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);
164 static struct kmem_cache *sense_buffer_slab;
165 static int sense_buffer_slab_users;
168 * __scsi_get_command - Allocate a struct scsi_cmnd
169 * @shost: host to transmit command
170 * @gfp_mask: allocation mask
172 * Description: allocate a struct scsi_cmd from host's slab, recycling from the
173 * host's free_list if necessary.
175 struct scsi_cmnd *__scsi_get_command(struct Scsi_Host *shost, gfp_t gfp_mask)
177 struct scsi_cmnd *cmd;
180 cmd = kmem_cache_alloc(shost->cmd_pool->slab,
181 gfp_mask | shost->cmd_pool->gfp_mask);
183 if (unlikely(!cmd)) {
186 spin_lock_irqsave(&shost->free_list_lock, flags);
187 if (likely(!list_empty(&shost->free_list))) {
188 cmd = list_entry(shost->free_list.next,
189 struct scsi_cmnd, list);
190 list_del_init(&cmd->list);
192 spin_unlock_irqrestore(&shost->free_list_lock, flags);
195 buf = cmd->sense_buffer;
196 memset(cmd, 0, sizeof(*cmd));
197 cmd->sense_buffer = buf;
200 buf = kmem_cache_alloc(sense_buffer_slab, __GFP_DMA|gfp_mask);
202 memset(cmd, 0, sizeof(*cmd));
203 cmd->sense_buffer = buf;
205 kmem_cache_free(shost->cmd_pool->slab, cmd);
212 EXPORT_SYMBOL_GPL(__scsi_get_command);
215 * scsi_get_command - Allocate and setup a scsi command block
216 * @dev: parent scsi device
217 * @gfp_mask: allocator flags
219 * Returns: The allocated scsi command structure.
221 struct scsi_cmnd *scsi_get_command(struct scsi_device *dev, gfp_t gfp_mask)
223 struct scsi_cmnd *cmd;
225 /* Bail if we can't get a reference to the device */
226 if (!get_device(&dev->sdev_gendev))
229 cmd = __scsi_get_command(dev->host, gfp_mask);
231 if (likely(cmd != NULL)) {
235 init_timer(&cmd->eh_timeout);
236 INIT_LIST_HEAD(&cmd->list);
237 spin_lock_irqsave(&dev->list_lock, flags);
238 list_add_tail(&cmd->list, &dev->cmd_list);
239 spin_unlock_irqrestore(&dev->list_lock, flags);
240 cmd->jiffies_at_alloc = jiffies;
242 put_device(&dev->sdev_gendev);
246 EXPORT_SYMBOL(scsi_get_command);
249 * __scsi_put_command - Free a struct scsi_cmnd
251 * @cmd: Command to free
252 * @dev: parent scsi device
254 void __scsi_put_command(struct Scsi_Host *shost, struct scsi_cmnd *cmd,
259 /* changing locks here, don't need to restore the irq state */
260 spin_lock_irqsave(&shost->free_list_lock, flags);
261 if (unlikely(list_empty(&shost->free_list))) {
262 list_add(&cmd->list, &shost->free_list);
265 spin_unlock_irqrestore(&shost->free_list_lock, flags);
267 if (likely(cmd != NULL)) {
268 kmem_cache_free(sense_buffer_slab, cmd->sense_buffer);
269 kmem_cache_free(shost->cmd_pool->slab, cmd);
274 EXPORT_SYMBOL(__scsi_put_command);
277 * scsi_put_command - Free a scsi command block
278 * @cmd: command block to free
282 * Notes: The command must not belong to any lists.
284 void scsi_put_command(struct scsi_cmnd *cmd)
286 struct scsi_device *sdev = cmd->device;
289 /* serious error if the command hasn't come from a device list */
290 spin_lock_irqsave(&cmd->device->list_lock, flags);
291 BUG_ON(list_empty(&cmd->list));
292 list_del_init(&cmd->list);
293 spin_unlock_irqrestore(&cmd->device->list_lock, flags);
295 __scsi_put_command(cmd->device->host, cmd, &sdev->sdev_gendev);
297 EXPORT_SYMBOL(scsi_put_command);
300 * scsi_setup_command_freelist - Setup the command freelist for a scsi host.
301 * @shost: host to allocate the freelist for.
