1 /*
2 * scsi.c Copyright (C) 1992 Drew Eckhardt
3 * Copyright (C) 1993, 1994, 1995, 1999 Eric Youngdale
4 * Copyright (C) 2002, 2003 Christoph Hellwig
5 *
6 * generic mid-level SCSI driver
7 * Initial versions: Drew Eckhardt
8 * Subsequent revisions: Eric Youngdale
9 *
10 * <drew@colorado.edu>
11 *
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>
16 *
17 * Modified by Eric Youngdale eric@andante.org or ericy@gnu.ai.mit.edu to
18 * add scatter-gather, multiple outstanding request, and other
19 * enhancements.
20 *
21 * Native multichannel, wide scsi, /proc/scsi and hot plugging
22 * support added by Michael Neuffer <mike@i-connect.net>
23 *
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>
27 * (changed to kmod)
28 *
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>
32 *
33 * Converted cli() code to spinlocks, Ingo Molnar
34 *
35 * Jiffies wrap fixes (host->resetting), 3 Dec 1998 Andrea Arcangeli
36 *
37 * out_of_space hacks, D. Gilbert (dpg) 990608
38 */
39
40 #include <linux/module.h>
41 #include <linux/moduleparam.h>
42 #include <linux/kernel.h>
43 #include <linux/sched.h>
44 #include <linux/timer.h>
45 #include <linux/string.h>
46 #include <linux/slab.h>
47 #include <linux/blkdev.h>
48 #include <linux/delay.h>
49 #include <linux/init.h>
50 #include <linux/completion.h>
51 #include <linux/devfs_fs_kernel.h>
52 #include <linux/unistd.h>
53 #include <linux/spinlock.h>
54 #include <linux/kmod.h>
55 #include <linux/interrupt.h>
56 #include <linux/notifier.h>
57 #include <linux/cpu.h>
58
59 #include <scsi/scsi.h>
60 #include <scsi/scsi_cmnd.h>
61 #include <scsi/scsi_dbg.h>
62 #include <scsi/scsi_device.h>
63 #include <scsi/scsi_eh.h>
64 #include <scsi/scsi_host.h>
65 #include <scsi/scsi_tcq.h>
66 #include <scsi/scsi_request.h>
67
68 #include "scsi_priv.h"
69 #include "scsi_logging.h"
70
71
72 /*
73 * Definitions and constants.
74 */
75
76 #define MIN_RESET_DELAY (2*HZ)
77
78 /* Do not call reset on error if we just did a reset within 15 sec. */
79 #define MIN_RESET_PERIOD (15*HZ)
80
81 /*
82 * Macro to determine the size of SCSI command. This macro takes vendor
83 * unique commands into account. SCSI commands in groups 6 and 7 are
84 * vendor unique and we will depend upon the command length being
85 * supplied correctly in cmd_len.
86 */
87 #define CDB_SIZE(cmd) (((((cmd)->cmnd[0] >> 5) & 7) < 6) ? \
88 COMMAND_SIZE((cmd)->cmnd[0]) : (cmd)->cmd_len)
89
90 /*
91 * Data declarations.
92 */
93 unsigned long scsi_pid;
94 static unsigned long serial_number;
95
96 /*
97 * Note - the initial logging level can be set here to log events at boot time.
98 * After the system is up, you may enable logging via the /proc interface.
99 */
100 unsigned int scsi_logging_level;
101 #if defined(CONFIG_SCSI_LOGGING)
102 EXPORT_SYMBOL(scsi_logging_level);
103 #endif
104
105 const char *const scsi_device_types[MAX_SCSI_DEVICE_CODE] = {
106 "Direct-Access ",
107 "Sequential-Access",
108 "Printer ",
109 "Processor ",
110 "WORM ",
111 "CD-ROM ",
112 "Scanner ",
113 "Optical Device ",
114 "Medium Changer ",
115 "Communications ",
116 "Unknown ",
117 "Unknown ",
118 "RAID ",
119 "Enclosure ",
120 };
121 EXPORT_SYMBOL(scsi_device_types);
122
123 /*
124 * Function: scsi_allocate_request
125 *
126 * Purpose: Allocate a request descriptor.
127 *
128 * Arguments: device - device for which we want a request
129 * gfp_mask - allocation flags passed to kmalloc
130 *
131 * Lock status: No locks assumed to be held. This function is SMP-safe.
132 *
133 * Returns: Pointer to request block.
134 */
135 struct scsi_request *scsi_allocate_request(struct scsi_device *sdev,
136 int gfp_mask)
137 {
138 const int offset = ALIGN(sizeof(struct scsi_request), 4);
139 const int size = offset + sizeof(struct request);
140 struct scsi_request *sreq;
141
142 sreq = kmalloc(size, gfp_mask);
143 if (likely(sreq != NULL)) {
144 memset(sreq, 0, size);
145 sreq->sr_request = (struct request *)(((char *)sreq) + offset);
146 sreq->sr_device = sdev;
147 sreq->sr_host = sdev->host;
148 sreq->sr_magic = SCSI_REQ_MAGIC;
149 sreq->sr_data_direction = DMA_BIDIRECTIONAL;
150 }
151
152 return sreq;
153 }
154 EXPORT_SYMBOL(scsi_allocate_request);
155
156 void __scsi_release_request(struct scsi_request *sreq)
157 {
158 struct request *req = sreq->sr_request;
159
160 /* unlikely because the tag was usually ended earlier by the
161 * mid-layer. However, for layering reasons ULD's don't end
162 * the tag of commands they generate. */
163 if (unlikely(blk_rq_tagged(req))) {
164 unsigned long flags;
165 struct request_queue *q = req->q;
166
167 spin_lock_irqsave(q->queue_lock, flags);
168 blk_queue_end_tag(q, req);
169 spin_unlock_irqrestore(q->queue_lock, flags);
170 }
171
172
173 if (likely(sreq->sr_command != NULL)) {
174 struct scsi_cmnd *cmd = sreq->sr_command;
175
176 sreq->sr_command = NULL;
177 scsi_next_command(cmd);
178 }
179 }
180
181 /*
182 * Function: scsi_release_request
183 *
184 * Purpose: Release a request descriptor.
