2 * scsi.c Copyright (C) 1992 Drew Eckhardt
3 * Copyright (C) 1993, 1994, 1995, 1999 Eric Youngdale
4 * Copyright (C) 2002, 2003 Christoph Hellwig
6 * generic mid-level SCSI driver
7 * Initial versions: Drew Eckhardt
8 * Subsequent revisions: Eric Youngdale
12 * Bug correction thanks go to :
13 * Rik Faith <faith@cs.unc.edu>
14 * Tommy Thorn <tthorn>
15 * Thomas Wuensche <tw@fgb1.fgb.mw.tu-muenchen.de>
17 * Modified by Eric Youngdale eric@andante.org or ericy@gnu.ai.mit.edu to
18 * add scatter-gather, multiple outstanding request, and other
21 * Native multichannel, wide scsi, /proc/scsi and hot plugging
22 * support added by Michael Neuffer <mike@i-connect.net>
24 * Added request_module("scsi_hostadapter") for kerneld:
25 * (Put an "alias scsi_hostadapter your_hostadapter" in /etc/modprobe.conf)
26 * Bjorn Ekwall <bj0rn@blox.se>
29 * Major improvements to the timeout, abort, and reset processing,
30 * as well as performance modifications for large queue depths by
31 * Leonard N. Zubkoff <lnz@dandelion.com>
33 * Converted cli() code to spinlocks, Ingo Molnar
35 * Jiffies wrap fixes (host->resetting), 3 Dec 1998 Andrea Arcangeli
37 * out_of_space hacks, D. Gilbert (dpg) 990608
40 #include <linux/module.h>
41 #include <linux/moduleparam.h>
42 #include <linux/kernel.h>
43 #include <linux/timer.h>
44 #include <linux/string.h>
45 #include <linux/slab.h>
46 #include <linux/blkdev.h>
47 #include <linux/delay.h>
48 #include <linux/init.h>
49 #include <linux/completion.h>
50 #include <linux/unistd.h>
51 #include <linux/spinlock.h>
52 #include <linux/kmod.h>
53 #include <linux/interrupt.h>
54 #include <linux/notifier.h>
55 #include <linux/cpu.h>
56 #include <linux/mutex.h>
58 #include <scsi/scsi.h>
59 #include <scsi/scsi_cmnd.h>
60 #include <scsi/scsi_dbg.h>
61 #include <scsi/scsi_device.h>
62 #include <scsi/scsi_eh.h>
63 #include <scsi/scsi_host.h>
64 #include <scsi/scsi_tcq.h>
66 #include "scsi_priv.h"
67 #include "scsi_logging.h"
69 static void scsi_done(struct scsi_cmnd
*cmd
);
72 * Definitions and constants.
75 #define MIN_RESET_DELAY (2*HZ)
77 /* Do not call reset on error if we just did a reset within 15 sec. */
78 #define MIN_RESET_PERIOD (15*HZ)
81 * Macro to determine the size of SCSI command. This macro takes vendor
82 * unique commands into account. SCSI commands in groups 6 and 7 are
83 * vendor unique and we will depend upon the command length being
84 * supplied correctly in cmd_len.
86 #define CDB_SIZE(cmd) (((((cmd)->cmnd[0] >> 5) & 7) < 6) ? \
87 COMMAND_SIZE((cmd)->cmnd[0]) : (cmd)->cmd_len)
90 * Note - the initial logging level can be set here to log events at boot time.
91 * After the system is up, you may enable logging via the /proc interface.
93 unsigned int scsi_logging_level
;
94 #if defined(CONFIG_SCSI_LOGGING)
95 EXPORT_SYMBOL(scsi_logging_level
);
98 /* NB: These are exposed through /proc/scsi/scsi and form part of the ABI.
