1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Generic SCSI-3 ALUA SCSI Device Handler
4 *
5 * Copyright (C) 2007-2010 Hannes Reinecke, SUSE Linux Products GmbH.
6 * All rights reserved.
7 */
8 #include <linux/slab.h>
9 #include <linux/delay.h>
10 #include <linux/module.h>
11 #include <asm/unaligned.h>
12 #include <scsi/scsi.h>
13 #include <scsi/scsi_proto.h>
14 #include <scsi/scsi_dbg.h>
15 #include <scsi/scsi_eh.h>
16 #include <scsi/scsi_dh.h>
17
18 #define ALUA_DH_NAME "alua"
19 #define ALUA_DH_VER "2.0"
20
21 #define TPGS_SUPPORT_NONE 0x00
22 #define TPGS_SUPPORT_OPTIMIZED 0x01
23 #define TPGS_SUPPORT_NONOPTIMIZED 0x02
24 #define TPGS_SUPPORT_STANDBY 0x04
25 #define TPGS_SUPPORT_UNAVAILABLE 0x08
26 #define TPGS_SUPPORT_LBA_DEPENDENT 0x10
27 #define TPGS_SUPPORT_OFFLINE 0x40
28 #define TPGS_SUPPORT_TRANSITION 0x80
29 #define TPGS_SUPPORT_ALL 0xdf
30
31 #define RTPG_FMT_MASK 0x70
32 #define RTPG_FMT_EXT_HDR 0x10
33
34 #define TPGS_MODE_UNINITIALIZED -1
35 #define TPGS_MODE_NONE 0x0
36 #define TPGS_MODE_IMPLICIT 0x1
37 #define TPGS_MODE_EXPLICIT 0x2
38
39 #define ALUA_RTPG_SIZE 128
40 #define ALUA_FAILOVER_TIMEOUT 60
41 #define ALUA_FAILOVER_RETRIES 5
42 #define ALUA_RTPG_DELAY_MSECS 5
43 #define ALUA_RTPG_RETRY_DELAY 2
44
45 /* device handler flags */
46 #define ALUA_OPTIMIZE_STPG 0x01
47 #define ALUA_RTPG_EXT_HDR_UNSUPP 0x02
48 /* State machine flags */
49 #define ALUA_PG_RUN_RTPG 0x10
50 #define ALUA_PG_RUN_STPG 0x20
51 #define ALUA_PG_RUNNING 0x40
52
53 static uint optimize_stpg;
54 module_param(optimize_stpg, uint, S_IRUGO|S_IWUSR);
55 MODULE_PARM_DESC(optimize_stpg, "Allow use of a non-optimized path, rather than sending a STPG, when implicit TPGS is supported (0=No,1=Yes). Default is 0.");
56
57 static LIST_HEAD(port_group_list);
58 static DEFINE_SPINLOCK(port_group_lock);
59 static struct workqueue_struct *kaluad_wq;
60
61 struct alua_port_group {
62 struct kref kref;
63 struct rcu_head rcu;
64 struct list_head node;
65 struct list_head dh_list;
66 unsigned char device_id_str[256];
67 int device_id_len;
68 int group_id;
69 int tpgs;
70 int state;
71 int pref;
72 int valid_states;
73 unsigned flags; /* used for optimizing STPG */
74 unsigned char transition_tmo;
75 unsigned long expiry;
76 unsigned long interval;
77 struct delayed_work rtpg_work;
78 spinlock_t lock;
79 struct list_head rtpg_list;
80 struct scsi_device *rtpg_sdev;
81 };
82
83 struct alua_dh_data {
84 struct list_head node;
85 struct alua_port_group __rcu *pg;
86 int group_id;
87 spinlock_t pg_lock;
88 struct scsi_device *sdev;
89 int init_error;
90 struct mutex init_mutex;
91 bool disabled;
92 };
93
94 struct alua_queue_data {
95 struct list_head entry;
96 activate_complete callback_fn;
97 void *callback_data;
98 };
99
100 #define ALUA_POLICY_SWITCH_CURRENT 0
101 #define ALUA_POLICY_SWITCH_ALL 1
102
103 static void alua_rtpg_work(struct work_struct *work);
104 static bool alua_rtpg_queue(struct alua_port_group *pg,
105 struct scsi_device *sdev,
106 struct alua_queue_data *qdata, bool force);
107 static void alua_check(struct scsi_device *sdev, bool force);
108
release_port_group(struct kref * kref)109 static void release_port_group(struct kref *kref)
110 {
111 struct alua_port_group *pg;
112
113 pg = container_of(kref, struct alua_port_group, kref);
114 if (pg->rtpg_sdev)
115 flush_delayed_work(&pg->rtpg_work);
116 spin_lock(&port_group_lock);
117 list_del(&pg->node);
118 spin_unlock(&port_group_lock);
119 kfree_rcu(pg, rcu);
120 }
121
122 /*
123 * submit_rtpg - Issue a REPORT TARGET GROUP STATES command
124 * @sdev: sdev the command should be sent to
125 */
submit_rtpg(struct scsi_device * sdev,unsigned char * buff,int bufflen,struct scsi_sense_hdr * sshdr,int flags)126 static int submit_rtpg(struct scsi_device *sdev, unsigned char *buff,
127 int bufflen, struct scsi_sense_hdr *sshdr, int flags)
128 {
129 u8 cdb[MAX_COMMAND_SIZE];
130 int req_flags = REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
131 REQ_FAILFAST_DRIVER;
132
133 /* Prepare the command. */
134 memset(cdb, 0x0, MAX_COMMAND_SIZE);
135 cdb[0] = MAINTENANCE_IN;
136 if (!(flags & ALUA_RTPG_EXT_HDR_UNSUPP))
137 cdb[1] = MI_REPORT_TARGET_PGS | MI_EXT_HDR_PARAM_FMT;
138 else
139 cdb[1] = MI_REPORT_TARGET_PGS;
140 put_unaligned_be32(bufflen, &cdb[6]);
141
142 return scsi_execute(sdev, cdb, DMA_FROM_DEVICE, buff, bufflen, NULL,
143 sshdr, ALUA_FAILOVER_TIMEOUT * HZ,
144 ALUA_FAILOVER_RETRIES, req_flags, 0, NULL);
145 }
146
147 /*
148 * submit_stpg - Issue a SET TARGET PORT GROUP command
149 *
150 * Currently we're only setting the current target port group state
151 * to 'active/optimized' and let the array firmware figure out
152 * the states of the remaining groups.
