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_driver.h>
63 #include <scsi/scsi_eh.h>
64 #include <scsi/scsi_host.h>
65 #include <scsi/scsi_tcq.h>
67 #include "scsi_priv.h"
68 #include "scsi_logging.h"
70 static void scsi_done(struct scsi_cmnd *cmd);
73 * Definitions and constants.
76 #define MIN_RESET_DELAY (2*HZ)
78 /* Do not call reset on error if we just did a reset within 15 sec. */
79 #define MIN_RESET_PERIOD (15*HZ)
82 * Macro to determine the size of SCSI command. This macro takes vendor
83 * unique commands into account. SCSI commands in groups 6 and 7 are
84 * vendor unique and we will depend upon the command length being
85 * supplied correctly in cmd_len.
87 #define CDB_SIZE(cmd) (((((cmd)->cmnd[0] >> 5) & 7) < 6) ? \
88 COMMAND_SIZE((cmd)->cmnd[0]) : (cmd)->cmd_len)
91 * Note - the initial logging level can be set here to log events at boot time.
92 * After the system is up, you may enable logging via the /proc interface.
94 unsigned int scsi_logging_level;
95 #if defined(CONFIG_SCSI_LOGGING)
96 EXPORT_SYMBOL(scsi_logging_level);
99 /* NB: These are exposed through /proc/scsi/scsi and form part of the ABI.
100 * You may not alter any existing entry (although adding new ones is
101 * encouraged once assigned by ANSI/INCITS T10
103 static const char *const scsi_device_types[] = {
126 * scsi_device_type - Return 17 char string indicating device type.
127 * @type: type number to look up
130 const char * scsi_device_type(unsigned type)
133 return "Well-known LUN ";
136 if (type >= ARRAY_SIZE(scsi_device_types))
138 return scsi_device_types[type];
141 EXPORT_SYMBOL(scsi_device_type);
143 struct scsi_host_cmd_pool {
144 struct kmem_cache *slab;
147 unsigned int slab_flags;
151 static struct scsi_host_cmd_pool scsi_cmd_pool = {
152 .name = "scsi_cmd_cache",
153 .slab_flags = SLAB_HWCACHE_ALIGN,
156 static struct scsi_host_cmd_pool scsi_cmd_dma_pool = {
157 .name = "scsi_cmd_cache(DMA)",
158 .slab_flags = SLAB_HWCACHE_ALIGN|SLAB_CACHE_DMA,
159 .gfp_mask = __GFP_DMA,
162 static DEFINE_MUTEX(host_cmd_pool_mutex);
165 * __scsi_get_command - Allocate a struct scsi_cmnd
166 * @shost: host to transmit command
167 * @gfp_mask: allocation mask
169 * Description: allocate a struct scsi_cmd from host's slab, recycling from the
170 * host's free_list if necessary.
172 struct scsi_cmnd *__scsi_get_command(struct Scsi_Host *shost, gfp_t gfp_mask)
174 struct scsi_cmnd *cmd;
176 cmd = kmem_cache_alloc(shost->cmd_pool->slab,
177 gfp_mask | shost->cmd_pool->gfp_mask);
179 if (unlikely(!cmd)) {
182 spin_lock_irqsave(&shost->free_list_lock, flags);
183 if (likely(!list_empty(&shost->free_list))) {
184 cmd = list_entry(shost->free_list.next,
185 struct scsi_cmnd, list);
186 list_del_init(&cmd->list);
188 spin_unlock_irqrestore(&shost->free_list_lock, flags);
193 EXPORT_SYMBOL_GPL(__scsi_get_command);
196 * scsi_get_command - Allocate and setup a scsi command block
197 * @dev: parent scsi device
198 * @gfp_mask: allocator flags
200 * Returns: The allocated scsi command structure.
