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