153 */
submit_stpg(struct scsi_device * sdev,int group_id,struct scsi_sense_hdr * sshdr)154 static int submit_stpg(struct scsi_device *sdev, int group_id,
155 struct scsi_sense_hdr *sshdr)
156 {
157 u8 cdb[MAX_COMMAND_SIZE];
158 unsigned char stpg_data[8];
159 int stpg_len = 8;
160 int req_flags = REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
161 REQ_FAILFAST_DRIVER;
162
163 /* Prepare the data buffer */
164 memset(stpg_data, 0, stpg_len);
165 stpg_data[4] = SCSI_ACCESS_STATE_OPTIMAL;
166 put_unaligned_be16(group_id, &stpg_data[6]);
167
168 /* Prepare the command. */
169 memset(cdb, 0x0, MAX_COMMAND_SIZE);
170 cdb[0] = MAINTENANCE_OUT;
171 cdb[1] = MO_SET_TARGET_PGS;
172 put_unaligned_be32(stpg_len, &cdb[6]);
173
174 return scsi_execute(sdev, cdb, DMA_TO_DEVICE, stpg_data, stpg_len, NULL,
175 sshdr, ALUA_FAILOVER_TIMEOUT * HZ,
176 ALUA_FAILOVER_RETRIES, req_flags, 0, NULL);
177 }
178
alua_find_get_pg(char * id_str,size_t id_size,int group_id)179 static struct alua_port_group *alua_find_get_pg(char *id_str, size_t id_size,
180 int group_id)
181 {
182 struct alua_port_group *pg;
183
184 if (!id_str || !id_size || !strlen(id_str))
185 return NULL;
186
187 list_for_each_entry(pg, &port_group_list, node) {
188 if (pg->group_id != group_id)
189 continue;
190 if (!pg->device_id_len || pg->device_id_len != id_size)
191 continue;
192 if (strncmp(pg->device_id_str, id_str, id_size))
193 continue;
194 if (!kref_get_unless_zero(&pg->kref))
195 continue;
196 return pg;
197 }
198
199 return NULL;
200 }
201
202 /*
203 * alua_alloc_pg - Allocate a new port_group structure
204 * @sdev: scsi device
205 * @group_id: port group id
206 * @tpgs: target port group settings
207 *
208 * Allocate a new port_group structure for a given
209 * device.
210 */
alua_alloc_pg(struct scsi_device * sdev,int group_id,int tpgs)211 static struct alua_port_group *alua_alloc_pg(struct scsi_device *sdev,
212 int group_id, int tpgs)
213 {
214 struct alua_port_group *pg, *tmp_pg;
215
216 pg = kzalloc(sizeof(struct alua_port_group), GFP_KERNEL);
217 if (!pg)
218 return ERR_PTR(-ENOMEM);
219
220 pg->device_id_len = scsi_vpd_lun_id(sdev, pg->device_id_str,
221 sizeof(pg->device_id_str));
222 if (pg->device_id_len <= 0) {
223 /*
224 * TPGS supported but no device identification found.
225 * Generate private device identification.
226 */
227 sdev_printk(KERN_INFO, sdev,
228 "%s: No device descriptors found\n",
229 ALUA_DH_NAME);
230 pg->device_id_str[0] = '\0';
231 pg->device_id_len = 0;
232 }
233 pg->group_id = group_id;
234 pg->tpgs = tpgs;
235 pg->state = SCSI_ACCESS_STATE_OPTIMAL;
236 pg->valid_states = TPGS_SUPPORT_ALL;
237 if (optimize_stpg)
238 pg->flags |= ALUA_OPTIMIZE_STPG;
239 kref_init(&pg->kref);
240 INIT_DELAYED_WORK(&pg->rtpg_work, alua_rtpg_work);
241 INIT_LIST_HEAD(&pg->rtpg_list);
242 INIT_LIST_HEAD(&pg->node);
243 INIT_LIST_HEAD(&pg->dh_list);
244 spin_lock_init(&pg->lock);
245
246 spin_lock(&port_group_lock);
247 tmp_pg = alua_find_get_pg(pg->device_id_str, pg->device_id_len,
248 group_id);
249 if (tmp_pg) {
250 spin_unlock(&port_group_lock);
251 kfree(pg);
252 return tmp_pg;
253 }
254
255 list_add(&pg->node, &port_group_list);
256 spin_unlock(&port_group_lock);
257
258 return pg;
259 }
260
261 /*
262 * alua_check_tpgs - Evaluate TPGS setting
263 * @sdev: device to be checked
264 *
265 * Examine the TPGS setting of the sdev to find out if ALUA
266 * is supported.
267 */
alua_check_tpgs(struct scsi_device * sdev)268 static int alua_check_tpgs(struct scsi_device *sdev)
269 {
270 int tpgs = TPGS_MODE_NONE;
271
272 /*
273 * ALUA support for non-disk devices is fraught with
274 * difficulties, so disable it for now.
275 */
276 if (sdev->type != TYPE_DISK) {
277 sdev_printk(KERN_INFO, sdev,
278 "%s: disable for non-disk devices\n",
279 ALUA_DH_NAME);
280 return tpgs;
281 }
282
283 tpgs = scsi_device_tpgs(sdev);
284 switch (tpgs) {
285 case TPGS_MODE_EXPLICIT|TPGS_MODE_IMPLICIT:
286 sdev_printk(KERN_INFO, sdev,
287 "%s: supports implicit and explicit TPGS\n",
288 ALUA_DH_NAME);
289 break;
290 case TPGS_MODE_EXPLICIT:
291 sdev_printk(KERN_INFO, sdev, "%s: supports explicit TPGS\n",
292 ALUA_DH_NAME);
293 break;
294 case TPGS_MODE_IMPLICIT:
295 sdev_printk(KERN_INFO, sdev, "%s: supports implicit TPGS\n",
296 ALUA_DH_NAME);
297 break;
298 case TPGS_MODE_NONE:
299 sdev_printk(KERN_INFO, sdev, "%s: not supported\n",
300 ALUA_DH_NAME);
301 break;
302 default:
303 sdev_printk(KERN_INFO, sdev,
304 "%s: unsupported TPGS setting %d\n",
305 ALUA_DH_NAME, tpgs);
306 tpgs = TPGS_MODE_NONE;
307 break;
308 }
309
310 return tpgs;
311 }
312
313 /*
314 * alua_check_vpd - Evaluate INQUIRY vpd page 0x83
315 * @sdev: device to be checked
316 *
317 * Extract the relative target port and the target port group
318 * descriptor from the list of identificators.
