Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2453 insertions, 0 deletions

diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
new file mode 100644
index 000000000..e731af504
--- /dev/null
+++ b/drivers/scsi/scsi_error.c
@@ -0,0 +1,2453 @@
+/*
+ *  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/gfp.h>
+#include <linux/timer.h>
+#include <linux/string.h>
+#include <linux/kernel.h>
+#include <linux/freezer.h>
+#include <linux/kthread.h>
+#include <linux/interrupt.h>
+#include <linux/blkdev.h>
+#include <linux/delay.h>
+#include <linux/jiffies.h>
+
+#include <scsi/scsi.h>
+#include <scsi/scsi_cmnd.h>
+#include <scsi/scsi_dbg.h>
+#include <scsi/scsi_device.h>
+#include <scsi/scsi_driver.h>
+#include <scsi/scsi_eh.h>
+#include <scsi/scsi_common.h>
+#include <scsi/scsi_transport.h>
+#include <scsi/scsi_host.h>
+#include <scsi/scsi_ioctl.h>
+#include <scsi/scsi_dh.h>
+#include <scsi/scsi_devinfo.h>
+#include <scsi/sg.h>
+
+#include "scsi_priv.h"
+#include "scsi_logging.h"
+#include "scsi_transport_api.h"
+
+#include <trace/events/scsi.h>
+
+#include <asm/unaligned.h>
+
+static void scsi_eh_done(struct scsi_cmnd *scmd);
+
+/*
+ * 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)
+
+static int scsi_eh_try_stu(struct scsi_cmnd *scmd);
+static int scsi_try_to_abort_cmd(struct scsi_host_template *,
+				 struct scsi_cmnd *);
+
+void scsi_eh_wakeup(struct Scsi_Host *shost)
+{
+	lockdep_assert_held(shost->host_lock);
+
+	if (scsi_host_busy(shost) == shost->host_failed) {
+		trace_scsi_eh_wakeup(shost);
+		wake_up_process(shost->ehandler);
+		SCSI_LOG_ERROR_RECOVERY(5, shost_printk(KERN_INFO, shost,
+			"Waking error handler thread\n"));
+	}
+}
+
+/**
+ * scsi_schedule_eh - schedule EH for SCSI host
+ * @shost:	SCSI host to invoke error handling on.
+ *
+ * Schedule SCSI EH without scmd.
+ */
+void scsi_schedule_eh(struct Scsi_Host *shost)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(shost->host_lock, flags);
+
+	if (scsi_host_set_state(shost, SHOST_RECOVERY) == 0 ||
+	    scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY) == 0) {
+		shost->host_eh_scheduled++;
+		scsi_eh_wakeup(shost);
+	}
+
+	spin_unlock_irqrestore(shost->host_lock, flags);
+}
+EXPORT_SYMBOL_GPL(scsi_schedule_eh);
+
+static int scsi_host_eh_past_deadline(struct Scsi_Host *shost)
+{
+	if (!shost->last_reset || shost->eh_deadline == -1)
+		return 0;
+
+	/*
+	 * 32bit accesses are guaranteed to be atomic
+	 * (on all supported architectures), so instead
+	 * of using a spinlock we can as well double check
+	 * if eh_deadline has been set to 'off' during the
+	 * time_before call.
+	 */
+	if (time_before(jiffies, shost->last_reset + shost->eh_deadline) &&
+	    shost->eh_deadline > -1)
+		return 0;
+
+	return 1;
+}
+
+/**
+ * scmd_eh_abort_handler - Handle command aborts
+ * @work:	command to be aborted.
+ *
+ * Note: this function must be called only for a command that has timed out.
+ * Because the block layer marks a request as complete before it calls
+ * scsi_times_out(), a .scsi_done() call from the LLD for a command that has
+ * timed out do not have any effect. Hence it is safe to call
+ * scsi_finish_command() from this function.
+ */
+void
+scmd_eh_abort_handler(struct work_struct *work)
+{
+	struct scsi_cmnd *scmd =
+		container_of(work, struct scsi_cmnd, abort_work.work);
+	struct scsi_device *sdev = scmd->device;
+	int rtn;
+
+	if (scsi_host_eh_past_deadline(sdev->host)) {
+		SCSI_LOG_ERROR_RECOVERY(3,
+			scmd_printk(KERN_INFO, scmd,
+				    "eh timeout, not aborting\n"));
+	} else {
+		SCSI_LOG_ERROR_RECOVERY(3,
+			scmd_printk(KERN_INFO, scmd,
+				    "aborting command\n"));
+		rtn = scsi_try_to_abort_cmd(sdev->host->hostt, scmd);
+		if (rtn == SUCCESS) {
+			set_host_byte(scmd, DID_TIME_OUT);
+			if (scsi_host_eh_past_deadline(sdev->host)) {
+				SCSI_LOG_ERROR_RECOVERY(3,
+					scmd_printk(KERN_INFO, scmd,
+						    "eh timeout, not retrying "
+						    "aborted command\n"));
+			} else if (!scsi_noretry_cmd(scmd) &&
+			    (++scmd->retries <= scmd->allowed)) {
+				SCSI_LOG_ERROR_RECOVERY(3,
+					scmd_printk(KERN_WARNING, scmd,
+						    "retry aborted command\n"));
+				scsi_queue_insert(scmd, SCSI_MLQUEUE_EH_RETRY);
+				return;
+			} else {
+				SCSI_LOG_ERROR_RECOVERY(3,
+					scmd_printk(KERN_WARNING, scmd,
+						    "finish aborted command\n"));
+				scsi_finish_command(scmd);
+				return;
+			}
+		} else {
+			SCSI_LOG_ERROR_RECOVERY(3,
+				scmd_printk(KERN_INFO, scmd,
+					    "cmd abort %s\n",
+					    (rtn == FAST_IO_FAIL) ?
+					    "not send" : "failed"));
+		}
+	}
+
+	scsi_eh_scmd_add(scmd);
+}
+
+/**
+ * scsi_abort_command - schedule a command abort
+ * @scmd:	scmd to abort.
+ *
+ * We only need to abort commands after a command timeout
+ */
+static int
+scsi_abort_command(struct scsi_cmnd *scmd)
+{
+	struct scsi_device *sdev = scmd->device;
+	struct Scsi_Host *shost = sdev->host;
+	unsigned long flags;
+
+	if (scmd->eh_eflags & SCSI_EH_ABORT_SCHEDULED) {
+		/*
+		 * Retry after abort failed, escalate to next level.
+		 */
+		SCSI_LOG_ERROR_RECOVERY(3,
+			scmd_printk(KERN_INFO, scmd,
+				    "previous abort failed\n"));
+		BUG_ON(delayed_work_pending(&scmd->abort_work));
+		return FAILED;
+	}
+
+	spin_lock_irqsave(shost->host_lock, flags);
+	if (shost->eh_deadline != -1 && !shost->last_reset)
+		shost->last_reset = jiffies;
+	spin_unlock_irqrestore(shost->host_lock, flags);
+
+	scmd->eh_eflags |= SCSI_EH_ABORT_SCHEDULED;
+	SCSI_LOG_ERROR_RECOVERY(3,
+		scmd_printk(KERN_INFO, scmd, "abort scheduled\n"));
+	queue_delayed_work(shost->tmf_work_q, &scmd->abort_work, HZ / 100);
+	return SUCCESS;
+}
+
+/**
+ * scsi_eh_reset - call into ->eh_action to reset internal counters
+ * @scmd:	scmd to run eh on.
+ *
+ * The scsi driver might be carrying internal state about the
+ * devices, so we need to call into the driver to reset the
+ * internal state once the error handler is started.
+ */
+static void scsi_eh_reset(struct scsi_cmnd *scmd)
+{
+	if (!blk_rq_is_passthrough(scmd->request)) {
+		struct scsi_driver *sdrv = scsi_cmd_to_driver(scmd);
+		if (sdrv->eh_reset)
+			sdrv->eh_reset(scmd);
+	}
+}
+
+static void scsi_eh_inc_host_failed(struct rcu_head *head)
+{
+	struct scsi_cmnd *scmd = container_of(head, typeof(*scmd), rcu);
+	struct Scsi_Host *shost = scmd->device->host;
+	unsigned long flags;
+
+	spin_lock_irqsave(shost->host_lock, flags);
+	shost->host_failed++;
+	scsi_eh_wakeup(shost);
+	spin_unlock_irqrestore(shost->host_lock, flags);
+}
+
+/**
+ * scsi_eh_scmd_add - add scsi cmd to error handling.
+ * @scmd:	scmd to run eh on.
