Commit dd172d72 authored by Chandra Seetharaman's avatar Chandra Seetharaman Committed by Linus Torvalds
Browse files

dm mpath: rdac 



This patch supports LSI/Engenio devices in RDAC mode. Like dm-emc
it requires userspace support. In your multipath.conf file you must have:

path_checker            rdac
hardware_handler        "1 rdac"
prio_callout		"/sbin/mpath_prio_tpc /dev/%n"

And you also then must have a updated multipath tools release which
has rdac support.

Signed-off-by: default avatarChandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: default avatarMike Christie <michaelc@cs.wisc.edu>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent fc1ff958

drivers/md/Kconfig

+6 −0
Original line number Diff line number Diff line
@@ -262,6 +262,12 @@ config DM_MULTIPATH_EMC 
	---help---

	  Multipath support for EMC CX/AX series hardware.



config DM_MULTIPATH_RDAC

	tristate "LSI/Engenio RDAC multipath support (EXPERIMENTAL)"

	depends on DM_MULTIPATH && BLK_DEV_DM && EXPERIMENTAL

	---help---

	  Multipath support for LSI/Engenio RDAC.



config DM_DELAY

	tristate "I/O delaying target (EXPERIMENTAL)"

	depends on BLK_DEV_DM && EXPERIMENTAL

drivers/md/Makefile

+2 −0
Original line number Diff line number Diff line
@@ -7,6 +7,7 @@ dm-mod-objs := dm.o dm-table.o dm-target.o dm-linear.o dm-stripe.o \ 
dm-multipath-objs := dm-hw-handler.o dm-path-selector.o dm-mpath.o

dm-snapshot-objs := dm-snap.o dm-exception-store.o

dm-mirror-objs	:= dm-log.o dm-raid1.o

dm-rdac-objs	:= dm-mpath-rdac.o

md-mod-objs     := md.o bitmap.o

raid456-objs	:= raid5.o raid6algos.o raid6recov.o raid6tables.o \

		   raid6int1.o raid6int2.o raid6int4.o \
@@ -34,6 +35,7 @@ obj-$(CONFIG_DM_CRYPT) += dm-crypt.o 
obj-$(CONFIG_DM_DELAY)		+= dm-delay.o

obj-$(CONFIG_DM_MULTIPATH)	+= dm-multipath.o dm-round-robin.o

obj-$(CONFIG_DM_MULTIPATH_EMC)	+= dm-emc.o

obj-$(CONFIG_DM_MULTIPATH_RDAC)	+= dm-rdac.o

obj-$(CONFIG_DM_SNAPSHOT)	+= dm-snapshot.o

obj-$(CONFIG_DM_MIRROR)		+= dm-mirror.o

obj-$(CONFIG_DM_ZERO)		+= dm-zero.o

drivers/md/dm-mpath-rdac.c

0 → 100644
+700 −0
Original line number Diff line number Diff line 
/*

 * Engenio/LSI RDAC DM HW 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_cmnd.h>

#include <scsi/scsi_eh.h>



#define DM_MSG_PREFIX "multipath rdac"



#include "dm.h"

#include "dm-hw-handler.h"



#define RDAC_DM_HWH_NAME "rdac"

#define RDAC_DM_HWH_VER "0.4"



/*

 * 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_ALL_LUNS		0x01

#define RDAC_MODE_TRANSFER_SPECIFIED_LUNS	0x02



/*

 * RDAC Options field

 */

#define RDAC_FORCED_QUIESENCE 0x02



#define RDAC_FAILOVER_TIMEOUT (60 * HZ)



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_10_ms;

	struct kref		kref;

	struct list_head	node; /* list of all controllers */

	spinlock_t		lock;

	int			submitted;

	struct list_head	cmd_list; /* list of commands to be submitted */

	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_handler {

	struct list_head	entry; /* list waiting to submit MODE SELECT */

	unsigned		timeout;

	struct rdac_controller	*ctlr;

#define UNINITIALIZED_LUN	(1 << 8)

	unsigned		lun;

	unsigned char		sense[SCSI_SENSE_BUFFERSIZE];

	struct dm_path		*path;

	struct work_struct	work;

#define	SEND_C2_INQUIRY		1

#define	SEND_C4_INQUIRY		2

#define	SEND_C8_INQUIRY		3

#define	SEND_C9_INQUIRY		4

#define	SEND_MODE_SELECT	5

	int			cmd_to_send;

