]> err.no Git - linux-2.6/commitdiff
[SCSI] scsi_dh: add lsi rdac device handler
authorChandra Seetharaman <sekharan@us.ibm.com>
Thu, 1 May 2008 21:49:52 +0000 (14:49 -0700)
committerJames Bottomley <James.Bottomley@HansenPartnership.com>
Thu, 5 Jun 2008 14:23:40 +0000 (09:23 -0500)
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>
drivers/scsi/device_handler/Kconfig
drivers/scsi/device_handler/Makefile
drivers/scsi/device_handler/scsi_dh_rdac.c [new file with mode: 0644]

index 228241d1d98c808ae01bb723cbd9c8d33e630a52..404f37732627c2c87d23c294fd9a545271cdefcc 100644 (file)
@@ -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.
index f306e44e3837a8abc7860523cb0db02a48f727ca..1a42b34983185e1030d2e9a6ad89886adf6da1d2 100644 (file)
@@ -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 (file)
index 0000000..6fff077
--- /dev/null
@@ -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");