Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 2050 insertions, 0 deletions

diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
new file mode 100644
index 0000000..9bc597b
--- /dev/null
+++ b/drivers/scsi/scsi_error.c
@@ -0,0 +1,2050 @@
+/*
+ *  scsi_error.c Copyright (C) 1997 Eric Youngdale
+ *
+ *  SCSI error/timeout handling
+ *      Initial versions: Eric Youngdale.  Based upon conversations with
+ *                        Leonard Zubkoff and David Miller at Linux Expo, 
+ *                        ideas originating from all over the place.
+ *
+ *	Restructured scsi_unjam_host and associated functions.
+ *	September 04, 2002 Mike Anderson (andmike@us.ibm.com)
+ *
+ *	Forward port of Russell King's (rmk@arm.linux.org.uk) changes and
+ *	minor  cleanups.
+ *	September 30, 2002 Mike Anderson (andmike@us.ibm.com)
+ */
+
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/timer.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/kernel.h>
+#include <linux/interrupt.h>
+#include <linux/blkdev.h>
+#include <linux/delay.h>
+
+#include <scsi/scsi.h>
+#include <scsi/scsi_dbg.h>
+#include <scsi/scsi_device.h>
+#include <scsi/scsi_eh.h>
+#include <scsi/scsi_host.h>
+#include <scsi/scsi_ioctl.h>
+#include <scsi/scsi_request.h>
+
+#include "scsi_priv.h"
+#include "scsi_logging.h"
+
+#define SENSE_TIMEOUT		(10*HZ)
+#define START_UNIT_TIMEOUT	(30*HZ)
+
+/*
+ * These should *probably* be handled by the host itself.
+ * Since it is allowed to sleep, it probably should.
+ */
+#define BUS_RESET_SETTLE_TIME   (10)
+#define HOST_RESET_SETTLE_TIME  (10)
+
+/* called with shost->host_lock held */
+void scsi_eh_wakeup(struct Scsi_Host *shost)
+{
+	if (shost->host_busy == shost->host_failed) {
+		up(shost->eh_wait);
+		SCSI_LOG_ERROR_RECOVERY(5,
+				printk("Waking error handler thread\n"));
+	}
+}
+
+/**
+ * scsi_eh_scmd_add - add scsi cmd to error handling.
+ * @scmd:	scmd to run eh on.
+ * @eh_flag:	optional SCSI_EH flag.
+ *
+ * Return value:
+ *	0 on failure.
+ **/
+int scsi_eh_scmd_add(struct scsi_cmnd *scmd, int eh_flag)
+{
+	struct Scsi_Host *shost = scmd->device->host;
+	unsigned long flags;
+
+	if (shost->eh_wait == NULL)
+		return 0;
+
+	spin_lock_irqsave(shost->host_lock, flags);
+
+	scsi_eh_eflags_set(scmd, eh_flag);
+	/*
+	 * FIXME: Can we stop setting owner and state.
+	 */
+	scmd->owner = SCSI_OWNER_ERROR_HANDLER;
+	scmd->state = SCSI_STATE_FAILED;
+	/*
+	 * Set the serial_number_at_timeout to the current
+	 * serial_number
+	 */
+	scmd->serial_number_at_timeout = scmd->serial_number;
+	list_add_tail(&scmd->eh_entry, &shost->eh_cmd_q);
+	set_bit(SHOST_RECOVERY, &shost->shost_state);
+	shost->host_failed++;
+	scsi_eh_wakeup(shost);
+	spin_unlock_irqrestore(shost->host_lock, flags);
+	return 1;
+}
+
+/**
+ * scsi_add_timer - Start timeout timer for a single scsi command.
+ * @scmd:	scsi command that is about to start running.
+ * @timeout:	amount of time to allow this command to run.
+ * @complete:	timeout function to call if timer isn't canceled.
+ *
+ * Notes:
+ *    This should be turned into an inline function.  Each scsi command
+ *    has its own timer, and as it is added to the queue, we set up the
+ *    timer.  When the command completes, we cancel the timer.
+ **/
+void scsi_add_timer(struct scsi_cmnd *scmd, int timeout,
+		    void (*complete)(struct scsi_cmnd *))
+{
+
+	/*
+	 * If the clock was already running for this command, then
+	 * first delete the timer.  The timer handling code gets rather
+	 * confused if we don't do this.
+	 */
+	if (scmd->eh_timeout.function)
+		del_timer(&scmd->eh_timeout);
+
+	scmd->eh_timeout.data = (unsigned long)scmd;
+	scmd->eh_timeout.expires = jiffies + timeout;
+	scmd->eh_timeout.function = (void (*)(unsigned long)) complete;
+
+	SCSI_LOG_ERROR_RECOVERY(5, printk("%s: scmd: %p, time:"
+					  " %d, (%p)\n", __FUNCTION__,
+					  scmd, timeout, complete));
+
+	add_timer(&scmd->eh_timeout);
+}
+EXPORT_SYMBOL(scsi_add_timer);
+
+/**
+ * scsi_delete_timer - Delete/cancel timer for a given function.
+ * @scmd:	Cmd that we are canceling timer for
+ *
+ * Notes:
+ *     This should be turned into an inline function.
+ *
+ * Return value:
+ *     1 if we were able to detach the timer.  0 if we blew it, and the
+ *     timer function has already started to run.
+ **/
+int scsi_delete_timer(struct scsi_cmnd *scmd)
+{
+	int rtn;
+
+	rtn = del_timer(&scmd->eh_timeout);
+
+	SCSI_LOG_ERROR_RECOVERY(5, printk("%s: scmd: %p,"
+					 " rtn: %d\n", __FUNCTION__,
+					 scmd, rtn));
+
+	scmd->eh_timeout.data = (unsigned long)NULL;
+	scmd->eh_timeout.function = NULL;
+
+	return rtn;
+}
+EXPORT_SYMBOL(scsi_delete_timer);
+
+/**
+ * scsi_times_out - Timeout function for normal scsi commands.
+ * @scmd:	Cmd that is timing out.
+ *
+ * Notes:
+ *     We do not need to lock this.  There is the potential for a race
+ *     only in that the normal completion handling might run, but if the
+ *     normal completion function determines that the timer has already
+ *     fired, then it mustn't do anything.
+ **/
+void scsi_times_out(struct scsi_cmnd *scmd)
+{
+	scsi_log_completion(scmd, TIMEOUT_ERROR);
+
+	if (scmd->device->host->hostt->eh_timed_out)
+		switch (scmd->device->host->hostt->eh_timed_out(scmd)) {
+		case EH_HANDLED:
+			__scsi_done(scmd);
+			return;
+		case EH_RESET_TIMER:
+			/* This allows a single retry even of a command
+			 * with allowed == 0 */
+			if (scmd->retries++ > scmd->allowed)
+				break;
+			scsi_add_timer(scmd, scmd->timeout_per_command,
+				       scsi_times_out);
+			return;
+		case EH_NOT_HANDLED:
+			break;
+		}
+
+	if (unlikely(!scsi_eh_scmd_add(scmd, SCSI_EH_CANCEL_CMD))) {
+		panic("Error handler thread not present at %p %p %s %d",
+		      scmd, scmd->device->host, __FILE__, __LINE__);
+	}
+}
+
+/**
+ * scsi_block_when_processing_errors - Prevent cmds from being queued.
+ * @sdev:	Device on which we are performing recovery.
+ *
+ * Description:
+ *     We block until the host is out of error recovery, and then check to
+ *     see whether the host or the device is offline.
+ *
+ * Return value:
+ *     0 when dev was taken offline by error recovery. 1 OK to proceed.
+ **/
+int scsi_block_when_processing_errors(struct scsi_device *sdev)
+{
+	int online;
+
+	wait_event(sdev->host->host_wait, (!test_bit(SHOST_RECOVERY, &sdev->host->shost_state)));
+
+	online = scsi_device_online(sdev);
+
+	SCSI_LOG_ERROR_RECOVERY(5, printk("%s: rtn: %d\n", __FUNCTION__,
+					  online));
+
+	return online;
+}
+EXPORT_SYMBOL(scsi_block_when_processing_errors);
+
+#ifdef CONFIG_SCSI_LOGGING
+/**
+ * scsi_eh_prt_fail_stats - Log info on failures.
+ * @shost:	scsi host being recovered.
+ * @work_q:	Queue of scsi cmds to process.
+ **/
+static inline void scsi_eh_prt_fail_stats(struct Scsi_Host *shost,
+					  struct list_head *work_q)
+{
+	struct scsi_cmnd *scmd;
+	struct scsi_device *sdev;
+	int total_failures = 0;
+	int cmd_failed = 0;
+	int cmd_cancel = 0;
+	int devices_failed = 0;
+
+	shost_for_each_device(sdev, shost) {
+		list_for_each_entry(scmd, work_q, eh_entry) {
+			if (scmd->device == sdev) {
+				++total_failures;
+				if (scsi_eh_eflags_chk(scmd,
+						       SCSI_EH_CANCEL_CMD))
+					++cmd_cancel;
+				else 
+					++cmd_failed;
+			}
+		}
+
+		if (cmd_cancel || cmd_failed) {
+			SCSI_LOG_ERROR_RECOVERY(3,
+				printk("%s: %d:%d:%d:%d cmds failed: %d,"
+				       " cancel: %d\n",
+				       __FUNCTION__, shost->host_no,
+				       sdev->channel, sdev->id, sdev->lun,
+				       cmd_failed, cmd_cancel));
+			cmd_cancel = 0;
+			cmd_failed = 0;
+			++devices_failed;
+		}
+	}
+
+	SCSI_LOG_ERROR_RECOVERY(2, printk("Total of %d commands on %d"
+					  " devices require eh work\n",
+				  total_failures, devices_failed));
+}
+#endif
+
+/**
+ * scsi_check_sense - Examine scsi cmd sense
+ * @scmd:	Cmd to have sense checked.
