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667257e8b2
The original commite9a823fb34(block: fix warning when I/O elevator is changed as request_queue is being removed) is pretty conflated. "conflated" because the resource being protected by q->sysfs_lock isn't the queue_flags (it is the 'queue' kobj). q->sysfs_lock serializes __elevator_change() (via elv_iosched_store) from racing with blk_unregister_queue(): 1) By holding q->sysfs_lock first, __elevator_change() can complete before a racing blk_unregister_queue(). 2) Conversely, __elevator_change() is testing for QUEUE_FLAG_REGISTERED in case elv_iosched_store() loses the race with blk_unregister_queue(), it needs a way to know the 'queue' kobj isn't there. Expand the scope of blk_unregister_queue()'s q->sysfs_lock use so it is held until after the 'queue' kobj is removed. To do so blk_mq_unregister_dev() must not also take q->sysfs_lock. So rename __blk_mq_unregister_dev() to blk_mq_unregister_dev(). Also, blk_unregister_queue() should use q->queue_lock to protect against any concurrent writes to q->queue_flags -- even though chances are the queue is being cleaned up so no concurrent writes are likely. Fixes:e9a823fb34("block: fix warning when I/O elevator is changed as request_queue is being removed") Signed-off-by: Mike Snitzer <snitzer@redhat.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
381 lines
8.1 KiB
C
381 lines
8.1 KiB
C
#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/backing-dev.h>
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#include <linux/bio.h>
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#include <linux/blkdev.h>
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#include <linux/mm.h>
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <linux/workqueue.h>
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#include <linux/smp.h>
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#include <linux/blk-mq.h>
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#include "blk-mq.h"
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#include "blk-mq-tag.h"
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static void blk_mq_sysfs_release(struct kobject *kobj)
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{
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}
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static void blk_mq_hw_sysfs_release(struct kobject *kobj)
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{
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struct blk_mq_hw_ctx *hctx = container_of(kobj, struct blk_mq_hw_ctx,
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kobj);
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free_cpumask_var(hctx->cpumask);
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kfree(hctx->ctxs);
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kfree(hctx);
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}
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struct blk_mq_ctx_sysfs_entry {
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struct attribute attr;
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ssize_t (*show)(struct blk_mq_ctx *, char *);
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ssize_t (*store)(struct blk_mq_ctx *, const char *, size_t);
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};
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struct blk_mq_hw_ctx_sysfs_entry {
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struct attribute attr;
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ssize_t (*show)(struct blk_mq_hw_ctx *, char *);
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ssize_t (*store)(struct blk_mq_hw_ctx *, const char *, size_t);
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};
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static ssize_t blk_mq_sysfs_show(struct kobject *kobj, struct attribute *attr,
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char *page)
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{
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struct blk_mq_ctx_sysfs_entry *entry;
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struct blk_mq_ctx *ctx;
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struct request_queue *q;
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ssize_t res;
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entry = container_of(attr, struct blk_mq_ctx_sysfs_entry, attr);
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ctx = container_of(kobj, struct blk_mq_ctx, kobj);
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q = ctx->queue;
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if (!entry->show)
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return -EIO;
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res = -ENOENT;
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mutex_lock(&q->sysfs_lock);
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if (!blk_queue_dying(q))
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res = entry->show(ctx, page);
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mutex_unlock(&q->sysfs_lock);
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return res;
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}
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static ssize_t blk_mq_sysfs_store(struct kobject *kobj, struct attribute *attr,
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const char *page, size_t length)
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{
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struct blk_mq_ctx_sysfs_entry *entry;
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struct blk_mq_ctx *ctx;
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struct request_queue *q;
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ssize_t res;
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entry = container_of(attr, struct blk_mq_ctx_sysfs_entry, attr);
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ctx = container_of(kobj, struct blk_mq_ctx, kobj);
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q = ctx->queue;
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if (!entry->store)
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return -EIO;
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res = -ENOENT;
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mutex_lock(&q->sysfs_lock);
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if (!blk_queue_dying(q))
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res = entry->store(ctx, page, length);
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mutex_unlock(&q->sysfs_lock);
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return res;
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}
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static ssize_t blk_mq_hw_sysfs_show(struct kobject *kobj,
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struct attribute *attr, char *page)
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{
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struct blk_mq_hw_ctx_sysfs_entry *entry;
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struct blk_mq_hw_ctx *hctx;
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struct request_queue *q;
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ssize_t res;
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entry = container_of(attr, struct blk_mq_hw_ctx_sysfs_entry, attr);
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hctx = container_of(kobj, struct blk_mq_hw_ctx, kobj);
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q = hctx->queue;
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if (!entry->show)
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return -EIO;
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res = -ENOENT;
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mutex_lock(&q->sysfs_lock);
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if (!blk_queue_dying(q))
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res = entry->show(hctx, page);
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mutex_unlock(&q->sysfs_lock);
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return res;
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}
