scsi_lib.c revision fa8e36c39b00a219d2c37250e493c3421e0e67e9
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 68static struct kmem_cache *scsi_bidi_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 req->cmd_flags &= ~REQ_DONTPREP; 89 req->special = NULL; 90 91 scsi_put_command(cmd); 92} 93 94/* 95 * Function: scsi_queue_insert() 96 * 97 * Purpose: Insert a command in the midlevel queue. 98 * 99 * Arguments: cmd - command that we are adding to queue. 100 * reason - why we are inserting command to queue. 101 * 102 * Lock status: Assumed that lock is not held upon entry. 103 * 104 * Returns: Nothing. 105 * 106 * Notes: We do this for one of two cases. Either the host is busy 107 * and it cannot accept any more commands for the time being, 108 * or the device returned QUEUE_FULL and can accept no more 109 * commands. 110 * Notes: This could be called either from an interrupt context or a 111 * normal process context. 112 */ 113int scsi_queue_insert(struct scsi_cmnd *cmd, int reason) 114{ 115 struct Scsi_Host *host = cmd->device->host; 116 struct scsi_device *device = cmd->device; 117 struct request_queue *q = device->request_queue; 118 unsigned long flags; 119 120 SCSI_LOG_MLQUEUE(1, 121 printk("Inserting command %p into mlqueue\n", cmd)); 122 123 /* 124 * Set the appropriate busy bit for the device/host. 125 * 126 * If the host/device isn't busy, assume that something actually 127 * completed, and that we should be able to queue a command now. 128 * 129 * Note that the prior mid-layer assumption that any host could 130 * always queue at least one command is now broken. The mid-layer 131 * will implement a user specifiable stall (see 132 * scsi_host.max_host_blocked and scsi_device.max_device_blocked) 133 * if a command is requeued with no other commands outstanding 134 * either for the device or for the host. 135 */ 136 if (reason == SCSI_MLQUEUE_HOST_BUSY) 137 host->host_blocked = host->max_host_blocked; 138 else if (reason == SCSI_MLQUEUE_DEVICE_BUSY) 139 device->device_blocked = device->max_device_blocked; 140 141 /* 142 * Decrement the counters, since these commands are no longer 143 * active on the host/device. 144 */ 145 scsi_device_unbusy(device); 146 147 /* 148 * Requeue this command. It will go before all other commands 149 * that are already in the queue. 150 * 151 * NOTE: there is magic here about the way the queue is plugged if 152 * we have no outstanding commands. 153 * 154 * Although we *don't* plug the queue, we call the request 155 * function. The SCSI request function detects the blocked condition 156 * and plugs the queue appropriately. 157 */ 158 spin_lock_irqsave(q->queue_lock, flags); 159 blk_requeue_request(q, cmd->request); 160 spin_unlock_irqrestore(q->queue_lock, flags); 161 162 scsi_run_queue(q); 163 164 return 0; 165} 166 167/** 168 * scsi_execute - insert request and wait for the result 169 * @sdev: scsi device 170 * @cmd: scsi command 171 * @data_direction: data direction 172 * @buffer: data buffer 173 * @bufflen: len of buffer 174 * @sense: optional sense buffer 175 * @timeout: request timeout in seconds 176 * @retries: number of times to retry request 177 * @flags: or into request flags; 178 * 179 * returns the req->errors value which is the scsi_cmnd result 180 * field. 181 */ 182int scsi_execute(struct scsi_device *sdev, const unsigned char *cmd, 183 int data_direction, void *buffer, unsigned bufflen, 184 unsigned char *sense, int timeout, int retries, int flags) 185{ 186 struct request *req; 187 int write = (data_direction == DMA_TO_DEVICE); 188 int ret = DRIVER_ERROR << 24; 189 190 req = blk_get_request(sdev->request_queue, write, __GFP_WAIT); 191 192 if (bufflen && blk_rq_map_kern(sdev->request_queue, req, 193 buffer, bufflen, __GFP_WAIT)) 194 goto out; 195 196 req->cmd_len = COMMAND_SIZE(cmd[0]); 197 memcpy(req->cmd, cmd, req->cmd_len); 198 req->sense = sense; 199 req->sense_len = 0; 200 req->retries = retries; 201 req->timeout = timeout; 202 req->cmd_type = REQ_TYPE_BLOCK_PC; 203 req->cmd_flags |= flags | REQ_QUIET | REQ_PREEMPT; 204 205 /* 206 * head injection *required* here otherwise quiesce won't work 207 */ 208 blk_execute_rq(req->q, NULL, req, 1); 209 210 ret = req->errors; 211 out: 212 blk_put_request(req); 213 214 return ret; 215} 216EXPORT_SYMBOL(scsi_execute); 217 218 219int scsi_execute_req(struct scsi_device *sdev, const unsigned char *cmd, 220 int data_direction, void *buffer, unsigned bufflen, 221 struct scsi_sense_hdr *sshdr, int timeout, int retries) 222{ 223 char *sense = NULL; 224 int result; 225 226 if (sshdr) { 227 sense = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_NOIO); 228 if (!sense) 229 return DRIVER_ERROR << 24; 230 } 231 result = scsi_execute(sdev, cmd, data_direction, buffer, bufflen, 232 sense, timeout, retries, 0); 233 if (sshdr) 234 scsi_normalize_sense(sense, SCSI_SENSE_BUFFERSIZE, sshdr); 235 236 kfree(sense); 237 return result; 238} 239EXPORT_SYMBOL(scsi_execute_req); 240 241struct scsi_io_context { 242 void *data; 243 void (*done)(void *data, char *sense, int result, int resid); 244 char sense[SCSI_SENSE_BUFFERSIZE]; 245}; 246 247static struct kmem_cache *scsi_io_context_cache; 248 249static void scsi_end_async(struct request *req, int uptodate) 250{ 251 struct scsi_io_context *sioc = req->end_io_data; 252 253 if (sioc->done) 254 sioc->done(sioc->data, sioc->sense, req->errors, req->data_len); 255 256 kmem_cache_free(scsi_io_context_cache, sioc); 257 __blk_put_request(req->q, req); 258} 259 260static int scsi_merge_bio(struct request *rq, struct bio *bio) 261{ 262 struct request_queue *q = rq->q; 263 264 bio->bi_flags &= ~(1 << BIO_SEG_VALID); 265 if (rq_data_dir(rq) == WRITE) 266 bio->bi_rw |= (1 << BIO_RW); 267 blk_queue_bounce(q, &bio); 268 269 return blk_rq_append_bio(q, rq, bio); 270} 271 272static void scsi_bi_endio(struct bio *bio, int error) 273{ 274 bio_put(bio); 275} 276 277/** 278 * scsi_req_map_sg - map a scatterlist into a request 279 * @rq: request to fill 280 * @sgl: scatterlist 281 * @nsegs: number of elements 282 * @bufflen: len of buffer 283 * @gfp: memory allocation flags 284 * 285 * scsi_req_map_sg maps a scatterlist into a request so that the 286 * request can be sent to the block layer. We do not trust the scatterlist 287 * sent to use, as some ULDs use that struct to only organize the pages. 288 */ 289static int scsi_req_map_sg(struct request *rq, struct scatterlist *sgl, 290 int nsegs, unsigned bufflen, gfp_t gfp) 291{ 292 struct request_queue *q = rq->q; 293 int nr_pages = (bufflen + sgl[0].offset + PAGE_SIZE - 1) >> PAGE_SHIFT; 294 unsigned int data_len = bufflen, len, bytes, off; 295 struct scatterlist *sg; 296 struct page *page; 297 struct bio *bio = NULL; 298 int i, err, nr_vecs = 0; 299 300 for_each_sg(sgl, sg, nsegs, i) { 301 page = sg_page(sg); 302 off = sg->offset; 303 len = sg->length; 304 305 while (len > 0 && data_len > 0) { 306 /* 307 * sg sends a scatterlist that is larger than 308 * the data_len it wants transferred for certain 309 * IO sizes 310 */ 311 bytes = min_t(unsigned int, len, PAGE_SIZE - off); 312 bytes = min(bytes, data_len); 313 314 if (!bio) { 315 nr_vecs = min_t(int, BIO_MAX_PAGES, nr_pages); 316 nr_pages -= nr_vecs; 317 318 bio = bio_alloc(gfp, nr_vecs); 319 if (!bio) { 320 err = -ENOMEM; 321 goto free_bios; 322 } 323 bio->bi_end_io = scsi_bi_endio; 324 } 325 326 if (bio_add_pc_page(q, bio, page, bytes, off) != 327 bytes) { 328 bio_put(bio); 329 err = -EINVAL; 330 goto free_bios; 331 } 332 333 if (bio->bi_vcnt >= nr_vecs) { 334 err = scsi_merge_bio(rq, bio); 335 if (err) { 336 bio_endio(bio, 0); 337 goto free_bios; 338 } 339 bio = NULL; 340 } 341 342 page++; 343 len -= bytes; 344 data_len -=bytes; 345 off = 0; 346 } 347 } 348 349 rq->buffer = rq->data = NULL; 350 rq->data_len = bufflen; 351 return 0; 352 353free_bios: 354 while ((bio = rq->bio) != NULL) { 355 rq->bio = bio->bi_next; 356 /* 357 * call endio instead of bio_put incase it was bounced 358 */ 359 bio_endio(bio, 0); 360 } 361 362 return err; 363} 364 365/** 366 * scsi_execute_async - insert request 367 * @sdev: scsi device 368 * @cmd: scsi command 369 * @cmd_len: length of scsi cdb 370 * @data_direction: DMA_TO_DEVICE, DMA_FROM_DEVICE, or DMA_NONE 371 * @buffer: data buffer (this can be a kernel buffer or scatterlist) 372 * @bufflen: len of buffer 373 * @use_sg: if buffer is a scatterlist this is the number of elements 374 * @timeout: request timeout in seconds 375 * @retries: number of times to retry request 376 * @privdata: data passed to done() 377 * @done: callback function when done 378 * @gfp: memory allocation flags 379 */ 