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libata-eh.c

/*
 *  libata-eh.c - libata error handling
 *
 *  Maintained by:  Jeff Garzik <jgarzik@pobox.com>
 *                    Please ALWAYS copy linux-ide@vger.kernel.org
 *              on emails.
 *
 *  Copyright 2006 Tejun Heo <htejun@gmail.com>
 *
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License as
 *  published by the Free Software Foundation; either version 2, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; see the file COPYING.  If not, write to
 *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139,
 *  USA.
 *
 *
 *  libata documentation is available via 'make {ps|pdf}docs',
 *  as Documentation/DocBook/libata.*
 *
 *  Hardware documentation available from http://www.t13.org/ and
 *  http://www.sata-io.org/
 *
 */

#include <linux/kernel.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_transport_api.h"

#include <linux/libata.h>

#include "libata.h"

enum {
      ATA_EH_SPDN_NCQ_OFF           = (1 << 0),
      ATA_EH_SPDN_SPEED_DOWN        = (1 << 1),
      ATA_EH_SPDN_FALLBACK_TO_PIO   = (1 << 2),
};

/* 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.
 */
enum {
      ATA_EH_PRERESET_TIMEOUT       = 10 * HZ,
      ATA_EH_FASTDRAIN_INTERVAL     = 3 * HZ,
};

/* 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 retarded devices.
 */
static const unsigned long ata_eh_reset_timeouts[] = {
      10 * HZ,    /* most drives spin up by 10sec */
      10 * HZ,    /* > 99% working drives spin up before 20sec */
      35 * HZ,    /* give > 30 secs of idleness for retarded devices */
      5 * HZ,           /* and sweet one last chance */
      /* > 1 min has elapsed, give up */
};

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 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);
}

/**
 *    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);
}

/**
 *    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;
}

/**
 *    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);
}

#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 + offset);
}

#endif /* CONFIG_PCI */

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 void ata_ering_clear(struct ata_ering *ering)
{
      memset(ering, 0, sizeof(*ering));
}

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->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_link_for_each_dev(tdev, link)
                  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_link_for_each_dev(tdev, link)
                        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_scsi_timed_out - SCSI layer time out callback
 *    @cmd: timed out SCSI command
 *
 *    Handles SCSI layer timeout.  We race with normal completion of
 *    the qc for @cmd.  If the qc is already gone, we lose and let
 *    the scsi command finish (EH_HANDLED).  Otherwise, the qc has
 *    timed out and EH should be invoked.  Prevent ata_qc_complete()
 *    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
 *
 *    RETURNS:
 *    EH_HANDLED or EH_NOT_HANDLED
 */
enum scsi_eh_timer_return ata_scsi_timed_out(struct scsi_cmnd *cmd)
{
      struct Scsi_Host *host = cmd->device->host;
      struct ata_port *ap = ata_shost_to_port(host);
      unsigned long flags;
      struct ata_queued_cmd *qc;
      enum scsi_eh_timer_return ret;

      DPRINTK("ENTER\n");

      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->link.active_tag);
      if (qc) {
            WARN_ON(qc->scsicmd != cmd);
            qc->flags |= ATA_QCFLAG_EH_SCHEDULED;
            qc->err_mask |= AC_ERR_TIMEOUT;
            ret = EH_NOT_HANDLED;
      }
      spin_unlock_irqrestore(ap->lock, flags);

 out:
      DPRINTK("EXIT, ret=%d\n", ret);
      return ret;
}

/**
 *    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);
      int i;
      unsigned long flags;

      DPRINTK("ENTER\n");

      /* synchronize with port task */
      ata_port_flush_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 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;

            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);

            /* initialize eh_tries */
            ap->eh_tries = ATA_EH_MAX_TRIES;
      } else
            spin_unlock_wait(ap->lock);

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

            /* 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_port_for_each_link(link, ap) {
                  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));
            }

            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
                  ata_eh_finish(ap);

            /* process port suspend request */
            ata_eh_handle_port_suspend(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->pflags & ATA_PFLAG_EH_PENDING) {
                  if (--ap->eh_tries) {
                        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_TRIES);
                  ap->pflags &= ~ATA_PFLAG_EH_PENDING;
            }

            /* this run is complete, make sure EH info is clear */
            __ata_port_for_each_link(link, ap)
                  memset(&link->eh_info, 0, sizeof(link->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->link.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->pflags & ATA_PFLAG_LOADING)
            ap->pflags &= ~ATA_PFLAG_LOADING;
      else if (ap->pflags & ATA_PFLAG_SCSI_HOTPLUG)
            queue_delayed_work(ata_aux_wq, &ap->hotplug_task, 0);

      if (ap->pflags & ATA_PFLAG_RECOVERED)
            ata_port_printk(ap, KERN_INFO, "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);

      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->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)) {
            msleep(10);
            goto retry;
      }
}

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

      /* count only non-internal commands */
      for (tag = 0; tag < ATA_MAX_QUEUE - 1; tag++)
            if (ata_qc_from_tag(ap, tag))
                  nr++;

      return nr;
}

void ata_eh_fastdrain_timerfn(unsigned long arg)
{
      struct ata_port *ap = (void *)arg;
      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) {
            unsigned int tag;

            /* No progress during the last interval, tag all
             * in-flight qcs as timed out and freeze the port.
             */
            for (tag = 0; tag < ATA_MAX_QUEUE - 1; tag++) {
                  struct ata_queued_cmd *qc = ata_qc_from_tag(ap, 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 =
                  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 = 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.
       */
      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 lock)
 */
void ata_port_schedule_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");
}

static int ata_do_link_abort(struct ata_port *ap, struct ata_link *link)
{
      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);

      for (tag = 0; tag < ATA_MAX_QUEUE; tag++) {
            struct ata_queued_cmd *qc = ata_qc_from_tag(ap, 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);
}

/**
 *    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);
}

/**
 *    __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.
 *
 *    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);