202 struct scsi_cmnd *scsi_get_command(struct scsi_device *dev, gfp_t gfp_mask)
204 struct scsi_cmnd *cmd;
206 /* Bail if we can't get a reference to the device */
207 if (!get_device(&dev->sdev_gendev))
210 cmd = __scsi_get_command(dev->host, gfp_mask);
212 if (likely(cmd != NULL)) {
215 memset(cmd, 0, sizeof(*cmd));
217 init_timer(&cmd->eh_timeout);
218 INIT_LIST_HEAD(&cmd->list);
219 spin_lock_irqsave(&dev->list_lock, flags);
220 list_add_tail(&cmd->list, &dev->cmd_list);
221 spin_unlock_irqrestore(&dev->list_lock, flags);
222 cmd->jiffies_at_alloc = jiffies;
224 put_device(&dev->sdev_gendev);
228 EXPORT_SYMBOL(scsi_get_command);
231 * __scsi_put_command - Free a struct scsi_cmnd
233 * @cmd: Command to free
234 * @dev: parent scsi device
236 void __scsi_put_command(struct Scsi_Host *shost, struct scsi_cmnd *cmd,
241 /* changing locks here, don't need to restore the irq state */
242 spin_lock_irqsave(&shost->free_list_lock, flags);
243 if (unlikely(list_empty(&shost->free_list))) {
244 list_add(&cmd->list, &shost->free_list);
247 spin_unlock_irqrestore(&shost->free_list_lock, flags);
249 if (likely(cmd != NULL))
250 kmem_cache_free(shost->cmd_pool->slab, cmd);
254 EXPORT_SYMBOL(__scsi_put_command);
257 * scsi_put_command - Free a scsi command block
258 * @cmd: command block to free
262 * Notes: The command must not belong to any lists.
264 void scsi_put_command(struct scsi_cmnd *cmd)
266 struct scsi_device *sdev = cmd->device;
269 /* serious error if the command hasn't come from a device list */
270 spin_lock_irqsave(&cmd->device->list_lock, flags);
271 BUG_ON(list_empty(&cmd->list));
272 list_del_init(&cmd->list);
273 spin_unlock_irqrestore(&cmd->device->list_lock, flags);
275 __scsi_put_command(cmd->device->host, cmd, &sdev->sdev_gendev);
277 EXPORT_SYMBOL(scsi_put_command);
280 * scsi_setup_command_freelist - Setup the command freelist for a scsi host.
281 * @shost: host to allocate the freelist for.
283 * Description: The command freelist protects against system-wide out of memory
284 * deadlock by preallocating one SCSI command structure for each host, so the
285 * system can always write to a swap file on a device associated with that host.
289 int scsi_setup_command_freelist(struct Scsi_Host *shost)
291 struct scsi_host_cmd_pool *pool;
292 struct scsi_cmnd *cmd;
294 spin_lock_init(&shost->free_list_lock);
295 INIT_LIST_HEAD(&shost->free_list);
298 * Select a command slab for this host and create it if not
301 mutex_lock(&host_cmd_pool_mutex);
302 pool = (shost->unchecked_isa_dma ? &scsi_cmd_dma_pool : &scsi_cmd_pool);
304 pool->slab = kmem_cache_create(pool->name,
305 sizeof(struct scsi_cmnd), 0,
306 pool->slab_flags, NULL);
312 shost->cmd_pool = pool;
313 mutex_unlock(&host_cmd_pool_mutex);
316 * Get one backup command for this host.
318 cmd = kmem_cache_alloc(shost->cmd_pool->slab,
319 GFP_KERNEL | shost->cmd_pool->gfp_mask);
322 list_add(&cmd->list, &shost->free_list);
327 kmem_cache_destroy(pool->slab);
330 mutex_unlock(&host_cmd_pool_mutex);
336 * scsi_destroy_command_freelist - Release the command freelist for a scsi host.