303 * Description: The command freelist protects against system-wide out of memory
304 * deadlock by preallocating one SCSI command structure for each host, so the
305 * system can always write to a swap file on a device associated with that host.
309 int scsi_setup_command_freelist(struct Scsi_Host *shost)
311 struct scsi_host_cmd_pool *pool;
312 struct scsi_cmnd *cmd;
313 unsigned char *sense_buffer;
315 spin_lock_init(&shost->free_list_lock);
316 INIT_LIST_HEAD(&shost->free_list);
319 * Select a command slab for this host and create it if not
322 mutex_lock(&host_cmd_pool_mutex);
323 pool = (shost->unchecked_isa_dma ? &scsi_cmd_dma_pool : &scsi_cmd_pool);
325 pool->slab = kmem_cache_create(pool->name,
326 sizeof(struct scsi_cmnd), 0,
327 pool->slab_flags, NULL);
333 shost->cmd_pool = pool;
334 mutex_unlock(&host_cmd_pool_mutex);
337 * Get one backup command for this host.
339 cmd = kmem_cache_alloc(shost->cmd_pool->slab,
340 GFP_KERNEL | shost->cmd_pool->gfp_mask);
344 sense_buffer = kmem_cache_alloc(sense_buffer_slab,
345 GFP_KERNEL | __GFP_DMA);
349 cmd->sense_buffer = sense_buffer;
350 list_add(&cmd->list, &shost->free_list);
354 kmem_cache_free(shost->cmd_pool->slab, cmd);
356 mutex_lock(&host_cmd_pool_mutex);
358 kmem_cache_destroy(pool->slab);
360 mutex_unlock(&host_cmd_pool_mutex);
365 * scsi_destroy_command_freelist - Release the command freelist for a scsi host.
366 * @shost: host whose freelist is going to be destroyed
368 void scsi_destroy_command_freelist(struct Scsi_Host *shost)
370 while (!list_empty(&shost->free_list)) {
371 struct scsi_cmnd *cmd;
373 cmd = list_entry(shost->free_list.next, struct scsi_cmnd, list);
374 list_del_init(&cmd->list);
375 kmem_cache_free(sense_buffer_slab, cmd->sense_buffer);
376 kmem_cache_free(shost->cmd_pool->slab, cmd);
379 mutex_lock(&host_cmd_pool_mutex);
380 if (!--shost->cmd_pool->users)
381 kmem_cache_destroy(shost->cmd_pool->slab);
382 mutex_unlock(&host_cmd_pool_mutex);
385 int scsi_setup_command_sense_buffer(struct Scsi_Host *shost)
387 mutex_lock(&host_cmd_pool_mutex);
388 if (!sense_buffer_slab_users) {
389 sense_buffer_slab = kmem_cache_create("scsi_sense_buffer",
390 SCSI_SENSE_BUFFERSIZE,
391 0, SLAB_CACHE_DMA, NULL);
392 if (!sense_buffer_slab) {
393 mutex_unlock(&host_cmd_pool_mutex);
397 sense_buffer_slab_users++;
398 mutex_unlock(&host_cmd_pool_mutex);
403 void scsi_destroy_command_sense_buffer(struct Scsi_Host *shost)
405 mutex_lock(&host_cmd_pool_mutex);
406 if (!--sense_buffer_slab_users)
407 kmem_cache_destroy(sense_buffer_slab);
408 mutex_unlock(&host_cmd_pool_mutex);
411 #ifdef CONFIG_SCSI_LOGGING
412 void scsi_log_send(struct scsi_cmnd *cmd)
417 * If ML QUEUE log level is greater than or equal to:
419 * 1: nothing (match completion)
421 * 2: log opcode + command of all commands
423 * 3: same as 2 plus dump cmd address
425 * 4: same as 3 plus dump extra junk
427 if (unlikely(scsi_logging_level)) {
428 level = SCSI_LOG_LEVEL(SCSI_LOG_MLQUEUE_SHIFT,
429 SCSI_LOG_MLQUEUE_BITS);
431 scmd_printk(KERN_INFO, cmd, "Send: ");
433 printk("0x%p ", cmd);
435 scsi_print_command(cmd);
437 printk(KERN_INFO "buffer = 0x%p, bufflen = %d,"
438 " queuecommand 0x%p\n",
439 scsi_sglist(cmd), scsi_bufflen(cmd),
440 cmd->device->host->hostt->queuecommand);
447 void scsi_log_completion(struct scsi_cmnd *cmd, int disposition)
452 * If ML COMPLETE log level is greater than or equal to:
454 * 1: log disposition, result, opcode + command, and conditionally
455 * sense data for failures or non SUCCESS dispositions.
