Linux kernel & device driver programming

Cross-Referenced Linux and Device Driver Code

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Version: [ 2.6.11.8 ] [ 2.6.25 ] [ 2.6.25.8 ] [ 2.6.31.13 ] Architecture: [ i386 ]
  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/timer.h>
 20 #include <linux/string.h>
 21 #include <linux/kernel.h>
 22 #include <linux/freezer.h>
 23 #include <linux/kthread.h>
 24 #include <linux/interrupt.h>
 25 #include <linux/blkdev.h>
 26 #include <linux/delay.h>
 27 
 28 #include <scsi/scsi.h>
 29 #include <scsi/scsi_cmnd.h>
 30 #include <scsi/scsi_dbg.h>
 31 #include <scsi/scsi_device.h>
 32 #include <scsi/scsi_eh.h>
 33 #include <scsi/scsi_transport.h>
 34 #include <scsi/scsi_host.h>
 35 #include <scsi/scsi_ioctl.h>
 36 
 37 #include "scsi_priv.h"
 38 #include "scsi_logging.h"
 39 #include "scsi_transport_api.h"
 40 
 41 #define SENSE_TIMEOUT           (10*HZ)
 42 
 43 /*
 44  * These should *probably* be handled by the host itself.
 45  * Since it is allowed to sleep, it probably should.
 46  */
 47 #define BUS_RESET_SETTLE_TIME   (10)
 48 #define HOST_RESET_SETTLE_TIME  (10)
 49 
 50 /* called with shost->host_lock held */
 51 void scsi_eh_wakeup(struct Scsi_Host *shost)
 52 {
 53         if (shost->host_busy == shost->host_failed) {
 54                 wake_up_process(shost->ehandler);
 55                 SCSI_LOG_ERROR_RECOVERY(5,
 56                                 printk("Waking error handler thread\n"));
 57         }
 58 }
 59 
 60 /**
 61  * scsi_schedule_eh - schedule EH for SCSI host
 62  * @shost:      SCSI host to invoke error handling on.
 63  *
 64  * Schedule SCSI EH without scmd.
 65  */
 66 void scsi_schedule_eh(struct Scsi_Host *shost)
 67 {
 68         unsigned long flags;
 69 
 70         spin_lock_irqsave(shost->host_lock, flags);
 71 
 72         if (scsi_host_set_state(shost, SHOST_RECOVERY) == 0 ||
 73             scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY) == 0) {
 74                 shost->host_eh_scheduled++;
 75                 scsi_eh_wakeup(shost);
 76         }
 77 
 78         spin_unlock_irqrestore(shost->host_lock, flags);
 79 }
 80 EXPORT_SYMBOL_GPL(scsi_schedule_eh);
 81 
 82 /**
 83  * scsi_eh_scmd_add - add scsi cmd to error handling.
 84  * @scmd:       scmd to run eh on.
 85  * @eh_flag:    optional SCSI_EH flag.
 86  *
 87  * Return value:
 88  *      0 on failure.
 89  */
 90 int scsi_eh_scmd_add(struct scsi_cmnd *scmd, int eh_flag)
 91 {
 92         struct Scsi_Host *shost = scmd->device->host;
 93         unsigned long flags;
 94         int ret = 0;
 95 
 96         if (!shost->ehandler)
 97                 return 0;
 98 
 99         spin_lock_irqsave(shost->host_lock, flags);
100         if (scsi_host_set_state(shost, SHOST_RECOVERY))
101                 if (scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY))
102                         goto out_unlock;
103 
104         ret = 1;
105         scmd->eh_eflags |= eh_flag;
106         list_add_tail(&scmd->eh_entry, &shost->eh_cmd_q);
107         shost->host_failed++;
108         scsi_eh_wakeup(shost);
109  out_unlock:
110         spin_unlock_irqrestore(shost->host_lock, flags);
111         return ret;
112 }
113 
114 /**
115  * scsi_add_timer - Start timeout timer for a single scsi command.
116  * @scmd:       scsi command that is about to start running.
117  * @timeout:    amount of time to allow this command to run.
118  * @complete:   timeout function to call if timer isn't canceled.
119  *
120  * Notes:
121  *    This should be turned into an inline function.  Each scsi command
122  *    has its own timer, and as it is added to the queue, we set up the
123  *    timer.  When the command completes, we cancel the timer.
124  */
125 void scsi_add_timer(struct scsi_cmnd *scmd, int timeout,
126                     void (*complete)(struct scsi_cmnd *))
127 {
128 
129         /*
130          * If the clock was already running for this command, then
131          * first delete the timer.  The timer handling code gets rather
132          * confused if we don't do this.
133          */
134         if (scmd->eh_timeout.function)
135                 del_timer(&scmd->eh_timeout);
136 
137         scmd->eh_timeout.data = (unsigned long)scmd;
138         scmd->eh_timeout.expires = jiffies + timeout;
139         scmd->eh_timeout.function = (void (*)(unsigned long)) complete;
140 
141         SCSI_LOG_ERROR_RECOVERY(5, printk("%s: scmd: %p, time:"
142                                           " %d, (%p)\n", __FUNCTION__,
143                                           scmd, timeout, complete));
144 
145         add_timer(&scmd->eh_timeout);
146 }
147 
148 /**
149  * scsi_delete_timer - Delete/cancel timer for a given function.
150  * @scmd:       Cmd that we are canceling timer for
151  *
152  * Notes:
153  *     This should be turned into an inline function.
154  *
155  * Return value:
156  *     1 if we were able to detach the timer.  0 if we blew it, and the
157  *     timer function has already started to run.
158  */
159 int scsi_delete_timer(struct scsi_cmnd *scmd)
160 {
161         int rtn;
162 
163         rtn = del_timer(&scmd->eh_timeout);
164 
165         SCSI_LOG_ERROR_RECOVERY(5, printk("%s: scmd: %p,"
166                                          " rtn: %d\n", __FUNCTION__,
167                                          scmd, rtn));
168 
169         scmd->eh_timeout.data = (unsigned long)NULL;
170         scmd->eh_timeout.function = NULL;
171 
172         return rtn;
173 }
174 
175 /**
176  * scsi_times_out - Timeout function for normal scsi commands.
177  * @scmd:       Cmd that is timing out.
178  *
179  * Notes:
180  *     We do not need to lock this.  There is the potential for a race
181  *     only in that the normal completion handling might run, but if the
182  *     normal completion function determines that the timer has already
183  *     fired, then it mustn't do anything.
184  */
185 void scsi_times_out(struct scsi_cmnd *scmd)
186 {
187         enum scsi_eh_timer_return (* eh_timed_out)(struct scsi_cmnd *);
188 
189         scsi_log_completion(scmd, TIMEOUT_ERROR);
190 
191         if (scmd->device->host->transportt->eh_timed_out)
192                 eh_timed_out = scmd->device->host->transportt->eh_timed_out;
193         else if (scmd->device->host->hostt->eh_timed_out)
194                 eh_timed_out = scmd->device->host->hostt->eh_timed_out;
195         else
196                 eh_timed_out = NULL;
197 
198         if (eh_timed_out)
199                 switch (eh_timed_out(scmd)) {
200                 case EH_HANDLED:
201                         __scsi_done(scmd);
202                         return;
203                 case EH_RESET_TIMER:
204                         scsi_add_timer(scmd, scmd->timeout_per_command,
205                                        scsi_times_out);
206                         return;
207                 case EH_NOT_HANDLED:
208                         break;
209                 }
210 
211         if (unlikely(!scsi_eh_scmd_add(scmd, SCSI_EH_CANCEL_CMD))) {
212                 scmd->result |= DID_TIME_OUT << 16;
213                 __scsi_done(scmd);
214         }
215 }
216 
217 /**
218  * scsi_block_when_processing_errors - Prevent cmds from being queued.
219  * @sdev:       Device on which we are performing recovery.
220  *
221  * Description:
222  *     We block until the host is out of error recovery, and then check to
223  *     see whether the host or the device is offline.
224  *
225  * Return value:
226  *     0 when dev was taken offline by error recovery. 1 OK to proceed.
227  */
228 int scsi_block_when_processing_errors(struct scsi_device *sdev)
229 {
230         int online;
231 
232         wait_event(sdev->host->host_wait, !scsi_host_in_recovery(sdev->host));
233 
234         online = scsi_device_online(sdev);
235 
236         SCSI_LOG_ERROR_RECOVERY(5, printk("%s: rtn: %d\n", __FUNCTION__,
237                                           online));
238 
239         return online;
240 }
241 EXPORT_SYMBOL(scsi_block_when_processing_errors);
242 
243 #ifdef CONFIG_SCSI_LOGGING
244 /**
245  * scsi_eh_prt_fail_stats - Log info on failures.
246  * @shost:      scsi host being recovered.
247  * @work_q:     Queue of scsi cmds to process.
