// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  libata-eh.c - libata error handling
 *
 *  Copyright 2006 Tejun Heo <htejun@gmail.com>
 *
 *  libata documentation is available via 'make {ps|pdf}docs',
 *  as Documentation/driver-api/libata.rst
 *
 *  Hardware documentation available from http://www.t13.org/ and
 *  http://www.sata-io.org/
 */

#include <linux/kernel.h>
#include <linux/blkdev.h>
#include <linux/export.h>
#include <linux/pci.h>
#include <scsi/scsi.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_eh.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_dbg.h>
#include "../scsi/scsi_transport_api.h"

#include <linux/libata.h>

#include <trace/events/libata.h>
#include "libata.h"

enum {
	/* speed down verdicts */
	ATA_EH_SPDN_NCQ_OFF		= (1 << 0),
	ATA_EH_SPDN_SPEED_DOWN		= (1 << 1),
	ATA_EH_SPDN_FALLBACK_TO_PIO	= (1 << 2),
	ATA_EH_SPDN_KEEP_ERRORS		= (1 << 3),

	/* error flags */
	ATA_EFLAG_IS_IO			= (1 << 0),
	ATA_EFLAG_DUBIOUS_XFER		= (1 << 1),
	ATA_EFLAG_OLD_ER                = (1 << 31),

	/* error categories */
	ATA_ECAT_NONE			= 0,
	ATA_ECAT_ATA_BUS		= 1,
	ATA_ECAT_TOUT_HSM		= 2,
	ATA_ECAT_UNK_DEV		= 3,
	ATA_ECAT_DUBIOUS_NONE		= 4,
	ATA_ECAT_DUBIOUS_ATA_BUS	= 5,
	ATA_ECAT_DUBIOUS_TOUT_HSM	= 6,
	ATA_ECAT_DUBIOUS_UNK_DEV	= 7,
	ATA_ECAT_NR			= 8,

	ATA_EH_CMD_DFL_TIMEOUT		=  5000,

	/* always put at least this amount of time between resets */
	ATA_EH_RESET_COOL_DOWN		=  5000,

	/* Waiting in ->prereset can never be reliable.  It's
	 * sometimes nice to wait there but it can't be depended upon;
	 * otherwise, we wouldn't be resetting.  Just give it enough
	 * time for most drives to spin up.
	 */
	ATA_EH_PRERESET_TIMEOUT		= 10000,
	ATA_EH_FASTDRAIN_INTERVAL	=  3000,

	ATA_EH_UA_TRIES			= 5,

	/* probe speed down parameters, see ata_eh_schedule_probe() */
	ATA_EH_PROBE_TRIAL_INTERVAL	= 60000,	/* 1 min */
	ATA_EH_PROBE_TRIALS		= 2,
};

/* The following table determines how we sequence resets.  Each entry
 * represents timeout for that try.  The first try can be soft or
 * hardreset.  All others are hardreset if available.  In most cases
 * the first reset w/ 10sec timeout should succeed.  Following entries
 * are mostly for error handling, hotplug and those outlier devices that
 * take an exceptionally long time to recover from reset.
 */
static const unsigned long ata_eh_reset_timeouts[] = {
	10000,	/* most drives spin up by 10sec */
	10000,	/* > 99% working drives spin up before 20sec */
	35000,	/* give > 30 secs of idleness for outlier devices */
	 5000,	/* and sweet one last chance */
	ULONG_MAX, /* > 1 min has elapsed, give up */
};

static const unsigned long ata_eh_identify_timeouts[] = {
	 5000,	/* covers > 99% of successes and not too boring on failures */
	10000,  /* combined time till here is enough even for media access */
	30000,	/* for true idiots */
	ULONG_MAX,
};

static const unsigned long ata_eh_flush_timeouts[] = {
	15000,	/* be generous with flush */
	15000,  /* ditto */
	30000,	/* and even more generous */
	ULONG_MAX,
};

static const unsigned long ata_eh_other_timeouts[] = {
	 5000,	/* same rationale as identify timeout */
	10000,	/* ditto */
	/* but no merciful 30sec for other commands, it just isn't worth it */
	ULONG_MAX,
};

struct ata_eh_cmd_timeout_ent {
	const u8		*commands;
	const unsigned long	*timeouts;
};

/* The following table determines timeouts to use for EH internal
 * commands.  Each table entry is a command class and matches the
 * commands the entry applies to and the timeout table to use.
 *
 * On the retry after a command timed out, the next timeout value from
 * the table is used.  If the table doesn't contain further entries,
 * the last value is used.
 *
 * ehc->cmd_timeout_idx keeps track of which timeout to use per
 * command class, so if SET_FEATURES times out on the first try, the
 * next try will use the second timeout value only for that class.
 */
#define CMDS(cmds...)	(const u8 []){ cmds, 0 }
static const struct ata_eh_cmd_timeout_ent
ata_eh_cmd_timeout_table[ATA_EH_CMD_TIMEOUT_TABLE_SIZE] = {
	{ .commands = CMDS(ATA_CMD_ID_ATA, ATA_CMD_ID_ATAPI),
	  .timeouts = ata_eh_identify_timeouts, },
	{ .commands = CMDS(ATA_CMD_READ_NATIVE_MAX, ATA_CMD_READ_NATIVE_MAX_EXT),
	  .timeouts = ata_eh_other_timeouts, },
	{ .commands = CMDS(ATA_CMD_SET_MAX, ATA_CMD_SET_MAX_EXT),
	  .timeouts = ata_eh_other_timeouts, },
	{ .commands = CMDS(ATA_CMD_SET_FEATURES),
	  .timeouts = ata_eh_other_timeouts, },
	{ .commands = CMDS(ATA_CMD_INIT_DEV_PARAMS),
	  .timeouts = ata_eh_other_timeouts, },
	{ .commands = CMDS(ATA_CMD_FLUSH, ATA_CMD_FLUSH_EXT),
	  .timeouts = ata_eh_flush_timeouts },
};
#undef CMDS

static void __ata_port_freeze(struct ata_port *ap);
#ifdef CONFIG_PM
static void ata_eh_handle_port_suspend(struct ata_port *ap);
static void ata_eh_handle_port_resume(struct ata_port *ap);
#else /* CONFIG_PM */
static void ata_eh_handle_port_suspend(struct ata_port *ap)
{ }

static void ata_eh_handle_port_resume(struct ata_port *ap)
{ }
#endif /* CONFIG_PM */

static __printf(2, 0) void __ata_ehi_pushv_desc(struct ata_eh_info *ehi,
				 const char *fmt, va_list args)
{
	ehi->desc_len += vscnprintf(ehi->desc + ehi->desc_len,
				     ATA_EH_DESC_LEN - ehi->desc_len,
				     fmt, args);
}

