/*
 * LSI/Engenio/NetApp E-Series RDAC SCSI Device Handler
 *
 * Copyright (C) 2005 Mike Christie. All rights reserved.
 * Copyright (C) Chandra Seetharaman, IBM Corp. 2007
 *
 * 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 <scsi/scsi.h>
#include <scsi/scsi_eh.h>
#include <scsi/scsi_dh.h>
#include <linux/workqueue.h>
#include <linux/slab.h>
#include <linux/module.h>

#define RDAC_NAME "rdac"
#define RDAC_RETRY_COUNT 5

/*
 * LSI mode page stuff
 *
 * These struct definitions and the forming of the
 * mode page were taken from the LSI RDAC 2.4 GPL'd
 * driver, and then converted to Linux conventions.
 */
#define RDAC_QUIESCENCE_TIME 20
/*
 * Page Codes
 */
#define RDAC_PAGE_CODE_REDUNDANT_CONTROLLER 0x2c

/*
 * Controller modes definitions
 */
#define RDAC_MODE_TRANSFER_SPECIFIED_LUNS       0x02

/*
 * RDAC Options field
 */
#define RDAC_FORCED_QUIESENCE 0x02

#define RDAC_TIMEOUT    (60 * HZ)
#define RDAC_RETRIES    3

struct rdac_mode_6_hdr {
        u8      data_len;
        u8      medium_type;
        u8      device_params;
        u8      block_desc_len;
};

struct rdac_mode_10_hdr {
        u16     data_len;
        u8      medium_type;
        u8      device_params;
        u16     reserved;
        u16     block_desc_len;
};

struct rdac_mode_common {
        u8      controller_serial[16];
        u8      alt_controller_serial[16];
        u8      rdac_mode[2];
        u8      alt_rdac_mode[2];
        u8      quiescence_timeout;
        u8      rdac_options;
};

struct rdac_pg_legacy {
        struct rdac_mode_6_hdr hdr;
        u8      page_code;
        u8      page_len;
        struct rdac_mode_common common;
#define MODE6_MAX_LUN   32
        u8      lun_table[MODE6_MAX_LUN];
        u8      reserved2[32];
        u8      reserved3;
        u8      reserved4;
};

struct rdac_pg_expanded {
        struct rdac_mode_10_hdr hdr;
        u8      page_code;
        u8      subpage_code;
        u8      page_len[2];
        struct rdac_mode_common common;
        u8      lun_table[256];
        u8      reserved3;
        u8      reserved4;
};

struct c9_inquiry {
        u8      peripheral_info;
        u8      page_code;      /* 0xC9 */
        u8      reserved1;
        u8      page_len;
        u8      page_id[4];     /* "vace" */
        u8      avte_cvp;
        u8      path_prio;
        u8      reserved2[38];
};

#define SUBSYS_ID_LEN   16
#define SLOT_ID_LEN     2
#define ARRAY_LABEL_LEN 31

struct c4_inquiry {
        u8      peripheral_info;
        u8      page_code;      /* 0xC4 */
        u8      reserved1;
        u8      page_len;
        u8      page_id[4];     /* "subs" */
        u8      subsys_id[SUBSYS_ID_LEN];
        u8      revision[4];
        u8      slot_id[SLOT_ID_LEN];
        u8      reserved[2];
};

#define UNIQUE_ID_LEN 16
struct c8_inquiry {
        u8      peripheral_info;
        u8      page_code; /* 0xC8 */
        u8      reserved1;
        u8      page_len;
        u8      page_id[4]; /* "edid" */
        u8      reserved2[3];
        u8      vol_uniq_id_len;
        u8      vol_uniq_id[16];
        u8      vol_user_label_len;
        u8      vol_user_label[60];
        u8      array_uniq_id_len;
        u8      array_unique_id[UNIQUE_ID_LEN];
        u8      array_user_label_len;
        u8      array_user_label[60];
        u8      lun[8];
};

