Merge remote-tracking branch 'origin/dev/sumit-linux-3.10.96' into TOT-merge
[linux-3.10.git] / drivers / scsi / scsi_error.c
1 /*
2  *  scsi_error.c Copyright (C) 1997 Eric Youngdale
3  *
4  *  SCSI error/timeout handling
5  *      Initial versions: Eric Youngdale.  Based upon conversations with
6  *                        Leonard Zubkoff and David Miller at Linux Expo,
7  *                        ideas originating from all over the place.
8  *
9  *      Restructured scsi_unjam_host and associated functions.
10  *      September 04, 2002 Mike Anderson (andmike@us.ibm.com)
11  *
12  *      Forward port of Russell King's (rmk@arm.linux.org.uk) changes and
13  *      minor cleanups.
14  *      September 30, 2002 Mike Anderson (andmike@us.ibm.com)
15  */
16
17 #include <linux/module.h>
18 #include <linux/sched.h>
19 #include <linux/gfp.h>
20 #include <linux/timer.h>
21 #include <linux/string.h>
22 #include <linux/kernel.h>
23 #include <linux/freezer.h>
24 #include <linux/kthread.h>
25 #include <linux/interrupt.h>
26 #include <linux/blkdev.h>
27 #include <linux/delay.h>
28 #include <linux/jiffies.h>
29
30 #include <scsi/scsi.h>
31 #include <scsi/scsi_cmnd.h>
32 #include <scsi/scsi_dbg.h>
33 #include <scsi/scsi_device.h>
34 #include <scsi/scsi_driver.h>
35 #include <scsi/scsi_eh.h>
36 #include <scsi/scsi_transport.h>
37 #include <scsi/scsi_host.h>
38 #include <scsi/scsi_ioctl.h>
39
40 #include "scsi_priv.h"
41 #include "scsi_logging.h"
42 #include "scsi_transport_api.h"
43
44 #include <trace/events/scsi.h>
45
46 static void scsi_eh_done(struct scsi_cmnd *scmd);
47
48 #define SENSE_TIMEOUT           (10*HZ)
49
50 /*
51  * These should *probably* be handled by the host itself.
52  * Since it is allowed to sleep, it probably should.
53  */
54 #define BUS_RESET_SETTLE_TIME   (10)
55 #define HOST_RESET_SETTLE_TIME  (10)
56
57 static int scsi_eh_try_stu(struct scsi_cmnd *scmd);
58
59 /* called with shost->host_lock held */
60 void scsi_eh_wakeup(struct Scsi_Host *shost)
61 {
62         if (shost->host_busy == shost->host_failed) {
63                 trace_scsi_eh_wakeup(shost);
64                 wake_up_process(shost->ehandler);
65                 SCSI_LOG_ERROR_RECOVERY(5,
66                                 printk("Waking error handler thread\n"));
67         }
68 }
69
70 /**
71  * scsi_schedule_eh - schedule EH for SCSI host
72  * @shost:      SCSI host to invoke error handling on.
73  *
74  * Schedule SCSI EH without scmd.
75  */
76 void scsi_schedule_eh(struct Scsi_Host *shost)
77 {
78         unsigned long flags;
79
80         spin_lock_irqsave(shost->host_lock, flags);
81
82         if (scsi_host_set_state(shost, SHOST_RECOVERY) == 0 ||
83             scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY) == 0) {
84                 shost->host_eh_scheduled++;
85                 scsi_eh_wakeup(shost);
86         }
87
88         spin_unlock_irqrestore(shost->host_lock, flags);
89 }
90 EXPORT_SYMBOL_GPL(scsi_schedule_eh);
91
92 /**
93  * scsi_eh_scmd_add - add scsi cmd to error handling.
94  * @scmd:       scmd to run eh on.
95  * @eh_flag:    optional SCSI_EH flag.
96  *
97  * Return value:
98  *      0 on failure.
99  */
100 int scsi_eh_scmd_add(struct scsi_cmnd *scmd, int eh_flag)
101 {
102         struct Scsi_Host *shost = scmd->device->host;
103         unsigned long flags;
104         int ret = 0;
105
106         if (!shost->ehandler)
107                 return 0;
108
109         spin_lock_irqsave(shost->host_lock, flags);
110         if (scsi_host_set_state(shost, SHOST_RECOVERY))
111                 if (scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY))
112                         goto out_unlock;
113
114         ret = 1;
115         scmd->eh_eflags |= eh_flag;
116         list_add_tail(&scmd->eh_entry, &shost->eh_cmd_q);
117         shost->host_failed++;
118         scsi_eh_wakeup(shost);
119  out_unlock:
120         spin_unlock_irqrestore(shost->host_lock, flags);
121         return ret;
122 }
123
124 /**
125  * scsi_times_out - Timeout function for normal scsi commands.
126  * @req:        request that is timing out.
127  *
128  * Notes:
129  *     We do not need to lock this.  There is the potential for a race
130  *     only in that the normal completion handling might run, but if the
131  *     normal completion function determines that the timer has already
132  *     fired, then it mustn't do anything.
133  */
134 enum blk_eh_timer_return scsi_times_out(struct request *req)
135 {
136         struct scsi_cmnd *scmd = req->special;
137         enum blk_eh_timer_return rtn = BLK_EH_NOT_HANDLED;
138         struct Scsi_Host *host = scmd->device->host;
139
140         trace_scsi_dispatch_cmd_timeout(scmd);
141         scsi_log_completion(scmd, TIMEOUT_ERROR);
142
143         if (host->transportt->eh_timed_out)
144                 rtn = host->transportt->eh_timed_out(scmd);
145         else if (host->hostt->eh_timed_out)
146                 rtn = host->hostt->eh_timed_out(scmd);
147
148         scmd->result |= DID_TIME_OUT << 16;
149
150         if (unlikely(rtn == BLK_EH_NOT_HANDLED &&
151                      !scsi_eh_scmd_add(scmd, SCSI_EH_CANCEL_CMD)))
152                 rtn = BLK_EH_HANDLED;
153
154         return rtn;
155 }
156
157 /**
158  * scsi_block_when_processing_errors - Prevent cmds from being queued.
159  * @sdev:       Device on which we are performing recovery.
160  *
161  * Description:
162  *     We block until the host is out of error recovery, and then check to
163  *     see whether the host or the device is offline.
164  *
165  * Return value:
166  *     0 when dev was taken offline by error recovery. 1 OK to proceed.
167  */
168 int scsi_block_when_processing_errors(struct scsi_device *sdev)
169 {
170         int online;
171
172         wait_event(sdev->host->host_wait, !scsi_host_in_recovery(sdev->host));
173
174         online = scsi_device_online(sdev);
175
176         SCSI_LOG_ERROR_RECOVERY(5, printk("%s: rtn: %d\n", __func__,
177                                           online));
178
179         return online;
180 }
181 EXPORT_SYMBOL(scsi_block_when_processing_errors);
182
183 #ifdef CONFIG_SCSI_LOGGING
184 /**
185  * scsi_eh_prt_fail_stats - Log info on failures.
186  * @shost:      scsi host being recovered.
187  * @work_q:     Queue of scsi cmds to process.
188  */
189 static inline void scsi_eh_prt_fail_stats(struct Scsi_Host *shost,
190                                           struct list_head *work_q)
191 {
192         struct scsi_cmnd *scmd;
193         struct scsi_device *sdev;
194         int total_failures = 0;
195         int cmd_failed = 0;
196         int cmd_cancel = 0;
197         int devices_failed = 0;
198
199         shost_for_each_device(sdev, shost) {
200                 list_for_each_entry(scmd, work_q, eh_entry) {
201                         if (scmd->device == sdev) {
202                                 ++total_failures;
203                                 if (scmd->eh_eflags & SCSI_EH_CANCEL_CMD)
204                                         ++cmd_cancel;
205                                 else
206                                         ++cmd_failed;
207                         }
208                 }
209
210                 if (cmd_cancel || cmd_failed) {
211                         SCSI_LOG_ERROR_RECOVERY(3,
212                                 sdev_printk(KERN_INFO, sdev,
213                                             "%s: cmds failed: %d, cancel: %d\n",
214                                             __func__, cmd_failed,
215                                             cmd_cancel));
216                         cmd_cancel = 0;
217                         cmd_failed = 0;
218                         ++devices_failed;
219                 }
220         }
221
222         SCSI_LOG_ERROR_RECOVERY(2, printk("Total of %d commands on %d"
223                                           " devices require eh work\n",
224                                    total_failures, devices_failed));
225 }
226 #endif
227
228 /**
229  * scsi_check_sense - Examine scsi cmd sense
230  * @scmd:       Cmd to have sense checked.
231  *
232  * Return value:
233  *      SUCCESS or FAILED or NEEDS_RETRY or TARGET_ERROR
234  *
235  * Notes:
236  *      When a deferred error is detected the current command has
237  *      not been executed and needs retrying.
238  */
239 static int scsi_check_sense(struct scsi_cmnd *scmd)
240 {
241         struct scsi_device *sdev = scmd->device;
242         struct scsi_sense_hdr sshdr;
243
244         if (! scsi_command_normalize_sense(scmd, &sshdr))
245                 return FAILED;  /* no valid sense data */
246
247         if (scmd->cmnd[0] == TEST_UNIT_READY && scmd->scsi_done != scsi_eh_done)
248                 /*
249                  * nasty: for mid-layer issued TURs, we need to return the
250                  * actual sense data without any recovery attempt.  For eh
251                  * issued ones, we need to try to recover and interpret
252                  */
253                 return SUCCESS;
254
255         if (scsi_sense_is_deferred(&sshdr))
256                 return NEEDS_RETRY;
257
258         if (sdev->scsi_dh_data && sdev->scsi_dh_data->scsi_dh &&
259                         sdev->scsi_dh_data->scsi_dh->check_sense) {
260                 int rc;
261
262                 rc = sdev->scsi_dh_data->scsi_dh->check_sense(sdev, &sshdr);
263                 if (rc != SCSI_RETURN_NOT_HANDLED)
264                         return rc;
265                 /* handler does not care. Drop down to default handling */
266         }
267
268         /*
269          * Previous logic looked for FILEMARK, EOM or ILI which are
270          * mainly associated with tapes and returned SUCCESS.
271          */
272         if (sshdr.response_code == 0x70) {
273                 /* fixed format */
274                 if (scmd->sense_buffer[2] & 0xe0)
275                         return SUCCESS;
276         } else {
277                 /*
278                  * descriptor format: look for "stream commands sense data
279                  * descriptor" (see SSC-3). Assume single sense data
280                  * descriptor. Ignore ILI from SBC-2 READ LONG and WRITE LONG.
