[SCSI] scsi_dh: add lsi rdac device handler

This patch provides the device handler to support the LSI RDAC SCSI
based storage devices.

Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

3 files changed, 698 insertions, 0 deletions

diff --git a/drivers/scsi/device_handler/Kconfig b/drivers/scsi/device_handler/Kconfig
index 228241d1d98c..404f37732627 100644
--- a/drivers/scsi/device_handler/Kconfig
+++ b/drivers/scsi/device_handler/Kconfig
@@ -10,3 +10,9 @@ menuconfig SCSI_DH
           SCSI Device Handlers provide device specific support for
           devices utilized in multipath configurations. Say Y here to
           select support for specific hardware.
+
+config SCSI_DH_RDAC
+        tristate "LSI RDAC Device Handler"
+        depends on SCSI_DH
+        help
+        If you have a LSI RDAC select y. Otherwise, say N.
diff --git a/drivers/scsi/device_handler/Makefile b/drivers/scsi/device_handler/Makefile
index f306e44e3837..1a42b3498318 100644
--- a/drivers/scsi/device_handler/Makefile
+++ b/drivers/scsi/device_handler/Makefile
@@ -2,3 +2,4 @@
 # SCSI Device Handler
 #
 obj-$(CONFIG_SCSI_DH)           += scsi_dh.o
+obj-$(CONFIG_SCSI_DH_RDAC)      += scsi_dh_rdac.o
diff --git a/drivers/scsi/device_handler/scsi_dh_rdac.c b/drivers/scsi/device_handler/scsi_dh_rdac.c
new file mode 100644
index 000000000000..6fff077a888d
--- /dev/null
+++ b/drivers/scsi/device_handler/scsi_dh_rdac.c
@@ -0,0 +1,691 @@
+/*
+ * Engenio/LSI 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>
+
+#define RDAC_NAME "rdac"
+
+/*
+ * 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
+
+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];
+};
+
+struct rdac_controller {
+        u8                      subsys_id[SUBSYS_ID_LEN];
+        u8                      slot_id[SLOT_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;
+};
+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[16];
+        u8      array_user_label_len;
+        u8      array_user_label[60];
+        u8      lun[8];
+};
+
+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 rdac_controller  *ctlr;
+#define UNINITIALIZED_LUN       (1 << 8)
+        unsigned                lun;
+#define RDAC_STATE_ACTIVE       0
+#define RDAC_STATE_PASSIVE      1
+        unsigned char           state;
+        unsigned char           sense[SCSI_SENSE_BUFFERSIZE];
+        union                   {
+                struct c2_inquiry c2;
+                struct c4_inquiry c4;
+                struct c8_inquiry c8;
+                struct c9_inquiry c9;
+        } inq;
+};
+
+static LIST_HEAD(ctlr_list);
+static DEFINE_SPINLOCK(list_lock);
+
+static inline struct rdac_dh_data *get_rdac_data(struct scsi_device *sdev)
+{
+        struct scsi_dh_data *scsi_dh_data = sdev->scsi_dh_data;
+        BUG_ON(scsi_dh_data == NULL);
+        return ((struct rdac_dh_data *) scsi_dh_data->buf);
+}
+
+static struct request *get_rdac_req(struct scsi_device *sdev,
+                        void *buffer, unsigned buflen, int rw)
+{
+        struct request *rq;
+        struct request_queue *q = sdev->request_queue;
+        struct rdac_dh_data *h = get_rdac_data(sdev);
+
+        rq = blk_get_request(q, rw, GFP_KERNEL);
+
+        if (!rq) {
+                sdev_printk(KERN_INFO, sdev,
+                                "get_rdac_req: blk_get_request failed.\n");
+                return NULL;
+        }
+
+        if (buflen && blk_rq_map_kern(q, rq, buffer, buflen, GFP_KERNEL)) {