319 */
alua_check_vpd(struct scsi_device * sdev,struct alua_dh_data * h,int tpgs)320 static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h,
321 int tpgs)
322 {
323 int rel_port = -1, group_id;
324 struct alua_port_group *pg, *old_pg = NULL;
325 bool pg_updated = false;
326 unsigned long flags;
327
328 group_id = scsi_vpd_tpg_id(sdev, &rel_port);
329 if (group_id < 0) {
330 /*
331 * Internal error; TPGS supported but required
332 * VPD identification descriptors not present.
333 * Disable ALUA support
334 */
335 sdev_printk(KERN_INFO, sdev,
336 "%s: No target port descriptors found\n",
337 ALUA_DH_NAME);
338 return SCSI_DH_DEV_UNSUPP;
339 }
340
341 pg = alua_alloc_pg(sdev, group_id, tpgs);
342 if (IS_ERR(pg)) {
343 if (PTR_ERR(pg) == -ENOMEM)
344 return SCSI_DH_NOMEM;
345 return SCSI_DH_DEV_UNSUPP;
346 }
347 if (pg->device_id_len)
348 sdev_printk(KERN_INFO, sdev,
349 "%s: device %s port group %x rel port %x\n",
350 ALUA_DH_NAME, pg->device_id_str,
351 group_id, rel_port);
352 else
353 sdev_printk(KERN_INFO, sdev,
354 "%s: port group %x rel port %x\n",
355 ALUA_DH_NAME, group_id, rel_port);
356
357 /* Check for existing port group references */
358 spin_lock(&h->pg_lock);
359 old_pg = rcu_dereference_protected(h->pg, lockdep_is_held(&h->pg_lock));
360 if (old_pg != pg) {
361 /* port group has changed. Update to new port group */
362 if (h->pg) {
363 spin_lock_irqsave(&old_pg->lock, flags);
364 list_del_rcu(&h->node);
365 spin_unlock_irqrestore(&old_pg->lock, flags);
366 }
367 rcu_assign_pointer(h->pg, pg);
368 pg_updated = true;
369 }
370
371 spin_lock_irqsave(&pg->lock, flags);
372 if (pg_updated)
373 list_add_rcu(&h->node, &pg->dh_list);
374 spin_unlock_irqrestore(&pg->lock, flags);
375
376 alua_rtpg_queue(rcu_dereference_protected(h->pg,
377 lockdep_is_held(&h->pg_lock)),
378 sdev, NULL, true);
379 spin_unlock(&h->pg_lock);
380
381 if (old_pg)
382 kref_put(&old_pg->kref, release_port_group);
383
384 return SCSI_DH_OK;
385 }
386
print_alua_state(unsigned char state)387 static char print_alua_state(unsigned char state)
388 {
389 switch (state) {
390 case SCSI_ACCESS_STATE_OPTIMAL:
391 return 'A';
392 case SCSI_ACCESS_STATE_ACTIVE:
393 return 'N';
394 case SCSI_ACCESS_STATE_STANDBY:
395 return 'S';
396 case SCSI_ACCESS_STATE_UNAVAILABLE:
397 return 'U';
398 case SCSI_ACCESS_STATE_LBA:
399 return 'L';
400 case SCSI_ACCESS_STATE_OFFLINE:
401 return 'O';
402 case SCSI_ACCESS_STATE_TRANSITIONING:
403 return 'T';
404 default:
405 return 'X';
406 }
407 }
408
alua_check_sense(struct scsi_device * sdev,struct scsi_sense_hdr * sense_hdr)409 static enum scsi_disposition alua_check_sense(struct scsi_device *sdev,
410 struct scsi_sense_hdr *sense_hdr)
411 {
412 struct alua_dh_data *h = sdev->handler_data;
413 struct alua_port_group *pg;
414
415 switch (sense_hdr->sense_key) {
416 case NOT_READY:
417 if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0a) {
418 /*
419 * LUN Not Accessible - ALUA state transition
420 */
421 rcu_read_lock();
422 pg = rcu_dereference(h->pg);
423 if (pg)
424 pg->state = SCSI_ACCESS_STATE_TRANSITIONING;
425 rcu_read_unlock();
426 alua_check(sdev, false);
427 return NEEDS_RETRY;
428 }
429 break;
430 case UNIT_ATTENTION:
431 if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00) {
432 /*
433 * Power On, Reset, or Bus Device Reset.
434 * Might have obscured a state transition,
435 * so schedule a recheck.
436 */
437 alua_check(sdev, true);
438 return ADD_TO_MLQUEUE;
439 }
440 if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x04)
441 /*
442 * Device internal reset
443 */
444 return ADD_TO_MLQUEUE;
445 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x01)
446 /*
447 * Mode Parameters Changed
448 */
449 return ADD_TO_MLQUEUE;
450 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x06) {
451 /*
452 * ALUA state changed
453 */
454 alua_check(sdev, true);
455 return ADD_TO_MLQUEUE;
456 }
457 if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x07) {
458 /*
459 * Implicit ALUA state transition failed
460 */
461 alua_check(sdev, true);
462 return ADD_TO_MLQUEUE;
463 }
464 if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x03)
465 /*
466 * Inquiry data has changed
467 */
468 return ADD_TO_MLQUEUE;
469 if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x0e)
470 /*
471 * REPORTED_LUNS_DATA_HAS_CHANGED is reported
472 * when switching controllers on targets like
473 * Intel Multi-Flex. We can just retry.
474 */
475 return ADD_TO_MLQUEUE;
476 break;
477 }
478
479 return SCSI_RETURN_NOT_HANDLED;
480 }
481
482 /*
483 * alua_tur - Send a TEST UNIT READY
484 * @sdev: device to which the TEST UNIT READY command should be send
485 *
486 * Send a TEST UNIT READY to @sdev to figure out the device state
487 * Returns SCSI_DH_RETRY if the sense code is NOT READY/ALUA TRANSITIONING,
488 * SCSI_DH_OK if no error occurred, and SCSI_DH_IO otherwise.
