1 // SPDX-License-Identifier: GPL-2.0-only
3 * scsi.c Copyright (C) 1992 Drew Eckhardt
4 * Copyright (C) 1993, 1994, 1995, 1999 Eric Youngdale
5 * Copyright (C) 2002, 2003 Christoph Hellwig
7 * generic mid-level SCSI driver
8 * Initial versions: Drew Eckhardt
9 * Subsequent revisions: Eric Youngdale
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>
18 * Modified by Eric Youngdale eric@andante.org or ericy@gnu.ai.mit.edu to
19 * add scatter-gather, multiple outstanding request, and other
22 * Native multichannel, wide scsi, /proc/scsi and hot plugging
23 * support added by Michael Neuffer <mike@i-connect.net>
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>
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>
34 * Converted cli() code to spinlocks, Ingo Molnar
36 * Jiffies wrap fixes (host->resetting), 3 Dec 1998 Andrea Arcangeli
38 * out_of_space hacks, D. Gilbert (dpg) 990608
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 <asm/unaligned.h>
60 #include <scsi/scsi.h>
61 #include <scsi/scsi_cmnd.h>
62 #include <scsi/scsi_dbg.h>
63 #include <scsi/scsi_device.h>
64 #include <scsi/scsi_driver.h>
65 #include <scsi/scsi_eh.h>
66 #include <scsi/scsi_host.h>
67 #include <scsi/scsi_tcq.h>
69 #include "scsi_priv.h"
70 #include "scsi_logging.h"
72 #define CREATE_TRACE_POINTS
73 #include <trace/events/scsi.h>
76 * Definitions and constants.
80 * Note - the initial logging level can be set here to log events at boot time.
81 * After the system is up, you may enable logging via the /proc interface.
83 unsigned int scsi_logging_level;
84 #if defined(CONFIG_SCSI_LOGGING)
85 EXPORT_SYMBOL(scsi_logging_level);
88 #ifdef CONFIG_SCSI_LOGGING
89 void scsi_log_send(struct scsi_cmnd *cmd)
94 * If ML QUEUE log level is greater than or equal to:
96 * 1: nothing (match completion)
98 * 2: log opcode + command of all commands + cmd address
104 if (unlikely(scsi_logging_level)) {
105 level = SCSI_LOG_LEVEL(SCSI_LOG_MLQUEUE_SHIFT,
106 SCSI_LOG_MLQUEUE_BITS);
108 scmd_printk(KERN_INFO, cmd,
109 "Send: scmd 0x%p\n", cmd);
110 scsi_print_command(cmd);
115 void scsi_log_completion(struct scsi_cmnd *cmd, int disposition)
120 * If ML COMPLETE log level is greater than or equal to:
122 * 1: log disposition, result, opcode + command, and conditionally
123 * sense data for failures or non SUCCESS dispositions.
125 * 2: same as 1 but for all command completions.
129 * 4: same as 3 plus dump extra junk
131 if (unlikely(scsi_logging_level)) {
132 level = SCSI_LOG_LEVEL(SCSI_LOG_MLCOMPLETE_SHIFT,
133 SCSI_LOG_MLCOMPLETE_BITS);
134 if (((level > 0) && (cmd->result || disposition != SUCCESS)) ||
136 scsi_print_result(cmd, "Done", disposition);
137 scsi_print_command(cmd);
138 if (scsi_status_is_check_condition(cmd->result))
139 scsi_print_sense(cmd);
141 scmd_printk(KERN_INFO, cmd,
142 "scsi host busy %d failed %d\n",
143 scsi_host_busy(cmd->device->host),
144 cmd->device->host->host_failed);
151 * scsi_finish_command - cleanup and pass command back to upper layer
154 * Description: Pass command off to upper layer for finishing of I/O
155 * request, waking processes that are waiting on results,
158 void scsi_finish_command(struct scsi_cmnd *cmd)
160 struct scsi_device *sdev = cmd->device;
161 struct scsi_target *starget = scsi_target(sdev);
162 struct Scsi_Host *shost = sdev->host;
163 struct scsi_driver *drv;
164 unsigned int good_bytes;
166 scsi_device_unbusy(sdev, cmd);
169 * Clear the flags that say that the device/target/host is no longer
170 * capable of accepting new commands.
