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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/blkdev.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 {
      /* 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),

      /* 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 retarded devices.
 */
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 retarded 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_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,
};

00119 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, },
};
#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 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 + (unsigned long long)offset);
}

#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;
}

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_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_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 blk_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 blk_eh_timer_return ret;

      DPRINTK("ENTER\n");

      if (ap->ops->error_handler) {
            ret = BLK_EH_NOT_HANDLED;
            goto out;
      }

      ret = BLK_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 = BLK_EH_NOT_HANDLED;
      }
      spin_unlock_irqrestore(ap->lock, flags);

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

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);
      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 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.
       */
      if (ap->ops->error_handler) {
            struct scsi_cmnd *scmd, *tmp;
            int nr_timedout = 0;

            spin_lock_irqsave(ap->lock, flags);
            
            /* 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, &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);
            
      /* If we timed raced normal completion and there is nothing to
         recover nr_timedout == 0 why exactly are we doing error recovery ? */

 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_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 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_for_each_link(link, ap, HOST_FIRST)
                  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 =
                  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_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 (!sata_pmp_attached(ap) || rc) {
            /* PMP is not attached or SNTF is not available */
            if (!sata_pmp_attached(ap)) {
                  /* 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_for_each_link(link, ap, EDGE) {
                  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_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_printk(dev, KERN_WARNING, "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);
}

/**
 *    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
*     @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;

      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_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.
 */
static 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;
}

/**
 *    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
 */
static 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");

      /* 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] = 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.
       */
      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).
 */
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->result_tf.flags = ATA_TFLAG_ISADDR | ATA_TFLAG_LBA | ATA_TFLAG_LBA48;
      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_RESET;
      }

      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->dev,
                                    qc->scsicmd->sense_buffer,
                                    qc->result_tf.feature >> 4);
                  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_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;
}

01730 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->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 followings 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
 *       ocurred 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_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(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_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, eflags = 0;
      int tag;
      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 reset and probing */
            ehc->i.probe_mask |= ATA_ALL_DEVICES;
            ehc->i.action |= ATA_EH_RESET;
            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) ||
                ata_dev_phys_link(qc->dev) != 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);

            /* determine whether the command is worth retrying */
            if (!(qc->err_mask & AC_ERR_INVALID) &&
                ((qc->flags & ATA_QCFLAG_IO) || qc->err_mask != AC_ERR_DEV))
                  qc->flags |= ATA_QCFLAG_RETRY;

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

      /* enforce default EH actions */
      if (ap->pflags & ATA_PFLAG_FROZEN ||
          all_err_mask & (AC_ERR_HSM | AC_ERR_TIMEOUT))
            ehc->i.action |= ATA_EH_RESET;
      else if (((eflags & ATA_EFLAG_IS_IO) && all_err_mask) ||
             (!(eflags & ATA_EFLAG_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) {
            if (dev->flags & ATA_DFLAG_DUBIOUS_XFER)
                  eflags |= ATA_EFLAG_DUBIOUS_XFER;
            ehc->i.action |= ata_eh_speed_down(dev, eflags, 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_for_each_link(link, ap, EDGE)
            ata_eh_link_autopsy(link);

      /* Handle the frigging slave link.  Autopsy is done similarly
       * but actions and flags are transferred over to the master
       * link and handled from there.
       */
      if (ap->slave_link) {
            struct ata_eh_context *mehc = &ap->link.eh_context;
            struct ata_eh_context *sehc = &ap->slave_link->eh_context;

            /* transfer control flags from master to slave */
            sehc->i.flags |= mehc->i.flags & ATA_EHI_TO_SLAVE_MASK;

            /* perform autopsy on the slave link */
            ata_eh_link_autopsy(ap->slave_link);

            /* transfer actions from slave to master and clear slave */
            ata_eh_about_to_do(ap->slave_link, NULL, ATA_EH_ALL_ACTIONS);
            mehc->i.action          |= sehc->i.action;
            mehc->i.dev_action[1]   |= sehc->i.dev_action[1];
            mehc->i.flags           |= sehc->i.flags;
            ata_eh_done(ap->slave_link, NULL, ATA_EH_ALL_ACTIONS);
      }

