xref: /linux/drivers/scsi/hosts.c (revision 870b7fdc660b38c4e1bd8bf48e62aa352ddf8f42)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  hosts.c Copyright (C) 1992 Drew Eckhardt
4  *          Copyright (C) 1993, 1994, 1995 Eric Youngdale
5  *          Copyright (C) 2002-2003 Christoph Hellwig
6  *
7  *  mid to lowlevel SCSI driver interface
8  *      Initial versions: Drew Eckhardt
9  *      Subsequent revisions: Eric Youngdale
10  *
11  *  <drew@colorado.edu>
12  *
13  *  Jiffies wrap fixes (host->resetting), 3 Dec 1998 Andrea Arcangeli
14  *  Added QLOGIC QLA1280 SCSI controller kernel host support.
15  *     August 4, 1999 Fred Lewis, Intel DuPont
16  *
17  *  Updated to reflect the new initialization scheme for the higher
18  *  level of scsi drivers (sd/sr/st)
19  *  September 17, 2000 Torben Mathiasen <tmm@image.dk>
20  *
21  *  Restructured scsi_host lists and associated functions.
22  *  September 04, 2002 Mike Anderson (andmike@us.ibm.com)
23  */
24 
25 #include <linux/module.h>
26 #include <linux/blkdev.h>
27 #include <linux/kernel.h>
28 #include <linux/slab.h>
29 #include <linux/kthread.h>
30 #include <linux/string.h>
31 #include <linux/mm.h>
32 #include <linux/init.h>
33 #include <linux/completion.h>
34 #include <linux/transport_class.h>
35 #include <linux/platform_device.h>
36 #include <linux/pm_runtime.h>
37 #include <linux/idr.h>
38 #include <scsi/scsi_device.h>
39 #include <scsi/scsi_host.h>
40 #include <scsi/scsi_transport.h>
41 #include <scsi/scsi_cmnd.h>
42 
43 #include "scsi_priv.h"
44 #include "scsi_logging.h"
45 
46 
47 static int shost_eh_deadline = -1;
48 
49 module_param_named(eh_deadline, shost_eh_deadline, int, S_IRUGO|S_IWUSR);
50 MODULE_PARM_DESC(eh_deadline,
51 		 "SCSI EH timeout in seconds (should be between 0 and 2^31-1)");
52 
53 static DEFINE_IDA(host_index_ida);
54 
55 
56 static void scsi_host_cls_release(struct device *dev)
57 {
58 	put_device(&class_to_shost(dev)->shost_gendev);
59 }
60 
61 static struct class shost_class = {
62 	.name		= "scsi_host",
63 	.dev_release	= scsi_host_cls_release,
64 	.dev_groups	= scsi_shost_groups,
65 };
66 
67 /**
68  *	scsi_host_set_state - Take the given host through the host state model.
69  *	@shost:	scsi host to change the state of.
70  *	@state:	state to change to.
71  *
72  *	Returns zero if unsuccessful or an error if the requested
73  *	transition is illegal.