+ */
+void scsi_eh_scmd_add(struct scsi_cmnd *scmd)
+{
+	struct Scsi_Host *shost = scmd->device->host;
+	unsigned long flags;
+	int ret;
+
+	WARN_ON_ONCE(!shost->ehandler);
+
+	spin_lock_irqsave(shost->host_lock, flags);
+	if (scsi_host_set_state(shost, SHOST_RECOVERY)) {
+		ret = scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY);
+		WARN_ON_ONCE(ret);
+	}
+	if (shost->eh_deadline != -1 && !shost->last_reset)
+		shost->last_reset = jiffies;
+
+	scsi_eh_reset(scmd);
+	list_add_tail(&scmd->eh_entry, &shost->eh_cmd_q);
+	spin_unlock_irqrestore(shost->host_lock, flags);
+	/*
+	 * Ensure that all tasks observe the host state change before the
+	 * host_failed change.
+	 */
+	call_rcu(&scmd->rcu, scsi_eh_inc_host_failed);
+}
+
+/**
+ * scsi_times_out - Timeout function for normal scsi commands.
+ * @req:	request 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.
+ */
+enum blk_eh_timer_return scsi_times_out(struct request *req)
+{
+	struct scsi_cmnd *scmd = blk_mq_rq_to_pdu(req);
+	enum blk_eh_timer_return rtn = BLK_EH_DONE;
+	struct Scsi_Host *host = scmd->device->host;
+
+	trace_scsi_dispatch_cmd_timeout(scmd);
+	scsi_log_completion(scmd, TIMEOUT_ERROR);
+
+	if (host->eh_deadline != -1 && !host->last_reset)
+		host->last_reset = jiffies;
+
+	if (host->hostt->eh_timed_out)
+		rtn = host->hostt->eh_timed_out(scmd);
+
+	if (rtn == BLK_EH_DONE) {
+		/*
+		 * For blk-mq, we must set the request state to complete now
+		 * before sending the request to the scsi error handler. This
+		 * will prevent a use-after-free in the event the LLD manages
+		 * to complete the request before the error handler finishes
+		 * processing this timed out request.
+		 *
+		 * If the request was already completed, then the LLD beat the
+		 * time out handler from transferring the request to the scsi
+		 * error handler. In that case we can return immediately as no
+		 * further action is required.
+		 */
+		if (req->q->mq_ops && !blk_mq_mark_complete(req))
+			return rtn;
+		if (scsi_abort_command(scmd) != SUCCESS) {
+			set_host_byte(scmd, DID_TIME_OUT);
+			scsi_eh_scmd_add(scmd);
+		}
+	}
+
+	return rtn;
+}
+
+/**
+ * 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, !scsi_host_in_recovery(sdev->host));
+
+	online = scsi_device_online(sdev);
+
+	SCSI_LOG_ERROR_RECOVERY(5, sdev_printk(KERN_INFO, sdev,
+		"%s: rtn: %d\n", __func__, 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 (scmd->eh_eflags & SCSI_EH_ABORT_SCHEDULED)
+					++cmd_cancel;
+				else
+					++cmd_failed;
+			}
+		}
+
+		if (cmd_cancel || cmd_failed) {
+			SCSI_LOG_ERROR_RECOVERY(3,
+				shost_printk(KERN_INFO, shost,
+					    "%s: cmds failed: %d, cancel: %d\n",
+					    __func__, cmd_failed,
+					    cmd_cancel));
+			cmd_cancel = 0;
+			cmd_failed = 0;
+			++devices_failed;
+		}
+	}
+
+	SCSI_LOG_ERROR_RECOVERY(2, shost_printk(KERN_INFO, shost,
+				   "Total of %d commands on %d"
+				   " devices require eh work\n",
+				   total_failures, devices_failed));
+}
+#endif
+
+ /**
+ * scsi_report_lun_change - Set flag on all *other* devices on the same target
+ *                          to indicate that a UNIT ATTENTION is expected.
+ * @sdev:	Device reporting the UNIT ATTENTION
+ */
+static void scsi_report_lun_change(struct scsi_device *sdev)
+{
+	sdev->sdev_target->expecting_lun_change = 1;
+}
+
+/**
+ * scsi_report_sense - Examine scsi sense information and log messages for
+ *		       certain conditions, also issue uevents for some of them.
+ * @sdev:	Device reporting the sense code
+ * @sshdr:	sshdr to be examined
+ */
+static void scsi_report_sense(struct scsi_device *sdev,
+			      struct scsi_sense_hdr *sshdr)
+{
+	enum scsi_device_event evt_type = SDEV_EVT_MAXBITS;	/* i.e. none */
+
+	if (sshdr->sense_key == UNIT_ATTENTION) {
+		if (sshdr->asc == 0x3f && sshdr->ascq == 0x03) {
+			evt_type = SDEV_EVT_INQUIRY_CHANGE_REPORTED;
+			sdev_printk(KERN_WARNING, sdev,
+				    "Inquiry data has changed");
+		} else if (sshdr->asc == 0x3f && sshdr->ascq == 0x0e) {
+			evt_type = SDEV_EVT_LUN_CHANGE_REPORTED;
+			scsi_report_lun_change(sdev);
+			sdev_printk(KERN_WARNING, sdev,
+				    "Warning! Received an indication that the "
+				    "LUN assignments on this target have "
+				    "changed. The Linux SCSI layer does not "
+				    "automatically remap LUN assignments.\n");
+		} else if (sshdr->asc == 0x3f)
+			sdev_printk(KERN_WARNING, sdev,
+				    "Warning! Received an indication that the "
+				    "operating parameters on this target have "
+				    "changed. The Linux SCSI layer does not "
+				    "automatically adjust these parameters.\n");
+
+		if (sshdr->asc == 0x38 && sshdr->ascq == 0x07) {
+			evt_type = SDEV_EVT_SOFT_THRESHOLD_REACHED_REPORTED;
+			sdev_printk(KERN_WARNING, sdev,
+				    "Warning! Received an indication that the "
+				    "LUN reached a thin provisioning soft "
+				    "threshold.\n");
+		}
+
+		if (sshdr->asc == 0x29) {
+			evt_type = SDEV_EVT_POWER_ON_RESET_OCCURRED;
+			sdev_printk(KERN_WARNING, sdev,
+				    "Power-on or device reset occurred\n");
+		}
+
+		if (sshdr->asc == 0x2a && sshdr->ascq == 0x01) {
+			evt_type = SDEV_EVT_MODE_PARAMETER_CHANGE_REPORTED;
+			sdev_printk(KERN_WARNING, sdev,
+				    "Mode parameters changed");
+		} else if (sshdr->asc == 0x2a && sshdr->ascq == 0x06) {
+			evt_type = SDEV_EVT_ALUA_STATE_CHANGE_REPORTED;
+			sdev_printk(KERN_WARNING, sdev,
+				    "Asymmetric access state changed");
+		} else if (sshdr->asc == 0x2a && sshdr->ascq == 0x09) {
+			evt_type = SDEV_EVT_CAPACITY_CHANGE_REPORTED;
+			sdev_printk(KERN_WARNING, sdev,
+				    "Capacity data has changed");
+		} else if (sshdr->asc == 0x2a)
+			sdev_printk(KERN_WARNING, sdev,
+				    "Parameters changed");
+	}
+
+	if (evt_type != SDEV_EVT_MAXBITS) {
+		set_bit(evt_type, sdev->pending_events);
+		schedule_work(&sdev->event_work);
+	}
+}
+
+/**
+ * scsi_check_sense - Examine scsi cmd sense
+ * @scmd:	Cmd to have sense checked.
+ *
+ * Return value:
+ *	SUCCESS or FAILED or NEEDS_RETRY or ADD_TO_MLQUEUE
+ *
+ * Notes:
+ *	When a deferred error is detected the current command has
+ *	not been executed and needs retrying.
+ */
+int scsi_check_sense(struct scsi_cmnd *scmd)
+{
+	struct scsi_device *sdev = scmd->device;
+	struct scsi_sense_hdr sshdr;
+
+	if (! scsi_command_normalize_sense(scmd, &sshdr))
+		return FAILED;	/* no valid sense data */
+
+	scsi_report_sense(sdev, &sshdr);
+
+	if (scsi_sense_is_deferred(&sshdr))
+		return NEEDS_RETRY;
+
+	if (sdev->handler && sdev->handler->check_sense) {
+		int rc;
+
+		rc = sdev->handler->check_sense(sdev, &sshdr);
+		if (rc != SCSI_RETURN_NOT_HANDLED)
+			return rc;
+		/* handler does not care. Drop down to default handling */
+	}
+
+	if (scmd->cmnd[0] == TEST_UNIT_READY && scmd->scsi_done != scsi_eh_done)
+		/*
+		 * nasty: for mid-layer issued TURs, we need to return the
+		 * actual sense data without any recovery attempt.  For eh
+		 * issued ones, we need to try to recover and interpret
+		 */
+		return SUCCESS;
+
+	/*
+	 * 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:
+		if (sshdr.asc == 0x10) /* DIF */
+			return SUCCESS;
+
+		if (sshdr.asc == 0x44 && sdev->sdev_bflags & BLIST_RETRY_ITF)
+			return ADD_TO_MLQUEUE;
+		if (sshdr.asc == 0xc1 && sshdr.ascq == 0x01 &&
+		    sdev->sdev_bflags & BLIST_RETRY_ASC_C1)
+			return ADD_TO_MLQUEUE;
+
+		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) {
+			/*
+			 * Because some device does not queue unit
+			 * attentions correctly, we carefully check
+			 * additional sense code and qualifier so as
+			 * not to squash media change unit attention.
