X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=drivers%2Fscsi%2Flibata-eh.c;h=bf5a72aca8a4979957ae9a7ce8ff519d70490655;hb=beb07c1a56e2cff3842e22c473bd1aaaea08e532;hp=c31b13fd53072da506bdc722c8a311825f28de04;hpb=857c68f733eea07f11a061caea43a38fed61adb7;p=linux-2.6

diff --git a/drivers/scsi/libata-eh.c b/drivers/scsi/libata-eh.c
index c31b13fd53..bf5a72aca8 100644
--- a/drivers/scsi/libata-eh.c
+++ b/drivers/scsi/libata-eh.c
@@ -39,11 +39,92 @@
 #include <scsi/scsi_eh.h>
 #include <scsi/scsi_device.h>
 #include <scsi/scsi_cmnd.h>
+#include "scsi_transport_api.h"
 
 #include <linux/libata.h>
 
 #include "libata.h"
 
+static void __ata_port_freeze(struct ata_port *ap);
+static void ata_eh_finish(struct ata_port *ap);
+
+static void ata_ering_record(struct ata_ering *ering, int is_io,
+			     unsigned int err_mask)
+{
+	struct ata_ering_entry *ent;
+
+	WARN_ON(!err_mask);
+
+	ering->cursor++;
+	ering->cursor %= ATA_ERING_SIZE;
+
+	ent = &ering->ring[ering->cursor];
+	ent->is_io = is_io;
+	ent->err_mask = err_mask;
+	ent->timestamp = get_jiffies_64();
+}
+
+static struct ata_ering_entry * ata_ering_top(struct ata_ering *ering)
+{
+	struct ata_ering_entry *ent = &ering->ring[ering->cursor];
+	if (!ent->err_mask)
+		return NULL;
+	return ent;
+}
+
+static int ata_ering_map(struct ata_ering *ering,
+			 int (*map_fn)(struct ata_ering_entry *, void *),
+			 void *arg)
+{
+	int idx, rc = 0;
+	struct ata_ering_entry *ent;
+
+	idx = ering->cursor;
+	do {
+		ent = &ering->ring[idx];
+		if (!ent->err_mask)
+			break;
+		rc = map_fn(ent, arg);
+		if (rc)
+			break;
+		idx = (idx - 1 + ATA_ERING_SIZE) % ATA_ERING_SIZE;
+	} while (idx != ering->cursor);
+
+	return rc;
+}
+
+static unsigned int ata_eh_dev_action(struct ata_device *dev)
+{
+	struct ata_eh_context *ehc = &dev->ap->eh_context;
+
+	return ehc->i.action | ehc->i.dev_action[dev->devno];
+}
+
+static void ata_eh_clear_action(struct ata_device *dev,
+				struct ata_eh_info *ehi, unsigned int action)
+{
+	int i;
+
+	if (!dev) {
+		ehi->action &= ~action;
+		for (i = 0; i < ATA_MAX_DEVICES; i++)
+			ehi->dev_action[i] &= ~action;
+	} else {
+		/* doesn't make sense for port-wide EH actions */
+		WARN_ON(!(action & ATA_EH_PERDEV_MASK));
+
+		/* break ehi->action into ehi->dev_action */
+		if (ehi->action & action) {
+			for (i = 0; i < ATA_MAX_DEVICES; i++)
+				ehi->dev_action[i] |= ehi->action & action;
+			ehi->action &= ~action;
+		}
+
+		/* turn off the specified per-dev action */
+		ehi->dev_action[dev->devno] &= ~action;
+	}
+}
+
 /**
  *	ata_scsi_timed_out - SCSI layer time out callback
  *	@cmd: timed out SCSI command
@@ -55,6 +136,8 @@
  *	from finishing it by setting EH_SCHEDULED and return
  *	EH_NOT_HANDLED.
  *
+ *	TODO: kill this function once old EH is gone.
+ *
  *	LOCKING:
  *	Called from timer context
  *
@@ -67,11 +150,17 @@ enum scsi_eh_timer_return ata_scsi_timed_out(struct scsi_cmnd *cmd)
 	struct ata_port *ap = ata_shost_to_port(host);
 	unsigned long flags;
 	struct ata_queued_cmd *qc;
-	enum scsi_eh_timer_return ret = EH_HANDLED;
+	enum scsi_eh_timer_return ret;
 
 	DPRINTK("ENTER\n");
 
-	spin_lock_irqsave(&ap->host_set->lock, flags);
+	if (ap->ops->error_handler) {
+		ret = EH_NOT_HANDLED;
+		goto out;
+	}
+
+	ret = EH_HANDLED;
+	spin_lock_irqsave(ap->lock, flags);
 	qc = ata_qc_from_tag(ap, ap->active_tag);
 	if (qc) {
 		WARN_ON(qc->scsicmd != cmd);
@@ -79,8 +168,9 @@ enum scsi_eh_timer_return ata_scsi_timed_out(struct scsi_cmnd *cmd)
 		qc->err_mask |= AC_ERR_TIMEOUT;
 		ret = EH_NOT_HANDLED;
 	}
-	spin_unlock_irqrestore(&ap->host_set->lock, flags);
+	spin_unlock_irqrestore(ap->lock, flags);
 
+ out:
 	DPRINTK("EXIT, ret=%d\n", ret);
 	return ret;
 }
@@ -100,24 +190,193 @@ enum scsi_eh_timer_return ata_scsi_timed_out(struct scsi_cmnd *cmd)
 void ata_scsi_error(struct Scsi_Host *host)
 {
 	struct ata_port *ap = ata_shost_to_port(host);
+	spinlock_t *ap_lock = ap->lock;
+	int i, repeat_cnt = ATA_EH_MAX_REPEAT;
+	unsigned long flags;
 
 	DPRINTK("ENTER\n");
 
-	/* synchronize with IRQ handler and port task */
-	spin_unlock_wait(&ap->host_set->lock);
+	/* synchronize with port task */
 	ata_port_flush_task(ap);
 
-	WARN_ON(ata_qc_from_tag(ap, ap->active_tag) == NULL);
+	/* synchronize with host_set lock and sort out timeouts */
+
+	/* For new EH, all qcs are finished in one of three ways -
+	 * normal completion, error completion, and SCSI timeout.
+	 * Both cmpletions can race against SCSI timeout.  When normal
+	 * completion wins, the qc never reaches EH.  When error
+	 * completion wins, the qc has ATA_QCFLAG_FAILED set.
+	 *
+	 * When SCSI timeout wins, things are a bit more complex.
+	 * Normal or error completion can occur after the timeout but
+	 * before this point.  In such cases, both types of
+	 * completions are honored.  A scmd is determined to have
+	 * timed out iff its associated qc is active and not failed.
+	 */
+	if (ap->ops->error_handler) {
+		struct scsi_cmnd *scmd, *tmp;
+		int nr_timedout = 0;
 
-	ap->ops->eng_timeout(ap);
+		spin_lock_irqsave(ap_lock, flags);
 
