1 /*
2  * LSI/Engenio/NetApp E-Series 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 #include <linux/workqueue.h>
26 #include <linux/slab.h>
27 #include <linux/module.h>
28 
29 #define RDAC_NAME "rdac"
30 #define RDAC_RETRY_COUNT 5
31 
32 /*
33  * LSI mode page stuff
34  *
35  * These struct definitions and the forming of the
36  * mode page were taken from the LSI RDAC 2.4 GPL'd
37  * driver, and then converted to Linux conventions.
38  */
39 #define RDAC_QUIESCENCE_TIME 20
40 /*
41  * Page Codes
42  */
43 #define RDAC_PAGE_CODE_REDUNDANT_CONTROLLER 0x2c
44 
45 /*
46  * Controller modes definitions
47  */
48 #define RDAC_MODE_TRANSFER_SPECIFIED_LUNS	0x02
49 
50 /*
51  * RDAC Options field
52  */
53 #define RDAC_FORCED_QUIESENCE 0x02
54 
55 #define RDAC_TIMEOUT	(60 * HZ)
56 #define RDAC_RETRIES	3
57 
58 struct rdac_mode_6_hdr {
59 	u8	data_len;
60 	u8	medium_type;
61 	u8	device_params;
62 	u8	block_desc_len;
63 };
64 
65 struct rdac_mode_10_hdr {
66 	u16	data_len;
67 	u8	medium_type;
68 	u8	device_params;
69 	u16	reserved;
70 	u16	block_desc_len;
71 };
72 
73 struct rdac_mode_common {
74 	u8	controller_serial[16];
75 	u8	alt_controller_serial[16];
76 	u8	rdac_mode[2];
77 	u8	alt_rdac_mode[2];
78 	u8	quiescence_timeout;
79 	u8	rdac_options;
80 };
81 
82 struct rdac_pg_legacy {
83 	struct rdac_mode_6_hdr hdr;
84 	u8	page_code;
85 	u8	page_len;
86 	struct rdac_mode_common common;
87 #define MODE6_MAX_LUN	32
88 	u8	lun_table[MODE6_MAX_LUN];
89 	u8	reserved2[32];
90 	u8	reserved3;
91 	u8	reserved4;
92 };
93 
94 struct rdac_pg_expanded {
95 	struct rdac_mode_10_hdr hdr;
96 	u8	page_code;
97 	u8	subpage_code;
98 	u8	page_len[2];
99 	struct rdac_mode_common common;
100 	u8	lun_table[256];
101 	u8	reserved3;
102 	u8	reserved4;
103 };
104 
105 struct c9_inquiry {
106 	u8	peripheral_info;
107 	u8	page_code;	/* 0xC9 */
108 	u8	reserved1;
109 	u8	page_len;
110 	u8	page_id[4];	/* "vace" */
111 	u8	avte_cvp;
112 	u8	path_prio;
113 	u8	reserved2[38];
114 };
115 
116 #define SUBSYS_ID_LEN	16
117 #define SLOT_ID_LEN	2
118 #define ARRAY_LABEL_LEN	31
119 
120 struct c4_inquiry {
121 	u8	peripheral_info;
122 	u8	page_code;	/* 0xC4 */
123 	u8	reserved1;
124 	u8	page_len;
125 	u8	page_id[4];	/* "subs" */
126 	u8	subsys_id[SUBSYS_ID_LEN];
127 	u8	revision[4];
128 	u8	slot_id[SLOT_ID_LEN];
129 	u8	reserved[2];
130 };
131 
132 #define UNIQUE_ID_LEN 16
133 struct c8_inquiry {
134 	u8	peripheral_info;
135 	u8	page_code; /* 0xC8 */
136 	u8	reserved1;