/**
 *	__ata_ehi_push_desc - push error description without adding separator
 *	@ehi: target EHI
 *	@fmt: printf format string
 *
 *	Format string according to @fmt and append it to @ehi->desc.
 *
 *	LOCKING:
 *	spin_lock_irqsave(host lock)
 */
void __ata_ehi_push_desc(struct ata_eh_info *ehi, const char *fmt, ...)
{
	va_list args;

	va_start(args, fmt);
	__ata_ehi_pushv_desc(ehi, fmt, args);
	va_end(args);
}
EXPORT_SYMBOL_GPL(__ata_ehi_push_desc);

/**
 *	ata_ehi_push_desc - push error description with separator
 *	@ehi: target EHI
 *	@fmt: printf format string
 *
 *	Format string according to @fmt and append it to @ehi->desc.
 *	If @ehi->desc is not empty, ", " is added in-between.
 *
 *	LOCKING:
 *	spin_lock_irqsave(host lock)
 */
void ata_ehi_push_desc(struct ata_eh_info *ehi, const char *fmt, ...)
{
	va_list args;

	if (ehi->desc_len)
		__ata_ehi_push_desc(ehi, ", ");

	va_start(args, fmt);
	__ata_ehi_pushv_desc(ehi, fmt, args);
	va_end(args);
}
EXPORT_SYMBOL_GPL(ata_ehi_push_desc);

/**
 *	ata_ehi_clear_desc - clean error description
 *	@ehi: target EHI
 *
 *	Clear @ehi->desc.
 *
 *	LOCKING:
 *	spin_lock_irqsave(host lock)
 */
void ata_ehi_clear_desc(struct ata_eh_info *ehi)
{
	ehi->desc[0] = '\0';
	ehi->desc_len = 0;
}
EXPORT_SYMBOL_GPL(ata_ehi_clear_desc);

/**
 *	ata_port_desc - append port description
 *	@ap: target ATA port
 *	@fmt: printf format string
 *
 *	Format string according to @fmt and append it to port
 *	description.  If port description is not empty, " " is added
 *	in-between.  This function is to be used while initializing
 *	ata_host.  The description is printed on host registration.
 *
 *	LOCKING:
 *	None.
 */
void ata_port_desc(struct ata_port *ap, const char *fmt, ...)
{
	va_list args;

	WARN_ON(!(ap->pflags & ATA_PFLAG_INITIALIZING));

	if (ap->link.eh_info.desc_len)
		__ata_ehi_push_desc(&ap->link.eh_info, " ");

	va_start(args, fmt);
	__ata_ehi_pushv_desc(&ap->link.eh_info, fmt, args);
	va_end(args);
}
EXPORT_SYMBOL_GPL(ata_port_desc);

#ifdef CONFIG_PCI
/**
 *	ata_port_pbar_desc - append PCI BAR description
 *	@ap: target ATA port
 *	@bar: target PCI BAR
 *	@offset: offset into PCI BAR
 *	@name: name of the area
 *
 *	If @offset is negative, this function formats a string which
 *	contains the name, address, size and type of the BAR and
 *	appends it to the port description.  If @offset is zero or
 *	positive, only name and offsetted address is appended.
 *
 *	LOCKING:
 *	None.
 */
void ata_port_pbar_desc(struct ata_port *ap, int bar, ssize_t offset,
			const char *name)
{
	struct pci_dev *pdev = to_pci_dev(ap->host->dev);
	char *type = "";
	unsigned long long start, len;

	if (pci_resource_flags(pdev, bar) & IORESOURCE_MEM)
		type = "m";
	else if (pci_resource_flags(pdev, bar) & IORESOURCE_IO)
		type = "i";

	start = (unsigned long long)pci_resource_start(pdev, bar);
	len = (unsigned long long)pci_resource_len(pdev, bar);

	if (offset < 0)
		ata_port_desc(ap, "%s %s%llu@0x%llx", name, type, len, start);
	else
		ata_port_desc(ap, "%s 0x%llx", name,
				start + (unsigned long long)offset);
}
EXPORT_SYMBOL_GPL(ata_port_pbar_desc);
#endif /* CONFIG_PCI */

static int ata_lookup_timeout_table(u8 cmd)
{
	int i;

	for (i = 0; i < ATA_EH_CMD_TIMEOUT_TABLE_SIZE; i++) {
		const u8 *cur;

		for (cur = ata_eh_cmd_timeout_table[i].commands; *cur; cur++)
			if (*cur == cmd)
				return i;
	}

	return -1;
}

/**
 *	ata_internal_cmd_timeout - determine timeout for an internal command
 *	@dev: target device
 *	@cmd: internal command to be issued
 *
 *	Determine timeout for internal command @cmd for @dev.
 *
 *	LOCKING:
 *	EH context.
 *
 *	RETURNS:
 *	Determined timeout.
 */
unsigned long ata_internal_cmd_timeout(struct ata_device *dev, u8 cmd)
{
	struct ata_eh_context *ehc = &dev->link->eh_context;
	int ent = ata_lookup_timeout_table(cmd);
	int idx;

	if (ent < 0)
		return ATA_EH_CMD_DFL_TIMEOUT;

	idx = ehc->cmd_timeout_idx[dev->devno][ent];
	return ata_eh_cmd_timeout_table[ent].timeouts[idx];
}

/**
 *	ata_internal_cmd_timed_out - notification for internal command timeout
 *	@dev: target device
 *	@cmd: internal command which timed out
 *
 *	Notify EH that internal command @cmd for @dev timed out.  This
 *	function should be called only for commands whose timeouts are
 *	determined using ata_internal_cmd_timeout().
 *
 *	LOCKING:
 *	EH context.
 */
void ata_internal_cmd_timed_out(struct ata_device *dev, u8 cmd)
{
	struct ata_eh_context *ehc = &dev->link->eh_context;
	int ent = ata_lookup_timeout_table(cmd);
	int idx;

	if (ent < 0)
		return;

	idx = ehc->cmd_timeout_idx[dev->devno][ent];
	if (ata_eh_cmd_timeout_table[ent].timeouts[idx + 1] != ULONG_MAX)
		ehc->cmd_timeout_idx[dev->devno][ent]++;
}

static void ata_ering_record(struct ata_ering *ering, unsigned int eflags,
			     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->eflags = eflags;
	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 ent;
	return NULL;
}

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 int ata_ering_clear_cb(struct ata_ering_entry *ent, void *void_arg)
{
	ent->eflags |= ATA_EFLAG_OLD_ER;
	return 0;
}

static void ata_ering_clear(struct ata_ering *ering)
{
	ata_ering_map(ering, ata_ering_clear_cb, NULL);
}

static unsigned int ata_eh_dev_action(struct ata_device *dev)
{
	struct ata_eh_context *ehc = &dev->link->eh_context;

	return ehc->i.action | ehc->i.dev_action[dev->devno];
}

static void ata_eh_clear_action(struct ata_link *link, struct ata_device *dev,
				struct ata_eh_info *ehi, unsigned int action)
{
	struct ata_device *tdev;

	if (!dev) {
		ehi->action &= ~action;
		ata_for_each_dev(tdev, link, ALL)
			ehi->dev_action[tdev->devno] &= ~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) {
			ata_for_each_dev(tdev, link, ALL)
				ehi->dev_action[tdev->devno] |=
					ehi->action & action;
			ehi->action &= ~action;
		}