99 * You may not alter any existing entry (although adding new ones is
100 * encouraged once assigned by ANSI/INCITS T10
102 static const char *const scsi_device_types
[] = {
124 const char * scsi_device_type(unsigned type
)
127 return "Well-known LUN ";
130 if (type
>= ARRAY_SIZE(scsi_device_types
))
132 return scsi_device_types
[type
];
135 EXPORT_SYMBOL(scsi_device_type
);
137 struct scsi_host_cmd_pool
{
138 struct kmem_cache
*slab
;
141 unsigned int slab_flags
;
145 static struct scsi_host_cmd_pool scsi_cmd_pool
= {
146 .name
= "scsi_cmd_cache",
147 .slab_flags
= SLAB_HWCACHE_ALIGN
,
150 static struct scsi_host_cmd_pool scsi_cmd_dma_pool
= {
151 .name
= "scsi_cmd_cache(DMA)",
152 .slab_flags
= SLAB_HWCACHE_ALIGN
|SLAB_CACHE_DMA
,
153 .gfp_mask
= __GFP_DMA
,
156 static DEFINE_MUTEX(host_cmd_pool_mutex
);
158 struct scsi_cmnd
*__scsi_get_command(struct Scsi_Host
*shost
, gfp_t gfp_mask
)
160 struct scsi_cmnd
*cmd
;
162 cmd
= kmem_cache_alloc(shost
->cmd_pool
->slab
,
163 gfp_mask
| shost
->cmd_pool
->gfp_mask
);
165 if (unlikely(!cmd
)) {
168 spin_lock_irqsave(&shost
->free_list_lock
, flags
);
169 if (likely(!list_empty(&shost
->free_list
))) {
170 cmd
= list_entry(shost
->free_list
.next
,
171 struct scsi_cmnd
, list
);
172 list_del_init(&cmd
->list
);
174 spin_unlock_irqrestore(&shost
->free_list_lock
, flags
);
179 EXPORT_SYMBOL_GPL(__scsi_get_command
);
182 * Function: scsi_get_command()
184 * Purpose: Allocate and setup a scsi command block
186 * Arguments: dev - parent scsi device
187 * gfp_mask- allocator flags
189 * Returns: The allocated scsi command structure.
191 struct scsi_cmnd
*scsi_get_command(struct scsi_device
*dev
, gfp_t gfp_mask
)
193 struct scsi_cmnd
*cmd
;
195 /* Bail if we can't get a reference to the device */
196 if (!get_device(&dev
->sdev_gendev
))
199 cmd
= __scsi_get_command(dev
->host
, gfp_mask
);
201 if (likely(cmd
!= NULL
)) {
204 memset(cmd
, 0, sizeof(*cmd
));
206 init_timer(&cmd
->eh_timeout
);
207 INIT_LIST_HEAD(&cmd
->list
);
208 spin_lock_irqsave(&dev
->list_lock
, flags
);
209 list_add_tail(&cmd
->list
, &dev
->cmd_list
);
210 spin_unlock_irqrestore(&dev
->list_lock
, flags
);
211 cmd
->jiffies_at_alloc
= jiffies
;
213 put_device(&dev
->sdev_gendev
);
217 EXPORT_SYMBOL(scsi_get_command
);
219 void __scsi_put_command(struct Scsi_Host
*shost
, struct scsi_cmnd
*cmd
,
224 /* changing locks here, don't need to restore the irq state */
225 spin_lock_irqsave(&shost
->free_list_lock
, flags
);
226 if (unlikely(list_empty(&shost
->free_list
))) {
227 list_add(&cmd
->list
, &shost
->free_list
);
230 spin_unlock_irqrestore(&shost
->free_list_lock
, flags
);
232 if (likely(cmd
!= NULL
))
233 kmem_cache_free(shost
->cmd_pool
->slab
, cmd
);
237 EXPORT_SYMBOL(__scsi_put_command
);
240 * Function: scsi_put_command()
242 * Purpose: Free a scsi command block
244 * Arguments: cmd - command block to free
248 * Notes: The command must not belong to any lists.
250 void scsi_put_command(struct scsi_cmnd
*cmd
)
252 struct scsi_device
*sdev
= cmd
->device
;
255 /* serious error if the command hasn't come from a device list */
256 spin_lock_irqsave(&cmd
->device
->list_lock
, flags
);
257 BUG_ON(list_empty(&cmd
->list
));
258 list_del_init(&cmd
->list
);
259 spin_unlock_irqrestore(&cmd
->device
->list_lock
, flags
);
261 __scsi_put_command(cmd
->device
->host
, cmd
, &sdev
->sdev_gendev
);
263 EXPORT_SYMBOL(scsi_put_command
);
266 * Function: scsi_setup_command_freelist()
268 * Purpose: Setup the command freelist for a scsi host.