457 * 2: same as 1 but for all command completions.
459 * 3: same as 2 plus dump cmd address
461 * 4: same as 3 plus dump extra junk
463 if (unlikely(scsi_logging_level)) {
464 level = SCSI_LOG_LEVEL(SCSI_LOG_MLCOMPLETE_SHIFT,
465 SCSI_LOG_MLCOMPLETE_BITS);
466 if (((level > 0) && (cmd->result || disposition != SUCCESS)) ||
468 scmd_printk(KERN_INFO, cmd, "Done: ");
470 printk("0x%p ", cmd);
472 * Dump truncated values, so we usually fit within
475 switch (disposition) {
490 * If called via scsi_times_out.
497 scsi_print_result(cmd);
498 scsi_print_command(cmd);
499 if (status_byte(cmd->result) & CHECK_CONDITION)
500 scsi_print_sense("", cmd);
502 scmd_printk(KERN_INFO, cmd,
503 "scsi host busy %d failed %d\n",
504 cmd->device->host->host_busy,
505 cmd->device->host->host_failed);
512 * scsi_cmd_get_serial - Assign a serial number to a command
513 * @host: the scsi host
514 * @cmd: command to assign serial number to
516 * Description: a serial number identifies a request for error recovery
517 * and debugging purposes. Protected by the Host_Lock of host.
519 static inline void scsi_cmd_get_serial(struct Scsi_Host *host, struct scsi_cmnd *cmd)
521 cmd->serial_number = host->cmd_serial_number++;
522 if (cmd->serial_number == 0)
523 cmd->serial_number = host->cmd_serial_number++;
527 * scsi_dispatch_command - Dispatch a command to the low-level driver.
528 * @cmd: command block we are dispatching.
530 * Return: nonzero return request was rejected and device's queue needs to be
533 int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
535 struct Scsi_Host *host = cmd->device->host;
536 unsigned long flags = 0;
537 unsigned long timeout;
540 /* check if the device is still usable */
541 if (unlikely(cmd->device->sdev_state == SDEV_DEL)) {
542 /* in SDEV_DEL we error all commands. DID_NO_CONNECT
543 * returns an immediate error upwards, and signals
544 * that the device is no longer present */
545 cmd->result = DID_NO_CONNECT << 16;
546 atomic_inc(&cmd->device->iorequest_cnt);
548 /* return 0 (because the command has been processed) */
552 /* Check to see if the scsi lld put this device into state SDEV_BLOCK. */
553 if (unlikely(cmd->device->sdev_state == SDEV_BLOCK)) {
555 * in SDEV_BLOCK, the command is just put back on the device
556 * queue. The suspend state has already blocked the queue so
557 * future requests should not occur until the device
558 * transitions out of the suspend state.
560 scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
562 SCSI_LOG_MLQUEUE(3, printk("queuecommand : device blocked \n"));
565 * NOTE: rtn is still zero here because we don't need the
566 * queue to be plugged on return (it's already stopped)
572 * If SCSI-2 or lower, store the LUN value in cmnd.
574 if (cmd->device->scsi_level <= SCSI_2 &&
575 cmd->device->scsi_level != SCSI_UNKNOWN) {
576 cmd->cmnd[1] = (cmd->cmnd[1] & 0x1f) |
577 (cmd->device->lun << 5 & 0xe0);
581 * We will wait MIN_RESET_DELAY clock ticks after the last reset so
582 * we can avoid the drive not being ready.
584 timeout = host->last_reset + MIN_RESET_DELAY;
586 if (host->resetting && time_before(jiffies, timeout)) {
587 int ticks_remaining = timeout - jiffies;
589 * NOTE: This may be executed from within an interrupt
590 * handler! This is bad, but for now, it'll do. The irq
591 * level of the interrupt handler has been masked out by the
592 * platform dependent interrupt handling code already, so the
593 * sti() here will not cause another call to the SCSI host's
594 * interrupt handler (assuming there is one irq-level per
597 while (--ticks_remaining >= 0)
598 mdelay(1 + 999 / HZ);
603 * AK: unlikely race here: for some reason the timer could
604 * expire before the serial number is set up below.
