1	// SPDX-License-Identifier: GPL-2.0-only
2	/*
3	* Copyright (C) 1999 Eric Youngdale
4	* Copyright (C) 2014 Christoph Hellwig
5	*
6	* SCSI queueing library.
7	* Initial versions: Eric Youngdale (eric@andante.org).
8	* Based upon conversations with large numbers
9	* of people at Linux Expo.
10	*/
11
12	#include <linux/bio.h>
13	#include <linux/bitops.h>
14	#include <linux/blkdev.h>
15	#include <linux/completion.h>
16	#include <linux/kernel.h>
17	#include <linux/export.h>
18	#include <linux/init.h>
19	#include <linux/pci.h>
20	#include <linux/delay.h>
21	#include <linux/hardirq.h>
22	#include <linux/scatterlist.h>
23	#include <linux/blk-mq.h>
24	#include <linux/blk-integrity.h>
25	#include <linux/ratelimit.h>
26	#include <asm/unaligned.h>
27
28	#include <scsi/scsi.h>
29	#include <scsi/scsi_cmnd.h>
30	#include <scsi/scsi_dbg.h>
31	#include <scsi/scsi_device.h>
32	#include <scsi/scsi_driver.h>
33	#include <scsi/scsi_eh.h>
34	#include <scsi/scsi_host.h>
35	#include <scsi/scsi_transport.h> /* __scsi_init_queue() */
36	#include <scsi/scsi_dh.h>
37
38	#include <trace/events/scsi.h>
39
40	#include "scsi_debugfs.h"
41	#include "scsi_priv.h"
42	#include "scsi_logging.h"
43
44	/*
45	* Size of integrity metadata is usually small, 1 inline sg should
46	* cover normal cases.
47	*/
48	#ifdef CONFIG_ARCH_NO_SG_CHAIN
49	#define SCSI_INLINE_PROT_SG_CNT 0
50	#define SCSI_INLINE_SG_CNT 0
51	#else
52	#define SCSI_INLINE_PROT_SG_CNT 1
53	#define SCSI_INLINE_SG_CNT 2
54	#endif
55
56	static struct kmem_cache *scsi_sense_cache;
57	static DEFINE_MUTEX(scsi_sense_cache_mutex);
58
59	static void scsi_mq_uninit_cmd(struct scsi_cmnd *cmd);
60
61	int scsi_init_sense_cache(struct Scsi_Host *shost)
62	{
63	int ret = 0;
64
65	mutex_lock(&scsi_sense_cache_mutex);
66	if (!scsi_sense_cache) {
67	scsi_sense_cache =
68	kmem_cache_create_usercopy(name: "scsi_sense_cache",
69	SCSI_SENSE_BUFFERSIZE, align: 0, SLAB_HWCACHE_ALIGN,
70	useroffset: 0, SCSI_SENSE_BUFFERSIZE, NULL);
71	if (!scsi_sense_cache)
72	ret = -ENOMEM;
73	}
74	mutex_unlock(lock: &scsi_sense_cache_mutex);
75	return ret;
76	}
77
78	static void
79	scsi_set_blocked(struct scsi_cmnd *cmd, int reason)
80	{
81	struct Scsi_Host *host = cmd->device->host;
82	struct scsi_device *device = cmd->device;
83	struct scsi_target *starget = scsi_target(sdev: device);
84
85	/*
86	* Set the appropriate busy bit for the device/host.
87	*
88	* If the host/device isn't busy, assume that something actually
89	* completed, and that we should be able to queue a command now.
90	*
91	* Note that the prior mid-layer assumption that any host could
92	* always queue at least one command is now broken. The mid-layer
93	* will implement a user specifiable stall (see
94	* scsi_host.max_host_blocked and scsi_device.max_device_blocked)
95	* if a command is requeued with no other commands outstanding
96	* either for the device or for the host.
97	*/
98	switch (reason) {
99	case SCSI_MLQUEUE_HOST_BUSY:
100	atomic_set(v: &host->host_blocked, i: host->max_host_blocked);
101	break;
102	case SCSI_MLQUEUE_DEVICE_BUSY:
103	case SCSI_MLQUEUE_EH_RETRY:
104	atomic_set(v: &device->device_blocked,
105	i: device->max_device_blocked);
106	break;
107	case SCSI_MLQUEUE_TARGET_BUSY:
108	atomic_set(v: &starget->target_blocked,
109	i: starget->max_target_blocked);
110	break;
111	}
112	}
113
114	static void scsi_mq_requeue_cmd(struct scsi_cmnd *cmd, unsigned long msecs)
115	{
116	struct request *rq = scsi_cmd_to_rq(scmd: cmd);
117
118	if (rq->rq_flags & RQF_DONTPREP) {
119	rq->rq_flags &= ~RQF_DONTPREP;
120	scsi_mq_uninit_cmd(cmd);
121	} else {
122	WARN_ON_ONCE(true);
123	}
124
125	blk_mq_requeue_request(rq, kick_requeue_list: false);
126	if (!scsi_host_in_recovery(shost: cmd->device->host))
127	blk_mq_delay_kick_requeue_list(q: rq->q, msecs);
128	}
129
130	/**
131	* __scsi_queue_insert - private queue insertion
132	* @cmd: The SCSI command being requeued
133	* @reason: The reason for the requeue
134	* @unbusy: Whether the queue should be unbusied
135	*
136	* This is a private queue insertion. The public interface
137	* scsi_queue_insert() always assumes the queue should be unbusied
138	* because it's always called before the completion. This function is
139	* for a requeue after completion, which should only occur in this
140	* file.
141	*/
142	static void __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, bool unbusy)
143	{
144	struct scsi_device *device = cmd->device;
145
146	SCSI_LOG_MLQUEUE(1, scmd_printk(KERN_INFO, cmd,
147	"Inserting command %p into mlqueue\n", cmd));
148
149	scsi_set_blocked(cmd, reason);
150
151	/*
152	* Decrement the counters, since these commands are no longer
153	* active on the host/device.
154	*/
155	if (unbusy)
156	scsi_device_unbusy(sdev: device, cmd);
157
158	/*
159	* Requeue this command. It will go before all other commands
160	* that are already in the queue. Schedule requeue work under
161	* lock such that the kblockd_schedule_work() call happens
162	* before blk_mq_destroy_queue() finishes.
163	*/
164	cmd->result = 0;
165
166	blk_mq_requeue_request(rq: scsi_cmd_to_rq(scmd: cmd),
167	kick_requeue_list: !scsi_host_in_recovery(shost: cmd->device->host));
168	}
169
170	/**
171	* scsi_queue_insert - Reinsert a command in the queue.
172	* @cmd: command that we are adding to queue.
173	* @reason: why we are inserting command to queue.
174	*
175	* We do this for one of two cases. Either the host is busy and it cannot accept
176	* any more commands for the time being, or the device returned QUEUE_FULL and
177	* can accept no more commands.
178	*
179	* Context: This could be called either from an interrupt context or a normal
180	* process context.
181	*/
182	void scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
183	{
184	__scsi_queue_insert(cmd, reason, unbusy: true);
185	}
186
187	void scsi_failures_reset_retries(struct scsi_failures *failures)
188	{
189	struct scsi_failure *failure;
190
191	failures->total_retries = 0;
192
193	for (failure = failures->failure_definitions; failure->result;
194	failure++)
195	failure->retries = 0;
196	}
197	EXPORT_SYMBOL_GPL(scsi_failures_reset_retries);
198
199	/**
200	* scsi_check_passthrough - Determine if passthrough scsi_cmnd needs a retry.
201	* @scmd: scsi_cmnd to check.
202	* @failures: scsi_failures struct that lists failures to check for.
203	*
204	* Returns -EAGAIN if the caller should retry else 0.
205	*/
206	static int scsi_check_passthrough(struct scsi_cmnd *scmd,
207	struct scsi_failures *failures)
208	{
209	struct scsi_failure *failure;
210	struct scsi_sense_hdr sshdr;
211	enum sam_status status;
212
213	if (!failures)
214	return 0;
215
216	for (failure = failures->failure_definitions; failure->result;
217	failure++) {
218	if (failure->result == SCMD_FAILURE_RESULT_ANY)
219	goto maybe_retry;
220
221	if (host_byte(scmd->result) &&
222	host_byte(scmd->result) == host_byte(failure->result))
223	goto maybe_retry;
224
225	status = status_byte(scmd->result);
226	if (!status)
227	continue;
228
229	if (failure->result == SCMD_FAILURE_STAT_ANY &&
230	!scsi_status_is_good(status: scmd->result))
231	goto maybe_retry;
232
233	if (status != status_byte(failure->result))
234	continue;
235
236	if (status_byte(failure->result) != SAM_STAT_CHECK_CONDITION ||
237	failure->sense == SCMD_FAILURE_SENSE_ANY)
238	goto maybe_retry;
239
240	if (!scsi_command_normalize_sense(cmd: scmd, sshdr: &sshdr))
241	return 0;
242
243	if (failure->sense != sshdr.sense_key)
244	continue;
245
246	if (failure->asc == SCMD_FAILURE_ASC_ANY)
247	goto maybe_retry;
248
249	if (failure->asc != sshdr.asc)
250	continue;
251
252	if (failure->ascq == SCMD_FAILURE_ASCQ_ANY ||
253	failure->ascq == sshdr.ascq)
254	goto maybe_retry;
255	}
256
257	return 0;
258
259	maybe_retry:
260	if (failure->allowed) {
261	if (failure->allowed == SCMD_FAILURE_NO_LIMIT ||
262	++failure->retries <= failure->allowed)
263	return -EAGAIN;
264	} else {
265	if (failures->total_allowed == SCMD_FAILURE_NO_LIMIT ||
266	++failures->total_retries <= failures->total_allowed)
267	return -EAGAIN;
268	}
269
270	return 0;
271	}
272
273	/**
274	* scsi_execute_cmd - insert request and wait for the result
275	* @sdev: scsi_device
276	* @cmd: scsi command
277	* @opf: block layer request cmd_flags
278	* @buffer: data buffer
279	* @bufflen: len of buffer
280	* @timeout: request timeout in HZ
281	* @ml_retries: number of times SCSI midlayer will retry request
282	* @args: Optional args. See struct definition for field descriptions
283	*
284	* Returns the scsi_cmnd result field if a command was executed, or a negative
285	* Linux error code if we didn't get that far.
286	*/
287	int scsi_execute_cmd(struct scsi_device *sdev, const unsigned char *cmd,
288	blk_opf_t opf, void *buffer, unsigned int bufflen,
289	int timeout, int ml_retries,
290	const struct scsi_exec_args *args)
291	{
292	static const struct scsi_exec_args default_args;
293	struct request *req;
294	struct scsi_cmnd *scmd;
295	int ret;
296
297	if (!args)
298	args = &default_args;
299	else if (WARN_ON_ONCE(args->sense &&
300	args->sense_len != SCSI_SENSE_BUFFERSIZE))
301	return -EINVAL;
302
303	retry:
304	req = scsi_alloc_request(q: sdev->request_queue, opf, flags: args->req_flags);
305	if (IS_ERR(ptr: req))
306	return PTR_ERR(ptr: req);
307
308	if (bufflen) {
309	ret = blk_rq_map_kern(sdev->request_queue, req,
310	buffer, bufflen, GFP_NOIO);
311	if (ret)
312	goto out;
313	}
314	scmd = blk_mq_rq_to_pdu(rq: req);
315	scmd->cmd_len = COMMAND_SIZE(cmd[0]);
316	memcpy(scmd->cmnd, cmd, scmd->cmd_len);
317	scmd->allowed = ml_retries;
318	scmd->flags |= args->scmd_flags;
319	req->timeout = timeout;
320	req->rq_flags |= RQF_QUIET;
321
322	/*
323	* head injection *required* here otherwise quiesce won't work
324	*/
325	blk_execute_rq(rq: req, at_head: true);
326
327	if (scsi_check_passthrough(scmd, failures: args->failures) == -EAGAIN) {
328	blk_mq_free_request(rq: req);
329	goto retry;
330	}
331
332	/*
333	* Some devices (USB mass-storage in particular) may transfer
334	* garbage data together with a residue indicating that the data
335	* is invalid. Prevent the garbage from being misinterpreted
336	* and prevent security leaks by zeroing out the excess data.
337	*/
338	if (unlikely(scmd->resid_len > 0 && scmd->resid_len <= bufflen))
339	memset(buffer + bufflen - scmd->resid_len, 0, scmd->resid_len);
340
341	if (args->resid)
342	*args->resid = scmd->resid_len;
343	if (args->sense)
344	memcpy(args->sense, scmd->sense_buffer, SCSI_SENSE_BUFFERSIZE);
345	if (args->sshdr)
346	scsi_normalize_sense(sense_buffer: scmd->sense_buffer, sb_len: scmd->sense_len,
347	sshdr: args->sshdr);
348
349	ret = scmd->result;
350	out:
351	blk_mq_free_request(rq: req);
352
353	return ret;
354	}
355	EXPORT_SYMBOL(scsi_execute_cmd);
356
357	/*
358	* Wake up the error handler if necessary. Avoid as follows that the error
359	* handler is not woken up if host in-flight requests number ==
360	* shost->host_failed: use call_rcu() in scsi_eh_scmd_add() in combination
361	* with an RCU read lock in this function to ensure that this function in
362	* its entirety either finishes before scsi_eh_scmd_add() increases the
363	* host_failed counter or that it notices the shost state change made by
364	* scsi_eh_scmd_add().
365	*/
366	static void scsi_dec_host_busy(struct Scsi_Host *shost, struct scsi_cmnd *cmd)
367	{
368	unsigned long flags;
369
370	rcu_read_lock();
371	__clear_bit(SCMD_STATE_INFLIGHT, &cmd->state);
372	if (unlikely(scsi_host_in_recovery(shost))) {
373	unsigned int busy = scsi_host_busy(shost);
374
375	spin_lock_irqsave(shost->host_lock, flags);
376	if (shost->host_failed || shost->host_eh_scheduled)
377	scsi_eh_wakeup(shost, busy);
378	spin_unlock_irqrestore(lock: shost->host_lock, flags);
379	}
380	rcu_read_unlock();
381	}
382
383	void scsi_device_unbusy(struct scsi_device *sdev, struct scsi_cmnd *cmd)
384	{
385	struct Scsi_Host *shost = sdev->host;
386	struct scsi_target *starget = scsi_target(sdev);
387
388	scsi_dec_host_busy(shost, cmd);
389
390	if (starget->can_queue > 0)
391	atomic_dec(v: &starget->target_busy);
392
393	sbitmap_put(sb: &sdev->budget_map, bitnr: cmd->budget_token);
394	cmd->budget_token = -1;
395	}
396
397	/*
398	* Kick the queue of SCSI device @sdev if @sdev != current_sdev. Called with
399	* interrupts disabled.
400	*/
401	static void scsi_kick_sdev_queue(struct scsi_device *sdev, void *data)
402	{
403	struct scsi_device *current_sdev = data;
404
405	if (sdev != current_sdev)
406	blk_mq_run_hw_queues(q: sdev->request_queue, async: true);
407	}
408
409	/*
410	* Called for single_lun devices on IO completion. Clear starget_sdev_user,
411	* and call blk_run_queue for all the scsi_devices on the target -
412	* including current_sdev first.
413	*
414	* Called with *no* scsi locks held.
415	*/
416	static void scsi_single_lun_run(struct scsi_device *current_sdev)
417	{
418	struct Scsi_Host *shost = current_sdev->host;
419	struct scsi_target *starget = scsi_target(sdev: current_sdev);
420	unsigned long flags;
421
422	spin_lock_irqsave(shost->host_lock, flags);
423	starget->starget_sdev_user = NULL;
424	spin_unlock_irqrestore(lock: shost->host_lock, flags);
425
426	/*
427	* Call blk_run_queue for all LUNs on the target, starting with
428	* current_sdev. We race with others (to set starget_sdev_user),
429	* but in most cases, we will be first. Ideally, each LU on the
430	* target would get some limited time or requests on the target.