137 	u8	page_len;
138 	u8	page_id[4]; /* "edid" */
139 	u8	reserved2[3];
140 	u8	vol_uniq_id_len;
141 	u8	vol_uniq_id[16];
142 	u8	vol_user_label_len;
143 	u8	vol_user_label[60];
144 	u8	array_uniq_id_len;
145 	u8	array_unique_id[UNIQUE_ID_LEN];
146 	u8	array_user_label_len;
147 	u8	array_user_label[60];
148 	u8	lun[8];
149 };
150 
151 struct rdac_controller {
152 	u8			array_id[UNIQUE_ID_LEN];
153 	int			use_ms10;
154 	struct kref		kref;
155 	struct list_head	node; /* list of all controllers */
156 	union			{
157 		struct rdac_pg_legacy legacy;
158 		struct rdac_pg_expanded expanded;
159 	} mode_select;
160 	u8	index;
161 	u8	array_name[ARRAY_LABEL_LEN];
162 	struct Scsi_Host	*host;
163 	spinlock_t		ms_lock;
164 	int			ms_queued;
165 	struct work_struct	ms_work;
166 	struct scsi_device	*ms_sdev;
167 	struct list_head	ms_head;
168 };
169 
170 struct c2_inquiry {
171 	u8	peripheral_info;
172 	u8	page_code;	/* 0xC2 */
173 	u8	reserved1;
174 	u8	page_len;
175 	u8	page_id[4];	/* "swr4" */
176 	u8	sw_version[3];
177 	u8	sw_date[3];
178 	u8	features_enabled;
179 	u8	max_lun_supported;
180 	u8	partitions[239]; /* Total allocation length should be 0xFF */
181 };
182 
183 struct rdac_dh_data {
184 	struct rdac_controller	*ctlr;
185 #define UNINITIALIZED_LUN	(1 << 8)
186 	unsigned		lun;
187 
188 #define RDAC_MODE		0
189 #define RDAC_MODE_AVT		1
190 #define RDAC_MODE_IOSHIP	2
191 	unsigned char		mode;
192 
193 #define RDAC_STATE_ACTIVE	0
194 #define RDAC_STATE_PASSIVE	1
195 	unsigned char		state;
196 
197 #define RDAC_LUN_UNOWNED	0
198 #define RDAC_LUN_OWNED		1
199 	char			lun_state;
200 
201 #define RDAC_PREFERRED		0
202 #define RDAC_NON_PREFERRED	1
203 	char			preferred;
204 
205 	unsigned char		sense[SCSI_SENSE_BUFFERSIZE];
206 	union			{
207 		struct c2_inquiry c2;
208 		struct c4_inquiry c4;
209 		struct c8_inquiry c8;
210 		struct c9_inquiry c9;
211 	} inq;
212 };
213 
214 static const char *mode[] = {
215 	"RDAC",
216 	"AVT",
217 	"IOSHIP",
218 };
219 static const char *lun_state[] =
220 {
221 	"unowned",
222 	"owned",
223 };
224 
225 struct rdac_queue_data {
226 	struct list_head	entry;
227 	struct rdac_dh_data	*h;
228 	activate_complete	callback_fn;
229 	void			*callback_data;
230 };
231 
232 static LIST_HEAD(ctlr_list);
233 static DEFINE_SPINLOCK(list_lock);
234 static struct workqueue_struct *kmpath_rdacd;
235 static void send_mode_select(struct work_struct *work);
236 
237 /*
238  * module parameter to enable rdac debug logging.