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static ssize_t blk_mq_hw_sysfs_store(struct kobject *kobj,
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struct attribute *attr, const char *page,
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size_t length)
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{
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struct blk_mq_hw_ctx_sysfs_entry *entry;
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struct blk_mq_hw_ctx *hctx;
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struct request_queue *q;
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ssize_t res;
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entry = container_of(attr, struct blk_mq_hw_ctx_sysfs_entry, attr);
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hctx = container_of(kobj, struct blk_mq_hw_ctx, kobj);
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q = hctx->queue;
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if (!entry->store)
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return -EIO;
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res = -ENOENT;
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mutex_lock(&q->sysfs_lock);
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if (!blk_queue_dying(q))
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res = entry->store(hctx, page, length);
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mutex_unlock(&q->sysfs_lock);
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return res;
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}
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static ssize_t blk_mq_hw_sysfs_nr_tags_show(struct blk_mq_hw_ctx *hctx,
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char *page)
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{
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return sprintf(page, "%u\n", hctx->tags->nr_tags);
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}
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static ssize_t blk_mq_hw_sysfs_nr_reserved_tags_show(struct blk_mq_hw_ctx *hctx,
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char *page)
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{
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return sprintf(page, "%u\n", hctx->tags->nr_reserved_tags);
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}
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static ssize_t blk_mq_hw_sysfs_cpus_show(struct blk_mq_hw_ctx *hctx, char *page)
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{
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unsigned int i, first = 1;
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ssize_t ret = 0;
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for_each_cpu(i, hctx->cpumask) {
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if (first)
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ret += sprintf(ret + page, "%u", i);
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else
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ret += sprintf(ret + page, ", %u", i);
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first = 0;
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}
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ret += sprintf(ret + page, "\n");
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return ret;
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}
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static struct attribute *default_ctx_attrs[] = {
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NULL,
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};
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static struct blk_mq_hw_ctx_sysfs_entry blk_mq_hw_sysfs_nr_tags = {
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.attr = {.name = "nr_tags", .mode = S_IRUGO },
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.show = blk_mq_hw_sysfs_nr_tags_show,
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};
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static struct blk_mq_hw_ctx_sysfs_entry blk_mq_hw_sysfs_nr_reserved_tags = {
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.attr = {.name = "nr_reserved_tags", .mode = S_IRUGO },
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.show = blk_mq_hw_sysfs_nr_reserved_tags_show,
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};
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static struct blk_mq_hw_ctx_sysfs_entry blk_mq_hw_sysfs_cpus = {
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.attr = {.name = "cpu_list", .mode = S_IRUGO },
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.show = blk_mq_hw_sysfs_cpus_show,
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};
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static struct attribute *default_hw_ctx_attrs[] = {
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&blk_mq_hw_sysfs_nr_tags.attr,
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&blk_mq_hw_sysfs_nr_reserved_tags.attr,
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&blk_mq_hw_sysfs_cpus.attr,
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NULL,
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};
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static const struct sysfs_ops blk_mq_sysfs_ops = {
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.show = blk_mq_sysfs_show,
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.store = blk_mq_sysfs_store,
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};
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static const struct sysfs_ops blk_mq_hw_sysfs_ops = {
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.show = blk_mq_hw_sysfs_show,
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.store = blk_mq_hw_sysfs_store,
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};
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static struct kobj_type blk_mq_ktype = {
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.sysfs_ops = &blk_mq_sysfs_ops,
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.release = blk_mq_sysfs_release,
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};
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static struct kobj_type blk_mq_ctx_ktype = {
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.sysfs_ops = &blk_mq_sysfs_ops,
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.default_attrs = default_ctx_attrs,
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.release = blk_mq_sysfs_release,
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};
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static struct kobj_type blk_mq_hw_ktype = {
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.sysfs_ops = &blk_mq_hw_sysfs_ops,
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.default_attrs = default_hw_ctx_attrs,
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.release = blk_mq_hw_sysfs_release,
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};
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static void blk_mq_unregister_hctx(struct blk_mq_hw_ctx *hctx)
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{
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struct blk_mq_ctx *ctx;
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int i;
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if (!hctx->nr_ctx)
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return;
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hctx_for_each_ctx(hctx, ctx, i)
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kobject_del(&ctx->kobj);
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kobject_del(&hctx->kobj);
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}
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static int blk_mq_register_hctx(struct blk_mq_hw_ctx *hctx)
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{
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struct request_queue *q = hctx->queue;
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struct blk_mq_ctx *ctx;
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int i, ret;
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if (!hctx->nr_ctx)
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return 0;