172 if (atomic_read(&shost->host_blocked))
173 atomic_set(&shost->host_blocked, 0);
174 if (atomic_read(&starget->target_blocked))
175 atomic_set(&starget->target_blocked, 0);
176 if (atomic_read(&sdev->device_blocked))
177 atomic_set(&sdev->device_blocked, 0);
179 SCSI_LOG_MLCOMPLETE(4, sdev_printk(KERN_INFO, sdev,
180 "Notifying upper driver of completion "
181 "(result %x)\n", cmd->result));
183 good_bytes = scsi_bufflen(cmd);
184 if (!blk_rq_is_passthrough(scsi_cmd_to_rq(cmd))) {
185 int old_good_bytes = good_bytes;
186 drv = scsi_cmd_to_driver(cmd);
188 good_bytes = drv->done(cmd);
190 * USB may not give sense identifying bad sector and
191 * simply return a residue instead, so subtract off the
192 * residue if drv->done() error processing indicates no
193 * change to the completion length.
195 if (good_bytes == old_good_bytes)
196 good_bytes -= scsi_get_resid(cmd);
198 scsi_io_completion(cmd, good_bytes);
203 * 4096 is big enough for saturating fast SCSI LUNs.
205 int scsi_device_max_queue_depth(struct scsi_device *sdev)
207 return min_t(int, sdev->host->can_queue, 4096);
211 * scsi_change_queue_depth - change a device's queue depth
212 * @sdev: SCSI Device in question
213 * @depth: number of commands allowed to be queued to the driver
215 * Sets the device queue depth and returns the new value.
217 int scsi_change_queue_depth(struct scsi_device *sdev, int depth)
219 depth = min_t(int, depth, scsi_device_max_queue_depth(sdev));
222 sdev->queue_depth = depth;
226 if (sdev->request_queue)
227 blk_set_queue_depth(sdev->request_queue, depth);
229 sbitmap_resize(&sdev->budget_map, sdev->queue_depth);
231 return sdev->queue_depth;
233 EXPORT_SYMBOL(scsi_change_queue_depth);
236 * scsi_track_queue_full - track QUEUE_FULL events to adjust queue depth
237 * @sdev: SCSI Device in question
238 * @depth: Current number of outstanding SCSI commands on this device,
239 * not counting the one returned as QUEUE_FULL.
241 * Description: This function will track successive QUEUE_FULL events on a
242 * specific SCSI device to determine if and when there is a
243 * need to adjust the queue depth on the device.
245 * Returns: 0 - No change needed, >0 - Adjust queue depth to this new depth,
246 * -1 - Drop back to untagged operation using host->cmd_per_lun
247 * as the untagged command depth
249 * Lock Status: None held on entry
251 * Notes: Low level drivers may call this at any time and we will do
252 * "The Right Thing." We are interrupt context safe.
254 int scsi_track_queue_full(struct scsi_device *sdev, int depth)
258 * Don't let QUEUE_FULLs on the same
259 * jiffies count, they could all be from
262 if ((jiffies >> 4) == (sdev->last_queue_full_time >> 4))
265 sdev->last_queue_full_time = jiffies;
266 if (sdev->last_queue_full_depth != depth) {
267 sdev->last_queue_full_count = 1;
268 sdev->last_queue_full_depth = depth;
270 sdev->last_queue_full_count++;
273 if (sdev->last_queue_full_count <= 10)
276 return scsi_change_queue_depth(sdev, depth);
278 EXPORT_SYMBOL(scsi_track_queue_full);
281 * scsi_vpd_inquiry - Request a device provide us with a VPD page
282 * @sdev: The device to ask
283 * @buffer: Where to put the result
284 * @page: Which Vital Product Data to return
285 * @len: The length of the buffer
287 * This is an internal helper function. You probably want to use
288 * scsi_get_vpd_page instead.
290 * Returns size of the vpd page on success or a negative error number.
292 static int scsi_vpd_inquiry(struct scsi_device *sdev, unsigned char *buffer,
293 u8 page, unsigned len)
296 unsigned char cmd[16];
302 cmd[1] = 1; /* EVPD */
306 cmd[5] = 0; /* Control byte */
309 * I'm not convinced we need to try quite this hard to get VPD, but
310 * all the existing users tried this hard.
312 result = scsi_execute_cmd(sdev, cmd, REQ_OP_DRV_IN, buffer, len,
318 * Sanity check that we got the page back that we asked for and that
319 * the page size is not 0.
