Loading...
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/export.h>
16#include <linux/mempool.h>
17#include <linux/slab.h>
18#include <linux/init.h>
19#include <linux/pci.h>
20#include <linux/delay.h>
21#include <linux/hardirq.h>
22#include <linux/scatterlist.h>
23
24#include <scsi/scsi.h>
25#include <scsi/scsi_cmnd.h>
26#include <scsi/scsi_dbg.h>
27#include <scsi/scsi_device.h>
28#include <scsi/scsi_driver.h>
29#include <scsi/scsi_eh.h>
30#include <scsi/scsi_host.h>
31
32#include "scsi_priv.h"
33#include "scsi_logging.h"
34
35
36#define SG_MEMPOOL_NR ARRAY_SIZE(scsi_sg_pools)
37#define SG_MEMPOOL_SIZE 2
38
39struct scsi_host_sg_pool {
40 size_t size;
41 char *name;
42 struct kmem_cache *slab;
43 mempool_t *pool;
44};
45
46#define SP(x) { x, "sgpool-" __stringify(x) }
47#if (SCSI_MAX_SG_SEGMENTS < 32)
48#error SCSI_MAX_SG_SEGMENTS is too small (must be 32 or greater)
49#endif
50static struct scsi_host_sg_pool scsi_sg_pools[] = {
51 SP(8),
52 SP(16),
53#if (SCSI_MAX_SG_SEGMENTS > 32)
54 SP(32),
55#if (SCSI_MAX_SG_SEGMENTS > 64)
56 SP(64),
57#if (SCSI_MAX_SG_SEGMENTS > 128)
58 SP(128),
59#if (SCSI_MAX_SG_SEGMENTS > 256)
60#error SCSI_MAX_SG_SEGMENTS is too large (256 MAX)
61#endif
62#endif
63#endif
64#endif
65 SP(SCSI_MAX_SG_SEGMENTS)
66};
67#undef SP
68
69struct kmem_cache *scsi_sdb_cache;
70
71/*
72 * When to reinvoke queueing after a resource shortage. It's 3 msecs to
73 * not change behaviour from the previous unplug mechanism, experimentation
74 * may prove this needs changing.
75 */
76#define SCSI_QUEUE_DELAY 3
77
78/*
79 * Function: scsi_unprep_request()
80 *
81 * Purpose: Remove all preparation done for a request, including its
82 * associated scsi_cmnd, so that it can be requeued.
83 *
84 * Arguments: req - request to unprepare
85 *
86 * Lock status: Assumed that no locks are held upon entry.
87 *
88 * Returns: Nothing.
89 */
90static void scsi_unprep_request(struct request *req)
91{
92 struct scsi_cmnd *cmd = req->special;
93
94 blk_unprep_request(req);
95 req->special = NULL;
96
97 scsi_put_command(cmd);
98}
99
100/**
101 * __scsi_queue_insert - private queue insertion
102 * @cmd: The SCSI command being requeued
103 * @reason: The reason for the requeue
104 * @unbusy: Whether the queue should be unbusied
105 *
106 * This is a private queue insertion. The public interface
107 * scsi_queue_insert() always assumes the queue should be unbusied
108 * because it's always called before the completion. This function is
109 * for a requeue after completion, which should only occur in this
110 * file.
111 */
112static int __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, int unbusy)
113{
114 struct Scsi_Host *host = cmd->device->host;
115 struct scsi_device *device = cmd->device;
116 struct scsi_target *starget = scsi_target(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 switch (reason) {
137 case SCSI_MLQUEUE_HOST_BUSY:
138 host->host_blocked = host->max_host_blocked;
139 break;
140 case SCSI_MLQUEUE_DEVICE_BUSY:
141 case SCSI_MLQUEUE_EH_RETRY:
142 device->device_blocked = device->max_device_blocked;
143 break;
144 case SCSI_MLQUEUE_TARGET_BUSY:
145 starget->target_blocked = starget->max_target_blocked;
146 break;
147 }
148
149 /*
150 * Decrement the counters, since these commands are no longer
151 * active on the host/device.
152 */
153 if (unbusy)
154 scsi_device_unbusy(device);
155
156 /*
157 * Requeue this command. It will go before all other commands
158 * that are already in the queue.
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 kblockd_schedule_work(q, &device->requeue_work);
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 if (!req)
219 return ret;
220
221 if (bufflen && blk_rq_map_kern(sdev->request_queue, req,
222 buffer, bufflen, __GFP_WAIT))
223 goto out;
224
225 req->cmd_len = COMMAND_SIZE(cmd[0]);
226 memcpy(req->cmd, cmd, req->cmd_len);
227 req->sense = sense;
228 req->sense_len = 0;
229 req->retries = retries;
230 req->timeout = timeout;
231 req->cmd_type = REQ_TYPE_BLOCK_PC;
232 req->cmd_flags |= flags | REQ_QUIET | REQ_PREEMPT;
233
234 /*
235 * head injection *required* here otherwise quiesce won't work
236 */
237 blk_execute_rq(req->q, NULL, req, 1);
238
239 /*
240 * Some devices (USB mass-storage in particular) may transfer
241 * garbage data together with a residue indicating that the data
242 * is invalid. Prevent the garbage from being misinterpreted
243 * and prevent security leaks by zeroing out the excess data.
244 */
245 if (unlikely(req->resid_len > 0 && req->resid_len <= bufflen))
246 memset(buffer + (bufflen - req->resid_len), 0, req->resid_len);
247
248 if (resid)
249 *resid = req->resid_len;
250 ret = req->errors;
251 out:
252 blk_put_request(req);
253
254 return ret;
255}
256EXPORT_SYMBOL(scsi_execute);
257
258
259int scsi_execute_req(struct scsi_device *sdev, const unsigned char *cmd,
260 int data_direction, void *buffer, unsigned bufflen,
261 struct scsi_sense_hdr *sshdr, int timeout, int retries,
262 int *resid)
263{
264 char *sense = NULL;
265 int result;
266
267 if (sshdr) {
268 sense = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_NOIO);
269 if (!sense)
270 return DRIVER_ERROR << 24;
271 }
272 result = scsi_execute(sdev, cmd, data_direction, buffer, bufflen,
273 sense, timeout, retries, 0, resid);
274 if (sshdr)
275 scsi_normalize_sense(sense, SCSI_SENSE_BUFFERSIZE, sshdr);
276
277 kfree(sense);
278 return result;
279}
280EXPORT_SYMBOL(scsi_execute_req);
281
282/*
283 * Function: scsi_init_cmd_errh()
284 *
285 * Purpose: Initialize cmd fields related to error handling.
286 *
287 * Arguments: cmd - command that is ready to be queued.
288 *
289 * Notes: This function has the job of initializing a number of
290 * fields related to error handling. Typically this will
291 * be called once for each command, as required.
292 */
293static void scsi_init_cmd_errh(struct scsi_cmnd *cmd)
294{
295 cmd->serial_number = 0;
296 scsi_set_resid(cmd, 0);
297 memset(cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);
298 if (cmd->cmd_len == 0)
299 cmd->cmd_len = scsi_command_size(cmd->cmnd);
300}
301
302void scsi_device_unbusy(struct scsi_device *sdev)
303{
304 struct Scsi_Host *shost = sdev->host;
305 struct scsi_target *starget = scsi_target(sdev);
306 unsigned long flags;
307
308 spin_lock_irqsave(shost->host_lock, flags);
309 shost->host_busy--;
310 starget->target_busy--;
311 if (unlikely(scsi_host_in_recovery(shost) &&
312 (shost->host_failed || shost->host_eh_scheduled)))
313 scsi_eh_wakeup(shost);
314 spin_unlock(shost->host_lock);
315 spin_lock(sdev->request_queue->queue_lock);
316 sdev->device_busy--;
317 spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
318}
319
320/*
321 * Called for single_lun devices on IO completion. Clear starget_sdev_user,
322 * and call blk_run_queue for all the scsi_devices on the target -
323 * including current_sdev first.
324 *
325 * Called with *no* scsi locks held.
326 */
327static void scsi_single_lun_run(struct scsi_device *current_sdev)
328{
329 struct Scsi_Host *shost = current_sdev->host;
330 struct scsi_device *sdev, *tmp;
331 struct scsi_target *starget = scsi_target(current_sdev);
332 unsigned long flags;
333
334 spin_lock_irqsave(shost->host_lock, flags);
335 starget->starget_sdev_user = NULL;
336 spin_unlock_irqrestore(shost->host_lock, flags);
337
338 /*
339 * Call blk_run_queue for all LUNs on the target, starting with
340 * current_sdev. We race with others (to set starget_sdev_user),
341 * but in most cases, we will be first. Ideally, each LU on the
342 * target would get some limited time or requests on the target.
343 */
344 blk_run_queue(current_sdev->request_queue);
345
346 spin_lock_irqsave(shost->host_lock, flags);
347 if (starget->starget_sdev_user)
348 goto out;
349 list_for_each_entry_safe(sdev, tmp, &starget->devices,
350 same_target_siblings) {
351 if (sdev == current_sdev)
352 continue;
353 if (scsi_device_get(sdev))
354 continue;
355
356 spin_unlock_irqrestore(shost->host_lock, flags);
357 blk_run_queue(sdev->request_queue);
358 spin_lock_irqsave(shost->host_lock, flags);
359
360 scsi_device_put(sdev);
361 }
362 out:
363 spin_unlock_irqrestore(shost->host_lock, flags);
364}
365
366static inline int scsi_device_is_busy(struct scsi_device *sdev)
367{
368 if (sdev->device_busy >= sdev->queue_depth || sdev->device_blocked)
369 return 1;
370
371 return 0;
372}
373
374static inline int scsi_target_is_busy(struct scsi_target *starget)
375{
376 return ((starget->can_queue > 0 &&
377 starget->target_busy >= starget->can_queue) ||
378 starget->target_blocked);
379}
380
381static inline int scsi_host_is_busy(struct Scsi_Host *shost)
382{
383 if ((shost->can_queue > 0 && shost->host_busy >= shost->can_queue) ||
384 shost->host_blocked || shost->host_self_blocked)
385 return 1;
386
387 return 0;
388}
389
390/*
391 * Function: scsi_run_queue()
392 *
393 * Purpose: Select a proper request queue to serve next
394 *
395 * Arguments: q - last request's queue
396 *
397 * Returns: Nothing
398 *
399 * Notes: The previous command was completely finished, start
400 * a new one if possible.