      /* Autopsy of fanout ports can affect host link autopsy.
       * Perform host link autopsy last.
       */
      if (sata_pmp_attached(ap))
            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) ||
                ata_dev_phys_link(qc->dev) != 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_link_printk(link, 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) ||
                ata_dev_phys_link(qc->dev) != 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",
                        [ATAPI_PROT_PIO]  = "pio",
                        [ATAPI_PROT_DMA]  = "dma",
                  };

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

            if (ata_is_atapi(qc->tf.protocol))
                  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_for_each_link(link, ap, HOST_FIRST)
            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,
                  bool clear_classes)
{
      struct ata_device *dev;

      if (clear_classes)
            ata_for_each_dev(dev, link, ALL)
                  classes[dev->devno] = ATA_DEV_UNKNOWN;

      return reset(link, classes, deadline);
}

static int ata_eh_followup_srst_needed(struct ata_link *link,
                               int rc, const unsigned int *classes)
{
      if ((link->flags & ATA_LFLAG_NO_SRST) || ata_link_offline(link))
            return 0;
      if (rc == -EAGAIN)
            return 1;
      if (sata_pmp_supported(link->ap) && ata_is_host_link(link))
            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)
{
      struct ata_port *ap = link->ap;
      struct ata_link *slave = ap->slave_link;
      struct ata_eh_context *ehc = &link->eh_context;
      struct ata_eh_context *sehc = slave ? &slave->eh_context : NULL;
      unsigned int *classes = ehc->classes;
      unsigned int lflags = link->flags;
      int verbose = !(ehc->i.flags & ATA_EHI_QUIET);
      int max_tries = 0, try = 0;
      struct ata_link *failed_link;
      struct ata_device *dev;
      unsigned long deadline, now;
      ata_reset_fn_t reset;
      unsigned long flags;
      u32 sstatus;
      int nr_unknown, rc;

      /*
       * Prepare to reset
       */
      while (ata_eh_reset_timeouts[max_tries] != ULONG_MAX)
            max_tries++;
      if (link->flags & ATA_LFLAG_NO_HRST)
            hardreset = NULL;
      if (link->flags & ATA_LFLAG_NO_SRST)
            softreset = NULL;

      /* make sure each reset attemp is at least COOL_DOWN apart */
      if (ehc->i.flags & ATA_EHI_DID_RESET) {
            now = jiffies;
            WARN_ON(time_after(ehc->last_reset, now));
            deadline = ata_deadline(ehc->last_reset,
                              ATA_EH_RESET_COOL_DOWN);
            if (time_before(now, deadline))
                  schedule_timeout_uninterruptible(deadline - now);
      }

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

      ata_eh_about_to_do(link, NULL, ATA_EH_RESET);

      ata_for_each_dev(dev, link, ALL) {
            /* 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);
      }

      /* prefer hardreset */
      reset = NULL;
      ehc->i.action &= ~ATA_EH_RESET;
      if (hardreset) {
            reset = hardreset;
            ehc->i.action |= ATA_EH_HARDRESET;
      } else if (softreset) {
            reset = softreset;
            ehc->i.action |= ATA_EH_SOFTRESET;
      }

      if (prereset) {
            unsigned long deadline = ata_deadline(jiffies,
                                          ATA_EH_PRERESET_TIMEOUT);

            if (slave) {
                  sehc->i.action &= ~ATA_EH_RESET;
                  sehc->i.action |= ehc->i.action;
            }

            rc = prereset(link, deadline);

            /* If present, do prereset on slave link too.  Reset
             * is skipped iff both master and slave links report
             * -ENOENT or clear ATA_EH_RESET.
             */
            if (slave && (rc == 0 || rc == -ENOENT)) {
                  int tmp;

                  tmp = prereset(slave, deadline);
                  if (tmp != -ENOENT)
                        rc = tmp;

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

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

                        ata_for_each_dev(dev, link, ALL)
                              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 cleared ATA_EH_RESET.  If so,
             * bang classes, thaw and return.
             */
            if (reset && !(ehc->i.action & ATA_EH_RESET)) {
                  ata_for_each_dev(dev, link, ALL)
                        classes[dev->devno] = ATA_DEV_NONE;
                  if ((ap->pflags & ATA_PFLAG_FROZEN) &&
                      ata_is_host_link(link))
                        ata_eh_thaw_port(ap);
                  rc = 0;
                  goto out;
            }
      }

 retry:
      /*
       * Perform reset
       */
      if (ata_is_host_link(link))
            ata_eh_freeze_port(ap);

      deadline = ata_deadline(jiffies, ata_eh_reset_timeouts[try++]);

      if (reset) {
            if (verbose)
                  ata_link_printk(link, KERN_INFO, "%s resetting link\n",
                              reset == softreset ? "soft" : "hard");