431	*/
432	blk_mq_run_hw_queues(q: current_sdev->request_queue,
433	async: shost->queuecommand_may_block);
434
435	spin_lock_irqsave(shost->host_lock, flags);
436	if (!starget->starget_sdev_user)
437	__starget_for_each_device(starget, current_sdev,
438	fn: scsi_kick_sdev_queue);
439	spin_unlock_irqrestore(lock: shost->host_lock, flags);
440	}
441
442	static inline bool scsi_device_is_busy(struct scsi_device *sdev)
443	{
444	if (scsi_device_busy(sdev) >= sdev->queue_depth)
445	return true;
446	if (atomic_read(v: &sdev->device_blocked) > 0)
447	return true;
448	return false;
449	}
450
451	static inline bool scsi_target_is_busy(struct scsi_target *starget)
452	{
453	if (starget->can_queue > 0) {
454	if (atomic_read(v: &starget->target_busy) >= starget->can_queue)
455	return true;
456	if (atomic_read(v: &starget->target_blocked) > 0)
457	return true;
458	}
459	return false;
460	}
461
462	static inline bool scsi_host_is_busy(struct Scsi_Host *shost)
463	{
464	if (atomic_read(v: &shost->host_blocked) > 0)
465	return true;
466	if (shost->host_self_blocked)
467	return true;
468	return false;
469	}
470
471	static void scsi_starved_list_run(struct Scsi_Host *shost)
472	{
473	LIST_HEAD(starved_list);
474	struct scsi_device *sdev;
475	unsigned long flags;
476
477	spin_lock_irqsave(shost->host_lock, flags);
478	list_splice_init(list: &shost->starved_list, head: &starved_list);
479
480	while (!list_empty(head: &starved_list)) {
481	struct request_queue *slq;
482
483	/*
484	* As long as shost is accepting commands and we have
485	* starved queues, call blk_run_queue. scsi_request_fn
486	* drops the queue_lock and can add us back to the
487	* starved_list.
488	*
489	* host_lock protects the starved_list and starved_entry.
490	* scsi_request_fn must get the host_lock before checking
491	* or modifying starved_list or starved_entry.
492	*/
493	if (scsi_host_is_busy(shost))
494	break;
495
496	sdev = list_entry(starved_list.next,
497	struct scsi_device, starved_entry);
498	list_del_init(entry: &sdev->starved_entry);
499	if (scsi_target_is_busy(starget: scsi_target(sdev))) {
500	list_move_tail(list: &sdev->starved_entry,
501	head: &shost->starved_list);
502	continue;
503	}
504
505	/*
506	* Once we drop the host lock, a racing scsi_remove_device()
507	* call may remove the sdev from the starved list and destroy
508	* it and the queue. Mitigate by taking a reference to the
509	* queue and never touching the sdev again after we drop the
510	* host lock. Note: if __scsi_remove_device() invokes
511	* blk_mq_destroy_queue() before the queue is run from this
512	* function then blk_run_queue() will return immediately since
513	* blk_mq_destroy_queue() marks the queue with QUEUE_FLAG_DYING.
514	*/
515	slq = sdev->request_queue;
516	if (!blk_get_queue(slq))
517	continue;
518	spin_unlock_irqrestore(lock: shost->host_lock, flags);
519
520	blk_mq_run_hw_queues(q: slq, async: false);
521	blk_put_queue(slq);
522
523	spin_lock_irqsave(shost->host_lock, flags);
524	}
525	/* put any unprocessed entries back */
526	list_splice(list: &starved_list, head: &shost->starved_list);
527	spin_unlock_irqrestore(lock: shost->host_lock, flags);
528	}
529
530	/**
531	* scsi_run_queue - Select a proper request queue to serve next.
532	* @q: last request's queue
533	*
534	* The previous command was completely finished, start a new one if possible.
535	*/
536	static void scsi_run_queue(struct request_queue *q)
537	{
538	struct scsi_device *sdev = q->queuedata;
539
540	if (scsi_target(sdev)->single_lun)
541	scsi_single_lun_run(current_sdev: sdev);
542	if (!list_empty(head: &sdev->host->starved_list))
543	scsi_starved_list_run(shost: sdev->host);
544
545	/* Note: blk_mq_kick_requeue_list() runs the queue asynchronously. */
546	blk_mq_kick_requeue_list(q);
547	}
548
549	void scsi_requeue_run_queue(struct work_struct *work)
550	{
551	struct scsi_device *sdev;
552	struct request_queue *q;
553
554	sdev = container_of(work, struct scsi_device, requeue_work);
555	q = sdev->request_queue;
556	scsi_run_queue(q);
557	}
558
559	void scsi_run_host_queues(struct Scsi_Host *shost)
560	{
561	struct scsi_device *sdev;
562
563	shost_for_each_device(sdev, shost)
564	scsi_run_queue(q: sdev->request_queue);
565	}
566
567	static void scsi_uninit_cmd(struct scsi_cmnd *cmd)
568	{
569	if (!blk_rq_is_passthrough(rq: scsi_cmd_to_rq(scmd: cmd))) {
570	struct scsi_driver *drv = scsi_cmd_to_driver(cmd);
571
572	if (drv->uninit_command)
573	drv->uninit_command(cmd);
574	}
575	}
576
577	void scsi_free_sgtables(struct scsi_cmnd *cmd)
578	{
579	if (cmd->sdb.table.nents)
580	sg_free_table_chained(table: &cmd->sdb.table,
581	SCSI_INLINE_SG_CNT);
582	if (scsi_prot_sg_count(cmd))
583	sg_free_table_chained(table: &cmd->prot_sdb->table,
584	SCSI_INLINE_PROT_SG_CNT);
585	}
586	EXPORT_SYMBOL_GPL(scsi_free_sgtables);
587
588	static void scsi_mq_uninit_cmd(struct scsi_cmnd *cmd)
589	{
590	scsi_free_sgtables(cmd);
591	scsi_uninit_cmd(cmd);
592	}
593
594	static void scsi_run_queue_async(struct scsi_device *sdev)
595	{
596	if (scsi_host_in_recovery(shost: sdev->host))
597	return;
598
599	if (scsi_target(sdev)->single_lun ||
600	!list_empty(head: &sdev->host->starved_list)) {
601	kblockd_schedule_work(work: &sdev->requeue_work);
602	} else {
603	/*
604	* smp_mb() present in sbitmap_queue_clear() or implied in
605	* .end_io is for ordering writing .device_busy in
606	* scsi_device_unbusy() and reading sdev->restarts.
607	*/
608	int old = atomic_read(v: &sdev->restarts);
609
610	/*
611	* ->restarts has to be kept as non-zero if new budget
612	* contention occurs.
613	*
614	* No need to run queue when either another re-run
615	* queue wins in updating ->restarts or a new budget
616	* contention occurs.
617	*/
618	if (old && atomic_cmpxchg(v: &sdev->restarts, old, new: 0) == old)
619	blk_mq_run_hw_queues(q: sdev->request_queue, async: true);
620	}
621	}
622
623	/* Returns false when no more bytes to process, true if there are more */
624	static bool scsi_end_request(struct request *req, blk_status_t error,
625	unsigned int bytes)
626	{
627	struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq: req);
628	struct scsi_device *sdev = cmd->device;
629	struct request_queue *q = sdev->request_queue;
630
631	if (blk_update_request(rq: req, error, nr_bytes: bytes))
632	return true;
633
634	// XXX:
635	if (blk_queue_add_random(q))
636	add_disk_randomness(disk: req->q->disk);
637
638	WARN_ON_ONCE(!blk_rq_is_passthrough(req) &&
639	!(cmd->flags & SCMD_INITIALIZED));
640	cmd->flags = 0;
641
642	/*
643	* Calling rcu_barrier() is not necessary here because the
644	* SCSI error handler guarantees that the function called by
645	* call_rcu() has been called before scsi_end_request() is
646	* called.
647	*/
648	destroy_rcu_head(head: &cmd->rcu);
649
650	/*
651	* In the MQ case the command gets freed by __blk_mq_end_request,
652	* so we have to do all cleanup that depends on it earlier.
653	*
654	* We also can't kick the queues from irq context, so we
655	* will have to defer it to a workqueue.
656	*/
657	scsi_mq_uninit_cmd(cmd);
658
659	/*
660	* queue is still alive, so grab the ref for preventing it
661	* from being cleaned up during running queue.
662	*/
663	percpu_ref_get(ref: &q->q_usage_counter);
664
665	__blk_mq_end_request(rq: req, error);
666
667	scsi_run_queue_async(sdev);
668
669	percpu_ref_put(ref: &q->q_usage_counter);
670	return false;
671	}
672
673	/**
674	* scsi_result_to_blk_status - translate a SCSI result code into blk_status_t
675	* @result: scsi error code
676	*
677	* Translate a SCSI result code into a blk_status_t value.
678	*/
679	static blk_status_t scsi_result_to_blk_status(int result)
680	{
681	/*
682	* Check the scsi-ml byte first in case we converted a host or status
683	* byte.
684	*/
685	switch (scsi_ml_byte(result)) {
686	case SCSIML_STAT_OK:
687	break;
688	case SCSIML_STAT_RESV_CONFLICT:
689	return BLK_STS_RESV_CONFLICT;
690	case SCSIML_STAT_NOSPC:
691	return BLK_STS_NOSPC;
692	case SCSIML_STAT_MED_ERROR:
693	return BLK_STS_MEDIUM;
694	case SCSIML_STAT_TGT_FAILURE:
695	return BLK_STS_TARGET;
696	case SCSIML_STAT_DL_TIMEOUT:
697	return BLK_STS_DURATION_LIMIT;
698	}
699
700	switch (host_byte(result)) {
701	case DID_OK:
702	if (scsi_status_is_good(status: result))
703	return BLK_STS_OK;
704	return BLK_STS_IOERR;
705	case DID_TRANSPORT_FAILFAST:
706	case DID_TRANSPORT_MARGINAL:
707	return BLK_STS_TRANSPORT;
708	default:
709	return BLK_STS_IOERR;
710	}
711	}
712
713	/**
714	* scsi_rq_err_bytes - determine number of bytes till the next failure boundary
715	* @rq: request to examine
716	*
717	* Description:
718	* A request could be merge of IOs which require different failure
719	* handling. This function determines the number of bytes which
720	* can be failed from the beginning of the request without
721	* crossing into area which need to be retried further.
722	*
723	* Return:
724	* The number of bytes to fail.
725	*/
726	static unsigned int scsi_rq_err_bytes(const struct request *rq)
727	{
728	blk_opf_t ff = rq->cmd_flags & REQ_FAILFAST_MASK;
729	unsigned int bytes = 0;
730	struct bio *bio;
731
732	if (!(rq->rq_flags & RQF_MIXED_MERGE))
733	return blk_rq_bytes(rq);
734
735	/*
736	* Currently the only 'mixing' which can happen is between
737	* different fastfail types. We can safely fail portions
738	* which have all the failfast bits that the first one has -
739	* the ones which are at least as eager to fail as the first
740	* one.
741	*/
742	for (bio = rq->bio; bio; bio = bio->bi_next) {
743	if ((bio->bi_opf & ff) != ff)
744	break;
745	bytes += bio->bi_iter.bi_size;
746	}
747
748	/* this could lead to infinite loop */
749	BUG_ON(blk_rq_bytes(rq) && !bytes);
750	return bytes;
751	}
752
753	static bool scsi_cmd_runtime_exceeced(struct scsi_cmnd *cmd)
754	{
755	struct request *req = scsi_cmd_to_rq(scmd: cmd);
756	unsigned long wait_for;
757
758	if (cmd->allowed == SCSI_CMD_RETRIES_NO_LIMIT)
759	return false;
760
761	wait_for = (cmd->allowed + 1) * req->timeout;
762	if (time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) {
763	scmd_printk(KERN_ERR, cmd, "timing out command, waited %lus\n",
764	wait_for/HZ);
765	return true;
766	}
767	return false;
768	}
769
770	/*
771	* When ALUA transition state is returned, reprep the cmd to
772	* use the ALUA handler's transition timeout. Delay the reprep
773	* 1 sec to avoid aggressive retries of the target in that
774	* state.
775	*/
776	#define ALUA_TRANSITION_REPREP_DELAY 1000
777
778	/* Helper for scsi_io_completion() when special action required. */
779	static void scsi_io_completion_action(struct scsi_cmnd *cmd, int result)
780	{
781	struct request *req = scsi_cmd_to_rq(scmd: cmd);
782	int level = 0;
783	enum {ACTION_FAIL, ACTION_REPREP, ACTION_DELAYED_REPREP,
784	ACTION_RETRY, ACTION_DELAYED_RETRY} action;
785	struct scsi_sense_hdr sshdr;
786	bool sense_valid;
787	bool sense_current = true; /* false implies "deferred sense" */
788	blk_status_t blk_stat;
789
790	sense_valid = scsi_command_normalize_sense(cmd, sshdr: &sshdr);
791	if (sense_valid)
792	sense_current = !scsi_sense_is_deferred(sshdr: &sshdr);
793
794	blk_stat = scsi_result_to_blk_status(result);
795
796	if (host_byte(result) == DID_RESET) {
797	/* Third party bus reset or reset for error recovery
798	* reasons. Just retry the command and see what
799	* happens.
800	*/
801	action = ACTION_RETRY;
802	} else if (sense_valid && sense_current) {
803	switch (sshdr.sense_key) {
804	case UNIT_ATTENTION:
805	if (cmd->device->removable) {
806	/* Detected disc change. Set a bit
807	* and quietly refuse further access.
808	*/
809	cmd->device->changed = 1;
810	action = ACTION_FAIL;
811	} else {
812	/* Must have been a power glitch, or a
813	* bus reset. Could not have been a
814	* media change, so we just retry the
815	* command and see what happens.
816	*/
817	action = ACTION_RETRY;
818	}
819	break;
820	case ILLEGAL_REQUEST:
821	/* If we had an ILLEGAL REQUEST returned, then
822	* we may have performed an unsupported
823	* command. The only thing this should be
824	* would be a ten byte read where only a six
825	* byte read was supported. Also, on a system
826	* where READ CAPACITY failed, we may have
827	* read past the end of the disk.
828	*/
829	if ((cmd->device->use_10_for_rw &&
830	sshdr.asc == 0x20 && sshdr.ascq == 0x00) &&
831	(cmd->cmnd[0] == READ_10 ||
832	cmd->cmnd[0] == WRITE_10)) {
833	/* This will issue a new 6-byte command. */
834	cmd->device->use_10_for_rw = 0;
835	action = ACTION_REPREP;
836	} else if (sshdr.asc == 0x10) /* DIX */ {
837	action = ACTION_FAIL;
838	blk_stat = BLK_STS_PROTECTION;
839	/* INVALID COMMAND OPCODE or INVALID FIELD IN CDB */
840	} else if (sshdr.asc == 0x20 || sshdr.asc == 0x24) {
841	action = ACTION_FAIL;
842	blk_stat = BLK_STS_TARGET;
843	} else
844	action = ACTION_FAIL;
845	break;
846	case ABORTED_COMMAND:
847	action = ACTION_FAIL;
848	if (sshdr.asc == 0x10) /* DIF */
849	blk_stat = BLK_STS_PROTECTION;
850	break;
851	case NOT_READY:
852	/* If the device is in the process of becoming
853	* ready, or has a temporary blockage, retry.