401 */
402static void scsi_run_queue(struct request_queue *q)
403{
404 struct scsi_device *sdev = q->queuedata;
405 struct Scsi_Host *shost;
406 LIST_HEAD(starved_list);
407 unsigned long flags;
408
409 shost = sdev->host;
410 if (scsi_target(sdev)->single_lun)
411 scsi_single_lun_run(sdev);
412
413 spin_lock_irqsave(shost->host_lock, flags);
414 list_splice_init(&shost->starved_list, &starved_list);
415
416 while (!list_empty(&starved_list)) {
417 /*
418 * As long as shost is accepting commands and we have
419 * starved queues, call blk_run_queue. scsi_request_fn
420 * drops the queue_lock and can add us back to the
421 * starved_list.
422 *
423 * host_lock protects the starved_list and starved_entry.
424 * scsi_request_fn must get the host_lock before checking
425 * or modifying starved_list or starved_entry.
426 */
427 if (scsi_host_is_busy(shost))
428 break;
429
430 sdev = list_entry(starved_list.next,
431 struct scsi_device, starved_entry);
432 list_del_init(&sdev->starved_entry);
433 if (scsi_target_is_busy(scsi_target(sdev))) {
434 list_move_tail(&sdev->starved_entry,
435 &shost->starved_list);
436 continue;
437 }
438
439 spin_unlock(shost->host_lock);
440 spin_lock(sdev->request_queue->queue_lock);
441 __blk_run_queue(sdev->request_queue);
442 spin_unlock(sdev->request_queue->queue_lock);
443 spin_lock(shost->host_lock);
444 }
445 /* put any unprocessed entries back */
446 list_splice(&starved_list, &shost->starved_list);
447 spin_unlock_irqrestore(shost->host_lock, flags);
448
449 blk_run_queue(q);
450}
451
452void scsi_requeue_run_queue(struct work_struct *work)
453{
454 struct scsi_device *sdev;
455 struct request_queue *q;
456
457 sdev = container_of(work, struct scsi_device, requeue_work);
458 q = sdev->request_queue;
459 scsi_run_queue(q);
460}
461
462/*
463 * Function: scsi_requeue_command()
464 *
465 * Purpose: Handle post-processing of completed commands.
466 *
467 * Arguments: q - queue to operate on
468 * cmd - command that may need to be requeued.
469 *
470 * Returns: Nothing
471 *
472 * Notes: After command completion, there may be blocks left
473 * over which weren't finished by the previous command
474 * this can be for a number of reasons - the main one is
475 * I/O errors in the middle of the request, in which case
476 * we need to request the blocks that come after the bad
477 * sector.
478 * Notes: Upon return, cmd is a stale pointer.
479 */
480static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd)
481{
482 struct scsi_device *sdev = cmd->device;
483 struct request *req = cmd->request;
484 unsigned long flags;
485
486 /*
487 * We need to hold a reference on the device to avoid the queue being
488 * killed after the unlock and before scsi_run_queue is invoked which
489 * may happen because scsi_unprep_request() puts the command which
490 * releases its reference on the device.
491 */
492 get_device(&sdev->sdev_gendev);
493
494 spin_lock_irqsave(q->queue_lock, flags);
495 scsi_unprep_request(req);
496 blk_requeue_request(q, req);
497 spin_unlock_irqrestore(q->queue_lock, flags);
498
499 scsi_run_queue(q);
500
501 put_device(&sdev->sdev_gendev);
502}
503
504void scsi_next_command(struct scsi_cmnd *cmd)
505{
506 struct scsi_device *sdev = cmd->device;
507 struct request_queue *q = sdev->request_queue;
508
509 /* need to hold a reference on the device before we let go of the cmd */
510 get_device(&sdev->sdev_gendev);
511
512 scsi_put_command(cmd);
513 scsi_run_queue(q);
514
515 /* ok to remove device now */
516 put_device(&sdev->sdev_gendev);
517}
518
519void scsi_run_host_queues(struct Scsi_Host *shost)
520{
521 struct scsi_device *sdev;
522
523 shost_for_each_device(sdev, shost)
524 scsi_run_queue(sdev->request_queue);
525}
526
527static void __scsi_release_buffers(struct scsi_cmnd *, int);
528
529/*
530 * Function: scsi_end_request()
531 *
532 * Purpose: Post-processing of completed commands (usually invoked at end
533 * of upper level post-processing and scsi_io_completion).
534 *
535 * Arguments: cmd - command that is complete.
536 * error - 0 if I/O indicates success, < 0 for I/O error.
537 * bytes - number of bytes of completed I/O
538 * requeue - indicates whether we should requeue leftovers.
539 *
540 * Lock status: Assumed that lock is not held upon entry.
541 *
542 * Returns: cmd if requeue required, NULL otherwise.
543 *
544 * Notes: This is called for block device requests in order to
545 * mark some number of sectors as complete.
546 *
547 * We are guaranteeing that the request queue will be goosed
548 * at some point during this call.
549 * Notes: If cmd was requeued, upon return it will be a stale pointer.
550 */
551static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int error,
552 int bytes, int requeue)
553{
554 struct request_queue *q = cmd->device->request_queue;
555 struct request *req = cmd->request;
556
557 /*
558 * If there are blocks left over at the end, set up the command
559 * to queue the remainder of them.
560 */
561 if (blk_end_request(req, error, bytes)) {
562 /* kill remainder if no retrys */
563 if (error && scsi_noretry_cmd(cmd))
564 blk_end_request_all(req, error);
565 else {
566 if (requeue) {
567 /*
568 * Bleah. Leftovers again. Stick the
569 * leftovers in the front of the
570 * queue, and goose the queue again.
571 */
572 scsi_release_buffers(cmd);
573 scsi_requeue_command(q, cmd);
574 cmd = NULL;
575 }
576 return cmd;
577 }
578 }
579
580 /*
581 * This will goose the queue request function at the end, so we don't
582 * need to worry about launching another command.
583 */
584 __scsi_release_buffers(cmd, 0);
585 scsi_next_command(cmd);
586 return NULL;
587}
588
589static inline unsigned int scsi_sgtable_index(unsigned short nents)
590{
591 unsigned int index;
592
593 BUG_ON(nents > SCSI_MAX_SG_SEGMENTS);
594
595 if (nents <= 8)
596 index = 0;
597 else
598 index = get_count_order(nents) - 3;
599
600 return index;
601}
602
603static void scsi_sg_free(struct scatterlist *sgl, unsigned int nents)
604{
605 struct scsi_host_sg_pool *sgp;
606
607 sgp = scsi_sg_pools + scsi_sgtable_index(nents);
608 mempool_free(sgl, sgp->pool);
609}
610
611static struct scatterlist *scsi_sg_alloc(unsigned int nents, gfp_t gfp_mask)
612{
613 struct scsi_host_sg_pool *sgp;
614
615 sgp = scsi_sg_pools + scsi_sgtable_index(nents);
616 return mempool_alloc(sgp->pool, gfp_mask);
617}
618
619static int scsi_alloc_sgtable(struct scsi_data_buffer *sdb, int nents,
620 gfp_t gfp_mask)
621{
622 int ret;
623
624 BUG_ON(!nents);
625
626 ret = __sg_alloc_table(&sdb->table, nents, SCSI_MAX_SG_SEGMENTS,
627 gfp_mask, scsi_sg_alloc);
628 if (unlikely(ret))
629 __sg_free_table(&sdb->table, SCSI_MAX_SG_SEGMENTS,
630 scsi_sg_free);
631
632 return ret;
633}
634
635static void scsi_free_sgtable(struct scsi_data_buffer *sdb)
636{
637 __sg_free_table(&sdb->table, SCSI_MAX_SG_SEGMENTS, scsi_sg_free);
638}
639
640static void __scsi_release_buffers(struct scsi_cmnd *cmd, int do_bidi_check)
641{
642
643 if (cmd->sdb.table.nents)
644 scsi_free_sgtable(&cmd->sdb);
645
646 memset(&cmd->sdb, 0, sizeof(cmd->sdb));
647
648 if (do_bidi_check && scsi_bidi_cmnd(cmd)) {
649 struct scsi_data_buffer *bidi_sdb =
650 cmd->request->next_rq->special;
651 scsi_free_sgtable(bidi_sdb);
652 kmem_cache_free(scsi_sdb_cache, bidi_sdb);
653 cmd->request->next_rq->special = NULL;
654 }
655
656 if (scsi_prot_sg_count(cmd))
657 scsi_free_sgtable(cmd->prot_sdb);
658}
659
660/*
661 * Function: scsi_release_buffers()
662 *
663 * Purpose: Completion processing for block device I/O requests.
664 *
665 * Arguments: cmd - command that we are bailing.
666 *
667 * Lock status: Assumed that no lock is held upon entry.
668 *
669 * Returns: Nothing
670 *
671 * Notes: In the event that an upper level driver rejects a
672 * command, we must release resources allocated during
673 * the __init_io() function. Primarily this would involve
674 * the scatter-gather table, and potentially any bounce
675 * buffers.
676 */
677void scsi_release_buffers(struct scsi_cmnd *cmd)
678{
679 __scsi_release_buffers(cmd, 1);
680}
681EXPORT_SYMBOL(scsi_release_buffers);
682
683static int __scsi_error_from_host_byte(struct scsi_cmnd *cmd, int result)
684{
685 int error = 0;
686
687 switch(host_byte(result)) {
688 case DID_TRANSPORT_FAILFAST:
689 error = -ENOLINK;
690 break;
691 case DID_TARGET_FAILURE:
692 set_host_byte(cmd, DID_OK);
693 error = -EREMOTEIO;
694 break;
695 case DID_NEXUS_FAILURE:
696 set_host_byte(cmd, DID_OK);
697 error = -EBADE;
698 break;
699 default:
700 error = -EIO;
701 break;
702 }
703
704 return error;
705}
706
707/*
708 * Function: scsi_io_completion()
709 *
710 * Purpose: Completion processing for block device I/O requests.
711 *
712 * Arguments: cmd - command that is finished.
713 *
714 * Lock status: Assumed that no lock is held upon entry.
715 *
716 * Returns: Nothing
717 *
718 * Notes: This function is matched in terms of capabilities to
719 * the function that created the scatter-gather list.
720 * In other words, if there are no bounce buffers
721 * (the normal case for most drivers), we don't need
722 * the logic to deal with cleaning up afterwards.
723 *
724 * We must call scsi_end_request(). This will finish off
725 * the specified number of sectors. If we are done, the
726 * command block will be released and the queue function
727 * will be goosed. If we are not done then we have to
728 * figure out what to do next:
729 *
730 * a) We can call scsi_requeue_command(). The request
731 * will be unprepared and put back on the queue. Then
732 * a new command will be created for it. This should
733 * be used if we made forward progress, or if we want
734 * to switch from READ(10) to READ(6) for example.