+			 */
+			if (sshdr.asc != 0x28 || sshdr.ascq != 0x00) {
+				scmd->device->expecting_cc_ua = 0;
+				return NEEDS_RETRY;
+			}
+		}
+		/*
+		 * we might also expect a cc/ua if another LUN on the target
+		 * reported a UA with an ASC/ASCQ of 3F 0E -
+		 * REPORTED LUNS DATA HAS CHANGED.
+		 */
+		if (scmd->device->sdev_target->expecting_lun_change &&
+		    sshdr.asc == 0x3f && sshdr.ascq == 0x0e)
+			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;
+		/*
+		 * Pass the UA upwards for a determination in the completion
+		 * functions.
+		 */
+		return SUCCESS;
+
+		/* these are not supported */
+	case DATA_PROTECT:
+		if (sshdr.asc == 0x27 && sshdr.ascq == 0x07) {
+			/* Thin provisioning hard threshold reached */
+			set_host_byte(scmd, DID_ALLOC_FAILURE);
+			return SUCCESS;
+		}
+		/* FALLTHROUGH */
+	case COPY_ABORTED:
+	case VOLUME_OVERFLOW:
+	case MISCOMPARE:
+	case BLANK_CHECK:
+		set_host_byte(scmd, DID_TARGET_FAILURE);
+		return SUCCESS;
+
+	case MEDIUM_ERROR:
+		if (sshdr.asc == 0x11 || /* UNRECOVERED READ ERR */
+		    sshdr.asc == 0x13 || /* AMNF DATA FIELD */
+		    sshdr.asc == 0x14) { /* RECORD NOT FOUND */
+			set_host_byte(scmd, DID_MEDIUM_ERROR);
+			return SUCCESS;
+		}
+		return NEEDS_RETRY;
+
+	case HARDWARE_ERROR:
+		if (scmd->device->retry_hwerror)
+			return ADD_TO_MLQUEUE;
+		else
+			set_host_byte(scmd, DID_TARGET_FAILURE);
+		/* FALLTHROUGH */
+
+	case ILLEGAL_REQUEST:
+		if (sshdr.asc == 0x20 || /* Invalid command operation code */
+		    sshdr.asc == 0x21 || /* Logical block address out of range */
+		    sshdr.asc == 0x22 || /* Invalid function */
+		    sshdr.asc == 0x24 || /* Invalid field in cdb */
+		    sshdr.asc == 0x26 || /* Parameter value invalid */
+		    sshdr.asc == 0x27) { /* Write protected */
+			set_host_byte(scmd, DID_TARGET_FAILURE);
+		}
+		return SUCCESS;
+
+	default:
+		return SUCCESS;
+	}
+}
+EXPORT_SYMBOL_GPL(scsi_check_sense);
+
+static void scsi_handle_queue_ramp_up(struct scsi_device *sdev)
+{
+	struct scsi_host_template *sht = sdev->host->hostt;
+	struct scsi_device *tmp_sdev;
+
+	if (!sht->track_queue_depth ||
+	    sdev->queue_depth >= sdev->max_queue_depth)
+		return;
+
+	if (time_before(jiffies,
+	    sdev->last_queue_ramp_up + sdev->queue_ramp_up_period))
+		return;
+
+	if (time_before(jiffies,
+	    sdev->last_queue_full_time + sdev->queue_ramp_up_period))
+		return;
+
+	/*
+	 * Walk all devices of a target and do
+	 * ramp up on them.
+	 */
+	shost_for_each_device(tmp_sdev, sdev->host) {
+		if (tmp_sdev->channel != sdev->channel ||
+		    tmp_sdev->id != sdev->id ||
+		    tmp_sdev->queue_depth == sdev->max_queue_depth)
+			continue;
+
+		scsi_change_queue_depth(tmp_sdev, tmp_sdev->queue_depth + 1);
+		sdev->last_queue_ramp_up = jiffies;
+	}
+}
+
+static void scsi_handle_queue_full(struct scsi_device *sdev)
+{
+	struct scsi_host_template *sht = sdev->host->hostt;
+	struct scsi_device *tmp_sdev;
+
+	if (!sht->track_queue_depth)
+		return;
+
+	shost_for_each_device(tmp_sdev, sdev->host) {
+		if (tmp_sdev->channel != sdev->channel ||
+		    tmp_sdev->id != sdev->id)
+			continue;
+		/*
+		 * We do not know the number of commands that were at
+		 * the device when we got the queue full so we start
+		 * from the highest possible value and work our way down.
+		 */
+		scsi_track_queue_full(tmp_sdev, tmp_sdev->queue_depth - 1);
+	}
+}
+
+/**
+ * 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:
+		scsi_handle_queue_ramp_up(scmd->device);
+		/* FALLTHROUGH */
+	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 RESERVATION_CONFLICT:
+		if (scmd->cmnd[0] == TEST_UNIT_READY)
+			/* it is a success, we probed the device and
+			 * found it */
+			return SUCCESS;
+		/* otherwise, we failed to send the command */
+		return FAILED;
+	case QUEUE_FULL:
+		scsi_handle_queue_full(scmd->device);
+		/* fall through */
+	case BUSY:
+		return NEEDS_RETRY;
+	default:
+		return FAILED;
+	}
+	return FAILED;
+}
+
+/**
+ * scsi_eh_done - Completion function for error handling.
+ * @scmd:	Cmd that is done.
+ */
+static void scsi_eh_done(struct scsi_cmnd *scmd)
+{
+	struct completion *eh_action;
+
+	SCSI_LOG_ERROR_RECOVERY(3, scmd_printk(KERN_INFO, scmd,
+			"%s result: %x\n", __func__, scmd->result));
+
+	eh_action = scmd->device->host->eh_action;
+	if (eh_action)
+		complete(eh_action);
+}
+
+/**
+ * scsi_try_host_reset - ask host adapter to reset itself
+ * @scmd:	SCSI cmd to send host reset.
+ */
+static int scsi_try_host_reset(struct scsi_cmnd *scmd)
+{
+	unsigned long flags;
+	int rtn;
+	struct Scsi_Host *host = scmd->device->host;
+	struct scsi_host_template *hostt = host->hostt;
+
+	SCSI_LOG_ERROR_RECOVERY(3,
+		shost_printk(KERN_INFO, host, "Snd Host RST\n"));
+
+	if (!hostt->eh_host_reset_handler)
+		return FAILED;
+
+	rtn = hostt->eh_host_reset_handler(scmd);
+
+	if (rtn == SUCCESS) {
+		if (!hostt->skip_settle_delay)
+			ssleep(HOST_RESET_SETTLE_TIME);
+		spin_lock_irqsave(host->host_lock, flags);
+		scsi_report_bus_reset(host, scmd_channel(scmd));
+		spin_unlock_irqrestore(host->host_lock, flags);
+	}
+
+	return rtn;
+}
+
+/**
+ * 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;
+	struct Scsi_Host *host = scmd->device->host;
+	struct scsi_host_template *hostt = host->hostt;
+
+	SCSI_LOG_ERROR_RECOVERY(3, scmd_printk(KERN_INFO, scmd,
+		"%s: Snd Bus RST\n", __func__));
+
+	if (!hostt->eh_bus_reset_handler)
+		return FAILED;
+
+	rtn = hostt->eh_bus_reset_handler(scmd);
+
+	if (rtn == SUCCESS) {
+		if (!hostt->skip_settle_delay)
+			ssleep(BUS_RESET_SETTLE_TIME);
+		spin_lock_irqsave(host->host_lock, flags);
+		scsi_report_bus_reset(host, scmd_channel(scmd));
+		spin_unlock_irqrestore(host->host_lock, flags);
+	}
+
+	return rtn;
+}
+
+static void __scsi_report_device_reset(struct scsi_device *sdev, void *data)
+{
+	sdev->was_reset = 1;
+	sdev->expecting_cc_ua = 1;
+}
+
+/**
+ * scsi_try_target_reset - Ask host to perform a target reset
+ * @scmd:	SCSI cmd used to send a target reset
+ *
+ * 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_target_reset(struct scsi_cmnd *scmd)
+{
+	unsigned long flags;
+	int rtn;
+	struct Scsi_Host *host = scmd->device->host;
+	struct scsi_host_template *hostt = host->hostt;
+
+	if (!hostt->eh_target_reset_handler)
+		return FAILED;
+
+	rtn = hostt->eh_target_reset_handler(scmd);
+	if (rtn == SUCCESS) {
+		spin_lock_irqsave(host->host_lock, flags);
+		__starget_for_each_device(scsi_target(scmd->device), NULL,
+					  __scsi_report_device_reset);
+		spin_unlock_irqrestore(host->host_lock, flags);
+	}
+
+	return rtn;
+}
+
+/**
+ * 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)
+{
+	int rtn;
+	struct scsi_host_template *hostt = scmd->device->host->hostt;
+
+	if (!hostt->eh_device_reset_handler)
+		return FAILED;
+
+	rtn = hostt->eh_device_reset_handler(scmd);
+	if (rtn == SUCCESS)
+		__scsi_report_device_reset(scmd->device, NULL);
+	return rtn;
+}
+
+/**
+ * scsi_try_to_abort_cmd - Ask host to abort a SCSI command
+ * @hostt:	SCSI driver host template
+ * @scmd:	SCSI cmd used to send a target reset
+ *
+ * Return value:
+ *	SUCCESS, FAILED, or FAST_IO_FAIL
+ *
+ * Notes:
+ *    SUCCESS does not necessarily indicate that the command
+ *    has been aborted; it only indicates that the LLDDs
+ *    has cleared all references to that command.
