sas_scsi_host.c

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/*
 * Serial Attached SCSI (SAS) class SCSI Host glue.
 *
 * Copyright (C) 2005 Adaptec, Inc.  All rights reserved.
 * Copyright (C) 2005 Luben Tuikov <[email protected]>
 *
 * This file is licensed under GPLv2.
 *
 * 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 of the
 * License, 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; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 * USA
 *
 */

#include <linux/kthread.h>
#include <linux/firmware.h>
#include <linux/export.h>
#include <linux/ctype.h>

#include "sas_internal.h"

#include <scsi/scsi_host.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_tcq.h>
#include <scsi/scsi.h>
#include <scsi/scsi_eh.h>
#include <scsi/scsi_transport.h>
#include <scsi/scsi_transport_sas.h>
#include <scsi/sas_ata.h>
#include "../scsi_sas_internal.h"
#include "../scsi_transport_api.h"
#include "../scsi_priv.h"

#include <linux/err.h>
#include <linux/blkdev.h>
#include <linux/freezer.h>
#include <linux/gfp.h>
#include <linux/scatterlist.h>
#include <linux/libata.h>

/* record final status and free the task */
static void sas_end_task(struct scsi_cmnd *sc, struct sas_task *task)
{
    struct task_status_struct *ts = &task->task_status;
    int hs = 0, stat = 0;

    if (ts->resp == SAS_TASK_UNDELIVERED) {
        /* transport error */
        hs = DID_NO_CONNECT;
    } else { /* ts->resp == SAS_TASK_COMPLETE */
        /* task delivered, what happened afterwards? */
        switch (ts->stat) {
        case SAS_DEV_NO_RESPONSE:
        case SAS_INTERRUPTED:
        case SAS_PHY_DOWN:
        case SAS_NAK_R_ERR:
        case SAS_OPEN_TO:
            hs = DID_NO_CONNECT;
            break;
        case SAS_DATA_UNDERRUN:
            scsi_set_resid(sc, ts->residual);
            if (scsi_bufflen(sc) - scsi_get_resid(sc) < sc->underflow)
                hs = DID_ERROR;
            break;
        case SAS_DATA_OVERRUN:
            hs = DID_ERROR;
            break;
        case SAS_QUEUE_FULL:
            hs = DID_SOFT_ERROR; /* retry */
            break;
        case SAS_DEVICE_UNKNOWN:
            hs = DID_BAD_TARGET;
            break;
        case SAS_SG_ERR:
            hs = DID_PARITY;
            break;
        case SAS_OPEN_REJECT:
            if (ts->open_rej_reason == SAS_OREJ_RSVD_RETRY)
                hs = DID_SOFT_ERROR; /* retry */
            else
                hs = DID_ERROR;
            break;
        case SAS_PROTO_RESPONSE:
            SAS_DPRINTK("LLDD:%s sent SAS_PROTO_RESP for an SSP "
                    "task; please report this\n",
                    task->dev->port->ha->sas_ha_name);
            break;
        case SAS_ABORTED_TASK:
            hs = DID_ABORT;
            break;
        case SAM_STAT_CHECK_CONDITION:
            memcpy(sc->sense_buffer, ts->buf,
                   min(SCSI_SENSE_BUFFERSIZE, ts->buf_valid_size));
            stat = SAM_STAT_CHECK_CONDITION;
            break;
        default:
            stat = ts->stat;
            break;
        }
    }

    sc->result = (hs << 16) | stat;
    ASSIGN_SAS_TASK(sc, NULL);
    list_del_init(&task->list);
    sas_free_task(task);
}

static void sas_scsi_task_done(struct sas_task *task)
{
    struct scsi_cmnd *sc = task->uldd_task;
    struct domain_device *dev = task->dev;
    struct sas_ha_struct *ha = dev->port->ha;
    unsigned long flags;

    spin_lock_irqsave(&dev->done_lock, flags);
    if (test_bit(SAS_HA_FROZEN, &ha->state))
        task = NULL;
    else
        ASSIGN_SAS_TASK(sc, NULL);
    spin_unlock_irqrestore(&dev->done_lock, flags);

    if (unlikely(!task)) {
        /* task will be completed by the error handler */
        SAS_DPRINTK("task done but aborted\n");
        return;
    }

    if (unlikely(!sc)) {
        SAS_DPRINTK("task_done called with non existing SCSI cmnd!\n");
        list_del_init(&task->list);
        sas_free_task(task);
        return;
    }

    sas_end_task(sc, task);
    sc->scsi_done(sc);
}

static struct sas_task *sas_create_task(struct scsi_cmnd *cmd,
                           struct domain_device *dev,
                           gfp_t gfp_flags)
{
    struct sas_task *task = sas_alloc_task(gfp_flags);
    struct scsi_lun lun;

    if (!task)
        return NULL;

    task->uldd_task = cmd;
    ASSIGN_SAS_TASK(cmd, task);

    task->dev = dev;
    task->task_proto = task->dev->tproto; /* BUG_ON(!SSP) */

    task->ssp_task.retry_count = 1;
    int_to_scsilun(cmd->device->lun, &lun);
    memcpy(task->ssp_task.LUN, &lun.scsi_lun, 8);
    task->ssp_task.task_attr = TASK_ATTR_SIMPLE;
    memcpy(task->ssp_task.cdb, cmd->cmnd, 16);