854	*/
855	if (sshdr.asc == 0x04) {
856	switch (sshdr.ascq) {
857	case 0x01: /* becoming ready */
858	case 0x04: /* format in progress */
859	case 0x05: /* rebuild in progress */
860	case 0x06: /* recalculation in progress */
861	case 0x07: /* operation in progress */
862	case 0x08: /* Long write in progress */
863	case 0x09: /* self test in progress */
864	case 0x11: /* notify (enable spinup) required */
865	case 0x14: /* space allocation in progress */
866	case 0x1a: /* start stop unit in progress */
867	case 0x1b: /* sanitize in progress */
868	case 0x1d: /* configuration in progress */
869	case 0x24: /* depopulation in progress */
870	case 0x25: /* depopulation restore in progress */
871	action = ACTION_DELAYED_RETRY;
872	break;
873	case 0x0a: /* ALUA state transition */
874	action = ACTION_DELAYED_REPREP;
875	break;
876	default:
877	action = ACTION_FAIL;
878	break;
879	}
880	} else
881	action = ACTION_FAIL;
882	break;
883	case VOLUME_OVERFLOW:
884	/* See SSC3rXX or current. */
885	action = ACTION_FAIL;
886	break;
887	case DATA_PROTECT:
888	action = ACTION_FAIL;
889	if ((sshdr.asc == 0x0C && sshdr.ascq == 0x12) ||
890	(sshdr.asc == 0x55 &&
891	(sshdr.ascq == 0x0E || sshdr.ascq == 0x0F))) {
892	/* Insufficient zone resources */
893	blk_stat = BLK_STS_ZONE_OPEN_RESOURCE;
894	}
895	break;
896	case COMPLETED:
897	fallthrough;
898	default:
899	action = ACTION_FAIL;
900	break;
901	}
902	} else
903	action = ACTION_FAIL;
904
905	if (action != ACTION_FAIL && scsi_cmd_runtime_exceeced(cmd))
906	action = ACTION_FAIL;
907
908	switch (action) {
909	case ACTION_FAIL:
910	/* Give up and fail the remainder of the request */
911	if (!(req->rq_flags & RQF_QUIET)) {
912	static DEFINE_RATELIMIT_STATE(_rs,
913	DEFAULT_RATELIMIT_INTERVAL,
914	DEFAULT_RATELIMIT_BURST);
915
916	if (unlikely(scsi_logging_level))
917	level =
918	SCSI_LOG_LEVEL(SCSI_LOG_MLCOMPLETE_SHIFT,
919	SCSI_LOG_MLCOMPLETE_BITS);
920
921	/*
922	* if logging is enabled the failure will be printed
923	* in scsi_log_completion(), so avoid duplicate messages
924	*/
925	if (!level && __ratelimit(&_rs)) {
926	scsi_print_result(cmd, NULL, FAILED);
927	if (sense_valid)
928	scsi_print_sense(cmd);
929	scsi_print_command(cmd);
930	}
931	}
932	if (!scsi_end_request(req, error: blk_stat, bytes: scsi_rq_err_bytes(rq: req)))
933	return;
934	fallthrough;
935	case ACTION_REPREP:
936	scsi_mq_requeue_cmd(cmd, msecs: 0);
937	break;
938	case ACTION_DELAYED_REPREP:
939	scsi_mq_requeue_cmd(cmd, ALUA_TRANSITION_REPREP_DELAY);
940	break;
941	case ACTION_RETRY:
942	/* Retry the same command immediately */
943	__scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY, unbusy: false);
944	break;
945	case ACTION_DELAYED_RETRY:
946	/* Retry the same command after a delay */
947	__scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY, unbusy: false);
948	break;
949	}
950	}
951
952	/*
953	* Helper for scsi_io_completion() when cmd->result is non-zero. Returns a
954	* new result that may suppress further error checking. Also modifies
955	* *blk_statp in some cases.
956	*/
957	static int scsi_io_completion_nz_result(struct scsi_cmnd *cmd, int result,
958	blk_status_t *blk_statp)
959	{
960	bool sense_valid;
961	bool sense_current = true; /* false implies "deferred sense" */
962	struct request *req = scsi_cmd_to_rq(scmd: cmd);
963	struct scsi_sense_hdr sshdr;
964
965	sense_valid = scsi_command_normalize_sense(cmd, sshdr: &sshdr);
966	if (sense_valid)
967	sense_current = !scsi_sense_is_deferred(sshdr: &sshdr);
968
969	if (blk_rq_is_passthrough(rq: req)) {
970	if (sense_valid) {
971	/*
972	* SG_IO wants current and deferred errors
973	*/
974	cmd->sense_len = min(8 + cmd->sense_buffer[7],
975	SCSI_SENSE_BUFFERSIZE);
976	}
977	if (sense_current)
978	*blk_statp = scsi_result_to_blk_status(result);
979	} else if (blk_rq_bytes(rq: req) == 0 && sense_current) {
980	/*
981	* Flush commands do not transfers any data, and thus cannot use
982	* good_bytes != blk_rq_bytes(req) as the signal for an error.
983	* This sets *blk_statp explicitly for the problem case.
984	*/
985	*blk_statp = scsi_result_to_blk_status(result);
986	}
987	/*
988	* Recovered errors need reporting, but they're always treated as
989	* success, so fiddle the result code here. For passthrough requests
990	* we already took a copy of the original into sreq->result which
991	* is what gets returned to the user
992	*/
993	if (sense_valid && (sshdr.sense_key == RECOVERED_ERROR)) {
994	bool do_print = true;
995	/*
996	* if ATA PASS-THROUGH INFORMATION AVAILABLE [0x0, 0x1d]
997	* skip print since caller wants ATA registers. Only occurs
998	* on SCSI ATA PASS_THROUGH commands when CK_COND=1
999	*/
1000	if ((sshdr.asc == 0x0) && (sshdr.ascq == 0x1d))
1001	do_print = false;
1002	else if (req->rq_flags & RQF_QUIET)
1003	do_print = false;
1004	if (do_print)
1005	scsi_print_sense(cmd);
1006	result = 0;
1007	/* for passthrough, *blk_statp may be set */
1008	*blk_statp = BLK_STS_OK;
1009	}
1010	/*
1011	* Another corner case: the SCSI status byte is non-zero but 'good'.
1012	* Example: PRE-FETCH command returns SAM_STAT_CONDITION_MET when
1013	* it is able to fit nominated LBs in its cache (and SAM_STAT_GOOD
1014	* if it can't fit). Treat SAM_STAT_CONDITION_MET and the related
1015	* intermediate statuses (both obsolete in SAM-4) as good.
1016	*/
1017	if ((result & 0xff) && scsi_status_is_good(status: result)) {
1018	result = 0;
1019	*blk_statp = BLK_STS_OK;
1020	}
1021	return result;
1022	}
1023
1024	/**
1025	* scsi_io_completion - Completion processing for SCSI commands.
1026	* @cmd: command that is finished.
1027	* @good_bytes: number of processed bytes.
1028	*
1029	* We will finish off the specified number of sectors. If we are done, the
1030	* command block will be released and the queue function will be goosed. If we
1031	* are not done then we have to figure out what to do next:
1032	*
1033	* a) We can call scsi_mq_requeue_cmd(). The request will be
1034	* unprepared and put back on the queue. Then a new command will
1035	* be created for it. This should be used if we made forward
1036	* progress, or if we want to switch from READ(10) to READ(6) for
1037	* example.
1038	*
1039	* b) We can call scsi_io_completion_action(). The request will be
1040	* put back on the queue and retried using the same command as
1041	* before, possibly after a delay.
1042	*
1043	* c) We can call scsi_end_request() with blk_stat other than
1044	* BLK_STS_OK, to fail the remainder of the request.
1045	*/
1046	void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
1047	{
1048	int result = cmd->result;
1049	struct request *req = scsi_cmd_to_rq(scmd: cmd);
1050	blk_status_t blk_stat = BLK_STS_OK;
1051
1052	if (unlikely(result)) /* a nz result may or may not be an error */
1053	result = scsi_io_completion_nz_result(cmd, result, blk_statp: &blk_stat);
1054
1055	/*
1056	* Next deal with any sectors which we were able to correctly
1057	* handle.
1058	*/
1059	SCSI_LOG_HLCOMPLETE(1, scmd_printk(KERN_INFO, cmd,
1060	"%u sectors total, %d bytes done.\n",
1061	blk_rq_sectors(req), good_bytes));
1062
1063	/*
1064	* Failed, zero length commands always need to drop down
1065	* to retry code. Fast path should return in this block.
1066	*/
1067	if (likely(blk_rq_bytes(req) > 0 || blk_stat == BLK_STS_OK)) {
1068	if (likely(!scsi_end_request(req, blk_stat, good_bytes)))
1069	return; /* no bytes remaining */
1070	}
1071
1072	/* Kill remainder if no retries. */
1073	if (unlikely(blk_stat && scsi_noretry_cmd(cmd))) {
1074	if (scsi_end_request(req, error: blk_stat, bytes: blk_rq_bytes(rq: req)))
1075	WARN_ONCE(true,
1076	"Bytes remaining after failed, no-retry command");
1077	return;
1078	}
1079
1080	/*
1081	* If there had been no error, but we have leftover bytes in the
1082	* request just queue the command up again.
1083	*/
1084	if (likely(result == 0))
1085	scsi_mq_requeue_cmd(cmd, msecs: 0);
1086	else
1087	scsi_io_completion_action(cmd, result);
1088	}
1089
1090	static inline bool scsi_cmd_needs_dma_drain(struct scsi_device *sdev,
1091	struct request *rq)
1092	{
1093	return sdev->dma_drain_len && blk_rq_is_passthrough(rq) &&
1094	!op_is_write(op: req_op(req: rq)) &&
1095	sdev->host->hostt->dma_need_drain(rq);
1096	}
1097
1098	/**
1099	* scsi_alloc_sgtables - Allocate and initialize data and integrity scatterlists
1100	* @cmd: SCSI command data structure to initialize.
1101	*
1102	* Initializes @cmd->sdb and also @cmd->prot_sdb if data integrity is enabled
1103	* for @cmd.
1104	*
1105	* Returns:
1106	* * BLK_STS_OK - on success
1107	* * BLK_STS_RESOURCE - if the failure is retryable
1108	* * BLK_STS_IOERR - if the failure is fatal
1109	*/
1110	blk_status_t scsi_alloc_sgtables(struct scsi_cmnd *cmd)
1111	{
1112	struct scsi_device *sdev = cmd->device;
1113	struct request *rq = scsi_cmd_to_rq(scmd: cmd);
1114	unsigned short nr_segs = blk_rq_nr_phys_segments(rq);
1115	struct scatterlist *last_sg = NULL;
1116	blk_status_t ret;
1117	bool need_drain = scsi_cmd_needs_dma_drain(sdev, rq);
1118	int count;
1119
1120	if (WARN_ON_ONCE(!nr_segs))
1121	return BLK_STS_IOERR;
1122
1123	/*
1124	* Make sure there is space for the drain. The driver must adjust
1125	* max_hw_segments to be prepared for this.
1126	*/
1127	if (need_drain)
1128	nr_segs++;
1129
1130	/*
1131	* If sg table allocation fails, requeue request later.
1132	*/
1133	if (unlikely(sg_alloc_table_chained(&cmd->sdb.table, nr_segs,
1134	cmd->sdb.table.sgl, SCSI_INLINE_SG_CNT)))
1135	return BLK_STS_RESOURCE;
1136
1137	/*
1138	* Next, walk the list, and fill in the addresses and sizes of
1139	* each segment.
1140	*/
1141	count = __blk_rq_map_sg(q: rq->q, rq, sglist: cmd->sdb.table.sgl, last_sg: &last_sg);
1142
1143	if (blk_rq_bytes(rq) & rq->q->dma_pad_mask) {
1144	unsigned int pad_len =
1145	(rq->q->dma_pad_mask & ~blk_rq_bytes(rq)) + 1;
1146
1147	last_sg->length += pad_len;
1148	cmd->extra_len += pad_len;
1149	}
1150
1151	if (need_drain) {
1152	sg_unmark_end(sg: last_sg);
1153	last_sg = sg_next(last_sg);
1154	sg_set_buf(sg: last_sg, buf: sdev->dma_drain_buf, buflen: sdev->dma_drain_len);
1155	sg_mark_end(sg: last_sg);
1156
1157	cmd->extra_len += sdev->dma_drain_len;
1158	count++;
1159	}
1160
1161	BUG_ON(count > cmd->sdb.table.nents);
1162	cmd->sdb.table.nents = count;
1163	cmd->sdb.length = blk_rq_payload_bytes(rq);
1164
1165	if (blk_integrity_rq(rq)) {
1166	struct scsi_data_buffer *prot_sdb = cmd->prot_sdb;
1167	int ivecs;
1168
1169	if (WARN_ON_ONCE(!prot_sdb)) {
1170	/*
1171	* This can happen if someone (e.g. multipath)
1172	* queues a command to a device on an adapter
1173	* that does not support DIX.
1174	*/
1175	ret = BLK_STS_IOERR;
1176	goto out_free_sgtables;
1177	}
1178
1179	ivecs = blk_rq_count_integrity_sg(rq->q, rq->bio);
1180
1181	if (sg_alloc_table_chained(table: &prot_sdb->table, nents: ivecs,
1182	first_chunk: prot_sdb->table.sgl,
1183	SCSI_INLINE_PROT_SG_CNT)) {
1184	ret = BLK_STS_RESOURCE;
1185	goto out_free_sgtables;
1186	}
1187
1188	count = blk_rq_map_integrity_sg(rq->q, rq->bio,
1189	prot_sdb->table.sgl);
1190	BUG_ON(count > ivecs);
1191	BUG_ON(count > queue_max_integrity_segments(rq->q));
1192
1193	cmd->prot_sdb = prot_sdb;
1194	cmd->prot_sdb->table.nents = count;
1195	}
1196
1197	return BLK_STS_OK;
1198	out_free_sgtables:
1199	scsi_free_sgtables(cmd);
1200	return ret;
1201	}
1202	EXPORT_SYMBOL(scsi_alloc_sgtables);
1203
1204	/**
1205	* scsi_initialize_rq - initialize struct scsi_cmnd partially
1206	* @rq: Request associated with the SCSI command to be initialized.
1207	*
1208	* This function initializes the members of struct scsi_cmnd that must be
1209	* initialized before request processing starts and that won't be
1210	* reinitialized if a SCSI command is requeued.
1211	*/
1212	static void scsi_initialize_rq(struct request *rq)
1213	{
1214	struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
1215
1216	memset(cmd->cmnd, 0, sizeof(cmd->cmnd));
1217	cmd->cmd_len = MAX_COMMAND_SIZE;
1218	cmd->sense_len = 0;
1219	init_rcu_head(head: &cmd->rcu);
1220	cmd->jiffies_at_alloc = jiffies;
1221	cmd->retries = 0;
1222	}
1223
1224	struct request *scsi_alloc_request(struct request_queue *q, blk_opf_t opf,
1225	blk_mq_req_flags_t flags)
1226	{
1227	struct request *rq;
1228
1229	rq = blk_mq_alloc_request(q, opf, flags);
1230	if (!IS_ERR(ptr: rq))
1231	scsi_initialize_rq(rq);
1232	return rq;
1233	}
1234	EXPORT_SYMBOL_GPL(scsi_alloc_request);
1235
1236	/*
1237	* Only called when the request isn't completed by SCSI, and not freed by
1238	* SCSI
1239	*/
1240	static void scsi_cleanup_rq(struct request *rq)
1241	{
1242	if (rq->rq_flags & RQF_DONTPREP) {
1243	scsi_mq_uninit_cmd(cmd: blk_mq_rq_to_pdu(rq));
1244	rq->rq_flags &= ~RQF_DONTPREP;
1245	}
1246	}
1247
1248	/* Called before a request is prepared. See also scsi_mq_prep_fn(). */
1249	void scsi_init_command(struct scsi_device *dev, struct scsi_cmnd *cmd)
1250	{
1251	struct request *rq = scsi_cmd_to_rq(scmd: cmd);
1252
1253	if (!blk_rq_is_passthrough(rq) && !(cmd->flags & SCMD_INITIALIZED)) {
1254	cmd->flags |= SCMD_INITIALIZED;
1255	scsi_initialize_rq(rq);
1256	}
1257
1258	cmd->device = dev;
1259	INIT_LIST_HEAD(list: &cmd->eh_entry);
1260	INIT_DELAYED_WORK(&cmd->abort_work, scmd_eh_abort_handler);
1261	}
1262
1263	static blk_status_t scsi_setup_scsi_cmnd(struct scsi_device *sdev,
1264	struct request *req)
1265	{
1266	struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq: req);
1267
1268	/*
1269	* Passthrough requests may transfer data, in which case they must
1270	* a bio attached to them. Or they might contain a SCSI command
1271	* that does not transfer data, in which case they may optionally
1272	* submit a request without an attached bio.