239  * 2 bits for each type of logging, only two types defined for now
240  * Can be enhanced if required at later point
241  */
242 static int rdac_logging = 1;
243 module_param(rdac_logging, int, S_IRUGO|S_IWUSR);
244 MODULE_PARM_DESC(rdac_logging, "A bit mask of rdac logging levels, "
245 		"Default is 1 - failover logging enabled, "
246 		"set it to 0xF to enable all the logs");
247 
248 #define RDAC_LOG_FAILOVER	0
249 #define RDAC_LOG_SENSE		2
250 
251 #define RDAC_LOG_BITS		2
252 
253 #define RDAC_LOG_LEVEL(SHIFT)  \
254 	((rdac_logging >> (SHIFT)) & ((1 << (RDAC_LOG_BITS)) - 1))
255 
256 #define RDAC_LOG(SHIFT, sdev, f, arg...) \
257 do { \
258 	if (unlikely(RDAC_LOG_LEVEL(SHIFT))) \
259 		sdev_printk(KERN_INFO, sdev, RDAC_NAME ": " f "\n", ## arg); \
260 } while (0);
261 
262 static struct request *get_rdac_req(struct scsi_device *sdev,
263 			void *buffer, unsigned buflen, int rw)
264 {
265 	struct request *rq;
266 	struct request_queue *q = sdev->request_queue;
267 
268 	rq = blk_get_request(q, rw, GFP_NOIO);
269 
270 	if (IS_ERR(rq)) {
271 		sdev_printk(KERN_INFO, sdev,
272 				"get_rdac_req: blk_get_request failed.\n");
273 		return NULL;
274 	}
275 	blk_rq_set_block_pc(rq);
276 
277 	if (buflen && blk_rq_map_kern(q, rq, buffer, buflen, GFP_NOIO)) {
278 		blk_put_request(rq);
279 		sdev_printk(KERN_INFO, sdev,
280 				"get_rdac_req: blk_rq_map_kern failed.\n");
281 		return NULL;
282 	}
283 
284 	rq->cmd_flags |= REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
285 			 REQ_FAILFAST_DRIVER;
286 	rq->retries = RDAC_RETRIES;
287 	rq->timeout = RDAC_TIMEOUT;
288 
289 	return rq;
290 }
291 
292 static struct request *rdac_failover_get(struct scsi_device *sdev,
293 			struct rdac_dh_data *h, struct list_head *list)
294 {
295 	struct request *rq;
296 	struct rdac_mode_common *common;
297 	unsigned data_size;
298 	struct rdac_queue_data *qdata;
299 	u8 *lun_table;
300 
301 	if (h->ctlr->use_ms10) {
302 		struct rdac_pg_expanded *rdac_pg;
303 
304 		data_size = sizeof(struct rdac_pg_expanded);
305 		rdac_pg = &h->ctlr->mode_select.expanded;
306 		memset(rdac_pg, 0, data_size);
307 		common = &rdac_pg->common;
308 		rdac_pg->page_code = RDAC_PAGE_CODE_REDUNDANT_CONTROLLER + 0x40;
309 		rdac_pg->subpage_code = 0x1;
310 		rdac_pg->page_len[0] = 0x01;
311 		rdac_pg->page_len[1] = 0x28;
312 		lun_table = rdac_pg->lun_table;
313 	} else {
314 		struct rdac_pg_legacy *rdac_pg;
315 
316 		data_size = sizeof(struct rdac_pg_legacy);
317 		rdac_pg = &h->ctlr->mode_select.legacy;
318 		memset(rdac_pg, 0, data_size);
319 		common = &rdac_pg->common;
320 		rdac_pg->page_code = RDAC_PAGE_CODE_REDUNDANT_CONTROLLER;
321 		rdac_pg->page_len = 0x68;
322 		lun_table = rdac_pg->lun_table;
323 	}
324 	common->rdac_mode[1] = RDAC_MODE_TRANSFER_SPECIFIED_LUNS;
325 	common->quiescence_timeout = RDAC_QUIESCENCE_TIME;
326 	common->rdac_options = RDAC_FORCED_QUIESENCE;
327 
328 	list_for_each_entry(qdata, list, entry) {
329 		lun_table[qdata->h->lun] = 0x81;
330 	}
331 
332 	/* get request for block layer packet command */
333 	rq = get_rdac_req(sdev, &h->ctlr->mode_select, data_size, WRITE);