struct rdac_controller {
        u8                      array_id[UNIQUE_ID_LEN];
        int                     use_ms10;
        struct kref             kref;
        struct list_head        node; /* list of all controllers */
        union                   {
                struct rdac_pg_legacy legacy;
                struct rdac_pg_expanded expanded;
        } mode_select;
        u8      index;
        u8      array_name[ARRAY_LABEL_LEN];
        struct Scsi_Host        *host;
        spinlock_t              ms_lock;
        int                     ms_queued;
        struct work_struct      ms_work;
        struct scsi_device      *ms_sdev;
        struct list_head        ms_head;
        struct list_head        dh_list;
};

struct c2_inquiry {
        u8      peripheral_info;
        u8      page_code;      /* 0xC2 */
        u8      reserved1;
        u8      page_len;
        u8      page_id[4];     /* "swr4" */
        u8      sw_version[3];
        u8      sw_date[3];
        u8      features_enabled;
        u8      max_lun_supported;
        u8      partitions[239]; /* Total allocation length should be 0xFF */
};

struct rdac_dh_data {
        struct list_head        node;
        struct rdac_controller  *ctlr;
        struct scsi_device      *sdev;
#define UNINITIALIZED_LUN       (1 << 8)
        unsigned                lun;

#define RDAC_MODE               0
#define RDAC_MODE_AVT           1
#define RDAC_MODE_IOSHIP        2
        unsigned char           mode;

#define RDAC_STATE_ACTIVE       0
#define RDAC_STATE_PASSIVE      1
        unsigned char           state;

#define RDAC_LUN_UNOWNED        0
#define RDAC_LUN_OWNED          1
        char                    lun_state;

#define RDAC_PREFERRED          0
#define RDAC_NON_PREFERRED      1
        char                    preferred;

        union                   {
                struct c2_inquiry c2;
                struct c4_inquiry c4;
                struct c8_inquiry c8;
                struct c9_inquiry c9;
        } inq;
};

static const char *mode[] = {
        "RDAC",
        "AVT",
        "IOSHIP",
};
static const char *lun_state[] =
{
        "unowned",
        "owned",
};

struct rdac_queue_data {
        struct list_head        entry;
        struct rdac_dh_data     *h;
        activate_complete       callback_fn;
        void                    *callback_data;
};

static LIST_HEAD(ctlr_list);
static DEFINE_SPINLOCK(list_lock);
static struct workqueue_struct *kmpath_rdacd;
static void send_mode_select(struct work_struct *work);

/*
 * module parameter to enable rdac debug logging.
 * 2 bits for each type of logging, only two types defined for now
 * Can be enhanced if required at later point
 */
static int rdac_logging = 1;
module_param(rdac_logging, int, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(rdac_logging, "A bit mask of rdac logging levels, "
                "Default is 1 - failover logging enabled, "
                "set it to 0xF to enable all the logs");

#define RDAC_LOG_FAILOVER       0
#define RDAC_LOG_SENSE          2

#define RDAC_LOG_BITS           2

#define RDAC_LOG_LEVEL(SHIFT)  \
        ((rdac_logging >> (SHIFT)) & ((1 << (RDAC_LOG_BITS)) - 1))

#define RDAC_LOG(SHIFT, sdev, f, arg...) \
do { \
        if (unlikely(RDAC_LOG_LEVEL(SHIFT))) \
                sdev_printk(KERN_INFO, sdev, RDAC_NAME ": " f "\n", ## arg); \
} while (0);

static unsigned int rdac_failover_get(struct rdac_controller *ctlr,
                                      struct list_head *list,
                                      unsigned char *cdb)
{
        struct rdac_mode_common *common;
        unsigned data_size;
        struct rdac_queue_data *qdata;
        u8 *lun_table;

        if (ctlr->use_ms10) {
                struct rdac_pg_expanded *rdac_pg;

                data_size = sizeof(struct rdac_pg_expanded);
                rdac_pg = &ctlr->mode_select.expanded;
                memset(rdac_pg, 0, data_size);
                common = &rdac_pg->common;
                rdac_pg->page_code = RDAC_PAGE_CODE_REDUNDANT_CONTROLLER + 0x40;
                rdac_pg->subpage_code = 0x1;
                rdac_pg->page_len[0] = 0x01;
                rdac_pg->page_len[1] = 0x28;
                lun_table = rdac_pg->lun_table;
        } else {
                struct rdac_pg_legacy *rdac_pg;