+		list_for_each_entry_safe(scmd, tmp, &host->eh_cmd_q, eh_entry) {
+			struct ata_queued_cmd *qc;
+
+			for (i = 0; i < ATA_MAX_QUEUE; i++) {
+				qc = __ata_qc_from_tag(ap, i);
+				if (qc->flags & ATA_QCFLAG_ACTIVE &&
+				    qc->scsicmd == scmd)
+					break;
+			}
+
+			if (i < ATA_MAX_QUEUE) {
+				/* the scmd has an associated qc */
+				if (!(qc->flags & ATA_QCFLAG_FAILED)) {
+					/* which hasn't failed yet, timeout */
+					qc->err_mask |= AC_ERR_TIMEOUT;
+					qc->flags |= ATA_QCFLAG_FAILED;
+					nr_timedout++;
+				}
+			} else {
+				/* Normal completion occurred after
+				 * SCSI timeout but before this point.
+				 * Successfully complete it.
+				 */
+				scmd->retries = scmd->allowed;
+				scsi_eh_finish_cmd(scmd, &ap->eh_done_q);
+			}
+		}
+
+		/* If we have timed out qcs.  They belong to EH from
+		 * this point but the state of the controller is
+		 * unknown.  Freeze the port to make sure the IRQ
+		 * handler doesn't diddle with those qcs.  This must
+		 * be done atomically w.r.t. setting QCFLAG_FAILED.
+		 */
+		if (nr_timedout)
+			__ata_port_freeze(ap);
+
+		spin_unlock_irqrestore(ap_lock, flags);
+	} else
+		spin_unlock_wait(ap_lock);
+
+ repeat:
+	/* invoke error handler */
+	if (ap->ops->error_handler) {
+		/* fetch & clear EH info */
+		spin_lock_irqsave(ap_lock, flags);
+
+		memset(&ap->eh_context, 0, sizeof(ap->eh_context));
+		ap->eh_context.i = ap->eh_info;
+		memset(&ap->eh_info, 0, sizeof(ap->eh_info));
+
+		ap->flags |= ATA_FLAG_EH_IN_PROGRESS;
+		ap->flags &= ~ATA_FLAG_EH_PENDING;
+
+		spin_unlock_irqrestore(ap_lock, flags);
+
+		/* invoke EH.  if unloading, just finish failed qcs */
+		if (!(ap->flags & ATA_FLAG_UNLOADING))
+			ap->ops->error_handler(ap);
+		else
+			ata_eh_finish(ap);
+
+		/* Exception might have happend after ->error_handler
+		 * recovered the port but before this point.  Repeat
+		 * EH in such case.
+		 */
+		spin_lock_irqsave(ap_lock, flags);
+
+		if (ap->flags & ATA_FLAG_EH_PENDING) {
+			if (--repeat_cnt) {
+				ata_port_printk(ap, KERN_INFO,
+					"EH pending after completion, "
+					"repeating EH (cnt=%d)\n", repeat_cnt);
+				spin_unlock_irqrestore(ap_lock, flags);
+				goto repeat;
+			}
+			ata_port_printk(ap, KERN_ERR, "EH pending after %d "
+					"tries, giving up\n", ATA_EH_MAX_REPEAT);
+		}
+
+		/* this run is complete, make sure EH info is clear */
+		memset(&ap->eh_info, 0, sizeof(ap->eh_info));
+
+		/* Clear host_eh_scheduled while holding ap_lock such
+		 * that if exception occurs after this point but
+		 * before EH completion, SCSI midlayer will
+		 * re-initiate EH.
+		 */
+		host->host_eh_scheduled = 0;
+
+		spin_unlock_irqrestore(ap_lock, flags);
+	} else {
+		WARN_ON(ata_qc_from_tag(ap, ap->active_tag) == NULL);
+		ap->ops->eng_timeout(ap);
+	}
+
+	/* finish or retry handled scmd's and clean up */
 	WARN_ON(host->host_failed || !list_empty(&host->eh_cmd_q));
 
 	scsi_eh_flush_done_q(&ap->eh_done_q);
 
+	/* clean up */
+	spin_lock_irqsave(ap_lock, flags);
+
+	if (ap->flags & ATA_FLAG_LOADING) {
+		ap->flags &= ~ATA_FLAG_LOADING;
+	} else {
+		if (ap->flags & ATA_FLAG_SCSI_HOTPLUG)
+			queue_work(ata_aux_wq, &ap->hotplug_task);
+		if (ap->flags & ATA_FLAG_RECOVERED)
+			ata_port_printk(ap, KERN_INFO, "EH complete\n");
+	}
+
+	ap->flags &= ~(ATA_FLAG_SCSI_HOTPLUG | ATA_FLAG_RECOVERED);
+
+	/* tell wait_eh that we're done */
+	ap->flags &= ~ATA_FLAG_EH_IN_PROGRESS;
+	wake_up_all(&ap->eh_wait_q);
+
+	spin_unlock_irqrestore(ap_lock, flags);
+
 	DPRINTK("EXIT\n");
 }
 
+/**
+ *	ata_port_wait_eh - Wait for the currently pending EH to complete
+ *	@ap: Port to wait EH for
+ *
+ *	Wait until the currently pending EH is complete.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ */
+void ata_port_wait_eh(struct ata_port *ap)
+{
+	unsigned long flags;
+	DEFINE_WAIT(wait);
+
+ retry:
+	spin_lock_irqsave(ap->lock, flags);
+
+	while (ap->flags & (ATA_FLAG_EH_PENDING | ATA_FLAG_EH_IN_PROGRESS)) {
+		prepare_to_wait(&ap->eh_wait_q, &wait, TASK_UNINTERRUPTIBLE);
+		spin_unlock_irqrestore(ap->lock, flags);
+		schedule();
+		spin_lock_irqsave(ap->lock, flags);
+	}
+	finish_wait(&ap->eh_wait_q, &wait);
+
+	spin_unlock_irqrestore(ap->lock, flags);
+
+	/* make sure SCSI EH is complete */
+	if (scsi_host_in_recovery(ap->host)) {
+		msleep(10);
+		goto retry;
+	}
+}
+
 /**
  *	ata_qc_timeout - Handle timeout of queued command
  *	@qc: Command that timed out
@@ -133,13 +392,14 @@ void ata_scsi_error(struct Scsi_Host *host)
  *	an interrupt was not delivered to the driver, even though the
  *	transaction completed successfully.
  *
+ *	TODO: kill this function once old EH is gone.
+ *
  *	LOCKING:
  *	Inherited from SCSI layer (none, can sleep)
  */
 static void ata_qc_timeout(struct ata_queued_cmd *qc)
 {
 	struct ata_port *ap = qc->ap;
-	struct ata_host_set *host_set = ap->host_set;
 	u8 host_stat = 0, drv_stat;
 	unsigned long flags;
 
@@ -147,7 +407,7 @@ static void ata_qc_timeout(struct ata_queued_cmd *qc)
 
 	ap->hsm_task_state = HSM_ST_IDLE;
 
-	spin_lock_irqsave(&host_set->lock, flags);
+	spin_lock_irqsave(ap->lock, flags);
 
 	switch (qc->tf.protocol) {
 
@@ -167,15 +427,16 @@ static void ata_qc_timeout(struct ata_queued_cmd *qc)
 		/* ack bmdma irq events */
 		ap->ops->irq_clear(ap);
 
-		printk(KERN_ERR "ata%u: command 0x%x timeout, stat 0x%x host_stat 0x%x\n",
-		       ap->id, qc->tf.command, drv_stat, host_stat);
+		ata_dev_printk(qc->dev, KERN_ERR, "command 0x%x timeout, "
+			       "stat 0x%x host_stat 0x%x\n",
+			       qc->tf.command, drv_stat, host_stat);
 
 		/* complete taskfile transaction */
-		qc->err_mask |= ac_err_mask(drv_stat);
+		qc->err_mask |= AC_ERR_TIMEOUT;
 		break;
 	}
 
-	spin_unlock_irqrestore(&host_set->lock, flags);
+	spin_unlock_irqrestore(ap->lock, flags);
 
 	ata_eh_qc_complete(qc);
 
@@ -197,6 +458,8 @@ static void ata_qc_timeout(struct ata_queued_cmd *qc)
  *	an interrupt was not delivered to the driver, even though the
  *	transaction completed successfully.
  *
+ *	TODO: kill this function once old EH is gone.
+ *
  *	LOCKING:
  *	Inherited from SCSI layer (none, can sleep)
  */
@@ -209,6 +472,190 @@ void ata_eng_timeout(struct ata_port *ap)
 	DPRINTK("EXIT\n");
 }
 