735 *
736 * b) We can call scsi_queue_insert(). The request will
737 * be put back on the queue and retried using the same
738 * command as before, possibly after a delay.
739 *
740 * c) We can call blk_end_request() with -EIO to fail
741 * the remainder of the request.
742 */
743void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
744{
745 int result = cmd->result;
746 struct request_queue *q = cmd->device->request_queue;
747 struct request *req = cmd->request;
748 int error = 0;
749 struct scsi_sense_hdr sshdr;
750 int sense_valid = 0;
751 int sense_deferred = 0;
752 enum {ACTION_FAIL, ACTION_REPREP, ACTION_RETRY,
753 ACTION_DELAYED_RETRY} action;
754 char *description = NULL;
755
756 if (result) {
757 sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
758 if (sense_valid)
759 sense_deferred = scsi_sense_is_deferred(&sshdr);
760 }
761
762 if (req->cmd_type == REQ_TYPE_BLOCK_PC) { /* SG_IO ioctl from block level */
763 if (result) {
764 if (sense_valid && req->sense) {
765 /*
766 * SG_IO wants current and deferred errors
767 */
768 int len = 8 + cmd->sense_buffer[7];
769
770 if (len > SCSI_SENSE_BUFFERSIZE)
771 len = SCSI_SENSE_BUFFERSIZE;
772 memcpy(req->sense, cmd->sense_buffer, len);
773 req->sense_len = len;
774 }
775 if (!sense_deferred)
776 error = __scsi_error_from_host_byte(cmd, result);
777 }
778 /*
779 * __scsi_error_from_host_byte may have reset the host_byte
780 */
781 req->errors = cmd->result;
782
783 req->resid_len = scsi_get_resid(cmd);
784
785 if (scsi_bidi_cmnd(cmd)) {
786 /*
787 * Bidi commands Must be complete as a whole,
788 * both sides at once.
789 */
790 req->next_rq->resid_len = scsi_in(cmd)->resid;
791
792 scsi_release_buffers(cmd);
793 blk_end_request_all(req, 0);
794
795 scsi_next_command(cmd);
796 return;
797 }
798 }
799
800 /* no bidi support for !REQ_TYPE_BLOCK_PC yet */
801 BUG_ON(blk_bidi_rq(req));
802
803 /*
804 * Next deal with any sectors which we were able to correctly
805 * handle.
806 */
807 SCSI_LOG_HLCOMPLETE(1, printk("%u sectors total, "
808 "%d bytes done.\n",
809 blk_rq_sectors(req), good_bytes));
810
811 /*
812 * Recovered errors need reporting, but they're always treated
813 * as success, so fiddle the result code here. For BLOCK_PC
814 * we already took a copy of the original into rq->errors which
815 * is what gets returned to the user
816 */
817 if (sense_valid && (sshdr.sense_key == RECOVERED_ERROR)) {
818 /* if ATA PASS-THROUGH INFORMATION AVAILABLE skip
819 * print since caller wants ATA registers. Only occurs on
820 * SCSI ATA PASS_THROUGH commands when CK_COND=1
821 */
822 if ((sshdr.asc == 0x0) && (sshdr.ascq == 0x1d))
823 ;
824 else if (!(req->cmd_flags & REQ_QUIET))
825 scsi_print_sense("", cmd);
826 result = 0;
827 /* BLOCK_PC may have set error */
828 error = 0;
829 }
830
831 /*
832 * A number of bytes were successfully read. If there
833 * are leftovers and there is some kind of error
834 * (result != 0), retry the rest.
835 */
836 if (scsi_end_request(cmd, error, good_bytes, result == 0) == NULL)
837 return;
838
839 error = __scsi_error_from_host_byte(cmd, result);
840
841 if (host_byte(result) == DID_RESET) {
842 /* Third party bus reset or reset for error recovery
843 * reasons. Just retry the command and see what
844 * happens.
845 */
846 action = ACTION_RETRY;
847 } else if (sense_valid && !sense_deferred) {
848 switch (sshdr.sense_key) {
849 case UNIT_ATTENTION:
850 if (cmd->device->removable) {
851 /* Detected disc change. Set a bit
852 * and quietly refuse further access.
853 */
854 cmd->device->changed = 1;
855 description = "Media Changed";
856 action = ACTION_FAIL;
857 } else {
858 /* Must have been a power glitch, or a
859 * bus reset. Could not have been a
860 * media change, so we just retry the
861 * command and see what happens.
862 */
863 action = ACTION_RETRY;
864 }
865 break;
866 case ILLEGAL_REQUEST:
867 /* If we had an ILLEGAL REQUEST returned, then
868 * we may have performed an unsupported
869 * command. The only thing this should be
870 * would be a ten byte read where only a six
871 * byte read was supported. Also, on a system
872 * where READ CAPACITY failed, we may have
873 * read past the end of the disk.
874 */
875 if ((cmd->device->use_10_for_rw &&
876 sshdr.asc == 0x20 && sshdr.ascq == 0x00) &&
877 (cmd->cmnd[0] == READ_10 ||
878 cmd->cmnd[0] == WRITE_10)) {
879 /* This will issue a new 6-byte command. */
880 cmd->device->use_10_for_rw = 0;
881 action = ACTION_REPREP;
882 } else if (sshdr.asc == 0x10) /* DIX */ {
883 description = "Host Data Integrity Failure";
884 action = ACTION_FAIL;
885 error = -EILSEQ;
886 /* INVALID COMMAND OPCODE or INVALID FIELD IN CDB */
887 } else if ((sshdr.asc == 0x20 || sshdr.asc == 0x24) &&
888 (cmd->cmnd[0] == UNMAP ||
889 cmd->cmnd[0] == WRITE_SAME_16 ||
890 cmd->cmnd[0] == WRITE_SAME)) {
891 description = "Discard failure";
892 action = ACTION_FAIL;
893 error = -EREMOTEIO;
894 } else
895 action = ACTION_FAIL;
896 break;
897 case ABORTED_COMMAND:
898 action = ACTION_FAIL;
899 if (sshdr.asc == 0x10) { /* DIF */
900 description = "Target Data Integrity Failure";
901 error = -EILSEQ;
902 }
903 break;
904 case NOT_READY:
905 /* If the device is in the process of becoming
906 * ready, or has a temporary blockage, retry.
907 */
908 if (sshdr.asc == 0x04) {
909 switch (sshdr.ascq) {
910 case 0x01: /* becoming ready */
911 case 0x04: /* format in progress */
912 case 0x05: /* rebuild in progress */
913 case 0x06: /* recalculation in progress */
914 case 0x07: /* operation in progress */
915 case 0x08: /* Long write in progress */
916 case 0x09: /* self test in progress */
917 case 0x14: /* space allocation in progress */
918 action = ACTION_DELAYED_RETRY;
919 break;
920 default:
921 description = "Device not ready";
922 action = ACTION_FAIL;
923 break;
924 }
925 } else {
926 description = "Device not ready";
927 action = ACTION_FAIL;
928 }
929 break;
930 case VOLUME_OVERFLOW:
931 /* See SSC3rXX or current. */
932 action = ACTION_FAIL;
933 break;
934 default:
935 description = "Unhandled sense code";
936 action = ACTION_FAIL;
937 break;
938 }
939 } else {
940 description = "Unhandled error code";
941 action = ACTION_FAIL;
942 }
943
944 switch (action) {
945 case ACTION_FAIL:
946 /* Give up and fail the remainder of the request */
947 scsi_release_buffers(cmd);
948 if (!(req->cmd_flags & REQ_QUIET)) {
949 if (description)
950 scmd_printk(KERN_INFO, cmd, "%s\n",
951 description);
952 scsi_print_result(cmd);
953 if (driver_byte(result) & DRIVER_SENSE)
954 scsi_print_sense("", cmd);
955 scsi_print_command(cmd);
956 }
957 if (blk_end_request_err(req, error))
958 scsi_requeue_command(q, cmd);
959 else
960 scsi_next_command(cmd);
961 break;
962 case ACTION_REPREP:
963 /* Unprep the request and put it back at the head of the queue.
964 * A new command will be prepared and issued.
965 */
966 scsi_release_buffers(cmd);
967 scsi_requeue_command(q, cmd);
968 break;
969 case ACTION_RETRY:
970 /* Retry the same command immediately */
971 __scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY, 0);
972 break;
973 case ACTION_DELAYED_RETRY:
974 /* Retry the same command after a delay */
975 __scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY, 0);
976 break;
977 }
978}
979
980static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb,
981 gfp_t gfp_mask)
982{
983 int count;
984
985 /*
986 * If sg table allocation fails, requeue request later.
987 */
988 if (unlikely(scsi_alloc_sgtable(sdb, req->nr_phys_segments,
989 gfp_mask))) {
990 return BLKPREP_DEFER;
991 }
992
993 req->buffer = NULL;
994
995 /*
996 * Next, walk the list, and fill in the addresses and sizes of
997 * each segment.
998 */
999 count = blk_rq_map_sg(req->q, req, sdb->table.sgl);
1000 BUG_ON(count > sdb->table.nents);
1001 sdb->table.nents = count;
1002 sdb->length = blk_rq_bytes(req);
1003 return BLKPREP_OK;
1004}
1005
1006/*
1007 * Function: scsi_init_io()
1008 *
1009 * Purpose: SCSI I/O initialize function.