                data_size = sizeof(struct rdac_pg_legacy);
                rdac_pg = &ctlr->mode_select.legacy;
                memset(rdac_pg, 0, data_size);
                common = &rdac_pg->common;
                rdac_pg->page_code = RDAC_PAGE_CODE_REDUNDANT_CONTROLLER;
                rdac_pg->page_len = 0x68;
                lun_table = rdac_pg->lun_table;
        }
        common->rdac_mode[1] = RDAC_MODE_TRANSFER_SPECIFIED_LUNS;
        common->quiescence_timeout = RDAC_QUIESCENCE_TIME;
        common->rdac_options = RDAC_FORCED_QUIESENCE;

        list_for_each_entry(qdata, list, entry) {
                lun_table[qdata->h->lun] = 0x81;
        }

        /* Prepare the command. */
        if (ctlr->use_ms10) {
                cdb[0] = MODE_SELECT_10;
                cdb[7] = data_size >> 8;
                cdb[8] = data_size & 0xff;
        } else {
                cdb[0] = MODE_SELECT;
                cdb[4] = data_size;
        }

        return data_size;
}

static void release_controller(struct kref *kref)
{
        struct rdac_controller *ctlr;
        ctlr = container_of(kref, struct rdac_controller, kref);

        list_del(&ctlr->node);
        kfree(ctlr);
}

static struct rdac_controller *get_controller(int index, char *array_name,
                        u8 *array_id, struct scsi_device *sdev)
{
        struct rdac_controller *ctlr, *tmp;

        list_for_each_entry(tmp, &ctlr_list, node) {
                if ((memcmp(tmp->array_id, array_id, UNIQUE_ID_LEN) == 0) &&
                          (tmp->index == index) &&
                          (tmp->host == sdev->host)) {
                        kref_get(&tmp->kref);
                        return tmp;
                }
        }
        ctlr = kmalloc_obj(*ctlr, GFP_ATOMIC);
        if (!ctlr)
                return NULL;

        /* initialize fields of controller */
        memcpy(ctlr->array_id, array_id, UNIQUE_ID_LEN);
        ctlr->index = index;
        ctlr->host = sdev->host;
        memcpy(ctlr->array_name, array_name, ARRAY_LABEL_LEN);

        kref_init(&ctlr->kref);
        ctlr->use_ms10 = -1;
        ctlr->ms_queued = 0;
        ctlr->ms_sdev = NULL;
        spin_lock_init(&ctlr->ms_lock);
        INIT_WORK(&ctlr->ms_work, send_mode_select);
        INIT_LIST_HEAD(&ctlr->ms_head);
        list_add(&ctlr->node, &ctlr_list);
        INIT_LIST_HEAD(&ctlr->dh_list);

        return ctlr;
}

static int get_lun_info(struct scsi_device *sdev, struct rdac_dh_data *h,
                        char *array_name, u8 *array_id)
{
        int err = SCSI_DH_IO, i;
        struct c8_inquiry *inqp = &h->inq.c8;

        if (!scsi_get_vpd_page(sdev, 0xC8, (unsigned char *)inqp,
                               sizeof(struct c8_inquiry))) {
                if (inqp->page_code != 0xc8)
                        return SCSI_DH_NOSYS;
                if (inqp->page_id[0] != 'e' || inqp->page_id[1] != 'd' ||
                    inqp->page_id[2] != 'i' || inqp->page_id[3] != 'd')
                        return SCSI_DH_NOSYS;
                h->lun = inqp->lun[7]; /* Uses only the last byte */

                for(i=0; i<ARRAY_LABEL_LEN-1; ++i)
                        *(array_name+i) = inqp->array_user_label[(2*i)+1];