+ *
+ * Return value:
+ * 	SUCCESS or FAILED or NEEDS_RETRY
+ *
+ * Notes:
+ *	When a deferred error is detected the current command has
+ *	not been executed and needs retrying.
+ **/
+static int scsi_check_sense(struct scsi_cmnd *scmd)
+{
+	struct scsi_sense_hdr sshdr;
+
+	if (! scsi_command_normalize_sense(scmd, &sshdr))
+		return FAILED;	/* no valid sense data */
+
+	if (scsi_sense_is_deferred(&sshdr))
+		return NEEDS_RETRY;
+
+	/*
+	 * Previous logic looked for FILEMARK, EOM or ILI which are
+	 * mainly associated with tapes and returned SUCCESS.
+	 */
+	if (sshdr.response_code == 0x70) {
+		/* fixed format */
+		if (scmd->sense_buffer[2] & 0xe0)
+			return SUCCESS;
+	} else {
+		/*
+		 * descriptor format: look for "stream commands sense data
+		 * descriptor" (see SSC-3). Assume single sense data
+		 * descriptor. Ignore ILI from SBC-2 READ LONG and WRITE LONG.
+		 */
+		if ((sshdr.additional_length > 3) &&
+		    (scmd->sense_buffer[8] == 0x4) &&
+		    (scmd->sense_buffer[11] & 0xe0))
+			return SUCCESS;
+	}
+
+	switch (sshdr.sense_key) {
+	case NO_SENSE:
+		return SUCCESS;
+	case RECOVERED_ERROR:
+		return /* soft_error */ SUCCESS;
+
+	case ABORTED_COMMAND:
+		return NEEDS_RETRY;
+	case NOT_READY:
+	case UNIT_ATTENTION:
+		/*
+		 * if we are expecting a cc/ua because of a bus reset that we
+		 * performed, treat this just as a retry.  otherwise this is
+		 * information that we should pass up to the upper-level driver
+		 * so that we can deal with it there.
+		 */
+		if (scmd->device->expecting_cc_ua) {
+			scmd->device->expecting_cc_ua = 0;
+			return NEEDS_RETRY;
+		}
+		/*
+		 * if the device is in the process of becoming ready, we 
+		 * should retry.
+		 */
+		if ((sshdr.asc == 0x04) && (sshdr.ascq == 0x01))
+			return NEEDS_RETRY;
+		/*
+		 * if the device is not started, we need to wake
+		 * the error handler to start the motor
+		 */
+		if (scmd->device->allow_restart &&
+		    (sshdr.asc == 0x04) && (sshdr.ascq == 0x02))
+			return FAILED;
+		return SUCCESS;
+
+		/* these three are not supported */
+	case COPY_ABORTED:
+	case VOLUME_OVERFLOW:
+	case MISCOMPARE:
+		return SUCCESS;
+
+	case MEDIUM_ERROR:
+		return NEEDS_RETRY;
+
+	case HARDWARE_ERROR:
+		if (scmd->device->retry_hwerror)
+			return NEEDS_RETRY;
+		else
+			return SUCCESS;
+
+	case ILLEGAL_REQUEST:
+	case BLANK_CHECK:
+	case DATA_PROTECT:
+	default:
+		return SUCCESS;
+	}
+}
+
+/**
+ * scsi_eh_completed_normally - Disposition a eh cmd on return from LLD.
+ * @scmd:	SCSI cmd to examine.
+ *
+ * Notes:
+ *    This is *only* called when we are examining the status of commands
+ *    queued during error recovery.  the main difference here is that we
+ *    don't allow for the possibility of retries here, and we are a lot
+ *    more restrictive about what we consider acceptable.
+ **/
+static int scsi_eh_completed_normally(struct scsi_cmnd *scmd)
+{
+	/*
+	 * first check the host byte, to see if there is anything in there
+	 * that would indicate what we need to do.
+	 */
+	if (host_byte(scmd->result) == DID_RESET) {
+		/*
+		 * rats.  we are already in the error handler, so we now
+		 * get to try and figure out what to do next.  if the sense
+		 * is valid, we have a pretty good idea of what to do.
+		 * if not, we mark it as FAILED.
+		 */
+		return scsi_check_sense(scmd);
+	}
+	if (host_byte(scmd->result) != DID_OK)
+		return FAILED;
+
+	/*
+	 * next, check the message byte.
+	 */
+	if (msg_byte(scmd->result) != COMMAND_COMPLETE)
+		return FAILED;
+
+	/*
+	 * now, check the status byte to see if this indicates
+	 * anything special.
+	 */
+	switch (status_byte(scmd->result)) {
+	case GOOD:
+	case COMMAND_TERMINATED:
+		return SUCCESS;
+	case CHECK_CONDITION:
+		return scsi_check_sense(scmd);
+	case CONDITION_GOOD:
+	case INTERMEDIATE_GOOD:
+	case INTERMEDIATE_C_GOOD:
+		/*
+		 * who knows?  FIXME(eric)
+		 */
+		return SUCCESS;
+	case BUSY:
+	case QUEUE_FULL:
+	case RESERVATION_CONFLICT:
+	default:
+		return FAILED;
+	}
+	return FAILED;
+}
+
+/**
+ * scsi_eh_times_out - timeout function for error handling.
+ * @scmd:	Cmd that is timing out.
+ *
+ * Notes:
+ *    During error handling, the kernel thread will be sleeping waiting
+ *    for some action to complete on the device.  our only job is to
+ *    record that it timed out, and to wake up the thread.
+ **/
+static void scsi_eh_times_out(struct scsi_cmnd *scmd)
+{
+	scsi_eh_eflags_set(scmd, SCSI_EH_REC_TIMEOUT);
+	SCSI_LOG_ERROR_RECOVERY(3, printk("%s: scmd:%p\n", __FUNCTION__,
+					  scmd));
+
+	if (scmd->device->host->eh_action)
+		up(scmd->device->host->eh_action);
+}
+
+/**
+ * scsi_eh_done - Completion function for error handling.
+ * @scmd:	Cmd that is done.
+ **/
+static void scsi_eh_done(struct scsi_cmnd *scmd)
+{
+	/*
+	 * if the timeout handler is already running, then just set the
+	 * flag which says we finished late, and return.  we have no
+	 * way of stopping the timeout handler from running, so we must
+	 * always defer to it.
+	 */
+	if (del_timer(&scmd->eh_timeout)) {
+		scmd->request->rq_status = RQ_SCSI_DONE;
+		scmd->owner = SCSI_OWNER_ERROR_HANDLER;
+
+		SCSI_LOG_ERROR_RECOVERY(3, printk("%s scmd: %p result: %x\n",
+					   __FUNCTION__, scmd, scmd->result));
+
+		if (scmd->device->host->eh_action)
+			up(scmd->device->host->eh_action);
+	}
+}
+
+/**
+ * scsi_send_eh_cmnd  - send a cmd to a device as part of error recovery.
+ * @scmd:	SCSI Cmd to send.
+ * @timeout:	Timeout for cmd.
+ *
+ * Notes:
+ *    The initialization of the structures is quite a bit different in
+ *    this case, and furthermore, there is a different completion handler
+ *    vs scsi_dispatch_cmd.
+ * Return value:
+ *    SUCCESS or FAILED or NEEDS_RETRY
+ **/
+static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, int timeout)
+{
+	struct Scsi_Host *host = scmd->device->host;
+	DECLARE_MUTEX_LOCKED(sem);
+	unsigned long flags;
+	int rtn = SUCCESS;
+
+	/*
+	 * we will use a queued command if possible, otherwise we will
+	 * emulate the queuing and calling of completion function ourselves.
+	 */
+	scmd->owner = SCSI_OWNER_LOWLEVEL;
+
+	if (scmd->device->scsi_level <= SCSI_2)
+		scmd->cmnd[1] = (scmd->cmnd[1] & 0x1f) |
+			(scmd->device->lun << 5 & 0xe0);
+
+	scsi_add_timer(scmd, timeout, scsi_eh_times_out);
+
+	/*
+	 * set up the semaphore so we wait for the command to complete.
+	 */
+	scmd->device->host->eh_action = &sem;
+	scmd->request->rq_status = RQ_SCSI_BUSY;
+
+	spin_lock_irqsave(scmd->device->host->host_lock, flags);
+	scsi_log_send(scmd);
+	host->hostt->queuecommand(scmd, scsi_eh_done);
+	spin_unlock_irqrestore(scmd->device->host->host_lock, flags);
+
+	down(&sem);
+	scsi_log_completion(scmd, SUCCESS);
+
+	scmd->device->host->eh_action = NULL;
+
+	/*
+	 * see if timeout.  if so, tell the host to forget about it.