334 	if (!rq)
335 		return NULL;
336 
337 	/* Prepare the command. */
338 	if (h->ctlr->use_ms10) {
339 		rq->cmd[0] = MODE_SELECT_10;
340 		rq->cmd[7] = data_size >> 8;
341 		rq->cmd[8] = data_size & 0xff;
342 	} else {
343 		rq->cmd[0] = MODE_SELECT;
344 		rq->cmd[4] = data_size;
345 	}
346 	rq->cmd_len = COMMAND_SIZE(rq->cmd[0]);
347 
348 	rq->sense = h->sense;
349 	memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
350 	rq->sense_len = 0;
351 
352 	return rq;
353 }
354 
355 static void release_controller(struct kref *kref)
356 {
357 	struct rdac_controller *ctlr;
358 	ctlr = container_of(kref, struct rdac_controller, kref);
359 
360 	list_del(&ctlr->node);
361 	kfree(ctlr);
362 }
363 
364 static struct rdac_controller *get_controller(int index, char *array_name,
365 			u8 *array_id, struct scsi_device *sdev)
366 {
367 	struct rdac_controller *ctlr, *tmp;
368 
369 	list_for_each_entry(tmp, &ctlr_list, node) {
370 		if ((memcmp(tmp->array_id, array_id, UNIQUE_ID_LEN) == 0) &&
371 			  (tmp->index == index) &&
372 			  (tmp->host == sdev->host)) {
373 			kref_get(&tmp->kref);
374 			return tmp;
375 		}
376 	}
377 	ctlr = kmalloc(sizeof(*ctlr), GFP_ATOMIC);
378 	if (!ctlr)
379 		return NULL;
380 
381 	/* initialize fields of controller */
382 	memcpy(ctlr->array_id, array_id, UNIQUE_ID_LEN);
383 	ctlr->index = index;
384 	ctlr->host = sdev->host;
385 	memcpy(ctlr->array_name, array_name, ARRAY_LABEL_LEN);
386 
387 	kref_init(&ctlr->kref);
388 	ctlr->use_ms10 = -1;
389 	ctlr->ms_queued = 0;
390 	ctlr->ms_sdev = NULL;
391 	spin_lock_init(&ctlr->ms_lock);
392 	INIT_WORK(&ctlr->ms_work, send_mode_select);
393 	INIT_LIST_HEAD(&ctlr->ms_head);
394 	list_add(&ctlr->node, &ctlr_list);
395 
396 	return ctlr;
397 }
398 
399 static int submit_inquiry(struct scsi_device *sdev, int page_code,
400 			  unsigned int len, struct rdac_dh_data *h)
401 {
402 	struct request *rq;
403 	struct request_queue *q = sdev->request_queue;
404 	int err = SCSI_DH_RES_TEMP_UNAVAIL;
405 
406 	rq = get_rdac_req(sdev, &h->inq, len, READ);
407 	if (!rq)
408 		goto done;
409 
410 	/* Prepare the command. */
411 	rq->cmd[0] = INQUIRY;
412 	rq->cmd[1] = 1;
413 	rq->cmd[2] = page_code;
414 	rq->cmd[4] = len;
415 	rq->cmd_len = COMMAND_SIZE(INQUIRY);
416 
417 	rq->sense = h->sense;
418 	memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
419 	rq->sense_len = 0;
420 
421 	err = blk_execute_rq(q, NULL, rq, 1);
422 	if (err == -EIO)
423 		err = SCSI_DH_IO;
424 
425 	blk_put_request(rq);
426 done:
427 	return err;
428 }
429 
430 static int get_lun_info(struct scsi_device *sdev, struct rdac_dh_data *h,
431 			char *array_name, u8 *array_id)
432 {
433 	int err, i;
434 	struct c8_inquiry *inqp;
435 
436 	err = submit_inquiry(sdev, 0xC8, sizeof(struct c8_inquiry), h);
437 	if (err == SCSI_DH_OK) {
438 		inqp = &h->inq.c8;
439 		if (inqp->page_code != 0xc8)
440 			return SCSI_DH_NOSYS;
441 		if (inqp->page_id[0] != 'e' || inqp->page_id[1] != 'd' ||
442 		    inqp->page_id[2] != 'i' || inqp->page_id[3] != 'd')
443 			return SCSI_DH_NOSYS;