380int scsi_execute_async(struct scsi_device *sdev, const unsigned char *cmd, 381 int cmd_len, int data_direction, void *buffer, unsigned bufflen, 382 int use_sg, int timeout, int retries, void *privdata, 383 void (*done)(void *, char *, int, int), gfp_t gfp) 384{ 385 struct request *req; 386 struct scsi_io_context *sioc; 387 int err = 0; 388 int write = (data_direction == DMA_TO_DEVICE); 389 390 sioc = kmem_cache_zalloc(scsi_io_context_cache, gfp); 391 if (!sioc) 392 return DRIVER_ERROR << 24; 393 394 req = blk_get_request(sdev->request_queue, write, gfp); 395 if (!req) 396 goto free_sense; 397 req->cmd_type = REQ_TYPE_BLOCK_PC; 398 req->cmd_flags |= REQ_QUIET; 399 400 if (use_sg) 401 err = scsi_req_map_sg(req, buffer, use_sg, bufflen, gfp); 402 else if (bufflen) 403 err = blk_rq_map_kern(req->q, req, buffer, bufflen, gfp); 404 405 if (err) 406 goto free_req; 407 408 req->cmd_len = cmd_len; 409 memset(req->cmd, 0, BLK_MAX_CDB); /* ATAPI hates garbage after CDB */ 410 memcpy(req->cmd, cmd, req->cmd_len); 411 req->sense = sioc->sense; 412 req->sense_len = 0; 413 req->timeout = timeout; 414 req->retries = retries; 415 req->end_io_data = sioc; 416 417 sioc->data = privdata; 418 sioc->done = done; 419 420 blk_execute_rq_nowait(req->q, NULL, req, 1, scsi_end_async); 421 return 0; 422 423free_req: 424 blk_put_request(req); 425free_sense: 426 kmem_cache_free(scsi_io_context_cache, sioc); 427 return DRIVER_ERROR << 24; 428} 429EXPORT_SYMBOL_GPL(scsi_execute_async); 430 431/* 432 * Function: scsi_init_cmd_errh() 433 * 434 * Purpose: Initialize cmd fields related to error handling. 435 * 436 * Arguments: cmd - command that is ready to be queued. 437 * 438 * Notes: This function has the job of initializing a number of 439 * fields related to error handling. Typically this will 440 * be called once for each command, as required. 441 */ 442static void scsi_init_cmd_errh(struct scsi_cmnd *cmd) 443{ 444 cmd->serial_number = 0; 445 scsi_set_resid(cmd, 0); 446 memset(cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE); 447 if (cmd->cmd_len == 0) 448 cmd->cmd_len = COMMAND_SIZE(cmd->cmnd[0]); 449} 450 451void scsi_device_unbusy(struct scsi_device *sdev) 452{ 453 struct Scsi_Host *shost = sdev->host; 454 unsigned long flags; 455 456 spin_lock_irqsave(shost->host_lock, flags); 457 shost->host_busy--; 458 if (unlikely(scsi_host_in_recovery(shost) && 459 (shost->host_failed || shost->host_eh_scheduled))) 460 scsi_eh_wakeup(shost); 461 spin_unlock(shost->host_lock); 462 spin_lock(sdev->request_queue->queue_lock); 463 sdev->device_busy--; 464 spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags); 465} 466 467/* 468 * Called for single_lun devices on IO completion. Clear starget_sdev_user, 469 * and call blk_run_queue for all the scsi_devices on the target - 470 * including current_sdev first. 471 * 472 * Called with *no* scsi locks held. 473 */ 474static void scsi_single_lun_run(struct scsi_device *current_sdev) 475{ 476 struct Scsi_Host *shost = current_sdev->host; 477 struct scsi_device *sdev, *tmp; 478 struct scsi_target *starget = scsi_target(current_sdev); 479 unsigned long flags; 480 481 spin_lock_irqsave(shost->host_lock, flags); 482 starget->starget_sdev_user = NULL; 483 spin_unlock_irqrestore(shost->host_lock, flags); 484 485 /* 486 * Call blk_run_queue for all LUNs on the target, starting with 487 * current_sdev. We race with others (to set starget_sdev_user), 488 * but in most cases, we will be first. Ideally, each LU on the 489 * target would get some limited time or requests on the target. 490 */ 491 blk_run_queue(current_sdev->request_queue); 492 493 spin_lock_irqsave(shost->host_lock, flags); 494 if (starget->starget_sdev_user) 495 goto out; 496 list_for_each_entry_safe(sdev, tmp, &starget->devices, 497 same_target_siblings) { 498 if (sdev == current_sdev) 499 continue; 500 if (scsi_device_get(sdev)) 501 continue; 502 503 spin_unlock_irqrestore(shost->host_lock, flags); 504 blk_run_queue(sdev->request_queue); 505 spin_lock_irqsave(shost->host_lock, flags); 506 507 scsi_device_put(sdev); 508 } 509 out: 510 spin_unlock_irqrestore(shost->host_lock, flags); 511} 512 513/* 514 * Function: scsi_run_queue() 515 * 516 * Purpose: Select a proper request queue to serve next 517 * 518 * Arguments: q - last request's queue 519 * 520 * Returns: Nothing 521 * 522 * Notes: The previous command was completely finished, start 523 * a new one if possible. 524 */ 525static void scsi_run_queue(struct request_queue *q) 526{ 527 struct scsi_device *sdev = q->queuedata; 528 struct Scsi_Host *shost = sdev->host; 529 unsigned long flags; 530 531 if (scsi_target(sdev)->single_lun) 532 scsi_single_lun_run(sdev); 533 534 spin_lock_irqsave(shost->host_lock, flags); 535 while (!list_empty(&shost->starved_list) && 536 !shost->host_blocked && !shost->host_self_blocked && 537 !((shost->can_queue > 0) && 538 (shost->host_busy >= shost->can_queue))) { 539 /* 540 * As long as shost is accepting commands and we have 541 * starved queues, call blk_run_queue. scsi_request_fn 542 * drops the queue_lock and can add us back to the 543 * starved_list. 544 * 545 * host_lock protects the starved_list and starved_entry. 546 * scsi_request_fn must get the host_lock before checking 547 * or modifying starved_list or starved_entry. 548 */ 549 sdev = list_entry(shost->starved_list.next, 550 struct scsi_device, starved_entry); 551 list_del_init(&sdev->starved_entry); 552 spin_unlock_irqrestore(shost->host_lock, flags); 553 554 555 if (test_bit(QUEUE_FLAG_REENTER, &q->queue_flags) && 556 !test_and_set_bit(QUEUE_FLAG_REENTER, 557 &sdev->request_queue->queue_flags)) { 558 blk_run_queue(sdev->request_queue); 559 clear_bit(QUEUE_FLAG_REENTER, 560 &sdev->request_queue->queue_flags); 561 } else 562 blk_run_queue(sdev->request_queue); 563 564 spin_lock_irqsave(shost->host_lock, flags); 565 if (unlikely(!list_empty(&sdev->starved_entry))) 566 /* 567 * sdev lost a race, and was put back on the 568 * starved list. This is unlikely but without this 569 * in theory we could loop forever. 570 */ 571 break; 572 } 573 spin_unlock_irqrestore(shost->host_lock, flags); 574 575 blk_run_queue(q); 576} 577 578/* 579 * Function: scsi_requeue_command() 580 * 581 * Purpose: Handle post-processing of completed commands. 582 * 583 * Arguments: q - queue to operate on 584 * cmd - command that may need to be requeued. 585 * 586 * Returns: Nothing 587 * 588 * Notes: After command completion, there may be blocks left 589 * over which weren't finished by the previous command 590 * this can be for a number of reasons - the main one is 591 * I/O errors in the middle of the request, in which case 592 * we need to request the blocks that come after the bad 593 * sector. 594 * Notes: Upon return, cmd is a stale pointer. 595 */ 596static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd) 597{ 598 struct request *req = cmd->request; 599 unsigned long flags; 600 601 scsi_unprep_request(req); 602 spin_lock_irqsave(q->queue_lock, flags); 603 blk_requeue_request(q, req); 604 spin_unlock_irqrestore(q->queue_lock, flags); 605 606 scsi_run_queue(q); 607} 608 609void scsi_next_command(struct scsi_cmnd *cmd) 610{ 611 struct scsi_device *sdev = cmd->device; 612 struct request_queue *q = sdev->request_queue; 613 614 /* need to hold a reference on the device before we let go of the cmd */ 615 get_device(&sdev->sdev_gendev); 616 617 scsi_put_command(cmd); 618 scsi_run_queue(q); 619 620 /* ok to remove device now */ 621 put_device(&sdev->sdev_gendev); 622} 623 624void scsi_run_host_queues(struct Scsi_Host *shost) 625{ 626 struct scsi_device *sdev; 627 628 shost_for_each_device(sdev, shost) 629 scsi_run_queue(sdev->request_queue); 630} 631 632/* 633 * Function: scsi_end_request() 634 * 635 * Purpose: Post-processing of completed commands (usually invoked at end 636 * of upper level post-processing and scsi_io_completion). 637 * 638 * Arguments: cmd - command that is complete. 639 * error - 0 if I/O indicates success, < 0 for I/O error. 640 * bytes - number of bytes of completed I/O 641 * requeue - indicates whether we should requeue leftovers. 642 * 643 * Lock status: Assumed that lock is not held upon entry. 644 * 645 * Returns: cmd if requeue required, NULL otherwise. 646 * 647 * Notes: This is called for block device requests in order to 648 * mark some number of sectors as complete. 649 * 650 * We are guaranteeing that the request queue will be goosed 651 * at some point during this call. 652 * Notes: If cmd was requeued, upon return it will be a stale pointer. 