		/* turn off the specified per-dev action */
		ehi->dev_action[dev->devno] &= ~action;
	}
}

/**
 *	ata_eh_acquire - acquire EH ownership
 *	@ap: ATA port to acquire EH ownership for
 *
 *	Acquire EH ownership for @ap.  This is the basic exclusion
 *	mechanism for ports sharing a host.  Only one port hanging off
 *	the same host can claim the ownership of EH.
 *
 *	LOCKING:
 *	EH context.
 */
void ata_eh_acquire(struct ata_port *ap)
{
	mutex_lock(&ap->host->eh_mutex);
	WARN_ON_ONCE(ap->host->eh_owner);
	ap->host->eh_owner = current;
}

/**
 *	ata_eh_release - release EH ownership
 *	@ap: ATA port to release EH ownership for
 *
 *	Release EH ownership for @ap if the caller.  The caller must
 *	have acquired EH ownership using ata_eh_acquire() previously.
 *
 *	LOCKING:
 *	EH context.
 */
void ata_eh_release(struct ata_port *ap)
{
	WARN_ON_ONCE(ap->host->eh_owner != current);
	ap->host->eh_owner = NULL;
	mutex_unlock(&ap->host->eh_mutex);
}

static void ata_eh_unload(struct ata_port *ap)
{
	struct ata_link *link;
	struct ata_device *dev;
	unsigned long flags;

	/* Restore SControl IPM and SPD for the next driver and
	 * disable attached devices.
	 */
	ata_for_each_link(link, ap, PMP_FIRST) {
		sata_scr_write(link, SCR_CONTROL, link->saved_scontrol & 0xff0);
		ata_for_each_dev(dev, link, ALL)
			ata_dev_disable(dev);
	}

	/* freeze and set UNLOADED */
	spin_lock_irqsave(ap->lock, flags);

	ata_port_freeze(ap);			/* won't be thawed */
	ap->pflags &= ~ATA_PFLAG_EH_PENDING;	/* clear pending from freeze */
	ap->pflags |= ATA_PFLAG_UNLOADED;

	spin_unlock_irqrestore(ap->lock, flags);
}

/**
 *	ata_scsi_error - SCSI layer error handler callback
 *	@host: SCSI host on which error occurred
 *
 *	Handles SCSI-layer-thrown error events.
 *
 *	LOCKING:
 *	Inherited from SCSI layer (none, can sleep)
 *
 *	RETURNS:
 *	Zero.
 */
void ata_scsi_error(struct Scsi_Host *host)
{
	struct ata_port *ap = ata_shost_to_port(host);
	unsigned long flags;
	LIST_HEAD(eh_work_q);

	DPRINTK("ENTER\n");

	spin_lock_irqsave(host->host_lock, flags);
	list_splice_init(&host->eh_cmd_q, &eh_work_q);
	spin_unlock_irqrestore(host->host_lock, flags);

	ata_scsi_cmd_error_handler(host, ap, &eh_work_q);

	/* If we timed raced normal completion and there is nothing to
	   recover nr_timedout == 0 why exactly are we doing error recovery ? */
	ata_scsi_port_error_handler(host, ap);

	/* finish or retry handled scmd's and clean up */
	WARN_ON(!list_empty(&eh_work_q));

	DPRINTK("EXIT\n");
}

/**
 * ata_scsi_cmd_error_handler - error callback for a list of commands
 * @host:	scsi host containing the port
 * @ap:		ATA port within the host
 * @eh_work_q:	list of commands to process
 *
 * process the given list of commands and return those finished to the
 * ap->eh_done_q.  This function is the first part of the libata error
 * handler which processes a given list of failed commands.
 */
void ata_scsi_cmd_error_handler(struct Scsi_Host *host, struct ata_port *ap,
				struct list_head *eh_work_q)
{
	int i;
	unsigned long flags;

	/* make sure sff pio task is not running */
	ata_sff_flush_pio_task(ap);

	/* synchronize with host 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 completions 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.
	 */
	spin_lock_irqsave(ap->lock, flags);
	if (ap->ops->error_handler) {
		struct scsi_cmnd *scmd, *tmp;
		int nr_timedout = 0;

		/* This must occur under the ap->lock as we don't want
		   a polled recovery to race the real interrupt handler

		   The lost_interrupt handler checks for any completed but
		   non-notified command and completes much like an IRQ handler.

		   We then fall into the error recovery code which will treat
		   this as if normal completion won the race */

		if (ap->ops->lost_interrupt)
			ap->ops->lost_interrupt(ap);

		list_for_each_entry_safe(scmd, tmp, eh_work_q, eh_entry) {
			struct ata_queued_cmd *qc;

			ata_qc_for_each_raw(ap, qc, 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);


		/* initialize eh_tries */
		ap->eh_tries = ATA_EH_MAX_TRIES;
	}
	spin_unlock_irqrestore(ap->lock, flags);

}
EXPORT_SYMBOL(ata_scsi_cmd_error_handler);

/**
 * ata_scsi_port_error_handler - recover the port after the commands
 * @host:	SCSI host containing the port
 * @ap:		the ATA port
 *
 * Handle the recovery of the port @ap after all the commands
 * have been recovered.
 */
void ata_scsi_port_error_handler(struct Scsi_Host *host, struct ata_port *ap)
{
	unsigned long flags;

	/* invoke error handler */
	if (ap->ops->error_handler) {
		struct ata_link *link;

		/* acquire EH ownership */
		ata_eh_acquire(ap);
 repeat:
		/* kill fast drain timer */
		del_timer_sync(&ap->fastdrain_timer);

		/* process port resume request */
		ata_eh_handle_port_resume(ap);

		/* fetch & clear EH info */
		spin_lock_irqsave(ap->lock, flags);

		ata_for_each_link(link, ap, HOST_FIRST) {
			struct ata_eh_context *ehc = &link->eh_context;
			struct ata_device *dev;

			memset(&link->eh_context, 0, sizeof(link->eh_context));
			link->eh_context.i = link->eh_info;
			memset(&link->eh_info, 0, sizeof(link->eh_info));

			ata_for_each_dev(dev, link, ENABLED) {
				int devno = dev->devno;

				ehc->saved_xfer_mode[devno] = dev->xfer_mode;
				if (ata_ncq_enabled(dev))
					ehc->saved_ncq_enabled |= 1 << devno;
			}
		}

		ap->pflags |= ATA_PFLAG_EH_IN_PROGRESS;
		ap->pflags &= ~ATA_PFLAG_EH_PENDING;
		ap->excl_link = NULL;	/* don't maintain exclusion over EH */

		spin_unlock_irqrestore(ap->lock, flags);