185 *
186 * Arguments: sreq - request to release
187 *
188 * Lock status: No locks assumed to be held. This function is SMP-safe.
189 */
190 void scsi_release_request(struct scsi_request *sreq)
191 {
192 __scsi_release_request(sreq);
193 kfree(sreq);
194 }
195 EXPORT_SYMBOL(scsi_release_request);
196
197 struct scsi_host_cmd_pool {
198 kmem_cache_t *slab;
199 unsigned int users;
200 char *name;
201 unsigned int slab_flags;
202 unsigned int gfp_mask;
203 };
204
205 static struct scsi_host_cmd_pool scsi_cmd_pool = {
206 .name = "scsi_cmd_cache",
207 .slab_flags = SLAB_HWCACHE_ALIGN,
208 };
209
210 static struct scsi_host_cmd_pool scsi_cmd_dma_pool = {
211 .name = "scsi_cmd_cache(DMA)",
212 .slab_flags = SLAB_HWCACHE_ALIGN|SLAB_CACHE_DMA,
213 .gfp_mask = __GFP_DMA,
214 };
215
216 static DECLARE_MUTEX(host_cmd_pool_mutex);
217
218 static struct scsi_cmnd *__scsi_get_command(struct Scsi_Host *shost,
219 int gfp_mask)
220 {
221 struct scsi_cmnd *cmd;
222
223 cmd = kmem_cache_alloc(shost->cmd_pool->slab,
224 gfp_mask | shost->cmd_pool->gfp_mask);
225
226 if (unlikely(!cmd)) {
227 unsigned long flags;
228
229 spin_lock_irqsave(&shost->free_list_lock, flags);
230 if (likely(!list_empty(&shost->free_list))) {
231 cmd = list_entry(shost->free_list.next,
232 struct scsi_cmnd, list);
233 list_del_init(&cmd->list);
234 }
235 spin_unlock_irqrestore(&shost->free_list_lock, flags);
236 }
237
238 return cmd;
239 }
240
241 /*
242 * Function: scsi_get_command()
243 *
244 * Purpose: Allocate and setup a scsi command block
245 *
246 * Arguments: dev - parent scsi device
247 * gfp_mask- allocator flags
248 *
249 * Returns: The allocated scsi command structure.
250 */
251 struct scsi_cmnd *scsi_get_command(struct scsi_device *dev, int gfp_mask)
252 {
253 struct scsi_cmnd *cmd;
254
255 /* Bail if we can't get a reference to the device */
256 if (!get_device(&dev->sdev_gendev))
257 return NULL;
258
259 cmd = __scsi_get_command(dev->host, gfp_mask);
260
261 if (likely(cmd != NULL)) {
262 unsigned long flags;
263
264 memset(cmd, 0, sizeof(*cmd));
265 cmd->device = dev;
266 cmd->state = SCSI_STATE_UNUSED;
267 cmd->owner = SCSI_OWNER_NOBODY;
268 init_timer(&cmd->eh_timeout);
269 INIT_LIST_HEAD(&cmd->list);
270 spin_lock_irqsave(&dev->list_lock, flags);
271 list_add_tail(&cmd->list, &dev->cmd_list);
272 spin_unlock_irqrestore(&dev->list_lock, flags);
273 } else
274 put_device(&dev->sdev_gendev);
275
276 return cmd;
277 }
278 EXPORT_SYMBOL(scsi_get_command);
279
280 /*
281 * Function: scsi_put_command()
282 *
283 * Purpose: Free a scsi command block
284 *
285 * Arguments: cmd - command block to free
286 *
287 * Returns: Nothing.
288 *
289 * Notes: The command must not belong to any lists.
290 */
291 void scsi_put_command(struct scsi_cmnd *cmd)
292 {
293 struct scsi_device *sdev = cmd->device;
294 struct Scsi_Host *shost = sdev->host;
295 unsigned long flags;
296
297 /* serious error if the command hasn't come from a device list */
298 spin_lock_irqsave(&cmd->device->list_lock, flags);
299 BUG_ON(list_empty(&cmd->list));
300 list_del_init(&cmd->list);
301 spin_unlock(&cmd->device->list_lock);
302 /* changing locks here, don't need to restore the irq state */
303 spin_lock(&shost->free_list_lock);
304 if (unlikely(list_empty(&shost->free_list))) {
305 list_add(&cmd->list, &shost->free_list);
306 cmd = NULL;
307 }
308 spin_unlock_irqrestore(&shost->free_list_lock, flags);
309
310 if (likely(cmd != NULL))
311 kmem_cache_free(shost->cmd_pool->slab, cmd);
312
313 put_device(&sdev->sdev_gendev);
314 }
315 EXPORT_SYMBOL(scsi_put_command);
316
317 /*
318 * Function: scsi_setup_command_freelist()
319 *
320 * Purpose: Setup the command freelist for a scsi host.
321 *
322 * Arguments: shost - host to allocate the freelist for.
323 *
324 * Returns: Nothing.
325 */
326 int scsi_setup_command_freelist(struct Scsi_Host *shost)
327 {
328 struct scsi_host_cmd_pool *pool;
329 struct scsi_cmnd *cmd;
330
331 spin_lock_init(&shost->free_list_lock);
332 INIT_LIST_HEAD(&shost->free_list);
333
334 /*
335 * Select a command slab for this host and create it if not
336 * yet existant.
