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
/* NB: These are exposed through /proc/scsi/scsi and form part of the ABI.
94
* You may not alter any existing entry (although adding new ones is
95
* encouraged once assigned by ANSI/INCITS T10
97
static const char *const scsi_device_types[] = {
120
* scsi_device_type - Return 17 char string indicating device type.
121
* @type: type number to look up
124
const char * scsi_device_type(unsigned type)
127
return "Well-known LUN ";
130
if (type >= ARRAY_SIZE(scsi_device_types))
132
return scsi_device_types[type];
135
EXPORT_SYMBOL(scsi_device_type);
137
struct scsi_host_cmd_pool {
138
struct kmem_cache *cmd_slab;
139
struct kmem_cache *sense_slab;
143
unsigned int slab_flags;
147
static struct scsi_host_cmd_pool scsi_cmd_pool = {
148
.cmd_name = "scsi_cmd_cache",
149
.sense_name = "scsi_sense_cache",
150
.slab_flags = SLAB_HWCACHE_ALIGN,
153
static struct scsi_host_cmd_pool scsi_cmd_dma_pool = {
154
.cmd_name = "scsi_cmd_cache(DMA)",
155
.sense_name = "scsi_sense_cache(DMA)",
156
.slab_flags = SLAB_HWCACHE_ALIGN|SLAB_CACHE_DMA,
157
.gfp_mask = __GFP_DMA,
160
static DEFINE_MUTEX(host_cmd_pool_mutex);
163
* scsi_pool_alloc_command - internal function to get a fully allocated command
164
* @pool: slab pool to allocate the command from
165
* @gfp_mask: mask for the allocation
167
* Returns a fully allocated command (with the allied sense buffer) or
170
static struct scsi_cmnd *
171
scsi_pool_alloc_command(struct scsi_host_cmd_pool *pool, gfp_t gfp_mask)
173
struct scsi_cmnd *cmd;
175
cmd = kmem_cache_zalloc(pool->cmd_slab, gfp_mask | pool->gfp_mask);
179
cmd->sense_buffer = kmem_cache_alloc(pool->sense_slab,
180
gfp_mask | pool->gfp_mask);
181
if (!cmd->sense_buffer) {
182
kmem_cache_free(pool->cmd_slab, cmd);
190
* scsi_pool_free_command - internal function to release a command
191
* @pool: slab pool to allocate the command from
192
* @cmd: command to release
194
* the command must previously have been allocated by
195
* scsi_pool_alloc_command.
198
scsi_pool_free_command(struct scsi_host_cmd_pool *pool,
199
struct scsi_cmnd *cmd)
202
kmem_cache_free(scsi_sdb_cache, cmd->prot_sdb);
204
kmem_cache_free(pool->sense_slab, cmd->sense_buffer);
205
kmem_cache_free(pool->cmd_slab, cmd);
209
* scsi_host_alloc_command - internal function to allocate command
210
* @shost: SCSI host whose pool to allocate from
211
* @gfp_mask: mask for the allocation
213
* Returns a fully allocated command with sense buffer and protection
214
* data buffer (where applicable) or NULL on failure
216
static struct scsi_cmnd *
217
scsi_host_alloc_command(struct Scsi_Host *shost, gfp_t gfp_mask)
219
struct scsi_cmnd *cmd;
221
cmd = scsi_pool_alloc_command(shost->cmd_pool, gfp_mask);
225
if (scsi_host_get_prot(shost) >= SHOST_DIX_TYPE0_PROTECTION) {
226
cmd->prot_sdb = kmem_cache_zalloc(scsi_sdb_cache, gfp_mask);
228
if (!cmd->prot_sdb) {
229
scsi_pool_free_command(shost->cmd_pool, cmd);
238
* __scsi_get_command - Allocate a struct scsi_cmnd
239
* @shost: host to transmit command
240
* @gfp_mask: allocation mask
242
* Description: allocate a struct scsi_cmd from host's slab, recycling from the
243
* host's free_list if necessary.
245
struct scsi_cmnd *__scsi_get_command(struct Scsi_Host *shost, gfp_t gfp_mask)
247
struct scsi_cmnd *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);
263
buf = cmd->sense_buffer;
264
prot = cmd->prot_sdb;
266
memset(cmd, 0, sizeof(*cmd));
268
cmd->sense_buffer = buf;
269
cmd->prot_sdb = prot;
275
EXPORT_SYMBOL_GPL(__scsi_get_command);
278
* scsi_get_command - Allocate and setup a scsi command block
279
* @dev: parent scsi device
280
* @gfp_mask: allocator flags
282
* Returns: The allocated scsi command structure.