+	 * in other words, we don't want a callback any more.
+	 */
+	if (scsi_eh_eflags_chk(scmd, SCSI_EH_REC_TIMEOUT)) {
+		scsi_eh_eflags_clr(scmd,  SCSI_EH_REC_TIMEOUT);
+		scmd->owner = SCSI_OWNER_LOWLEVEL;
+
+		/*
+		 * as far as the low level driver is
+		 * concerned, this command is still active, so
+		 * we must give the low level driver a chance
+		 * to abort it. (db) 
+		 *
+		 * FIXME(eric) - we are not tracking whether we could
+		 * abort a timed out command or not.  not sure how
+		 * we should treat them differently anyways.
+		 */
+		spin_lock_irqsave(scmd->device->host->host_lock, flags);
+		if (scmd->device->host->hostt->eh_abort_handler)
+			scmd->device->host->hostt->eh_abort_handler(scmd);
+		spin_unlock_irqrestore(scmd->device->host->host_lock, flags);
+			
+		scmd->request->rq_status = RQ_SCSI_DONE;
+		scmd->owner = SCSI_OWNER_ERROR_HANDLER;
+			
+		rtn = FAILED;
+	}
+
+	SCSI_LOG_ERROR_RECOVERY(3, printk("%s: scmd: %p, rtn:%x\n",
+					  __FUNCTION__, scmd, rtn));
+
+	/*
+	 * now examine the actual status codes to see whether the command
+	 * actually did complete normally.
+	 */
+	if (rtn == SUCCESS) {
+		rtn = scsi_eh_completed_normally(scmd);
+		SCSI_LOG_ERROR_RECOVERY(3,
+			printk("%s: scsi_eh_completed_normally %x\n",
+			       __FUNCTION__, rtn));
+		switch (rtn) {
+		case SUCCESS:
+		case NEEDS_RETRY:
+		case FAILED:
+			break;
+		default:
+			rtn = FAILED;
+			break;
+		}
+	}
+
+	return rtn;
+}
+
+/**
+ * scsi_request_sense - Request sense data from a particular target.
+ * @scmd:	SCSI cmd for request sense.
+ *
+ * Notes:
+ *    Some hosts automatically obtain this information, others require
+ *    that we obtain it on our own. This function will *not* return until
+ *    the command either times out, or it completes.
+ **/
+static int scsi_request_sense(struct scsi_cmnd *scmd)
+{
+	static unsigned char generic_sense[6] =
+	{REQUEST_SENSE, 0, 0, 0, 252, 0};
+	unsigned char *scsi_result;
+	int saved_result;
+	int rtn;
+
+	memcpy(scmd->cmnd, generic_sense, sizeof(generic_sense));
+
+	scsi_result = kmalloc(252, GFP_ATOMIC | (scmd->device->host->hostt->unchecked_isa_dma) ? __GFP_DMA : 0);
+
+
+	if (unlikely(!scsi_result)) {
+		printk(KERN_ERR "%s: cannot allocate scsi_result.\n",
+		       __FUNCTION__);
+		return FAILED;
+	}
+
+	/*
+	 * zero the sense buffer.  some host adapters automatically always
+	 * request sense, so it is not a good idea that
+	 * scmd->request_buffer and scmd->sense_buffer point to the same
+	 * address (db).  0 is not a valid sense code. 
+	 */
+	memset(scmd->sense_buffer, 0, sizeof(scmd->sense_buffer));
+	memset(scsi_result, 0, 252);
+
+	saved_result = scmd->result;
+	scmd->request_buffer = scsi_result;
+	scmd->request_bufflen = 252;
+	scmd->use_sg = 0;
+	scmd->cmd_len = COMMAND_SIZE(scmd->cmnd[0]);
+	scmd->sc_data_direction = DMA_FROM_DEVICE;
+	scmd->underflow = 0;
+
+	rtn = scsi_send_eh_cmnd(scmd, SENSE_TIMEOUT);
+
+	/* last chance to have valid sense data */
+	if(!SCSI_SENSE_VALID(scmd)) {
+		memcpy(scmd->sense_buffer, scmd->request_buffer,
+		       sizeof(scmd->sense_buffer));
+	}
+
+	kfree(scsi_result);
+
+	/*
+	 * when we eventually call scsi_finish, we really wish to complete
+	 * the original request, so let's restore the original data. (db)
+	 */
+	scsi_setup_cmd_retry(scmd);
+	scmd->result = saved_result;
+	return rtn;
+}
+
+/**
+ * scsi_eh_finish_cmd - Handle a cmd that eh is finished with.
+ * @scmd:	Original SCSI cmd that eh has finished.
+ * @done_q:	Queue for processed commands.
+ *
+ * Notes:
+ *    We don't want to use the normal command completion while we are are
+ *    still handling errors - it may cause other commands to be queued,
+ *    and that would disturb what we are doing.  thus we really want to
+ *    keep a list of pending commands for final completion, and once we
+ *    are ready to leave error handling we handle completion for real.
+ **/
+static void scsi_eh_finish_cmd(struct scsi_cmnd *scmd,
+			       struct list_head *done_q)
+{
+	scmd->device->host->host_failed--;
+	scmd->state = SCSI_STATE_BHQUEUE;
+
+	scsi_eh_eflags_clr_all(scmd);
+
+	/*
+	 * set this back so that the upper level can correctly free up
+	 * things.
+	 */
+	scsi_setup_cmd_retry(scmd);
+	list_move_tail(&scmd->eh_entry, done_q);
+}
+
+/**
+ * scsi_eh_get_sense - Get device sense data.
+ * @work_q:	Queue of commands to process.
+ * @done_q:	Queue of proccessed commands..
+ *
+ * Description:
+ *    See if we need to request sense information.  if so, then get it
+ *    now, so we have a better idea of what to do.  
+ *
+ * Notes:
+ *    This has the unfortunate side effect that if a shost adapter does
+ *    not automatically request sense information, that we end up shutting
+ *    it down before we request it.
+ *
+ *    All drivers should request sense information internally these days,
+ *    so for now all I have to say is tough noogies if you end up in here.
+ *
+ *    XXX: Long term this code should go away, but that needs an audit of
+ *         all LLDDs first.
+ **/
+static int scsi_eh_get_sense(struct list_head *work_q,
+			     struct list_head *done_q)
+{
+	struct list_head *lh, *lh_sf;
+	struct scsi_cmnd *scmd;
+	int rtn;
+
+	list_for_each_safe(lh, lh_sf, work_q) {
+		scmd = list_entry(lh, struct scsi_cmnd, eh_entry);
+		if (scsi_eh_eflags_chk(scmd, SCSI_EH_CANCEL_CMD) ||
+		    SCSI_SENSE_VALID(scmd))
+			continue;
+
+		SCSI_LOG_ERROR_RECOVERY(2, printk("%s: requesting sense"
+						  " for id: %d\n",
+						  current->comm,
+						  scmd->device->id));
+		rtn = scsi_request_sense(scmd);
+		if (rtn != SUCCESS)
+			continue;
+
+		SCSI_LOG_ERROR_RECOVERY(3, printk("sense requested for %p"
+						  " result %x\n", scmd,
+						  scmd->result));
+		SCSI_LOG_ERROR_RECOVERY(3, scsi_print_sense("bh", scmd));
+
+		rtn = scsi_decide_disposition(scmd);
+
+		/*
+		 * if the result was normal, then just pass it along to the
+		 * upper level.
+		 */
+		if (rtn == SUCCESS)
+			/* we don't want this command reissued, just
+			 * finished with the sense data, so set
+			 * retries to the max allowed to ensure it
+			 * won't get reissued */
+			scmd->retries = scmd->allowed;
+		else if (rtn != NEEDS_RETRY)
+			continue;
+
+		scsi_eh_finish_cmd(scmd, done_q);
+	}
+
+	return list_empty(work_q);
+}
+
+/**
+ * scsi_try_to_abort_cmd - Ask host to abort a running command.
+ * @scmd:	SCSI cmd to abort from Lower Level.
+ *
+ * Notes:
+ *    This function will not return until the user's completion function
+ *    has been called.  there is no timeout on this operation.  if the
+ *    author of the low-level driver wishes this operation to be timed,
+ *    they can provide this facility themselves.  helper functions in
+ *    scsi_error.c can be supplied to make this easier to do.
+ **/
+static int scsi_try_to_abort_cmd(struct scsi_cmnd *scmd)
+{
+	unsigned long flags;
+	int rtn = FAILED;
+
+	if (!scmd->device->host->hostt->eh_abort_handler)
+		return rtn;
+
+	/*
+	 * scsi_done was called just after the command timed out and before
+	 * we had a chance to process it. (db)
+	 */
+	if (scmd->serial_number == 0)
+		return SUCCESS;
+
+	scmd->owner = SCSI_OWNER_LOWLEVEL;
+
+	spin_lock_irqsave(scmd->device->host->host_lock, flags);
+	rtn = scmd->device->host->hostt->eh_abort_handler(scmd);
+	spin_unlock_irqrestore(scmd->device->host->host_lock, flags);
+
+	return rtn;
+}
+
+/**
+ * scsi_eh_tur - Send TUR to device.