+                blk_put_request(rq);
+                sdev_printk(KERN_INFO, sdev,
+                                "get_rdac_req: blk_rq_map_kern failed.\n");
+                return NULL;
+        }
+
+        memset(&rq->cmd, 0, BLK_MAX_CDB);
+        rq->sense = h->sense;
+        memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
+        rq->sense_len = 0;
+
+        rq->cmd_type = REQ_TYPE_BLOCK_PC;
+        rq->cmd_flags |= REQ_FAILFAST | REQ_NOMERGE;
+        rq->retries = RDAC_RETRIES;
+        rq->timeout = RDAC_TIMEOUT;
+
+        return rq;
+}
+
+static struct request *rdac_failover_get(struct scsi_device *sdev)
+{
+        struct request *rq;
+        struct rdac_mode_common *common;
+        unsigned data_size;
+        struct rdac_dh_data *h = get_rdac_data(sdev);
+
+        if (h->ctlr->use_ms10) {
+                struct rdac_pg_expanded *rdac_pg;
+
+                data_size = sizeof(struct rdac_pg_expanded);
+                rdac_pg = &h->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;
+                rdac_pg->lun_table[h->lun] = 0x81;
+        } else {
+                struct rdac_pg_legacy *rdac_pg;
+
+                data_size = sizeof(struct rdac_pg_legacy);
+                rdac_pg = &h->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;
+                rdac_pg->lun_table[h->lun] = 0x81;
+        }
+        common->rdac_mode[1] = RDAC_MODE_TRANSFER_SPECIFIED_LUNS;
+        common->quiescence_timeout = RDAC_QUIESCENCE_TIME;
+        common->rdac_options = RDAC_FORCED_QUIESENCE;
+
+        /* get request for block layer packet command */
+        rq = get_rdac_req(sdev, &h->ctlr->mode_select, data_size, WRITE);
+        if (!rq)
+                return NULL;
+
+        /* Prepare the command. */
+        if (h->ctlr->use_ms10) {
+                rq->cmd[0] = MODE_SELECT_10;
+                rq->cmd[7] = data_size >> 8;
+                rq->cmd[8] = data_size & 0xff;
+        } else {
+                rq->cmd[0] = MODE_SELECT;
+                rq->cmd[4] = data_size;
+        }
+        rq->cmd_len = COMMAND_SIZE(rq->cmd[0]);
+
+        return rq;
+}
+
+static void release_controller(struct kref *kref)
+{
+        struct rdac_controller *ctlr;
+        ctlr = container_of(kref, struct rdac_controller, kref);
+
+        spin_lock(&list_lock);
+        list_del(&ctlr->node);
+        spin_unlock(&list_lock);
+        kfree(ctlr);
+}
+
+static struct rdac_controller *get_controller(u8 *subsys_id, u8 *slot_id)
+{
+        struct rdac_controller *ctlr, *tmp;
+
+        spin_lock(&list_lock);
+
+        list_for_each_entry(tmp, &ctlr_list, node) {
+                if ((memcmp(tmp->subsys_id, subsys_id, SUBSYS_ID_LEN) == 0) &&
+                          (memcmp(tmp->slot_id, slot_id, SLOT_ID_LEN) == 0)) {
+                        kref_get(&tmp->kref);
+                        spin_unlock(&list_lock);
+                        return tmp;
+                }
+        }
+        ctlr = kmalloc(sizeof(*ctlr), GFP_ATOMIC);
+        if (!ctlr)
+                goto done;
+
+        /* initialize fields of controller */
+        memcpy(ctlr->subsys_id, subsys_id, SUBSYS_ID_LEN);
+        memcpy(ctlr->slot_id, slot_id, SLOT_ID_LEN);
+        kref_init(&ctlr->kref);
+        ctlr->use_ms10 = -1;
+        list_add(&ctlr->node, &ctlr_list);
+done:
+        spin_unlock(&list_lock);
+        return ctlr;
+}
+
+static int submit_inquiry(struct scsi_device *sdev, int page_code,
+                unsigned int len)
+{
