Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0
2 : /*
3 : * blk-mq scheduling framework
4 : *
5 : * Copyright (C) 2016 Jens Axboe
6 : */
7 : #include <linux/kernel.h>
8 : #include <linux/module.h>
9 : #include <linux/blk-mq.h>
10 : #include <linux/list_sort.h>
11 :
12 : #include <trace/events/block.h>
13 :
14 : #include "blk.h"
15 : #include "blk-mq.h"
16 : #include "blk-mq-debugfs.h"
17 : #include "blk-mq-sched.h"
18 : #include "blk-mq-tag.h"
19 : #include "blk-wbt.h"
20 :
21 : /*
22 : * Mark a hardware queue as needing a restart.
23 : */
24 0 : void blk_mq_sched_mark_restart_hctx(struct blk_mq_hw_ctx *hctx)
25 : {
26 0 : if (test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state))
27 : return;
28 :
29 0 : set_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);
30 : }
31 : EXPORT_SYMBOL_GPL(blk_mq_sched_mark_restart_hctx);
32 :
33 0 : void __blk_mq_sched_restart(struct blk_mq_hw_ctx *hctx)
34 : {
35 0 : clear_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);
36 :
37 : /*
38 : * Order clearing SCHED_RESTART and list_empty_careful(&hctx->dispatch)
39 : * in blk_mq_run_hw_queue(). Its pair is the barrier in
40 : * blk_mq_dispatch_rq_list(). So dispatch code won't see SCHED_RESTART,
41 : * meantime new request added to hctx->dispatch is missed to check in
42 : * blk_mq_run_hw_queue().
43 : */
44 0 : smp_mb();
45 :
46 0 : blk_mq_run_hw_queue(hctx, true);
47 0 : }
48 :
49 0 : static int sched_rq_cmp(void *priv, const struct list_head *a,
50 : const struct list_head *b)
51 : {
52 0 : struct request *rqa = container_of(a, struct request, queuelist);
53 0 : struct request *rqb = container_of(b, struct request, queuelist);
54 :
55 0 : return rqa->mq_hctx > rqb->mq_hctx;
56 : }
57 :
58 0 : static bool blk_mq_dispatch_hctx_list(struct list_head *rq_list)
59 : {
60 0 : struct blk_mq_hw_ctx *hctx =
61 0 : list_first_entry(rq_list, struct request, queuelist)->mq_hctx;
62 : struct request *rq;
63 0 : LIST_HEAD(hctx_list);
64 0 : unsigned int count = 0;
65 :
66 0 : list_for_each_entry(rq, rq_list, queuelist) {
67 0 : if (rq->mq_hctx != hctx) {
68 0 : list_cut_before(&hctx_list, rq_list, &rq->queuelist);
69 : goto dispatch;
70 : }
71 0 : count++;
72 : }
73 : list_splice_tail_init(rq_list, &hctx_list);
74 :
75 : dispatch:
76 0 : return blk_mq_dispatch_rq_list(hctx, &hctx_list, count);
77 : }
78 :
79 : #define BLK_MQ_BUDGET_DELAY 3 /* ms units */
80 :
81 : /*
82 : * Only SCSI implements .get_budget and .put_budget, and SCSI restarts
83 : * its queue by itself in its completion handler, so we don't need to
84 : * restart queue if .get_budget() fails to get the budget.
85 : *
86 : * Returns -EAGAIN if hctx->dispatch was found non-empty and run_work has to
87 : * be run again. This is necessary to avoid starving flushes.