+/**
+ *	ata_qc_schedule_eh - schedule qc for error handling
+ *	@qc: command to schedule error handling for
+ *
+ *	Schedule error handling for @qc.  EH will kick in as soon as
+ *	other commands are drained.
+ *
+ *	LOCKING:
+ *	spin_lock_irqsave(host_set lock)
+ */
+void ata_qc_schedule_eh(struct ata_queued_cmd *qc)
+{
+	struct ata_port *ap = qc->ap;
+
+	WARN_ON(!ap->ops->error_handler);
+
+	qc->flags |= ATA_QCFLAG_FAILED;
+	qc->ap->flags |= ATA_FLAG_EH_PENDING;
+
+	/* The following will fail if timeout has already expired.
+	 * ata_scsi_error() takes care of such scmds on EH entry.
+	 * Note that ATA_QCFLAG_FAILED is unconditionally set after
+	 * this function completes.
+	 */
+	scsi_req_abort_cmd(qc->scsicmd);
+}
+
+/**
+ *	ata_port_schedule_eh - schedule error handling without a qc
+ *	@ap: ATA port to schedule EH for
+ *
+ *	Schedule error handling for @ap.  EH will kick in as soon as
+ *	all commands are drained.
+ *
+ *	LOCKING:
+ *	spin_lock_irqsave(host_set lock)
+ */
+void ata_port_schedule_eh(struct ata_port *ap)
+{
+	WARN_ON(!ap->ops->error_handler);
+
+	ap->flags |= ATA_FLAG_EH_PENDING;
+	scsi_schedule_eh(ap->host);
+
+	DPRINTK("port EH scheduled\n");
+}
+
+/**
+ *	ata_port_abort - abort all qc's on the port
+ *	@ap: ATA port to abort qc's for
+ *
+ *	Abort all active qc's of @ap and schedule EH.
+ *
+ *	LOCKING:
+ *	spin_lock_irqsave(host_set lock)
+ *
+ *	RETURNS:
+ *	Number of aborted qc's.
+ */
+int ata_port_abort(struct ata_port *ap)
+{
+	int tag, nr_aborted = 0;
+
+	WARN_ON(!ap->ops->error_handler);
+
+	for (tag = 0; tag < ATA_MAX_QUEUE; tag++) {
+		struct ata_queued_cmd *qc = ata_qc_from_tag(ap, tag);
+
+		if (qc) {
+			qc->flags |= ATA_QCFLAG_FAILED;
+			ata_qc_complete(qc);
+			nr_aborted++;
+		}
+	}
+
+	if (!nr_aborted)
+		ata_port_schedule_eh(ap);
+
+	return nr_aborted;
+}
+
+/**
+ *	__ata_port_freeze - freeze port
+ *	@ap: ATA port to freeze
+ *
+ *	This function is called when HSM violation or some other
+ *	condition disrupts normal operation of the port.  Frozen port
+ *	is not allowed to perform any operation until the port is
+ *	thawed, which usually follows a successful reset.
+ *
+ *	ap->ops->freeze() callback can be used for freezing the port
+ *	hardware-wise (e.g. mask interrupt and stop DMA engine).  If a
+ *	port cannot be frozen hardware-wise, the interrupt handler
+ *	must ack and clear interrupts unconditionally while the port
+ *	is frozen.
+ *
+ *	LOCKING:
+ *	spin_lock_irqsave(host_set lock)
+ */
+static void __ata_port_freeze(struct ata_port *ap)
+{
+	WARN_ON(!ap->ops->error_handler);
+
+	if (ap->ops->freeze)
+		ap->ops->freeze(ap);
+
+	ap->flags |= ATA_FLAG_FROZEN;
+
+	DPRINTK("ata%u port frozen\n", ap->id);
+}
+
+/**
+ *	ata_port_freeze - abort & freeze port
+ *	@ap: ATA port to freeze
+ *
+ *	Abort and freeze @ap.
+ *
+ *	LOCKING:
+ *	spin_lock_irqsave(host_set lock)
+ *
+ *	RETURNS:
+ *	Number of aborted commands.
+ */
+int ata_port_freeze(struct ata_port *ap)
+{
+	int nr_aborted;
+
+	WARN_ON(!ap->ops->error_handler);
+
+	nr_aborted = ata_port_abort(ap);
+	__ata_port_freeze(ap);
+
+	return nr_aborted;
+}
+
+/**
+ *	ata_eh_freeze_port - EH helper to freeze port
+ *	@ap: ATA port to freeze
+ *
+ *	Freeze @ap.
+ *
+ *	LOCKING:
+ *	None.
+ */
+void ata_eh_freeze_port(struct ata_port *ap)
+{
+	unsigned long flags;
+
+	if (!ap->ops->error_handler)
+		return;
+
+	spin_lock_irqsave(ap->lock, flags);
+	__ata_port_freeze(ap);
+	spin_unlock_irqrestore(ap->lock, flags);
+}
+
+/**
+ *	ata_port_thaw_port - EH helper to thaw port
+ *	@ap: ATA port to thaw
+ *
+ *	Thaw frozen port @ap.
+ *
+ *	LOCKING:
+ *	None.
+ */
+void ata_eh_thaw_port(struct ata_port *ap)
+{
+	unsigned long flags;
+
+	if (!ap->ops->error_handler)
+		return;
+
+	spin_lock_irqsave(ap->lock, flags);
+
+	ap->flags &= ~ATA_FLAG_FROZEN;
+
+	if (ap->ops->thaw)
+		ap->ops->thaw(ap);
+
+	spin_unlock_irqrestore(ap->lock, flags);
+
+	DPRINTK("ata%u port thawed\n", ap->id);
+}
+
 static void ata_eh_scsidone(struct scsi_cmnd *scmd)
 {
 	/* nada */
@@ -220,11 +667,11 @@ static void __ata_eh_qc_complete(struct ata_queued_cmd *qc)
 	struct scsi_cmnd *scmd = qc->scsicmd;
 	unsigned long flags;
 
-	spin_lock_irqsave(&ap->host_set->lock, flags);
+	spin_lock_irqsave(ap->lock, flags);
 	qc->scsidone = ata_eh_scsidone;
 	__ata_qc_complete(qc);
 	WARN_ON(ata_tag_valid(qc->tag));
-	spin_unlock_irqrestore(&ap->host_set->lock, flags);
+	spin_unlock_irqrestore(ap->lock, flags);
 