+ *    LLDDs should return FAILED only if an abort was required
+ *    but could not be executed. LLDDs should return FAST_IO_FAIL
+ *    if the device is temporarily unavailable (eg due to a
+ *    link down on FibreChannel)
+ */
+static int scsi_try_to_abort_cmd(struct scsi_host_template *hostt,
+				 struct scsi_cmnd *scmd)
+{
+	if (!hostt->eh_abort_handler)
+		return FAILED;
+
+	return hostt->eh_abort_handler(scmd);
+}
+
+static void scsi_abort_eh_cmnd(struct scsi_cmnd *scmd)
+{
+	if (scsi_try_to_abort_cmd(scmd->device->host->hostt, scmd) != SUCCESS)
+		if (scsi_try_bus_device_reset(scmd) != SUCCESS)
+			if (scsi_try_target_reset(scmd) != SUCCESS)
+				if (scsi_try_bus_reset(scmd) != SUCCESS)
+					scsi_try_host_reset(scmd);
+}
+
+/**
+ * scsi_eh_prep_cmnd  - Save a scsi command info as part of error recovery
+ * @scmd:       SCSI command structure to hijack
+ * @ses:        structure to save restore information
+ * @cmnd:       CDB to send. Can be NULL if no new cmnd is needed
+ * @cmnd_size:  size in bytes of @cmnd (must be <= BLK_MAX_CDB)
+ * @sense_bytes: size of sense data to copy. or 0 (if != 0 @cmnd is ignored)
+ *
+ * This function is used to save a scsi command information before re-execution
+ * as part of the error recovery process.  If @sense_bytes is 0 the command
+ * sent must be one that does not transfer any data.  If @sense_bytes != 0
+ * @cmnd is ignored and this functions sets up a REQUEST_SENSE command
+ * and cmnd buffers to read @sense_bytes into @scmd->sense_buffer.
+ */
+void scsi_eh_prep_cmnd(struct scsi_cmnd *scmd, struct scsi_eh_save *ses,
+			unsigned char *cmnd, int cmnd_size, unsigned sense_bytes)
+{
+	struct scsi_device *sdev = scmd->device;
+
+	/*
+	 * We need saved copies of a number of fields - this is because
+	 * error handling may need to overwrite these with different values
+	 * to run different commands, and once error handling is complete,
+	 * we will need to restore these values prior to running the actual
+	 * command.
+	 */
+	ses->cmd_len = scmd->cmd_len;
+	ses->cmnd = scmd->cmnd;
+	ses->data_direction = scmd->sc_data_direction;
+	ses->sdb = scmd->sdb;
+	ses->next_rq = scmd->request->next_rq;
+	ses->result = scmd->result;
+	ses->resid_len = scmd->req.resid_len;
+	ses->underflow = scmd->underflow;
+	ses->prot_op = scmd->prot_op;
+	ses->eh_eflags = scmd->eh_eflags;
+
+	scmd->prot_op = SCSI_PROT_NORMAL;
+	scmd->eh_eflags = 0;
+	scmd->cmnd = ses->eh_cmnd;
+	memset(scmd->cmnd, 0, BLK_MAX_CDB);
+	memset(&scmd->sdb, 0, sizeof(scmd->sdb));
+	scmd->request->next_rq = NULL;
+	scmd->result = 0;
+	scmd->req.resid_len = 0;
+
+	if (sense_bytes) {
+		scmd->sdb.length = min_t(unsigned, SCSI_SENSE_BUFFERSIZE,
+					 sense_bytes);
+		sg_init_one(&ses->sense_sgl, scmd->sense_buffer,
+			    scmd->sdb.length);
+		scmd->sdb.table.sgl = &ses->sense_sgl;
+		scmd->sc_data_direction = DMA_FROM_DEVICE;
+		scmd->sdb.table.nents = scmd->sdb.table.orig_nents = 1;
+		scmd->cmnd[0] = REQUEST_SENSE;
+		scmd->cmnd[4] = scmd->sdb.length;
+		scmd->cmd_len = COMMAND_SIZE(scmd->cmnd[0]);
+	} else {
+		scmd->sc_data_direction = DMA_NONE;
+		if (cmnd) {
+			BUG_ON(cmnd_size > BLK_MAX_CDB);
+			memcpy(scmd->cmnd, cmnd, cmnd_size);
+			scmd->cmd_len = COMMAND_SIZE(scmd->cmnd[0]);
+		}
+	}
+
+	scmd->underflow = 0;
+
+	if (sdev->scsi_level <= SCSI_2 && sdev->scsi_level != SCSI_UNKNOWN)
+		scmd->cmnd[1] = (scmd->cmnd[1] & 0x1f) |
+			(sdev->lun << 5 & 0xe0);
+
+	/*
+	 * Zero the sense buffer.  The scsi spec mandates that any
+	 * untransferred sense data should be interpreted as being zero.
+	 */
+	memset(scmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);
+}
+EXPORT_SYMBOL(scsi_eh_prep_cmnd);
+
+/**
+ * scsi_eh_restore_cmnd  - Restore a scsi command info as part of error recovery
+ * @scmd:       SCSI command structure to restore
+ * @ses:        saved information from a coresponding call to scsi_eh_prep_cmnd
+ *
+ * Undo any damage done by above scsi_eh_prep_cmnd().
+ */
+void scsi_eh_restore_cmnd(struct scsi_cmnd* scmd, struct scsi_eh_save *ses)
+{
+	/*
+	 * Restore original data
+	 */
+	scmd->cmd_len = ses->cmd_len;
+	scmd->cmnd = ses->cmnd;
+	scmd->sc_data_direction = ses->data_direction;
+	scmd->sdb = ses->sdb;
+	scmd->request->next_rq = ses->next_rq;
+	scmd->result = ses->result;
+	scmd->req.resid_len = ses->resid_len;
+	scmd->underflow = ses->underflow;
+	scmd->prot_op = ses->prot_op;
+	scmd->eh_eflags = ses->eh_eflags;
+}
+EXPORT_SYMBOL(scsi_eh_restore_cmnd);
+
+/**
+ * scsi_send_eh_cmnd  - submit a scsi command as part of error recovery
+ * @scmd:       SCSI command structure to hijack
+ * @cmnd:       CDB to send
+ * @cmnd_size:  size in bytes of @cmnd
+ * @timeout:    timeout for this request
+ * @sense_bytes: size of sense data to copy or 0
+ *
+ * This function is used to send a scsi command down to a target device
+ * as part of the error recovery process. See also scsi_eh_prep_cmnd() above.