248  */
249 static inline void scsi_eh_prt_fail_stats(struct Scsi_Host *shost,
250                                           struct list_head *work_q)
251 {
252         struct scsi_cmnd *scmd;
253         struct scsi_device *sdev;
254         int total_failures = 0;
255         int cmd_failed = 0;
256         int cmd_cancel = 0;
257         int devices_failed = 0;
258 
259         shost_for_each_device(sdev, shost) {
260                 list_for_each_entry(scmd, work_q, eh_entry) {
261                         if (scmd->device == sdev) {
262                                 ++total_failures;
263                                 if (scmd->eh_eflags & SCSI_EH_CANCEL_CMD)
264                                         ++cmd_cancel;
265                                 else 
266                                         ++cmd_failed;
267                         }
268                 }
269 
270                 if (cmd_cancel || cmd_failed) {
271                         SCSI_LOG_ERROR_RECOVERY(3,
272                                 sdev_printk(KERN_INFO, sdev,
273                                             "%s: cmds failed: %d, cancel: %d\n",
274                                             __FUNCTION__, cmd_failed,
275                                             cmd_cancel));
276                         cmd_cancel = 0;
277                         cmd_failed = 0;
278                         ++devices_failed;
279                 }
280         }
281 
282         SCSI_LOG_ERROR_RECOVERY(2, printk("Total of %d commands on %d"
283                                           " devices require eh work\n",
284                                   total_failures, devices_failed));
285 }
286 #endif
287 
288 /**
289  * scsi_check_sense - Examine scsi cmd sense
290  * @scmd:       Cmd to have sense checked.
291  *
292  * Return value:
293  *      SUCCESS or FAILED or NEEDS_RETRY
294  *
295  * Notes:
296  *      When a deferred error is detected the current command has
297  *      not been executed and needs retrying.
298  */
299 static int scsi_check_sense(struct scsi_cmnd *scmd)
300 {
301         struct scsi_sense_hdr sshdr;
302 
303         if (! scsi_command_normalize_sense(scmd, &sshdr))
304                 return FAILED;  /* no valid sense data */
305 
306         if (scsi_sense_is_deferred(&sshdr))
307                 return NEEDS_RETRY;
308 
309         /*
310          * Previous logic looked for FILEMARK, EOM or ILI which are
311          * mainly associated with tapes and returned SUCCESS.
312          */
313         if (sshdr.response_code == 0x70) {
314                 /* fixed format */
315                 if (scmd->sense_buffer[2] & 0xe0)
316                         return SUCCESS;
317         } else {
318                 /*
319                  * descriptor format: look for "stream commands sense data
320                  * descriptor" (see SSC-3). Assume single sense data
321                  * descriptor. Ignore ILI from SBC-2 READ LONG and WRITE LONG.
322                  */
323                 if ((sshdr.additional_length > 3) &&
324                     (scmd->sense_buffer[8] == 0x4) &&
325                     (scmd->sense_buffer[11] & 0xe0))
326                         return SUCCESS;
327         }
328 
329         switch (sshdr.sense_key) {
330         case NO_SENSE:
331                 return SUCCESS;
332         case RECOVERED_ERROR:
333                 return /* soft_error */ SUCCESS;
334 
335         case ABORTED_COMMAND:
336                 return NEEDS_RETRY;
337         case NOT_READY:
338         case UNIT_ATTENTION:
339                 /*
340                  * if we are expecting a cc/ua because of a bus reset that we
341                  * performed, treat this just as a retry.  otherwise this is
342                  * information that we should pass up to the upper-level driver
343                  * so that we can deal with it there.
344                  */
345                 if (scmd->device->expecting_cc_ua) {
346                         scmd->device->expecting_cc_ua = 0;
347                         return NEEDS_RETRY;
348                 }
349                 /*
350                  * if the device is in the process of becoming ready, we 
351                  * should retry.
352                  */
353                 if ((sshdr.asc == 0x04) && (sshdr.ascq == 0x01))
354                         return NEEDS_RETRY;
355                 /*
356                  * if the device is not started, we need to wake
357                  * the error handler to start the motor
358                  */
359                 if (scmd->device->allow_restart &&
360                     (sshdr.asc == 0x04) && (sshdr.ascq == 0x02))
361                         return FAILED;
362                 return SUCCESS;
363 
364                 /* these three are not supported */
365         case COPY_ABORTED:
366         case VOLUME_OVERFLOW:
367         case MISCOMPARE:
368                 return SUCCESS;
369 
370         case MEDIUM_ERROR:
371                 if (sshdr.asc == 0x11 || /* UNRECOVERED READ ERR */
372                     sshdr.asc == 0x13 || /* AMNF DATA FIELD */
373                     sshdr.asc == 0x14) { /* RECORD NOT FOUND */
374                         return SUCCESS;
375                 }
376                 return NEEDS_RETRY;
377 
378         case HARDWARE_ERROR:
379                 if (scmd->device->retry_hwerror)
380                         return NEEDS_RETRY;
381                 else
382                         return SUCCESS;
383 
384         case ILLEGAL_REQUEST:
385         case BLANK_CHECK:
386         case DATA_PROTECT:
387         default:
388                 return SUCCESS;
389         }
390 }
391 
392 /**
393  * scsi_eh_completed_normally - Disposition a eh cmd on return from LLD.
394  * @scmd:       SCSI cmd to examine.
395  *
396  * Notes:
397  *    This is *only* called when we are examining the status of commands
398  *    queued during error recovery.  the main difference here is that we
399  *    don't allow for the possibility of retries here, and we are a lot
400  *    more restrictive about what we consider acceptable.
401  */
402 static int scsi_eh_completed_normally(struct scsi_cmnd *scmd)
403 {
404         /*
405          * first check the host byte, to see if there is anything in there
406          * that would indicate what we need to do.
407          */
408         if (host_byte(scmd->result) == DID_RESET) {
409                 /*
410                  * rats.  we are already in the error handler, so we now
411                  * get to try and figure out what to do next.  if the sense
412                  * is valid, we have a pretty good idea of what to do.
413                  * if not, we mark it as FAILED.
414                  */
415                 return scsi_check_sense(scmd);
416         }
417         if (host_byte(scmd->result) != DID_OK)
418                 return FAILED;
419 
420         /*
421          * next, check the message byte.
422          */
423         if (msg_byte(scmd->result) != COMMAND_COMPLETE)
424                 return FAILED;
425 
426         /*
427          * now, check the status byte to see if this indicates
428          * anything special.
429          */
430         switch (status_byte(scmd->result)) {
431         case GOOD:
432         case COMMAND_TERMINATED:
433                 return SUCCESS;
434         case CHECK_CONDITION:
435                 return scsi_check_sense(scmd);
436         case CONDITION_GOOD:
437         case INTERMEDIATE_GOOD:
438         case INTERMEDIATE_C_GOOD:
439                 /*
440                  * who knows?  FIXME(eric)
441                  */
442                 return SUCCESS;
443         case BUSY:
444         case QUEUE_FULL:
445         case RESERVATION_CONFLICT:
446         default:
447                 return FAILED;
448         }
449         return FAILED;
450 }
451 
452 /**
453  * scsi_eh_done - Completion function for error handling.
454  * @scmd:       Cmd that is done.
455  */
456 static void scsi_eh_done(struct scsi_cmnd *scmd)
457 {
458         struct completion     *eh_action;
459 
460         SCSI_LOG_ERROR_RECOVERY(3,
461                 printk("%s scmd: %p result: %x\n",
462                         __FUNCTION__, scmd, scmd->result));
463 
464         eh_action = scmd->device->host->eh_action;
465         if (eh_action)
466                 complete(eh_action);
467 }
468 
469 /**
470  * scsi_try_host_reset - ask host adapter to reset itself
471  * @scmd:       SCSI cmd to send hsot reset.
472  */
473 static int scsi_try_host_reset(struct scsi_cmnd *scmd)
474 {
475         unsigned long flags;
476         int rtn;
477 
478         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Snd Host RST\n",
479                                           __FUNCTION__));
480 
481         if (!scmd->device->host->hostt->eh_host_reset_handler)
482                 return FAILED;
483 
484         rtn = scmd->device->host->hostt->eh_host_reset_handler(scmd);
485 
486         if (rtn == SUCCESS) {
487                 if (!scmd->device->host->hostt->skip_settle_delay)
488                         ssleep(HOST_RESET_SETTLE_TIME);
489                 spin_lock_irqsave(scmd->device->host->host_lock, flags);
490                 scsi_report_bus_reset(scmd->device->host,
491                                       scmd_channel(scmd));
492                 spin_unlock_irqrestore(scmd->device->host->host_lock, flags);
493         }
494 
495         return rtn;
496 }
497 
498 /**
499  * scsi_try_bus_reset - ask host to perform a bus reset
500  * @scmd:       SCSI cmd to send bus reset.