489 */
alua_tur(struct scsi_device * sdev)490 static int alua_tur(struct scsi_device *sdev)
491 {
492 struct scsi_sense_hdr sense_hdr;
493 int retval;
494
495 retval = scsi_test_unit_ready(sdev, ALUA_FAILOVER_TIMEOUT * HZ,
496 ALUA_FAILOVER_RETRIES, &sense_hdr);
497 if (sense_hdr.sense_key == NOT_READY &&
498 sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a)
499 return SCSI_DH_RETRY;
500 else if (retval)
501 return SCSI_DH_IO;
502 else
503 return SCSI_DH_OK;
504 }
505
506 /*
507 * alua_rtpg - Evaluate REPORT TARGET GROUP STATES
508 * @sdev: the device to be evaluated.
509 *
510 * Evaluate the Target Port Group State.
511 * Returns SCSI_DH_DEV_OFFLINED if the path is
512 * found to be unusable.
513 */
alua_rtpg(struct scsi_device * sdev,struct alua_port_group * pg)514 static int alua_rtpg(struct scsi_device *sdev, struct alua_port_group *pg)
515 {
516 struct scsi_sense_hdr sense_hdr;
517 struct alua_port_group *tmp_pg;
518 int len, k, off, bufflen = ALUA_RTPG_SIZE;
519 int group_id_old, state_old, pref_old, valid_states_old;
520 unsigned char *desc, *buff;
521 unsigned err;
522 int retval;
523 unsigned int tpg_desc_tbl_off;
524 unsigned char orig_transition_tmo;
525 unsigned long flags;
526 bool transitioning_sense = false;
527
528 group_id_old = pg->group_id;
529 state_old = pg->state;
530 pref_old = pg->pref;
531 valid_states_old = pg->valid_states;
532
533 if (!pg->expiry) {
534 unsigned long transition_tmo = ALUA_FAILOVER_TIMEOUT * HZ;
535
536 if (pg->transition_tmo)
537 transition_tmo = pg->transition_tmo * HZ;
538
539 pg->expiry = round_jiffies_up(jiffies + transition_tmo);
540 }
541
542 buff = kzalloc(bufflen, GFP_KERNEL);
543 if (!buff)
544 return SCSI_DH_DEV_TEMP_BUSY;
545
546 retry:
547 err = 0;
548 retval = submit_rtpg(sdev, buff, bufflen, &sense_hdr, pg->flags);
549
550 if (retval) {
551 /*
552 * Some (broken) implementations have a habit of returning
553 * an error during things like firmware update etc.
554 * But if the target only supports active/optimized there's
555 * not much we can do; it's not that we can switch paths
556 * or anything.
557 * So ignore any errors to avoid spurious failures during
558 * path failover.
559 */
560 if ((pg->valid_states & ~TPGS_SUPPORT_OPTIMIZED) == 0) {
561 sdev_printk(KERN_INFO, sdev,
562 "%s: ignoring rtpg result %d\n",
563 ALUA_DH_NAME, retval);
564 kfree(buff);
565 return SCSI_DH_OK;
566 }
567 if (retval < 0 || !scsi_sense_valid(&sense_hdr)) {
568 sdev_printk(KERN_INFO, sdev,
569 "%s: rtpg failed, result %d\n",
570 ALUA_DH_NAME, retval);
571 kfree(buff);
572 if (retval < 0)
573 return SCSI_DH_DEV_TEMP_BUSY;
574 if (host_byte(retval) == DID_NO_CONNECT)
575 return SCSI_DH_RES_TEMP_UNAVAIL;
576 return SCSI_DH_IO;
577 }
578
579 /*
580 * submit_rtpg() has failed on existing arrays
581 * when requesting extended header info, and
582 * the array doesn't support extended headers,
583 * even though it shouldn't according to T10.
584 * The retry without rtpg_ext_hdr_req set
585 * handles this.
586 * Note: some arrays return a sense key of ILLEGAL_REQUEST
587 * with ASC 00h if they don't support the extended header.
588 */
589 if (!(pg->flags & ALUA_RTPG_EXT_HDR_UNSUPP) &&
590 sense_hdr.sense_key == ILLEGAL_REQUEST) {
591 pg->flags |= ALUA_RTPG_EXT_HDR_UNSUPP;
592 goto retry;
593 }
594 /*
595 * If the array returns with 'ALUA state transition'
596 * sense code here it cannot return RTPG data during
597 * transition. So set the state to 'transitioning' directly.
598 */
599 if (sense_hdr.sense_key == NOT_READY &&
600 sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a) {
601 transitioning_sense = true;
602 goto skip_rtpg;
603 }
604 /*
605 * Retry on any other UNIT ATTENTION occurred.
606 */
607 if (sense_hdr.sense_key == UNIT_ATTENTION)
608 err = SCSI_DH_RETRY;
609 if (err == SCSI_DH_RETRY &&
610 pg->expiry != 0 && time_before(jiffies, pg->expiry)) {
611 sdev_printk(KERN_ERR, sdev, "%s: rtpg retry\n",
612 ALUA_DH_NAME);
613 scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
614 kfree(buff);
615 return err;
616 }
617 sdev_printk(KERN_ERR, sdev, "%s: rtpg failed\n",
618 ALUA_DH_NAME);
619 scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
620 kfree(buff);
621 pg->expiry = 0;
622 return SCSI_DH_IO;
623 }
624
625 len = get_unaligned_be32(&buff[0]) + 4;
626
627 if (len > bufflen) {
628 /* Resubmit with the correct length */
629 kfree(buff);
630 bufflen = len;
631 buff = kmalloc(bufflen, GFP_KERNEL);
632 if (!buff) {
633 sdev_printk(KERN_WARNING, sdev,
634 "%s: kmalloc buffer failed\n",__func__);
635 /* Temporary failure, bypass */
636 pg->expiry = 0;
637 return SCSI_DH_DEV_TEMP_BUSY;
638 }
639 goto retry;
640 }
641
642 orig_transition_tmo = pg->transition_tmo;
643 if ((buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR && buff[5] != 0)
644 pg->transition_tmo = buff[5];
645 else
646 pg->transition_tmo = ALUA_FAILOVER_TIMEOUT;
647
648 if (orig_transition_tmo != pg->transition_tmo) {
649 sdev_printk(KERN_INFO, sdev,
650 "%s: transition timeout set to %d seconds\n",
651 ALUA_DH_NAME, pg->transition_tmo);
652 pg->expiry = jiffies + pg->transition_tmo * HZ;
653 }
654
