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 #define CREATE_TRACE_POINTS
71 #include <trace/events/scsi.h>
73 static void scsi_done(struct scsi_cmnd *cmd);
76 * Definitions and constants.
79 #define MIN_RESET_DELAY (2*HZ)
81 /* Do not call reset on error if we just did a reset within 15 sec. */
82 #define MIN_RESET_PERIOD (15*HZ)
85 * Note - the initial logging level can be set here to log events at boot time.
86 * After the system is up, you may enable logging via the /proc interface.
88 unsigned int scsi_logging_level;
89 #if defined(CONFIG_SCSI_LOGGING)
90 EXPORT_SYMBOL(scsi_logging_level);
93 /* sd, scsi core and power management need to coordinate flushing async actions */
94 LIST_HEAD(scsi_sd_probe_domain);
95 EXPORT_SYMBOL(scsi_sd_probe_domain);
97 /* NB: These are exposed through /proc/scsi/scsi and form part of the ABI.
98 * You may not alter any existing entry (although adding new ones is
99 * encouraged once assigned by ANSI/INCITS T10
101 static const char *const scsi_device_types[] = {
124 * scsi_device_type - Return 17 char string indicating device type.
125 * @type: type number to look up
128 const char * scsi_device_type(unsigned type)
131 return "Well-known LUN ";
134 if (type >= ARRAY_SIZE(scsi_device_types))
136 return scsi_device_types[type];
139 EXPORT_SYMBOL(scsi_device_type);
141 struct scsi_host_cmd_pool {
142 struct kmem_cache *cmd_slab;
143 struct kmem_cache *sense_slab;
147 unsigned int slab_flags;
151 static struct scsi_host_cmd_pool scsi_cmd_pool = {
152 .cmd_name = "scsi_cmd_cache",
153 .sense_name = "scsi_sense_cache",
154 .slab_flags = SLAB_HWCACHE_ALIGN,
157 static struct scsi_host_cmd_pool scsi_cmd_dma_pool = {
158 .cmd_name = "scsi_cmd_cache(DMA)",
159 .sense_name = "scsi_sense_cache(DMA)",
160 .slab_flags = SLAB_HWCACHE_ALIGN|SLAB_CACHE_DMA,
161 .gfp_mask = __GFP_DMA,
164 static DEFINE_MUTEX(host_cmd_pool_mutex);
167 * scsi_pool_alloc_command - internal function to get a fully allocated command
168 * @pool: slab pool to allocate the command from
169 * @gfp_mask: mask for the allocation
171 * Returns a fully allocated command (with the allied sense buffer) or
174 static struct scsi_cmnd *
175 scsi_pool_alloc_command(struct scsi_host_cmd_pool *pool, gfp_t gfp_mask)
177 struct scsi_cmnd *cmd;
179 cmd = kmem_cache_zalloc(pool->cmd_slab, gfp_mask | pool->gfp_mask);
183 cmd->sense_buffer = kmem_cache_alloc(pool->sense_slab,
184 gfp_mask | pool->gfp_mask);
185 if (!cmd->sense_buffer) {
186 kmem_cache_free(pool->cmd_slab, cmd);
194 * scsi_pool_free_command - internal function to release a command
195 * @pool: slab pool to allocate the command from
196 * @cmd: command to release
198 * the command must previously have been allocated by
199 * scsi_pool_alloc_command.
202 scsi_pool_free_command(struct scsi_host_cmd_pool *pool,
203 struct scsi_cmnd *cmd)
206 kmem_cache_free(scsi_sdb_cache, cmd->prot_sdb);
208 kmem_cache_free(pool->sense_slab, cmd->sense_buffer);
209 kmem_cache_free(pool->cmd_slab, cmd);
213 * scsi_host_alloc_command - internal function to allocate command
214 * @shost: SCSI host whose pool to allocate from
215 * @gfp_mask: mask for the allocation
217 * Returns a fully allocated command with sense buffer and protection
218 * data buffer (where applicable) or NULL on failure
220 static struct scsi_cmnd *
221 scsi_host_alloc_command(struct Scsi_Host *shost, gfp_t gfp_mask)
223 struct scsi_cmnd *cmd;
225 cmd = scsi_pool_alloc_command(shost->cmd_pool, gfp_mask);
229 if (scsi_host_get_prot(shost) >= SHOST_DIX_TYPE0_PROTECTION) {
230 cmd->prot_sdb = kmem_cache_zalloc(scsi_sdb_cache, gfp_mask);
232 if (!cmd->prot_sdb) {
233 scsi_pool_free_command(shost->cmd_pool, cmd);
242 * __scsi_get_command - Allocate a struct scsi_cmnd
243 * @shost: host to transmit command
244 * @gfp_mask: allocation mask
246 * Description: allocate a struct scsi_cmd from host's slab, recycling from the
247 * host's free_list if necessary.
