shost->host_self_blocked = 1; 1699} 1700EXPORT_SYMBOL(scsi_block_requests); 1701 1702/* 1703 * Function: scsi_unblock_requests() 1704 * 1705 * Purpose: Utility function used by low-level drivers to allow further 1706 * commands from being queued to the device. 1707 * 1708 * Arguments: shost - Host in question 1709 * 1710 * Returns: Nothing 1711 * 1712 * Lock status: No locks are assumed held. 1713 * 1714 * Notes: There is no timer nor any other means by which the requests 1715 * get unblocked other than the low-level driver calling 1716 * scsi_unblock_requests(). 1717 * 1718 * This is done as an API function so that changes to the 1719 * internals of the scsi mid-layer won't require wholesale 1720 * changes to drivers that use this feature. 1721 */ 1722void scsi_unblock_requests(struct Scsi_Host *shost) 1723{ 1724 shost->host_self_blocked = 0; 1725 scsi_run_host_queues(shost); 1726} 1727EXPORT_SYMBOL(scsi_unblock_requests); 1728 1729int __init scsi_init_queue(void) 1730{ 1731 int i; 1732 1733 scsi_sdb_cache = kmem_cache_create("scsi_data_buffer", 1734 sizeof(struct scsi_data_buffer), 1735 0, 0, NULL); 1736 if (!scsi_sdb_cache) { 1737 printk(KERN_ERR "SCSI: can't init scsi sdb cache\n"); 1738 return -ENOMEM; 1739 } 1740 1741 for (i = 0; i < SG_MEMPOOL_NR; i++) { 1742 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i; 1743 int size = sgp->size * sizeof(struct scatterlist); 1744 1745 sgp->slab = kmem_cache_create(sgp->name, size, 0, 1746 SLAB_HWCACHE_ALIGN, NULL); 1747 if (!sgp->slab) { 1748 printk(KERN_ERR "SCSI: can't init sg slab %s\n", 1749 sgp->name); 1750 goto cleanup_sdb; 1751 } 1752 1753 sgp->pool = mempool_create_slab_pool(SG_MEMPOOL_SIZE, 1754 sgp->slab); 1755 if (!sgp->pool) { 1756 printk(KERN_ERR "SCSI: can't init sg mempool %s\n", 1757 sgp->name); 1758 goto cleanup_sdb; 1759 } 1760 } 1761 1762 return 0; 1763 1764cleanup_sdb: 1765 for (i = 0; i < SG_MEMPOOL_NR; i++) { 1766 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i; 1767 if (sgp->pool) 1768 mempool_destroy(sgp->pool); 1769 if (sgp->slab) 1770 kmem_cache_destroy(sgp->slab); 1771 } 1772 kmem_cache_destroy(scsi_sdb_cache); 1773 1774 return -ENOMEM; 1775} 1776 1777void scsi_exit_queue(void) 1778{ 1779 int i; 1780 1781 kmem_cache_destroy(scsi_sdb_cache); 1782 1783 for (i = 0; i < SG_MEMPOOL_NR; i++) { 1784 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i; 1785 mempool_destroy(sgp->pool); 1786 kmem_cache_destroy(sgp->slab); 1787 } 1788} 1789 1790/** 1791 * scsi_mode_select - issue a mode select 1792 * @sdev: SCSI device to be queried 1793 * @pf: Page format bit (1 == standard, 0 == vendor specific) 1794 * @sp: Save page bit (0 == don't save, 1 == save) 1795 * @modepage: mode page being requested 1796 * @buffer: request buffer (may not be smaller than eight bytes) 1797 * @len: length of request buffer. 1798 * @timeout: command timeout 1799 * @retries: number of retries before failing 1800 * @data: returns a structure abstracting the mode header data 1801 * @sshdr: place to put sense data (or NULL if no sense to be collected). 1802 * must be SCSI_SENSE_BUFFERSIZE big. 1803 * 1804 * Returns zero if successful; negative error number or scsi 1805 * status on error 1806 * 1807 */ 1808int 1809scsi_mode_select(struct scsi_device *sdev, int pf, int sp, int modepage, 1810 unsigned char *buffer, int len, int timeout, int retries, 1811 struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr) 1812{ 1813 unsigned char cmd[10]; 1814 unsigned char *real_buffer; 1815 int ret; 1816 1817 memset(cmd, 0, sizeof(cmd)); 1818 cmd[1] = (pf ? 