655 if ((buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR)
656 tpg_desc_tbl_off = 8;
657 else
658 tpg_desc_tbl_off = 4;
659
660 for (k = tpg_desc_tbl_off, desc = buff + tpg_desc_tbl_off;
661 k < len;
662 k += off, desc += off) {
663 u16 group_id = get_unaligned_be16(&desc[2]);
664
665 spin_lock_irqsave(&port_group_lock, flags);
666 tmp_pg = alua_find_get_pg(pg->device_id_str, pg->device_id_len,
667 group_id);
668 spin_unlock_irqrestore(&port_group_lock, flags);
669 if (tmp_pg) {
670 if (spin_trylock_irqsave(&tmp_pg->lock, flags)) {
671 if ((tmp_pg == pg) ||
672 !(tmp_pg->flags & ALUA_PG_RUNNING)) {
673 struct alua_dh_data *h;
674
675 tmp_pg->state = desc[0] & 0x0f;
676 tmp_pg->pref = desc[0] >> 7;
677 rcu_read_lock();
678 list_for_each_entry_rcu(h,
679 &tmp_pg->dh_list, node) {
680 if (!h->sdev)
681 continue;
682 h->sdev->access_state = desc[0];
683 }
684 rcu_read_unlock();
685 }
686 if (tmp_pg == pg)
687 tmp_pg->valid_states = desc[1];
688 spin_unlock_irqrestore(&tmp_pg->lock, flags);
689 }
690 kref_put(&tmp_pg->kref, release_port_group);
691 }
692 off = 8 + (desc[7] * 4);
693 }
694
695 skip_rtpg:
696 spin_lock_irqsave(&pg->lock, flags);
697 if (transitioning_sense)
698 pg->state = SCSI_ACCESS_STATE_TRANSITIONING;
699
700 if (group_id_old != pg->group_id || state_old != pg->state ||
701 pref_old != pg->pref || valid_states_old != pg->valid_states)
702 sdev_printk(KERN_INFO, sdev,
703 "%s: port group %02x state %c %s supports %c%c%c%c%c%c%c\n",
704 ALUA_DH_NAME, pg->group_id, print_alua_state(pg->state),
705 pg->pref ? "preferred" : "non-preferred",
706 pg->valid_states&TPGS_SUPPORT_TRANSITION?'T':'t',
707 pg->valid_states&TPGS_SUPPORT_OFFLINE?'O':'o',
708 pg->valid_states&TPGS_SUPPORT_LBA_DEPENDENT?'L':'l',
709 pg->valid_states&TPGS_SUPPORT_UNAVAILABLE?'U':'u',
710 pg->valid_states&TPGS_SUPPORT_STANDBY?'S':'s',
711 pg->valid_states&TPGS_SUPPORT_NONOPTIMIZED?'N':'n',
712 pg->valid_states&TPGS_SUPPORT_OPTIMIZED?'A':'a');
713
714 switch (pg->state) {
715 case SCSI_ACCESS_STATE_TRANSITIONING:
716 if (time_before(jiffies, pg->expiry)) {
717 /* State transition, retry */
718 pg->interval = ALUA_RTPG_RETRY_DELAY;
719 err = SCSI_DH_RETRY;
720 } else {
721 struct alua_dh_data *h;
722
723 /* Transitioning time exceeded, set port to standby */
724 err = SCSI_DH_IO;
725 pg->state = SCSI_ACCESS_STATE_STANDBY;
726 pg->expiry = 0;
727 rcu_read_lock();
728 list_for_each_entry_rcu(h, &pg->dh_list, node) {
729 if (!h->sdev)
730 continue;
731 h->sdev->access_state =
732 (pg->state & SCSI_ACCESS_STATE_MASK);
733 if (pg->pref)
734 h->sdev->access_state |=
735 SCSI_ACCESS_STATE_PREFERRED;
736 }
737 rcu_read_unlock();
738 }
739 break;
740 case SCSI_ACCESS_STATE_OFFLINE:
741 /* Path unusable */
742 err = SCSI_DH_DEV_OFFLINED;
743 pg->expiry = 0;
744 break;
745 default:
746 /* Useable path if active */
747 err = SCSI_DH_OK;
748 pg->expiry = 0;
749 break;
750 }
751 spin_unlock_irqrestore(&pg->lock, flags);
752 kfree(buff);
753 return err;
754 }
755
756 /*
757 * alua_stpg - Issue a SET TARGET PORT GROUP command
758 *
759 * Issue a SET TARGET PORT GROUP command and evaluate the
760 * response. Returns SCSI_DH_RETRY per default to trigger
761 * a re-evaluation of the target group state or SCSI_DH_OK
762 * if no further action needs to be taken.
763 */
alua_stpg(struct scsi_device * sdev,struct alua_port_group * pg)764 static unsigned alua_stpg(struct scsi_device *sdev, struct alua_port_group *pg)
765 {
766 int retval;
767 struct scsi_sense_hdr sense_hdr;
768
769 if (!(pg->tpgs & TPGS_MODE_EXPLICIT)) {
770 /* Only implicit ALUA supported, retry */
771 return SCSI_DH_RETRY;
772 }
773 switch (pg->state) {
774 case SCSI_ACCESS_STATE_OPTIMAL:
775 return SCSI_DH_OK;
776 case SCSI_ACCESS_STATE_ACTIVE:
777 if ((pg->flags & ALUA_OPTIMIZE_STPG) &&
778 !pg->pref &&
779 (pg->tpgs & TPGS_MODE_IMPLICIT))
780 return SCSI_DH_OK;
781 break;
782 case SCSI_ACCESS_STATE_STANDBY:
783 case SCSI_ACCESS_STATE_UNAVAILABLE:
784 break;
785 case SCSI_ACCESS_STATE_OFFLINE:
786 return SCSI_DH_IO;
787 case SCSI_ACCESS_STATE_TRANSITIONING:
788 break;
789 default:
790 sdev_printk(KERN_INFO, sdev,
791 "%s: stpg failed, unhandled TPGS state %d",
792 ALUA_DH_NAME, pg->state);
793 return SCSI_DH_NOSYS;
794 }
795 retval = submit_stpg(sdev, pg->group_id, &sense_hdr);
796
797 if (retval) {
798 if (retval < 0 || !scsi_sense_valid(&sense_hdr)) {
799 sdev_printk(KERN_INFO, sdev,
800 "%s: stpg failed, result %d",
801 ALUA_DH_NAME, retval);
802 if (retval < 0)
803 return SCSI_DH_DEV_TEMP_BUSY;
804 } else {
805 sdev_printk(KERN_INFO, sdev, "%s: stpg failed\n",
806 ALUA_DH_NAME);
807 scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr);
808 }
809 }
810 /* Retry RTPG */
811 return SCSI_DH_RETRY;
812 }
813
alua_rtpg_select_sdev(struct alua_port_group * pg)814 static bool alua_rtpg_select_sdev(struct alua_port_group *pg)
815 {
816 struct alua_dh_data *h;
817 struct scsi_device *sdev = NULL;
818
819 lockdep_assert_held(&pg->lock);
820 if (WARN_ON(!pg->rtpg_sdev))
821 return false;
822
823 /*
824 * RCU protection isn't necessary for dh_list here
825 * as we hold pg->lock, but for access to h->pg.