270 * Arguments: shost - host to allocate the freelist for.
274 int scsi_setup_command_freelist(struct Scsi_Host
*shost
)
276 struct scsi_host_cmd_pool
*pool
;
277 struct scsi_cmnd
*cmd
;
279 spin_lock_init(&shost
->free_list_lock
);
280 INIT_LIST_HEAD(&shost
->free_list
);
283 * Select a command slab for this host and create it if not
286 mutex_lock(&host_cmd_pool_mutex
);
287 pool
= (shost
->unchecked_isa_dma
? &scsi_cmd_dma_pool
: &scsi_cmd_pool
);
289 pool
->slab
= kmem_cache_create(pool
->name
,
290 sizeof(struct scsi_cmnd
), 0,
291 pool
->slab_flags
, NULL
);
297 shost
->cmd_pool
= pool
;
298 mutex_unlock(&host_cmd_pool_mutex
);
301 * Get one backup command for this host.
303 cmd
= kmem_cache_alloc(shost
->cmd_pool
->slab
,
304 GFP_KERNEL
| shost
->cmd_pool
->gfp_mask
);
307 list_add(&cmd
->list
, &shost
->free_list
);
312 kmem_cache_destroy(pool
->slab
);
315 mutex_unlock(&host_cmd_pool_mutex
);
321 * Function: scsi_destroy_command_freelist()
323 * Purpose: Release the command freelist for a scsi host.
325 * Arguments: shost - host that's freelist is going to be destroyed
327 void scsi_destroy_command_freelist(struct Scsi_Host
*shost
)
329 while (!list_empty(&shost
->free_list
)) {
330 struct scsi_cmnd
*cmd
;
332 cmd
= list_entry(shost
->free_list
.next
, struct scsi_cmnd
, list
);
333 list_del_init(&cmd
->list
);
334 kmem_cache_free(shost
->cmd_pool
->slab
, cmd
);
337 mutex_lock(&host_cmd_pool_mutex
);
338 if (!--shost
->cmd_pool
->users
)
339 kmem_cache_destroy(shost
->cmd_pool
->slab
);
340 mutex_unlock(&host_cmd_pool_mutex
);
343 #ifdef CONFIG_SCSI_LOGGING
344 void scsi_log_send(struct scsi_cmnd
*cmd
)
349 * If ML QUEUE log level is greater than or equal to:
351 * 1: nothing (match completion)
353 * 2: log opcode + command of all commands
355 * 3: same as 2 plus dump cmd address
357 * 4: same as 3 plus dump extra junk
359 if (unlikely(scsi_logging_level
)) {
360 level
= SCSI_LOG_LEVEL(SCSI_LOG_MLQUEUE_SHIFT
,
361 SCSI_LOG_MLQUEUE_BITS
);
363 scmd_printk(KERN_INFO
, cmd
, "Send: ");
365 printk("0x%p ", cmd
);
367 scsi_print_command(cmd
);
369 printk(KERN_INFO
"buffer = 0x%p, bufflen = %d,"
370 " done = 0x%p, queuecommand 0x%p\n",
371 scsi_sglist(cmd
), scsi_bufflen(cmd
),
373 cmd
->device
->host
->hostt
->queuecommand
);
380 void scsi_log_completion(struct scsi_cmnd
*cmd
, int disposition
)
385 * If ML COMPLETE log level is greater than or equal to:
387 * 1: log disposition, result, opcode + command, and conditionally
388 * sense data for failures or non SUCCESS dispositions.
390 * 2: same as 1 but for all command completions.
392 * 3: same as 2 plus dump cmd address
394 * 4: same as 3 plus dump extra junk
396 if (unlikely(scsi_logging_level
)) {
397 level
= SCSI_LOG_LEVEL(SCSI_LOG_MLCOMPLETE_SHIFT
,
398 SCSI_LOG_MLCOMPLETE_BITS
);
399 if (((level
> 0) && (cmd
->result
|| disposition
!= SUCCESS
)) ||
401 scmd_printk(KERN_INFO
, cmd
, "Done: ");
403 printk("0x%p ", cmd
);
405 * Dump truncated values, so we usually fit within
408 switch (disposition
) {
423 * If called via scsi_times_out.