284
struct scsi_cmnd *scsi_get_command(struct scsi_device *dev, gfp_t gfp_mask)
286
struct scsi_cmnd *cmd;
288
/* Bail if we can't get a reference to the device */
289
if (!get_device(&dev->sdev_gendev))
292
cmd = __scsi_get_command(dev->host, gfp_mask);
294
if (likely(cmd != NULL)) {
298
INIT_LIST_HEAD(&cmd->list);
299
spin_lock_irqsave(&dev->list_lock, flags);
300
list_add_tail(&cmd->list, &dev->cmd_list);
301
spin_unlock_irqrestore(&dev->list_lock, flags);
302
cmd->jiffies_at_alloc = jiffies;
304
put_device(&dev->sdev_gendev);
308
EXPORT_SYMBOL(scsi_get_command);
311
* __scsi_put_command - Free a struct scsi_cmnd
313
* @cmd: Command to free
314
* @dev: parent scsi device
316
void __scsi_put_command(struct Scsi_Host *shost, struct scsi_cmnd *cmd,
321
/* changing locks here, don't need to restore the irq state */
322
spin_lock_irqsave(&shost->free_list_lock, flags);
323
if (unlikely(list_empty(&shost->free_list))) {
324
list_add(&cmd->list, &shost->free_list);
327
spin_unlock_irqrestore(&shost->free_list_lock, flags);
329
if (likely(cmd != NULL))
330
scsi_pool_free_command(shost->cmd_pool, cmd);
334
EXPORT_SYMBOL(__scsi_put_command);
337
* scsi_put_command - Free a scsi command block
338
* @cmd: command block to free
342
* Notes: The command must not belong to any lists.
344
void scsi_put_command(struct scsi_cmnd *cmd)
346
struct scsi_device *sdev = cmd->device;
349
/* serious error if the command hasn't come from a device list */
350
spin_lock_irqsave(&cmd->device->list_lock, flags);
351
BUG_ON(list_empty(&cmd->list));
352
list_del_init(&cmd->list);
353
spin_unlock_irqrestore(&cmd->device->list_lock, flags);
355
__scsi_put_command(cmd->device->host, cmd, &sdev->sdev_gendev);
357
EXPORT_SYMBOL(scsi_put_command);
359
static struct scsi_host_cmd_pool *scsi_get_host_cmd_pool(gfp_t gfp_mask)
361
struct scsi_host_cmd_pool *retval = NULL, *pool;
363
* Select a command slab for this host and create it if not
366
mutex_lock(&host_cmd_pool_mutex);
367
pool = (gfp_mask & __GFP_DMA) ? &scsi_cmd_dma_pool :
370
pool->cmd_slab = kmem_cache_create(pool->cmd_name,
371
sizeof(struct scsi_cmnd), 0,
372
pool->slab_flags, NULL);
376
pool->sense_slab = kmem_cache_create(pool->sense_name,
377
SCSI_SENSE_BUFFERSIZE, 0,
378
pool->slab_flags, NULL);
379
if (!pool->sense_slab) {
380
kmem_cache_destroy(pool->cmd_slab);
388
mutex_unlock(&host_cmd_pool_mutex);
392
static void scsi_put_host_cmd_pool(gfp_t gfp_mask)
394
struct scsi_host_cmd_pool *pool;
396
mutex_lock(&host_cmd_pool_mutex);
397
pool = (gfp_mask & __GFP_DMA) ? &scsi_cmd_dma_pool :
400
* This may happen if a driver has a mismatched get and put
401
* of the command pool; the driver should be implicated in
404
BUG_ON(pool->users == 0);
406
if (!--pool->users) {
407
kmem_cache_destroy(pool->cmd_slab);
408
kmem_cache_destroy(pool->sense_slab);
410
mutex_unlock(&host_cmd_pool_mutex);
414
* scsi_allocate_command - get a fully allocated SCSI command
415
* @gfp_mask: allocation mask
417
* This function is for use outside of the normal host based pools.
418
* It allocates the relevant command and takes an additional reference
419
* on the pool it used. This function *must* be paired with
420
* scsi_free_command which also has the identical mask, otherwise the
421
* free pool counts will eventually go wrong and you'll trigger a bug.
423
* This function should *only* be used by drivers that need a static
424
* command allocation at start of day for internal functions.