 	scsi_eh_finish_cmd(scmd, &ap->eh_done_q);
 }
@@ -261,3 +708,1211 @@ void ata_eh_qc_retry(struct ata_queued_cmd *qc)
 		scmd->retries--;
 	__ata_eh_qc_complete(qc);
 }
+
+/**
+ *	ata_eh_detach_dev - detach ATA device
+ *	@dev: ATA device to detach
+ *
+ *	Detach @dev.
+ *
+ *	LOCKING:
+ *	None.
+ */
+static void ata_eh_detach_dev(struct ata_device *dev)
+{
+	struct ata_port *ap = dev->ap;
+	unsigned long flags;
+
+	ata_dev_disable(dev);
+
+	spin_lock_irqsave(ap->lock, flags);
+
+	dev->flags &= ~ATA_DFLAG_DETACH;
+
+	if (ata_scsi_offline_dev(dev)) {
+		dev->flags |= ATA_DFLAG_DETACHED;
+		ap->flags |= ATA_FLAG_SCSI_HOTPLUG;
+	}
+
+	/* clear per-dev EH actions */
+	ata_eh_clear_action(dev, &ap->eh_info, ATA_EH_PERDEV_MASK);
+	ata_eh_clear_action(dev, &ap->eh_context.i, ATA_EH_PERDEV_MASK);
+
+	spin_unlock_irqrestore(ap->lock, flags);
+}
+
+/**
+ *	ata_eh_about_to_do - about to perform eh_action
+ *	@ap: target ATA port
+ *	@dev: target ATA dev for per-dev action (can be NULL)
+ *	@action: action about to be performed
+ *
+ *	Called just before performing EH actions to clear related bits
+ *	in @ap->eh_info such that eh actions are not unnecessarily
+ *	repeated.
+ *
+ *	LOCKING:
+ *	None.
+ */
+static void ata_eh_about_to_do(struct ata_port *ap, struct ata_device *dev,
+			       unsigned int action)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(ap->lock, flags);
+	ata_eh_clear_action(dev, &ap->eh_info, action);
+	ap->flags |= ATA_FLAG_RECOVERED;
+	spin_unlock_irqrestore(ap->lock, flags);
+}
+
+/**
+ *	ata_eh_done - EH action complete
+ *	@ap: target ATA port
+ *	@dev: target ATA dev for per-dev action (can be NULL)
+ *	@action: action just completed
+ *
+ *	Called right after performing EH actions to clear related bits
+ *	in @ap->eh_context.
+ *
+ *	LOCKING:
+ *	None.
+ */
+static void ata_eh_done(struct ata_port *ap, struct ata_device *dev,
+			unsigned int action)
+{
+	ata_eh_clear_action(dev, &ap->eh_context.i, action);
+}
+
+/**
+ *	ata_err_string - convert err_mask to descriptive string
+ *	@err_mask: error mask to convert to string
+ *
+ *	Convert @err_mask to descriptive string.  Errors are
+ *	prioritized according to severity and only the most severe
+ *	error is reported.
+ *
+ *	LOCKING:
+ *	None.
+ *
+ *	RETURNS:
+ *	Descriptive string for @err_mask
+ */
+static const char * ata_err_string(unsigned int err_mask)
+{
+	if (err_mask & AC_ERR_HOST_BUS)
+		return "host bus error";
+	if (err_mask & AC_ERR_ATA_BUS)
+		return "ATA bus error";
+	if (err_mask & AC_ERR_TIMEOUT)
+		return "timeout";
+	if (err_mask & AC_ERR_HSM)
+		return "HSM violation";
+	if (err_mask & AC_ERR_SYSTEM)
+		return "internal error";
+	if (err_mask & AC_ERR_MEDIA)
+		return "media error";
+	if (err_mask & AC_ERR_INVALID)
+		return "invalid argument";
+	if (err_mask & AC_ERR_DEV)
+		return "device error";
+	return "unknown error";
+}
+
+/**
+ *	ata_read_log_page - read a specific log page
+ *	@dev: target device
+ *	@page: page to read
+ *	@buf: buffer to store read page
+ *	@sectors: number of sectors to read
+ *
+ *	Read log page using READ_LOG_EXT command.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ *
+ *	RETURNS:
+ *	0 on success, AC_ERR_* mask otherwise.
+ */
+static unsigned int ata_read_log_page(struct ata_device *dev,
+				      u8 page, void *buf, unsigned int sectors)
+{
+	struct ata_taskfile tf;
+	unsigned int err_mask;
+
+	DPRINTK("read log page - page %d\n", page);
+
+	ata_tf_init(dev, &tf);
+	tf.command = ATA_CMD_READ_LOG_EXT;
+	tf.lbal = page;
+	tf.nsect = sectors;
+	tf.hob_nsect = sectors >> 8;
+	tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_LBA48 | ATA_TFLAG_DEVICE;
+	tf.protocol = ATA_PROT_PIO;
+
+	err_mask = ata_exec_internal(dev, &tf, NULL, DMA_FROM_DEVICE,
+				     buf, sectors * ATA_SECT_SIZE);
+
+	DPRINTK("EXIT, err_mask=%x\n", err_mask);
+	return err_mask;
+}
+
+/**
+ *	ata_eh_read_log_10h - Read log page 10h for NCQ error details
+ *	@dev: Device to read log page 10h from
+ *	@tag: Resulting tag of the failed command
+ *	@tf: Resulting taskfile registers of the failed command
+ *
+ *	Read log page 10h to obtain NCQ error details and clear error
+ *	condition.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ *
+ *	RETURNS:
+ *	0 on success, -errno otherwise.
+ */
+static int ata_eh_read_log_10h(struct ata_device *dev,
+			       int *tag, struct ata_taskfile *tf)
+{
+	u8 *buf = dev->ap->sector_buf;
+	unsigned int err_mask;
+	u8 csum;
+	int i;
+
+	err_mask = ata_read_log_page(dev, ATA_LOG_SATA_NCQ, buf, 1);
+	if (err_mask)
+		return -EIO;
+
+	csum = 0;
+	for (i = 0; i < ATA_SECT_SIZE; i++)
+		csum += buf[i];
+	if (csum)
+		ata_dev_printk(dev, KERN_WARNING,
+			       "invalid checksum 0x%x on log page 10h\n", csum);
+
+	if (buf[0] & 0x80)
+		return -ENOENT;
+
+	*tag = buf[0] & 0x1f;
+
+	tf->command = buf[2];
+	tf->feature = buf[3];
+	tf->lbal = buf[4];
+	tf->lbam = buf[5];
+	tf->lbah = buf[6];
+	tf->device = buf[7];
+	tf->hob_lbal = buf[8];
+	tf->hob_lbam = buf[9];
+	tf->hob_lbah = buf[10];
+	tf->nsect = buf[12];
+	tf->hob_nsect = buf[13];
+
+	return 0;
+}
+
+/**
+ *	atapi_eh_request_sense - perform ATAPI REQUEST_SENSE
+ *	@dev: device to perform REQUEST_SENSE to
+ *	@sense_buf: result sense data buffer (SCSI_SENSE_BUFFERSIZE bytes long)
+ *
+ *	Perform ATAPI REQUEST_SENSE after the device reported CHECK
+ *	SENSE.  This function is EH helper.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ *
+ *	RETURNS:
+ *	0 on success, AC_ERR_* mask on failure
+ */
+static unsigned int atapi_eh_request_sense(struct ata_device *dev,
+					   unsigned char *sense_buf)
+{
+	struct ata_port *ap = dev->ap;
+	struct ata_taskfile tf;
+	u8 cdb[ATAPI_CDB_LEN];
+
+	DPRINTK("ATAPI request sense\n");
+
+	ata_tf_init(dev, &tf);
+
+	/* FIXME: is this needed? */
+	memset(sense_buf, 0, SCSI_SENSE_BUFFERSIZE);
+
+	/* XXX: why tf_read here? */
+	ap->ops->tf_read(ap, &tf);
+
+	/* fill these in, for the case where they are -not- overwritten */
+	sense_buf[0] = 0x70;
+	sense_buf[2] = tf.feature >> 4;
+
+	memset(cdb, 0, ATAPI_CDB_LEN);
+	cdb[0] = REQUEST_SENSE;