281                  */
282                 if ((sshdr.additional_length > 3) &&
283                     (scmd->sense_buffer[8] == 0x4) &&
284                     (scmd->sense_buffer[11] & 0xe0))
285                         return SUCCESS;
286         }
287
288         switch (sshdr.sense_key) {
289         case NO_SENSE:
290                 return SUCCESS;
291         case RECOVERED_ERROR:
292                 return /* soft_error */ SUCCESS;
293
294         case ABORTED_COMMAND:
295                 if (sshdr.asc == 0x10) /* DIF */
296                         return SUCCESS;
297
298                 return NEEDS_RETRY;
299         case NOT_READY:
300         case UNIT_ATTENTION:
301                 /*
302                  * if we are expecting a cc/ua because of a bus reset that we
303                  * performed, treat this just as a retry.  otherwise this is
304                  * information that we should pass up to the upper-level driver
305                  * so that we can deal with it there.
306                  */
307                 if (scmd->device->expecting_cc_ua) {
308                         /*
309                          * Because some device does not queue unit
310                          * attentions correctly, we carefully check
311                          * additional sense code and qualifier so as
312                          * not to squash media change unit attention.
313                          */
314                         if (sshdr.asc != 0x28 || sshdr.ascq != 0x00) {
315                                 scmd->device->expecting_cc_ua = 0;
316                                 return NEEDS_RETRY;
317                         }
318                 }
319                 /*
320                  * if the device is in the process of becoming ready, we
321                  * should retry.
322                  */
323                 if ((sshdr.asc == 0x04) && (sshdr.ascq == 0x01))
324                         return NEEDS_RETRY;
325                 /*
326                  * if the device is not started, we need to wake
327                  * the error handler to start the motor
328                  */
329                 if (scmd->device->allow_restart &&
330                     (sshdr.asc == 0x04) && (sshdr.ascq == 0x02))
331                         return FAILED;
332
333                 if (sshdr.asc == 0x3f && sshdr.ascq == 0x0e)
334                         scmd_printk(KERN_WARNING, scmd,
335                                     "Warning! Received an indication that the "
336                                     "LUN assignments on this target have "
337                                     "changed. The Linux SCSI layer does not "
338                                     "automatically remap LUN assignments.\n");
339                 else if (sshdr.asc == 0x3f)
340                         scmd_printk(KERN_WARNING, scmd,
341                                     "Warning! Received an indication that the "
342                                     "operating parameters on this target have "
343                                     "changed. The Linux SCSI layer does not "
344                                     "automatically adjust these parameters.\n");
345
346                 if (sshdr.asc == 0x38 && sshdr.ascq == 0x07)
347                         scmd_printk(KERN_WARNING, scmd,
348                                     "Warning! Received an indication that the "
349                                     "LUN reached a thin provisioning soft "
350                                     "threshold.\n");
351
352                 /*
353                  * Pass the UA upwards for a determination in the completion
354                  * functions.
355                  */
356                 return SUCCESS;
357
358                 /* these are not supported */
359         case COPY_ABORTED:
360         case VOLUME_OVERFLOW:
361         case MISCOMPARE:
362         case BLANK_CHECK:
363         case DATA_PROTECT:
364                 return TARGET_ERROR;
365
366         case MEDIUM_ERROR:
367                 if (sshdr.asc == 0x11 || /* UNRECOVERED READ ERR */
368                     sshdr.asc == 0x13 || /* AMNF DATA FIELD */
369                     sshdr.asc == 0x14) { /* RECORD NOT FOUND */
370                         return TARGET_ERROR;
371                 }
372                 return NEEDS_RETRY;
373
374         case HARDWARE_ERROR:
375                 if (scmd->device->retry_hwerror)
376                         return ADD_TO_MLQUEUE;
377                 else
378                         return TARGET_ERROR;
379
380         case ILLEGAL_REQUEST:
381                 if (sshdr.asc == 0x20 || /* Invalid command operation code */
382                     sshdr.asc == 0x21 || /* Logical block address out of range */
383                     sshdr.asc == 0x24 || /* Invalid field in cdb */
384                     sshdr.asc == 0x26) { /* Parameter value invalid */
385                         return TARGET_ERROR;
386                 }
387                 return SUCCESS;
388
389         default:
390                 return SUCCESS;
391         }
392 }
393
394 static void scsi_handle_queue_ramp_up(struct scsi_device *sdev)
395 {
396         struct scsi_host_template *sht = sdev->host->hostt;
397         struct scsi_device *tmp_sdev;
398
399         if (!sht->change_queue_depth ||
400             sdev->queue_depth >= sdev->max_queue_depth)
401                 return;
402
403         if (time_before(jiffies,
404             sdev->last_queue_ramp_up + sdev->queue_ramp_up_period))
405                 return;
406
407         if (time_before(jiffies,
408             sdev->last_queue_full_time + sdev->queue_ramp_up_period))
409                 return;
410
411         /*
412          * Walk all devices of a target and do
413          * ramp up on them.
414          */
415         shost_for_each_device(tmp_sdev, sdev->host) {
416                 if (tmp_sdev->channel != sdev->channel ||
417                     tmp_sdev->id != sdev->id ||
418                     tmp_sdev->queue_depth == sdev->max_queue_depth)
419                         continue;
420                 /*
421                  * call back into LLD to increase queue_depth by one
422                  * with ramp up reason code.
423                  */
424                 sht->change_queue_depth(tmp_sdev, tmp_sdev->queue_depth + 1,
425                                         SCSI_QDEPTH_RAMP_UP);
426                 sdev->last_queue_ramp_up = jiffies;
427         }
428 }
429
430 static void scsi_handle_queue_full(struct scsi_device *sdev)
431 {
432         struct scsi_host_template *sht = sdev->host->hostt;
433         struct scsi_device *tmp_sdev;
434
435         if (!sht->change_queue_depth)
436                 return;
437
438         shost_for_each_device(tmp_sdev, sdev->host) {
439                 if (tmp_sdev->channel != sdev->channel ||
440                     tmp_sdev->id != sdev->id)
441                         continue;
442                 /*
443                  * We do not know the number of commands that were at
444                  * the device when we got the queue full so we start
445                  * from the highest possible value and work our way down.
446                  */
447                 sht->change_queue_depth(tmp_sdev, tmp_sdev->queue_depth - 1,
448                                         SCSI_QDEPTH_QFULL);
449         }
450 }
451
452 /**
453  * scsi_eh_completed_normally - Disposition a eh cmd on return from LLD.
454  * @scmd:       SCSI cmd to examine.
455  *
456  * Notes:
457  *    This is *only* called when we are examining the status of commands
458  *    queued during error recovery.  the main difference here is that we
459  *    don't allow for the possibility of retries here, and we are a lot
460  *    more restrictive about what we consider acceptable.
461  */
462 static int scsi_eh_completed_normally(struct scsi_cmnd *scmd)
463 {
464         /*
465          * first check the host byte, to see if there is anything in there
466          * that would indicate what we need to do.
467          */
468         if (host_byte(scmd->result) == DID_RESET) {
469                 /*
470                  * rats.  we are already in the error handler, so we now
471                  * get to try and figure out what to do next.  if the sense
472                  * is valid, we have a pretty good idea of what to do.
473                  * if not, we mark it as FAILED.
474                  */
475                 return scsi_check_sense(scmd);
476         }
477         if (host_byte(scmd->result) != DID_OK)
478                 return FAILED;
479
480         /*
481          * next, check the message byte.
482          */
483         if (msg_byte(scmd->result) != COMMAND_COMPLETE)
484                 return FAILED;
485
486         /*
487          * now, check the status byte to see if this indicates
488          * anything special.
489          */
490         switch (status_byte(scmd->result)) {
491         case GOOD:
492                 scsi_handle_queue_ramp_up(scmd->device);
493         case COMMAND_TERMINATED:
494                 return SUCCESS;
495         case CHECK_CONDITION:
496                 return scsi_check_sense(scmd);
497         case CONDITION_GOOD:
498         case INTERMEDIATE_GOOD:
499         case INTERMEDIATE_C_GOOD:
500                 /*
501                  * who knows?  FIXME(eric)
502                  */
503                 return SUCCESS;
504         case RESERVATION_CONFLICT:
505                 if (scmd->cmnd[0] == TEST_UNIT_READY)
506                         /* it is a success, we probed the device and
507                          * found it */
508                         return SUCCESS;
509                 /* otherwise, we failed to send the command */
510                 return FAILED;
511         case QUEUE_FULL:
512                 scsi_handle_queue_full(scmd->device);
513                 /* fall through */
514         case BUSY:
515                 return NEEDS_RETRY;
516         default:
517                 return FAILED;
518         }
519         return FAILED;
520 }
521
522 /**
523  * scsi_eh_done - Completion function for error handling.
524  * @scmd:       Cmd that is done.
525  */
526 static void scsi_eh_done(struct scsi_cmnd *scmd)
527 {
528         struct completion *eh_action;
529
530         SCSI_LOG_ERROR_RECOVERY(3,
531                 printk("%s scmd: %p result: %x\n",
532                         __func__, scmd, scmd->result));
533
534         eh_action = scmd->device->host->eh_action;
535         if (eh_action)
536                 complete(eh_action);
537 }
538
539 /**
540  * scsi_try_host_reset - ask host adapter to reset itself
541  * @scmd:       SCSI cmd to send hsot reset.
542  */
543 static int scsi_try_host_reset(struct scsi_cmnd *scmd)
544 {
545         unsigned long flags;
546         int rtn;
547         struct Scsi_Host *host = scmd->device->host;
548         struct scsi_host_template *hostt = host->hostt;
549
550         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Snd Host RST\n",
551                                           __func__));
552
553         if (!hostt->eh_host_reset_handler)
554                 return FAILED;
555
556         rtn = hostt->eh_host_reset_handler(scmd);
557
558         if (rtn == SUCCESS) {
559                 if (!hostt->skip_settle_delay)
560                         ssleep(HOST_RESET_SETTLE_TIME);
561                 spin_lock_irqsave(host->host_lock, flags);
562                 scsi_report_bus_reset(host, scmd_channel(scmd));
563                 spin_unlock_irqrestore(host->host_lock, flags);
564         }
565
566         return rtn;
567 }
568
569 /**
570  * scsi_try_bus_reset - ask host to perform a bus reset
571  * @scmd:       SCSI cmd to send bus reset.