		/* invoke EH, skip if unloading or suspended */
		if (!(ap->pflags & (ATA_PFLAG_UNLOADING | ATA_PFLAG_SUSPENDED)))
			ap->ops->error_handler(ap);
		else {
			/* if unloading, commence suicide */
			if ((ap->pflags & ATA_PFLAG_UNLOADING) &&
			    !(ap->pflags & ATA_PFLAG_UNLOADED))
				ata_eh_unload(ap);
			ata_eh_finish(ap);
		}

		/* process port suspend request */
		ata_eh_handle_port_suspend(ap);

		/* Exception might have happened after ->error_handler
		 * recovered the port but before this point.  Repeat
		 * EH in such case.
		 */
		spin_lock_irqsave(ap->lock, flags);

		if (ap->pflags & ATA_PFLAG_EH_PENDING) {
			if (--ap->eh_tries) {
				spin_unlock_irqrestore(ap->lock, flags);
				goto repeat;
			}
			ata_port_err(ap,
				     "EH pending after %d tries, giving up\n",
				     ATA_EH_MAX_TRIES);
			ap->pflags &= ~ATA_PFLAG_EH_PENDING;
		}

		/* this run is complete, make sure EH info is clear */
		ata_for_each_link(link, ap, HOST_FIRST)
			memset(&link->eh_info, 0, sizeof(link->eh_info));

		/* end eh (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.
		 */
		ap->ops->end_eh(ap);

		spin_unlock_irqrestore(ap->lock, flags);
		ata_eh_release(ap);
	} else {
		WARN_ON(ata_qc_from_tag(ap, ap->link.active_tag) == NULL);
		ap->ops->eng_timeout(ap);
	}

	scsi_eh_flush_done_q(&ap->eh_done_q);

	/* clean up */
	spin_lock_irqsave(ap->lock, flags);

	if (ap->pflags & ATA_PFLAG_LOADING)
		ap->pflags &= ~ATA_PFLAG_LOADING;
	else if ((ap->pflags & ATA_PFLAG_SCSI_HOTPLUG) &&
		!(ap->flags & ATA_FLAG_SAS_HOST))
		schedule_delayed_work(&ap->hotplug_task, 0);

	if (ap->pflags & ATA_PFLAG_RECOVERED)
		ata_port_info(ap, "EH complete\n");

	ap->pflags &= ~(ATA_PFLAG_SCSI_HOTPLUG | ATA_PFLAG_RECOVERED);

	/* tell wait_eh that we're done */
	ap->pflags &= ~ATA_PFLAG_EH_IN_PROGRESS;
	wake_up_all(&ap->eh_wait_q);

	spin_unlock_irqrestore(ap->lock, flags);
}
EXPORT_SYMBOL_GPL(ata_scsi_port_error_handler);

/**
 *	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->pflags & (ATA_PFLAG_EH_PENDING | ATA_PFLAG_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->scsi_host)) {
		ata_msleep(ap, 10);
		goto retry;
	}
}
EXPORT_SYMBOL_GPL(ata_port_wait_eh);

static int ata_eh_nr_in_flight(struct ata_port *ap)
{
	struct ata_queued_cmd *qc;
	unsigned int tag;
	int nr = 0;

	/* count only non-internal commands */
	ata_qc_for_each(ap, qc, tag) {
		if (qc)
			nr++;
	}

	return nr;
}

void ata_eh_fastdrain_timerfn(struct timer_list *t)
{
	struct ata_port *ap = from_timer(ap, t, fastdrain_timer);
	unsigned long flags;
	int cnt;

	spin_lock_irqsave(ap->lock, flags);

	cnt = ata_eh_nr_in_flight(ap);

	/* are we done? */
	if (!cnt)
		goto out_unlock;

	if (cnt == ap->fastdrain_cnt) {
		struct ata_queued_cmd *qc;
		unsigned int tag;

		/* No progress during the last interval, tag all
		 * in-flight qcs as timed out and freeze the port.
		 */
		ata_qc_for_each(ap, qc, tag) {
			if (qc)
				qc->err_mask |= AC_ERR_TIMEOUT;
		}

		ata_port_freeze(ap);
	} else {
		/* some qcs have finished, give it another chance */
		ap->fastdrain_cnt = cnt;
		ap->fastdrain_timer.expires =
			ata_deadline(jiffies, ATA_EH_FASTDRAIN_INTERVAL);
		add_timer(&ap->fastdrain_timer);
	}

 out_unlock:
	spin_unlock_irqrestore(ap->lock, flags);
}

/**
 *	ata_eh_set_pending - set ATA_PFLAG_EH_PENDING and activate fast drain
 *	@ap: target ATA port
 *	@fastdrain: activate fast drain
 *
 *	Set ATA_PFLAG_EH_PENDING and activate fast drain if @fastdrain
 *	is non-zero and EH wasn't pending before.  Fast drain ensures
 *	that EH kicks in in timely manner.
 *
 *	LOCKING:
 *	spin_lock_irqsave(host lock)
 */
static void ata_eh_set_pending(struct ata_port *ap, int fastdrain)
{
	int cnt;

	/* already scheduled? */
	if (ap->pflags & ATA_PFLAG_EH_PENDING)
		return;

	ap->pflags |= ATA_PFLAG_EH_PENDING;

	if (!fastdrain)
		return;

	/* do we have in-flight qcs? */
	cnt = ata_eh_nr_in_flight(ap);
	if (!cnt)
		return;

	/* activate fast drain */
	ap->fastdrain_cnt = cnt;
	ap->fastdrain_timer.expires =
		ata_deadline(jiffies, ATA_EH_FASTDRAIN_INTERVAL);
	add_timer(&ap->fastdrain_timer);
}

/**
 *	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 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;
	ata_eh_set_pending(ap, 1);

	/* 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.
	 */
	blk_abort_request(qc->scsicmd->request);
}

/**
 * ata_std_sched_eh - non-libsas ata_ports issue eh with this common routine
 * @ap: ATA port to schedule EH for
 *
 *	LOCKING: inherited from ata_port_schedule_eh
 *	spin_lock_irqsave(host lock)
 */
void ata_std_sched_eh(struct ata_port *ap)
{
	WARN_ON(!ap->ops->error_handler);

	if (ap->pflags & ATA_PFLAG_INITIALIZING)
		return;

	ata_eh_set_pending(ap, 1);
	scsi_schedule_eh(ap->scsi_host);

	DPRINTK("port EH scheduled\n");
}
EXPORT_SYMBOL_GPL(ata_std_sched_eh);

/**
 * ata_std_end_eh - non-libsas ata_ports complete eh with this common routine
 * @ap: ATA port to end EH for
 *
 * In the libata object model there is a 1:1 mapping of ata_port to
 * shost, so host fields can be directly manipulated under ap->lock, in
 * the libsas case we need to hold a lock at the ha->level to coordinate
 * these events.
 *
 *	LOCKING:
 *	spin_lock_irqsave(host lock)
 */
void ata_std_end_eh(struct ata_port *ap)
{
	struct Scsi_Host *host = ap->scsi_host;

	host->host_eh_scheduled = 0;
}
EXPORT_SYMBOL(ata_std_end_eh);