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

      return nr_aborted;
}

/**
 *    sata_async_notification - SATA async notification handler
 *    @ap: ATA port where async notification is received
 *
 *    Handler to be called when async notification via SDB FIS is
 *    received.  This function schedules EH if necessary.
 *
 *    LOCKING:
 *    spin_lock_irqsave(host lock)
 *
 *    RETURNS:
 *    1 if EH is scheduled, 0 otherwise.
 */
int sata_async_notification(struct ata_port *ap)
{
      u32 sntf;
      int rc;

      if (!(ap->flags & ATA_FLAG_AN))
            return 0;

      rc = sata_scr_read(&ap->link, SCR_NOTIFICATION, &sntf);
      if (rc == 0)
            sata_scr_write(&ap->link, SCR_NOTIFICATION, sntf);

      if (!ap->nr_pmp_links || rc) {
            /* PMP is not attached or SNTF is not available */
            if (!ap->nr_pmp_links) {
                  /* PMP is not attached.  Check whether ATAPI
                   * AN is configured.  If so, notify media
                   * change.
                   */
                  struct ata_device *dev = ap->link.device;

                  if ((dev->class == ATA_DEV_ATAPI) &&
                      (dev->flags & ATA_DFLAG_AN))
                        ata_scsi_media_change_notify(dev);
                  return 0;
            } else {
                  /* PMP is attached but SNTF is not available.
                   * ATAPI async media change notification is
                   * not used.  The PMP must be reporting PHY
                   * status change, schedule EH.
                   */
                  ata_port_schedule_eh(ap);
                  return 1;
            }
      } else {
            /* PMP is attached and SNTF is available */
            struct ata_link *link;

            /* check and notify ATAPI AN */
            ata_port_for_each_link(link, ap) {
                  if (!(sntf & (1 << link->pmp)))
                        continue;

                  if ((link->device->class == ATA_DEV_ATAPI) &&
                      (link->device->flags & ATA_DFLAG_AN))
                        ata_scsi_media_change_notify(link->device);
            }

            /* If PMP is reporting that PHY status of some
             * downstream ports has changed, schedule EH.
             */
            if (sntf & (1 << SATA_PMP_CTRL_PORT)) {
                  ata_port_schedule_eh(ap);
                  return 1;
            }

            return 0;
      }
}

/**
 *    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->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->retries is decremented 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->retries)
            scmd->retries--;
      __ata_eh_qc_complete(qc);
}

/**
 *    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;
      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 actions */
      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);

      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);

      /* Reset is represented by combination of actions and EHI
       * flags.  Suck in all related bits before clearing eh_info to
       * avoid losing requested action.
       */
      if (action & ATA_EH_RESET_MASK) {
            ehc->i.action |= ehi->action & ATA_EH_RESET_MASK;
            ehc->i.flags |= ehi->flags & ATA_EHI_RESET_MODIFIER_MASK;

            /* make sure all reset actions are cleared & clear EHI flags */
            action |= ATA_EH_RESET_MASK;
            ehi->flags &= ~ATA_EHI_RESET_MODIFIER_MASK;
      }

      ata_eh_clear_action(link, dev, ehi, action);

      if (!(ehc->i.flags & ATA_EHI_QUIET))
            ap->pflags |= ATA_PFLAG_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 @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;

      /* if reset is complete, clear all reset actions & reset modifier */
      if (action & ATA_EH_RESET_MASK) {
            action |= ATA_EH_RESET_MASK;
            ehc->i.flags &= ~ATA_EHI_RESET_MODIFIER_MASK;
      }

      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";
      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, 0);

      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->link->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_queued_cmd *qc)
{
      struct ata_device *dev = qc->dev;
      unsigned char *sense_buf = qc->scsicmd->sense_buffer;
      struct ata_port *ap = dev->link->ap;
      struct ata_taskfile tf;
      u8 cdb[ATAPI_CDB_LEN];

      DPRINTK("ATAPI request sense\n");

      /* FIXME: is this needed? */
      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] = qc->result_tf.feature >> 4;

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

      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 = 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) {
            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_HARDRESET;
      }

      /* 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.
       */
      hotplug_mask = 0;

      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_ncq_error - analyze NCQ error
 *    @link: ATA link 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_link *link)
{
      struct ata_port *ap = link->ap;
      struct ata_eh_context *ehc = &link->eh_context;
      struct ata_device *dev = link->device;
      struct ata_queued_cmd *qc;
      struct ata_taskfile tf;
      int tag, rc;

      /* if frozen, we can't do much */
      if (ap->pflags & ATA_PFLAG_FROZEN)
            return;

      /* is it NCQ device error? */
      if (!link->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_link_printk(link, KERN_ERR, "failed to read log page 10h "
                        "(errno=%d)\n", rc);
            return;
      }

      if (!(link->sactive & (1 << tag))) {
            ata_link_printk(link, 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 | AC_ERR_NCQ;
      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 (stat & (ATA_ERR | ATA_DF))
            qc->err_mask |= AC_ERR_DEV;
      else
            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:
            if (!(qc->ap->pflags & ATA_PFLAG_FROZEN)) {
                  tmp = atapi_eh_request_sense(qc);
                  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_error(int is_io, unsigned int err_mask)
{
      if (err_mask & AC_ERR_ATA_BUS)
            return 1;

      if (err_mask & AC_ERR_TIMEOUT)
            return 2;

      if (is_io) {
            if (err_mask & AC_ERR_HSM)
                  return 2;
            if ((err_mask &
                 (AC_ERR_DEV|AC_ERR_MEDIA|AC_ERR_INVALID)) == AC_ERR_DEV)
                  return 3;
      }

      return 0;
}

struct speed_down_verdict_arg {
      u64 since;
      int nr_errors[4];
};

static int speed_down_verdict_cb(struct ata_ering_entry *ent, void *void_arg)
{
      struct speed_down_verdict_arg *arg = void_arg;
      int cat = ata_eh_categorize_error(ent->is_io, ent->err_mask);

      if (ent->timestamp < arg->since)
            return -1;