74  **/
75 int scsi_host_set_state(struct Scsi_Host *shost, enum scsi_host_state state)
76 {
77 	enum scsi_host_state oldstate = shost->shost_state;
78 
79 	if (state == oldstate)
80 		return 0;
81 
82 	switch (state) {
83 	case SHOST_CREATED:
84 		/* There are no legal states that come back to
85 		 * created.  This is the manually initialised start
86 		 * state */
87 		goto illegal;
88 
89 	case SHOST_RUNNING:
90 		switch (oldstate) {
91 		case SHOST_CREATED:
92 		case SHOST_RECOVERY:
93 			break;
94 		default:
95 			goto illegal;
96 		}
97 		break;
98 
99 	case SHOST_RECOVERY:
100 		switch (oldstate) {
101 		case SHOST_RUNNING:
102 			break;
103 		default:
104 			goto illegal;
105 		}
106 		break;
107 
108 	case SHOST_CANCEL:
109 		switch (oldstate) {
110 		case SHOST_CREATED:
111 		case SHOST_RUNNING:
112 		case SHOST_CANCEL_RECOVERY:
113 			break;
114 		default:
115 			goto illegal;
116 		}
117 		break;
118 
119 	case SHOST_DEL:
120 		switch (oldstate) {
121 		case SHOST_CANCEL:
122 		case SHOST_DEL_RECOVERY:
123 			break;
124 		default:
125 			goto illegal;
126 		}
127 		break;
128 
129 	case SHOST_CANCEL_RECOVERY:
130 		switch (oldstate) {
131 		case SHOST_CANCEL:
132 		case SHOST_RECOVERY:
133 			break;
134 		default:
135 			goto illegal;
136 		}
137 		break;
138 
139 	case SHOST_DEL_RECOVERY:
140 		switch (oldstate) {
141 		case SHOST_CANCEL_RECOVERY:
142 			break;
143 		default:
144 			goto illegal;
145 		}
146 		break;
147 	}
148 	shost->shost_state = state;
149 	return 0;
150 
151  illegal:
152 	SCSI_LOG_ERROR_RECOVERY(1,
153 				shost_printk(KERN_ERR, shost,
154 					     "Illegal host state transition"
155 					     "%s->%s\n",
156 					     scsi_host_state_name(oldstate),
157 					     scsi_host_state_name(state)));
158 	return -EINVAL;
159 }
160 
161 /**
162  * scsi_remove_host - remove a scsi host
163  * @shost:	a pointer to a scsi host to remove
164  **/
165 void scsi_remove_host(struct Scsi_Host *shost)
166 {
167 	unsigned long flags;
168 
169 	mutex_lock(&shost->scan_mutex);
170 	spin_lock_irqsave(shost->host_lock, flags);
171 	if (scsi_host_set_state(shost, SHOST_CANCEL))
172 		if (scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY)) {
173 			spin_unlock_irqrestore(shost->host_lock, flags);
174 			mutex_unlock(&shost->scan_mutex);
175 			return;
176 		}
177 	spin_unlock_irqrestore(shost->host_lock, flags);
178 
179 	scsi_autopm_get_host(shost);
180 	flush_workqueue(shost->tmf_work_q);
181 	scsi_forget_host(shost);
182 	mutex_unlock(&shost->scan_mutex);
183 	scsi_proc_host_rm(shost);
184 	scsi_proc_hostdir_rm(shost->hostt);
185 
186 	/*
187 	 * New SCSI devices cannot be attached anymore because of the SCSI host
188 	 * state so drop the tag set refcnt. Wait until the tag set refcnt drops
189 	 * to zero because .exit_cmd_priv implementations may need the host
190 	 * pointer.
191 	 */
192 	kref_put(&shost->tagset_refcnt, scsi_mq_free_tags);
193 	wait_for_completion(&shost->tagset_freed);
194 
195 	spin_lock_irqsave(shost->host_lock, flags);
196 	if (scsi_host_set_state(shost, SHOST_DEL))
197 		BUG_ON(scsi_host_set_state(shost, SHOST_DEL_RECOVERY));
198 	spin_unlock_irqrestore(shost->host_lock, flags);
199 
200 	transport_unregister_device(&shost->shost_gendev);
201 	device_unregister(&shost->shost_dev);
202 	device_del(&shost->shost_gendev);
203 }
204 EXPORT_SYMBOL(scsi_remove_host);
205 
206 /**
207  * scsi_add_host_with_dma - add a scsi host with dma device
208  * @shost:	scsi host pointer to add
209  * @dev:	a struct device of type scsi class
210  * @dma_dev:	dma device for the host
211  *
212  * Note: You rarely need to worry about this unless you're in a
213  * virtualised host environments, so use the simpler scsi_add_host()
214  * function instead.