    task->scatter = scsi_sglist(cmd);
    task->num_scatter = scsi_sg_count(cmd);
    task->total_xfer_len = scsi_bufflen(cmd);
    task->data_dir = cmd->sc_data_direction;

    task->task_done = sas_scsi_task_done;

    return task;
}

int sas_queue_up(struct sas_task *task)
{
    struct sas_ha_struct *sas_ha = task->dev->port->ha;
    struct scsi_core *core = &sas_ha->core;
    unsigned long flags;
    LIST_HEAD(list);

    spin_lock_irqsave(&core->task_queue_lock, flags);
    if (sas_ha->lldd_queue_size < core->task_queue_size + 1) {
        spin_unlock_irqrestore(&core->task_queue_lock, flags);
        return -SAS_QUEUE_FULL;
    }
    list_add_tail(&task->list, &core->task_queue);
    core->task_queue_size += 1;
    spin_unlock_irqrestore(&core->task_queue_lock, flags);
    wake_up_process(core->queue_thread);

    return 0;
}

int sas_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *cmd)
{
    struct sas_internal *i = to_sas_internal(host->transportt);
    struct domain_device *dev = cmd_to_domain_dev(cmd);
    struct sas_ha_struct *sas_ha = dev->port->ha;
    struct sas_task *task;
    int res = 0;

    /* If the device fell off, no sense in issuing commands */
    if (test_bit(SAS_DEV_GONE, &dev->state)) {
        cmd->result = DID_BAD_TARGET << 16;
        goto out_done;
    }

    if (dev_is_sata(dev)) {
        spin_lock_irq(dev->sata_dev.ap->lock);
        res = ata_sas_queuecmd(cmd, dev->sata_dev.ap);
        spin_unlock_irq(dev->sata_dev.ap->lock);
        return res;
    }

    task = sas_create_task(cmd, dev, GFP_ATOMIC);
    if (!task)
        return SCSI_MLQUEUE_HOST_BUSY;

    /* Queue up, Direct Mode or Task Collector Mode. */
    if (sas_ha->lldd_max_execute_num < 2)
        res = i->dft->lldd_execute_task(task, 1, GFP_ATOMIC);
    else
        res = sas_queue_up(task);

    if (res)
        goto out_free_task;
    return 0;

out_free_task:
    SAS_DPRINTK("lldd_execute_task returned: %d\n", res);
    ASSIGN_SAS_TASK(cmd, NULL);
    sas_free_task(task);
    if (res == -SAS_QUEUE_FULL)
        cmd->result = DID_SOFT_ERROR << 16; /* retry */
    else
        cmd->result = DID_ERROR << 16;
out_done:
    cmd->scsi_done(cmd);
    return 0;
}

static void sas_eh_finish_cmd(struct scsi_cmnd *cmd)
{
    struct sas_ha_struct *sas_ha = SHOST_TO_SAS_HA(cmd->device->host);
    struct sas_task *task = TO_SAS_TASK(cmd);

    /* At this point, we only get called following an actual abort
     * of the task, so we should be guaranteed not to be racing with
     * any completions from the LLD.  Task is freed after this.
     */
    sas_end_task(cmd, task);

    /* now finish the command and move it on to the error
     * handler done list, this also takes it off the
     * error handler pending list.
     */
    scsi_eh_finish_cmd(cmd, &sas_ha->eh_done_q);
}

static void sas_eh_defer_cmd(struct scsi_cmnd *cmd)
{
    struct domain_device *dev = cmd_to_domain_dev(cmd);
    struct sas_ha_struct *ha = dev->port->ha;
    struct sas_task *task = TO_SAS_TASK(cmd);

    if (!dev_is_sata(dev)) {
        sas_eh_finish_cmd(cmd);
        return;
    }

    /* report the timeout to libata */
    sas_end_task(cmd, task);
    list_move_tail(&cmd->eh_entry, &ha->eh_ata_q);
}

static void sas_scsi_clear_queue_lu(struct list_head *error_q, struct scsi_cmnd *my_cmd)
{
    struct scsi_cmnd *cmd, *n;

    list_for_each_entry_safe(cmd, n, error_q, eh_entry) {
        if (cmd->device->sdev_target == my_cmd->device->sdev_target &&
            cmd->device->lun == my_cmd->device->lun)
            sas_eh_defer_cmd(cmd);
    }
}

static void sas_scsi_clear_queue_I_T(struct list_head *error_q,
                     struct domain_device *dev)
{
    struct scsi_cmnd *cmd, *n;

    list_for_each_entry_safe(cmd, n, error_q, eh_entry) {
        struct domain_device *x = cmd_to_domain_dev(cmd);

        if (x == dev)
            sas_eh_finish_cmd(cmd);
    }
}

static void sas_scsi_clear_queue_port(struct list_head *error_q,
                      struct asd_sas_port *port)
{
    struct scsi_cmnd *cmd, *n;

    list_for_each_entry_safe(cmd, n, error_q, eh_entry) {
        struct domain_device *dev = cmd_to_domain_dev(cmd);
        struct asd_sas_port *x = dev->port;

