1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * scsi.c Copyright (C) 1992 Drew Eckhardt
4 * Copyright (C) 1993, 1994, 1995, 1999 Eric Youngdale
5 * Copyright (C) 2002, 2003 Christoph Hellwig
6 *
7 * generic mid-level SCSI driver
8 * Initial versions: Drew Eckhardt
9 * Subsequent revisions: Eric Youngdale
10 *
11 * <drew@colorado.edu>
12 *
13 * Bug correction thanks go to :
14 * Rik Faith <faith@cs.unc.edu>
15 * Tommy Thorn <tthorn>
16 * Thomas Wuensche <tw@fgb1.fgb.mw.tu-muenchen.de>
17 *
18 * Modified by Eric Youngdale eric@andante.org or ericy@gnu.ai.mit.edu to
19 * add scatter-gather, multiple outstanding request, and other
20 * enhancements.
21 *
22 * Native multichannel, wide scsi, /proc/scsi and hot plugging
23 * support added by Michael Neuffer <mike@i-connect.net>
24 *
25 * Added request_module("scsi_hostadapter") for kerneld:
26 * (Put an "alias scsi_hostadapter your_hostadapter" in /etc/modprobe.conf)
27 * Bjorn Ekwall <bj0rn@blox.se>
28 * (changed to kmod)
29 *
30 * Major improvements to the timeout, abort, and reset processing,
31 * as well as performance modifications for large queue depths by
32 * Leonard N. Zubkoff <lnz@dandelion.com>
33 *
34 * Converted cli() code to spinlocks, Ingo Molnar
35 *
36 * Jiffies wrap fixes (host->resetting), 3 Dec 1998 Andrea Arcangeli
37 *
38 * out_of_space hacks, D. Gilbert (dpg) 990608
39 */
40
41 #include <linux/module.h>
42 #include <linux/moduleparam.h>
43 #include <linux/kernel.h>
44 #include <linux/timer.h>
45 #include <linux/string.h>
46 #include <linux/slab.h>
47 #include <linux/blkdev.h>
48 #include <linux/delay.h>
49 #include <linux/init.h>
50 #include <linux/completion.h>
51 #include <linux/unistd.h>
52 #include <linux/spinlock.h>
53 #include <linux/kmod.h>
54 #include <linux/interrupt.h>
55 #include <linux/notifier.h>
56 #include <linux/cpu.h>
57 #include <linux/mutex.h>
58 #include <linux/async.h>
59 #include <asm/unaligned.h>
60
61 #include <scsi/scsi.h>
62 #include <scsi/scsi_cmnd.h>
63 #include <scsi/scsi_dbg.h>
64 #include <scsi/scsi_device.h>
65 #include <scsi/scsi_driver.h>
66 #include <scsi/scsi_eh.h>
67 #include <scsi/scsi_host.h>
68 #include <scsi/scsi_tcq.h>
69
70 #include "scsi_priv.h"
71 #include "scsi_logging.h"
72
73 #define CREATE_TRACE_POINTS
74 #include <trace/events/scsi.h>
75
76 /*
77 * Definitions and constants.
78 */
79
80 /*
81 * Note - the initial logging level can be set here to log events at boot time.
82 * After the system is up, you may enable logging via the /proc interface.
83 */
84 unsigned int scsi_logging_level;
85 #if defined(CONFIG_SCSI_LOGGING)
86 EXPORT_SYMBOL(scsi_logging_level);
87 #endif
88
89 /*
90 * Domain for asynchronous system resume operations. It is marked 'exclusive'
91 * to avoid being included in the async_synchronize_full() that is invoked by
92 * dpm_resume().
93 */
94 ASYNC_DOMAIN_EXCLUSIVE(scsi_sd_pm_domain);
95 EXPORT_SYMBOL(scsi_sd_pm_domain);
96
97 /**
98 * scsi_put_command - Free a scsi command block
99 * @cmd: command block to free
100 *
101 * Returns: Nothing.
102 *
103 * Notes: The command must not belong to any lists.
