[PATCH] libata-eh: implement dev->ering

[deliverable/linux.git] / drivers / scsi / 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/config.h>
#include <linux/kernel.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 <linux/libata.h>

#include "libata.h"

static void __ata_port_freeze(struct ata_port *ap);

static void ata_ering_record(struct ata_ering *ering, int is_io,
                             unsigned int err_mask)
{
        struct ata_ering_entry *ent;

        WARN_ON(!err_mask);

        ering->cursor++;
        ering->cursor %= ATA_ERING_SIZE;

        ent = &ering->ring[ering->cursor];
        ent->is_io = is_io;
        ent->err_mask = err_mask;
        ent->timestamp = get_jiffies_64();
}

static struct ata_ering_entry * ata_ering_top(struct ata_ering *ering)
{
        struct ata_ering_entry *ent = &ering->ring[ering->cursor];
        if (!ent->err_mask)
                return NULL;
        return ent;
}

static int ata_ering_map(struct ata_ering *ering,
                         int (*map_fn)(struct ata_ering_entry *, void *),
                         void *arg)
{
        int idx, rc = 0;
        struct ata_ering_entry *ent;

        idx = ering->cursor;
        do {
                ent = &ering->ring[idx];
                if (!ent->err_mask)
                        break;
                rc = map_fn(ent, arg);
                if (rc)
                        break;
                idx = (idx - 1 + ATA_ERING_SIZE) % ATA_ERING_SIZE;
        } while (idx != ering->cursor);

        return rc;
}

/**
 *      ata_scsi_timed_out - SCSI layer time out callback
 *      @cmd: timed out SCSI command
 *
 *      Handles SCSI layer timeout.  We race with normal completion of
 *      the qc for @cmd.  If the qc is already gone, we lose and let
 *      the scsi command finish (EH_HANDLED).  Otherwise, the qc has
 *      timed out and EH should be invoked.  Prevent ata_qc_complete()
 *      from finishing it by setting EH_SCHEDULED and return
 *      EH_NOT_HANDLED.
 *
 *      TODO: kill this function once old EH is gone.
 *
 *      LOCKING:
 *      Called from timer context
 *
 *      RETURNS:
 *      EH_HANDLED or EH_NOT_HANDLED
 */
enum scsi_eh_timer_return ata_scsi_timed_out(struct scsi_cmnd *cmd)
{
        struct Scsi_Host *host = cmd->device->host;
        struct ata_port *ap = ata_shost_to_port(host);
        unsigned long flags;
        struct ata_queued_cmd *qc;
        enum scsi_eh_timer_return ret;

        DPRINTK("ENTER\n");

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

        ret = EH_HANDLED;
        spin_lock_irqsave(&ap->host_set->lock, flags);
        qc = ata_qc_from_tag(ap, ap->active_tag);
        if (qc) {
                WARN_ON(qc->scsicmd != cmd);
                qc->flags |= ATA_QCFLAG_EH_SCHEDULED;
                qc->err_mask |= AC_ERR_TIMEOUT;
                ret = EH_NOT_HANDLED;
        }
        spin_unlock_irqrestore(&ap->host_set->lock, flags);

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

/**
 *      ata_scsi_error - SCSI layer error handler callback
 *      @host: SCSI host on which error occurred
 *
 *      Handles SCSI-layer-thrown error events.
 *
 *      LOCKING:
 *      Inherited from SCSI layer (none, can sleep)
 *
 *      RETURNS:
 *      Zero.
 */
void ata_scsi_error(struct Scsi_Host *host)
{
        struct ata_port *ap = ata_shost_to_port(host);
        spinlock_t *hs_lock = &ap->host_set->lock;
        int i, repeat_cnt = ATA_EH_MAX_REPEAT;
        unsigned long flags;

        DPRINTK("ENTER\n");

        /* synchronize with port task */
        ata_port_flush_task(ap);

        /* synchronize with host_set lock and sort out timeouts */

        /* For new EH, all qcs are finished in one of three ways -
         * normal completion, error completion, and SCSI timeout.
         * Both cmpletions can race against SCSI timeout.  When normal
         * completion wins, the qc never reaches EH.  When error
         * completion wins, the qc has ATA_QCFLAG_FAILED set.
         *
         * When SCSI timeout wins, things are a bit more complex.
         * Normal or error completion can occur after the timeout but
         * before this point.  In such cases, both types of
         * completions are honored.  A scmd is determined to have
         * timed out iff its associated qc is active and not failed.
         */
        if (ap->ops->error_handler) {
                struct scsi_cmnd *scmd, *tmp;
                int nr_timedout = 0;

                spin_lock_irqsave(hs_lock, flags);

                list_for_each_entry_safe(scmd, tmp, &host->eh_cmd_q, eh_entry) {
                        struct ata_queued_cmd *qc;

                        for (i = 0; i < ATA_MAX_QUEUE; i++) {
                                qc = __ata_qc_from_tag(ap, i);
                                if (qc->flags & ATA_QCFLAG_ACTIVE &&
                                    qc->scsicmd == scmd)
                                        break;
                        }