337 */
338 down(&host_cmd_pool_mutex);
339 pool = (shost->unchecked_isa_dma ? &scsi_cmd_dma_pool : &scsi_cmd_pool);
340 if (!pool->users) {
341 pool->slab = kmem_cache_create(pool->name,
342 sizeof(struct scsi_cmnd), 0,
343 pool->slab_flags, NULL, NULL);
344 if (!pool->slab)
345 goto fail;
346 }
347
348 pool->users++;
349 shost->cmd_pool = pool;
350 up(&host_cmd_pool_mutex);
351
352 /*
353 * Get one backup command for this host.
354 */
355 cmd = kmem_cache_alloc(shost->cmd_pool->slab,
356 GFP_KERNEL | shost->cmd_pool->gfp_mask);
357 if (!cmd)
358 goto fail2;
359 list_add(&cmd->list, &shost->free_list);
360 return 0;
361
362 fail2:
363 if (!--pool->users)
364 kmem_cache_destroy(pool->slab);
365 return -ENOMEM;
366 fail:
367 up(&host_cmd_pool_mutex);
368 return -ENOMEM;
369
370 }
371
372 /*
373 * Function: scsi_destroy_command_freelist()
374 *
375 * Purpose: Release the command freelist for a scsi host.
376 *
377 * Arguments: shost - host that's freelist is going to be destroyed
378 */
379 void scsi_destroy_command_freelist(struct Scsi_Host *shost)
380 {
381 while (!list_empty(&shost->free_list)) {
382 struct scsi_cmnd *cmd;
383
384 cmd = list_entry(shost->free_list.next, struct scsi_cmnd, list);
385 list_del_init(&cmd->list);
386 kmem_cache_free(shost->cmd_pool->slab, cmd);
387 }
388
389 down(&host_cmd_pool_mutex);
390 if (!--shost->cmd_pool->users)
391 kmem_cache_destroy(shost->cmd_pool->slab);
392 up(&host_cmd_pool_mutex);
393 }
394
395 #ifdef CONFIG_SCSI_LOGGING
396 void scsi_log_send(struct scsi_cmnd *cmd)
397 {
398 unsigned int level;
399 struct scsi_device *sdev;
400
401 /*
402 * If ML QUEUE log level is greater than or equal to:
403 *
404 * 1: nothing (match completion)
405 *
406 * 2: log opcode + command of all commands
407 *
408 * 3: same as 2 plus dump cmd address
409 *
410 * 4: same as 3 plus dump extra junk
411 */
412 if (unlikely(scsi_logging_level)) {
413 level = SCSI_LOG_LEVEL(SCSI_LOG_MLQUEUE_SHIFT,
414 SCSI_LOG_MLQUEUE_BITS);
415 if (level > 1) {
416 sdev = cmd->device;
417 printk(KERN_INFO "scsi <%d:%d:%d:%d> send ",
418 sdev->host->host_no, sdev->channel, sdev->id,
419 sdev->lun);
420 if (level > 2)
421 printk("0x%p ", cmd);
422 /*
423 * spaces to match disposition and cmd->result
424 * output in scsi_log_completion.
425 */
426 printk(" ");
427 scsi_print_command(cmd);
428 if (level > 3) {
429 printk(KERN_INFO "buffer = 0x%p, bufflen = %d,"
430 " done = 0x%p, queuecommand 0x%p\n",
431 cmd->buffer, cmd->bufflen,
432 cmd->done,
433 sdev->host->hostt->queuecommand);
434
435 }
436 }
437 }
438 }
439
440 void scsi_log_completion(struct scsi_cmnd *cmd, int disposition)
441 {
442 unsigned int level;
443 struct scsi_device *sdev;
444
445 /*
446 * If ML COMPLETE log level is greater than or equal to:
447 *
448 * 1: log disposition, result, opcode + command, and conditionally
449 * sense data for failures or non SUCCESS dispositions.
450 *
451 * 2: same as 1 but for all command completions.
452 *
453 * 3: same as 2 plus dump cmd address
454 *
455 * 4: same as 3 plus dump extra junk
456 */
457 if (unlikely(scsi_logging_level)) {
458 level = SCSI_LOG_LEVEL(SCSI_LOG_MLCOMPLETE_SHIFT,
459 SCSI_LOG_MLCOMPLETE_BITS);
460 if (((level > 0) && (cmd->result || disposition != SUCCESS)) ||
461 (level > 1)) {
462 sdev = cmd->device;
463 printk(KERN_INFO "scsi <%d:%d:%d:%d> done ",
464 sdev->host->host_no, sdev->channel, sdev->id,
465 sdev->lun);
466 if (level > 2)
467 printk("0x%p ", cmd);
468 /*
469 * Dump truncated values, so we usually fit within
470 * 80 chars.
471 */
472 switch (disposition) {
473 case SUCCESS:
474 printk("SUCCESS");
475 break;
476 case NEEDS_RETRY:
477 printk("RETRY ");
478 break;
479 case ADD_TO_MLQUEUE:
480 printk("MLQUEUE");
481 break;
482 case FAILED:
483 printk("FAILED ");
484 break;
485 case TIMEOUT_ERROR:
486 /*
487 * If called via scsi_times_out.
488 */
489 printk("TIMEOUT");
490 break;
491 default:
492 printk("UNKNOWN");
493 }
494 printk(" %8x ", cmd->result);
495 scsi_print_command(cmd);
496 if (status_byte(cmd->result) & CHECK_CONDITION) {
497 /*
498 * XXX The print_sense formatting/prefix
499 * doesn't match this function.
500 */
501 scsi_print_sense("", cmd);
502 }
503 if (level > 3) {
504 printk(KERN_INFO "scsi host busy %d failed %d\n",
505 sdev->host->host_busy,
506 sdev->host->host_failed);
507 }
508 }
509 }
510 }
511 #endif
512
513 /*
514 * Function: scsi_dispatch_command
515 *
516 * Purpose: Dispatch a command to the low-level driver.
517 *
518 * Arguments: cmd - command block we are dispatching.