0x10 : 0) | (sp ? 0x01 : 0); 1819 1820 if (sdev->use_10_for_ms) { 1821 if (len > 65535) 1822 return -EINVAL; 1823 real_buffer = kmalloc(8 + len, GFP_KERNEL); 1824 if (!real_buffer) 1825 return -ENOMEM; 1826 memcpy(real_buffer + 8, buffer, len); 1827 len += 8; 1828 real_buffer[0] = 0; 1829 real_buffer[1] = 0; 1830 real_buffer[2] = data->medium_type; 1831 real_buffer[3] = data->device_specific; 1832 real_buffer[4] = data->longlba ? 0x01 : 0; 1833 real_buffer[5] = 0; 1834 real_buffer[6] = data->block_descriptor_length >> 8; 1835 real_buffer[7] = data->block_descriptor_length; 1836 1837 cmd[0] = MODE_SELECT_10; 1838 cmd[7] = len >> 8; 1839 cmd[8] = len; 1840 } else { 1841 if (len > 255 || data->block_descriptor_length > 255 || 1842 data->longlba) 1843 return -EINVAL; 1844 1845 real_buffer = kmalloc(4 + len, GFP_KERNEL); 1846 if (!real_buffer) 1847 return -ENOMEM; 1848 memcpy(real_buffer + 4, buffer, len); 1849 len += 4; 1850 real_buffer[0] = 0; 1851 real_buffer[1] = data->medium_type; 1852 real_buffer[2] = data->device_specific; 1853 real_buffer[3] = data->block_descriptor_length; 1854 1855 1856 cmd[0] = MODE_SELECT; 1857 cmd[4] = len; 1858 } 1859 1860 ret = scsi_execute_req(sdev, cmd, DMA_TO_DEVICE, real_buffer, len, 1861 sshdr, timeout, retries, NULL); 1862 kfree(real_buffer); 1863 return ret; 1864} 1865EXPORT_SYMBOL_GPL(scsi_mode_select); 1866 1867/** 1868 * scsi_mode_sense - issue a mode sense, falling back from 10 to six bytes if necessary. 1869 * @sdev: SCSI device to be queried 1870 * @dbd: set if mode sense will allow block descriptors to be returned 1871 * @modepage: mode page being requested 1872 * @buffer: request buffer (may not be smaller than eight bytes) 1873 * @len: length of request buffer. 1874 * @timeout: command timeout 1875 * @retries: number of retries before failing 1876 * @data: returns a structure abstracting the mode header data 1877 * @sshdr: place to put sense data (or NULL if no sense to be collected). 1878 * must be SCSI_SENSE_BUFFERSIZE big. 1879 * 1880 * Returns zero if unsuccessful, or the header offset (either 4 1881 * or 8 depending on whether a six or ten byte command was 1882 * issued) if successful. 1883 */ 1884int 1885scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage, 1886 unsigned char *buffer, int len, int timeout, int retries, 1887 struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr) 1888{ 1889 unsigned char cmd[12]; 1890 int use_10_for_ms; 1891 int header_length; 1892 int result; 1893 struct scsi_sense_hdr my_sshdr; 1894 1895 memset(data, 0, sizeof(*data)); 1896 memset(&cmd[0], 0, 12); 1897 cmd[1] = dbd & 0x18; /* allows DBD and LLBA bits */ 1898 cmd[2] = modepage; 1899 1900 /* caller might not be interested in sense, but we need it */ 1901 if (!sshdr) 1902 sshdr = &my_sshdr; 1903 1904 retry: 1905 use_10_for_ms = sdev->use_10_for_ms; 1906 1907 if (use_10_for_ms) { 1908 if (len < 8) 1909 len = 8; 1910 1911 cmd[0] = MODE_SENSE_10; 1912 cmd[8] = len; 1913 header_length = 8; 1914 } else { 1915 if (len < 4) 1916 len = 4; 1917 1918 cmd[0] = MODE_SENSE; 1919 cmd[4] = len; 1920 header_length = 4; 1921 } 1922 1923 memset(buffer, 0, len); 1924 1925 result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len, 1926 sshdr, timeout, retries, NULL); 1927 1928 /* This code looks awful: what it's doing is making sure an 1929 * ILLEGAL REQUEST sense return identifies