826 */
827 rcu_read_lock();
828 list_for_each_entry_rcu(h, &pg->dh_list, node) {
829 if (!h->sdev)
830 continue;
831 if (h->sdev == pg->rtpg_sdev) {
832 h->disabled = true;
833 continue;
834 }
835 if (rcu_dereference(h->pg) == pg &&
836 !h->disabled &&
837 !scsi_device_get(h->sdev)) {
838 sdev = h->sdev;
839 break;
840 }
841 }
842 rcu_read_unlock();
843
844 if (!sdev) {
845 pr_warn("%s: no device found for rtpg\n",
846 (pg->device_id_len ?
847 (char *)pg->device_id_str : "(nameless PG)"));
848 return false;
849 }
850
851 sdev_printk(KERN_INFO, sdev, "rtpg retry on different device\n");
852
853 scsi_device_put(pg->rtpg_sdev);
854 pg->rtpg_sdev = sdev;
855
856 return true;
857 }
858
alua_rtpg_work(struct work_struct * work)859 static void alua_rtpg_work(struct work_struct *work)
860 {
861 struct alua_port_group *pg =
862 container_of(work, struct alua_port_group, rtpg_work.work);
863 struct scsi_device *sdev;
864 LIST_HEAD(qdata_list);
865 int err = SCSI_DH_OK;
866 struct alua_queue_data *qdata, *tmp;
867 struct alua_dh_data *h;
868 unsigned long flags;
869
870 spin_lock_irqsave(&pg->lock, flags);
871 sdev = pg->rtpg_sdev;
872 if (!sdev) {
873 WARN_ON(pg->flags & ALUA_PG_RUN_RTPG);
874 WARN_ON(pg->flags & ALUA_PG_RUN_STPG);
875 spin_unlock_irqrestore(&pg->lock, flags);
876 kref_put(&pg->kref, release_port_group);
877 return;
878 }
879 pg->flags |= ALUA_PG_RUNNING;
880 if (pg->flags & ALUA_PG_RUN_RTPG) {
881 int state = pg->state;
882
883 pg->flags &= ~ALUA_PG_RUN_RTPG;
884 spin_unlock_irqrestore(&pg->lock, flags);
885 if (state == SCSI_ACCESS_STATE_TRANSITIONING) {
886 if (alua_tur(sdev) == SCSI_DH_RETRY) {
887 spin_lock_irqsave(&pg->lock, flags);
888 pg->flags &= ~ALUA_PG_RUNNING;
889 pg->flags |= ALUA_PG_RUN_RTPG;
890 if (!pg->interval)
891 pg->interval = ALUA_RTPG_RETRY_DELAY;
892 spin_unlock_irqrestore(&pg->lock, flags);
893 queue_delayed_work(kaluad_wq, &pg->rtpg_work,
894 pg->interval * HZ);
895 return;
896 }
897 /* Send RTPG on failure or if TUR indicates SUCCESS */
898 }
899 err = alua_rtpg(sdev, pg);
900 spin_lock_irqsave(&pg->lock, flags);
901
902 /* If RTPG failed on the current device, try using another */
903 if (err == SCSI_DH_RES_TEMP_UNAVAIL &&
904 alua_rtpg_select_sdev(pg))
905 err = SCSI_DH_IMM_RETRY;
906
907 if (err == SCSI_DH_RETRY || err == SCSI_DH_IMM_RETRY ||
908 pg->flags & ALUA_PG_RUN_RTPG) {
909 pg->flags &= ~ALUA_PG_RUNNING;
910 if (err == SCSI_DH_IMM_RETRY)
911 pg->interval = 0;
912 else if (!pg->interval && !(pg->flags & ALUA_PG_RUN_RTPG))
913 pg->interval = ALUA_RTPG_RETRY_DELAY;
914 pg->flags |= ALUA_PG_RUN_RTPG;
915 spin_unlock_irqrestore(&pg->lock, flags);
916 queue_delayed_work(kaluad_wq, &pg->rtpg_work,
917 pg->interval * HZ);
918 return;
919 }
920 if (err != SCSI_DH_OK)
921 pg->flags &= ~ALUA_PG_RUN_STPG;
922 }
923 if (pg->flags & ALUA_PG_RUN_STPG) {
924 pg->flags &= ~ALUA_PG_RUN_STPG;
925 spin_unlock_irqrestore(&pg->lock, flags);
926 err = alua_stpg(sdev, pg);
927 spin_lock_irqsave(&pg->lock, flags);
928 if (err == SCSI_DH_RETRY || pg->flags & ALUA_PG_RUN_RTPG) {
929 pg->flags |= ALUA_PG_RUN_RTPG;
930 pg->interval = 0;
931 pg->flags &= ~ALUA_PG_RUNNING;
932 spin_unlock_irqrestore(&pg->lock, flags);
933 queue_delayed_work(kaluad_wq, &pg->rtpg_work,
934 pg->interval * HZ);
935 return;
936 }
937 }
938
939 list_splice_init(&pg->rtpg_list, &qdata_list);
940 /*
941 * We went through an RTPG, for good or bad.
942 * Re-enable all devices for the next attempt.
943 */
944 list_for_each_entry(h, &pg->dh_list, node)
945 h->disabled = false;
946 pg->rtpg_sdev = NULL;
947 spin_unlock_irqrestore(&pg->lock, flags);
948
949 list_for_each_entry_safe(qdata, tmp, &qdata_list, entry) {
950 list_del(&qdata->entry);
951 if (qdata->callback_fn)
952 qdata->callback_fn(qdata->callback_data, err);
953 kfree(qdata);
954 }
955 spin_lock_irqsave(&pg->lock, flags);
956 pg->flags &= ~ALUA_PG_RUNNING;
957 spin_unlock_irqrestore(&pg->lock, flags);
958 scsi_device_put(sdev);
959 kref_put(&pg->kref, release_port_group);
960 }
961
962 /**
963 * alua_rtpg_queue() - cause RTPG to be submitted asynchronously
964 * @pg: ALUA port group associated with @sdev.