519 *
520 * Notes:
521 */
522 int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
523 {
524 struct Scsi_Host *host = cmd->device->host;
525 unsigned long flags = 0;
526 unsigned long timeout;
527 int rtn = 0;
528
529 /* check if the device is still usable */
530 if (unlikely(cmd->device->sdev_state == SDEV_DEL)) {
531 /* in SDEV_DEL we error all commands. DID_NO_CONNECT
532 * returns an immediate error upwards, and signals
533 * that the device is no longer present */
534 cmd->result = DID_NO_CONNECT << 16;
535 scsi_done(cmd);
536 /* return 0 (because the command has been processed) */
537 goto out;
538 }
539
540 /* Check to see if the scsi lld put this device into state SDEV_BLOCK. */
541 if (unlikely(cmd->device->sdev_state == SDEV_BLOCK)) {
542 /*
543 * in SDEV_BLOCK, the command is just put back on the device
544 * queue. The suspend state has already blocked the queue so
545 * future requests should not occur until the device
546 * transitions out of the suspend state.
547 */
548 scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
549
550 SCSI_LOG_MLQUEUE(3, printk("queuecommand : device blocked \n"));
551
552 /*
553 * NOTE: rtn is still zero here because we don't need the
554 * queue to be plugged on return (it's already stopped)
555 */
556 goto out;
557 }
558
559 /* Assign a unique nonzero serial_number. */
560 /* XXX(hch): this is racy */
561 if (++serial_number == 0)
562 serial_number = 1;
563 cmd->serial_number = serial_number;
564 cmd->pid = scsi_pid++;
565
566 /*
567 * If SCSI-2 or lower, store the LUN value in cmnd.
568 */
569 if (cmd->device->scsi_level <= SCSI_2) {
570 cmd->cmnd[1] = (cmd->cmnd[1] & 0x1f) |
571 (cmd->device->lun << 5 & 0xe0);
572 }
573
574 /*
575 * We will wait MIN_RESET_DELAY clock ticks after the last reset so
576 * we can avoid the drive not being ready.
577 */
578 timeout = host->last_reset + MIN_RESET_DELAY;
579
580 if (host->resetting && time_before(jiffies, timeout)) {
581 int ticks_remaining = timeout - jiffies;
582 /*
583 * NOTE: This may be executed from within an interrupt
584 * handler! This is bad, but for now, it'll do. The irq
585 * level of the interrupt handler has been masked out by the
586 * platform dependent interrupt handling code already, so the
587 * sti() here will not cause another call to the SCSI host's
588 * interrupt handler (assuming there is one irq-level per
589 * host).
590 */
591 while (--ticks_remaining >= 0)
592 mdelay(1 + 999 / HZ);
593 host->resetting = 0;
594 }
595
596 scsi_add_timer(cmd, cmd->timeout_per_command, scsi_times_out);
597
598 scsi_log_send(cmd);
599
600 /*
601 * We will use a queued command if possible, otherwise we will
602 * emulate the queuing and calling of completion function ourselves.
603 */
604
605 cmd->state = SCSI_STATE_QUEUED;
606 cmd->owner = SCSI_OWNER_LOWLEVEL;
607
608 /*
609 * Before we queue this command, check if the command
610 * length exceeds what the host adapter can handle.
611 */
612 if (CDB_SIZE(cmd) > cmd->device->host->max_cmd_len) {
613 SCSI_LOG_MLQUEUE(3,
614 printk("queuecommand : command too long.\n"));
615 cmd->result = (DID_ABORT << 16);
616
617 scsi_done(cmd);
618 goto out;
619 }
620
621 spin_lock_irqsave(host->host_lock, flags);
622 if (unlikely(test_bit(SHOST_CANCEL, &host->shost_state))) {
623 cmd->result = (DID_NO_CONNECT << 16);
624 scsi_done(cmd);
625 } else {
626 rtn = host->hostt->queuecommand(cmd, scsi_done);
627 }
628 spin_unlock_irqrestore(host->host_lock, flags);
629 if (rtn) {
630 scsi_queue_insert(cmd,
631 (rtn == SCSI_MLQUEUE_DEVICE_BUSY) ?
632 rtn : SCSI_MLQUEUE_HOST_BUSY);
633 SCSI_LOG_MLQUEUE(3,
634 printk("queuecommand : request rejected\n"));
635 }
636
637 out:
638 SCSI_LOG_MLQUEUE(3, printk("leaving scsi_dispatch_cmnd()\n"));
639 return rtn;
640 }
641
642 /*
643 * Function: scsi_init_cmd_from_req
644 *
645 * Purpose: Queue a SCSI command
646 * Purpose: Initialize a struct scsi_cmnd from a struct scsi_request
647 *
648 * Arguments: cmd - command descriptor.
649 * sreq - Request from the queue.
650 *
651 * Lock status: None needed.
652 *
653 * Returns: Nothing.
654 *
655 * Notes: Mainly transfer data from the request structure to the
656 * command structure. The request structure is allocated
657 * using the normal memory allocator, and requests can pile
658 * up to more or less any depth. The command structure represents
659 * a consumable resource, as these are allocated into a pool
660 * when the SCSI subsystem initializes. The preallocation is
661 * required so that in low-memory situations a disk I/O request
662 * won't cause the memory manager to try and write out a page.
663 * The request structure is generally used by ioctls and character
664 * devices.