653 */ 654static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int error, 655 int bytes, int requeue) 656{ 657 struct request_queue *q = cmd->device->request_queue; 658 struct request *req = cmd->request; 659 660 /* 661 * If there are blocks left over at the end, set up the command 662 * to queue the remainder of them. 663 */ 664 if (blk_end_request(req, error, bytes)) { 665 int leftover = (req->hard_nr_sectors << 9); 666 667 if (blk_pc_request(req)) 668 leftover = req->data_len; 669 670 /* kill remainder if no retrys */ 671 if (error && blk_noretry_request(req)) 672 blk_end_request(req, error, leftover); 673 else { 674 if (requeue) { 675 /* 676 * Bleah. Leftovers again. Stick the 677 * leftovers in the front of the 678 * queue, and goose the queue again. 679 */ 680 scsi_requeue_command(q, cmd); 681 cmd = NULL; 682 } 683 return cmd; 684 } 685 } 686 687 /* 688 * This will goose the queue request function at the end, so we don't 689 * need to worry about launching another command. 690 */ 691 scsi_next_command(cmd); 692 return NULL; 693} 694 695static inline unsigned int scsi_sgtable_index(unsigned short nents) 696{ 697 unsigned int index; 698 699 BUG_ON(nents > SCSI_MAX_SG_SEGMENTS); 700 701 if (nents <= 8) 702 index = 0; 703 else 704 index = get_count_order(nents) - 3; 705 706 return index; 707} 708 709static void scsi_sg_free(struct scatterlist *sgl, unsigned int nents) 710{ 711 struct scsi_host_sg_pool *sgp; 712 713 sgp = scsi_sg_pools + scsi_sgtable_index(nents); 714 mempool_free(sgl, sgp->pool); 715} 716 717static struct scatterlist *scsi_sg_alloc(unsigned int nents, gfp_t gfp_mask) 718{ 719 struct scsi_host_sg_pool *sgp; 720 721 sgp = scsi_sg_pools + scsi_sgtable_index(nents); 722 return mempool_alloc(sgp->pool, gfp_mask); 723} 724 725static int scsi_alloc_sgtable(struct scsi_data_buffer *sdb, int nents, 726 gfp_t gfp_mask) 727{ 728 int ret; 729 730 BUG_ON(!nents); 731 732 ret = __sg_alloc_table(&sdb->table, nents, SCSI_MAX_SG_SEGMENTS, 733 gfp_mask, scsi_sg_alloc); 734 if (unlikely(ret)) 735 __sg_free_table(&sdb->table, SCSI_MAX_SG_SEGMENTS, 736 scsi_sg_free); 737 738 return ret; 739} 740 741static void scsi_free_sgtable(struct scsi_data_buffer *sdb) 742{ 743 __sg_free_table(&sdb->table, SCSI_MAX_SG_SEGMENTS, scsi_sg_free); 744} 745 746/* 747 * Function: scsi_release_buffers() 748 * 749 * Purpose: Completion processing for block device I/O requests. 750 * 751 * Arguments: cmd - command that we are bailing. 752 * 753 * Lock status: Assumed that no lock is held upon entry. 754 * 755 * Returns: Nothing 756 * 757 * Notes: In the event that an upper level driver rejects a 758 * command, we must release resources allocated during 759 * the __init_io() function. Primarily this would involve 760 * the scatter-gather table, and potentially any bounce 761 * buffers. 762 */ 763void scsi_release_buffers(struct scsi_cmnd *cmd) 764{ 765 if (cmd->sdb.table.nents) 766 scsi_free_sgtable(&cmd->sdb); 767 768 memset(&cmd->sdb, 0, sizeof(cmd->sdb)); 769 770 if (scsi_bidi_cmnd(cmd)) { 771 struct scsi_data_buffer *bidi_sdb = 772 cmd->request->next_rq->special; 773 scsi_free_sgtable(bidi_sdb); 774 kmem_cache_free(scsi_bidi_sdb_cache, bidi_sdb); 775 cmd->request->next_rq->special = NULL; 776 } 777} 778EXPORT_SYMBOL(scsi_release_buffers); 779 780/* 781 * Bidi commands Must be complete as a whole, both sides at once. 782 * If part of the bytes were written and lld returned 783 * scsi_in()->resid and/or scsi_out()->resid this information will be left 784 * in req->data_len and req->next_rq->data_len. The upper-layer driver can 785 * decide what to do with this information. 786 */ 787static void scsi_end_bidi_request(struct scsi_cmnd *cmd) 788{ 789 struct request *req = cmd->request; 790 unsigned int dlen = req->data_len; 791 unsigned int next_dlen = req->next_rq->data_len; 792 793 req->data_len = scsi_out(cmd)->resid; 794 req->next_rq->data_len = scsi_in(cmd)->resid; 795 796 /* The req and req->next_rq have not been completed */ 797 BUG_ON(blk_end_bidi_request(req, 0, dlen, next_dlen)); 798 799 scsi_release_buffers(cmd); 800 801 /* 802 * This will goose the queue request function at the end, so we don't 803 * need to worry about launching another command. 804 */ 805 scsi_next_command(cmd); 806} 807 808/* 809 * Function: scsi_io_completion() 810 * 811 * Purpose: Completion processing for block device I/O requests. 812 * 813 * Arguments: cmd - command that is finished. 814 * 815 * Lock status: Assumed that no lock is held upon entry. 816 * 817 * Returns: Nothing 818 * 819 * Notes: This function is matched in terms of capabilities to 820 * the function that created the scatter-gather list. 821 * In other words, if there are no bounce buffers 822 * (the normal case for most drivers), we don't need 823 * the logic to deal with cleaning up afterwards. 824 * 825 * We must do one of several things here: 826 * 827 * a) Call scsi_end_request. This will finish off the 828 * specified number of sectors. If we are done, the 829 * command block will be released, and the queue 830 * function will be goosed. If we are not done, then 831 * scsi_end_request will directly goose the queue. 832 * 833 * b) We can just use scsi_requeue_command() here. This would 834 * be used if we just wanted to retry, for example. 835 */ 836void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes) 837{ 838 int result = cmd->result; 839 int this_count = scsi_bufflen(cmd); 840 struct request_queue *q = cmd->device->request_queue; 841 struct request *req = cmd->request; 842 int error = 0; 843 struct scsi_sense_hdr sshdr; 844 int sense_valid = 0; 845 int sense_deferred = 0; 846 847 if (result) { 848 sense_valid = scsi_command_normalize_sense(cmd, &sshdr); 849 if (sense_valid) 850 sense_deferred = scsi_sense_is_deferred(&sshdr); 851 } 852 853 if (blk_pc_request(req)) { /* SG_IO ioctl from block level */ 854 req->errors = result; 855 if (result) { 856 if (sense_valid && req->sense) { 857 /* 858 * SG_IO wants current and deferred errors 859 */ 860 int len = 8 + cmd->sense_buffer[7]; 861 862 if (len > SCSI_SENSE_BUFFERSIZE) 863 len = SCSI_SENSE_BUFFERSIZE; 864 memcpy(req->sense, cmd->sense_buffer, len); 865 req->sense_len = len; 866 } 867 if (!sense_deferred) 868 error = -EIO; 869 } 870 if (scsi_bidi_cmnd(cmd)) { 871 /* will also release_buffers */ 872 scsi_end_bidi_request(cmd); 873 return; 874 } 875 req->data_len = scsi_get_resid(cmd); 876 } 877 878 BUG_ON(blk_bidi_rq(req)); /* bidi not support for !blk_pc_request yet */ 879 scsi_release_buffers(cmd); 880 881 /* 882 * Next deal with any sectors which we were able to correctly 883 * handle. 884 */ 885 SCSI_LOG_HLCOMPLETE(1, printk("%ld sectors total, " 886 "%d bytes done.\n", 887 req->nr_sectors, good_bytes)); 888 889 /* A number of bytes were successfully read. If there 890 * are leftovers and there is some kind of error 891 * (result != 0), retry the rest. 892 */ 893 if (scsi_end_request(cmd, error, good_bytes, result == 0) == NULL) 894 return; 895 896 /* good_bytes = 0, or (inclusive) there were leftovers and 897 * result = 0, so scsi_end_request couldn't retry. 898 */ 899 if (sense_valid && !sense_deferred) { 900 switch (sshdr.sense_key) { 901 case UNIT_ATTENTION: 902 if (cmd->device->removable) { 903 /* Detected disc change. Set a bit 904 * and quietly refuse further access. 905 */ 906 cmd->device->changed = 1; 907 scsi_end_request(cmd, -EIO, this_count, 1); 908 return; 909 } else { 910 /* Must have been a power glitch, or a 911 * bus reset. Could not have been a 912 * media change, so we just retry the 913 * request and see what happens. 914 */ 915 scsi_requeue_command(q, cmd); 916 return; 917 } 918 break; 919 case ILLEGAL_REQUEST: 920 /* If we had an ILLEGAL REQUEST returned, then 921 * we may have performed an unsupported 922 * command. The only thing this should be 923 * would be a ten byte read where only a six 924 * byte read was supported. Also, on a system 925 * where READ CAPACITY failed, we may have 926 * read past the end of the disk. 927 */ 928 if ((cmd->device->use_10_for_rw && 929 sshdr.asc == 0x20 && sshdr.ascq == 0x00) && 930 (cmd->cmnd[0] == READ_10 || 931 cmd->cmnd[0] == WRITE_10)) { 932 cmd->device->use_10_for_rw = 0; 933 /* This will cause a retry with a 934 * 6-byte command. 935 */ 936 scsi_requeue_command(q, cmd); 937 return; 938 } else { 939 scsi_end_request(cmd, -EIO, this_count, 1); 940 return; 941 } 942 break; 943 case NOT_READY: 944 /* If the device is in the process of becoming 945 * ready, or has a temporary blockage, retry. 