215  *
216  * Return value:
217  * 	0 on success / != 0 for error
218  **/
219 int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev,
220 			   struct device *dma_dev)
221 {
222 	const struct scsi_host_template *sht = shost->hostt;
223 	int error = -EINVAL;
224 
225 	shost_printk(KERN_INFO, shost, "%s\n",
226 			sht->info ? sht->info(shost) : sht->name);
227 
228 	if (!shost->can_queue) {
229 		shost_printk(KERN_ERR, shost,
230 			     "can_queue = 0 no longer supported\n");
231 		goto fail;
232 	}
233 
234 	/* Use min_t(int, ...) in case shost->can_queue exceeds SHRT_MAX */
235 	shost->cmd_per_lun = min_t(int, shost->cmd_per_lun,
236 				   shost->can_queue);
237 
238 	error = scsi_init_sense_cache(shost);
239 	if (error)
240 		goto fail;
241 
242 	if (!shost->shost_gendev.parent)
243 		shost->shost_gendev.parent = dev ? dev : &platform_bus;
244 	if (!dma_dev)
245 		dma_dev = shost->shost_gendev.parent;
246 
247 	shost->dma_dev = dma_dev;
248 
249 	if (dma_dev->dma_mask) {
250 		shost->max_sectors = min_t(unsigned int, shost->max_sectors,
251 				dma_max_mapping_size(dma_dev) >> SECTOR_SHIFT);
252 	}
253 
254 	error = scsi_mq_setup_tags(shost);
255 	if (error)
256 		goto fail;
257 
258 	kref_init(&shost->tagset_refcnt);
259 	init_completion(&shost->tagset_freed);
260 
261 	/*
262 	 * Increase usage count temporarily here so that calling
263 	 * scsi_autopm_put_host() will trigger runtime idle if there is
264 	 * nothing else preventing suspending the device.
265 	 */
266 	pm_runtime_get_noresume(&shost->shost_gendev);
267 	pm_runtime_set_active(&shost->shost_gendev);
268 	pm_runtime_enable(&shost->shost_gendev);
269 	device_enable_async_suspend(&shost->shost_gendev);
270 
271 	error = device_add(&shost->shost_gendev);
272 	if (error)
273 		goto out_disable_runtime_pm;
274 
275 	scsi_host_set_state(shost, SHOST_RUNNING);
276 	get_device(shost->shost_gendev.parent);
277 
278 	device_enable_async_suspend(&shost->shost_dev);
279 
280 	get_device(&shost->shost_gendev);
281 	error = device_add(&shost->shost_dev);
282 	if (error)
283 		goto out_del_gendev;
284 
285 	if (shost->transportt->host_size) {
286 		shost->shost_data = kzalloc(shost->transportt->host_size,
287 					 GFP_KERNEL);
288 		if (shost->shost_data == NULL) {
289 			error = -ENOMEM;
290 			goto out_del_dev;
291 		}
292 	}
293 
294 	if (shost->transportt->create_work_queue) {
295 		shost->work_q = alloc_workqueue(
296 			"scsi_wq_%d",
297 			WQ_SYSFS | __WQ_LEGACY | WQ_MEM_RECLAIM | WQ_UNBOUND, 1,
298 			shost->host_no);
299 
300 		if (!shost->work_q) {
301 			error = -EINVAL;
302 			goto out_del_dev;
303 		}
304 	}
305 
306 	error = scsi_sysfs_add_host(shost);
307 	if (error)
308 		goto out_del_dev;
309 
310 	scsi_proc_host_add(shost);
311 	scsi_autopm_put_host(shost);
312 	return error;
313 
314 	/*
315 	 * Any host allocation in this function will be freed in
316 	 * scsi_host_dev_release().
317 	 */
318  out_del_dev:
319 	device_del(&shost->shost_dev);
320  out_del_gendev:
321 	/*
322 	 * Host state is SHOST_RUNNING so we have to explicitly release
323 	 * ->shost_dev.