572  */
573 static int scsi_try_bus_reset(struct scsi_cmnd *scmd)
574 {
575         unsigned long flags;
576         int rtn;
577         struct Scsi_Host *host = scmd->device->host;
578         struct scsi_host_template *hostt = host->hostt;
579
580         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Snd Bus RST\n",
581                                           __func__));
582
583         if (!hostt->eh_bus_reset_handler)
584                 return FAILED;
585
586         rtn = hostt->eh_bus_reset_handler(scmd);
587
588         if (rtn == SUCCESS) {
589                 if (!hostt->skip_settle_delay)
590                         ssleep(BUS_RESET_SETTLE_TIME);
591                 spin_lock_irqsave(host->host_lock, flags);
592                 scsi_report_bus_reset(host, scmd_channel(scmd));
593                 spin_unlock_irqrestore(host->host_lock, flags);
594         }
595
596         return rtn;
597 }
598
599 static void __scsi_report_device_reset(struct scsi_device *sdev, void *data)
600 {
601         sdev->was_reset = 1;
602         sdev->expecting_cc_ua = 1;
603 }
604
605 /**
606  * scsi_try_target_reset - Ask host to perform a target reset
607  * @scmd:       SCSI cmd used to send a target reset
608  *
609  * Notes:
610  *    There is no timeout for this operation.  if this operation is
611  *    unreliable for a given host, then the host itself needs to put a
612  *    timer on it, and set the host back to a consistent state prior to
613  *    returning.
614  */
615 static int scsi_try_target_reset(struct scsi_cmnd *scmd)
616 {
617         unsigned long flags;
618         int rtn;
619         struct Scsi_Host *host = scmd->device->host;
620         struct scsi_host_template *hostt = host->hostt;
621
622         if (!hostt->eh_target_reset_handler)
623                 return FAILED;
624
625         rtn = hostt->eh_target_reset_handler(scmd);
626         if (rtn == SUCCESS) {
627                 spin_lock_irqsave(host->host_lock, flags);
628                 __starget_for_each_device(scsi_target(scmd->device), NULL,
629                                           __scsi_report_device_reset);
630                 spin_unlock_irqrestore(host->host_lock, flags);
631         }
632
633         return rtn;
634 }
635
636 /**
637  * scsi_try_bus_device_reset - Ask host to perform a BDR on a dev
638  * @scmd:       SCSI cmd used to send BDR
639  *
640  * Notes:
641  *    There is no timeout for this operation.  if this operation is
642  *    unreliable for a given host, then the host itself needs to put a
643  *    timer on it, and set the host back to a consistent state prior to
644  *    returning.
645  */
646 static int scsi_try_bus_device_reset(struct scsi_cmnd *scmd)
647 {
648         int rtn;
649         struct scsi_host_template *hostt = scmd->device->host->hostt;
650
651         if (!hostt->eh_device_reset_handler)
652                 return FAILED;
653
654         rtn = hostt->eh_device_reset_handler(scmd);
655         if (rtn == SUCCESS)
656                 __scsi_report_device_reset(scmd->device, NULL);
657         return rtn;
658 }
659
660 static int scsi_try_to_abort_cmd(struct scsi_host_template *hostt, struct scsi_cmnd *scmd)
661 {
662         if (!hostt->eh_abort_handler)
663                 return FAILED;
664
665         return hostt->eh_abort_handler(scmd);
666 }
667
668 static void scsi_abort_eh_cmnd(struct scsi_cmnd *scmd)
669 {
670         if (scsi_try_to_abort_cmd(scmd->device->host->hostt, scmd) != SUCCESS)
671                 if (scsi_try_bus_device_reset(scmd) != SUCCESS)
672                         if (scsi_try_target_reset(scmd) != SUCCESS)
673                                 if (scsi_try_bus_reset(scmd) != SUCCESS)
674                                         scsi_try_host_reset(scmd);
675 }
676
677 /**
678  * scsi_eh_prep_cmnd  - Save a scsi command info as part of error recovery
679  * @scmd:       SCSI command structure to hijack
680  * @ses:        structure to save restore information
681  * @cmnd:       CDB to send. Can be NULL if no new cmnd is needed
682  * @cmnd_size:  size in bytes of @cmnd (must be <= BLK_MAX_CDB)
683  * @sense_bytes: size of sense data to copy. or 0 (if != 0 @cmnd is ignored)
684  *
685  * This function is used to save a scsi command information before re-execution
686  * as part of the error recovery process.  If @sense_bytes is 0 the command
687  * sent must be one that does not transfer any data.  If @sense_bytes != 0
688  * @cmnd is ignored and this functions sets up a REQUEST_SENSE command
689  * and cmnd buffers to read @sense_bytes into @scmd->sense_buffer.
690  */
691 void scsi_eh_prep_cmnd(struct scsi_cmnd *scmd, struct scsi_eh_save *ses,
692                         unsigned char *cmnd, int cmnd_size, unsigned sense_bytes)
693 {
694         struct scsi_device *sdev = scmd->device;
695
696         /*
697          * We need saved copies of a number of fields - this is because
698          * error handling may need to overwrite these with different values
699          * to run different commands, and once error handling is complete,
700          * we will need to restore these values prior to running the actual
701          * command.
702          */
703         ses->cmd_len = scmd->cmd_len;
704         ses->cmnd = scmd->cmnd;
705         ses->data_direction = scmd->sc_data_direction;
706         ses->sdb = scmd->sdb;
707         ses->next_rq = scmd->request->next_rq;
708         ses->result = scmd->result;
709         ses->underflow = scmd->underflow;
710         ses->prot_op = scmd->prot_op;
711
712         scmd->prot_op = SCSI_PROT_NORMAL;
713         scmd->cmnd = ses->eh_cmnd;
714         memset(scmd->cmnd, 0, BLK_MAX_CDB);
715         memset(&scmd->sdb, 0, sizeof(scmd->sdb));
716         scmd->request->next_rq = NULL;
717
718         if (sense_bytes) {
719                 scmd->sdb.length = min_t(unsigned, SCSI_SENSE_BUFFERSIZE,
720                                          sense_bytes);
721                 sg_init_one(&ses->sense_sgl, scmd->sense_buffer,
722                             scmd->sdb.length);
723                 scmd->sdb.table.sgl = &ses->sense_sgl;
724                 scmd->sc_data_direction = DMA_FROM_DEVICE;
725                 scmd->sdb.table.nents = 1;
726                 scmd->cmnd[0] = REQUEST_SENSE;
727                 scmd->cmnd[4] = scmd->sdb.length;
728                 scmd->cmd_len = COMMAND_SIZE(scmd->cmnd[0]);
729         } else {
730                 scmd->sc_data_direction = DMA_NONE;
731                 if (cmnd) {
732                         BUG_ON(cmnd_size > BLK_MAX_CDB);
733                         memcpy(scmd->cmnd, cmnd, cmnd_size);
734                         scmd->cmd_len = COMMAND_SIZE(scmd->cmnd[0]);
735                 }
736         }
737
738         scmd->underflow = 0;
739
740         if (sdev->scsi_level <= SCSI_2 && sdev->scsi_level != SCSI_UNKNOWN)
741                 scmd->cmnd[1] = (scmd->cmnd[1] & 0x1f) |
742                         (sdev->lun << 5 & 0xe0);
743
744         /*
745          * Zero the sense buffer.  The scsi spec mandates that any
746          * untransferred sense data should be interpreted as being zero.
747          */
748         memset(scmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);
749 }
750 EXPORT_SYMBOL(scsi_eh_prep_cmnd);
751
752 /**
753  * scsi_eh_restore_cmnd  - Restore a scsi command info as part of error recovery
754  * @scmd:       SCSI command structure to restore
755  * @ses:        saved information from a coresponding call to scsi_eh_prep_cmnd
756  *
757  * Undo any damage done by above scsi_eh_prep_cmnd().
758  */
759 void scsi_eh_restore_cmnd(struct scsi_cmnd* scmd, struct scsi_eh_save *ses)
760 {
761         /*
762          * Restore original data
763          */
764         scmd->cmd_len = ses->cmd_len;
765         scmd->cmnd = ses->cmnd;
766         scmd->sc_data_direction = ses->data_direction;
767         scmd->sdb = ses->sdb;
768         scmd->request->next_rq = ses->next_rq;
769         scmd->result = ses->result;
770         scmd->underflow = ses->underflow;
771         scmd->prot_op = ses->prot_op;
772 }
773 EXPORT_SYMBOL(scsi_eh_restore_cmnd);
774
775 /**
776  * scsi_send_eh_cmnd  - submit a scsi command as part of error recovery
777  * @scmd:       SCSI command structure to hijack
778  * @cmnd:       CDB to send
779  * @cmnd_size:  size in bytes of @cmnd
780  * @timeout:    timeout for this request
781  * @sense_bytes: size of sense data to copy or 0
782  *
783  * This function is used to send a scsi command down to a target device
784  * as part of the error recovery process. See also scsi_eh_prep_cmnd() above.
785  *
786  * Return value:
787  *    SUCCESS or FAILED or NEEDS_RETRY
788  */
789 static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd,
790                              int cmnd_size, int timeout, unsigned sense_bytes)
791 {
792         struct scsi_device *sdev = scmd->device;
793         struct Scsi_Host *shost = sdev->host;
794         DECLARE_COMPLETION_ONSTACK(done);
795         unsigned long timeleft = timeout;
796         struct scsi_eh_save ses;
797         const unsigned long stall_for = msecs_to_jiffies(100);
798         int rtn;
799
800 retry:
801         scsi_eh_prep_cmnd(scmd, &ses, cmnd, cmnd_size, sense_bytes);
802         shost->eh_action = &done;
803
804         scsi_log_send(scmd);
805         scmd->scsi_done = scsi_eh_done;
806         rtn = shost->hostt->queuecommand(shost, scmd);
807         if (rtn) {
808                 if (timeleft > stall_for) {
809                         scsi_eh_restore_cmnd(scmd, &ses);
810                         timeleft -= stall_for;
811                         msleep(jiffies_to_msecs(stall_for));
812                         goto retry;
813                 }
814                 /* signal not to enter either branch of the if () below */
815                 timeleft = 0;
816                 rtn = NEEDS_RETRY;
817         } else {
818                 timeleft = wait_for_completion_timeout(&done, timeout);
819         }
820
821         shost->eh_action = NULL;
822
823         scsi_log_completion(scmd, rtn);
824
825         SCSI_LOG_ERROR_RECOVERY(3,
826                 printk("%s: scmd: %p, timeleft: %ld\n",
827                         __func__, scmd, timeleft));
828
829         /*
830          * If there is time left scsi_eh_done got called, and we will examine
831          * the actual status codes to see whether the command actually did
832          * complete normally, else if we have a zero return and no time left,
833          * the command must still be pending, so abort it and return FAILED.