                *(array_name+ARRAY_LABEL_LEN-1) = '\0';
                memset(array_id, 0, UNIQUE_ID_LEN);
                memcpy(array_id, inqp->array_unique_id, inqp->array_uniq_id_len);
                err = SCSI_DH_OK;
        }
        return err;
}

static int check_ownership(struct scsi_device *sdev, struct rdac_dh_data *h)
{
        int err = SCSI_DH_IO, access_state;
        struct rdac_dh_data *tmp;
        struct c9_inquiry *inqp = &h->inq.c9;

        h->state = RDAC_STATE_ACTIVE;
        if (!scsi_get_vpd_page(sdev, 0xC9, (unsigned char *)inqp,
                               sizeof(struct c9_inquiry))) {
                /* detect the operating mode */
                if ((inqp->avte_cvp >> 5) & 0x1)
                        h->mode = RDAC_MODE_IOSHIP; /* LUN in IOSHIP mode */
                else if (inqp->avte_cvp >> 7)
                        h->mode = RDAC_MODE_AVT; /* LUN in AVT mode */
                else
                        h->mode = RDAC_MODE; /* LUN in RDAC mode */

                /* Update ownership */
                if (inqp->avte_cvp & 0x1) {
                        h->lun_state = RDAC_LUN_OWNED;
                        access_state = SCSI_ACCESS_STATE_OPTIMAL;
                } else {
                        h->lun_state = RDAC_LUN_UNOWNED;
                        if (h->mode == RDAC_MODE) {
                                h->state = RDAC_STATE_PASSIVE;
                                access_state = SCSI_ACCESS_STATE_STANDBY;
                        } else
                                access_state = SCSI_ACCESS_STATE_ACTIVE;
                }

                /* Update path prio*/
                if (inqp->path_prio & 0x1) {
                        h->preferred = RDAC_PREFERRED;
                        access_state |= SCSI_ACCESS_STATE_PREFERRED;
                } else
                        h->preferred = RDAC_NON_PREFERRED;
                rcu_read_lock();
                list_for_each_entry_rcu(tmp, &h->ctlr->dh_list, node) {
                        /* h->sdev should always be valid */
                        BUG_ON(!tmp->sdev);
                        tmp->sdev->access_state = access_state;
                }
                rcu_read_unlock();
                err = SCSI_DH_OK;
        }

        return err;
}

static int initialize_controller(struct scsi_device *sdev,
                struct rdac_dh_data *h, char *array_name, u8 *array_id)
{
        int err = SCSI_DH_IO, index;
        struct c4_inquiry *inqp = &h->inq.c4;

        if (!scsi_get_vpd_page(sdev, 0xC4, (unsigned char *)inqp,
                               sizeof(struct c4_inquiry))) {
                /* get the controller index */
                if (inqp->slot_id[1] == 0x31)
                        index = 0;
                else
                        index = 1;

                spin_lock(&list_lock);
                h->ctlr = get_controller(index, array_name, array_id, sdev);
                if (!h->ctlr)
                        err = SCSI_DH_RES_TEMP_UNAVAIL;
                else {
                        h->sdev = sdev;
                        list_add_rcu(&h->node, &h->ctlr->dh_list);
                }
                spin_unlock(&list_lock);
                err = SCSI_DH_OK;
        }
        return err;
}

static int set_mode_select(struct scsi_device *sdev, struct rdac_dh_data *h)
{
        int err = SCSI_DH_IO;
        struct c2_inquiry *inqp = &h->inq.c2;

        if (!scsi_get_vpd_page(sdev, 0xC2, (unsigned char *)inqp,
                               sizeof(struct c2_inquiry))) {
                /*
                 * If more than MODE6_MAX_LUN luns are supported, use
                 * mode select 10
                 */
                if (inqp->max_lun_supported >= MODE6_MAX_LUN)
                        h->ctlr->use_ms10 = 1;
                else
                        h->ctlr->use_ms10 = 0;
                err = SCSI_DH_OK;
        }
        return err;
}

static int mode_select_handle_sense(struct scsi_device *sdev,
                                    struct scsi_sense_hdr *sense_hdr)
{
        struct rdac_dh_data *h = sdev->handler_data;

        if (!scsi_sense_valid(sense_hdr))
                return SCSI_DH_IO;