	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 struct workqueue_struct *rdac_wkqd;



static inline int had_failures(struct request *req, int error)

{

	return (error || host_byte(req->errors) != DID_OK ||

			msg_byte(req->errors) != COMMAND_COMPLETE);

}



static void rdac_resubmit_all(struct rdac_handler *h)

{

	struct rdac_controller *ctlr = h->ctlr;

	struct rdac_handler *tmp, *h1;



	spin_lock(&ctlr->lock);

	list_for_each_entry_safe(h1, tmp, &ctlr->cmd_list, entry) {

		h1->cmd_to_send = SEND_C9_INQUIRY;

		queue_work(rdac_wkqd, &h1->work);

		list_del(&h1->entry);

	}

	ctlr->submitted = 0;

	spin_unlock(&ctlr->lock);

}



static void mode_select_endio(struct request *req, int error)

{

	struct rdac_handler *h = req->end_io_data;

	struct scsi_sense_hdr sense_hdr;

	int sense = 0, fail = 0;



	if (had_failures(req, error)) {

		fail = 1;

		goto failed;

	}



	if (status_byte(req->errors) == CHECK_CONDITION) {

		scsi_normalize_sense(req->sense, SCSI_SENSE_BUFFERSIZE,

				&sense_hdr);

		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

			 */

			h->cmd_to_send = SEND_C9_INQUIRY;

			queue_work(rdac_wkqd, &h->work);

			goto done;

		}

		if (sense)

			DMINFO("MODE_SELECT failed on %s with sense 0x%x",

						h->path->dev->name, sense);

 	}

failed:

	if (fail || sense)

		dm_pg_init_complete(h->path, MP_FAIL_PATH);

	else

		dm_pg_init_complete(h->path, 0);



done:

	rdac_resubmit_all(h);

	__blk_put_request(req->q, req);

}



static struct request *get_rdac_req(struct rdac_handler *h,

			void *buffer, unsigned buflen, int rw)

{

	struct request *rq;

	struct request_queue *q = bdev_get_queue(h->path->dev->bdev);



	rq = blk_get_request(q, rw, GFP_KERNEL);



	if (!rq) {

		DMINFO("get_rdac_req: blk_get_request failed");

		return NULL;

	}



	if (buflen && blk_rq_map_kern(q, rq, buffer, buflen, GFP_KERNEL)) {

		blk_put_request(rq);

		DMINFO("get_rdac_req: blk_rq_map_kern failed");

		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->end_io_data = h;

	rq->timeout = h->timeout;

	rq->cmd_type = REQ_TYPE_BLOCK_PC;

	rq->cmd_flags = REQ_FAILFAST | REQ_NOMERGE;

	return rq;

}



static struct request *rdac_failover_get(struct rdac_handler *h)

{

	struct request *rq;

	struct rdac_mode_common *common;

	unsigned data_size;



	if (h->ctlr->use_10_ms) {

		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(h, &h->ctlr->mode_select, data_size, WRITE);

	if (!rq) {

		DMERR("rdac_failover_get: no rq");

		return NULL;

	}



	/* Prepare the command. */

	if (h->ctlr->use_10_ms) {

		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;

}



/* Acquires h->ctlr->lock */

static void submit_mode_select(struct rdac_handler *h)

{

	struct request *rq;

	struct request_queue *q = bdev_get_queue(h->path->dev->bdev);



	spin_lock(&h->ctlr->lock);

	if (h->ctlr->submitted) {

		list_add(&h->entry, &h->ctlr->cmd_list);

		goto drop_lock;

	}



	if (!q) {

		DMINFO("submit_mode_select: no queue");

		goto fail_path;

	}



	rq = rdac_failover_get(h);

	if (!rq) {

		DMERR("submit_mode_select: no rq");

		goto fail_path;

	}



	DMINFO("queueing MODE_SELECT command on %s", h->path->dev->name);



	blk_execute_rq_nowait(q, NULL, rq, 1, mode_select_endio);

	h->ctlr->submitted = 1;

	goto drop_lock;

fail_path:

	dm_pg_init_complete(h->path, MP_FAIL_PATH);

drop_lock:

	spin_unlock(&h->ctlr->lock);