321 if (buffer[1] != page)
324 result = get_unaligned_be16(&buffer[2]);
331 static int scsi_get_vpd_size(struct scsi_device *sdev, u8 page)
333 unsigned char vpd_header[SCSI_VPD_HEADER_SIZE] __aligned(4);
336 if (sdev->no_vpd_size)
337 return SCSI_DEFAULT_VPD_LEN;
340 * Fetch the VPD page header to find out how big the page
341 * is. This is done to prevent problems on legacy devices
342 * which can not handle allocation lengths as large as
343 * potentially requested by the caller.
345 result = scsi_vpd_inquiry(sdev, vpd_header, page, sizeof(vpd_header));
349 if (result < SCSI_VPD_HEADER_SIZE) {
350 dev_warn_once(&sdev->sdev_gendev,
351 "%s: short VPD page 0x%02x length: %d bytes\n",
352 __func__, page, result);
360 * scsi_get_vpd_page - Get Vital Product Data from a SCSI device
361 * @sdev: The device to ask
362 * @page: Which Vital Product Data to return
363 * @buf: where to store the VPD
364 * @buf_len: number of bytes in the VPD buffer area
366 * SCSI devices may optionally supply Vital Product Data. Each 'page'
367 * of VPD is defined in the appropriate SCSI document (eg SPC, SBC).
368 * If the device supports this VPD page, this routine fills @buf
369 * with the data from that page and return 0. If the VPD page is not
370 * supported or its content cannot be retrieved, -EINVAL is returned.
372 int scsi_get_vpd_page(struct scsi_device *sdev, u8 page, unsigned char *buf,
377 if (!scsi_device_supports_vpd(sdev))
380 vpd_len = scsi_get_vpd_size(sdev, page);
384 vpd_len = min(vpd_len, buf_len);
387 * Fetch the actual page. Since the appropriate size was reported
388 * by the device it is now safe to ask for something bigger.
390 memset(buf, 0, buf_len);
391 result = scsi_vpd_inquiry(sdev, buf, page, vpd_len);
394 else if (result > vpd_len)
395 dev_warn_once(&sdev->sdev_gendev,
396 "%s: VPD page 0x%02x result %d > %d bytes\n",
397 __func__, page, result, vpd_len);
401 EXPORT_SYMBOL_GPL(scsi_get_vpd_page);
404 * scsi_get_vpd_buf - Get Vital Product Data from a SCSI device
405 * @sdev: The device to ask
406 * @page: Which Vital Product Data to return
408 * Returns %NULL upon failure.
410 static struct scsi_vpd *scsi_get_vpd_buf(struct scsi_device *sdev, u8 page)
412 struct scsi_vpd *vpd_buf;
415 vpd_len = scsi_get_vpd_size(sdev, page);
421 * Fetch the actual page. Since the appropriate size was reported
422 * by the device it is now safe to ask for something bigger.
424 vpd_buf = kmalloc(sizeof(*vpd_buf) + vpd_len, GFP_KERNEL);
428 result = scsi_vpd_inquiry(sdev, vpd_buf->data, page, vpd_len);
433 if (result > vpd_len) {
434 dev_warn_once(&sdev->sdev_gendev,
435 "%s: VPD page 0x%02x result %d > %d bytes\n",
436 __func__, page, result, vpd_len);
442 vpd_buf->len = result;
447 static void scsi_update_vpd_page(struct scsi_device *sdev, u8 page,
448 struct scsi_vpd __rcu **sdev_vpd_buf)
450 struct scsi_vpd *vpd_buf;
452 vpd_buf = scsi_get_vpd_buf(sdev, page);
456 mutex_lock(&sdev->inquiry_mutex);
457 vpd_buf = rcu_replace_pointer(*sdev_vpd_buf, vpd_buf,
458 lockdep_is_held(&sdev->inquiry_mutex));
459 mutex_unlock(&sdev->inquiry_mutex);
462 kfree_rcu(vpd_buf, rcu);
466 * scsi_attach_vpd - Attach Vital Product Data to a SCSI device structure
467 * @sdev: The device to ask
469 * Attach the 'Device Identification' VPD page (0x83) and the
470 * 'Unit Serial Number' VPD page (0x80) to a SCSI device
471 * structure. This information can be used to identify the device
474 void scsi_attach_vpd(struct scsi_device *sdev)
477 struct scsi_vpd *vpd_buf;
479 if (!scsi_device_supports_vpd(sdev))
