xref: /linux/drivers/scsi/device_handler/scsi_dh_rdac.c (revision b233b28eac0cc37d07c2d007ea08c86c778c5af4)
1 /*
2  * Engenio/LSI RDAC SCSI Device Handler
3  *
4  * Copyright (C) 2005 Mike Christie. All rights reserved.
5  * Copyright (C) Chandra Seetharaman, IBM Corp. 2007
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License as published by
9  * the Free Software Foundation; either version 2 of the License, or
10  * (at your option) any later version.
11  *
12  * This program is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15  * GNU General Public License for more details.
16  *
17  * You should have received a copy of the GNU General Public License
18  * along with this program; if not, write to the Free Software
19  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
20  *
21  */
22 #include <scsi/scsi.h>
23 #include <scsi/scsi_eh.h>
24 #include <scsi/scsi_dh.h>
25 
26 #define RDAC_NAME "rdac"
27 #define RDAC_RETRY_COUNT 5
28 
29 /*
30  * LSI mode page stuff
31  *
32  * These struct definitions and the forming of the
33  * mode page were taken from the LSI RDAC 2.4 GPL'd
34  * driver, and then converted to Linux conventions.
35  */
36 #define RDAC_QUIESCENCE_TIME 20;
37 /*
38  * Page Codes
39  */
40 #define RDAC_PAGE_CODE_REDUNDANT_CONTROLLER 0x2c
41 
42 /*
43  * Controller modes definitions
44  */
45 #define RDAC_MODE_TRANSFER_SPECIFIED_LUNS	0x02
46 
47 /*
48  * RDAC Options field
49  */
50 #define RDAC_FORCED_QUIESENCE 0x02
51 
52 #define RDAC_TIMEOUT	(60 * HZ)
53 #define RDAC_RETRIES	3
54 
55 struct rdac_mode_6_hdr {
56 	u8	data_len;
57 	u8	medium_type;
58 	u8	device_params;
59 	u8	block_desc_len;
60 };
61 
62 struct rdac_mode_10_hdr {
63 	u16	data_len;
64 	u8	medium_type;
65 	u8	device_params;
66 	u16	reserved;
67 	u16	block_desc_len;
68 };
69 
70 struct rdac_mode_common {
71 	u8	controller_serial[16];
72 	u8	alt_controller_serial[16];
73 	u8	rdac_mode[2];
74 	u8	alt_rdac_mode[2];
75 	u8	quiescence_timeout;
76 	u8	rdac_options;
77 };
78 
79 struct rdac_pg_legacy {
80 	struct rdac_mode_6_hdr hdr;
81 	u8	page_code;
82 	u8	page_len;
83 	struct rdac_mode_common common;
84 #define MODE6_MAX_LUN	32
85 	u8	lun_table[MODE6_MAX_LUN];
86 	u8	reserved2[32];
87 	u8	reserved3;
88 	u8	reserved4;
89 };
90 
91 struct rdac_pg_expanded {
92 	struct rdac_mode_10_hdr hdr;
93 	u8	page_code;
94 	u8	subpage_code;
95 	u8	page_len[2];
96 	struct rdac_mode_common common;
97 	u8	lun_table[256];
98 	u8	reserved3;
99 	u8	reserved4;
100 };
101 
102 struct c9_inquiry {
103 	u8	peripheral_info;
104 	u8	page_code;	/* 0xC9 */
105 	u8	reserved1;
106 	u8	page_len;
107 	u8	page_id[4];	/* "vace" */
108 	u8	avte_cvp;
109 	u8	path_prio;
110 	u8	reserved2[38];
111 };
112 
113 #define SUBSYS_ID_LEN	16
114 #define SLOT_ID_LEN	2
115 