946 */ 947 if (sshdr.asc == 0x04) { 948 switch (sshdr.ascq) { 949 case 0x01: /* becoming ready */ 950 case 0x04: /* format in progress */ 951 case 0x05: /* rebuild in progress */ 952 case 0x06: /* recalculation in progress */ 953 case 0x07: /* operation in progress */ 954 case 0x08: /* Long write in progress */ 955 case 0x09: /* self test in progress */ 956 scsi_requeue_command(q, cmd); 957 return; 958 default: 959 break; 960 } 961 } 962 if (!(req->cmd_flags & REQ_QUIET)) 963 scsi_cmd_print_sense_hdr(cmd, 964 "Device not ready", 965 &sshdr); 966 967 scsi_end_request(cmd, -EIO, this_count, 1); 968 return; 969 case VOLUME_OVERFLOW: 970 if (!(req->cmd_flags & REQ_QUIET)) { 971 scmd_printk(KERN_INFO, cmd, 972 "Volume overflow, CDB: "); 973 __scsi_print_command(cmd->cmnd); 974 scsi_print_sense("", cmd); 975 } 976 /* See SSC3rXX or current. */ 977 scsi_end_request(cmd, -EIO, this_count, 1); 978 return; 979 default: 980 break; 981 } 982 } 983 if (host_byte(result) == DID_RESET) { 984 /* Third party bus reset or reset for error recovery 985 * reasons. Just retry the request and see what 986 * happens. 987 */ 988 scsi_requeue_command(q, cmd); 989 return; 990 } 991 if (result) { 992 if (!(req->cmd_flags & REQ_QUIET)) { 993 scsi_print_result(cmd); 994 if (driver_byte(result) & DRIVER_SENSE) 995 scsi_print_sense("", cmd); 996 } 997 } 998 scsi_end_request(cmd, -EIO, this_count, !result); 999} 1000 1001static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb, 1002 gfp_t gfp_mask) 1003{ 1004 int count; 1005 1006 /* 1007 * If sg table allocation fails, requeue request later. 1008 */ 1009 if (unlikely(scsi_alloc_sgtable(sdb, req->nr_phys_segments, 1010 gfp_mask))) { 1011 return BLKPREP_DEFER; 1012 } 1013 1014 req->buffer = NULL; 1015 1016 /* 1017 * Next, walk the list, and fill in the addresses and sizes of 1018 * each segment. 1019 */ 1020 count = blk_rq_map_sg(req->q, req, sdb->table.sgl); 1021 BUG_ON(count > sdb->table.nents); 1022 sdb->table.nents = count; 1023 if (blk_pc_request(req)) 1024 sdb->length = req->data_len; 1025 else 1026 sdb->length = req->nr_sectors << 9; 1027 return BLKPREP_OK; 1028} 1029 1030/* 1031 * Function: scsi_init_io() 1032 * 1033 * Purpose: SCSI I/O initialize function. 1034 * 1035 * Arguments: cmd - Command descriptor we wish to initialize 1036 * 1037 * Returns: 0 on success 1038 * BLKPREP_DEFER if the failure is retryable 1039 * BLKPREP_KILL if the failure is fatal 1040 */ 1041int scsi_init_io(struct scsi_cmnd *cmd, gfp_t gfp_mask) 1042{ 1043 int error = scsi_init_sgtable(cmd->request, &cmd->sdb, gfp_mask); 1044 if (error) 1045 goto err_exit; 1046 1047 if (blk_bidi_rq(cmd->request)) { 1048 struct scsi_data_buffer *bidi_sdb = kmem_cache_zalloc( 1049 scsi_bidi_sdb_cache, GFP_ATOMIC); 1050 if (!bidi_sdb) { 1051 error = BLKPREP_DEFER; 1052 goto err_exit; 1053 } 1054 1055 cmd->request->next_rq->special = bidi_sdb; 1056 error = scsi_init_sgtable(cmd->request->next_rq, bidi_sdb, 1057 GFP_ATOMIC); 1058 if (error) 1059 goto err_exit; 1060 } 1061 1062 return BLKPREP_OK ; 1063 1064err_exit: 1065 scsi_release_buffers(cmd); 1066 if (error == BLKPREP_KILL) 1067 scsi_put_command(cmd); 1068 else /* BLKPREP_DEFER */ 1069 scsi_unprep_request(cmd->request); 1070 1071 return error; 1072} 1073EXPORT_SYMBOL(scsi_init_io); 1074 1075static struct scsi_cmnd *scsi_get_cmd_from_req(struct scsi_device *sdev, 1076 struct request *req) 1077{ 1078 struct scsi_cmnd *cmd; 1079 1080 if (!req->special) { 1081 cmd = scsi_get_command(sdev, GFP_ATOMIC); 1082 if (unlikely(!cmd)) 1083 return NULL; 1084 req->special = cmd; 1085 } else { 1086 cmd = req->special; 1087 } 1088 1089 /* pull a tag out of the request if we have one */ 1090 cmd->tag = req->tag; 1091 cmd->request = req; 1092 1093 return cmd; 1094} 1095 1096int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req) 1097{ 1098 struct scsi_cmnd *cmd; 1099 int ret = scsi_prep_state_check(sdev, req); 1100 1101 if (ret != BLKPREP_OK) 1102 return ret; 1103 1104 cmd = scsi_get_cmd_from_req(sdev, req); 1105 if (unlikely(!cmd)) 1106 return BLKPREP_DEFER; 1107 1108 /* 1109 * BLOCK_PC requests may transfer data, in which case they must 1110 * a bio attached to them. Or they might contain a SCSI command 1111 * that does not transfer data, in which case they may optionally 1112 * submit a request without an attached bio. 1113 */ 1114 if (req->bio) { 1115 int ret; 1116 1117 BUG_ON(!req->nr_phys_segments); 1118 1119 ret = scsi_init_io(cmd, GFP_ATOMIC); 1120 if (unlikely(ret)) 1121 return ret; 1122 } else { 1123 BUG_ON(req->data_len); 1124 BUG_ON(req->data); 1125 1126 memset(&cmd->sdb, 0, sizeof(cmd->sdb)); 1127 req->buffer = NULL; 1128 } 1129 1130 BUILD_BUG_ON(sizeof(req->cmd) > sizeof(cmd->cmnd)); 1131 memcpy(cmd->cmnd, req->cmd, sizeof(cmd->cmnd)); 1132 cmd->cmd_len = req->cmd_len; 1133 if (!req->data_len) 1134 cmd->sc_data_direction = DMA_NONE; 1135 else if (rq_data_dir(req) == WRITE) 1136 cmd->sc_data_direction = DMA_TO_DEVICE; 1137 else 1138 cmd->sc_data_direction = DMA_FROM_DEVICE; 1139 1140 cmd->transfersize = req->data_len; 1141 cmd->allowed = req->retries; 1142 cmd->timeout_per_command = req->timeout; 1143 return BLKPREP_OK; 1144} 1145EXPORT_SYMBOL(scsi_setup_blk_pc_cmnd); 1146 1147/* 1148 * Setup a REQ_TYPE_FS command. These are simple read/write request 1149 * from filesystems that still need to be translated to SCSI CDBs from 1150 * the ULD. 1151 */ 1152int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct request *req) 1153{ 1154 struct scsi_cmnd *cmd; 1155 int ret = scsi_prep_state_check(sdev, req); 1156 1157 if (ret != BLKPREP_OK) 1158 return ret; 1159 /* 1160 * Filesystem requests must transfer data. 1161 */ 1162 BUG_ON(!req->nr_phys_segments); 1163 1164 cmd = scsi_get_cmd_from_req(sdev, req); 1165 if (unlikely(!cmd)) 1166 return BLKPREP_DEFER; 1167 1168 return scsi_init_io(cmd, GFP_ATOMIC); 1169} 1170EXPORT_SYMBOL(scsi_setup_fs_cmnd); 1171 1172int scsi_prep_state_check(struct scsi_device *sdev, struct request *req) 1173{ 1174 int ret = BLKPREP_OK; 1175 1176 /* 1177 * If the device is not in running state we will reject some 1178 * or all commands. 1179 */ 1180 if (unlikely(sdev->sdev_state != SDEV_RUNNING)) { 1181 switch (sdev->sdev_state) { 1182 case SDEV_OFFLINE: 1183 /* 1184 * If the device is offline we refuse to process any 1185 * commands. The device must be brought online 1186 * before trying any recovery commands. 1187 */ 1188 sdev_printk(KERN_ERR, sdev, 1189 "rejecting I/O to offline device\n"); 1190 ret = BLKPREP_KILL; 1191 break; 1192 case SDEV_DEL: 1193 /* 1194 * If the device is fully deleted, we refuse to 1195 * process any commands as well. 1196 */ 1197 sdev_printk(KERN_ERR, sdev, 1198 "rejecting I/O to dead device\n"); 1199 ret = BLKPREP_KILL; 1200 break; 1201 case SDEV_QUIESCE: 1202 case SDEV_BLOCK: 1203 /* 1204 * If the devices is blocked we defer normal commands. 1205 */ 1206 if (!(req->cmd_flags & REQ_PREEMPT)) 1207 ret = BLKPREP_DEFER; 1208 break; 1209 default: 1210 /* 1211 * For any other not fully online state we only allow 1212 * special commands. In particular any user initiated 1213 * command is not allowed. 1214 */ 1215 if (!(req->cmd_flags & REQ_PREEMPT)) 1216 ret = BLKPREP_KILL; 1217 break; 1218 } 1219 } 1220 return ret; 1221} 1222EXPORT_SYMBOL(scsi_prep_state_check); 1223 1224int scsi_prep_return(struct request_queue *q, struct request *req, int ret) 1225{ 1226 struct scsi_device *sdev = q->queuedata; 1227 1228 switch (ret) { 1229 case BLKPREP_KILL: 1230 req->errors = DID_NO_CONNECT << 16; 1231 /* release the command and kill it */ 1232 if (req->special) { 1233 struct scsi_cmnd *cmd = req->special; 1234 scsi_release_buffers(cmd); 1235 scsi_put_command(cmd); 1236 req->special = NULL; 1237 } 1238 break; 1239 case BLKPREP_DEFER: 1240 /* 1241 * If we defer, the elv_next_request() returns NULL, but the 1242 * queue must be restarted, so we plug here if no returning 1243 * command will automatically do that. 1244 */ 1245 if (sdev->device_busy == 0) 1246 blk_plug_device(q); 1247 break; 1248 default: 1249 req->cmd_flags |= REQ_DONTPREP; 1250 } 1251 1252 return ret; 1253} 1254EXPORT_SYMBOL(scsi_prep_return); 1255 1256int scsi_prep_fn(struct request_queue *q, struct request *req) 1257{ 1258 struct scsi_device *sdev = q->queuedata; 1259 int ret = BLKPREP_KILL; 1260 1261 if (req->cmd_type == REQ_TYPE_BLOCK_PC) 1262 ret = scsi_setup_blk_pc_cmnd(sdev, req); 1263 return scsi_prep_return(q, req, ret); 1264} 1265 1266/* 1267 * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else 1268 * return 0. 