88 : */
89 0 : static int __blk_mq_do_dispatch_sched(struct blk_mq_hw_ctx *hctx)
90 : {
91 0 : struct request_queue *q = hctx->queue;
92 0 : struct elevator_queue *e = q->elevator;
93 0 : bool multi_hctxs = false, run_queue = false;
94 0 : bool dispatched = false, busy = false;
95 : unsigned int max_dispatch;
96 0 : LIST_HEAD(rq_list);
97 0 : int count = 0;
98 :
99 0 : if (hctx->dispatch_busy)
100 : max_dispatch = 1;
101 : else
102 0 : max_dispatch = hctx->queue->nr_requests;
103 :
104 : do {
105 : struct request *rq;
106 : int budget_token;
107 :
108 0 : if (e->type->ops.has_work && !e->type->ops.has_work(hctx))
109 : break;
110 :
111 0 : if (!list_empty_careful(&hctx->dispatch)) {
112 : busy = true;
113 : break;
114 : }
115 :
116 0 : budget_token = blk_mq_get_dispatch_budget(q);
117 0 : if (budget_token < 0)
118 : break;
119 :
120 0 : rq = e->type->ops.dispatch_request(hctx);
121 0 : if (!rq) {
122 : blk_mq_put_dispatch_budget(q, budget_token);
123 : /*
124 : * We're releasing without dispatching. Holding the
125 : * budget could have blocked any "hctx"s with the
126 : * same queue and if we didn't dispatch then there's
127 : * no guarantee anyone will kick the queue. Kick it
128 : * ourselves.
129 : */
130 : run_queue = true;
131 : break;
132 : }
133 :
134 0 : blk_mq_set_rq_budget_token(rq, budget_token);
135 :
136 : /*
137 : * Now this rq owns the budget which has to be released
138 : * if this rq won't be queued to driver via .queue_rq()
139 : * in blk_mq_dispatch_rq_list().
140 : */
141 0 : list_add_tail(&rq->queuelist, &rq_list);
142 0 : count++;
143 0 : if (rq->mq_hctx != hctx)
144 0 : multi_hctxs = true;
145 :
146 : /*
147 : * If we cannot get tag for the request, stop dequeueing
148 : * requests from the IO scheduler. We are unlikely to be able
149 : * to submit them anyway and it creates false impression for
150 : * scheduling heuristics that the device can take more IO.
151 : */
152 0 : if (!blk_mq_get_driver_tag(rq))
153 : break;
154 0 : } while (count < max_dispatch);
155 :
156 0 : if (!count) {
157 0 : if (run_queue)
158 0 : blk_mq_delay_run_hw_queues(q, BLK_MQ_BUDGET_DELAY);
159 0 : } else if (multi_hctxs) {
160 : /*
161 : * Requests from different hctx may be dequeued from some
162 : * schedulers, such as bfq and deadline.
163 : *
164 : * Sort the requests in the list according to their hctx,
165 : * dispatch batching requests from same hctx at a time.
166 : */
167 0 : list_sort(NULL, &rq_list, sched_rq_cmp);
168 : do {
169 0 : dispatched |= blk_mq_dispatch_hctx_list(&rq_list);
170 0 : } while (!list_empty(&rq_list));
171 : } else {
172 0 : dispatched = blk_mq_dispatch_rq_list(hctx, &rq_list, count);
173 : }
174 :
175 0 : if (busy)
176 : return -EAGAIN;
177 0 : return !!dispatched;
178 : }
179 :
180 0 : static int blk_mq_do_dispatch_sched(struct blk_mq_hw_ctx *hctx)
181 : {
182 0 : unsigned long end = jiffies + HZ;
183 : int ret;
184 :
185 : do {
186 0 : ret = __blk_mq_do_dispatch_sched(hctx);
187 0 : if (ret != 1)
188 : break;
189 0 : if (need_resched() || time_is_before_jiffies(end)) {
190 0 : blk_mq_delay_run_hw_queue(hctx, 0);
191 0 : break;
192 : }
193 : } while (1);
194 :
195 0 : return ret;
196 : }
197 :
198 : static struct blk_mq_ctx *blk_mq_next_ctx(struct blk_mq_hw_ctx *hctx,
199 : struct blk_mq_ctx *ctx)
200 : {
201 0 : unsigned short idx = ctx->index_hw[hctx->type];
202 :
203 0 : if (++idx == hctx->nr_ctx)
204 0 : idx = 0;
205 :
206 0 : return hctx->ctxs[idx];
207 : }
208 :
209 : /*
210 : * Only SCSI implements .get_budget and .put_budget, and SCSI restarts
211 : * its queue by itself in its completion handler, so we don't need to
212 : * restart queue if .get_budget() fails to get the budget.