426
struct scsi_cmnd *scsi_allocate_command(gfp_t gfp_mask)
428
struct scsi_host_cmd_pool *pool = scsi_get_host_cmd_pool(gfp_mask);
433
return scsi_pool_alloc_command(pool, gfp_mask);
435
EXPORT_SYMBOL(scsi_allocate_command);
438
* scsi_free_command - free a command allocated by scsi_allocate_command
439
* @gfp_mask: mask used in the original allocation
440
* @cmd: command to free
442
* Note: using the original allocation mask is vital because that's
443
* what determines which command pool we use to free the command. Any
444
* mismatch will cause the system to BUG eventually.
446
void scsi_free_command(gfp_t gfp_mask, struct scsi_cmnd *cmd)
448
struct scsi_host_cmd_pool *pool = scsi_get_host_cmd_pool(gfp_mask);
451
* this could trigger if the mask to scsi_allocate_command
452
* doesn't match this mask. Otherwise we're guaranteed that this
453
* succeeds because scsi_allocate_command must have taken a reference
458
scsi_pool_free_command(pool, cmd);
460
* scsi_put_host_cmd_pool is called twice; once to release the
461
* reference we took above, and once to release the reference
462
* originally taken by scsi_allocate_command
464
scsi_put_host_cmd_pool(gfp_mask);
465
scsi_put_host_cmd_pool(gfp_mask);
467
EXPORT_SYMBOL(scsi_free_command);
470
* scsi_setup_command_freelist - Setup the command freelist for a scsi host.
471
* @shost: host to allocate the freelist for.
473
* Description: The command freelist protects against system-wide out of memory
474
* deadlock by preallocating one SCSI command structure for each host, so the
475
* system can always write to a swap file on a device associated with that host.
479
int scsi_setup_command_freelist(struct Scsi_Host *shost)
481
struct scsi_cmnd *cmd;
482
const gfp_t gfp_mask = shost->unchecked_isa_dma ? GFP_DMA : GFP_KERNEL;
484
spin_lock_init(&shost->free_list_lock);
485
INIT_LIST_HEAD(&shost->free_list);
487
shost->cmd_pool = scsi_get_host_cmd_pool(gfp_mask);
489
if (!shost->cmd_pool)
493
* Get one backup command for this host.
495
cmd = scsi_host_alloc_command(shost, gfp_mask);
497
scsi_put_host_cmd_pool(gfp_mask);
498
shost->cmd_pool = NULL;
501
list_add(&cmd->list, &shost->free_list);
506
* scsi_destroy_command_freelist - Release the command freelist for a scsi host.
507
* @shost: host whose freelist is going to be destroyed
509
void scsi_destroy_command_freelist(struct Scsi_Host *shost)
512
* If cmd_pool is NULL the free list was not initialized, so
513
* do not attempt to release resources.
515
if (!shost->cmd_pool)
518
while (!list_empty(&shost->free_list)) {
519
struct scsi_cmnd *cmd;
521
cmd = list_entry(shost->free_list.next, struct scsi_cmnd, list);
522
list_del_init(&cmd->list);
523
scsi_pool_free_command(shost->cmd_pool, cmd);
525
shost->cmd_pool = NULL;
526
scsi_put_host_cmd_pool(shost->unchecked_isa_dma ? GFP_DMA : GFP_KERNEL);
529
#ifdef CONFIG_SCSI_LOGGING
530
void scsi_log_send(struct scsi_cmnd *cmd)
535
* If ML QUEUE log level is greater than or equal to:
537
* 1: nothing (match completion)
539
* 2: log opcode + command of all commands
541
* 3: same as 2 plus dump cmd address
543
* 4: same as 3 plus dump extra junk
545
if (unlikely(scsi_logging_level)) {
546
level = SCSI_LOG_LEVEL(SCSI_LOG_MLQUEUE_SHIFT,
547
SCSI_LOG_MLQUEUE_BITS);
549
scmd_printk(KERN_INFO, cmd, "Send: ");
551
printk("0x%p ", cmd);
553
scsi_print_command(cmd);
555
printk(KERN_INFO "buffer = 0x%p, bufflen = %d,"
556
" queuecommand 0x%p\n",
557
scsi_sglist(cmd), scsi_bufflen(cmd),
558
cmd->device->host->hostt->queuecommand);
565
void scsi_log_completion(struct scsi_cmnd *cmd, int disposition)
570
* If ML COMPLETE log level is greater than or equal to:
572
* 1: log disposition, result, opcode + command, and conditionally
573
* sense data for failures or non SUCCESS dispositions.