1010 *
1011 * Arguments: cmd - Command descriptor we wish to initialize
1012 *
1013 * Returns: 0 on success
1014 * BLKPREP_DEFER if the failure is retryable
1015 * BLKPREP_KILL if the failure is fatal
1016 */
1017int scsi_init_io(struct scsi_cmnd *cmd, gfp_t gfp_mask)
1018{
1019 struct request *rq = cmd->request;
1020
1021 int error = scsi_init_sgtable(rq, &cmd->sdb, gfp_mask);
1022 if (error)
1023 goto err_exit;
1024
1025 if (blk_bidi_rq(rq)) {
1026 struct scsi_data_buffer *bidi_sdb = kmem_cache_zalloc(
1027 scsi_sdb_cache, GFP_ATOMIC);
1028 if (!bidi_sdb) {
1029 error = BLKPREP_DEFER;
1030 goto err_exit;
1031 }
1032
1033 rq->next_rq->special = bidi_sdb;
1034 error = scsi_init_sgtable(rq->next_rq, bidi_sdb, GFP_ATOMIC);
1035 if (error)
1036 goto err_exit;
1037 }
1038
1039 if (blk_integrity_rq(rq)) {
1040 struct scsi_data_buffer *prot_sdb = cmd->prot_sdb;
1041 int ivecs, count;
1042
1043 BUG_ON(prot_sdb == NULL);
1044 ivecs = blk_rq_count_integrity_sg(rq->q, rq->bio);
1045
1046 if (scsi_alloc_sgtable(prot_sdb, ivecs, gfp_mask)) {
1047 error = BLKPREP_DEFER;
1048 goto err_exit;
1049 }
1050
1051 count = blk_rq_map_integrity_sg(rq->q, rq->bio,
1052 prot_sdb->table.sgl);
1053 BUG_ON(unlikely(count > ivecs));
1054 BUG_ON(unlikely(count > queue_max_integrity_segments(rq->q)));
1055
1056 cmd->prot_sdb = prot_sdb;
1057 cmd->prot_sdb->table.nents = count;
1058 }
1059
1060 return BLKPREP_OK ;
1061
1062err_exit:
1063 scsi_release_buffers(cmd);
1064 cmd->request->special = NULL;
1065 scsi_put_command(cmd);
1066 return error;
1067}
1068EXPORT_SYMBOL(scsi_init_io);
1069
1070static struct scsi_cmnd *scsi_get_cmd_from_req(struct scsi_device *sdev,
1071 struct request *req)
1072{
1073 struct scsi_cmnd *cmd;
1074
1075 if (!req->special) {
1076 cmd = scsi_get_command(sdev, GFP_ATOMIC);
1077 if (unlikely(!cmd))
1078 return NULL;
1079 req->special = cmd;
1080 } else {
1081 cmd = req->special;
1082 }
1083
1084 /* pull a tag out of the request if we have one */
1085 cmd->tag = req->tag;
1086 cmd->request = req;
1087
1088 cmd->cmnd = req->cmd;
1089 cmd->prot_op = SCSI_PROT_NORMAL;
1090
1091 return cmd;
1092}
1093
1094int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req)
1095{
1096 struct scsi_cmnd *cmd;
1097 int ret = scsi_prep_state_check(sdev, req);
1098
1099 if (ret != BLKPREP_OK)
1100 return ret;
1101
1102 cmd = scsi_get_cmd_from_req(sdev, req);
1103 if (unlikely(!cmd))
1104 return BLKPREP_DEFER;
1105
1106 /*
1107 * BLOCK_PC requests may transfer data, in which case they must
1108 * a bio attached to them. Or they might contain a SCSI command
1109 * that does not transfer data, in which case they may optionally
1110 * submit a request without an attached bio.
1111 */
1112 if (req->bio) {
1113 int ret;
1114
1115 BUG_ON(!req->nr_phys_segments);
1116
1117 ret = scsi_init_io(cmd, GFP_ATOMIC);
1118 if (unlikely(ret))
1119 return ret;
1120 } else {
1121 BUG_ON(blk_rq_bytes(req));
1122
1123 memset(&cmd->sdb, 0, sizeof(cmd->sdb));
1124 req->buffer = NULL;
1125 }
1126
1127 cmd->cmd_len = req->cmd_len;
1128 if (!blk_rq_bytes(req))
1129 cmd->sc_data_direction = DMA_NONE;
1130 else if (rq_data_dir(req) == WRITE)
1131 cmd->sc_data_direction = DMA_TO_DEVICE;
1132 else
1133 cmd->sc_data_direction = DMA_FROM_DEVICE;
1134
1135 cmd->transfersize = blk_rq_bytes(req);
1136 cmd->allowed = req->retries;
1137 return BLKPREP_OK;
1138}
1139EXPORT_SYMBOL(scsi_setup_blk_pc_cmnd);
1140
1141/*
1142 * Setup a REQ_TYPE_FS command. These are simple read/write request
1143 * from filesystems that still need to be translated to SCSI CDBs from
1144 * the ULD.
1145 */
1146int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct request *req)
1147{
1148 struct scsi_cmnd *cmd;
1149 int ret = scsi_prep_state_check(sdev, req);
1150
1151 if (ret != BLKPREP_OK)
1152 return ret;
1153
1154 if (unlikely(sdev->scsi_dh_data && sdev->scsi_dh_data->scsi_dh
1155 && sdev->scsi_dh_data->scsi_dh->prep_fn)) {
1156 ret = sdev->scsi_dh_data->scsi_dh->prep_fn(sdev, req);
1157 if (ret != BLKPREP_OK)
1158 return ret;
1159 }
1160
1161 /*
1162 * Filesystem requests must transfer data.
1163 */
1164 BUG_ON(!req->nr_phys_segments);
1165
1166 cmd = scsi_get_cmd_from_req(sdev, req);
1167 if (unlikely(!cmd))
1168 return BLKPREP_DEFER;
1169
1170 memset(cmd->cmnd, 0, BLK_MAX_CDB);
1171 return scsi_init_io(cmd, GFP_ATOMIC);
1172}
1173EXPORT_SYMBOL(scsi_setup_fs_cmnd);
1174
1175int scsi_prep_state_check(struct scsi_device *sdev, struct request *req)
1176{
1177 int ret = BLKPREP_OK;
1178
1179 /*
1180 * If the device is not in running state we will reject some
1181 * or all commands.
1182 */
1183 if (unlikely(sdev->sdev_state != SDEV_RUNNING)) {
1184 switch (sdev->sdev_state) {
1185 case SDEV_OFFLINE:
1186 /*
1187 * If the device is offline we refuse to process any
1188 * commands. The device must be brought online
1189 * before trying any recovery commands.
1190 */
1191 sdev_printk(KERN_ERR, sdev,
1192 "rejecting I/O to offline device\n");
1193 ret = BLKPREP_KILL;
1194 break;
1195 case SDEV_DEL:
1196 /*
1197 * If the device is fully deleted, we refuse to
1198 * process any commands as well.
1199 */
1200 sdev_printk(KERN_ERR, sdev,
1201 "rejecting I/O to dead device\n");
1202 ret = BLKPREP_KILL;
1203 break;
1204 case SDEV_QUIESCE:
1205 case SDEV_BLOCK:
1206 case SDEV_CREATED_BLOCK:
1207 /*
1208 * If the devices is blocked we defer normal commands.
1209 */
1210 if (!(req->cmd_flags & REQ_PREEMPT))
1211 ret = BLKPREP_DEFER;
1212 break;
1213 default:
1214 /*
1215 * For any other not fully online state we only allow
1216 * special commands. In particular any user initiated
1217 * command is not allowed.
1218 */
1219 if (!(req->cmd_flags & REQ_PREEMPT))
1220 ret = BLKPREP_KILL;
1221 break;
1222 }
1223 }
1224 return ret;
1225}
1226EXPORT_SYMBOL(scsi_prep_state_check);
1227
1228int scsi_prep_return(struct request_queue *q, struct request *req, int ret)
1229{
1230 struct scsi_device *sdev = q->queuedata;
1231
1232 switch (ret) {
1233 case BLKPREP_KILL:
1234 req->errors = DID_NO_CONNECT << 16;
1235 /* release the command and kill it */
1236 if (req->special) {
1237 struct scsi_cmnd *cmd = req->special;
1238 scsi_release_buffers(cmd);
1239 scsi_put_command(cmd);
1240 req->special = NULL;
1241 }
1242 break;
1243 case BLKPREP_DEFER:
1244 /*
1245 * If we defer, the blk_peek_request() returns NULL, but the
1246 * queue must be restarted, so we schedule a callback to happen
1247 * shortly.
1248 */
1249 if (sdev->device_busy == 0)
1250 blk_delay_queue(q, SCSI_QUEUE_DELAY);
1251 break;
1252 default:
1253 req->cmd_flags |= REQ_DONTPREP;
1254 }
1255
1256 return ret;
1257}
1258EXPORT_SYMBOL(scsi_prep_return);
1259
1260int scsi_prep_fn(struct request_queue *q, struct request *req)
1261{
1262 struct scsi_device *sdev = q->queuedata;
1263 int ret = BLKPREP_KILL;
1264
1265 if (req->cmd_type == REQ_TYPE_BLOCK_PC)
1266 ret = scsi_setup_blk_pc_cmnd(sdev, req);
1267 return scsi_prep_return(q, req, ret);
1268}
1269EXPORT_SYMBOL(scsi_prep_fn);
1270
1271/*
1272 * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
1273 * return 0.
1274 *
1275 * Called with the queue_lock held.
1276 */
1277static inline int scsi_dev_queue_ready(struct request_queue *q,
1278 struct scsi_device *sdev)
1279{
1280 if (sdev->device_busy == 0 && sdev->device_blocked) {
1281 /*
1282 * unblock after device_blocked iterates to zero
1283 */
1284 if (--sdev->device_blocked == 0) {
1285 SCSI_LOG_MLQUEUE(3,
1286 sdev_printk(KERN_INFO, sdev,
1287 "unblocking device at zero depth\n"));
1288 } else {
1289 blk_delay_queue(q, SCSI_QUEUE_DELAY);
1290 return 0;
1291 }
1292 }
1293 if (scsi_device_is_busy(sdev))
1294 return 0;
1295
1296 return 1;
1297}
1298
1299
1300/*
1301 * scsi_target_queue_ready: checks if there we can send commands to target
1302 * @sdev: scsi device on starget to check.
1303 *
1304 * Called with the host lock held.
1305 */
1306static inline int scsi_target_queue_ready(struct Scsi_Host *shost,
1307 struct scsi_device *sdev)
1308{
1309 struct scsi_target *starget = scsi_target(sdev);
1310
1311 if (starget->single_lun) {
1312 if (starget->starget_sdev_user &&
1313 starget->starget_sdev_user != sdev)
1314 return 0;
1315 starget->starget_sdev_user = sdev;
1316 }
1317
1318 if (starget->target_busy == 0 && starget->target_blocked) {
1319 /*
1320 * unblock after target_blocked iterates to zero
1321 */
1322 if (--starget->target_blocked == 0) {
1323 SCSI_LOG_MLQUEUE(3, starget_printk(KERN_INFO, starget,
1324 "unblocking target at zero depth\n"));
1325 } else
1326 return 0;
1327 }
1328
1329 if (scsi_target_is_busy(starget)) {
1330 list_move_tail(&sdev->starved_entry, &shost->starved_list);
1331 return 0;
1332 }
1333
1334 return 1;
1335}
1336
1337/*
1338 * scsi_host_queue_ready: if we can send requests to shost, return 1 else
1339 * return 0. We must end up running the queue again whenever 0 is
1340 * returned, else IO can hang.
1341 *
1342 * Called with host_lock held.
