1 // SPDX-License-Identifier: GPL-2.0
3 * Functions related to sysfs handling
5 #include <linux/kernel.h>
6 #include <linux/slab.h>
7 #include <linux/module.h>
9 #include <linux/blkdev.h>
10 #include <linux/backing-dev.h>
11 #include <linux/blktrace_api.h>
12 #include <linux/blk-mq.h>
13 #include <linux/blk-cgroup.h>
17 #include "blk-mq-debugfs.h"
20 struct queue_sysfs_entry {
21 struct attribute attr;
22 ssize_t (*show)(struct request_queue *, char *);
23 ssize_t (*store)(struct request_queue *, const char *, size_t);
27 queue_var_show(unsigned long var, char *page)
29 return sprintf(page, "%lu\n", var);
33 queue_var_store(unsigned long *var, const char *page, size_t count)
38 err = kstrtoul(page, 10, &v);
39 if (err || v > UINT_MAX)
47 static ssize_t queue_var_store64(s64 *var, const char *page)
52 err = kstrtos64(page, 10, &v);
60 static ssize_t queue_requests_show(struct request_queue *q, char *page)
62 return queue_var_show(q->nr_requests, (page));
66 queue_requests_store(struct request_queue *q, const char *page, size_t count)
74 ret = queue_var_store(&nr, page, count);
78 if (nr < BLKDEV_MIN_RQ)
81 err = blk_mq_update_nr_requests(q, nr);
88 static ssize_t queue_ra_show(struct request_queue *q, char *page)
90 unsigned long ra_kb = q->backing_dev_info->ra_pages <<
93 return queue_var_show(ra_kb, (page));
97 queue_ra_store(struct request_queue *q, const char *page, size_t count)
100 ssize_t ret = queue_var_store(&ra_kb, page, count);
105 q->backing_dev_info->ra_pages = ra_kb >> (PAGE_SHIFT - 10);
110 static ssize_t queue_max_sectors_show(struct request_queue *q, char *page)
112 int max_sectors_kb = queue_max_sectors(q) >> 1;
114 return queue_var_show(max_sectors_kb, (page));
117 static ssize_t queue_max_segments_show(struct request_queue *q, char *page)
119 return queue_var_show(queue_max_segments(q), (page));
122 static ssize_t queue_max_discard_segments_show(struct request_queue *q,
125 return queue_var_show(queue_max_discard_segments(q), (page));
128 static ssize_t queue_max_integrity_segments_show(struct request_queue *q, char *page)
130 return queue_var_show(q->limits.max_integrity_segments, (page));
133 static ssize_t queue_max_segment_size_show(struct request_queue *q, char *page)
135 if (blk_queue_cluster(q))
136 return queue_var_show(queue_max_segment_size(q), (page));
138 return queue_var_show(PAGE_SIZE, (page));
141 static ssize_t queue_logical_block_size_show(struct request_queue *q, char *page)
143 return queue_var_show(queue_logical_block_size(q), page);
146 static ssize_t queue_physical_block_size_show(struct request_queue *q, char *page)
148 return queue_var_show(queue_physical_block_size(q), page);
151 static ssize_t queue_chunk_sectors_show(struct request_queue *q, char *page)
153 return queue_var_show(q->limits.chunk_sectors, page);
156 static ssize_t queue_io_min_show(struct request_queue *q, char *page)
158 return queue_var_show(queue_io_min(q), page);
161 static ssize_t queue_io_opt_show(struct request_queue *q, char *page)
163 return queue_var_show(queue_io_opt(q), page);