            /* mark that this EH session started with reset */
            ehc->last_reset = jiffies;
            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, true);
            if (rc && rc != -EAGAIN) {
                  failed_link = link;
                  goto fail;
            }

            /* hardreset slave link if existent */
            if (slave && reset == hardreset) {
                  int tmp;

                  if (verbose)
                        ata_link_printk(slave, KERN_INFO,
                                    "hard resetting link\n");

                  ata_eh_about_to_do(slave, NULL, ATA_EH_RESET);
                  tmp = ata_do_reset(slave, reset, classes, deadline,
                                 false);
                  switch (tmp) {
                  case -EAGAIN:
                        rc = -EAGAIN;
                  case 0:
                        break;
                  default:
                        failed_link = slave;
                        rc = tmp;
                        goto fail;
                  }
            }

            /* perform follow-up SRST if necessary */
            if (reset == hardreset &&
                ata_eh_followup_srst_needed(link, rc, classes)) {
                  reset = softreset;

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

                  ata_eh_about_to_do(link, NULL, ATA_EH_RESET);
                  rc = ata_do_reset(link, reset, classes, deadline, true);
                  if (rc) {
                        failed_link = link;
                        goto fail;
                  }
            }
      } else {
            if (verbose)
                  ata_link_printk(link, KERN_INFO, "no reset method "
                              "available, skipping reset\n");
            if (!(lflags & ATA_LFLAG_ASSUME_CLASS))
                  lflags |= ATA_LFLAG_ASSUME_ATA;
      }

      /*
       * Post-reset processing
       */
      ata_for_each_dev(dev, link, ALL) {
            /* 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_phys_link_offline(ata_dev_phys_link(dev))) {
                  /* 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;
            } else
                  classes[dev->devno] = ATA_DEV_NONE;
      }

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

      /* thaw the port */
      if (ata_is_host_link(link))
            ata_eh_thaw_port(ap);

      /* postreset() should clear hardware SError.  Although SError
       * is cleared during link resume, clearing SError here is
       * necessary as some PHYs raise hotplug events after SRST.
       * This introduces race condition where hotplug occurs between
       * reset and here.  This race is mediated by cross checking
       * link onlineness and classification result later.
       */
      if (postreset) {
            postreset(link, classes);
            if (slave)
                  postreset(slave, classes);
      }

      /* clear cached SError */
      spin_lock_irqsave(link->ap->lock, flags);
      link->eh_info.serror = 0;
      if (slave)
            slave->eh_info.serror = 0;
      spin_unlock_irqrestore(link->ap->lock, flags);

      /* Make sure onlineness and classification result correspond.
       * Hotplug could have happened during reset and some
       * controllers fail to wait while a drive is spinning up after
       * being hotplugged causing misdetection.  By cross checking
       * link onlineness and classification result, those conditions
       * can be reliably detected and retried.
       */
      nr_unknown = 0;
      ata_for_each_dev(dev, link, ALL) {
            /* convert all ATA_DEV_UNKNOWN to ATA_DEV_NONE */
            if (classes[dev->devno] == ATA_DEV_UNKNOWN) {
                  classes[dev->devno] = ATA_DEV_NONE;
                  if (ata_phys_link_online(ata_dev_phys_link(dev)))
                        nr_unknown++;
            }
      }

      if (classify && nr_unknown) {
            if (try < max_tries) {
                  ata_link_printk(link, KERN_WARNING, "link online but "
                               "device misclassified, retrying\n");
                  failed_link = link;
                  rc = -EAGAIN;
                  goto fail;
            }
            ata_link_printk(link, KERN_WARNING,
                         "link online but device misclassified, "
                         "device detection might fail\n");
      }