      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.
 *
 *    Cat-1 is ATA_BUS error for any command.
 *
 *    Cat-2 is TIMEOUT for any command or HSM violation for known
 *    supported commands.
 *
 *    Cat-3 is is unclassified DEV error for known supported
 *    command.
 *
 *    NCQ needs to be turned off if there have been more than 3
 *    Cat-2 + Cat-3 errors during last 10 minutes.
 *
 *    Speed down is necessary if there have been more than 3 Cat-1 +
 *    Cat-2 errors or 10 Cat-3 errors during last 10 minutes.
 *
 *    Falling back to PIO mode is necessary if there have been more
 *    than 10 Cat-1 + Cat-2 + Cat-3 errors during last 5 minutes.
 *
 *    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 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[2] + arg.nr_errors[3] > 3)
            verdict |= ATA_EH_SPDN_NCQ_OFF;
      if (arg.nr_errors[1] + arg.nr_errors[2] > 3 || arg.nr_errors[3] > 10)
            verdict |= ATA_EH_SPDN_SPEED_DOWN;

      /* scan past 3 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[1] + arg.nr_errors[2] + arg.nr_errors[3] > 10)
            verdict |= ATA_EH_SPDN_FALLBACK_TO_PIO;

      return verdict;
}

/**
 *    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:
 *    Determined recovery action.
 */
static unsigned int ata_eh_speed_down(struct ata_device *dev, int is_io,
                              unsigned int err_mask)
{
      unsigned int verdict;
      unsigned int action = 0;

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

      /* record error and determine whether speed down is necessary */
      ata_ering_record(&dev->ering, is_io, 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_printk(dev, KERN_WARNING,
                         "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(dev->link) == 0) {
                  action |= ATA_EH_HARDRESET;
                  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_SOFTRESET;
                        goto done;
                  }
            }
      }

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

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

/**
 *    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_device *dev;
      unsigned int all_err_mask = 0;
      int tag, is_io = 0;
      u32 serror;
      int rc;

      DPRINTK("ENTER\n");

      if (ehc->i.flags & ATA_EHI_NO_AUTOPSY)
            return;

      /* obtain and analyze SError */
      rc = sata_scr_read(link, SCR_ERROR, &serror);
      if (rc == 0) {
            ehc->i.serror |= serror;
            ata_eh_analyze_serror(link);
      } else if (rc != -EOPNOTSUPP) {
            /* SError read failed, force hardreset and probing */
            ata_ehi_schedule_probe(&ehc->i);
            ehc->i.action |= ATA_EH_HARDRESET;
            ehc->i.err_mask |= AC_ERR_OTHER;
      }

      /* analyze NCQ failure */
      ata_eh_analyze_ncq_error(link);

      /* 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) || qc->dev->link != link)
                  continue;

            /* inherit upper level err_mask */
            qc->err_mask |= ehc->i.err_mask;

            /* analyze TF */
            ehc->i.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);

            /* accumulate error info */
            ehc->i.dev = qc->dev;
            all_err_mask |= qc->err_mask;
            if (qc->flags & ATA_QCFLAG_IO)
                  is_io = 1;
      }

      /* enforce default EH actions */
      if (ap->pflags & ATA_PFLAG_FROZEN ||
          all_err_mask & (AC_ERR_HSM | AC_ERR_TIMEOUT))
            ehc->i.action |= ATA_EH_SOFTRESET;
      else if ((is_io && all_err_mask) ||
             (!is_io && (all_err_mask & ~AC_ERR_DEV)))
            ehc->i.action |= ATA_EH_REVALIDATE;

      /* If we have offending qcs and the associated failed device,
       * perform per-dev EH action only on the offending device.
       */
      if (ehc->i.dev) {
            ehc->i.dev_action[ehc->i.dev->devno] |=
                  ehc->i.action & ATA_EH_PERDEV_MASK;
            ehc->i.action &= ~ATA_EH_PERDEV_MASK;
      }

      /* propagate timeout to host link */
      if ((all_err_mask & AC_ERR_TIMEOUT) && !ata_is_host_link(link))
            ap->link.eh_context.i.err_mask |= AC_ERR_TIMEOUT;

      /* record error and consider speeding down */
      dev = ehc->i.dev;
      if (!dev && ((ata_link_max_devices(link) == 1 &&
                  ata_dev_enabled(link->device))))
          dev = link->device;

      if (dev)
            ehc->i.action |= ata_eh_speed_down(dev, is_io, all_err_mask);

      DPRINTK("EXIT\n");
}

/**
 *    ata_eh_autopsy - analyze error and determine recovery action
 *    @ap: host port to perform autopsy on
 *
 *    Analyze all links of @ap and determine why they failed and
 *    which recovery actions are needed.
 *
 *    LOCKING:
 *    Kernel thread context (may sleep).
 */
void ata_eh_autopsy(struct ata_port *ap)
{
      struct ata_link *link;

      ata_port_for_each_link(link, ap)
            ata_eh_link_autopsy(link);

      /* Autopsy of fanout ports can affect host link autopsy.
       * Perform host link autopsy last.
       */
      if (ap->nr_pmp_links)
            ata_eh_link_autopsy(&ap->link);
}

/**
 *    ata_eh_link_report - report error handling to user
 *    @link: ATA link EH is going on
 *
 *    Report EH to user.
 *
 *    LOCKING:
 *    None.
 */
static void ata_eh_link_report(struct ata_link *link)
{
      struct ata_port *ap = link->ap;
      struct ata_eh_context *ehc = &link->eh_context;
      const char *frozen, *desc;
      char tries_buf[6];
      int tag, nr_failed = 0;

      if (ehc->i.flags & ATA_EHI_QUIET)
            return;

      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) || qc->dev->link != link ||
                ((qc->flags & ATA_QCFLAG_QUIET) &&
                 qc->err_mask == AC_ERR_DEV))
                  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->pflags & ATA_PFLAG_FROZEN)
            frozen = " frozen";

      memset(tries_buf, 0, sizeof(tries_buf));
      if (ap->eh_tries < ATA_EH_MAX_TRIES)
            snprintf(tries_buf, sizeof(tries_buf) - 1, " t%d",
                   ap->eh_tries);