        RDAC_LOG(RDAC_LOG_FAILOVER, sdev, "array %s, ctlr %d, "
                "MODE_SELECT returned with sense %02x/%02x/%02x",
                (char *) h->ctlr->array_name, h->ctlr->index,
                sense_hdr->sense_key, sense_hdr->asc, sense_hdr->ascq);

        return SCSI_DH_IO;
}

static void send_mode_select(struct work_struct *work)
{
        struct rdac_controller *ctlr =
                container_of(work, struct rdac_controller, ms_work);
        struct scsi_device *sdev = ctlr->ms_sdev;
        struct rdac_dh_data *h = sdev->handler_data;
        int rc, err;
        struct rdac_queue_data *tmp, *qdata;
        LIST_HEAD(list);
        unsigned char cdb[MAX_COMMAND_SIZE];
        struct scsi_sense_hdr sshdr;
        unsigned int data_size;
        blk_opf_t opf = REQ_OP_DRV_OUT | REQ_FAILFAST_DEV |
                                REQ_FAILFAST_TRANSPORT | REQ_FAILFAST_DRIVER;
        struct scsi_failure failure_defs[] = {
                {
                        .sense = NO_SENSE,
                        .asc = SCMD_FAILURE_ASC_ANY,
                        .ascq = SCMD_FAILURE_ASCQ_ANY,
                        .result = SAM_STAT_CHECK_CONDITION,
                },
                {
                        .sense = ABORTED_COMMAND,
                        .asc = SCMD_FAILURE_ASC_ANY,
                        .ascq = SCMD_FAILURE_ASCQ_ANY,
                        .result = SAM_STAT_CHECK_CONDITION,
                },
                {
                        .sense = UNIT_ATTENTION,
                        .asc = SCMD_FAILURE_ASC_ANY,
                        .ascq = SCMD_FAILURE_ASCQ_ANY,
                        .result = SAM_STAT_CHECK_CONDITION,
                },
                /* LUN Not Ready and is in the Process of Becoming Ready */
                {
                        .sense = NOT_READY,
                        .asc = 0x04,
                        .ascq = 0x01,
                        .result = SAM_STAT_CHECK_CONDITION,
                },
                /* Command Lock contention */
                {
                        .sense = ILLEGAL_REQUEST,
                        .asc = 0x91,
                        .ascq = 0x36,
                        .allowed = SCMD_FAILURE_NO_LIMIT,
                        .result = SAM_STAT_CHECK_CONDITION,
                },
                {}
        };
        struct scsi_failures failures = {
                .total_allowed = RDAC_RETRY_COUNT,
                .failure_definitions = failure_defs,
        };
        const struct scsi_exec_args exec_args = {
                .sshdr = &sshdr,
                .failures = &failures,
        };

        spin_lock(&ctlr->ms_lock);
        list_splice_init(&ctlr->ms_head, &list);
        ctlr->ms_queued = 0;
        ctlr->ms_sdev = NULL;
        spin_unlock(&ctlr->ms_lock);

        memset(cdb, 0, sizeof(cdb));

        data_size = rdac_failover_get(ctlr, &list, cdb);

        RDAC_LOG(RDAC_LOG_FAILOVER, sdev, "array %s, ctlr %d, queueing MODE_SELECT command",
                (char *)h->ctlr->array_name, h->ctlr->index);

        rc = scsi_execute_cmd(sdev, cdb, opf, &h->ctlr->mode_select, data_size,
                              RDAC_TIMEOUT * HZ, RDAC_RETRIES, &exec_args);
        if (!rc) {
                h->state = RDAC_STATE_ACTIVE;
                RDAC_LOG(RDAC_LOG_FAILOVER, sdev, "array %s, ctlr %d, "
                                "MODE_SELECT completed",
                                (char *) h->ctlr->array_name, h->ctlr->index);
                err = SCSI_DH_OK;
        } else if (rc < 0) {
                err = SCSI_DH_IO;
        } else {
                err = mode_select_handle_sense(sdev, &sshdr);
        }