501  */
502 static int scsi_try_bus_reset(struct scsi_cmnd *scmd)
503 {
504         unsigned long flags;
505         int rtn;
506 
507         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Snd Bus RST\n",
508                                           __FUNCTION__));
509 
510         if (!scmd->device->host->hostt->eh_bus_reset_handler)
511                 return FAILED;
512 
513         rtn = scmd->device->host->hostt->eh_bus_reset_handler(scmd);
514 
515         if (rtn == SUCCESS) {
516                 if (!scmd->device->host->hostt->skip_settle_delay)
517                         ssleep(BUS_RESET_SETTLE_TIME);
518                 spin_lock_irqsave(scmd->device->host->host_lock, flags);
519                 scsi_report_bus_reset(scmd->device->host,
520                                       scmd_channel(scmd));
521                 spin_unlock_irqrestore(scmd->device->host->host_lock, flags);
522         }
523 
524         return rtn;
525 }
526 
527 /**
528  * scsi_try_bus_device_reset - Ask host to perform a BDR on a dev
529  * @scmd:       SCSI cmd used to send BDR
530  *
531  * Notes:
532  *    There is no timeout for this operation.  if this operation is
533  *    unreliable for a given host, then the host itself needs to put a
534  *    timer on it, and set the host back to a consistent state prior to
535  *    returning.
536  */
537 static int scsi_try_bus_device_reset(struct scsi_cmnd *scmd)
538 {
539         int rtn;
540 
541         if (!scmd->device->host->hostt->eh_device_reset_handler)
542                 return FAILED;
543 
544         rtn = scmd->device->host->hostt->eh_device_reset_handler(scmd);
545         if (rtn == SUCCESS) {
546                 scmd->device->was_reset = 1;
547                 scmd->device->expecting_cc_ua = 1;
548         }
549 
550         return rtn;
551 }
552 
553 static int __scsi_try_to_abort_cmd(struct scsi_cmnd *scmd)
554 {
555         if (!scmd->device->host->hostt->eh_abort_handler)
556                 return FAILED;
557 
558         return scmd->device->host->hostt->eh_abort_handler(scmd);
559 }
560 
561 /**
562  * scsi_try_to_abort_cmd - Ask host to abort a running command.
563  * @scmd:       SCSI cmd to abort from Lower Level.
564  *
565  * Notes:
566  *    This function will not return until the user's completion function
567  *    has been called.  there is no timeout on this operation.  if the
568  *    author of the low-level driver wishes this operation to be timed,
569  *    they can provide this facility themselves.  helper functions in
570  *    scsi_error.c can be supplied to make this easier to do.
571  */
572 static int scsi_try_to_abort_cmd(struct scsi_cmnd *scmd)
573 {
574         /*
575          * scsi_done was called just after the command timed out and before
576          * we had a chance to process it. (db)
577          */
578         if (scmd->serial_number == 0)
579                 return SUCCESS;
580         return __scsi_try_to_abort_cmd(scmd);
581 }
582 
583 static void scsi_abort_eh_cmnd(struct scsi_cmnd *scmd)
584 {
585         if (__scsi_try_to_abort_cmd(scmd) != SUCCESS)
586                 if (scsi_try_bus_device_reset(scmd) != SUCCESS)
587                         if (scsi_try_bus_reset(scmd) != SUCCESS)
588                                 scsi_try_host_reset(scmd);
589 }
590 
591 /**
592  * scsi_eh_prep_cmnd  - Save a scsi command info as part of error recory
593  * @scmd:       SCSI command structure to hijack
594  * @ses:        structure to save restore information
595  * @cmnd:       CDB to send. Can be NULL if no new cmnd is needed
596  * @cmnd_size:  size in bytes of @cmnd
597  * @sense_bytes: size of sense data to copy. or 0 (if != 0 @cmnd is ignored)
598  *
599  * This function is used to save a scsi command information before re-execution
600  * as part of the error recovery process.  If @sense_bytes is 0 the command
601  * sent must be one that does not transfer any data.  If @sense_bytes != 0
602  * @cmnd is ignored and this functions sets up a REQUEST_SENSE command
603  * and cmnd buffers to read @sense_bytes into @scmd->sense_buffer.
604  */
605 void scsi_eh_prep_cmnd(struct scsi_cmnd *scmd, struct scsi_eh_save *ses,
606                         unsigned char *cmnd, int cmnd_size, unsigned sense_bytes)
607 {
608         struct scsi_device *sdev = scmd->device;
609 
610         /*
611          * We need saved copies of a number of fields - this is because
612          * error handling may need to overwrite these with different values
613          * to run different commands, and once error handling is complete,
614          * we will need to restore these values prior to running the actual
615          * command.
616          */
617         ses->cmd_len = scmd->cmd_len;
618         memcpy(ses->cmnd, scmd->cmnd, sizeof(scmd->cmnd));
619         ses->data_direction = scmd->sc_data_direction;
620         ses->sdb = scmd->sdb;
621         ses->next_rq = scmd->request->next_rq;
622         ses->result = scmd->result;
623 
624         memset(&scmd->sdb, 0, sizeof(scmd->sdb));
625         scmd->request->next_rq = NULL;
626 
627         if (sense_bytes) {
628                 scmd->sdb.length = min_t(unsigned, SCSI_SENSE_BUFFERSIZE,
629                                          sense_bytes);
630                 sg_init_one(&ses->sense_sgl, scmd->sense_buffer,
631                             scmd->sdb.length);
632                 scmd->sdb.table.sgl = &ses->sense_sgl;
633                 scmd->sc_data_direction = DMA_FROM_DEVICE;
634                 scmd->sdb.table.nents = 1;
635                 memset(scmd->cmnd, 0, sizeof(scmd->cmnd));
636                 scmd->cmnd[0] = REQUEST_SENSE;
637                 scmd->cmnd[4] = scmd->sdb.length;
638                 scmd->cmd_len = COMMAND_SIZE(scmd->cmnd[0]);
639         } else {
640                 scmd->sc_data_direction = DMA_NONE;
641                 if (cmnd) {
642                         memset(scmd->cmnd, 0, sizeof(scmd->cmnd));
643                         memcpy(scmd->cmnd, cmnd, cmnd_size);
644                         scmd->cmd_len = COMMAND_SIZE(scmd->cmnd[0]);
645                 }
646         }
647 
648         scmd->underflow = 0;
649 
650         if (sdev->scsi_level <= SCSI_2 && sdev->scsi_level != SCSI_UNKNOWN)
651                 scmd->cmnd[1] = (scmd->cmnd[1] & 0x1f) |
652                         (sdev->lun << 5 & 0xe0);
653 
654         /*
655          * Zero the sense buffer.  The scsi spec mandates that any
656          * untransferred sense data should be interpreted as being zero.
657          */
658         memset(scmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);
659 }
660 EXPORT_SYMBOL(scsi_eh_prep_cmnd);
661 
662 /**
663  * scsi_eh_restore_cmnd  - Restore a scsi command info as part of error recory
664  * @scmd:       SCSI command structure to restore
665  * @ses:        saved information from a coresponding call to scsi_prep_eh_cmnd
666  *
667  * Undo any damage done by above scsi_prep_eh_cmnd().
668  */
669 void scsi_eh_restore_cmnd(struct scsi_cmnd* scmd, struct scsi_eh_save *ses)
670 {
671         /*
672          * Restore original data
673          */
674         scmd->cmd_len = ses->cmd_len;
675         memcpy(scmd->cmnd, ses->cmnd, sizeof(scmd->cmnd));
676         scmd->sc_data_direction = ses->data_direction;
677         scmd->sdb = ses->sdb;
678         scmd->request->next_rq = ses->next_rq;
679         scmd->result = ses->result;
680 }
681 EXPORT_SYMBOL(scsi_eh_restore_cmnd);
682 
683 /**
684  * scsi_send_eh_cmnd  - submit a scsi command as part of error recory
685  * @scmd:       SCSI command structure to hijack
686  * @cmnd:       CDB to send
687  * @cmnd_size:  size in bytes of @cmnd
688  * @timeout:    timeout for this request
689  * @sense_bytes: size of sense data to copy or 0
690  *
691  * This function is used to send a scsi command down to a target device
692  * as part of the error recovery process. See also scsi_eh_prep_cmnd() above.
693  *
694  * Return value:
695  *    SUCCESS or FAILED or NEEDS_RETRY
696  */
697 static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd,
698                              int cmnd_size, int timeout, unsigned sense_bytes)
699 {
700         struct scsi_device *sdev = scmd->device;
701         struct Scsi_Host *shost = sdev->host;
702         DECLARE_COMPLETION_ONSTACK(done);
703         unsigned long timeleft;
704         unsigned long flags;
705         struct scsi_eh_save ses;
706         int rtn;
707 
708         scsi_eh_prep_cmnd(scmd, &ses, cmnd, cmnd_size, sense_bytes);
709         shost->eh_action = &done;
710 
711         spin_lock_irqsave(shost->host_lock, flags);
712         scsi_log_send(scmd);
713         shost->hostt->queuecommand(scmd, scsi_eh_done);
714         spin_unlock_irqrestore(shost->host_lock, flags);
715 
716         timeleft = wait_for_completion_timeout(&done, timeout);
717 
718         shost->eh_action = NULL;
719 
720         scsi_log_completion(scmd, SUCCESS);
721 
722         SCSI_LOG_ERROR_RECOVERY(3,
723                 printk("%s: scmd: %p, timeleft: %ld\n",
724                         __FUNCTION__, scmd, timeleft));
725 
726         /*
727          * If there is time left scsi_eh_done got called, and we will
728          * examine the actual status codes to see whether the command
729          * actually did complete normally, else tell the host to forget
730          * about this command.
