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 * Note - the initial logging level can be set here to log events at boot time.
83 * After the system is up, you may enable logging via the /proc interface.
85 unsigned int scsi_logging_level;
86 #if defined(CONFIG_SCSI_LOGGING)
87 EXPORT_SYMBOL(scsi_logging_level);
90 /* NB: These are exposed through /proc/scsi/scsi and form part of the ABI.
91 * You may not alter any existing entry (although adding new ones is
92 * encouraged once assigned by ANSI/INCITS T10
94 static const char *const scsi_device_types[] = {
117 * scsi_device_type - Return 17 char string indicating device type.
118 * @type: type number to look up
121 const char * scsi_device_type(unsigned type)
124 return "Well-known LUN ";
127 if (type >= ARRAY_SIZE(scsi_device_types))
129 return scsi_device_types[type];
132 EXPORT_SYMBOL(scsi_device_type);
134 struct scsi_host_cmd_pool {
135 struct kmem_cache *cmd_slab;
136 struct kmem_cache *sense_slab;
140 unsigned int slab_flags;
144 static struct scsi_host_cmd_pool scsi_cmd_pool = {
145 .cmd_name = "scsi_cmd_cache",
146 .sense_name = "scsi_sense_cache",
147 .slab_flags = SLAB_HWCACHE_ALIGN,
150 static struct scsi_host_cmd_pool scsi_cmd_dma_pool = {
151 .cmd_name = "scsi_cmd_cache(DMA)",
152 .sense_name = "scsi_sense_cache(DMA)",
153 .slab_flags = SLAB_HWCACHE_ALIGN|SLAB_CACHE_DMA,
154 .gfp_mask = __GFP_DMA,
157 static DEFINE_MUTEX(host_cmd_pool_mutex);
160 * scsi_pool_alloc_command - internal function to get a fully allocated command
161 * @pool: slab pool to allocate the command from
162 * @gfp_mask: mask for the allocation
164 * Returns a fully allocated command (with the allied sense buffer) or
167 static struct scsi_cmnd *
168 scsi_pool_alloc_command(struct scsi_host_cmd_pool *pool, gfp_t gfp_mask)
170 struct scsi_cmnd *cmd;
172 cmd = kmem_cache_zalloc(pool->cmd_slab, gfp_mask | pool->gfp_mask);
176 cmd->sense_buffer = kmem_cache_alloc(pool->sense_slab,
177 gfp_mask | pool->gfp_mask);
178 if (!cmd->sense_buffer) {
179 kmem_cache_free(pool->cmd_slab, cmd);
187 * scsi_pool_free_command - internal function to release a command
188 * @pool: slab pool to allocate the command from
189 * @cmd: command to release
191 * the command must previously have been allocated by
192 * scsi_pool_alloc_command.
195 scsi_pool_free_command(struct scsi_host_cmd_pool *pool,
196 struct scsi_cmnd *cmd)
199 kmem_cache_free(scsi_sdb_cache, cmd->prot_sdb);
201 kmem_cache_free(pool->sense_slab, cmd->sense_buffer);
202 kmem_cache_free(pool->cmd_slab, cmd);
206 * scsi_host_alloc_command - internal function to allocate command
207 * @shost: SCSI host whose pool to allocate from
208 * @gfp_mask: mask for the allocation
210 * Returns a fully allocated command with sense buffer and protection
211 * data buffer (where applicable) or NULL on failure
213 static struct scsi_cmnd *
214 scsi_host_alloc_command(struct Scsi_Host *shost, gfp_t gfp_mask)
216 struct scsi_cmnd *cmd;
218 cmd = scsi_pool_alloc_command(shost->cmd_pool, gfp_mask);
222 if (scsi_host_get_prot(shost) >= SHOST_DIX_TYPE0_PROTECTION) {
223 cmd->prot_sdb = kmem_cache_zalloc(scsi_sdb_cache, gfp_mask);
225 if (!cmd->prot_sdb) {
226 scsi_pool_free_command(shost->cmd_pool, cmd);
235 * __scsi_get_command - Allocate a struct scsi_cmnd
236 * @shost: host to transmit command
237 * @gfp_mask: allocation mask
239 * Description: allocate a struct scsi_cmd from host's slab, recycling from the
240 * host's free_list if necessary.