213 : *
214 : * Returns -EAGAIN if hctx->dispatch was found non-empty and run_work has to
215 : * be run again. This is necessary to avoid starving flushes.
216 : */
217 0 : static int blk_mq_do_dispatch_ctx(struct blk_mq_hw_ctx *hctx)
218 : {
219 0 : struct request_queue *q = hctx->queue;
220 0 : LIST_HEAD(rq_list);
221 0 : struct blk_mq_ctx *ctx = READ_ONCE(hctx->dispatch_from);
222 0 : int ret = 0;
223 : struct request *rq;
224 :
225 : do {
226 : int budget_token;
227 :
228 0 : if (!list_empty_careful(&hctx->dispatch)) {
229 : ret = -EAGAIN;
230 : break;
231 : }
232 :
233 0 : if (!sbitmap_any_bit_set(&hctx->ctx_map))
234 : break;
235 :
236 0 : budget_token = blk_mq_get_dispatch_budget(q);
237 0 : if (budget_token < 0)
238 : break;
239 :
240 0 : rq = blk_mq_dequeue_from_ctx(hctx, ctx);
241 0 : if (!rq) {
242 0 : blk_mq_put_dispatch_budget(q, budget_token);
243 : /*
244 : * We're releasing without dispatching. Holding the
245 : * budget could have blocked any "hctx"s with the
246 : * same queue and if we didn't dispatch then there's
247 : * no guarantee anyone will kick the queue. Kick it
248 : * ourselves.
249 : */
250 0 : blk_mq_delay_run_hw_queues(q, BLK_MQ_BUDGET_DELAY);
251 0 : break;
252 : }
253 :
254 0 : blk_mq_set_rq_budget_token(rq, budget_token);
255 :
256 : /*
257 : * Now this rq owns the budget which has to be released
258 : * if this rq won't be queued to driver via .queue_rq()
259 : * in blk_mq_dispatch_rq_list().
260 : */
261 0 : list_add(&rq->queuelist, &rq_list);
262 :
263 : /* round robin for fair dispatch */
264 0 : ctx = blk_mq_next_ctx(hctx, rq->mq_ctx);
265 :
266 0 : } while (blk_mq_dispatch_rq_list(rq->mq_hctx, &rq_list, 1));
267 :
268 0 : WRITE_ONCE(hctx->dispatch_from, ctx);
269 0 : return ret;
270 : }
271 :
272 0 : static int __blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
273 : {
274 0 : struct request_queue *q = hctx->queue;
275 0 : const bool has_sched = q->elevator;
276 0 : int ret = 0;
277 0 : LIST_HEAD(rq_list);
278 :
279 : /*
280 : * If we have previous entries on our dispatch list, grab them first for
281 : * more fair dispatch.
282 : */
283 0 : if (!list_empty_careful(&hctx->dispatch)) {
284 0 : spin_lock(&hctx->lock);
285 0 : if (!list_empty(&hctx->dispatch))
286 0 : list_splice_init(&hctx->dispatch, &rq_list);
287 0 : spin_unlock(&hctx->lock);
288 : }
289 :
290 : /*
291 : * Only ask the scheduler for requests, if we didn't have residual
292 : * requests from the dispatch list. This is to avoid the case where
293 : * we only ever dispatch a fraction of the requests available because
294 : * of low device queue depth. Once we pull requests out of the IO
295 : * scheduler, we can no longer merge or sort them. So it's best to
296 : * leave them there for as long as we can. Mark the hw queue as
297 : * needing a restart in that case.