731          */
732         if (timeleft) {
733                 rtn = scsi_eh_completed_normally(scmd);
734                 SCSI_LOG_ERROR_RECOVERY(3,
735                         printk("%s: scsi_eh_completed_normally %x\n",
736                                __FUNCTION__, rtn));
737 
738                 switch (rtn) {
739                 case SUCCESS:
740                 case NEEDS_RETRY:
741                 case FAILED:
742                         break;
743                 default:
744                         rtn = FAILED;
745                         break;
746                 }
747         } else {
748                 scsi_abort_eh_cmnd(scmd);
749                 rtn = FAILED;
750         }
751 
752         scsi_eh_restore_cmnd(scmd, &ses);
753         return rtn;
754 }
755 
756 /**
757  * scsi_request_sense - Request sense data from a particular target.
758  * @scmd:       SCSI cmd for request sense.
759  *
760  * Notes:
761  *    Some hosts automatically obtain this information, others require
762  *    that we obtain it on our own. This function will *not* return until
763  *    the command either times out, or it completes.
764  */
765 static int scsi_request_sense(struct scsi_cmnd *scmd)
766 {
767         return scsi_send_eh_cmnd(scmd, NULL, 0, SENSE_TIMEOUT, ~0);
768 }
769 
770 /**
771  * scsi_eh_finish_cmd - Handle a cmd that eh is finished with.
772  * @scmd:       Original SCSI cmd that eh has finished.
773  * @done_q:     Queue for processed commands.
774  *
775  * Notes:
776  *    We don't want to use the normal command completion while we are are
777  *    still handling errors - it may cause other commands to be queued,
778  *    and that would disturb what we are doing.  Thus we really want to
779  *    keep a list of pending commands for final completion, and once we
780  *    are ready to leave error handling we handle completion for real.
781  */
782 void scsi_eh_finish_cmd(struct scsi_cmnd *scmd, struct list_head *done_q)
783 {
784         scmd->device->host->host_failed--;
785         scmd->eh_eflags = 0;
786         list_move_tail(&scmd->eh_entry, done_q);
787 }
788 EXPORT_SYMBOL(scsi_eh_finish_cmd);
789 
790 /**
791  * scsi_eh_get_sense - Get device sense data.
792  * @work_q:     Queue of commands to process.
793  * @done_q:     Queue of processed commands.
794  *
795  * Description:
796  *    See if we need to request sense information.  if so, then get it
797  *    now, so we have a better idea of what to do.  
798  *
799  * Notes:
800  *    This has the unfortunate side effect that if a shost adapter does
801  *    not automatically request sense information, we end up shutting
802  *    it down before we request it.
803  *
804  *    All drivers should request sense information internally these days,
805  *    so for now all I have to say is tough noogies if you end up in here.
806  *
807  *    XXX: Long term this code should go away, but that needs an audit of
808  *         all LLDDs first.
809  */
810 int scsi_eh_get_sense(struct list_head *work_q,
811                       struct list_head *done_q)
812 {
813         struct scsi_cmnd *scmd, *next;
814         int rtn;
815 
816         list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
817                 if ((scmd->eh_eflags & SCSI_EH_CANCEL_CMD) ||
818                     SCSI_SENSE_VALID(scmd))
819                         continue;
820 
821                 SCSI_LOG_ERROR_RECOVERY(2, scmd_printk(KERN_INFO, scmd,
822                                                   "%s: requesting sense\n",
823                                                   current->comm));
824                 rtn = scsi_request_sense(scmd);
825                 if (rtn != SUCCESS)
826                         continue;
827 
828                 SCSI_LOG_ERROR_RECOVERY(3, printk("sense requested for %p"
829                                                   " result %x\n", scmd,
830                                                   scmd->result));
831                 SCSI_LOG_ERROR_RECOVERY(3, scsi_print_sense("bh", scmd));
832 
833                 rtn = scsi_decide_disposition(scmd);
834 
835                 /*
836                  * if the result was normal, then just pass it along to the
837                  * upper level.
838                  */
839                 if (rtn == SUCCESS)
840                         /* we don't want this command reissued, just
841                          * finished with the sense data, so set
842                          * retries to the max allowed to ensure it
843                          * won't get reissued */
844                         scmd->retries = scmd->allowed;
845                 else if (rtn != NEEDS_RETRY)
846                         continue;
847 
848                 scsi_eh_finish_cmd(scmd, done_q);
849         }
850 
851         return list_empty(work_q);
852 }
853 EXPORT_SYMBOL_GPL(scsi_eh_get_sense);
854 
855 /**
856  * scsi_eh_tur - Send TUR to device.
857  * @scmd:       &scsi_cmnd to send TUR
858  *
859  * Return value:
860  *    0 - Device is ready. 1 - Device NOT ready.
861  */
862 static int scsi_eh_tur(struct scsi_cmnd *scmd)
863 {
864         static unsigned char tur_command[6] = {TEST_UNIT_READY, 0, 0, 0, 0, 0};
865         int retry_cnt = 1, rtn;
866 
867 retry_tur:
868         rtn = scsi_send_eh_cmnd(scmd, tur_command, 6, SENSE_TIMEOUT, 0);
869 
870         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: scmd %p rtn %x\n",
871                 __FUNCTION__, scmd, rtn));
872 
873         switch (rtn) {
874         case NEEDS_RETRY:
875                 if (retry_cnt--)
876                         goto retry_tur;
877                 /*FALLTHRU*/
878         case SUCCESS:
879                 return 0;
880         default:
881                 return 1;
882         }
883 }
884 
885 /**
886  * scsi_eh_abort_cmds - abort pending commands.
887  * @work_q:     &list_head for pending commands.
888  * @done_q:     &list_head for processed commands.
889  *
890  * Decription:
891  *    Try and see whether or not it makes sense to try and abort the
892  *    running command.  This only works out to be the case if we have one
893  *    command that has timed out.  If the command simply failed, it makes
894  *    no sense to try and abort the command, since as far as the shost
895  *    adapter is concerned, it isn't running.
896  */
897 static int scsi_eh_abort_cmds(struct list_head *work_q,
898                               struct list_head *done_q)
899 {
900         struct scsi_cmnd *scmd, *next;
901         int rtn;
902 
903         list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
904                 if (!(scmd->eh_eflags & SCSI_EH_CANCEL_CMD))
905                         continue;
906                 SCSI_LOG_ERROR_RECOVERY(3, printk("%s: aborting cmd:"
907                                                   "0x%p\n", current->comm,
908                                                   scmd));
909                 rtn = scsi_try_to_abort_cmd(scmd);
910                 if (rtn == SUCCESS) {
911                         scmd->eh_eflags &= ~SCSI_EH_CANCEL_CMD;
912                         if (!scsi_device_online(scmd->device) ||
913                             !scsi_eh_tur(scmd)) {
914                                 scsi_eh_finish_cmd(scmd, done_q);
915                         }
916                                 
917                 } else
918                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: aborting"
919                                                           " cmd failed:"
920                                                           "0x%p\n",
921                                                           current->comm,
922                                                           scmd));
923         }
924 
925         return list_empty(work_q);
926 }
927 
928 /**
929  * scsi_eh_try_stu - Send START_UNIT to device.
930  * @scmd:       &scsi_cmnd to send START_UNIT
931  *
932  * Return value:
933  *    0 - Device is ready. 1 - Device NOT ready.
934  */
935 static int scsi_eh_try_stu(struct scsi_cmnd *scmd)
936 {
937         static unsigned char stu_command[6] = {START_STOP, 0, 0, 0, 1, 0};
938 
939         if (scmd->device->allow_restart) {
940                 int i, rtn = NEEDS_RETRY;
941 
942                 for (i = 0; rtn == NEEDS_RETRY && i < 2; i++)
943                         rtn = scsi_send_eh_cmnd(scmd, stu_command, 6,
944                                                 scmd->device->timeout, 0);
945 
946                 if (rtn == SUCCESS)
947                         return 0;
948         }
949 
950         return 1;
951 }
952 
953  /**
954  * scsi_eh_stu - send START_UNIT if needed
955  * @shost:      &scsi host being recovered.
956  * @work_q:     &list_head for pending commands.
957  * @done_q:     &list_head for processed commands.
958  *
959  * Notes:
960  *    If commands are failing due to not ready, initializing command required,
961  *      try revalidating the device, which will end up sending a start unit. 