242 struct scsi_cmnd *__scsi_get_command(struct Scsi_Host *shost, gfp_t gfp_mask)
244 struct scsi_cmnd *cmd;
247 cmd = scsi_host_alloc_command(shost, gfp_mask);
249 if (unlikely(!cmd)) {
252 spin_lock_irqsave(&shost->free_list_lock, flags);
253 if (likely(!list_empty(&shost->free_list))) {
254 cmd = list_entry(shost->free_list.next,
255 struct scsi_cmnd, list);
256 list_del_init(&cmd->list);
258 spin_unlock_irqrestore(&shost->free_list_lock, flags);
261 buf = cmd->sense_buffer;
262 memset(cmd, 0, sizeof(*cmd));
263 cmd->sense_buffer = buf;
269 EXPORT_SYMBOL_GPL(__scsi_get_command);
272 * scsi_get_command - Allocate and setup a scsi command block
273 * @dev: parent scsi device
274 * @gfp_mask: allocator flags
276 * Returns: The allocated scsi command structure.
278 struct scsi_cmnd *scsi_get_command(struct scsi_device *dev, gfp_t gfp_mask)
280 struct scsi_cmnd *cmd;
282 /* Bail if we can't get a reference to the device */
283 if (!get_device(&dev->sdev_gendev))
286 cmd = __scsi_get_command(dev->host, gfp_mask);
288 if (likely(cmd != NULL)) {
292 INIT_LIST_HEAD(&cmd->list);
293 spin_lock_irqsave(&dev->list_lock, flags);
294 list_add_tail(&cmd->list, &dev->cmd_list);
295 spin_unlock_irqrestore(&dev->list_lock, flags);
296 cmd->jiffies_at_alloc = jiffies;
298 put_device(&dev->sdev_gendev);
302 EXPORT_SYMBOL(scsi_get_command);
305 * __scsi_put_command - Free a struct scsi_cmnd
307 * @cmd: Command to free
308 * @dev: parent scsi device
310 void __scsi_put_command(struct Scsi_Host *shost, struct scsi_cmnd *cmd,
315 /* changing locks here, don't need to restore the irq state */
316 spin_lock_irqsave(&shost->free_list_lock, flags);
317 if (unlikely(list_empty(&shost->free_list))) {
318 list_add(&cmd->list, &shost->free_list);
321 spin_unlock_irqrestore(&shost->free_list_lock, flags);
323 if (likely(cmd != NULL))
324 scsi_pool_free_command(shost->cmd_pool, cmd);
328 EXPORT_SYMBOL(__scsi_put_command);
331 * scsi_put_command - Free a scsi command block
332 * @cmd: command block to free
336 * Notes: The command must not belong to any lists.
338 void scsi_put_command(struct scsi_cmnd *cmd)
340 struct scsi_device *sdev = cmd->device;
343 /* serious error if the command hasn't come from a device list */
344 spin_lock_irqsave(&cmd->device->list_lock, flags);
345 BUG_ON(list_empty(&cmd->list));
346 list_del_init(&cmd->list);
347 spin_unlock_irqrestore(&cmd->device->list_lock, flags);
349 __scsi_put_command(cmd->device->host, cmd, &sdev->sdev_gendev);
351 EXPORT_SYMBOL(scsi_put_command);
353 static struct scsi_host_cmd_pool *scsi_get_host_cmd_pool(gfp_t gfp_mask)
355 struct scsi_host_cmd_pool *retval = NULL, *pool;
357 * Select a command slab for this host and create it if not
360 mutex_lock(&host_cmd_pool_mutex);
361 pool = (gfp_mask & __GFP_DMA) ? &scsi_cmd_dma_pool :
364 pool->cmd_slab = kmem_cache_create(pool->cmd_name,
365 sizeof(struct scsi_cmnd), 0,
366 pool->slab_flags, NULL);
370 pool->sense_slab = kmem_cache_create(pool->sense_name,
371 SCSI_SENSE_BUFFERSIZE, 0,
372 pool->slab_flags, NULL);
373 if (!pool->sense_slab) {
374 kmem_cache_destroy(pool->cmd_slab);
382 mutex_unlock(&host_cmd_pool_mutex);
386 static void scsi_put_host_cmd_pool(gfp_t gfp_mask)
388 struct scsi_host_cmd_pool *pool;
390 mutex_lock(&host_cmd_pool_mutex);
391 pool = (gfp_mask & __GFP_DMA) ? &scsi_cmd_dma_pool :
394 * This may happen if a driver has a mismatched get and put
395 * of the command pool; the driver should be implicated in
398 BUG_ON(pool->users == 0);
400 if (!--pool->users) {
401 kmem_cache_destroy(pool->cmd_slab);
402 kmem_cache_destroy(pool->sense_slab);
404 mutex_unlock(&host_cmd_pool_mutex);
408 * scsi_allocate_command - get a fully allocated SCSI command
409 * @gfp_mask: allocation mask
411 * This function is for use outside of the normal host based pools.
412 * It allocates the relevant command and takes an additional reference
413 * on the pool it used. This function *must* be paired with
414 * scsi_free_command which also has the identical mask, otherwise the
415 * free pool counts will eventually go wrong and you'll trigger a bug.