665 */
666 void scsi_init_cmd_from_req(struct scsi_cmnd *cmd, struct scsi_request *sreq)
667 {
668 sreq->sr_command = cmd;
669
670 cmd->owner = SCSI_OWNER_MIDLEVEL;
671 cmd->cmd_len = sreq->sr_cmd_len;
672 cmd->use_sg = sreq->sr_use_sg;
673
674 cmd->request = sreq->sr_request;
675 memcpy(cmd->data_cmnd, sreq->sr_cmnd, sizeof(cmd->data_cmnd));
676 cmd->serial_number = 0;
677 cmd->serial_number_at_timeout = 0;
678 cmd->bufflen = sreq->sr_bufflen;
679 cmd->buffer = sreq->sr_buffer;
680 cmd->retries = 0;
681 cmd->allowed = sreq->sr_allowed;
682 cmd->done = sreq->sr_done;
683 cmd->timeout_per_command = sreq->sr_timeout_per_command;
684 cmd->sc_data_direction = sreq->sr_data_direction;
685 cmd->sglist_len = sreq->sr_sglist_len;
686 cmd->underflow = sreq->sr_underflow;
687 cmd->sc_request = sreq;
688 memcpy(cmd->cmnd, sreq->sr_cmnd, sizeof(sreq->sr_cmnd));
689
690 /*
691 * Zero the sense buffer. Some host adapters automatically request
692 * sense on error. 0 is not a valid sense code.
693 */
694 memset(cmd->sense_buffer, 0, sizeof(sreq->sr_sense_buffer));
695 cmd->request_buffer = sreq->sr_buffer;
696 cmd->request_bufflen = sreq->sr_bufflen;
697 cmd->old_use_sg = cmd->use_sg;
698 if (cmd->cmd_len == 0)
699 cmd->cmd_len = COMMAND_SIZE(cmd->cmnd[0]);
700 cmd->old_cmd_len = cmd->cmd_len;
701 cmd->sc_old_data_direction = cmd->sc_data_direction;
702 cmd->old_underflow = cmd->underflow;
703
704 /*
705 * Start the timer ticking.
706 */
707 cmd->internal_timeout = NORMAL_TIMEOUT;
708 cmd->abort_reason = 0;
709 cmd->result = 0;
710
711 SCSI_LOG_MLQUEUE(3, printk("Leaving scsi_init_cmd_from_req()\n"));
712 }
713
714 /*
715 * Per-CPU I/O completion queue.
716 */
717 static DEFINE_PER_CPU(struct list_head, scsi_done_q);
718
719 /**
720 * scsi_done - Enqueue the finished SCSI command into the done queue.
721 * @cmd: The SCSI Command for which a low-level device driver (LLDD) gives
722 * ownership back to SCSI Core -- i.e. the LLDD has finished with it.
723 *
724 * This function is the mid-level's (SCSI Core) interrupt routine, which
725 * regains ownership of the SCSI command (de facto) from a LLDD, and enqueues
726 * the command to the done queue for further processing.
727 *
728 * This is the producer of the done queue who enqueues at the tail.
729 *
730 * This function is interrupt context safe.
731 */
732 void scsi_done(struct scsi_cmnd *cmd)
733 {
734 /*
735 * We don't have to worry about this one timing out any more.
736 * If we are unable to remove the timer, then the command
737 * has already timed out. In which case, we have no choice but to
738 * let the timeout function run, as we have no idea where in fact
739 * that function could really be. It might be on another processor,
740 * etc, etc.
741 */
742 if (!scsi_delete_timer(cmd))
743 return;
744 __scsi_done(cmd);
745 }
746
747 /* Private entry to scsi_done() to complete a command when the timer
748 * isn't running --- used by scsi_times_out */
749 void __scsi_done(struct scsi_cmnd *cmd)
750 {
751 unsigned long flags;
752
753 /*
754 * Set the serial numbers back to zero
755 */
756 cmd->serial_number = 0;
757 cmd->serial_number_at_timeout = 0;
758 cmd->state = SCSI_STATE_BHQUEUE;
759 cmd->owner = SCSI_OWNER_BH_HANDLER;
760
761 /*
762 * Next, enqueue the command into the done queue.
763 * It is a per-CPU queue, so we just disable local interrupts
764 * and need no spinlock.
765 */
766 local_irq_save(flags);
767 list_add_tail(&cmd->eh_entry, &__get_cpu_var(scsi_done_q));
768 raise_softirq_irqoff(SCSI_SOFTIRQ);
769 local_irq_restore(flags);
770 }
771
772 /**
773 * scsi_softirq - Perform post-interrupt processing of finished SCSI commands.
774 *
775 * This is the consumer of the done queue.
776 *
777 * This is called with all interrupts enabled. This should reduce
778 * interrupt latency, stack depth, and reentrancy of the low-level
779 * drivers.
780 */
781 static void scsi_softirq(struct softirq_action *h)
782 {
783 int disposition;
784 LIST_HEAD(local_q);
785
786 local_irq_disable();
787 list_splice_init(&__get_cpu_var(scsi_done_q), &local_q);
788 local_irq_enable();
789
790 while (!list_empty(&local_q)) {
791 struct scsi_cmnd *cmd = list_entry(local_q.next,
792 struct scsi_cmnd, eh_entry);
793 list_del_init(&cmd->eh_entry);
794
795 disposition = scsi_decide_disposition(cmd);
796 scsi_log_completion(cmd, disposition);
797 switch (disposition) {
798 case SUCCESS:
799 scsi_finish_command(cmd);
800 break;
801 case NEEDS_RETRY:
802 scsi_retry_command(cmd);
803 break;
804 case ADD_TO_MLQUEUE:
805 scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
806 break;
807 default:
808 if (!scsi_eh_scmd_add(cmd, 0))
809 scsi_finish_command(cmd);
810 }
811 }
812 }
813
814 /*
815 * Function: scsi_retry_command
816 *
817 * Purpose: Send a command back to the low level to be retried.
818 *
819 * Notes: This command is always executed in the context of the
820 * bottom half handler, or the error handler thread. Low
821 * level drivers should not become re-entrant as a result of
822 * this.
823 */
824 int scsi_retry_command(struct scsi_cmnd *cmd)
825 {
826 /*
827 * Restore the SCSI command state.
828 */
829 scsi_setup_cmd_retry(cmd);
830
831 /*
832 * Zero the sense information from the last time we tried
833 * this command.