249 struct scsi_cmnd *__scsi_get_command(struct Scsi_Host *shost, gfp_t gfp_mask)
251 struct scsi_cmnd *cmd = scsi_host_alloc_command(shost, gfp_mask);
253 if (unlikely(!cmd)) {
256 spin_lock_irqsave(&shost->free_list_lock, flags);
257 if (likely(!list_empty(&shost->free_list))) {
258 cmd = list_entry(shost->free_list.next,
259 struct scsi_cmnd, list);
260 list_del_init(&cmd->list);
262 spin_unlock_irqrestore(&shost->free_list_lock, flags);
267 buf = cmd->sense_buffer;
268 prot = cmd->prot_sdb;
270 memset(cmd, 0, sizeof(*cmd));
272 cmd->sense_buffer = buf;
273 cmd->prot_sdb = prot;
279 EXPORT_SYMBOL_GPL(__scsi_get_command);
282 * scsi_get_command - Allocate and setup a scsi command block
283 * @dev: parent scsi device
284 * @gfp_mask: allocator flags
286 * Returns: The allocated scsi command structure.
288 struct scsi_cmnd *scsi_get_command(struct scsi_device *dev, gfp_t gfp_mask)
290 struct scsi_cmnd *cmd;
292 /* Bail if we can't get a reference to the device */
293 if (!get_device(&dev->sdev_gendev))
296 cmd = __scsi_get_command(dev->host, gfp_mask);
298 if (likely(cmd != NULL)) {
302 INIT_LIST_HEAD(&cmd->list);
303 spin_lock_irqsave(&dev->list_lock, flags);
304 list_add_tail(&cmd->list, &dev->cmd_list);
305 spin_unlock_irqrestore(&dev->list_lock, flags);
306 cmd->jiffies_at_alloc = jiffies;
308 put_device(&dev->sdev_gendev);
312 EXPORT_SYMBOL(scsi_get_command);
315 * __scsi_put_command - Free a struct scsi_cmnd
317 * @cmd: Command to free
318 * @dev: parent scsi device
320 void __scsi_put_command(struct Scsi_Host *shost, struct scsi_cmnd *cmd,
325 /* changing locks here, don't need to restore the irq state */
326 spin_lock_irqsave(&shost->free_list_lock, flags);
327 if (unlikely(list_empty(&shost->free_list))) {
328 list_add(&cmd->list, &shost->free_list);
331 spin_unlock_irqrestore(&shost->free_list_lock, flags);
333 if (likely(cmd != NULL))
334 scsi_pool_free_command(shost->cmd_pool, cmd);
338 EXPORT_SYMBOL(__scsi_put_command);
341 * scsi_put_command - Free a scsi command block
342 * @cmd: command block to free
346 * Notes: The command must not belong to any lists.
348 void scsi_put_command(struct scsi_cmnd *cmd)
350 struct scsi_device *sdev = cmd->device;
353 /* serious error if the command hasn't come from a device list */
354 spin_lock_irqsave(&cmd->device->list_lock, flags);
355 BUG_ON(list_empty(&cmd->list));
356 list_del_init(&cmd->list);
357 spin_unlock_irqrestore(&cmd->device->list_lock, flags);
359 __scsi_put_command(cmd->device->host, cmd, &sdev->sdev_gendev);
361 EXPORT_SYMBOL(scsi_put_command);
363 static struct scsi_host_cmd_pool *scsi_get_host_cmd_pool(gfp_t gfp_mask)
365 struct scsi_host_cmd_pool *retval = NULL, *pool;
367 * Select a command slab for this host and create it if not
370 mutex_lock(&host_cmd_pool_mutex);
371 pool = (gfp_mask & __GFP_DMA) ? &scsi_cmd_dma_pool :
374 pool->cmd_slab = kmem_cache_create(pool->cmd_name,
375 sizeof(struct scsi_cmnd), 0,
376 pool->slab_flags, NULL);
380 pool->sense_slab = kmem_cache_create(pool->sense_name,
381 SCSI_SENSE_BUFFERSIZE, 0,
382 pool->slab_flags, NULL);
383 if (!pool->sense_slab) {
384 kmem_cache_destroy(pool->cmd_slab);
392 mutex_unlock(&host_cmd_pool_mutex);
396 static void scsi_put_host_cmd_pool(gfp_t gfp_mask)
398 struct scsi_host_cmd_pool *pool;
400 mutex_lock(&host_cmd_pool_mutex);
401 pool = (gfp_mask & __GFP_DMA) ? &scsi_cmd_dma_pool :
404 * This may happen if a driver has a mismatched get and put
405 * of the command pool; the driver should be implicated in
408 BUG_ON(pool->users == 0);
410 if (!--pool->users) {
411 kmem_cache_destroy(pool->cmd_slab);
412 kmem_cache_destroy(pool->sense_slab);
414 mutex_unlock(&host_cmd_pool_mutex);
418 * scsi_allocate_command - get a fully allocated SCSI command
419 * @gfp_mask: allocation mask
421 * This function is for use outside of the normal host based pools.