+ * @scmd:	Scsi cmd to send TUR
+ *
+ * Return value:
+ *    0 - Device is ready. 1 - Device NOT ready.
+ **/
+static int scsi_eh_tur(struct scsi_cmnd *scmd)
+{
+	static unsigned char tur_command[6] = {TEST_UNIT_READY, 0, 0, 0, 0, 0};
+	int retry_cnt = 1, rtn;
+
+retry_tur:
+	memcpy(scmd->cmnd, tur_command, sizeof(tur_command));
+
+	/*
+	 * zero the sense buffer.  the scsi spec mandates that any
+	 * untransferred sense data should be interpreted as being zero.
+	 */
+	memset(scmd->sense_buffer, 0, sizeof(scmd->sense_buffer));
+
+	scmd->request_buffer = NULL;
+	scmd->request_bufflen = 0;
+	scmd->use_sg = 0;
+	scmd->cmd_len = COMMAND_SIZE(scmd->cmnd[0]);
+	scmd->underflow = 0;
+	scmd->sc_data_direction = DMA_NONE;
+
+	rtn = scsi_send_eh_cmnd(scmd, SENSE_TIMEOUT);
+
+	/*
+	 * when we eventually call scsi_finish, we really wish to complete
+	 * the original request, so let's restore the original data. (db)
+	 */
+	scsi_setup_cmd_retry(scmd);
+
+	/*
+	 * hey, we are done.  let's look to see what happened.
+	 */
+	SCSI_LOG_ERROR_RECOVERY(3, printk("%s: scmd %p rtn %x\n",
+		__FUNCTION__, scmd, rtn));
+	if (rtn == SUCCESS)
+		return 0;
+	else if (rtn == NEEDS_RETRY)
+		if (retry_cnt--)
+			goto retry_tur;
+	return 1;
+}
+
+/**
+ * scsi_eh_abort_cmds - abort canceled commands.
+ * @shost:	scsi host being recovered.
+ * @eh_done_q:	list_head for processed commands.
+ *
+ * Decription:
+ *    Try and see whether or not it makes sense to try and abort the
+ *    running command.  this only works out to be the case if we have one
+ *    command that has timed out.  if the command simply failed, it makes
+ *    no sense to try and abort the command, since as far as the shost
+ *    adapter is concerned, it isn't running.
+ **/
+static int scsi_eh_abort_cmds(struct list_head *work_q,
+			      struct list_head *done_q)
+{
+	struct list_head *lh, *lh_sf;
+	struct scsi_cmnd *scmd;
+	int rtn;
+
+	list_for_each_safe(lh, lh_sf, work_q) {
+		scmd = list_entry(lh, struct scsi_cmnd, eh_entry);
+		if (!scsi_eh_eflags_chk(scmd, SCSI_EH_CANCEL_CMD))
+			continue;
+		SCSI_LOG_ERROR_RECOVERY(3, printk("%s: aborting cmd:"
+						  "0x%p\n", current->comm,
+						  scmd));
+		rtn = scsi_try_to_abort_cmd(scmd);
+		if (rtn == SUCCESS) {
+			scsi_eh_eflags_clr(scmd,  SCSI_EH_CANCEL_CMD);
+			if (!scsi_device_online(scmd->device) ||
+			    !scsi_eh_tur(scmd)) {
+				scsi_eh_finish_cmd(scmd, done_q);
+			}
+				
+		} else
+			SCSI_LOG_ERROR_RECOVERY(3, printk("%s: aborting"
+							  " cmd failed:"
+							  "0x%p\n",
+							  current->comm,
+							  scmd));
+	}
+
+	return list_empty(work_q);
+}
+
+/**
+ * scsi_try_bus_device_reset - Ask host to perform a BDR on a dev
+ * @scmd:	SCSI cmd used to send BDR	
+ *
+ * Notes:
+ *    There is no timeout for this operation.  if this operation is
+ *    unreliable for a given host, then the host itself needs to put a
+ *    timer on it, and set the host back to a consistent state prior to
+ *    returning.
+ **/
+static int scsi_try_bus_device_reset(struct scsi_cmnd *scmd)
+{
+	unsigned long flags;
+	int rtn = FAILED;
+
+	if (!scmd->device->host->hostt->eh_device_reset_handler)
+		return rtn;
+
+	scmd->owner = SCSI_OWNER_LOWLEVEL;
+
+	spin_lock_irqsave(scmd->device->host->host_lock, flags);
+	rtn = scmd->device->host->hostt->eh_device_reset_handler(scmd);
+	spin_unlock_irqrestore(scmd->device->host->host_lock, flags);
+
+	if (rtn == SUCCESS) {
+		scmd->device->was_reset = 1;
+		scmd->device->expecting_cc_ua = 1;
+	}
+
+	return rtn;
+}
+
+/**
+ * scsi_eh_try_stu - Send START_UNIT to device.
+ * @scmd:	Scsi cmd to send START_UNIT
+ *
+ * Return value:
+ *    0 - Device is ready. 1 - Device NOT ready.
+ **/
+static int scsi_eh_try_stu(struct scsi_cmnd *scmd)
+{
+	static unsigned char stu_command[6] = {START_STOP, 0, 0, 0, 1, 0};
+	int rtn;
+
+	if (!scmd->device->allow_restart)
+		return 1;
+
+	memcpy(scmd->cmnd, stu_command, sizeof(stu_command));
+
+	/*
+	 * zero the sense buffer.  the scsi spec mandates that any
+	 * untransferred sense data should be interpreted as being zero.
+	 */
+	memset(scmd->sense_buffer, 0, sizeof(scmd->sense_buffer));
+
+	scmd->request_buffer = NULL;
+	scmd->request_bufflen = 0;
+	scmd->use_sg = 0;
+	scmd->cmd_len = COMMAND_SIZE(scmd->cmnd[0]);
+	scmd->underflow = 0;
+	scmd->sc_data_direction = DMA_NONE;
+
+	rtn = scsi_send_eh_cmnd(scmd, START_UNIT_TIMEOUT);
+
+	/*
+	 * when we eventually call scsi_finish, we really wish to complete
+	 * the original request, so let's restore the original data. (db)
+	 */
+	scsi_setup_cmd_retry(scmd);
+
+	/*
+	 * hey, we are done.  let's look to see what happened.
+	 */
+	SCSI_LOG_ERROR_RECOVERY(3, printk("%s: scmd %p rtn %x\n",
+		__FUNCTION__, scmd, rtn));
+	if (rtn == SUCCESS)
+		return 0;
+	return 1;
+}
+
+ /**
+ * scsi_eh_stu - send START_UNIT if needed
+ * @shost:	scsi host being recovered.
+ * @eh_done_q:	list_head for processed commands.
+ *
+ * Notes:
+ *    If commands are failing due to not ready, initializing command required,
+ *	try revalidating the device, which will end up sending a start unit. 
+ **/
+static int scsi_eh_stu(struct Scsi_Host *shost,
+			      struct list_head *work_q,
+			      struct list_head *done_q)
+{
+	struct list_head *lh, *lh_sf;
+	struct scsi_cmnd *scmd, *stu_scmd;
+	struct scsi_device *sdev;
+
+	shost_for_each_device(sdev, shost) {
+		stu_scmd = NULL;
+		list_for_each_entry(scmd, work_q, eh_entry)
+			if (scmd->device == sdev && SCSI_SENSE_VALID(scmd) &&
+			    scsi_check_sense(scmd) == FAILED ) {
+				stu_scmd = scmd;
+				break;
+			}
+
+		if (!stu_scmd)
+			continue;
+
+		SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending START_UNIT to sdev:"
+						  " 0x%p\n", current->comm, sdev));
+
+		if (!scsi_eh_try_stu(stu_scmd)) {
+			if (!scsi_device_online(sdev) ||
+			    !scsi_eh_tur(stu_scmd)) {
+				list_for_each_safe(lh, lh_sf, work_q) {
+					scmd = list_entry(lh, struct scsi_cmnd, eh_entry);
+					if (scmd->device == sdev)
+						scsi_eh_finish_cmd(scmd, done_q);
+				}
+			}
+		} else {
+			SCSI_LOG_ERROR_RECOVERY(3,
+						printk("%s: START_UNIT failed to sdev:"
+						       " 0x%p\n", current->comm, sdev));
+		}
+	}
+
+	return list_empty(work_q);
+}
+
+
+/**
+ * scsi_eh_bus_device_reset - send bdr if needed
+ * @shost:	scsi host being recovered.
+ * @eh_done_q:	list_head for processed commands.
+ *
+ * Notes:
+ *    Try a bus device reset.  still, look to see whether we have multiple
+ *    devices that are jammed or not - if we have multiple devices, it
+ *    makes no sense to try bus_device_reset - we really would need to try
+ *    a bus_reset instead. 