1273	*/
1274	if (req->bio) {
1275	blk_status_t ret = scsi_alloc_sgtables(cmd);
1276	if (unlikely(ret != BLK_STS_OK))
1277	return ret;
1278	} else {
1279	BUG_ON(blk_rq_bytes(req));
1280
1281	memset(&cmd->sdb, 0, sizeof(cmd->sdb));
1282	}
1283
1284	cmd->transfersize = blk_rq_bytes(rq: req);
1285	return BLK_STS_OK;
1286	}
1287
1288	static blk_status_t
1289	scsi_device_state_check(struct scsi_device *sdev, struct request *req)
1290	{
1291	switch (sdev->sdev_state) {
1292	case SDEV_CREATED:
1293	return BLK_STS_OK;
1294	case SDEV_OFFLINE:
1295	case SDEV_TRANSPORT_OFFLINE:
1296	/*
1297	* If the device is offline we refuse to process any
1298	* commands. The device must be brought online
1299	* before trying any recovery commands.
1300	*/
1301	if (!sdev->offline_already) {
1302	sdev->offline_already = true;
1303	sdev_printk(KERN_ERR, sdev,
1304	"rejecting I/O to offline device\n");
1305	}
1306	return BLK_STS_IOERR;
1307	case SDEV_DEL:
1308	/*
1309	* If the device is fully deleted, we refuse to
1310	* process any commands as well.
1311	*/
1312	sdev_printk(KERN_ERR, sdev,
1313	"rejecting I/O to dead device\n");
1314	return BLK_STS_IOERR;
1315	case SDEV_BLOCK:
1316	case SDEV_CREATED_BLOCK:
1317	return BLK_STS_RESOURCE;
1318	case SDEV_QUIESCE:
1319	/*
1320	* If the device is blocked we only accept power management
1321	* commands.
1322	*/
1323	if (req && WARN_ON_ONCE(!(req->rq_flags & RQF_PM)))
1324	return BLK_STS_RESOURCE;
1325	return BLK_STS_OK;
1326	default:
1327	/*
1328	* For any other not fully online state we only allow
1329	* power management commands.
1330	*/
1331	if (req && !(req->rq_flags & RQF_PM))
1332	return BLK_STS_OFFLINE;
1333	return BLK_STS_OK;
1334	}
1335	}
1336
1337	/*
1338	* scsi_dev_queue_ready: if we can send requests to sdev, assign one token
1339	* and return the token else return -1.
1340	*/
1341	static inline int scsi_dev_queue_ready(struct request_queue *q,
1342	struct scsi_device *sdev)
1343	{
1344	int token;
1345
1346	token = sbitmap_get(sb: &sdev->budget_map);
1347	if (token < 0)
1348	return -1;
1349
1350	if (!atomic_read(v: &sdev->device_blocked))
1351	return token;
1352
1353	/*
1354	* Only unblock if no other commands are pending and
1355	* if device_blocked has decreased to zero
1356	*/
1357	if (scsi_device_busy(sdev) > 1 ||
1358	atomic_dec_return(v: &sdev->device_blocked) > 0) {
1359	sbitmap_put(sb: &sdev->budget_map, bitnr: token);
1360	return -1;
1361	}
1362
1363	SCSI_LOG_MLQUEUE(3, sdev_printk(KERN_INFO, sdev,
1364	"unblocking device at zero depth\n"));
1365
1366	return token;
1367	}
1368
1369	/*
1370	* scsi_target_queue_ready: checks if there we can send commands to target
1371	* @sdev: scsi device on starget to check.
1372	*/
1373	static inline int scsi_target_queue_ready(struct Scsi_Host *shost,
1374	struct scsi_device *sdev)
1375	{
1376	struct scsi_target *starget = scsi_target(sdev);
1377	unsigned int busy;
1378
1379	if (starget->single_lun) {
1380	spin_lock_irq(lock: shost->host_lock);
1381	if (starget->starget_sdev_user &&
1382	starget->starget_sdev_user != sdev) {
1383	spin_unlock_irq(lock: shost->host_lock);
1384	return 0;
1385	}
1386	starget->starget_sdev_user = sdev;
1387	spin_unlock_irq(lock: shost->host_lock);
1388	}
1389
1390	if (starget->can_queue <= 0)
1391	return 1;
1392
1393	busy = atomic_inc_return(v: &starget->target_busy) - 1;
1394	if (atomic_read(v: &starget->target_blocked) > 0) {
1395	if (busy)
1396	goto starved;
1397
1398	/*
1399	* unblock after target_blocked iterates to zero
1400	*/
1401	if (atomic_dec_return(v: &starget->target_blocked) > 0)
1402	goto out_dec;
1403
1404	SCSI_LOG_MLQUEUE(3, starget_printk(KERN_INFO, starget,
1405	"unblocking target at zero depth\n"));
1406	}
1407
1408	if (busy >= starget->can_queue)
1409	goto starved;
1410
1411	return 1;
1412
1413	starved:
1414	spin_lock_irq(lock: shost->host_lock);
1415	list_move_tail(list: &sdev->starved_entry, head: &shost->starved_list);
1416	spin_unlock_irq(lock: shost->host_lock);
1417	out_dec:
1418	if (starget->can_queue > 0)
1419	atomic_dec(v: &starget->target_busy);
1420	return 0;
1421	}
1422
1423	/*
1424	* scsi_host_queue_ready: if we can send requests to shost, return 1 else
1425	* return 0. We must end up running the queue again whenever 0 is
1426	* returned, else IO can hang.
1427	*/
1428	static inline int scsi_host_queue_ready(struct request_queue *q,
1429	struct Scsi_Host *shost,
1430	struct scsi_device *sdev,
1431	struct scsi_cmnd *cmd)
1432	{
1433	if (atomic_read(v: &shost->host_blocked) > 0) {
1434	if (scsi_host_busy(shost) > 0)
1435	goto starved;
1436
1437	/*
1438	* unblock after host_blocked iterates to zero
1439	*/
1440	if (atomic_dec_return(v: &shost->host_blocked) > 0)
1441	goto out_dec;
1442
1443	SCSI_LOG_MLQUEUE(3,
1444	shost_printk(KERN_INFO, shost,
1445	"unblocking host at zero depth\n"));
1446	}
1447
1448	if (shost->host_self_blocked)
1449	goto starved;
1450
1451	/* We're OK to process the command, so we can't be starved */
1452	if (!list_empty(head: &sdev->starved_entry)) {
1453	spin_lock_irq(lock: shost->host_lock);
1454	if (!list_empty(head: &sdev->starved_entry))
1455	list_del_init(entry: &sdev->starved_entry);
1456	spin_unlock_irq(lock: shost->host_lock);
1457	}
1458
1459	__set_bit(SCMD_STATE_INFLIGHT, &cmd->state);
1460
1461	return 1;
1462
1463	starved:
1464	spin_lock_irq(lock: shost->host_lock);
1465	if (list_empty(head: &sdev->starved_entry))
1466	list_add_tail(new: &sdev->starved_entry, head: &shost->starved_list);
1467	spin_unlock_irq(lock: shost->host_lock);
1468	out_dec:
1469	scsi_dec_host_busy(shost, cmd);
1470	return 0;
1471	}
1472
1473	/*
1474	* Busy state exporting function for request stacking drivers.
1475	*
1476	* For efficiency, no lock is taken to check the busy state of
1477	* shost/starget/sdev, since the returned value is not guaranteed and
1478	* may be changed after request stacking drivers call the function,
1479	* regardless of taking lock or not.
1480	*
1481	* When scsi can't dispatch I/Os anymore and needs to kill I/Os scsi
1482	* needs to return 'not busy'. Otherwise, request stacking drivers
1483	* may hold requests forever.
1484	*/
1485	static bool scsi_mq_lld_busy(struct request_queue *q)
1486	{
1487	struct scsi_device *sdev = q->queuedata;
1488	struct Scsi_Host *shost;
1489
1490	if (blk_queue_dying(q))
1491	return false;
1492
1493	shost = sdev->host;
1494
1495	/*
1496	* Ignore host/starget busy state.
1497	* Since block layer does not have a concept of fairness across
1498	* multiple queues, congestion of host/starget needs to be handled
1499	* in SCSI layer.
1500	*/
1501	if (scsi_host_in_recovery(shost) || scsi_device_is_busy(sdev))
1502	return true;
1503
1504	return false;
1505	}
1506
1507	/*
1508	* Block layer request completion callback. May be called from interrupt
1509	* context.
1510	*/
1511	static void scsi_complete(struct request *rq)
1512	{
1513	struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
1514	enum scsi_disposition disposition;
1515
1516	INIT_LIST_HEAD(list: &cmd->eh_entry);
1517
1518	atomic_inc(v: &cmd->device->iodone_cnt);
1519	if (cmd->result)
1520	atomic_inc(v: &cmd->device->ioerr_cnt);
1521
1522	disposition = scsi_decide_disposition(cmd);
1523	if (disposition != SUCCESS && scsi_cmd_runtime_exceeced(cmd))
1524	disposition = SUCCESS;
1525
1526	scsi_log_completion(cmd, disposition);
1527
1528	switch (disposition) {
1529	case SUCCESS:
1530	scsi_finish_command(cmd);
1531	break;
1532	case NEEDS_RETRY:
1533	scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY);
1534	break;
1535	case ADD_TO_MLQUEUE:
1536	scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
1537	break;
1538	default:
1539	scsi_eh_scmd_add(cmd);
1540	break;
1541	}
1542	}
1543
1544	/**
1545	* scsi_dispatch_cmd - Dispatch a command to the low-level driver.
1546	* @cmd: command block we are dispatching.
1547	*
1548	* Return: nonzero return request was rejected and device's queue needs to be
1549	* plugged.
1550	*/
1551	static int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
1552	{
1553	struct Scsi_Host *host = cmd->device->host;
1554	int rtn = 0;
1555
1556	atomic_inc(v: &cmd->device->iorequest_cnt);
1557
1558	/* check if the device is still usable */
1559	if (unlikely(cmd->device->sdev_state == SDEV_DEL)) {
1560	/* in SDEV_DEL we error all commands. DID_NO_CONNECT
1561	* returns an immediate error upwards, and signals
1562	* that the device is no longer present */
1563	cmd->result = DID_NO_CONNECT << 16;
1564	goto done;
1565	}
1566
1567	/* Check to see if the scsi lld made this device blocked. */
1568	if (unlikely(scsi_device_blocked(cmd->device))) {
1569	/*
1570	* in blocked state, the command is just put back on
1571	* the device queue. The suspend state has already
1572	* blocked the queue so future requests should not
1573	* occur until the device transitions out of the
1574	* suspend state.
1575	*/
1576	SCSI_LOG_MLQUEUE(3, scmd_printk(KERN_INFO, cmd,
1577	"queuecommand : device blocked\n"));
1578	atomic_dec(v: &cmd->device->iorequest_cnt);
1579	return SCSI_MLQUEUE_DEVICE_BUSY;
1580	}
1581
1582	/* Store the LUN value in cmnd, if needed. */
1583	if (cmd->device->lun_in_cdb)
1584	cmd->cmnd[1] = (cmd->cmnd[1] & 0x1f) |
1585	(cmd->device->lun << 5 & 0xe0);
1586
1587	scsi_log_send(cmd);
1588
1589	/*
1590	* Before we queue this command, check if the command
1591	* length exceeds what the host adapter can handle.
1592	*/
1593	if (cmd->cmd_len > cmd->device->host->max_cmd_len) {
1594	SCSI_LOG_MLQUEUE(3, scmd_printk(KERN_INFO, cmd,
1595	"queuecommand : command too long. "
1596	"cdb_size=%d host->max_cmd_len=%d\n",
1597	cmd->cmd_len, cmd->device->host->max_cmd_len));
1598	cmd->result = (DID_ABORT << 16);
1599	goto done;
1600	}
1601
1602	if (unlikely(host->shost_state == SHOST_DEL)) {
1603	cmd->result = (DID_NO_CONNECT << 16);
1604	goto done;
1605
1606	}
1607
1608	trace_scsi_dispatch_cmd_start(cmd);
1609	rtn = host->hostt->queuecommand(host, cmd);
1610	if (rtn) {
1611	atomic_dec(v: &cmd->device->iorequest_cnt);
1612	trace_scsi_dispatch_cmd_error(cmd, rtn);
1613	if (rtn != SCSI_MLQUEUE_DEVICE_BUSY &&
1614	rtn != SCSI_MLQUEUE_TARGET_BUSY)
1615	rtn = SCSI_MLQUEUE_HOST_BUSY;
1616
1617	SCSI_LOG_MLQUEUE(3, scmd_printk(KERN_INFO, cmd,
1618	"queuecommand : request rejected\n"));
1619	}
1620
1621	return rtn;
1622	done:
1623	scsi_done(cmd);
1624	return 0;
1625	}
1626
1627	/* Size in bytes of the sg-list stored in the scsi-mq command-private data. */
1628	static unsigned int scsi_mq_inline_sgl_size(struct Scsi_Host *shost)
1629	{
1630	return min_t(unsigned int, shost->sg_tablesize, SCSI_INLINE_SG_CNT) *
1631	sizeof(struct scatterlist);
1632	}
1633
1634	static blk_status_t scsi_prepare_cmd(struct request *req)
1635	{
1636	struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq: req);
1637	struct scsi_device *sdev = req->q->queuedata;
1638	struct Scsi_Host *shost = sdev->host;
1639	bool in_flight = test_bit(SCMD_STATE_INFLIGHT, &cmd->state);
1640	struct scatterlist *sg;
1641
1642	scsi_init_command(dev: sdev, cmd);
1643
1644	cmd->eh_eflags = 0;
1645	cmd->prot_type = 0;
1646	cmd->prot_flags = 0;
1647	cmd->submitter = 0;
1648	memset(&cmd->sdb, 0, sizeof(cmd->sdb));
1649	cmd->underflow = 0;
1650	cmd->transfersize = 0;
1651	cmd->host_scribble = NULL;
1652	cmd->result = 0;
1653	cmd->extra_len = 0;
1654	cmd->state = 0;
1655	if (in_flight)
1656	__set_bit(SCMD_STATE_INFLIGHT, &cmd->state);
1657
1658	/*
1659	* Only clear the driver-private command data if the LLD does not supply
1660	* a function to initialize that data.
1661	*/
1662	if (!shost->hostt->init_cmd_priv)
1663	memset(cmd + 1, 0, shost->hostt->cmd_size);
1664
1665	cmd->prot_op = SCSI_PROT_NORMAL;
1666	if (blk_rq_bytes(rq: req))
1667	cmd->sc_data_direction = rq_dma_dir(req);
1668	else
1669	cmd->sc_data_direction = DMA_NONE;
1670
1671	sg = (void *)cmd + sizeof(struct scsi_cmnd) + shost->hostt->cmd_size;
1672	cmd->sdb.table.sgl = sg;
1673
1674	if (scsi_host_get_prot(shost)) {
1675	memset(cmd->prot_sdb, 0, sizeof(struct scsi_data_buffer));
1676
1677	cmd->prot_sdb->table.sgl =
1678	(struct scatterlist *)(cmd->prot_sdb + 1);
1679	}
1680
1681	/*
1682	* Special handling for passthrough commands, which don't go to the ULP
1683	* at all:
1684	*/
1685	if (blk_rq_is_passthrough(rq: req))
1686	return scsi_setup_scsi_cmnd(sdev, req);
1687
1688	if (sdev->handler && sdev->handler->prep_fn) {
1689	blk_status_t ret = sdev->handler->prep_fn(sdev, req);
1690
1691	if (ret != BLK_STS_OK)
1692	return ret;
1693	}
1694
1695	/* Usually overridden by the ULP */
1696	cmd->allowed = 0;
1697	memset(cmd->cmnd, 0, sizeof(cmd->cmnd));
1698	return scsi_cmd_to_driver(cmd)->init_command(cmd);
1699	}
1700
1701	static void scsi_done_internal(struct scsi_cmnd *cmd, bool complete_directly)
1702	{
1703	struct request *req = scsi_cmd_to_rq(scmd: cmd);
1704
1705	switch (cmd->submitter) {
1706	case SUBMITTED_BY_BLOCK_LAYER:
1707	break;
1708	case SUBMITTED_BY_SCSI_ERROR_HANDLER:
1709	return scsi_eh_done(scmd: cmd);
1710	case SUBMITTED_BY_SCSI_RESET_IOCTL:
1711	return;
1712	}
1713
1714	if (unlikely(blk_should_fake_timeout(scsi_cmd_to_rq(cmd)->q)))
1715	return;
1716	if (unlikely(test_and_set_bit(SCMD_STATE_COMPLETE, &cmd->state)))
1717	return;
1718	trace_scsi_dispatch_cmd_done(cmd);
1719
1720	if (complete_directly)
1721	blk_mq_complete_request_direct(rq: req, complete: scsi_complete);
1722	else
1723	blk_mq_complete_request(rq: req);
1724	}
1725
1726	void scsi_done(struct scsi_cmnd *cmd)
1727	{
1728	scsi_done_internal(cmd, complete_directly: false);
1729	}
1730	EXPORT_SYMBOL(scsi_done);
1731
1732	void scsi_done_direct(struct scsi_cmnd *cmd)
1733	{
1734	scsi_done_internal(cmd, complete_directly: true);
1735	}
1736	EXPORT_SYMBOL(scsi_done_direct);
1737
1738	static void scsi_mq_put_budget(struct request_queue *q, int budget_token)
1739	{
1740	struct scsi_device *sdev = q->queuedata;
1741
1742	sbitmap_put(sb: &sdev->budget_map, bitnr: budget_token);
1743	}
1744
1745	/*
1746	* When to reinvoke queueing after a resource shortage. It's 3 msecs to
1747	* not change behaviour from the previous unplug mechanism, experimentation
1748	* may prove this needs changing.