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ret = kobject_add(&hctx->kobj, &q->mq_kobj, "%u", hctx->queue_num);
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if (ret)
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return ret;
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hctx_for_each_ctx(hctx, ctx, i) {
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ret = kobject_add(&ctx->kobj, &hctx->kobj, "cpu%u", ctx->cpu);
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if (ret)
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break;
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}
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return ret;
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}
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void blk_mq_unregister_dev(struct device *dev, struct request_queue *q)
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{
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struct blk_mq_hw_ctx *hctx;
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int i;
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lockdep_assert_held(&q->sysfs_lock);
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queue_for_each_hw_ctx(q, hctx, i)
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blk_mq_unregister_hctx(hctx);
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kobject_uevent(&q->mq_kobj, KOBJ_REMOVE);
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kobject_del(&q->mq_kobj);
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kobject_put(&dev->kobj);
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q->mq_sysfs_init_done = false;
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}
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void blk_mq_hctx_kobj_init(struct blk_mq_hw_ctx *hctx)
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{
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kobject_init(&hctx->kobj, &blk_mq_hw_ktype);
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}
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void blk_mq_sysfs_deinit(struct request_queue *q)
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{
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struct blk_mq_ctx *ctx;
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int cpu;
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for_each_possible_cpu(cpu) {
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ctx = per_cpu_ptr(q->queue_ctx, cpu);
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kobject_put(&ctx->kobj);
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}
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kobject_put(&q->mq_kobj);
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}
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void blk_mq_sysfs_init(struct request_queue *q)
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{
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struct blk_mq_ctx *ctx;
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int cpu;
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kobject_init(&q->mq_kobj, &blk_mq_ktype);
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for_each_possible_cpu(cpu) {
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ctx = per_cpu_ptr(q->queue_ctx, cpu);
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kobject_init(&ctx->kobj, &blk_mq_ctx_ktype);
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}
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}
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int __blk_mq_register_dev(struct device *dev, struct request_queue *q)
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{
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struct blk_mq_hw_ctx *hctx;
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int ret, i;
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WARN_ON_ONCE(!q->kobj.parent);
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lockdep_assert_held(&q->sysfs_lock);
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ret = kobject_add(&q->mq_kobj, kobject_get(&dev->kobj), "%s", "mq");
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if (ret < 0)
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goto out;
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kobject_uevent(&q->mq_kobj, KOBJ_ADD);
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queue_for_each_hw_ctx(q, hctx, i) {
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ret = blk_mq_register_hctx(hctx);
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if (ret)
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goto unreg;
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}
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q->mq_sysfs_init_done = true;
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out:
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return ret;
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unreg:
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while (--i >= 0)
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blk_mq_unregister_hctx(q->queue_hw_ctx[i]);
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kobject_uevent(&q->mq_kobj, KOBJ_REMOVE);
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kobject_del(&q->mq_kobj);
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kobject_put(&dev->kobj);
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return ret;
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}
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int blk_mq_register_dev(struct device *dev, struct request_queue *q)
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{
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int ret;
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mutex_lock(&q->sysfs_lock);
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ret = __blk_mq_register_dev(dev, q);
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mutex_unlock(&q->sysfs_lock);
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return ret;
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}
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EXPORT_SYMBOL_GPL(blk_mq_register_dev);
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void blk_mq_sysfs_unregister(struct request_queue *q)
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{
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struct blk_mq_hw_ctx *hctx;
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int i;
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mutex_lock(&q->sysfs_lock);
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if (!q->mq_sysfs_init_done)
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goto unlock;
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queue_for_each_hw_ctx(q, hctx, i)
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blk_mq_unregister_hctx(hctx);
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unlock:
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mutex_unlock(&q->sysfs_lock);
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}
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int blk_mq_sysfs_register(struct request_queue *q)
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{
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struct blk_mq_hw_ctx *hctx;
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int i, ret = 0;
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mutex_lock(&q->sysfs_lock);
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if (!q->mq_sysfs_init_done)
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goto unlock;
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queue_for_each_hw_ctx(q, hctx, i) {
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ret = blk_mq_register_hctx(hctx);
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if (ret)
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break;
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}
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unlock:
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mutex_unlock(&q->sysfs_lock);
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return ret;
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}
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