575
* 2: same as 1 but for all command completions.
577
* 3: same as 2 plus dump cmd address
579
* 4: same as 3 plus dump extra junk
581
if (unlikely(scsi_logging_level)) {
582
level = SCSI_LOG_LEVEL(SCSI_LOG_MLCOMPLETE_SHIFT,
583
SCSI_LOG_MLCOMPLETE_BITS);
584
if (((level > 0) && (cmd->result || disposition != SUCCESS)) ||
586
scmd_printk(KERN_INFO, cmd, "Done: ");
588
printk("0x%p ", cmd);
590
* Dump truncated values, so we usually fit within
593
switch (disposition) {
608
* If called via scsi_times_out.
615
scsi_print_result(cmd);
616
scsi_print_command(cmd);
617
if (status_byte(cmd->result) & CHECK_CONDITION)
618
scsi_print_sense("", cmd);
620
scmd_printk(KERN_INFO, cmd,
621
"scsi host busy %d failed %d\n",
622
cmd->device->host->host_busy,
623
cmd->device->host->host_failed);
630
* scsi_cmd_get_serial - Assign a serial number to a command
631
* @host: the scsi host
632
* @cmd: command to assign serial number to
634
* Description: a serial number identifies a request for error recovery
635
* and debugging purposes. Protected by the Host_Lock of host.
637
void scsi_cmd_get_serial(struct Scsi_Host *host, struct scsi_cmnd *cmd)
639
cmd->serial_number = host->cmd_serial_number++;
640
if (cmd->serial_number == 0)
641
cmd->serial_number = host->cmd_serial_number++;
643
EXPORT_SYMBOL(scsi_cmd_get_serial);
646
* scsi_dispatch_command - Dispatch a command to the low-level driver.
647
* @cmd: command block we are dispatching.
649
* Return: nonzero return request was rejected and device's queue needs to be
652
int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
654
struct Scsi_Host *host = cmd->device->host;
655
unsigned long timeout;
658
atomic_inc(&cmd->device->iorequest_cnt);
660
/* check if the device is still usable */
661
if (unlikely(cmd->device->sdev_state == SDEV_DEL)) {
662
/* in SDEV_DEL we error all commands. DID_NO_CONNECT
663
* returns an immediate error upwards, and signals
664
* that the device is no longer present */
665
cmd->result = DID_NO_CONNECT << 16;
667
/* return 0 (because the command has been processed) */
671
/* Check to see if the scsi lld made this device blocked. */
672
if (unlikely(scsi_device_blocked(cmd->device))) {
674
* in blocked state, the command is just put back on
675
* the device queue. The suspend state has already
676
* blocked the queue so future requests should not
677
* occur until the device transitions out of the
681
scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
683
SCSI_LOG_MLQUEUE(3, printk("queuecommand : device blocked \n"));
686
* NOTE: rtn is still zero here because we don't need the
687
* queue to be plugged on return (it's already stopped)
693
* If SCSI-2 or lower, store the LUN value in cmnd.
695
if (cmd->device->scsi_level <= SCSI_2 &&
696
cmd->device->scsi_level != SCSI_UNKNOWN) {
697
cmd->cmnd[1] = (cmd->cmnd[1] & 0x1f) |
698
(cmd->device->lun << 5 & 0xe0);
702
* We will wait MIN_RESET_DELAY clock ticks after the last reset so
703
* we can avoid the drive not being ready.
705
timeout = host->last_reset + MIN_RESET_DELAY;
707
if (host->resetting && time_before(jiffies, timeout)) {
708
int ticks_remaining = timeout - jiffies;
710
* NOTE: This may be executed from within an interrupt
711
* handler! This is bad, but for now, it'll do. The irq
712
* level of the interrupt handler has been masked out by the
713
* platform dependent interrupt handling code already, so the
714
* sti() here will not cause another call to the SCSI host's
715
* interrupt handler (assuming there is one irq-level per
718
while (--ticks_remaining >= 0)
719
mdelay(1 + 999 / HZ);
726
* Before we queue this command, check if the command
727
* length exceeds what the host adapter can handle.