1749	*/
1750	#define SCSI_QUEUE_DELAY 3
1751
1752	static int scsi_mq_get_budget(struct request_queue *q)
1753	{
1754	struct scsi_device *sdev = q->queuedata;
1755	int token = scsi_dev_queue_ready(q, sdev);
1756
1757	if (token >= 0)
1758	return token;
1759
1760	atomic_inc(v: &sdev->restarts);
1761
1762	/*
1763	* Orders atomic_inc(&sdev->restarts) and atomic_read(&sdev->device_busy).
1764	* .restarts must be incremented before .device_busy is read because the
1765	* code in scsi_run_queue_async() depends on the order of these operations.
1766	*/
1767	smp_mb__after_atomic();
1768
1769	/*
1770	* If all in-flight requests originated from this LUN are completed
1771	* before reading .device_busy, sdev->device_busy will be observed as
1772	* zero, then blk_mq_delay_run_hw_queues() will dispatch this request
1773	* soon. Otherwise, completion of one of these requests will observe
1774	* the .restarts flag, and the request queue will be run for handling
1775	* this request, see scsi_end_request().
1776	*/
1777	if (unlikely(scsi_device_busy(sdev) == 0 &&
1778	!scsi_device_blocked(sdev)))
1779	blk_mq_delay_run_hw_queues(q: sdev->request_queue, SCSI_QUEUE_DELAY);
1780	return -1;
1781	}
1782
1783	static void scsi_mq_set_rq_budget_token(struct request *req, int token)
1784	{
1785	struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq: req);
1786
1787	cmd->budget_token = token;
1788	}
1789
1790	static int scsi_mq_get_rq_budget_token(struct request *req)
1791	{
1792	struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq: req);
1793
1794	return cmd->budget_token;
1795	}
1796
1797	static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx,
1798	const struct blk_mq_queue_data *bd)
1799	{
1800	struct request *req = bd->rq;
1801	struct request_queue *q = req->q;
1802	struct scsi_device *sdev = q->queuedata;
1803	struct Scsi_Host *shost = sdev->host;
1804	struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq: req);
1805	blk_status_t ret;
1806	int reason;
1807
1808	WARN_ON_ONCE(cmd->budget_token < 0);
1809
1810	/*
1811	* If the device is not in running state we will reject some or all
1812	* commands.
1813	*/
1814	if (unlikely(sdev->sdev_state != SDEV_RUNNING)) {
1815	ret = scsi_device_state_check(sdev, req);
1816	if (ret != BLK_STS_OK)
1817	goto out_put_budget;
1818	}
1819
1820	ret = BLK_STS_RESOURCE;
1821	if (!scsi_target_queue_ready(shost, sdev))
1822	goto out_put_budget;
1823	if (unlikely(scsi_host_in_recovery(shost))) {
1824	if (cmd->flags & SCMD_FAIL_IF_RECOVERING)
1825	ret = BLK_STS_OFFLINE;
1826	goto out_dec_target_busy;
1827	}
1828	if (!scsi_host_queue_ready(q, shost, sdev, cmd))
1829	goto out_dec_target_busy;
1830
1831	if (!(req->rq_flags & RQF_DONTPREP)) {
1832	ret = scsi_prepare_cmd(req);
1833	if (ret != BLK_STS_OK)
1834	goto out_dec_host_busy;
1835	req->rq_flags |= RQF_DONTPREP;
1836	} else {
1837	clear_bit(SCMD_STATE_COMPLETE, addr: &cmd->state);
1838	}
1839
1840	cmd->flags &= SCMD_PRESERVED_FLAGS;
1841	if (sdev->simple_tags)
1842	cmd->flags |= SCMD_TAGGED;
1843	if (bd->last)
1844	cmd->flags |= SCMD_LAST;
1845
1846	scsi_set_resid(cmd, resid: 0);
1847	memset(cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);
1848	cmd->submitter = SUBMITTED_BY_BLOCK_LAYER;
1849
1850	blk_mq_start_request(rq: req);
1851	reason = scsi_dispatch_cmd(cmd);
1852	if (reason) {
1853	scsi_set_blocked(cmd, reason);
1854	ret = BLK_STS_RESOURCE;
1855	goto out_dec_host_busy;
1856	}
1857
1858	return BLK_STS_OK;
1859
1860	out_dec_host_busy:
1861	scsi_dec_host_busy(shost, cmd);
1862	out_dec_target_busy:
1863	if (scsi_target(sdev)->can_queue > 0)
1864	atomic_dec(v: &scsi_target(sdev)->target_busy);
1865	out_put_budget:
1866	scsi_mq_put_budget(q, budget_token: cmd->budget_token);
1867	cmd->budget_token = -1;
1868	switch (ret) {
1869	case BLK_STS_OK:
1870	break;
1871	case BLK_STS_RESOURCE:
1872	case BLK_STS_ZONE_RESOURCE:
1873	if (scsi_device_blocked(sdev))
1874	ret = BLK_STS_DEV_RESOURCE;
1875	break;
1876	case BLK_STS_AGAIN:
1877	cmd->result = DID_BUS_BUSY << 16;
1878	if (req->rq_flags & RQF_DONTPREP)
1879	scsi_mq_uninit_cmd(cmd);
1880	break;
1881	default:
1882	if (unlikely(!scsi_device_online(sdev)))
1883	cmd->result = DID_NO_CONNECT << 16;
1884	else
1885	cmd->result = DID_ERROR << 16;
1886	/*
1887	* Make sure to release all allocated resources when
1888	* we hit an error, as we will never see this command
1889	* again.
1890	*/
1891	if (req->rq_flags & RQF_DONTPREP)
1892	scsi_mq_uninit_cmd(cmd);
1893	scsi_run_queue_async(sdev);
1894	break;
1895	}
1896	return ret;
1897	}
1898
1899	static int scsi_mq_init_request(struct blk_mq_tag_set *set, struct request *rq,
1900	unsigned int hctx_idx, unsigned int numa_node)
1901	{
1902	struct Scsi_Host *shost = set->driver_data;
1903	struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
1904	struct scatterlist *sg;
1905	int ret = 0;
1906
1907	cmd->sense_buffer =
1908	kmem_cache_alloc_node(s: scsi_sense_cache, GFP_KERNEL, node: numa_node);
1909	if (!cmd->sense_buffer)
1910	return -ENOMEM;
1911
1912	if (scsi_host_get_prot(shost)) {
1913	sg = (void *)cmd + sizeof(struct scsi_cmnd) +
1914	shost->hostt->cmd_size;
1915	cmd->prot_sdb = (void *)sg + scsi_mq_inline_sgl_size(shost);
1916	}
1917
1918	if (shost->hostt->init_cmd_priv) {
1919	ret = shost->hostt->init_cmd_priv(shost, cmd);
1920	if (ret < 0)
1921	kmem_cache_free(s: scsi_sense_cache, objp: cmd->sense_buffer);
1922	}
1923
1924	return ret;
1925	}
1926
1927	static void scsi_mq_exit_request(struct blk_mq_tag_set *set, struct request *rq,
1928	unsigned int hctx_idx)
1929	{
1930	struct Scsi_Host *shost = set->driver_data;
1931	struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
1932
1933	if (shost->hostt->exit_cmd_priv)
1934	shost->hostt->exit_cmd_priv(shost, cmd);
1935	kmem_cache_free(s: scsi_sense_cache, objp: cmd->sense_buffer);
1936	}
1937
1938
1939	static int scsi_mq_poll(struct blk_mq_hw_ctx *hctx, struct io_comp_batch *iob)
1940	{
1941	struct Scsi_Host *shost = hctx->driver_data;
1942
1943	if (shost->hostt->mq_poll)
1944	return shost->hostt->mq_poll(shost, hctx->queue_num);
1945
1946	return 0;
1947	}
1948
1949	static int scsi_init_hctx(struct blk_mq_hw_ctx *hctx, void *data,
1950	unsigned int hctx_idx)
1951	{
1952	struct Scsi_Host *shost = data;
1953
1954	hctx->driver_data = shost;
1955	return 0;
1956	}
1957
1958	static void scsi_map_queues(struct blk_mq_tag_set *set)
1959	{
1960	struct Scsi_Host *shost = container_of(set, struct Scsi_Host, tag_set);
1961
1962	if (shost->hostt->map_queues)
1963	return shost->hostt->map_queues(shost);
1964	blk_mq_map_queues(qmap: &set->map[HCTX_TYPE_DEFAULT]);
1965	}
1966
1967	void __scsi_init_queue(struct Scsi_Host *shost, struct request_queue *q)
1968	{
1969	struct device *dev = shost->dma_dev;
1970
1971	/*
1972	* this limit is imposed by hardware restrictions
1973	*/
1974	blk_queue_max_segments(q, min_t(unsigned short, shost->sg_tablesize,
1975	SG_MAX_SEGMENTS));
1976
1977	if (scsi_host_prot_dma(shost)) {
1978	shost->sg_prot_tablesize =
1979	min_not_zero(shost->sg_prot_tablesize,
1980	(unsigned short)SCSI_MAX_PROT_SG_SEGMENTS);
1981	BUG_ON(shost->sg_prot_tablesize < shost->sg_tablesize);
1982	blk_queue_max_integrity_segments(q, segs: shost->sg_prot_tablesize);
1983	}
1984
1985	blk_queue_max_hw_sectors(q, shost->max_sectors);
1986	blk_queue_segment_boundary(q, shost->dma_boundary);
1987	dma_set_seg_boundary(dev, mask: shost->dma_boundary);
1988
1989	blk_queue_max_segment_size(q, shost->max_segment_size);
1990	blk_queue_virt_boundary(q, shost->virt_boundary_mask);
1991	dma_set_max_seg_size(dev, size: queue_max_segment_size(q));
1992
1993	/*
1994	* Set a reasonable default alignment: The larger of 32-byte (dword),
1995	* which is a common minimum for HBAs, and the minimum DMA alignment,
1996	* which is set by the platform.
1997	*
1998	* Devices that require a bigger alignment can increase it later.
1999	*/
2000	blk_queue_dma_alignment(q, max(4, dma_get_cache_alignment()) - 1);
2001	}
2002	EXPORT_SYMBOL_GPL(__scsi_init_queue);
2003
2004	static const struct blk_mq_ops scsi_mq_ops_no_commit = {
2005	.get_budget = scsi_mq_get_budget,
2006	.put_budget = scsi_mq_put_budget,
2007	.queue_rq = scsi_queue_rq,
2008	.complete = scsi_complete,
2009	.timeout = scsi_timeout,
2010	#ifdef CONFIG_BLK_DEBUG_FS
2011	.show_rq = scsi_show_rq,
2012	#endif
2013	.init_request = scsi_mq_init_request,
2014	.exit_request = scsi_mq_exit_request,
2015	.cleanup_rq = scsi_cleanup_rq,
2016	.busy = scsi_mq_lld_busy,
2017	.map_queues = scsi_map_queues,
2018	.init_hctx = scsi_init_hctx,
2019	.poll = scsi_mq_poll,
2020	.set_rq_budget_token = scsi_mq_set_rq_budget_token,
2021	.get_rq_budget_token = scsi_mq_get_rq_budget_token,
2022	};
2023
2024
2025	static void scsi_commit_rqs(struct blk_mq_hw_ctx *hctx)
2026	{
2027	struct Scsi_Host *shost = hctx->driver_data;
2028
2029	shost->hostt->commit_rqs(shost, hctx->queue_num);
2030	}
2031
2032	static const struct blk_mq_ops scsi_mq_ops = {
2033	.get_budget = scsi_mq_get_budget,
2034	.put_budget = scsi_mq_put_budget,
2035	.queue_rq = scsi_queue_rq,
2036	.commit_rqs = scsi_commit_rqs,
2037	.complete = scsi_complete,
2038	.timeout = scsi_timeout,
2039	#ifdef CONFIG_BLK_DEBUG_FS
2040	.show_rq = scsi_show_rq,
2041	#endif
2042	.init_request = scsi_mq_init_request,
2043	.exit_request = scsi_mq_exit_request,
2044	.cleanup_rq = scsi_cleanup_rq,
2045	.busy = scsi_mq_lld_busy,
2046	.map_queues = scsi_map_queues,
2047	.init_hctx = scsi_init_hctx,
2048	.poll = scsi_mq_poll,
2049	.set_rq_budget_token = scsi_mq_set_rq_budget_token,
2050	.get_rq_budget_token = scsi_mq_get_rq_budget_token,
2051	};
2052
2053	int scsi_mq_setup_tags(struct Scsi_Host *shost)
2054	{
2055	unsigned int cmd_size, sgl_size;
2056	struct blk_mq_tag_set *tag_set = &shost->tag_set;
2057
2058	sgl_size = max_t(unsigned int, sizeof(struct scatterlist),
2059	scsi_mq_inline_sgl_size(shost));
2060	cmd_size = sizeof(struct scsi_cmnd) + shost->hostt->cmd_size + sgl_size;
2061	if (scsi_host_get_prot(shost))
2062	cmd_size += sizeof(struct scsi_data_buffer) +
2063	sizeof(struct scatterlist) * SCSI_INLINE_PROT_SG_CNT;
2064
2065	memset(tag_set, 0, sizeof(*tag_set));
2066	if (shost->hostt->commit_rqs)
2067	tag_set->ops = &scsi_mq_ops;
2068	else
2069	tag_set->ops = &scsi_mq_ops_no_commit;
2070	tag_set->nr_hw_queues = shost->nr_hw_queues ? : 1;
2071	tag_set->nr_maps = shost->nr_maps ? : 1;
2072	tag_set->queue_depth = shost->can_queue;
2073	tag_set->cmd_size = cmd_size;
2074	tag_set->numa_node = dev_to_node(dev: shost->dma_dev);
2075	tag_set->flags = BLK_MQ_F_SHOULD_MERGE;
2076	tag_set->flags |=
2077	BLK_ALLOC_POLICY_TO_MQ_FLAG(shost->hostt->tag_alloc_policy);
2078	if (shost->queuecommand_may_block)
2079	tag_set->flags |= BLK_MQ_F_BLOCKING;
2080	tag_set->driver_data = shost;
2081	if (shost->host_tagset)
2082	tag_set->flags |= BLK_MQ_F_TAG_HCTX_SHARED;
2083
2084	return blk_mq_alloc_tag_set(set: tag_set);
2085	}
2086
2087	void scsi_mq_free_tags(struct kref *kref)
2088	{
2089	struct Scsi_Host *shost = container_of(kref, typeof(*shost),
2090	tagset_refcnt);
2091
2092	blk_mq_free_tag_set(set: &shost->tag_set);
2093	complete(&shost->tagset_freed);
2094	}
2095
2096	/**
2097	* scsi_device_from_queue - return sdev associated with a request_queue
2098	* @q: The request queue to return the sdev from
2099	*
2100	* Return the sdev associated with a request queue or NULL if the
2101	* request_queue does not reference a SCSI device.