116 struct c4_inquiry {
117 	u8	peripheral_info;
118 	u8	page_code;	/* 0xC4 */
119 	u8	reserved1;
120 	u8	page_len;
121 	u8	page_id[4];	/* "subs" */
122 	u8	subsys_id[SUBSYS_ID_LEN];
123 	u8	revision[4];
124 	u8	slot_id[SLOT_ID_LEN];
125 	u8	reserved[2];
126 };
127 
128 struct rdac_controller {
129 	u8			subsys_id[SUBSYS_ID_LEN];
130 	u8			slot_id[SLOT_ID_LEN];
131 	int			use_ms10;
132 	struct kref		kref;
133 	struct list_head	node; /* list of all controllers */
134 	union			{
135 		struct rdac_pg_legacy legacy;
136 		struct rdac_pg_expanded expanded;
137 	} mode_select;
138 };
139 struct c8_inquiry {
140 	u8	peripheral_info;
141 	u8	page_code; /* 0xC8 */
142 	u8	reserved1;
143 	u8	page_len;
144 	u8	page_id[4]; /* "edid" */
145 	u8	reserved2[3];
146 	u8	vol_uniq_id_len;
147 	u8	vol_uniq_id[16];
148 	u8	vol_user_label_len;
149 	u8	vol_user_label[60];
150 	u8	array_uniq_id_len;
151 	u8	array_unique_id[16];
152 	u8	array_user_label_len;
153 	u8	array_user_label[60];
154 	u8	lun[8];
155 };
156 
157 struct c2_inquiry {
158 	u8	peripheral_info;
159 	u8	page_code;	/* 0xC2 */
160 	u8	reserved1;
161 	u8	page_len;
162 	u8	page_id[4];	/* "swr4" */
163 	u8	sw_version[3];
164 	u8	sw_date[3];
165 	u8	features_enabled;
166 	u8	max_lun_supported;
167 	u8	partitions[239]; /* Total allocation length should be 0xFF */
168 };
169 
170 struct rdac_dh_data {
171 	struct rdac_controller	*ctlr;
172 #define UNINITIALIZED_LUN	(1 << 8)
173 	unsigned		lun;
174 #define RDAC_STATE_ACTIVE	0
175 #define RDAC_STATE_PASSIVE	1
176 	unsigned char		state;
177 
178 #define RDAC_LUN_UNOWNED	0
179 #define RDAC_LUN_OWNED		1
180 #define RDAC_LUN_AVT		2
181 	char			lun_state;
182 	unsigned char		sense[SCSI_SENSE_BUFFERSIZE];
183 	union			{
184 		struct c2_inquiry c2;
185 		struct c4_inquiry c4;
186 		struct c8_inquiry c8;
187 		struct c9_inquiry c9;
188 	} inq;
189 };
190 
191 static const char *lun_state[] =
192 {
193 	"unowned",
194 	"owned",
195 	"owned (AVT mode)",
196 };
197 
198 static LIST_HEAD(ctlr_list);
199 static DEFINE_SPINLOCK(list_lock);
200 
201 static inline struct rdac_dh_data *get_rdac_data(struct scsi_device *sdev)
202 {
203 	struct scsi_dh_data *scsi_dh_data = sdev->scsi_dh_data;
204 	BUG_ON(scsi_dh_data == NULL);
205 	return ((struct rdac_dh_data *) scsi_dh_data->buf);
206 }
207 
208 static struct request *get_rdac_req(struct scsi_device *sdev,
209 			void *buffer, unsigned buflen, int rw)
210 {
211 	struct request *rq;
212 	struct request_queue *q = sdev->request_queue;
213 
214 	rq = blk_get_request(q, rw, GFP_NOIO);
215 
216 	if (!rq) {
217 		sdev_printk(KERN_INFO, sdev,
218 				"get_rdac_req: blk_get_request failed.\n");
219 		return NULL;
220 	}
221 
222 	if (buflen && blk_rq_map_kern(q, rq, buffer, buflen, GFP_NOIO)) {
223 		blk_put_request(rq);