+ *
+ * Return value:
+ *    SUCCESS or FAILED or NEEDS_RETRY
+ */
+static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd,
+			     int cmnd_size, int timeout, unsigned sense_bytes)
+{
+	struct scsi_device *sdev = scmd->device;
+	struct Scsi_Host *shost = sdev->host;
+	DECLARE_COMPLETION_ONSTACK(done);
+	unsigned long timeleft = timeout;
+	struct scsi_eh_save ses;
+	const unsigned long stall_for = msecs_to_jiffies(100);
+	int rtn;
+
+retry:
+	scsi_eh_prep_cmnd(scmd, &ses, cmnd, cmnd_size, sense_bytes);
+	shost->eh_action = &done;
+
+	scsi_log_send(scmd);
+	scmd->scsi_done = scsi_eh_done;
+	rtn = shost->hostt->queuecommand(shost, scmd);
+	if (rtn) {
+		if (timeleft > stall_for) {
+			scsi_eh_restore_cmnd(scmd, &ses);
+			timeleft -= stall_for;
+			msleep(jiffies_to_msecs(stall_for));
+			goto retry;
+		}
+		/* signal not to enter either branch of the if () below */
+		timeleft = 0;
+		rtn = FAILED;
+	} else {
+		timeleft = wait_for_completion_timeout(&done, timeout);
+		rtn = SUCCESS;
+	}
+
+	shost->eh_action = NULL;
+
+	scsi_log_completion(scmd, rtn);
+
+	SCSI_LOG_ERROR_RECOVERY(3, scmd_printk(KERN_INFO, scmd,
+			"%s timeleft: %ld\n",
+			__func__, timeleft));
+
+	/*
+	 * If there is time left scsi_eh_done got called, and we will examine
+	 * the actual status codes to see whether the command actually did
+	 * complete normally, else if we have a zero return and no time left,
+	 * the command must still be pending, so abort it and return FAILED.
+	 * If we never actually managed to issue the command, because
+	 * ->queuecommand() kept returning non zero, use the rtn = FAILED
+	 * value above (so don't execute either branch of the if)
+	 */
+	if (timeleft) {
+		rtn = scsi_eh_completed_normally(scmd);
+		SCSI_LOG_ERROR_RECOVERY(3, scmd_printk(KERN_INFO, scmd,
+			"%s: scsi_eh_completed_normally %x\n", __func__, rtn));
+
+		switch (rtn) {
+		case SUCCESS:
+		case NEEDS_RETRY:
+		case FAILED:
+			break;
+		case ADD_TO_MLQUEUE:
+			rtn = NEEDS_RETRY;
+			break;
+		default:
+			rtn = FAILED;
+			break;
+		}
+	} else if (rtn != FAILED) {
+		scsi_abort_eh_cmnd(scmd);
+		rtn = FAILED;
+	}
+
+	scsi_eh_restore_cmnd(scmd, &ses);
+
+	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)
+{
+	return scsi_send_eh_cmnd(scmd, NULL, 0, scmd->device->eh_timeout, ~0);
+}
+
+static int scsi_eh_action(struct scsi_cmnd *scmd, int rtn)
+{
+	if (!blk_rq_is_passthrough(scmd->request)) {
+		struct scsi_driver *sdrv = scsi_cmd_to_driver(scmd);
+		if (sdrv->eh_action)
+			rtn = sdrv->eh_action(scmd, rtn);
+	}
+	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.
+ */
+void scsi_eh_finish_cmd(struct scsi_cmnd *scmd, struct list_head *done_q)
+{
+	list_move_tail(&scmd->eh_entry, done_q);
+}
+EXPORT_SYMBOL(scsi_eh_finish_cmd);
+
+/**
+ * scsi_eh_get_sense - Get device sense data.
+ * @work_q:	Queue of commands to process.
+ * @done_q:	Queue of processed 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, 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.
+ */
+int scsi_eh_get_sense(struct list_head *work_q,
+		      struct list_head *done_q)
+{
+	struct scsi_cmnd *scmd, *next;
+	struct Scsi_Host *shost;
+	int rtn;
+
+	/*
+	 * If SCSI_EH_ABORT_SCHEDULED has been set, it is timeout IO,
+	 * should not get sense.
+	 */
+	list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
+		if ((scmd->eh_eflags & SCSI_EH_ABORT_SCHEDULED) ||
+		    SCSI_SENSE_VALID(scmd))
+			continue;
+
+		shost = scmd->device->host;
+		if (scsi_host_eh_past_deadline(shost)) {
+			SCSI_LOG_ERROR_RECOVERY(3,
+				scmd_printk(KERN_INFO, scmd,
+					    "%s: skip request sense, past eh deadline\n",
+					     current->comm));
+			break;
+		}
+		if (status_byte(scmd->result) != CHECK_CONDITION)
+			/*
+			 * don't request sense if there's no check condition
+			 * status because the error we're processing isn't one
+			 * that has a sense code (and some devices get
+			 * confused by sense requests out of the blue)
+			 */
+			continue;
+
+		SCSI_LOG_ERROR_RECOVERY(2, scmd_printk(KERN_INFO, scmd,
+						  "%s: requesting sense\n",
+						  current->comm));
+		rtn = scsi_request_sense(scmd);
+		if (rtn != SUCCESS)
+			continue;
+
+		SCSI_LOG_ERROR_RECOVERY(3, scmd_printk(KERN_INFO, scmd,
+			"sense requested, result %x\n", scmd->result));
+		SCSI_LOG_ERROR_RECOVERY(3, scsi_print_sense(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);
+}
+EXPORT_SYMBOL_GPL(scsi_eh_get_sense);
+
+/**
+ * scsi_eh_tur - Send TUR to device.
+ * @scmd:	&scsi_cmnd 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:
+	rtn = scsi_send_eh_cmnd(scmd, tur_command, 6,
+				scmd->device->eh_timeout, 0);
+
+	SCSI_LOG_ERROR_RECOVERY(3, scmd_printk(KERN_INFO, scmd,
+		"%s return: %x\n", __func__, rtn));
+
+	switch (rtn) {
+	case NEEDS_RETRY:
+		if (retry_cnt--)
+			goto retry_tur;
+		/*FALLTHRU*/
+	case SUCCESS:
+		return 0;
+	default:
+		return 1;
+	}
+}
+
+/**
+ * scsi_eh_test_devices - check if devices are responding from error recovery.
+ * @cmd_list:	scsi commands in error recovery.
+ * @work_q:	queue for commands which still need more error recovery
+ * @done_q:	queue for commands which are finished
+ * @try_stu:	boolean on if a STU command should be tried in addition to TUR.
+ *
+ * Decription:
+ *    Tests if devices are in a working state.  Commands to devices now in
+ *    a working state are sent to the done_q while commands to devices which
+ *    are still failing to respond are returned to the work_q for more
+ *    processing.
+ **/
+static int scsi_eh_test_devices(struct list_head *cmd_list,
+				struct list_head *work_q,
+				struct list_head *done_q, int try_stu)
+{
+	struct scsi_cmnd *scmd, *next;
+	struct scsi_device *sdev;
+	int finish_cmds;
+
+	while (!list_empty(cmd_list)) {
+		scmd = list_entry(cmd_list->next, struct scsi_cmnd, eh_entry);
+		sdev = scmd->device;
+
+		if (!try_stu) {
+			if (scsi_host_eh_past_deadline(sdev->host)) {
+				/* Push items back onto work_q */
+				list_splice_init(cmd_list, work_q);
+				SCSI_LOG_ERROR_RECOVERY(3,
+					sdev_printk(KERN_INFO, sdev,
+						    "%s: skip test device, past eh deadline",
+						    current->comm));
+				break;
+			}
+		}
+
+		finish_cmds = !scsi_device_online(scmd->device) ||
+			(try_stu && !scsi_eh_try_stu(scmd) &&
+			 !scsi_eh_tur(scmd)) ||
+			!scsi_eh_tur(scmd);
+
+		list_for_each_entry_safe(scmd, next, cmd_list, eh_entry)
+			if (scmd->device == sdev) {
+				if (finish_cmds &&
+				    (try_stu ||
+				     scsi_eh_action(scmd, SUCCESS) == SUCCESS))
+					scsi_eh_finish_cmd(scmd, done_q);
+				else
+					list_move_tail(&scmd->eh_entry, work_q);
+			}
+	}
+	return list_empty(work_q);
+}
+
+/**
+ * scsi_eh_try_stu - Send START_UNIT to device.
+ * @scmd:	&scsi_cmnd 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};
+
+	if (scmd->device->allow_restart) {
+		int i, rtn = NEEDS_RETRY;
+
+		for (i = 0; rtn == NEEDS_RETRY && i < 2; i++)
+			rtn = scsi_send_eh_cmnd(scmd, stu_command, 6, scmd->device->request_queue->rq_timeout, 0);
+
+		if (rtn == SUCCESS)
+			return 0;
+	}
+
+	return 1;
+}
+
+ /**
+ * scsi_eh_stu - send START_UNIT if needed
+ * @shost:	&scsi host being recovered.
+ * @work_q:	&list_head for pending commands.