417 * This function should *only* be used by drivers that need a static
418 * command allocation at start of day for internal functions.
420 struct scsi_cmnd *scsi_allocate_command(gfp_t gfp_mask)
422 struct scsi_host_cmd_pool *pool = scsi_get_host_cmd_pool(gfp_mask);
427 return scsi_pool_alloc_command(pool, gfp_mask);
429 EXPORT_SYMBOL(scsi_allocate_command);
432 * scsi_free_command - free a command allocated by scsi_allocate_command
433 * @gfp_mask: mask used in the original allocation
434 * @cmd: command to free
436 * Note: using the original allocation mask is vital because that's
437 * what determines which command pool we use to free the command. Any
438 * mismatch will cause the system to BUG eventually.
440 void scsi_free_command(gfp_t gfp_mask, struct scsi_cmnd *cmd)
442 struct scsi_host_cmd_pool *pool = scsi_get_host_cmd_pool(gfp_mask);
445 * this could trigger if the mask to scsi_allocate_command
446 * doesn't match this mask. Otherwise we're guaranteed that this
447 * succeeds because scsi_allocate_command must have taken a reference
452 scsi_pool_free_command(pool, cmd);
454 * scsi_put_host_cmd_pool is called twice; once to release the
455 * reference we took above, and once to release the reference
456 * originally taken by scsi_allocate_command
458 scsi_put_host_cmd_pool(gfp_mask);
459 scsi_put_host_cmd_pool(gfp_mask);
461 EXPORT_SYMBOL(scsi_free_command);
464 * scsi_setup_command_freelist - Setup the command freelist for a scsi host.
465 * @shost: host to allocate the freelist for.
467 * Description: The command freelist protects against system-wide out of memory
468 * deadlock by preallocating one SCSI command structure for each host, so the
469 * system can always write to a swap file on a device associated with that host.
473 int scsi_setup_command_freelist(struct Scsi_Host *shost)
475 struct scsi_cmnd *cmd;
476 const gfp_t gfp_mask = shost->unchecked_isa_dma ? GFP_DMA : GFP_KERNEL;
478 spin_lock_init(&shost->free_list_lock);
479 INIT_LIST_HEAD(&shost->free_list);
481 shost->cmd_pool = scsi_get_host_cmd_pool(gfp_mask);
483 if (!shost->cmd_pool)
487 * Get one backup command for this host.
489 cmd = scsi_host_alloc_command(shost, gfp_mask);
491 scsi_put_host_cmd_pool(gfp_mask);
492 shost->cmd_pool = NULL;
495 list_add(&cmd->list, &shost->free_list);
500 * scsi_destroy_command_freelist - Release the command freelist for a scsi host.
501 * @shost: host whose freelist is going to be destroyed
503 void scsi_destroy_command_freelist(struct Scsi_Host *shost)
506 * If cmd_pool is NULL the free list was not initialized, so
507 * do not attempt to release resources.
509 if (!shost->cmd_pool)
512 while (!list_empty(&shost->free_list)) {
513 struct scsi_cmnd *cmd;
515 cmd = list_entry(shost->free_list.next, struct scsi_cmnd, list);
516 list_del_init(&cmd->list);
517 scsi_pool_free_command(shost->cmd_pool, cmd);
519 shost->cmd_pool = NULL;
520 scsi_put_host_cmd_pool(shost->unchecked_isa_dma ? GFP_DMA : GFP_KERNEL);
523 #ifdef CONFIG_SCSI_LOGGING
524 void scsi_log_send(struct scsi_cmnd *cmd)
529 * If ML QUEUE log level is greater than or equal to:
531 * 1: nothing (match completion)
533 * 2: log opcode + command of all commands
535 * 3: same as 2 plus dump cmd address
537 * 4: same as 3 plus dump extra junk
539 if (unlikely(scsi_logging_level)) {
540 level = SCSI_LOG_LEVEL(SCSI_LOG_MLQUEUE_SHIFT,
541 SCSI_LOG_MLQUEUE_BITS);
543 scmd_printk(KERN_INFO, cmd, "Send: ");
545 printk("0x%p ", cmd);
547 scsi_print_command(cmd);
549 printk(KERN_INFO "buffer = 0x%p, bufflen = %d,"
550 " queuecommand 0x%p\n",
551 scsi_sglist(cmd), scsi_bufflen(cmd),
552 cmd->device->host->hostt->queuecommand);
559 void scsi_log_completion(struct scsi_cmnd *cmd, int disposition)
564 * If ML COMPLETE log level is greater than or equal to:
566 * 1: log disposition, result, opcode + command, and conditionally
567 * sense data for failures or non SUCCESS dispositions.