        if (x == port)
            sas_eh_finish_cmd(cmd);
    }
}

enum task_disposition {
    TASK_IS_DONE,
    TASK_IS_ABORTED,
    TASK_IS_AT_LU,
    TASK_IS_NOT_AT_HA,
    TASK_IS_NOT_AT_LU,
    TASK_ABORT_FAILED,
};

static enum task_disposition sas_scsi_find_task(struct sas_task *task)
{
    struct sas_ha_struct *ha = task->dev->port->ha;
    unsigned long flags;
    int i, res;
    struct sas_internal *si =
        to_sas_internal(task->dev->port->ha->core.shost->transportt);

    if (ha->lldd_max_execute_num > 1) {
        struct scsi_core *core = &ha->core;
        struct sas_task *t, *n;

        mutex_lock(&core->task_queue_flush);
        spin_lock_irqsave(&core->task_queue_lock, flags);
        list_for_each_entry_safe(t, n, &core->task_queue, list)
            if (task == t) {
                list_del_init(&t->list);
                break;
            }
        spin_unlock_irqrestore(&core->task_queue_lock, flags);
        mutex_unlock(&core->task_queue_flush);

        if (task == t)
            return TASK_IS_NOT_AT_HA;
    }

    for (i = 0; i < 5; i++) {
        SAS_DPRINTK("%s: aborting task 0x%p\n", __func__, task);
        res = si->dft->lldd_abort_task(task);

        spin_lock_irqsave(&task->task_state_lock, flags);
        if (task->task_state_flags & SAS_TASK_STATE_DONE) {
            spin_unlock_irqrestore(&task->task_state_lock, flags);
            SAS_DPRINTK("%s: task 0x%p is done\n", __func__,
                    task);
            return TASK_IS_DONE;
        }
        spin_unlock_irqrestore(&task->task_state_lock, flags);

        if (res == TMF_RESP_FUNC_COMPLETE) {
            SAS_DPRINTK("%s: task 0x%p is aborted\n",
                    __func__, task);
            return TASK_IS_ABORTED;
        } else if (si->dft->lldd_query_task) {
            SAS_DPRINTK("%s: querying task 0x%p\n",
                    __func__, task);
            res = si->dft->lldd_query_task(task);
            switch (res) {
            case TMF_RESP_FUNC_SUCC:
                SAS_DPRINTK("%s: task 0x%p at LU\n",
                        __func__, task);
                return TASK_IS_AT_LU;
            case TMF_RESP_FUNC_COMPLETE:
                SAS_DPRINTK("%s: task 0x%p not at LU\n",
                        __func__, task);
                return TASK_IS_NOT_AT_LU;
            case TMF_RESP_FUNC_FAILED:
                                SAS_DPRINTK("%s: task 0x%p failed to abort\n",
                                                __func__, task);
                                return TASK_ABORT_FAILED;
                        }

        }
    }
    return res;
}

static int sas_recover_lu(struct domain_device *dev, struct scsi_cmnd *cmd)
{
    int res = TMF_RESP_FUNC_FAILED;
    struct scsi_lun lun;
    struct sas_internal *i =
        to_sas_internal(dev->port->ha->core.shost->transportt);

    int_to_scsilun(cmd->device->lun, &lun);

    SAS_DPRINTK("eh: device %llx LUN %x has the task\n",
            SAS_ADDR(dev->sas_addr),
            cmd->device->lun);

    if (i->dft->lldd_abort_task_set)
        res = i->dft->lldd_abort_task_set(dev, lun.scsi_lun);

    if (res == TMF_RESP_FUNC_FAILED) {
        if (i->dft->lldd_clear_task_set)
            res = i->dft->lldd_clear_task_set(dev, lun.scsi_lun);
    }

    if (res == TMF_RESP_FUNC_FAILED) {
        if (i->dft->lldd_lu_reset)
            res = i->dft->lldd_lu_reset(dev, lun.scsi_lun);
    }

    return res;
}

static int sas_recover_I_T(struct domain_device *dev)
{
    int res = TMF_RESP_FUNC_FAILED;
    struct sas_internal *i =
        to_sas_internal(dev->port->ha->core.shost->transportt);

    SAS_DPRINTK("I_T nexus reset for dev %016llx\n",
            SAS_ADDR(dev->sas_addr));

    if (i->dft->lldd_I_T_nexus_reset)
        res = i->dft->lldd_I_T_nexus_reset(dev);

    return res;
}

/* take a reference on the last known good phy for this device */
struct sas_phy *sas_get_local_phy(struct domain_device *dev)
{
    struct sas_ha_struct *ha = dev->port->ha;
    struct sas_phy *phy;
    unsigned long flags;