+ * @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 scsi_cmnd *scmd, *stu_scmd, *next;
+	struct scsi_device *sdev;
+
+	shost_for_each_device(sdev, shost) {
+		if (scsi_host_eh_past_deadline(shost)) {
+			SCSI_LOG_ERROR_RECOVERY(3,
+				sdev_printk(KERN_INFO, sdev,
+					    "%s: skip START_UNIT, past eh deadline\n",
+					    current->comm));
+			break;
+		}
+		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,
+			sdev_printk(KERN_INFO, sdev,
+				     "%s: Sending START_UNIT\n",
+				    current->comm));
+
+		if (!scsi_eh_try_stu(stu_scmd)) {
+			if (!scsi_device_online(sdev) ||
+			    !scsi_eh_tur(stu_scmd)) {
+				list_for_each_entry_safe(scmd, next,
+							  work_q, eh_entry) {
+					if (scmd->device == sdev &&
+					    scsi_eh_action(scmd, SUCCESS) == SUCCESS)
+						scsi_eh_finish_cmd(scmd, done_q);
+				}
+			}
+		} else {
+			SCSI_LOG_ERROR_RECOVERY(3,
+				sdev_printk(KERN_INFO, sdev,
+					    "%s: START_UNIT failed\n",
+					    current->comm));
+		}
+	}
+
+	return list_empty(work_q);
+}
+
+
+/**
+ * scsi_eh_bus_device_reset - send bdr if needed
+ * @shost:	scsi host being recovered.
+ * @work_q:	&list_head for pending commands.
+ * @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 scsi_cmnd *scmd, *bdr_scmd, *next;
+	struct scsi_device *sdev;
+	int rtn;
+
+	shost_for_each_device(sdev, shost) {
+		if (scsi_host_eh_past_deadline(shost)) {
+			SCSI_LOG_ERROR_RECOVERY(3,
+				sdev_printk(KERN_INFO, sdev,
+					    "%s: skip BDR, past eh deadline\n",
+					     current->comm));
+			break;
+		}
+		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,
+			sdev_printk(KERN_INFO, sdev,
+				     "%s: Sending BDR\n", current->comm));
+		rtn = scsi_try_bus_device_reset(bdr_scmd);
+		if (rtn == SUCCESS || rtn == FAST_IO_FAIL) {
+			if (!scsi_device_online(sdev) ||
+			    rtn == FAST_IO_FAIL ||
+			    !scsi_eh_tur(bdr_scmd)) {
+				list_for_each_entry_safe(scmd, next,
+							 work_q, eh_entry) {
+					if (scmd->device == sdev &&
+					    scsi_eh_action(scmd, rtn) != FAILED)
+						scsi_eh_finish_cmd(scmd,
+								   done_q);
+				}
+			}
+		} else {
+			SCSI_LOG_ERROR_RECOVERY(3,
+				sdev_printk(KERN_INFO, sdev,
+					    "%s: BDR failed\n", current->comm));
+		}
+	}
+
+	return list_empty(work_q);
+}
+
+/**
+ * scsi_eh_target_reset - send target reset if needed
+ * @shost:	scsi host being recovered.
+ * @work_q:	&list_head for pending commands.
+ * @done_q:	&list_head for processed commands.
+ *
+ * Notes:
+ *    Try a target reset.
+ */
+static int scsi_eh_target_reset(struct Scsi_Host *shost,
+				struct list_head *work_q,
+				struct list_head *done_q)
+{
+	LIST_HEAD(tmp_list);
+	LIST_HEAD(check_list);
+
+	list_splice_init(work_q, &tmp_list);
+
+	while (!list_empty(&tmp_list)) {
+		struct scsi_cmnd *next, *scmd;
+		int rtn;
+		unsigned int id;
+
+		if (scsi_host_eh_past_deadline(shost)) {
+			/* push back on work queue for further processing */
+			list_splice_init(&check_list, work_q);
+			list_splice_init(&tmp_list, work_q);
+			SCSI_LOG_ERROR_RECOVERY(3,
+				shost_printk(KERN_INFO, shost,
+					    "%s: Skip target reset, past eh deadline\n",
+					     current->comm));
+			return list_empty(work_q);
+		}
+
+		scmd = list_entry(tmp_list.next, struct scsi_cmnd, eh_entry);
+		id = scmd_id(scmd);
+
+		SCSI_LOG_ERROR_RECOVERY(3,
+			shost_printk(KERN_INFO, shost,
+				     "%s: Sending target reset to target %d\n",
+				     current->comm, id));
+		rtn = scsi_try_target_reset(scmd);
+		if (rtn != SUCCESS && rtn != FAST_IO_FAIL)
+			SCSI_LOG_ERROR_RECOVERY(3,
+				shost_printk(KERN_INFO, shost,
+					     "%s: Target reset failed"
+					     " target: %d\n",
+					     current->comm, id));
+		list_for_each_entry_safe(scmd, next, &tmp_list, eh_entry) {
+			if (scmd_id(scmd) != id)
+				continue;
+
+			if (rtn == SUCCESS)
+				list_move_tail(&scmd->eh_entry, &check_list);
+			else if (rtn == FAST_IO_FAIL)
+				scsi_eh_finish_cmd(scmd, done_q);
+			else
+				/* push back on work queue for further processing */
+				list_move(&scmd->eh_entry, work_q);
+		}
+	}
+
+	return scsi_eh_test_devices(&check_list, work_q, done_q, 0);
+}
+
+/**
+ * scsi_eh_bus_reset - send a bus reset
+ * @shost:	&scsi host being recovered.
+ * @work_q:	&list_head for pending commands.
+ * @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 scsi_cmnd *scmd, *chan_scmd, *next;
+	LIST_HEAD(check_list);
+	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++) {
+		if (scsi_host_eh_past_deadline(shost)) {
+			list_splice_init(&check_list, work_q);
+			SCSI_LOG_ERROR_RECOVERY(3,
+				shost_printk(KERN_INFO, shost,
+					    "%s: skip BRST, past eh deadline\n",
+					     current->comm));
+			return list_empty(work_q);
+		}
+
+		chan_scmd = NULL;
+		list_for_each_entry(scmd, work_q, eh_entry) {
+			if (channel == scmd_channel(scmd)) {
+				chan_scmd = scmd;
+				break;
+				/*
+				 * FIXME add back in some support for
+				 * soft_reset devices.
+				 */
+			}
+		}
+
+		if (!chan_scmd)
+			continue;
+		SCSI_LOG_ERROR_RECOVERY(3,
+			shost_printk(KERN_INFO, shost,
+				     "%s: Sending BRST chan: %d\n",
+				     current->comm, channel));
+		rtn = scsi_try_bus_reset(chan_scmd);
+		if (rtn == SUCCESS || rtn == FAST_IO_FAIL) {
+			list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
+				if (channel == scmd_channel(scmd)) {
+					if (rtn == FAST_IO_FAIL)
+						scsi_eh_finish_cmd(scmd,
+								   done_q);
+					else
+						list_move_tail(&scmd->eh_entry,
+							       &check_list);
+				}
+			}
+		} else {
+			SCSI_LOG_ERROR_RECOVERY(3,
+				shost_printk(KERN_INFO, shost,
+					     "%s: BRST failed chan: %d\n",
+					     current->comm, channel));
+		}
+	}
+	return scsi_eh_test_devices(&check_list, work_q, done_q, 0);
+}
+
+/**
+ * scsi_eh_host_reset - send a host reset
+ * @shost:	host to be reset.
+ * @work_q:	&list_head for pending commands.
+ * @done_q:	&list_head for processed commands.
+ */
+static int scsi_eh_host_reset(struct Scsi_Host *shost,
+			      struct list_head *work_q,
+			      struct list_head *done_q)
+{
+	struct scsi_cmnd *scmd, *next;
+	LIST_HEAD(check_list);
+	int rtn;
+
+	if (!list_empty(work_q)) {
+		scmd = list_entry(work_q->next,
+				  struct scsi_cmnd, eh_entry);
+
+		SCSI_LOG_ERROR_RECOVERY(3,
+			shost_printk(KERN_INFO, shost,
+				     "%s: Sending HRST\n",
+				     current->comm));
+
+		rtn = scsi_try_host_reset(scmd);
+		if (rtn == SUCCESS) {
+			list_splice_init(work_q, &check_list);
+		} else if (rtn == FAST_IO_FAIL) {
+			list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
+					scsi_eh_finish_cmd(scmd, done_q);
+			}
+		} else {
+			SCSI_LOG_ERROR_RECOVERY(3,
+				shost_printk(KERN_INFO, shost,
+					     "%s: HRST failed\n",
+					     current->comm));
+		}
+	}
+	return scsi_eh_test_devices(&check_list, work_q, done_q, 1);
+}
+
+/**
+ * scsi_eh_offline_sdevs - offline scsi devices that fail to recover
+ * @work_q:	&list_head for pending 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 scsi_cmnd *scmd, *next;
+	struct scsi_device *sdev;
+
+	list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
+		sdev_printk(KERN_INFO, scmd->device, "Device offlined - "
+			    "not ready after error recovery\n");
+		sdev = scmd->device;
+
+		mutex_lock(&sdev->state_mutex);
+		scsi_device_set_state(sdev, SDEV_OFFLINE);
+		mutex_unlock(&sdev->state_mutex);
+
+		scsi_eh_finish_cmd(scmd, done_q);
+	}
+	return;
+}
+
+/**
+ * scsi_noretry_cmd - determine if command should be failed fast
+ * @scmd:	SCSI cmd to examine.