/**
 *	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 lock)
 */
void ata_port_schedule_eh(struct ata_port *ap)
{
	/* see: ata_std_sched_eh, unless you know better */
	ap->ops->sched_eh(ap);
}
EXPORT_SYMBOL_GPL(ata_port_schedule_eh);

static int ata_do_link_abort(struct ata_port *ap, struct ata_link *link)
{
	struct ata_queued_cmd *qc;
	int tag, nr_aborted = 0;

	WARN_ON(!ap->ops->error_handler);

	/* we're gonna abort all commands, no need for fast drain */
	ata_eh_set_pending(ap, 0);

	/* include internal tag in iteration */
	ata_qc_for_each_with_internal(ap, qc, tag) {
		if (qc && (!link || qc->dev->link == link)) {
			qc->flags |= ATA_QCFLAG_FAILED;
			ata_qc_complete(qc);
			nr_aborted++;
		}
	}

	if (!nr_aborted)
		ata_port_schedule_eh(ap);

	return nr_aborted;
}

/**
 *	ata_link_abort - abort all qc's on the link
 *	@link: ATA link to abort qc's for
 *
 *	Abort all active qc's active on @link and schedule EH.
 *
 *	LOCKING:
 *	spin_lock_irqsave(host lock)
 *
 *	RETURNS:
 *	Number of aborted qc's.
 */
int ata_link_abort(struct ata_link *link)
{
	return ata_do_link_abort(link->ap, link);
}
EXPORT_SYMBOL_GPL(ata_link_abort);

/**
 *	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)
{
	return ata_do_link_abort(ap, NULL);
}
EXPORT_SYMBOL_GPL(ata_port_abort);

/**
 *	__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 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->pflags |= ATA_PFLAG_FROZEN;

	DPRINTK("ata%u port frozen\n", ap->print_id);
}

/**
 *	ata_port_freeze - abort & freeze port
 *	@ap: ATA port to freeze
 *
 *	Abort and freeze @ap.  The freeze operation must be called
 *	first, because some hardware requires special operations
 *	before the taskfile registers are accessible.
 *
 *	LOCKING:
 *	spin_lock_irqsave(host lock)
 *
 *	RETURNS:
 *	Number of aborted commands.
 */
int ata_port_freeze(struct ata_port *ap)
{
	int nr_aborted;

	WARN_ON(!ap->ops->error_handler);

	__ata_port_freeze(ap);
	nr_aborted = ata_port_abort(ap);

	return nr_aborted;
}
EXPORT_SYMBOL_GPL(ata_port_freeze);

/**
 *	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);
}
EXPORT_SYMBOL_GPL(ata_eh_freeze_port);

/**
 *	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->pflags &= ~ATA_PFLAG_FROZEN;

	if (ap->ops->thaw)
		ap->ops->thaw(ap);

	spin_unlock_irqrestore(ap->lock, flags);

	DPRINTK("ata%u port thawed\n", ap->print_id);
}

static void ata_eh_scsidone(struct scsi_cmnd *scmd)
{
	/* nada */
}

static void __ata_eh_qc_complete(struct ata_queued_cmd *qc)
{
	struct ata_port *ap = qc->ap;
	struct scsi_cmnd *scmd = qc->scsicmd;
	unsigned long 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->lock, flags);

	scsi_eh_finish_cmd(scmd, &ap->eh_done_q);
}

/**
 *	ata_eh_qc_complete - Complete an active ATA command from EH
 *	@qc: Command to complete
 *
 *	Indicate to the mid and upper layers that an ATA command has
 *	completed.  To be used from EH.
 */
void ata_eh_qc_complete(struct ata_queued_cmd *qc)
{
	struct scsi_cmnd *scmd = qc->scsicmd;
	scmd->retries = scmd->allowed;
	__ata_eh_qc_complete(qc);
}

/**
 *	ata_eh_qc_retry - Tell midlayer to retry an ATA command after EH
 *	@qc: Command to retry
 *
 *	Indicate to the mid and upper layers that an ATA command
 *	should be retried.  To be used from EH.
 *
 *	SCSI midlayer limits the number of retries to scmd->allowed.
 *	scmd->allowed is incremented for commands which get retried
 *	due to unrelated failures (qc->err_mask is zero).
 */
void ata_eh_qc_retry(struct ata_queued_cmd *qc)
{
	struct scsi_cmnd *scmd = qc->scsicmd;
	if (!qc->err_mask)
		scmd->allowed++;
	__ata_eh_qc_complete(qc);
}

/**
 *	ata_dev_disable - disable ATA device
 *	@dev: ATA device to disable
 *
 *	Disable @dev.
 *
 *	Locking:
 *	EH context.
 */
void ata_dev_disable(struct ata_device *dev)
{
	if (!ata_dev_enabled(dev))
		return;

	if (ata_msg_drv(dev->link->ap))
		ata_dev_warn(dev, "disabled\n");
	ata_acpi_on_disable(dev);
	ata_down_xfermask_limit(dev, ATA_DNXFER_FORCE_PIO0 | ATA_DNXFER_QUIET);
	dev->class++;

	/* From now till the next successful probe, ering is used to
	 * track probe failures.  Clear accumulated device error info.
	 */
	ata_ering_clear(&dev->ering);
}
EXPORT_SYMBOL_GPL(ata_dev_disable);

/**
 *	ata_eh_detach_dev - detach ATA device
 *	@dev: ATA device to detach
 *
 *	Detach @dev.
 *
 *	LOCKING:
 *	None.
 */
void ata_eh_detach_dev(struct ata_device *dev)
{
	struct ata_link *link = dev->link;
	struct ata_port *ap = link->ap;
	struct ata_eh_context *ehc = &link->eh_context;
	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->pflags |= ATA_PFLAG_SCSI_HOTPLUG;
	}

	/* clear per-dev EH info */
	ata_eh_clear_action(link, dev, &link->eh_info, ATA_EH_PERDEV_MASK);
	ata_eh_clear_action(link, dev, &link->eh_context.i, ATA_EH_PERDEV_MASK);
	ehc->saved_xfer_mode[dev->devno] = 0;
	ehc->saved_ncq_enabled &= ~(1 << dev->devno);

	spin_unlock_irqrestore(ap->lock, flags);
}

/**
 *	ata_eh_about_to_do - about to perform eh_action
 *	@link: target ATA link
 *	@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 @link->eh_info such that eh actions are not unnecessarily
 *	repeated.
 *
 *	LOCKING:
 *	None.
 */
void ata_eh_about_to_do(struct ata_link *link, struct ata_device *dev,
			unsigned int action)
{
	struct ata_port *ap = link->ap;
	struct ata_eh_info *ehi = &link->eh_info;
	struct ata_eh_context *ehc = &link->eh_context;
	unsigned long flags;

	spin_lock_irqsave(ap->lock, flags);

	ata_eh_clear_action(link, dev, ehi, action);