    /* a published domain device always has a valid phy, it may be
     * stale, but it is never NULL
     */
    BUG_ON(!dev->phy);

    spin_lock_irqsave(&ha->phy_port_lock, flags);
    phy = dev->phy;
    get_device(&phy->dev);
    spin_unlock_irqrestore(&ha->phy_port_lock, flags);

    return phy;
}
EXPORT_SYMBOL_GPL(sas_get_local_phy);

static void sas_wait_eh(struct domain_device *dev)
{
    struct sas_ha_struct *ha = dev->port->ha;
    DEFINE_WAIT(wait);

    if (dev_is_sata(dev)) {
        ata_port_wait_eh(dev->sata_dev.ap);
        return;
    }
 retry:
    spin_lock_irq(&ha->lock);

    while (test_bit(SAS_DEV_EH_PENDING, &dev->state)) {
        prepare_to_wait(&ha->eh_wait_q, &wait, TASK_UNINTERRUPTIBLE);
        spin_unlock_irq(&ha->lock);
        schedule();
        spin_lock_irq(&ha->lock);
    }
    finish_wait(&ha->eh_wait_q, &wait);

    spin_unlock_irq(&ha->lock);

    /* make sure SCSI EH is complete */
    if (scsi_host_in_recovery(ha->core.shost)) {
        msleep(10);
        goto retry;
    }
}
EXPORT_SYMBOL(sas_wait_eh);

static int sas_queue_reset(struct domain_device *dev, int reset_type, int lun, int wait)
{
    struct sas_ha_struct *ha = dev->port->ha;
    int scheduled = 0, tries = 100;

    /* ata: promote lun reset to bus reset */
    if (dev_is_sata(dev)) {
        sas_ata_schedule_reset(dev);
        if (wait)
            sas_ata_wait_eh(dev);
        return SUCCESS;
    }

    while (!scheduled && tries--) {
        spin_lock_irq(&ha->lock);
        if (!test_bit(SAS_DEV_EH_PENDING, &dev->state) &&
            !test_bit(reset_type, &dev->state)) {
            scheduled = 1;
            ha->eh_active++;
            list_add_tail(&dev->ssp_dev.eh_list_node, &ha->eh_dev_q);
            set_bit(SAS_DEV_EH_PENDING, &dev->state);
            set_bit(reset_type, &dev->state);
            int_to_scsilun(lun, &dev->ssp_dev.reset_lun);
            scsi_schedule_eh(ha->core.shost);
        }
        spin_unlock_irq(&ha->lock);

        if (wait)
            sas_wait_eh(dev);

        if (scheduled)
            return SUCCESS;
    }

    SAS_DPRINTK("%s reset of %s failed\n",
            reset_type == SAS_DEV_LU_RESET ? "LUN" : "Bus",
            dev_name(&dev->rphy->dev));

    return FAILED;
}

int sas_eh_abort_handler(struct scsi_cmnd *cmd)
{
    int res;
    struct sas_task *task = TO_SAS_TASK(cmd);
    struct Scsi_Host *host = cmd->device->host;
    struct sas_internal *i = to_sas_internal(host->transportt);

    if (current != host->ehandler)
        return FAILED;

    if (!i->dft->lldd_abort_task)
        return FAILED;

    res = i->dft->lldd_abort_task(task);
    if (res == TMF_RESP_FUNC_SUCC || res == TMF_RESP_FUNC_COMPLETE)
        return SUCCESS;

    return FAILED;
}
EXPORT_SYMBOL_GPL(sas_eh_abort_handler);

/* Attempt to send a LUN reset message to a device */
int sas_eh_device_reset_handler(struct scsi_cmnd *cmd)
{
    int res;
    struct scsi_lun lun;
    struct Scsi_Host *host = cmd->device->host;
    struct domain_device *dev = cmd_to_domain_dev(cmd);
    struct sas_internal *i = to_sas_internal(host->transportt);

    if (current != host->ehandler)
        return sas_queue_reset(dev, SAS_DEV_LU_RESET, cmd->device->lun, 0);

    int_to_scsilun(cmd->device->lun, &lun);

    if (!i->dft->lldd_lu_reset)
        return FAILED;

    res = i->dft->lldd_lu_reset(dev, lun.scsi_lun);
    if (res == TMF_RESP_FUNC_SUCC || res == TMF_RESP_FUNC_COMPLETE)
        return SUCCESS;

    return FAILED;
}

int sas_eh_bus_reset_handler(struct scsi_cmnd *cmd)
{
    int res;
    struct Scsi_Host *host = cmd->device->host;
    struct domain_device *dev = cmd_to_domain_dev(cmd);
    struct sas_internal *i = to_sas_internal(host->transportt);

    if (current != host->ehandler)
        return sas_queue_reset(dev, SAS_DEV_RESET, 0, 0);

    if (!i->dft->lldd_I_T_nexus_reset)
        return FAILED;

    res = i->dft->lldd_I_T_nexus_reset(dev);
    if (res == TMF_RESP_FUNC_SUCC || res == TMF_RESP_FUNC_COMPLETE ||
        res == -ENODEV)
        return SUCCESS;

    return FAILED;
}

/* Try to reset a device */
static int try_to_reset_cmd_device(struct scsi_cmnd *cmd)
{
    int res;
    struct Scsi_Host *shost = cmd->device->host;

    if (!shost->hostt->eh_device_reset_handler)
        goto try_bus_reset;

    res = shost->hostt->eh_device_reset_handler(cmd);
    if (res == SUCCESS)
        return res;

try_bus_reset:
    if (shost->hostt->eh_bus_reset_handler)
        return shost->hostt->eh_bus_reset_handler(cmd);

    return FAILED;
}

static void sas_eh_handle_sas_errors(struct Scsi_Host *shost, struct list_head *work_q)
{
    struct scsi_cmnd *cmd, *n;
    enum task_disposition res = TASK_IS_DONE;
    int tmf_resp, need_reset;
    struct sas_internal *i = to_sas_internal(shost->transportt);
    unsigned long flags;
    struct sas_ha_struct *ha = SHOST_TO_SAS_HA(shost);
    LIST_HEAD(done);