      /* reset successful, schedule revalidation */
      ata_eh_done(link, NULL, ATA_EH_RESET);
      if (slave)
            ata_eh_done(slave, NULL, ATA_EH_RESET);
      ehc->last_reset = jiffies;    /* update to completion time */
      ehc->i.action |= ATA_EH_REVALIDATE;

      rc = 0;
 out:
      /* clear hotplug flag */
      ehc->i.flags &= ~ATA_EHI_HOTPLUGGED;
      if (slave)
            sehc->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 SCR isn't accessible on a fan-out port, PMP needs to be reset */
      if (!ata_is_host_link(link) &&
          sata_scr_read(link, SCR_STATUS, &sstatus))
            rc = -ERESTART;

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

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

            ata_link_printk(failed_link, KERN_WARNING,
                  "reset failed (errno=%d), retrying in %u secs\n",
                  rc, DIV_ROUND_UP(jiffies_to_msecs(delta), 1000));

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

      if (try == max_tries - 1) {
            sata_down_spd_limit(link, 0);
            if (slave)
                  sata_down_spd_limit(slave, 0);
      } else if (rc == -EPIPE)
            sata_down_spd_limit(failed_link, 0);

      if (hardreset)
            reset = hardreset;
      goto retry;
}

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

      /*
       * This function can be thought of as an extended version of
       * ata_eh_about_to_do() specially crafted to accommodate the
       * requirements of ATA_EH_PARK handling. Since the EH thread
       * does not leave the do {} while () loop in ata_eh_recover as
       * long as the timeout for a park request to *one* device on
       * the port has not expired, and since we still want to pick
       * up park requests to other devices on the same port or
       * timeout updates for the same device, we have to pull
       * ATA_EH_PARK actions from eh_info into eh_context.i
       * ourselves at the beginning of each pass over the loop.
       *
       * Additionally, all write accesses to &ap->park_req_pending
       * through INIT_COMPLETION() (see below) or complete_all()
       * (see ata_scsi_park_store()) are protected by the host lock.
       * As a result we have that park_req_pending.done is zero on
       * exit from this function, i.e. when ATA_EH_PARK actions for
       * *all* devices on port ap have been pulled into the
       * respective eh_context structs. If, and only if,
       * park_req_pending.done is non-zero by the time we reach
       * wait_for_completion_timeout(), another ATA_EH_PARK action
       * has been scheduled for at least one of the devices on port
       * ap and we have to cycle over the do {} while () loop in
       * ata_eh_recover() again.
       */

      spin_lock_irqsave(ap->lock, flags);
      INIT_COMPLETION(ap->park_req_pending);
      ata_for_each_link(link, ap, EDGE) {
            ata_for_each_dev(dev, link, ALL) {
                  struct ata_eh_info *ehi = &link->eh_info;

                  link->eh_context.i.dev_action[dev->devno] |=
                        ehi->dev_action[dev->devno] & ATA_EH_PARK;
                  ata_eh_clear_action(link, dev, ehi, ATA_EH_PARK);
            }
      }
      spin_unlock_irqrestore(ap->lock, flags);
}

static void ata_eh_park_issue_cmd(struct ata_device *dev, int park)
{
      struct ata_eh_context *ehc = &dev->link->eh_context;
      struct ata_taskfile tf;
      unsigned int err_mask;

      ata_tf_init(dev, &tf);
      if (park) {
            ehc->unloaded_mask |= 1 << dev->devno;
            tf.command = ATA_CMD_IDLEIMMEDIATE;
            tf.feature = 0x44;
            tf.lbal = 0x4c;
            tf.lbam = 0x4e;
            tf.lbah = 0x55;
      } else {
            ehc->unloaded_mask &= ~(1 << dev->devno);
            tf.command = ATA_CMD_CHK_POWER;
      }

      tf.flags |= ATA_TFLAG_DEVICE | ATA_TFLAG_ISADDR;
      tf.protocol |= ATA_PROT_NODATA;
      err_mask = ata_exec_internal(dev, &tf, NULL, DMA_NONE, NULL, 0, 0);
      if (park && (err_mask || tf.lbal != 0xc4)) {
            ata_dev_printk(dev, KERN_ERR, "head unload failed!\n");
            ehc->unloaded_mask &= ~(1 << dev->devno);
      }
}

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_for_each_dev(dev, link, ALL_REVERSE) {
            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_phys_link_offline(ata_dev_phys_link(dev))) {
                        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])) {
                  /* Temporarily set dev->class, it will be
                   * permanently set once all configurations are
                   * complete.  This is necessary because new
                   * device configuration is done in two
                   * separate loops.
                   */
                  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);