	/* About to take EH action, set RECOVERED.  Ignore actions on
	 * slave links as master will do them again.
	 */
	if (!(ehc->i.flags & ATA_EHI_QUIET) && link != ap->slave_link)
		ap->pflags |= ATA_PFLAG_RECOVERED;

	spin_unlock_irqrestore(ap->lock, flags);
}

/**
 *	ata_eh_done - EH action complete
 *	@link: ATA link for which EH actions are complete
 *	@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 @link->eh_context.
 *
 *	LOCKING:
 *	None.
 */
void ata_eh_done(struct ata_link *link, struct ata_device *dev,
		 unsigned int action)
{
	struct ata_eh_context *ehc = &link->eh_context;

	ata_eh_clear_action(link, dev, &ehc->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";
	if (err_mask & AC_ERR_NCQ)
		return "NCQ error";
	if (err_mask & AC_ERR_NODEV_HINT)
		return "Polling detection error";
	return "unknown error";
}

/**
 *	atapi_eh_tur - perform ATAPI TEST_UNIT_READY
 *	@dev: target ATAPI device
 *	@r_sense_key: out parameter for sense_key
 *
 *	Perform ATAPI TEST_UNIT_READY.
 *
 *	LOCKING:
 *	EH context (may sleep).
 *
 *	RETURNS:
 *	0 on success, AC_ERR_* mask on failure.
 */
unsigned int atapi_eh_tur(struct ata_device *dev, u8 *r_sense_key)
{
	u8 cdb[ATAPI_CDB_LEN] = { TEST_UNIT_READY, 0, 0, 0, 0, 0 };
	struct ata_taskfile tf;
	unsigned int err_mask;

	ata_tf_init(dev, &tf);

	tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
	tf.command = ATA_CMD_PACKET;
	tf.protocol = ATAPI_PROT_NODATA;

	err_mask = ata_exec_internal(dev, &tf, cdb, DMA_NONE, NULL, 0, 0);
	if (err_mask == AC_ERR_DEV)
		*r_sense_key = tf.feature >> 4;
	return err_mask;
}

/**
 *	ata_eh_request_sense - perform REQUEST_SENSE_DATA_EXT
 *	@qc: qc to perform REQUEST_SENSE_SENSE_DATA_EXT to
 *	@cmd: scsi command for which the sense code should be set
 *
 *	Perform REQUEST_SENSE_DATA_EXT after the device reported CHECK
 *	SENSE.  This function is an EH helper.
 *
 *	LOCKING:
 *	Kernel thread context (may sleep).
 */
static void ata_eh_request_sense(struct ata_queued_cmd *qc,
				 struct scsi_cmnd *cmd)
{
	struct ata_device *dev = qc->dev;
	struct ata_taskfile tf;
	unsigned int err_mask;

	if (qc->ap->pflags & ATA_PFLAG_FROZEN) {
		ata_dev_warn(dev, "sense data available but port frozen\n");
		return;
	}

	if (!cmd || qc->flags & ATA_QCFLAG_SENSE_VALID)
		return;

	if (!ata_id_sense_reporting_enabled(dev->id)) {
		ata_dev_warn(qc->dev, "sense data reporting disabled\n");
		return;
	}

	DPRINTK("ATA request sense\n");

	ata_tf_init(dev, &tf);
	tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
	tf.flags |= ATA_TFLAG_LBA | ATA_TFLAG_LBA48;
	tf.command = ATA_CMD_REQ_SENSE_DATA;
	tf.protocol = ATA_PROT_NODATA;

	err_mask = ata_exec_internal(dev, &tf, NULL, DMA_NONE, NULL, 0, 0);
	/* Ignore err_mask; ATA_ERR might be set */
	if (tf.command & ATA_SENSE) {
		ata_scsi_set_sense(dev, cmd, tf.lbah, tf.lbam, tf.lbal);
		qc->flags |= ATA_QCFLAG_SENSE_VALID;
	} else {
		ata_dev_warn(dev, "request sense failed stat %02x emask %x\n",
			     tf.command, err_mask);
	}
}

/**
 *	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)
 *	@dfl_sense_key: default sense key to use
 *
 *	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
 */
unsigned int atapi_eh_request_sense(struct ata_device *dev,
					   u8 *sense_buf, u8 dfl_sense_key)
{
	u8 cdb[ATAPI_CDB_LEN] =
		{ REQUEST_SENSE, 0, 0, 0, SCSI_SENSE_BUFFERSIZE, 0 };
	struct ata_port *ap = dev->link->ap;
	struct ata_taskfile tf;

	DPRINTK("ATAPI request sense\n");

	memset(sense_buf, 0, SCSI_SENSE_BUFFERSIZE);

	/* initialize sense_buf with the error register,
	 * for the case where they are -not- overwritten
	 */
	sense_buf[0] = 0x70;
	sense_buf[2] = dfl_sense_key;

	/* some devices time out if garbage left in tf */
	ata_tf_init(dev, &tf);

	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 = ATAPI_PROT_DMA;
		tf.feature |= ATAPI_PKT_DMA;
	} else {
		tf.protocol = ATAPI_PROT_PIO;
		tf.lbam = SCSI_SENSE_BUFFERSIZE;
		tf.lbah = 0;
	}

	return ata_exec_internal(dev, &tf, cdb, DMA_FROM_DEVICE,
				 sense_buf, SCSI_SENSE_BUFFERSIZE, 0);
}

/**
 *	ata_eh_analyze_serror - analyze SError for a failed port
 *	@link: ATA link to analyze SError for
 *
 *	Analyze SError if available and further determine cause of
 *	failure.
 *
 *	LOCKING:
 *	None.
 */
static void ata_eh_analyze_serror(struct ata_link *link)
{
	struct ata_eh_context *ehc = &link->eh_context;
	u32 serror = ehc->i.serror;
	unsigned int err_mask = 0, action = 0;
	u32 hotplug_mask;

	if (serror & (SERR_PERSISTENT | SERR_DATA)) {
		err_mask |= AC_ERR_ATA_BUS;
		action |= ATA_EH_RESET;
	}
	if (serror & SERR_PROTOCOL) {
		err_mask |= AC_ERR_HSM;
		action |= ATA_EH_RESET;
	}
	if (serror & SERR_INTERNAL) {
		err_mask |= AC_ERR_SYSTEM;
		action |= ATA_EH_RESET;
	}