    /* clean out any commands that won the completion vs eh race */
    list_for_each_entry_safe(cmd, n, work_q, eh_entry) {
        struct domain_device *dev = cmd_to_domain_dev(cmd);
        struct sas_task *task;

        spin_lock_irqsave(&dev->done_lock, flags);
        /* by this point the lldd has either observed
         * SAS_HA_FROZEN and is leaving the task alone, or has
         * won the race with eh and decided to complete it
         */
        task = TO_SAS_TASK(cmd);
        spin_unlock_irqrestore(&dev->done_lock, flags);

        if (!task)
            list_move_tail(&cmd->eh_entry, &done);
    }

 Again:
    list_for_each_entry_safe(cmd, n, work_q, eh_entry) {
        struct sas_task *task = TO_SAS_TASK(cmd);

        list_del_init(&cmd->eh_entry);

        spin_lock_irqsave(&task->task_state_lock, flags);
        need_reset = task->task_state_flags & SAS_TASK_NEED_DEV_RESET;
        spin_unlock_irqrestore(&task->task_state_lock, flags);

        if (need_reset) {
            SAS_DPRINTK("%s: task 0x%p requests reset\n",
                    __func__, task);
            goto reset;
        }

        SAS_DPRINTK("trying to find task 0x%p\n", task);
        res = sas_scsi_find_task(task);

        cmd->eh_eflags = 0;

        switch (res) {
        case TASK_IS_NOT_AT_HA:
            SAS_DPRINTK("%s: task 0x%p is not at ha: %s\n",
                    __func__, task,
                    cmd->retries ? "retry" : "aborted");
            if (cmd->retries)
                cmd->retries--;
            sas_eh_finish_cmd(cmd);
            continue;
        case TASK_IS_DONE:
            SAS_DPRINTK("%s: task 0x%p is done\n", __func__,
                    task);
            sas_eh_defer_cmd(cmd);
            continue;
        case TASK_IS_ABORTED:
            SAS_DPRINTK("%s: task 0x%p is aborted\n",
                    __func__, task);
            sas_eh_defer_cmd(cmd);
            continue;
        case TASK_IS_AT_LU:
            SAS_DPRINTK("task 0x%p is at LU: lu recover\n", task);
 reset:
            tmf_resp = sas_recover_lu(task->dev, cmd);
            if (tmf_resp == TMF_RESP_FUNC_COMPLETE) {
                SAS_DPRINTK("dev %016llx LU %x is "
                        "recovered\n",
                        SAS_ADDR(task->dev),
                        cmd->device->lun);
                sas_eh_defer_cmd(cmd);
                sas_scsi_clear_queue_lu(work_q, cmd);
                goto Again;
            }
            /* fallthrough */
        case TASK_IS_NOT_AT_LU:
        case TASK_ABORT_FAILED:
            SAS_DPRINTK("task 0x%p is not at LU: I_T recover\n",
                    task);
            tmf_resp = sas_recover_I_T(task->dev);
            if (tmf_resp == TMF_RESP_FUNC_COMPLETE ||
                tmf_resp == -ENODEV) {
                struct domain_device *dev = task->dev;
                SAS_DPRINTK("I_T %016llx recovered\n",
                        SAS_ADDR(task->dev->sas_addr));
                sas_eh_finish_cmd(cmd);
                sas_scsi_clear_queue_I_T(work_q, dev);
                goto Again;
            }
            /* Hammer time :-) */
            try_to_reset_cmd_device(cmd);
            if (i->dft->lldd_clear_nexus_port) {
                struct asd_sas_port *port = task->dev->port;
                SAS_DPRINTK("clearing nexus for port:%d\n",
                        port->id);
                res = i->dft->lldd_clear_nexus_port(port);
                if (res == TMF_RESP_FUNC_COMPLETE) {
                    SAS_DPRINTK("clear nexus port:%d "
                            "succeeded\n", port->id);
                    sas_eh_finish_cmd(cmd);
                    sas_scsi_clear_queue_port(work_q,
                                  port);
                    goto Again;
                }
            }
            if (i->dft->lldd_clear_nexus_ha) {
                SAS_DPRINTK("clear nexus ha\n");
                res = i->dft->lldd_clear_nexus_ha(ha);
                if (res == TMF_RESP_FUNC_COMPLETE) {
                    SAS_DPRINTK("clear nexus ha "
                            "succeeded\n");
                    sas_eh_finish_cmd(cmd);
                    goto clear_q;
                }
            }
            /* If we are here -- this means that no amount
             * of effort could recover from errors.  Quite
             * possibly the HA just disappeared.
             */
            SAS_DPRINTK("error from  device %llx, LUN %x "
                    "couldn't be recovered in any way\n",
                    SAS_ADDR(task->dev->sas_addr),
                    cmd->device->lun);

            sas_eh_finish_cmd(cmd);
            goto clear_q;
        }
    }
 out:
    list_splice_tail(&done, work_q);
    list_splice_tail_init(&ha->eh_ata_q, work_q);
    return;

 clear_q:
    SAS_DPRINTK("--- Exit %s -- clear_q\n", __func__);
    list_for_each_entry_safe(cmd, n, work_q, eh_entry)
        sas_eh_finish_cmd(cmd);
    goto out;
}

static void sas_eh_handle_resets(struct Scsi_Host *shost)
{
    struct sas_ha_struct *ha = SHOST_TO_SAS_HA(shost);
    struct sas_internal *i = to_sas_internal(shost->transportt);