337 * @shost: host whose freelist is going to be destroyed
339 void scsi_destroy_command_freelist(struct Scsi_Host *shost)
341 while (!list_empty(&shost->free_list)) {
342 struct scsi_cmnd *cmd;
344 cmd = list_entry(shost->free_list.next, struct scsi_cmnd, list);
345 list_del_init(&cmd->list);
346 kmem_cache_free(shost->cmd_pool->slab, cmd);
349 mutex_lock(&host_cmd_pool_mutex);
350 if (!--shost->cmd_pool->users)
351 kmem_cache_destroy(shost->cmd_pool->slab);
352 mutex_unlock(&host_cmd_pool_mutex);
355 #ifdef CONFIG_SCSI_LOGGING
356 void scsi_log_send(struct scsi_cmnd *cmd)
361 * If ML QUEUE log level is greater than or equal to:
363 * 1: nothing (match completion)
365 * 2: log opcode + command of all commands
367 * 3: same as 2 plus dump cmd address
369 * 4: same as 3 plus dump extra junk
371 if (unlikely(scsi_logging_level)) {
372 level = SCSI_LOG_LEVEL(SCSI_LOG_MLQUEUE_SHIFT,
373 SCSI_LOG_MLQUEUE_BITS);
375 scmd_printk(KERN_INFO, cmd, "Send: ");
377 printk("0x%p ", cmd);
379 scsi_print_command(cmd);
381 printk(KERN_INFO "buffer = 0x%p, bufflen = %d,"
382 " queuecommand 0x%p\n",
383 scsi_sglist(cmd), scsi_bufflen(cmd),
384 cmd->device->host->hostt->queuecommand);
391 void scsi_log_completion(struct scsi_cmnd *cmd, int disposition)
396 * If ML COMPLETE log level is greater than or equal to:
398 * 1: log disposition, result, opcode + command, and conditionally
399 * sense data for failures or non SUCCESS dispositions.
401 * 2: same as 1 but for all command completions.
403 * 3: same as 2 plus dump cmd address
405 * 4: same as 3 plus dump extra junk
407 if (unlikely(scsi_logging_level)) {
408 level = SCSI_LOG_LEVEL(SCSI_LOG_MLCOMPLETE_SHIFT,
409 SCSI_LOG_MLCOMPLETE_BITS);
410 if (((level > 0) && (cmd->result || disposition != SUCCESS)) ||
412 scmd_printk(KERN_INFO, cmd, "Done: ");
414 printk("0x%p ", cmd);
416 * Dump truncated values, so we usually fit within
419 switch (disposition) {
434 * If called via scsi_times_out.
441 scsi_print_result(cmd);
442 scsi_print_command(cmd);
443 if (status_byte(cmd->result) & CHECK_CONDITION)
444 scsi_print_sense("", cmd);
446 scmd_printk(KERN_INFO, cmd,
447 "scsi host busy %d failed %d\n",
448 cmd->device->host->host_busy,
449 cmd->device->host->host_failed);
456 * scsi_cmd_get_serial - Assign a serial number to a command
457 * @host: the scsi host
458 * @cmd: command to assign serial number to
460 * Description: a serial number identifies a request for error recovery
461 * and debugging purposes. Protected by the Host_Lock of host.
463 static inline void scsi_cmd_get_serial(struct Scsi_Host *host, struct scsi_cmnd *cmd)
465 cmd->serial_number = host->cmd_serial_number++;
466 if (cmd->serial_number == 0)
467 cmd->serial_number = host->cmd_serial_number++;
471 * scsi_dispatch_command - Dispatch a command to the low-level driver.
472 * @cmd: command block we are dispatching.