+	cdb[4] = SCSI_SENSE_BUFFERSIZE;
+
+	tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
+	tf.command = ATA_CMD_PACKET;
+
+	/* is it pointless to prefer PIO for "safety reasons"? */
+	if (ap->flags & ATA_FLAG_PIO_DMA) {
+		tf.protocol = ATA_PROT_ATAPI_DMA;
+		tf.feature |= ATAPI_PKT_DMA;
+	} else {
+		tf.protocol = ATA_PROT_ATAPI;
+		tf.lbam = (8 * 1024) & 0xff;
+		tf.lbah = (8 * 1024) >> 8;
+	}
+
+	return ata_exec_internal(dev, &tf, cdb, DMA_FROM_DEVICE,
+				 sense_buf, SCSI_SENSE_BUFFERSIZE);
+}
+
+/**
+ *	ata_eh_analyze_serror - analyze SError for a failed port
+ *	@ap: ATA port to analyze SError for
+ *
+ *	Analyze SError if available and further determine cause of
+ *	failure.
+ *
+ *	LOCKING:
+ *	None.
+ */
+static void ata_eh_analyze_serror(struct ata_port *ap)
+{
+	struct ata_eh_context *ehc = &ap->eh_context;
+	u32 serror = ehc->i.serror;
+	unsigned int err_mask = 0, action = 0;
+
+	if (serror & SERR_PERSISTENT) {
+		err_mask |= AC_ERR_ATA_BUS;
+		action |= ATA_EH_HARDRESET;
+	}
+	if (serror &
+	    (SERR_DATA_RECOVERED | SERR_COMM_RECOVERED | SERR_DATA)) {
+		err_mask |= AC_ERR_ATA_BUS;
+		action |= ATA_EH_SOFTRESET;
+	}
+	if (serror & SERR_PROTOCOL) {
+		err_mask |= AC_ERR_HSM;
+		action |= ATA_EH_SOFTRESET;
+	}
+	if (serror & SERR_INTERNAL) {
+		err_mask |= AC_ERR_SYSTEM;
+		action |= ATA_EH_SOFTRESET;
+	}
+	if (serror & (SERR_PHYRDY_CHG | SERR_DEV_XCHG))
+		ata_ehi_hotplugged(&ehc->i);
+
+	ehc->i.err_mask |= err_mask;
+	ehc->i.action |= action;
+}
+
+/**
+ *	ata_eh_analyze_ncq_error - analyze NCQ error
+ *	@ap: ATA port to analyze NCQ error for
+ *
+ *	Read log page 10h, determine the offending qc and acquire
+ *	error status TF.  For NCQ device errors, all LLDDs have to do
+ *	is setting AC_ERR_DEV in ehi->err_mask.  This function takes
+ *	care of the rest.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ */
+static void ata_eh_analyze_ncq_error(struct ata_port *ap)
+{
+	struct ata_eh_context *ehc = &ap->eh_context;
+	struct ata_device *dev = ap->device;
+	struct ata_queued_cmd *qc;
+	struct ata_taskfile tf;
+	int tag, rc;
+
+	/* if frozen, we can't do much */
+	if (ap->flags & ATA_FLAG_FROZEN)
+		return;
+
+	/* is it NCQ device error? */
+	if (!ap->sactive || !(ehc->i.err_mask & AC_ERR_DEV))
+		return;
+
+	/* has LLDD analyzed already? */
+	for (tag = 0; tag < ATA_MAX_QUEUE; tag++) {
+		qc = __ata_qc_from_tag(ap, tag);
+
+		if (!(qc->flags & ATA_QCFLAG_FAILED))
+			continue;
+
+		if (qc->err_mask)
+			return;
+	}
+
+	/* okay, this error is ours */
+	rc = ata_eh_read_log_10h(dev, &tag, &tf);
+	if (rc) {
+		ata_port_printk(ap, KERN_ERR, "failed to read log page 10h "
+				"(errno=%d)\n", rc);
+		return;
+	}
+
+	if (!(ap->sactive & (1 << tag))) {
+		ata_port_printk(ap, KERN_ERR, "log page 10h reported "
+				"inactive tag %d\n", tag);
+		return;
+	}
+
+	/* we've got the perpetrator, condemn it */
+	qc = __ata_qc_from_tag(ap, tag);
+	memcpy(&qc->result_tf, &tf, sizeof(tf));
+	qc->err_mask |= AC_ERR_DEV;
+	ehc->i.err_mask &= ~AC_ERR_DEV;
+}
+
+/**
+ *	ata_eh_analyze_tf - analyze taskfile of a failed qc
+ *	@qc: qc to analyze
+ *	@tf: Taskfile registers to analyze
+ *
+ *	Analyze taskfile of @qc and further determine cause of
+ *	failure.  This function also requests ATAPI sense data if
+ *	avaliable.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ *
+ *	RETURNS:
+ *	Determined recovery action
+ */
+static unsigned int ata_eh_analyze_tf(struct ata_queued_cmd *qc,
+				      const struct ata_taskfile *tf)
+{
+	unsigned int tmp, action = 0;
+	u8 stat = tf->command, err = tf->feature;
+
+	if ((stat & (ATA_BUSY | ATA_DRQ | ATA_DRDY)) != ATA_DRDY) {
+		qc->err_mask |= AC_ERR_HSM;
+		return ATA_EH_SOFTRESET;
+	}
+
+	if (!(qc->err_mask & AC_ERR_DEV))
+		return 0;
+
+	switch (qc->dev->class) {
+	case ATA_DEV_ATA:
+		if (err & ATA_ICRC)
+			qc->err_mask |= AC_ERR_ATA_BUS;
+		if (err & ATA_UNC)
+			qc->err_mask |= AC_ERR_MEDIA;
+		if (err & ATA_IDNF)
+			qc->err_mask |= AC_ERR_INVALID;
+		break;
+
+	case ATA_DEV_ATAPI:
+		tmp = atapi_eh_request_sense(qc->dev,
+					     qc->scsicmd->sense_buffer);
+		if (!tmp) {
+			/* ATA_QCFLAG_SENSE_VALID is used to tell
+			 * atapi_qc_complete() that sense data is
+			 * already valid.
+			 *
+			 * TODO: interpret sense data and set
+			 * appropriate err_mask.
+			 */
+			qc->flags |= ATA_QCFLAG_SENSE_VALID;
+		} else
+			qc->err_mask |= tmp;
+	}
+
+	if (qc->err_mask & (AC_ERR_HSM | AC_ERR_TIMEOUT | AC_ERR_ATA_BUS))
+		action |= ATA_EH_SOFTRESET;
+
+	return action;
+}
+
+static int ata_eh_categorize_ering_entry(struct ata_ering_entry *ent)
+{
+	if (ent->err_mask & (AC_ERR_ATA_BUS | AC_ERR_TIMEOUT))
+		return 1;
+
+	if (ent->is_io) {
+		if (ent->err_mask & AC_ERR_HSM)
+			return 1;
+		if ((ent->err_mask &
+		     (AC_ERR_DEV|AC_ERR_MEDIA|AC_ERR_INVALID)) == AC_ERR_DEV)
+			return 2;
+	}
+
+	return 0;
+}
+
+struct speed_down_needed_arg {
+	u64 since;
+	int nr_errors[3];
+};
+
+static int speed_down_needed_cb(struct ata_ering_entry *ent, void *void_arg)
+{
+	struct speed_down_needed_arg *arg = void_arg;
+
+	if (ent->timestamp < arg->since)
+		return -1;
+
+	arg->nr_errors[ata_eh_categorize_ering_entry(ent)]++;
+	return 0;
+}
+
+/**
+ *	ata_eh_speed_down_needed - Determine wheter speed down is necessary
+ *	@dev: Device of interest
+ *
+ *	This function examines error ring of @dev and determines
+ *	whether speed down is necessary.  Speed down is necessary if
+ *	there have been more than 3 of Cat-1 errors or 10 of Cat-2
+ *	errors during last 15 minutes.
+ *
+ *	Cat-1 errors are ATA_BUS, TIMEOUT for any command and HSM
+ *	violation for known supported commands.
+ *
+ *	Cat-2 errors are unclassified DEV error for known supported
+ *	command.
+ *
+ *	LOCKING:
+ *	Inherited from caller.
+ *
+ *	RETURNS:
+ *	1 if speed down is necessary, 0 otherwise
+ */
+static int ata_eh_speed_down_needed(struct ata_device *dev)
+{
+	const u64 interval = 15LLU * 60 * HZ;
+	static const int err_limits[3] = { -1, 3, 10 };
+	struct speed_down_needed_arg arg;
+	struct ata_ering_entry *ent;
+	int err_cat;