569 * 2: same as 1 but for all command completions.
571 * 3: same as 2 plus dump cmd address
573 * 4: same as 3 plus dump extra junk
575 if (unlikely(scsi_logging_level)) {
576 level = SCSI_LOG_LEVEL(SCSI_LOG_MLCOMPLETE_SHIFT,
577 SCSI_LOG_MLCOMPLETE_BITS);
578 if (((level > 0) && (cmd->result || disposition != SUCCESS)) ||
580 scmd_printk(KERN_INFO, cmd, "Done: ");
582 printk("0x%p ", cmd);
584 * Dump truncated values, so we usually fit within
587 switch (disposition) {
602 * If called via scsi_times_out.
609 scsi_print_result(cmd);
610 scsi_print_command(cmd);
611 if (status_byte(cmd->result) & CHECK_CONDITION)
612 scsi_print_sense("", cmd);
614 scmd_printk(KERN_INFO, cmd,
615 "scsi host busy %d failed %d\n",
616 cmd->device->host->host_busy,
617 cmd->device->host->host_failed);
624 * scsi_cmd_get_serial - Assign a serial number to a command
625 * @host: the scsi host
626 * @cmd: command to assign serial number to
628 * Description: a serial number identifies a request for error recovery
629 * and debugging purposes. Protected by the Host_Lock of host.
631 static inline void scsi_cmd_get_serial(struct Scsi_Host *host, struct scsi_cmnd *cmd)
633 cmd->serial_number = host->cmd_serial_number++;
634 if (cmd->serial_number == 0)
635 cmd->serial_number = host->cmd_serial_number++;
639 * scsi_dispatch_command - Dispatch a command to the low-level driver.
640 * @cmd: command block we are dispatching.
642 * Return: nonzero return request was rejected and device's queue needs to be
645 int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
647 struct Scsi_Host *host = cmd->device->host;
648 unsigned long flags = 0;
649 unsigned long timeout;
652 atomic_inc(&cmd->device->iorequest_cnt);
654 /* check if the device is still usable */
655 if (unlikely(cmd->device->sdev_state == SDEV_DEL)) {
656 /* in SDEV_DEL we error all commands. DID_NO_CONNECT
657 * returns an immediate error upwards, and signals
658 * that the device is no longer present */
659 cmd->result = DID_NO_CONNECT << 16;
661 /* return 0 (because the command has been processed) */
665 /* Check to see if the scsi lld made this device blocked. */
666 if (unlikely(scsi_device_blocked(cmd->device))) {
668 * in blocked state, the command is just put back on
669 * the device queue. The suspend state has already
670 * blocked the queue so future requests should not
671 * occur until the device transitions out of the
675 scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
677 SCSI_LOG_MLQUEUE(3, printk("queuecommand : device blocked \n"));
680 * NOTE: rtn is still zero here because we don't need the
681 * queue to be plugged on return (it's already stopped)
687 * If SCSI-2 or lower, store the LUN value in cmnd.
689 if (cmd->device->scsi_level <= SCSI_2 &&
690 cmd->device->scsi_level != SCSI_UNKNOWN) {
691 cmd->cmnd[1] = (cmd->cmnd[1] & 0x1f) |
692 (cmd->device->lun << 5 & 0xe0);
696 * We will wait MIN_RESET_DELAY clock ticks after the last reset so
697 * we can avoid the drive not being ready.
699 timeout = host->last_reset + MIN_RESET_DELAY;
701 if (host->resetting && time_before(jiffies, timeout)) {
702 int ticks_remaining = timeout - jiffies;
704 * NOTE: This may be executed from within an interrupt
705 * handler! This is bad, but for now, it'll do. The irq
706 * level of the interrupt handler has been masked out by the
707 * platform dependent interrupt handling code already, so the
708 * sti() here will not cause another call to the SCSI host's
709 * interrupt handler (assuming there is one irq-level per
712 while (--ticks_remaining >= 0)
713 mdelay(1 + 999 / HZ);
720 * Before we queue this command, check if the command
721 * length exceeds what the host adapter can handle.
723 if (cmd->cmd_len > cmd->device->host->max_cmd_len) {
725 printk("queuecommand : command too long. "
726 "cdb_size=%d host->max_cmd_len=%d\n",
727 cmd->cmd_len, cmd->device->host->max_cmd_len));
728 cmd->result = (DID_ABORT << 16);
734 spin_lock_irqsave(host->host_lock, flags);
736 * AK: unlikely race here: for some reason the timer could
737 * expire before the serial number is set up below.