729
if (cmd->cmd_len > cmd->device->host->max_cmd_len) {
731
printk("queuecommand : command too long. "
732
"cdb_size=%d host->max_cmd_len=%d\n",
733
cmd->cmd_len, cmd->device->host->max_cmd_len));
734
cmd->result = (DID_ABORT << 16);
740
if (unlikely(host->shost_state == SHOST_DEL)) {
741
cmd->result = (DID_NO_CONNECT << 16);
744
trace_scsi_dispatch_cmd_start(cmd);
745
cmd->scsi_done = scsi_done;
746
rtn = host->hostt->queuecommand(host, cmd);
750
trace_scsi_dispatch_cmd_error(cmd, rtn);
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
trace_scsi_dispatch_cmd_done(cmd);
782
blk_complete_request(cmd->request);
785
/* Move this to a header if it becomes more generally useful */
786
static struct scsi_driver *scsi_cmd_to_driver(struct scsi_cmnd *cmd)
788
return *(struct scsi_driver **)cmd->request->rq_disk->private_data;
792
* scsi_finish_command - cleanup and pass command back to upper layer
795
* Description: Pass command off to upper layer for finishing of I/O
796
* request, waking processes that are waiting on results,
799
void scsi_finish_command(struct scsi_cmnd *cmd)
801
struct scsi_device *sdev = cmd->device;
802
struct scsi_target *starget = scsi_target(sdev);
803
struct Scsi_Host *shost = sdev->host;
804
struct scsi_driver *drv;
805
unsigned int good_bytes;
807
scsi_device_unbusy(sdev);
810
* Clear the flags which say that the device/host is no longer
811
* capable of accepting new commands. These are set in scsi_queue.c
812
* for both the queue full condition on a device, and for a
813
* host full condition on the host.
815
* XXX(hch): What about locking?
817
shost->host_blocked = 0;
818
starget->target_blocked = 0;
819
sdev->device_blocked = 0;
822
* If we have valid sense information, then some kind of recovery
823
* must have taken place. Make a note of this.
825
if (SCSI_SENSE_VALID(cmd))
826
cmd->result |= (DRIVER_SENSE << 24);
828
SCSI_LOG_MLCOMPLETE(4, sdev_printk(KERN_INFO, sdev,
829
"Notifying upper driver of completion "
830
"(result %x)\n", cmd->result));
832
good_bytes = scsi_bufflen(cmd);
833
if (cmd->request->cmd_type != REQ_TYPE_BLOCK_PC) {
834
int old_good_bytes = good_bytes;
835
drv = scsi_cmd_to_driver(cmd);
837
good_bytes = drv->done(cmd);
839
* USB may not give sense identifying bad sector and
840
* simply return a residue instead, so subtract off the
841
* residue if drv->done() error processing indicates no
842
* change to the completion length.
844
if (good_bytes == old_good_bytes)
845
good_bytes -= scsi_get_resid(cmd);
847
scsi_io_completion(cmd, good_bytes);
849
EXPORT_SYMBOL(scsi_finish_command);
852
* scsi_adjust_queue_depth - Let low level drivers change a device's queue depth
853
* @sdev: SCSI Device in question
854
* @tagged: Do we use tagged queueing (non-0) or do we treat
855
* this device as an untagged device (0)
856
* @tags: Number of tags allowed if tagged queueing enabled,
857
* or number of commands the low level driver can
858
* queue up in non-tagged mode (as per cmd_per_lun).
862
* Lock Status: None held on entry
864
* Notes: Low level drivers may call this at any time and we will do
865
* the right thing depending on whether or not the device is
866
* currently active and whether or not it even has the
867
* command blocks built yet.
869
void scsi_adjust_queue_depth(struct scsi_device *sdev, int tagged, int tags)
874
* refuse to set tagged depth to an unworkable size
879
spin_lock_irqsave(sdev->request_queue->queue_lock, flags);
882
* Check to see if the queue is managed by the block layer.
883
* If it is, and we fail to adjust the depth, exit.
885
* Do not resize the tag map if it is a host wide share bqt,
886
* because the size should be the hosts's can_queue. If there
887
* is more IO than the LLD's can_queue (so there are not enuogh
888
* tags) request_fn's host queue ready check will handle it.
890
if (!sdev->host->bqt) {
891
if (blk_queue_tagged(sdev->request_queue) &&
892
blk_queue_resize_tags(sdev->request_queue, tags) != 0)
896
sdev->queue_depth = tags;
898
case MSG_ORDERED_TAG:
899
sdev->ordered_tags = 1;
900
sdev->simple_tags = 1;
903
sdev->ordered_tags = 0;
904
sdev->simple_tags = 1;
907
sdev_printk(KERN_WARNING, sdev,
908
"scsi_adjust_queue_depth, bad queue type, "
911
sdev->ordered_tags = sdev->simple_tags = 0;
912
sdev->queue_depth = tags;
916
spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
918
EXPORT_SYMBOL(scsi_adjust_queue_depth);
921
* scsi_track_queue_full - track QUEUE_FULL events to adjust queue depth
922
* @sdev: SCSI Device in question
923
* @depth: Current number of outstanding SCSI commands on this device,
924
* not counting the one returned as QUEUE_FULL.