324 	 */
325 	put_device(&shost->shost_dev);
326 	device_del(&shost->shost_gendev);
327  out_disable_runtime_pm:
328 	device_disable_async_suspend(&shost->shost_gendev);
329 	pm_runtime_disable(&shost->shost_gendev);
330 	pm_runtime_set_suspended(&shost->shost_gendev);
331 	pm_runtime_put_noidle(&shost->shost_gendev);
332 	kref_put(&shost->tagset_refcnt, scsi_mq_free_tags);
333  fail:
334 	return error;
335 }
336 EXPORT_SYMBOL(scsi_add_host_with_dma);
337 
338 static void scsi_host_dev_release(struct device *dev)
339 {
340 	struct Scsi_Host *shost = dev_to_shost(dev);
341 	struct device *parent = dev->parent;
342 
343 	/* Wait for functions invoked through call_rcu(&scmd->rcu, ...) */
344 	rcu_barrier();
345 
346 	if (shost->tmf_work_q)
347 		destroy_workqueue(shost->tmf_work_q);
348 	if (shost->ehandler)
349 		kthread_stop(shost->ehandler);
350 	if (shost->work_q)
351 		destroy_workqueue(shost->work_q);
352 
353 	if (shost->shost_state == SHOST_CREATED) {
354 		/*
355 		 * Free the shost_dev device name and remove the proc host dir
356 		 * here if scsi_host_{alloc,put}() have been called but neither
357 		 * scsi_host_add() nor scsi_remove_host() has been called.
358 		 * This avoids that the memory allocated for the shost_dev
359 		 * name as well as the proc dir structure are leaked.
360 		 */
361 		scsi_proc_hostdir_rm(shost->hostt);
362 		kfree(dev_name(&shost->shost_dev));
363 	}
364 
365 	kfree(shost->shost_data);
366 
367 	ida_free(&host_index_ida, shost->host_no);
368 
369 	if (shost->shost_state != SHOST_CREATED)
370 		put_device(parent);
371 	kfree(shost);
372 }
373 
374 static const struct device_type scsi_host_type = {
375 	.name =		"scsi_host",
376 	.release =	scsi_host_dev_release,
377 };
378 
379 /**
380  * scsi_host_alloc - register a scsi host adapter instance.
381  * @sht:	pointer to scsi host template
382  * @privsize:	extra bytes to allocate for driver
383  *
384  * Note:
385  * 	Allocate a new Scsi_Host and perform basic initialization.
386  * 	The host is not published to the scsi midlayer until scsi_add_host
387  * 	is called.
388  *
389  * Return value:
390  * 	Pointer to a new Scsi_Host
391  **/
392 struct Scsi_Host *scsi_host_alloc(const struct scsi_host_template *sht, int privsize)
393 {
394 	struct Scsi_Host *shost;
395 	int index;
396 
397 	shost = kzalloc(sizeof(struct Scsi_Host) + privsize, GFP_KERNEL);
398 	if (!shost)
399 		return NULL;
400 
401 	shost->host_lock = &shost->default_lock;
402 	spin_lock_init(shost->host_lock);
403 	shost->shost_state = SHOST_CREATED;
404 	INIT_LIST_HEAD(&shost->__devices);
405 	INIT_LIST_HEAD(&shost->__targets);
406 	INIT_LIST_HEAD(&shost->eh_abort_list);
407 	INIT_LIST_HEAD(&shost->eh_cmd_q);
408 	INIT_LIST_HEAD(&shost->starved_list);
409 	init_waitqueue_head(&shost->host_wait);
410 	mutex_init(&shost->scan_mutex);
411 
412 	index = ida_alloc(&host_index_ida, GFP_KERNEL);
413 	if (index < 0) {
414 		kfree(shost);
415 		return NULL;
416 	}
417 	shost->host_no = index;
418 
419 	shost->dma_channel = 0xff;
420 
421 	/* These three are default values which can be overridden */
422 	shost->max_channel = 0;
423 	shost->max_id = 8;
424 	shost->max_lun = 8;
425 
426 	/* Give each shost a default transportt */
427 	shost->transportt = &blank_transport_template;
428 
429 	/*
430 	 * All drivers right now should be able to handle 12 byte
431 	 * commands.  Every so often there are requests for 16 byte
432 	 * commands, but individual low-level drivers need to certify that
433 	 * they actually do something sensible with such commands.