	/* Determine whether a hotplug event has occurred.  Both
	 * SError.N/X are considered hotplug events for enabled or
	 * host links.  For disabled PMP links, only N bit is
	 * considered as X bit is left at 1 for link plugging.
	 */
	if (link->lpm_policy > ATA_LPM_MAX_POWER)
		hotplug_mask = 0;	/* hotplug doesn't work w/ LPM */
	else if (!(link->flags & ATA_LFLAG_DISABLED) || ata_is_host_link(link))
		hotplug_mask = SERR_PHYRDY_CHG | SERR_DEV_XCHG;
	else
		hotplug_mask = SERR_PHYRDY_CHG;

	if (serror & hotplug_mask)
		ata_ehi_hotplugged(&ehc->i);

	ehc->i.err_mask |= err_mask;
	ehc->i.action |= action;
}

/**
 *	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
 *	available.
 *
 *	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_RESET;
	}

	if (stat & (ATA_ERR | ATA_DF)) {
		qc->err_mask |= AC_ERR_DEV;
		/*
		 * Sense data reporting does not work if the
		 * device fault bit is set.
		 */
		if (stat & ATA_DF)
			stat &= ~ATA_SENSE;
	} else {
		return 0;
	}

	switch (qc->dev->class) {
	case ATA_DEV_ZAC:
		if (stat & ATA_SENSE)
			ata_eh_request_sense(qc, qc->scsicmd);
		/* fall through */
	case ATA_DEV_ATA:
		if (err & ATA_ICRC)
			qc->err_mask |= AC_ERR_ATA_BUS;
		if (err & (ATA_UNC | ATA_AMNF))
			qc->err_mask |= AC_ERR_MEDIA;
		if (err & ATA_IDNF)
			qc->err_mask |= AC_ERR_INVALID;
		break;

	case ATA_DEV_ATAPI:
		if (!(qc->ap->pflags & ATA_PFLAG_FROZEN)) {
			tmp = atapi_eh_request_sense(qc->dev,
						qc->scsicmd->sense_buffer,
						qc->result_tf.feature >> 4);
			if (!tmp)
				qc->flags |= ATA_QCFLAG_SENSE_VALID;
			else
				qc->err_mask |= tmp;
		}
	}

	if (qc->flags & ATA_QCFLAG_SENSE_VALID) {
		int ret = scsi_check_sense(qc->scsicmd);
		/*
		 * SUCCESS here means that the sense code could be
		 * evaluated and should be passed to the upper layers
		 * for correct evaluation.
		 * FAILED means the sense code could not be interpreted
		 * and the device would need to be reset.
		 * NEEDS_RETRY and ADD_TO_MLQUEUE means that the
		 * command would need to be retried.
		 */
		if (ret == NEEDS_RETRY || ret == ADD_TO_MLQUEUE) {
			qc->flags |= ATA_QCFLAG_RETRY;
			qc->err_mask |= AC_ERR_OTHER;
		} else if (ret != SUCCESS) {
			qc->err_mask |= AC_ERR_HSM;
		}
	}
	if (qc->err_mask & (AC_ERR_HSM | AC_ERR_TIMEOUT | AC_ERR_ATA_BUS))
		action |= ATA_EH_RESET;

	return action;
}

static int ata_eh_categorize_error(unsigned int eflags, unsigned int err_mask,
				   int *xfer_ok)
{
	int base = 0;

	if (!(eflags & ATA_EFLAG_DUBIOUS_XFER))
		*xfer_ok = 1;

	if (!*xfer_ok)
		base = ATA_ECAT_DUBIOUS_NONE;

	if (err_mask & AC_ERR_ATA_BUS)
		return base + ATA_ECAT_ATA_BUS;

	if (err_mask & AC_ERR_TIMEOUT)
		return base + ATA_ECAT_TOUT_HSM;

	if (eflags & ATA_EFLAG_IS_IO) {
		if (err_mask & AC_ERR_HSM)
			return base + ATA_ECAT_TOUT_HSM;
		if ((err_mask &
		     (AC_ERR_DEV|AC_ERR_MEDIA|AC_ERR_INVALID)) == AC_ERR_DEV)
			return base + ATA_ECAT_UNK_DEV;
	}

	return 0;
}

struct speed_down_verdict_arg {
	u64 since;
	int xfer_ok;
	int nr_errors[ATA_ECAT_NR];
};

static int speed_down_verdict_cb(struct ata_ering_entry *ent, void *void_arg)
{
	struct speed_down_verdict_arg *arg = void_arg;
	int cat;

	if ((ent->eflags & ATA_EFLAG_OLD_ER) || (ent->timestamp < arg->since))
		return -1;

	cat = ata_eh_categorize_error(ent->eflags, ent->err_mask,
				      &arg->xfer_ok);
	arg->nr_errors[cat]++;

	return 0;
}

/**
 *	ata_eh_speed_down_verdict - Determine speed down verdict
 *	@dev: Device of interest
 *
 *	This function examines error ring of @dev and determines
 *	whether NCQ needs to be turned off, transfer speed should be
 *	stepped down, or falling back to PIO is necessary.
 *
 *	ECAT_ATA_BUS	: ATA_BUS error for any command
 *
 *	ECAT_TOUT_HSM	: TIMEOUT for any command or HSM violation for
 *			  IO commands
 *
 *	ECAT_UNK_DEV	: Unknown DEV error for IO commands
 *
 *	ECAT_DUBIOUS_*	: Identical to above three but occurred while
 *			  data transfer hasn't been verified.
 *
 *	Verdicts are
 *
 *	NCQ_OFF		: Turn off NCQ.
 *
 *	SPEED_DOWN	: Speed down transfer speed but don't fall back
 *			  to PIO.
 *
 *	FALLBACK_TO_PIO	: Fall back to PIO.
 *
 *	Even if multiple verdicts are returned, only one action is
 *	taken per error.  An action triggered by non-DUBIOUS errors
 *	clears ering, while one triggered by DUBIOUS_* errors doesn't.
 *	This is to expedite speed down decisions right after device is
 *	initially configured.
 *
 *	The following are speed down rules.  #1 and #2 deal with
 *	DUBIOUS errors.
 *
 *	1. If more than one DUBIOUS_ATA_BUS or DUBIOUS_TOUT_HSM errors
 *	   occurred during last 5 mins, SPEED_DOWN and FALLBACK_TO_PIO.
 *
 *	2. If more than one DUBIOUS_TOUT_HSM or DUBIOUS_UNK_DEV errors
 *	   occurred during last 5 mins, NCQ_OFF.
 *
 *	3. If more than 8 ATA_BUS, TOUT_HSM or UNK_DEV errors
 *	   occurred during last 5 mins, FALLBACK_TO_PIO
 *
 *	4. If more than 3 TOUT_HSM or UNK_DEV errors occurred
 *	   during last 10 mins, NCQ_OFF.
 *
 *	5. If more than 3 ATA_BUS or TOUT_HSM errors, or more than 6
 *	   UNK_DEV errors occurred during last 10 mins, SPEED_DOWN.
 *
 *	LOCKING:
 *	Inherited from caller.
 *
 *	RETURNS:
 *	OR of ATA_EH_SPDN_* flags.
 */
static unsigned int ata_eh_speed_down_verdict(struct ata_device *dev)
{
	const u64 j5mins = 5LLU * 60 * HZ, j10mins = 10LLU * 60 * HZ;
	u64 j64 = get_jiffies_64();
	struct speed_down_verdict_arg arg;
	unsigned int verdict = 0;