      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%s\n",
                         ehc->i.err_mask, link->sactive, ehc->i.serror,
                         ehc->i.action, frozen, tries_buf);
            if (desc)
                  ata_dev_printk(ehc->i.dev, KERN_ERR, "%s\n", desc);
      } else {
            ata_link_printk(link, KERN_ERR, "exception Emask 0x%x "
                        "SAct 0x%x SErr 0x%x action 0x%x%s%s\n",
                        ehc->i.err_mask, link->sactive, ehc->i.serror,
                        ehc->i.action, frozen, tries_buf);
            if (desc)
                  ata_link_printk(link, KERN_ERR, "%s\n", desc);
      }

      if (ehc->i.serror)
            ata_port_printk(ap, KERN_ERR,
              "SError: { %s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s}\n",
              ehc->i.serror & SERR_DATA_RECOVERED ? "RecovData " : "",
              ehc->i.serror & SERR_COMM_RECOVERED ? "RecovComm " : "",
              ehc->i.serror & SERR_DATA ? "UnrecovData " : "",
              ehc->i.serror & SERR_PERSISTENT ? "Persist " : "",
              ehc->i.serror & SERR_PROTOCOL ? "Proto " : "",
              ehc->i.serror & SERR_INTERNAL ? "HostInt " : "",
              ehc->i.serror & SERR_PHYRDY_CHG ? "PHYRdyChg " : "",
              ehc->i.serror & SERR_PHY_INT_ERR ? "PHYInt " : "",
              ehc->i.serror & SERR_COMM_WAKE ? "CommWake " : "",
              ehc->i.serror & SERR_10B_8B_ERR ? "10B8B " : "",
              ehc->i.serror & SERR_DISPARITY ? "Dispar " : "",
              ehc->i.serror & SERR_CRC ? "BadCRC " : "",
              ehc->i.serror & SERR_HANDSHAKE ? "Handshk " : "",
              ehc->i.serror & SERR_LINK_SEQ_ERR ? "LinkSeq " : "",
              ehc->i.serror & SERR_TRANS_ST_ERROR ? "TrStaTrns " : "",
              ehc->i.serror & SERR_UNRECOG_FIS ? "UnrecFIS " : "",
              ehc->i.serror & SERR_DEV_XCHG ? "DevExch " : "");

      for (tag = 0; tag < ATA_MAX_QUEUE; tag++) {
            struct ata_queued_cmd *qc = __ata_qc_from_tag(ap, tag);
            struct ata_taskfile *cmd = &qc->tf, *res = &qc->result_tf;
            const u8 *cdb = qc->cdb;
            char data_buf[20] = "";
            char cdb_buf[70] = "";

            if (!(qc->flags & ATA_QCFLAG_FAILED) ||
                qc->dev->link != link || !qc->err_mask)
                  continue;

            if (qc->dma_dir != DMA_NONE) {
                  static const char *dma_str[] = {
                        [DMA_BIDIRECTIONAL]     = "bidi",
                        [DMA_TO_DEVICE]         = "out",
                        [DMA_FROM_DEVICE] = "in",
                  };
                  static const char *prot_str[] = {
                        [ATA_PROT_PIO]          = "pio",
                        [ATA_PROT_DMA]          = "dma",
                        [ATA_PROT_NCQ]          = "ncq",
                        [ATA_PROT_ATAPI]  = "pio",
                        [ATA_PROT_ATAPI_DMA]    = "dma",
                  };

                  snprintf(data_buf, sizeof(data_buf), " %s %u %s",
                         prot_str[qc->tf.protocol], qc->nbytes,
                         dma_str[qc->dma_dir]);
            }

            if (is_atapi_taskfile(&qc->tf))
                  snprintf(cdb_buf, sizeof(cdb_buf),
                         "cdb %02x %02x %02x %02x %02x %02x %02x %02x  "
                         "%02x %02x %02x %02x %02x %02x %02x %02x\n         ",
                         cdb[0], cdb[1], cdb[2], cdb[3],
                         cdb[4], cdb[5], cdb[6], cdb[7],
                         cdb[8], cdb[9], cdb[10], cdb[11],
                         cdb[12], cdb[13], cdb[14], cdb[15]);

            ata_dev_printk(qc->dev, KERN_ERR,
                  "cmd %02x/%02x:%02x:%02x:%02x:%02x/%02x:%02x:%02x:%02x:%02x/%02x "
                  "tag %d%s\n         %s"
                  "res %02x/%02x:%02x:%02x:%02x:%02x/%02x:%02x:%02x:%02x:%02x/%02x "
                  "Emask 0x%x (%s)%s\n",
                  cmd->command, cmd->feature, cmd->nsect,
                  cmd->lbal, cmd->lbam, cmd->lbah,
                  cmd->hob_feature, cmd->hob_nsect,
                  cmd->hob_lbal, cmd->hob_lbam, cmd->hob_lbah,
                  cmd->device, qc->tag, data_buf, cdb_buf,
                  res->command, res->feature, res->nsect,
                  res->lbal, res->lbam, res->lbah,
                  res->hob_feature, res->hob_nsect,
                  res->hob_lbal, res->hob_lbam, res->hob_lbah,
                  res->device, qc->err_mask, ata_err_string(qc->err_mask),
                  qc->err_mask & AC_ERR_NCQ ? " <F>" : "");

            if (res->command & (ATA_BUSY | ATA_DRDY | ATA_DF | ATA_DRQ |
                            ATA_ERR)) {
                  if (res->command & ATA_BUSY)
                        ata_dev_printk(qc->dev, KERN_ERR,
                          "status: { Busy }\n");
                  else
                        ata_dev_printk(qc->dev, KERN_ERR,
                          "status: { %s%s%s%s}\n",
                          res->command & ATA_DRDY ? "DRDY " : "",
                          res->command & ATA_DF ? "DF " : "",
                          res->command & ATA_DRQ ? "DRQ " : "",
                          res->command & ATA_ERR ? "ERR " : "");
            }

            if (cmd->command != ATA_CMD_PACKET &&
                (res->feature & (ATA_ICRC | ATA_UNC | ATA_IDNF |
                             ATA_ABORTED)))
                  ata_dev_printk(qc->dev, KERN_ERR,
                    "error: { %s%s%s%s}\n",
                    res->feature & ATA_ICRC ? "ICRC " : "",
                    res->feature & ATA_UNC ? "UNC " : "",
                    res->feature & ATA_IDNF ? "IDNF " : "",
                    res->feature & ATA_ABORTED ? "ABRT " : "");
      }
}