104 */
105 void scsi_put_command(struct scsi_cmnd *cmd)
106 {
107 scsi_del_cmd_from_list(cmd);
108 BUG_ON(delayed_work_pending(&cmd->abort_work));
109 }
110
111 #ifdef CONFIG_SCSI_LOGGING
112 void scsi_log_send(struct scsi_cmnd *cmd)
113 {
114 unsigned int level;
115
116 /*
117 * If ML QUEUE log level is greater than or equal to:
118 *
119 * 1: nothing (match completion)
120 *
121 * 2: log opcode + command of all commands + cmd address
122 *
123 * 3: same as 2
124 *
125 * 4: same as 3
126 */
127 if (unlikely(scsi_logging_level)) {
128 level = SCSI_LOG_LEVEL(SCSI_LOG_MLQUEUE_SHIFT,
129 SCSI_LOG_MLQUEUE_BITS);
130 if (level > 1) {
131 scmd_printk(KERN_INFO, cmd,
132 "Send: scmd 0x%p\n", cmd);
133 scsi_print_command(cmd);
134 }
135 }
136 }
137
138 void scsi_log_completion(struct scsi_cmnd *cmd, int disposition)
139 {
140 unsigned int level;
141
142 /*
143 * If ML COMPLETE log level is greater than or equal to:
144 *
145 * 1: log disposition, result, opcode + command, and conditionally
146 * sense data for failures or non SUCCESS dispositions.
147 *
148 * 2: same as 1 but for all command completions.
149 *
150 * 3: same as 2
151 *
152 * 4: same as 3 plus dump extra junk
153 */
154 if (unlikely(scsi_logging_level)) {
155 level = SCSI_LOG_LEVEL(SCSI_LOG_MLCOMPLETE_SHIFT,
156 SCSI_LOG_MLCOMPLETE_BITS);
157 if (((level > 0) && (cmd->result || disposition != SUCCESS)) ||
158 (level > 1)) {
159 scsi_print_result(cmd, "Done", disposition);
160 scsi_print_command(cmd);
161 if (status_byte(cmd->result) == CHECK_CONDITION)
162 scsi_print_sense(cmd);
163 if (level > 3)
164 scmd_printk(KERN_INFO, cmd,
165 "scsi host busy %d failed %d\n",
166 scsi_host_busy(cmd->device->host),
167 cmd->device->host->host_failed);
168 }
169 }
170 }
171 #endif
172
173 /**
174 * scsi_finish_command - cleanup and pass command back to upper layer
175 * @cmd: the command
176 *
177 * Description: Pass command off to upper layer for finishing of I/O
178 * request, waking processes that are waiting on results,
179 * etc.
180 */
181 void scsi_finish_command(struct scsi_cmnd *cmd)
182 {
183 struct scsi_device *sdev = cmd->device;
184 struct scsi_target *starget = scsi_target(sdev);
185 struct Scsi_Host *shost = sdev->host;
186 struct scsi_driver *drv;
187 unsigned int good_bytes;
188
189 scsi_device_unbusy(sdev);
190
191 /*
192 * Clear the flags that say that the device/target/host is no longer
193 * capable of accepting new commands.
194 */
195 if (atomic_read(&shost->host_blocked))
196 atomic_set(&shost->host_blocked, 0);
197 if (atomic_read(&starget->target_blocked))
198 atomic_set(&starget->target_blocked, 0);
199 if (atomic_read(&sdev->device_blocked))
200 atomic_set(&sdev->device_blocked, 0);
201
202 /*
203 * If we have valid sense information, then some kind of recovery
204 * must have taken place. Make a note of this.
205 */
206 if (SCSI_SENSE_VALID(cmd))
207 cmd->result |= (DRIVER_SENSE << 24);
208
209 SCSI_LOG_MLCOMPLETE(4, sdev_printk(KERN_INFO, sdev,
210 "Notifying upper driver of completion "
211 "(result %x)\n", cmd->result));
212
213 good_bytes = scsi_bufflen(cmd);
214 if (!blk_rq_is_passthrough(cmd->request)) {
215 int old_good_bytes = good_bytes;
216 drv = scsi_cmd_to_driver(cmd);
217 if (drv->done)
218 good_bytes = drv->done(cmd);
219 /*
220 * USB may not give sense identifying bad sector and
221 * simply return a residue instead, so subtract off the
222 * residue if drv->done() error processing indicates no
223 * change to the completion length.