224 		sdev_printk(KERN_INFO, sdev,
225 				"get_rdac_req: blk_rq_map_kern failed.\n");
226 		return NULL;
227 	}
228 
229 	rq->cmd_type = REQ_TYPE_BLOCK_PC;
230 	rq->cmd_flags |= REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
231 			 REQ_FAILFAST_DRIVER;
232 	rq->retries = RDAC_RETRIES;
233 	rq->timeout = RDAC_TIMEOUT;
234 
235 	return rq;
236 }
237 
238 static struct request *rdac_failover_get(struct scsi_device *sdev,
239 					 struct rdac_dh_data *h)
240 {
241 	struct request *rq;
242 	struct rdac_mode_common *common;
243 	unsigned data_size;
244 
245 	if (h->ctlr->use_ms10) {
246 		struct rdac_pg_expanded *rdac_pg;
247 
248 		data_size = sizeof(struct rdac_pg_expanded);
249 		rdac_pg = &h->ctlr->mode_select.expanded;
250 		memset(rdac_pg, 0, data_size);
251 		common = &rdac_pg->common;
252 		rdac_pg->page_code = RDAC_PAGE_CODE_REDUNDANT_CONTROLLER + 0x40;
253 		rdac_pg->subpage_code = 0x1;
254 		rdac_pg->page_len[0] = 0x01;
255 		rdac_pg->page_len[1] = 0x28;
256 		rdac_pg->lun_table[h->lun] = 0x81;
257 	} else {
258 		struct rdac_pg_legacy *rdac_pg;
259 
260 		data_size = sizeof(struct rdac_pg_legacy);
261 		rdac_pg = &h->ctlr->mode_select.legacy;
262 		memset(rdac_pg, 0, data_size);
263 		common = &rdac_pg->common;
264 		rdac_pg->page_code = RDAC_PAGE_CODE_REDUNDANT_CONTROLLER;
265 		rdac_pg->page_len = 0x68;
266 		rdac_pg->lun_table[h->lun] = 0x81;
267 	}
268 	common->rdac_mode[1] = RDAC_MODE_TRANSFER_SPECIFIED_LUNS;
269 	common->quiescence_timeout = RDAC_QUIESCENCE_TIME;
270 	common->rdac_options = RDAC_FORCED_QUIESENCE;
271 
272 	/* get request for block layer packet command */
273 	rq = get_rdac_req(sdev, &h->ctlr->mode_select, data_size, WRITE);
274 	if (!rq)
275 		return NULL;
276 
277 	/* Prepare the command. */
278 	if (h->ctlr->use_ms10) {
279 		rq->cmd[0] = MODE_SELECT_10;
280 		rq->cmd[7] = data_size >> 8;
281 		rq->cmd[8] = data_size & 0xff;
282 	} else {
283 		rq->cmd[0] = MODE_SELECT;
284 		rq->cmd[4] = data_size;
285 	}
286 	rq->cmd_len = COMMAND_SIZE(rq->cmd[0]);
287 
288 	rq->sense = h->sense;
289 	memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
290 	rq->sense_len = 0;
291 
292 	return rq;
293 }
294 
295 static void release_controller(struct kref *kref)
296 {
297 	struct rdac_controller *ctlr;
298 	ctlr = container_of(kref, struct rdac_controller, kref);
299 
300 	spin_lock(&list_lock);
301 	list_del(&ctlr->node);
302 	spin_unlock(&list_lock);
303 	kfree(ctlr);
304 }
305 
306 static struct rdac_controller *get_controller(u8 *subsys_id, u8 *slot_id)
307 {
308 	struct rdac_controller *ctlr, *tmp;
309 
310 	spin_lock(&list_lock);
311 
312 	list_for_each_entry(tmp, &ctlr_list, node) {
313 		if ((memcmp(tmp->subsys_id, subsys_id, SUBSYS_ID_LEN) == 0) &&
314 			  (memcmp(tmp->slot_id, slot_id, SLOT_ID_LEN) == 0)) {