/**
 *    ata_eh_report - report error handling to user
 *    @ap: ATA port to report EH about
 *
 *    Report EH to user.
 *
 *    LOCKING:
 *    None.
 */
void ata_eh_report(struct ata_port *ap)
{
      struct ata_link *link;

      __ata_port_for_each_link(link, ap)
            ata_eh_link_report(link);
}

static int ata_do_reset(struct ata_link *link, ata_reset_fn_t reset,
                  unsigned int *classes, unsigned long deadline)
{
      struct ata_device *dev;
      int rc;

      ata_link_for_each_dev(dev, link)
            classes[dev->devno] = ATA_DEV_UNKNOWN;

      rc = reset(link, classes, deadline);
      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.
       */
      ata_link_for_each_dev(dev, link)
            if (classes[dev->devno] != ATA_DEV_UNKNOWN)
                  break;

      if (dev) {
            ata_link_for_each_dev(dev, link) {
                  if (classes[dev->devno] == ATA_DEV_UNKNOWN)
                        classes[dev->devno] = ATA_DEV_NONE;
            }
      }

      return 0;
}

static int ata_eh_followup_srst_needed(struct ata_link *link,
                               int rc, int classify,
                               const unsigned int *classes)
{
      if (link->flags & ATA_LFLAG_NO_SRST)
            return 0;
      if (rc == -EAGAIN)
            return 1;
      if (rc != 0)
            return 0;
      if ((link->ap->flags & ATA_FLAG_PMP) && ata_is_host_link(link))
            return 1;
      if (classify && !(link->flags & ATA_LFLAG_ASSUME_CLASS) &&
          classes[0] == ATA_DEV_UNKNOWN)
            return 1;
      return 0;
}

int ata_eh_reset(struct ata_link *link, int classify,
             ata_prereset_fn_t prereset, ata_reset_fn_t softreset,
             ata_reset_fn_t hardreset, ata_postreset_fn_t postreset)
{
      const int max_tries = ARRAY_SIZE(ata_eh_reset_timeouts);
      struct ata_port *ap = link->ap;
      struct ata_eh_context *ehc = &link->eh_context;
      unsigned int *classes = ehc->classes;
      unsigned int lflags = link->flags;
      int verbose = !(ehc->i.flags & ATA_EHI_QUIET);
      int try = 0;
      struct ata_device *dev;
      unsigned long deadline, now;
      unsigned int tmp_action;
      ata_reset_fn_t reset;
      unsigned long flags;
      u32 sstatus;
      int rc;

      /* about to reset */
      spin_lock_irqsave(ap->lock, flags);
      ap->pflags |= ATA_PFLAG_RESETTING;
      spin_unlock_irqrestore(ap->lock, flags);

      ata_eh_about_to_do(link, NULL, ehc->i.action & ATA_EH_RESET_MASK);

      ata_link_for_each_dev(dev, link) {
            /* If we issue an SRST then an ATA drive (not ATAPI)
             * may change configuration and be in PIO0 timing. If
             * we do a hard reset (or are coming from power on)
             * this is true for ATA or ATAPI. Until we've set a
             * suitable controller mode we should not touch the
             * bus as we may be talking too fast.
             */
            dev->pio_mode = XFER_PIO_0;

            /* If the controller has a pio mode setup function
             * then use it to set the chipset to rights. Don't
             * touch the DMA setup as that will be dealt with when
             * configuring devices.
             */
            if (ap->ops->set_piomode)
                  ap->ops->set_piomode(ap, dev);
      }

      /* Determine which reset to use and record in ehc->i.action.
       * prereset() may examine and modify it.
       */
      if (softreset && (!hardreset || (!(lflags & ATA_LFLAG_NO_SRST) &&
                               !sata_set_spd_needed(link) &&
                               !(ehc->i.action & ATA_EH_HARDRESET))))
            tmp_action = ATA_EH_SOFTRESET;
      else
            tmp_action = ATA_EH_HARDRESET;

      ehc->i.action = (ehc->i.action & ~ATA_EH_RESET_MASK) | tmp_action;

      if (prereset) {
            rc = prereset(link, jiffies + ATA_EH_PRERESET_TIMEOUT);
            if (rc) {
                  if (rc == -ENOENT) {
                        ata_link_printk(link, KERN_DEBUG,
                                    "port disabled. ignoring.\n");
                        ehc->i.action &= ~ATA_EH_RESET_MASK;

                        ata_link_for_each_dev(dev, link)
                              classes[dev->devno] = ATA_DEV_NONE;

                        rc = 0;
                  } else
                        ata_link_printk(link, KERN_ERR,
                              "prereset failed (errno=%d)\n", rc);
                  goto out;
            }
      }

      /* 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 */
            ata_link_for_each_dev(dev, link)
                  classes[dev->devno] = ATA_DEV_NONE;
            rc = 0;
            goto out;
      }

      /* did prereset() screw up?  if so, fix up to avoid oopsing */
      if (!reset) {
            if (softreset)
                  reset = softreset;
            else
                  reset = hardreset;
      }

 retry:
      deadline = jiffies + ata_eh_reset_timeouts[try++];

      /* shut up during boot probing */
      if (verbose)
            ata_link_printk(link, KERN_INFO, "%s resetting link\n",
                        reset == softreset ? "soft" : "hard");