}



static void release_ctlr(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);

	spin_lock_init(&ctlr->lock);

	ctlr->submitted = 0;

	ctlr->use_10_ms = -1;

	INIT_LIST_HEAD(&ctlr->cmd_list);

	list_add(&ctlr->node, &ctlr_list);

done:

	spin_unlock(&list_lock);

	return ctlr;

}



static void c4_endio(struct request *req, int error)

{

	struct rdac_handler *h = req->end_io_data;

	struct c4_inquiry *sp;



	if (had_failures(req, error)) {

		dm_pg_init_complete(h->path, MP_FAIL_PATH);

		goto done;

	}



	sp = &h->inq.c4;



	h->ctlr = get_controller(sp->subsys_id, sp->slot_id);



	if (h->ctlr) {

		h->cmd_to_send = SEND_C9_INQUIRY;

		queue_work(rdac_wkqd, &h->work);

	} else

		dm_pg_init_complete(h->path, MP_FAIL_PATH);

done:

	__blk_put_request(req->q, req);

}



static void c2_endio(struct request *req, int error)

{

	struct rdac_handler *h = req->end_io_data;

	struct c2_inquiry *sp;



	if (had_failures(req, error)) {

		dm_pg_init_complete(h->path, MP_FAIL_PATH);

		goto done;

	}



	sp = &h->inq.c2;



	/* If more than MODE6_MAX_LUN luns are supported, use mode select 10 */

	if (sp->max_lun_supported >= MODE6_MAX_LUN)

		h->ctlr->use_10_ms = 1;

	else

		h->ctlr->use_10_ms = 0;



	h->cmd_to_send = SEND_MODE_SELECT;

	queue_work(rdac_wkqd, &h->work);

done:

	__blk_put_request(req->q, req);

}



static void c9_endio(struct request *req, int error)

{

	struct rdac_handler *h = req->end_io_data;

	struct c9_inquiry *sp;



	if (had_failures(req, error)) {

		dm_pg_init_complete(h->path, MP_FAIL_PATH);

		goto done;

	}



	/* We need to look at the sense keys here to take clear action.

	 * For now simple logic: If the host is in AVT mode or if controller

	 * owns the lun, return dm_pg_init_complete(), otherwise submit

	 * MODE SELECT.

	 */

	sp = &h->inq.c9;



	/* If in AVT mode, return success */

	if ((sp->avte_cvp >> 7) == 0x1) {

		dm_pg_init_complete(h->path, 0);

		goto done;

	}



	/* If the controller on this path owns the LUN, return success */

	if (sp->avte_cvp & 0x1) {

		dm_pg_init_complete(h->path, 0);

		goto done;

	}



	if (h->ctlr) {

		if (h->ctlr->use_10_ms == -1)

			h->cmd_to_send = SEND_C2_INQUIRY;

		else

			h->cmd_to_send = SEND_MODE_SELECT;

	} else

		h->cmd_to_send = SEND_C4_INQUIRY;

	queue_work(rdac_wkqd, &h->work);

done:

	__blk_put_request(req->q, req);

}



static void c8_endio(struct request *req, int error)

{

	struct rdac_handler *h = req->end_io_data;

	struct c8_inquiry *sp;



	if (had_failures(req, error)) {

		dm_pg_init_complete(h->path, MP_FAIL_PATH);

		goto done;

	}



	/* We need to look at the sense keys here to take clear action.

	 * For now simple logic: Get the lun from the inquiry page.

	 */

	sp = &h->inq.c8;

	h->lun = sp->lun[7]; /* currently it uses only one byte */

	h->cmd_to_send = SEND_C9_INQUIRY;

	queue_work(rdac_wkqd, &h->work);

done:

	__blk_put_request(req->q, req);

}



static void submit_inquiry(struct rdac_handler *h, int page_code,

		unsigned int len, rq_end_io_fn endio)

{

	struct request *rq;

	struct request_queue *q = bdev_get_queue(h->path->dev->bdev);



	if (!q)

		goto fail_path;



	rq = get_rdac_req(h, &h->inq, len, READ);

	if (!rq)

		goto fail_path;



	/* 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);

	blk_execute_rq_nowait(q, NULL, rq, 1, endio);

	return;



fail_path:

	dm_pg_init_complete(h->path, MP_FAIL_PATH);

}



static void service_wkq(struct work_struct *work)