the actual command 1930 * byte as the problem. MODE_SENSE commands can return 1931 * ILLEGAL REQUEST if the code page isn't supported */ 1932 1933 if (use_10_for_ms && !scsi_status_is_good(result) && 1934 (driver_byte(result) & DRIVER_SENSE)) { 1935 if (scsi_sense_valid(sshdr)) { 1936 if ((sshdr->sense_key == ILLEGAL_REQUEST) && 1937 (sshdr->asc == 0x20) && (sshdr->ascq == 0)) { 1938 /* 1939 * Invalid command operation code 1940 */ 1941 sdev->use_10_for_ms = 0; 1942 goto retry; 1943 } 1944 } 1945 } 1946 1947 if(scsi_status_is_good(result)) { 1948 if (unlikely(buffer[0] == 0x86 && buffer[1] == 0x0b && 1949 (modepage == 6 || modepage == 8))) { 1950 /* Initio breakage? */ 1951 header_length = 0; 1952 data->length = 13; 1953 data->medium_type = 0; 1954 data->device_specific = 0; 1955 data->longlba = 0; 1956 data->block_descriptor_length = 0; 1957 } else if(use_10_for_ms) { 1958 data->length = buffer[0]*256 + buffer[1] + 2; 1959 data->medium_type = buffer[2]; 1960 data->device_specific = buffer[3]; 1961 data->longlba = buffer[4] & 0x01; 1962 data->block_descriptor_length = buffer[6]*256 1963 + buffer[7]; 1964 } else { 1965 data->length = buffer[0] + 1; 1966 data->medium_type = buffer[1]; 1967 data->device_specific = buffer[2]; 1968 data->block_descriptor_length = buffer[3]; 1969 } 1970 data->header_length = header_length; 1971 } 1972 1973 return result; 1974} 1975EXPORT_SYMBOL(scsi_mode_sense); 1976 1977/** 1978 * scsi_test_unit_ready - test if unit is ready 1979 * @sdev: scsi device to change the state of. 1980 * @timeout: command timeout 1981 * @retries: number of retries before failing 1982 * @sshdr_external: Optional pointer to struct scsi_sense_hdr for 1983 * returning sense. Make sure that this is cleared before passing 1984 * in. 1985 * 1986 * Returns zero if unsuccessful or an error if TUR failed. For 1987 * removable media, a return of NOT_READY or UNIT_ATTENTION is 1988 * translated to success, with the ->changed flag updated. 1989 **/ 1990int 1991scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries, 1992 struct scsi_sense_hdr *sshdr_external) 1993{ 1994 char cmd[] = { 1995 TEST_UNIT_READY, 0, 0, 0, 0, 0, 1996 }; 1997 struct scsi_sense_hdr *sshdr; 1998 int result; 1999 2000 if (!sshdr_external) 2001 sshdr = kzalloc(sizeof(*sshdr), GFP_KERNEL); 2002 else 2003 sshdr = sshdr_external; 2004 2005 /* try to eat the UNIT_ATTENTION if there are enough retries */ 2006 do { 2007 result = scsi_execute_req(sdev, cmd, DMA_NONE, NULL, 0, sshdr, 2008 timeout, retries, NULL); 2009 if (sdev->removable && scsi_sense_valid(sshdr) && 2010 sshdr->sense_key == UNIT_ATTENTION) 2011 sdev->changed = 1; 2012 } while (scsi_sense_valid(sshdr) && 2013 sshdr->sense_key == UNIT_ATTENTION && --retries); 2014 2015 if (!sshdr) 2016 /* could not allocate sense buffer, so can't process it */ 2017 return result; 2018 2019 if (sdev->removable && scsi_sense_valid(sshdr) && 2020 (sshdr->sense_key == UNIT_ATTENTION || 2021 sshdr->sense_key == NOT_READY)) { 2022 sdev->changed = 1; 2023 result = 0; 2024 } 2025 if (!sshdr_external) 2026 kfree(sshdr); 2027 return result; 2028} 2029EXPORT_SYMBOL(scsi_test_unit_ready); 2030 2031/** 2032 * scsi_device_set_state - Take the given device through the device state model. 2033 * @sdev: scsi device to change the state of. 2034 * @state: state to change to. 2035 * 2036 * Returns zero if unsuccessful or an error if the requested 2037 * transition is illegal. 