422 * It allocates the relevant command and takes an additional reference
423 * on the pool it used. This function *must* be paired with
424 * scsi_free_command which also has the identical mask, otherwise the
425 * free pool counts will eventually go wrong and you'll trigger a bug.
427 * This function should *only* be used by drivers that need a static
428 * command allocation at start of day for internal functions.
430 struct scsi_cmnd *scsi_allocate_command(gfp_t gfp_mask)
432 struct scsi_host_cmd_pool *pool = scsi_get_host_cmd_pool(gfp_mask);
437 return scsi_pool_alloc_command(pool, gfp_mask);
439 EXPORT_SYMBOL(scsi_allocate_command);
442 * scsi_free_command - free a command allocated by scsi_allocate_command
443 * @gfp_mask: mask used in the original allocation
444 * @cmd: command to free
446 * Note: using the original allocation mask is vital because that's
447 * what determines which command pool we use to free the command. Any
448 * mismatch will cause the system to BUG eventually.
450 void scsi_free_command(gfp_t gfp_mask, struct scsi_cmnd *cmd)
452 struct scsi_host_cmd_pool *pool = scsi_get_host_cmd_pool(gfp_mask);
455 * this could trigger if the mask to scsi_allocate_command
456 * doesn't match this mask. Otherwise we're guaranteed that this
457 * succeeds because scsi_allocate_command must have taken a reference
462 scsi_pool_free_command(pool, cmd);
464 * scsi_put_host_cmd_pool is called twice; once to release the
465 * reference we took above, and once to release the reference
466 * originally taken by scsi_allocate_command
468 scsi_put_host_cmd_pool(gfp_mask);
469 scsi_put_host_cmd_pool(gfp_mask);
471 EXPORT_SYMBOL(scsi_free_command);
474 * scsi_setup_command_freelist - Setup the command freelist for a scsi host.
475 * @shost: host to allocate the freelist for.
477 * Description: The command freelist protects against system-wide out of memory
478 * deadlock by preallocating one SCSI command structure for each host, so the
479 * system can always write to a swap file on a device associated with that host.
483 int scsi_setup_command_freelist(struct Scsi_Host *shost)
485 struct scsi_cmnd *cmd;
486 const gfp_t gfp_mask = shost->unchecked_isa_dma ? GFP_DMA : GFP_KERNEL;
488 spin_lock_init(&shost->free_list_lock);
489 INIT_LIST_HEAD(&shost->free_list);
491 shost->cmd_pool = scsi_get_host_cmd_pool(gfp_mask);
493 if (!shost->cmd_pool)
497 * Get one backup command for this host.
499 cmd = scsi_host_alloc_command(shost, gfp_mask);
501 scsi_put_host_cmd_pool(gfp_mask);
502 shost->cmd_pool = NULL;
505 list_add(&cmd->list, &shost->free_list);
510 * scsi_destroy_command_freelist - Release the command freelist for a scsi host.
511 * @shost: host whose freelist is going to be destroyed
513 void scsi_destroy_command_freelist(struct Scsi_Host *shost)
516 * If cmd_pool is NULL the free list was not initialized, so
517 * do not attempt to release resources.
519 if (!shost->cmd_pool)
522 while (!list_empty(&shost->free_list)) {
523 struct scsi_cmnd *cmd;
525 cmd = list_entry(shost->free_list.next, struct scsi_cmnd, list);
526 list_del_init(&cmd->list);
527 scsi_pool_free_command(shost->cmd_pool, cmd);
529 shost->cmd_pool = NULL;
530 scsi_put_host_cmd_pool(shost->unchecked_isa_dma ? GFP_DMA : GFP_KERNEL);
533 #ifdef CONFIG_SCSI_LOGGING
534 void scsi_log_send(struct scsi_cmnd *cmd)
539 * If ML QUEUE log level is greater than or equal to:
541 * 1: nothing (match completion)
543 * 2: log opcode + command of all commands
545 * 3: same as 2 plus dump cmd address
547 * 4: same as 3 plus dump extra junk
549 if (unlikely(scsi_logging_level)) {
550 level = SCSI_LOG_LEVEL(SCSI_LOG_MLQUEUE_SHIFT,
551 SCSI_LOG_MLQUEUE_BITS);
553 scmd_printk(KERN_INFO, cmd, "Send: ");
555 printk("0x%p ", cmd);
557 scsi_print_command(cmd);
559 printk(KERN_INFO "buffer = 0x%p, bufflen = %d,"
560 " queuecommand 0x%p\n",
561 scsi_sglist(cmd), scsi_bufflen(cmd),
562 cmd->device->host->hostt->queuecommand);
569 void scsi_log_completion(struct scsi_cmnd *cmd, int disposition)
574 * If ML COMPLETE log level is greater than or equal to:
576 * 1: log disposition, result, opcode + command, and conditionally
577 * sense data for failures or non SUCCESS dispositions.