1269 * 1270 * Called with the queue_lock held. 1271 */ 1272static inline int scsi_dev_queue_ready(struct request_queue *q, 1273 struct scsi_device *sdev) 1274{ 1275 if (sdev->device_busy >= sdev->queue_depth) 1276 return 0; 1277 if (sdev->device_busy == 0 && sdev->device_blocked) { 1278 /* 1279 * unblock after device_blocked iterates to zero 1280 */ 1281 if (--sdev->device_blocked == 0) { 1282 SCSI_LOG_MLQUEUE(3, 1283 sdev_printk(KERN_INFO, sdev, 1284 "unblocking device at zero depth\n")); 1285 } else { 1286 blk_plug_device(q); 1287 return 0; 1288 } 1289 } 1290 if (sdev->device_blocked) 1291 return 0; 1292 1293 return 1; 1294} 1295 1296/* 1297 * scsi_host_queue_ready: if we can send requests to shost, return 1 else 1298 * return 0. We must end up running the queue again whenever 0 is 1299 * returned, else IO can hang. 1300 * 1301 * Called with host_lock held. 1302 */ 1303static inline int scsi_host_queue_ready(struct request_queue *q, 1304 struct Scsi_Host *shost, 1305 struct scsi_device *sdev) 1306{ 1307 if (scsi_host_in_recovery(shost)) 1308 return 0; 1309 if (shost->host_busy == 0 && shost->host_blocked) { 1310 /* 1311 * unblock after host_blocked iterates to zero 1312 */ 1313 if (--shost->host_blocked == 0) { 1314 SCSI_LOG_MLQUEUE(3, 1315 printk("scsi%d unblocking host at zero depth\n", 1316 shost->host_no)); 1317 } else { 1318 blk_plug_device(q); 1319 return 0; 1320 } 1321 } 1322 if ((shost->can_queue > 0 && shost->host_busy >= shost->can_queue) || 1323 shost->host_blocked || shost->host_self_blocked) { 1324 if (list_empty(&sdev->starved_entry)) 1325 list_add_tail(&sdev->starved_entry, &shost->starved_list); 1326 return 0; 1327 } 1328 1329 /* We're OK to process the command, so we can't be starved */ 1330 if (!list_empty(&sdev->starved_entry)) 1331 list_del_init(&sdev->starved_entry); 1332 1333 return 1; 1334} 1335 1336/* 1337 * Kill a request for a dead device 1338 */ 1339static void scsi_kill_request(struct request *req, struct request_queue *q) 1340{ 1341 struct scsi_cmnd *cmd = req->special; 1342 struct scsi_device *sdev = cmd->device; 1343 struct Scsi_Host *shost = sdev->host; 1344 1345 blkdev_dequeue_request(req); 1346 1347 if (unlikely(cmd == NULL)) { 1348 printk(KERN_CRIT "impossible request in %s.\n", 1349 __FUNCTION__); 1350 BUG(); 1351 } 1352 1353 scsi_init_cmd_errh(cmd); 1354 cmd->result = DID_NO_CONNECT << 16; 1355 atomic_inc(&cmd->device->iorequest_cnt); 1356 1357 /* 1358 * SCSI request completion path will do scsi_device_unbusy(), 1359 * bump busy counts. To bump the counters, we need to dance 1360 * with the locks as normal issue path does. 1361 */ 1362 sdev->device_busy++; 1363 spin_unlock(sdev->request_queue->queue_lock); 1364 spin_lock(shost->host_lock); 1365 shost->host_busy++; 1366 spin_unlock(shost->host_lock); 1367 spin_lock(sdev->request_queue->queue_lock); 1368 1369 __scsi_done(cmd); 1370} 1371 1372static void scsi_softirq_done(struct request *rq) 1373{ 1374 struct scsi_cmnd *cmd = rq->completion_data; 1375 unsigned long wait_for = (cmd->allowed + 1) * cmd->timeout_per_command; 1376 int disposition; 1377 1378 INIT_LIST_HEAD(&cmd->eh_entry); 1379 1380 disposition = scsi_decide_disposition(cmd); 1381 if (disposition != SUCCESS && 1382 time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) { 1383 sdev_printk(KERN_ERR, cmd->device, 1384 "timing out command, waited %lus\n", 1385 wait_for/HZ); 1386 disposition = SUCCESS; 1387 } 1388 1389 scsi_log_completion(cmd, disposition); 1390 1391 switch (disposition) { 1392 case SUCCESS: 1393 scsi_finish_command(cmd); 1394 break; 1395 case NEEDS_RETRY: 1396 scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY); 1397 break; 1398 case ADD_TO_MLQUEUE: 1399 scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY); 1400 break; 1401 default: 1402 if (!scsi_eh_scmd_add(cmd, 0)) 1403 scsi_finish_command(cmd); 1404 } 1405} 1406 1407/* 1408 * Function: scsi_request_fn() 1409 * 1410 * Purpose: Main strategy routine for SCSI. 1411 * 1412 * Arguments: q - Pointer to actual queue. 1413 * 1414 * Returns: Nothing 1415 * 1416 * Lock status: IO request lock assumed to be held when called. 1417 */ 1418static void scsi_request_fn(struct request_queue *q) 1419{ 1420 struct scsi_device *sdev = q->queuedata; 1421 struct Scsi_Host *shost; 1422 struct scsi_cmnd *cmd; 1423 struct request *req; 1424 1425 if (!sdev) { 1426 printk("scsi: killing requests for dead queue\n"); 1427 while ((req = elv_next_request(q)) != NULL) 1428 scsi_kill_request(req, q); 1429 return; 1430 } 1431 1432 if(!get_device(&sdev->sdev_gendev)) 1433 /* We must be tearing the block queue down already */ 1434 return; 1435 1436 /* 1437 * To start with, we keep looping until the queue is empty, or until 1438 * the host is no longer able to accept any more requests. 1439 */ 1440 shost = sdev->host; 1441 while (!blk_queue_plugged(q)) { 1442 int rtn; 1443 /* 1444 * get next queueable request. We do this early to make sure 1445 * that the request is fully prepared even if we cannot 1446 * accept it. 1447 */ 1448 req = elv_next_request(q); 1449 if (!req || !scsi_dev_queue_ready(q, sdev)) 1450 break; 1451 1452 if (unlikely(!scsi_device_online(sdev))) { 1453 sdev_printk(KERN_ERR, sdev, 1454 "rejecting I/O to offline device\n"); 1455 scsi_kill_request(req, q); 1456 continue; 1457 } 1458 1459 1460 /* 1461 * Remove the request from the request list. 1462 */ 1463 if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req))) 1464 blkdev_dequeue_request(req); 1465 sdev->device_busy++; 1466 1467 spin_unlock(q->queue_lock); 1468 cmd = req->special; 1469 if (unlikely(cmd == NULL)) { 1470 printk(KERN_CRIT "impossible request in %s.\n" 1471 "please mail a stack trace to " 1472 "linux-scsi@vger.kernel.org\n", 1473 __FUNCTION__); 1474 blk_dump_rq_flags(req, "foo"); 1475 BUG(); 1476 } 1477 spin_lock(shost->host_lock); 1478 1479 if (!scsi_host_queue_ready(q, shost, sdev)) 1480 goto not_ready; 1481 if (scsi_target(sdev)->single_lun) { 1482 if (scsi_target(sdev)->starget_sdev_user && 1483 scsi_target(sdev)->starget_sdev_user != sdev) 1484 goto not_ready; 1485 scsi_target(sdev)->starget_sdev_user = sdev; 1486 } 1487 shost->host_busy++; 1488 1489 /* 1490 * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will 1491 * take the lock again. 1492 */ 1493 spin_unlock_irq(shost->host_lock); 1494 1495 /* 1496 * Finally, initialize any error handling parameters, and set up 1497 * the timers for timeouts. 1498 */ 1499 scsi_init_cmd_errh(cmd); 1500 1501 /* 1502 * Dispatch the command to the low-level driver. 1503 */ 1504 rtn = scsi_dispatch_cmd(cmd); 1505 spin_lock_irq(q->queue_lock); 1506 if(rtn) { 1507 /* we're refusing the command; because of 1508 * the way locks get dropped, we need to 1509 * check here if plugging is required */ 1510 if(sdev->device_busy == 0) 1511 blk_plug_device(q); 1512 1513 break; 1514 } 1515 } 1516 1517 goto out; 1518 1519 not_ready: 1520 spin_unlock_irq(shost->host_lock); 1521 1522 /* 1523 * lock q, handle tag, requeue req, and decrement device_busy. We 1524 * must return with queue_lock held. 1525 * 1526 * Decrementing device_busy without checking it is OK, as all such 1527 * cases (host limits or settings) should run the queue at some 1528 * later time. 1529 */ 1530 spin_lock_irq(q->queue_lock); 1531 blk_requeue_request(q, req); 1532 sdev->device_busy--; 1533 if(sdev->device_busy == 0) 1534 blk_plug_device(q); 1535 out: 1536 /* must be careful here...if we trigger the ->remove() function 1537 * we cannot be holding the q lock */ 1538 spin_unlock_irq(q->queue_lock); 1539 put_device(&sdev->sdev_gendev); 1540 spin_lock_irq(q->queue_lock); 1541} 1542 1543u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost) 1544{ 1545 struct device *host_dev; 1546 u64 bounce_limit = 0xffffffff; 1547 1548 if (shost->unchecked_isa_dma) 1549 return BLK_BOUNCE_ISA; 1550 /* 1551 * Platforms with virtual-DMA translation 1552 * hardware have no practical limit. 1553 */ 1554 if (!PCI_DMA_BUS_IS_PHYS) 1555 return BLK_BOUNCE_ANY; 1556 1557 host_dev = scsi_get_device(shost); 1558 if (host_dev && host_dev->dma_mask) 1559 bounce_limit = *host_dev->dma_mask; 1560 1561 return bounce_limit; 1562} 1563EXPORT_SYMBOL(scsi_calculate_bounce_limit); 1564 1565struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost, 1566 request_fn_proc *request_fn) 1567{ 1568 struct request_queue *q; 1569 struct device *dev = shost->shost_gendev.parent; 1570 1571 q = blk_init_queue(request_fn, NULL); 1572 if (!q) 1573 return NULL; 1574 1575 /* 1576 * this limit is imposed by hardware restrictions 1577 */ 1578 blk_queue_max_hw_segments(q, shost->sg_tablesize); 1579 blk_queue_max_phys_segments(q, SCSI_MAX_SG_CHAIN_SEGMENTS); 1580 1581 blk_queue_max_sectors(q, shost->max_sectors); 1582 blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost)); 1583 blk_queue_segment_boundary(q, shost->dma_boundary); 1584 dma_set_seg_boundary(dev, shost->dma_boundary); 1585 1586 blk_queue_max_segment_size(q, dma_get_max_seg_size(dev)); 1587 1588 if (!shost->use_clustering) 1589 clear_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags); 1590 1591 /* 1592 * set a reasonable default alignment on word boundaries: the 1593 * host and device may alter it using 1594 * blk_queue_update_dma_alignment() later. 