224 */
225 if (good_bytes == old_good_bytes)
226 good_bytes -= scsi_get_resid(cmd);
227 }
228 scsi_io_completion(cmd, good_bytes);
229 }
230
231 /**
232 * scsi_change_queue_depth - change a device's queue depth
233 * @sdev: SCSI Device in question
234 * @depth: number of commands allowed to be queued to the driver
235 *
236 * Sets the device queue depth and returns the new value.
237 */
238 int scsi_change_queue_depth(struct scsi_device *sdev, int depth)
239 {
240 if (depth > 0) {
241 sdev->queue_depth = depth;
242 wmb();
243 }
244
245 if (sdev->request_queue)
246 blk_set_queue_depth(sdev->request_queue, depth);
247
248 return sdev->queue_depth;
249 }
250 EXPORT_SYMBOL(scsi_change_queue_depth);
251
252 /**
253 * scsi_track_queue_full - track QUEUE_FULL events to adjust queue depth
254 * @sdev: SCSI Device in question
255 * @depth: Current number of outstanding SCSI commands on this device,
256 * not counting the one returned as QUEUE_FULL.
257 *
258 * Description: This function will track successive QUEUE_FULL events on a
259 * specific SCSI device to determine if and when there is a
260 * need to adjust the queue depth on the device.
261 *
262 * Returns: 0 - No change needed, >0 - Adjust queue depth to this new depth,
263 * -1 - Drop back to untagged operation using host->cmd_per_lun
264 * as the untagged command depth
265 *
266 * Lock Status: None held on entry
267 *
268 * Notes: Low level drivers may call this at any time and we will do
269 * "The Right Thing." We are interrupt context safe.
270 */
271 int scsi_track_queue_full(struct scsi_device *sdev, int depth)
272 {
273
274 /*
275 * Don't let QUEUE_FULLs on the same
276 * jiffies count, they could all be from
277 * same event.
278 */
279 if ((jiffies >> 4) == (sdev->last_queue_full_time >> 4))
280 return 0;
281
282 sdev->last_queue_full_time = jiffies;
283 if (sdev->last_queue_full_depth != depth) {
284 sdev->last_queue_full_count = 1;
285 sdev->last_queue_full_depth = depth;
286 } else {
287 sdev->last_queue_full_count++;
288 }
289
290 if (sdev->last_queue_full_count <= 10)
291 return 0;
292
293 return scsi_change_queue_depth(sdev, depth);
294 }
295 EXPORT_SYMBOL(scsi_track_queue_full);
296
297 /**
298 * scsi_vpd_inquiry - Request a device provide us with a VPD page
299 * @sdev: The device to ask
300 * @buffer: Where to put the result
301 * @page: Which Vital Product Data to return
302 * @len: The length of the buffer
303 *
304 * This is an internal helper function. You probably want to use
305 * scsi_get_vpd_page instead.
306 *
307 * Returns size of the vpd page on success or a negative error number.
308 */
309 static int scsi_vpd_inquiry(struct scsi_device *sdev, unsigned char *buffer,
310 u8 page, unsigned len)
311 {
312 int result;
313 unsigned char cmd[16];
314
315 if (len < 4)
316 return -EINVAL;
317
318 cmd[0] = INQUIRY;
319 cmd[1] = 1; /* EVPD */
320 cmd[2] = page;
321 cmd[3] = len >> 8;
322 cmd[4] = len & 0xff;
323 cmd[5] = 0; /* Control byte */
324
325 /*
326 * I'm not convinced we need to try quite this hard to get VPD, but
327 * all the existing users tried this hard.
328 */
329 result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer,
330 len, NULL, 30 * HZ, 3, NULL);
331 if (result)
332 return -EIO;
333
334 /* Sanity check that we got the page back that we asked for */
335 if (buffer[1] != page)
336 return -EIO;
337
338 return get_unaligned_be16(&buffer[2]) + 4;
339 }
340
341 /**
342 * scsi_get_vpd_page - Get Vital Product Data from a SCSI device
343 * @sdev: The device to ask
344 * @page: Which Vital Product Data to return
345 * @buf: where to store the VPD
346 * @buf_len: number of bytes in the VPD buffer area
347 *
348 * SCSI devices may optionally supply Vital Product Data. Each 'page'
349 * of VPD is defined in the appropriate SCSI document (eg SPC, SBC).