	/* scan past 5 mins of error history */
	memset(&arg, 0, sizeof(arg));
	arg.since = j64 - min(j64, j5mins);
	ata_ering_map(&dev->ering, speed_down_verdict_cb, &arg);

	if (arg.nr_errors[ATA_ECAT_DUBIOUS_ATA_BUS] +
	    arg.nr_errors[ATA_ECAT_DUBIOUS_TOUT_HSM] > 1)
		verdict |= ATA_EH_SPDN_SPEED_DOWN |
			ATA_EH_SPDN_FALLBACK_TO_PIO | ATA_EH_SPDN_KEEP_ERRORS;

	if (arg.nr_errors[ATA_ECAT_DUBIOUS_TOUT_HSM] +
	    arg.nr_errors[ATA_ECAT_DUBIOUS_UNK_DEV] > 1)
		verdict |= ATA_EH_SPDN_NCQ_OFF | ATA_EH_SPDN_KEEP_ERRORS;

	if (arg.nr_errors[ATA_ECAT_ATA_BUS] +
	    arg.nr_errors[ATA_ECAT_TOUT_HSM] +
	    arg.nr_errors[ATA_ECAT_UNK_DEV] > 6)
		verdict |= ATA_EH_SPDN_FALLBACK_TO_PIO;

	/* scan past 10 mins of error history */
	memset(&arg, 0, sizeof(arg));
	arg.since = j64 - min(j64, j10mins);
	ata_ering_map(&dev->ering, speed_down_verdict_cb, &arg);

	if (arg.nr_errors[ATA_ECAT_TOUT_HSM] +
	    arg.nr_errors[ATA_ECAT_UNK_DEV] > 3)
		verdict |= ATA_EH_SPDN_NCQ_OFF;

	if (arg.nr_errors[ATA_ECAT_ATA_BUS] +
	    arg.nr_errors[ATA_ECAT_TOUT_HSM] > 3 ||
	    arg.nr_errors[ATA_ECAT_UNK_DEV] > 6)
		verdict |= ATA_EH_SPDN_SPEED_DOWN;

	return verdict;
}

/**
 *	ata_eh_speed_down - record error and speed down if necessary
 *	@dev: Failed device
 *	@eflags: mask of ATA_EFLAG_* flags
 *	@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:
 *	Determined recovery action.
 */
static unsigned int ata_eh_speed_down(struct ata_device *dev,
				unsigned int eflags, unsigned int err_mask)
{
	struct ata_link *link = ata_dev_phys_link(dev);
	int xfer_ok = 0;
	unsigned int verdict;
	unsigned int action = 0;

	/* don't bother if Cat-0 error */
	if (ata_eh_categorize_error(eflags, err_mask, &xfer_ok) == 0)
		return 0;

	/* record error and determine whether speed down is necessary */
	ata_ering_record(&dev->ering, eflags, err_mask);
	verdict = ata_eh_speed_down_verdict(dev);

	/* turn off NCQ? */
	if ((verdict & ATA_EH_SPDN_NCQ_OFF) &&
	    (dev->flags & (ATA_DFLAG_PIO | ATA_DFLAG_NCQ |
			   ATA_DFLAG_NCQ_OFF)) == ATA_DFLAG_NCQ) {
		dev->flags |= ATA_DFLAG_NCQ_OFF;
		ata_dev_warn(dev, "NCQ disabled due to excessive errors\n");
		goto done;
	}

	/* speed down? */
	if (verdict & ATA_EH_SPDN_SPEED_DOWN) {
		/* speed down SATA link speed if possible */
		if (sata_down_spd_limit(link, 0) == 0) {
			action |= ATA_EH_RESET;
			goto done;
		}

		/* lower transfer mode */
		if (dev->spdn_cnt < 2) {
			static const int dma_dnxfer_sel[] =
				{ ATA_DNXFER_DMA, ATA_DNXFER_40C };
			static const int pio_dnxfer_sel[] =
				{ ATA_DNXFER_PIO, ATA_DNXFER_FORCE_PIO0 };
			int sel;

			if (dev->xfer_shift != ATA_SHIFT_PIO)
				sel = dma_dnxfer_sel[dev->spdn_cnt];
			else
				sel = pio_dnxfer_sel[dev->spdn_cnt];

			dev->spdn_cnt++;

			if (ata_down_xfermask_limit(dev, sel) == 0) {
				action |= ATA_EH_RESET;
				goto done;
			}
		}
	}

	/* Fall back to PIO?  Slowing down to PIO is meaningless for
	 * SATA ATA devices.  Consider it only for PATA and SATAPI.
	 */
	if ((verdict & ATA_EH_SPDN_FALLBACK_TO_PIO) && (dev->spdn_cnt >= 2) &&
	    (link->ap->cbl != ATA_CBL_SATA || dev->class == ATA_DEV_ATAPI) &&
	    (dev->xfer_shift != ATA_SHIFT_PIO)) {
		if (ata_down_xfermask_limit(dev, ATA_DNXFER_FORCE_PIO) == 0) {
			dev->spdn_cnt = 0;
			action |= ATA_EH_RESET;
			goto done;
		}
	}

	return 0;
 done:
	/* device has been slowed down, blow error history */
	if (!(verdict & ATA_EH_SPDN_KEEP_ERRORS))
		ata_ering_clear(&dev->ering);
	return action;
}

/**
 *	ata_eh_worth_retry - analyze error and decide whether to retry
 *	@qc: qc to possibly retry
 *
 *	Look at the cause of the error and decide if a retry
 * 	might be useful or not.  We don't want to retry media errors
 *	because the drive itself has probably already taken 10-30 seconds
 *	doing its own internal retries before reporting the failure.
 */
static inline int ata_eh_worth_retry(struct ata_queued_cmd *qc)
{
	if (qc->err_mask & AC_ERR_MEDIA)
		return 0;	/* don't retry media errors */
	if (qc->flags & ATA_QCFLAG_IO)
		return 1;	/* otherwise retry anything from fs stack */
	if (qc->err_mask & AC_ERR_INVALID)
		return 0;	/* don't retry these */
	return qc->err_mask != AC_ERR_DEV;  /* retry if not dev error */
}

/**
 *      ata_eh_quiet - check if we need to be quiet about a command error
 *      @qc: qc to check
 *
 *      Look at the qc flags anbd its scsi command request flags to determine
 *      if we need to be quiet about the command failure.
 */
static inline bool ata_eh_quiet(struct ata_queued_cmd *qc)
{
	if (qc->scsicmd &&
	    qc->scsicmd->request->rq_flags & RQF_QUIET)
		qc->flags |= ATA_QCFLAG_QUIET;
	return qc->flags & ATA_QCFLAG_QUIET;
}

/**
 *	ata_eh_link_autopsy - analyze error and determine recovery action
 *	@link: host link to perform autopsy on
 *
 *	Analyze why @link failed and determine which recovery actions
 *	are 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_link_autopsy(struct ata_link *link)
{
	struct ata_port *ap = link->ap;
	struct ata_eh_context *ehc = &link->eh_context;
	struct ata_queued_cmd *qc;
	struct ata_device *dev;
	unsigned int all_err_mask = 0, eflags = 0;…