    /* handle directed resets to sas devices */
    spin_lock_irq(&ha->lock);
    while (!list_empty(&ha->eh_dev_q)) {
        struct domain_device *dev;
        struct ssp_device *ssp;

        ssp = list_entry(ha->eh_dev_q.next, typeof(*ssp), eh_list_node);
        list_del_init(&ssp->eh_list_node);
        dev = container_of(ssp, typeof(*dev), ssp_dev);
        kref_get(&dev->kref);
        WARN_ONCE(dev_is_sata(dev), "ssp reset to ata device?\n");

        spin_unlock_irq(&ha->lock);

        if (test_and_clear_bit(SAS_DEV_LU_RESET, &dev->state))
            i->dft->lldd_lu_reset(dev, ssp->reset_lun.scsi_lun);

        if (test_and_clear_bit(SAS_DEV_RESET, &dev->state))
            i->dft->lldd_I_T_nexus_reset(dev);

        sas_put_device(dev);
        spin_lock_irq(&ha->lock);
        clear_bit(SAS_DEV_EH_PENDING, &dev->state);
        ha->eh_active--;
    }
    spin_unlock_irq(&ha->lock);
}


void sas_scsi_recover_host(struct Scsi_Host *shost)
{
    struct sas_ha_struct *ha = SHOST_TO_SAS_HA(shost);
    LIST_HEAD(eh_work_q);
    int tries = 0;
    bool retry;

retry:
    tries++;
    retry = true;
    spin_lock_irq(shost->host_lock);
    list_splice_init(&shost->eh_cmd_q, &eh_work_q);
    spin_unlock_irq(shost->host_lock);

    SAS_DPRINTK("Enter %s busy: %d failed: %d\n",
            __func__, shost->host_busy, shost->host_failed);
    /*
     * Deal with commands that still have SAS tasks (i.e. they didn't
     * complete via the normal sas_task completion mechanism),
     * SAS_HA_FROZEN gives eh dominion over all sas_task completion.
     */
    set_bit(SAS_HA_FROZEN, &ha->state);
    sas_eh_handle_sas_errors(shost, &eh_work_q);
    clear_bit(SAS_HA_FROZEN, &ha->state);
    if (list_empty(&eh_work_q))
        goto out;

    /*
     * Now deal with SCSI commands that completed ok but have a an error
     * code (and hopefully sense data) attached.  This is roughly what
     * scsi_unjam_host does, but we skip scsi_eh_abort_cmds because any
     * command we see here has no sas_task and is thus unknown to the HA.
     */
    sas_ata_eh(shost, &eh_work_q, &ha->eh_done_q);
    if (!scsi_eh_get_sense(&eh_work_q, &ha->eh_done_q))
        scsi_eh_ready_devs(shost, &eh_work_q, &ha->eh_done_q);

out:
    if (ha->lldd_max_execute_num > 1)
        wake_up_process(ha->core.queue_thread);

    sas_eh_handle_resets(shost);

    /* now link into libata eh --- if we have any ata devices */
    sas_ata_strategy_handler(shost);

    scsi_eh_flush_done_q(&ha->eh_done_q);

    /* check if any new eh work was scheduled during the last run */
    spin_lock_irq(&ha->lock);
    if (ha->eh_active == 0) {
        shost->host_eh_scheduled = 0;
        retry = false;
    }
    spin_unlock_irq(&ha->lock);

    if (retry)
        goto retry;

    SAS_DPRINTK("--- Exit %s: busy: %d failed: %d tries: %d\n",
            __func__, shost->host_busy, shost->host_failed, tries);
}

enum blk_eh_timer_return sas_scsi_timed_out(struct scsi_cmnd *cmd)
{
    scmd_printk(KERN_DEBUG, cmd, "command %p timed out\n", cmd);

    return BLK_EH_NOT_HANDLED;
}

int sas_ioctl(struct scsi_device *sdev, int cmd, void __user *arg)
{
    struct domain_device *dev = sdev_to_domain_dev(sdev);

    if (dev_is_sata(dev))
        return ata_sas_scsi_ioctl(dev->sata_dev.ap, sdev, cmd, arg);

    return -EINVAL;
}

struct domain_device *sas_find_dev_by_rphy(struct sas_rphy *rphy)
{
    struct Scsi_Host *shost = dev_to_shost(rphy->dev.parent);
    struct sas_ha_struct *ha = SHOST_TO_SAS_HA(shost);
    struct domain_device *found_dev = NULL;
    int i;
    unsigned long flags;