                  /* read_id might have changed class, store and reset */
                  ehc->classes[dev->devno] = dev->class;
                  dev->class = ATA_DEV_UNKNOWN;

                  switch (rc) {
                  case 0:
                        /* clear error info accumulated during probe */
                        ata_ering_clear(&dev->ering);
                        new_mask |= 1 << dev->devno;
                        break;
                  case -ENOENT:
                        /* IDENTIFY was issued to non-existent
                         * device.  No need to reset.  Just
                         * thaw and ignore the device.
                         */
                        ata_eh_thaw_port(ap);
                        break;
                  default:
                        goto err;
                  }
            }
      }

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

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

            dev->class = ehc->classes[dev->devno];

            ehc->i.flags |= ATA_EHI_PRINTINFO;
            rc = ata_dev_configure(dev);
            ehc->i.flags &= ~ATA_EHI_PRINTINFO;
            if (rc) {
                  dev->class = ATA_DEV_UNKNOWN;
                  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;
}

/**
 *    ata_set_mode - Program timings and issue SET FEATURES - XFER
 *    @link: link on which timings will be programmed
 *    @r_failed_dev: out parameter for failed device
 *
 *    Set ATA device disk transfer mode (PIO3, UDMA6, etc.).  If
 *    ata_set_mode() fails, pointer to the failing device is
 *    returned in @r_failed_dev.
 *
 *    LOCKING:
 *    PCI/etc. bus probe sem.
 *
 *    RETURNS:
 *    0 on success, negative errno otherwise
 */
int ata_set_mode(struct ata_link *link, struct ata_device **r_failed_dev)
{
      struct ata_port *ap = link->ap;
      struct ata_device *dev;
      int rc;

      /* if data transfer is verified, clear DUBIOUS_XFER on ering top */
      ata_for_each_dev(dev, link, ENABLED) {
            if (!(dev->flags & ATA_DFLAG_DUBIOUS_XFER)) {
                  struct ata_ering_entry *ent;

                  ent = ata_ering_top(&dev->ering);
                  if (ent)
                        ent->eflags &= ~ATA_EFLAG_DUBIOUS_XFER;
            }
      }

      /* has private set_mode? */
      if (ap->ops->set_mode)
            rc = ap->ops->set_mode(link, r_failed_dev);
      else
            rc = ata_do_set_mode(link, r_failed_dev);

      /* if transfer mode has changed, set DUBIOUS_XFER on device */
      ata_for_each_dev(dev, link, ENABLED) {
            struct ata_eh_context *ehc = &link->eh_context;
            u8 saved_xfer_mode = ehc->saved_xfer_mode[dev->devno];
            u8 saved_ncq = !!(ehc->saved_ncq_enabled & (1 << dev->devno));

            if (dev->xfer_mode != saved_xfer_mode ||
                ata_ncq_enabled(dev) != saved_ncq)
                  dev->flags |= ATA_DFLAG_DUBIOUS_XFER;
      }

      return rc;
}

/**
 *    atapi_eh_clear_ua - Clear ATAPI UNIT ATTENTION after reset
 *    @dev: ATAPI device to clear UA for
 *
 *    Resets and other operations can make an ATAPI device raise
 *    UNIT ATTENTION which causes the next operation to fail.  This
 *    function clears UA.
 *
 *    LOCKING:
 *    EH context (may sleep).
 *
 *    RETURNS:
 *    0 on success, -errno on failure.
 */
static int atapi_eh_clear_ua(struct ata_device *dev)
{
      int i;

      for (i = 0; i < ATA_EH_UA_TRIES; i++) {
            u8 *sense_buffer = dev->link->ap->sector_buf;
            u8 sense_key = 0;
            unsigned int err_mask;

            err_mask = atapi_eh_tur(dev, &sense_key);
            if (err_mask != 0 && err_mask != AC_ERR_DEV) {
                  ata_dev_printk(dev, KERN_WARNING, "TEST_UNIT_READY "
                        "failed (err_mask=0x%x)\n", err_mask);
                  return -EIO;
            }

            if (!err_mask || sense_key != UNIT_ATTENTION)
                  return 0;