834 */
835 memset(cmd->sense_buffer, 0, sizeof(cmd->sense_buffer));
836
837 return scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY);
838 }
839
840 /*
841 * Function: scsi_finish_command
842 *
843 * Purpose: Pass command off to upper layer for finishing of I/O
844 * request, waking processes that are waiting on results,
845 * etc.
846 */
847 void scsi_finish_command(struct scsi_cmnd *cmd)
848 {
849 struct scsi_device *sdev = cmd->device;
850 struct Scsi_Host *shost = sdev->host;
851 struct scsi_request *sreq;
852
853 scsi_device_unbusy(sdev);
854
855 /*
856 * Clear the flags which say that the device/host is no longer
857 * capable of accepting new commands. These are set in scsi_queue.c
858 * for both the queue full condition on a device, and for a
859 * host full condition on the host.
860 *
861 * XXX(hch): What about locking?
862 */
863 shost->host_blocked = 0;
864 sdev->device_blocked = 0;
865
866 /*
867 * If we have valid sense information, then some kind of recovery
868 * must have taken place. Make a note of this.
869 */
870 if (SCSI_SENSE_VALID(cmd))
871 cmd->result |= (DRIVER_SENSE << 24);
872
873 SCSI_LOG_MLCOMPLETE(4, printk("Notifying upper driver of completion "
874 "for device %d %x\n", sdev->id, cmd->result));
875
876 cmd->owner = SCSI_OWNER_HIGHLEVEL;
877 cmd->state = SCSI_STATE_FINISHED;
878
879 /*
880 * We can get here with use_sg=0, causing a panic in the upper level
881 */
882 cmd->use_sg = cmd->old_use_sg;
883
884 /*
885 * If there is an associated request structure, copy the data over
886 * before we call the completion function.
887 */
888 sreq = cmd->sc_request;
889 if (sreq) {
890 sreq->sr_result = sreq->sr_command->result;
891 if (sreq->sr_result) {
892 memcpy(sreq->sr_sense_buffer,
893 sreq->sr_command->sense_buffer,
894 sizeof(sreq->sr_sense_buffer));
895 }
896 }
897
898 cmd->done(cmd);
899 }
900 EXPORT_SYMBOL(scsi_finish_command);
901
902 /*
903 * Function: scsi_adjust_queue_depth()
904 *
905 * Purpose: Allow low level drivers to tell us to change the queue depth
906 * on a specific SCSI device
907 *
908 * Arguments: sdev - SCSI Device in question
909 * tagged - Do we use tagged queueing (non-0) or do we treat
910 * this device as an untagged device (0)
911 * tags - Number of tags allowed if tagged queueing enabled,
912 * or number of commands the low level driver can
913 * queue up in non-tagged mode (as per cmd_per_lun).
914 *
915 * Returns: Nothing
916 *
917 * Lock Status: None held on entry
918 *
919 * Notes: Low level drivers may call this at any time and we will do
920 * the right thing depending on whether or not the device is
921 * currently active and whether or not it even has the
922 * command blocks built yet.
923 *
924 * XXX(hch): What exactly is device_request_lock trying to protect?
925 */
926 void scsi_adjust_queue_depth(struct scsi_device *sdev, int tagged, int tags)
927 {
928 static DEFINE_SPINLOCK(device_request_lock);
929 unsigned long flags;
930
931 /*
932 * refuse to set tagged depth to an unworkable size
933 */
934 if (tags <= 0)
935 return;
936
937 spin_lock_irqsave(&device_request_lock, flags);
938 spin_lock(sdev->request_queue->queue_lock);
939
940 /* Check to see if the queue is managed by the block layer
941 * if it is, and we fail to adjust the depth, exit */
942 if (blk_queue_tagged(sdev->request_queue) &&
943 blk_queue_resize_tags(sdev->request_queue, tags) != 0)
944 goto out;
945
946 sdev->queue_depth = tags;
947 switch (tagged) {
948 case MSG_ORDERED_TAG:
949 sdev->ordered_tags = 1;
950 sdev->simple_tags = 1;
951 break;
952 case MSG_SIMPLE_TAG:
953 sdev->ordered_tags = 0;
954 sdev->simple_tags = 1;
955 break;
956 default:
957 printk(KERN_WARNING "(scsi%d:%d:%d:%d) "
958 "scsi_adjust_queue_depth, bad queue type, "
959 "disabled\n", sdev->host->host_no,
960 sdev->channel, sdev->id, sdev->lun);
961 case 0:
962 sdev->ordered_tags = sdev->simple_tags = 0;
963 sdev->queue_depth = tags;
964 break;
965 }
966 out:
967 spin_unlock(sdev->request_queue->queue_lock);
968 spin_unlock_irqrestore(&device_request_lock, flags);
969 }
970 EXPORT_SYMBOL(scsi_adjust_queue_depth);
971
972 /*
973 * Function: scsi_track_queue_full()
974 *
975 * Purpose: This function will track successive QUEUE_FULL events on a
976 * specific SCSI device to determine if and when there is a
977 * need to adjust the queue depth on the device.
978 *
979 * Arguments: sdev - SCSI Device in question
980 * depth - Current number of outstanding SCSI commands on
981 * this device, not counting the one returned as
982 * QUEUE_FULL.
983 *
984 * Returns: 0 - No change needed
985 * >0 - Adjust queue depth to this new depth
986 * -1 - Drop back to untagged operation using host->cmd_per_lun
987 * as the untagged command depth
988 *
989 * Lock Status: None held on entry
990 *
991 * Notes: Low level drivers may call this at any time and we will do
992 * "The Right Thing." We are interrupt context safe.