579 * 2: same as 1 but for all command completions.
581 * 3: same as 2 plus dump cmd address
583 * 4: same as 3 plus dump extra junk
585 if (unlikely(scsi_logging_level)) {
586 level = SCSI_LOG_LEVEL(SCSI_LOG_MLCOMPLETE_SHIFT,
587 SCSI_LOG_MLCOMPLETE_BITS);
588 if (((level > 0) && (cmd->result || disposition != SUCCESS)) ||
590 scmd_printk(KERN_INFO, cmd, "Done: ");
592 printk("0x%p ", cmd);
594 * Dump truncated values, so we usually fit within
597 switch (disposition) {
612 * If called via scsi_times_out.
619 scsi_print_result(cmd);
620 scsi_print_command(cmd);
621 if (status_byte(cmd->result) & CHECK_CONDITION)
622 scsi_print_sense("", cmd);
624 scmd_printk(KERN_INFO, cmd,
625 "scsi host busy %d failed %d\n",
626 cmd->device->host->host_busy,
627 cmd->device->host->host_failed);
634 * scsi_cmd_get_serial - Assign a serial number to a command
635 * @host: the scsi host
636 * @cmd: command to assign serial number to
638 * Description: a serial number identifies a request for error recovery
639 * and debugging purposes. Protected by the Host_Lock of host.
641 void scsi_cmd_get_serial(struct Scsi_Host *host, struct scsi_cmnd *cmd)
643 cmd->serial_number = host->cmd_serial_number++;
644 if (cmd->serial_number == 0)
645 cmd->serial_number = host->cmd_serial_number++;
647 EXPORT_SYMBOL(scsi_cmd_get_serial);
650 * scsi_dispatch_command - Dispatch a command to the low-level driver.
651 * @cmd: command block we are dispatching.
653 * Return: nonzero return request was rejected and device's queue needs to be
656 int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
658 struct Scsi_Host *host = cmd->device->host;
659 unsigned long timeout;
662 atomic_inc(&cmd->device->iorequest_cnt);
664 /* check if the device is still usable */
665 if (unlikely(cmd->device->sdev_state == SDEV_DEL)) {
666 /* in SDEV_DEL we error all commands. DID_NO_CONNECT
667 * returns an immediate error upwards, and signals
668 * that the device is no longer present */
669 cmd->result = DID_NO_CONNECT << 16;
671 /* return 0 (because the command has been processed) */
675 /* Check to see if the scsi lld made this device blocked. */
676 if (unlikely(scsi_device_blocked(cmd->device))) {
678 * in blocked state, the command is just put back on
679 * the device queue. The suspend state has already
680 * blocked the queue so future requests should not
681 * occur until the device transitions out of the
685 scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
687 SCSI_LOG_MLQUEUE(3, printk("queuecommand : device blocked \n"));
690 * NOTE: rtn is still zero here because we don't need the
691 * queue to be plugged on return (it's already stopped)
697 * If SCSI-2 or lower, store the LUN value in cmnd.
699 if (cmd->device->scsi_level <= SCSI_2 &&
700 cmd->device->scsi_level != SCSI_UNKNOWN) {
701 cmd->cmnd[1] = (cmd->cmnd[1] & 0x1f) |
702 (cmd->device->lun << 5 & 0xe0);
706 * We will wait MIN_RESET_DELAY clock ticks after the last reset so
707 * we can avoid the drive not being ready.
709 timeout = host->last_reset + MIN_RESET_DELAY;
711 if (host->resetting && time_before(jiffies, timeout)) {
712 int ticks_remaining = timeout - jiffies;
714 * NOTE: This may be executed from within an interrupt
715 * handler! This is bad, but for now, it'll do. The irq
716 * level of the interrupt handler has been masked out by the
717 * platform dependent interrupt handling code already, so the
718 * sti() here will not cause another call to the SCSI host's
719 * interrupt handler (assuming there is one irq-level per
722 while (--ticks_remaining >= 0)
723 mdelay(1 + 999 / HZ);
730 * Before we queue this command, check if the command
731 * length exceeds what the host adapter can handle.
