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blk-mq: Register <dev>/queue/mq after having registered <dev>/queue 

A later patch in this series will modify blk_mq_debugfs_register()
such that it uses q->kobj.parent to determine the name of a
request queue. Hence make sure that that pointer is initialized
before blk_mq_debugfs_register() is called. To avoid lock inversion,
protect sysfs / debugfs registration with the queue sysfs_lock
instead of the global mutex all_q_mutex.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Bart Van Assche 2017-04-26 13:47:48 -07:00 committed by Jens Axboe
parent 1608fd1ca3
commit 2d0364c8c1
3 changed files with 32 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

35
block/blk-mq-sysfs.c
View File

@ -253,6 +253,8 @@ static void __blk_mq_unregister_dev(struct device *dev, struct request_queue *q)
struct blk_mq_hw_ctx *hctx;
int i;
lockdep_assert_held(&q->sysfs_lock);
queue_for_each_hw_ctx(q, hctx, i)
blk_mq_unregister_hctx(hctx);
@ -267,9 +269,9 @@ static void __blk_mq_unregister_dev(struct device *dev, struct request_queue *q)
void blk_mq_unregister_dev(struct device *dev, struct request_queue *q)
{
blk_mq_disable_hotplug();
mutex_lock(&q->sysfs_lock);
__blk_mq_unregister_dev(dev, q);
blk_mq_enable_hotplug();
mutex_unlock(&q->sysfs_lock);
}
void blk_mq_hctx_kobj_init(struct blk_mq_hw_ctx *hctx)
@ -302,12 +304,13 @@ void blk_mq_sysfs_init(struct request_queue *q)
}
}
int blk_mq_register_dev(struct device *dev, struct request_queue *q)
int __blk_mq_register_dev(struct device *dev, struct request_queue *q)
{
struct blk_mq_hw_ctx *hctx;
int ret, i;
blk_mq_disable_hotplug();
WARN_ON_ONCE(!q->kobj.parent);
lockdep_assert_held(&q->sysfs_lock);
ret = kobject_add(&q->mq_kobj, kobject_get(&dev->kobj), "%s", "mq");
if (ret < 0)
@ -327,8 +330,18 @@ int blk_mq_register_dev(struct device *dev, struct request_queue *q)
__blk_mq_unregister_dev(dev, q);
else
q->mq_sysfs_init_done = true;
out:
blk_mq_enable_hotplug();
return ret;
}
int blk_mq_register_dev(struct device *dev, struct request_queue *q)
{
int ret;
mutex_lock(&q->sysfs_lock);
ret = __blk_mq_register_dev(dev, q);
mutex_unlock(&q->sysfs_lock);
return ret;
}
@ -339,13 +352,17 @@ void blk_mq_sysfs_unregister(struct request_queue *q)
struct blk_mq_hw_ctx *hctx;
int i;
mutex_lock(&q->sysfs_lock);
if (!q->mq_sysfs_init_done)
return;
goto unlock;
blk_mq_debugfs_unregister_hctxs(q);
queue_for_each_hw_ctx(q, hctx, i)
blk_mq_unregister_hctx(hctx);
unlock:
mutex_unlock(&q->sysfs_lock);
}
int blk_mq_sysfs_register(struct request_queue *q)
@ -353,8 +370,9 @@ int blk_mq_sysfs_register(struct request_queue *q)
struct blk_mq_hw_ctx *hctx;
int i, ret = 0;
mutex_lock(&q->sysfs_lock);
if (!q->mq_sysfs_init_done)
return ret;
goto unlock;
blk_mq_debugfs_register_hctxs(q);
@ -364,5 +382,8 @@ int blk_mq_sysfs_register(struct request_queue *q)
break;
}
unlock:
mutex_unlock(&q->sysfs_lock);
return ret;
}

1
block/blk-mq.h
View File

@ -78,6 +78,7 @@ static inline struct blk_mq_hw_ctx *blk_mq_map_queue(struct request_queue *q,
*/
extern void blk_mq_sysfs_init(struct request_queue *q);
extern void blk_mq_sysfs_deinit(struct request_queue *q);
extern int __blk_mq_register_dev(struct device *dev, struct request_queue *q);
extern int blk_mq_sysfs_register(struct request_queue *q);
extern void blk_mq_sysfs_unregister(struct request_queue *q);
extern void blk_mq_hctx_kobj_init(struct blk_mq_hw_ctx *hctx);

6
block/blk-sysfs.c
View File

@ -877,9 +877,6 @@ int blk_register_queue(struct gendisk *disk)
if (ret)
return ret;
if (q->mq_ops)
blk_mq_register_dev(dev, q);
/* Prevent changes through sysfs until registration is completed. */
mutex_lock(&q->sysfs_lock);
@ -889,6 +886,9 @@ int blk_register_queue(struct gendisk *disk)
goto unlock;
}
if (q->mq_ops)
__blk_mq_register_dev(dev, q);
kobject_uevent(&q->kobj, KOBJ_ADD);
wbt_enable_default(q);