1595 */ 1596 blk_queue_dma_alignment(q, 0x03); 1597 1598 return q; 1599} 1600EXPORT_SYMBOL(__scsi_alloc_queue); 1601 1602struct request_queue *scsi_alloc_queue(struct scsi_device *sdev) 1603{ 1604 struct request_queue *q; 1605 1606 q = __scsi_alloc_queue(sdev->host, scsi_request_fn); 1607 if (!q) 1608 return NULL; 1609 1610 blk_queue_prep_rq(q, scsi_prep_fn); 1611 blk_queue_softirq_done(q, scsi_softirq_done); 1612 return q; 1613} 1614 1615void scsi_free_queue(struct request_queue *q) 1616{ 1617 blk_cleanup_queue(q); 1618} 1619 1620/* 1621 * Function: scsi_block_requests() 1622 * 1623 * Purpose: Utility function used by low-level drivers to prevent further 1624 * commands from being queued to the device. 1625 * 1626 * Arguments: shost - Host in question 1627 * 1628 * Returns: Nothing 1629 * 1630 * Lock status: No locks are assumed held. 1631 * 1632 * Notes: There is no timer nor any other means by which the requests 1633 * get unblocked other than the low-level driver calling 1634 * scsi_unblock_requests(). 1635 */ 1636void scsi_block_requests(struct Scsi_Host *shost) 1637{ 1638 shost->host_self_blocked = 1; 1639} 1640EXPORT_SYMBOL(scsi_block_requests); 1641 1642/* 1643 * Function: scsi_unblock_requests() 1644 * 1645 * Purpose: Utility function used by low-level drivers to allow further 1646 * commands from being queued to the device. 1647 * 1648 * Arguments: shost - Host in question 1649 * 1650 * Returns: Nothing 1651 * 1652 * Lock status: No locks are assumed held. 1653 * 1654 * Notes: There is no timer nor any other means by which the requests 1655 * get unblocked other than the low-level driver calling 1656 * scsi_unblock_requests(). 1657 * 1658 * This is done as an API function so that changes to the 1659 * internals of the scsi mid-layer won't require wholesale 1660 * changes to drivers that use this feature. 1661 */ 1662void scsi_unblock_requests(struct Scsi_Host *shost) 1663{ 1664 shost->host_self_blocked = 0; 1665 scsi_run_host_queues(shost); 1666} 1667EXPORT_SYMBOL(scsi_unblock_requests); 1668 1669int __init scsi_init_queue(void) 1670{ 1671 int i; 1672 1673 scsi_io_context_cache = kmem_cache_create("scsi_io_context", 1674 sizeof(struct scsi_io_context), 1675 0, 0, NULL); 1676 if (!scsi_io_context_cache) { 1677 printk(KERN_ERR "SCSI: can't init scsi io context cache\n"); 1678 return -ENOMEM; 1679 } 1680 1681 scsi_bidi_sdb_cache = kmem_cache_create("scsi_bidi_sdb", 1682 sizeof(struct scsi_data_buffer), 1683 0, 0, NULL); 1684 if (!scsi_bidi_sdb_cache) { 1685 printk(KERN_ERR "SCSI: can't init scsi bidi sdb cache\n"); 1686 goto cleanup_io_context; 1687 } 1688 1689 for (i = 0; i < SG_MEMPOOL_NR; i++) { 1690 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i; 1691 int size = sgp->size * sizeof(struct scatterlist); 1692 1693 sgp->slab = kmem_cache_create(sgp->name, size, 0, 1694 SLAB_HWCACHE_ALIGN, NULL); 1695 if (!sgp->slab) { 1696 printk(KERN_ERR "SCSI: can't init sg slab %s\n", 1697 sgp->name); 1698 goto cleanup_bidi_sdb; 1699 } 1700 1701 sgp->pool = mempool_create_slab_pool(SG_MEMPOOL_SIZE, 1702 sgp->slab); 1703 if (!sgp->pool) { 1704 printk(KERN_ERR "SCSI: can't init sg mempool %s\n", 1705 sgp->name); 1706 goto cleanup_bidi_sdb; 1707 } 1708 } 1709 1710 return 0; 1711 1712cleanup_bidi_sdb: 1713 for (i = 0; i < SG_MEMPOOL_NR; i++) { 1714 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i; 1715 if (sgp->pool) 1716 mempool_destroy(sgp->pool); 1717 if (sgp->slab) 1718 kmem_cache_destroy(sgp->slab); 1719 } 1720 kmem_cache_destroy(scsi_bidi_sdb_cache); 1721cleanup_io_context: 1722 kmem_cache_destroy(scsi_io_context_cache); 1723 1724 return -ENOMEM; 1725} 1726 1727void scsi_exit_queue(void) 1728{ 1729 int i; 1730 1731 kmem_cache_destroy(scsi_io_context_cache); 1732 kmem_cache_destroy(scsi_bidi_sdb_cache); 1733 1734 for (i = 0; i < SG_MEMPOOL_NR; i++) { 1735 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i; 1736 mempool_destroy(sgp->pool); 1737 kmem_cache_destroy(sgp->slab); 1738 } 1739} 1740 1741/** 1742 * scsi_mode_select - issue a mode select 1743 * @sdev: SCSI device to be queried 1744 * @pf: Page format bit (1 == standard, 0 == vendor specific) 1745 * @sp: Save page bit (0 == don't save, 1 == save) 1746 * @modepage: mode page being requested 1747 * @buffer: request buffer (may not be smaller than eight bytes) 1748 * @len: length of request buffer. 1749 * @timeout: command timeout 1750 * @retries: number of retries before failing 1751 * @data: returns a structure abstracting the mode header data 1752 * @sshdr: place to put sense data (or NULL if no sense to be collected). 1753 * must be SCSI_SENSE_BUFFERSIZE big. 1754 * 1755 * Returns zero if successful; negative error number or scsi 1756 * status on error 1757 * 1758 */ 1759int 1760scsi_mode_select(struct scsi_device *sdev, int pf, int sp, int modepage, 1761 unsigned char *buffer, int len, int timeout, int retries, 1762 struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr) 1763{ 1764 unsigned char cmd[10]; 1765 unsigned char *real_buffer; 1766 int ret; 1767 1768 memset(cmd, 0, sizeof(cmd)); 1769 cmd[1] = (pf ? 0x10 : 0) | (sp ? 0x01 : 0); 1770 1771 if (sdev->use_10_for_ms) { 1772 if (len > 65535) 1773 return -EINVAL; 1774 real_buffer = kmalloc(8 + len, GFP_KERNEL); 1775 if (!real_buffer) 1776 return -ENOMEM; 1777 memcpy(real_buffer + 8, buffer, len); 1778 len += 8; 1779 real_buffer[0] = 0; 1780 real_buffer[1] = 0; 1781 real_buffer[2] = data->medium_type; 1782 real_buffer[3] = data->device_specific; 1783 real_buffer[4] = data->longlba ? 0x01 : 0; 1784 real_buffer[5] = 0; 1785 real_buffer[6] = data->block_descriptor_length >> 8; 1786 real_buffer[7] = data->block_descriptor_length; 1787 1788 cmd[0] = MODE_SELECT_10; 1789 cmd[7] = len >> 8; 1790 cmd[8] = len; 1791 } else { 1792 if (len > 255 || data->block_descriptor_length > 255 || 1793 data->longlba) 1794 return -EINVAL; 1795 1796 real_buffer = kmalloc(4 + len, GFP_KERNEL); 1797 if (!real_buffer) 1798 return -ENOMEM; 1799 memcpy(real_buffer + 4, buffer, len); 1800 len += 4; 1801 real_buffer[0] = 0; 1802 real_buffer[1] = data->medium_type; 1803 real_buffer[2] = data->device_specific; 1804 real_buffer[3] = data->block_descriptor_length; 1805 1806 1807 cmd[0] = MODE_SELECT; 1808 cmd[4] = len; 1809 } 1810 1811 ret = scsi_execute_req(sdev, cmd, DMA_TO_DEVICE, real_buffer, len, 1812 sshdr, timeout, retries); 1813 kfree(real_buffer); 1814 return ret; 1815} 1816EXPORT_SYMBOL_GPL(scsi_mode_select); 1817 1818/** 1819 * scsi_mode_sense - issue a mode sense, falling back from 10 to six bytes if necessary. 1820 * @sdev: SCSI device to be queried 1821 * @dbd: set if mode sense will allow block descriptors to be returned 1822 * @modepage: mode page being requested 1823 * @buffer: request buffer (may not be smaller than eight bytes) 1824 * @len: length of request buffer. 1825 * @timeout: command timeout 1826 * @retries: number of retries before failing 1827 * @data: returns a structure abstracting the mode header data 1828 * @sshdr: place to put sense data (or NULL if no sense to be collected). 1829 * must be SCSI_SENSE_BUFFERSIZE big. 1830 * 1831 * Returns zero if unsuccessful, or the header offset (either 4 1832 * or 8 depending on whether a six or ten byte command was 1833 * issued) if successful. 