350 * If the device supports this VPD page, this routine returns a pointer
351 * to a buffer containing the data from that page. The caller is
352 * responsible for calling kfree() on this pointer when it is no longer
353 * needed. If we cannot retrieve the VPD page this routine returns %NULL.
354 */
355 int scsi_get_vpd_page(struct scsi_device *sdev, u8 page, unsigned char *buf,
356 int buf_len)
357 {
358 int i, result;
359
360 if (sdev->skip_vpd_pages)
361 goto fail;
362
363 /* Ask for all the pages supported by this device */
364 result = scsi_vpd_inquiry(sdev, buf, 0, buf_len);
365 if (result < 4)
366 goto fail;
367
368 /* If the user actually wanted this page, we can skip the rest */
369 if (page == 0)
370 return 0;
371
372 for (i = 4; i < min(result, buf_len); i++)
373 if (buf[i] == page)
374 goto found;
375
376 if (i < result && i >= buf_len)
377 /* ran off the end of the buffer, give us benefit of doubt */
378 goto found;
379 /* The device claims it doesn't support the requested page */
380 goto fail;
381
382 found:
383 result = scsi_vpd_inquiry(sdev, buf, page, buf_len);
384 if (result < 0)
385 goto fail;
386
387 return 0;
388
389 fail:
390 return -EINVAL;
391 }
392 EXPORT_SYMBOL_GPL(scsi_get_vpd_page);
393
394 /**
395 * scsi_get_vpd_buf - Get Vital Product Data from a SCSI device
396 * @sdev: The device to ask
397 * @page: Which Vital Product Data to return
398 *
399 * Returns %NULL upon failure.
400 */
401 static struct scsi_vpd *scsi_get_vpd_buf(struct scsi_device *sdev, u8 page)
402 {
403 struct scsi_vpd *vpd_buf;
404 int vpd_len = SCSI_VPD_PG_LEN, result;
405
406 retry_pg:
407 vpd_buf = kmalloc(sizeof(*vpd_buf) + vpd_len, GFP_KERNEL);
408 if (!vpd_buf)
409 return NULL;
410
411 result = scsi_vpd_inquiry(sdev, vpd_buf->data, page, vpd_len);
412 if (result < 0) {
413 kfree(vpd_buf);
414 return NULL;
415 }
416 if (result > vpd_len) {
417 vpd_len = result;
418 kfree(vpd_buf);
419 goto retry_pg;
420 }
421
422 vpd_buf->len = result;
423
424 return vpd_buf;
425 }
426
427 static void scsi_update_vpd_page(struct scsi_device *sdev, u8 page,
428 struct scsi_vpd __rcu **sdev_vpd_buf)
429 {
430 struct scsi_vpd *vpd_buf;
431
432 vpd_buf = scsi_get_vpd_buf(sdev, page);
433 if (!vpd_buf)
434 return;
435
436 mutex_lock(&sdev->inquiry_mutex);
437 rcu_swap_protected(*sdev_vpd_buf, vpd_buf,
438 lockdep_is_held(&sdev->inquiry_mutex));
439 mutex_unlock(&sdev->inquiry_mutex);
440
441 if (vpd_buf)
442 kfree_rcu(vpd_buf, rcu);
443 }
444
445 /**
446 * scsi_attach_vpd - Attach Vital Product Data to a SCSI device structure
447 * @sdev: The device to ask
448 *
449 * Attach the 'Device Identification' VPD page (0x83) and the
450 * 'Unit Serial Number' VPD page (0x80) to a SCSI device
451 * structure. This information can be used to identify the device
452 * uniquely.
453 */
454 void scsi_attach_vpd(struct scsi_device *sdev)
455 {
456 int i;
457 struct scsi_vpd *vpd_buf;
458
459 if (!scsi_device_supports_vpd(sdev))
460 return;
461
462 /* Ask for all the pages supported by this device */
463 vpd_buf = scsi_get_vpd_buf(sdev, 0);
464 if (!vpd_buf)
465 return;
466
467 for (i = 4; i < vpd_buf->len; i++) {
468 if (vpd_buf->data[i] == 0x80)
469 scsi_update_vpd_page(sdev, 0x80, &sdev->vpd_pg80);
470 if (vpd_buf->data[i] == 0x83)
471 scsi_update_vpd_page(sdev, 0x83, &sdev->vpd_pg83);
472 }
473 kfree(vpd_buf);
474 }
475
476 /**
477 * scsi_report_opcode - Find out if a given command opcode is supported
478 * @sdev: scsi device to query
479 * @buffer: scratch buffer (must be at least 20 bytes long)
480 * @len: length of buffer
481 * @opcode: opcode for command to look up
482 *
483 * Uses the REPORT SUPPORTED OPERATION CODES to look up the given
484 * opcode. Returns -EINVAL if RSOC fails, 0 if the command opcode is
485 * unsupported and 1 if the device claims to support the command.