298 : *
299 : * We want to dispatch from the scheduler if there was nothing
300 : * on the dispatch list or we were able to dispatch from the
301 : * dispatch list.
302 : */
303 0 : if (!list_empty(&rq_list)) {
304 0 : blk_mq_sched_mark_restart_hctx(hctx);
305 0 : if (blk_mq_dispatch_rq_list(hctx, &rq_list, 0)) {
306 0 : if (has_sched)
307 0 : ret = blk_mq_do_dispatch_sched(hctx);
308 : else
309 0 : ret = blk_mq_do_dispatch_ctx(hctx);
310 : }
311 0 : } else if (has_sched) {
312 0 : ret = blk_mq_do_dispatch_sched(hctx);
313 0 : } else if (hctx->dispatch_busy) {
314 : /* dequeue request one by one from sw queue if queue is busy */
315 0 : ret = blk_mq_do_dispatch_ctx(hctx);
316 : } else {
317 0 : blk_mq_flush_busy_ctxs(hctx, &rq_list);
318 0 : blk_mq_dispatch_rq_list(hctx, &rq_list, 0);
319 : }
320 :
321 0 : return ret;
322 : }
323 :
324 0 : void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
325 : {
326 0 : struct request_queue *q = hctx->queue;
327 :
328 : /* RCU or SRCU read lock is needed before checking quiesced flag */
329 0 : if (unlikely(blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q)))
330 : return;
331 :
332 0 : hctx->run++;
333 :
334 : /*
335 : * A return of -EAGAIN is an indication that hctx->dispatch is not
336 : * empty and we must run again in order to avoid starving flushes.
337 : */
338 0 : if (__blk_mq_sched_dispatch_requests(hctx) == -EAGAIN) {
339 0 : if (__blk_mq_sched_dispatch_requests(hctx) == -EAGAIN)
340 0 : blk_mq_run_hw_queue(hctx, true);
341 : }
342 : }
343 :
344 0 : bool blk_mq_sched_bio_merge(struct request_queue *q, struct bio *bio,
345 : unsigned int nr_segs)
346 : {
347 0 : struct elevator_queue *e = q->elevator;
348 : struct blk_mq_ctx *ctx;
349 : struct blk_mq_hw_ctx *hctx;
350 0 : bool ret = false;
351 : enum hctx_type type;
352 :
353 0 : if (e && e->type->ops.bio_merge) {
354 0 : ret = e->type->ops.bio_merge(q, bio, nr_segs);
355 0 : goto out_put;
356 : }
357 :
358 0 : ctx = blk_mq_get_ctx(q);
359 0 : hctx = blk_mq_map_queue(q, bio->bi_opf, ctx);
360 0 : type = hctx->type;
361 0 : if (!(hctx->flags & BLK_MQ_F_SHOULD_MERGE) ||
362 0 : list_empty_careful(&ctx->rq_lists[type]))
363 : goto out_put;
364 :
365 : /* default per sw-queue merge */
366 0 : spin_lock(&ctx->lock);
367 : /*
368 : * Reverse check our software queue for entries that we could
369 : * potentially merge with. Currently includes a hand-wavy stop
370 : * count of 8, to not spend too much time checking for merges.
371 : */
372 0 : if (blk_bio_list_merge(q, &ctx->rq_lists[type], bio, nr_segs))
373 0 : ret = true;
374 :
375 0 : spin_unlock(&ctx->lock);
376 : out_put:
377 0 : return ret;
378 : }
379 :
380 0 : bool blk_mq_sched_try_insert_merge(struct request_queue *q, struct request *rq,
381 : struct list_head *free)
382 : {
383 0 : return rq_mergeable(rq) && elv_attempt_insert_merge(q, rq, free);
384 : }
385 : EXPORT_SYMBOL_GPL(blk_mq_sched_try_insert_merge);
386 :
387 : static bool blk_mq_sched_bypass_insert(struct blk_mq_hw_ctx *hctx,
388 : struct request *rq)
389 : {
390 : /*
391 : * dispatch flush and passthrough rq directly
392 : *
393 : * passthrough request has to be added to hctx->dispatch directly.