430 scsi_print_result(cmd
);
431 scsi_print_command(cmd
);
432 if (status_byte(cmd
->result
) & CHECK_CONDITION
)
433 scsi_print_sense("", cmd
);
435 scmd_printk(KERN_INFO
, cmd
,
436 "scsi host busy %d failed %d\n",
437 cmd
->device
->host
->host_busy
,
438 cmd
->device
->host
->host_failed
);
445 * Assign a serial number to the request for error recovery
446 * and debugging purposes. Protected by the Host_Lock of host.
448 static inline void scsi_cmd_get_serial(struct Scsi_Host
*host
, struct scsi_cmnd
*cmd
)
450 cmd
->serial_number
= host
->cmd_serial_number
++;
451 if (cmd
->serial_number
== 0)
452 cmd
->serial_number
= host
->cmd_serial_number
++;
456 * Function: scsi_dispatch_command
458 * Purpose: Dispatch a command to the low-level driver.
460 * Arguments: cmd - command block we are dispatching.
464 int scsi_dispatch_cmd(struct scsi_cmnd
*cmd
)
466 struct Scsi_Host
*host
= cmd
->device
->host
;
467 unsigned long flags
= 0;
468 unsigned long timeout
;
471 /* check if the device is still usable */
472 if (unlikely(cmd
->device
->sdev_state
== SDEV_DEL
)) {
473 /* in SDEV_DEL we error all commands. DID_NO_CONNECT
474 * returns an immediate error upwards, and signals
475 * that the device is no longer present */
476 cmd
->result
= DID_NO_CONNECT
<< 16;
477 atomic_inc(&cmd
->device
->iorequest_cnt
);
479 /* return 0 (because the command has been processed) */
483 /* Check to see if the scsi lld put this device into state SDEV_BLOCK. */
484 if (unlikely(cmd
->device
->sdev_state
== SDEV_BLOCK
)) {
486 * in SDEV_BLOCK, the command is just put back on the device
487 * queue. The suspend state has already blocked the queue so
488 * future requests should not occur until the device
489 * transitions out of the suspend state.
491 scsi_queue_insert(cmd
, SCSI_MLQUEUE_DEVICE_BUSY
);
493 SCSI_LOG_MLQUEUE(3, printk("queuecommand : device blocked \n"));
496 * NOTE: rtn is still zero here because we don't need the
497 * queue to be plugged on return (it's already stopped)
503 * If SCSI-2 or lower, store the LUN value in cmnd.
505 if (cmd
->device
->scsi_level
<= SCSI_2
&&
506 cmd
->device
->scsi_level
!= SCSI_UNKNOWN
) {
507 cmd
->cmnd
[1] = (cmd
->cmnd
[1] & 0x1f) |
508 (cmd
->device
->lun
<< 5 & 0xe0);
512 * We will wait MIN_RESET_DELAY clock ticks after the last reset so
513 * we can avoid the drive not being ready.
515 timeout
= host
->last_reset
+ MIN_RESET_DELAY
;
517 if (host
->resetting
&& time_before(jiffies
, timeout
)) {
518 int ticks_remaining
= timeout
- jiffies
;
520 * NOTE: This may be executed from within an interrupt
521 * handler! This is bad, but for now, it'll do. The irq
522 * level of the interrupt handler has been masked out by the
523 * platform dependent interrupt handling code already, so the
524 * sti() here will not cause another call to the SCSI host's
525 * interrupt handler (assuming there is one irq-level per
528 while (--ticks_remaining
>= 0)
529 mdelay(1 + 999 / HZ
);
534 * AK: unlikely race here: for some reason the timer could
535 * expire before the serial number is set up below.
537 scsi_add_timer(cmd
, cmd
->timeout_per_command
, scsi_times_out
);
542 * We will use a queued command if possible, otherwise we will
543 * emulate the queuing and calling of completion function ourselves.