+        struct request *rq;
+        struct request_queue *q = sdev->request_queue;
+        struct rdac_dh_data *h = get_rdac_data(sdev);
+        int err = SCSI_DH_RES_TEMP_UNAVAIL;
+
+        rq = get_rdac_req(sdev, &h->inq, len, READ);
+        if (!rq)
+                goto done;
+
+        /* Prepare the command. */
+        rq->cmd[0] = INQUIRY;
+        rq->cmd[1] = 1;
+        rq->cmd[2] = page_code;
+        rq->cmd[4] = len;
+        rq->cmd_len = COMMAND_SIZE(INQUIRY);
+        err = blk_execute_rq(q, NULL, rq, 1);
+        if (err == -EIO)
+                err = SCSI_DH_IO;
+done:
+        return err;
+}
+
+static int get_lun(struct scsi_device *sdev)
+{
+        int err;
+        struct c8_inquiry *inqp;
+        struct rdac_dh_data *h = get_rdac_data(sdev);
+
+        err = submit_inquiry(sdev, 0xC8, sizeof(struct c8_inquiry));
+        if (err == SCSI_DH_OK) {
+                inqp = &h->inq.c8;
+                h->lun = inqp->lun[7]; /* currently it uses only one byte */
+        }
+        return err;
+}
+
+#define RDAC_OWNED      0
+#define RDAC_UNOWNED    1
+#define RDAC_FAILED     2
+static int check_ownership(struct scsi_device *sdev)
+{
+        int err;
+        struct c9_inquiry *inqp;
+        struct rdac_dh_data *h = get_rdac_data(sdev);
+
+        err = submit_inquiry(sdev, 0xC9, sizeof(struct c9_inquiry));
+        if (err == SCSI_DH_OK) {
+                err = RDAC_UNOWNED;
+                inqp = &h->inq.c9;
+                /*
+                 * If in AVT mode or if the path already owns the LUN,
+                 * return RDAC_OWNED;
+                 */
+                if (((inqp->avte_cvp >> 7) == 0x1) ||
+                                 ((inqp->avte_cvp & 0x1) != 0))
+                        err = RDAC_OWNED;
+        } else
+                err = RDAC_FAILED;
+        return err;
+}
+
+static int initialize_controller(struct scsi_device *sdev)
+{
+        int err;
+        struct c4_inquiry *inqp;
+        struct rdac_dh_data *h = get_rdac_data(sdev);
+
+        err = submit_inquiry(sdev, 0xC4, sizeof(struct c4_inquiry));
+        if (err == SCSI_DH_OK) {
+                inqp = &h->inq.c4;
+                h->ctlr = get_controller(inqp->subsys_id, inqp->slot_id);
+                if (!h->ctlr)
+                        err = SCSI_DH_RES_TEMP_UNAVAIL;
+        }
+        return err;
+}
+
+static int set_mode_select(struct scsi_device *sdev)
+{
+        int err;
+        struct c2_inquiry *inqp;
+        struct rdac_dh_data *h = get_rdac_data(sdev);
+
+        err = submit_inquiry(sdev, 0xC2, sizeof(struct c2_inquiry));
+        if (err == SCSI_DH_OK) {
+                inqp = &h->inq.c2;
+                /*
+                 * 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;
+        }
+        return err;
+}
+
+static int mode_select_handle_sense(struct scsi_device *sdev)
+{
+        struct scsi_sense_hdr sense_hdr;
+        struct rdac_dh_data *h = get_rdac_data(sdev);
+        int sense, err = SCSI_DH_IO, ret;
+
+        ret = scsi_normalize_sense(h->sense, SCSI_SENSE_BUFFERSIZE, &sense_hdr);
+        if (!ret)
+                goto done;
+
+        err = SCSI_DH_OK;
+        sense = (sense_hdr.sense_key << 16) | (sense_hdr.asc << 8) |
+                        sense_hdr.ascq;
+        /* If it is retryable failure, submit the c9 inquiry again */
+        if (sense == 0x59136 || sense == 0x68b02 || sense == 0xb8b02 ||
+                            sense == 0x62900) {