+	u64 j64;
+
+	ent = ata_ering_top(&dev->ering);
+	if (!ent)
+		return 0;
+
+	err_cat = ata_eh_categorize_ering_entry(ent);
+	if (err_cat == 0)
+		return 0;
+
+	memset(&arg, 0, sizeof(arg));
+
+	j64 = get_jiffies_64();
+	if (j64 >= interval)
+		arg.since = j64 - interval;
+	else
+		arg.since = 0;
+
+	ata_ering_map(&dev->ering, speed_down_needed_cb, &arg);
+
+	return arg.nr_errors[err_cat] > err_limits[err_cat];
+}
+
+/**
+ *	ata_eh_speed_down - record error and speed down if necessary
+ *	@dev: Failed device
+ *	@is_io: Did the device fail during normal IO?
+ *	@err_mask: err_mask of the error
+ *
+ *	Record error and examine error history to determine whether
+ *	adjusting transmission speed is necessary.  It also sets
+ *	transmission limits appropriately if such adjustment is
+ *	necessary.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ *
+ *	RETURNS:
+ *	0 on success, -errno otherwise
+ */
+static int ata_eh_speed_down(struct ata_device *dev, int is_io,
+			     unsigned int err_mask)
+{
+	if (!err_mask)
+		return 0;
+
+	/* record error and determine whether speed down is necessary */
+	ata_ering_record(&dev->ering, is_io, err_mask);
+
+	if (!ata_eh_speed_down_needed(dev))
+		return 0;
+
+	/* speed down SATA link speed if possible */
+	if (sata_down_spd_limit(dev->ap) == 0)
+		return ATA_EH_HARDRESET;
+
+	/* lower transfer mode */
+	if (ata_down_xfermask_limit(dev, 0) == 0)
+		return ATA_EH_SOFTRESET;
+
+	ata_dev_printk(dev, KERN_ERR,
+		       "speed down requested but no transfer mode left\n");
+	return 0;
+}
+
+/**
+ *	ata_eh_autopsy - analyze error and determine recovery action
+ *	@ap: ATA port to perform autopsy on
+ *
+ *	Analyze why @ap failed and determine which recovery action is
+ *	needed.  This function also sets more detailed AC_ERR_* values
+ *	and fills sense data for ATAPI CHECK SENSE.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ */
+static void ata_eh_autopsy(struct ata_port *ap)
+{
+	struct ata_eh_context *ehc = &ap->eh_context;
+	unsigned int action = ehc->i.action;
+	struct ata_device *failed_dev = NULL;
+	unsigned int all_err_mask = 0;
+	int tag, is_io = 0;
+	u32 serror;
+	int rc;
+
+	DPRINTK("ENTER\n");
+
+	/* obtain and analyze SError */
+	rc = sata_scr_read(ap, SCR_ERROR, &serror);
+	if (rc == 0) {
+		ehc->i.serror |= serror;
+		ata_eh_analyze_serror(ap);
+	} else if (rc != -EOPNOTSUPP)
+		action |= ATA_EH_HARDRESET;
+
+	/* analyze NCQ failure */
+	ata_eh_analyze_ncq_error(ap);
+
+	/* any real error trumps AC_ERR_OTHER */
+	if (ehc->i.err_mask & ~AC_ERR_OTHER)
+		ehc->i.err_mask &= ~AC_ERR_OTHER;
+
+	all_err_mask |= ehc->i.err_mask;
+
+	for (tag = 0; tag < ATA_MAX_QUEUE; tag++) {
+		struct ata_queued_cmd *qc = __ata_qc_from_tag(ap, tag);
+
+		if (!(qc->flags & ATA_QCFLAG_FAILED))
+			continue;
+
+		/* inherit upper level err_mask */
+		qc->err_mask |= ehc->i.err_mask;
+
+		/* analyze TF */
+		action |= ata_eh_analyze_tf(qc, &qc->result_tf);
+
+		/* DEV errors are probably spurious in case of ATA_BUS error */
+		if (qc->err_mask & AC_ERR_ATA_BUS)
+			qc->err_mask &= ~(AC_ERR_DEV | AC_ERR_MEDIA |
+					  AC_ERR_INVALID);
+
+		/* any real error trumps unknown error */
+		if (qc->err_mask & ~AC_ERR_OTHER)
+			qc->err_mask &= ~AC_ERR_OTHER;
+
+		/* SENSE_VALID trumps dev/unknown error and revalidation */
+		if (qc->flags & ATA_QCFLAG_SENSE_VALID) {
+			qc->err_mask &= ~(AC_ERR_DEV | AC_ERR_OTHER);
+			action &= ~ATA_EH_REVALIDATE;
+		}
+
+		/* accumulate error info */
+		failed_dev = qc->dev;
+		all_err_mask |= qc->err_mask;
+		if (qc->flags & ATA_QCFLAG_IO)
+			is_io = 1;
+	}
+
+	/* enforce default EH actions */
+	if (ap->flags & ATA_FLAG_FROZEN ||
+	    all_err_mask & (AC_ERR_HSM | AC_ERR_TIMEOUT))
+		action |= ATA_EH_SOFTRESET;
+	else if (all_err_mask)
+		action |= ATA_EH_REVALIDATE;
+
+	/* if we have offending qcs and the associated failed device */
+	if (failed_dev) {
+		/* speed down */
+		action |= ata_eh_speed_down(failed_dev, is_io, all_err_mask);
+
+		/* perform per-dev EH action only on the offending device */
+		ehc->i.dev_action[failed_dev->devno] |=
+			action & ATA_EH_PERDEV_MASK;
+		action &= ~ATA_EH_PERDEV_MASK;
+	}
+
+	/* record autopsy result */
+	ehc->i.dev = failed_dev;
+	ehc->i.action = action;
+
+	DPRINTK("EXIT\n");
+}
+
+/**
+ *	ata_eh_report - report error handling to user
+ *	@ap: ATA port EH is going on
+ *
+ *	Report EH to user.
+ *
+ *	LOCKING:
+ *	None.
+ */
+static void ata_eh_report(struct ata_port *ap)
+{
+	struct ata_eh_context *ehc = &ap->eh_context;
+	const char *frozen, *desc;
+	int tag, nr_failed = 0;
+
+	desc = NULL;
+	if (ehc->i.desc[0] != '\0')
+		desc = ehc->i.desc;
+
+	for (tag = 0; tag < ATA_MAX_QUEUE; tag++) {
+		struct ata_queued_cmd *qc = __ata_qc_from_tag(ap, tag);
+
+		if (!(qc->flags & ATA_QCFLAG_FAILED))
+			continue;
+		if (qc->flags & ATA_QCFLAG_SENSE_VALID && !qc->err_mask)
+			continue;
+
+		nr_failed++;
+	}
+
+	if (!nr_failed && !ehc->i.err_mask)
+		return;
+
+	frozen = "";
+	if (ap->flags & ATA_FLAG_FROZEN)
+		frozen = " frozen";
+
+	if (ehc->i.dev) {
+		ata_dev_printk(ehc->i.dev, KERN_ERR, "exception Emask 0x%x "
+			       "SAct 0x%x SErr 0x%x action 0x%x%s\n",
+			       ehc->i.err_mask, ap->sactive, ehc->i.serror,
+			       ehc->i.action, frozen);
+		if (desc)
+			ata_dev_printk(ehc->i.dev, KERN_ERR, "(%s)\n", desc);
+	} else {
+		ata_port_printk(ap, KERN_ERR, "exception Emask 0x%x "
+				"SAct 0x%x SErr 0x%x action 0x%x%s\n",
+				ehc->i.err_mask, ap->sactive, ehc->i.serror,
+				ehc->i.action, frozen);
+		if (desc)
+			ata_port_printk(ap, KERN_ERR, "(%s)\n", desc);
+	}
+
+	for (tag = 0; tag < ATA_MAX_QUEUE; tag++) {
+		struct ata_queued_cmd *qc = __ata_qc_from_tag(ap, tag);
+
+		if (!(qc->flags & ATA_QCFLAG_FAILED) || !qc->err_mask)
+			continue;
+
+		ata_dev_printk(qc->dev, KERN_ERR, "tag %d cmd 0x%x "
+			       "Emask 0x%x stat 0x%x err 0x%x (%s)\n",
+			       qc->tag, qc->tf.command, qc->err_mask,
+			       qc->result_tf.command, qc->result_tf.feature,
+			       ata_err_string(qc->err_mask));
+	}
+}
+
+static int ata_do_reset(struct ata_port *ap, ata_reset_fn_t reset,