315 			kref_get(&tmp->kref);
316 			spin_unlock(&list_lock);
317 			return tmp;
318 		}
319 	}
320 	ctlr = kmalloc(sizeof(*ctlr), GFP_ATOMIC);
321 	if (!ctlr)
322 		goto done;
323 
324 	/* initialize fields of controller */
325 	memcpy(ctlr->subsys_id, subsys_id, SUBSYS_ID_LEN);
326 	memcpy(ctlr->slot_id, slot_id, SLOT_ID_LEN);
327 	kref_init(&ctlr->kref);
328 	ctlr->use_ms10 = -1;
329 	list_add(&ctlr->node, &ctlr_list);
330 done:
331 	spin_unlock(&list_lock);
332 	return ctlr;
333 }
334 
335 static int submit_inquiry(struct scsi_device *sdev, int page_code,
336 			  unsigned int len, struct rdac_dh_data *h)
337 {
338 	struct request *rq;
339 	struct request_queue *q = sdev->request_queue;
340 	int err = SCSI_DH_RES_TEMP_UNAVAIL;
341 
342 	rq = get_rdac_req(sdev, &h->inq, len, READ);
343 	if (!rq)
344 		goto done;
345 
346 	/* Prepare the command. */
347 	rq->cmd[0] = INQUIRY;
348 	rq->cmd[1] = 1;
349 	rq->cmd[2] = page_code;
350 	rq->cmd[4] = len;
351 	rq->cmd_len = COMMAND_SIZE(INQUIRY);
352 
353 	rq->sense = h->sense;
354 	memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
355 	rq->sense_len = 0;
356 
357 	err = blk_execute_rq(q, NULL, rq, 1);
358 	if (err == -EIO)
359 		err = SCSI_DH_IO;
360 
361 	blk_put_request(rq);
362 done:
363 	return err;
364 }
365 
366 static int get_lun(struct scsi_device *sdev, struct rdac_dh_data *h)
367 {
368 	int err;
369 	struct c8_inquiry *inqp;
370 
371 	err = submit_inquiry(sdev, 0xC8, sizeof(struct c8_inquiry), h);
372 	if (err == SCSI_DH_OK) {
373 		inqp = &h->inq.c8;
374 		if (inqp->page_code != 0xc8)
375 			return SCSI_DH_NOSYS;
376 		if (inqp->page_id[0] != 'e' || inqp->page_id[1] != 'd' ||
377 		    inqp->page_id[2] != 'i' || inqp->page_id[3] != 'd')
378 			return SCSI_DH_NOSYS;
379 		h->lun = inqp->lun[7]; /* Uses only the last byte */
380 	}
381 	return err;
382 }
383 
384 static int check_ownership(struct scsi_device *sdev, struct rdac_dh_data *h)
385 {
386 	int err;
387 	struct c9_inquiry *inqp;
388 
389 	h->lun_state = RDAC_LUN_UNOWNED;
390 	h->state = RDAC_STATE_ACTIVE;
391 	err = submit_inquiry(sdev, 0xC9, sizeof(struct c9_inquiry), h);
392 	if (err == SCSI_DH_OK) {
393 		inqp = &h->inq.c9;
394 		if ((inqp->avte_cvp >> 7) == 0x1) {
395 			/* LUN in AVT mode */
396 			sdev_printk(KERN_NOTICE, sdev,
397 				    "%s: AVT mode detected\n",
398 				    RDAC_NAME);
399 			h->lun_state = RDAC_LUN_AVT;
400 		} else if ((inqp->avte_cvp & 0x1) != 0) {
401 			/* LUN was owned by the controller */
402 			h->lun_state = RDAC_LUN_OWNED;
403 		}
404 	}
405 
406 	if (h->lun_state == RDAC_LUN_UNOWNED)
407 		h->state = RDAC_STATE_PASSIVE;
408 
409 	return err;
410 }
411 
412 static int initialize_controller(struct scsi_device *sdev,
413 				 struct rdac_dh_data *h)