434 	 */
435 	shost->max_cmd_len = 12;
436 	shost->hostt = sht;
437 	shost->this_id = sht->this_id;
438 	shost->can_queue = sht->can_queue;
439 	shost->sg_tablesize = sht->sg_tablesize;
440 	shost->sg_prot_tablesize = sht->sg_prot_tablesize;
441 	shost->cmd_per_lun = sht->cmd_per_lun;
442 	shost->no_write_same = sht->no_write_same;
443 	shost->host_tagset = sht->host_tagset;
444 	shost->queuecommand_may_block = sht->queuecommand_may_block;
445 
446 	if (shost_eh_deadline == -1 || !sht->eh_host_reset_handler)
447 		shost->eh_deadline = -1;
448 	else if ((ulong) shost_eh_deadline * HZ > INT_MAX) {
449 		shost_printk(KERN_WARNING, shost,
450 			     "eh_deadline %u too large, setting to %u\n",
451 			     shost_eh_deadline, INT_MAX / HZ);
452 		shost->eh_deadline = INT_MAX;
453 	} else
454 		shost->eh_deadline = shost_eh_deadline * HZ;
455 
456 	if (sht->supported_mode == MODE_UNKNOWN)
457 		/* means we didn't set it ... default to INITIATOR */
458 		shost->active_mode = MODE_INITIATOR;
459 	else
460 		shost->active_mode = sht->supported_mode;
461 
462 	if (sht->max_host_blocked)
463 		shost->max_host_blocked = sht->max_host_blocked;
464 	else
465 		shost->max_host_blocked = SCSI_DEFAULT_HOST_BLOCKED;
466 
467 	/*
468 	 * If the driver imposes no hard sector transfer limit, start at
469 	 * machine infinity initially.
470 	 */
471 	if (sht->max_sectors)
472 		shost->max_sectors = sht->max_sectors;
473 	else
474 		shost->max_sectors = SCSI_DEFAULT_MAX_SECTORS;
475 
476 	if (sht->max_segment_size)
477 		shost->max_segment_size = sht->max_segment_size;
478 	else
479 		shost->max_segment_size = BLK_MAX_SEGMENT_SIZE;
480 
481 	/* 32-byte (dword) is a common minimum for HBAs. */
482 	if (sht->dma_alignment)
483 		shost->dma_alignment = sht->dma_alignment;
484 	else
485 		shost->dma_alignment = 3;
486 
487 	/*
488 	 * assume a 4GB boundary, if not set
489 	 */
490 	if (sht->dma_boundary)
491 		shost->dma_boundary = sht->dma_boundary;
492 	else
493 		shost->dma_boundary = 0xffffffff;
494 
495 	if (sht->virt_boundary_mask)
496 		shost->virt_boundary_mask = sht->virt_boundary_mask;
497 
498 	device_initialize(&shost->shost_gendev);
499 	dev_set_name(&shost->shost_gendev, "host%d", shost->host_no);
500 	shost->shost_gendev.bus = &scsi_bus_type;
501 	shost->shost_gendev.type = &scsi_host_type;
502 	scsi_enable_async_suspend(&shost->shost_gendev);
503 
504 	device_initialize(&shost->shost_dev);
505 	shost->shost_dev.parent = &shost->shost_gendev;
506 	shost->shost_dev.class = &shost_class;
507 	dev_set_name(&shost->shost_dev, "host%d", shost->host_no);
508 	shost->shost_dev.groups = sht->shost_groups;
509 
510 	shost->ehandler = kthread_run(scsi_error_handler, shost,
511 			"scsi_eh_%d", shost->host_no);
512 	if (IS_ERR(shost->ehandler)) {
513 		shost_printk(KERN_WARNING, shost,
514 			"error handler thread failed to spawn, error = %ld\n",
515 			PTR_ERR(shost->ehandler));
516 		shost->ehandler = NULL;
517 		goto fail;
518 	}
519 
520 	shost->tmf_work_q = alloc_workqueue("scsi_tmf_%d",
521 					WQ_UNBOUND | WQ_MEM_RECLAIM | WQ_SYSFS,
522 					   1, shost->host_no);
523 	if (!shost->tmf_work_q) {
524 		shost_printk(KERN_WARNING, shost,
525 			     "failed to create tmf workq\n");
526 		goto fail;
527 	}
528 	if (scsi_proc_hostdir_add(shost->hostt) < 0)
529 		goto fail;
530 	return shost;
531  fail:
532 	/*
533 	 * Host state is still SHOST_CREATED and that is enough to release
534 	 * ->shost_gendev. scsi_host_dev_release() will free
535 	 * dev_name(&shost->shost_dev).