733 if (cmd->cmd_len > cmd->device->host->max_cmd_len) {
735 printk("queuecommand : command too long. "
736 "cdb_size=%d host->max_cmd_len=%d\n",
737 cmd->cmd_len, cmd->device->host->max_cmd_len));
738 cmd->result = (DID_ABORT << 16);
744 if (unlikely(host->shost_state == SHOST_DEL)) {
745 cmd->result = (DID_NO_CONNECT << 16);
748 trace_scsi_dispatch_cmd_start(cmd);
749 cmd->scsi_done = scsi_done;
750 rtn = host->hostt->queuecommand(host, cmd);
754 trace_scsi_dispatch_cmd_error(cmd, rtn);
755 if (rtn != SCSI_MLQUEUE_DEVICE_BUSY &&
756 rtn != SCSI_MLQUEUE_TARGET_BUSY)
757 rtn = SCSI_MLQUEUE_HOST_BUSY;
759 scsi_queue_insert(cmd, rtn);
762 printk("queuecommand : request rejected\n"));
766 SCSI_LOG_MLQUEUE(3, printk("leaving scsi_dispatch_cmnd()\n"));
771 * scsi_done - Enqueue the finished SCSI command into the done queue.
772 * @cmd: The SCSI Command for which a low-level device driver (LLDD) gives
773 * ownership back to SCSI Core -- i.e. the LLDD has finished with it.
775 * Description: This function is the mid-level's (SCSI Core) interrupt routine,
776 * which regains ownership of the SCSI command (de facto) from a LLDD, and
777 * enqueues the command to the done queue for further processing.
779 * This is the producer of the done queue who enqueues at the tail.
781 * This function is interrupt context safe.
783 static void scsi_done(struct scsi_cmnd *cmd)
785 trace_scsi_dispatch_cmd_done(cmd);
786 blk_complete_request(cmd->request);
790 * scsi_finish_command - cleanup and pass command back to upper layer
793 * Description: Pass command off to upper layer for finishing of I/O
794 * request, waking processes that are waiting on results,
797 void scsi_finish_command(struct scsi_cmnd *cmd)
799 struct scsi_device *sdev = cmd->device;
800 struct scsi_target *starget = scsi_target(sdev);
801 struct Scsi_Host *shost = sdev->host;
802 struct scsi_driver *drv;
803 unsigned int good_bytes;
805 scsi_device_unbusy(sdev);
808 * Clear the flags which say that the device/host is no longer
809 * capable of accepting new commands. These are set in scsi_queue.c
810 * for both the queue full condition on a device, and for a
811 * host full condition on the host.
813 * XXX(hch): What about locking?
815 shost->host_blocked = 0;
816 starget->target_blocked = 0;
817 sdev->device_blocked = 0;
820 * If we have valid sense information, then some kind of recovery
821 * must have taken place. Make a note of this.
823 if (SCSI_SENSE_VALID(cmd))
824 cmd->result |= (DRIVER_SENSE << 24);
826 SCSI_LOG_MLCOMPLETE(4, sdev_printk(KERN_INFO, sdev,
827 "Notifying upper driver of completion "
828 "(result %x)\n", cmd->result));
830 good_bytes = scsi_bufflen(cmd);
831 if (cmd->request->cmd_type != REQ_TYPE_BLOCK_PC) {
832 int old_good_bytes = good_bytes;
833 drv = scsi_cmd_to_driver(cmd);
835 good_bytes = drv->done(cmd);
837 * USB may not give sense identifying bad sector and
838 * simply return a residue instead, so subtract off the
839 * residue if drv->done() error processing indicates no
840 * change to the completion length.
842 if (good_bytes == old_good_bytes)
843 good_bytes -= scsi_get_resid(cmd);
845 scsi_io_completion(cmd, good_bytes);
847 EXPORT_SYMBOL(scsi_finish_command);
850 * scsi_adjust_queue_depth - Let low level drivers change a device's queue depth
851 * @sdev: SCSI Device in question
852 * @tagged: Do we use tagged queueing (non-0) or do we treat
853 * this device as an untagged device (0)
854 * @tags: Number of tags allowed if tagged queueing enabled,
855 * or number of commands the low level driver can
856 * queue up in non-tagged mode (as per cmd_per_lun).
860 * Lock Status: None held on entry
862 * Notes: Low level drivers may call this at any time and we will do
863 * the right thing depending on whether or not the device is
864 * currently active and whether or not it even has the
865 * command blocks built yet.
867 void scsi_adjust_queue_depth(struct scsi_device *sdev, int tagged, int tags)
872 * refuse to set tagged depth to an unworkable size
877 spin_lock_irqsave(sdev->request_queue->queue_lock, flags);
880 * Check to see if the queue is managed by the block layer.
881 * If it is, and we fail to adjust the depth, exit.