2102	*/
2103	struct scsi_device *scsi_device_from_queue(struct request_queue *q)
2104	{
2105	struct scsi_device *sdev = NULL;
2106
2107	if (q->mq_ops == &scsi_mq_ops_no_commit ||
2108	q->mq_ops == &scsi_mq_ops)
2109	sdev = q->queuedata;
2110	if (!sdev || !get_device(dev: &sdev->sdev_gendev))
2111	sdev = NULL;
2112
2113	return sdev;
2114	}
2115	/*
2116	* pktcdvd should have been integrated into the SCSI layers, but for historical
2117	* reasons like the old IDE driver it isn't. This export allows it to safely
2118	* probe if a given device is a SCSI one and only attach to that.
2119	*/
2120	#ifdef CONFIG_CDROM_PKTCDVD_MODULE
2121	EXPORT_SYMBOL_GPL(scsi_device_from_queue);
2122	#endif
2123
2124	/**
2125	* scsi_block_requests - Utility function used by low-level drivers to prevent
2126	* further commands from being queued to the device.
2127	* @shost: host in question
2128	*
2129	* There is no timer nor any other means by which the requests get unblocked
2130	* other than the low-level driver calling scsi_unblock_requests().
2131	*/
2132	void scsi_block_requests(struct Scsi_Host *shost)
2133	{
2134	shost->host_self_blocked = 1;
2135	}
2136	EXPORT_SYMBOL(scsi_block_requests);
2137
2138	/**
2139	* scsi_unblock_requests - Utility function used by low-level drivers to allow
2140	* further commands to be queued to the device.
2141	* @shost: host in question
2142	*
2143	* There is no timer nor any other means by which the requests get unblocked
2144	* other than the low-level driver calling scsi_unblock_requests(). This is done
2145	* as an API function so that changes to the internals of the scsi mid-layer
2146	* won't require wholesale changes to drivers that use this feature.
2147	*/
2148	void scsi_unblock_requests(struct Scsi_Host *shost)
2149	{
2150	shost->host_self_blocked = 0;
2151	scsi_run_host_queues(shost);
2152	}
2153	EXPORT_SYMBOL(scsi_unblock_requests);
2154
2155	void scsi_exit_queue(void)
2156	{
2157	kmem_cache_destroy(s: scsi_sense_cache);
2158	}
2159
2160	/**
2161	* scsi_mode_select - issue a mode select
2162	* @sdev: SCSI device to be queried
2163	* @pf: Page format bit (1 == standard, 0 == vendor specific)
2164	* @sp: Save page bit (0 == don't save, 1 == save)
2165	* @buffer: request buffer (may not be smaller than eight bytes)
2166	* @len: length of request buffer.
2167	* @timeout: command timeout
2168	* @retries: number of retries before failing
2169	* @data: returns a structure abstracting the mode header data
2170	* @sshdr: place to put sense data (or NULL if no sense to be collected).
2171	* must be SCSI_SENSE_BUFFERSIZE big.
2172	*
2173	* Returns zero if successful; negative error number or scsi
2174	* status on error
2175	*
2176	*/
2177	int scsi_mode_select(struct scsi_device *sdev, int pf, int sp,
2178	unsigned char *buffer, int len, int timeout, int retries,
2179	struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
2180	{
2181	unsigned char cmd[10];
2182	unsigned char *real_buffer;
2183	const struct scsi_exec_args exec_args = {
2184	.sshdr = sshdr,
2185	};
2186	int ret;
2187
2188	memset(cmd, 0, sizeof(cmd));
2189	cmd[1] = (pf ? 0x10 : 0) | (sp ? 0x01 : 0);
2190
2191	/*
2192	* Use MODE SELECT(10) if the device asked for it or if the mode page
2193	* and the mode select header cannot fit within the maximumm 255 bytes
2194	* of the MODE SELECT(6) command.
2195	*/
2196	if (sdev->use_10_for_ms ||
2197	len + 4 > 255 ||
2198	data->block_descriptor_length > 255) {
2199	if (len > 65535 - 8)
2200	return -EINVAL;
2201	real_buffer = kmalloc(size: 8 + len, GFP_KERNEL);
2202	if (!real_buffer)
2203	return -ENOMEM;
2204	memcpy(real_buffer + 8, buffer, len);
2205	len += 8;
2206	real_buffer[0] = 0;
2207	real_buffer[1] = 0;
2208	real_buffer[2] = data->medium_type;
2209	real_buffer[3] = data->device_specific;
2210	real_buffer[4] = data->longlba ? 0x01 : 0;
2211	real_buffer[5] = 0;
2212	put_unaligned_be16(val: data->block_descriptor_length,
2213	p: &real_buffer[6]);
2214
2215	cmd[0] = MODE_SELECT_10;
2216	put_unaligned_be16(val: len, p: &cmd[7]);
2217	} else {
2218	if (data->longlba)
2219	return -EINVAL;
2220
2221	real_buffer = kmalloc(size: 4 + len, GFP_KERNEL);
2222	if (!real_buffer)
2223	return -ENOMEM;
2224	memcpy(real_buffer + 4, buffer, len);
2225	len += 4;
2226	real_buffer[0] = 0;
2227	real_buffer[1] = data->medium_type;
2228	real_buffer[2] = data->device_specific;
2229	real_buffer[3] = data->block_descriptor_length;
2230
2231	cmd[0] = MODE_SELECT;
2232	cmd[4] = len;
2233	}
2234
2235	ret = scsi_execute_cmd(sdev, cmd, REQ_OP_DRV_OUT, real_buffer, len,
2236	timeout, retries, &exec_args);
2237	kfree(objp: real_buffer);
2238	return ret;
2239	}
2240	EXPORT_SYMBOL_GPL(scsi_mode_select);
2241
2242	/**
2243	* scsi_mode_sense - issue a mode sense, falling back from 10 to six bytes if necessary.
2244	* @sdev: SCSI device to be queried
2245	* @dbd: set to prevent mode sense from returning block descriptors
2246	* @modepage: mode page being requested
2247	* @subpage: sub-page of the mode page being requested
2248	* @buffer: request buffer (may not be smaller than eight bytes)
2249	* @len: length of request buffer.
2250	* @timeout: command timeout
2251	* @retries: number of retries before failing
2252	* @data: returns a structure abstracting the mode header data
2253	* @sshdr: place to put sense data (or NULL if no sense to be collected).
2254	* must be SCSI_SENSE_BUFFERSIZE big.
2255	*
2256	* Returns zero if successful, or a negative error number on failure
2257	*/
2258	int
2259	scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage, int subpage,
2260	unsigned char *buffer, int len, int timeout, int retries,
2261	struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
2262	{
2263	unsigned char cmd[12];
2264	int use_10_for_ms;
2265	int header_length;
2266	int result;
2267	struct scsi_sense_hdr my_sshdr;
2268	struct scsi_failure failure_defs[] = {
2269	{
2270	.sense = UNIT_ATTENTION,
2271	.asc = SCMD_FAILURE_ASC_ANY,
2272	.ascq = SCMD_FAILURE_ASCQ_ANY,
2273	.allowed = retries,
2274	.result = SAM_STAT_CHECK_CONDITION,
2275	},
2276	{}
2277	};
2278	struct scsi_failures failures = {
2279	.failure_definitions = failure_defs,
2280	};
2281	const struct scsi_exec_args exec_args = {
2282	/* caller might not be interested in sense, but we need it */
2283	.sshdr = sshdr ? : &my_sshdr,
2284	.failures = &failures,
2285	};
2286
2287	memset(data, 0, sizeof(*data));
2288	memset(&cmd[0], 0, 12);
2289
2290	dbd = sdev->set_dbd_for_ms ? 8 : dbd;
2291	cmd[1] = dbd & 0x18; /* allows DBD and LLBA bits */
2292	cmd[2] = modepage;
2293	cmd[3] = subpage;
2294
2295	sshdr = exec_args.sshdr;
2296
2297	retry:
2298	use_10_for_ms = sdev->use_10_for_ms || len > 255;
2299
2300	if (use_10_for_ms) {
2301	if (len < 8 || len > 65535)
2302	return -EINVAL;
2303
2304	cmd[0] = MODE_SENSE_10;
2305	put_unaligned_be16(val: len, p: &cmd[7]);
2306	header_length = 8;
2307	} else {
2308	if (len < 4)
2309	return -EINVAL;
2310
2311	cmd[0] = MODE_SENSE;
2312	cmd[4] = len;
2313	header_length = 4;
2314	}
2315
2316	memset(buffer, 0, len);
2317
2318	result = scsi_execute_cmd(sdev, cmd, REQ_OP_DRV_IN, buffer, len,
2319	timeout, retries, &exec_args);
2320	if (result < 0)
2321	return result;
2322
2323	/* This code looks awful: what it's doing is making sure an
2324	* ILLEGAL REQUEST sense return identifies the actual command
2325	* byte as the problem. MODE_SENSE commands can return
2326	* ILLEGAL REQUEST if the code page isn't supported */
2327
2328	if (!scsi_status_is_good(status: result)) {
2329	if (scsi_sense_valid(sshdr)) {
2330	if ((sshdr->sense_key == ILLEGAL_REQUEST) &&
2331	(sshdr->asc == 0x20) && (sshdr->ascq == 0)) {
2332	/*
2333	* Invalid command operation code: retry using
2334	* MODE SENSE(6) if this was a MODE SENSE(10)
2335	* request, except if the request mode page is
2336	* too large for MODE SENSE single byte
2337	* allocation length field.
2338	*/
2339	if (use_10_for_ms) {
2340	if (len > 255)
2341	return -EIO;
2342	sdev->use_10_for_ms = 0;
2343	goto retry;
2344	}
2345	}
2346	}
2347	return -EIO;
2348	}
2349	if (unlikely(buffer[0] == 0x86 && buffer[1] == 0x0b &&
2350	(modepage == 6 || modepage == 8))) {
2351	/* Initio breakage? */
2352	header_length = 0;
2353	data->length = 13;
2354	data->medium_type = 0;
2355	data->device_specific = 0;
2356	data->longlba = 0;
2357	data->block_descriptor_length = 0;
2358	} else if (use_10_for_ms) {
2359	data->length = get_unaligned_be16(p: &buffer[0]) + 2;
2360	data->medium_type = buffer[2];
2361	data->device_specific = buffer[3];
2362	data->longlba = buffer[4] & 0x01;
2363	data->block_descriptor_length = get_unaligned_be16(p: &buffer[6]);
2364	} else {
2365	data->length = buffer[0] + 1;
2366	data->medium_type = buffer[1];
2367	data->device_specific = buffer[2];
2368	data->block_descriptor_length = buffer[3];
2369	}
2370	data->header_length = header_length;
2371
2372	return 0;
2373	}
2374	EXPORT_SYMBOL(scsi_mode_sense);
2375
2376	/**
2377	* scsi_test_unit_ready - test if unit is ready
2378	* @sdev: scsi device to change the state of.
2379	* @timeout: command timeout
2380	* @retries: number of retries before failing
2381	* @sshdr: outpout pointer for decoded sense information.
2382	*
2383	* Returns zero if unsuccessful or an error if TUR failed. For
2384	* removable media, UNIT_ATTENTION sets ->changed flag.
2385	**/
2386	int
2387	scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries,
2388	struct scsi_sense_hdr *sshdr)
2389	{
2390	char cmd[] = {
2391	TEST_UNIT_READY, 0, 0, 0, 0, 0,
2392	};
2393	const struct scsi_exec_args exec_args = {
2394	.sshdr = sshdr,
2395	};
2396	int result;
2397
2398	/* try to eat the UNIT_ATTENTION if there are enough retries */
2399	do {
2400	result = scsi_execute_cmd(sdev, cmd, REQ_OP_DRV_IN, NULL, 0,
2401	timeout, 1, &exec_args);
2402	if (sdev->removable && result > 0 && scsi_sense_valid(sshdr) &&
2403	sshdr->sense_key == UNIT_ATTENTION)
2404	sdev->changed = 1;
2405	} while (result > 0 && scsi_sense_valid(sshdr) &&
2406	sshdr->sense_key == UNIT_ATTENTION && --retries);
2407
2408	return result;
2409	}
2410	EXPORT_SYMBOL(scsi_test_unit_ready);
2411
2412	/**
2413	* scsi_device_set_state - Take the given device through the device state model.
2414	* @sdev: scsi device to change the state of.
2415	* @state: state to change to.
2416	*
2417	* Returns zero if successful or an error if the requested
2418	* transition is illegal.
2419	*/
2420	int
2421	scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
2422	{
2423	enum scsi_device_state oldstate = sdev->sdev_state;
2424
2425	if (state == oldstate)
2426	return 0;
2427
2428	switch (state) {
2429	case SDEV_CREATED:
2430	switch (oldstate) {
2431	case SDEV_CREATED_BLOCK:
2432	break;
2433	default:
2434	goto illegal;
2435	}
2436	break;
2437
2438	case SDEV_RUNNING:
2439	switch (oldstate) {
2440	case SDEV_CREATED:
2441	case SDEV_OFFLINE:
2442	case SDEV_TRANSPORT_OFFLINE:
2443	case SDEV_QUIESCE:
2444	case SDEV_BLOCK:
2445	break;
2446	default:
2447	goto illegal;
2448	}
2449	break;
2450
2451	case SDEV_QUIESCE:
2452	switch (oldstate) {
2453	case SDEV_RUNNING:
2454	case SDEV_OFFLINE:
2455	case SDEV_TRANSPORT_OFFLINE:
2456	break;
2457	default:
2458	goto illegal;
2459	}
2460	break;
2461
2462	case SDEV_OFFLINE:
2463	case SDEV_TRANSPORT_OFFLINE:
2464	switch (oldstate) {
2465	case SDEV_CREATED:
2466	case SDEV_RUNNING:
2467	case SDEV_QUIESCE:
2468	case SDEV_BLOCK:
2469	break;
2470	default:
2471	goto illegal;
2472	}
2473	break;
2474
2475	case SDEV_BLOCK:
2476	switch (oldstate) {
2477	case SDEV_RUNNING:
2478	case SDEV_CREATED_BLOCK:
2479	case SDEV_QUIESCE:
2480	case SDEV_OFFLINE:
2481	break;
2482	default:
2483	goto illegal;
2484	}
2485	break;
2486
2487	case SDEV_CREATED_BLOCK:
2488	switch (oldstate) {
2489	case SDEV_CREATED:
2490	break;
2491	default:
2492	goto illegal;
2493	}
2494	break;
2495
2496	case SDEV_CANCEL:
2497	switch (oldstate) {
2498	case SDEV_CREATED:
2499	case SDEV_RUNNING:
2500	case SDEV_QUIESCE:
2501	case SDEV_OFFLINE:
2502	case SDEV_TRANSPORT_OFFLINE:
2503	break;
2504	default:
2505	goto illegal;
2506	}
2507	break;
2508
2509	case SDEV_DEL:
2510	switch (oldstate) {
2511	case SDEV_CREATED:
2512	case SDEV_RUNNING:
2513	case SDEV_OFFLINE:
2514	case SDEV_TRANSPORT_OFFLINE:
2515	case SDEV_CANCEL:
2516	case SDEV_BLOCK:
2517	case SDEV_CREATED_BLOCK:
2518	break;
2519	default:
2520	goto illegal;
2521	}
2522	break;
2523
2524	}
2525	sdev->offline_already = false;
2526	sdev->sdev_state = state;
2527	return 0;
2528
2529	illegal:
2530	SCSI_LOG_ERROR_RECOVERY(1,
2531	sdev_printk(KERN_ERR, sdev,
2532	"Illegal state transition %s->%s",
2533	scsi_device_state_name(oldstate),
2534	scsi_device_state_name(state))
2535	);
2536	return -EINVAL;
2537	}
2538	EXPORT_SYMBOL(scsi_device_set_state);
2539
2540	/**
2541	* scsi_evt_emit - emit a single SCSI device uevent
2542	* @sdev: associated SCSI device
2543	* @evt: event to emit
2544	*
2545	* Send a single uevent (scsi_event) to the associated scsi_device.