                        if (i < ATA_MAX_QUEUE) {
                                /* the scmd has an associated qc */
                                if (!(qc->flags & ATA_QCFLAG_FAILED)) {
                                        /* which hasn't failed yet, timeout */
                                        qc->err_mask |= AC_ERR_TIMEOUT;
                                        qc->flags |= ATA_QCFLAG_FAILED;
                                        nr_timedout++;
                                }
                        } else {
                                /* Normal completion occurred after
                                 * SCSI timeout but before this point.
                                 * Successfully complete it.
                                 */
                                scmd->retries = scmd->allowed;
                                scsi_eh_finish_cmd(scmd, &ap->eh_done_q);
                        }
                }

                /* If we have timed out qcs.  They belong to EH from
                 * this point but the state of the controller is
                 * unknown.  Freeze the port to make sure the IRQ
                 * handler doesn't diddle with those qcs.  This must
                 * be done atomically w.r.t. setting QCFLAG_FAILED.
                 */
                if (nr_timedout)
                        __ata_port_freeze(ap);

                spin_unlock_irqrestore(hs_lock, flags);
        } else
                spin_unlock_wait(hs_lock);

 repeat:
        /* invoke error handler */
        if (ap->ops->error_handler) {
                /* clear EH pending */
                spin_lock_irqsave(hs_lock, flags);
                ap->flags &= ~ATA_FLAG_EH_PENDING;
                spin_unlock_irqrestore(hs_lock, flags);

                /* invoke EH */
                ap->ops->error_handler(ap);

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

                if (ap->flags & ATA_FLAG_EH_PENDING) {
                        if (--repeat_cnt) {
                                ata_port_printk(ap, KERN_INFO,
                                        "EH pending after completion, "
                                        "repeating EH (cnt=%d)\n", repeat_cnt);
                                spin_unlock_irqrestore(hs_lock, flags);
                                goto repeat;
                        }
                        ata_port_printk(ap, KERN_ERR, "EH pending after %d "
                                        "tries, giving up\n", ATA_EH_MAX_REPEAT);
                }

                /* Clear host_eh_scheduled while holding hs_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(hs_lock, flags);
        } else {
                WARN_ON(ata_qc_from_tag(ap, ap->active_tag) == NULL);
                ap->ops->eng_timeout(ap);
        }

        /* finish or retry handled scmd's and clean up */
        WARN_ON(host->host_failed || !list_empty(&host->eh_cmd_q));

        scsi_eh_flush_done_q(&ap->eh_done_q);

        /* clean up */
        spin_lock_irqsave(hs_lock, flags);

        if (ap->flags & ATA_FLAG_RECOVERED)
                ata_port_printk(ap, KERN_INFO, "EH complete\n");
        ap->flags &= ~ATA_FLAG_RECOVERED;

        spin_unlock_irqrestore(hs_lock, flags);

        DPRINTK("EXIT\n");
}

/**
 *      ata_qc_timeout - Handle timeout of queued command
 *      @qc: Command that timed out
 *
 *      Some part of the kernel (currently, only the SCSI layer)
 *      has noticed that the active command on port @ap has not
 *      completed after a specified length of time.  Handle this
 *      condition by disabling DMA (if necessary) and completing
 *      transactions, with error if necessary.
 *
 *      This also handles the case of the "lost interrupt", where
 *      for some reason (possibly hardware bug, possibly driver bug)
 *      an interrupt was not delivered to the driver, even though the
 *      transaction completed successfully.
 *
 *      TODO: kill this function once old EH is gone.
 *
 *      LOCKING:
 *      Inherited from SCSI layer (none, can sleep)
 */
static void ata_qc_timeout(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;
        struct ata_host_set *host_set = ap->host_set;
        u8 host_stat = 0, drv_stat;
        unsigned long flags;

        DPRINTK("ENTER\n");

        ap->hsm_task_state = HSM_ST_IDLE;

        spin_lock_irqsave(&host_set->lock, flags);

        switch (qc->tf.protocol) {

        case ATA_PROT_DMA:
        case ATA_PROT_ATAPI_DMA:
                host_stat = ap->ops->bmdma_status(ap);

                /* before we do anything else, clear DMA-Start bit */
                ap->ops->bmdma_stop(qc);

                /* fall through */

        default:
                ata_altstatus(ap);
                drv_stat = ata_chk_status(ap);

                /* ack bmdma irq events */
                ap->ops->irq_clear(ap);

                ata_dev_printk(qc->dev, KERN_ERR, "command 0x%x timeout, "
                               "stat 0x%x host_stat 0x%x\n",
                               qc->tf.command, drv_stat, host_stat);

                /* complete taskfile transaction */
                qc->err_mask |= ac_err_mask(drv_stat);
                break;
        }

        spin_unlock_irqrestore(&host_set->lock, flags);

        ata_eh_qc_complete(qc);