444 		h->lun = inqp->lun[7]; /* Uses only the last byte */
445 
446 		for(i=0; i<ARRAY_LABEL_LEN-1; ++i)
447 			*(array_name+i) = inqp->array_user_label[(2*i)+1];
448 
449 		*(array_name+ARRAY_LABEL_LEN-1) = '\0';
450 		memset(array_id, 0, UNIQUE_ID_LEN);
451 		memcpy(array_id, inqp->array_unique_id, inqp->array_uniq_id_len);
452 	}
453 	return err;
454 }
455 
456 static int check_ownership(struct scsi_device *sdev, struct rdac_dh_data *h)
457 {
458 	int err;
459 	struct c9_inquiry *inqp;
460 
461 	h->state = RDAC_STATE_ACTIVE;
462 	err = submit_inquiry(sdev, 0xC9, sizeof(struct c9_inquiry), h);
463 	if (err == SCSI_DH_OK) {
464 		inqp = &h->inq.c9;
465 		/* detect the operating mode */
466 		if ((inqp->avte_cvp >> 5) & 0x1)
467 			h->mode = RDAC_MODE_IOSHIP; /* LUN in IOSHIP mode */
468 		else if (inqp->avte_cvp >> 7)
469 			h->mode = RDAC_MODE_AVT; /* LUN in AVT mode */
470 		else
471 			h->mode = RDAC_MODE; /* LUN in RDAC mode */
472 
473 		/* Update ownership */
474 		if (inqp->avte_cvp & 0x1)
475 			h->lun_state = RDAC_LUN_OWNED;
476 		else {
477 			h->lun_state = RDAC_LUN_UNOWNED;
478 			if (h->mode == RDAC_MODE)
479 				h->state = RDAC_STATE_PASSIVE;
480 		}
481 
482 		/* Update path prio*/
483 		if (inqp->path_prio & 0x1)
484 			h->preferred = RDAC_PREFERRED;
485 		else
486 			h->preferred = RDAC_NON_PREFERRED;
487 	}
488 
489 	return err;
490 }
491 
492 static int initialize_controller(struct scsi_device *sdev,
493 		struct rdac_dh_data *h, char *array_name, u8 *array_id)
494 {
495 	int err, index;
496 	struct c4_inquiry *inqp;
497 
498 	err = submit_inquiry(sdev, 0xC4, sizeof(struct c4_inquiry), h);
499 	if (err == SCSI_DH_OK) {
500 		inqp = &h->inq.c4;
501 		/* get the controller index */
502 		if (inqp->slot_id[1] == 0x31)
503 			index = 0;
504 		else
505 			index = 1;
506 
507 		spin_lock(&list_lock);
508 		h->ctlr = get_controller(index, array_name, array_id, sdev);
509 		if (!h->ctlr)
510 			err = SCSI_DH_RES_TEMP_UNAVAIL;
511 		spin_unlock(&list_lock);
512 	}
513 	return err;
514 }
515 
516 static int set_mode_select(struct scsi_device *sdev, struct rdac_dh_data *h)
517 {
518 	int err;
519 	struct c2_inquiry *inqp;
520 
521 	err = submit_inquiry(sdev, 0xC2, sizeof(struct c2_inquiry), h);
522 	if (err == SCSI_DH_OK) {
523 		inqp = &h->inq.c2;
524 		/*
525 		 * If more than MODE6_MAX_LUN luns are supported, use
526 		 * mode select 10
527 		 */
528 		if (inqp->max_lun_supported >= MODE6_MAX_LUN)
529 			h->ctlr->use_ms10 = 1;
530 		else
531 			h->ctlr->use_ms10 = 0;
532 	}
533 	return err;
534 }
535 
536 static int mode_select_handle_sense(struct scsi_device *sdev,
537 					unsigned char *sensebuf)
538 {
539 	struct scsi_sense_hdr sense_hdr;
540 	int err = SCSI_DH_IO, ret;
541 	struct rdac_dh_data *h = sdev->handler_data;
542 
543 	ret = scsi_normalize_sense(sensebuf, SCSI_SENSE_BUFFERSIZE, &sense_hdr);
544 	if (!ret)
545 		goto done;
546 
547 	switch (sense_hdr.sense_key) {
548 	case NO_SENSE:
549 	case ABORTED_COMMAND:
550 	case UNIT_ATTENTION:
551 		err = SCSI_DH_RETRY;
552 		break;
553 	case NOT_READY:
554 		if (sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x01)