+			unsigned int *classes)
+{
+	int i, rc;
+
+	for (i = 0; i < ATA_MAX_DEVICES; i++)
+		classes[i] = ATA_DEV_UNKNOWN;
+
+	rc = reset(ap, classes);
+	if (rc)
+		return rc;
+
+	/* If any class isn't ATA_DEV_UNKNOWN, consider classification
+	 * is complete and convert all ATA_DEV_UNKNOWN to
+	 * ATA_DEV_NONE.
+	 */
+	for (i = 0; i < ATA_MAX_DEVICES; i++)
+		if (classes[i] != ATA_DEV_UNKNOWN)
+			break;
+
+	if (i < ATA_MAX_DEVICES)
+		for (i = 0; i < ATA_MAX_DEVICES; i++)
+			if (classes[i] == ATA_DEV_UNKNOWN)
+				classes[i] = ATA_DEV_NONE;
+
+	return 0;
+}
+
+static int ata_eh_followup_srst_needed(int rc, int classify,
+				       const unsigned int *classes)
+{
+	if (rc == -EAGAIN)
+		return 1;
+	if (rc != 0)
+		return 0;
+	if (classify && classes[0] == ATA_DEV_UNKNOWN)
+		return 1;
+	return 0;
+}
+
+static int ata_eh_reset(struct ata_port *ap, int classify,
+			ata_prereset_fn_t prereset, ata_reset_fn_t softreset,
+			ata_reset_fn_t hardreset, ata_postreset_fn_t postreset)
+{
+	struct ata_eh_context *ehc = &ap->eh_context;
+	unsigned int *classes = ehc->classes;
+	int tries = ATA_EH_RESET_TRIES;
+	int verbose = !(ap->flags & ATA_FLAG_LOADING);
+	unsigned int action;
+	ata_reset_fn_t reset;
+	int i, did_followup_srst, rc;
+
+	/* Determine which reset to use and record in ehc->i.action.
+	 * prereset() may examine and modify it.
+	 */
+	action = ehc->i.action;
+	ehc->i.action &= ~ATA_EH_RESET_MASK;
+	if (softreset && (!hardreset || (!sata_set_spd_needed(ap) &&
+					 !(action & ATA_EH_HARDRESET))))
+		ehc->i.action |= ATA_EH_SOFTRESET;
+	else
+		ehc->i.action |= ATA_EH_HARDRESET;
+
+	if (prereset) {
+		rc = prereset(ap);
+		if (rc) {
+			ata_port_printk(ap, KERN_ERR,
+					"prereset failed (errno=%d)\n", rc);
+			return rc;
+		}
+	}
+
+	/* prereset() might have modified ehc->i.action */
+	if (ehc->i.action & ATA_EH_HARDRESET)
+		reset = hardreset;
+	else if (ehc->i.action & ATA_EH_SOFTRESET)
+		reset = softreset;
+	else {
+		/* prereset told us not to reset, bang classes and return */
+		for (i = 0; i < ATA_MAX_DEVICES; i++)
+			classes[i] = ATA_DEV_NONE;
+		return 0;
+	}
+
+	/* did prereset() screw up?  if so, fix up to avoid oopsing */
+	if (!reset) {
+		ata_port_printk(ap, KERN_ERR, "BUG: prereset() requested "
+				"invalid reset type\n");
+		if (softreset)
+			reset = softreset;
+		else
+			reset = hardreset;
+	}
+
+ retry:
+	/* shut up during boot probing */
+	if (verbose)
+		ata_port_printk(ap, KERN_INFO, "%s resetting port\n",
+				reset == softreset ? "soft" : "hard");
+
+	/* reset */
+	ata_eh_about_to_do(ap, NULL, ATA_EH_RESET_MASK);
+	ehc->i.flags |= ATA_EHI_DID_RESET;
+
+	rc = ata_do_reset(ap, reset, classes);
+
+	did_followup_srst = 0;
+	if (reset == hardreset &&
+	    ata_eh_followup_srst_needed(rc, classify, classes)) {
+		/* okay, let's do follow-up softreset */
+		did_followup_srst = 1;
+		reset = softreset;
+
+		if (!reset) {
+			ata_port_printk(ap, KERN_ERR,
+					"follow-up softreset required "
+					"but no softreset avaliable\n");
+			return -EINVAL;
+		}
+
+		ata_eh_about_to_do(ap, NULL, ATA_EH_RESET_MASK);
+		rc = ata_do_reset(ap, reset, classes);
+
+		if (rc == 0 && classify &&
+		    classes[0] == ATA_DEV_UNKNOWN) {
+			ata_port_printk(ap, KERN_ERR,
+					"classification failed\n");
+			return -EINVAL;
+		}
+	}
+
+	if (rc && --tries) {
+		const char *type;
+
+		if (reset == softreset) {
+			if (did_followup_srst)
+				type = "follow-up soft";
+			else
+				type = "soft";
+		} else
+			type = "hard";
+
+		ata_port_printk(ap, KERN_WARNING,
+				"%sreset failed, retrying in 5 secs\n", type);
+		ssleep(5);
+
+		if (reset == hardreset)
+			sata_down_spd_limit(ap);
+		if (hardreset)
+			reset = hardreset;
+		goto retry;
+	}
+
+	if (rc == 0) {
+		/* After the reset, the device state is PIO 0 and the
+		 * controller state is undefined.  Record the mode.
+		 */
+		for (i = 0; i < ATA_MAX_DEVICES; i++)
+			ap->device[i].pio_mode = XFER_PIO_0;
+
+		if (postreset)
+			postreset(ap, classes);
+
+		/* reset successful, schedule revalidation */
+		ata_eh_done(ap, NULL, ATA_EH_RESET_MASK);
+		ehc->i.action |= ATA_EH_REVALIDATE;
+	}
+
+	return rc;
+}
+
+static int ata_eh_revalidate_and_attach(struct ata_port *ap,
+					struct ata_device **r_failed_dev)
+{
+	struct ata_eh_context *ehc = &ap->eh_context;
+	struct ata_device *dev;
+	unsigned long flags;
+	int i, rc = 0;
+
+	DPRINTK("ENTER\n");
+
+	for (i = 0; i < ATA_MAX_DEVICES; i++) {
+		unsigned int action;
+
+		dev = &ap->device[i];
+		action = ata_eh_dev_action(dev);
+
+		if (action & ATA_EH_REVALIDATE && ata_dev_enabled(dev)) {
+			if (ata_port_offline(ap)) {
+				rc = -EIO;
+				break;
+			}
+
+			ata_eh_about_to_do(ap, dev, ATA_EH_REVALIDATE);
+			rc = ata_dev_revalidate(dev,
+					ehc->i.flags & ATA_EHI_DID_RESET);
+			if (rc)
+				break;
+
+			ata_eh_done(ap, dev, ATA_EH_REVALIDATE);
+
+			/* schedule the scsi_rescan_device() here */
+			queue_work(ata_aux_wq, &(ap->scsi_rescan_task));
+		} else if (dev->class == ATA_DEV_UNKNOWN &&
+			   ehc->tries[dev->devno] &&
+			   ata_class_enabled(ehc->classes[dev->devno])) {
+			dev->class = ehc->classes[dev->devno];
+
+			rc = ata_dev_read_id(dev, &dev->class, 1, dev->id);
+			if (rc == 0)
+				rc = ata_dev_configure(dev, 1);
+
+			if (rc) {
+				dev->class = ATA_DEV_UNKNOWN;
+				break;
+			}
+
+			spin_lock_irqsave(ap->lock, flags);
+			ap->flags |= ATA_FLAG_SCSI_HOTPLUG;
+			spin_unlock_irqrestore(ap->lock, flags);
+		}
+	}
+
+	if (rc)
+		*r_failed_dev = dev;
+
+	DPRINTK("EXIT\n");
+	return rc;
+}
+
+static int ata_port_nr_enabled(struct ata_port *ap)
+{
+	int i, cnt = 0;
+
+	for (i = 0; i < ATA_MAX_DEVICES; i++)
+		if (ata_dev_enabled(&ap->device[i]))
+			cnt++;
+	return cnt;
+}
+
+static int ata_port_nr_vacant(struct ata_port *ap)
+{
+	int i, cnt = 0;
+
+	for (i = 0; i < ATA_MAX_DEVICES; i++)
+		if (ap->device[i].class == ATA_DEV_UNKNOWN)
+			cnt++;
+	return cnt;
+}
+
+static int ata_eh_skip_recovery(struct ata_port *ap)
+{
+	struct ata_eh_context *ehc = &ap->eh_context;
+	int i;
+
+	if (ap->flags & ATA_FLAG_FROZEN || ata_port_nr_enabled(ap))