962  */
963 static int scsi_eh_stu(struct Scsi_Host *shost,
964                               struct list_head *work_q,
965                               struct list_head *done_q)
966 {
967         struct scsi_cmnd *scmd, *stu_scmd, *next;
968         struct scsi_device *sdev;
969 
970         shost_for_each_device(sdev, shost) {
971                 stu_scmd = NULL;
972                 list_for_each_entry(scmd, work_q, eh_entry)
973                         if (scmd->device == sdev && SCSI_SENSE_VALID(scmd) &&
974                             scsi_check_sense(scmd) == FAILED ) {
975                                 stu_scmd = scmd;
976                                 break;
977                         }
978 
979                 if (!stu_scmd)
980                         continue;
981 
982                 SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending START_UNIT to sdev:"
983                                                   " 0x%p\n", current->comm, sdev));
984 
985                 if (!scsi_eh_try_stu(stu_scmd)) {
986                         if (!scsi_device_online(sdev) ||
987                             !scsi_eh_tur(stu_scmd)) {
988                                 list_for_each_entry_safe(scmd, next,
989                                                           work_q, eh_entry) {
990                                         if (scmd->device == sdev)
991                                                 scsi_eh_finish_cmd(scmd, done_q);
992                                 }
993                         }
994                 } else {
995                         SCSI_LOG_ERROR_RECOVERY(3,
996                                                 printk("%s: START_UNIT failed to sdev:"
997                                                        " 0x%p\n", current->comm, sdev));
998                 }
999         }
1000 
1001         return list_empty(work_q);
1002 }
1003 
1004 
1005 /**
1006  * scsi_eh_bus_device_reset - send bdr if needed
1007  * @shost:      scsi host being recovered.
1008  * @work_q:     &list_head for pending commands.
1009  * @done_q:     &list_head for processed commands.
1010  *
1011  * Notes:
1012  *    Try a bus device reset.  Still, look to see whether we have multiple
1013  *    devices that are jammed or not - if we have multiple devices, it
1014  *    makes no sense to try bus_device_reset - we really would need to try
1015  *    a bus_reset instead. 
1016  */
1017 static int scsi_eh_bus_device_reset(struct Scsi_Host *shost,
1018                                     struct list_head *work_q,
1019                                     struct list_head *done_q)
1020 {
1021         struct scsi_cmnd *scmd, *bdr_scmd, *next;
1022         struct scsi_device *sdev;
1023         int rtn;
1024 
1025         shost_for_each_device(sdev, shost) {
1026                 bdr_scmd = NULL;
1027                 list_for_each_entry(scmd, work_q, eh_entry)
1028                         if (scmd->device == sdev) {
1029                                 bdr_scmd = scmd;
1030                                 break;
1031                         }
1032 
1033                 if (!bdr_scmd)
1034                         continue;
1035 
1036                 SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending BDR sdev:"
1037                                                   " 0x%p\n", current->comm,
1038                                                   sdev));
1039                 rtn = scsi_try_bus_device_reset(bdr_scmd);
1040                 if (rtn == SUCCESS) {
1041                         if (!scsi_device_online(sdev) ||
1042                             !scsi_eh_tur(bdr_scmd)) {
1043                                 list_for_each_entry_safe(scmd, next,
1044                                                          work_q, eh_entry) {
1045                                         if (scmd->device == sdev)
1046                                                 scsi_eh_finish_cmd(scmd,
1047                                                                    done_q);
1048                                 }
1049                         }
1050                 } else {
1051                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: BDR"
1052                                                           " failed sdev:"
1053                                                           "0x%p\n",
1054                                                           current->comm,
1055                                                            sdev));
1056                 }
1057         }
1058 
1059         return list_empty(work_q);
1060 }
1061 
1062 /**
1063  * scsi_eh_bus_reset - send a bus reset 
1064  * @shost:      &scsi host being recovered.
1065  * @work_q:     &list_head for pending commands.
1066  * @done_q:     &list_head for processed commands.
1067  */
1068 static int scsi_eh_bus_reset(struct Scsi_Host *shost,
1069                              struct list_head *work_q,
1070                              struct list_head *done_q)
1071 {
1072         struct scsi_cmnd *scmd, *chan_scmd, *next;
1073         unsigned int channel;
1074         int rtn;
1075 
1076         /*
1077          * we really want to loop over the various channels, and do this on
1078          * a channel by channel basis.  we should also check to see if any
1079          * of the failed commands are on soft_reset devices, and if so, skip
1080          * the reset.  
1081          */
1082 
1083         for (channel = 0; channel <= shost->max_channel; channel++) {
1084                 chan_scmd = NULL;
1085                 list_for_each_entry(scmd, work_q, eh_entry) {
1086                         if (channel == scmd_channel(scmd)) {
1087                                 chan_scmd = scmd;
1088                                 break;
1089                                 /*
1090                                  * FIXME add back in some support for
1091                                  * soft_reset devices.
1092                                  */
1093                         }
1094                 }
1095 
1096                 if (!chan_scmd)
1097                         continue;
1098                 SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending BRST chan:"
1099                                                   " %d\n", current->comm,
1100                                                   channel));
1101                 rtn = scsi_try_bus_reset(chan_scmd);
1102                 if (rtn == SUCCESS) {
1103                         list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
1104                                 if (channel == scmd_channel(scmd))
1105                                         if (!scsi_device_online(scmd->device) ||
1106                                             !scsi_eh_tur(scmd))
1107                                                 scsi_eh_finish_cmd(scmd,
1108                                                                    done_q);
1109                         }
1110                 } else {
1111                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: BRST"
1112                                                           " failed chan: %d\n",
1113                                                           current->comm,
1114                                                           channel));
1115                 }
1116         }
1117         return list_empty(work_q);
1118 }
1119 
1120 /**
1121  * scsi_eh_host_reset - send a host reset 
1122  * @work_q:     list_head for processed commands.
1123  * @done_q:     list_head for processed commands.
1124  */
1125 static int scsi_eh_host_reset(struct list_head *work_q,
1126                               struct list_head *done_q)
1127 {
1128         struct scsi_cmnd *scmd, *next;
1129         int rtn;
1130 
1131         if (!list_empty(work_q)) {
1132                 scmd = list_entry(work_q->next,
1133                                   struct scsi_cmnd, eh_entry);
1134 
1135                 SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending HRST\n"
1136                                                   , current->comm));
1137 
1138                 rtn = scsi_try_host_reset(scmd);
1139                 if (rtn == SUCCESS) {
1140                         list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
1141                                 if (!scsi_device_online(scmd->device) ||
1142                                     (!scsi_eh_try_stu(scmd) && !scsi_eh_tur(scmd)) ||
1143                                     !scsi_eh_tur(scmd))
1144                                         scsi_eh_finish_cmd(scmd, done_q);
1145                         }
1146                 } else {
1147                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: HRST"
1148                                                           " failed\n",
1149                                                           current->comm));
1150                 }
1151         }
1152         return list_empty(work_q);
1153 }
1154 
1155 /**
1156  * scsi_eh_offline_sdevs - offline scsi devices that fail to recover
1157  * @work_q:     list_head for processed commands.
1158  * @done_q:     list_head for processed commands.
1159  */
1160 static void scsi_eh_offline_sdevs(struct list_head *work_q,
1161                                   struct list_head *done_q)
1162 {
1163         struct scsi_cmnd *scmd, *next;
1164 
1165         list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
1166                 sdev_printk(KERN_INFO, scmd->device, "Device offlined - "
1167                             "not ready after error recovery\n");
1168                 scsi_device_set_state(scmd->device, SDEV_OFFLINE);
1169                 if (scmd->eh_eflags & SCSI_EH_CANCEL_CMD) {
1170                         /*
1171                          * FIXME: Handle lost cmds.
1172                          */
1173                 }
1174                 scsi_eh_finish_cmd(scmd, done_q);
1175         }
1176         return;
1177 }
1178 
1179 /**
1180  * scsi_decide_disposition - Disposition a cmd on return from LLD.
1181  * @scmd:       SCSI cmd to examine.
1182  *
1183  * Notes:
1184  *    This is *only* called when we are examining the status after sending
1185  *    out the actual data command.  any commands that are queued for error
1186  *    recovery (e.g. test_unit_ready) do *not* come through here.
1187  *
1188  *    When this routine returns failed, it means the error handler thread
1189  *    is woken.  In cases where the error code indicates an error that
1190  *    doesn't require the error handler read (i.e. we don't need to
1191  *    abort/reset), this function should return SUCCESS.
1192  */
1193 int scsi_decide_disposition(struct scsi_cmnd *scmd)
1194 {
1195         int rtn;
1196 
1197         /*
1198          * if the device is offline, then we clearly just pass the result back
1199          * up to the top level.
1200          */
1201         if (!scsi_device_online(scmd->device)) {
1202                 SCSI_LOG_ERROR_RECOVERY(5, printk("%s: device offline - report"
1203                                                   " as SUCCESS\n",
1204                                                   __FUNCTION__));
1205                 return SUCCESS;
1206         }
1207 
1208         /*
1209          * first check the host byte, to see if there is anything in there
1210          * that would indicate what we need to do.
1211          */
1212         switch (host_byte(scmd->result)) {
1213         case DID_PASSTHROUGH:
1214                 /*
1215                  * no matter what, pass this through to the upper layer.