        list_for_each_entry_safe(qdata, tmp, &list, entry) {
                list_del(&qdata->entry);
                if (err == SCSI_DH_OK)
                        qdata->h->state = RDAC_STATE_ACTIVE;
                if (qdata->callback_fn)
                        qdata->callback_fn(qdata->callback_data, err);
                kfree(qdata);
        }
        return;
}

static int queue_mode_select(struct scsi_device *sdev,
                                activate_complete fn, void *data)
{
        struct rdac_queue_data *qdata;
        struct rdac_controller *ctlr;

        qdata = kzalloc_obj(*qdata);
        if (!qdata)
                return SCSI_DH_RETRY;

        qdata->h = sdev->handler_data;
        qdata->callback_fn = fn;
        qdata->callback_data = data;

        ctlr = qdata->h->ctlr;
        spin_lock(&ctlr->ms_lock);
        list_add_tail(&qdata->entry, &ctlr->ms_head);
        if (!ctlr->ms_queued) {
                ctlr->ms_queued = 1;
                ctlr->ms_sdev = sdev;
                queue_work(kmpath_rdacd, &ctlr->ms_work);
        }
        spin_unlock(&ctlr->ms_lock);
        return SCSI_DH_OK;
}

static int rdac_activate(struct scsi_device *sdev,
                        activate_complete fn, void *data)
{
        struct rdac_dh_data *h = sdev->handler_data;
        int err = SCSI_DH_OK;
        int act = 0;

        err = check_ownership(sdev, h);
        if (err != SCSI_DH_OK)
                goto done;

        switch (h->mode) {
        case RDAC_MODE:
                if (h->lun_state == RDAC_LUN_UNOWNED)
                        act = 1;
                break;
        case RDAC_MODE_IOSHIP:
                if ((h->lun_state == RDAC_LUN_UNOWNED) &&
                    (h->preferred == RDAC_PREFERRED))
                        act = 1;
                break;
        default:
                break;
        }

        if (act) {
                err = queue_mode_select(sdev, fn, data);
                if (err == SCSI_DH_OK)
                        return 0;
        }
done:
        if (fn)
                fn(data, err);
        return 0;
}

static blk_status_t rdac_prep_fn(struct scsi_device *sdev, struct request *req)
{
        struct rdac_dh_data *h = sdev->handler_data;

        if (h->state != RDAC_STATE_ACTIVE) {
                req->rq_flags |= RQF_QUIET;
                return BLK_STS_IOERR;
        }

        return BLK_STS_OK;
}

static enum scsi_disposition rdac_check_sense(struct scsi_device *sdev,
                                              struct scsi_sense_hdr *sense_hdr)
{
        struct rdac_dh_data *h = sdev->handler_data;

        RDAC_LOG(RDAC_LOG_SENSE, sdev, "array %s, ctlr %d, "
                        "I/O returned with sense %02x/%02x/%02x",
                        (char *) h->ctlr->array_name, h->ctlr->index,
                        sense_hdr->sense_key, sense_hdr->asc, sense_hdr->ascq);

        switch (sense_hdr->sense_key) {
        case NOT_READY:
                if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x01)
                        /* LUN Not Ready - Logical Unit Not Ready and is in
                        * the process of becoming ready
                        * Just retry.
                        */
                        return ADD_TO_MLQUEUE;
                if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x81)
                        /* LUN Not Ready - Storage firmware incompatible
                         * Manual code synchonisation required.
                         *
                         * Nothing we can do here. Try to bypass the path.
                         */
                        return SUCCESS;
                if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0xA1)
                        /* LUN Not Ready - Quiescense in progress
                         *
                         * Just retry and wait.
                         */
                        return ADD_TO_MLQUEUE;
                if (sense_hdr->asc == 0xA1  && sense_hdr->ascq == 0x02)
                        /* LUN Not Ready - Quiescense in progress
                         * or has been achieved
                         * Just retry.
                         */
                        return ADD_TO_MLQUEUE;
                break;
        case ILLEGAL_REQUEST:
                if (sense_hdr->asc == 0x94 && sense_hdr->ascq == 0x01) {
                        /* Invalid Request - Current Logical Unit Ownership.
                         * Controller is not the current owner of the LUN,
                         * Fail the path, so that the other path be used.
                         */
                        h->state = RDAC_STATE_PASSIVE;
                        return SUCCESS;
                }
                break;
        case UNIT_ATTENTION:
                if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00)
                        /*
                         * Power On, Reset, or Bus Device Reset, just retry.
                         */
                        return ADD_TO_MLQUEUE;
                if (sense_hdr->asc == 0x8b && sense_hdr->ascq == 0x02)
                        /*
                         * Quiescence in progress , just retry.
                         */
                        return ADD_TO_MLQUEUE;
                break;
        }
        /* success just means we do not care what scsi-ml does */
        return SCSI_RETURN_NOT_HANDLED;
}