+		return 0;
+
+	/* skip if class codes for all vacant slots are ATA_DEV_NONE */
+	for (i = 0; i < ATA_MAX_DEVICES; i++) {
+		struct ata_device *dev = &ap->device[i];
+
+		if (dev->class == ATA_DEV_UNKNOWN &&
+		    ehc->classes[dev->devno] != ATA_DEV_NONE)
+			return 0;
+	}
+
+	return 1;
+}
+
+/**
+ *	ata_eh_recover - recover host port after error
+ *	@ap: host port to recover
+ *	@prereset: prereset method (can be NULL)
+ *	@softreset: softreset method (can be NULL)
+ *	@hardreset: hardreset method (can be NULL)
+ *	@postreset: postreset method (can be NULL)
+ *
+ *	This is the alpha and omega, eum and yang, heart and soul of
+ *	libata exception handling.  On entry, actions required to
+ *	recover the port and hotplug requests are recorded in
+ *	eh_context.  This function executes all the operations with
+ *	appropriate retrials and fallbacks to resurrect failed
+ *	devices, detach goners and greet newcomers.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ *
+ *	RETURNS:
+ *	0 on success, -errno on failure.
+ */
+static int ata_eh_recover(struct ata_port *ap, ata_prereset_fn_t prereset,
+			  ata_reset_fn_t softreset, ata_reset_fn_t hardreset,
+			  ata_postreset_fn_t postreset)
+{
+	struct ata_eh_context *ehc = &ap->eh_context;
+	struct ata_device *dev;
+	int down_xfermask, i, rc;
+
+	DPRINTK("ENTER\n");
+
+	/* prep for recovery */
+	for (i = 0; i < ATA_MAX_DEVICES; i++) {
+		dev = &ap->device[i];
+
+		ehc->tries[dev->devno] = ATA_EH_DEV_TRIES;
+
+		/* process hotplug request */
+		if (dev->flags & ATA_DFLAG_DETACH)
+			ata_eh_detach_dev(dev);
+
+		if (!ata_dev_enabled(dev) &&
+		    ((ehc->i.probe_mask & (1 << dev->devno)) &&
+		     !(ehc->did_probe_mask & (1 << dev->devno)))) {
+			ata_eh_detach_dev(dev);
+			ata_dev_init(dev);
+			ehc->did_probe_mask |= (1 << dev->devno);
+			ehc->i.action |= ATA_EH_SOFTRESET;
+		}
+	}
+
+ retry:
+	down_xfermask = 0;
+	rc = 0;
+
+	/* if UNLOADING, finish immediately */
+	if (ap->flags & ATA_FLAG_UNLOADING)
+		goto out;
+
+	/* skip EH if possible. */
+	if (ata_eh_skip_recovery(ap))
+		ehc->i.action = 0;
+
+	for (i = 0; i < ATA_MAX_DEVICES; i++)
+		ehc->classes[i] = ATA_DEV_UNKNOWN;
+
+	/* reset */
+	if (ehc->i.action & ATA_EH_RESET_MASK) {
+		ata_eh_freeze_port(ap);
+
+		rc = ata_eh_reset(ap, ata_port_nr_vacant(ap), prereset,
+				  softreset, hardreset, postreset);
+		if (rc) {
+			ata_port_printk(ap, KERN_ERR,
+					"reset failed, giving up\n");
+			goto out;
+		}
+
+		ata_eh_thaw_port(ap);
+	}
+
+	/* revalidate existing devices and attach new ones */
+	rc = ata_eh_revalidate_and_attach(ap, &dev);
+	if (rc)
+		goto dev_fail;
+
+	/* configure transfer mode if the port has been reset */
+	if (ehc->i.flags & ATA_EHI_DID_RESET) {
+		rc = ata_set_mode(ap, &dev);
+		if (rc) {
+			down_xfermask = 1;
+			goto dev_fail;
+		}
+	}
+
+	goto out;
+
+ dev_fail:
+	switch (rc) {
+	case -ENODEV:
+		/* device missing, schedule probing */
+		ehc->i.probe_mask |= (1 << dev->devno);
+	case -EINVAL:
+		ehc->tries[dev->devno] = 0;
+		break;
+	case -EIO:
+		sata_down_spd_limit(ap);
+	default:
+		ehc->tries[dev->devno]--;
+		if (down_xfermask &&
+		    ata_down_xfermask_limit(dev, ehc->tries[dev->devno] == 1))
+			ehc->tries[dev->devno] = 0;
+	}
+
+	if (ata_dev_enabled(dev) && !ehc->tries[dev->devno]) {
+		/* disable device if it has used up all its chances */
+		ata_dev_disable(dev);
+
+		/* detach if offline */
+		if (ata_port_offline(ap))
+			ata_eh_detach_dev(dev);
+
+		/* probe if requested */
+		if ((ehc->i.probe_mask & (1 << dev->devno)) &&
+		    !(ehc->did_probe_mask & (1 << dev->devno))) {
+			ata_eh_detach_dev(dev);
+			ata_dev_init(dev);
+
+			ehc->tries[dev->devno] = ATA_EH_DEV_TRIES;
+			ehc->did_probe_mask |= (1 << dev->devno);
+			ehc->i.action |= ATA_EH_SOFTRESET;
+		}
+	} else {
+		/* soft didn't work?  be haaaaard */
+		if (ehc->i.flags & ATA_EHI_DID_RESET)
+			ehc->i.action |= ATA_EH_HARDRESET;
+		else
+			ehc->i.action |= ATA_EH_SOFTRESET;
+	}
+
+	if (ata_port_nr_enabled(ap)) {
+		ata_port_printk(ap, KERN_WARNING, "failed to recover some "
+				"devices, retrying in 5 secs\n");
+		ssleep(5);
+	} else {
+		/* no device left, repeat fast */
+		msleep(500);
+	}
+
+	goto retry;
+
+ out:
+	if (rc) {
+		for (i = 0; i < ATA_MAX_DEVICES; i++)
+			ata_dev_disable(&ap->device[i]);
+	}
+
+	DPRINTK("EXIT, rc=%d\n", rc);
+	return rc;
+}
+
+/**
+ *	ata_eh_finish - finish up EH
+ *	@ap: host port to finish EH for
+ *
+ *	Recovery is complete.  Clean up EH states and retry or finish
+ *	failed qcs.
+ *
+ *	LOCKING:
+ *	None.
+ */
+static void ata_eh_finish(struct ata_port *ap)
+{
+	int tag;
+
+	/* retry or finish qcs */
+	for (tag = 0; tag < ATA_MAX_QUEUE; tag++) {
+		struct ata_queued_cmd *qc = __ata_qc_from_tag(ap, tag);
+
+		if (!(qc->flags & ATA_QCFLAG_FAILED))
+			continue;
+
+		if (qc->err_mask) {
+			/* FIXME: Once EH migration is complete,
+			 * generate sense data in this function,
+			 * considering both err_mask and tf.
+			 */
+			if (qc->err_mask & AC_ERR_INVALID)
+				ata_eh_qc_complete(qc);
+			else
+				ata_eh_qc_retry(qc);
+		} else {
+			if (qc->flags & ATA_QCFLAG_SENSE_VALID) {
+				ata_eh_qc_complete(qc);
+			} else {
+				/* feed zero TF to sense generation */
+				memset(&qc->result_tf, 0, sizeof(qc->result_tf));
+				ata_eh_qc_retry(qc);
+			}
+		}
+	}
+}
+
+/**
+ *	ata_do_eh - do standard error handling
+ *	@ap: host port to handle error for
+ *	@prereset: prereset method (can be NULL)
+ *	@softreset: softreset method (can be NULL)
+ *	@hardreset: hardreset method (can be NULL)
+ *	@postreset: postreset method (can be NULL)
+ *
+ *	Perform standard error handling sequence.
+ *
+ *	LOCKING:
+ *	Kernel thread context (may sleep).
+ */
+void ata_do_eh(struct ata_port *ap, ata_prereset_fn_t prereset,
+	       ata_reset_fn_t softreset, ata_reset_fn_t hardreset,
+	       ata_postreset_fn_t postreset)
+{
+	if (!(ap->flags & ATA_FLAG_LOADING)) {
+		ata_eh_autopsy(ap);
+		ata_eh_report(ap);
+	}
+
+	ata_eh_recover(ap, prereset, softreset, hardreset, postreset);
+	ata_eh_finish(ap);
+}