536 	 */
537 	put_device(&shost->shost_gendev);
538 
539 	return NULL;
540 }
541 EXPORT_SYMBOL(scsi_host_alloc);
542 
543 static int __scsi_host_match(struct device *dev, const void *data)
544 {
545 	struct Scsi_Host *p;
546 	const unsigned int *hostnum = data;
547 
548 	p = class_to_shost(dev);
549 	return p->host_no == *hostnum;
550 }
551 
552 /**
553  * scsi_host_lookup - get a reference to a Scsi_Host by host no
554  * @hostnum:	host number to locate
555  *
556  * Return value:
557  *	A pointer to located Scsi_Host or NULL.
558  *
559  *	The caller must do a scsi_host_put() to drop the reference
560  *	that scsi_host_get() took. The put_device() below dropped
561  *	the reference from class_find_device().
562  **/
563 struct Scsi_Host *scsi_host_lookup(unsigned int hostnum)
564 {
565 	struct device *cdev;
566 	struct Scsi_Host *shost = NULL;
567 
568 	cdev = class_find_device(&shost_class, NULL, &hostnum,
569 				 __scsi_host_match);
570 	if (cdev) {
571 		shost = scsi_host_get(class_to_shost(cdev));
572 		put_device(cdev);
573 	}
574 	return shost;
575 }
576 EXPORT_SYMBOL(scsi_host_lookup);
577 
578 /**
579  * scsi_host_get - inc a Scsi_Host ref count
580  * @shost:	Pointer to Scsi_Host to inc.
581  **/
582 struct Scsi_Host *scsi_host_get(struct Scsi_Host *shost)
583 {
584 	if ((shost->shost_state == SHOST_DEL) ||
585 		!get_device(&shost->shost_gendev))
586 		return NULL;
587 	return shost;
588 }
589 EXPORT_SYMBOL(scsi_host_get);
590 
591 static bool scsi_host_check_in_flight(struct request *rq, void *data)
592 {
593 	int *count = data;
594 	struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
595 
596 	if (test_bit(SCMD_STATE_INFLIGHT, &cmd->state))
597 		(*count)++;
598 
599 	return true;
600 }
601 
602 /**
603  * scsi_host_busy - Return the host busy counter
604  * @shost:	Pointer to Scsi_Host to inc.
605  **/
606 int scsi_host_busy(struct Scsi_Host *shost)
607 {
608 	int cnt = 0;
609 
610 	blk_mq_tagset_busy_iter(&shost->tag_set,
611 				scsi_host_check_in_flight, &cnt);
612 	return cnt;
613 }
614 EXPORT_SYMBOL(scsi_host_busy);
615 
616 /**
617  * scsi_host_put - dec a Scsi_Host ref count
618  * @shost:	Pointer to Scsi_Host to dec.
619  **/
620 void scsi_host_put(struct Scsi_Host *shost)
621 {
622 	put_device(&shost->shost_gendev);
623 }
624 EXPORT_SYMBOL(scsi_host_put);
625 
626 int scsi_init_hosts(void)
627 {
628 	return class_register(&shost_class);
629 }
630 
631 void scsi_exit_hosts(void)
632 {
633 	class_unregister(&shost_class);
634 	ida_destroy(&host_index_ida);
635 }
636 
637 int scsi_is_host_device(const struct device *dev)
638 {
639 	return dev->type == &scsi_host_type;
640 }
641 EXPORT_SYMBOL(scsi_is_host_device);
642 
643 /**
644  * scsi_queue_work - Queue work to the Scsi_Host workqueue.