545 atomic_inc(&cmd
->device
->iorequest_cnt
);
548 * Before we queue this command, check if the command
549 * length exceeds what the host adapter can handle.
551 if (CDB_SIZE(cmd
) > cmd
->device
->host
->max_cmd_len
) {
553 printk("queuecommand : command too long.\n"));
554 cmd
->result
= (DID_ABORT
<< 16);
560 spin_lock_irqsave(host
->host_lock
, flags
);
561 scsi_cmd_get_serial(host
, cmd
);
563 if (unlikely(host
->shost_state
== SHOST_DEL
)) {
564 cmd
->result
= (DID_NO_CONNECT
<< 16);
567 rtn
= host
->hostt
->queuecommand(cmd
, scsi_done
);
569 spin_unlock_irqrestore(host
->host_lock
, flags
);
571 if (scsi_delete_timer(cmd
)) {
572 atomic_inc(&cmd
->device
->iodone_cnt
);
573 scsi_queue_insert(cmd
,
574 (rtn
== SCSI_MLQUEUE_DEVICE_BUSY
) ?
575 rtn
: SCSI_MLQUEUE_HOST_BUSY
);
578 printk("queuecommand : request rejected\n"));
582 SCSI_LOG_MLQUEUE(3, printk("leaving scsi_dispatch_cmnd()\n"));
587 * scsi_req_abort_cmd -- Request command recovery for the specified command
588 * cmd: pointer to the SCSI command of interest
590 * This function requests that SCSI Core start recovery for the
591 * command by deleting the timer and adding the command to the eh
592 * queue. It can be called by either LLDDs or SCSI Core. LLDDs who
593 * implement their own error recovery MAY ignore the timeout event if
594 * they generated scsi_req_abort_cmd.
596 void scsi_req_abort_cmd(struct scsi_cmnd
*cmd
)
598 if (!scsi_delete_timer(cmd
))
602 EXPORT_SYMBOL(scsi_req_abort_cmd
);
605 * scsi_done - Enqueue the finished SCSI command into the done queue.
606 * @cmd: The SCSI Command for which a low-level device driver (LLDD) gives
607 * ownership back to SCSI Core -- i.e. the LLDD has finished with it.
609 * This function is the mid-level's (SCSI Core) interrupt routine, which
610 * regains ownership of the SCSI command (de facto) from a LLDD, and enqueues
611 * the command to the done queue for further processing.
613 * This is the producer of the done queue who enqueues at the tail.
615 * This function is interrupt context safe.
617 static void scsi_done(struct scsi_cmnd
*cmd
)
620 * We don't have to worry about this one timing out any more.
621 * If we are unable to remove the timer, then the command
622 * has already timed out. In which case, we have no choice but to
623 * let the timeout function run, as we have no idea where in fact
624 * that function could really be. It might be on another processor,
627 if (!scsi_delete_timer(cmd
))
632 /* Private entry to scsi_done() to complete a command when the timer
633 * isn't running --- used by scsi_times_out */
634 void __scsi_done(struct scsi_cmnd
*cmd
)
636 struct request
*rq
= cmd
->request
;
639 * Set the serial numbers back to zero
641 cmd
->serial_number
= 0;
643 atomic_inc(&cmd
->device
->iodone_cnt
);
645 atomic_inc(&cmd
->device
->ioerr_cnt
);
650 * The uptodate/nbytes values don't matter, as we allow partial
651 * completes and thus will check this in the softirq callback
653 rq
->completion_data
= cmd
;
654 blk_complete_request(rq
);
658 * Function: scsi_finish_command
660 * Purpose: Pass command off to upper layer for finishing of I/O
661 * request, waking processes that are waiting on results,
664 void scsi_finish_command(struct scsi_cmnd
*cmd
)
666 struct scsi_device
*sdev
= cmd
->device
;
667 struct Scsi_Host
*shost
= sdev
->host
;
669 scsi_device_unbusy(sdev
);
672 * Clear the flags which say that the device/host is no longer
673 * capable of accepting new commands. These are set in scsi_queue.c
674 * for both the queue full condition on a device, and for a
675 * host full condition on the host.