414 {
415 	int err;
416 	struct c4_inquiry *inqp;
417 
418 	err = submit_inquiry(sdev, 0xC4, sizeof(struct c4_inquiry), h);
419 	if (err == SCSI_DH_OK) {
420 		inqp = &h->inq.c4;
421 		h->ctlr = get_controller(inqp->subsys_id, inqp->slot_id);
422 		if (!h->ctlr)
423 			err = SCSI_DH_RES_TEMP_UNAVAIL;
424 	}
425 	return err;
426 }
427 
428 static int set_mode_select(struct scsi_device *sdev, struct rdac_dh_data *h)
429 {
430 	int err;
431 	struct c2_inquiry *inqp;
432 
433 	err = submit_inquiry(sdev, 0xC2, sizeof(struct c2_inquiry), h);
434 	if (err == SCSI_DH_OK) {
435 		inqp = &h->inq.c2;
436 		/*
437 		 * If more than MODE6_MAX_LUN luns are supported, use
438 		 * mode select 10
439 		 */
440 		if (inqp->max_lun_supported >= MODE6_MAX_LUN)
441 			h->ctlr->use_ms10 = 1;
442 		else
443 			h->ctlr->use_ms10 = 0;
444 	}
445 	return err;
446 }
447 
448 static int mode_select_handle_sense(struct scsi_device *sdev,
449 				    unsigned char *sensebuf)
450 {
451 	struct scsi_sense_hdr sense_hdr;
452 	int sense, err = SCSI_DH_IO, ret;
453 
454 	ret = scsi_normalize_sense(sensebuf, SCSI_SENSE_BUFFERSIZE, &sense_hdr);
455 	if (!ret)
456 		goto done;
457 
458 	err = SCSI_DH_OK;
459 	sense = (sense_hdr.sense_key << 16) | (sense_hdr.asc << 8) |
460 			sense_hdr.ascq;
461 	/* If it is retryable failure, submit the c9 inquiry again */
462 	if (sense == 0x59136 || sense == 0x68b02 || sense == 0xb8b02 ||
463 			    sense == 0x62900) {
464 		/* 0x59136    - Command lock contention
465 		 * 0x[6b]8b02 - Quiesense in progress or achieved
466 		 * 0x62900    - Power On, Reset, or Bus Device Reset
467 		 */
468 		err = SCSI_DH_RETRY;
469 	}
470 
471 	if (sense)
472 		sdev_printk(KERN_INFO, sdev,
473 			"MODE_SELECT failed with sense 0x%x.\n", sense);
474 done:
475 	return err;
476 }
477 
478 static int send_mode_select(struct scsi_device *sdev, struct rdac_dh_data *h)
479 {
480 	struct request *rq;
481 	struct request_queue *q = sdev->request_queue;
482 	int err, retry_cnt = RDAC_RETRY_COUNT;
483 
484 retry:
485 	err = SCSI_DH_RES_TEMP_UNAVAIL;
486 	rq = rdac_failover_get(sdev, h);
487 	if (!rq)
488 		goto done;
489 
490 	sdev_printk(KERN_INFO, sdev, "%s MODE_SELECT command.\n",
491 		(retry_cnt == RDAC_RETRY_COUNT) ? "queueing" : "retrying");
492 
493 	err = blk_execute_rq(q, NULL, rq, 1);
494 	blk_put_request(rq);
495 	if (err != SCSI_DH_OK) {
496 		err = mode_select_handle_sense(sdev, h->sense);
497 		if (err == SCSI_DH_RETRY && retry_cnt--)
498 			goto retry;
499 	}
500 	if (err == SCSI_DH_OK)
501 		h->state = RDAC_STATE_ACTIVE;
502 
503 done:
504 	return err;
505 }
506 
507 static int rdac_activate(struct scsi_device *sdev)
508 {
509 	struct rdac_dh_data *h = get_rdac_data(sdev);
510 	int err = SCSI_DH_OK;
511 
512 	err = check_ownership(sdev, h);