1343 */
1344static inline int scsi_host_queue_ready(struct request_queue *q,
1345 struct Scsi_Host *shost,
1346 struct scsi_device *sdev)
1347{
1348 if (scsi_host_in_recovery(shost))
1349 return 0;
1350 if (shost->host_busy == 0 && shost->host_blocked) {
1351 /*
1352 * unblock after host_blocked iterates to zero
1353 */
1354 if (--shost->host_blocked == 0) {
1355 SCSI_LOG_MLQUEUE(3,
1356 printk("scsi%d unblocking host at zero depth\n",
1357 shost->host_no));
1358 } else {
1359 return 0;
1360 }
1361 }
1362 if (scsi_host_is_busy(shost)) {
1363 if (list_empty(&sdev->starved_entry))
1364 list_add_tail(&sdev->starved_entry, &shost->starved_list);
1365 return 0;
1366 }
1367
1368 /* We're OK to process the command, so we can't be starved */
1369 if (!list_empty(&sdev->starved_entry))
1370 list_del_init(&sdev->starved_entry);
1371
1372 return 1;
1373}
1374
1375/*
1376 * Busy state exporting function for request stacking drivers.
1377 *
1378 * For efficiency, no lock is taken to check the busy state of
1379 * shost/starget/sdev, since the returned value is not guaranteed and
1380 * may be changed after request stacking drivers call the function,
1381 * regardless of taking lock or not.
1382 *
1383 * When scsi can't dispatch I/Os anymore and needs to kill I/Os scsi
1384 * needs to return 'not busy'. Otherwise, request stacking drivers
1385 * may hold requests forever.
1386 */
1387static int scsi_lld_busy(struct request_queue *q)
1388{
1389 struct scsi_device *sdev = q->queuedata;
1390 struct Scsi_Host *shost;
1391
1392 if (blk_queue_dead(q))
1393 return 0;
1394
1395 shost = sdev->host;
1396
1397 /*
1398 * Ignore host/starget busy state.
1399 * Since block layer does not have a concept of fairness across
1400 * multiple queues, congestion of host/starget needs to be handled
1401 * in SCSI layer.
1402 */
1403 if (scsi_host_in_recovery(shost) || scsi_device_is_busy(sdev))
1404 return 1;
1405
1406 return 0;
1407}
1408
1409/*
1410 * Kill a request for a dead device
1411 */
1412static void scsi_kill_request(struct request *req, struct request_queue *q)
1413{
1414 struct scsi_cmnd *cmd = req->special;
1415 struct scsi_device *sdev;
1416 struct scsi_target *starget;
1417 struct Scsi_Host *shost;
1418
1419 blk_start_request(req);
1420
1421 scmd_printk(KERN_INFO, cmd, "killing request\n");
1422
1423 sdev = cmd->device;
1424 starget = scsi_target(sdev);
1425 shost = sdev->host;
1426 scsi_init_cmd_errh(cmd);
1427 cmd->result = DID_NO_CONNECT << 16;
1428 atomic_inc(&cmd->device->iorequest_cnt);
1429
1430 /*
1431 * SCSI request completion path will do scsi_device_unbusy(),
1432 * bump busy counts. To bump the counters, we need to dance
1433 * with the locks as normal issue path does.
1434 */
1435 sdev->device_busy++;
1436 spin_unlock(sdev->request_queue->queue_lock);
1437 spin_lock(shost->host_lock);
1438 shost->host_busy++;
1439 starget->target_busy++;
1440 spin_unlock(shost->host_lock);
1441 spin_lock(sdev->request_queue->queue_lock);
1442
1443 blk_complete_request(req);
1444}
1445
1446static void scsi_softirq_done(struct request *rq)
1447{
1448 struct scsi_cmnd *cmd = rq->special;
1449 unsigned long wait_for = (cmd->allowed + 1) * rq->timeout;
1450 int disposition;
1451
1452 INIT_LIST_HEAD(&cmd->eh_entry);
1453
1454 atomic_inc(&cmd->device->iodone_cnt);
1455 if (cmd->result)
1456 atomic_inc(&cmd->device->ioerr_cnt);
1457
1458 disposition = scsi_decide_disposition(cmd);
1459 if (disposition != SUCCESS &&
1460 time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) {
1461 sdev_printk(KERN_ERR, cmd->device,
1462 "timing out command, waited %lus\n",
1463 wait_for/HZ);
1464 disposition = SUCCESS;
1465 }
1466
1467 scsi_log_completion(cmd, disposition);
1468
1469 switch (disposition) {
1470 case SUCCESS:
1471 scsi_finish_command(cmd);
1472 break;
1473 case NEEDS_RETRY:
1474 scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY);
1475 break;
1476 case ADD_TO_MLQUEUE:
1477 scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
1478 break;
1479 default:
1480 if (!scsi_eh_scmd_add(cmd, 0))
1481 scsi_finish_command(cmd);
1482 }
1483}
1484
1485/*
1486 * Function: scsi_request_fn()
1487 *
1488 * Purpose: Main strategy routine for SCSI.
1489 *
1490 * Arguments: q - Pointer to actual queue.
1491 *
1492 * Returns: Nothing
1493 *
1494 * Lock status: IO request lock assumed to be held when called.
1495 */
1496static void scsi_request_fn(struct request_queue *q)
1497{
1498 struct scsi_device *sdev = q->queuedata;
1499 struct Scsi_Host *shost;
1500 struct scsi_cmnd *cmd;
1501 struct request *req;
1502
1503 if(!get_device(&sdev->sdev_gendev))
1504 /* We must be tearing the block queue down already */
1505 return;
1506
1507 /*
1508 * To start with, we keep looping until the queue is empty, or until
1509 * the host is no longer able to accept any more requests.
1510 */
1511 shost = sdev->host;
1512 for (;;) {
1513 int rtn;
1514 /*
1515 * get next queueable request. We do this early to make sure
1516 * that the request is fully prepared even if we cannot
1517 * accept it.
1518 */
1519 req = blk_peek_request(q);
1520 if (!req || !scsi_dev_queue_ready(q, sdev))
1521 break;
1522
1523 if (unlikely(!scsi_device_online(sdev))) {
1524 sdev_printk(KERN_ERR, sdev,
1525 "rejecting I/O to offline device\n");
1526 scsi_kill_request(req, q);
1527 continue;
1528 }
1529
1530
1531 /*
1532 * Remove the request from the request list.
1533 */
1534 if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req)))
1535 blk_start_request(req);
1536 sdev->device_busy++;
1537
1538 spin_unlock(q->queue_lock);
1539 cmd = req->special;
1540 if (unlikely(cmd == NULL)) {
1541 printk(KERN_CRIT "impossible request in %s.\n"
1542 "please mail a stack trace to "
1543 "linux-scsi@vger.kernel.org\n",
1544 __func__);
1545 blk_dump_rq_flags(req, "foo");
1546 BUG();
1547 }
1548 spin_lock(shost->host_lock);
1549
1550 /*
1551 * We hit this when the driver is using a host wide
1552 * tag map. For device level tag maps the queue_depth check
1553 * in the device ready fn would prevent us from trying
1554 * to allocate a tag. Since the map is a shared host resource
1555 * we add the dev to the starved list so it eventually gets
1556 * a run when a tag is freed.
1557 */
1558 if (blk_queue_tagged(q) && !blk_rq_tagged(req)) {
1559 if (list_empty(&sdev->starved_entry))
1560 list_add_tail(&sdev->starved_entry,
1561 &shost->starved_list);
1562 goto not_ready;
1563 }
1564
1565 if (!scsi_target_queue_ready(shost, sdev))
1566 goto not_ready;
1567
1568 if (!scsi_host_queue_ready(q, shost, sdev))
1569 goto not_ready;
1570
1571 scsi_target(sdev)->target_busy++;
1572 shost->host_busy++;
1573
1574 /*
1575 * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will
1576 * take the lock again.
1577 */
1578 spin_unlock_irq(shost->host_lock);
1579
1580 /*
1581 * Finally, initialize any error handling parameters, and set up
1582 * the timers for timeouts.
1583 */
1584 scsi_init_cmd_errh(cmd);
1585
1586 /*
1587 * Dispatch the command to the low-level driver.
1588 */
1589 rtn = scsi_dispatch_cmd(cmd);
1590 spin_lock_irq(q->queue_lock);
1591 if (rtn)
1592 goto out_delay;
1593 }
1594
1595 goto out;
1596
1597 not_ready:
1598 spin_unlock_irq(shost->host_lock);
1599
1600 /*
1601 * lock q, handle tag, requeue req, and decrement device_busy. We
1602 * must return with queue_lock held.
1603 *
1604 * Decrementing device_busy without checking it is OK, as all such
1605 * cases (host limits or settings) should run the queue at some
1606 * later time.
1607 */
1608 spin_lock_irq(q->queue_lock);
1609 blk_requeue_request(q, req);
1610 sdev->device_busy--;
1611out_delay:
1612 if (sdev->device_busy == 0)
1613 blk_delay_queue(q, SCSI_QUEUE_DELAY);
1614out:
1615 /* must be careful here...if we trigger the ->remove() function
1616 * we cannot be holding the q lock */
1617 spin_unlock_irq(q->queue_lock);
1618 put_device(&sdev->sdev_gendev);
1619 spin_lock_irq(q->queue_lock);
1620}
1621
1622u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost)
1623{
1624 struct device *host_dev;
1625 u64 bounce_limit = 0xffffffff;
1626
1627 if (shost->unchecked_isa_dma)
1628 return BLK_BOUNCE_ISA;
1629 /*
1630 * Platforms with virtual-DMA translation
1631 * hardware have no practical limit.
1632 */
1633 if (!PCI_DMA_BUS_IS_PHYS)
1634 return BLK_BOUNCE_ANY;
1635
1636 host_dev = scsi_get_device(shost);
1637 if (host_dev && host_dev->dma_mask)
1638 bounce_limit = *host_dev->dma_mask;
1639
1640 return bounce_limit;
1641}
1642EXPORT_SYMBOL(scsi_calculate_bounce_limit);
1643
1644struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost,
1645 request_fn_proc *request_fn)
1646{
1647 struct request_queue *q;
1648 struct device *dev = shost->dma_dev;
1649
1650 q = blk_init_queue(request_fn, NULL);
1651 if (!q)
1652 return NULL;
1653
1654 /*
1655 * this limit is imposed by hardware restrictions
1656 */
1657 blk_queue_max_segments(q, min_t(unsigned short, shost->sg_tablesize,
1658 SCSI_MAX_SG_CHAIN_SEGMENTS));
1659
1660 if (scsi_host_prot_dma(shost)) {
1661 shost->sg_prot_tablesize =
1662 min_not_zero(shost->sg_prot_tablesize,
1663 (unsigned short)SCSI_MAX_PROT_SG_SEGMENTS);
1664 BUG_ON(shost->sg_prot_tablesize < shost->sg_tablesize);
1665 blk_queue_max_integrity_segments(q, shost->sg_prot_tablesize);
1666 }
1667
1668 blk_queue_max_hw_sectors(q, shost->max_sectors);
1669 blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));
1670 blk_queue_segment_boundary(q, shost->dma_boundary);
1671 dma_set_seg_boundary(dev, shost->dma_boundary);
1672
1673 blk_queue_max_segment_size(q, dma_get_max_seg_size(dev));
1674
1675 if (!shost->use_clustering)
1676 q->limits.cluster = 0;
1677
1678 /*
1679 * set a reasonable default alignment on word boundaries: the
1680 * host and device may alter it using
1681 * blk_queue_update_dma_alignment() later.