739 * TODO: kill serial or move to blk layer
741 scsi_cmd_get_serial(host, cmd);
743 if (unlikely(host->shost_state == SHOST_DEL)) {
744 cmd->result = (DID_NO_CONNECT << 16);
747 rtn = host->hostt->queuecommand(cmd, scsi_done);
749 spin_unlock_irqrestore(host->host_lock, flags);
751 if (rtn != SCSI_MLQUEUE_DEVICE_BUSY &&
752 rtn != SCSI_MLQUEUE_TARGET_BUSY)
753 rtn = SCSI_MLQUEUE_HOST_BUSY;
755 scsi_queue_insert(cmd, rtn);
758 printk("queuecommand : request rejected\n"));
762 SCSI_LOG_MLQUEUE(3, printk("leaving scsi_dispatch_cmnd()\n"));
767 * scsi_done - Enqueue the finished SCSI command into the done queue.
768 * @cmd: The SCSI Command for which a low-level device driver (LLDD) gives
769 * ownership back to SCSI Core -- i.e. the LLDD has finished with it.
771 * Description: This function is the mid-level's (SCSI Core) interrupt routine,
772 * which regains ownership of the SCSI command (de facto) from a LLDD, and
773 * enqueues the command to the done queue for further processing.
775 * This is the producer of the done queue who enqueues at the tail.
777 * This function is interrupt context safe.
779 static void scsi_done(struct scsi_cmnd *cmd)
781 blk_complete_request(cmd->request);
784 /* Move this to a header if it becomes more generally useful */
785 static struct scsi_driver *scsi_cmd_to_driver(struct scsi_cmnd *cmd)
787 return *(struct scsi_driver **)cmd->request->rq_disk->private_data;
791 * scsi_finish_command - cleanup and pass command back to upper layer
794 * Description: Pass command off to upper layer for finishing of I/O
795 * request, waking processes that are waiting on results,
798 void scsi_finish_command(struct scsi_cmnd *cmd)
800 struct scsi_device *sdev = cmd->device;
801 struct scsi_target *starget = scsi_target(sdev);
802 struct Scsi_Host *shost = sdev->host;
803 struct scsi_driver *drv;
804 unsigned int good_bytes;
806 scsi_device_unbusy(sdev);
809 * Clear the flags which say that the device/host is no longer
810 * capable of accepting new commands. These are set in scsi_queue.c
811 * for both the queue full condition on a device, and for a
812 * host full condition on the host.
814 * XXX(hch): What about locking?
816 shost->host_blocked = 0;
817 starget->target_blocked = 0;
818 sdev->device_blocked = 0;
821 * If we have valid sense information, then some kind of recovery
822 * must have taken place. Make a note of this.
824 if (SCSI_SENSE_VALID(cmd))
825 cmd->result |= (DRIVER_SENSE << 24);
827 SCSI_LOG_MLCOMPLETE(4, sdev_printk(KERN_INFO, sdev,
828 "Notifying upper driver of completion "
829 "(result %x)\n", cmd->result));
831 good_bytes = scsi_bufflen(cmd);
832 if (cmd->request->cmd_type != REQ_TYPE_BLOCK_PC) {
833 int old_good_bytes = good_bytes;
834 drv = scsi_cmd_to_driver(cmd);
836 good_bytes = drv->done(cmd);
838 * USB may not give sense identifying bad sector and
839 * simply return a residue instead, so subtract off the
840 * residue if drv->done() error processing indicates no
841 * change to the completion length.
843 if (good_bytes == old_good_bytes)
844 good_bytes -= scsi_get_resid(cmd);
846 scsi_io_completion(cmd, good_bytes);
848 EXPORT_SYMBOL(scsi_finish_command);
851 * scsi_adjust_queue_depth - Let low level drivers change a device's queue depth
852 * @sdev: SCSI Device in question
853 * @tagged: Do we use tagged queueing (non-0) or do we treat
854 * this device as an untagged device (0)
855 * @tags: Number of tags allowed if tagged queueing enabled,
856 * or number of commands the low level driver can
857 * queue up in non-tagged mode (as per cmd_per_lun).
861 * Lock Status: None held on entry
863 * Notes: Low level drivers may call this at any time and we will do
864 * the right thing depending on whether or not the device is
865 * currently active and whether or not it even has the
866 * command blocks built yet.
868 void scsi_adjust_queue_depth(struct scsi_device *sdev, int tagged, int tags)
873 * refuse to set tagged depth to an unworkable size
878 spin_lock_irqsave(sdev->request_queue->queue_lock, flags);
881 * Check to see if the queue is managed by the block layer.
882 * If it is, and we fail to adjust the depth, exit.
884 * Do not resize the tag map if it is a host wide share bqt,
885 * because the size should be the hosts's can_queue. If there
886 * is more IO than the LLD's can_queue (so there are not enuogh
887 * tags) request_fn's host queue ready check will handle it.