474 * Return: nonzero return request was rejected and device's queue needs to be
477 int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
479 struct Scsi_Host *host = cmd->device->host;
480 unsigned long flags = 0;
481 unsigned long timeout;
484 /* check if the device is still usable */
485 if (unlikely(cmd->device->sdev_state == SDEV_DEL)) {
486 /* in SDEV_DEL we error all commands. DID_NO_CONNECT
487 * returns an immediate error upwards, and signals
488 * that the device is no longer present */
489 cmd->result = DID_NO_CONNECT << 16;
490 atomic_inc(&cmd->device->iorequest_cnt);
492 /* return 0 (because the command has been processed) */
496 /* Check to see if the scsi lld put this device into state SDEV_BLOCK. */
497 if (unlikely(cmd->device->sdev_state == SDEV_BLOCK)) {
499 * in SDEV_BLOCK, the command is just put back on the device
500 * queue. The suspend state has already blocked the queue so
501 * future requests should not occur until the device
502 * transitions out of the suspend state.
504 scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
506 SCSI_LOG_MLQUEUE(3, printk("queuecommand : device blocked \n"));
509 * NOTE: rtn is still zero here because we don't need the
510 * queue to be plugged on return (it's already stopped)
516 * If SCSI-2 or lower, store the LUN value in cmnd.
518 if (cmd->device->scsi_level <= SCSI_2 &&
519 cmd->device->scsi_level != SCSI_UNKNOWN) {
520 cmd->cmnd[1] = (cmd->cmnd[1] & 0x1f) |
521 (cmd->device->lun << 5 & 0xe0);
525 * We will wait MIN_RESET_DELAY clock ticks after the last reset so
526 * we can avoid the drive not being ready.
528 timeout = host->last_reset + MIN_RESET_DELAY;
530 if (host->resetting && time_before(jiffies, timeout)) {
531 int ticks_remaining = timeout - jiffies;
533 * NOTE: This may be executed from within an interrupt
534 * handler! This is bad, but for now, it'll do. The irq
535 * level of the interrupt handler has been masked out by the
536 * platform dependent interrupt handling code already, so the
537 * sti() here will not cause another call to the SCSI host's
538 * interrupt handler (assuming there is one irq-level per
541 while (--ticks_remaining >= 0)
542 mdelay(1 + 999 / HZ);
547 * AK: unlikely race here: for some reason the timer could
548 * expire before the serial number is set up below.
550 scsi_add_timer(cmd, cmd->timeout_per_command, scsi_times_out);
555 * We will use a queued command if possible, otherwise we will
556 * emulate the queuing and calling of completion function ourselves.
558 atomic_inc(&cmd->device->iorequest_cnt);
561 * Before we queue this command, check if the command
562 * length exceeds what the host adapter can handle.
564 if (CDB_SIZE(cmd) > cmd->device->host->max_cmd_len) {
566 printk("queuecommand : command too long.\n"));
567 cmd->result = (DID_ABORT << 16);
573 spin_lock_irqsave(host->host_lock, flags);
574 scsi_cmd_get_serial(host, cmd);
576 if (unlikely(host->shost_state == SHOST_DEL)) {
577 cmd->result = (DID_NO_CONNECT << 16);
580 rtn = host->hostt->queuecommand(cmd, scsi_done);
582 spin_unlock_irqrestore(host->host_lock, flags);
584 if (scsi_delete_timer(cmd)) {
585 atomic_inc(&cmd->device->iodone_cnt);
586 scsi_queue_insert(cmd,
587 (rtn == SCSI_MLQUEUE_DEVICE_BUSY) ?
588 rtn : SCSI_MLQUEUE_HOST_BUSY);
591 printk("queuecommand : request rejected\n"));
595 SCSI_LOG_MLQUEUE(3, printk("leaving scsi_dispatch_cmnd()\n"));
600 * scsi_req_abort_cmd -- Request command recovery for the specified command
601 * @cmd: pointer to the SCSI command of interest
603 * This function requests that SCSI Core start recovery for the
604 * command by deleting the timer and adding the command to the eh
605 * queue. It can be called by either LLDDs or SCSI Core. LLDDs who
606 * implement their own error recovery MAY ignore the timeout event if
607 * they generated scsi_req_abort_cmd.