606 scsi_add_timer(cmd, cmd->timeout_per_command, scsi_times_out);
611 * We will use a queued command if possible, otherwise we will
612 * emulate the queuing and calling of completion function ourselves.
614 atomic_inc(&cmd->device->iorequest_cnt);
617 * Before we queue this command, check if the command
618 * length exceeds what the host adapter can handle.
620 if (CDB_SIZE(cmd) > cmd->device->host->max_cmd_len) {
622 printk("queuecommand : command too long.\n"));
623 cmd->result = (DID_ABORT << 16);
629 spin_lock_irqsave(host->host_lock, flags);
630 scsi_cmd_get_serial(host, cmd);
632 if (unlikely(host->shost_state == SHOST_DEL)) {
633 cmd->result = (DID_NO_CONNECT << 16);
636 rtn = host->hostt->queuecommand(cmd, scsi_done);
638 spin_unlock_irqrestore(host->host_lock, flags);
640 if (scsi_delete_timer(cmd)) {
641 atomic_inc(&cmd->device->iodone_cnt);
642 scsi_queue_insert(cmd,
643 (rtn == SCSI_MLQUEUE_DEVICE_BUSY) ?
644 rtn : SCSI_MLQUEUE_HOST_BUSY);
647 printk("queuecommand : request rejected\n"));
651 SCSI_LOG_MLQUEUE(3, printk("leaving scsi_dispatch_cmnd()\n"));
656 * scsi_req_abort_cmd -- Request command recovery for the specified command
657 * @cmd: pointer to the SCSI command of interest
659 * This function requests that SCSI Core start recovery for the
660 * command by deleting the timer and adding the command to the eh
661 * queue. It can be called by either LLDDs or SCSI Core. LLDDs who
662 * implement their own error recovery MAY ignore the timeout event if
663 * they generated scsi_req_abort_cmd.
665 void scsi_req_abort_cmd(struct scsi_cmnd *cmd)
667 if (!scsi_delete_timer(cmd))
671 EXPORT_SYMBOL(scsi_req_abort_cmd);
674 * scsi_done - Enqueue the finished SCSI command into the done queue.
675 * @cmd: The SCSI Command for which a low-level device driver (LLDD) gives
676 * ownership back to SCSI Core -- i.e. the LLDD has finished with it.
678 * Description: This function is the mid-level's (SCSI Core) interrupt routine,
679 * which regains ownership of the SCSI command (de facto) from a LLDD, and
680 * enqueues the command to the done queue for further processing.
682 * This is the producer of the done queue who enqueues at the tail.
684 * This function is interrupt context safe.
686 static void scsi_done(struct scsi_cmnd *cmd)
689 * We don't have to worry about this one timing out anymore.
690 * If we are unable to remove the timer, then the command
691 * has already timed out. In which case, we have no choice but to
692 * let the timeout function run, as we have no idea where in fact
693 * that function could really be. It might be on another processor,
696 if (!scsi_delete_timer(cmd))
701 /* Private entry to scsi_done() to complete a command when the timer
702 * isn't running --- used by scsi_times_out */
703 void __scsi_done(struct scsi_cmnd *cmd)
705 struct request *rq = cmd->request;
708 * Set the serial numbers back to zero
710 cmd->serial_number = 0;
712 atomic_inc(&cmd->device->iodone_cnt);
714 atomic_inc(&cmd->device->ioerr_cnt);
719 * The uptodate/nbytes values don't matter, as we allow partial
720 * completes and thus will check this in the softirq callback
722 rq->completion_data = cmd;
723 blk_complete_request(rq);
726 /* Move this to a header if it becomes more generally useful */
727 static struct scsi_driver *scsi_cmd_to_driver(struct scsi_cmnd *cmd)
729 return *(struct scsi_driver **)cmd->request->rq_disk->private_data;
733 * scsi_finish_command - cleanup and pass command back to upper layer
736 * Description: Pass command off to upper layer for finishing of I/O
737 * request, waking processes that are waiting on results,
740 void scsi_finish_command(struct scsi_cmnd *cmd)
742 struct scsi_device *sdev = cmd->device;
743 struct Scsi_Host *shost = sdev->host;
744 struct scsi_driver *drv;
745 unsigned int good_bytes;
747 scsi_device_unbusy(sdev);
750 * Clear the flags which say that the device/host is no longer
751 * capable of accepting new commands. These are set in scsi_queue.c
752 * for both the queue full condition on a device, and for a
753 * host full condition on the host.