883 * Do not resize the tag map if it is a host wide share bqt,
884 * because the size should be the hosts's can_queue. If there
885 * is more IO than the LLD's can_queue (so there are not enuogh
886 * tags) request_fn's host queue ready check will handle it.
888 if (!sdev->host->bqt) {
889 if (blk_queue_tagged(sdev->request_queue) &&
890 blk_queue_resize_tags(sdev->request_queue, tags) != 0)
894 sdev->queue_depth = tags;
896 case MSG_ORDERED_TAG:
897 sdev->ordered_tags = 1;
898 sdev->simple_tags = 1;
901 sdev->ordered_tags = 0;
902 sdev->simple_tags = 1;
905 sdev_printk(KERN_WARNING, sdev,
906 "scsi_adjust_queue_depth, bad queue type, "
909 sdev->ordered_tags = sdev->simple_tags = 0;
910 sdev->queue_depth = tags;
914 spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
916 EXPORT_SYMBOL(scsi_adjust_queue_depth);
919 * scsi_track_queue_full - track QUEUE_FULL events to adjust queue depth
920 * @sdev: SCSI Device in question
921 * @depth: Current number of outstanding SCSI commands on this device,
922 * not counting the one returned as QUEUE_FULL.
924 * Description: This function will track successive QUEUE_FULL events on a
925 * specific SCSI device to determine if and when there is a
926 * need to adjust the queue depth on the device.
928 * Returns: 0 - No change needed, >0 - Adjust queue depth to this new depth,
929 * -1 - Drop back to untagged operation using host->cmd_per_lun
930 * as the untagged command depth
932 * Lock Status: None held on entry
934 * Notes: Low level drivers may call this at any time and we will do
935 * "The Right Thing." We are interrupt context safe.
937 int scsi_track_queue_full(struct scsi_device *sdev, int depth)
941 * Don't let QUEUE_FULLs on the same
942 * jiffies count, they could all be from
945 if ((jiffies >> 4) == (sdev->last_queue_full_time >> 4))
948 sdev->last_queue_full_time = jiffies;
949 if (sdev->last_queue_full_depth != depth) {
950 sdev->last_queue_full_count = 1;
951 sdev->last_queue_full_depth = depth;
953 sdev->last_queue_full_count++;
956 if (sdev->last_queue_full_count <= 10)
958 if (sdev->last_queue_full_depth < 8) {
959 /* Drop back to untagged */
960 scsi_adjust_queue_depth(sdev, 0, sdev->host->cmd_per_lun);
964 if (sdev->ordered_tags)
965 scsi_adjust_queue_depth(sdev, MSG_ORDERED_TAG, depth);
967 scsi_adjust_queue_depth(sdev, MSG_SIMPLE_TAG, depth);
970 EXPORT_SYMBOL(scsi_track_queue_full);
973 * scsi_vpd_inquiry - Request a device provide us with a VPD page
974 * @sdev: The device to ask
975 * @buffer: Where to put the result
976 * @page: Which Vital Product Data to return
977 * @len: The length of the buffer
979 * This is an internal helper function. You probably want to use
980 * scsi_get_vpd_page instead.
982 * Returns 0 on success or a negative error number.
984 static int scsi_vpd_inquiry(struct scsi_device *sdev, unsigned char *buffer,
985 u8 page, unsigned len)
988 unsigned char cmd[16];
991 cmd[1] = 1; /* EVPD */
995 cmd[5] = 0; /* Control byte */
998 * I'm not convinced we need to try quite this hard to get VPD, but
999 * all the existing users tried this hard.
1001 result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer,
1002 len, NULL, 30 * HZ, 3, NULL);
1006 /* Sanity check that we got the page back that we asked for */
1007 if (buffer[1] != page)
1014 * scsi_get_vpd_page - Get Vital Product Data from a SCSI device
1015 * @sdev: The device to ask
1016 * @page: Which Vital Product Data to return
1017 * @buf: where to store the VPD
1018 * @buf_len: number of bytes in the VPD buffer area
1020 * SCSI devices may optionally supply Vital Product Data. Each 'page'
1021 * of VPD is defined in the appropriate SCSI document (eg SPC, SBC).
1022 * If the device supports this VPD page, this routine returns a pointer
1023 * to a buffer containing the data from that page. The caller is
1024 * responsible for calling kfree() on this pointer when it is no longer
1025 * needed. If we cannot retrieve the VPD page this routine returns %NULL.