609 void scsi_req_abort_cmd(struct scsi_cmnd *cmd)
611 if (!scsi_delete_timer(cmd))
615 EXPORT_SYMBOL(scsi_req_abort_cmd);
618 * scsi_done - Enqueue the finished SCSI command into the done queue.
619 * @cmd: The SCSI Command for which a low-level device driver (LLDD) gives
620 * ownership back to SCSI Core -- i.e. the LLDD has finished with it.
622 * Description: This function is the mid-level's (SCSI Core) interrupt routine,
623 * which regains ownership of the SCSI command (de facto) from a LLDD, and
624 * enqueues the command to the done queue for further processing.
626 * This is the producer of the done queue who enqueues at the tail.
628 * This function is interrupt context safe.
630 static void scsi_done(struct scsi_cmnd *cmd)
633 * We don't have to worry about this one timing out anymore.
634 * If we are unable to remove the timer, then the command
635 * has already timed out. In which case, we have no choice but to
636 * let the timeout function run, as we have no idea where in fact
637 * that function could really be. It might be on another processor,
640 if (!scsi_delete_timer(cmd))
645 /* Private entry to scsi_done() to complete a command when the timer
646 * isn't running --- used by scsi_times_out */
647 void __scsi_done(struct scsi_cmnd *cmd)
649 struct request *rq = cmd->request;
652 * Set the serial numbers back to zero
654 cmd->serial_number = 0;
656 atomic_inc(&cmd->device->iodone_cnt);
658 atomic_inc(&cmd->device->ioerr_cnt);
663 * The uptodate/nbytes values don't matter, as we allow partial
664 * completes and thus will check this in the softirq callback
666 rq->completion_data = cmd;
667 blk_complete_request(rq);
670 /* Move this to a header if it becomes more generally useful */
671 static struct scsi_driver *scsi_cmd_to_driver(struct scsi_cmnd *cmd)
673 return *(struct scsi_driver **)cmd->request->rq_disk->private_data;
677 * scsi_finish_command - cleanup and pass command back to upper layer
680 * Description: Pass command off to upper layer for finishing of I/O
681 * request, waking processes that are waiting on results,
684 void scsi_finish_command(struct scsi_cmnd *cmd)
686 struct scsi_device *sdev = cmd->device;
687 struct Scsi_Host *shost = sdev->host;
688 struct scsi_driver *drv;
689 unsigned int good_bytes;
691 scsi_device_unbusy(sdev);
694 * Clear the flags which say that the device/host is no longer
695 * capable of accepting new commands. These are set in scsi_queue.c
696 * for both the queue full condition on a device, and for a
697 * host full condition on the host.
699 * XXX(hch): What about locking?
701 shost->host_blocked = 0;
702 sdev->device_blocked = 0;
705 * If we have valid sense information, then some kind of recovery
706 * must have taken place. Make a note of this.
708 if (SCSI_SENSE_VALID(cmd))
709 cmd->result |= (DRIVER_SENSE << 24);
711 SCSI_LOG_MLCOMPLETE(4, sdev_printk(KERN_INFO, sdev,
712 "Notifying upper driver of completion "
713 "(result %x)\n", cmd->result));
715 good_bytes = cmd->request_bufflen;
716 if (cmd->request->cmd_type != REQ_TYPE_BLOCK_PC) {
717 drv = scsi_cmd_to_driver(cmd);
719 good_bytes = drv->done(cmd);
721 scsi_io_completion(cmd, good_bytes);
723 EXPORT_SYMBOL(scsi_finish_command);
726 * scsi_adjust_queue_depth - Let low level drivers change a device's queue depth
727 * @sdev: SCSI Device in question
728 * @tagged: Do we use tagged queueing (non-0) or do we treat
729 * this device as an untagged device (0)
730 * @tags: Number of tags allowed if tagged queueing enabled,
731 * or number of commands the low level driver can
732 * queue up in non-tagged mode (as per cmd_per_lun).