1682 */
1683 blk_queue_dma_alignment(q, 0x03);
1684
1685 return q;
1686}
1687EXPORT_SYMBOL(__scsi_alloc_queue);
1688
1689struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
1690{
1691 struct request_queue *q;
1692
1693 q = __scsi_alloc_queue(sdev->host, scsi_request_fn);
1694 if (!q)
1695 return NULL;
1696
1697 blk_queue_prep_rq(q, scsi_prep_fn);
1698 blk_queue_softirq_done(q, scsi_softirq_done);
1699 blk_queue_rq_timed_out(q, scsi_times_out);
1700 blk_queue_lld_busy(q, scsi_lld_busy);
1701 return q;
1702}
1703
1704/*
1705 * Function: scsi_block_requests()
1706 *
1707 * Purpose: Utility function used by low-level drivers to prevent further
1708 * commands from being queued to the device.
1709 *
1710 * Arguments: shost - Host in question
1711 *
1712 * Returns: Nothing
1713 *
1714 * Lock status: No locks are assumed held.
1715 *
1716 * Notes: There is no timer nor any other means by which the requests
1717 * get unblocked other than the low-level driver calling
1718 * scsi_unblock_requests().
1719 */
1720void scsi_block_requests(struct Scsi_Host *shost)
1721{
1722 shost->host_self_blocked = 1;
1723}
1724EXPORT_SYMBOL(scsi_block_requests);
1725
1726/*
1727 * Function: scsi_unblock_requests()
1728 *
1729 * Purpose: Utility function used by low-level drivers to allow further
1730 * commands from being queued to the device.
1731 *
1732 * Arguments: shost - Host in question
1733 *
1734 * Returns: Nothing
1735 *
1736 * Lock status: No locks are assumed held.
1737 *
1738 * Notes: There is no timer nor any other means by which the requests
1739 * get unblocked other than the low-level driver calling
1740 * scsi_unblock_requests().
1741 *
1742 * This is done as an API function so that changes to the
1743 * internals of the scsi mid-layer won't require wholesale
1744 * changes to drivers that use this feature.
1745 */
1746void scsi_unblock_requests(struct Scsi_Host *shost)
1747{
1748 shost->host_self_blocked = 0;
1749 scsi_run_host_queues(shost);
1750}
1751EXPORT_SYMBOL(scsi_unblock_requests);
1752
1753int __init scsi_init_queue(void)
1754{
1755 int i;
1756
1757 scsi_sdb_cache = kmem_cache_create("scsi_data_buffer",
1758 sizeof(struct scsi_data_buffer),
1759 0, 0, NULL);
1760 if (!scsi_sdb_cache) {
1761 printk(KERN_ERR "SCSI: can't init scsi sdb cache\n");
1762 return -ENOMEM;
1763 }
1764
1765 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1766 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1767 int size = sgp->size * sizeof(struct scatterlist);
1768
1769 sgp->slab = kmem_cache_create(sgp->name, size, 0,
1770 SLAB_HWCACHE_ALIGN, NULL);
1771 if (!sgp->slab) {
1772 printk(KERN_ERR "SCSI: can't init sg slab %s\n",
1773 sgp->name);
1774 goto cleanup_sdb;
1775 }
1776
1777 sgp->pool = mempool_create_slab_pool(SG_MEMPOOL_SIZE,
1778 sgp->slab);
1779 if (!sgp->pool) {
1780 printk(KERN_ERR "SCSI: can't init sg mempool %s\n",
1781 sgp->name);
1782 goto cleanup_sdb;
1783 }
1784 }
1785
1786 return 0;
1787
1788cleanup_sdb:
1789 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1790 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1791 if (sgp->pool)
1792 mempool_destroy(sgp->pool);
1793 if (sgp->slab)
1794 kmem_cache_destroy(sgp->slab);
1795 }
1796 kmem_cache_destroy(scsi_sdb_cache);
1797
1798 return -ENOMEM;
1799}
1800
1801void scsi_exit_queue(void)
1802{
1803 int i;
1804
1805 kmem_cache_destroy(scsi_sdb_cache);
1806
1807 for (i = 0; i < SG_MEMPOOL_NR; i++) {
1808 struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
1809 mempool_destroy(sgp->pool);
1810 kmem_cache_destroy(sgp->slab);
1811 }
1812}
1813
1814/**
1815 * scsi_mode_select - issue a mode select
1816 * @sdev: SCSI device to be queried
1817 * @pf: Page format bit (1 == standard, 0 == vendor specific)
1818 * @sp: Save page bit (0 == don't save, 1 == save)
1819 * @modepage: mode page being requested
1820 * @buffer: request buffer (may not be smaller than eight bytes)
1821 * @len: length of request buffer.
1822 * @timeout: command timeout
1823 * @retries: number of retries before failing
1824 * @data: returns a structure abstracting the mode header data
1825 * @sshdr: place to put sense data (or NULL if no sense to be collected).
1826 * must be SCSI_SENSE_BUFFERSIZE big.
1827 *
1828 * Returns zero if successful; negative error number or scsi
1829 * status on error
1830 *
1831 */
1832int
1833scsi_mode_select(struct scsi_device *sdev, int pf, int sp, int modepage,
1834 unsigned char *buffer, int len, int timeout, int retries,
1835 struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
1836{
1837 unsigned char cmd[10];
1838 unsigned char *real_buffer;
1839 int ret;
1840
1841 memset(cmd, 0, sizeof(cmd));
1842 cmd[1] = (pf ? 0x10 : 0) | (sp ? 0x01 : 0);
1843
1844 if (sdev->use_10_for_ms) {
1845 if (len > 65535)
1846 return -EINVAL;
1847 real_buffer = kmalloc(8 + len, GFP_KERNEL);
1848 if (!real_buffer)
1849 return -ENOMEM;
1850 memcpy(real_buffer + 8, buffer, len);
1851 len += 8;
1852 real_buffer[0] = 0;
1853 real_buffer[1] = 0;
1854 real_buffer[2] = data->medium_type;
1855 real_buffer[3] = data->device_specific;
1856 real_buffer[4] = data->longlba ? 0x01 : 0;
1857 real_buffer[5] = 0;
1858 real_buffer[6] = data->block_descriptor_length >> 8;
1859 real_buffer[7] = data->block_descriptor_length;
1860
1861 cmd[0] = MODE_SELECT_10;
1862 cmd[7] = len >> 8;
1863 cmd[8] = len;
1864 } else {
1865 if (len > 255 || data->block_descriptor_length > 255 ||
1866 data->longlba)
1867 return -EINVAL;
1868
1869 real_buffer = kmalloc(4 + len, GFP_KERNEL);
1870 if (!real_buffer)
1871 return -ENOMEM;
1872 memcpy(real_buffer + 4, buffer, len);
1873 len += 4;
1874 real_buffer[0] = 0;
1875 real_buffer[1] = data->medium_type;
1876 real_buffer[2] = data->device_specific;
1877 real_buffer[3] = data->block_descriptor_length;
1878
1879
1880 cmd[0] = MODE_SELECT;
1881 cmd[4] = len;
1882 }
1883
1884 ret = scsi_execute_req(sdev, cmd, DMA_TO_DEVICE, real_buffer, len,
1885 sshdr, timeout, retries, NULL);
1886 kfree(real_buffer);
1887 return ret;
1888}
1889EXPORT_SYMBOL_GPL(scsi_mode_select);
1890
1891/**
1892 * scsi_mode_sense - issue a mode sense, falling back from 10 to six bytes if necessary.
1893 * @sdev: SCSI device to be queried
1894 * @dbd: set if mode sense will allow block descriptors to be returned
1895 * @modepage: mode page being requested
1896 * @buffer: request buffer (may not be smaller than eight bytes)
1897 * @len: length of request buffer.
1898 * @timeout: command timeout
1899 * @retries: number of retries before failing
1900 * @data: returns a structure abstracting the mode header data
1901 * @sshdr: place to put sense data (or NULL if no sense to be collected).
1902 * must be SCSI_SENSE_BUFFERSIZE big.
1903 *
1904 * Returns zero if unsuccessful, or the header offset (either 4
1905 * or 8 depending on whether a six or ten byte command was
1906 * issued) if successful.