1027 int scsi_get_vpd_page(struct scsi_device *sdev, u8 page, unsigned char *buf,
1032 /* Ask for all the pages supported by this device */
1033 result = scsi_vpd_inquiry(sdev, buf, 0, buf_len);
1037 /* If the user actually wanted this page, we can skip the rest */
1041 for (i = 0; i < min((int)buf[3], buf_len - 4); i++)
1042 if (buf[i + 4] == page)
1045 if (i < buf[3] && i >= buf_len - 4)
1046 /* ran off the end of the buffer, give us benefit of doubt */
1048 /* The device claims it doesn't support the requested page */
1052 result = scsi_vpd_inquiry(sdev, buf, page, buf_len);
1061 EXPORT_SYMBOL_GPL(scsi_get_vpd_page);
1064 * scsi_device_get - get an additional reference to a scsi_device
1065 * @sdev: device to get a reference to
1067 * Description: Gets a reference to the scsi_device and increments the use count
1068 * of the underlying LLDD module. You must hold host_lock of the
1069 * parent Scsi_Host or already have a reference when calling this.
1071 int scsi_device_get(struct scsi_device *sdev)
1073 if (sdev->sdev_state == SDEV_DEL)
1075 if (!get_device(&sdev->sdev_gendev))
1077 /* We can fail this if we're doing SCSI operations
1078 * from module exit (like cache flush) */
1079 try_module_get(sdev->host->hostt->module);
1083 EXPORT_SYMBOL(scsi_device_get);
1086 * scsi_device_put - release a reference to a scsi_device
1087 * @sdev: device to release a reference on.
1089 * Description: Release a reference to the scsi_device and decrements the use
1090 * count of the underlying LLDD module. The device is freed once the last
1093 void scsi_device_put(struct scsi_device *sdev)
1095 #ifdef CONFIG_MODULE_UNLOAD
1096 struct module *module = sdev->host->hostt->module;
1098 /* The module refcount will be zero if scsi_device_get()
1099 * was called from a module removal routine */
1100 if (module && module_refcount(module) != 0)
1103 put_device(&sdev->sdev_gendev);
1105 EXPORT_SYMBOL(scsi_device_put);
1107 /* helper for shost_for_each_device, see that for documentation */
1108 struct scsi_device *__scsi_iterate_devices(struct Scsi_Host *shost,
1109 struct scsi_device *prev)
1111 struct list_head *list = (prev ? &prev->siblings : &shost->__devices);
1112 struct scsi_device *next = NULL;
1113 unsigned long flags;
1115 spin_lock_irqsave(shost->host_lock, flags);
1116 while (list->next != &shost->__devices) {
1117 next = list_entry(list->next, struct scsi_device, siblings);
1118 /* skip devices that we can't get a reference to */
1119 if (!scsi_device_get(next))
1124 spin_unlock_irqrestore(shost->host_lock, flags);
1127 scsi_device_put(prev);
1130 EXPORT_SYMBOL(__scsi_iterate_devices);
1133 * starget_for_each_device - helper to walk all devices of a target
1134 * @starget: target whose devices we want to iterate over.
1135 * @data: Opaque passed to each function call.
1136 * @fn: Function to call on each device
1138 * This traverses over each device of @starget. The devices have
1139 * a reference that must be released by scsi_host_put when breaking
1142 void starget_for_each_device(struct scsi_target *starget, void *data,
1143 void (*fn)(struct scsi_device *, void *))
1145 struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
1146 struct scsi_device *sdev;
1148 shost_for_each_device(sdev, shost) {
1149 if ((sdev->channel == starget->channel) &&
1150 (sdev->id == starget->id))
1154 EXPORT_SYMBOL(starget_for_each_device);
1157 * __starget_for_each_device - helper to walk all devices of a target (UNLOCKED)
1158 * @starget: target whose devices we want to iterate over.
1159 * @data: parameter for callback @fn()
1160 * @fn: callback function that is invoked for each device
1162 * This traverses over each device of @starget. It does _not_
1163 * take a reference on the scsi_device, so the whole loop must be
1164 * protected by shost->host_lock.
1166 * Note: The only reason why drivers would want to use this is because
1167 * they need to access the device list in irq context. Otherwise you
1168 * really want to use starget_for_each_device instead.
1170 void __starget_for_each_device(struct scsi_target *starget, void *data,
1171 void (*fn)(struct scsi_device *, void *))
1173 struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
1174 struct scsi_device *sdev;
1176 __shost_for_each_device(sdev, shost) {
1177 if ((sdev->channel == starget->channel) &&
1178 (sdev->id == starget->id))
1182 EXPORT_SYMBOL(__starget_for_each_device);
1185 * __scsi_device_lookup_by_target - find a device given the target (UNLOCKED)
1186 * @starget: SCSI target pointer
1187 * @lun: SCSI Logical Unit Number
1189 * Description: Looks up the scsi_device with the specified @lun for a given
1190 * @starget. The returned scsi_device does not have an additional
1191 * reference. You must hold the host's host_lock over this call and
1192 * any access to the returned scsi_device. A scsi_device in state
1193 * SDEV_DEL is skipped.