926
* Description: This function will track successive QUEUE_FULL events on a
927
* specific SCSI device to determine if and when there is a
928
* need to adjust the queue depth on the device.
930
* Returns: 0 - No change needed, >0 - Adjust queue depth to this new depth,
931
* -1 - Drop back to untagged operation using host->cmd_per_lun
932
* as the untagged command depth
934
* Lock Status: None held on entry
936
* Notes: Low level drivers may call this at any time and we will do
937
* "The Right Thing." We are interrupt context safe.
939
int scsi_track_queue_full(struct scsi_device *sdev, int depth)
943
* Don't let QUEUE_FULLs on the same
944
* jiffies count, they could all be from
947
if ((jiffies >> 4) == (sdev->last_queue_full_time >> 4))
950
sdev->last_queue_full_time = jiffies;
951
if (sdev->last_queue_full_depth != depth) {
952
sdev->last_queue_full_count = 1;
953
sdev->last_queue_full_depth = depth;
955
sdev->last_queue_full_count++;
958
if (sdev->last_queue_full_count <= 10)
960
if (sdev->last_queue_full_depth < 8) {
961
/* Drop back to untagged */
962
scsi_adjust_queue_depth(sdev, 0, sdev->host->cmd_per_lun);
966
if (sdev->ordered_tags)
967
scsi_adjust_queue_depth(sdev, MSG_ORDERED_TAG, depth);
969
scsi_adjust_queue_depth(sdev, MSG_SIMPLE_TAG, depth);
972
EXPORT_SYMBOL(scsi_track_queue_full);
975
* scsi_vpd_inquiry - Request a device provide us with a VPD page
976
* @sdev: The device to ask
977
* @buffer: Where to put the result
978
* @page: Which Vital Product Data to return
979
* @len: The length of the buffer
981
* This is an internal helper function. You probably want to use
982
* scsi_get_vpd_page instead.
984
* Returns 0 on success or a negative error number.
986
static int scsi_vpd_inquiry(struct scsi_device *sdev, unsigned char *buffer,
987
u8 page, unsigned len)
990
unsigned char cmd[16];
993
cmd[1] = 1; /* EVPD */
997
cmd[5] = 0; /* Control byte */
1000
* I'm not convinced we need to try quite this hard to get VPD, but
1001
* all the existing users tried this hard.
1003
result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer,
1004
len, NULL, 30 * HZ, 3, NULL);
1008
/* Sanity check that we got the page back that we asked for */
1009
if (buffer[1] != page)
1016
* scsi_get_vpd_page - Get Vital Product Data from a SCSI device
1017
* @sdev: The device to ask
1018
* @page: Which Vital Product Data to return
1019
* @buf: where to store the VPD
1020
* @buf_len: number of bytes in the VPD buffer area
1022
* SCSI devices may optionally supply Vital Product Data. Each 'page'
1023
* of VPD is defined in the appropriate SCSI document (eg SPC, SBC).
1024
* If the device supports this VPD page, this routine returns a pointer
1025
* to a buffer containing the data from that page. The caller is
1026
* responsible for calling kfree() on this pointer when it is no longer
1027
* needed. If we cannot retrieve the VPD page this routine returns %NULL.
1029
int scsi_get_vpd_page(struct scsi_device *sdev, u8 page, unsigned char *buf,
1034
/* Ask for all the pages supported by this device */
1035
result = scsi_vpd_inquiry(sdev, buf, 0, buf_len);
1039
/* If the user actually wanted this page, we can skip the rest */
1043
for (i = 0; i < min((int)buf[3], buf_len - 4); i++)
1044
if (buf[i + 4] == page)
1047
if (i < buf[3] && i >= buf_len - 4)
1048
/* ran off the end of the buffer, give us benefit of doubt */
1050
/* The device claims it doesn't support the requested page */
1054
result = scsi_vpd_inquiry(sdev, buf, page, buf_len);
1063
EXPORT_SYMBOL_GPL(scsi_get_vpd_page);
1066
* scsi_device_get - get an additional reference to a scsi_device
1067
* @sdev: device to get a reference to
1069
* Description: Gets a reference to the scsi_device and increments the use count
1070
* of the underlying LLDD module. You must hold host_lock of the
1071
* parent Scsi_Host or already have a reference when calling this.