+ **/
+static int scsi_eh_bus_device_reset(struct Scsi_Host *shost,
+				    struct list_head *work_q,
+				    struct list_head *done_q)
+{
+	struct list_head *lh, *lh_sf;
+	struct scsi_cmnd *scmd, *bdr_scmd;
+	struct scsi_device *sdev;
+	int rtn;
+
+	shost_for_each_device(sdev, shost) {
+		bdr_scmd = NULL;
+		list_for_each_entry(scmd, work_q, eh_entry)
+			if (scmd->device == sdev) {
+				bdr_scmd = scmd;
+				break;
+			}
+
+		if (!bdr_scmd)
+			continue;
+
+		SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending BDR sdev:"
+						  " 0x%p\n", current->comm,
+						  sdev));
+		rtn = scsi_try_bus_device_reset(bdr_scmd);
+		if (rtn == SUCCESS) {
+			if (!scsi_device_online(sdev) ||
+			    !scsi_eh_tur(bdr_scmd)) {
+				list_for_each_safe(lh, lh_sf,
+						   work_q) {
+					scmd = list_entry(lh, struct
+							  scsi_cmnd,
+							  eh_entry);
+					if (scmd->device == sdev)
+						scsi_eh_finish_cmd(scmd,
+								   done_q);
+				}
+			}
+		} else {
+			SCSI_LOG_ERROR_RECOVERY(3, printk("%s: BDR"
+							  " failed sdev:"
+							  "0x%p\n",
+							  current->comm,
+							   sdev));
+		}
+	}
+
+	return list_empty(work_q);
+}
+
+/**
+ * scsi_try_bus_reset - ask host to perform a bus reset
+ * @scmd:	SCSI cmd to send bus reset.
+ **/
+static int scsi_try_bus_reset(struct scsi_cmnd *scmd)
+{
+	unsigned long flags;
+	int rtn;
+
+	SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Snd Bus RST\n",
+					  __FUNCTION__));
+	scmd->owner = SCSI_OWNER_LOWLEVEL;
+	scmd->serial_number_at_timeout = scmd->serial_number;
+
+	if (!scmd->device->host->hostt->eh_bus_reset_handler)
+		return FAILED;
+
+	spin_lock_irqsave(scmd->device->host->host_lock, flags);
+	rtn = scmd->device->host->hostt->eh_bus_reset_handler(scmd);
+	spin_unlock_irqrestore(scmd->device->host->host_lock, flags);
+
+	if (rtn == SUCCESS) {
+		if (!scmd->device->host->hostt->skip_settle_delay)
+			ssleep(BUS_RESET_SETTLE_TIME);
+		spin_lock_irqsave(scmd->device->host->host_lock, flags);
+		scsi_report_bus_reset(scmd->device->host, scmd->device->channel);
+		spin_unlock_irqrestore(scmd->device->host->host_lock, flags);
+	}
+
+	return rtn;
+}
+
+/**
+ * scsi_try_host_reset - ask host adapter to reset itself
+ * @scmd:	SCSI cmd to send hsot reset.
+ **/
+static int scsi_try_host_reset(struct scsi_cmnd *scmd)
+{
+	unsigned long flags;
+	int rtn;
+
+	SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Snd Host RST\n",
+					  __FUNCTION__));
+	scmd->owner = SCSI_OWNER_LOWLEVEL;
+	scmd->serial_number_at_timeout = scmd->serial_number;
+
+	if (!scmd->device->host->hostt->eh_host_reset_handler)
+		return FAILED;
+
+	spin_lock_irqsave(scmd->device->host->host_lock, flags);
+	rtn = scmd->device->host->hostt->eh_host_reset_handler(scmd);
+	spin_unlock_irqrestore(scmd->device->host->host_lock, flags);
+
+	if (rtn == SUCCESS) {
+		if (!scmd->device->host->hostt->skip_settle_delay)
+			ssleep(HOST_RESET_SETTLE_TIME);
+		spin_lock_irqsave(scmd->device->host->host_lock, flags);
+		scsi_report_bus_reset(scmd->device->host, scmd->device->channel);
+		spin_unlock_irqrestore(scmd->device->host->host_lock, flags);
+	}
+
+	return rtn;
+}
+
+/**
+ * scsi_eh_bus_reset - send a bus reset 
+ * @shost:	scsi host being recovered.
+ * @eh_done_q:	list_head for processed commands.
+ **/
+static int scsi_eh_bus_reset(struct Scsi_Host *shost,
+			     struct list_head *work_q,
+			     struct list_head *done_q)
+{
+	struct list_head *lh, *lh_sf;
+	struct scsi_cmnd *scmd;
+	struct scsi_cmnd *chan_scmd;
+	unsigned int channel;
+	int rtn;
+
+	/*
+	 * we really want to loop over the various channels, and do this on
+	 * a channel by channel basis.  we should also check to see if any
+	 * of the failed commands are on soft_reset devices, and if so, skip
+	 * the reset.  
+	 */
+
+	for (channel = 0; channel <= shost->max_channel; channel++) {
+		chan_scmd = NULL;
+		list_for_each_entry(scmd, work_q, eh_entry) {
+			if (channel == scmd->device->channel) {
+				chan_scmd = scmd;
+				break;
+				/*
+				 * FIXME add back in some support for
+				 * soft_reset devices.
+				 */
+			}
+		}
+
+		if (!chan_scmd)
+			continue;
+		SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending BRST chan:"
+						  " %d\n", current->comm,
+						  channel));
+		rtn = scsi_try_bus_reset(chan_scmd);
+		if (rtn == SUCCESS) {
+			list_for_each_safe(lh, lh_sf, work_q) {
+				scmd = list_entry(lh, struct scsi_cmnd,
+						  eh_entry);
+				if (channel == scmd->device->channel)
+					if (!scsi_device_online(scmd->device) ||
+					    !scsi_eh_tur(scmd))
+						scsi_eh_finish_cmd(scmd,
+								   done_q);
+			}
+		} else {
+			SCSI_LOG_ERROR_RECOVERY(3, printk("%s: BRST"
+							  " failed chan: %d\n",
+							  current->comm,
+							  channel));
+		}
+	}
+	return list_empty(work_q);
+}
+
+/**
+ * scsi_eh_host_reset - send a host reset 
+ * @work_q:	list_head for processed commands.
+ * @done_q:	list_head for processed commands.
+ **/
+static int scsi_eh_host_reset(struct list_head *work_q,
+			      struct list_head *done_q)
+{
+	int rtn;
+	struct list_head *lh, *lh_sf;
+	struct scsi_cmnd *scmd;
+
+	if (!list_empty(work_q)) {
+		scmd = list_entry(work_q->next,
+				  struct scsi_cmnd, eh_entry);
+
+		SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending HRST\n"
+						  , current->comm));
+
+		rtn = scsi_try_host_reset(scmd);
+		if (rtn == SUCCESS) {
+			list_for_each_safe(lh, lh_sf, work_q) {
+				scmd = list_entry(lh, struct scsi_cmnd, eh_entry);
+				if (!scsi_device_online(scmd->device) ||
+				    (!scsi_eh_try_stu(scmd) && !scsi_eh_tur(scmd)) ||
+				    !scsi_eh_tur(scmd))
+					scsi_eh_finish_cmd(scmd, done_q);
+			}
+		} else {
+			SCSI_LOG_ERROR_RECOVERY(3, printk("%s: HRST"
+							  " failed\n",
+							  current->comm));
+		}
+	}
+	return list_empty(work_q);
+}
+
+/**
+ * scsi_eh_offline_sdevs - offline scsi devices that fail to recover
+ * @work_q:	list_head for processed commands.
+ * @done_q:	list_head for processed commands.
+ *
+ **/
+static void scsi_eh_offline_sdevs(struct list_head *work_q,
+				  struct list_head *done_q)
+{
+	struct list_head *lh, *lh_sf;
+	struct scsi_cmnd *scmd;
+
+	list_for_each_safe(lh, lh_sf, work_q) {
+		scmd = list_entry(lh, struct scsi_cmnd, eh_entry);
+		printk(KERN_INFO "scsi: Device offlined - not"
+		       		" ready after error recovery: host"
+				" %d channel %d id %d lun %d\n",
+				scmd->device->host->host_no,
+				scmd->device->channel,
+				scmd->device->id,
+				scmd->device->lun);
+		scsi_device_set_state(scmd->device, SDEV_OFFLINE);
+		if (scsi_eh_eflags_chk(scmd, SCSI_EH_CANCEL_CMD)) {
+			/*
+			 * FIXME: Handle lost cmds.
+			 */
+		}
+		scsi_eh_finish_cmd(scmd, done_q);
+	}
+	return;
+}
+
+/**
+ * scsi_decide_disposition - Disposition a cmd on return from LLD.
+ * @scmd:	SCSI cmd to examine.
+ *
+ * Notes:
+ *    This is *only* called when we are examining the status after sending
+ *    out the actual data command.  any commands that are queued for error
+ *    recovery (e.g. test_unit_ready) do *not* come through here.
+ *
+ *    When this routine returns failed, it means the error handler thread
+ *    is woken.  In cases where the error code indicates an error that
+ *    doesn't require the error handler read (i.e. we don't need to
+ *    abort/reset), this function should return SUCCESS.
+ **/
+int scsi_decide_disposition(struct scsi_cmnd *scmd)
+{
+	int rtn;
+
+	/*
+	 * if the device is offline, then we clearly just pass the result back
+	 * up to the top level.