+                /* 0x59136    - Command lock contention
+                 * 0x[6b]8b02 - Quiesense in progress or achieved
+                 * 0x62900    - Power On, Reset, or Bus Device Reset
+                 */
+                err = SCSI_DH_RETRY;
+        }
+
+        if (sense)
+                sdev_printk(KERN_INFO, sdev,
+                        "MODE_SELECT failed with sense 0x%x.\n", sense);
+done:
+        return err;
+}
+
+static int send_mode_select(struct scsi_device *sdev)
+{
+        struct request *rq;
+        struct request_queue *q = sdev->request_queue;
+        struct rdac_dh_data *h = get_rdac_data(sdev);
+        int err = SCSI_DH_RES_TEMP_UNAVAIL;
+
+        rq = rdac_failover_get(sdev);
+        if (!rq)
+                goto done;
+
+        sdev_printk(KERN_INFO, sdev, "queueing MODE_SELECT command.\n");
+
+        err = blk_execute_rq(q, NULL, rq, 1);
+        if (err != SCSI_DH_OK)
+                err = mode_select_handle_sense(sdev);
+        if (err == SCSI_DH_OK)
+                h->state = RDAC_STATE_ACTIVE;
+done:
+        return err;
+}
+
+static int rdac_activate(struct scsi_device *sdev)
+{
+        struct rdac_dh_data *h = get_rdac_data(sdev);
+        int err = SCSI_DH_OK;
+
+        if (h->lun == UNINITIALIZED_LUN) {
+                err = get_lun(sdev);
+                if (err != SCSI_DH_OK)
+                        goto done;
+        }
+
+        err = check_ownership(sdev);
+        switch (err) {
+        case RDAC_UNOWNED:
+                break;
+        case RDAC_OWNED:
+                err = SCSI_DH_OK;
+                goto done;
+        case RDAC_FAILED:
+        default:
+                err = SCSI_DH_IO;
+                goto done;
+        }
+
+        if (!h->ctlr) {
+                err = initialize_controller(sdev);
+                if (err != SCSI_DH_OK)
+                        goto done;
+        }
+
+        if (h->ctlr->use_ms10 == -1) {
+                err = set_mode_select(sdev);
+                if (err != SCSI_DH_OK)
+                        goto done;
+        }
+
+        err = send_mode_select(sdev);
+done:
+        return err;
+}
+
+static int rdac_prep_fn(struct scsi_device *sdev, struct request *req)
+{
+        struct rdac_dh_data *h = get_rdac_data(sdev);
+        int ret = BLKPREP_OK;
+
+        if (h->state != RDAC_STATE_ACTIVE) {
+                ret = BLKPREP_KILL;
+                req->cmd_flags |= REQ_QUIET;
+        }
+        return ret;
+
+}
+
+static int rdac_check_sense(struct scsi_device *sdev,
+                                struct scsi_sense_hdr *sense_hdr)
+{
+        struct rdac_dh_data *h = get_rdac_data(sdev);
+        switch (sense_hdr->sense_key) {
+        case NOT_READY:
+                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 NEEDS_RETRY;
+                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 NEEDS_RETRY;
+                break;
+        }
+        /* success just means we do not care what scsi-ml does */
+        return SCSI_RETURN_NOT_HANDLED;
+}
+
+static const struct {
+        char *vendor;
+        char *model;
+} rdac_dev_list[] = {
+        {"IBM", "1722"},
+        {"IBM", "1724"},
+        {"IBM", "1726"},
+        {"IBM", "1742"},
+        {"IBM", "1814"},
+        {"IBM", "1815"},
+        {"IBM", "1818"},
+        {"IBM", "3526"},
+        {"SGI", "TP9400"},
+        {"SGI", "TP9500"},
+        {"SGI", "IS"},
+        {"STK", "OPENstorage D280"},
+        {"SUN", "CSM200_R"},
+        {"SUN", "LCSM100_F"},