394 : * For some reason, device may be in one situation which can't
395 : * handle FS request, so STS_RESOURCE is always returned and the
396 : * FS request will be added to hctx->dispatch. However passthrough
397 : * request may be required at that time for fixing the problem. If
398 : * passthrough request is added to scheduler queue, there isn't any
399 : * chance to dispatch it given we prioritize requests in hctx->dispatch.
400 : */
401 0 : if ((rq->rq_flags & RQF_FLUSH_SEQ) || blk_rq_is_passthrough(rq))
402 : return true;
403 :
404 : return false;
405 : }
406 :
407 0 : void blk_mq_sched_insert_request(struct request *rq, bool at_head,
408 : bool run_queue, bool async)
409 : {
410 0 : struct request_queue *q = rq->q;
411 0 : struct elevator_queue *e = q->elevator;
412 0 : struct blk_mq_ctx *ctx = rq->mq_ctx;
413 0 : struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
414 :
415 0 : WARN_ON(e && (rq->tag != BLK_MQ_NO_TAG));
416 :
417 0 : if (blk_mq_sched_bypass_insert(hctx, rq)) {
418 : /*
419 : * Firstly normal IO request is inserted to scheduler queue or
420 : * sw queue, meantime we add flush request to dispatch queue(
421 : * hctx->dispatch) directly and there is at most one in-flight
422 : * flush request for each hw queue, so it doesn't matter to add
423 : * flush request to tail or front of the dispatch queue.
424 : *
425 : * Secondly in case of NCQ, flush request belongs to non-NCQ
426 : * command, and queueing it will fail when there is any
427 : * in-flight normal IO request(NCQ command). When adding flush
428 : * rq to the front of hctx->dispatch, it is easier to introduce
429 : * extra time to flush rq's latency because of S_SCHED_RESTART
430 : * compared with adding to the tail of dispatch queue, then
431 : * chance of flush merge is increased, and less flush requests
432 : * will be issued to controller. It is observed that ~10% time
433 : * is saved in blktests block/004 on disk attached to AHCI/NCQ
434 : * drive when adding flush rq to the front of hctx->dispatch.
435 : *
436 : * Simply queue flush rq to the front of hctx->dispatch so that
437 : * intensive flush workloads can benefit in case of NCQ HW.
438 : */
439 0 : at_head = (rq->rq_flags & RQF_FLUSH_SEQ) ? true : at_head;
440 0 : blk_mq_request_bypass_insert(rq, at_head, false);
441 0 : goto run;
442 : }
443 :
444 0 : if (e) {
445 : LIST_HEAD(list);
446 :
447 0 : list_add(&rq->queuelist, &list);
448 0 : e->type->ops.insert_requests(hctx, &list, at_head);
449 : } else {
450 0 : spin_lock(&ctx->lock);
451 0 : __blk_mq_insert_request(hctx, rq, at_head);
452 0 : spin_unlock(&ctx->lock);
453 : }
454 :
455 : run:
456 0 : if (run_queue)
457 0 : blk_mq_run_hw_queue(hctx, async);
458 0 : }
459 :
460 0 : void blk_mq_sched_insert_requests(struct blk_mq_hw_ctx *hctx,
461 : struct blk_mq_ctx *ctx,
462 : struct list_head *list, bool run_queue_async)
463 : {
464 : struct elevator_queue *e;
465 0 : struct request_queue *q = hctx->queue;
466 :
467 : /*
468 : * blk_mq_sched_insert_requests() is called from flush plug
469 : * context only, and hold one usage counter to prevent queue
470 : * from being released.
471 : */
472 0 : percpu_ref_get(&q->q_usage_counter);
473 :
474 0 : e = hctx->queue->elevator;
475 0 : if (e) {
476 0 : e->type->ops.insert_requests(hctx, list, false);
477 : } else {
478 : /*
479 : * try to issue requests directly if the hw queue isn't
480 : * busy in case of 'none' scheduler, and this way may save
481 : * us one extra enqueue & dequeue to sw queue.