{

	struct rdac_handler *h = container_of(work, struct rdac_handler, work);



	switch (h->cmd_to_send) {

	case SEND_C2_INQUIRY:

		submit_inquiry(h, 0xC2, sizeof(struct c2_inquiry), c2_endio);

		break;

	case SEND_C4_INQUIRY:

		submit_inquiry(h, 0xC4, sizeof(struct c4_inquiry), c4_endio);

		break;

	case SEND_C8_INQUIRY:

		submit_inquiry(h, 0xC8, sizeof(struct c8_inquiry), c8_endio);

		break;

	case SEND_C9_INQUIRY:

		submit_inquiry(h, 0xC9, sizeof(struct c9_inquiry), c9_endio);

		break;

	case SEND_MODE_SELECT:

		submit_mode_select(h);

		break;

	default:

		BUG();

	}

}

/*

 * only support subpage2c until we confirm that this is just a matter of

 * of updating firmware or not, and RDAC (basic AVT works already) for now

 * but we can add these in in when we get time and testers

 */

static int rdac_create(struct hw_handler *hwh, unsigned argc, char **argv)

{

	struct rdac_handler *h;

	unsigned timeout;



	if (argc == 0) {

		/* No arguments: use defaults */

		timeout = RDAC_FAILOVER_TIMEOUT;

	} else if (argc != 1) {

		DMWARN("incorrect number of arguments");

		return -EINVAL;

	} else {

		if (sscanf(argv[1], "%u", &timeout) != 1) {

			DMWARN("invalid timeout value");

			return -EINVAL;

		}

	}



	h = kzalloc(sizeof(*h), GFP_KERNEL);

	if (!h)

		return -ENOMEM;



	hwh->context = h;

	h->timeout = timeout;

	h->lun = UNINITIALIZED_LUN;

	INIT_WORK(&h->work, service_wkq);

	DMWARN("using RDAC command with timeout %u", h->timeout);



	return 0;

}



static void rdac_destroy(struct hw_handler *hwh)

{

	struct rdac_handler *h = hwh->context;



	if (h->ctlr)

		kref_put(&h->ctlr->kref, release_ctlr);

	kfree(h);

	hwh->context = NULL;

}



static unsigned rdac_error(struct hw_handler *hwh, struct bio *bio)

{

	/* Try default handler */

	return dm_scsi_err_handler(hwh, bio);

}



static void rdac_pg_init(struct hw_handler *hwh, unsigned bypassed,

			struct dm_path *path)

{

	struct rdac_handler *h = hwh->context;



	h->path = path;

	switch (h->lun) {

	case UNINITIALIZED_LUN:

		submit_inquiry(h, 0xC8, sizeof(struct c8_inquiry), c8_endio);

		break;

	default:

		submit_inquiry(h, 0xC9, sizeof(struct c9_inquiry), c9_endio);

	}

}



static struct hw_handler_type rdac_handler = {

	.name = RDAC_DM_HWH_NAME,

	.module = THIS_MODULE,

	.create = rdac_create,

	.destroy = rdac_destroy,

	.pg_init = rdac_pg_init,

	.error = rdac_error,

};



static int __init rdac_init(void)

{

	int r = dm_register_hw_handler(&rdac_handler);



	if (r < 0) {

		DMERR("%s: register failed %d", RDAC_DM_HWH_NAME, r);

		return r;

	}



	rdac_wkqd = create_singlethread_workqueue("rdac_wkqd");

	if (!rdac_wkqd) {

		DMERR("Failed to create workqueue rdac_wkqd.");

		dm_unregister_hw_handler(&rdac_handler);

		return -ENOMEM;

	}



	DMINFO("%s: version %s loaded", RDAC_DM_HWH_NAME, RDAC_DM_HWH_VER);

	return 0;

}



static void __exit rdac_exit(void)

{

	int r = dm_unregister_hw_handler(&rdac_handler);



	destroy_workqueue(rdac_wkqd);

	if (r < 0)

		DMERR("%s: unregister failed %d", RDAC_DM_HWH_NAME, r);

}



module_init(rdac_init);

module_exit(rdac_exit);



MODULE_DESCRIPTION("DM Multipath LSI/Engenio RDAC support");

MODULE_AUTHOR("Mike Christie, Chandra Seetharaman");

MODULE_LICENSE("GPL");

MODULE_VERSION(RDAC_DM_HWH_VER);

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