482 /* Ask for all the pages supported by this device */
483 vpd_buf = scsi_get_vpd_buf(sdev, 0);
487 for (i = 4; i < vpd_buf->len; i++) {
488 if (vpd_buf->data[i] == 0x0)
489 scsi_update_vpd_page(sdev, 0x0, &sdev->vpd_pg0);
490 if (vpd_buf->data[i] == 0x80)
491 scsi_update_vpd_page(sdev, 0x80, &sdev->vpd_pg80);
492 if (vpd_buf->data[i] == 0x83)
493 scsi_update_vpd_page(sdev, 0x83, &sdev->vpd_pg83);
494 if (vpd_buf->data[i] == 0x89)
495 scsi_update_vpd_page(sdev, 0x89, &sdev->vpd_pg89);
496 if (vpd_buf->data[i] == 0xb0)
497 scsi_update_vpd_page(sdev, 0xb0, &sdev->vpd_pgb0);
498 if (vpd_buf->data[i] == 0xb1)
499 scsi_update_vpd_page(sdev, 0xb1, &sdev->vpd_pgb1);
500 if (vpd_buf->data[i] == 0xb2)
501 scsi_update_vpd_page(sdev, 0xb2, &sdev->vpd_pgb2);
507 * scsi_report_opcode - Find out if a given command is supported
508 * @sdev: scsi device to query
509 * @buffer: scratch buffer (must be at least 20 bytes long)
510 * @len: length of buffer
511 * @opcode: opcode for the command to look up
512 * @sa: service action for the command to look up
514 * Uses the REPORT SUPPORTED OPERATION CODES to check support for the
515 * command identified with @opcode and @sa. If the command does not
516 * have a service action, @sa must be 0. Returns -EINVAL if RSOC fails,
517 * 0 if the command is not supported and 1 if the device claims to
518 * support the command.
520 int scsi_report_opcode(struct scsi_device *sdev, unsigned char *buffer,
521 unsigned int len, unsigned char opcode,
524 unsigned char cmd[16];
525 struct scsi_sense_hdr sshdr;
526 int result, request_len;
527 const struct scsi_exec_args exec_args = {
531 if (sdev->no_report_opcodes || sdev->scsi_level < SCSI_SPC_3)
534 /* RSOC header + size of command we are asking about */
535 request_len = 4 + COMMAND_SIZE(opcode);
536 if (request_len > len) {
537 dev_warn_once(&sdev->sdev_gendev,
538 "%s: len %u bytes, opcode 0x%02x needs %u\n",
539 __func__, len, opcode, request_len);
544 cmd[0] = MAINTENANCE_IN;
545 cmd[1] = MI_REPORT_SUPPORTED_OPERATION_CODES;
547 cmd[2] = 1; /* One command format */
550 cmd[2] = 3; /* One command format with service action */
552 put_unaligned_be16(sa, &cmd[4]);
554 put_unaligned_be32(request_len, &cmd[6]);
555 memset(buffer, 0, len);
557 result = scsi_execute_cmd(sdev, cmd, REQ_OP_DRV_IN, buffer,
558 request_len, 30 * HZ, 3, &exec_args);
561 if (result && scsi_sense_valid(&sshdr) &&
562 sshdr.sense_key == ILLEGAL_REQUEST &&
563 (sshdr.asc == 0x20 || sshdr.asc == 0x24) && sshdr.ascq == 0x00)
566 if ((buffer[1] & 3) == 3) /* Command supported */
571 EXPORT_SYMBOL(scsi_report_opcode);
573 #define SCSI_CDL_CHECK_BUF_LEN 64
575 static bool scsi_cdl_check_cmd(struct scsi_device *sdev, u8 opcode, u16 sa,
581 /* Check operation code */
582 ret = scsi_report_opcode(sdev, buf, SCSI_CDL_CHECK_BUF_LEN, opcode, sa);
586 if ((buf[1] & 0x03) != 0x03)
589 /* See SPC-6, one command format of REPORT SUPPORTED OPERATION CODES */
590 cdlp = (buf[1] & 0x18) >> 3;
617 * scsi_cdl_check - Check if a SCSI device supports Command Duration Limits
618 * @sdev: The device to check
620 void scsi_cdl_check(struct scsi_device *sdev)
625 buf = kmalloc(SCSI_CDL_CHECK_BUF_LEN, GFP_KERNEL);
627 sdev->cdl_supported = 0;
631 /* Check support for READ_16, WRITE_16, READ_32 and WRITE_32 commands */
633 scsi_cdl_check_cmd(sdev, READ_16, 0, buf) ||
634 scsi_cdl_check_cmd(sdev, WRITE_16, 0, buf) ||
635 scsi_cdl_check_cmd(sdev, VARIABLE_LENGTH_CMD, READ_32, buf) ||
636 scsi_cdl_check_cmd(sdev, VARIABLE_LENGTH_CMD, WRITE_32, buf);
639 * We have CDL support: force the use of READ16/WRITE16.