513 	if (err != SCSI_DH_OK)
514 		goto done;
515 
516 	if (!h->ctlr) {
517 		err = initialize_controller(sdev, h);
518 		if (err != SCSI_DH_OK)
519 			goto done;
520 	}
521 
522 	if (h->ctlr->use_ms10 == -1) {
523 		err = set_mode_select(sdev, h);
524 		if (err != SCSI_DH_OK)
525 			goto done;
526 	}
527 	if (h->lun_state == RDAC_LUN_UNOWNED)
528 		err = send_mode_select(sdev, h);
529 done:
530 	return err;
531 }
532 
533 static int rdac_prep_fn(struct scsi_device *sdev, struct request *req)
534 {
535 	struct rdac_dh_data *h = get_rdac_data(sdev);
536 	int ret = BLKPREP_OK;
537 
538 	if (h->state != RDAC_STATE_ACTIVE) {
539 		ret = BLKPREP_KILL;
540 		req->cmd_flags |= REQ_QUIET;
541 	}
542 	return ret;
543 
544 }
545 
546 static int rdac_check_sense(struct scsi_device *sdev,
547 				struct scsi_sense_hdr *sense_hdr)
548 {
549 	struct rdac_dh_data *h = get_rdac_data(sdev);
550 	switch (sense_hdr->sense_key) {
551 	case NOT_READY:
552 		if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x81)
553 			/* LUN Not Ready - Storage firmware incompatible
554 			 * Manual code synchonisation required.
555 			 *
556 			 * Nothing we can do here. Try to bypass the path.
557 			 */
558 			return SUCCESS;
559 		if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0xA1)
560 			/* LUN Not Ready - Quiescense in progress
561 			 *
562 			 * Just retry and wait.
563 			 */
564 			return ADD_TO_MLQUEUE;
565 		break;
566 	case ILLEGAL_REQUEST:
567 		if (sense_hdr->asc == 0x94 && sense_hdr->ascq == 0x01) {
568 			/* Invalid Request - Current Logical Unit Ownership.
569 			 * Controller is not the current owner of the LUN,
570 			 * Fail the path, so that the other path be used.
571 			 */
572 			h->state = RDAC_STATE_PASSIVE;
573 			return SUCCESS;
574 		}
575 		break;
576 	case UNIT_ATTENTION:
577 		if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00)
578 			/*
579 			 * Power On, Reset, or Bus Device Reset, just retry.
580 			 */
581 			return ADD_TO_MLQUEUE;
582 		break;
583 	}
584 	/* success just means we do not care what scsi-ml does */
585 	return SCSI_RETURN_NOT_HANDLED;
586 }
587 
588 static const struct scsi_dh_devlist rdac_dev_list[] = {
589 	{"IBM", "1722"},
590 	{"IBM", "1724"},
591 	{"IBM", "1726"},
592 	{"IBM", "1742"},
593 	{"IBM", "1814"},
594 	{"IBM", "1815"},
595 	{"IBM", "1818"},
596 	{"IBM", "3526"},
597 	{"SGI", "TP9400"},
598 	{"SGI", "TP9500"},
599 	{"SGI", "IS"},
600 	{"STK", "OPENstorage D280"},
601 	{"SUN", "CSM200_R"},
602 	{"SUN", "LCSM100_F"},
603 	{"DELL", "MD3000"},
604 	{"DELL", "MD3000i"},
605 	{"LSI", "INF-01-00"},
606 	{"ENGENIO", "INF-01-00"},
607 	{NULL, NULL},
608 };
609 
610 static int rdac_bus_attach(struct scsi_device *sdev);
611 static void rdac_bus_detach(struct scsi_device *sdev);