555 			/* LUN Not Ready and is in the Process of Becoming
556 			 * Ready
557 			 */
558 			err = SCSI_DH_RETRY;
559 		break;
560 	case ILLEGAL_REQUEST:
561 		if (sense_hdr.asc == 0x91 && sense_hdr.ascq == 0x36)
562 			/*
563 			 * Command Lock contention
564 			 */
565 			err = SCSI_DH_RETRY;
566 		break;
567 	default:
568 		break;
569 	}
570 
571 	RDAC_LOG(RDAC_LOG_FAILOVER, sdev, "array %s, ctlr %d, "
572 		"MODE_SELECT returned with sense %02x/%02x/%02x",
573 		(char *) h->ctlr->array_name, h->ctlr->index,
574 		sense_hdr.sense_key, sense_hdr.asc, sense_hdr.ascq);
575 
576 done:
577 	return err;
578 }
579 
580 static void send_mode_select(struct work_struct *work)
581 {
582 	struct rdac_controller *ctlr =
583 		container_of(work, struct rdac_controller, ms_work);
584 	struct request *rq;
585 	struct scsi_device *sdev = ctlr->ms_sdev;
586 	struct rdac_dh_data *h = sdev->handler_data;
587 	struct request_queue *q = sdev->request_queue;
588 	int err, retry_cnt = RDAC_RETRY_COUNT;
589 	struct rdac_queue_data *tmp, *qdata;
590 	LIST_HEAD(list);
591 
592 	spin_lock(&ctlr->ms_lock);
593 	list_splice_init(&ctlr->ms_head, &list);
594 	ctlr->ms_queued = 0;
595 	ctlr->ms_sdev = NULL;
596 	spin_unlock(&ctlr->ms_lock);
597 
598 retry:
599 	err = SCSI_DH_RES_TEMP_UNAVAIL;
600 	rq = rdac_failover_get(sdev, h, &list);
601 	if (!rq)
602 		goto done;
603 
604 	RDAC_LOG(RDAC_LOG_FAILOVER, sdev, "array %s, ctlr %d, "
605 		"%s MODE_SELECT command",
606 		(char *) h->ctlr->array_name, h->ctlr->index,
607 		(retry_cnt == RDAC_RETRY_COUNT) ? "queueing" : "retrying");
608 
609 	err = blk_execute_rq(q, NULL, rq, 1);
610 	blk_put_request(rq);
611 	if (err != SCSI_DH_OK) {
612 		err = mode_select_handle_sense(sdev, h->sense);
613 		if (err == SCSI_DH_RETRY && retry_cnt--)
614 			goto retry;
615 	}
616 	if (err == SCSI_DH_OK) {
617 		h->state = RDAC_STATE_ACTIVE;
618 		RDAC_LOG(RDAC_LOG_FAILOVER, sdev, "array %s, ctlr %d, "
619 				"MODE_SELECT completed",
620 				(char *) h->ctlr->array_name, h->ctlr->index);
621 	}
622 
623 done:
624 	list_for_each_entry_safe(qdata, tmp, &list, entry) {
625 		list_del(&qdata->entry);
626 		if (err == SCSI_DH_OK)
627 			qdata->h->state = RDAC_STATE_ACTIVE;
628 		if (qdata->callback_fn)
629 			qdata->callback_fn(qdata->callback_data, err);
630 		kfree(qdata);
631 	}
632 	return;
633 }
634 
635 static int queue_mode_select(struct scsi_device *sdev,
636 				activate_complete fn, void *data)
637 {
638 	struct rdac_queue_data *qdata;
639 	struct rdac_controller *ctlr;
640 
641 	qdata = kzalloc(sizeof(*qdata), GFP_KERNEL);
642 	if (!qdata)
643 		return SCSI_DH_RETRY;
644 
645 	qdata->h = sdev->handler_data;
646 	qdata->callback_fn = fn;
647 	qdata->callback_data = data;
648 
649 	ctlr = qdata->h->ctlr;
650 	spin_lock(&ctlr->ms_lock);
651 	list_add_tail(&qdata->entry, &ctlr->ms_head);
652 	if (!ctlr->ms_queued) {
653 		ctlr->ms_queued = 1;
654 		ctlr->ms_sdev = sdev;
655 		queue_work(kmpath_rdacd, &ctlr->ms_work);
656 	}
657 	spin_unlock(&ctlr->ms_lock);
658 	return SCSI_DH_OK;
659 }
660 