965 * @sdev: SCSI device for which to submit an RTPG.
966 * @qdata: Information about the callback to invoke after the RTPG.
967 * @force: Whether or not to submit an RTPG if a work item that will submit an
968 * RTPG already has been scheduled.
969 *
970 * Returns true if and only if alua_rtpg_work() will be called asynchronously.
971 * That function is responsible for calling @qdata->fn().
972 */
alua_rtpg_queue(struct alua_port_group * pg,struct scsi_device * sdev,struct alua_queue_data * qdata,bool force)973 static bool alua_rtpg_queue(struct alua_port_group *pg,
974 struct scsi_device *sdev,
975 struct alua_queue_data *qdata, bool force)
976 {
977 int start_queue = 0;
978 unsigned long flags;
979 if (WARN_ON_ONCE(!pg) || scsi_device_get(sdev))
980 return false;
981
982 spin_lock_irqsave(&pg->lock, flags);
983 if (qdata) {
984 list_add_tail(&qdata->entry, &pg->rtpg_list);
985 pg->flags |= ALUA_PG_RUN_STPG;
986 force = true;
987 }
988 if (pg->rtpg_sdev == NULL) {
989 pg->interval = 0;
990 pg->flags |= ALUA_PG_RUN_RTPG;
991 kref_get(&pg->kref);
992 pg->rtpg_sdev = sdev;
993 start_queue = 1;
994 } else if (!(pg->flags & ALUA_PG_RUN_RTPG) && force) {
995 pg->flags |= ALUA_PG_RUN_RTPG;
996 /* Do not queue if the worker is already running */
997 if (!(pg->flags & ALUA_PG_RUNNING)) {
998 kref_get(&pg->kref);
999 start_queue = 1;
1000 }
1001 }
1002
1003 spin_unlock_irqrestore(&pg->lock, flags);
1004
1005 if (start_queue) {
1006 if (queue_delayed_work(kaluad_wq, &pg->rtpg_work,
1007 msecs_to_jiffies(ALUA_RTPG_DELAY_MSECS)))
1008 sdev = NULL;
1009 else
1010 kref_put(&pg->kref, release_port_group);
1011 }
1012 if (sdev)
1013 scsi_device_put(sdev);
1014
1015 return true;
1016 }
1017
1018 /*
1019 * alua_initialize - Initialize ALUA state
1020 * @sdev: the device to be initialized
1021 *
1022 * For the prep_fn to work correctly we have
1023 * to initialize the ALUA state for the device.
1024 */
alua_initialize(struct scsi_device * sdev,struct alua_dh_data * h)1025 static int alua_initialize(struct scsi_device *sdev, struct alua_dh_data *h)
1026 {
1027 int err = SCSI_DH_DEV_UNSUPP, tpgs;
1028
1029 mutex_lock(&h->init_mutex);
1030 h->disabled = false;
1031 tpgs = alua_check_tpgs(sdev);
1032 if (tpgs != TPGS_MODE_NONE)
1033 err = alua_check_vpd(sdev, h, tpgs);
1034 h->init_error = err;
1035 mutex_unlock(&h->init_mutex);
1036 return err;
1037 }
1038 /*
1039 * alua_set_params - set/unset the optimize flag
1040 * @sdev: device on the path to be activated
1041 * params - parameters in the following format
1042 * "no_of_params\0param1\0param2\0param3\0...\0"
1043 * For example, to set the flag pass the following parameters
1044 * from multipath.conf
1045 * hardware_handler "2 alua 1"
1046 */
alua_set_params(struct scsi_device * sdev,const char * params)1047 static int alua_set_params(struct scsi_device *sdev, const char *params)
1048 {
1049 struct alua_dh_data *h = sdev->handler_data;
1050 struct alua_port_group *pg = NULL;
1051 unsigned int optimize = 0, argc;
1052 const char *p = params;
1053 int result = SCSI_DH_OK;
1054 unsigned long flags;
1055
1056 if ((sscanf(params, "%u", &argc) != 1) || (argc != 1))
1057 return -EINVAL;
1058
1059 while (*p++)
1060 ;
1061 if ((sscanf(p, "%u", &optimize) != 1) || (optimize > 1))
1062 return -EINVAL;
1063
1064 rcu_read_lock();
1065 pg = rcu_dereference(h->pg);
1066 if (!pg) {
1067 rcu_read_unlock();
1068 return -ENXIO;
1069 }
1070 spin_lock_irqsave(&pg->lock, flags);
1071 if (optimize)
1072 pg->flags |= ALUA_OPTIMIZE_STPG;
1073 else
1074 pg->flags &= ~ALUA_OPTIMIZE_STPG;
1075 spin_unlock_irqrestore(&pg->lock, flags);
1076 rcu_read_unlock();
1077
1078 return result;
1079 }
1080
1081 /*
1082 * alua_activate - activate a path
1083 * @sdev: device on the path to be activated
1084 *
1085 * We're currently switching the port group to be activated only and
1086 * let the array figure out the rest.
1087 * There may be other arrays which require us to switch all port groups
1088 * based on a certain policy. But until we actually encounter them it
1089 * should be okay.