1216                  * nuke this special code so that it looks like we are saying
1217                  * did_ok.
1218                  */
1219                 scmd->result &= 0xff00ffff;
1220                 return SUCCESS;
1221         case DID_OK:
1222                 /*
1223                  * looks good.  drop through, and check the next byte.
1224                  */
1225                 break;
1226         case DID_NO_CONNECT:
1227         case DID_BAD_TARGET:
1228         case DID_ABORT:
1229                 /*
1230                  * note - this means that we just report the status back
1231                  * to the top level driver, not that we actually think
1232                  * that it indicates SUCCESS.
1233                  */
1234                 return SUCCESS;
1235                 /*
1236                  * when the low level driver returns did_soft_error,
1237                  * it is responsible for keeping an internal retry counter 
1238                  * in order to avoid endless loops (db)
1239                  *
1240                  * actually this is a bug in this function here.  we should
1241                  * be mindful of the maximum number of retries specified
1242                  * and not get stuck in a loop.
1243                  */
1244         case DID_SOFT_ERROR:
1245                 goto maybe_retry;
1246         case DID_IMM_RETRY:
1247                 return NEEDS_RETRY;
1248 
1249         case DID_REQUEUE:
1250                 return ADD_TO_MLQUEUE;
1251 
1252         case DID_ERROR:
1253                 if (msg_byte(scmd->result) == COMMAND_COMPLETE &&
1254                     status_byte(scmd->result) == RESERVATION_CONFLICT)
1255                         /*
1256                          * execute reservation conflict processing code
1257                          * lower down
1258                          */
1259                         break;
1260                 /* fallthrough */
1261 
1262         case DID_BUS_BUSY:
1263         case DID_PARITY:
1264                 goto maybe_retry;
1265         case DID_TIME_OUT:
1266                 /*
1267                  * when we scan the bus, we get timeout messages for
1268                  * these commands if there is no device available.
1269                  * other hosts report did_no_connect for the same thing.
1270                  */
1271                 if ((scmd->cmnd[0] == TEST_UNIT_READY ||
1272                      scmd->cmnd[0] == INQUIRY)) {
1273                         return SUCCESS;
1274                 } else {
1275                         return FAILED;
1276                 }
1277         case DID_RESET:
1278                 return SUCCESS;
1279         default:
1280                 return FAILED;
1281         }
1282 
1283         /*
1284          * next, check the message byte.
1285          */
1286         if (msg_byte(scmd->result) != COMMAND_COMPLETE)
1287                 return FAILED;
1288 
1289         /*
1290          * check the status byte to see if this indicates anything special.
1291          */
1292         switch (status_byte(scmd->result)) {
1293         case QUEUE_FULL:
1294                 /*
1295                  * the case of trying to send too many commands to a
1296                  * tagged queueing device.
1297                  */
1298         case BUSY:
1299                 /*
1300                  * device can't talk to us at the moment.  Should only
1301                  * occur (SAM-3) when the task queue is empty, so will cause
1302                  * the empty queue handling to trigger a stall in the
1303                  * device.
1304                  */
1305                 return ADD_TO_MLQUEUE;
1306         case GOOD:
1307         case COMMAND_TERMINATED:
1308         case TASK_ABORTED:
1309                 return SUCCESS;
1310         case CHECK_CONDITION:
1311                 rtn = scsi_check_sense(scmd);
1312                 if (rtn == NEEDS_RETRY)
1313                         goto maybe_retry;
1314                 /* if rtn == FAILED, we have no sense information;
1315                  * returning FAILED will wake the error handler thread
1316                  * to collect the sense and redo the decide
1317                  * disposition */
1318                 return rtn;
1319         case CONDITION_GOOD:
1320         case INTERMEDIATE_GOOD:
1321         case INTERMEDIATE_C_GOOD:
1322         case ACA_ACTIVE:
1323                 /*
1324                  * who knows?  FIXME(eric)
1325                  */
1326                 return SUCCESS;
1327 
1328         case RESERVATION_CONFLICT:
1329                 sdev_printk(KERN_INFO, scmd->device,
1330                             "reservation conflict\n");
1331                 return SUCCESS; /* causes immediate i/o error */
1332         default:
1333                 return FAILED;
1334         }
1335         return FAILED;
1336 
1337       maybe_retry:
1338 
1339         /* we requeue for retry because the error was retryable, and
1340          * the request was not marked fast fail.  Note that above,
1341          * even if the request is marked fast fail, we still requeue
1342          * for queue congestion conditions (QUEUE_FULL or BUSY) */
1343         if ((++scmd->retries) <= scmd->allowed
1344             && !blk_noretry_request(scmd->request)) {
1345                 return NEEDS_RETRY;
1346         } else {
1347                 /*
1348                  * no more retries - report this one back to upper level.
1349                  */
1350                 return SUCCESS;
1351         }
1352 }
1353 
1354 /**
1355  * scsi_eh_lock_door - Prevent medium removal for the specified device
1356  * @sdev:       SCSI device to prevent medium removal
1357  *
1358  * Locking:
1359  *      We must be called from process context; scsi_allocate_request()
1360  *      may sleep.
1361  *
1362  * Notes:
1363  *      We queue up an asynchronous "ALLOW MEDIUM REMOVAL" request on the
1364  *      head of the devices request queue, and continue.
1365  *
1366  * Bugs:
1367  *      scsi_allocate_request() may sleep waiting for existing requests to
1368  *      be processed.  However, since we haven't kicked off any request
1369  *      processing for this host, this may deadlock.
1370  *
1371  *      If scsi_allocate_request() fails for what ever reason, we
1372  *      completely forget to lock the door.
1373  */
1374 static void scsi_eh_lock_door(struct scsi_device *sdev)
1375 {
1376         unsigned char cmnd[MAX_COMMAND_SIZE];
1377 
1378         cmnd[0] = ALLOW_MEDIUM_REMOVAL;
1379         cmnd[1] = 0;
1380         cmnd[2] = 0;
1381         cmnd[3] = 0;
1382         cmnd[4] = SCSI_REMOVAL_PREVENT;
1383         cmnd[5] = 0;
1384 
1385         scsi_execute_async(sdev, cmnd, 6, DMA_NONE, NULL, 0, 0, 10 * HZ,
1386                            5, NULL, NULL, GFP_KERNEL);
1387 }
1388 
1389 
1390 /**
1391  * scsi_restart_operations - restart io operations to the specified host.
1392  * @shost:      Host we are restarting.
1393  *
1394  * Notes:
1395  *    When we entered the error handler, we blocked all further i/o to
1396  *    this device.  we need to 'reverse' this process.
1397  */
1398 static void scsi_restart_operations(struct Scsi_Host *shost)
1399 {
1400         struct scsi_device *sdev;
1401         unsigned long flags;
1402 
1403         /*
1404          * If the door was locked, we need to insert a door lock request
1405          * onto the head of the SCSI request queue for the device.  There
1406          * is no point trying to lock the door of an off-line device.
1407          */
1408         shost_for_each_device(sdev, shost) {
1409                 if (scsi_device_online(sdev) && sdev->locked)
1410                         scsi_eh_lock_door(sdev);
1411         }
1412 
1413         /*
1414          * next free up anything directly waiting upon the host.  this
1415          * will be requests for character device operations, and also for
1416          * ioctls to queued block devices.
1417          */
1418         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: waking up host to restart\n",
1419                                           __FUNCTION__));
1420 
1421         spin_lock_irqsave(shost->host_lock, flags);
1422         if (scsi_host_set_state(shost, SHOST_RUNNING))
1423                 if (scsi_host_set_state(shost, SHOST_CANCEL))
1424                         BUG_ON(scsi_host_set_state(shost, SHOST_DEL));
1425         spin_unlock_irqrestore(shost->host_lock, flags);
1426 
1427         wake_up(&shost->host_wait);
1428 
1429         /*
1430          * finally we need to re-initiate requests that may be pending.  we will
1431          * have had everything blocked while error handling is taking place, and
1432          * now that error recovery is done, we will need to ensure that these
1433          * requests are started.
1434          */
1435         scsi_run_host_queues(shost);
1436 }
1437 
1438 /**
1439  * scsi_eh_ready_devs - check device ready state and recover if not.
1440  * @shost:      host to be recovered.
1441  * @work_q:     &list_head for pending commands.
1442  * @done_q:     &list_head for processed commands.
1443  */
1444 void scsi_eh_ready_devs(struct Scsi_Host *shost,
1445                         struct list_head *work_q,
1446                         struct list_head *done_q)
1447 {
1448         if (!scsi_eh_stu(shost, work_q, done_q))
1449                 if (!scsi_eh_bus_device_reset(shost, work_q, done_q))
1450                         if (!scsi_eh_bus_reset(shost, work_q, done_q))
1451                                 if (!scsi_eh_host_reset(work_q, done_q))
1452                                         scsi_eh_offline_sdevs(work_q, done_q);
1453 }
1454 EXPORT_SYMBOL_GPL(scsi_eh_ready_devs);
1455 
1456 /**
1457  * scsi_eh_flush_done_q - finish processed commands or retry them.