640 * READ32 and WRITE32 will be used for devices that support
641 * the T10_PI_TYPE2_PROTECTION protection type.
643 sdev->use_16_for_rw = 1;
644 sdev->use_10_for_rw = 0;
646 sdev->cdl_supported = 1;
648 sdev->cdl_supported = 0;
655 * scsi_device_get - get an additional reference to a scsi_device
656 * @sdev: device to get a reference to
658 * Description: Gets a reference to the scsi_device and increments the use count
659 * of the underlying LLDD module. You must hold host_lock of the
660 * parent Scsi_Host or already have a reference when calling this.
662 * This will fail if a device is deleted or cancelled, or when the LLD module
663 * is in the process of being unloaded.
665 int scsi_device_get(struct scsi_device *sdev)
667 if (sdev->sdev_state == SDEV_DEL || sdev->sdev_state == SDEV_CANCEL)
669 if (!try_module_get(sdev->host->hostt->module))
671 if (!get_device(&sdev->sdev_gendev))
672 goto fail_put_module;
676 module_put(sdev->host->hostt->module);
680 EXPORT_SYMBOL(scsi_device_get);
683 * scsi_device_put - release a reference to a scsi_device
684 * @sdev: device to release a reference on.
686 * Description: Release a reference to the scsi_device and decrements the use
687 * count of the underlying LLDD module. The device is freed once the last
690 void scsi_device_put(struct scsi_device *sdev)
692 struct module *mod = sdev->host->hostt->module;
694 put_device(&sdev->sdev_gendev);
697 EXPORT_SYMBOL(scsi_device_put);
699 /* helper for shost_for_each_device, see that for documentation */
700 struct scsi_device *__scsi_iterate_devices(struct Scsi_Host *shost,
701 struct scsi_device *prev)
703 struct list_head *list = (prev ? &prev->siblings : &shost->__devices);
704 struct scsi_device *next = NULL;
707 spin_lock_irqsave(shost->host_lock, flags);
708 while (list->next != &shost->__devices) {
709 next = list_entry(list->next, struct scsi_device, siblings);
710 /* skip devices that we can't get a reference to */
711 if (!scsi_device_get(next))
716 spin_unlock_irqrestore(shost->host_lock, flags);
719 scsi_device_put(prev);
722 EXPORT_SYMBOL(__scsi_iterate_devices);
725 * starget_for_each_device - helper to walk all devices of a target
726 * @starget: target whose devices we want to iterate over.
727 * @data: Opaque passed to each function call.
728 * @fn: Function to call on each device
730 * This traverses over each device of @starget. The devices have
731 * a reference that must be released by scsi_host_put when breaking
734 void starget_for_each_device(struct scsi_target *starget, void *data,
735 void (*fn)(struct scsi_device *, void *))
737 struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
738 struct scsi_device *sdev;
740 shost_for_each_device(sdev, shost) {
741 if ((sdev->channel == starget->channel) &&
742 (sdev->id == starget->id))
746 EXPORT_SYMBOL(starget_for_each_device);
749 * __starget_for_each_device - helper to walk all devices of a target (UNLOCKED)
750 * @starget: target whose devices we want to iterate over.
751 * @data: parameter for callback @fn()
752 * @fn: callback function that is invoked for each device
754 * This traverses over each device of @starget. It does _not_
755 * take a reference on the scsi_device, so the whole loop must be
756 * protected by shost->host_lock.
758 * Note: The only reason why drivers would want to use this is because
759 * they need to access the device list in irq context. Otherwise you
760 * really want to use starget_for_each_device instead.
762 void __starget_for_each_device(struct scsi_target *starget, void *data,
763 void (*fn)(struct scsi_device *, void *))
765 struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
766 struct scsi_device *sdev;
768 __shost_for_each_device(sdev, shost) {
769 if ((sdev->channel == starget->channel) &&
770 (sdev->id == starget->id))
774 EXPORT_SYMBOL(__starget_for_each_device);
777 * __scsi_device_lookup_by_target - find a device given the target (UNLOCKED)
778 * @starget: SCSI target pointer
779 * @lun: SCSI Logical Unit Number
781 * Description: Looks up the scsi_device with the specified @lun for a given
782 * @starget. The returned scsi_device does not have an additional
783 * reference. You must hold the host's host_lock over this call and
784 * any access to the returned scsi_device. A scsi_device in state
785 * SDEV_DEL is skipped.