736 * Lock Status: None held on entry
738 * Notes: Low level drivers may call this at any time and we will do
739 * the right thing depending on whether or not the device is
740 * currently active and whether or not it even has the
741 * command blocks built yet.
743 void scsi_adjust_queue_depth(struct scsi_device *sdev, int tagged, int tags)
748 * refuse to set tagged depth to an unworkable size
753 spin_lock_irqsave(sdev->request_queue->queue_lock, flags);
755 /* Check to see if the queue is managed by the block layer.
756 * If it is, and we fail to adjust the depth, exit. */
757 if (blk_queue_tagged(sdev->request_queue) &&
758 blk_queue_resize_tags(sdev->request_queue, tags) != 0)
761 sdev->queue_depth = tags;
763 case MSG_ORDERED_TAG:
764 sdev->ordered_tags = 1;
765 sdev->simple_tags = 1;
768 sdev->ordered_tags = 0;
769 sdev->simple_tags = 1;
772 sdev_printk(KERN_WARNING, sdev,
773 "scsi_adjust_queue_depth, bad queue type, "
776 sdev->ordered_tags = sdev->simple_tags = 0;
777 sdev->queue_depth = tags;
781 spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
783 EXPORT_SYMBOL(scsi_adjust_queue_depth);
786 * scsi_track_queue_full - track QUEUE_FULL events to adjust queue depth
787 * @sdev: SCSI Device in question
788 * @depth: Current number of outstanding SCSI commands on this device,
789 * not counting the one returned as QUEUE_FULL.
791 * Description: This function will track successive QUEUE_FULL events on a
792 * specific SCSI device to determine if and when there is a
793 * need to adjust the queue depth on the device.
795 * Returns: 0 - No change needed, >0 - Adjust queue depth to this new depth,
796 * -1 - Drop back to untagged operation using host->cmd_per_lun
797 * as the untagged command depth
799 * Lock Status: None held on entry
801 * Notes: Low level drivers may call this at any time and we will do
802 * "The Right Thing." We are interrupt context safe.
804 int scsi_track_queue_full(struct scsi_device *sdev, int depth)
806 if ((jiffies >> 4) == sdev->last_queue_full_time)
809 sdev->last_queue_full_time = (jiffies >> 4);
810 if (sdev->last_queue_full_depth != depth) {
811 sdev->last_queue_full_count = 1;
812 sdev->last_queue_full_depth = depth;
814 sdev->last_queue_full_count++;
817 if (sdev->last_queue_full_count <= 10)
819 if (sdev->last_queue_full_depth < 8) {
820 /* Drop back to untagged */
821 scsi_adjust_queue_depth(sdev, 0, sdev->host->cmd_per_lun);
825 if (sdev->ordered_tags)
826 scsi_adjust_queue_depth(sdev, MSG_ORDERED_TAG, depth);
828 scsi_adjust_queue_depth(sdev, MSG_SIMPLE_TAG, depth);
831 EXPORT_SYMBOL(scsi_track_queue_full);
834 * scsi_device_get - get an additional reference to a scsi_device
835 * @sdev: device to get a reference to
837 * Description: Gets a reference to the scsi_device and increments the use count
838 * of the underlying LLDD module. You must hold host_lock of the
839 * parent Scsi_Host or already have a reference when calling this.
841 int scsi_device_get(struct scsi_device *sdev)
843 if (sdev->sdev_state == SDEV_DEL)
845 if (!get_device(&sdev->sdev_gendev))
847 /* We can fail this if we're doing SCSI operations
848 * from module exit (like cache flush) */
849 try_module_get(sdev->host->hostt->module);
853 EXPORT_SYMBOL(scsi_device_get);
856 * scsi_device_put - release a reference to a scsi_device
857 * @sdev: device to release a reference on.