1907 */
1908int
1909scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
1910 unsigned char *buffer, int len, int timeout, int retries,
1911 struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
1912{
1913 unsigned char cmd[12];
1914 int use_10_for_ms;
1915 int header_length;
1916 int result;
1917 struct scsi_sense_hdr my_sshdr;
1918
1919 memset(data, 0, sizeof(*data));
1920 memset(&cmd[0], 0, 12);
1921 cmd[1] = dbd & 0x18; /* allows DBD and LLBA bits */
1922 cmd[2] = modepage;
1923
1924 /* caller might not be interested in sense, but we need it */
1925 if (!sshdr)
1926 sshdr = &my_sshdr;
1927
1928 retry:
1929 use_10_for_ms = sdev->use_10_for_ms;
1930
1931 if (use_10_for_ms) {
1932 if (len < 8)
1933 len = 8;
1934
1935 cmd[0] = MODE_SENSE_10;
1936 cmd[8] = len;
1937 header_length = 8;
1938 } else {
1939 if (len < 4)
1940 len = 4;
1941
1942 cmd[0] = MODE_SENSE;
1943 cmd[4] = len;
1944 header_length = 4;
1945 }
1946
1947 memset(buffer, 0, len);
1948
1949 result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len,
1950 sshdr, timeout, retries, NULL);
1951
1952 /* This code looks awful: what it's doing is making sure an
1953 * ILLEGAL REQUEST sense return identifies the actual command
1954 * byte as the problem. MODE_SENSE commands can return
1955 * ILLEGAL REQUEST if the code page isn't supported */
1956
1957 if (use_10_for_ms && !scsi_status_is_good(result) &&
1958 (driver_byte(result) & DRIVER_SENSE)) {
1959 if (scsi_sense_valid(sshdr)) {
1960 if ((sshdr->sense_key == ILLEGAL_REQUEST) &&
1961 (sshdr->asc == 0x20) && (sshdr->ascq == 0)) {
1962 /*
1963 * Invalid command operation code
1964 */
1965 sdev->use_10_for_ms = 0;
1966 goto retry;
1967 }
1968 }
1969 }
1970
1971 if(scsi_status_is_good(result)) {
1972 if (unlikely(buffer[0] == 0x86 && buffer[1] == 0x0b &&
1973 (modepage == 6 || modepage == 8))) {
1974 /* Initio breakage? */
1975 header_length = 0;
1976 data->length = 13;
1977 data->medium_type = 0;
1978 data->device_specific = 0;
1979 data->longlba = 0;
1980 data->block_descriptor_length = 0;
1981 } else if(use_10_for_ms) {
1982 data->length = buffer[0]*256 + buffer[1] + 2;
1983 data->medium_type = buffer[2];
1984 data->device_specific = buffer[3];
1985 data->longlba = buffer[4] & 0x01;
1986 data->block_descriptor_length = buffer[6]*256
1987 + buffer[7];
1988 } else {
1989 data->length = buffer[0] + 1;
1990 data->medium_type = buffer[1];
1991 data->device_specific = buffer[2];
1992 data->block_descriptor_length = buffer[3];
1993 }
1994 data->header_length = header_length;
1995 }
1996
1997 return result;
1998}
1999EXPORT_SYMBOL(scsi_mode_sense);
2000
2001/**
2002 * scsi_test_unit_ready - test if unit is ready
2003 * @sdev: scsi device to change the state of.
2004 * @timeout: command timeout
2005 * @retries: number of retries before failing
2006 * @sshdr_external: Optional pointer to struct scsi_sense_hdr for
2007 * returning sense. Make sure that this is cleared before passing
2008 * in.
2009 *
2010 * Returns zero if unsuccessful or an error if TUR failed. For
2011 * removable media, UNIT_ATTENTION sets ->changed flag.
2012 **/
2013int
2014scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries,
2015 struct scsi_sense_hdr *sshdr_external)
2016{
2017 char cmd[] = {
2018 TEST_UNIT_READY, 0, 0, 0, 0, 0,
2019 };
2020 struct scsi_sense_hdr *sshdr;
2021 int result;
2022
2023 if (!sshdr_external)
2024 sshdr = kzalloc(sizeof(*sshdr), GFP_KERNEL);
2025 else
2026 sshdr = sshdr_external;
2027
2028 /* try to eat the UNIT_ATTENTION if there are enough retries */
2029 do {
2030 result = scsi_execute_req(sdev, cmd, DMA_NONE, NULL, 0, sshdr,
2031 timeout, retries, NULL);
2032 if (sdev->removable && scsi_sense_valid(sshdr) &&
2033 sshdr->sense_key == UNIT_ATTENTION)
2034 sdev->changed = 1;
2035 } while (scsi_sense_valid(sshdr) &&
2036 sshdr->sense_key == UNIT_ATTENTION && --retries);
2037
2038 if (!sshdr_external)
2039 kfree(sshdr);
2040 return result;
2041}
2042EXPORT_SYMBOL(scsi_test_unit_ready);
2043
2044/**
2045 * scsi_device_set_state - Take the given device through the device state model.
2046 * @sdev: scsi device to change the state of.
2047 * @state: state to change to.
2048 *
2049 * Returns zero if unsuccessful or an error if the requested
2050 * transition is illegal.
2051 */
2052int
2053scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
2054{
2055 enum scsi_device_state oldstate = sdev->sdev_state;
2056
2057 if (state == oldstate)
2058 return 0;
2059
2060 switch (state) {
2061 case SDEV_CREATED:
2062 switch (oldstate) {
2063 case SDEV_CREATED_BLOCK:
2064 break;
2065 default:
2066 goto illegal;
2067 }
2068 break;
2069
2070 case SDEV_RUNNING:
2071 switch (oldstate) {
2072 case SDEV_CREATED:
2073 case SDEV_OFFLINE:
2074 case SDEV_QUIESCE:
2075 case SDEV_BLOCK:
2076 break;
2077 default:
2078 goto illegal;
2079 }
2080 break;
2081
2082 case SDEV_QUIESCE:
2083 switch (oldstate) {
2084 case SDEV_RUNNING:
2085 case SDEV_OFFLINE:
2086 break;
2087 default:
2088 goto illegal;
2089 }
2090 break;
2091
2092 case SDEV_OFFLINE:
2093 switch (oldstate) {
2094 case SDEV_CREATED:
2095 case SDEV_RUNNING:
2096 case SDEV_QUIESCE:
2097 case SDEV_BLOCK:
2098 break;
2099 default:
2100 goto illegal;
2101 }
2102 break;
2103
2104 case SDEV_BLOCK:
2105 switch (oldstate) {
2106 case SDEV_RUNNING:
2107 case SDEV_CREATED_BLOCK:
2108 break;
2109 default:
2110 goto illegal;
2111 }
2112 break;
2113
2114 case SDEV_CREATED_BLOCK:
2115 switch (oldstate) {
2116 case SDEV_CREATED:
2117 break;
2118 default:
2119 goto illegal;
2120 }
2121 break;
2122
2123 case SDEV_CANCEL:
2124 switch (oldstate) {
2125 case SDEV_CREATED:
2126 case SDEV_RUNNING:
2127 case SDEV_QUIESCE:
2128 case SDEV_OFFLINE:
2129 case SDEV_BLOCK:
2130 break;
2131 default:
2132 goto illegal;
2133 }
2134 break;
2135
2136 case SDEV_DEL:
2137 switch (oldstate) {
2138 case SDEV_CREATED:
2139 case SDEV_RUNNING:
2140 case SDEV_OFFLINE:
2141 case SDEV_CANCEL:
2142 break;
2143 default:
2144 goto illegal;
2145 }
2146 break;
2147
2148 }
2149 sdev->sdev_state = state;
2150 return 0;
2151
2152 illegal:
2153 SCSI_LOG_ERROR_RECOVERY(1,
2154 sdev_printk(KERN_ERR, sdev,
2155 "Illegal state transition %s->%s\n",
2156 scsi_device_state_name(oldstate),
2157 scsi_device_state_name(state))
2158 );
2159 return -EINVAL;
2160}
2161EXPORT_SYMBOL(scsi_device_set_state);
2162
2163/**
2164 * sdev_evt_emit - emit a single SCSI device uevent
2165 * @sdev: associated SCSI device
2166 * @evt: event to emit
2167 *
2168 * Send a single uevent (scsi_event) to the associated scsi_device.
2169 */
2170static void scsi_evt_emit(struct scsi_device *sdev, struct scsi_event *evt)
2171{
2172 int idx = 0;
2173 char *envp[3];
2174
2175 switch (evt->evt_type) {
2176 case SDEV_EVT_MEDIA_CHANGE:
2177 envp[idx++] = "SDEV_MEDIA_CHANGE=1";
2178 break;
2179
2180 default:
2181 /* do nothing */
2182 break;
2183 }
2184
2185 envp[idx++] = NULL;
2186
2187 kobject_uevent_env(&sdev->sdev_gendev.kobj, KOBJ_CHANGE, envp);
2188}
2189
2190/**
2191 * sdev_evt_thread - send a uevent for each scsi event
2192 * @work: work struct for scsi_device
2193 *
2194 * Dispatch queued events to their associated scsi_device kobjects
2195 * as uevents.
2196 */
2197void scsi_evt_thread(struct work_struct *work)
2198{
2199 struct scsi_device *sdev;
2200 LIST_HEAD(event_list);
2201
2202 sdev = container_of(work, struct scsi_device, event_work);
2203
2204 while (1) {
2205 struct scsi_event *evt;
2206 struct list_head *this, *tmp;
2207 unsigned long flags;
2208
2209 spin_lock_irqsave(&sdev->list_lock, flags);
2210 list_splice_init(&sdev->event_list, &event_list);
2211 spin_unlock_irqrestore(&sdev->list_lock, flags);
2212
2213 if (list_empty(&event_list))
2214 break;
2215
2216 list_for_each_safe(this, tmp, &event_list) {
2217 evt = list_entry(this, struct scsi_event, node);
2218 list_del(&evt->node);
2219 scsi_evt_emit(sdev, evt);
2220 kfree(evt);
2221 }
2222 }
2223}
2224
2225/**
2226 * sdev_evt_send - send asserted event to uevent thread
2227 * @sdev: scsi_device event occurred on
2228 * @evt: event to send
2229 *
2230 * Assert scsi device event asynchronously.
2231 */
2232void sdev_evt_send(struct scsi_device *sdev, struct scsi_event *evt)
2233{
2234 unsigned long flags;
2235
2236#if 0
2237 /* FIXME: currently this check eliminates all media change events
2238 * for polled devices. Need to update to discriminate between AN
2239 * and polled events */
2240 if (!test_bit(evt->evt_type, sdev->supported_events)) {
2241 kfree(evt);
2242 return;
2243 }
2244#endif
2245
2246 spin_lock_irqsave(&sdev->list_lock, flags);
2247 list_add_tail(&evt->node, &sdev->event_list);
2248 schedule_work(&sdev->event_work);
2249 spin_unlock_irqrestore(&sdev->list_lock, flags);
2250}
2251EXPORT_SYMBOL_GPL(sdev_evt_send);
2252
2253/**
2254 * sdev_evt_alloc - allocate a new scsi event
2255 * @evt_type: type of event to allocate
2256 * @gfpflags: GFP flags for allocation
2257 *
2258 * Allocates and returns a new scsi_event.
2259 */
2260struct scsi_event *sdev_evt_alloc(enum scsi_device_event evt_type,
2261 gfp_t gfpflags)
2262{
2263 struct scsi_event *evt = kzalloc(sizeof(struct scsi_event), gfpflags);
2264 if (!evt)
2265 return NULL;
2266
2267 evt->evt_type = evt_type;
2268 INIT_LIST_HEAD(&evt->node);
2269
2270 /* evt_type-specific initialization, if any */
2271 switch (evt_type) {
2272 case SDEV_EVT_MEDIA_CHANGE:
2273 default:
2274 /* do nothing */
2275 break;
2276 }
2277
2278 return evt;
2279}
2280EXPORT_SYMBOL_GPL(sdev_evt_alloc);
2281
2282/**
2283 * sdev_evt_send_simple - send asserted event to uevent thread
2284 * @sdev: scsi_device event occurred on
2285 * @evt_type: type of event to send
2286 * @gfpflags: GFP flags for allocation
2287 *
2288 * Assert scsi device event asynchronously, given an event type.