166 static ssize_t queue_discard_granularity_show(struct request_queue *q, char *page)
168 return queue_var_show(q->limits.discard_granularity, page);
171 static ssize_t queue_discard_max_hw_show(struct request_queue *q, char *page)
174 return sprintf(page, "%llu\n",
175 (unsigned long long)q->limits.max_hw_discard_sectors << 9);
178 static ssize_t queue_discard_max_show(struct request_queue *q, char *page)
180 return sprintf(page, "%llu\n",
181 (unsigned long long)q->limits.max_discard_sectors << 9);
184 static ssize_t queue_discard_max_store(struct request_queue *q,
185 const char *page, size_t count)
187 unsigned long max_discard;
188 ssize_t ret = queue_var_store(&max_discard, page, count);
193 if (max_discard & (q->limits.discard_granularity - 1))
197 if (max_discard > UINT_MAX)
200 if (max_discard > q->limits.max_hw_discard_sectors)
201 max_discard = q->limits.max_hw_discard_sectors;
203 q->limits.max_discard_sectors = max_discard;
207 static ssize_t queue_discard_zeroes_data_show(struct request_queue *q, char *page)
209 return queue_var_show(0, page);
212 static ssize_t queue_write_same_max_show(struct request_queue *q, char *page)
214 return sprintf(page, "%llu\n",
215 (unsigned long long)q->limits.max_write_same_sectors << 9);
218 static ssize_t queue_write_zeroes_max_show(struct request_queue *q, char *page)
220 return sprintf(page, "%llu\n",
221 (unsigned long long)q->limits.max_write_zeroes_sectors << 9);
225 queue_max_sectors_store(struct request_queue *q, const char *page, size_t count)
227 unsigned long max_sectors_kb,
228 max_hw_sectors_kb = queue_max_hw_sectors(q) >> 1,
229 page_kb = 1 << (PAGE_SHIFT - 10);
230 ssize_t ret = queue_var_store(&max_sectors_kb, page, count);
235 max_hw_sectors_kb = min_not_zero(max_hw_sectors_kb, (unsigned long)
236 q->limits.max_dev_sectors >> 1);
238 if (max_sectors_kb > max_hw_sectors_kb || max_sectors_kb < page_kb)
241 spin_lock_irq(&q->queue_lock);
242 q->limits.max_sectors = max_sectors_kb << 1;
243 q->backing_dev_info->io_pages = max_sectors_kb >> (PAGE_SHIFT - 10);
244 spin_unlock_irq(&q->queue_lock);
249 static ssize_t queue_max_hw_sectors_show(struct request_queue *q, char *page)
251 int max_hw_sectors_kb = queue_max_hw_sectors(q) >> 1;
253 return queue_var_show(max_hw_sectors_kb, (page));
256 #define QUEUE_SYSFS_BIT_FNS(name, flag, neg) \
258 queue_show_##name(struct request_queue *q, char *page) \
261 bit = test_bit(QUEUE_FLAG_##flag, &q->queue_flags); \
262 return queue_var_show(neg ? !bit : bit, page); \
265 queue_store_##name(struct request_queue *q, const char *page, size_t count) \
269 ret = queue_var_store(&val, page, count); \
276 blk_queue_flag_set(QUEUE_FLAG_##flag, q); \
278 blk_queue_flag_clear(QUEUE_FLAG_##flag, q); \
282 QUEUE_SYSFS_BIT_FNS(nonrot, NONROT, 1);
283 QUEUE_SYSFS_BIT_FNS(random, ADD_RANDOM, 0);
284 QUEUE_SYSFS_BIT_FNS(iostats, IO_STAT, 0);
285 #undef QUEUE_SYSFS_BIT_FNS
287 static ssize_t queue_zoned_show(struct request_queue *q, char *page)
289 switch (blk_queue_zoned_model(q)) {
291 return sprintf(page, "host-aware\n");
293 return sprintf(page, "host-managed\n");