            err_mask = atapi_eh_request_sense(dev, sense_buffer, sense_key);
            if (err_mask) {
                  ata_dev_printk(dev, KERN_WARNING, "failed to clear "
                        "UNIT ATTENTION (err_mask=0x%x)\n", err_mask);
                  return -EIO;
            }
      }

      ata_dev_printk(dev, KERN_WARNING,
            "UNIT ATTENTION persists after %d tries\n", ATA_EH_UA_TRIES);

      return 0;
}

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

      ata_for_each_dev(dev, link, ENABLED)
            cnt++;
      return cnt;
}

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

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

static int ata_eh_skip_recovery(struct ata_link *link)
{
      struct ata_port *ap = link->ap;
      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 and recover failed devices */
      if ((ap->pflags & ATA_PFLAG_FROZEN) || ata_link_nr_enabled(link))
            return 0;

      /* reset at least once if reset is requested */
      if ((ehc->i.action & ATA_EH_RESET) &&
          !(ehc->i.flags & ATA_EHI_DID_RESET))
            return 0;

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

      return 1;
}

static int ata_count_probe_trials_cb(struct ata_ering_entry *ent, void *void_arg)
{
      u64 interval = msecs_to_jiffies(ATA_EH_PROBE_TRIAL_INTERVAL);
      u64 now = get_jiffies_64();
      int *trials = void_arg;

      if (ent->timestamp < now - min(now, interval))
            return -1;

      (*trials)++;
      return 0;
}

static int ata_eh_schedule_probe(struct ata_device *dev)
{
      struct ata_eh_context *ehc = &dev->link->eh_context;
      struct ata_link *link = ata_dev_phys_link(dev);
      int trials = 0;

      if (!(ehc->i.probe_mask & (1 << dev->devno)) ||
          (ehc->did_probe_mask & (1 << dev->devno)))
            return 0;

      ata_eh_detach_dev(dev);
      ata_dev_init(dev);
      ehc->did_probe_mask |= (1 << dev->devno);
      ehc->i.action |= ATA_EH_RESET;
      ehc->saved_xfer_mode[dev->devno] = 0;
      ehc->saved_ncq_enabled &= ~(1 << dev->devno);

      /* Record and count probe trials on the ering.  The specific
       * error mask used is irrelevant.  Because a successful device
       * detection clears the ering, this count accumulates only if
       * there are consecutive failed probes.
       *
       * If the count is equal to or higher than ATA_EH_PROBE_TRIALS
       * in the last ATA_EH_PROBE_TRIAL_INTERVAL, link speed is
       * forced to 1.5Gbps.
       *
       * This is to work around cases where failed link speed
       * negotiation results in device misdetection leading to
       * infinite DEVXCHG or PHRDY CHG events.
       */
      ata_ering_record(&dev->ering, 0, AC_ERR_OTHER);
      ata_ering_map(&dev->ering, ata_count_probe_trials_cb, &trials);

      if (trials > ATA_EH_PROBE_TRIALS)
            sata_down_spd_limit(link, 1);

      return 1;
}

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

      /* -EAGAIN from EH routine indicates retry without prejudice.
       * The requester is responsible for ensuring forward progress.
       */
      if (err != -EAGAIN)
            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) {
                  /* This is the last chance, better to slow
                   * down than lose it.
                   */
                  sata_down_spd_limit(ata_dev_phys_link(dev), 0);
                  if (dev->pio_mode > XFER_PIO_0)
                        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_phys_link_offline(ata_dev_phys_link(dev)))
                  ata_eh_detach_dev(dev);

            /* schedule probe if necessary */
            if (ata_eh_schedule_probe(dev)) {
                  ehc->tries[dev->devno] = ATA_EH_DEV_TRIES;
                  memset(ehc->cmd_timeout_idx[dev->devno], 0,
                         sizeof(ehc->cmd_timeout_idx[dev->devno]));
            }

            return 1;
      } else {
            ehc->i.action |= ATA_EH_RESET;
            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;
      int rc;
      unsigned long flags, deadline;

      DPRINTK("ENTER\n");

      /* prep for recovery */
      ata_for_each_link(link, ap, EDGE) {
            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_for_each_dev(dev, link, ALL) {
                  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);