993 */
994 int scsi_track_queue_full(struct scsi_device *sdev, int depth)
995 {
996 if ((jiffies >> 4) == sdev->last_queue_full_time)
997 return 0;
998
999 sdev->last_queue_full_time = (jiffies >> 4);
1000 if (sdev->last_queue_full_depth != depth) {
1001 sdev->last_queue_full_count = 1;
1002 sdev->last_queue_full_depth = depth;
1003 } else {
1004 sdev->last_queue_full_count++;
1005 }
1006
1007 if (sdev->last_queue_full_count <= 10)
1008 return 0;
1009 if (sdev->last_queue_full_depth < 8) {
1010 /* Drop back to untagged */
1011 scsi_adjust_queue_depth(sdev, 0, sdev->host->cmd_per_lun);
1012 return -1;
1013 }
1014
1015 if (sdev->ordered_tags)
1016 scsi_adjust_queue_depth(sdev, MSG_ORDERED_TAG, depth);
1017 else
1018 scsi_adjust_queue_depth(sdev, MSG_SIMPLE_TAG, depth);
1019 return depth;
1020 }
1021 EXPORT_SYMBOL(scsi_track_queue_full);
1022
1023 /**
1024 * scsi_device_get - get an addition reference to a scsi_device
1025 * @sdev: device to get a reference to
1026 *
1027 * Gets a reference to the scsi_device and increments the use count
1028 * of the underlying LLDD module. You must hold host_lock of the
1029 * parent Scsi_Host or already have a reference when calling this.
1030 */
1031 int scsi_device_get(struct scsi_device *sdev)
1032 {
1033 if (sdev->sdev_state == SDEV_DEL || sdev->sdev_state == SDEV_CANCEL)
1034 return -ENXIO;
1035 if (!get_device(&sdev->sdev_gendev))
1036 return -ENXIO;
1037 if (!try_module_get(sdev->host->hostt->module)) {
1038 put_device(&sdev->sdev_gendev);
1039 return -ENXIO;
1040 }
1041 return 0;
1042 }
1043 EXPORT_SYMBOL(scsi_device_get);
1044
1045 /**
1046 * scsi_device_put - release a reference to a scsi_device
1047 * @sdev: device to release a reference on.
1048 *
1049 * Release a reference to the scsi_device and decrements the use count
1050 * of the underlying LLDD module. The device is freed once the last
1051 * user vanishes.
1052 */
1053 void scsi_device_put(struct scsi_device *sdev)
1054 {
1055 module_put(sdev->host->hostt->module);
1056 put_device(&sdev->sdev_gendev);
1057 }
1058 EXPORT_SYMBOL(scsi_device_put);
1059
1060 /* helper for shost_for_each_device, thus not documented */
1061 struct scsi_device *__scsi_iterate_devices(struct Scsi_Host *shost,
1062 struct scsi_device *prev)
1063 {
1064 struct list_head *list = (prev ? &prev->siblings : &shost->__devices);
1065 struct scsi_device *next = NULL;
1066 unsigned long flags;
1067
1068 spin_lock_irqsave(shost->host_lock, flags);
1069 while (list->next != &shost->__devices) {
1070 next = list_entry(list->next, struct scsi_device, siblings);
1071 /* skip devices that we can't get a reference to */
1072 if (!scsi_device_get(next))
1073 break;
1074 next = NULL;
1075 list = list->next;
1076 }
1077 spin_unlock_irqrestore(shost->host_lock, flags);
1078
1079 if (prev)
1080 scsi_device_put(prev);
1081 return next;
1082 }
1083 EXPORT_SYMBOL(__scsi_iterate_devices);
1084
1085 /**
1086 * starget_for_each_device - helper to walk all devices of a target
1087 * @starget: target whose devices we want to iterate over.
1088 *
1089 * This traverses over each devices of @shost. The devices have
1090 * a reference that must be released by scsi_host_put when breaking
1091 * out of the loop.
1092 */
1093 void starget_for_each_device(struct scsi_target *starget, void * data,
1094 void (*fn)(struct scsi_device *, void *))
1095 {
1096 struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
1097 struct scsi_device *sdev;
1098
1099 shost_for_each_device(sdev, shost) {
1100 if ((sdev->channel == starget->channel) &&
1101 (sdev->id == starget->id))
1102 fn(sdev, data);
1103 }
1104 }
1105 EXPORT_SYMBOL(starget_for_each_device);
1106
1107 /**
1108 * scsi_device_lookup - find a device given the host (UNLOCKED)
1109 * @shost: SCSI host pointer
1110 * @channel: SCSI channel (zero if only one channel)
1111 * @pun: SCSI target number (physical unit number)
1112 * @lun: SCSI Logical Unit Number
1113 *
1114 * Looks up the scsi_device with the specified @channel, @id, @lun for a
1115 * give host. The returned scsi_device does not have an additional reference.
1116 * You must hold the host's host_lock over this call and any access to the
1117 * returned scsi_device.
1118 *
1119 * Note: The only reason why drivers would want to use this is because
1120 * they're need to access the device list in irq context. Otherwise you
1121 * really want to use scsi_device_lookup instead.
1122 **/
1123 struct scsi_device *__scsi_device_lookup(struct Scsi_Host *shost,
1124 uint channel, uint id, uint lun)
1125 {
1126 struct scsi_device *sdev;
1127
1128 list_for_each_entry(sdev, &shost->__devices, siblings) {
1129 if (sdev->channel == channel && sdev->id == id &&
1130 sdev->lun ==lun)
1131 return sdev;
1132 }
1133
1134 return NULL;
1135 }
1136 EXPORT_SYMBOL(__scsi_device_lookup);
1137
1138 /**
1139 * scsi_device_lookup - find a device given the host
1140 * @shost: SCSI host pointer
1141 * @channel: SCSI channel (zero if only one channel)
1142 * @id: SCSI target number (physical unit number)
1143 * @lun: SCSI Logical Unit Number
1144 *
1145 * Looks up the scsi_device with the specified @channel, @id, @lun for a
1146 * give host. The returned scsi_device has an additional reference that
1147 * needs to be release with scsi_host_put once you're done with it.
