[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");