486 */
487 int scsi_report_opcode(struct scsi_device *sdev, unsigned char *buffer,
488 unsigned int len, unsigned char opcode)
489 {
490 unsigned char cmd[16];
491 struct scsi_sense_hdr sshdr;
492 int result;
493
494 if (sdev->no_report_opcodes || sdev->scsi_level < SCSI_SPC_3)
495 return -EINVAL;
496
497 memset(cmd, 0, 16);
498 cmd[0] = MAINTENANCE_IN;
499 cmd[1] = MI_REPORT_SUPPORTED_OPERATION_CODES;
500 cmd[2] = 1; /* One command format */
501 cmd[3] = opcode;
502 put_unaligned_be32(len, &cmd[6]);
503 memset(buffer, 0, len);
504
505 result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len,
506 &sshdr, 30 * HZ, 3, NULL);
507
508 if (result && scsi_sense_valid(&sshdr) &&
509 sshdr.sense_key == ILLEGAL_REQUEST &&
510 (sshdr.asc == 0x20 || sshdr.asc == 0x24) && sshdr.ascq == 0x00)
511 return -EINVAL;
512
513 if ((buffer[1] & 3) == 3) /* Command supported */
514 return 1;
515
516 return 0;
517 }
518 EXPORT_SYMBOL(scsi_report_opcode);
519
520 /**
521 * scsi_device_get - get an additional reference to a scsi_device
522 * @sdev: device to get a reference to
523 *
524 * Description: Gets a reference to the scsi_device and increments the use count
525 * of the underlying LLDD module. You must hold host_lock of the
526 * parent Scsi_Host or already have a reference when calling this.
527 *
528 * This will fail if a device is deleted or cancelled, or when the LLD module
529 * is in the process of being unloaded.
530 */
531 int scsi_device_get(struct scsi_device *sdev)
532 {
533 if (sdev->sdev_state == SDEV_DEL || sdev->sdev_state == SDEV_CANCEL)
534 goto fail;
535 if (!get_device(&sdev->sdev_gendev))
536 goto fail;
537 if (!try_module_get(sdev->host->hostt->module))
538 goto fail_put_device;
539 return 0;
540
541 fail_put_device:
542 put_device(&sdev->sdev_gendev);
543 fail:
544 return -ENXIO;
545 }
546 EXPORT_SYMBOL(scsi_device_get);
547
548 /**
549 * scsi_device_put - release a reference to a scsi_device
550 * @sdev: device to release a reference on.
551 *
552 * Description: Release a reference to the scsi_device and decrements the use
553 * count of the underlying LLDD module. The device is freed once the last
554 * user vanishes.
555 */
556 void scsi_device_put(struct scsi_device *sdev)
557 {
558 module_put(sdev->host->hostt->module);
559 put_device(&sdev->sdev_gendev);
560 }
561 EXPORT_SYMBOL(scsi_device_put);
562
563 /* helper for shost_for_each_device, see that for documentation */
564 struct scsi_device *__scsi_iterate_devices(struct Scsi_Host *shost,
565 struct scsi_device *prev)
566 {
567 struct list_head *list = (prev ? &prev->siblings : &shost->__devices);
568 struct scsi_device *next = NULL;
569 unsigned long flags;
570
571 spin_lock_irqsave(shost->host_lock, flags);
572 while (list->next != &shost->__devices) {
573 next = list_entry(list->next, struct scsi_device, siblings);
574 /* skip devices that we can't get a reference to */
575 if (!scsi_device_get(next))
576 break;
577 next = NULL;
578 list = list->next;
579 }
580 spin_unlock_irqrestore(shost->host_lock, flags);
581
582 if (prev)
583 scsi_device_put(prev);
584 return next;
585 }
586 EXPORT_SYMBOL(__scsi_iterate_devices);
587
588 /**
589 * starget_for_each_device - helper to walk all devices of a target
590 * @starget: target whose devices we want to iterate over.