+	 */
+	if (!scsi_device_online(scmd->device)) {
+		SCSI_LOG_ERROR_RECOVERY(5, printk("%s: device offline - report"
+						  " as SUCCESS\n",
+						  __FUNCTION__));
+		return SUCCESS;
+	}
+
+	/*
+	 * first check the host byte, to see if there is anything in there
+	 * that would indicate what we need to do.
+	 */
+	switch (host_byte(scmd->result)) {
+	case DID_PASSTHROUGH:
+		/*
+		 * no matter what, pass this through to the upper layer.
+		 * nuke this special code so that it looks like we are saying
+		 * did_ok.
+		 */
+		scmd->result &= 0xff00ffff;
+		return SUCCESS;
+	case DID_OK:
+		/*
+		 * looks good.  drop through, and check the next byte.
+		 */
+		break;
+	case DID_NO_CONNECT:
+	case DID_BAD_TARGET:
+	case DID_ABORT:
+		/*
+		 * note - this means that we just report the status back
+		 * to the top level driver, not that we actually think
+		 * that it indicates SUCCESS.
+		 */
+		return SUCCESS;
+		/*
+		 * when the low level driver returns did_soft_error,
+		 * it is responsible for keeping an internal retry counter 
+		 * in order to avoid endless loops (db)
+		 *
+		 * actually this is a bug in this function here.  we should
+		 * be mindful of the maximum number of retries specified
+		 * and not get stuck in a loop.
+		 */
+	case DID_SOFT_ERROR:
+		goto maybe_retry;
+	case DID_IMM_RETRY:
+		return NEEDS_RETRY;
+
+	case DID_ERROR:
+		if (msg_byte(scmd->result) == COMMAND_COMPLETE &&
+		    status_byte(scmd->result) == RESERVATION_CONFLICT)
+			/*
+			 * execute reservation conflict processing code
+			 * lower down
+			 */
+			break;
+		/* fallthrough */
+
+	case DID_BUS_BUSY:
+	case DID_PARITY:
+		goto maybe_retry;
+	case DID_TIME_OUT:
+		/*
+		 * when we scan the bus, we get timeout messages for
+		 * these commands if there is no device available.
+		 * other hosts report did_no_connect for the same thing.
+		 */
+		if ((scmd->cmnd[0] == TEST_UNIT_READY ||
+		     scmd->cmnd[0] == INQUIRY)) {
+			return SUCCESS;
+		} else {
+			return FAILED;
+		}
+	case DID_RESET:
+		return SUCCESS;
+	default:
+		return FAILED;
+	}
+
+	/*
+	 * next, check the message byte.
+	 */
+	if (msg_byte(scmd->result) != COMMAND_COMPLETE)
+		return FAILED;
+
+	/*
+	 * check the status byte to see if this indicates anything special.
+	 */
+	switch (status_byte(scmd->result)) {
+	case QUEUE_FULL:
+		/*
+		 * the case of trying to send too many commands to a
+		 * tagged queueing device.
+		 */
+	case BUSY:
+		/*
+		 * device can't talk to us at the moment.  Should only
+		 * occur (SAM-3) when the task queue is empty, so will cause
+		 * the empty queue handling to trigger a stall in the
+		 * device.
+		 */
+		return ADD_TO_MLQUEUE;
+	case GOOD:
+	case COMMAND_TERMINATED:
+	case TASK_ABORTED:
+		return SUCCESS;
+	case CHECK_CONDITION:
+		rtn = scsi_check_sense(scmd);
+		if (rtn == NEEDS_RETRY)
+			goto maybe_retry;
+		/* if rtn == FAILED, we have no sense information;
+		 * returning FAILED will wake the error handler thread
+		 * to collect the sense and redo the decide
+		 * disposition */
+		return rtn;
+	case CONDITION_GOOD:
+	case INTERMEDIATE_GOOD:
+	case INTERMEDIATE_C_GOOD:
+	case ACA_ACTIVE:
+		/*
+		 * who knows?  FIXME(eric)
+		 */
+		return SUCCESS;
+
+	case RESERVATION_CONFLICT:
+		printk(KERN_INFO "scsi: reservation conflict: host"
+                                " %d channel %d id %d lun %d\n",
+		       scmd->device->host->host_no, scmd->device->channel,
+		       scmd->device->id, scmd->device->lun);
+		return SUCCESS; /* causes immediate i/o error */
+	default:
+		return FAILED;
+	}
+	return FAILED;
+
+      maybe_retry:
+
+	/* we requeue for retry because the error was retryable, and
+	 * the request was not marked fast fail.  Note that above,
+	 * even if the request is marked fast fail, we still requeue
+	 * for queue congestion conditions (QUEUE_FULL or BUSY) */
+	if ((++scmd->retries) < scmd->allowed 
+	    && !blk_noretry_request(scmd->request)) {
+		return NEEDS_RETRY;
+	} else {
+		/*
+		 * no more retries - report this one back to upper level.
+		 */
+		return SUCCESS;
+	}
+}
+
+/**
+ * scsi_eh_lock_done - done function for eh door lock request
+ * @scmd:	SCSI command block for the door lock request
+ *
+ * Notes:
+ * 	We completed the asynchronous door lock request, and it has either
+ * 	locked the door or failed.  We must free the command structures
+ * 	associated with this request.
+ **/
+static void scsi_eh_lock_done(struct scsi_cmnd *scmd)
+{
+	struct scsi_request *sreq = scmd->sc_request;
+
+	scsi_release_request(sreq);
+}
+
+
+/**
+ * scsi_eh_lock_door - Prevent medium removal for the specified device
+ * @sdev:	SCSI device to prevent medium removal
+ *
+ * Locking:
+ * 	We must be called from process context; scsi_allocate_request()
+ * 	may sleep.
+ *
+ * Notes:
+ * 	We queue up an asynchronous "ALLOW MEDIUM REMOVAL" request on the
+ * 	head of the devices request queue, and continue.
+ *
+ * Bugs:
+ * 	scsi_allocate_request() may sleep waiting for existing requests to
+ * 	be processed.  However, since we haven't kicked off any request
+ * 	processing for this host, this may deadlock.
+ *
+ *	If scsi_allocate_request() fails for what ever reason, we
+ *	completely forget to lock the door.
+ **/
+static void scsi_eh_lock_door(struct scsi_device *sdev)
+{
+	struct scsi_request *sreq = scsi_allocate_request(sdev, GFP_KERNEL);
+
+	if (unlikely(!sreq)) {
+		printk(KERN_ERR "%s: request allocate failed,"
+		       "prevent media removal cmd not sent\n", __FUNCTION__);
+		return;
+	}
+
+	sreq->sr_cmnd[0] = ALLOW_MEDIUM_REMOVAL;
+	sreq->sr_cmnd[1] = 0;
+	sreq->sr_cmnd[2] = 0;
+	sreq->sr_cmnd[3] = 0;
+	sreq->sr_cmnd[4] = SCSI_REMOVAL_PREVENT;
+	sreq->sr_cmnd[5] = 0;
+	sreq->sr_data_direction = DMA_NONE;
+	sreq->sr_bufflen = 0;
+	sreq->sr_buffer = NULL;
+	sreq->sr_allowed = 5;
+	sreq->sr_done = scsi_eh_lock_done;
+	sreq->sr_timeout_per_command = 10 * HZ;
+	sreq->sr_cmd_len = COMMAND_SIZE(sreq->sr_cmnd[0]);
+
+	scsi_insert_special_req(sreq, 1);
+}
+
+
+/**
+ * scsi_restart_operations - restart io operations to the specified host.
+ * @shost:	Host we are restarting.
+ *
+ * Notes:
+ *    When we entered the error handler, we blocked all further i/o to
+ *    this device.  we need to 'reverse' this process.
+ **/
+static void scsi_restart_operations(struct Scsi_Host *shost)
+{
+	struct scsi_device *sdev;
+
+	/*
+	 * If the door was locked, we need to insert a door lock request
+	 * onto the head of the SCSI request queue for the device.  There
+	 * is no point trying to lock the door of an off-line device.
+	 */
+	shost_for_each_device(sdev, shost) {
+		if (scsi_device_online(sdev) && sdev->locked)
+			scsi_eh_lock_door(sdev);
+	}
+
+	/*
+	 * next free up anything directly waiting upon the host.  this
+	 * will be requests for character device operations, and also for
+	 * ioctls to queued block devices.
+	 */
+	SCSI_LOG_ERROR_RECOVERY(3, printk("%s: waking up host to restart\n",
+					  __FUNCTION__));
+
+	clear_bit(SHOST_RECOVERY, &shost->shost_state);
+
+	wake_up(&shost->host_wait);
+
+	/*
+	 * finally we need to re-initiate requests that may be pending.  we will
+	 * have had everything blocked while error handling is taking place, and
+	 * now that error recovery is done, we will need to ensure that these
+	 * requests are started.
+	 */
+	scsi_run_host_queues(shost);
+}
+
+/**
+ * scsi_eh_ready_devs - check device ready state and recover if not.
+ * @shost: 	host to be recovered.
+ * @eh_done_q:	list_head for processed commands.