295 return sprintf(page, "none\n");
299 static ssize_t queue_nr_zones_show(struct request_queue *q, char *page)
301 return queue_var_show(blk_queue_nr_zones(q), page);
304 static ssize_t queue_nomerges_show(struct request_queue *q, char *page)
306 return queue_var_show((blk_queue_nomerges(q) << 1) |
307 blk_queue_noxmerges(q), page);
310 static ssize_t queue_nomerges_store(struct request_queue *q, const char *page,
314 ssize_t ret = queue_var_store(&nm, page, count);
319 blk_queue_flag_clear(QUEUE_FLAG_NOMERGES, q);
320 blk_queue_flag_clear(QUEUE_FLAG_NOXMERGES, q);
322 blk_queue_flag_set(QUEUE_FLAG_NOMERGES, q);
324 blk_queue_flag_set(QUEUE_FLAG_NOXMERGES, q);
329 static ssize_t queue_rq_affinity_show(struct request_queue *q, char *page)
331 bool set = test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags);
332 bool force = test_bit(QUEUE_FLAG_SAME_FORCE, &q->queue_flags);
334 return queue_var_show(set << force, page);
338 queue_rq_affinity_store(struct request_queue *q, const char *page, size_t count)
340 ssize_t ret = -EINVAL;
344 ret = queue_var_store(&val, page, count);
349 blk_queue_flag_set(QUEUE_FLAG_SAME_COMP, q);
350 blk_queue_flag_set(QUEUE_FLAG_SAME_FORCE, q);
351 } else if (val == 1) {
352 blk_queue_flag_set(QUEUE_FLAG_SAME_COMP, q);
353 blk_queue_flag_clear(QUEUE_FLAG_SAME_FORCE, q);
354 } else if (val == 0) {
355 blk_queue_flag_clear(QUEUE_FLAG_SAME_COMP, q);
356 blk_queue_flag_clear(QUEUE_FLAG_SAME_FORCE, q);
362 static ssize_t queue_poll_delay_show(struct request_queue *q, char *page)
366 if (q->poll_nsec == -1)
369 val = q->poll_nsec / 1000;
371 return sprintf(page, "%d\n", val);
374 static ssize_t queue_poll_delay_store(struct request_queue *q, const char *page,
379 if (!q->mq_ops || !q->mq_ops->poll)
382 err = kstrtoint(page, 10, &val);
389 q->poll_nsec = val * 1000;
394 static ssize_t queue_poll_show(struct request_queue *q, char *page)
396 return queue_var_show(test_bit(QUEUE_FLAG_POLL, &q->queue_flags), page);
399 static ssize_t queue_poll_store(struct request_queue *q, const char *page,
402 unsigned long poll_on;
405 if (!q->tag_set || q->tag_set->nr_maps <= HCTX_TYPE_POLL)
408 ret = queue_var_store(&poll_on, page, count);
413 blk_queue_flag_set(QUEUE_FLAG_POLL, q);
415 blk_queue_flag_clear(QUEUE_FLAG_POLL, q);
420 static ssize_t queue_io_timeout_show(struct request_queue *q, char *page)
422 return sprintf(page, "%u\n", jiffies_to_msecs(q->rq_timeout));
425 static ssize_t queue_io_timeout_store(struct request_queue *q, const char *page,
431 err = kstrtou32(page, 10, &val);
435 blk_queue_rq_timeout(q, msecs_to_jiffies(val));
440 static ssize_t queue_wb_lat_show(struct request_queue *q, char *page)
445 return sprintf(page, "%llu\n", div_u64(wbt_get_min_lat(q), 1000));
448 static ssize_t queue_wb_lat_store(struct request_queue *q, const char *page,
455 ret = queue_var_store64(&val, page);
461 rqos = wbt_rq_qos(q);
469 val = wbt_default_latency_nsec(q);
474 * Ensure that the queue is idled, in case the latency update
475 * ends up either enabling or disabling wbt completely. We can't
476 * have IO inflight if that happens.