482 : */
483 0 : if (!hctx->dispatch_busy && !run_queue_async) {
484 0 : blk_mq_run_dispatch_ops(hctx->queue,
485 : blk_mq_try_issue_list_directly(hctx, list));
486 0 : if (list_empty(list))
487 : goto out;
488 : }
489 0 : blk_mq_insert_requests(hctx, ctx, list);
490 : }
491 :
492 0 : blk_mq_run_hw_queue(hctx, run_queue_async);
493 : out:
494 0 : percpu_ref_put(&q->q_usage_counter);
495 0 : }
496 :
497 0 : static int blk_mq_sched_alloc_map_and_rqs(struct request_queue *q,
498 : struct blk_mq_hw_ctx *hctx,
499 : unsigned int hctx_idx)
500 : {
501 0 : if (blk_mq_is_shared_tags(q->tag_set->flags)) {
502 0 : hctx->sched_tags = q->sched_shared_tags;
503 : return 0;
504 : }
505 :
506 0 : hctx->sched_tags = blk_mq_alloc_map_and_rqs(q->tag_set, hctx_idx,
507 0 : q->nr_requests);
508 :
509 0 : if (!hctx->sched_tags)
510 : return -ENOMEM;
511 : return 0;
512 : }
513 :
514 : static void blk_mq_exit_sched_shared_tags(struct request_queue *queue)
515 : {
516 0 : blk_mq_free_rq_map(queue->sched_shared_tags);
517 0 : queue->sched_shared_tags = NULL;
518 : }
519 :
520 : /* called in queue's release handler, tagset has gone away */
521 0 : static void blk_mq_sched_tags_teardown(struct request_queue *q, unsigned int flags)
522 : {
523 : struct blk_mq_hw_ctx *hctx;
524 : unsigned long i;
525 :
526 0 : queue_for_each_hw_ctx(q, hctx, i) {
527 0 : if (hctx->sched_tags) {
528 0 : if (!blk_mq_is_shared_tags(flags))
529 0 : blk_mq_free_rq_map(hctx->sched_tags);
530 0 : hctx->sched_tags = NULL;
531 : }
532 : }
533 :
534 0 : if (blk_mq_is_shared_tags(flags))
535 0 : blk_mq_exit_sched_shared_tags(q);
536 0 : }
537 :
538 0 : static int blk_mq_init_sched_shared_tags(struct request_queue *queue)
539 : {
540 0 : struct blk_mq_tag_set *set = queue->tag_set;
541 :
542 : /*
543 : * Set initial depth at max so that we don't need to reallocate for
544 : * updating nr_requests.
545 : */
546 0 : queue->sched_shared_tags = blk_mq_alloc_map_and_rqs(set,
547 : BLK_MQ_NO_HCTX_IDX,
548 : MAX_SCHED_RQ);
549 0 : if (!queue->sched_shared_tags)
550 : return -ENOMEM;
551 :
552 0 : blk_mq_tag_update_sched_shared_tags(queue);
553 :
554 0 : return 0;
555 : }
556 :
557 : /* caller must have a reference to @e, will grab another one if successful */
558 0 : int blk_mq_init_sched(struct request_queue *q, struct elevator_type *e)
559 : {
560 0 : unsigned int flags = q->tag_set->flags;
561 : struct blk_mq_hw_ctx *hctx;
562 : struct elevator_queue *eq;
563 : unsigned long i;
564 : int ret;
565 :
566 : /*
567 : * Default to double of smaller one between hw queue_depth and 128,
568 : * since we don't split into sync/async like the old code did.
569 : * Additionally, this is a per-hw queue depth.