1148 **/
1149 struct scsi_device *scsi_device_lookup(struct Scsi_Host *shost,
1150 uint channel, uint id, uint lun)
1151 {
1152 struct scsi_device *sdev;
1153 unsigned long flags;
1154
1155 spin_lock_irqsave(shost->host_lock, flags);
1156 sdev = __scsi_device_lookup(shost, channel, id, lun);
1157 if (sdev && scsi_device_get(sdev))
1158 sdev = NULL;
1159 spin_unlock_irqrestore(shost->host_lock, flags);
1160
1161 return sdev;
1162 }
1163 EXPORT_SYMBOL(scsi_device_lookup);
1164
1165 /**
1166 * scsi_device_cancel - cancel outstanding IO to this device
1167 * @sdev: Pointer to struct scsi_device
1168 * @recovery: Boolean instructing function to recover device or not.
1169 *
1170 **/
1171 int scsi_device_cancel(struct scsi_device *sdev, int recovery)
1172 {
1173 struct scsi_cmnd *scmd;
1174 LIST_HEAD(active_list);
1175 struct list_head *lh, *lh_sf;
1176 unsigned long flags;
1177
1178 scsi_device_set_state(sdev, SDEV_CANCEL);
1179
1180 spin_lock_irqsave(&sdev->list_lock, flags);
1181 list_for_each_entry(scmd, &sdev->cmd_list, list) {
1182 if (scmd->request && scmd->request->rq_status != RQ_INACTIVE) {
1183 /*
1184 * If we are unable to remove the timer, it means
1185 * that the command has already timed out or
1186 * finished.
1187 */
1188 if (!scsi_delete_timer(scmd))
1189 continue;
1190 list_add_tail(&scmd->eh_entry, &active_list);
1191 }
1192 }
1193 spin_unlock_irqrestore(&sdev->list_lock, flags);
1194
1195 if (!list_empty(&active_list)) {
1196 list_for_each_safe(lh, lh_sf, &active_list) {
1197 scmd = list_entry(lh, struct scsi_cmnd, eh_entry);
1198 list_del_init(lh);
1199 if (recovery) {
1200 scsi_eh_scmd_add(scmd, SCSI_EH_CANCEL_CMD);
1201 } else {
1202 scmd->result = (DID_ABORT << 16);
1203 scsi_finish_command(scmd);
1204 }
1205 }
1206 }
1207
1208 return 0;
1209 }
1210 EXPORT_SYMBOL(scsi_device_cancel);
1211
1212 #ifdef CONFIG_HOTPLUG_CPU
1213 static int scsi_cpu_notify(struct notifier_block *self,
1214 unsigned long action, void *hcpu)
1215 {
1216 int cpu = (unsigned long)hcpu;
1217
1218 switch(action) {
1219 case CPU_DEAD:
1220 /* Drain scsi_done_q. */
1221 local_irq_disable();
1222 list_splice_init(&per_cpu(scsi_done_q, cpu),
1223 &__get_cpu_var(scsi_done_q));
1224 raise_softirq_irqoff(SCSI_SOFTIRQ);
1225 local_irq_enable();
1226 break;
1227 default:
1228 break;
1229 }
1230 return NOTIFY_OK;
1231 }
1232
1233 static struct notifier_block __devinitdata scsi_cpu_nb = {
1234 .notifier_call = scsi_cpu_notify,
1235 };
1236
1237 #define register_scsi_cpu() register_cpu_notifier(&scsi_cpu_nb)
1238 #define unregister_scsi_cpu() unregister_cpu_notifier(&scsi_cpu_nb)
1239 #else
1240 #define register_scsi_cpu()
1241 #define unregister_scsi_cpu()
1242 #endif /* CONFIG_HOTPLUG_CPU */
1243
1244 MODULE_DESCRIPTION("SCSI core");
1245 MODULE_LICENSE("GPL");
1246
1247 module_param(scsi_logging_level, int, S_IRUGO|S_IWUSR);
1248 MODULE_PARM_DESC(scsi_logging_level, "a bit mask of logging levels");
1249
1250 static int __init init_scsi(void)
1251 {
1252 int error, i;
1253
1254 error = scsi_init_queue();
1255 if (error)
1256 return error;
1257 error = scsi_init_procfs();
1258 if (error)
1259 goto cleanup_queue;
1260 error = scsi_init_devinfo();
1261 if (error)
1262 goto cleanup_procfs;
1263 error = scsi_init_hosts();
1264 if (error)
1265 goto cleanup_devlist;
1266 error = scsi_init_sysctl();
1267 if (error)
1268 goto cleanup_hosts;
1269 error = scsi_sysfs_register();
1270 if (error)
1271 goto cleanup_sysctl;
1272
1273 for (i = 0; i < NR_CPUS; i++)
1274 INIT_LIST_HEAD(&per_cpu(scsi_done_q, i));
1275
1276 devfs_mk_dir("scsi");
1277 open_softirq(SCSI_SOFTIRQ, scsi_softirq, NULL);
1278 register_scsi_cpu();
1279 printk(KERN_NOTICE "SCSI subsystem initialized\n");
1280 return 0;
1281
1282 cleanup_sysctl:
1283 scsi_exit_sysctl();
1284 cleanup_hosts:
1285 scsi_exit_hosts();
1286 cleanup_devlist:
1287 scsi_exit_devinfo();
1288 cleanup_procfs:
1289 scsi_exit_procfs();
1290 cleanup_queue:
1291 scsi_exit_queue();
1292 printk(KERN_ERR "SCSI subsystem failed to initialize, error = %d\n",
1293 -error);
1294 return error;
1295 }
1296
1297 static void __exit exit_scsi(void)
1298 {
1299 scsi_sysfs_unregister();
1300 scsi_exit_sysctl();
1301 scsi_exit_hosts();
1302 scsi_exit_devinfo();
1303 devfs_remove("scsi");
1304 scsi_exit_procfs();
1305 scsi_exit_queue();
1306 unregister_scsi_cpu();
1307 }
1308
1309 subsys_initcall(init_scsi);
1310 module_exit(exit_scsi);
1311
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