859 * Description: Release a reference to the scsi_device and decrements the use
860 * count of the underlying LLDD module. The device is freed once the last
863 void scsi_device_put(struct scsi_device *sdev)
865 #ifdef CONFIG_MODULE_UNLOAD
866 struct module *module = sdev->host->hostt->module;
868 /* The module refcount will be zero if scsi_device_get()
869 * was called from a module removal routine */
870 if (module && module_refcount(module) != 0)
873 put_device(&sdev->sdev_gendev);
875 EXPORT_SYMBOL(scsi_device_put);
877 /* helper for shost_for_each_device, see that for documentation */
878 struct scsi_device *__scsi_iterate_devices(struct Scsi_Host *shost,
879 struct scsi_device *prev)
881 struct list_head *list = (prev ? &prev->siblings : &shost->__devices);
882 struct scsi_device *next = NULL;
885 spin_lock_irqsave(shost->host_lock, flags);
886 while (list->next != &shost->__devices) {
887 next = list_entry(list->next, struct scsi_device, siblings);
888 /* skip devices that we can't get a reference to */
889 if (!scsi_device_get(next))
894 spin_unlock_irqrestore(shost->host_lock, flags);
897 scsi_device_put(prev);
900 EXPORT_SYMBOL(__scsi_iterate_devices);
903 * starget_for_each_device - helper to walk all devices of a target
904 * @starget: target whose devices we want to iterate over.
905 * @data: Opaque passed to each function call.
906 * @fn: Function to call on each device
908 * This traverses over each device of @starget. The devices have
909 * a reference that must be released by scsi_host_put when breaking
912 void starget_for_each_device(struct scsi_target *starget, void *data,
913 void (*fn)(struct scsi_device *, void *))
915 struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
916 struct scsi_device *sdev;
918 shost_for_each_device(sdev, shost) {
919 if ((sdev->channel == starget->channel) &&
920 (sdev->id == starget->id))
924 EXPORT_SYMBOL(starget_for_each_device);
927 * __starget_for_each_device - helper to walk all devices of a target
929 * @starget: target whose devices we want to iterate over.
931 * This traverses over each device of @starget. It does _not_
932 * take a reference on the scsi_device, so the whole loop must be
933 * protected by shost->host_lock.
935 * Note: The only reason why drivers would want to use this is because
936 * they need to access the device list in irq context. Otherwise you
937 * really want to use starget_for_each_device instead.
939 void __starget_for_each_device(struct scsi_target *starget, void *data,
940 void (*fn)(struct scsi_device *, void *))
942 struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
943 struct scsi_device *sdev;
945 __shost_for_each_device(sdev, shost) {
946 if ((sdev->channel == starget->channel) &&
947 (sdev->id == starget->id))
951 EXPORT_SYMBOL(__starget_for_each_device);
954 * __scsi_device_lookup_by_target - find a device given the target (UNLOCKED)
955 * @starget: SCSI target pointer
956 * @lun: SCSI Logical Unit Number
958 * Description: Looks up the scsi_device with the specified @lun for a given
959 * @starget. The returned scsi_device does not have an additional
960 * reference. You must hold the host's host_lock over this call and
961 * any access to the returned scsi_device.
963 * Note: The only reason why drivers should use this is because
964 * they need to access the device list in irq context. Otherwise you
965 * really want to use scsi_device_lookup_by_target instead.
967 struct scsi_device *__scsi_device_lookup_by_target(struct scsi_target *starget,
970 struct scsi_device *sdev;
972 list_for_each_entry(sdev, &starget->devices, same_target_siblings) {
979 EXPORT_SYMBOL(__scsi_device_lookup_by_target);
982 * scsi_device_lookup_by_target - find a device given the target
983 * @starget: SCSI target pointer
984 * @lun: SCSI Logical Unit Number
986 * Description: Looks up the scsi_device with the specified @channel, @id, @lun
987 * for a given host. The returned scsi_device has an additional reference that
988 * needs to be released with scsi_device_put once you're done with it.