591 * @data: Opaque passed to each function call.
592 * @fn: Function to call on each device
593 *
594 * This traverses over each device of @starget. The devices have
595 * a reference that must be released by scsi_host_put when breaking
596 * out of the loop.
597 */
598 void starget_for_each_device(struct scsi_target *starget, void *data,
599 void (*fn)(struct scsi_device *, void *))
600 {
601 struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
602 struct scsi_device *sdev;
603
604 shost_for_each_device(sdev, shost) {
605 if ((sdev->channel == starget->channel) &&
606 (sdev->id == starget->id))
607 fn(sdev, data);
608 }
609 }
610 EXPORT_SYMBOL(starget_for_each_device);
611
612 /**
613 * __starget_for_each_device - helper to walk all devices of a target (UNLOCKED)
614 * @starget: target whose devices we want to iterate over.
615 * @data: parameter for callback @fn()
616 * @fn: callback function that is invoked for each device
617 *
618 * This traverses over each device of @starget. It does _not_
619 * take a reference on the scsi_device, so the whole loop must be
620 * protected by shost->host_lock.
621 *
622 * Note: The only reason why drivers would want to use this is because
623 * they need to access the device list in irq context. Otherwise you
624 * really want to use starget_for_each_device instead.
625 **/
626 void __starget_for_each_device(struct scsi_target *starget, void *data,
627 void (*fn)(struct scsi_device *, void *))
628 {
629 struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
630 struct scsi_device *sdev;
631
632 __shost_for_each_device(sdev, shost) {
633 if ((sdev->channel == starget->channel) &&
634 (sdev->id == starget->id))
635 fn(sdev, data);
636 }
637 }
638 EXPORT_SYMBOL(__starget_for_each_device);
639
640 /**
641 * __scsi_device_lookup_by_target - find a device given the target (UNLOCKED)
642 * @starget: SCSI target pointer
643 * @lun: SCSI Logical Unit Number
644 *
645 * Description: Looks up the scsi_device with the specified @lun for a given
646 * @starget. The returned scsi_device does not have an additional
647 * reference. You must hold the host's host_lock over this call and
648 * any access to the returned scsi_device. A scsi_device in state
649 * SDEV_DEL is skipped.
650 *
651 * Note: The only reason why drivers should use this is because
652 * they need to access the device list in irq context. Otherwise you
653 * really want to use scsi_device_lookup_by_target instead.
654 **/
655 struct scsi_device *__scsi_device_lookup_by_target(struct scsi_target *starget,
656 u64 lun)
657 {
658 struct scsi_device *sdev;
659
660 list_for_each_entry(sdev, &starget->devices, same_target_siblings) {
661 if (sdev->sdev_state == SDEV_DEL)
662 continue;
663 if (sdev->lun ==lun)
664 return sdev;
665 }
666
667 return NULL;
668 }
669 EXPORT_SYMBOL(__scsi_device_lookup_by_target);
670
671 /**
672 * scsi_device_lookup_by_target - find a device given the target
673 * @starget: SCSI target pointer
674 * @lun: SCSI Logical Unit Number
675 *
676 * Description: Looks up the scsi_device with the specified @lun for a given
677 * @starget. The returned scsi_device has an additional reference that
678 * needs to be released with scsi_device_put once you're done with it.
679 **/
680 struct scsi_device *scsi_device_lookup_by_target(struct scsi_target *starget,
681 u64 lun)
682 {
683 struct scsi_device *sdev;
684 struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
685 unsigned long flags;
686
687 spin_lock_irqsave(shost->host_lock, flags);
688 sdev = __scsi_device_lookup_by_target(starget, lun);
689 if (sdev && scsi_device_get(sdev))
690 sdev = NULL;
691 spin_unlock_irqrestore(shost->host_lock, flags);
692
693 return sdev;
694 }
695 EXPORT_SYMBOL(scsi_device_lookup_by_target);
696
697 /**
698 * __scsi_device_lookup - find a device given the host (UNLOCKED)
699 * @shost: SCSI host pointer
700 * @channel: SCSI channel (zero if only one channel)
701 * @id: SCSI target number (physical unit number)
702 * @lun: SCSI Logical Unit Number
703 *
704 * Description: Looks up the scsi_device with the specified @channel, @id, @lun
705 * for a given host. The returned scsi_device does not have an additional
706 * reference. You must hold the host's host_lock over this call and any access
707 * to the returned scsi_device.