+ */
+int scsi_noretry_cmd(struct scsi_cmnd *scmd)
+{
+	switch (host_byte(scmd->result)) {
+	case DID_OK:
+		break;
+	case DID_TIME_OUT:
+		goto check_type;
+	case DID_BUS_BUSY:
+		return (scmd->request->cmd_flags & REQ_FAILFAST_TRANSPORT);
+	case DID_PARITY:
+		return (scmd->request->cmd_flags & REQ_FAILFAST_DEV);
+	case DID_ERROR:
+		if (msg_byte(scmd->result) == COMMAND_COMPLETE &&
+		    status_byte(scmd->result) == RESERVATION_CONFLICT)
+			return 0;
+		/* fall through */
+	case DID_SOFT_ERROR:
+		return (scmd->request->cmd_flags & REQ_FAILFAST_DRIVER);
+	}
+
+	if (status_byte(scmd->result) != CHECK_CONDITION)
+		return 0;
+
+check_type:
+	/*
+	 * assume caller has checked sense and determined
+	 * the check condition was retryable.
+	 */
+	if (scmd->request->cmd_flags & REQ_FAILFAST_DEV ||
+	    blk_rq_is_passthrough(scmd->request))
+		return 1;
+	else
+		return 0;
+}
+
+/**
+ * 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, scmd_printk(KERN_INFO, scmd,
+			"%s: device offline - report as SUCCESS\n", __func__));
+		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_ABORT:
+		if (scmd->eh_eflags & SCSI_EH_ABORT_SCHEDULED) {
+			set_host_byte(scmd, DID_TIME_OUT);
+			return SUCCESS;
+		}
+		/* FALLTHROUGH */
+	case DID_NO_CONNECT:
+	case DID_BAD_TARGET:
+		/*
+		 * 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;
+	case DID_SOFT_ERROR:
+		/*
+		 * 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)
+		 */
+		goto maybe_retry;
+	case DID_IMM_RETRY:
+		return NEEDS_RETRY;
+
+	case DID_REQUEUE:
+		return ADD_TO_MLQUEUE;
+	case DID_TRANSPORT_DISRUPTED:
+		/*
+		 * LLD/transport was disrupted during processing of the IO.
+		 * The transport class is now blocked/blocking,
+		 * and the transport will decide what to do with the IO
+		 * based on its timers and recovery capablilities if
+		 * there are enough retries.
+		 */
+		goto maybe_retry;
+	case DID_TRANSPORT_FAILFAST:
+		/*
+		 * The transport decided to failfast the IO (most likely
+		 * the fast io fail tmo fired), so send IO directly upwards.
+		 */
+		return SUCCESS;
+	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:
+		scsi_handle_queue_full(scmd->device);
+		/*
+		 * the case of trying to send too many commands to a
+		 * tagged queueing device.
+		 */
+		/* FALLTHROUGH */
+	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:
+		if (scmd->cmnd[0] == REPORT_LUNS)
+			scmd->device->sdev_target->expecting_lun_change = 0;
+		scsi_handle_queue_ramp_up(scmd->device);
+		/* FALLTHROUGH */
+	case COMMAND_TERMINATED:
+		return SUCCESS;
+	case TASK_ABORTED:
+		goto maybe_retry;
+	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:
+		sdev_printk(KERN_INFO, scmd->device,
+			    "reservation conflict\n");
+		set_host_byte(scmd, DID_NEXUS_FAILURE);
+		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
+	    && !scsi_noretry_cmd(scmd)) {
+		return NEEDS_RETRY;
+	} else {
+		/*
+		 * no more retries - report this one back to upper level.
+		 */
+		return SUCCESS;
+	}
+}
+
+static void eh_lock_door_done(struct request *req, blk_status_t status)
+{
+	__blk_put_request(req->q, req);
+}
+
+/**
+ * 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.
+ *
+ * Notes:
+ * 	We queue up an asynchronous "ALLOW MEDIUM REMOVAL" request on the
+ * 	head of the devices request queue, and continue.
+ */
+static void scsi_eh_lock_door(struct scsi_device *sdev)
+{
+	struct request *req;
+	struct scsi_request *rq;
+
+	req = blk_get_request(sdev->request_queue, REQ_OP_SCSI_IN, 0);
+	if (IS_ERR(req))
+		return;
+	rq = scsi_req(req);
+
+	rq->cmd[0] = ALLOW_MEDIUM_REMOVAL;
+	rq->cmd[1] = 0;
+	rq->cmd[2] = 0;
+	rq->cmd[3] = 0;
+	rq->cmd[4] = SCSI_REMOVAL_PREVENT;
+	rq->cmd[5] = 0;
+	rq->cmd_len = COMMAND_SIZE(rq->cmd[0]);
+
+	req->rq_flags |= RQF_QUIET;
+	req->timeout = 10 * HZ;
+	rq->retries = 5;
+
+	blk_execute_rq_nowait(req->q, NULL, req, 1, eh_lock_door_done);
+}
+
+/**
+ * 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;
+	unsigned long flags;
+
+	/*
+	 * 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->was_reset && sdev->locked) {
+			scsi_eh_lock_door(sdev);
+			sdev->was_reset = 0;
+		}
+	}
+
+	/*
+	 * 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,
+		shost_printk(KERN_INFO, shost, "waking up host to restart\n"));
+
+	spin_lock_irqsave(shost->host_lock, flags);
+	if (scsi_host_set_state(shost, SHOST_RUNNING))
+		if (scsi_host_set_state(shost, SHOST_CANCEL))
+			BUG_ON(scsi_host_set_state(shost, SHOST_DEL));
+	spin_unlock_irqrestore(shost->host_lock, flags);
+
+	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);
+
+	/*
+	 * if eh is active and host_eh_scheduled is pending we need to re-run
+	 * recovery.  we do this check after scsi_run_host_queues() to allow
+	 * everything pent up since the last eh run a chance to make forward
+	 * progress before we sync again.  Either we'll immediately re-run
+	 * recovery or scsi_device_unbusy() will wake us again when these
+	 * pending commands complete.
+	 */
+	spin_lock_irqsave(shost->host_lock, flags);
+	if (shost->host_eh_scheduled)
+		if (scsi_host_set_state(shost, SHOST_RECOVERY))
+			WARN_ON(scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY));
+	spin_unlock_irqrestore(shost->host_lock, flags);
+}
+
+/**
+ * scsi_eh_ready_devs - check device ready state and recover if not.
+ * @shost:	host to be recovered.
+ * @work_q:	&list_head for pending commands.
+ * @done_q:	&list_head for processed commands.
+ */
+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_target_reset(shost, work_q, done_q))
+				if (!scsi_eh_bus_reset(shost, work_q, done_q))
+					if (!scsi_eh_host_reset(shost, work_q, done_q))
+						scsi_eh_offline_sdevs(work_q,
+								      done_q);
+}
+EXPORT_SYMBOL_GPL(scsi_eh_ready_devs);
+
+/**
+ * scsi_eh_flush_done_q - finish processed commands or retry them.
+ * @done_q:	list_head of processed commands.
+ */
+void scsi_eh_flush_done_q(struct list_head *done_q)
+{
+	struct scsi_cmnd *scmd, *next;
+
+	list_for_each_entry_safe(scmd, next, done_q, eh_entry) {
+		list_del_init(&scmd->eh_entry);
+		if (scsi_device_online(scmd->device) &&
+		    !scsi_noretry_cmd(scmd) &&
+		    (++scmd->retries <= scmd->allowed)) {
+			SCSI_LOG_ERROR_RECOVERY(3,
+				scmd_printk(KERN_INFO, scmd,
+					     "%s: flush retry cmd\n",
+					     current->comm));
+				scsi_queue_insert(scmd, SCSI_MLQUEUE_EH_RETRY);
+		} else {
+			/*
+			 * If just we got sense for the device (called
+			 * scsi_eh_get_sense), scmd->result is already
+			 * set, do not set DRIVER_TIMEOUT.