1458  * @done_q:     list_head of processed commands.
1459  */
1460 void scsi_eh_flush_done_q(struct list_head *done_q)
1461 {
1462         struct scsi_cmnd *scmd, *next;
1463 
1464         list_for_each_entry_safe(scmd, next, done_q, eh_entry) {
1465                 list_del_init(&scmd->eh_entry);
1466                 if (scsi_device_online(scmd->device) &&
1467                     !blk_noretry_request(scmd->request) &&
1468                     (++scmd->retries <= scmd->allowed)) {
1469                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: flush"
1470                                                           " retry cmd: %p\n",
1471                                                           current->comm,
1472                                                           scmd));
1473                                 scsi_queue_insert(scmd, SCSI_MLQUEUE_EH_RETRY);
1474                 } else {
1475                         /*
1476                          * If just we got sense for the device (called
1477                          * scsi_eh_get_sense), scmd->result is already
1478                          * set, do not set DRIVER_TIMEOUT.
1479                          */
1480                         if (!scmd->result)
1481                                 scmd->result |= (DRIVER_TIMEOUT << 24);
1482                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: flush finish"
1483                                                         " cmd: %p\n",
1484                                                         current->comm, scmd));
1485                         scsi_finish_command(scmd);
1486                 }
1487         }
1488 }
1489 EXPORT_SYMBOL(scsi_eh_flush_done_q);
1490 
1491 /**
1492  * scsi_unjam_host - Attempt to fix a host which has a cmd that failed.
1493  * @shost:      Host to unjam.
1494  *
1495  * Notes:
1496  *    When we come in here, we *know* that all commands on the bus have
1497  *    either completed, failed or timed out.  we also know that no further
1498  *    commands are being sent to the host, so things are relatively quiet
1499  *    and we have freedom to fiddle with things as we wish.
1500  *
1501  *    This is only the *default* implementation.  it is possible for
1502  *    individual drivers to supply their own version of this function, and
1503  *    if the maintainer wishes to do this, it is strongly suggested that
1504  *    this function be taken as a template and modified.  this function
1505  *    was designed to correctly handle problems for about 95% of the
1506  *    different cases out there, and it should always provide at least a
1507  *    reasonable amount of error recovery.
1508  *
1509  *    Any command marked 'failed' or 'timeout' must eventually have
1510  *    scsi_finish_cmd() called for it.  we do all of the retry stuff
1511  *    here, so when we restart the host after we return it should have an
1512  *    empty queue.
1513  */
1514 static void scsi_unjam_host(struct Scsi_Host *shost)
1515 {
1516         unsigned long flags;
1517         LIST_HEAD(eh_work_q);
1518         LIST_HEAD(eh_done_q);
1519 
1520         spin_lock_irqsave(shost->host_lock, flags);
1521         list_splice_init(&shost->eh_cmd_q, &eh_work_q);
1522         spin_unlock_irqrestore(shost->host_lock, flags);
1523 
1524         SCSI_LOG_ERROR_RECOVERY(1, scsi_eh_prt_fail_stats(shost, &eh_work_q));
1525 
1526         if (!scsi_eh_get_sense(&eh_work_q, &eh_done_q))
1527                 if (!scsi_eh_abort_cmds(&eh_work_q, &eh_done_q))
1528                         scsi_eh_ready_devs(shost, &eh_work_q, &eh_done_q);
1529 
1530         scsi_eh_flush_done_q(&eh_done_q);
1531 }
1532 
1533 /**
1534  * scsi_error_handler - SCSI error handler thread
1535  * @data:       Host for which we are running.
1536  *
1537  * Notes:
1538  *    This is the main error handling loop.  This is run as a kernel thread
1539  *    for every SCSI host and handles all error handling activity.
1540  */
1541 int scsi_error_handler(void *data)
1542 {
1543         struct Scsi_Host *shost = data;
1544 
1545         /*
1546          * We use TASK_INTERRUPTIBLE so that the thread is not
1547          * counted against the load average as a running process.
1548          * We never actually get interrupted because kthread_run
1549          * disables singal delivery for the created thread.
1550          */
1551         set_current_state(TASK_INTERRUPTIBLE);
1552         while (!kthread_should_stop()) {
1553                 if ((shost->host_failed == 0 && shost->host_eh_scheduled == 0) ||
1554                     shost->host_failed != shost->host_busy) {
1555                         SCSI_LOG_ERROR_RECOVERY(1,
1556                                 printk("Error handler scsi_eh_%d sleeping\n",
1557                                         shost->host_no));
1558                         schedule();
1559                         set_current_state(TASK_INTERRUPTIBLE);
1560                         continue;
1561                 }
1562 
1563                 __set_current_state(TASK_RUNNING);
1564                 SCSI_LOG_ERROR_RECOVERY(1,
1565                         printk("Error handler scsi_eh_%d waking up\n",
1566                                 shost->host_no));
1567 
1568                 /*
1569                  * We have a host that is failing for some reason.  Figure out
1570                  * what we need to do to get it up and online again (if we can).
1571                  * If we fail, we end up taking the thing offline.
1572                  */
1573                 if (shost->transportt->eh_strategy_handler)
1574                         shost->transportt->eh_strategy_handler(shost);
1575                 else
1576                         scsi_unjam_host(shost);
1577 
1578                 /*
1579                  * Note - if the above fails completely, the action is to take
1580                  * individual devices offline and flush the queue of any
1581                  * outstanding requests that may have been pending.  When we
1582                  * restart, we restart any I/O to any other devices on the bus
1583                  * which are still online.
1584                  */
1585                 scsi_restart_operations(shost);
1586                 set_current_state(TASK_INTERRUPTIBLE);
1587         }
1588         __set_current_state(TASK_RUNNING);
1589 
1590         SCSI_LOG_ERROR_RECOVERY(1,
1591                 printk("Error handler scsi_eh_%d exiting\n", shost->host_no));
1592         shost->ehandler = NULL;
1593         return 0;
1594 }
1595 
1596 /*
1597  * Function:    scsi_report_bus_reset()
1598  *
1599  * Purpose:     Utility function used by low-level drivers to report that
1600  *              they have observed a bus reset on the bus being handled.
1601  *
1602  * Arguments:   shost       - Host in question
1603  *              channel     - channel on which reset was observed.
1604  *
1605  * Returns:     Nothing
1606  *
1607  * Lock status: Host lock must be held.
1608  *
1609  * Notes:       This only needs to be called if the reset is one which
1610  *              originates from an unknown location.  Resets originated
1611  *              by the mid-level itself don't need to call this, but there
1612  *              should be no harm.
1613  *
1614  *              The main purpose of this is to make sure that a CHECK_CONDITION
1615  *              is properly treated.
1616  */
1617 void scsi_report_bus_reset(struct Scsi_Host *shost, int channel)
1618 {
1619         struct scsi_device *sdev;
1620 
1621         __shost_for_each_device(sdev, shost) {
1622                 if (channel == sdev_channel(sdev)) {
1623                         sdev->was_reset = 1;
1624                         sdev->expecting_cc_ua = 1;
1625                 }
1626         }
1627 }
1628 EXPORT_SYMBOL(scsi_report_bus_reset);
1629 
1630 /*
1631  * Function:    scsi_report_device_reset()
1632  *
1633  * Purpose:     Utility function used by low-level drivers to report that
1634  *              they have observed a device reset on the device being handled.
1635  *
1636  * Arguments:   shost       - Host in question
1637  *              channel     - channel on which reset was observed
1638  *              target      - target on which reset was observed
1639  *
1640  * Returns:     Nothing
1641  *
1642  * Lock status: Host lock must be held
1643  *
1644  * Notes:       This only needs to be called if the reset is one which
1645  *              originates from an unknown location.  Resets originated
1646  *              by the mid-level itself don't need to call this, but there
1647  *              should be no harm.
1648  *
1649  *              The main purpose of this is to make sure that a CHECK_CONDITION
1650  *              is properly treated.
1651  */
1652 void scsi_report_device_reset(struct Scsi_Host *shost, int channel, int target)
1653 {
1654         struct scsi_device *sdev;
1655 
1656         __shost_for_each_device(sdev, shost) {
1657                 if (channel == sdev_channel(sdev) &&
1658                     target == sdev_id(sdev)) {
1659                         sdev->was_reset = 1;
1660                         sdev->expecting_cc_ua = 1;
1661                 }
1662         }
1663 }
1664 EXPORT_SYMBOL(scsi_report_device_reset);
1665 
1666 static void
1667 scsi_reset_provider_done_command(struct scsi_cmnd *scmd)
1668 {
1669 }
1670 
1671 /*
1672  * Function:    scsi_reset_provider
1673  *
1674  * Purpose:     Send requested reset to a bus or device at any phase.
1675  *
1676  * Arguments:   device  - device to send reset to
1677  *              flag - reset type (see scsi.h)
1678  *
1679  * Returns:     SUCCESS/FAILURE.