990 struct scsi_device *scsi_device_lookup_by_target(struct scsi_target *starget,
993 struct scsi_device *sdev;
994 struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
997 spin_lock_irqsave(shost->host_lock, flags);
998 sdev = __scsi_device_lookup_by_target(starget, lun);
999 if (sdev && scsi_device_get(sdev))
1001 spin_unlock_irqrestore(shost->host_lock, flags);
1005 EXPORT_SYMBOL(scsi_device_lookup_by_target);
1008 * __scsi_device_lookup - find a device given the host (UNLOCKED)
1009 * @shost: SCSI host pointer
1010 * @channel: SCSI channel (zero if only one channel)
1011 * @id: SCSI target number (physical unit number)
1012 * @lun: SCSI Logical Unit Number
1014 * Description: Looks up the scsi_device with the specified @channel, @id, @lun
1015 * for a given host. The returned scsi_device does not have an additional
1016 * reference. You must hold the host's host_lock over this call and any access
1017 * to the returned scsi_device.
1019 * Note: The only reason why drivers would want to use this is because
1020 * they need to access the device list in irq context. Otherwise you
1021 * really want to use scsi_device_lookup instead.
1023 struct scsi_device *__scsi_device_lookup(struct Scsi_Host *shost,
1024 uint channel, uint id, uint lun)
1026 struct scsi_device *sdev;
1028 list_for_each_entry(sdev, &shost->__devices, siblings) {
1029 if (sdev->channel == channel && sdev->id == id &&
1036 EXPORT_SYMBOL(__scsi_device_lookup);
1039 * scsi_device_lookup - find a device given the host
1040 * @shost: SCSI host pointer
1041 * @channel: SCSI channel (zero if only one channel)
1042 * @id: SCSI target number (physical unit number)
1043 * @lun: SCSI Logical Unit Number
1045 * Description: Looks up the scsi_device with the specified @channel, @id, @lun
1046 * for a given host. The returned scsi_device has an additional reference that
1047 * needs to be released with scsi_device_put once you're done with it.
1049 struct scsi_device *scsi_device_lookup(struct Scsi_Host *shost,
1050 uint channel, uint id, uint lun)
1052 struct scsi_device *sdev;
1053 unsigned long flags;
1055 spin_lock_irqsave(shost->host_lock, flags);
1056 sdev = __scsi_device_lookup(shost, channel, id, lun);
1057 if (sdev && scsi_device_get(sdev))
1059 spin_unlock_irqrestore(shost->host_lock, flags);
1063 EXPORT_SYMBOL(scsi_device_lookup);
1065 MODULE_DESCRIPTION("SCSI core");
1066 MODULE_LICENSE("GPL");
1068 module_param(scsi_logging_level, int, S_IRUGO|S_IWUSR);
1069 MODULE_PARM_DESC(scsi_logging_level, "a bit mask of logging levels");
1071 static int __init init_scsi(void)
1075 error = scsi_init_queue();
1078 error = scsi_init_procfs();
1081 error = scsi_init_devinfo();
1083 goto cleanup_procfs;
1084 error = scsi_init_hosts();
1086 goto cleanup_devlist;
1087 error = scsi_init_sysctl();
1090 error = scsi_sysfs_register();
1092 goto cleanup_sysctl;
1094 scsi_netlink_init();
1096 printk(KERN_NOTICE "SCSI subsystem initialized\n");
1104 scsi_exit_devinfo();
1109 printk(KERN_ERR "SCSI subsystem failed to initialize, error = %d\n",
1114 static void __exit exit_scsi(void)
1116 scsi_netlink_exit();
1117 scsi_sysfs_unregister();
1120 scsi_exit_devinfo();
1125 subsys_initcall(init_scsi);
1126 module_exit(exit_scsi);