478 blk_mq_freeze_queue(q);
479 blk_mq_quiesce_queue(q);
481 wbt_set_min_lat(q, val);
482 wbt_update_limits(q);
484 blk_mq_unquiesce_queue(q);
485 blk_mq_unfreeze_queue(q);
490 static ssize_t queue_wc_show(struct request_queue *q, char *page)
492 if (test_bit(QUEUE_FLAG_WC, &q->queue_flags))
493 return sprintf(page, "write back\n");
495 return sprintf(page, "write through\n");
498 static ssize_t queue_wc_store(struct request_queue *q, const char *page,
503 if (!strncmp(page, "write back", 10))
505 else if (!strncmp(page, "write through", 13) ||
506 !strncmp(page, "none", 4))
513 blk_queue_flag_set(QUEUE_FLAG_WC, q);
515 blk_queue_flag_clear(QUEUE_FLAG_WC, q);
520 static ssize_t queue_fua_show(struct request_queue *q, char *page)
522 return sprintf(page, "%u\n", test_bit(QUEUE_FLAG_FUA, &q->queue_flags));
525 static ssize_t queue_dax_show(struct request_queue *q, char *page)
527 return queue_var_show(blk_queue_dax(q), page);
530 static struct queue_sysfs_entry queue_requests_entry = {
531 .attr = {.name = "nr_requests", .mode = 0644 },
532 .show = queue_requests_show,
533 .store = queue_requests_store,
536 static struct queue_sysfs_entry queue_ra_entry = {
537 .attr = {.name = "read_ahead_kb", .mode = 0644 },
538 .show = queue_ra_show,
539 .store = queue_ra_store,
542 static struct queue_sysfs_entry queue_max_sectors_entry = {
543 .attr = {.name = "max_sectors_kb", .mode = 0644 },
544 .show = queue_max_sectors_show,
545 .store = queue_max_sectors_store,
548 static struct queue_sysfs_entry queue_max_hw_sectors_entry = {
549 .attr = {.name = "max_hw_sectors_kb", .mode = 0444 },
550 .show = queue_max_hw_sectors_show,
553 static struct queue_sysfs_entry queue_max_segments_entry = {
554 .attr = {.name = "max_segments", .mode = 0444 },
555 .show = queue_max_segments_show,
558 static struct queue_sysfs_entry queue_max_discard_segments_entry = {
559 .attr = {.name = "max_discard_segments", .mode = 0444 },
560 .show = queue_max_discard_segments_show,
563 static struct queue_sysfs_entry queue_max_integrity_segments_entry = {
564 .attr = {.name = "max_integrity_segments", .mode = 0444 },
565 .show = queue_max_integrity_segments_show,
568 static struct queue_sysfs_entry queue_max_segment_size_entry = {
569 .attr = {.name = "max_segment_size", .mode = 0444 },
570 .show = queue_max_segment_size_show,
573 static struct queue_sysfs_entry queue_iosched_entry = {
574 .attr = {.name = "scheduler", .mode = 0644 },
575 .show = elv_iosched_show,
576 .store = elv_iosched_store,
579 static struct queue_sysfs_entry queue_hw_sector_size_entry = {
580 .attr = {.name = "hw_sector_size", .mode = 0444 },
581 .show = queue_logical_block_size_show,
584 static struct queue_sysfs_entry queue_logical_block_size_entry = {
585 .attr = {.name = "logical_block_size", .mode = 0444 },
586 .show = queue_logical_block_size_show,
589 static struct queue_sysfs_entry queue_physical_block_size_entry = {
590 .attr = {.name = "physical_block_size", .mode = 0444 },
591 .show = queue_physical_block_size_show,
594 static struct queue_sysfs_entry queue_chunk_sectors_entry = {
595 .attr = {.name = "chunk_sectors", .mode = 0444 },
596 .show = queue_chunk_sectors_show,
599 static struct queue_sysfs_entry queue_io_min_entry = {
600 .attr = {.name = "minimum_io_size", .mode = 0444 },
601 .show = queue_io_min_show,
604 static struct queue_sysfs_entry queue_io_opt_entry = {
605 .attr = {.name = "optimal_io_size", .mode = 0444 },
606 .show = queue_io_opt_show,
609 static struct queue_sysfs_entry queue_discard_granularity_entry = {
610 .attr = {.name = "discard_granularity", .mode = 0444 },
611 .show = queue_discard_granularity_show,
614 static struct queue_sysfs_entry queue_discard_max_hw_entry = {
615 .attr = {.name = "discard_max_hw_bytes", .mode = 0444 },
616 .show = queue_discard_max_hw_show,
619 static struct queue_sysfs_entry queue_discard_max_entry = {