661 static int rdac_activate(struct scsi_device *sdev,
662 			activate_complete fn, void *data)
663 {
664 	struct rdac_dh_data *h = sdev->handler_data;
665 	int err = SCSI_DH_OK;
666 	int act = 0;
667 
668 	err = check_ownership(sdev, h);
669 	if (err != SCSI_DH_OK)
670 		goto done;
671 
672 	switch (h->mode) {
673 	case RDAC_MODE:
674 		if (h->lun_state == RDAC_LUN_UNOWNED)
675 			act = 1;
676 		break;
677 	case RDAC_MODE_IOSHIP:
678 		if ((h->lun_state == RDAC_LUN_UNOWNED) &&
679 		    (h->preferred == RDAC_PREFERRED))
680 			act = 1;
681 		break;
682 	default:
683 		break;
684 	}
685 
686 	if (act) {
687 		err = queue_mode_select(sdev, fn, data);
688 		if (err == SCSI_DH_OK)
689 			return 0;
690 	}
691 done:
692 	if (fn)
693 		fn(data, err);
694 	return 0;
695 }
696 
697 static int rdac_prep_fn(struct scsi_device *sdev, struct request *req)
698 {
699 	struct rdac_dh_data *h = sdev->handler_data;
700 	int ret = BLKPREP_OK;
701 
702 	if (h->state != RDAC_STATE_ACTIVE) {
703 		ret = BLKPREP_KILL;
704 		req->cmd_flags |= REQ_QUIET;
705 	}
706 	return ret;
707 
708 }
709 
710 static int rdac_check_sense(struct scsi_device *sdev,
711 				struct scsi_sense_hdr *sense_hdr)
712 {
713 	struct rdac_dh_data *h = sdev->handler_data;
714 
715 	RDAC_LOG(RDAC_LOG_SENSE, sdev, "array %s, ctlr %d, "
716 			"I/O returned with sense %02x/%02x/%02x",
717 			(char *) h->ctlr->array_name, h->ctlr->index,
718 			sense_hdr->sense_key, sense_hdr->asc, sense_hdr->ascq);
719 
720 	switch (sense_hdr->sense_key) {
721 	case NOT_READY:
722 		if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x01)
723 			/* LUN Not Ready - Logical Unit Not Ready and is in
724 			* the process of becoming ready
725 			* Just retry.
726 			*/
727 			return ADD_TO_MLQUEUE;
728 		if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x81)
729 			/* LUN Not Ready - Storage firmware incompatible
730 			 * Manual code synchonisation required.
731 			 *
732 			 * Nothing we can do here. Try to bypass the path.
733 			 */
734 			return SUCCESS;
735 		if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0xA1)
736 			/* LUN Not Ready - Quiescense in progress
737 			 *
738 			 * Just retry and wait.
739 			 */
740 			return ADD_TO_MLQUEUE;
741 		if (sense_hdr->asc == 0xA1  && sense_hdr->ascq == 0x02)
742 			/* LUN Not Ready - Quiescense in progress
743 			 * or has been achieved
744 			 * Just retry.
745 			 */
746 			return ADD_TO_MLQUEUE;
747 		break;
748 	case ILLEGAL_REQUEST:
749 		if (sense_hdr->asc == 0x94 && sense_hdr->ascq == 0x01) {
750 			/* Invalid Request - Current Logical Unit Ownership.
751 			 * Controller is not the current owner of the LUN,
752 			 * Fail the path, so that the other path be used.
753 			 */
754 			h->state = RDAC_STATE_PASSIVE;
755 			return SUCCESS;
756 		}
757 		break;
758 	case UNIT_ATTENTION:
759 		if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00)
760 			/*
761 			 * Power On, Reset, or Bus Device Reset, just retry.
762 			 */
763 			return ADD_TO_MLQUEUE;
764 		if (sense_hdr->asc == 0x8b && sense_hdr->ascq == 0x02)
765 			/*
766 			 * Quiescence in progress , just retry.