1073
int scsi_device_get(struct scsi_device *sdev)
1075
if (sdev->sdev_state == SDEV_DEL)
1077
if (!get_device(&sdev->sdev_gendev))
1079
/* We can fail this if we're doing SCSI operations
1080
* from module exit (like cache flush) */
1081
try_module_get(sdev->host->hostt->module);
1085
EXPORT_SYMBOL(scsi_device_get);
1088
* scsi_device_put - release a reference to a scsi_device
1089
* @sdev: device to release a reference on.
1091
* Description: Release a reference to the scsi_device and decrements the use
1092
* count of the underlying LLDD module. The device is freed once the last
1095
void scsi_device_put(struct scsi_device *sdev)
1097
#ifdef CONFIG_MODULE_UNLOAD
1098
struct module *module = sdev->host->hostt->module;
1100
/* The module refcount will be zero if scsi_device_get()
1101
* was called from a module removal routine */
1102
if (module && module_refcount(module) != 0)
1105
put_device(&sdev->sdev_gendev);
1107
EXPORT_SYMBOL(scsi_device_put);
1109
/* helper for shost_for_each_device, see that for documentation */
1110
struct scsi_device *__scsi_iterate_devices(struct Scsi_Host *shost,
1111
struct scsi_device *prev)
1113
struct list_head *list = (prev ? &prev->siblings : &shost->__devices);
1114
struct scsi_device *next = NULL;
1115
unsigned long flags;
1117
spin_lock_irqsave(shost->host_lock, flags);
1118
while (list->next != &shost->__devices) {
1119
next = list_entry(list->next, struct scsi_device, siblings);
1120
/* skip devices that we can't get a reference to */
1121
if (!scsi_device_get(next))
1126
spin_unlock_irqrestore(shost->host_lock, flags);
1129
scsi_device_put(prev);
1132
EXPORT_SYMBOL(__scsi_iterate_devices);
1135
* starget_for_each_device - helper to walk all devices of a target
1136
* @starget: target whose devices we want to iterate over.
1137
* @data: Opaque passed to each function call.
1138
* @fn: Function to call on each device
1140
* This traverses over each device of @starget. The devices have
1141
* a reference that must be released by scsi_host_put when breaking
1144
void starget_for_each_device(struct scsi_target *starget, void *data,
1145
void (*fn)(struct scsi_device *, void *))
1147
struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
1148
struct scsi_device *sdev;
1150
shost_for_each_device(sdev, shost) {
1151
if ((sdev->channel == starget->channel) &&
1152
(sdev->id == starget->id))
1156
EXPORT_SYMBOL(starget_for_each_device);
1159
* __starget_for_each_device - helper to walk all devices of a target (UNLOCKED)
1160
* @starget: target whose devices we want to iterate over.
1161
* @data: parameter for callback @fn()
1162
* @fn: callback function that is invoked for each device
1164
* This traverses over each device of @starget. It does _not_
1165
* take a reference on the scsi_device, so the whole loop must be
1166
* protected by shost->host_lock.
1168
* Note: The only reason why drivers would want to use this is because
1169
* they need to access the device list in irq context. Otherwise you
1170
* really want to use starget_for_each_device instead.
1172
void __starget_for_each_device(struct scsi_target *starget, void *data,
1173
void (*fn)(struct scsi_device *, void *))
1175
struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
1176
struct scsi_device *sdev;
1178
__shost_for_each_device(sdev, shost) {
1179
if ((sdev->channel == starget->channel) &&
1180
(sdev->id == starget->id))
1184
EXPORT_SYMBOL(__starget_for_each_device);
1187
* __scsi_device_lookup_by_target - find a device given the target (UNLOCKED)
1188
* @starget: SCSI target pointer
1189
* @lun: SCSI Logical Unit Number
1191
* Description: Looks up the scsi_device with the specified @lun for a given
1192
* @starget. The returned scsi_device does not have an additional
1193
* reference. You must hold the host's host_lock over this call and
1194
* any access to the returned scsi_device. A scsi_device in state
1195
* SDEV_DEL is skipped.
1197
* Note: The only reason why drivers should use this is because
1198
* they need to access the device list in irq context. Otherwise you
1199
* really want to use scsi_device_lookup_by_target instead.