889 if (!sdev->host->bqt) {
890 if (blk_queue_tagged(sdev->request_queue) &&
891 blk_queue_resize_tags(sdev->request_queue, tags) != 0)
895 sdev->queue_depth = tags;
897 case MSG_ORDERED_TAG:
898 sdev->ordered_tags = 1;
899 sdev->simple_tags = 1;
902 sdev->ordered_tags = 0;
903 sdev->simple_tags = 1;
906 sdev_printk(KERN_WARNING, sdev,
907 "scsi_adjust_queue_depth, bad queue type, "
910 sdev->ordered_tags = sdev->simple_tags = 0;
911 sdev->queue_depth = tags;
915 spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
917 EXPORT_SYMBOL(scsi_adjust_queue_depth);
920 * scsi_track_queue_full - track QUEUE_FULL events to adjust queue depth
921 * @sdev: SCSI Device in question
922 * @depth: Current number of outstanding SCSI commands on this device,
923 * not counting the one returned as QUEUE_FULL.
925 * Description: This function will track successive QUEUE_FULL events on a
926 * specific SCSI device to determine if and when there is a
927 * need to adjust the queue depth on the device.
929 * Returns: 0 - No change needed, >0 - Adjust queue depth to this new depth,
930 * -1 - Drop back to untagged operation using host->cmd_per_lun
931 * as the untagged command depth
933 * Lock Status: None held on entry
935 * Notes: Low level drivers may call this at any time and we will do
936 * "The Right Thing." We are interrupt context safe.
938 int scsi_track_queue_full(struct scsi_device *sdev, int depth)
940 if ((jiffies >> 4) == sdev->last_queue_full_time)
943 sdev->last_queue_full_time = (jiffies >> 4);
944 if (sdev->last_queue_full_depth != depth) {
945 sdev->last_queue_full_count = 1;
946 sdev->last_queue_full_depth = depth;
948 sdev->last_queue_full_count++;
951 if (sdev->last_queue_full_count <= 10)
953 if (sdev->last_queue_full_depth < 8) {
954 /* Drop back to untagged */
955 scsi_adjust_queue_depth(sdev, 0, sdev->host->cmd_per_lun);
959 if (sdev->ordered_tags)
960 scsi_adjust_queue_depth(sdev, MSG_ORDERED_TAG, depth);
962 scsi_adjust_queue_depth(sdev, MSG_SIMPLE_TAG, depth);
965 EXPORT_SYMBOL(scsi_track_queue_full);
968 * scsi_vpd_inquiry - Request a device provide us with a VPD page
969 * @sdev: The device to ask
970 * @buffer: Where to put the result
971 * @page: Which Vital Product Data to return
972 * @len: The length of the buffer
974 * This is an internal helper function. You probably want to use
975 * scsi_get_vpd_page instead.
977 * Returns 0 on success or a negative error number.
979 static int scsi_vpd_inquiry(struct scsi_device *sdev, unsigned char *buffer,
980 u8 page, unsigned len)
983 unsigned char cmd[16];
986 cmd[1] = 1; /* EVPD */
990 cmd[5] = 0; /* Control byte */
993 * I'm not convinced we need to try quite this hard to get VPD, but
994 * all the existing users tried this hard.
996 result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer,
997 len + 4, NULL, 30 * HZ, 3, NULL);
1001 /* Sanity check that we got the page back that we asked for */
1002 if (buffer[1] != page)
1009 * scsi_get_vpd_page - Get Vital Product Data from a SCSI device
1010 * @sdev: The device to ask
1011 * @page: Which Vital Product Data to return
1013 * SCSI devices may optionally supply Vital Product Data. Each 'page'
1014 * of VPD is defined in the appropriate SCSI document (eg SPC, SBC).
1015 * If the device supports this VPD page, this routine returns a pointer
1016 * to a buffer containing the data from that page. The caller is
1017 * responsible for calling kfree() on this pointer when it is no longer
1018 * needed. If we cannot retrieve the VPD page this routine returns %NULL.
1020 unsigned char *scsi_get_vpd_page(struct scsi_device *sdev, u8 page)
1024 unsigned char *buf = kmalloc(259, GFP_KERNEL);
1029 /* Ask for all the pages supported by this device */
1030 result = scsi_vpd_inquiry(sdev, buf, 0, 255);
1034 /* If the user actually wanted this page, we can skip the rest */
1038 for (i = 0; i < buf[3]; i++)
1039 if (buf[i + 4] == page)
1041 /* The device claims it doesn't support the requested page */
1045 result = scsi_vpd_inquiry(sdev, buf, page, 255);
1050 * Some pages are longer than 255 bytes. The actual length of
1051 * the page is returned in the header.