834          * If we never actually managed to issue the command, because
835          * ->queuecommand() kept returning non zero, use the rtn = FAILED
836          * value above (so don't execute either branch of the if)
837          */
838         if (timeleft) {
839                 rtn = scsi_eh_completed_normally(scmd);
840                 SCSI_LOG_ERROR_RECOVERY(3,
841                         printk("%s: scsi_eh_completed_normally %x\n",
842                                __func__, rtn));
843
844                 switch (rtn) {
845                 case SUCCESS:
846                 case NEEDS_RETRY:
847                 case FAILED:
848                 case TARGET_ERROR:
849                         break;
850                 case ADD_TO_MLQUEUE:
851                         rtn = NEEDS_RETRY;
852                         break;
853                 default:
854                         rtn = FAILED;
855                         break;
856                 }
857         } else if (!rtn) {
858                 scsi_abort_eh_cmnd(scmd);
859                 rtn = FAILED;
860         }
861
862         scsi_eh_restore_cmnd(scmd, &ses);
863
864         if (scmd->request->cmd_type != REQ_TYPE_BLOCK_PC) {
865                 struct scsi_driver *sdrv = scsi_cmd_to_driver(scmd);
866                 if (sdrv->eh_action)
867                         rtn = sdrv->eh_action(scmd, cmnd, cmnd_size, rtn);
868         }
869
870         return rtn;
871 }
872
873 /**
874  * scsi_request_sense - Request sense data from a particular target.
875  * @scmd:       SCSI cmd for request sense.
876  *
877  * Notes:
878  *    Some hosts automatically obtain this information, others require
879  *    that we obtain it on our own. This function will *not* return until
880  *    the command either times out, or it completes.
881  */
882 static int scsi_request_sense(struct scsi_cmnd *scmd)
883 {
884         return scsi_send_eh_cmnd(scmd, NULL, 0, SENSE_TIMEOUT, ~0);
885 }
886
887 /**
888  * scsi_eh_finish_cmd - Handle a cmd that eh is finished with.
889  * @scmd:       Original SCSI cmd that eh has finished.
890  * @done_q:     Queue for processed commands.
891  *
892  * Notes:
893  *    We don't want to use the normal command completion while we are are
894  *    still handling errors - it may cause other commands to be queued,
895  *    and that would disturb what we are doing.  Thus we really want to
896  *    keep a list of pending commands for final completion, and once we
897  *    are ready to leave error handling we handle completion for real.
898  */
899 void scsi_eh_finish_cmd(struct scsi_cmnd *scmd, struct list_head *done_q)
900 {
901         scmd->device->host->host_failed--;
902         scmd->eh_eflags = 0;
903         list_move_tail(&scmd->eh_entry, done_q);
904 }
905 EXPORT_SYMBOL(scsi_eh_finish_cmd);
906
907 /**
908  * scsi_eh_get_sense - Get device sense data.
909  * @work_q:     Queue of commands to process.
910  * @done_q:     Queue of processed commands.
911  *
912  * Description:
913  *    See if we need to request sense information.  if so, then get it
914  *    now, so we have a better idea of what to do.
915  *
916  * Notes:
917  *    This has the unfortunate side effect that if a shost adapter does
918  *    not automatically request sense information, we end up shutting
919  *    it down before we request it.
920  *
921  *    All drivers should request sense information internally these days,
922  *    so for now all I have to say is tough noogies if you end up in here.
923  *
924  *    XXX: Long term this code should go away, but that needs an audit of
925  *         all LLDDs first.
926  */
927 int scsi_eh_get_sense(struct list_head *work_q,
928                       struct list_head *done_q)
929 {
930         struct scsi_cmnd *scmd, *next;
931         int rtn;
932
933         list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
934                 if ((scmd->eh_eflags & SCSI_EH_CANCEL_CMD) ||
935                     SCSI_SENSE_VALID(scmd))
936                         continue;
937
938                 SCSI_LOG_ERROR_RECOVERY(2, scmd_printk(KERN_INFO, scmd,
939                                                   "%s: requesting sense\n",
940                                                   current->comm));
941                 rtn = scsi_request_sense(scmd);
942                 if (rtn != SUCCESS)
943                         continue;
944
945                 SCSI_LOG_ERROR_RECOVERY(3, printk("sense requested for %p"
946                                                   " result %x\n", scmd,
947                                                   scmd->result));
948                 SCSI_LOG_ERROR_RECOVERY(3, scsi_print_sense("bh", scmd));
949
950                 rtn = scsi_decide_disposition(scmd);
951
952                 /*
953                  * if the result was normal, then just pass it along to the
954                  * upper level.
955                  */
956                 if (rtn == SUCCESS)
957                         /* we don't want this command reissued, just
958                          * finished with the sense data, so set
959                          * retries to the max allowed to ensure it
960                          * won't get reissued */
961                         scmd->retries = scmd->allowed;
962                 else if (rtn != NEEDS_RETRY)
963                         continue;
964
965                 scsi_eh_finish_cmd(scmd, done_q);
966         }
967
968         return list_empty(work_q);
969 }
970 EXPORT_SYMBOL_GPL(scsi_eh_get_sense);
971
972 /**
973  * scsi_eh_tur - Send TUR to device.
974  * @scmd:       &scsi_cmnd to send TUR
975  *
976  * Return value:
977  *    0 - Device is ready. 1 - Device NOT ready.
978  */
979 static int scsi_eh_tur(struct scsi_cmnd *scmd)
980 {
981         static unsigned char tur_command[6] = {TEST_UNIT_READY, 0, 0, 0, 0, 0};
982         int retry_cnt = 1, rtn;
983
984 retry_tur:
985         rtn = scsi_send_eh_cmnd(scmd, tur_command, 6, SENSE_TIMEOUT, 0);
986
987         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: scmd %p rtn %x\n",
988                 __func__, scmd, rtn));
989
990         switch (rtn) {
991         case NEEDS_RETRY:
992                 if (retry_cnt--)
993                         goto retry_tur;
994                 /*FALLTHRU*/
995         case SUCCESS:
996                 return 0;
997         default:
998                 return 1;
999         }
1000 }
1001
1002 /**
1003  * scsi_eh_test_devices - check if devices are responding from error recovery.
1004  * @cmd_list:   scsi commands in error recovery.
1005  * @work_q:     queue for commands which still need more error recovery
1006  * @done_q:     queue for commands which are finished
1007  * @try_stu:    boolean on if a STU command should be tried in addition to TUR.
1008  *
1009  * Decription:
1010  *    Tests if devices are in a working state.  Commands to devices now in
1011  *    a working state are sent to the done_q while commands to devices which
1012  *    are still failing to respond are returned to the work_q for more
1013  *    processing.
1014  **/
1015 static int scsi_eh_test_devices(struct list_head *cmd_list,
1016                                 struct list_head *work_q,
1017                                 struct list_head *done_q, int try_stu)
1018 {
1019         struct scsi_cmnd *scmd, *next;
1020         struct scsi_device *sdev;
1021         int finish_cmds;
1022
1023         while (!list_empty(cmd_list)) {
1024                 scmd = list_entry(cmd_list->next, struct scsi_cmnd, eh_entry);
1025                 sdev = scmd->device;
1026
1027                 finish_cmds = !scsi_device_online(scmd->device) ||
1028                         (try_stu && !scsi_eh_try_stu(scmd) &&
1029                          !scsi_eh_tur(scmd)) ||
1030                         !scsi_eh_tur(scmd);
1031
1032                 list_for_each_entry_safe(scmd, next, cmd_list, eh_entry)
1033                         if (scmd->device == sdev) {
1034                                 if (finish_cmds)
1035                                         scsi_eh_finish_cmd(scmd, done_q);
1036                                 else
1037                                         list_move_tail(&scmd->eh_entry, work_q);
1038                         }
1039         }
1040         return list_empty(work_q);
1041 }
1042
1043
1044 /**
1045  * scsi_eh_abort_cmds - abort pending commands.
1046  * @work_q:     &list_head for pending commands.
1047  * @done_q:     &list_head for processed commands.
1048  *
1049  * Decription:
1050  *    Try and see whether or not it makes sense to try and abort the
1051  *    running command.  This only works out to be the case if we have one
1052  *    command that has timed out.  If the command simply failed, it makes
1053  *    no sense to try and abort the command, since as far as the shost
1054  *    adapter is concerned, it isn't running.
1055  */
1056 static int scsi_eh_abort_cmds(struct list_head *work_q,
1057                               struct list_head *done_q)
1058 {
1059         struct scsi_cmnd *scmd, *next;
1060         LIST_HEAD(check_list);
1061         int rtn;
1062
1063         list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
1064                 if (!(scmd->eh_eflags & SCSI_EH_CANCEL_CMD))
1065                         continue;
1066                 SCSI_LOG_ERROR_RECOVERY(3, printk("%s: aborting cmd:"
1067                                                   "0x%p\n", current->comm,
1068                                                   scmd));
1069                 rtn = scsi_try_to_abort_cmd(scmd->device->host->hostt, scmd);
1070                 if (rtn == SUCCESS || rtn == FAST_IO_FAIL) {
1071                         scmd->eh_eflags &= ~SCSI_EH_CANCEL_CMD;
1072                         if (rtn == FAST_IO_FAIL)
1073                                 scsi_eh_finish_cmd(scmd, done_q);
1074                         else
1075                                 list_move_tail(&scmd->eh_entry, &check_list);
1076                 } else
1077                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: aborting"
1078                                                           " cmd failed:"
1079                                                           "0x%p\n",
1080                                                           current->comm,
1081                                                           scmd));
1082         }
1083
1084         return scsi_eh_test_devices(&check_list, work_q, done_q, 0);
1085 }
1086
1087 /**
1088  * scsi_eh_try_stu - Send START_UNIT to device.
1089  * @scmd:       &scsi_cmnd to send START_UNIT
1090  *
1091  * Return value:
1092  *    0 - Device is ready. 1 - Device NOT ready.
1093  */
1094 static int scsi_eh_try_stu(struct scsi_cmnd *scmd)
1095 {
1096         static unsigned char stu_command[6] = {START_STOP, 0, 0, 0, 1, 0};
1097
1098         if (scmd->device->allow_restart) {
1099                 int i, rtn = NEEDS_RETRY;
1100
1101                 for (i = 0; rtn == NEEDS_RETRY && i < 2; i++)
1102                         rtn = scsi_send_eh_cmnd(scmd, stu_command, 6, scmd->device->request_queue->rq_timeout, 0);
1103
1104                 if (rtn == SUCCESS)
1105                         return 0;
1106         }
1107
1108         return 1;
1109 }
1110
1111  /**
1112  * scsi_eh_stu - send START_UNIT if needed
1113  * @shost:      &scsi host being recovered.
1114  * @work_q:     &list_head for pending commands.
1115  * @done_q:     &list_head for processed commands.
1116  *
1117  * Notes:
1118  *    If commands are failing due to not ready, initializing command required,
1119  *      try revalidating the device, which will end up sending a start unit.