677 * XXX(hch): What about locking?
679 shost
->host_blocked
= 0;
680 sdev
->device_blocked
= 0;
683 * If we have valid sense information, then some kind of recovery
684 * must have taken place. Make a note of this.
686 if (SCSI_SENSE_VALID(cmd
))
687 cmd
->result
|= (DRIVER_SENSE
<< 24);
689 SCSI_LOG_MLCOMPLETE(4, sdev_printk(KERN_INFO
, sdev
,
690 "Notifying upper driver of completion "
691 "(result %x)\n", cmd
->result
));
695 EXPORT_SYMBOL(scsi_finish_command
);
698 * Function: scsi_adjust_queue_depth()
700 * Purpose: Allow low level drivers to tell us to change the queue depth
701 * on a specific SCSI device
703 * Arguments: sdev - SCSI Device in question
704 * tagged - Do we use tagged queueing (non-0) or do we treat
705 * this device as an untagged device (0)
706 * tags - Number of tags allowed if tagged queueing enabled,
707 * or number of commands the low level driver can
708 * queue up in non-tagged mode (as per cmd_per_lun).
712 * Lock Status: None held on entry
714 * Notes: Low level drivers may call this at any time and we will do
715 * the right thing depending on whether or not the device is
716 * currently active and whether or not it even has the
717 * command blocks built yet.
719 void scsi_adjust_queue_depth(struct scsi_device
*sdev
, int tagged
, int tags
)
724 * refuse to set tagged depth to an unworkable size
729 spin_lock_irqsave(sdev
->request_queue
->queue_lock
, flags
);
731 /* Check to see if the queue is managed by the block layer
732 * if it is, and we fail to adjust the depth, exit */
733 if (blk_queue_tagged(sdev
->request_queue
) &&
734 blk_queue_resize_tags(sdev
->request_queue
, tags
) != 0)
737 sdev
->queue_depth
= tags
;
739 case MSG_ORDERED_TAG
:
740 sdev
->ordered_tags
= 1;
741 sdev
->simple_tags
= 1;
744 sdev
->ordered_tags
= 0;
745 sdev
->simple_tags
= 1;
748 sdev_printk(KERN_WARNING
, sdev
,
749 "scsi_adjust_queue_depth, bad queue type, "
752 sdev
->ordered_tags
= sdev
->simple_tags
= 0;
753 sdev
->queue_depth
= tags
;
757 spin_unlock_irqrestore(sdev
->request_queue
->queue_lock
, flags
);
759 EXPORT_SYMBOL(scsi_adjust_queue_depth
);
762 * Function: scsi_track_queue_full()
764 * Purpose: This function will track successive QUEUE_FULL events on a
765 * specific SCSI device to determine if and when there is a
766 * need to adjust the queue depth on the device.
768 * Arguments: sdev - SCSI Device in question
769 * depth - Current number of outstanding SCSI commands on
770 * this device, not counting the one returned as
773 * Returns: 0 - No change needed
774 * >0 - Adjust queue depth to this new depth
775 * -1 - Drop back to untagged operation using host->cmd_per_lun
776 * as the untagged command depth
778 * Lock Status: None held on entry
780 * Notes: Low level drivers may call this at any time and we will do
781 * "The Right Thing." We are interrupt context safe.
783 int scsi_track_queue_full(struct scsi_device
*sdev
, int depth
)
785 if ((jiffies
>> 4) == sdev
->last_queue_full_time
)
788 sdev
->last_queue_full_time
= (jiffies
>> 4);
789 if (sdev
->last_queue_full_depth
!= depth
) {
790 sdev
->last_queue_full_count
= 1;
791 sdev
->last_queue_full_depth
= depth
;
793 sdev
->last_queue_full_count
++;
796 if (sdev
->last_queue_full_count
<= 10)
798 if (sdev
->last_queue_full_depth
< 8) {
799 /* Drop back to untagged */
800 scsi_adjust_queue_depth(sdev
, 0, sdev
->host
->cmd_per_lun
);
804 if (sdev
->ordered_tags
)
805 scsi_adjust_queue_depth(sdev
, MSG_ORDERED_TAG
, depth
);
807 scsi_adjust_queue_depth(sdev
, MSG_SIMPLE_TAG
, depth
);
810 EXPORT_SYMBOL(scsi_track_queue_full
);
813 * scsi_device_get - get an addition reference to a scsi_device
814 * @sdev: device to get a reference to
816 * Gets a reference to the scsi_device and increments the use count
817 * of the underlying LLDD module. You must hold host_lock of the
818 * parent Scsi_Host or already have a reference when calling this.