2546	*/
2547	static void scsi_evt_emit(struct scsi_device *sdev, struct scsi_event *evt)
2548	{
2549	int idx = 0;
2550	char *envp[3];
2551
2552	switch (evt->evt_type) {
2553	case SDEV_EVT_MEDIA_CHANGE:
2554	envp[idx++] = "SDEV_MEDIA_CHANGE=1";
2555	break;
2556	case SDEV_EVT_INQUIRY_CHANGE_REPORTED:
2557	scsi_rescan_device(sdev);
2558	envp[idx++] = "SDEV_UA=INQUIRY_DATA_HAS_CHANGED";
2559	break;
2560	case SDEV_EVT_CAPACITY_CHANGE_REPORTED:
2561	envp[idx++] = "SDEV_UA=CAPACITY_DATA_HAS_CHANGED";
2562	break;
2563	case SDEV_EVT_SOFT_THRESHOLD_REACHED_REPORTED:
2564	envp[idx++] = "SDEV_UA=THIN_PROVISIONING_SOFT_THRESHOLD_REACHED";
2565	break;
2566	case SDEV_EVT_MODE_PARAMETER_CHANGE_REPORTED:
2567	envp[idx++] = "SDEV_UA=MODE_PARAMETERS_CHANGED";
2568	break;
2569	case SDEV_EVT_LUN_CHANGE_REPORTED:
2570	envp[idx++] = "SDEV_UA=REPORTED_LUNS_DATA_HAS_CHANGED";
2571	break;
2572	case SDEV_EVT_ALUA_STATE_CHANGE_REPORTED:
2573	envp[idx++] = "SDEV_UA=ASYMMETRIC_ACCESS_STATE_CHANGED";
2574	break;
2575	case SDEV_EVT_POWER_ON_RESET_OCCURRED:
2576	envp[idx++] = "SDEV_UA=POWER_ON_RESET_OCCURRED";
2577	break;
2578	default:
2579	/* do nothing */
2580	break;
2581	}
2582
2583	envp[idx++] = NULL;
2584
2585	kobject_uevent_env(kobj: &sdev->sdev_gendev.kobj, action: KOBJ_CHANGE, envp);
2586	}
2587
2588	/**
2589	* scsi_evt_thread - send a uevent for each scsi event
2590	* @work: work struct for scsi_device
2591	*
2592	* Dispatch queued events to their associated scsi_device kobjects
2593	* as uevents.
2594	*/
2595	void scsi_evt_thread(struct work_struct *work)
2596	{
2597	struct scsi_device *sdev;
2598	enum scsi_device_event evt_type;
2599	LIST_HEAD(event_list);
2600
2601	sdev = container_of(work, struct scsi_device, event_work);
2602
2603	for (evt_type = SDEV_EVT_FIRST; evt_type <= SDEV_EVT_LAST; evt_type++)
2604	if (test_and_clear_bit(nr: evt_type, addr: sdev->pending_events))
2605	sdev_evt_send_simple(sdev, evt_type, GFP_KERNEL);
2606
2607	while (1) {
2608	struct scsi_event *evt;
2609	struct list_head *this, *tmp;
2610	unsigned long flags;
2611
2612	spin_lock_irqsave(&sdev->list_lock, flags);
2613	list_splice_init(list: &sdev->event_list, head: &event_list);
2614	spin_unlock_irqrestore(lock: &sdev->list_lock, flags);
2615
2616	if (list_empty(head: &event_list))
2617	break;
2618
2619	list_for_each_safe(this, tmp, &event_list) {
2620	evt = list_entry(this, struct scsi_event, node);
2621	list_del(entry: &evt->node);
2622	scsi_evt_emit(sdev, evt);
2623	kfree(objp: evt);
2624	}
2625	}
2626	}
2627
2628	/**
2629	* sdev_evt_send - send asserted event to uevent thread
2630	* @sdev: scsi_device event occurred on
2631	* @evt: event to send
2632	*
2633	* Assert scsi device event asynchronously.
2634	*/
2635	void sdev_evt_send(struct scsi_device *sdev, struct scsi_event *evt)
2636	{
2637	unsigned long flags;
2638
2639	#if 0
2640	/* FIXME: currently this check eliminates all media change events
2641	* for polled devices. Need to update to discriminate between AN
2642	* and polled events */
2643	if (!test_bit(evt->evt_type, sdev->supported_events)) {
2644	kfree(evt);
2645	return;
2646	}
2647	#endif
2648
2649	spin_lock_irqsave(&sdev->list_lock, flags);
2650	list_add_tail(new: &evt->node, head: &sdev->event_list);
2651	schedule_work(work: &sdev->event_work);
2652	spin_unlock_irqrestore(lock: &sdev->list_lock, flags);
2653	}
2654	EXPORT_SYMBOL_GPL(sdev_evt_send);
2655
2656	/**
2657	* sdev_evt_alloc - allocate a new scsi event
2658	* @evt_type: type of event to allocate
2659	* @gfpflags: GFP flags for allocation
2660	*
2661	* Allocates and returns a new scsi_event.
2662	*/
2663	struct scsi_event *sdev_evt_alloc(enum scsi_device_event evt_type,
2664	gfp_t gfpflags)
2665	{
2666	struct scsi_event *evt = kzalloc(size: sizeof(struct scsi_event), flags: gfpflags);
2667	if (!evt)
2668	return NULL;
2669
2670	evt->evt_type = evt_type;
2671	INIT_LIST_HEAD(list: &evt->node);
2672
2673	/* evt_type-specific initialization, if any */
2674	switch (evt_type) {
2675	case SDEV_EVT_MEDIA_CHANGE:
2676	case SDEV_EVT_INQUIRY_CHANGE_REPORTED:
2677	case SDEV_EVT_CAPACITY_CHANGE_REPORTED:
2678	case SDEV_EVT_SOFT_THRESHOLD_REACHED_REPORTED:
2679	case SDEV_EVT_MODE_PARAMETER_CHANGE_REPORTED:
2680	case SDEV_EVT_LUN_CHANGE_REPORTED:
2681	case SDEV_EVT_ALUA_STATE_CHANGE_REPORTED:
2682	case SDEV_EVT_POWER_ON_RESET_OCCURRED:
2683	default:
2684	/* do nothing */
2685	break;
2686	}
2687
2688	return evt;
2689	}
2690	EXPORT_SYMBOL_GPL(sdev_evt_alloc);
2691
2692	/**
2693	* sdev_evt_send_simple - send asserted event to uevent thread
2694	* @sdev: scsi_device event occurred on
2695	* @evt_type: type of event to send
2696	* @gfpflags: GFP flags for allocation
2697	*
2698	* Assert scsi device event asynchronously, given an event type.
2699	*/
2700	void sdev_evt_send_simple(struct scsi_device *sdev,
2701	enum scsi_device_event evt_type, gfp_t gfpflags)
2702	{
2703	struct scsi_event *evt = sdev_evt_alloc(evt_type, gfpflags);
2704	if (!evt) {
2705	sdev_printk(KERN_ERR, sdev, "event %d eaten due to OOM\n",
2706	evt_type);
2707	return;
2708	}
2709
2710	sdev_evt_send(sdev, evt);
2711	}
2712	EXPORT_SYMBOL_GPL(sdev_evt_send_simple);
2713
2714	/**
2715	* scsi_device_quiesce - Block all commands except power management.
2716	* @sdev: scsi device to quiesce.
2717	*
2718	* This works by trying to transition to the SDEV_QUIESCE state
2719	* (which must be a legal transition). When the device is in this
2720	* state, only power management requests will be accepted, all others will
2721	* be deferred.
2722	*
2723	* Must be called with user context, may sleep.
2724	*
2725	* Returns zero if unsuccessful or an error if not.
2726	*/
2727	int
2728	scsi_device_quiesce(struct scsi_device *sdev)
2729	{
2730	struct request_queue *q = sdev->request_queue;
2731	int err;
2732
2733	/*
2734	* It is allowed to call scsi_device_quiesce() multiple times from
2735	* the same context but concurrent scsi_device_quiesce() calls are
2736	* not allowed.
2737	*/
2738	WARN_ON_ONCE(sdev->quiesced_by && sdev->quiesced_by != current);
2739
2740	if (sdev->quiesced_by == current)
2741	return 0;
2742
2743	blk_set_pm_only(q);
2744
2745	blk_mq_freeze_queue(q);
2746	/*
2747	* Ensure that the effect of blk_set_pm_only() will be visible
2748	* for percpu_ref_tryget() callers that occur after the queue
2749	* unfreeze even if the queue was already frozen before this function
2750	* was called. See also https://lwn.net/Articles/573497/.
2751	*/
2752	synchronize_rcu();
2753	blk_mq_unfreeze_queue(q);
2754
2755	mutex_lock(&sdev->state_mutex);
2756	err = scsi_device_set_state(sdev, SDEV_QUIESCE);
2757	if (err == 0)
2758	sdev->quiesced_by = current;
2759	else
2760	blk_clear_pm_only(q);
2761	mutex_unlock(lock: &sdev->state_mutex);
2762
2763	return err;
2764	}
2765	EXPORT_SYMBOL(scsi_device_quiesce);
2766
2767	/**
2768	* scsi_device_resume - Restart user issued commands to a quiesced device.
2769	* @sdev: scsi device to resume.
2770	*
2771	* Moves the device from quiesced back to running and restarts the
2772	* queues.
2773	*
2774	* Must be called with user context, may sleep.
2775	*/
2776	void scsi_device_resume(struct scsi_device *sdev)
2777	{
2778	/* check if the device state was mutated prior to resume, and if
2779	* so assume the state is being managed elsewhere (for example
2780	* device deleted during suspend)
2781	*/
2782	mutex_lock(&sdev->state_mutex);
2783	if (sdev->sdev_state == SDEV_QUIESCE)
2784	scsi_device_set_state(sdev, SDEV_RUNNING);
2785	if (sdev->quiesced_by) {
2786	sdev->quiesced_by = NULL;
2787	blk_clear_pm_only(q: sdev->request_queue);
2788	}
2789	mutex_unlock(lock: &sdev->state_mutex);
2790	}
2791	EXPORT_SYMBOL(scsi_device_resume);
2792
2793	static void
2794	device_quiesce_fn(struct scsi_device *sdev, void *data)
2795	{
2796	scsi_device_quiesce(sdev);
2797	}
2798
2799	void
2800	scsi_target_quiesce(struct scsi_target *starget)
2801	{
2802	starget_for_each_device(starget, NULL, fn: device_quiesce_fn);
2803	}
2804	EXPORT_SYMBOL(scsi_target_quiesce);
2805
2806	static void
2807	device_resume_fn(struct scsi_device *sdev, void *data)
2808	{
2809	scsi_device_resume(sdev);
2810	}
2811
2812	void
2813	scsi_target_resume(struct scsi_target *starget)
2814	{
2815	starget_for_each_device(starget, NULL, fn: device_resume_fn);
2816	}
2817	EXPORT_SYMBOL(scsi_target_resume);
2818
2819	static int __scsi_internal_device_block_nowait(struct scsi_device *sdev)
2820	{
2821	if (scsi_device_set_state(sdev, SDEV_BLOCK))
2822	return scsi_device_set_state(sdev, SDEV_CREATED_BLOCK);
2823
2824	return 0;
2825	}
2826
2827	void scsi_start_queue(struct scsi_device *sdev)
2828	{
2829	if (cmpxchg(&sdev->queue_stopped, 1, 0))
2830	blk_mq_unquiesce_queue(q: sdev->request_queue);
2831	}
2832
2833	static void scsi_stop_queue(struct scsi_device *sdev)
2834	{
2835	/*
2836	* The atomic variable of ->queue_stopped covers that
2837	* blk_mq_quiesce_queue* is balanced with blk_mq_unquiesce_queue.
2838	*
2839	* The caller needs to wait until quiesce is done.
2840	*/
2841	if (!cmpxchg(&sdev->queue_stopped, 0, 1))
2842	blk_mq_quiesce_queue_nowait(q: sdev->request_queue);
2843	}
2844
2845	/**
2846	* scsi_internal_device_block_nowait - try to transition to the SDEV_BLOCK state
2847	* @sdev: device to block
2848	*
2849	* Pause SCSI command processing on the specified device. Does not sleep.
2850	*
2851	* Returns zero if successful or a negative error code upon failure.
2852	*
2853	* Notes:
2854	* This routine transitions the device to the SDEV_BLOCK state (which must be
2855	* a legal transition). When the device is in this state, command processing
2856	* is paused until the device leaves the SDEV_BLOCK state. See also
2857	* scsi_internal_device_unblock_nowait().
2858	*/
2859	int scsi_internal_device_block_nowait(struct scsi_device *sdev)
2860	{
2861	int ret = __scsi_internal_device_block_nowait(sdev);
2862
2863	/*
2864	* The device has transitioned to SDEV_BLOCK. Stop the
2865	* block layer from calling the midlayer with this device's
2866	* request queue.
2867	*/
2868	if (!ret)
2869	scsi_stop_queue(sdev);
2870	return ret;
2871	}
2872	EXPORT_SYMBOL_GPL(scsi_internal_device_block_nowait);
2873
2874	/**
2875	* scsi_device_block - try to transition to the SDEV_BLOCK state
2876	* @sdev: device to block
2877	* @data: dummy argument, ignored
2878	*
2879	* Pause SCSI command processing on the specified device. Callers must wait
2880	* until all ongoing scsi_queue_rq() calls have finished after this function
2881	* returns.
2882	*
2883	* Note:
2884	* This routine transitions the device to the SDEV_BLOCK state (which must be
2885	* a legal transition). When the device is in this state, command processing
2886	* is paused until the device leaves the SDEV_BLOCK state. See also
2887	* scsi_internal_device_unblock().
2888	*/
2889	static void scsi_device_block(struct scsi_device *sdev, void *data)
2890	{
2891	int err;
2892	enum scsi_device_state state;
2893
2894	mutex_lock(&sdev->state_mutex);
2895	err = __scsi_internal_device_block_nowait(sdev);
2896	state = sdev->sdev_state;
2897	if (err == 0)
2898	/*
2899	* scsi_stop_queue() must be called with the state_mutex
2900	* held. Otherwise a simultaneous scsi_start_queue() call
2901	* might unquiesce the queue before we quiesce it.
2902	*/
2903	scsi_stop_queue(sdev);
2904
2905	mutex_unlock(lock: &sdev->state_mutex);
2906
2907	WARN_ONCE(err, "%s: failed to block %s in state %d\n",
2908	__func__, dev_name(&sdev->sdev_gendev), state);
2909	}
2910
2911	/**
2912	* scsi_internal_device_unblock_nowait - resume a device after a block request
2913	* @sdev: device to resume
2914	* @new_state: state to set the device to after unblocking
2915	*
2916	* Restart the device queue for a previously suspended SCSI device. Does not
2917	* sleep.
2918	*
2919	* Returns zero if successful or a negative error code upon failure.
2920	*
2921	* Notes:
2922	* This routine transitions the device to the SDEV_RUNNING state or to one of
2923	* the offline states (which must be a legal transition) allowing the midlayer
2924	* to goose the queue for this device.
2925	*/
2926	int scsi_internal_device_unblock_nowait(struct scsi_device *sdev,
2927	enum scsi_device_state new_state)
2928	{
2929	switch (new_state) {
2930	case SDEV_RUNNING:
2931	case SDEV_TRANSPORT_OFFLINE:
2932	break;
2933	default:
2934	return -EINVAL;
2935	}
2936
2937	/*
2938	* Try to transition the scsi device to SDEV_RUNNING or one of the
2939	* offlined states and goose the device queue if successful.
2940	*/
2941	switch (sdev->sdev_state) {
2942	case SDEV_BLOCK:
2943	case SDEV_TRANSPORT_OFFLINE:
2944	sdev->sdev_state = new_state;
2945	break;
2946	case SDEV_CREATED_BLOCK:
2947	if (new_state == SDEV_TRANSPORT_OFFLINE ||
2948	new_state == SDEV_OFFLINE)
2949	sdev->sdev_state = new_state;
2950	else
2951	sdev->sdev_state = SDEV_CREATED;
2952	break;
2953	case SDEV_CANCEL:
2954	case SDEV_OFFLINE:
2955	break;
2956	default:
2957	return -EINVAL;
2958	}
2959	scsi_start_queue(sdev);
2960
2961	return 0;
2962	}
2963	EXPORT_SYMBOL_GPL(scsi_internal_device_unblock_nowait);
2964
2965	/**
2966	* scsi_internal_device_unblock - resume a device after a block request
2967	* @sdev: device to resume
2968	* @new_state: state to set the device to after unblocking
2969	*
2970	* Restart the device queue for a previously suspended SCSI device. May sleep.