1120  */
1121 static int scsi_eh_stu(struct Scsi_Host *shost,
1122                               struct list_head *work_q,
1123                               struct list_head *done_q)
1124 {
1125         struct scsi_cmnd *scmd, *stu_scmd, *next;
1126         struct scsi_device *sdev;
1127
1128         shost_for_each_device(sdev, shost) {
1129                 stu_scmd = NULL;
1130                 list_for_each_entry(scmd, work_q, eh_entry)
1131                         if (scmd->device == sdev && SCSI_SENSE_VALID(scmd) &&
1132                             scsi_check_sense(scmd) == FAILED ) {
1133                                 stu_scmd = scmd;
1134                                 break;
1135                         }
1136
1137                 if (!stu_scmd)
1138                         continue;
1139
1140                 SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending START_UNIT to sdev:"
1141                                                   " 0x%p\n", current->comm, sdev));
1142
1143                 if (!scsi_eh_try_stu(stu_scmd)) {
1144                         if (!scsi_device_online(sdev) ||
1145                             !scsi_eh_tur(stu_scmd)) {
1146                                 list_for_each_entry_safe(scmd, next,
1147                                                           work_q, eh_entry) {
1148                                         if (scmd->device == sdev)
1149                                                 scsi_eh_finish_cmd(scmd, done_q);
1150                                 }
1151                         }
1152                 } else {
1153                         SCSI_LOG_ERROR_RECOVERY(3,
1154                                                 printk("%s: START_UNIT failed to sdev:"
1155                                                        " 0x%p\n", current->comm, sdev));
1156                 }
1157         }
1158
1159         return list_empty(work_q);
1160 }
1161
1162
1163 /**
1164  * scsi_eh_bus_device_reset - send bdr if needed
1165  * @shost:      scsi host being recovered.
1166  * @work_q:     &list_head for pending commands.
1167  * @done_q:     &list_head for processed commands.
1168  *
1169  * Notes:
1170  *    Try a bus device reset.  Still, look to see whether we have multiple
1171  *    devices that are jammed or not - if we have multiple devices, it
1172  *    makes no sense to try bus_device_reset - we really would need to try
1173  *    a bus_reset instead.
1174  */
1175 static int scsi_eh_bus_device_reset(struct Scsi_Host *shost,
1176                                     struct list_head *work_q,
1177                                     struct list_head *done_q)
1178 {
1179         struct scsi_cmnd *scmd, *bdr_scmd, *next;
1180         struct scsi_device *sdev;
1181         int rtn;
1182
1183         shost_for_each_device(sdev, shost) {
1184                 bdr_scmd = NULL;
1185                 list_for_each_entry(scmd, work_q, eh_entry)
1186                         if (scmd->device == sdev) {
1187                                 bdr_scmd = scmd;
1188                                 break;
1189                         }
1190
1191                 if (!bdr_scmd)
1192                         continue;
1193
1194                 SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending BDR sdev:"
1195                                                   " 0x%p\n", current->comm,
1196                                                   sdev));
1197                 rtn = scsi_try_bus_device_reset(bdr_scmd);
1198                 if (rtn == SUCCESS || rtn == FAST_IO_FAIL) {
1199                         if (!scsi_device_online(sdev) ||
1200                             rtn == FAST_IO_FAIL ||
1201                             !scsi_eh_tur(bdr_scmd)) {
1202                                 list_for_each_entry_safe(scmd, next,
1203                                                          work_q, eh_entry) {
1204                                         if (scmd->device == sdev)
1205                                                 scsi_eh_finish_cmd(scmd,
1206                                                                    done_q);
1207                                 }
1208                         }
1209                 } else {
1210                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: BDR"
1211                                                           " failed sdev:"
1212                                                           "0x%p\n",
1213                                                           current->comm,
1214                                                            sdev));
1215                 }
1216         }
1217
1218         return list_empty(work_q);
1219 }
1220
1221 /**
1222  * scsi_eh_target_reset - send target reset if needed
1223  * @shost:      scsi host being recovered.
1224  * @work_q:     &list_head for pending commands.
1225  * @done_q:     &list_head for processed commands.
1226  *
1227  * Notes:
1228  *    Try a target reset.
1229  */
1230 static int scsi_eh_target_reset(struct Scsi_Host *shost,
1231                                 struct list_head *work_q,
1232                                 struct list_head *done_q)
1233 {
1234         LIST_HEAD(tmp_list);
1235         LIST_HEAD(check_list);
1236
1237         list_splice_init(work_q, &tmp_list);
1238
1239         while (!list_empty(&tmp_list)) {
1240                 struct scsi_cmnd *next, *scmd;
1241                 int rtn;
1242                 unsigned int id;
1243
1244                 scmd = list_entry(tmp_list.next, struct scsi_cmnd, eh_entry);
1245                 id = scmd_id(scmd);
1246
1247                 SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending target reset "
1248                                                   "to target %d\n",
1249                                                   current->comm, id));
1250                 rtn = scsi_try_target_reset(scmd);
1251                 if (rtn != SUCCESS && rtn != FAST_IO_FAIL)
1252                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Target reset"
1253                                                           " failed target: "
1254                                                           "%d\n",
1255                                                           current->comm, id));
1256                 list_for_each_entry_safe(scmd, next, &tmp_list, eh_entry) {
1257                         if (scmd_id(scmd) != id)
1258                                 continue;
1259
1260                         if (rtn == SUCCESS)
1261                                 list_move_tail(&scmd->eh_entry, &check_list);
1262                         else if (rtn == FAST_IO_FAIL)
1263                                 scsi_eh_finish_cmd(scmd, done_q);
1264                         else
1265                                 /* push back on work queue for further processing */
1266                                 list_move(&scmd->eh_entry, work_q);
1267                 }
1268         }
1269
1270         return scsi_eh_test_devices(&check_list, work_q, done_q, 0);
1271 }
1272
1273 /**
1274  * scsi_eh_bus_reset - send a bus reset
1275  * @shost:      &scsi host being recovered.
1276  * @work_q:     &list_head for pending commands.
1277  * @done_q:     &list_head for processed commands.
1278  */
1279 static int scsi_eh_bus_reset(struct Scsi_Host *shost,
1280                              struct list_head *work_q,
1281                              struct list_head *done_q)
1282 {
1283         struct scsi_cmnd *scmd, *chan_scmd, *next;
1284         LIST_HEAD(check_list);
1285         unsigned int channel;
1286         int rtn;
1287
1288         /*
1289          * we really want to loop over the various channels, and do this on
1290          * a channel by channel basis.  we should also check to see if any
1291          * of the failed commands are on soft_reset devices, and if so, skip
1292          * the reset.
1293          */
1294
1295         for (channel = 0; channel <= shost->max_channel; channel++) {
1296                 chan_scmd = NULL;
1297                 list_for_each_entry(scmd, work_q, eh_entry) {
1298                         if (channel == scmd_channel(scmd)) {
1299                                 chan_scmd = scmd;
1300                                 break;
1301                                 /*
1302                                  * FIXME add back in some support for
1303                                  * soft_reset devices.
1304                                  */
1305                         }
1306                 }
1307
1308                 if (!chan_scmd)
1309                         continue;
1310                 SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending BRST chan:"
1311                                                   " %d\n", current->comm,
1312                                                   channel));
1313                 rtn = scsi_try_bus_reset(chan_scmd);
1314                 if (rtn == SUCCESS || rtn == FAST_IO_FAIL) {
1315                         list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
1316                                 if (channel == scmd_channel(scmd)) {
1317                                         if (rtn == FAST_IO_FAIL)
1318                                                 scsi_eh_finish_cmd(scmd,
1319                                                                    done_q);
1320                                         else
1321                                                 list_move_tail(&scmd->eh_entry,
1322                                                                &check_list);
1323                                 }
1324                         }
1325                 } else {
1326                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: BRST"
1327                                                           " failed chan: %d\n",
1328                                                           current->comm,
1329                                                           channel));
1330                 }
1331         }
1332         return scsi_eh_test_devices(&check_list, work_q, done_q, 0);
1333 }
1334
1335 /**
1336  * scsi_eh_host_reset - send a host reset
1337  * @work_q:     list_head for processed commands.
1338  * @done_q:     list_head for processed commands.
1339  */
1340 static int scsi_eh_host_reset(struct list_head *work_q,
1341                               struct list_head *done_q)
1342 {
1343         struct scsi_cmnd *scmd, *next;
1344         LIST_HEAD(check_list);
1345         int rtn;
1346
1347         if (!list_empty(work_q)) {
1348                 scmd = list_entry(work_q->next,
1349                                   struct scsi_cmnd, eh_entry);
1350
1351                 SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending HRST\n"
1352                                                   , current->comm));
1353
1354                 rtn = scsi_try_host_reset(scmd);
1355                 if (rtn == SUCCESS) {
1356                         list_splice_init(work_q, &check_list);
1357                 } else if (rtn == FAST_IO_FAIL) {
1358                         list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
1359                                         scsi_eh_finish_cmd(scmd, done_q);
1360                         }
1361                 } else {
1362                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: HRST"
1363                                                           " failed\n",
1364                                                           current->comm));
1365                 }
1366         }
1367         return scsi_eh_test_devices(&check_list, work_q, done_q, 1);
1368 }
1369
1370 /**
1371  * scsi_eh_offline_sdevs - offline scsi devices that fail to recover
1372  * @work_q:     list_head for processed commands.
1373  * @done_q:     list_head for processed commands.
1374  */
1375 static void scsi_eh_offline_sdevs(struct list_head *work_q,
1376                                   struct list_head *done_q)
1377 {
1378         struct scsi_cmnd *scmd, *next;
1379
1380         list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
1381                 sdev_printk(KERN_INFO, scmd->device, "Device offlined - "
1382                             "not ready after error recovery\n");
1383                 scsi_device_set_state(scmd->device, SDEV_OFFLINE);
1384                 if (scmd->eh_eflags & SCSI_EH_CANCEL_CMD) {
1385                         /*
1386                          * FIXME: Handle lost cmds.
1387                          */
1388                 }
1389                 scsi_eh_finish_cmd(scmd, done_q);
1390         }
1391         return;
1392 }
1393
1394 /**
1395  * scsi_noretry_cmd - determinte if command should be failed fast
1396  * @scmd:       SCSI cmd to examine.
1397  */
1398 int scsi_noretry_cmd(struct scsi_cmnd *scmd)
1399 {
1400         switch (host_byte(scmd->result)) {
1401         case DID_OK:
1402                 break;
1403         case DID_BUS_BUSY:
1404                 return (scmd->request->cmd_flags & REQ_FAILFAST_TRANSPORT);
1405         case DID_PARITY:
1406                 return (scmd->request->cmd_flags & REQ_FAILFAST_DEV);
1407         case DID_ERROR:
1408                 if (msg_byte(scmd->result) == COMMAND_COMPLETE &&
1409                     status_byte(scmd->result) == RESERVATION_CONFLICT)
1410                         return 0;
1411                 /* fall through */
1412         case DID_SOFT_ERROR:
1413                 return (scmd->request->cmd_flags & REQ_FAILFAST_DRIVER);
1414         }
1415
1416         switch (status_byte(scmd->result)) {
1417         case CHECK_CONDITION:
1418                 /*
1419                  * assume caller has checked sense and determinted
1420                  * the check condition was retryable.