612 
613 static struct scsi_device_handler rdac_dh = {
614 	.name = RDAC_NAME,
615 	.module = THIS_MODULE,
616 	.devlist = rdac_dev_list,
617 	.prep_fn = rdac_prep_fn,
618 	.check_sense = rdac_check_sense,
619 	.attach = rdac_bus_attach,
620 	.detach = rdac_bus_detach,
621 	.activate = rdac_activate,
622 };
623 
624 static int rdac_bus_attach(struct scsi_device *sdev)
625 {
626 	struct scsi_dh_data *scsi_dh_data;
627 	struct rdac_dh_data *h;
628 	unsigned long flags;
629 	int err;
630 
631 	scsi_dh_data = kzalloc(sizeof(struct scsi_device_handler *)
632 			       + sizeof(*h) , GFP_KERNEL);
633 	if (!scsi_dh_data) {
634 		sdev_printk(KERN_ERR, sdev, "%s: Attach failed\n",
635 			    RDAC_NAME);
636 		return 0;
637 	}
638 
639 	scsi_dh_data->scsi_dh = &rdac_dh;
640 	h = (struct rdac_dh_data *) scsi_dh_data->buf;
641 	h->lun = UNINITIALIZED_LUN;
642 	h->state = RDAC_STATE_ACTIVE;
643 
644 	err = get_lun(sdev, h);
645 	if (err != SCSI_DH_OK)
646 		goto failed;
647 
648 	err = check_ownership(sdev, h);
649 	if (err != SCSI_DH_OK)
650 		goto failed;
651 
652 	if (!try_module_get(THIS_MODULE))
653 		goto failed;
654 
655 	spin_lock_irqsave(sdev->request_queue->queue_lock, flags);
656 	sdev->scsi_dh_data = scsi_dh_data;
657 	spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
658 
659 	sdev_printk(KERN_NOTICE, sdev,
660 		    "%s: LUN %d (%s)\n",
661 		    RDAC_NAME, h->lun, lun_state[(int)h->lun_state]);
662 
663 	return 0;
664 
665 failed:
666 	kfree(scsi_dh_data);
667 	sdev_printk(KERN_ERR, sdev, "%s: not attached\n",
668 		    RDAC_NAME);
669 	return -EINVAL;
670 }
671 
672 static void rdac_bus_detach( struct scsi_device *sdev )
673 {
674 	struct scsi_dh_data *scsi_dh_data;
675 	struct rdac_dh_data *h;
676 	unsigned long flags;
677 
678 	spin_lock_irqsave(sdev->request_queue->queue_lock, flags);
679 	scsi_dh_data = sdev->scsi_dh_data;
680 	sdev->scsi_dh_data = NULL;
681 	spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
682 
683 	h = (struct rdac_dh_data *) scsi_dh_data->buf;
684 	if (h->ctlr)
685 		kref_put(&h->ctlr->kref, release_controller);
686 	kfree(scsi_dh_data);
687 	module_put(THIS_MODULE);
688 	sdev_printk(KERN_NOTICE, sdev, "%s: Detached\n", RDAC_NAME);
689 }
690 
691 
692 
693 static int __init rdac_init(void)
694 {
695 	int r;
696 
697 	r = scsi_register_device_handler(&rdac_dh);
698 	if (r != 0)
699 		printk(KERN_ERR "Failed to register scsi device handler.");
700 	return r;
701 }
702 
703 static void __exit rdac_exit(void)
704 {
705 	scsi_unregister_device_handler(&rdac_dh);
706 }
707 
708 module_init(rdac_init);
709 module_exit(rdac_exit);
710 
711 MODULE_DESCRIPTION("Multipath LSI/Engenio RDAC driver");
712 MODULE_AUTHOR("Mike Christie, Chandra Seetharaman");
713 MODULE_LICENSE("GPL");
714