        DPRINTK("EXIT\n");
}

/**
 *      ata_eng_timeout - Handle timeout of queued command
 *      @ap: Port on which timed-out command is active
 *
 *      Some part of the kernel (currently, only the SCSI layer)
 *      has noticed that the active command on port @ap has not
 *      completed after a specified length of time.  Handle this
 *      condition by disabling DMA (if necessary) and completing
 *      transactions, with error if necessary.
 *
 *      This also handles the case of the "lost interrupt", where
 *      for some reason (possibly hardware bug, possibly driver bug)
 *      an interrupt was not delivered to the driver, even though the
 *      transaction completed successfully.
 *
 *      TODO: kill this function once old EH is gone.
 *
 *      LOCKING:
 *      Inherited from SCSI layer (none, can sleep)
 */
void ata_eng_timeout(struct ata_port *ap)
{
        DPRINTK("ENTER\n");

        ata_qc_timeout(ata_qc_from_tag(ap, ap->active_tag));

        DPRINTK("EXIT\n");
}

/**
 *      ata_qc_schedule_eh - schedule qc for error handling
 *      @qc: command to schedule error handling for
 *
 *      Schedule error handling for @qc.  EH will kick in as soon as
 *      other commands are drained.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */
void ata_qc_schedule_eh(struct ata_queued_cmd *qc)
{
        struct ata_port *ap = qc->ap;

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

        qc->flags |= ATA_QCFLAG_FAILED;
        qc->ap->flags |= ATA_FLAG_EH_PENDING;

        /* The following will fail if timeout has already expired.
         * ata_scsi_error() takes care of such scmds on EH entry.
         * Note that ATA_QCFLAG_FAILED is unconditionally set after
         * this function completes.
         */
        scsi_req_abort_cmd(qc->scsicmd);
}

/**
 *      ata_port_schedule_eh - schedule error handling without a qc
 *      @ap: ATA port to schedule EH for
 *
 *      Schedule error handling for @ap.  EH will kick in as soon as
 *      all commands are drained.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */
void ata_port_schedule_eh(struct ata_port *ap)
{
        WARN_ON(!ap->ops->error_handler);

        ap->flags |= ATA_FLAG_EH_PENDING;
        ata_schedule_scsi_eh(ap->host);

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

/**
 *      ata_port_abort - abort all qc's on the port
 *      @ap: ATA port to abort qc's for
 *
 *      Abort all active qc's of @ap and schedule EH.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 *
 *      RETURNS:
 *      Number of aborted qc's.
 */
int ata_port_abort(struct ata_port *ap)
{
        int tag, nr_aborted = 0;

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

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

                if (qc) {
                        qc->flags |= ATA_QCFLAG_FAILED;
                        ata_qc_complete(qc);
                        nr_aborted++;
                }
        }

        if (!nr_aborted)
                ata_port_schedule_eh(ap);

        return nr_aborted;
}

/**
 *      __ata_port_freeze - freeze port
 *      @ap: ATA port to freeze
 *
 *      This function is called when HSM violation or some other
 *      condition disrupts normal operation of the port.  Frozen port
 *      is not allowed to perform any operation until the port is
 *      thawed, which usually follows a successful reset.
 *
 *      ap->ops->freeze() callback can be used for freezing the port
 *      hardware-wise (e.g. mask interrupt and stop DMA engine).  If a
 *      port cannot be frozen hardware-wise, the interrupt handler
 *      must ack and clear interrupts unconditionally while the port
 *      is frozen.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 */
static void __ata_port_freeze(struct ata_port *ap)
{
        WARN_ON(!ap->ops->error_handler);

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

        ap->flags |= ATA_FLAG_FROZEN;

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

/**
 *      ata_port_freeze - abort & freeze port
 *      @ap: ATA port to freeze
 *
 *      Abort and freeze @ap.
 *
 *      LOCKING:
 *      spin_lock_irqsave(host_set lock)
 *
 *      RETURNS:
 *      Number of aborted commands.
 */
int ata_port_freeze(struct ata_port *ap)
{
        int nr_aborted;

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

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

        return nr_aborted;
}

/**
 *      ata_eh_freeze_port - EH helper to freeze port
 *      @ap: ATA port to freeze
 *
 *      Freeze @ap.
 *
 *      LOCKING:
 *      None.
 */
void ata_eh_freeze_port(struct ata_port *ap)
{
        unsigned long flags;

        if (!ap->ops->error_handler)
                return;

        spin_lock_irqsave(&ap->host_set->lock, flags);
        __ata_port_freeze(ap);
        spin_unlock_irqrestore(&ap->host_set->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->host_set->lock, flags);

        ap->flags &= ~ATA_FLAG_FROZEN;

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

        spin_unlock_irqrestore(&ap->host_set->lock, flags);

        DPRINTK("ata%u port thawed\n", ap->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->host_set->lock, flags);
        qc->scsidone = ata_eh_scsidone;
        __ata_qc_complete(qc);
        WARN_ON(ata_tag_valid(qc->tag));
        spin_unlock_irqrestore(&ap->host_set->lock, flags);

        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);
}