1834 */ 1835int 1836scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage, 1837 unsigned char *buffer, int len, int timeout, int retries, 1838 struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr) 1839{ 1840 unsigned char cmd[12]; 1841 int use_10_for_ms; 1842 int header_length; 1843 int result; 1844 struct scsi_sense_hdr my_sshdr; 1845 1846 memset(data, 0, sizeof(*data)); 1847 memset(&cmd[0], 0, 12); 1848 cmd[1] = dbd & 0x18; /* allows DBD and LLBA bits */ 1849 cmd[2] = modepage; 1850 1851 /* caller might not be interested in sense, but we need it */ 1852 if (!sshdr) 1853 sshdr = &my_sshdr; 1854 1855 retry: 1856 use_10_for_ms = sdev->use_10_for_ms; 1857 1858 if (use_10_for_ms) { 1859 if (len < 8) 1860 len = 8; 1861 1862 cmd[0] = MODE_SENSE_10; 1863 cmd[8] = len; 1864 header_length = 8; 1865 } else { 1866 if (len < 4) 1867 len = 4; 1868 1869 cmd[0] = MODE_SENSE; 1870 cmd[4] = len; 1871 header_length = 4; 1872 } 1873 1874 memset(buffer, 0, len); 1875 1876 result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len, 1877 sshdr, timeout, retries); 1878 1879 /* This code looks awful: what it's doing is making sure an 1880 * ILLEGAL REQUEST sense return identifies the actual command 1881 * byte as the problem. MODE_SENSE commands can return 1882 * ILLEGAL REQUEST if the code page isn't supported */ 1883 1884 if (use_10_for_ms && !scsi_status_is_good(result) && 1885 (driver_byte(result) & DRIVER_SENSE)) { 1886 if (scsi_sense_valid(sshdr)) { 1887 if ((sshdr->sense_key == ILLEGAL_REQUEST) && 1888 (sshdr->asc == 0x20) && (sshdr->ascq == 0)) { 1889 /* 1890 * Invalid command operation code 1891 */ 1892 sdev->use_10_for_ms = 0; 1893 goto retry; 1894 } 1895 } 1896 } 1897 1898 if(scsi_status_is_good(result)) { 1899 if (unlikely(buffer[0] == 0x86 && buffer[1] == 0x0b && 1900 (modepage == 6 || modepage == 8))) { 1901 /* Initio breakage? */ 1902 header_length = 0; 1903 data->length = 13; 1904 data->medium_type = 0; 1905 data->device_specific = 0; 1906 data->longlba = 0; 1907 data->block_descriptor_length = 0; 1908 } else if(use_10_for_ms) { 1909 data->length = buffer[0]*256 + buffer[1] + 2; 1910 data->medium_type = buffer[2]; 1911 data->device_specific = buffer[3]; 1912 data->longlba = buffer[4] & 0x01; 1913 data->block_descriptor_length = buffer[6]*256 1914 + buffer[7]; 1915 } else { 1916 data->length = buffer[0] + 1; 1917 data->medium_type = buffer[1]; 1918 data->device_specific = buffer[2]; 1919 data->block_descriptor_length = buffer[3]; 1920 } 1921 data->header_length = header_length; 1922 } 1923 1924 return result; 1925} 1926EXPORT_SYMBOL(scsi_mode_sense); 1927 1928/** 1929 * scsi_test_unit_ready - test if unit is ready 1930 * @sdev: scsi device to change the state of. 1931 * @timeout: command timeout 1932 * @retries: number of retries before failing 1933 * @sshdr_external: Optional pointer to struct scsi_sense_hdr for 1934 * returning sense. Make sure that this is cleared before passing 1935 * in. 1936 * 1937 * Returns zero if unsuccessful or an error if TUR failed. For 1938 * removable media, a return of NOT_READY or UNIT_ATTENTION is 1939 * translated to success, with the ->changed flag updated. 1940 **/ 1941int 1942scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries, 1943 struct scsi_sense_hdr *sshdr_external) 1944{ 1945 char cmd[] = { 1946 TEST_UNIT_READY, 0, 0, 0, 0, 0, 1947 }; 1948 struct scsi_sense_hdr *sshdr; 1949 int result; 1950 1951 if (!sshdr_external) 1952 sshdr = kzalloc(sizeof(*sshdr), GFP_KERNEL); 1953 else 1954 sshdr = sshdr_external; 1955 1956 /* try to eat the UNIT_ATTENTION if there are enough retries */ 1957 do { 1958 result = scsi_execute_req(sdev, cmd, DMA_NONE, NULL, 0, sshdr, 1959 timeout, retries); 1960 } while ((driver_byte(result) & DRIVER_SENSE) && 1961 sshdr && sshdr->sense_key == UNIT_ATTENTION && 1962 --retries); 1963 1964 if (!sshdr) 1965 /* could not allocate sense buffer, so can't process it */ 1966 return result; 1967 1968 if ((driver_byte(result) & DRIVER_SENSE) && sdev->removable) { 1969 1970 if ((scsi_sense_valid(sshdr)) && 1971 ((sshdr->sense_key == UNIT_ATTENTION) || 1972 (sshdr->sense_key == NOT_READY))) { 1973 sdev->changed = 1; 1974 result = 0; 1975 } 1976 } 1977 if (!sshdr_external) 1978 kfree(sshdr); 1979 return result; 1980} 1981EXPORT_SYMBOL(scsi_test_unit_ready); 1982 1983/** 1984 * scsi_device_set_state - Take the given device through the device state model. 1985 * @sdev: scsi device to change the state of. 1986 * @state: state to change to. 1987 * 1988 * Returns zero if unsuccessful or an error if the requested 1989 * transition is illegal. 1990 */ 1991int 1992scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state) 1993{ 1994 enum scsi_device_state oldstate = sdev->sdev_state; 1995 1996 if (state == oldstate) 1997 return 0; 1998 1999 switch (state) { 2000 case SDEV_CREATED: 2001 /* There are no legal states that come back to 2002 * created. This is the manually initialised start 2003 * state */ 2004 goto illegal; 2005 2006 case SDEV_RUNNING: 2007 switch (oldstate) { 2008 case SDEV_CREATED: 2009 case SDEV_OFFLINE: 2010 case SDEV_QUIESCE: 2011 case SDEV_BLOCK: 2012 break; 2013 default: 2014 goto illegal; 2015 } 2016 break; 2017 2018 case SDEV_QUIESCE: 2019 switch (oldstate) { 2020 case SDEV_RUNNING: 2021 case SDEV_OFFLINE: 2022 break; 2023 default: 2024 goto illegal; 2025 } 2026 break; 2027 2028 case SDEV_OFFLINE: 2029 switch (oldstate) { 2030 case SDEV_CREATED: 2031 case SDEV_RUNNING: 2032 case SDEV_QUIESCE: 2033 case SDEV_BLOCK: 2034 break; 2035 default: 2036 goto illegal; 2037 } 2038 break; 2039 2040 case SDEV_BLOCK: 2041 switch (oldstate) { 2042 case SDEV_CREATED: 2043 case SDEV_RUNNING: 2044 break; 2045 default: 2046 goto illegal; 2047 } 2048 break; 2049 2050 case SDEV_CANCEL: 2051 switch (oldstate) { 2052 case SDEV_CREATED: 2053 case SDEV_RUNNING: 2054 case SDEV_QUIESCE: 2055 case SDEV_OFFLINE: 2056 case SDEV_BLOCK: 2057 break; 2058 default: 2059 goto illegal; 2060 } 2061 break; 2062 2063 case SDEV_DEL: 2064 switch (oldstate) { 2065 case SDEV_CREATED: 2066 case SDEV_RUNNING: 2067 case SDEV_OFFLINE: 2068 case SDEV_CANCEL: 2069 break; 2070 default: 2071 goto illegal; 2072 } 2073 break; 2074 2075 } 2076 sdev->sdev_state = state; 2077 return 0; 2078 2079 illegal: 2080 SCSI_LOG_ERROR_RECOVERY(1, 2081 sdev_printk(KERN_ERR, sdev, 2082 "Illegal state transition %s->%s\n", 2083 scsi_device_state_name(oldstate), 2084 scsi_device_state_name(state)) 2085 ); 2086 return -EINVAL; 2087} 2088EXPORT_SYMBOL(scsi_device_set_state); 2089 2090/** 2091 * sdev_evt_emit - emit a single SCSI device uevent 2092 * @sdev: associated SCSI device 2093 * @evt: event to emit 2094 * 2095 * Send a single uevent (scsi_event) to the associated scsi_device. 2096 */ 2097static void scsi_evt_emit(struct scsi_device *sdev, struct scsi_event *evt) 2098{ 2099 int idx = 0; 2100 char *envp[3]; 2101 2102 switch (evt->evt_type) { 2103 case SDEV_EVT_MEDIA_CHANGE: 2104 envp[idx++] = "SDEV_MEDIA_CHANGE=1"; 2105 break; 2106 2107 default: 2108 /* do nothing */ 2109 break; 2110 } 2111 2112 envp[idx++] = NULL; 2113 2114 kobject_uevent_env(&sdev->sdev_gendev.kobj, KOBJ_CHANGE, envp); 2115} 2116 2117/** 2118 * sdev_evt_thread - send a uevent for each scsi event 2119 * @work: work struct for scsi_device 2120 * 2121 * Dispatch queued events to their associated scsi_device kobjects 2122 * as uevents. 2123 */ 2124void scsi_evt_thread(struct work_struct *work) 2125{ 2126 struct scsi_device *sdev; 2127 LIST_HEAD(event_list); 2128 2129 sdev = container_of(work, struct scsi_device, event_work); 2130 2131 while (1) { 2132 struct scsi_event *evt; 2133 struct list_head *this, *tmp; 2134 unsigned long flags; 2135 2136 spin_lock_irqsave(&sdev->list_lock, flags); 2137 list_splice_init(&sdev->event_list, &event_list); 2138 spin_unlock_irqrestore(&sdev->list_lock, flags); 2139 2140 if (list_empty(&event_list)) 2141 break; 2142 2143 list_for_each_safe(this, tmp, &event_list) { 2144 evt = list_entry(this, struct scsi_event, node); 2145 list_del(&evt->node); 2146 scsi_evt_emit(sdev, evt); 2147 kfree(evt); 2148 } 2149 } 2150} 2151 2152/** 2153 * sdev_evt_send - send asserted event to uevent thread 2154 * @sdev: scsi_device event occurred on 2155 * @evt: event to send 2156 * 2157 * Assert scsi device event asynchronously. 2158 */ 2159void sdev_evt_send(struct scsi_device *sdev, struct scsi_event *evt) 2160{ 2161 unsigned long flags; 2162 2163#if 0 2164 /* FIXME: currently this check eliminates all media change events 2165 * for polled devices. Need to update to discriminate between AN 2166 * and polled events */ 2167 if (!test_bit(evt->evt_type, sdev->supported_events)) { 2168 kfree(evt); 2169 return; 2170 } 2171#endif 2172 2173 spin_lock_irqsave(&sdev->list_lock, flags); 2174 list_add_tail(&evt->node, &sdev->event_list); 2175 schedule_work(&sdev->event_work); 2176 spin_unlock_irqrestore(&sdev->list_lock, flags); 2177} 2178EXPORT_SYMBOL_GPL(sdev_evt_send); 2179 2180/** 2181 * sdev_evt_alloc - allocate a new scsi event 2182 * @evt_type: type of event to allocate 2183 * @gfpflags: GFP flags for allocation 2184 * 2185 * Allocates and returns a new scsi_event. 