2289 */
2290void sdev_evt_send_simple(struct scsi_device *sdev,
2291 enum scsi_device_event evt_type, gfp_t gfpflags)
2292{
2293 struct scsi_event *evt = sdev_evt_alloc(evt_type, gfpflags);
2294 if (!evt) {
2295 sdev_printk(KERN_ERR, sdev, "event %d eaten due to OOM\n",
2296 evt_type);
2297 return;
2298 }
2299
2300 sdev_evt_send(sdev, evt);
2301}
2302EXPORT_SYMBOL_GPL(sdev_evt_send_simple);
2303
2304/**
2305 * scsi_device_quiesce - Block user issued commands.
2306 * @sdev: scsi device to quiesce.
2307 *
2308 * This works by trying to transition to the SDEV_QUIESCE state
2309 * (which must be a legal transition). When the device is in this
2310 * state, only special requests will be accepted, all others will
2311 * be deferred. Since special requests may also be requeued requests,
2312 * a successful return doesn't guarantee the device will be
2313 * totally quiescent.
2314 *
2315 * Must be called with user context, may sleep.
2316 *
2317 * Returns zero if unsuccessful or an error if not.
2318 */
2319int
2320scsi_device_quiesce(struct scsi_device *sdev)
2321{
2322 int err = scsi_device_set_state(sdev, SDEV_QUIESCE);
2323 if (err)
2324 return err;
2325
2326 scsi_run_queue(sdev->request_queue);
2327 while (sdev->device_busy) {
2328 msleep_interruptible(200);
2329 scsi_run_queue(sdev->request_queue);
2330 }
2331 return 0;
2332}
2333EXPORT_SYMBOL(scsi_device_quiesce);
2334
2335/**
2336 * scsi_device_resume - Restart user issued commands to a quiesced device.
2337 * @sdev: scsi device to resume.
2338 *
2339 * Moves the device from quiesced back to running and restarts the
2340 * queues.
2341 *
2342 * Must be called with user context, may sleep.
2343 */
2344void scsi_device_resume(struct scsi_device *sdev)
2345{
2346 /* check if the device state was mutated prior to resume, and if
2347 * so assume the state is being managed elsewhere (for example
2348 * device deleted during suspend)
2349 */
2350 if (sdev->sdev_state != SDEV_QUIESCE ||
2351 scsi_device_set_state(sdev, SDEV_RUNNING))
2352 return;
2353 scsi_run_queue(sdev->request_queue);
2354}
2355EXPORT_SYMBOL(scsi_device_resume);
2356
2357static void
2358device_quiesce_fn(struct scsi_device *sdev, void *data)
2359{
2360 scsi_device_quiesce(sdev);
2361}
2362
2363void
2364scsi_target_quiesce(struct scsi_target *starget)
2365{
2366 starget_for_each_device(starget, NULL, device_quiesce_fn);
2367}
2368EXPORT_SYMBOL(scsi_target_quiesce);
2369
2370static void
2371device_resume_fn(struct scsi_device *sdev, void *data)
2372{
2373 scsi_device_resume(sdev);
2374}
2375
2376void
2377scsi_target_resume(struct scsi_target *starget)
2378{
2379 starget_for_each_device(starget, NULL, device_resume_fn);
2380}
2381EXPORT_SYMBOL(scsi_target_resume);
2382
2383/**
2384 * scsi_internal_device_block - internal function to put a device temporarily into the SDEV_BLOCK state
2385 * @sdev: device to block
2386 *
2387 * Block request made by scsi lld's to temporarily stop all
2388 * scsi commands on the specified device. Called from interrupt
2389 * or normal process context.
2390 *
2391 * Returns zero if successful or error if not
2392 *
2393 * Notes:
2394 * This routine transitions the device to the SDEV_BLOCK state
2395 * (which must be a legal transition). When the device is in this
2396 * state, all commands are deferred until the scsi lld reenables
2397 * the device with scsi_device_unblock or device_block_tmo fires.
2398 * This routine assumes the host_lock is held on entry.
2399 */
2400int
2401scsi_internal_device_block(struct scsi_device *sdev)
2402{
2403 struct request_queue *q = sdev->request_queue;
2404 unsigned long flags;
2405 int err = 0;
2406
2407 err = scsi_device_set_state(sdev, SDEV_BLOCK);
2408 if (err) {
2409 err = scsi_device_set_state(sdev, SDEV_CREATED_BLOCK);
2410
2411 if (err)
2412 return err;
2413 }
2414
2415 /*
2416 * The device has transitioned to SDEV_BLOCK. Stop the
2417 * block layer from calling the midlayer with this device's
2418 * request queue.
2419 */
2420 spin_lock_irqsave(q->queue_lock, flags);
2421 blk_stop_queue(q);
2422 spin_unlock_irqrestore(q->queue_lock, flags);
2423
2424 return 0;
2425}
2426EXPORT_SYMBOL_GPL(scsi_internal_device_block);
2427
2428/**
2429 * scsi_internal_device_unblock - resume a device after a block request
2430 * @sdev: device to resume
2431 *
2432 * Called by scsi lld's or the midlayer to restart the device queue
2433 * for the previously suspended scsi device. Called from interrupt or
2434 * normal process context.
2435 *
2436 * Returns zero if successful or error if not.
2437 *
2438 * Notes:
2439 * This routine transitions the device to the SDEV_RUNNING state
2440 * (which must be a legal transition) allowing the midlayer to
2441 * goose the queue for this device. This routine assumes the
2442 * host_lock is held upon entry.
2443 */
2444int
2445scsi_internal_device_unblock(struct scsi_device *sdev)
2446{
2447 struct request_queue *q = sdev->request_queue;
2448 unsigned long flags;
2449
2450 /*
2451 * Try to transition the scsi device to SDEV_RUNNING
2452 * and goose the device queue if successful.
2453 */
2454 if (sdev->sdev_state == SDEV_BLOCK)
2455 sdev->sdev_state = SDEV_RUNNING;
2456 else if (sdev->sdev_state == SDEV_CREATED_BLOCK)
2457 sdev->sdev_state = SDEV_CREATED;
2458 else if (sdev->sdev_state != SDEV_CANCEL &&
2459 sdev->sdev_state != SDEV_OFFLINE)
2460 return -EINVAL;
2461
2462 spin_lock_irqsave(q->queue_lock, flags);
2463 blk_start_queue(q);
2464 spin_unlock_irqrestore(q->queue_lock, flags);
2465
2466 return 0;
2467}
2468EXPORT_SYMBOL_GPL(scsi_internal_device_unblock);
2469
2470static void
2471device_block(struct scsi_device *sdev, void *data)
2472{
2473 scsi_internal_device_block(sdev);
2474}
2475
2476static int
2477target_block(struct device *dev, void *data)
2478{
2479 if (scsi_is_target_device(dev))
2480 starget_for_each_device(to_scsi_target(dev), NULL,
2481 device_block);
2482 return 0;
2483}
2484
2485void
2486scsi_target_block(struct device *dev)
2487{
2488 if (scsi_is_target_device(dev))
2489 starget_for_each_device(to_scsi_target(dev), NULL,
2490 device_block);
2491 else
2492 device_for_each_child(dev, NULL, target_block);
2493}
2494EXPORT_SYMBOL_GPL(scsi_target_block);
2495
2496static void
2497device_unblock(struct scsi_device *sdev, void *data)
2498{
2499 scsi_internal_device_unblock(sdev);
2500}
2501
2502static int
2503target_unblock(struct device *dev, void *data)
2504{
2505 if (scsi_is_target_device(dev))
2506 starget_for_each_device(to_scsi_target(dev), NULL,
2507 device_unblock);
2508 return 0;
2509}
2510
2511void
2512scsi_target_unblock(struct device *dev)
2513{
2514 if (scsi_is_target_device(dev))
2515 starget_for_each_device(to_scsi_target(dev), NULL,
2516 device_unblock);
2517 else
2518 device_for_each_child(dev, NULL, target_unblock);
2519}
2520EXPORT_SYMBOL_GPL(scsi_target_unblock);
2521
2522/**
2523 * scsi_kmap_atomic_sg - find and atomically map an sg-elemnt
2524 * @sgl: scatter-gather list
2525 * @sg_count: number of segments in sg
2526 * @offset: offset in bytes into sg, on return offset into the mapped area
2527 * @len: bytes to map, on return number of bytes mapped
2528 *
2529 * Returns virtual address of the start of the mapped page
2530 */
2531void *scsi_kmap_atomic_sg(struct scatterlist *sgl, int sg_count,
2532 size_t *offset, size_t *len)
2533{
2534 int i;
2535 size_t sg_len = 0, len_complete = 0;
2536 struct scatterlist *sg;
2537 struct page *page;
2538
2539 WARN_ON(!irqs_disabled());
2540
2541 for_each_sg(sgl, sg, sg_count, i) {
2542 len_complete = sg_len; /* Complete sg-entries */
2543 sg_len += sg->length;
2544 if (sg_len > *offset)
2545 break;
2546 }
2547
2548 if (unlikely(i == sg_count)) {
2549 printk(KERN_ERR "%s: Bytes in sg: %zu, requested offset %zu, "
2550 "elements %d\n",
2551 __func__, sg_len, *offset, sg_count);
2552 WARN_ON(1);
2553 return NULL;
2554 }
2555
2556 /* Offset starting from the beginning of first page in this sg-entry */
2557 *offset = *offset - len_complete + sg->offset;
2558
2559 /* Assumption: contiguous pages can be accessed as "page + i" */
2560 page = nth_page(sg_page(sg), (*offset >> PAGE_SHIFT));
2561 *offset &= ~PAGE_MASK;
2562
2563 /* Bytes in this sg-entry from *offset to the end of the page */
2564 sg_len = PAGE_SIZE - *offset;
2565 if (*len > sg_len)
2566 *len = sg_len;
2567
2568 return kmap_atomic(page);
2569}
2570EXPORT_SYMBOL(scsi_kmap_atomic_sg);
2571
2572/**
2573 * scsi_kunmap_atomic_sg - atomically unmap a virtual address, previously mapped with scsi_kmap_atomic_sg
2574 * @virt: virtual address to be unmapped
2575 */
2576void scsi_kunmap_atomic_sg(void *virt)
2577{
2578 kunmap_atomic(virt);
2579}
2580EXPORT_SYMBOL(scsi_kunmap_atomic_sg);