1201
struct scsi_device *__scsi_device_lookup_by_target(struct scsi_target *starget,
1204
struct scsi_device *sdev;
1206
list_for_each_entry(sdev, &starget->devices, same_target_siblings) {
1207
if (sdev->sdev_state == SDEV_DEL)
1209
if (sdev->lun ==lun)
1215
EXPORT_SYMBOL(__scsi_device_lookup_by_target);
1218
* scsi_device_lookup_by_target - find a device given the target
1219
* @starget: SCSI target pointer
1220
* @lun: SCSI Logical Unit Number
1222
* Description: Looks up the scsi_device with the specified @lun for a given
1223
* @starget. The returned scsi_device has an additional reference that
1224
* needs to be released with scsi_device_put once you're done with it.
1226
struct scsi_device *scsi_device_lookup_by_target(struct scsi_target *starget,
1229
struct scsi_device *sdev;
1230
struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
1231
unsigned long flags;
1233
spin_lock_irqsave(shost->host_lock, flags);
1234
sdev = __scsi_device_lookup_by_target(starget, lun);
1235
if (sdev && scsi_device_get(sdev))
1237
spin_unlock_irqrestore(shost->host_lock, flags);
1241
EXPORT_SYMBOL(scsi_device_lookup_by_target);
1244
* __scsi_device_lookup - find a device given the host (UNLOCKED)
1245
* @shost: SCSI host pointer
1246
* @channel: SCSI channel (zero if only one channel)
1247
* @id: SCSI target number (physical unit number)
1248
* @lun: SCSI Logical Unit Number
1250
* Description: Looks up the scsi_device with the specified @channel, @id, @lun
1251
* for a given host. The returned scsi_device does not have an additional
1252
* reference. You must hold the host's host_lock over this call and any access
1253
* to the returned scsi_device.
1255
* Note: The only reason why drivers would want to use this is because
1256
* they need to access the device list in irq context. Otherwise you
1257
* really want to use scsi_device_lookup instead.
1259
struct scsi_device *__scsi_device_lookup(struct Scsi_Host *shost,
1260
uint channel, uint id, uint lun)
1262
struct scsi_device *sdev;
1264
list_for_each_entry(sdev, &shost->__devices, siblings) {
1265
if (sdev->channel == channel && sdev->id == id &&
1272
EXPORT_SYMBOL(__scsi_device_lookup);
1275
* scsi_device_lookup - find a device given the host
1276
* @shost: SCSI host pointer
1277
* @channel: SCSI channel (zero if only one channel)
1278
* @id: SCSI target number (physical unit number)
1279
* @lun: SCSI Logical Unit Number
1281
* Description: Looks up the scsi_device with the specified @channel, @id, @lun
1282
* for a given host. The returned scsi_device has an additional reference that
1283
* needs to be released with scsi_device_put once you're done with it.
1285
struct scsi_device *scsi_device_lookup(struct Scsi_Host *shost,
1286
uint channel, uint id, uint lun)
1288
struct scsi_device *sdev;
1289
unsigned long flags;
1291
spin_lock_irqsave(shost->host_lock, flags);
1292
sdev = __scsi_device_lookup(shost, channel, id, lun);
1293
if (sdev && scsi_device_get(sdev))
1295
spin_unlock_irqrestore(shost->host_lock, flags);
1299
EXPORT_SYMBOL(scsi_device_lookup);
1301
MODULE_DESCRIPTION("SCSI core");
1302
MODULE_LICENSE("GPL");
1304
module_param(scsi_logging_level, int, S_IRUGO|S_IWUSR);
1305
MODULE_PARM_DESC(scsi_logging_level, "a bit mask of logging levels");
1307
static int __init init_scsi(void)
1311
error = scsi_init_queue();
1314
error = scsi_init_procfs();
1317
error = scsi_init_devinfo();
1319
goto cleanup_procfs;
1320
error = scsi_init_hosts();
1322
goto cleanup_devlist;
1323
error = scsi_init_sysctl();
1326
error = scsi_sysfs_register();
1328
goto cleanup_sysctl;
1330
scsi_netlink_init();
1332
printk(KERN_NOTICE "SCSI subsystem initialized\n");
1340
scsi_exit_devinfo();
1345
printk(KERN_ERR "SCSI subsystem failed to initialize, error = %d\n",
1350
static void __exit exit_scsi(void)
1352
scsi_netlink_exit();
1353
scsi_sysfs_unregister();
1356
scsi_exit_devinfo();
1361
subsys_initcall(init_scsi);
1362
module_exit(exit_scsi);