+			 */
+			if (!scmd->result)
+				scmd->result |= (DRIVER_TIMEOUT << 24);
+			SCSI_LOG_ERROR_RECOVERY(3,
+				scmd_printk(KERN_INFO, scmd,
+					     "%s: flush finish cmd\n",
+					     current->comm));
+			scsi_finish_command(scmd);
+		}
+	}
+}
+EXPORT_SYMBOL(scsi_eh_flush_done_q);
+
+/**
+ * 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))
+		scsi_eh_ready_devs(shost, &eh_work_q, &eh_done_q);
+
+	spin_lock_irqsave(shost->host_lock, flags);
+	if (shost->eh_deadline != -1)
+		shost->last_reset = 0;
+	spin_unlock_irqrestore(shost->host_lock, flags);
+	scsi_eh_flush_done_q(&eh_done_q);
+}
+
+/**
+ * scsi_error_handler - SCSI error handler thread
+ * @data:	Host for which we are running.
+ *
+ * Notes:
+ *    This is the main error handling loop.  This is run as a kernel thread
+ *    for every SCSI host and handles all error handling activity.
+ */
+int scsi_error_handler(void *data)
+{
+	struct Scsi_Host *shost = data;
+
+	/*
+	 * We use TASK_INTERRUPTIBLE so that the thread is not
+	 * counted against the load average as a running process.
+	 * We never actually get interrupted because kthread_run
+	 * disables signal delivery for the created thread.
+	 */
+	while (true) {
+		/*
+		 * The sequence in kthread_stop() sets the stop flag first
+		 * then wakes the process.  To avoid missed wakeups, the task
+		 * should always be in a non running state before the stop
+		 * flag is checked
+		 */
+		set_current_state(TASK_INTERRUPTIBLE);
+		if (kthread_should_stop())
+			break;
+
+		if ((shost->host_failed == 0 && shost->host_eh_scheduled == 0) ||
+		    shost->host_failed != scsi_host_busy(shost)) {
+			SCSI_LOG_ERROR_RECOVERY(1,
+				shost_printk(KERN_INFO, shost,
+					     "scsi_eh_%d: sleeping\n",
+					     shost->host_no));
+			schedule();
+			continue;
+		}
+
+		__set_current_state(TASK_RUNNING);
+		SCSI_LOG_ERROR_RECOVERY(1,
+			shost_printk(KERN_INFO, shost,
+				     "scsi_eh_%d: waking up %d/%d/%d\n",
+				     shost->host_no, shost->host_eh_scheduled,
+				     shost->host_failed,
+				     scsi_host_busy(shost)));
+
+		/*
+		 * 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->eh_noresume && scsi_autopm_get_host(shost) != 0) {
+			SCSI_LOG_ERROR_RECOVERY(1,
+				shost_printk(KERN_ERR, shost,
+					     "scsi_eh_%d: unable to autoresume\n",
+					     shost->host_no));
+			continue;
+		}
+
+		if (shost->transportt->eh_strategy_handler)
+			shost->transportt->eh_strategy_handler(shost);
+		else
+			scsi_unjam_host(shost);
+
+		/* All scmds have been handled */
+		shost->host_failed = 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);
+		if (!shost->eh_noresume)
+			scsi_autopm_put_host(shost);
+	}
+	__set_current_state(TASK_RUNNING);
+
+	SCSI_LOG_ERROR_RECOVERY(1,
+		shost_printk(KERN_INFO, shost,
+			     "Error handler scsi_eh_%d exiting\n",
+			     shost->host_no));
+	shost->ehandler = NULL;
+	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))
+			__scsi_report_device_reset(sdev, NULL);
+	}
+}
+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(sdev) &&
+		    target == sdev_id(sdev))
+			__scsi_report_device_reset(sdev, NULL);
+	}
+}
+EXPORT_SYMBOL(scsi_report_device_reset);
+
+static void
+scsi_reset_provider_done_command(struct scsi_cmnd *scmd)
+{
+}
+
+/**
+ * scsi_ioctl_reset: explicitly reset a host/bus/target/device
+ * @dev:	scsi_device to operate on
+ * @arg:	reset type (see sg.h)
+ */
+int
+scsi_ioctl_reset(struct scsi_device *dev, int __user *arg)
+{
+	struct scsi_cmnd *scmd;
+	struct Scsi_Host *shost = dev->host;
+	struct request *rq;
+	unsigned long flags;
+	int error = 0, rtn, val;
+
+	if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SYS_RAWIO))
+		return -EACCES;
+
+	error = get_user(val, arg);
+	if (error)
+		return error;
+
+	if (scsi_autopm_get_host(shost) < 0)
+		return -EIO;
+
+	error = -EIO;
+	rq = kzalloc(sizeof(struct request) + sizeof(struct scsi_cmnd) +
+			shost->hostt->cmd_size, GFP_KERNEL);
+	if (!rq)
+		goto out_put_autopm_host;
+	blk_rq_init(NULL, rq);
+
+	scmd = (struct scsi_cmnd *)(rq + 1);
+	scsi_init_command(dev, scmd);
+	scmd->request = rq;
+	scmd->cmnd = scsi_req(rq)->cmd;
+
+	scmd->scsi_done		= scsi_reset_provider_done_command;
+	memset(&scmd->sdb, 0, sizeof(scmd->sdb));
+
+	scmd->cmd_len			= 0;
+
+	scmd->sc_data_direction		= DMA_BIDIRECTIONAL;
+
+	spin_lock_irqsave(shost->host_lock, flags);
+	shost->tmf_in_progress = 1;
+	spin_unlock_irqrestore(shost->host_lock, flags);
+
+	switch (val & ~SG_SCSI_RESET_NO_ESCALATE) {
+	case SG_SCSI_RESET_NOTHING:
+		rtn = SUCCESS;
+		break;
+	case SG_SCSI_RESET_DEVICE:
+		rtn = scsi_try_bus_device_reset(scmd);
+		if (rtn == SUCCESS || (val & SG_SCSI_RESET_NO_ESCALATE))
+			break;
+		/* FALLTHROUGH */
+	case SG_SCSI_RESET_TARGET:
+		rtn = scsi_try_target_reset(scmd);
+		if (rtn == SUCCESS || (val & SG_SCSI_RESET_NO_ESCALATE))
+			break;
+		/* FALLTHROUGH */
+	case SG_SCSI_RESET_BUS:
+		rtn = scsi_try_bus_reset(scmd);
+		if (rtn == SUCCESS || (val & SG_SCSI_RESET_NO_ESCALATE))
+			break;
+		/* FALLTHROUGH */
+	case SG_SCSI_RESET_HOST:
+		rtn = scsi_try_host_reset(scmd);
+		if (rtn == SUCCESS)
+			break;
+		/* FALLTHROUGH */
+	default:
+		rtn = FAILED;
+		break;
+	}
+
+	error = (rtn == SUCCESS) ? 0 : -EIO;
+
+	spin_lock_irqsave(shost->host_lock, flags);
+	shost->tmf_in_progress = 0;
+	spin_unlock_irqrestore(shost->host_lock, flags);
+
+	/*
+	 * be sure to wake up anyone who was sleeping or had their queue
+	 * suspended while we performed the TMF.
+	 */
+	SCSI_LOG_ERROR_RECOVERY(3,
+		shost_printk(KERN_INFO, shost,
+			     "waking up host to restart after TMF\n"));
+
+	wake_up(&shost->host_wait);
+	scsi_run_host_queues(shost);
+
+	scsi_put_command(scmd);
+	kfree(rq);
+
+out_put_autopm_host:
+	scsi_autopm_put_host(shost);
+	return error;
+}
+EXPORT_SYMBOL(scsi_ioctl_reset);
+
+bool scsi_command_normalize_sense(const struct scsi_cmnd *cmd,
+				  struct scsi_sense_hdr *sshdr)
+{
+	return scsi_normalize_sense(cmd->sense_buffer,
+			SCSI_SENSE_BUFFERSIZE, sshdr);
+}
+EXPORT_SYMBOL(scsi_command_normalize_sense);
+
+/**
+ * scsi_get_sense_info_fld - 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:
+ *	true if information field found, false if not found.
+ */
+bool scsi_get_sense_info_fld(const u8 *sense_buffer, int sb_len,
+			     u64 *info_out)
+{
+	const u8 * ucp;
+
+	if (sb_len < 7)
+		return false;
+	switch (sense_buffer[0] & 0x7f) {
+	case 0x70:
+	case 0x71:
+		if (sense_buffer[0] & 0x80) {
+			*info_out = get_unaligned_be32(&sense_buffer[3]);
+			return true;
+		}
+		return false;
+	case 0x72:
+	case 0x73:
+		ucp = scsi_sense_desc_find(sense_buffer, sb_len,
+					   0 /* info desc */);
+		if (ucp && (0xa == ucp[1])) {
+			*info_out = get_unaligned_be64(&ucp[4]);
+			return true;
+		}
+		return false;
+	default:
+		return false;
+	}
+}
+EXPORT_SYMBOL(scsi_get_sense_info_fld);