767 			 */
768 			return ADD_TO_MLQUEUE;
769 		break;
770 	}
771 	/* success just means we do not care what scsi-ml does */
772 	return SCSI_RETURN_NOT_HANDLED;
773 }
774 
775 static int rdac_bus_attach(struct scsi_device *sdev)
776 {
777 	struct rdac_dh_data *h;
778 	int err;
779 	char array_name[ARRAY_LABEL_LEN];
780 	char array_id[UNIQUE_ID_LEN];
781 
782 	h = kzalloc(sizeof(*h) , GFP_KERNEL);
783 	if (!h)
784 		return -ENOMEM;
785 	h->lun = UNINITIALIZED_LUN;
786 	h->state = RDAC_STATE_ACTIVE;
787 
788 	err = get_lun_info(sdev, h, array_name, array_id);
789 	if (err != SCSI_DH_OK)
790 		goto failed;
791 
792 	err = initialize_controller(sdev, h, array_name, array_id);
793 	if (err != SCSI_DH_OK)
794 		goto failed;
795 
796 	err = check_ownership(sdev, h);
797 	if (err != SCSI_DH_OK)
798 		goto clean_ctlr;
799 
800 	err = set_mode_select(sdev, h);
801 	if (err != SCSI_DH_OK)
802 		goto clean_ctlr;
803 
804 	sdev_printk(KERN_NOTICE, sdev,
805 		    "%s: LUN %d (%s) (%s)\n",
806 		    RDAC_NAME, h->lun, mode[(int)h->mode],
807 		    lun_state[(int)h->lun_state]);
808 
809 	sdev->handler_data = h;
810 	return 0;
811 
812 clean_ctlr:
813 	spin_lock(&list_lock);
814 	kref_put(&h->ctlr->kref, release_controller);
815 	spin_unlock(&list_lock);
816 
817 failed:
818 	kfree(h);
819 	return -EINVAL;
820 }
821 
822 static void rdac_bus_detach( struct scsi_device *sdev )
823 {
824 	struct rdac_dh_data *h = sdev->handler_data;
825 
826 	if (h->ctlr && h->ctlr->ms_queued)
827 		flush_workqueue(kmpath_rdacd);
828 
829 	spin_lock(&list_lock);
830 	if (h->ctlr)
831 		kref_put(&h->ctlr->kref, release_controller);
832 	spin_unlock(&list_lock);
833 	sdev->handler_data = NULL;
834 	kfree(h);
835 }
836 
837 static struct scsi_device_handler rdac_dh = {
838 	.name = RDAC_NAME,
839 	.module = THIS_MODULE,
840 	.prep_fn = rdac_prep_fn,
841 	.check_sense = rdac_check_sense,
842 	.attach = rdac_bus_attach,
843 	.detach = rdac_bus_detach,
844 	.activate = rdac_activate,
845 };
846 
847 static int __init rdac_init(void)
848 {
849 	int r;
850 
851 	r = scsi_register_device_handler(&rdac_dh);
852 	if (r != 0) {
853 		printk(KERN_ERR "Failed to register scsi device handler.");
854 		goto done;
855 	}
856 
857 	/*
858 	 * Create workqueue to handle mode selects for rdac
859 	 */
860 	kmpath_rdacd = create_singlethread_workqueue("kmpath_rdacd");
861 	if (!kmpath_rdacd) {
862 		scsi_unregister_device_handler(&rdac_dh);
863 		printk(KERN_ERR "kmpath_rdacd creation failed.\n");
864 
865 		r = -EINVAL;
866 	}
867 done:
868 	return r;
869 }
870 
871 static void __exit rdac_exit(void)
872 {
873 	destroy_workqueue(kmpath_rdacd);
874 	scsi_unregister_device_handler(&rdac_dh);
875 }
876 
877 module_init(rdac_init);
878 module_exit(rdac_exit);
879 
880 MODULE_DESCRIPTION("Multipath LSI/Engenio/NetApp E-Series RDAC driver");
881 MODULE_AUTHOR("Mike Christie, Chandra Seetharaman");
882 MODULE_VERSION("01.00.0000.0000");
883 MODULE_LICENSE("GPL");
884