      /* mark that this EH session started with reset */
      if (reset == hardreset)
            ehc->i.flags |= ATA_EHI_DID_HARDRESET;
      else
            ehc->i.flags |= ATA_EHI_DID_SOFTRESET;

      rc = ata_do_reset(link, reset, classes, deadline);

      if (reset == hardreset &&
          ata_eh_followup_srst_needed(link, rc, classify, classes)) {
            /* okay, let's do follow-up softreset */
            reset = softreset;

            if (!reset) {
                  ata_link_printk(link, KERN_ERR,
                              "follow-up softreset required "
                              "but no softreset avaliable\n");
                  rc = -EINVAL;
                  goto fail;
            }

            ata_eh_about_to_do(link, NULL, ATA_EH_RESET_MASK);
            rc = ata_do_reset(link, reset, classes, deadline);
      }

      /* -EAGAIN can happen if we skipped followup SRST */
      if (rc && rc != -EAGAIN)
            goto fail;

      /* was classification successful? */
      if (classify && classes[0] == ATA_DEV_UNKNOWN &&
          !(lflags & ATA_LFLAG_ASSUME_CLASS)) {
            if (try < max_tries) {
                  ata_link_printk(link, KERN_WARNING,
                              "classification failed\n");
                  rc = -EINVAL;
                  goto fail;
            }

            ata_link_printk(link, KERN_WARNING,
                        "classfication failed, assuming ATA\n");
            lflags |= ATA_LFLAG_ASSUME_ATA;
      }

      ata_link_for_each_dev(dev, link) {
            /* After the reset, the device state is PIO 0 and the
             * controller state is undefined.  Reset also wakes up
             * drives from sleeping mode.
             */
            dev->pio_mode = XFER_PIO_0;
            dev->flags &= ~ATA_DFLAG_SLEEPING;

            if (ata_link_offline(link))
                  continue;

            /* apply class override */
            if (lflags & ATA_LFLAG_ASSUME_ATA)
                  classes[dev->devno] = ATA_DEV_ATA;
            else if (lflags & ATA_LFLAG_ASSUME_SEMB)
                  classes[dev->devno] = ATA_DEV_SEMB_UNSUP; /* not yet */
      }

      /* record current link speed */
      if (sata_scr_read(link, SCR_STATUS, &sstatus) == 0)
            link->sata_spd = (sstatus >> 4) & 0xf;

      if (postreset)
            postreset(link, classes);

      /* reset successful, schedule revalidation */
      ata_eh_done(link, NULL, ehc->i.action & ATA_EH_RESET_MASK);
      ehc->i.action |= ATA_EH_REVALIDATE;

      rc = 0;
 out:
      /* clear hotplug flag */
      ehc->i.flags &= ~ATA_EHI_HOTPLUGGED;

      spin_lock_irqsave(ap->lock, flags);
      ap->pflags &= ~ATA_PFLAG_RESETTING;
      spin_unlock_irqrestore(ap->lock, flags);

      return rc;

 fail:
      if (rc == -ERESTART || try >= max_tries)
            goto out;

      now = jiffies;
      if (time_before(now, deadline)) {
            unsigned long delta = deadline - now;

            ata_link_printk(link, KERN_WARNING, "reset failed "
                        "(errno=%d), retrying in %u secs\n",
                        rc, (jiffies_to_msecs(delta) + 999) / 1000);

            while (delta)
                  delta = schedule_timeout_uninterruptible(delta);
      }

      if (rc == -EPIPE || try == max_tries - 1)
            sata_down_spd_limit(link);
      if (hardreset)
            reset = hardreset;
      goto retry;
}

static int ata_eh_revalidate_and_attach(struct ata_link *link,
                              struct ata_device **r_failed_dev)
{
      struct ata_port *ap = link->ap;
      struct ata_eh_context *ehc = &link->eh_context;
      struct ata_device *dev;
      unsigned int new_mask = 0;
      unsigned long flags;
      int rc = 0;

      DPRINTK("ENTER\n");

      /* For PATA drive side cable detection to work, IDENTIFY must
       * be done backwards such that PDIAG- is released by the slave
       * device before the master device is identified.
       */
      ata_link_for_each_dev_reverse(dev, link) {
            unsigned int action = ata_eh_dev_action(dev);
            unsigned int readid_flags = 0;

            if (ehc->i.flags & ATA_EHI_DID_RESET)
                  readid_flags |= ATA_READID_POSTRESET;

            if ((action & ATA_EH_REVALIDATE) && ata_dev_enabled(dev)) {
                  WARN_ON(dev->class == ATA_DEV_PMP);

                  if (ata_link_offline(link)) {
                        rc = -EIO;
                        goto err;
                  }

                  ata_eh_about_to_do(link, dev, ATA_EH_REVALIDATE);
                  rc = ata_dev_revalidate(dev, ehc->classes[dev->devno],
                                    readid_flags);
                  if (rc)
                        goto err;

                  ata_eh_done(link, dev, ATA_EH_REVALIDATE);

                  /* Configuration may have changed, reconfigure
                   * transfer mode.
                   */
                  ehc->i.flags |= ATA_EHI_SETMODE;

                  /* 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];

                  if (dev->class == ATA_DEV_PMP)
                        rc = sata_pmp_attach(dev);
                  else
                        rc = ata_dev_read_id(dev, &dev->class,
                                         readid_flags, dev->id);
                  switch (rc) {
                  case 0:
                        new_mask |= 1 << dev->devno;
                        break;
                  case -ENOENT:
                        /* IDENTIFY was issued to non-existent
                         * device.  No need to reset.  Just
                         * thaw and kill the device.
                         */
                        ata_eh_thaw_port(ap);
                        dev->class = ATA_DEV_UNKNOWN;
                        break;
                  default:
                        dev->class = ATA_DEV_UNKNOWN;
                        goto err;
                  }
            }
      }

      /* PDIAG- should have been released, ask cable type if post-reset */
      if (ata_is_host_link(link) && ap->ops->cable_detect &&
          (ehc->i.flags & ATA_EHI_DID_RESET))
            ap->cbl = ap->ops->cable_detect(ap);