+ *
+ **/
+static void scsi_eh_ready_devs(struct Scsi_Host *shost,
+			       struct list_head *work_q,
+			       struct list_head *done_q)
+{
+	if (!scsi_eh_stu(shost, work_q, done_q))
+		if (!scsi_eh_bus_device_reset(shost, work_q, done_q))
+			if (!scsi_eh_bus_reset(shost, work_q, done_q))
+				if (!scsi_eh_host_reset(work_q, done_q))
+					scsi_eh_offline_sdevs(work_q, done_q);
+}
+
+/**
+ * scsi_eh_flush_done_q - finish processed commands or retry them.
+ * @done_q:	list_head of processed commands.
+ *
+ **/
+static void scsi_eh_flush_done_q(struct list_head *done_q)
+{
+	struct list_head *lh, *lh_sf;
+	struct scsi_cmnd *scmd;
+
+	list_for_each_safe(lh, lh_sf, done_q) {
+		scmd = list_entry(lh, struct scsi_cmnd, eh_entry);
+		list_del_init(lh);
+		if (scsi_device_online(scmd->device) &&
+		    !blk_noretry_request(scmd->request) &&
+		    (++scmd->retries < scmd->allowed)) {
+			SCSI_LOG_ERROR_RECOVERY(3, printk("%s: flush"
+							  " retry cmd: %p\n",
+							  current->comm,
+							  scmd));
+				scsi_queue_insert(scmd, SCSI_MLQUEUE_EH_RETRY);
+		} else {
+			if (!scmd->result)
+				scmd->result |= (DRIVER_TIMEOUT << 24);
+			SCSI_LOG_ERROR_RECOVERY(3, printk("%s: flush finish"
+							" cmd: %p\n",
+							current->comm, scmd));
+			scsi_finish_command(scmd);
+		}
+	}
+}
+
+/**
+ * scsi_unjam_host - Attempt to fix a host which has a cmd that failed.
+ * @shost:	Host to unjam.
+ *
+ * Notes:
+ *    When we come in here, we *know* that all commands on the bus have
+ *    either completed, failed or timed out.  we also know that no further
+ *    commands are being sent to the host, so things are relatively quiet
+ *    and we have freedom to fiddle with things as we wish.
+ *
+ *    This is only the *default* implementation.  it is possible for
+ *    individual drivers to supply their own version of this function, and
+ *    if the maintainer wishes to do this, it is strongly suggested that
+ *    this function be taken as a template and modified.  this function
+ *    was designed to correctly handle problems for about 95% of the
+ *    different cases out there, and it should always provide at least a
+ *    reasonable amount of error recovery.
+ *
+ *    Any command marked 'failed' or 'timeout' must eventually have
+ *    scsi_finish_cmd() called for it.  we do all of the retry stuff
+ *    here, so when we restart the host after we return it should have an
+ *    empty queue.
+ **/
+static void scsi_unjam_host(struct Scsi_Host *shost)
+{
+	unsigned long flags;
+	LIST_HEAD(eh_work_q);
+	LIST_HEAD(eh_done_q);
+
+	spin_lock_irqsave(shost->host_lock, flags);
+	list_splice_init(&shost->eh_cmd_q, &eh_work_q);
+	spin_unlock_irqrestore(shost->host_lock, flags);
+
+	SCSI_LOG_ERROR_RECOVERY(1, scsi_eh_prt_fail_stats(shost, &eh_work_q));
+
+	if (!scsi_eh_get_sense(&eh_work_q, &eh_done_q))
+		if (!scsi_eh_abort_cmds(&eh_work_q, &eh_done_q))
+			scsi_eh_ready_devs(shost, &eh_work_q, &eh_done_q);
+
+	scsi_eh_flush_done_q(&eh_done_q);
+}
+
+/**
+ * scsi_error_handler - Handle errors/timeouts of SCSI cmds.
+ * @data:	Host for which we are running.
+ *
+ * Notes:
+ *    This is always run in the context of a kernel thread.  The idea is
+ *    that we start this thing up when the kernel starts up (one per host
+ *    that we detect), and it immediately goes to sleep and waits for some
+ *    event (i.e. failure).  When this takes place, we have the job of
+ *    trying to unjam the bus and restarting things.
+ **/
+int scsi_error_handler(void *data)
+{
+	struct Scsi_Host *shost = (struct Scsi_Host *) data;
+	int rtn;
+	DECLARE_MUTEX_LOCKED(sem);
+
+	/*
+	 *    Flush resources
+	 */
+
+	daemonize("scsi_eh_%d", shost->host_no);
+
+	current->flags |= PF_NOFREEZE;
+
+	shost->eh_wait = &sem;
+	shost->ehandler = current;
+
+	/*
+	 * Wake up the thread that created us.
+	 */
+	SCSI_LOG_ERROR_RECOVERY(3, printk("Wake up parent of"
+					  " scsi_eh_%d\n",shost->host_no));
+
+	complete(shost->eh_notify);
+
+	while (1) {
+		/*
+		 * If we get a signal, it means we are supposed to go
+		 * away and die.  This typically happens if the user is
+		 * trying to unload a module.
+		 */
+		SCSI_LOG_ERROR_RECOVERY(1, printk("Error handler"
+						  " scsi_eh_%d"
+						  " sleeping\n",shost->host_no));
+
+		/*
+		 * Note - we always use down_interruptible with the semaphore
+		 * even if the module was loaded as part of the kernel.  The
+		 * reason is that down() will cause this thread to be counted
+		 * in the load average as a running process, and down
+		 * interruptible doesn't.  Given that we need to allow this
+		 * thread to die if the driver was loaded as a module, using
+		 * semaphores isn't unreasonable.
+		 */
+		down_interruptible(&sem);
+		if (shost->eh_kill)
+			break;
+
+		SCSI_LOG_ERROR_RECOVERY(1, printk("Error handler"
+						  " scsi_eh_%d waking"
+						  " up\n",shost->host_no));
+
+		shost->eh_active = 1;
+
+		/*
+		 * We have a host that is failing for some reason.  Figure out
+		 * what we need to do to get it up and online again (if we can).
+		 * If we fail, we end up taking the thing offline.
+		 */
+		if (shost->hostt->eh_strategy_handler) 
+			rtn = shost->hostt->eh_strategy_handler(shost);
+		else
+			scsi_unjam_host(shost);
+
+		shost->eh_active = 0;
+
+		/*
+		 * Note - if the above fails completely, the action is to take
+		 * individual devices offline and flush the queue of any
+		 * outstanding requests that may have been pending.  When we
+		 * restart, we restart any I/O to any other devices on the bus
+		 * which are still online.
+		 */
+		scsi_restart_operations(shost);
+
+	}
+
+	SCSI_LOG_ERROR_RECOVERY(1, printk("Error handler scsi_eh_%d"
+					  " exiting\n",shost->host_no));
+
+	/*
+	 * Make sure that nobody tries to wake us up again.
+	 */
+	shost->eh_wait = NULL;
+
+	/*
+	 * Knock this down too.  From this point on, the host is flying
+	 * without a pilot.  If this is because the module is being unloaded,
+	 * that's fine.  If the user sent a signal to this thing, we are
+	 * potentially in real danger.
+	 */
+	shost->eh_active = 0;
+	shost->ehandler = NULL;
+
+	/*
+	 * If anyone is waiting for us to exit (i.e. someone trying to unload
+	 * a driver), then wake up that process to let them know we are on
+	 * the way out the door.
+	 */
+	complete_and_exit(shost->eh_notify, 0);
+	return 0;
+}
+
+/*
+ * Function:    scsi_report_bus_reset()
+ *
+ * Purpose:     Utility function used by low-level drivers to report that
+ *		they have observed a bus reset on the bus being handled.
+ *
+ * Arguments:   shost       - Host in question
+ *		channel     - channel on which reset was observed.
+ *
+ * Returns:     Nothing
+ *
+ * Lock status: Host lock must be held.
+ *
+ * Notes:       This only needs to be called if the reset is one which
+ *		originates from an unknown location.  Resets originated
+ *		by the mid-level itself don't need to call this, but there
+ *		should be no harm.
+ *
+ *		The main purpose of this is to make sure that a CHECK_CONDITION
+ *		is properly treated.
+ */
+void scsi_report_bus_reset(struct Scsi_Host *shost, int channel)
+{
+	struct scsi_device *sdev;
+
+	__shost_for_each_device(sdev, shost) {
+		if (channel == sdev->channel) {
+			sdev->was_reset = 1;
+			sdev->expecting_cc_ua = 1;
+		}
+	}
+}
+EXPORT_SYMBOL(scsi_report_bus_reset);
+
+/*
+ * Function:    scsi_report_device_reset()
+ *
+ * Purpose:     Utility function used by low-level drivers to report that
+ *		they have observed a device reset on the device being handled.
+ *
+ * Arguments:   shost       - Host in question
+ *		channel     - channel on which reset was observed
+ *		target	    - target on which reset was observed
+ *
+ * Returns:     Nothing
+ *
+ * Lock status: Host lock must be held
+ *
+ * Notes:       This only needs to be called if the reset is one which
+ *		originates from an unknown location.  Resets originated
+ *		by the mid-level itself don't need to call this, but there
+ *		should be no harm.
+ *
+ *		The main purpose of this is to make sure that a CHECK_CONDITION
+ *		is properly treated.