2038 */ 2039int 2040scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state) 2041{ 2042 enum scsi_device_state oldstate = sdev->sdev_state; 2043 2044 if (state == oldstate) 2045 return 0; 2046 2047 switch (state) { 2048 case SDEV_CREATED: 2049 switch (oldstate) { 2050 case SDEV_CREATED_BLOCK: 2051 break; 2052 default: 2053 goto illegal; 2054 } 2055 break; 2056 2057 case SDEV_RUNNING: 2058 switch (oldstate) { 2059 case SDEV_CREATED: 2060 case SDEV_OFFLINE: 2061 case SDEV_QUIESCE: 2062 case SDEV_BLOCK: 2063 break; 2064 default: 2065 goto illegal; 2066 } 2067 break; 2068 2069 case SDEV_QUIESCE: 2070 switch (oldstate) { 2071 case SDEV_RUNNING: 2072 case SDEV_OFFLINE: 2073 break; 2074 default: 2075 goto illegal; 2076 } 2077 break; 2078 2079 case SDEV_OFFLINE: 2080 switch (oldstate) { 2081 case SDEV_CREATED: 2082 case SDEV_RUNNING: 2083 case SDEV_QUIESCE: 2084 case SDEV_BLOCK: 2085 break; 2086 default: 2087 goto illegal; 2088 } 2089 break; 2090 2091 case SDEV_BLOCK: 2092 switch (oldstate) { 2093 case SDEV_RUNNING: 2094 case SDEV_CREATED_BLOCK: 2095 break; 2096 default: 2097 goto illegal; 2098 } 2099 break; 2100 2101 case SDEV_CREATED_BLOCK: 2102 switch (oldstate) { 2103 case SDEV_CREATED: 2104 break; 2105 default: 2106 goto illegal; 2107 } 2108 break; 2109 2110 case SDEV_CANCEL: 2111 switch (oldstate) { 2112 case SDEV_CREATED: 2113 case SDEV_RUNNING: 2114 case SDEV_QUIESCE: 2115 case SDEV_OFFLINE: 2116 case SDEV_BLOCK: 2117 break; 2118 default: 2119 goto illegal; 2120 } 2121 break; 2122 2123 case SDEV_DEL: 2124 switch (oldstate) { 2125 case SDEV_CREATED: 2126 case SDEV_RUNNING: 2127 case SDEV_OFFLINE: 2128 case SDEV_CANCEL: 2129 break; 2130 default: 2131 goto illegal; 2132 } 2133 break; 2134 2135 } 2136 sdev->sdev_state = state; 2137 return 0; 2138 2139 illegal: 2140 SCSI_LOG_ERROR_RECOVERY(1, 2141 sdev_printk(KERN_ERR, sdev, 2142 "Illegal state transition %s->%s\n", 2143 scsi_device_state_name(oldstate), 2144 scsi_device_state_name(state)) 2145 ); 2146 return -EINVAL; 2147} 2148EXPORT_SYMBOL(scsi_device_set_state); 2149 2150/** 2151 * sdev_evt_emit - emit a single SCSI device uevent 2152 * @sdev: associated SCSI device 2153 * @evt: event to emit 2154 * 2155 * Send a single uevent (scsi_event) to the associated scsi_device. 2156 */ 2157static void scsi_evt_emit(struct scsi_device *sdev, struct scsi_event *evt) 2158{ 2159 int idx = 0; 2160 char *envp[3]; 2161 2162 switch (evt->evt_type) { 2163 case SDEV_EVT_MEDIA_CHANGE: 2164 envp[idx++] = "SDEV_MEDIA_CHANGE=1"; 2165 break; 2166 2167 default: 2168 /* do nothing */ 2169 break; 2170 } 2171 2172 envp[idx++] = NULL; 2173 2174 kobject_uevent_env(&sdev->sdev_gendev.kobj, KOBJ_CHANGE, envp); 2175} 2176 2177/** 2178 * sdev_evt_thread - send a uevent for each scsi event 2179 * @work: work struct for scsi_device 2180 * 2181 * Dispatch queued events to their associated scsi_device kobjects 2182 * as uevents. 2183 */ 2184void scsi_evt_thread(struct work_struct *work) 2185{ 2186 struct scsi_device *sdev; 2187 LIST_HEAD(event_list); 2188 2189 sdev = container_of(work, struct scsi_device, event_work); 2190 2191 while (1) { 2192 struct scsi_event *evt; 2193 struct list_head *this, *tmp; 2194 unsigned long flags; 2195 2196 spin_lock_irqsave(&sdev->list_lock, flags); 2197 list_splice_init(&sdev->event_list, &event_list); 2198 spin_unlock_irqrestore(&sdev->list_lock, flags); 2199 2200 if (list_empty(&event_list)) 2201 break; 2202 2203 list_for_each_safe(this, tmp, &event_list) { 2204 evt = list_entry(this, struct scsi_event, node); 2205 list_del(&evt->node); 2206 scsi_evt_emit(sdev, evt); 2207 kfree(evt); 2208 } 2209 } 2210} 2211 2212/** 2213 * sdev_evt_send - send asserted event to uevent thread 2214 * @sdev: scsi_device event occurred on 2215 * @evt: event to send 2216 * 2217 * Assert scsi device event asynchronously. 