755 * XXX(hch): What about locking?
757 shost->host_blocked = 0;
758 sdev->device_blocked = 0;
761 * If we have valid sense information, then some kind of recovery
762 * must have taken place. Make a note of this.
764 if (SCSI_SENSE_VALID(cmd))
765 cmd->result |= (DRIVER_SENSE << 24);
767 SCSI_LOG_MLCOMPLETE(4, sdev_printk(KERN_INFO, sdev,
768 "Notifying upper driver of completion "
769 "(result %x)\n", cmd->result));
771 good_bytes = cmd->request_bufflen;
772 if (cmd->request->cmd_type != REQ_TYPE_BLOCK_PC) {
773 drv = scsi_cmd_to_driver(cmd);
775 good_bytes = drv->done(cmd);
777 scsi_io_completion(cmd, good_bytes);
779 EXPORT_SYMBOL(scsi_finish_command);
782 * scsi_adjust_queue_depth - Let low level drivers change a device's queue depth
783 * @sdev: SCSI Device in question
784 * @tagged: Do we use tagged queueing (non-0) or do we treat
785 * this device as an untagged device (0)
786 * @tags: Number of tags allowed if tagged queueing enabled,
787 * or number of commands the low level driver can
788 * queue up in non-tagged mode (as per cmd_per_lun).
792 * Lock Status: None held on entry
794 * Notes: Low level drivers may call this at any time and we will do
795 * the right thing depending on whether or not the device is
796 * currently active and whether or not it even has the
797 * command blocks built yet.
799 void scsi_adjust_queue_depth(struct scsi_device *sdev, int tagged, int tags)
804 * refuse to set tagged depth to an unworkable size
809 spin_lock_irqsave(sdev->request_queue->queue_lock, flags);
811 /* Check to see if the queue is managed by the block layer.
812 * If it is, and we fail to adjust the depth, exit. */
813 if (blk_queue_tagged(sdev->request_queue) &&
814 blk_queue_resize_tags(sdev->request_queue, tags) != 0)
817 sdev->queue_depth = tags;
819 case MSG_ORDERED_TAG:
820 sdev->ordered_tags = 1;
821 sdev->simple_tags = 1;
824 sdev->ordered_tags = 0;
825 sdev->simple_tags = 1;
828 sdev_printk(KERN_WARNING, sdev,
829 "scsi_adjust_queue_depth, bad queue type, "
832 sdev->ordered_tags = sdev->simple_tags = 0;
833 sdev->queue_depth = tags;
837 spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
839 EXPORT_SYMBOL(scsi_adjust_queue_depth);
842 * scsi_track_queue_full - track QUEUE_FULL events to adjust queue depth
843 * @sdev: SCSI Device in question
844 * @depth: Current number of outstanding SCSI commands on this device,
845 * not counting the one returned as QUEUE_FULL.
847 * Description: This function will track successive QUEUE_FULL events on a
848 * specific SCSI device to determine if and when there is a
849 * need to adjust the queue depth on the device.
851 * Returns: 0 - No change needed, >0 - Adjust queue depth to this new depth,
852 * -1 - Drop back to untagged operation using host->cmd_per_lun
853 * as the untagged command depth
855 * Lock Status: None held on entry
857 * Notes: Low level drivers may call this at any time and we will do
858 * "The Right Thing." We are interrupt context safe.
860 int scsi_track_queue_full(struct scsi_device *sdev, int depth)
862 if ((jiffies >> 4) == sdev->last_queue_full_time)
865 sdev->last_queue_full_time = (jiffies >> 4);
866 if (sdev->last_queue_full_depth != depth) {
867 sdev->last_queue_full_count = 1;
868 sdev->last_queue_full_depth = depth;
870 sdev->last_queue_full_count++;
873 if (sdev->last_queue_full_count <= 10)
875 if (sdev->last_queue_full_depth < 8) {
876 /* Drop back to untagged */
877 scsi_adjust_queue_depth(sdev, 0, sdev->host->cmd_per_lun);
881 if (sdev->ordered_tags)
882 scsi_adjust_queue_depth(sdev, MSG_ORDERED_TAG, depth);
884 scsi_adjust_queue_depth(sdev, MSG_SIMPLE_TAG, depth);
887 EXPORT_SYMBOL(scsi_track_queue_full);
890 * scsi_device_get - get an additional reference to a scsi_device
891 * @sdev: device to get a reference to
893 * Description: Gets a reference to the scsi_device and increments the use count
894 * of the underlying LLDD module. You must hold host_lock of the
895 * parent Scsi_Host or already have a reference when calling this.