static int rdac_bus_attach(struct scsi_device *sdev)
{
        struct rdac_dh_data *h;
        int err;
        char array_name[ARRAY_LABEL_LEN];
        char array_id[UNIQUE_ID_LEN];

        h = kzalloc_obj(*h);
        if (!h)
                return SCSI_DH_NOMEM;
        h->lun = UNINITIALIZED_LUN;
        h->state = RDAC_STATE_ACTIVE;

        err = get_lun_info(sdev, h, array_name, array_id);
        if (err != SCSI_DH_OK)
                goto failed;

        err = initialize_controller(sdev, h, array_name, array_id);
        if (err != SCSI_DH_OK)
                goto failed;

        err = check_ownership(sdev, h);
        if (err != SCSI_DH_OK)
                goto clean_ctlr;

        err = set_mode_select(sdev, h);
        if (err != SCSI_DH_OK)
                goto clean_ctlr;

        sdev_printk(KERN_NOTICE, sdev,
                    "%s: LUN %d (%s) (%s)\n",
                    RDAC_NAME, h->lun, mode[(int)h->mode],
                    lun_state[(int)h->lun_state]);

        sdev->handler_data = h;
        return SCSI_DH_OK;

clean_ctlr:
        spin_lock(&list_lock);
        kref_put(&h->ctlr->kref, release_controller);
        spin_unlock(&list_lock);

failed:
        kfree(h);
        return err;
}

static void rdac_bus_detach( struct scsi_device *sdev )
{
        struct rdac_dh_data *h = sdev->handler_data;

        if (h->ctlr && h->ctlr->ms_queued)
                flush_workqueue(kmpath_rdacd);

        spin_lock(&list_lock);
        if (h->ctlr) {
                list_del_rcu(&h->node);
                kref_put(&h->ctlr->kref, release_controller);
        }
        spin_unlock(&list_lock);
        sdev->handler_data = NULL;
        synchronize_rcu();
        kfree(h);
}

static struct scsi_device_handler rdac_dh = {
        .name = RDAC_NAME,
        .module = THIS_MODULE,
        .prep_fn = rdac_prep_fn,
        .check_sense = rdac_check_sense,
        .attach = rdac_bus_attach,
        .detach = rdac_bus_detach,
        .activate = rdac_activate,
};

static int __init rdac_init(void)
{
        int r;

        r = scsi_register_device_handler(&rdac_dh);
        if (r != 0) {
                printk(KERN_ERR "Failed to register scsi device handler.");
                goto done;
        }

        /*
         * Create workqueue to handle mode selects for rdac
         */
        kmpath_rdacd =
                alloc_ordered_workqueue("%s", WQ_MEM_RECLAIM, "kmpath_rdacd");
        if (!kmpath_rdacd) {
                scsi_unregister_device_handler(&rdac_dh);
                printk(KERN_ERR "kmpath_rdacd creation failed.\n");

                r = -EINVAL;
        }
done:
        return r;
}

static void __exit rdac_exit(void)
{
        destroy_workqueue(kmpath_rdacd);
        scsi_unregister_device_handler(&rdac_dh);
}

module_init(rdac_init);
module_exit(rdac_exit);

MODULE_DESCRIPTION("Multipath LSI/Engenio/NetApp E-Series RDAC driver");
MODULE_AUTHOR("Mike Christie, Chandra Seetharaman");
MODULE_VERSION("01.00.0000.0000");
MODULE_LICENSE("GPL");