1053 len = (buf[2] << 8) | buf[3];
1058 buf = kmalloc(len + 4, GFP_KERNEL);
1059 result = scsi_vpd_inquiry(sdev, buf, page, len);
1069 EXPORT_SYMBOL_GPL(scsi_get_vpd_page);
1072 * scsi_device_get - get an additional reference to a scsi_device
1073 * @sdev: device to get a reference to
1075 * Description: Gets a reference to the scsi_device and increments the use count
1076 * of the underlying LLDD module. You must hold host_lock of the
1077 * parent Scsi_Host or already have a reference when calling this.
1079 int scsi_device_get(struct scsi_device *sdev)
1081 if (sdev->sdev_state == SDEV_DEL)
1083 if (!get_device(&sdev->sdev_gendev))
1085 /* We can fail this if we're doing SCSI operations
1086 * from module exit (like cache flush) */
1087 try_module_get(sdev->host->hostt->module);
1091 EXPORT_SYMBOL(scsi_device_get);
1094 * scsi_device_put - release a reference to a scsi_device
1095 * @sdev: device to release a reference on.
1097 * Description: Release a reference to the scsi_device and decrements the use
1098 * count of the underlying LLDD module. The device is freed once the last
1101 void scsi_device_put(struct scsi_device *sdev)
1103 #ifdef CONFIG_MODULE_UNLOAD
1104 struct module *module = sdev->host->hostt->module;
1106 /* The module refcount will be zero if scsi_device_get()
1107 * was called from a module removal routine */
1108 if (module && module_refcount(module) != 0)
1111 put_device(&sdev->sdev_gendev);
1113 EXPORT_SYMBOL(scsi_device_put);
1115 /* helper for shost_for_each_device, see that for documentation */
1116 struct scsi_device *__scsi_iterate_devices(struct Scsi_Host *shost,
1117 struct scsi_device *prev)
1119 struct list_head *list = (prev ? &prev->siblings : &shost->__devices);
1120 struct scsi_device *next = NULL;
1121 unsigned long flags;
1123 spin_lock_irqsave(shost->host_lock, flags);
1124 while (list->next != &shost->__devices) {
1125 next = list_entry(list->next, struct scsi_device, siblings);
1126 /* skip devices that we can't get a reference to */
1127 if (!scsi_device_get(next))
1132 spin_unlock_irqrestore(shost->host_lock, flags);
1135 scsi_device_put(prev);
1138 EXPORT_SYMBOL(__scsi_iterate_devices);
1141 * starget_for_each_device - helper to walk all devices of a target
1142 * @starget: target whose devices we want to iterate over.
1143 * @data: Opaque passed to each function call.
1144 * @fn: Function to call on each device
1146 * This traverses over each device of @starget. The devices have
1147 * a reference that must be released by scsi_host_put when breaking
1150 void starget_for_each_device(struct scsi_target *starget, void *data,
1151 void (*fn)(struct scsi_device *, void *))
1153 struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
1154 struct scsi_device *sdev;
1156 shost_for_each_device(sdev, shost) {
1157 if ((sdev->channel == starget->channel) &&
1158 (sdev->id == starget->id))
1162 EXPORT_SYMBOL(starget_for_each_device);
1165 * __starget_for_each_device - helper to walk all devices of a target (UNLOCKED)
1166 * @starget: target whose devices we want to iterate over.
1167 * @data: parameter for callback @fn()
1168 * @fn: callback function that is invoked for each device
1170 * This traverses over each device of @starget. It does _not_
1171 * take a reference on the scsi_device, so the whole loop must be
1172 * protected by shost->host_lock.
1174 * Note: The only reason why drivers would want to use this is because
1175 * they need to access the device list in irq context. Otherwise you
1176 * really want to use starget_for_each_device instead.
1178 void __starget_for_each_device(struct scsi_target *starget, void *data,
1179 void (*fn)(struct scsi_device *, void *))
1181 struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
1182 struct scsi_device *sdev;
1184 __shost_for_each_device(sdev, shost) {
1185 if ((sdev->channel == starget->channel) &&
1186 (sdev->id == starget->id))
1190 EXPORT_SYMBOL(__starget_for_each_device);
1193 * __scsi_device_lookup_by_target - find a device given the target (UNLOCKED)
1194 * @starget: SCSI target pointer
1195 * @lun: SCSI Logical Unit Number
1197 * Description: Looks up the scsi_device with the specified @lun for a given
1198 * @starget. The returned scsi_device does not have an additional
1199 * reference. You must hold the host's host_lock over this call and
1200 * any access to the returned scsi_device. A scsi_device in state
1201 * SDEV_DEL is skipped.