897 int scsi_device_get(struct scsi_device *sdev)
899 if (sdev->sdev_state == SDEV_DEL)
901 if (!get_device(&sdev->sdev_gendev))
903 /* We can fail this if we're doing SCSI operations
904 * from module exit (like cache flush) */
905 try_module_get(sdev->host->hostt->module);
909 EXPORT_SYMBOL(scsi_device_get);
912 * scsi_device_put - release a reference to a scsi_device
913 * @sdev: device to release a reference on.
915 * Description: Release a reference to the scsi_device and decrements the use
916 * count of the underlying LLDD module. The device is freed once the last
919 void scsi_device_put(struct scsi_device *sdev)
921 #ifdef CONFIG_MODULE_UNLOAD
922 struct module *module = sdev->host->hostt->module;
924 /* The module refcount will be zero if scsi_device_get()
925 * was called from a module removal routine */
926 if (module && module_refcount(module) != 0)
929 put_device(&sdev->sdev_gendev);
931 EXPORT_SYMBOL(scsi_device_put);
933 /* helper for shost_for_each_device, see that for documentation */
934 struct scsi_device *__scsi_iterate_devices(struct Scsi_Host *shost,
935 struct scsi_device *prev)
937 struct list_head *list = (prev ? &prev->siblings : &shost->__devices);
938 struct scsi_device *next = NULL;
941 spin_lock_irqsave(shost->host_lock, flags);
942 while (list->next != &shost->__devices) {
943 next = list_entry(list->next, struct scsi_device, siblings);
944 /* skip devices that we can't get a reference to */
945 if (!scsi_device_get(next))
950 spin_unlock_irqrestore(shost->host_lock, flags);
953 scsi_device_put(prev);
956 EXPORT_SYMBOL(__scsi_iterate_devices);
959 * starget_for_each_device - helper to walk all devices of a target
960 * @starget: target whose devices we want to iterate over.
961 * @data: Opaque passed to each function call.
962 * @fn: Function to call on each device
964 * This traverses over each device of @starget. The devices have
965 * a reference that must be released by scsi_host_put when breaking
968 void starget_for_each_device(struct scsi_target *starget, void *data,
969 void (*fn)(struct scsi_device *, void *))
971 struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
972 struct scsi_device *sdev;
974 shost_for_each_device(sdev, shost) {
975 if ((sdev->channel == starget->channel) &&
976 (sdev->id == starget->id))
980 EXPORT_SYMBOL(starget_for_each_device);
983 * __starget_for_each_device - helper to walk all devices of a target
985 * @starget: target whose devices we want to iterate over.
987 * This traverses over each device of @starget. It does _not_
988 * take a reference on the scsi_device, so the whole loop must be
989 * protected by shost->host_lock.
991 * Note: The only reason why drivers would want to use this is because
992 * they need to access the device list in irq context. Otherwise you
993 * really want to use starget_for_each_device instead.
995 void __starget_for_each_device(struct scsi_target *starget, void *data,
996 void (*fn)(struct scsi_device *, void *))
998 struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
999 struct scsi_device *sdev;
1001 __shost_for_each_device(sdev, shost) {
1002 if ((sdev->channel == starget->channel) &&
1003 (sdev->id == starget->id))
1007 EXPORT_SYMBOL(__starget_for_each_device);
1010 * __scsi_device_lookup_by_target - find a device given the target (UNLOCKED)
1011 * @starget: SCSI target pointer
1012 * @lun: SCSI Logical Unit Number
1014 * Description: Looks up the scsi_device with the specified @lun for a given
1015 * @starget. The returned scsi_device does not have an additional
1016 * reference. You must hold the host's host_lock over this call and
1017 * any access to the returned scsi_device.
1019 * Note: The only reason why drivers should 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_by_target instead.