2218 */ 2219void sdev_evt_send(struct scsi_device *sdev, struct scsi_event *evt) 2220{ 2221 unsigned long flags; 2222 2223#if 0 2224 /* FIXME: currently this check eliminates all media change events 2225 * for polled devices. Need to update to discriminate between AN 2226 * and polled events */ 2227 if (!test_bit(evt->evt_type, sdev->supported_events)) { 2228 kfree(evt); 2229 return; 2230 } 2231#endif 2232 2233 spin_lock_irqsave(&sdev->list_lock, flags); 2234 list_add_tail(&evt->node, &sdev->event_list); 2235 schedule_work(&sdev->event_work); 2236 spin_unlock_irqrestore(&sdev->list_lock, flags); 2237} 2238EXPORT_SYMBOL_GPL(sdev_evt_send); 2239 2240/** 2241 * sdev_evt_alloc - allocate a new scsi event 2242 * @evt_type: type of event to allocate 2243 * @gfpflags: GFP flags for allocation 2244 * 2245 * Allocates and returns a new scsi_event. 2246 */ 2247struct scsi_event *sdev_evt_alloc(enum scsi_device_event evt_type, 2248 gfp_t gfpflags) 2249{ 2250 struct scsi_event *evt = kzalloc(sizeof(struct scsi_event), gfpflags); 2251 if (!evt) 2252 return NULL; 2253 2254 evt->evt_type = evt_type; 2255 INIT_LIST_HEAD(&evt->node); 2256 2257 /* evt_type-specific initialization, if any */ 2258 switch (evt_type) { 2259 case SDEV_EVT_MEDIA_CHANGE: 2260 default: 2261 /* do nothing */ 2262 break; 2263 } 2264 2265 return evt; 2266} 2267EXPORT_SYMBOL_GPL(sdev_evt_alloc); 2268 2269/** 2270 * sdev_evt_send_simple - send asserted event to uevent thread 2271 * @sdev: scsi_device event occurred on 2272 * @evt_type: type of event to send 2273 * @gfpflags: GFP flags for allocation 2274 * 2275 * Assert scsi device event asynchronously, given an event type. 2276 */ 2277void sdev_evt_send_simple(struct scsi_device *sdev, 2278 enum scsi_device_event evt_type, gfp_t gfpflags) 2279{ 2280 struct scsi_event *evt = sdev_evt_alloc(evt_type, gfpflags); 2281 if (!evt) { 2282 sdev_printk(KERN_ERR, sdev, "event %d eaten due to OOM\n", 2283 evt_type); 2284 return; 2285 } 2286 2287 sdev_evt_send(sdev, evt); 2288} 2289EXPORT_SYMBOL_GPL(sdev_evt_send_simple); 2290 2291/** 2292 * scsi_device_quiesce - Block user issued commands. 2293 * @sdev: scsi device to quiesce. 2294 * 2295 * This works by trying to transition to the SDEV_QUIESCE state 2296 * (which must be a legal transition). When the device is in this 2297 * state, only special requests will be accepted, all others will 2298 * be deferred. Since special requests may also be requeued requests, 2299 * a successful return doesn't guarantee the device will be 2300 * totally quiescent. 2301 * 2302 * Must be called with user context, may sleep. 2303 * 2304 * Returns zero if unsuccessful or an error if not. 2305 */ 2306int 2307scsi_device_quiesce(struct scsi_device *sdev) 2308{ 2309 int err = scsi_device_set_state(sdev, SDEV_QUIESCE); 2310 if (err) 2311 return err; 2312 2313 scsi_run_queue(sdev->request_queue); 2314 while (sdev->device_busy) { 2315 msleep_interruptible(200); 2316 scsi_run_queue(sdev->request_queue); 2317 } 2318 return 0; 2319} 2320EXPORT_SYMBOL(scsi_device_quiesce); 2321 2322/** 2323 * scsi_device_resume - Restart user issued commands to a quiesced device. 