1195 * Note: The only reason why drivers should use this is because
1196 * they need to access the device list in irq context. Otherwise you
1197 * really want to use scsi_device_lookup_by_target instead.
1199 struct scsi_device *__scsi_device_lookup_by_target(struct scsi_target *starget,
1202 struct scsi_device *sdev;
1204 list_for_each_entry(sdev, &starget->devices, same_target_siblings) {
1205 if (sdev->sdev_state == SDEV_DEL)
1207 if (sdev->lun ==lun)
1213 EXPORT_SYMBOL(__scsi_device_lookup_by_target);
1216 * scsi_device_lookup_by_target - find a device given the target
1217 * @starget: SCSI target pointer
1218 * @lun: SCSI Logical Unit Number
1220 * Description: Looks up the scsi_device with the specified @lun for a given
1221 * @starget. The returned scsi_device has an additional reference that
1222 * needs to be released with scsi_device_put once you're done with it.
1224 struct scsi_device *scsi_device_lookup_by_target(struct scsi_target *starget,
1227 struct scsi_device *sdev;
1228 struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
1229 unsigned long flags;
1231 spin_lock_irqsave(shost->host_lock, flags);
1232 sdev = __scsi_device_lookup_by_target(starget, lun);
1233 if (sdev && scsi_device_get(sdev))
1235 spin_unlock_irqrestore(shost->host_lock, flags);
1239 EXPORT_SYMBOL(scsi_device_lookup_by_target);
1242 * __scsi_device_lookup - find a device given the host (UNLOCKED)
1243 * @shost: SCSI host pointer
1244 * @channel: SCSI channel (zero if only one channel)
1245 * @id: SCSI target number (physical unit number)
1246 * @lun: SCSI Logical Unit Number
1248 * Description: Looks up the scsi_device with the specified @channel, @id, @lun
1249 * for a given host. The returned scsi_device does not have an additional
1250 * reference. You must hold the host's host_lock over this call and any access
1251 * to the returned scsi_device.
1253 * Note: The only reason why drivers would want to use this is because
1254 * they need to access the device list in irq context. Otherwise you
1255 * really want to use scsi_device_lookup instead.
1257 struct scsi_device *__scsi_device_lookup(struct Scsi_Host *shost,
1258 uint channel, uint id, uint lun)
1260 struct scsi_device *sdev;
1262 list_for_each_entry(sdev, &shost->__devices, siblings) {
1263 if (sdev->channel == channel && sdev->id == id &&
1270 EXPORT_SYMBOL(__scsi_device_lookup);
1273 * scsi_device_lookup - find a device given the host
1274 * @shost: SCSI host pointer
1275 * @channel: SCSI channel (zero if only one channel)
1276 * @id: SCSI target number (physical unit number)
1277 * @lun: SCSI Logical Unit Number
1279 * Description: Looks up the scsi_device with the specified @channel, @id, @lun
1280 * for a given host. The returned scsi_device has an additional reference that
1281 * needs to be released with scsi_device_put once you're done with it.
1283 struct scsi_device *scsi_device_lookup(struct Scsi_Host *shost,
1284 uint channel, uint id, uint lun)
1286 struct scsi_device *sdev;
1287 unsigned long flags;
1289 spin_lock_irqsave(shost->host_lock, flags);
1290 sdev = __scsi_device_lookup(shost, channel, id, lun);
1291 if (sdev && scsi_device_get(sdev))
1293 spin_unlock_irqrestore(shost->host_lock, flags);
1297 EXPORT_SYMBOL(scsi_device_lookup);
1299 MODULE_DESCRIPTION("SCSI core");
1300 MODULE_LICENSE("GPL");
1302 module_param(scsi_logging_level, int, S_IRUGO|S_IWUSR);
1303 MODULE_PARM_DESC(scsi_logging_level, "a bit mask of logging levels");
1305 static int __init init_scsi(void)
1309 error = scsi_init_queue();
1312 error = scsi_init_procfs();
1315 error = scsi_init_devinfo();
1317 goto cleanup_procfs;
1318 error = scsi_init_hosts();
1320 goto cleanup_devlist;
1321 error = scsi_init_sysctl();
1324 error = scsi_sysfs_register();
1326 goto cleanup_sysctl;
1328 scsi_netlink_init();
1330 printk(KERN_NOTICE "SCSI subsystem initialized\n");
1338 scsi_exit_devinfo();
1343 printk(KERN_ERR "SCSI subsystem failed to initialize, error = %d\n",
1348 static void __exit exit_scsi(void)
1350 scsi_netlink_exit();
1351 scsi_sysfs_unregister();
1354 scsi_exit_devinfo();
1359 subsys_initcall(init_scsi);
1360 module_exit(exit_scsi);