787 * Note: The only reason why drivers should use this is because
788 * they need to access the device list in irq context. Otherwise you
789 * really want to use scsi_device_lookup_by_target instead.
791 struct scsi_device *__scsi_device_lookup_by_target(struct scsi_target *starget,
794 struct scsi_device *sdev;
796 list_for_each_entry(sdev, &starget->devices, same_target_siblings) {
797 if (sdev->sdev_state == SDEV_DEL)
805 EXPORT_SYMBOL(__scsi_device_lookup_by_target);
808 * scsi_device_lookup_by_target - find a device given the target
809 * @starget: SCSI target pointer
810 * @lun: SCSI Logical Unit Number
812 * Description: Looks up the scsi_device with the specified @lun for a given
813 * @starget. The returned scsi_device has an additional reference that
814 * needs to be released with scsi_device_put once you're done with it.
816 struct scsi_device *scsi_device_lookup_by_target(struct scsi_target *starget,
819 struct scsi_device *sdev;
820 struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
823 spin_lock_irqsave(shost->host_lock, flags);
824 sdev = __scsi_device_lookup_by_target(starget, lun);
825 if (sdev && scsi_device_get(sdev))
827 spin_unlock_irqrestore(shost->host_lock, flags);
831 EXPORT_SYMBOL(scsi_device_lookup_by_target);
834 * __scsi_device_lookup - find a device given the host (UNLOCKED)
835 * @shost: SCSI host pointer
836 * @channel: SCSI channel (zero if only one channel)
837 * @id: SCSI target number (physical unit number)
838 * @lun: SCSI Logical Unit Number
840 * Description: Looks up the scsi_device with the specified @channel, @id, @lun
841 * for a given host. The returned scsi_device does not have an additional
842 * reference. You must hold the host's host_lock over this call and any access
843 * to the returned scsi_device.
845 * Note: The only reason why drivers would want to use this is because
846 * they need to access the device list in irq context. Otherwise you
847 * really want to use scsi_device_lookup instead.
849 struct scsi_device *__scsi_device_lookup(struct Scsi_Host *shost,
850 uint channel, uint id, u64 lun)
852 struct scsi_device *sdev;
854 list_for_each_entry(sdev, &shost->__devices, siblings) {
855 if (sdev->sdev_state == SDEV_DEL)
857 if (sdev->channel == channel && sdev->id == id &&
864 EXPORT_SYMBOL(__scsi_device_lookup);
867 * scsi_device_lookup - find a device given the host
868 * @shost: SCSI host pointer
869 * @channel: SCSI channel (zero if only one channel)
870 * @id: SCSI target number (physical unit number)
871 * @lun: SCSI Logical Unit Number
873 * Description: Looks up the scsi_device with the specified @channel, @id, @lun
874 * for a given host. The returned scsi_device has an additional reference that
875 * needs to be released with scsi_device_put once you're done with it.
877 struct scsi_device *scsi_device_lookup(struct Scsi_Host *shost,
878 uint channel, uint id, u64 lun)
880 struct scsi_device *sdev;
883 spin_lock_irqsave(shost->host_lock, flags);
884 sdev = __scsi_device_lookup(shost, channel, id, lun);
885 if (sdev && scsi_device_get(sdev))
887 spin_unlock_irqrestore(shost->host_lock, flags);
891 EXPORT_SYMBOL(scsi_device_lookup);
893 MODULE_DESCRIPTION("SCSI core");
894 MODULE_LICENSE("GPL");
896 module_param(scsi_logging_level, int, S_IRUGO|S_IWUSR);
897 MODULE_PARM_DESC(scsi_logging_level, "a bit mask of logging levels");
899 static int __init init_scsi(void)
903 error = scsi_init_procfs();
906 error = scsi_init_devinfo();
909 error = scsi_init_hosts();
911 goto cleanup_devlist;
912 error = scsi_init_sysctl();
915 error = scsi_sysfs_register();
921 printk(KERN_NOTICE "SCSI subsystem initialized\n");
934 printk(KERN_ERR "SCSI subsystem failed to initialize, error = %d\n",
939 static void __exit exit_scsi(void)
942 scsi_sysfs_unregister();
950 subsys_initcall(init_scsi);
951 module_exit(exit_scsi);