620 .attr = {.name = "discard_max_bytes", .mode = 0644 },
621 .show = queue_discard_max_show,
622 .store = queue_discard_max_store,
625 static struct queue_sysfs_entry queue_discard_zeroes_data_entry = {
626 .attr = {.name = "discard_zeroes_data", .mode = 0444 },
627 .show = queue_discard_zeroes_data_show,
630 static struct queue_sysfs_entry queue_write_same_max_entry = {
631 .attr = {.name = "write_same_max_bytes", .mode = 0444 },
632 .show = queue_write_same_max_show,
635 static struct queue_sysfs_entry queue_write_zeroes_max_entry = {
636 .attr = {.name = "write_zeroes_max_bytes", .mode = 0444 },
637 .show = queue_write_zeroes_max_show,
640 static struct queue_sysfs_entry queue_nonrot_entry = {
641 .attr = {.name = "rotational", .mode = 0644 },
642 .show = queue_show_nonrot,
643 .store = queue_store_nonrot,
646 static struct queue_sysfs_entry queue_zoned_entry = {
647 .attr = {.name = "zoned", .mode = 0444 },
648 .show = queue_zoned_show,
651 static struct queue_sysfs_entry queue_nr_zones_entry = {
652 .attr = {.name = "nr_zones", .mode = 0444 },
653 .show = queue_nr_zones_show,
656 static struct queue_sysfs_entry queue_nomerges_entry = {
657 .attr = {.name = "nomerges", .mode = 0644 },
658 .show = queue_nomerges_show,
659 .store = queue_nomerges_store,
662 static struct queue_sysfs_entry queue_rq_affinity_entry = {
663 .attr = {.name = "rq_affinity", .mode = 0644 },
664 .show = queue_rq_affinity_show,
665 .store = queue_rq_affinity_store,
668 static struct queue_sysfs_entry queue_iostats_entry = {
669 .attr = {.name = "iostats", .mode = 0644 },
670 .show = queue_show_iostats,
671 .store = queue_store_iostats,
674 static struct queue_sysfs_entry queue_random_entry = {
675 .attr = {.name = "add_random", .mode = 0644 },
676 .show = queue_show_random,
677 .store = queue_store_random,
680 static struct queue_sysfs_entry queue_poll_entry = {
681 .attr = {.name = "io_poll", .mode = 0644 },
682 .show = queue_poll_show,
683 .store = queue_poll_store,
686 static struct queue_sysfs_entry queue_poll_delay_entry = {
687 .attr = {.name = "io_poll_delay", .mode = 0644 },
688 .show = queue_poll_delay_show,
689 .store = queue_poll_delay_store,
692 static struct queue_sysfs_entry queue_wc_entry = {
693 .attr = {.name = "write_cache", .mode = 0644 },
694 .show = queue_wc_show,
695 .store = queue_wc_store,
698 static struct queue_sysfs_entry queue_fua_entry = {
699 .attr = {.name = "fua", .mode = 0444 },
700 .show = queue_fua_show,
703 static struct queue_sysfs_entry queue_dax_entry = {
704 .attr = {.name = "dax", .mode = 0444 },
705 .show = queue_dax_show,
708 static struct queue_sysfs_entry queue_io_timeout_entry = {
709 .attr = {.name = "io_timeout", .mode = 0644 },
710 .show = queue_io_timeout_show,
711 .store = queue_io_timeout_store,
714 static struct queue_sysfs_entry queue_wb_lat_entry = {
715 .attr = {.name = "wbt_lat_usec", .mode = 0644 },
716 .show = queue_wb_lat_show,
717 .store = queue_wb_lat_store,
720 #ifdef CONFIG_BLK_DEV_THROTTLING_LOW
721 static struct queue_sysfs_entry throtl_sample_time_entry = {
722 .attr = {.name = "throttle_sample_time", .mode = 0644 },
723 .show = blk_throtl_sample_time_show,
724 .store = blk_throtl_sample_time_store,
728 static struct attribute *default_attrs[] = {
729 &queue_requests_entry.attr,
730 &queue_ra_entry.attr,
731 &queue_max_hw_sectors_entry.attr,
732 &queue_max_sectors_entry.attr,
733 &queue_max_segments_entry.attr,
734 &queue_max_discard_segments_entry.attr,
735 &queue_max_integrity_segments_entry.attr,
736 &queue_max_segment_size_entry.attr,
737 &queue_iosched_entry.attr,
738 &queue_hw_sector_size_entry.attr,
739 &queue_logical_block_size_entry.attr,
740 &queue_physical_block_size_entry.attr,
741 &queue_chunk_sectors_entry.attr,
742 &queue_io_min_entry.attr,
743 &queue_io_opt_entry.attr,
744 &queue_discard_granularity_entry.attr,
745 &queue_discard_max_entry.attr,