570 : */
571 0 : q->nr_requests = 2 * min_t(unsigned int, q->tag_set->queue_depth,
572 : BLKDEV_DEFAULT_RQ);
573 :
574 0 : if (blk_mq_is_shared_tags(flags)) {
575 0 : ret = blk_mq_init_sched_shared_tags(q);
576 0 : if (ret)
577 : return ret;
578 : }
579 :
580 0 : queue_for_each_hw_ctx(q, hctx, i) {
581 0 : ret = blk_mq_sched_alloc_map_and_rqs(q, hctx, i);
582 0 : if (ret)
583 : goto err_free_map_and_rqs;
584 : }
585 :
586 0 : ret = e->ops.init_sched(q, e);
587 0 : if (ret)
588 : goto err_free_map_and_rqs;
589 :
590 0 : mutex_lock(&q->debugfs_mutex);
591 0 : blk_mq_debugfs_register_sched(q);
592 0 : mutex_unlock(&q->debugfs_mutex);
593 :
594 0 : queue_for_each_hw_ctx(q, hctx, i) {
595 0 : if (e->ops.init_hctx) {
596 0 : ret = e->ops.init_hctx(hctx, i);
597 0 : if (ret) {
598 0 : eq = q->elevator;
599 0 : blk_mq_sched_free_rqs(q);
600 0 : blk_mq_exit_sched(q, eq);
601 0 : kobject_put(&eq->kobj);
602 0 : return ret;
603 : }
604 : }
605 0 : mutex_lock(&q->debugfs_mutex);
606 0 : blk_mq_debugfs_register_sched_hctx(q, hctx);
607 0 : mutex_unlock(&q->debugfs_mutex);
608 : }
609 :
610 : return 0;
611 :
612 : err_free_map_and_rqs:
613 0 : blk_mq_sched_free_rqs(q);
614 0 : blk_mq_sched_tags_teardown(q, flags);
615 :
616 0 : q->elevator = NULL;
617 0 : return ret;
618 : }
619 :
620 : /*
621 : * called in either blk_queue_cleanup or elevator_switch, tagset
622 : * is required for freeing requests
623 : */
624 0 : void blk_mq_sched_free_rqs(struct request_queue *q)
625 : {
626 : struct blk_mq_hw_ctx *hctx;
627 : unsigned long i;
628 :
629 0 : if (blk_mq_is_shared_tags(q->tag_set->flags)) {
630 0 : blk_mq_free_rqs(q->tag_set, q->sched_shared_tags,
631 : BLK_MQ_NO_HCTX_IDX);
632 : } else {
633 0 : queue_for_each_hw_ctx(q, hctx, i) {
634 0 : if (hctx->sched_tags)
635 0 : blk_mq_free_rqs(q->tag_set,
636 : hctx->sched_tags, i);
637 : }
638 : }
639 0 : }
640 :
641 0 : void blk_mq_exit_sched(struct request_queue *q, struct elevator_queue *e)
642 : {
643 : struct blk_mq_hw_ctx *hctx;
644 : unsigned long i;
645 0 : unsigned int flags = 0;
646 :
647 0 : queue_for_each_hw_ctx(q, hctx, i) {
648 0 : mutex_lock(&q->debugfs_mutex);
649 0 : blk_mq_debugfs_unregister_sched_hctx(hctx);
650 0 : mutex_unlock(&q->debugfs_mutex);
651 :
652 0 : if (e->type->ops.exit_hctx && hctx->sched_data) {
653 0 : e->type->ops.exit_hctx(hctx, i);
654 0 : hctx->sched_data = NULL;
655 : }
656 0 : flags = hctx->flags;
657 : }
658 :
659 0 : mutex_lock(&q->debugfs_mutex);
660 0 : blk_mq_debugfs_unregister_sched(q);
661 0 : mutex_unlock(&q->debugfs_mutex);
662 :
663 0 : if (e->type->ops.exit_sched)
664 0 : e->type->ops.exit_sched(e);
665 0 : blk_mq_sched_tags_teardown(q, flags);
666 0 : q->elevator = NULL;
667 0 : }
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