1203 * Note: The only reason why drivers should use this is because
1204 * they need to access the device list in irq context. Otherwise you
1205 * really want to use scsi_device_lookup_by_target instead.
1207 struct scsi_device *__scsi_device_lookup_by_target(struct scsi_target *starget,
1210 struct scsi_device *sdev;
1212 list_for_each_entry(sdev, &starget->devices, same_target_siblings) {
1213 if (sdev->sdev_state == SDEV_DEL)
1215 if (sdev->lun ==lun)
1221 EXPORT_SYMBOL(__scsi_device_lookup_by_target);
1224 * scsi_device_lookup_by_target - find a device given the target
1225 * @starget: SCSI target pointer
1226 * @lun: SCSI Logical Unit Number
1228 * Description: Looks up the scsi_device with the specified @lun for a given
1229 * @starget. The returned scsi_device has an additional reference that
1230 * needs to be released with scsi_device_put once you're done with it.
1232 struct scsi_device *scsi_device_lookup_by_target(struct scsi_target *starget,
1235 struct scsi_device *sdev;
1236 struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
1237 unsigned long flags;
1239 spin_lock_irqsave(shost->host_lock, flags);
1240 sdev = __scsi_device_lookup_by_target(starget, lun);
1241 if (sdev && scsi_device_get(sdev))
1243 spin_unlock_irqrestore(shost->host_lock, flags);
1247 EXPORT_SYMBOL(scsi_device_lookup_by_target);
1250 * __scsi_device_lookup - find a device given the host (UNLOCKED)
1251 * @shost: SCSI host pointer
1252 * @channel: SCSI channel (zero if only one channel)
1253 * @id: SCSI target number (physical unit number)
1254 * @lun: SCSI Logical Unit Number
1256 * Description: Looks up the scsi_device with the specified @channel, @id, @lun
1257 * for a given host. The returned scsi_device does not have an additional
1258 * reference. You must hold the host's host_lock over this call and any access
1259 * to the returned scsi_device.
1261 * Note: The only reason why drivers would want to use this is because
1262 * they need to access the device list in irq context. Otherwise you
1263 * really want to use scsi_device_lookup instead.
1265 struct scsi_device *__scsi_device_lookup(struct Scsi_Host *shost,
1266 uint channel, uint id, uint lun)
1268 struct scsi_device *sdev;
1270 list_for_each_entry(sdev, &shost->__devices, siblings) {
1271 if (sdev->channel == channel && sdev->id == id &&
1278 EXPORT_SYMBOL(__scsi_device_lookup);
1281 * scsi_device_lookup - find a device given the host
1282 * @shost: SCSI host pointer
1283 * @channel: SCSI channel (zero if only one channel)
1284 * @id: SCSI target number (physical unit number)
1285 * @lun: SCSI Logical Unit Number
1287 * Description: Looks up the scsi_device with the specified @channel, @id, @lun
1288 * for a given host. The returned scsi_device has an additional reference that
1289 * needs to be released with scsi_device_put once you're done with it.
1291 struct scsi_device *scsi_device_lookup(struct Scsi_Host *shost,
1292 uint channel, uint id, uint lun)
1294 struct scsi_device *sdev;
1295 unsigned long flags;
1297 spin_lock_irqsave(shost->host_lock, flags);
1298 sdev = __scsi_device_lookup(shost, channel, id, lun);
1299 if (sdev && scsi_device_get(sdev))
1301 spin_unlock_irqrestore(shost->host_lock, flags);
1305 EXPORT_SYMBOL(scsi_device_lookup);
1307 MODULE_DESCRIPTION("SCSI core");
1308 MODULE_LICENSE("GPL");
1310 module_param(scsi_logging_level, int, S_IRUGO|S_IWUSR);
1311 MODULE_PARM_DESC(scsi_logging_level, "a bit mask of logging levels");
1313 static int __init init_scsi(void)
1317 error = scsi_init_queue();
1320 error = scsi_init_procfs();
1323 error = scsi_init_devinfo();
1325 goto cleanup_procfs;
1326 error = scsi_init_hosts();
1328 goto cleanup_devlist;
1329 error = scsi_init_sysctl();
1332 error = scsi_sysfs_register();
1334 goto cleanup_sysctl;
1336 scsi_netlink_init();
1338 printk(KERN_NOTICE "SCSI subsystem initialized\n");
1346 scsi_exit_devinfo();
1351 printk(KERN_ERR "SCSI subsystem failed to initialize, error = %d\n",
1356 static void __exit exit_scsi(void)
1358 scsi_netlink_exit();
1359 scsi_sysfs_unregister();
1362 scsi_exit_devinfo();
1367 subsys_initcall(init_scsi);
1368 module_exit(exit_scsi);