746 &queue_discard_max_hw_entry.attr,
747 &queue_discard_zeroes_data_entry.attr,
748 &queue_write_same_max_entry.attr,
749 &queue_write_zeroes_max_entry.attr,
750 &queue_nonrot_entry.attr,
751 &queue_zoned_entry.attr,
752 &queue_nr_zones_entry.attr,
753 &queue_nomerges_entry.attr,
754 &queue_rq_affinity_entry.attr,
755 &queue_iostats_entry.attr,
756 &queue_random_entry.attr,
757 &queue_poll_entry.attr,
758 &queue_wc_entry.attr,
759 &queue_fua_entry.attr,
760 &queue_dax_entry.attr,
761 &queue_wb_lat_entry.attr,
762 &queue_poll_delay_entry.attr,
763 &queue_io_timeout_entry.attr,
764 #ifdef CONFIG_BLK_DEV_THROTTLING_LOW
765 &throtl_sample_time_entry.attr,
770 #define to_queue(atr) container_of((atr), struct queue_sysfs_entry, attr)
773 queue_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
775 struct queue_sysfs_entry *entry = to_queue(attr);
776 struct request_queue *q =
777 container_of(kobj, struct request_queue, kobj);
782 mutex_lock(&q->sysfs_lock);
783 if (blk_queue_dying(q)) {
784 mutex_unlock(&q->sysfs_lock);
787 res = entry->show(q, page);
788 mutex_unlock(&q->sysfs_lock);
793 queue_attr_store(struct kobject *kobj, struct attribute *attr,
794 const char *page, size_t length)
796 struct queue_sysfs_entry *entry = to_queue(attr);
797 struct request_queue *q;
803 q = container_of(kobj, struct request_queue, kobj);
804 mutex_lock(&q->sysfs_lock);
805 if (blk_queue_dying(q)) {
806 mutex_unlock(&q->sysfs_lock);
809 res = entry->store(q, page, length);
810 mutex_unlock(&q->sysfs_lock);
814 static void blk_free_queue_rcu(struct rcu_head *rcu_head)
816 struct request_queue *q = container_of(rcu_head, struct request_queue,
818 kmem_cache_free(blk_requestq_cachep, q);
822 * __blk_release_queue - release a request queue when it is no longer needed
823 * @work: pointer to the release_work member of the request queue to be released
826 * blk_release_queue is the counterpart of blk_init_queue(). It should be
827 * called when a request queue is being released; typically when a block
828 * device is being de-registered. Its primary task it to free the queue
832 * The low level driver must have finished any outstanding requests first
833 * via blk_cleanup_queue().
835 * Although blk_release_queue() may be called with preemption disabled,
836 * __blk_release_queue() may sleep.
838 static void __blk_release_queue(struct work_struct *work)
840 struct request_queue *q = container_of(work, typeof(*q), release_work);
842 if (test_bit(QUEUE_FLAG_POLL_STATS, &q->queue_flags))
843 blk_stat_remove_callback(q, q->poll_cb);
844 blk_stat_free_callback(q->poll_cb);
846 if (!blk_queue_dead(q)) {
848 * Last reference was dropped without having called
849 * blk_cleanup_queue().
851 WARN_ONCE(blk_queue_init_done(q),
852 "request queue %p has been registered but blk_cleanup_queue() has not been called for that queue\n",
857 WARN(blk_queue_root_blkg(q),
858 "request queue %p is being released but it has not yet been removed from the blkcg controller\n",
861 blk_free_queue_stats(q->stats);
863 blk_queue_free_zone_bitmaps(q);
868 blk_trace_shutdown(q);
871 blk_mq_debugfs_unregister(q);
873 bioset_exit(&q->bio_split);
875 ida_simple_remove(&blk_queue_ida, q->id);
876 call_rcu(&q->rcu_head, blk_free_queue_rcu);
879 static void blk_release_queue(struct kobject *kobj)
881 struct request_queue *q =
882 container_of(kobj, struct request_queue, kobj);
884 INIT_WORK(&q->release_work, __blk_release_queue);
885 schedule_work(&q->release_work);
888 static const struct sysfs_ops queue_sysfs_ops = {
889 .show = queue_attr_show,
890 .store = queue_attr_store,
893 struct kobj_type blk_queue_ktype = {
894 .sysfs_ops = &queue_sysfs_ops,
895 .default_attrs = default_attrs,
896 .release = blk_release_queue,
900 * blk_register_queue - register a block layer queue with sysfs
901 * @disk: Disk of which the request queue should be registered with sysfs.