1421                  */
1422                 if (scmd->request->cmd_flags & REQ_FAILFAST_DEV ||
1423                     scmd->request->cmd_type == REQ_TYPE_BLOCK_PC)
1424                         return 1;
1425         }
1426
1427         return 0;
1428 }
1429
1430 /**
1431  * scsi_decide_disposition - Disposition a cmd on return from LLD.
1432  * @scmd:       SCSI cmd to examine.
1433  *
1434  * Notes:
1435  *    This is *only* called when we are examining the status after sending
1436  *    out the actual data command.  any commands that are queued for error
1437  *    recovery (e.g. test_unit_ready) do *not* come through here.
1438  *
1439  *    When this routine returns failed, it means the error handler thread
1440  *    is woken.  In cases where the error code indicates an error that
1441  *    doesn't require the error handler read (i.e. we don't need to
1442  *    abort/reset), this function should return SUCCESS.
1443  */
1444 int scsi_decide_disposition(struct scsi_cmnd *scmd)
1445 {
1446         int rtn;
1447
1448         /*
1449          * if the device is offline, then we clearly just pass the result back
1450          * up to the top level.
1451          */
1452         if (!scsi_device_online(scmd->device)) {
1453                 SCSI_LOG_ERROR_RECOVERY(5, printk("%s: device offline - report"
1454                                                   " as SUCCESS\n",
1455                                                   __func__));
1456                 return SUCCESS;
1457         }
1458
1459         /*
1460          * first check the host byte, to see if there is anything in there
1461          * that would indicate what we need to do.
1462          */
1463         switch (host_byte(scmd->result)) {
1464         case DID_PASSTHROUGH:
1465                 /*
1466                  * no matter what, pass this through to the upper layer.
1467                  * nuke this special code so that it looks like we are saying
1468                  * did_ok.
1469                  */
1470                 scmd->result &= 0xff00ffff;
1471                 return SUCCESS;
1472         case DID_OK:
1473                 /*
1474                  * looks good.  drop through, and check the next byte.
1475                  */
1476                 break;
1477         case DID_NO_CONNECT:
1478         case DID_BAD_TARGET:
1479         case DID_ABORT:
1480                 /*
1481                  * note - this means that we just report the status back
1482                  * to the top level driver, not that we actually think
1483                  * that it indicates SUCCESS.
1484                  */
1485                 return SUCCESS;
1486                 /*
1487                  * when the low level driver returns did_soft_error,
1488                  * it is responsible for keeping an internal retry counter
1489                  * in order to avoid endless loops (db)
1490                  *
1491                  * actually this is a bug in this function here.  we should
1492                  * be mindful of the maximum number of retries specified
1493                  * and not get stuck in a loop.
1494                  */
1495         case DID_SOFT_ERROR:
1496                 goto maybe_retry;
1497         case DID_IMM_RETRY:
1498                 return NEEDS_RETRY;
1499
1500         case DID_REQUEUE:
1501                 return ADD_TO_MLQUEUE;
1502         case DID_TRANSPORT_DISRUPTED:
1503                 /*
1504                  * LLD/transport was disrupted during processing of the IO.
1505                  * The transport class is now blocked/blocking,
1506                  * and the transport will decide what to do with the IO
1507                  * based on its timers and recovery capablilities if
1508                  * there are enough retries.
1509                  */
1510                 goto maybe_retry;
1511         case DID_TRANSPORT_FAILFAST:
1512                 /*
1513                  * The transport decided to failfast the IO (most likely
1514                  * the fast io fail tmo fired), so send IO directly upwards.
1515                  */
1516                 return SUCCESS;
1517         case DID_ERROR:
1518                 if (msg_byte(scmd->result) == COMMAND_COMPLETE &&
1519                     status_byte(scmd->result) == RESERVATION_CONFLICT)
1520                         /*
1521                          * execute reservation conflict processing code
1522                          * lower down
1523                          */
1524                         break;
1525                 /* fallthrough */
1526         case DID_BUS_BUSY:
1527         case DID_PARITY:
1528                 goto maybe_retry;
1529         case DID_TIME_OUT:
1530                 /*
1531                  * when we scan the bus, we get timeout messages for
1532                  * these commands if there is no device available.
1533                  * other hosts report did_no_connect for the same thing.
1534                  */
1535                 if ((scmd->cmnd[0] == TEST_UNIT_READY ||
1536                      scmd->cmnd[0] == INQUIRY)) {
1537                         return SUCCESS;
1538                 } else {
1539                         return FAILED;
1540                 }
1541         case DID_RESET:
1542                 return SUCCESS;
1543         default:
1544                 return FAILED;
1545         }
1546
1547         /*
1548          * next, check the message byte.
1549          */
1550         if (msg_byte(scmd->result) != COMMAND_COMPLETE)
1551                 return FAILED;
1552
1553         /*
1554          * check the status byte to see if this indicates anything special.
1555          */
1556         switch (status_byte(scmd->result)) {
1557         case QUEUE_FULL:
1558                 scsi_handle_queue_full(scmd->device);
1559                 /*
1560                  * the case of trying to send too many commands to a
1561                  * tagged queueing device.
1562                  */
1563         case BUSY:
1564                 /*
1565                  * device can't talk to us at the moment.  Should only
1566                  * occur (SAM-3) when the task queue is empty, so will cause
1567                  * the empty queue handling to trigger a stall in the
1568                  * device.
1569                  */
1570                 return ADD_TO_MLQUEUE;
1571         case GOOD:
1572                 scsi_handle_queue_ramp_up(scmd->device);
1573         case COMMAND_TERMINATED:
1574                 return SUCCESS;
1575         case TASK_ABORTED:
1576                 goto maybe_retry;
1577         case CHECK_CONDITION:
1578                 rtn = scsi_check_sense(scmd);
1579                 if (rtn == NEEDS_RETRY)
1580                         goto maybe_retry;
1581                 else if (rtn == TARGET_ERROR) {
1582                         /*
1583                          * Need to modify host byte to signal a
1584                          * permanent target failure
1585                          */
1586                         set_host_byte(scmd, DID_TARGET_FAILURE);
1587                         rtn = SUCCESS;
1588                 }
1589                 /* if rtn == FAILED, we have no sense information;
1590                  * returning FAILED will wake the error handler thread
1591                  * to collect the sense and redo the decide
1592                  * disposition */
1593                 return rtn;
1594         case CONDITION_GOOD:
1595         case INTERMEDIATE_GOOD:
1596         case INTERMEDIATE_C_GOOD:
1597         case ACA_ACTIVE:
1598                 /*
1599                  * who knows?  FIXME(eric)
1600                  */
1601                 return SUCCESS;
1602
1603         case RESERVATION_CONFLICT:
1604                 sdev_printk(KERN_INFO, scmd->device,
1605                             "reservation conflict\n");
1606                 set_host_byte(scmd, DID_NEXUS_FAILURE);
1607                 return SUCCESS; /* causes immediate i/o error */
1608         default:
1609                 return FAILED;
1610         }
1611         return FAILED;
1612
1613       maybe_retry:
1614
1615         /* we requeue for retry because the error was retryable, and
1616          * the request was not marked fast fail.  Note that above,
1617          * even if the request is marked fast fail, we still requeue
1618          * for queue congestion conditions (QUEUE_FULL or BUSY) */
1619         if ((++scmd->retries) <= scmd->allowed
1620             && !scsi_noretry_cmd(scmd)) {
1621                 return NEEDS_RETRY;
1622         } else {
1623                 /*
1624                  * no more retries - report this one back to upper level.
1625                  */
1626                 return SUCCESS;
1627         }
1628 }
1629
1630 static void eh_lock_door_done(struct request *req, int uptodate)
1631 {
1632         __blk_put_request(req->q, req);
1633 }
1634
1635 /**
1636  * scsi_eh_lock_door - Prevent medium removal for the specified device
1637  * @sdev:       SCSI device to prevent medium removal
1638  *
1639  * Locking:
1640  *      We must be called from process context.
1641  *
1642  * Notes:
1643  *      We queue up an asynchronous "ALLOW MEDIUM REMOVAL" request on the
1644  *      head of the devices request queue, and continue.
1645  */
1646 static void scsi_eh_lock_door(struct scsi_device *sdev)
1647 {
1648         struct request *req;
1649
1650         /*
1651          * blk_get_request with GFP_KERNEL (__GFP_WAIT) sleeps until a
1652          * request becomes available
1653          */
1654         req = blk_get_request(sdev->request_queue, READ, GFP_KERNEL);
1655         if (!req)
1656                 return;
1657
1658         req->cmd[0] = ALLOW_MEDIUM_REMOVAL;
1659         req->cmd[1] = 0;
1660         req->cmd[2] = 0;
1661         req->cmd[3] = 0;
1662         req->cmd[4] = SCSI_REMOVAL_PREVENT;
1663         req->cmd[5] = 0;
1664
1665         req->cmd_len = COMMAND_SIZE(req->cmd[0]);
1666
1667         req->cmd_type = REQ_TYPE_BLOCK_PC;
1668         req->cmd_flags |= REQ_QUIET;
1669         req->timeout = 10 * HZ;
1670         req->retries = 5;
1671
1672         blk_execute_rq_nowait(req->q, NULL, req, 1, eh_lock_door_done);
1673 }
1674
1675 /**
1676  * scsi_restart_operations - restart io operations to the specified host.
1677  * @shost:      Host we are restarting.
1678  *
1679  * Notes:
1680  *    When we entered the error handler, we blocked all further i/o to
1681  *    this device.  we need to 'reverse' this process.
1682  */
1683 static void scsi_restart_operations(struct Scsi_Host *shost)
1684 {
1685         struct scsi_device *sdev;
1686         unsigned long flags;
1687
1688         /*
1689          * If the door was locked, we need to insert a door lock request
1690          * onto the head of the SCSI request queue for the device.  There
1691          * is no point trying to lock the door of an off-line device.
1692          */
1693         shost_for_each_device(sdev, shost) {
1694                 if (scsi_device_online(sdev) && sdev->was_reset && sdev->locked) {
1695                         scsi_eh_lock_door(sdev);
1696                         sdev->was_reset = 0;
1697                 }
1698         }
1699
1700         /*
1701          * next free up anything directly waiting upon the host.  this
1702          * will be requests for character device operations, and also for
1703          * ioctls to queued block devices.
1704          */
1705         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: waking up host to restart\n",
1706                                           __func__));
1707
1708         spin_lock_irqsave(shost->host_lock, flags);
1709         if (scsi_host_set_state(shost, SHOST_RUNNING))
1710                 if (scsi_host_set_state(shost, SHOST_CANCEL))
1711                         BUG_ON(scsi_host_set_state(shost, SHOST_DEL));
1712         spin_unlock_irqrestore(shost->host_lock, flags);
1713
1714         wake_up(&shost->host_wait);
1715
1716         /*
1717          * finally we need to re-initiate requests that may be pending.  we will
1718          * have had everything blocked while error handling is taking place, and
1719          * now that error recovery is done, we will need to ensure that these
1720          * requests are started.