      /* Configure new devices forward such that user doesn't see
       * device detection messages backwards.
       */
      ata_link_for_each_dev(dev, link) {
            if (!(new_mask & (1 << dev->devno)) ||
                dev->class == ATA_DEV_PMP)
                  continue;

            ehc->i.flags |= ATA_EHI_PRINTINFO;
            rc = ata_dev_configure(dev);
            ehc->i.flags &= ~ATA_EHI_PRINTINFO;
            if (rc)
                  goto err;

            spin_lock_irqsave(ap->lock, flags);
            ap->pflags |= ATA_PFLAG_SCSI_HOTPLUG;
            spin_unlock_irqrestore(ap->lock, flags);

            /* new device discovered, configure xfermode */
            ehc->i.flags |= ATA_EHI_SETMODE;
      }

      return 0;

 err:
      *r_failed_dev = dev;
      DPRINTK("EXIT rc=%d\n", rc);
      return rc;
}

static int ata_link_nr_enabled(struct ata_link *link)
{
      struct ata_device *dev;
      int cnt = 0;

      ata_link_for_each_dev(dev, link)
            if (ata_dev_enabled(dev))
                  cnt++;
      return cnt;
}

static int ata_link_nr_vacant(struct ata_link *link)
{
      struct ata_device *dev;
      int cnt = 0;

      ata_link_for_each_dev(dev, link)
            if (dev->class == ATA_DEV_UNKNOWN)
                  cnt++;
      return cnt;
}

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

      /* skip disabled links */
      if (link->flags & ATA_LFLAG_DISABLED)
            return 1;

      /* thaw frozen port, resume link and recover failed devices */
      if ((link->ap->pflags & ATA_PFLAG_FROZEN) ||
          (ehc->i.flags & ATA_EHI_RESUME_LINK) || ata_link_nr_enabled(link))
            return 0;

      /* skip if class codes for all vacant slots are ATA_DEV_NONE */
      ata_link_for_each_dev(dev, link) {
            if (dev->class == ATA_DEV_UNKNOWN &&
                ehc->classes[dev->devno] != ATA_DEV_NONE)
                  return 0;
      }

      return 1;
}

static int ata_eh_handle_dev_fail(struct ata_device *dev, int err)
{
      struct ata_eh_context *ehc = &dev->link->eh_context;

      ehc->tries[dev->devno]--;

      switch (err) {
      case -ENODEV:
            /* device missing or wrong IDENTIFY data, schedule probing */
            ehc->i.probe_mask |= (1 << dev->devno);
      case -EINVAL:
            /* give it just one more chance */
            ehc->tries[dev->devno] = min(ehc->tries[dev->devno], 1);
      case -EIO:
            if (ehc->tries[dev->devno] == 1 && dev->pio_mode > XFER_PIO_0) {
                  /* This is the last chance, better to slow
                   * down than lose it.
                   */
                  sata_down_spd_limit(dev->link);
                  ata_down_xfermask_limit(dev, ATA_DNXFER_PIO);
            }
      }

      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_link_offline(dev->link))
                  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;
            }

            return 1;
      } 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;

            return 0;
      }
}

/**
 *    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)
 *    @r_failed_link: out parameter for failed link
 *
 *    This is the alpha and omega, eum and yang, heart and soul of
 *    libata exception handling.  On entry, actions required to
 *    recover each link and hotplug requests are recorded in the
 *    link's 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.
 */
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_link **r_failed_link)
{
      struct ata_link *link;
      struct ata_device *dev;
      int nr_failed_devs, nr_disabled_devs;
      int reset, rc;
      unsigned long flags;

      DPRINTK("ENTER\n");

      /* prep for recovery */
      ata_port_for_each_link(link, ap) {
            struct ata_eh_context *ehc = &link->eh_context;

            /* re-enable link? */
            if (ehc->i.action & ATA_EH_ENABLE_LINK) {
                  ata_eh_about_to_do(link, NULL, ATA_EH_ENABLE_LINK);
                  spin_lock_irqsave(ap->lock, flags);
                  link->flags &= ~ATA_LFLAG_DISABLED;
                  spin_unlock_irqrestore(ap->lock, flags);
                  ata_eh_done(link, NULL, ATA_EH_ENABLE_LINK);
            }

            ata_link_for_each_dev(dev, link) {
                  if (link->flags & ATA_LFLAG_NO_RETRY)
                        ehc->tries[dev->devno] = 1;
                  else
                        ehc->tries[dev->devno] = ATA_EH_DEV_TRIES;

                  /* collect port action mask recorded in dev actions */
                  ehc->i.action |= ehc->i.dev_action[dev->devno] &
                               ~ATA_EH_PERDEV_MASK;
                  ehc->i.dev_action[dev->devno] &= ATA_EH_PERDEV_MASK;

                  /* 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:
      rc = 0;
      nr_failed_devs = 0;
      nr_disabled_devs = 0;
      reset = 0;

      /* if UNLOADING, finish immediately */
      if (ap->pflags & ATA_PFLAG_UNLOADING)
            goto out;

      /* prep for EH */
      ata_port_for_each_link(link, ap) {
            struct ata_eh_context *ehc = &link->eh_context;

            /* skip EH if possible. */
            if (ata_eh_skip_recovery(link))
                  ehc->i.action = 0;

            /* do we need to reset? */
            if (ehc->i.action & ATA_EH_RESET_MASK)
                  reset = 1;

            ata_link_for_each_dev(dev, link)
                  ehc->classes[dev->devno] = ATA_DEV_UNKNOWN;
      }

      /* reset */
      if (reset) {
            /* if PMP is attached, this function only deals with
             * downstream links, port should stay thawed.
             */
            if (!ap->nr_pmp_links)
                  ata_eh_freeze_port(ap);

            ata_port_for_each_link(link, ap) {
                  struct ata_eh_context *ehc = &link->eh_context;

                  if (!(ehc->i.action & ATA_EH_RESET_MASK))
                        continue;

                  rc = ata_eh_reset(link, ata_link_nr_vacant(link),
                                prereset, softreset, hardreset,
                                postreset);
                  if (rc) {
                        ata_link_printk(link, KERN_ERR,
                                    "reset failed, giving up\n");
                        goto out;
                  }
            }

            if (!ap->nr_pmp_links)
                  ata_eh_thaw_port(ap);
      }

      /* the rest */
      ata_port_for_each_link(link, ap) {
            struct ata_eh_context *ehc = &link->eh_context;