+ */
+void scsi_report_device_reset(struct Scsi_Host *shost, int channel, int target)
+{
+	struct scsi_device *sdev;
+
+	__shost_for_each_device(sdev, shost) {
+		if (channel == sdev->channel &&
+		    target == sdev->id) {
+			sdev->was_reset = 1;
+			sdev->expecting_cc_ua = 1;
+		}
+	}
+}
+EXPORT_SYMBOL(scsi_report_device_reset);
+
+static void
+scsi_reset_provider_done_command(struct scsi_cmnd *scmd)
+{
+}
+
+/*
+ * Function:	scsi_reset_provider
+ *
+ * Purpose:	Send requested reset to a bus or device at any phase.
+ *
+ * Arguments:	device	- device to send reset to
+ *		flag - reset type (see scsi.h)
+ *
+ * Returns:	SUCCESS/FAILURE.
+ *
+ * Notes:	This is used by the SCSI Generic driver to provide
+ *		Bus/Device reset capability.
+ */
+int
+scsi_reset_provider(struct scsi_device *dev, int flag)
+{
+	struct scsi_cmnd *scmd = scsi_get_command(dev, GFP_KERNEL);
+	struct request req;
+	int rtn;
+
+	scmd->request = &req;
+	memset(&scmd->eh_timeout, 0, sizeof(scmd->eh_timeout));
+	scmd->request->rq_status      	= RQ_SCSI_BUSY;
+	scmd->state                   	= SCSI_STATE_INITIALIZING;
+	scmd->owner	     		= SCSI_OWNER_MIDLEVEL;
+    
+	memset(&scmd->cmnd, '\0', sizeof(scmd->cmnd));
+    
+	scmd->scsi_done		= scsi_reset_provider_done_command;
+	scmd->done			= NULL;
+	scmd->buffer			= NULL;
+	scmd->bufflen			= 0;
+	scmd->request_buffer		= NULL;
+	scmd->request_bufflen		= 0;
+	scmd->internal_timeout		= NORMAL_TIMEOUT;
+	scmd->abort_reason		= DID_ABORT;
+
+	scmd->cmd_len			= 0;
+
+	scmd->sc_data_direction		= DMA_BIDIRECTIONAL;
+	scmd->sc_request		= NULL;
+	scmd->sc_magic			= SCSI_CMND_MAGIC;
+
+	init_timer(&scmd->eh_timeout);
+
+	/*
+	 * Sometimes the command can get back into the timer chain,
+	 * so use the pid as an identifier.
+	 */
+	scmd->pid			= 0;
+
+	switch (flag) {
+	case SCSI_TRY_RESET_DEVICE:
+		rtn = scsi_try_bus_device_reset(scmd);
+		if (rtn == SUCCESS)
+			break;
+		/* FALLTHROUGH */
+	case SCSI_TRY_RESET_BUS:
+		rtn = scsi_try_bus_reset(scmd);
+		if (rtn == SUCCESS)
+			break;
+		/* FALLTHROUGH */
+	case SCSI_TRY_RESET_HOST:
+		rtn = scsi_try_host_reset(scmd);
+		break;
+	default:
+		rtn = FAILED;
+	}
+
+	scsi_delete_timer(scmd);
+	scsi_next_command(scmd);
+	return rtn;
+}
+EXPORT_SYMBOL(scsi_reset_provider);
+
+/**
+ * scsi_normalize_sense - normalize main elements from either fixed or
+ *			descriptor sense data format into a common format.
+ *
+ * @sense_buffer:	byte array containing sense data returned by device
+ * @sb_len:		number of valid bytes in sense_buffer
+ * @sshdr:		pointer to instance of structure that common
+ *			elements are written to.
+ *
+ * Notes:
+ *	The "main elements" from sense data are: response_code, sense_key,
+ *	asc, ascq and additional_length (only for descriptor format).
+ *
+ *	Typically this function can be called after a device has
+ *	responded to a SCSI command with the CHECK_CONDITION status.
+ *
+ * Return value:
+ *	1 if valid sense data information found, else 0;
+ **/
+int scsi_normalize_sense(const u8 *sense_buffer, int sb_len,
+                         struct scsi_sense_hdr *sshdr)
+{
+	if (!sense_buffer || !sb_len || (sense_buffer[0] & 0x70) != 0x70)
+		return 0;
+
+	memset(sshdr, 0, sizeof(struct scsi_sense_hdr));
+
+	sshdr->response_code = (sense_buffer[0] & 0x7f);
+	if (sshdr->response_code >= 0x72) {
+		/*
+		 * descriptor format
+		 */
+		if (sb_len > 1)
+			sshdr->sense_key = (sense_buffer[1] & 0xf);
+		if (sb_len > 2)
+			sshdr->asc = sense_buffer[2];
+		if (sb_len > 3)
+			sshdr->ascq = sense_buffer[3];
+		if (sb_len > 7)
+			sshdr->additional_length = sense_buffer[7];
+	} else {
+		/* 
+		 * fixed format
+		 */
+		if (sb_len > 2)
+			sshdr->sense_key = (sense_buffer[2] & 0xf);
+		if (sb_len > 7) {
+			sb_len = (sb_len < (sense_buffer[7] + 8)) ?
+					 sb_len : (sense_buffer[7] + 8);
+			if (sb_len > 12)
+				sshdr->asc = sense_buffer[12];
+			if (sb_len > 13)
+				sshdr->ascq = sense_buffer[13];
+		}
+	}
+
+	return 1;
+}
+EXPORT_SYMBOL(scsi_normalize_sense);
+
+int scsi_request_normalize_sense(struct scsi_request *sreq,
+				 struct scsi_sense_hdr *sshdr)
+{
+	return scsi_normalize_sense(sreq->sr_sense_buffer,
+			sizeof(sreq->sr_sense_buffer), sshdr);
+}
+EXPORT_SYMBOL(scsi_request_normalize_sense);
+
+int scsi_command_normalize_sense(struct scsi_cmnd *cmd,
+				 struct scsi_sense_hdr *sshdr)
+{
+	return scsi_normalize_sense(cmd->sense_buffer,
+			sizeof(cmd->sense_buffer), sshdr);
+}
+EXPORT_SYMBOL(scsi_command_normalize_sense);
+
+/**
+ * scsi_sense_desc_find - search for a given descriptor type in
+ *			descriptor sense data format.
+ *
+ * @sense_buffer:	byte array of descriptor format sense data
+ * @sb_len:		number of valid bytes in sense_buffer
+ * @desc_type:		value of descriptor type to find
+ *			(e.g. 0 -> information)
+ *
+ * Notes:
+ *	only valid when sense data is in descriptor format
+ *
+ * Return value:
+ *	pointer to start of (first) descriptor if found else NULL
+ **/
+const u8 * scsi_sense_desc_find(const u8 * sense_buffer, int sb_len,
+				int desc_type)
+{
+	int add_sen_len, add_len, desc_len, k;
+	const u8 * descp;
+
+	if ((sb_len < 8) || (0 == (add_sen_len = sense_buffer[7])))
+		return NULL;
+	if ((sense_buffer[0] < 0x72) || (sense_buffer[0] > 0x73))
+		return NULL;
+	add_sen_len = (add_sen_len < (sb_len - 8)) ?
+			add_sen_len : (sb_len - 8);
+	descp = &sense_buffer[8];
+	for (desc_len = 0, k = 0; k < add_sen_len; k += desc_len) {
+		descp += desc_len;
+		add_len = (k < (add_sen_len - 1)) ? descp[1]: -1;
+		desc_len = add_len + 2;
+		if (descp[0] == desc_type)
+			return descp;
+		if (add_len < 0) // short descriptor ??
+			break;
+	}
+	return NULL;
+}
+EXPORT_SYMBOL(scsi_sense_desc_find);
+
+/**
+ * scsi_get_sense_info_fld - attempts to get information field from
+ *			sense data (either fixed or descriptor format)
+ *
+ * @sense_buffer:	byte array of sense data
+ * @sb_len:		number of valid bytes in sense_buffer
+ * @info_out:		pointer to 64 integer where 8 or 4 byte information
+ *			field will be placed if found.
+ *
+ * Return value:
+ *	1 if information field found, 0 if not found.
+ **/
+int scsi_get_sense_info_fld(const u8 * sense_buffer, int sb_len,
+			    u64 * info_out)
+{
+	int j;
+	const u8 * ucp;
+	u64 ull;
+
+	if (sb_len < 7)
+		return 0;
+	switch (sense_buffer[0] & 0x7f) {
+	case 0x70:
+	case 0x71:
+		if (sense_buffer[0] & 0x80) {
+			*info_out = (sense_buffer[3] << 24) +
+				    (sense_buffer[4] << 16) +
+				    (sense_buffer[5] << 8) + sense_buffer[6];
+			return 1;
+		} else
+			return 0;
+	case 0x72:
+	case 0x73:
+		ucp = scsi_sense_desc_find(sense_buffer, sb_len,
+					   0 /* info desc */);
+		if (ucp && (0xa == ucp[1])) {
+			ull = 0;
+			for (j = 0; j < 8; ++j) {
+				if (j > 0)
+					ull <<= 8;
+				ull |= ucp[4 + j];
+			}
+			*info_out = ull;
+			return 1;
+		} else
+			return 0;
+	default:
+		return 0;
+	}
+}
+EXPORT_SYMBOL(scsi_get_sense_info_fld);