1721          */
1722         scsi_run_host_queues(shost);
1723
1724         /*
1725          * if eh is active and host_eh_scheduled is pending we need to re-run
1726          * recovery.  we do this check after scsi_run_host_queues() to allow
1727          * everything pent up since the last eh run a chance to make forward
1728          * progress before we sync again.  Either we'll immediately re-run
1729          * recovery or scsi_device_unbusy() will wake us again when these
1730          * pending commands complete.
1731          */
1732         spin_lock_irqsave(shost->host_lock, flags);
1733         if (shost->host_eh_scheduled)
1734                 if (scsi_host_set_state(shost, SHOST_RECOVERY))
1735                         WARN_ON(scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY));
1736         spin_unlock_irqrestore(shost->host_lock, flags);
1737 }
1738
1739 /**
1740  * scsi_eh_ready_devs - check device ready state and recover if not.
1741  * @shost:      host to be recovered.
1742  * @work_q:     &list_head for pending commands.
1743  * @done_q:     &list_head for processed commands.
1744  */
1745 void scsi_eh_ready_devs(struct Scsi_Host *shost,
1746                         struct list_head *work_q,
1747                         struct list_head *done_q)
1748 {
1749         if (!scsi_eh_stu(shost, work_q, done_q))
1750                 if (!scsi_eh_bus_device_reset(shost, work_q, done_q))
1751                         if (!scsi_eh_target_reset(shost, work_q, done_q))
1752                                 if (!scsi_eh_bus_reset(shost, work_q, done_q))
1753                                         if (!scsi_eh_host_reset(work_q, done_q))
1754                                                 scsi_eh_offline_sdevs(work_q,
1755                                                                       done_q);
1756 }
1757 EXPORT_SYMBOL_GPL(scsi_eh_ready_devs);
1758
1759 /**
1760  * scsi_eh_flush_done_q - finish processed commands or retry them.
1761  * @done_q:     list_head of processed commands.
1762  */
1763 void scsi_eh_flush_done_q(struct list_head *done_q)
1764 {
1765         struct scsi_cmnd *scmd, *next;
1766
1767         list_for_each_entry_safe(scmd, next, done_q, eh_entry) {
1768                 list_del_init(&scmd->eh_entry);
1769                 if (scsi_device_online(scmd->device) &&
1770                     !scsi_noretry_cmd(scmd) &&
1771                     (++scmd->retries <= scmd->allowed)) {
1772                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: flush"
1773                                                           " retry cmd: %p\n",
1774                                                           current->comm,
1775                                                           scmd));
1776                                 scsi_queue_insert(scmd, SCSI_MLQUEUE_EH_RETRY);
1777                 } else {
1778                         /*
1779                          * If just we got sense for the device (called
1780                          * scsi_eh_get_sense), scmd->result is already
1781                          * set, do not set DRIVER_TIMEOUT.
1782                          */
1783                         if (!scmd->result)
1784                                 scmd->result |= (DRIVER_TIMEOUT << 24);
1785                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: flush finish"
1786                                                         " cmd: %p\n",
1787                                                         current->comm, scmd));
1788                         scsi_finish_command(scmd);
1789                 }
1790         }
1791 }
1792 EXPORT_SYMBOL(scsi_eh_flush_done_q);
1793
1794 /**
1795  * scsi_unjam_host - Attempt to fix a host which has a cmd that failed.
1796  * @shost:      Host to unjam.
1797  *
1798  * Notes:
1799  *    When we come in here, we *know* that all commands on the bus have
1800  *    either completed, failed or timed out.  we also know that no further
1801  *    commands are being sent to the host, so things are relatively quiet
1802  *    and we have freedom to fiddle with things as we wish.
1803  *
1804  *    This is only the *default* implementation.  it is possible for
1805  *    individual drivers to supply their own version of this function, and
1806  *    if the maintainer wishes to do this, it is strongly suggested that
1807  *    this function be taken as a template and modified.  this function
1808  *    was designed to correctly handle problems for about 95% of the
1809  *    different cases out there, and it should always provide at least a
1810  *    reasonable amount of error recovery.
1811  *
1812  *    Any command marked 'failed' or 'timeout' must eventually have
1813  *    scsi_finish_cmd() called for it.  we do all of the retry stuff
1814  *    here, so when we restart the host after we return it should have an
1815  *    empty queue.
1816  */
1817 static void scsi_unjam_host(struct Scsi_Host *shost)
1818 {
1819         unsigned long flags;
1820         LIST_HEAD(eh_work_q);
1821         LIST_HEAD(eh_done_q);
1822
1823         spin_lock_irqsave(shost->host_lock, flags);
1824         list_splice_init(&shost->eh_cmd_q, &eh_work_q);
1825         spin_unlock_irqrestore(shost->host_lock, flags);
1826
1827         SCSI_LOG_ERROR_RECOVERY(1, scsi_eh_prt_fail_stats(shost, &eh_work_q));
1828
1829         if (!scsi_eh_get_sense(&eh_work_q, &eh_done_q))
1830                 if (!scsi_eh_abort_cmds(&eh_work_q, &eh_done_q))
1831                         scsi_eh_ready_devs(shost, &eh_work_q, &eh_done_q);
1832
1833         scsi_eh_flush_done_q(&eh_done_q);
1834 }
1835
1836 /**
1837  * scsi_error_handler - SCSI error handler thread
1838  * @data:       Host for which we are running.
1839  *
1840  * Notes:
1841  *    This is the main error handling loop.  This is run as a kernel thread
1842  *    for every SCSI host and handles all error handling activity.
1843  */
1844 int scsi_error_handler(void *data)
1845 {
1846         struct Scsi_Host *shost = data;
1847
1848         /*
1849          * We use TASK_INTERRUPTIBLE so that the thread is not
1850          * counted against the load average as a running process.
1851          * We never actually get interrupted because kthread_run
1852          * disables signal delivery for the created thread.
1853          */
1854         while (true) {
1855                 /*
1856                  * The sequence in kthread_stop() sets the stop flag first
1857                  * then wakes the process.  To avoid missed wakeups, the task
1858                  * should always be in a non running state before the stop
1859                  * flag is checked
1860                  */
1861                 set_current_state(TASK_INTERRUPTIBLE);
1862                 if (kthread_should_stop())
1863                         break;
1864
1865                 if ((shost->host_failed == 0 && shost->host_eh_scheduled == 0) ||
1866                     shost->host_failed != shost->host_busy) {
1867                         SCSI_LOG_ERROR_RECOVERY(1,
1868                                 printk("Error handler scsi_eh_%d sleeping\n",
1869                                         shost->host_no));
1870                         schedule();
1871                         continue;
1872                 }
1873
1874                 __set_current_state(TASK_RUNNING);
1875                 SCSI_LOG_ERROR_RECOVERY(1,
1876                         printk("Error handler scsi_eh_%d waking up\n",
1877                                 shost->host_no));
1878
1879                 /*
1880                  * We have a host that is failing for some reason.  Figure out
1881                  * what we need to do to get it up and online again (if we can).
1882                  * If we fail, we end up taking the thing offline.
1883                  */
1884                 if (!shost->eh_noresume && scsi_autopm_get_host(shost) != 0) {
1885                         SCSI_LOG_ERROR_RECOVERY(1,
1886                                 printk(KERN_ERR "Error handler scsi_eh_%d "
1887                                                 "unable to autoresume\n",
1888                                                 shost->host_no));
1889                         continue;
1890                 }
1891
1892                 if (shost->transportt->eh_strategy_handler)
1893                         shost->transportt->eh_strategy_handler(shost);
1894                 else
1895                         scsi_unjam_host(shost);
1896
1897                 /*
1898                  * Note - if the above fails completely, the action is to take
1899                  * individual devices offline and flush the queue of any
1900                  * outstanding requests that may have been pending.  When we
1901                  * restart, we restart any I/O to any other devices on the bus
1902                  * which are still online.
1903                  */
1904                 scsi_restart_operations(shost);
1905                 if (!shost->eh_noresume)
1906                         scsi_autopm_put_host(shost);
1907         }
1908         __set_current_state(TASK_RUNNING);
1909
1910         SCSI_LOG_ERROR_RECOVERY(1,
1911                 printk("Error handler scsi_eh_%d exiting\n", shost->host_no));
1912         shost->ehandler = NULL;
1913         return 0;
1914 }
1915
1916 /*
1917  * Function:    scsi_report_bus_reset()
1918  *
1919  * Purpose:     Utility function used by low-level drivers to report that
1920  *              they have observed a bus reset on the bus being handled.
1921  *
1922  * Arguments:   shost       - Host in question
1923  *              channel     - channel on which reset was observed.
1924  *
1925  * Returns:     Nothing
1926  *
1927  * Lock status: Host lock must be held.
1928  *
1929  * Notes:       This only needs to be called if the reset is one which
1930  *              originates from an unknown location.  Resets originated
1931  *              by the mid-level itself don't need to call this, but there
1932  *              should be no harm.
1933  *
1934  *              The main purpose of this is to make sure that a CHECK_CONDITION
1935  *              is properly treated.
1936  */
1937 void scsi_report_bus_reset(struct Scsi_Host *shost, int channel)
1938 {
1939         struct scsi_device *sdev;
1940
1941         __shost_for_each_device(sdev, shost) {
1942                 if (channel == sdev_channel(sdev))
1943                         __scsi_report_device_reset(sdev, NULL);
1944         }
1945 }
1946 EXPORT_SYMBOL(scsi_report_bus_reset);
1947
1948 /*
1949  * Function:    scsi_report_device_reset()
1950  *
1951  * Purpose:     Utility function used by low-level drivers to report that
1952  *              they have observed a device reset on the device being handled.
1953  *
1954  * Arguments:   shost       - Host in question
1955  *              channel     - channel on which reset was observed
1956  *              target      - target on which reset was observed
1957  *
1958  * Returns:     Nothing
1959  *
1960  * Lock status: Host lock must be held
1961  *
1962  * Notes:       This only needs to be called if the reset is one which
1963  *              originates from an unknown location.  Resets originated
1964  *              by the mid-level itself don't need to call this, but there
1965  *              should be no harm.
1966  *
1967  *              The main purpose of this is to make sure that a CHECK_CONDITION
1968  *              is properly treated.