+        {NULL, NULL},
+};
+
+static int rdac_bus_notify(struct notifier_block *, unsigned long, void *);
+
+static struct scsi_device_handler rdac_dh = {
+        .name = RDAC_NAME,
+        .module = THIS_MODULE,
+        .nb.notifier_call = rdac_bus_notify,
+        .prep_fn = rdac_prep_fn,
+        .check_sense = rdac_check_sense,
+        .activate = rdac_activate,
+};
+
+/*
+ * TODO: need some interface so we can set trespass values
+ */
+static int rdac_bus_notify(struct notifier_block *nb,
+                            unsigned long action, void *data)
+{
+        struct device *dev = data;
+        struct scsi_device *sdev = to_scsi_device(dev);
+        struct scsi_dh_data *scsi_dh_data;
+        struct rdac_dh_data *h;
+        int i, found = 0;
+        unsigned long flags;
+
+        if (action == BUS_NOTIFY_ADD_DEVICE) {
+                for (i = 0; rdac_dev_list[i].vendor; i++) {
+                        if (!strncmp(sdev->vendor, rdac_dev_list[i].vendor,
+                                     strlen(rdac_dev_list[i].vendor)) &&
+                            !strncmp(sdev->model, rdac_dev_list[i].model,
+                                     strlen(rdac_dev_list[i].model))) {
+                                found = 1;
+                                break;
+                        }
+                }
+                if (!found)
+                        goto out;
+
+                scsi_dh_data = kzalloc(sizeof(struct scsi_device_handler *)
+                                + sizeof(*h) , GFP_KERNEL);
+                if (!scsi_dh_data) {
+                        sdev_printk(KERN_ERR, sdev, "Attach failed %s.\n",
+                                    RDAC_NAME);
+                        goto out;
+                }
+
+                scsi_dh_data->scsi_dh = &rdac_dh;
+                h = (struct rdac_dh_data *) scsi_dh_data->buf;
+                h->lun = UNINITIALIZED_LUN;
+                h->state = RDAC_STATE_ACTIVE;
+                spin_lock_irqsave(sdev->request_queue->queue_lock, flags);
+                sdev->scsi_dh_data = scsi_dh_data;
+                spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
+                try_module_get(THIS_MODULE);
+
+                sdev_printk(KERN_NOTICE, sdev, "Attached %s.\n", RDAC_NAME);
+
+        } else if (action == BUS_NOTIFY_DEL_DEVICE) {
+                if (sdev->scsi_dh_data == NULL ||
+                                sdev->scsi_dh_data->scsi_dh != &rdac_dh)
+                        goto out;
+
+                spin_lock_irqsave(sdev->request_queue->queue_lock, flags);
+                scsi_dh_data = sdev->scsi_dh_data;
+                sdev->scsi_dh_data = NULL;
+                spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
+
+                h = (struct rdac_dh_data *) scsi_dh_data->buf;
+                if (h->ctlr)
+                        kref_put(&h->ctlr->kref, release_controller);
+                kfree(scsi_dh_data);
+                module_put(THIS_MODULE);
+                sdev_printk(KERN_NOTICE, sdev, "Dettached %s.\n", RDAC_NAME);
+        }
+
+out:
+        return 0;
+}
+
+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.");
+        return r;
+}
+
+static void __exit rdac_exit(void)
+{
+        scsi_unregister_device_handler(&rdac_dh);
+}
+
+module_init(rdac_init);
+module_exit(rdac_exit);
+
+MODULE_DESCRIPTION("Multipath LSI/Engenio RDAC driver");
+MODULE_AUTHOR("Mike Christie, Chandra Seetharaman");
+MODULE_LICENSE("GPL");