2186 */ 2187struct scsi_event *sdev_evt_alloc(enum scsi_device_event evt_type, 2188 gfp_t gfpflags) 2189{ 2190 struct scsi_event *evt = kzalloc(sizeof(struct scsi_event), gfpflags); 2191 if (!evt) 2192 return NULL; 2193 2194 evt->evt_type = evt_type; 2195 INIT_LIST_HEAD(&evt->node); 2196 2197 /* evt_type-specific initialization, if any */ 2198 switch (evt_type) { 2199 case SDEV_EVT_MEDIA_CHANGE: 2200 default: 2201 /* do nothing */ 2202 break; 2203 } 2204 2205 return evt; 2206} 2207EXPORT_SYMBOL_GPL(sdev_evt_alloc); 2208 2209/** 2210 * sdev_evt_send_simple - send asserted event to uevent thread 2211 * @sdev: scsi_device event occurred on 2212 * @evt_type: type of event to send 2213 * @gfpflags: GFP flags for allocation 2214 * 2215 * Assert scsi device event asynchronously, given an event type. 2216 */ 2217void sdev_evt_send_simple(struct scsi_device *sdev, 2218 enum scsi_device_event evt_type, gfp_t gfpflags) 2219{ 2220 struct scsi_event *evt = sdev_evt_alloc(evt_type, gfpflags); 2221 if (!evt) { 2222 sdev_printk(KERN_ERR, sdev, "event %d eaten due to OOM\n", 2223 evt_type); 2224 return; 2225 } 2226 2227 sdev_evt_send(sdev, evt); 2228} 2229EXPORT_SYMBOL_GPL(sdev_evt_send_simple); 2230 2231/** 2232 * scsi_device_quiesce - Block user issued commands. 2233 * @sdev: scsi device to quiesce. 2234 * 2235 * This works by trying to transition to the SDEV_QUIESCE state 2236 * (which must be a legal transition). When the device is in this 2237 * state, only special requests will be accepted, all others will 2238 * be deferred. Since special requests may also be requeued requests, 2239 * a successful return doesn't guarantee the device will be 2240 * totally quiescent. 2241 * 2242 * Must be called with user context, may sleep. 2243 * 2244 * Returns zero if unsuccessful or an error if not. 2245 */ 2246int 2247scsi_device_quiesce(struct scsi_device *sdev) 2248{ 2249 int err = scsi_device_set_state(sdev, SDEV_QUIESCE); 2250 if (err) 2251 return err; 2252 2253 scsi_run_queue(sdev->request_queue); 2254 while (sdev->device_busy) { 2255 msleep_interruptible(200); 2256 scsi_run_queue(sdev->request_queue); 2257 } 2258 return 0; 2259} 2260EXPORT_SYMBOL(scsi_device_quiesce); 2261 2262/** 2263 * scsi_device_resume - Restart user issued commands to a quiesced device. 2264 * @sdev: scsi device to resume. 2265 * 2266 * Moves the device from quiesced back to running and restarts the 2267 * queues. 2268 * 2269 * Must be called with user context, may sleep. 2270 */ 2271void 2272scsi_device_resume(struct scsi_device *sdev) 2273{ 2274 if(scsi_device_set_state(sdev, SDEV_RUNNING)) 2275 return; 2276 scsi_run_queue(sdev->request_queue); 2277} 2278EXPORT_SYMBOL(scsi_device_resume); 2279 2280static void 2281device_quiesce_fn(struct scsi_device *sdev, void *data) 2282{ 2283 scsi_device_quiesce(sdev); 2284} 2285 2286void 2287scsi_target_quiesce(struct scsi_target *starget) 2288{ 2289 starget_for_each_device(starget, NULL, device_quiesce_fn); 2290} 2291EXPORT_SYMBOL(scsi_target_quiesce); 2292 2293static void 2294device_resume_fn(struct scsi_device *sdev, void *data) 2295{ 2296 scsi_device_resume(sdev); 2297} 2298 2299void 2300scsi_target_resume(struct scsi_target *starget) 2301{ 2302 starget_for_each_device(starget, NULL, device_resume_fn); 2303} 2304EXPORT_SYMBOL(scsi_target_resume); 2305 2306/** 2307 * scsi_internal_device_block - internal function to put a device temporarily into the SDEV_BLOCK state 2308 * @sdev: device to block 2309 * 2310 * Block request made by scsi lld's to temporarily stop all 2311 * scsi commands on the specified device. Called from interrupt 2312 * or normal process context. 2313 * 2314 * Returns zero if successful or error if not 2315 * 2316 * Notes: 2317 * This routine transitions the device to the SDEV_BLOCK state 2318 * (which must be a legal transition). When the device is in this 2319 * state, all commands are deferred until the scsi lld reenables 2320 * the device with scsi_device_unblock or device_block_tmo fires. 2321 * This routine assumes the host_lock is held on entry. 2322 */ 2323int 2324scsi_internal_device_block(struct scsi_device *sdev) 2325{ 2326 struct request_queue *q = sdev->request_queue; 2327 unsigned long flags; 2328 int err = 0; 2329 2330 err = scsi_device_set_state(sdev, SDEV_BLOCK); 2331 if (err) 2332 return err; 2333 2334 /* 2335 * The device has transitioned to SDEV_BLOCK. Stop the 2336 * block layer from calling the midlayer with this device's 2337 * request queue. 2338 */ 2339 spin_lock_irqsave(q->queue_lock, flags); 2340 blk_stop_queue(q); 2341 spin_unlock_irqrestore(q->queue_lock, flags); 2342 2343 return 0; 2344} 2345EXPORT_SYMBOL_GPL(scsi_internal_device_block); 2346 2347/** 2348 * scsi_internal_device_unblock - resume a device after a block request 2349 * @sdev: device to resume 2350 * 2351 * Called by scsi lld's or the midlayer to restart the device queue 2352 * for the previously suspended scsi device. Called from interrupt or 2353 * normal process context. 2354 * 2355 * Returns zero if successful or error if not. 2356 * 2357 * Notes: 2358 * This routine transitions the device to the SDEV_RUNNING state 2359 * (which must be a legal transition) allowing the midlayer to 2360 * goose the queue for this device. This routine assumes the 2361 * host_lock is held upon entry. 2362 */ 2363int 2364scsi_internal_device_unblock(struct scsi_device *sdev) 2365{ 2366 struct request_queue *q = sdev->request_queue; 2367 int err; 2368 unsigned long flags; 2369 2370 /* 2371 * Try to transition the scsi device to SDEV_RUNNING 2372 * and goose the device queue if successful. 2373 */ 2374 err = scsi_device_set_state(sdev, SDEV_RUNNING); 2375 if (err) 2376 return err; 2377 2378 spin_lock_irqsave(q->queue_lock, flags); 2379 blk_start_queue(q); 2380 spin_unlock_irqrestore(q->queue_lock, flags); 2381 2382 return 0; 2383} 2384EXPORT_SYMBOL_GPL(scsi_internal_device_unblock); 2385 2386static void 2387device_block(struct scsi_device *sdev, void *data) 2388{ 2389 scsi_internal_device_block(sdev); 2390} 2391 2392static int 2393target_block(struct device *dev, void *data) 2394{ 2395 if (scsi_is_target_device(dev)) 2396 starget_for_each_device(to_scsi_target(dev), NULL, 2397 device_block); 2398 return 0; 2399} 2400 2401void 2402scsi_target_block(struct device *dev) 2403{ 2404 if (scsi_is_target_device(dev)) 2405 starget_for_each_device(to_scsi_target(dev), NULL, 2406 device_block); 2407 else 2408 device_for_each_child(dev, NULL, target_block); 2409} 2410EXPORT_SYMBOL_GPL(scsi_target_block); 2411 2412static void 2413device_unblock(struct scsi_device *sdev, void *data) 2414{ 2415 scsi_internal_device_unblock(sdev); 2416} 2417 2418static int 2419target_unblock(struct device *dev, void *data) 2420{ 2421 if (scsi_is_target_device(dev)) 2422 starget_for_each_device(to_scsi_target(dev), NULL, 2423 device_unblock); 2424 return 0; 2425} 2426 2427void 2428scsi_target_unblock(struct device *dev) 2429{ 2430 if (scsi_is_target_device(dev)) 2431 starget_for_each_device(to_scsi_target(dev), NULL, 2432 device_unblock); 2433 else 2434 device_for_each_child(dev, NULL, target_unblock); 2435} 2436EXPORT_SYMBOL_GPL(scsi_target_unblock); 2437 2438/** 2439 * scsi_kmap_atomic_sg - find and atomically map an sg-elemnt 2440 * @sgl: scatter-gather list 2441 * @sg_count: number of segments in sg 2442 * @offset: offset in bytes into sg, on return offset into the mapped area 2443 * @len: bytes to map, on return number of bytes mapped 2444 * 2445 * Returns virtual address of the start of the mapped page 2446 */ 2447void *scsi_kmap_atomic_sg(struct scatterlist *sgl, int sg_count, 2448 size_t *offset, size_t *len) 2449{ 2450 int i; 2451 size_t sg_len = 0, len_complete = 0; 2452 struct scatterlist *sg; 2453 struct page *page; 2454 2455 WARN_ON(!irqs_disabled()); 2456 2457 for_each_sg(sgl, sg, sg_count, i) { 2458 len_complete = sg_len; /* Complete sg-entries */ 2459 sg_len += sg->length; 2460 if (sg_len > *offset) 2461 break; 2462 } 2463 2464 if (unlikely(i == sg_count)) { 2465 printk(KERN_ERR "%s: Bytes in sg: %zu, requested offset %zu, " 2466 "elements %d\n", 2467 __FUNCTION__, sg_len, *offset, sg_count); 2468 WARN_ON(1); 2469 return NULL; 2470 } 2471 2472 /* Offset starting from the beginning of first page in this sg-entry */ 2473 *offset = *offset - len_complete + sg->offset; 2474 2475 /* Assumption: contiguous pages can be accessed as "page + i" */ 2476 page = nth_page(sg_page(sg), (*offset >> PAGE_SHIFT)); 2477 *offset &= ~PAGE_MASK; 2478 2479 /* Bytes in this sg-entry from *offset to the end of the page */ 2480 sg_len = PAGE_SIZE - *offset; 2481 if (*len > sg_len) 2482 *len = sg_len; 2483 2484 return kmap_atomic(page, KM_BIO_SRC_IRQ); 2485} 2486EXPORT_SYMBOL(scsi_kmap_atomic_sg); 2487 2488/** 2489 * scsi_kunmap_atomic_sg - atomically unmap a virtual address, previously mapped with scsi_kmap_atomic_sg 2490 * @virt: virtual address to be unmapped 2491 */ 2492void scsi_kunmap_atomic_sg(void *virt) 2493{ 2494 kunmap_atomic(virt, KM_BIO_SRC_IRQ); 2495} 2496EXPORT_SYMBOL(scsi_kunmap_atomic_sg); 2497