645  * @shost:	Pointer to Scsi_Host.
646  * @work:	Work to queue for execution.
647  *
648  * Return value:
649  * 	1 - work queued for execution
650  *	0 - work is already queued
651  *	-EINVAL - work queue doesn't exist
652  **/
653 int scsi_queue_work(struct Scsi_Host *shost, struct work_struct *work)
654 {
655 	if (unlikely(!shost->work_q)) {
656 		shost_printk(KERN_ERR, shost,
657 			"ERROR: Scsi host '%s' attempted to queue scsi-work, "
658 			"when no workqueue created.\n", shost->hostt->name);
659 		dump_stack();
660 
661 		return -EINVAL;
662 	}
663 
664 	return queue_work(shost->work_q, work);
665 }
666 EXPORT_SYMBOL_GPL(scsi_queue_work);
667 
668 /**
669  * scsi_flush_work - Flush a Scsi_Host's workqueue.
670  * @shost:	Pointer to Scsi_Host.
671  **/
672 void scsi_flush_work(struct Scsi_Host *shost)
673 {
674 	if (!shost->work_q) {
675 		shost_printk(KERN_ERR, shost,
676 			"ERROR: Scsi host '%s' attempted to flush scsi-work, "
677 			"when no workqueue created.\n", shost->hostt->name);
678 		dump_stack();
679 		return;
680 	}
681 
682 	flush_workqueue(shost->work_q);
683 }
684 EXPORT_SYMBOL_GPL(scsi_flush_work);
685 
686 static bool complete_all_cmds_iter(struct request *rq, void *data)
687 {
688 	struct scsi_cmnd *scmd = blk_mq_rq_to_pdu(rq);
689 	enum scsi_host_status status = *(enum scsi_host_status *)data;
690 
691 	scsi_dma_unmap(scmd);
692 	scmd->result = 0;
693 	set_host_byte(scmd, status);
694 	scsi_done(scmd);
695 	return true;
696 }
697 
698 /**
699  * scsi_host_complete_all_commands - Terminate all running commands
700  * @shost:	Scsi Host on which commands should be terminated
701  * @status:	Status to be set for the terminated commands
702  *
703  * There is no protection against modification of the number
704  * of outstanding commands. It is the responsibility of the
705  * caller to ensure that concurrent I/O submission and/or
706  * completion is stopped when calling this function.
707  */
708 void scsi_host_complete_all_commands(struct Scsi_Host *shost,
709 				     enum scsi_host_status status)
710 {
711 	blk_mq_tagset_busy_iter(&shost->tag_set, complete_all_cmds_iter,
712 				&status);
713 }
714 EXPORT_SYMBOL_GPL(scsi_host_complete_all_commands);
715 
716 struct scsi_host_busy_iter_data {
717 	bool (*fn)(struct scsi_cmnd *, void *);
718 	void *priv;
719 };
720 
721 static bool __scsi_host_busy_iter_fn(struct request *req, void *priv)
722 {
723 	struct scsi_host_busy_iter_data *iter_data = priv;
724 	struct scsi_cmnd *sc = blk_mq_rq_to_pdu(req);
725 
726 	return iter_data->fn(sc, iter_data->priv);
727 }
728 
729 /**
730  * scsi_host_busy_iter - Iterate over all busy commands
731  * @shost:	Pointer to Scsi_Host.
732  * @fn:		Function to call on each busy command
733  * @priv:	Data pointer passed to @fn
734  *
735  * If locking against concurrent command completions is required
736  * ithas to be provided by the caller
737  **/
738 void scsi_host_busy_iter(struct Scsi_Host *shost,
739 			 bool (*fn)(struct scsi_cmnd *, void *),
740 			 void *priv)
741 {
742 	struct scsi_host_busy_iter_data iter_data = {
743 		.fn = fn,
744 		.priv = priv,
745 	};
746 
747 	blk_mq_tagset_busy_iter(&shost->tag_set, __scsi_host_busy_iter_fn,
748 				&iter_data);
749 }
750 EXPORT_SYMBOL_GPL(scsi_host_busy_iter);
751