            /* revalidate existing devices and attach new ones */
            rc = ata_eh_revalidate_and_attach(link, &dev);
            if (rc)
                  goto dev_fail;

            /* if PMP got attached, return, pmp EH will take care of it */
            if (link->device->class == ATA_DEV_PMP) {
                  ehc->i.action = 0;
                  return 0;
            }

            /* configure transfer mode if necessary */
            if (ehc->i.flags & ATA_EHI_SETMODE) {
                  rc = ata_set_mode(link, &dev);
                  if (rc)
                        goto dev_fail;
                  ehc->i.flags &= ~ATA_EHI_SETMODE;
            }

            if (ehc->i.action & ATA_EHI_LPM)
                  ata_link_for_each_dev(dev, link)
                        ata_dev_enable_pm(dev, ap->pm_policy);

            /* this link is okay now */
            ehc->i.flags = 0;
            continue;

dev_fail:
            nr_failed_devs++;
            if (ata_eh_handle_dev_fail(dev, rc))
                  nr_disabled_devs++;

            if (ap->pflags & ATA_PFLAG_FROZEN) {
                  /* PMP reset requires working host port.
                   * Can't retry if it's frozen.
                   */
                  if (ap->nr_pmp_links)
                        goto out;
                  break;
            }
      }

      if (nr_failed_devs) {
            if (nr_failed_devs != nr_disabled_devs) {
                  ata_port_printk(ap, KERN_WARNING, "failed to recover "
                              "some devices, retrying in 5 secs\n");
                  ssleep(5);
            } else {
                  /* no device left to recover, repeat fast */
                  msleep(500);
            }

            goto retry;
      }

 out:
      if (rc && r_failed_link)
            *r_failed_link = link;

      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.
 */
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.
                   *
                   * There's no point in retrying invalid
                   * (detected by libata) and non-IO device
                   * errors (rejected by device).  Finish them
                   * immediately.
                   */
                  if ((qc->err_mask & AC_ERR_INVALID) ||
                      (!(qc->flags & ATA_QCFLAG_IO) &&
                       qc->err_mask == AC_ERR_DEV))
                        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);
                  }
            }
      }

      /* make sure nr_active_links is zero after EH */
      WARN_ON(ap->nr_active_links);
      ap->nr_active_links = 0;
}

/**
 *    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)
{
      struct ata_device *dev;
      int rc;

      ata_eh_autopsy(ap);
      ata_eh_report(ap);

      rc = ata_eh_recover(ap, prereset, softreset, hardreset, postreset,
                      NULL);
      if (rc) {
            ata_link_for_each_dev(dev, &ap->link)
                  ata_dev_disable(dev);
      }

      ata_eh_finish(ap);
}

#ifdef CONFIG_PM
/**
 *    ata_eh_handle_port_suspend - perform port suspend operation
 *    @ap: port to suspend
 *
 *    Suspend @ap.
 *
 *    LOCKING:
 *    Kernel thread context (may sleep).
 */
static void ata_eh_handle_port_suspend(struct ata_port *ap)
{
      unsigned long flags;
      int rc = 0;

      /* are we suspending? */
      spin_lock_irqsave(ap->lock, flags);
      if (!(ap->pflags & ATA_PFLAG_PM_PENDING) ||
          ap->pm_mesg.event == PM_EVENT_ON) {
            spin_unlock_irqrestore(ap->lock, flags);
            return;
      }
      spin_unlock_irqrestore(ap->lock, flags);

      WARN_ON(ap->pflags & ATA_PFLAG_SUSPENDED);

      /* tell ACPI we're suspending */
      rc = ata_acpi_on_suspend(ap);
      if (rc)
            goto out;

      /* suspend */
      ata_eh_freeze_port(ap);

      if (ap->ops->port_suspend)
            rc = ap->ops->port_suspend(ap, ap->pm_mesg);

 out:
      /* report result */
      spin_lock_irqsave(ap->lock, flags);

      ap->pflags &= ~ATA_PFLAG_PM_PENDING;
      if (rc == 0)
            ap->pflags |= ATA_PFLAG_SUSPENDED;
      else if (ap->pflags & ATA_PFLAG_FROZEN)
            ata_port_schedule_eh(ap);

      if (ap->pm_result) {
            *ap->pm_result = rc;
            ap->pm_result = NULL;
      }

      spin_unlock_irqrestore(ap->lock, flags);

      return;
}

/**
 *    ata_eh_handle_port_resume - perform port resume operation
 *    @ap: port to resume
 *
 *    Resume @ap.
 *
 *    LOCKING:
 *    Kernel thread context (may sleep).
 */
static void ata_eh_handle_port_resume(struct ata_port *ap)
{
      unsigned long flags;
      int rc = 0;

      /* are we resuming? */
      spin_lock_irqsave(ap->lock, flags);
      if (!(ap->pflags & ATA_PFLAG_PM_PENDING) ||
          ap->pm_mesg.event != PM_EVENT_ON) {
            spin_unlock_irqrestore(ap->lock, flags);
            return;
      }
      spin_unlock_irqrestore(ap->lock, flags);

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

      if (ap->ops->port_resume)
            rc = ap->ops->port_resume(ap);

      /* tell ACPI that we're resuming */
      ata_acpi_on_resume(ap);

      /* report result */
      spin_lock_irqsave(ap->lock, flags);
      ap->pflags &= ~(ATA_PFLAG_PM_PENDING | ATA_PFLAG_SUSPENDED);
      if (ap->pm_result) {
            *ap->pm_result = rc;
            ap->pm_result = NULL;
      }
      spin_unlock_irqrestore(ap->lock, flags);
}
#endif /* CONFIG_PM */

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