820 int scsi_device_get(struct scsi_device
*sdev
)
822 if (sdev
->sdev_state
== SDEV_DEL
)
824 if (!get_device(&sdev
->sdev_gendev
))
826 /* We can fail this if we're doing SCSI operations
827 * from module exit (like cache flush) */
828 try_module_get(sdev
->host
->hostt
->module
);
832 EXPORT_SYMBOL(scsi_device_get
);
835 * scsi_device_put - release a reference to a scsi_device
836 * @sdev: device to release a reference on.
838 * Release a reference to the scsi_device and decrements the use count
839 * of the underlying LLDD module. The device is freed once the last
842 void scsi_device_put(struct scsi_device
*sdev
)
844 #ifdef CONFIG_MODULE_UNLOAD
845 struct module
*module
= sdev
->host
->hostt
->module
;
847 /* The module refcount will be zero if scsi_device_get()
848 * was called from a module removal routine */
849 if (module
&& module_refcount(module
) != 0)
852 put_device(&sdev
->sdev_gendev
);
854 EXPORT_SYMBOL(scsi_device_put
);
856 /* helper for shost_for_each_device, thus not documented */
857 struct scsi_device
*__scsi_iterate_devices(struct Scsi_Host
*shost
,
858 struct scsi_device
*prev
)
860 struct list_head
*list
= (prev
? &prev
->siblings
: &shost
->__devices
);
861 struct scsi_device
*next
= NULL
;
864 spin_lock_irqsave(shost
->host_lock
, flags
);
865 while (list
->next
!= &shost
->__devices
) {
866 next
= list_entry(list
->next
, struct scsi_device
, siblings
);
867 /* skip devices that we can't get a reference to */
868 if (!scsi_device_get(next
))
873 spin_unlock_irqrestore(shost
->host_lock
, flags
);
876 scsi_device_put(prev
);
879 EXPORT_SYMBOL(__scsi_iterate_devices
);
882 * starget_for_each_device - helper to walk all devices of a target
883 * @starget: target whose devices we want to iterate over.
885 * This traverses over each devices of @shost. The devices have
886 * a reference that must be released by scsi_host_put when breaking
889 void starget_for_each_device(struct scsi_target
*starget
, void * data
,
890 void (*fn
)(struct scsi_device
*, void *))
892 struct Scsi_Host
*shost
= dev_to_shost(starget
->dev
.parent
);
893 struct scsi_device
*sdev
;
895 shost_for_each_device(sdev
, shost
) {
896 if ((sdev
->channel
== starget
->channel
) &&
897 (sdev
->id
== starget
->id
))
901 EXPORT_SYMBOL(starget_for_each_device
);
904 * __scsi_device_lookup_by_target - find a device given the target (UNLOCKED)
905 * @starget: SCSI target pointer
906 * @lun: SCSI Logical Unit Number
908 * Looks up the scsi_device with the specified @lun for a give
909 * @starget. The returned scsi_device does not have an additional
910 * reference. You must hold the host's host_lock over this call and
911 * any access to the returned scsi_device.
913 * Note: The only reason why drivers would want to use this is because
914 * they're need to access the device list in irq context. Otherwise you
915 * really want to use scsi_device_lookup_by_target instead.
917 struct scsi_device
*__scsi_device_lookup_by_target(struct scsi_target
*starget
,
920 struct scsi_device
*sdev
;
922 list_for_each_entry(sdev
, &starget
->devices
, same_target_siblings
) {
929 EXPORT_SYMBOL(__scsi_device_lookup_by_target
);
932 * scsi_device_lookup_by_target - find a device given the target
933 * @starget: SCSI target pointer
934 * @lun: SCSI Logical Unit Number
936 * Looks up the scsi_device with the specified @channel, @id, @lun for a
937 * give host. The returned scsi_device has an additional reference that
938 * needs to be release with scsi_host_put once you're done with it.