    spin_lock_irqsave(&ha->phy_port_lock, flags);
    for (i = 0; i < ha->num_phys; i++) {
        struct asd_sas_port *port = ha->sas_port[i];
        struct domain_device *dev;

        spin_lock(&port->dev_list_lock);
        list_for_each_entry(dev, &port->dev_list, dev_list_node) {
            if (rphy == dev->rphy) {
                found_dev = dev;
                spin_unlock(&port->dev_list_lock);
                goto found;
            }
        }
        spin_unlock(&port->dev_list_lock);
    }
 found:
    spin_unlock_irqrestore(&ha->phy_port_lock, flags);

    return found_dev;
}

int sas_target_alloc(struct scsi_target *starget)
{
    struct sas_rphy *rphy = dev_to_rphy(starget->dev.parent);
    struct domain_device *found_dev = sas_find_dev_by_rphy(rphy);

    if (!found_dev)
        return -ENODEV;

    kref_get(&found_dev->kref);
    starget->hostdata = found_dev;
    return 0;
}

#define SAS_DEF_QD 256

int sas_slave_configure(struct scsi_device *scsi_dev)
{
    struct domain_device *dev = sdev_to_domain_dev(scsi_dev);
    struct sas_ha_struct *sas_ha;

    BUG_ON(dev->rphy->identify.device_type != SAS_END_DEVICE);

    if (dev_is_sata(dev)) {
        ata_sas_slave_configure(scsi_dev, dev->sata_dev.ap);
        return 0;
    }

    sas_ha = dev->port->ha;

    sas_read_port_mode_page(scsi_dev);

    if (scsi_dev->tagged_supported) {
        scsi_set_tag_type(scsi_dev, MSG_SIMPLE_TAG);
        scsi_activate_tcq(scsi_dev, SAS_DEF_QD);
    } else {
        SAS_DPRINTK("device %llx, LUN %x doesn't support "
                "TCQ\n", SAS_ADDR(dev->sas_addr),
                scsi_dev->lun);
        scsi_dev->tagged_supported = 0;
        scsi_set_tag_type(scsi_dev, 0);
        scsi_deactivate_tcq(scsi_dev, 1);
    }

    scsi_dev->allow_restart = 1;

    return 0;
}

int sas_change_queue_depth(struct scsi_device *sdev, int depth, int reason)
{
    struct domain_device *dev = sdev_to_domain_dev(sdev);

    if (dev_is_sata(dev))
        return __ata_change_queue_depth(dev->sata_dev.ap, sdev, depth,
                        reason);

    switch (reason) {
    case SCSI_QDEPTH_DEFAULT:
    case SCSI_QDEPTH_RAMP_UP:
        if (!sdev->tagged_supported)
            depth = 1;
        scsi_adjust_queue_depth(sdev, scsi_get_tag_type(sdev), depth);
        break;
    case SCSI_QDEPTH_QFULL:
        scsi_track_queue_full(sdev, depth);
        break;
    default:
        return -EOPNOTSUPP;
    }

    return depth;
}

int sas_change_queue_type(struct scsi_device *scsi_dev, int qt)
{
    struct domain_device *dev = sdev_to_domain_dev(scsi_dev);

    if (dev_is_sata(dev))
        return -EINVAL;

    if (!scsi_dev->tagged_supported)
        return 0;

    scsi_deactivate_tcq(scsi_dev, 1);

    scsi_set_tag_type(scsi_dev, qt);
    scsi_activate_tcq(scsi_dev, scsi_dev->queue_depth);

    return qt;
}

int sas_bios_param(struct scsi_device *scsi_dev,
              struct block_device *bdev,
              sector_t capacity, int *hsc)
{
    hsc[0] = 255;
    hsc[1] = 63;
    sector_div(capacity, 255*63);
    hsc[2] = capacity;

    return 0;
}

/* ---------- Task Collector Thread implementation ---------- */

static void sas_queue(struct sas_ha_struct *sas_ha)
{
    struct scsi_core *core = &sas_ha->core;
    unsigned long flags;
    LIST_HEAD(q);
    int can_queue;
    int res;
    struct sas_internal *i = to_sas_internal(core->shost->transportt);

    mutex_lock(&core->task_queue_flush);
    spin_lock_irqsave(&core->task_queue_lock, flags);
    while (!kthread_should_stop() &&
           !list_empty(&core->task_queue) &&
           !test_bit(SAS_HA_FROZEN, &sas_ha->state)) {

        can_queue = sas_ha->lldd_queue_size - core->task_queue_size;
        if (can_queue >= 0) {
            can_queue = core->task_queue_size;
            list_splice_init(&core->task_queue, &q);
        } else {
            struct list_head *a, *n;

            can_queue = sas_ha->lldd_queue_size;
            list_for_each_safe(a, n, &core->task_queue) {
                list_move_tail(a, &q);
                if (--can_queue == 0)
                    break;
            }
            can_queue = sas_ha->lldd_queue_size;
        }
        core->task_queue_size -= can_queue;
        spin_unlock_irqrestore(&core->task_queue_lock, flags);
        {
            struct sas_task *task = list_entry(q.next,
                               struct sas_task,
                               list);
            list_del_init(&q);
            res = i->dft->lldd_execute_task(task, can_queue,
                            GFP_KERNEL);
            if (unlikely(res))
                __list_add(&q, task->list.prev, &task->list);
        }
        spin_lock_irqsave(&core->task_queue_lock, flags);
        if (res) {
            list_splice_init(&q, &core->task_queue); /*at head*/
            core->task_queue_size += can_queue;
        }
    }
    spin_unlock_irqrestore(&core->task_queue_lock, flags);
    mutex_unlock(&core->task_queue_flush);
}