1090 */
alua_activate(struct scsi_device * sdev,activate_complete fn,void * data)1091 static int alua_activate(struct scsi_device *sdev,
1092 activate_complete fn, void *data)
1093 {
1094 struct alua_dh_data *h = sdev->handler_data;
1095 int err = SCSI_DH_OK;
1096 struct alua_queue_data *qdata;
1097 struct alua_port_group *pg;
1098
1099 qdata = kzalloc(sizeof(*qdata), GFP_KERNEL);
1100 if (!qdata) {
1101 err = SCSI_DH_RES_TEMP_UNAVAIL;
1102 goto out;
1103 }
1104 qdata->callback_fn = fn;
1105 qdata->callback_data = data;
1106
1107 mutex_lock(&h->init_mutex);
1108 rcu_read_lock();
1109 pg = rcu_dereference(h->pg);
1110 if (!pg || !kref_get_unless_zero(&pg->kref)) {
1111 rcu_read_unlock();
1112 kfree(qdata);
1113 err = h->init_error;
1114 mutex_unlock(&h->init_mutex);
1115 goto out;
1116 }
1117 rcu_read_unlock();
1118 mutex_unlock(&h->init_mutex);
1119
1120 if (alua_rtpg_queue(pg, sdev, qdata, true))
1121 fn = NULL;
1122 else
1123 err = SCSI_DH_DEV_OFFLINED;
1124 kref_put(&pg->kref, release_port_group);
1125 out:
1126 if (fn)
1127 fn(data, err);
1128 return 0;
1129 }
1130
1131 /*
1132 * alua_check - check path status
1133 * @sdev: device on the path to be checked
1134 *
1135 * Check the device status
1136 */
alua_check(struct scsi_device * sdev,bool force)1137 static void alua_check(struct scsi_device *sdev, bool force)
1138 {
1139 struct alua_dh_data *h = sdev->handler_data;
1140 struct alua_port_group *pg;
1141
1142 rcu_read_lock();
1143 pg = rcu_dereference(h->pg);
1144 if (!pg || !kref_get_unless_zero(&pg->kref)) {
1145 rcu_read_unlock();
1146 return;
1147 }
1148 rcu_read_unlock();
1149 alua_rtpg_queue(pg, sdev, NULL, force);
1150 kref_put(&pg->kref, release_port_group);
1151 }
1152
1153 /*
1154 * alua_prep_fn - request callback
1155 *
1156 * Fail I/O to all paths not in state
1157 * active/optimized or active/non-optimized.
1158 */
alua_prep_fn(struct scsi_device * sdev,struct request * req)1159 static blk_status_t alua_prep_fn(struct scsi_device *sdev, struct request *req)
1160 {
1161 struct alua_dh_data *h = sdev->handler_data;
1162 struct alua_port_group *pg;
1163 unsigned char state = SCSI_ACCESS_STATE_OPTIMAL;
1164
1165 rcu_read_lock();
1166 pg = rcu_dereference(h->pg);
1167 if (pg)
1168 state = pg->state;
1169 rcu_read_unlock();
1170
1171 switch (state) {
1172 case SCSI_ACCESS_STATE_OPTIMAL:
1173 case SCSI_ACCESS_STATE_ACTIVE:
1174 case SCSI_ACCESS_STATE_LBA:
1175 case SCSI_ACCESS_STATE_TRANSITIONING:
1176 return BLK_STS_OK;
1177 default:
1178 req->rq_flags |= RQF_QUIET;
1179 return BLK_STS_IOERR;
1180 }
1181 }
1182
alua_rescan(struct scsi_device * sdev)1183 static void alua_rescan(struct scsi_device *sdev)
1184 {
1185 struct alua_dh_data *h = sdev->handler_data;
1186
1187 alua_initialize(sdev, h);
1188 }
1189
1190 /*
1191 * alua_bus_attach - Attach device handler
1192 * @sdev: device to be attached to
1193 */
alua_bus_attach(struct scsi_device * sdev)1194 static int alua_bus_attach(struct scsi_device *sdev)
1195 {
1196 struct alua_dh_data *h;
1197 int err;
1198
1199 h = kzalloc(sizeof(*h) , GFP_KERNEL);
1200 if (!h)
1201 return SCSI_DH_NOMEM;
1202 spin_lock_init(&h->pg_lock);
1203 rcu_assign_pointer(h->pg, NULL);
1204 h->init_error = SCSI_DH_OK;
1205 h->sdev = sdev;
1206 INIT_LIST_HEAD(&h->node);
1207
1208 mutex_init(&h->init_mutex);
1209 err = alua_initialize(sdev, h);
1210 if (err != SCSI_DH_OK && err != SCSI_DH_DEV_OFFLINED)
1211 goto failed;
1212
1213 sdev->handler_data = h;
1214 return SCSI_DH_OK;
1215 failed:
1216 kfree(h);
1217 return err;
1218 }
1219
1220 /*
1221 * alua_bus_detach - Detach device handler
1222 * @sdev: device to be detached from
1223 */
alua_bus_detach(struct scsi_device * sdev)1224 static void alua_bus_detach(struct scsi_device *sdev)
1225 {
1226 struct alua_dh_data *h = sdev->handler_data;
1227 struct alua_port_group *pg;
1228
1229 spin_lock(&h->pg_lock);
1230 pg = rcu_dereference_protected(h->pg, lockdep_is_held(&h->pg_lock));
1231 rcu_assign_pointer(h->pg, NULL);
1232 spin_unlock(&h->pg_lock);
1233 if (pg) {
1234 spin_lock_irq(&pg->lock);
1235 list_del_rcu(&h->node);
1236 spin_unlock_irq(&pg->lock);
1237 kref_put(&pg->kref, release_port_group);
1238 }
1239 sdev->handler_data = NULL;
1240 synchronize_rcu();
1241 kfree(h);
1242 }
1243
1244 static struct scsi_device_handler alua_dh = {
1245 .name = ALUA_DH_NAME,
1246 .module = THIS_MODULE,
1247 .attach = alua_bus_attach,
1248 .detach = alua_bus_detach,
1249 .prep_fn = alua_prep_fn,
1250 .check_sense = alua_check_sense,
1251 .activate = alua_activate,
1252 .rescan = alua_rescan,
1253 .set_params = alua_set_params,
1254 };
1255
alua_init(void)1256 static int __init alua_init(void)
1257 {
1258 int r;
1259
1260 kaluad_wq = alloc_workqueue("kaluad", WQ_MEM_RECLAIM, 0);
1261 if (!kaluad_wq)
1262 return -ENOMEM;
1263
1264 r = scsi_register_device_handler(&alua_dh);
1265 if (r != 0) {
1266 printk(KERN_ERR "%s: Failed to register scsi device handler",
1267 ALUA_DH_NAME);
1268 destroy_workqueue(kaluad_wq);
1269 }
1270 return r;
1271 }
1272
alua_exit(void)1273 static void __exit alua_exit(void)
1274 {
1275 scsi_unregister_device_handler(&alua_dh);
1276 destroy_workqueue(kaluad_wq);
1277 }
1278
1279 module_init(alua_init);
1280 module_exit(alua_exit);
1281
1282 MODULE_DESCRIPTION("DM Multipath ALUA support");
1283 MODULE_AUTHOR("Hannes Reinecke <hare@suse.de>");
1284 MODULE_LICENSE("GPL");
1285 MODULE_VERSION(ALUA_DH_VER);
1286