                  /* schedule probe if necessary */
                  if (!ata_dev_enabled(dev))
                        ata_eh_schedule_probe(dev);
            }
      }

 retry:
      rc = 0;
      nr_failed_devs = 0;

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

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

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

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

      /* reset */
      ata_for_each_link(link, ap, EDGE) {
            struct ata_eh_context *ehc = &link->eh_context;

            if (!(ehc->i.action & ATA_EH_RESET))
                  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;
            }
      }

      do {
            unsigned long now;

            /*
             * clears ATA_EH_PARK in eh_info and resets
             * ap->park_req_pending
             */
            ata_eh_pull_park_action(ap);

            deadline = jiffies;
            ata_for_each_link(link, ap, EDGE) {
                  ata_for_each_dev(dev, link, ALL) {
                        struct ata_eh_context *ehc = &link->eh_context;
                        unsigned long tmp;

                        if (dev->class != ATA_DEV_ATA)
                              continue;
                        if (!(ehc->i.dev_action[dev->devno] &
                              ATA_EH_PARK))
                              continue;
                        tmp = dev->unpark_deadline;
                        if (time_before(deadline, tmp))
                              deadline = tmp;
                        else if (time_before_eq(tmp, jiffies))
                              continue;
                        if (ehc->unloaded_mask & (1 << dev->devno))
                              continue;

                        ata_eh_park_issue_cmd(dev, 1);
                  }
            }

            now = jiffies;
            if (time_before_eq(deadline, now))
                  break;

            deadline = wait_for_completion_timeout(&ap->park_req_pending,
                                           deadline - now);
      } while (deadline);
      ata_for_each_link(link, ap, EDGE) {
            ata_for_each_dev(dev, link, ALL) {
                  if (!(link->eh_context.unloaded_mask &
                        (1 << dev->devno)))
                        continue;

                  ata_eh_park_issue_cmd(dev, 0);
                  ata_eh_done(link, dev, ATA_EH_PARK);
            }
      }

      /* the rest */
      ata_for_each_link(link, ap, EDGE) {
            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 reset has been issued, clear UA to avoid
             * disrupting the current users of the device.
             */
            if (ehc->i.flags & ATA_EHI_DID_RESET) {
                  ata_for_each_dev(dev, link, ALL) {
                        if (dev->class != ATA_DEV_ATAPI)
                              continue;
                        rc = atapi_eh_clear_ua(dev);
                        if (rc)
                              goto dev_fail;
                  }
            }

            /* configure link power saving */
            if (ehc->i.action & ATA_EH_LPM)
                  ata_for_each_dev(dev, link, ALL)
                        ata_dev_enable_pm(dev, ap->pm_policy);

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

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

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

      if (nr_failed_devs)
            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.
                   */
                  if (qc->flags & ATA_QCFLAG_RETRY)
                        ata_eh_qc_retry(qc);
                  else
                        ata_eh_qc_complete(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_for_each_dev(dev, &ap->link, ALL)
                  ata_dev_disable(dev);
      }

      ata_eh_finish(ap);
}

/**
 *    ata_std_error_handler - standard error handler
 *    @ap: host port to handle error for
 *
 *    Standard error handler
 *
 *    LOCKING:
 *    Kernel thread context (may sleep).
 */
void ata_std_error_handler(struct ata_port *ap)
{
      struct ata_port_operations *ops = ap->ops;
      ata_reset_fn_t hardreset = ops->hardreset;

      /* ignore built-in hardreset if SCR access is not available */
      if (ata_is_builtin_hardreset(hardreset) && !sata_scr_valid(&ap->link))
            hardreset = NULL;

      ata_do_eh(ap, ops->prereset, ops->softreset, hardreset, ops->postreset);
}

#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);

      ata_acpi_set_state(ap, PMSG_SUSPEND);
 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)
{
      struct ata_link *link;
      struct ata_device *dev;
      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));

      /*
       * Error timestamps are in jiffies which doesn't run while
       * suspended and PHY events during resume isn't too uncommon.
       * When the two are combined, it can lead to unnecessary speed
       * downs if the machine is suspended and resumed repeatedly.
       * Clear error history.
       */
      ata_for_each_link(link, ap, HOST_FIRST)
            ata_for_each_dev(dev, link, ALL)
                  ata_ering_clear(&dev->ering);

      ata_acpi_set_state(ap, PMSG_ON);

      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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