static int sas_queue_thread(void *_sas_ha)
{
    struct sas_ha_struct *sas_ha = _sas_ha;

    while (1) {
        set_current_state(TASK_INTERRUPTIBLE);
        schedule();
        sas_queue(sas_ha);
        if (kthread_should_stop())
            break;
    }

    return 0;
}

int sas_init_queue(struct sas_ha_struct *sas_ha)
{
    struct scsi_core *core = &sas_ha->core;

    spin_lock_init(&core->task_queue_lock);
    mutex_init(&core->task_queue_flush);
    core->task_queue_size = 0;
    INIT_LIST_HEAD(&core->task_queue);

    core->queue_thread = kthread_run(sas_queue_thread, sas_ha,
                     "sas_queue_%d", core->shost->host_no);
    if (IS_ERR(core->queue_thread))
        return PTR_ERR(core->queue_thread);
    return 0;
}

void sas_shutdown_queue(struct sas_ha_struct *sas_ha)
{
    unsigned long flags;
    struct scsi_core *core = &sas_ha->core;
    struct sas_task *task, *n;

    kthread_stop(core->queue_thread);

    if (!list_empty(&core->task_queue))
        SAS_DPRINTK("HA: %llx: scsi core task queue is NOT empty!?\n",
                SAS_ADDR(sas_ha->sas_addr));

    spin_lock_irqsave(&core->task_queue_lock, flags);
    list_for_each_entry_safe(task, n, &core->task_queue, list) {
        struct scsi_cmnd *cmd = task->uldd_task;

        list_del_init(&task->list);

        ASSIGN_SAS_TASK(cmd, NULL);
        sas_free_task(task);
        cmd->result = DID_ABORT << 16;
        cmd->scsi_done(cmd);
    }
    spin_unlock_irqrestore(&core->task_queue_lock, flags);
}

/*
 * Tell an upper layer that it needs to initiate an abort for a given task.
 * This should only ever be called by an LLDD.
 */
void sas_task_abort(struct sas_task *task)
{
    struct scsi_cmnd *sc = task->uldd_task;

    /* Escape for libsas internal commands */
    if (!sc) {
        struct sas_task_slow *slow = task->slow_task;

        if (!slow)
            return;
        if (!del_timer(&slow->timer))
            return;
        slow->timer.function(slow->timer.data);
        return;
    }

    if (dev_is_sata(task->dev)) {
        sas_ata_task_abort(task);
    } else {
        struct request_queue *q = sc->device->request_queue;
        unsigned long flags;

        spin_lock_irqsave(q->queue_lock, flags);
        blk_abort_request(sc->request);
        spin_unlock_irqrestore(q->queue_lock, flags);
    }
}

void sas_target_destroy(struct scsi_target *starget)
{
    struct domain_device *found_dev = starget->hostdata;

    if (!found_dev)
        return;

    starget->hostdata = NULL;
    sas_put_device(found_dev);
}

static void sas_parse_addr(u8 *sas_addr, const char *p)
{
    int i;
    for (i = 0; i < SAS_ADDR_SIZE; i++) {
        u8 h, l;
        if (!*p)
            break;
        h = isdigit(*p) ? *p-'0' : toupper(*p)-'A'+10;
        p++;
        l = isdigit(*p) ? *p-'0' : toupper(*p)-'A'+10;
        p++;
        sas_addr[i] = (h<<4) | l;
    }
}

#define SAS_STRING_ADDR_SIZE    16

int sas_request_addr(struct Scsi_Host *shost, u8 *addr)
{
    int res;
    const struct firmware *fw;

    res = request_firmware(&fw, "sas_addr", &shost->shost_gendev);
    if (res)
        return res;

    if (fw->size < SAS_STRING_ADDR_SIZE) {
        res = -ENODEV;
        goto out;
    }

    sas_parse_addr(addr, fw->data);

out:
    release_firmware(fw);
    return res;
}
EXPORT_SYMBOL_GPL(sas_request_addr);

EXPORT_SYMBOL_GPL(sas_queuecommand);
EXPORT_SYMBOL_GPL(sas_target_alloc);
EXPORT_SYMBOL_GPL(sas_slave_configure);
EXPORT_SYMBOL_GPL(sas_change_queue_depth);
EXPORT_SYMBOL_GPL(sas_change_queue_type);
EXPORT_SYMBOL_GPL(sas_bios_param);
EXPORT_SYMBOL_GPL(sas_task_abort);
EXPORT_SYMBOL_GPL(sas_phy_reset);
EXPORT_SYMBOL_GPL(sas_eh_device_reset_handler);
EXPORT_SYMBOL_GPL(sas_eh_bus_reset_handler);
EXPORT_SYMBOL_GPL(sas_target_destroy);
EXPORT_SYMBOL_GPL(sas_ioctl);