2324 * @sdev: scsi device to resume. 2325 * 2326 * Moves the device from quiesced back to running and restarts the 2327 * queues. 2328 * 2329 * Must be called with user context, may sleep. 2330 */ 2331void 2332scsi_device_resume(struct scsi_device *sdev) 2333{ 2334 if(scsi_device_set_state(sdev, SDEV_RUNNING)) 2335 return; 2336 scsi_run_queue(sdev->request_queue); 2337} 2338EXPORT_SYMBOL(scsi_device_resume); 2339 2340static void 2341device_quiesce_fn(struct scsi_device *sdev, void *data) 2342{ 2343 scsi_device_quiesce(sdev); 2344} 2345 2346void 2347scsi_target_quiesce(struct scsi_target *starget) 2348{ 2349 starget_for_each_device(starget, NULL, device_quiesce_fn); 2350} 2351EXPORT_SYMBOL(scsi_target_quiesce); 2352 2353static void 2354device_resume_fn(struct scsi_device *sdev, void *data) 2355{ 2356 scsi_device_resume(sdev); 2357} 2358 2359void 2360scsi_target_resume(struct scsi_target *starget) 2361{ 2362 starget_for_each_device(starget, NULL, device_resume_fn); 2363} 2364EXPORT_SYMBOL(scsi_target_resume); 2365 2366/** 2367 * scsi_internal_device_block - internal function to put a device temporarily into the SDEV_BLOCK state 2368 * @sdev: device to block 2369 * 2370 * Block request made by scsi lld's to temporarily stop all 2371 * scsi commands on the specified device. Called from interrupt 2372 * or normal process context. 2373 * 2374 * Returns zero if successful or error if not 2375 * 2376 * Notes: 2377 * This routine transitions the device to the SDEV_BLOCK state 2378 * (which must be a legal transition). When the device is in this 2379 * state, all commands are deferred until the scsi lld reenables 2380 * the device with scsi_device_unblock or device_block_tmo fires. 2381 * This routine assumes the host_lock is held on entry. 2382 */ 2383int 2384scsi_internal_device_block(struct scsi_device *sdev) 2385{ 2386 struct request_queue *q = sdev->request_queue; 2387 unsigned long flags; 2388 int err = 0; 2389 2390 err = scsi_device_set_state(sdev, SDEV_BLOCK); 2391 if (err) { 2392 err = scsi_device_set_state(sdev, SDEV_CREATED_BLOCK); 2393 2394 if (err) 2395 return err; 2396 } 2397 2398 /* 2399 * The device has transitioned to SDEV_BLOCK. Stop the 2400 * block layer from calling the midlayer with this device's 2401 * request queue. 2402 */ 2403 spin_lock_irqsave(q->queue_lock, flags); 2404 blk_stop_queue(q); 2405 spin_unlock_irqrestore(q->queue_lock, flags); 2406 2407 return 0; 2408} 2409EXPORT_SYMBOL_GPL(scsi_internal_device_block); 2410 2411/** 2412 * scsi_internal_device_unblock - resume a device after a block request 2413 * @sdev: device to resume 2414 * 2415 * Called by scsi lld's or the midlayer to restart the device queue 2416 * for the previously suspended scsi device. Called from interrupt or 2417 * normal process context. 2418 * 2419 * Returns zero if successful or error if not. 2420 * 2421 * Notes: 2422 * This routine transitions the device to the SDEV_RUNNING state 2423 * (which must be a legal transition) allowing the midlayer to 2424 * goose the queue for this device. This routine assumes the 2425 * host_lock is held upon entry. 2426 */ 2427int 2428scsi_internal_device_unblock(struct scsi_device *sdev) 2429{ 2430 struct request_queue *q = sdev->request_queue; 2431 unsigned long flags; 2432 2433 /* 2434 * Try to transition the scsi device to SDEV_RUNNING 2435 * and goose the device queue if successful. 