1969  */
1970 void scsi_report_device_reset(struct Scsi_Host *shost, int channel, int target)
1971 {
1972         struct scsi_device *sdev;
1973
1974         __shost_for_each_device(sdev, shost) {
1975                 if (channel == sdev_channel(sdev) &&
1976                     target == sdev_id(sdev))
1977                         __scsi_report_device_reset(sdev, NULL);
1978         }
1979 }
1980 EXPORT_SYMBOL(scsi_report_device_reset);
1981
1982 static void
1983 scsi_reset_provider_done_command(struct scsi_cmnd *scmd)
1984 {
1985 }
1986
1987 /*
1988  * Function:    scsi_reset_provider
1989  *
1990  * Purpose:     Send requested reset to a bus or device at any phase.
1991  *
1992  * Arguments:   device  - device to send reset to
1993  *              flag - reset type (see scsi.h)
1994  *
1995  * Returns:     SUCCESS/FAILURE.
1996  *
1997  * Notes:       This is used by the SCSI Generic driver to provide
1998  *              Bus/Device reset capability.
1999  */
2000 int
2001 scsi_reset_provider(struct scsi_device *dev, int flag)
2002 {
2003         struct scsi_cmnd *scmd;
2004         struct Scsi_Host *shost = dev->host;
2005         struct request req;
2006         unsigned long flags;
2007         int rtn;
2008
2009         if (scsi_autopm_get_host(shost) < 0)
2010                 return FAILED;
2011
2012         scmd = scsi_get_command(dev, GFP_KERNEL);
2013         blk_rq_init(NULL, &req);
2014         scmd->request = &req;
2015
2016         scmd->cmnd = req.cmd;
2017
2018         scmd->scsi_done         = scsi_reset_provider_done_command;
2019         memset(&scmd->sdb, 0, sizeof(scmd->sdb));
2020
2021         scmd->cmd_len                   = 0;
2022
2023         scmd->sc_data_direction         = DMA_BIDIRECTIONAL;
2024
2025         spin_lock_irqsave(shost->host_lock, flags);
2026         shost->tmf_in_progress = 1;
2027         spin_unlock_irqrestore(shost->host_lock, flags);
2028
2029         switch (flag) {
2030         case SCSI_TRY_RESET_DEVICE:
2031                 rtn = scsi_try_bus_device_reset(scmd);
2032                 if (rtn == SUCCESS)
2033                         break;
2034                 /* FALLTHROUGH */
2035         case SCSI_TRY_RESET_TARGET:
2036                 rtn = scsi_try_target_reset(scmd);
2037                 if (rtn == SUCCESS)
2038                         break;
2039                 /* FALLTHROUGH */
2040         case SCSI_TRY_RESET_BUS:
2041                 rtn = scsi_try_bus_reset(scmd);
2042                 if (rtn == SUCCESS)
2043                         break;
2044                 /* FALLTHROUGH */
2045         case SCSI_TRY_RESET_HOST:
2046                 rtn = scsi_try_host_reset(scmd);
2047                 break;
2048         default:
2049                 rtn = FAILED;
2050         }
2051
2052         spin_lock_irqsave(shost->host_lock, flags);
2053         shost->tmf_in_progress = 0;
2054         spin_unlock_irqrestore(shost->host_lock, flags);
2055
2056         /*
2057          * be sure to wake up anyone who was sleeping or had their queue
2058          * suspended while we performed the TMF.
2059          */
2060         SCSI_LOG_ERROR_RECOVERY(3,
2061                 printk("%s: waking up host to restart after TMF\n",
2062                 __func__));
2063
2064         wake_up(&shost->host_wait);
2065
2066         scsi_run_host_queues(shost);
2067
2068         scsi_next_command(scmd);
2069         scsi_autopm_put_host(shost);
2070         return rtn;
2071 }
2072 EXPORT_SYMBOL(scsi_reset_provider);
2073
2074 /**
2075  * scsi_normalize_sense - normalize main elements from either fixed or
2076  *                      descriptor sense data format into a common format.
2077  *
2078  * @sense_buffer:       byte array containing sense data returned by device
2079  * @sb_len:             number of valid bytes in sense_buffer
2080  * @sshdr:              pointer to instance of structure that common
2081  *                      elements are written to.
2082  *
2083  * Notes:
2084  *      The "main elements" from sense data are: response_code, sense_key,
2085  *      asc, ascq and additional_length (only for descriptor format).
2086  *
2087  *      Typically this function can be called after a device has
2088  *      responded to a SCSI command with the CHECK_CONDITION status.
2089  *
2090  * Return value:
2091  *      1 if valid sense data information found, else 0;
2092  */
2093 int scsi_normalize_sense(const u8 *sense_buffer, int sb_len,
2094                          struct scsi_sense_hdr *sshdr)
2095 {
2096         if (!sense_buffer || !sb_len)
2097                 return 0;
2098
2099         memset(sshdr, 0, sizeof(struct scsi_sense_hdr));
2100
2101         sshdr->response_code = (sense_buffer[0] & 0x7f);
2102
2103         if (!scsi_sense_valid(sshdr))
2104                 return 0;
2105
2106         if (sshdr->response_code >= 0x72) {
2107                 /*
2108                  * descriptor format
2109                  */
2110                 if (sb_len > 1)
2111                         sshdr->sense_key = (sense_buffer[1] & 0xf);
2112                 if (sb_len > 2)
2113                         sshdr->asc = sense_buffer[2];
2114                 if (sb_len > 3)
2115                         sshdr->ascq = sense_buffer[3];
2116                 if (sb_len > 7)
2117                         sshdr->additional_length = sense_buffer[7];
2118         } else {
2119                 /*
2120                  * fixed format
2121                  */
2122                 if (sb_len > 2)
2123                         sshdr->sense_key = (sense_buffer[2] & 0xf);
2124                 if (sb_len > 7) {
2125                         sb_len = (sb_len < (sense_buffer[7] + 8)) ?
2126                                          sb_len : (sense_buffer[7] + 8);
2127                         if (sb_len > 12)
2128                                 sshdr->asc = sense_buffer[12];
2129                         if (sb_len > 13)
2130                                 sshdr->ascq = sense_buffer[13];
2131                 }
2132         }
2133
2134         return 1;
2135 }
2136 EXPORT_SYMBOL(scsi_normalize_sense);
2137
2138 int scsi_command_normalize_sense(struct scsi_cmnd *cmd,
2139                                  struct scsi_sense_hdr *sshdr)
2140 {
2141         return scsi_normalize_sense(cmd->sense_buffer,
2142                         SCSI_SENSE_BUFFERSIZE, sshdr);
2143 }
2144 EXPORT_SYMBOL(scsi_command_normalize_sense);
2145
2146 /**
2147  * scsi_sense_desc_find - search for a given descriptor type in descriptor sense data format.
2148  * @sense_buffer:       byte array of descriptor format sense data
2149  * @sb_len:             number of valid bytes in sense_buffer
2150  * @desc_type:          value of descriptor type to find
2151  *                      (e.g. 0 -> information)
2152  *
2153  * Notes:
2154  *      only valid when sense data is in descriptor format
2155  *
2156  * Return value:
2157  *      pointer to start of (first) descriptor if found else NULL
2158  */
2159 const u8 * scsi_sense_desc_find(const u8 * sense_buffer, int sb_len,
2160                                 int desc_type)
2161 {
2162         int add_sen_len, add_len, desc_len, k;
2163         const u8 * descp;
2164
2165         if ((sb_len < 8) || (0 == (add_sen_len = sense_buffer[7])))
2166                 return NULL;
2167         if ((sense_buffer[0] < 0x72) || (sense_buffer[0] > 0x73))
2168                 return NULL;
2169         add_sen_len = (add_sen_len < (sb_len - 8)) ?
2170                         add_sen_len : (sb_len - 8);
2171         descp = &sense_buffer[8];
2172         for (desc_len = 0, k = 0; k < add_sen_len; k += desc_len) {
2173                 descp += desc_len;
2174                 add_len = (k < (add_sen_len - 1)) ? descp[1]: -1;
2175                 desc_len = add_len + 2;
2176                 if (descp[0] == desc_type)
2177                         return descp;
2178                 if (add_len < 0) // short descriptor ??
2179                         break;
2180         }
2181         return NULL;
2182 }
2183 EXPORT_SYMBOL(scsi_sense_desc_find);
2184
2185 /**
2186  * scsi_get_sense_info_fld - get information field from sense data (either fixed or descriptor format)
2187  * @sense_buffer:       byte array of sense data
2188  * @sb_len:             number of valid bytes in sense_buffer
2189  * @info_out:           pointer to 64 integer where 8 or 4 byte information
2190  *                      field will be placed if found.
2191  *
2192  * Return value:
2193  *      1 if information field found, 0 if not found.
2194  */
2195 int scsi_get_sense_info_fld(const u8 * sense_buffer, int sb_len,
2196                             u64 * info_out)
2197 {
2198         int j;
2199         const u8 * ucp;
2200         u64 ull;
2201
2202         if (sb_len < 7)
2203                 return 0;
2204         switch (sense_buffer[0] & 0x7f) {
2205         case 0x70:
2206         case 0x71:
2207                 if (sense_buffer[0] & 0x80) {
2208                         *info_out = (sense_buffer[3] << 24) +
2209                                     (sense_buffer[4] << 16) +
2210                                     (sense_buffer[5] << 8) + sense_buffer[6];
2211                         return 1;
2212                 } else
2213                         return 0;
2214         case 0x72:
2215         case 0x73:
2216                 ucp = scsi_sense_desc_find(sense_buffer, sb_len,
2217                                            0 /* info desc */);
2218                 if (ucp && (0xa == ucp[1])) {
2219                         ull = 0;
2220                         for (j = 0; j < 8; ++j) {
2221                                 if (j > 0)
2222                                         ull <<= 8;
2223                                 ull |= ucp[4 + j];
2224                         }
2225                         *info_out = ull;
2226                         return 1;
2227                 } else
2228                         return 0;
2229         default:
2230                 return 0;
2231         }
2232 }
2233 EXPORT_SYMBOL(scsi_get_sense_info_fld);
2234
2235 /**
2236  * scsi_build_sense_buffer - build sense data in a buffer
2237  * @desc:       Sense format (non zero == descriptor format,
2238  *              0 == fixed format)
2239  * @buf:        Where to build sense data
2240  * @key:        Sense key
2241  * @asc:        Additional sense code
2242  * @ascq:       Additional sense code qualifier
2243  *
2244  **/
2245 void scsi_build_sense_buffer(int desc, u8 *buf, u8 key, u8 asc, u8 ascq)
2246 {
2247         if (desc) {
2248                 buf[0] = 0x72;  /* descriptor, current */
2249                 buf[1] = key;
2250                 buf[2] = asc;
2251                 buf[3] = ascq;
2252                 buf[7] = 0;
2253         } else {
2254                 buf[0] = 0x70;  /* fixed, current */
2255                 buf[2] = key;
2256                 buf[7] = 0xa;
2257                 buf[12] = asc;
2258                 buf[13] = ascq;
2259         }
2260 }
2261 EXPORT_SYMBOL(scsi_build_sense_buffer);