1680  *
1681  * Notes:       This is used by the SCSI Generic driver to provide
1682  *              Bus/Device reset capability.
1683  */
1684 int
1685 scsi_reset_provider(struct scsi_device *dev, int flag)
1686 {
1687         struct scsi_cmnd *scmd = scsi_get_command(dev, GFP_KERNEL);
1688         struct Scsi_Host *shost = dev->host;
1689         struct request req;
1690         unsigned long flags;
1691         int rtn;
1692 
1693         scmd->request = &req;
1694         memset(&scmd->eh_timeout, 0, sizeof(scmd->eh_timeout));
1695 
1696         memset(&scmd->cmnd, '\0', sizeof(scmd->cmnd));
1697     
1698         scmd->scsi_done         = scsi_reset_provider_done_command;
1699         memset(&scmd->sdb, 0, sizeof(scmd->sdb));
1700 
1701         scmd->cmd_len                   = 0;
1702 
1703         scmd->sc_data_direction         = DMA_BIDIRECTIONAL;
1704 
1705         init_timer(&scmd->eh_timeout);
1706 
1707         spin_lock_irqsave(shost->host_lock, flags);
1708         shost->tmf_in_progress = 1;
1709         spin_unlock_irqrestore(shost->host_lock, flags);
1710 
1711         switch (flag) {
1712         case SCSI_TRY_RESET_DEVICE:
1713                 rtn = scsi_try_bus_device_reset(scmd);
1714                 if (rtn == SUCCESS)
1715                         break;
1716                 /* FALLTHROUGH */
1717         case SCSI_TRY_RESET_BUS:
1718                 rtn = scsi_try_bus_reset(scmd);
1719                 if (rtn == SUCCESS)
1720                         break;
1721                 /* FALLTHROUGH */
1722         case SCSI_TRY_RESET_HOST:
1723                 rtn = scsi_try_host_reset(scmd);
1724                 break;
1725         default:
1726                 rtn = FAILED;
1727         }
1728 
1729         spin_lock_irqsave(shost->host_lock, flags);
1730         shost->tmf_in_progress = 0;
1731         spin_unlock_irqrestore(shost->host_lock, flags);
1732 
1733         /*
1734          * be sure to wake up anyone who was sleeping or had their queue
1735          * suspended while we performed the TMF.
1736          */
1737         SCSI_LOG_ERROR_RECOVERY(3,
1738                 printk("%s: waking up host to restart after TMF\n",
1739                 __FUNCTION__));
1740 
1741         wake_up(&shost->host_wait);
1742 
1743         scsi_run_host_queues(shost);
1744 
1745         scsi_next_command(scmd);
1746         return rtn;
1747 }
1748 EXPORT_SYMBOL(scsi_reset_provider);
1749 
1750 /**
1751  * scsi_normalize_sense - normalize main elements from either fixed or
1752  *                      descriptor sense data format into a common format.
1753  *
1754  * @sense_buffer:       byte array containing sense data returned by device
1755  * @sb_len:             number of valid bytes in sense_buffer
1756  * @sshdr:              pointer to instance of structure that common
1757  *                      elements are written to.
1758  *
1759  * Notes:
1760  *      The "main elements" from sense data are: response_code, sense_key,
1761  *      asc, ascq and additional_length (only for descriptor format).
1762  *
1763  *      Typically this function can be called after a device has
1764  *      responded to a SCSI command with the CHECK_CONDITION status.
1765  *
1766  * Return value:
1767  *      1 if valid sense data information found, else 0;
1768  */
1769 int scsi_normalize_sense(const u8 *sense_buffer, int sb_len,
1770                          struct scsi_sense_hdr *sshdr)
1771 {
1772         if (!sense_buffer || !sb_len)
1773                 return 0;
1774 
1775         memset(sshdr, 0, sizeof(struct scsi_sense_hdr));
1776 
1777         sshdr->response_code = (sense_buffer[0] & 0x7f);
1778 
1779         if (!scsi_sense_valid(sshdr))
1780                 return 0;
1781 
1782         if (sshdr->response_code >= 0x72) {
1783                 /*
1784                  * descriptor format
1785                  */
1786                 if (sb_len > 1)
1787                         sshdr->sense_key = (sense_buffer[1] & 0xf);
1788                 if (sb_len > 2)
1789                         sshdr->asc = sense_buffer[2];
1790                 if (sb_len > 3)
1791                         sshdr->ascq = sense_buffer[3];
1792                 if (sb_len > 7)
1793                         sshdr->additional_length = sense_buffer[7];
1794         } else {
1795                 /* 
1796                  * fixed format
1797                  */
1798                 if (sb_len > 2)
1799                         sshdr->sense_key = (sense_buffer[2] & 0xf);
1800                 if (sb_len > 7) {
1801                         sb_len = (sb_len < (sense_buffer[7] + 8)) ?
1802                                          sb_len : (sense_buffer[7] + 8);
1803                         if (sb_len > 12)
1804                                 sshdr->asc = sense_buffer[12];
1805                         if (sb_len > 13)
1806                                 sshdr->ascq = sense_buffer[13];
1807                 }
1808         }
1809 
1810         return 1;
1811 }
1812 EXPORT_SYMBOL(scsi_normalize_sense);
1813 
1814 int scsi_command_normalize_sense(struct scsi_cmnd *cmd,
1815                                  struct scsi_sense_hdr *sshdr)
1816 {
1817         return scsi_normalize_sense(cmd->sense_buffer,
1818                         SCSI_SENSE_BUFFERSIZE, sshdr);
1819 }
1820 EXPORT_SYMBOL(scsi_command_normalize_sense);
1821 
1822 /**
1823  * scsi_sense_desc_find - search for a given descriptor type in descriptor sense data format.
1824  * @sense_buffer:       byte array of descriptor format sense data
1825  * @sb_len:             number of valid bytes in sense_buffer
1826  * @desc_type:          value of descriptor type to find
1827  *                      (e.g. 0 -> information)
1828  *
1829  * Notes:
1830  *      only valid when sense data is in descriptor format
1831  *
1832  * Return value:
1833  *      pointer to start of (first) descriptor if found else NULL
1834  */
1835 const u8 * scsi_sense_desc_find(const u8 * sense_buffer, int sb_len,
1836                                 int desc_type)
1837 {
1838         int add_sen_len, add_len, desc_len, k;
1839         const u8 * descp;
1840 
1841         if ((sb_len < 8) || (0 == (add_sen_len = sense_buffer[7])))
1842                 return NULL;
1843         if ((sense_buffer[0] < 0x72) || (sense_buffer[0] > 0x73))
1844                 return NULL;
1845         add_sen_len = (add_sen_len < (sb_len - 8)) ?
1846                         add_sen_len : (sb_len - 8);
1847         descp = &sense_buffer[8];
1848         for (desc_len = 0, k = 0; k < add_sen_len; k += desc_len) {
1849                 descp += desc_len;
1850                 add_len = (k < (add_sen_len - 1)) ? descp[1]: -1;
1851                 desc_len = add_len + 2;
1852                 if (descp[0] == desc_type)
1853                         return descp;
1854                 if (add_len < 0) // short descriptor ??
1855                         break;
1856         }
1857         return NULL;
1858 }
1859 EXPORT_SYMBOL(scsi_sense_desc_find);
1860 
1861 /**
1862  * scsi_get_sense_info_fld - get information field from sense data (either fixed or descriptor format)
1863  * @sense_buffer:       byte array of sense data
1864  * @sb_len:             number of valid bytes in sense_buffer
1865  * @info_out:           pointer to 64 integer where 8 or 4 byte information
1866  *                      field will be placed if found.
1867  *
1868  * Return value:
1869  *      1 if information field found, 0 if not found.
1870  */
1871 int scsi_get_sense_info_fld(const u8 * sense_buffer, int sb_len,
1872                             u64 * info_out)
1873 {
1874         int j;
1875         const u8 * ucp;
1876         u64 ull;
1877 
1878         if (sb_len < 7)
1879                 return 0;
1880         switch (sense_buffer[0] & 0x7f) {
1881         case 0x70:
1882         case 0x71:
1883                 if (sense_buffer[0] & 0x80) {
1884                         *info_out = (sense_buffer[3] << 24) +
1885                                     (sense_buffer[4] << 16) +
1886                                     (sense_buffer[5] << 8) + sense_buffer[6];
1887                         return 1;
1888                 } else
1889                         return 0;
1890         case 0x72:
1891         case 0x73:
1892                 ucp = scsi_sense_desc_find(sense_buffer, sb_len,
1893                                            0 /* info desc */);
1894                 if (ucp && (0xa == ucp[1])) {
1895                         ull = 0;
1896                         for (j = 0; j < 8; ++j) {
1897                                 if (j > 0)
1898                                         ull <<= 8;
1899                                 ull |= ucp[4 + j];
1900                         }
1901                         *info_out = ull;
1902                         return 1;
1903                 } else
1904                         return 0;
1905         default:
1906                 return 0;
1907         }
1908 }
1909 EXPORT_SYMBOL(scsi_get_sense_info_fld);
1910 
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