2436 */ 2437 if (sdev->sdev_state == SDEV_BLOCK) 2438 sdev->sdev_state = SDEV_RUNNING; 2439 else if (sdev->sdev_state == SDEV_CREATED_BLOCK) 2440 sdev->sdev_state = SDEV_CREATED; 2441 else 2442 return -EINVAL; 2443 2444 spin_lock_irqsave(q->queue_lock, flags); 2445 blk_start_queue(q); 2446 spin_unlock_irqrestore(q->queue_lock, flags); 2447 2448 return 0; 2449} 2450EXPORT_SYMBOL_GPL(scsi_internal_device_unblock); 2451 2452static void 2453device_block(struct scsi_device *sdev, void *data) 2454{ 2455 scsi_internal_device_block(sdev); 2456} 2457 2458static int 2459target_block(struct device *dev, void *data) 2460{ 2461 if (scsi_is_target_device(dev)) 2462 starget_for_each_device(to_scsi_target(dev), NULL, 2463 device_block); 2464 return 0; 2465} 2466 2467void 2468scsi_target_block(struct device *dev) 2469{ 2470 if (scsi_is_target_device(dev)) 2471 starget_for_each_device(to_scsi_target(dev), NULL, 2472 device_block); 2473 else 2474 device_for_each_child(dev, NULL, target_block); 2475} 2476EXPORT_SYMBOL_GPL(scsi_target_block); 2477 2478static void 2479device_unblock(struct scsi_device *sdev, void *data) 2480{ 2481 scsi_internal_device_unblock(sdev); 2482} 2483 2484static int 2485target_unblock(struct device *dev, void *data) 2486{ 2487 if (scsi_is_target_device(dev)) 2488 starget_for_each_device(to_scsi_target(dev), NULL, 2489 device_unblock); 2490 return 0; 2491} 2492 2493void 2494scsi_target_unblock(struct device *dev) 2495{ 2496 if (scsi_is_target_device(dev)) 2497 starget_for_each_device(to_scsi_target(dev), NULL, 2498 device_unblock); 2499 else 2500 device_for_each_child(dev, NULL, target_unblock); 2501} 2502EXPORT_SYMBOL_GPL(scsi_target_unblock); 2503 2504/** 2505 * scsi_kmap_atomic_sg - find and atomically map an sg-elemnt 2506 * @sgl: scatter-gather list 2507 * @sg_count: number of segments in sg 2508 * @offset: offset in bytes into sg, on return offset into the mapped area 2509 * @len: bytes to map, on return number of bytes mapped 2510 * 2511 * Returns virtual address of the start of the mapped page 2512 */ 2513void *scsi_kmap_atomic_sg(struct scatterlist *sgl, int sg_count, 2514 size_t *offset, size_t *len) 2515{ 2516 int i; 2517 size_t sg_len = 0, len_complete = 0; 2518 struct scatterlist *sg; 2519 struct page *page; 2520 2521 WARN_ON(!irqs_disabled()); 2522 2523 for_each_sg(sgl, sg, sg_count, i) { 2524 len_complete = sg_len; /* Complete sg-entries */ 2525 sg_len += sg->length; 2526 if (sg_len > *offset) 2527 break; 2528 } 2529 2530 if (unlikely(i == sg_count)) { 2531 printk(KERN_ERR "%s: Bytes in sg: %zu, requested offset %zu, " 2532 "elements %d\n", 2533 __func__, sg_len, *offset, sg_count); 2534 WARN_ON(1); 2535 return NULL; 2536 } 2537 2538 /* Offset starting from the beginning of first page in this sg-entry */ 2539 *offset = *offset - len_complete + sg->offset; 2540 2541 /* Assumption: contiguous pages can be accessed as "page + i" */ 2542 page = nth_page(sg_page(sg), (*offset >> PAGE_SHIFT)); 2543 *offset &= ~PAGE_MASK; 2544 2545 /* Bytes in this sg-entry from *offset to the end of the page */ 2546 sg_len = PAGE_SIZE - *offset; 2547 if (*len > sg_len) 2548 *len = sg_len; 2549 2550 return kmap_atomic(page, KM_BIO_SRC_IRQ); 2551} 2552EXPORT_SYMBOL(scsi_kmap_atomic_sg); 2553 2554/** 2555 * scsi_kunmap_atomic_sg - atomically unmap a virtual address, previously mapped with scsi_kmap_atomic_sg 2556 * @virt: virtual address to be unmapped 2557 */ 2558void scsi_kunmap_atomic_sg(void *virt) 2559{ 2560 kunmap_atomic(virt, KM_BIO_SRC_IRQ); 2561} 2562EXPORT_SYMBOL(scsi_kunmap_atomic_sg); 2563