940 struct scsi_device
*scsi_device_lookup_by_target(struct scsi_target
*starget
,
943 struct scsi_device
*sdev
;
944 struct Scsi_Host
*shost
= dev_to_shost(starget
->dev
.parent
);
947 spin_lock_irqsave(shost
->host_lock
, flags
);
948 sdev
= __scsi_device_lookup_by_target(starget
, lun
);
949 if (sdev
&& scsi_device_get(sdev
))
951 spin_unlock_irqrestore(shost
->host_lock
, flags
);
955 EXPORT_SYMBOL(scsi_device_lookup_by_target
);
958 * scsi_device_lookup - find a device given the host (UNLOCKED)
959 * @shost: SCSI host pointer
960 * @channel: SCSI channel (zero if only one channel)
961 * @pun: SCSI target number (physical unit number)
962 * @lun: SCSI Logical Unit Number
964 * Looks up the scsi_device with the specified @channel, @id, @lun for a
965 * give host. The returned scsi_device does not have an additional reference.
966 * You must hold the host's host_lock over this call and any access to the
967 * returned scsi_device.
969 * Note: The only reason why drivers would want to use this is because
970 * they're need to access the device list in irq context. Otherwise you
971 * really want to use scsi_device_lookup instead.
973 struct scsi_device
*__scsi_device_lookup(struct Scsi_Host
*shost
,
974 uint channel
, uint id
, uint lun
)
976 struct scsi_device
*sdev
;
978 list_for_each_entry(sdev
, &shost
->__devices
, siblings
) {
979 if (sdev
->channel
== channel
&& sdev
->id
== id
&&
986 EXPORT_SYMBOL(__scsi_device_lookup
);
989 * scsi_device_lookup - find a device given the host
990 * @shost: SCSI host pointer
991 * @channel: SCSI channel (zero if only one channel)
992 * @id: SCSI target number (physical unit number)
993 * @lun: SCSI Logical Unit Number
995 * Looks up the scsi_device with the specified @channel, @id, @lun for a
996 * give host. The returned scsi_device has an additional reference that
997 * needs to be release with scsi_host_put once you're done with it.
999 struct scsi_device
*scsi_device_lookup(struct Scsi_Host
*shost
,
1000 uint channel
, uint id
, uint lun
)
1002 struct scsi_device
*sdev
;
1003 unsigned long flags
;
1005 spin_lock_irqsave(shost
->host_lock
, flags
);
1006 sdev
= __scsi_device_lookup(shost
, channel
, id
, lun
);
1007 if (sdev
&& scsi_device_get(sdev
))
1009 spin_unlock_irqrestore(shost
->host_lock
, flags
);
1013 EXPORT_SYMBOL(scsi_device_lookup
);
1015 MODULE_DESCRIPTION("SCSI core");
1016 MODULE_LICENSE("GPL");
1018 module_param(scsi_logging_level
, int, S_IRUGO
|S_IWUSR
);
1019 MODULE_PARM_DESC(scsi_logging_level
, "a bit mask of logging levels");
1021 static int __init
init_scsi(void)
1025 error
= scsi_init_queue();
1028 error
= scsi_init_procfs();
1031 error
= scsi_init_devinfo();
1033 goto cleanup_procfs
;
1034 error
= scsi_init_hosts();
1036 goto cleanup_devlist
;
1037 error
= scsi_init_sysctl();
1040 error
= scsi_sysfs_register();
1042 goto cleanup_sysctl
;
1044 scsi_netlink_init();
1046 printk(KERN_NOTICE
"SCSI subsystem initialized\n");
1054 scsi_exit_devinfo();
1059 printk(KERN_ERR
"SCSI subsystem failed to initialize, error = %d\n",
1064 static void __exit
exit_scsi(void)
1066 scsi_netlink_exit();
1067 scsi_sysfs_unregister();
1070 scsi_exit_devinfo();
1075 subsys_initcall(init_scsi
);
1076 module_exit(exit_scsi
);