903 int blk_register_queue(struct gendisk *disk)
906 struct device *dev = disk_to_dev(disk);
907 struct request_queue *q = disk->queue;
912 WARN_ONCE(test_bit(QUEUE_FLAG_REGISTERED, &q->queue_flags),
913 "%s is registering an already registered queue\n",
914 kobject_name(&dev->kobj));
915 blk_queue_flag_set(QUEUE_FLAG_REGISTERED, q);
918 * SCSI probing may synchronously create and destroy a lot of
919 * request_queues for non-existent devices. Shutting down a fully
920 * functional queue takes measureable wallclock time as RCU grace
921 * periods are involved. To avoid excessive latency in these
922 * cases, a request_queue starts out in a degraded mode which is
923 * faster to shut down and is made fully functional here as
924 * request_queues for non-existent devices never get registered.
926 if (!blk_queue_init_done(q)) {
927 blk_queue_flag_set(QUEUE_FLAG_INIT_DONE, q);
928 percpu_ref_switch_to_percpu(&q->q_usage_counter);
931 ret = blk_trace_init_sysfs(dev);
935 /* Prevent changes through sysfs until registration is completed. */
936 mutex_lock(&q->sysfs_lock);
938 ret = kobject_add(&q->kobj, kobject_get(&dev->kobj), "%s", "queue");
940 blk_trace_remove_sysfs(dev);
944 if (queue_is_mq(q)) {
945 __blk_mq_register_dev(dev, q);
946 blk_mq_debugfs_register(q);
949 kobject_uevent(&q->kobj, KOBJ_ADD);
951 wbt_enable_default(q);
953 blk_throtl_register_queue(q);
956 ret = elv_register_queue(q);
958 mutex_unlock(&q->sysfs_lock);
959 kobject_uevent(&q->kobj, KOBJ_REMOVE);
960 kobject_del(&q->kobj);
961 blk_trace_remove_sysfs(dev);
962 kobject_put(&dev->kobj);
968 mutex_unlock(&q->sysfs_lock);
971 EXPORT_SYMBOL_GPL(blk_register_queue);
974 * blk_unregister_queue - counterpart of blk_register_queue()
975 * @disk: Disk of which the request queue should be unregistered from sysfs.
977 * Note: the caller is responsible for guaranteeing that this function is called
978 * after blk_register_queue() has finished.
980 void blk_unregister_queue(struct gendisk *disk)
982 struct request_queue *q = disk->queue;
987 /* Return early if disk->queue was never registered. */
988 if (!test_bit(QUEUE_FLAG_REGISTERED, &q->queue_flags))
992 * Since sysfs_remove_dir() prevents adding new directory entries
993 * before removal of existing entries starts, protect against
994 * concurrent elv_iosched_store() calls.
996 mutex_lock(&q->sysfs_lock);
998 blk_queue_flag_clear(QUEUE_FLAG_REGISTERED, q);
1001 * Remove the sysfs attributes before unregistering the queue data
1002 * structures that can be modified through sysfs.
1005 blk_mq_unregister_dev(disk_to_dev(disk), q);
1006 mutex_unlock(&q->sysfs_lock);
1008 kobject_uevent(&q->kobj, KOBJ_REMOVE);
1009 kobject_del(&q->kobj);
1010 blk_trace_remove_sysfs(disk_to_dev(disk));
1012 mutex_lock(&q->sysfs_lock);
1014 elv_unregister_queue(q);
1015 mutex_unlock(&q->sysfs_lock);
1017 kobject_put(&disk_to_dev(disk)->kobj);