1023 struct scsi_device *__scsi_device_lookup_by_target(struct scsi_target *starget,
1026 struct scsi_device *sdev;
1028 list_for_each_entry(sdev, &starget->devices, same_target_siblings) {
1029 if (sdev->lun ==lun)
1035 EXPORT_SYMBOL(__scsi_device_lookup_by_target);
1038 * scsi_device_lookup_by_target - find a device given the target
1039 * @starget: SCSI target pointer
1040 * @lun: SCSI Logical Unit Number
1042 * Description: Looks up the scsi_device with the specified @channel, @id, @lun
1043 * for a given host. The returned scsi_device has an additional reference that
1044 * needs to be released with scsi_device_put once you're done with it.
1046 struct scsi_device *scsi_device_lookup_by_target(struct scsi_target *starget,
1049 struct scsi_device *sdev;
1050 struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
1051 unsigned long flags;
1053 spin_lock_irqsave(shost->host_lock, flags);
1054 sdev = __scsi_device_lookup_by_target(starget, lun);
1055 if (sdev && scsi_device_get(sdev))
1057 spin_unlock_irqrestore(shost->host_lock, flags);
1061 EXPORT_SYMBOL(scsi_device_lookup_by_target);
1064 * __scsi_device_lookup - find a device given the host (UNLOCKED)
1065 * @shost: SCSI host pointer
1066 * @channel: SCSI channel (zero if only one channel)
1067 * @id: SCSI target number (physical unit number)
1068 * @lun: SCSI Logical Unit Number
1070 * Description: Looks up the scsi_device with the specified @channel, @id, @lun
1071 * for a given host. The returned scsi_device does not have an additional
1072 * reference. You must hold the host's host_lock over this call and any access
1073 * to the returned scsi_device.
1075 * Note: The only reason why drivers would want to use this is because
1076 * they need to access the device list in irq context. Otherwise you
1077 * really want to use scsi_device_lookup instead.
1079 struct scsi_device *__scsi_device_lookup(struct Scsi_Host *shost,
1080 uint channel, uint id, uint lun)
1082 struct scsi_device *sdev;
1084 list_for_each_entry(sdev, &shost->__devices, siblings) {
1085 if (sdev->channel == channel && sdev->id == id &&
1092 EXPORT_SYMBOL(__scsi_device_lookup);
1095 * scsi_device_lookup - find a device given the host
1096 * @shost: SCSI host pointer
1097 * @channel: SCSI channel (zero if only one channel)
1098 * @id: SCSI target number (physical unit number)
1099 * @lun: SCSI Logical Unit Number
1101 * Description: Looks up the scsi_device with the specified @channel, @id, @lun
1102 * for a given host. The returned scsi_device has an additional reference that
1103 * needs to be released with scsi_device_put once you're done with it.
1105 struct scsi_device *scsi_device_lookup(struct Scsi_Host *shost,
1106 uint channel, uint id, uint lun)
1108 struct scsi_device *sdev;
1109 unsigned long flags;
1111 spin_lock_irqsave(shost->host_lock, flags);
1112 sdev = __scsi_device_lookup(shost, channel, id, lun);
1113 if (sdev && scsi_device_get(sdev))
1115 spin_unlock_irqrestore(shost->host_lock, flags);
1119 EXPORT_SYMBOL(scsi_device_lookup);
1121 MODULE_DESCRIPTION("SCSI core");
1122 MODULE_LICENSE("GPL");
1124 module_param(scsi_logging_level, int, S_IRUGO|S_IWUSR);
1125 MODULE_PARM_DESC(scsi_logging_level, "a bit mask of logging levels");
1127 static int __init init_scsi(void)
1131 error = scsi_init_queue();
1134 error = scsi_init_procfs();
1137 error = scsi_init_devinfo();
1139 goto cleanup_procfs;
1140 error = scsi_init_hosts();
1142 goto cleanup_devlist;
1143 error = scsi_init_sysctl();
1146 error = scsi_sysfs_register();
1148 goto cleanup_sysctl;
1150 scsi_netlink_init();
1152 printk(KERN_NOTICE "SCSI subsystem initialized\n");
1160 scsi_exit_devinfo();
1165 printk(KERN_ERR "SCSI subsystem failed to initialize, error = %d\n",
1170 static void __exit exit_scsi(void)
1172 scsi_netlink_exit();
1173 scsi_sysfs_unregister();
1176 scsi_exit_devinfo();
1181 subsys_initcall(init_scsi);
1182 module_exit(exit_scsi);