2971	*
2972	* Returns zero if successful or a negative error code upon failure.
2973	*
2974	* Notes:
2975	* This routine transitions the device to the SDEV_RUNNING state or to one of
2976	* the offline states (which must be a legal transition) allowing the midlayer
2977	* to goose the queue for this device.
2978	*/
2979	static int scsi_internal_device_unblock(struct scsi_device *sdev,
2980	enum scsi_device_state new_state)
2981	{
2982	int ret;
2983
2984	mutex_lock(&sdev->state_mutex);
2985	ret = scsi_internal_device_unblock_nowait(sdev, new_state);
2986	mutex_unlock(lock: &sdev->state_mutex);
2987
2988	return ret;
2989	}
2990
2991	static int
2992	target_block(struct device *dev, void *data)
2993	{
2994	if (scsi_is_target_device(dev))
2995	starget_for_each_device(to_scsi_target(dev), NULL,
2996	fn: scsi_device_block);
2997	return 0;
2998	}
2999
3000	/**
3001	* scsi_block_targets - transition all SCSI child devices to SDEV_BLOCK state
3002	* @dev: a parent device of one or more scsi_target devices
3003	* @shost: the Scsi_Host to which this device belongs
3004	*
3005	* Iterate over all children of @dev, which should be scsi_target devices,
3006	* and switch all subordinate scsi devices to SDEV_BLOCK state. Wait for
3007	* ongoing scsi_queue_rq() calls to finish. May sleep.
3008	*
3009	* Note:
3010	* @dev must not itself be a scsi_target device.
3011	*/
3012	void
3013	scsi_block_targets(struct Scsi_Host *shost, struct device *dev)
3014	{
3015	WARN_ON_ONCE(scsi_is_target_device(dev));
3016	device_for_each_child(dev, NULL, fn: target_block);
3017	blk_mq_wait_quiesce_done(set: &shost->tag_set);
3018	}
3019	EXPORT_SYMBOL_GPL(scsi_block_targets);
3020
3021	static void
3022	device_unblock(struct scsi_device *sdev, void *data)
3023	{
3024	scsi_internal_device_unblock(sdev, new_state: *(enum scsi_device_state *)data);
3025	}
3026
3027	static int
3028	target_unblock(struct device *dev, void *data)
3029	{
3030	if (scsi_is_target_device(dev))
3031	starget_for_each_device(to_scsi_target(dev), data,
3032	fn: device_unblock);
3033	return 0;
3034	}
3035
3036	void
3037	scsi_target_unblock(struct device *dev, enum scsi_device_state new_state)
3038	{
3039	if (scsi_is_target_device(dev))
3040	starget_for_each_device(to_scsi_target(dev), &new_state,
3041	fn: device_unblock);
3042	else
3043	device_for_each_child(dev, data: &new_state, fn: target_unblock);
3044	}
3045	EXPORT_SYMBOL_GPL(scsi_target_unblock);
3046
3047	/**
3048	* scsi_host_block - Try to transition all logical units to the SDEV_BLOCK state
3049	* @shost: device to block
3050	*
3051	* Pause SCSI command processing for all logical units associated with the SCSI
3052	* host and wait until pending scsi_queue_rq() calls have finished.
3053	*
3054	* Returns zero if successful or a negative error code upon failure.
3055	*/
3056	int
3057	scsi_host_block(struct Scsi_Host *shost)
3058	{
3059	struct scsi_device *sdev;
3060	int ret;
3061
3062	/*
3063	* Call scsi_internal_device_block_nowait so we can avoid
3064	* calling synchronize_rcu() for each LUN.
3065	*/
3066	shost_for_each_device(sdev, shost) {
3067	mutex_lock(&sdev->state_mutex);
3068	ret = scsi_internal_device_block_nowait(sdev);
3069	mutex_unlock(lock: &sdev->state_mutex);
3070	if (ret) {
3071	scsi_device_put(sdev);
3072	return ret;
3073	}
3074	}
3075
3076	/* Wait for ongoing scsi_queue_rq() calls to finish. */
3077	blk_mq_wait_quiesce_done(set: &shost->tag_set);
3078
3079	return 0;
3080	}
3081	EXPORT_SYMBOL_GPL(scsi_host_block);
3082
3083	int
3084	scsi_host_unblock(struct Scsi_Host *shost, int new_state)
3085	{
3086	struct scsi_device *sdev;
3087	int ret = 0;
3088
3089	shost_for_each_device(sdev, shost) {
3090	ret = scsi_internal_device_unblock(sdev, new_state);
3091	if (ret) {
3092	scsi_device_put(sdev);
3093	break;
3094	}
3095	}
3096	return ret;
3097	}
3098	EXPORT_SYMBOL_GPL(scsi_host_unblock);
3099
3100	/**
3101	* scsi_kmap_atomic_sg - find and atomically map an sg-elemnt
3102	* @sgl: scatter-gather list
3103	* @sg_count: number of segments in sg
3104	* @offset: offset in bytes into sg, on return offset into the mapped area
3105	* @len: bytes to map, on return number of bytes mapped
3106	*
3107	* Returns virtual address of the start of the mapped page
3108	*/
3109	void *scsi_kmap_atomic_sg(struct scatterlist *sgl, int sg_count,
3110	size_t *offset, size_t *len)
3111	{
3112	int i;
3113	size_t sg_len = 0, len_complete = 0;
3114	struct scatterlist *sg;
3115	struct page *page;
3116
3117	WARN_ON(!irqs_disabled());
3118
3119	for_each_sg(sgl, sg, sg_count, i) {
3120	len_complete = sg_len; /* Complete sg-entries */
3121	sg_len += sg->length;
3122	if (sg_len > *offset)
3123	break;
3124	}
3125
3126	if (unlikely(i == sg_count)) {
3127	printk(KERN_ERR "%s: Bytes in sg: %zu, requested offset %zu, "
3128	"elements %d\n",
3129	__func__, sg_len, *offset, sg_count);
3130	WARN_ON(1);
3131	return NULL;
3132	}
3133
3134	/* Offset starting from the beginning of first page in this sg-entry */
3135	*offset = *offset - len_complete + sg->offset;
3136
3137	/* Assumption: contiguous pages can be accessed as "page + i" */
3138	page = nth_page(sg_page(sg), (*offset >> PAGE_SHIFT));
3139	*offset &= ~PAGE_MASK;
3140
3141	/* Bytes in this sg-entry from *offset to the end of the page */
3142	sg_len = PAGE_SIZE - *offset;
3143	if (*len > sg_len)
3144	*len = sg_len;
3145
3146	return kmap_atomic(page);
3147	}
3148	EXPORT_SYMBOL(scsi_kmap_atomic_sg);
3149
3150	/**
3151	* scsi_kunmap_atomic_sg - atomically unmap a virtual address, previously mapped with scsi_kmap_atomic_sg
3152	* @virt: virtual address to be unmapped
3153	*/
3154	void scsi_kunmap_atomic_sg(void *virt)
3155	{
3156	kunmap_atomic(virt);
3157	}
3158	EXPORT_SYMBOL(scsi_kunmap_atomic_sg);
3159
3160	void sdev_disable_disk_events(struct scsi_device *sdev)
3161	{
3162	atomic_inc(v: &sdev->disk_events_disable_depth);
3163	}
3164	EXPORT_SYMBOL(sdev_disable_disk_events);
3165
3166	void sdev_enable_disk_events(struct scsi_device *sdev)
3167	{
3168	if (WARN_ON_ONCE(atomic_read(&sdev->disk_events_disable_depth) <= 0))
3169	return;
3170	atomic_dec(v: &sdev->disk_events_disable_depth);
3171	}
3172	EXPORT_SYMBOL(sdev_enable_disk_events);
3173
3174	static unsigned char designator_prio(const unsigned char *d)
3175	{
3176	if (d[1] & 0x30)
3177	/* not associated with LUN */
3178	return 0;
3179
3180	if (d[3] == 0)
3181	/* invalid length */
3182	return 0;
3183
3184	/*
3185	* Order of preference for lun descriptor:
3186	* - SCSI name string
3187	* - NAA IEEE Registered Extended
3188	* - EUI-64 based 16-byte
3189	* - EUI-64 based 12-byte
3190	* - NAA IEEE Registered
3191	* - NAA IEEE Extended
3192	* - EUI-64 based 8-byte
3193	* - SCSI name string (truncated)
3194	* - T10 Vendor ID
3195	* as longer descriptors reduce the likelyhood
3196	* of identification clashes.
3197	*/
3198
3199	switch (d[1] & 0xf) {
3200	case 8:
3201	/* SCSI name string, variable-length UTF-8 */
3202	return 9;
3203	case 3:
3204	switch (d[4] >> 4) {
3205	case 6:
3206	/* NAA registered extended */
3207	return 8;
3208	case 5:
3209	/* NAA registered */
3210	return 5;
3211	case 4:
3212	/* NAA extended */
3213	return 4;
3214	case 3:
3215	/* NAA locally assigned */
3216	return 1;
3217	default:
3218	break;
3219	}
3220	break;
3221	case 2:
3222	switch (d[3]) {
3223	case 16:
3224	/* EUI64-based, 16 byte */
3225	return 7;
3226	case 12:
3227	/* EUI64-based, 12 byte */
3228	return 6;
3229	case 8:
3230	/* EUI64-based, 8 byte */
3231	return 3;
3232	default:
3233	break;
3234	}
3235	break;
3236	case 1:
3237	/* T10 vendor ID */
3238	return 1;
3239	default:
3240	break;
3241	}
3242
3243	return 0;
3244	}
3245
3246	/**
3247	* scsi_vpd_lun_id - return a unique device identification
3248	* @sdev: SCSI device
3249	* @id: buffer for the identification
3250	* @id_len: length of the buffer
3251	*
3252	* Copies a unique device identification into @id based
3253	* on the information in the VPD page 0x83 of the device.
3254	* The string will be formatted as a SCSI name string.
3255	*
3256	* Returns the length of the identification or error on failure.
3257	* If the identifier is longer than the supplied buffer the actual
3258	* identifier length is returned and the buffer is not zero-padded.
3259	*/
3260	int scsi_vpd_lun_id(struct scsi_device *sdev, char *id, size_t id_len)
3261	{
3262	u8 cur_id_prio = 0;
3263	u8 cur_id_size = 0;
3264	const unsigned char *d, *cur_id_str;
3265	const struct scsi_vpd *vpd_pg83;
3266	int id_size = -EINVAL;
3267
3268	rcu_read_lock();
3269	vpd_pg83 = rcu_dereference(sdev->vpd_pg83);
3270	if (!vpd_pg83) {
3271	rcu_read_unlock();
3272	return -ENXIO;
3273	}
3274
3275	/* The id string must be at least 20 bytes + terminating NULL byte */
3276	if (id_len < 21) {
3277	rcu_read_unlock();
3278	return -EINVAL;
3279	}
3280
3281	memset(id, 0, id_len);
3282	for (d = vpd_pg83->data + 4;
3283	d < vpd_pg83->data + vpd_pg83->len;
3284	d += d[3] + 4) {
3285	u8 prio = designator_prio(d);
3286
3287	if (prio == 0 || cur_id_prio > prio)
3288	continue;
3289
3290	switch (d[1] & 0xf) {
3291	case 0x1:
3292	/* T10 Vendor ID */
3293	if (cur_id_size > d[3])
3294	break;
3295	cur_id_prio = prio;
3296	cur_id_size = d[3];
3297	if (cur_id_size + 4 > id_len)
3298	cur_id_size = id_len - 4;
3299	cur_id_str = d + 4;
3300	id_size = snprintf(buf: id, size: id_len, fmt: "t10.%*pE",
3301	cur_id_size, cur_id_str);
3302	break;
3303	case 0x2:
3304	/* EUI-64 */
3305	cur_id_prio = prio;
3306	cur_id_size = d[3];
3307	cur_id_str = d + 4;
3308	switch (cur_id_size) {
3309	case 8:
3310	id_size = snprintf(buf: id, size: id_len,
3311	fmt: "eui.%8phN",
3312	cur_id_str);
3313	break;
3314	case 12:
3315	id_size = snprintf(buf: id, size: id_len,
3316	fmt: "eui.%12phN",
3317	cur_id_str);
3318	break;
3319	case 16:
3320	id_size = snprintf(buf: id, size: id_len,
3321	fmt: "eui.%16phN",
3322	cur_id_str);
3323	break;
3324	default:
3325	break;
3326	}
3327	break;
3328	case 0x3:
3329	/* NAA */
3330	cur_id_prio = prio;
3331	cur_id_size = d[3];
3332	cur_id_str = d + 4;
3333	switch (cur_id_size) {
3334	case 8:
3335	id_size = snprintf(buf: id, size: id_len,
3336	fmt: "naa.%8phN",
3337	cur_id_str);
3338	break;
3339	case 16:
3340	id_size = snprintf(buf: id, size: id_len,
3341	fmt: "naa.%16phN",
3342	cur_id_str);
3343	break;
3344	default:
3345	break;
3346	}
3347	break;
3348	case 0x8:
3349	/* SCSI name string */
3350	if (cur_id_size > d[3])
3351	break;
3352	/* Prefer others for truncated descriptor */
3353	if (d[3] > id_len) {
3354	prio = 2;
3355	if (cur_id_prio > prio)
3356	break;
3357	}
3358	cur_id_prio = prio;
3359	cur_id_size = id_size = d[3];
3360	cur_id_str = d + 4;
3361	if (cur_id_size >= id_len)
3362	cur_id_size = id_len - 1;
3363	memcpy(id, cur_id_str, cur_id_size);
3364	break;
3365	default:
3366	break;
3367	}
3368	}
3369	rcu_read_unlock();
3370
3371	return id_size;
3372	}
3373	EXPORT_SYMBOL(scsi_vpd_lun_id);
3374
3375	/*
3376	* scsi_vpd_tpg_id - return a target port group identifier
3377	* @sdev: SCSI device
3378	*
3379	* Returns the Target Port Group identifier from the information
3380	* froom VPD page 0x83 of the device.
3381	*
3382	* Returns the identifier or error on failure.
3383	*/
3384	int scsi_vpd_tpg_id(struct scsi_device *sdev, int *rel_id)
3385	{
3386	const unsigned char *d;
3387	const struct scsi_vpd *vpd_pg83;
3388	int group_id = -EAGAIN, rel_port = -1;
3389
3390	rcu_read_lock();
3391	vpd_pg83 = rcu_dereference(sdev->vpd_pg83);
3392	if (!vpd_pg83) {
3393	rcu_read_unlock();
3394	return -ENXIO;
3395	}
3396
3397	d = vpd_pg83->data + 4;
3398	while (d < vpd_pg83->data + vpd_pg83->len) {
3399	switch (d[1] & 0xf) {
3400	case 0x4:
3401	/* Relative target port */
3402	rel_port = get_unaligned_be16(p: &d[6]);
3403	break;
3404	case 0x5:
3405	/* Target port group */
3406	group_id = get_unaligned_be16(p: &d[6]);
3407	break;
3408	default:
3409	break;
3410	}
3411	d += d[3] + 4;
3412	}
3413	rcu_read_unlock();
3414
3415	if (group_id >= 0 && rel_id && rel_port != -1)
3416	*rel_id = rel_port;
3417
3418	return group_id;
3419	}
3420	EXPORT_SYMBOL(scsi_vpd_tpg_id);
3421
3422	/**
3423	* scsi_build_sense - build sense data for a command
3424	* @scmd: scsi command for which the sense should be formatted
3425	* @desc: Sense format (non-zero == descriptor format,
3426	* 0 == fixed format)
3427	* @key: Sense key
3428	* @asc: Additional sense code
3429	* @ascq: Additional sense code qualifier
3430	*
3431	**/
3432	void scsi_build_sense(struct scsi_cmnd *scmd, int desc, u8 key, u8 asc, u8 ascq)
3433	{
3434	scsi_build_sense_buffer(desc, buf: scmd->sense_buffer, key, asc, ascq);
3435	scmd->result = SAM_STAT_CHECK_CONDITION;
3436	}
3437	EXPORT_SYMBOL_GPL(scsi_build_sense);
3438
3439	#ifdef CONFIG_SCSI_LIB_KUNIT_TEST
3440	#include "scsi_lib_test.c"
3441	#endif
3442