708 *
709 * Note: The only reason why drivers would want to use this is because
710 * they need to access the device list in irq context. Otherwise you
711 * really want to use scsi_device_lookup instead.
712 **/
713 struct scsi_device *__scsi_device_lookup(struct Scsi_Host *shost,
714 uint channel, uint id, u64 lun)
715 {
716 struct scsi_device *sdev;
717
718 list_for_each_entry(sdev, &shost->__devices, siblings) {
719 if (sdev->sdev_state == SDEV_DEL)
720 continue;
721 if (sdev->channel == channel && sdev->id == id &&
722 sdev->lun ==lun)
723 return sdev;
724 }
725
726 return NULL;
727 }
728 EXPORT_SYMBOL(__scsi_device_lookup);
729
730 /**
731 * scsi_device_lookup - find a device given the host
732 * @shost: SCSI host pointer
733 * @channel: SCSI channel (zero if only one channel)
734 * @id: SCSI target number (physical unit number)
735 * @lun: SCSI Logical Unit Number
736 *
737 * Description: Looks up the scsi_device with the specified @channel, @id, @lun
738 * for a given host. The returned scsi_device has an additional reference that
739 * needs to be released with scsi_device_put once you're done with it.
740 **/
741 struct scsi_device *scsi_device_lookup(struct Scsi_Host *shost,
742 uint channel, uint id, u64 lun)
743 {
744 struct scsi_device *sdev;
745 unsigned long flags;
746
747 spin_lock_irqsave(shost->host_lock, flags);
748 sdev = __scsi_device_lookup(shost, channel, id, lun);
749 if (sdev && scsi_device_get(sdev))
750 sdev = NULL;
751 spin_unlock_irqrestore(shost->host_lock, flags);
752
753 return sdev;
754 }
755 EXPORT_SYMBOL(scsi_device_lookup);
756
757 MODULE_DESCRIPTION("SCSI core");
758 MODULE_LICENSE("GPL");
759
760 module_param(scsi_logging_level, int, S_IRUGO|S_IWUSR);
761 MODULE_PARM_DESC(scsi_logging_level, "a bit mask of logging levels");
762
763 /* This should go away in the future, it doesn't do anything anymore */
764 bool scsi_use_blk_mq = true;
765 module_param_named(use_blk_mq, scsi_use_blk_mq, bool, S_IWUSR | S_IRUGO);
766
767 static int __init init_scsi(void)
768 {
769 int error;
770
771 error = scsi_init_queue();
772 if (error)
773 return error;
774 error = scsi_init_procfs();
775 if (error)
776 goto cleanup_queue;
777 error = scsi_init_devinfo();
778 if (error)
779 goto cleanup_procfs;
780 error = scsi_init_hosts();
781 if (error)
782 goto cleanup_devlist;
783 error = scsi_init_sysctl();
784 if (error)
785 goto cleanup_hosts;
786 error = scsi_sysfs_register();
787 if (error)
788 goto cleanup_sysctl;
789
790 scsi_netlink_init();
791
792 printk(KERN_NOTICE "SCSI subsystem initialized\n");
793 return 0;
794
795 cleanup_sysctl:
796 scsi_exit_sysctl();
797 cleanup_hosts:
798 scsi_exit_hosts();
799 cleanup_devlist:
800 scsi_exit_devinfo();
801 cleanup_procfs:
802 scsi_exit_procfs();
803 cleanup_queue:
804 scsi_exit_queue();
805 printk(KERN_ERR "SCSI subsystem failed to initialize, error = %d\n",
806 -error);
807 return error;
808 }
809
810 static void __exit exit_scsi(void)
811 {
812 scsi_netlink_exit();
813 scsi_sysfs_unregister();
814 scsi_exit_sysctl();
815 scsi_exit_hosts();
816 scsi_exit_devinfo();
817 scsi_exit_procfs();
818 scsi_exit_queue();
819 }
820
821 subsys_initcall(init_scsi);
822 module_exit(exit_scsi);