Commit 2d0364c8 authored by Bart Van Assche's avatar Bart Van Assche Committed by Jens Axboe
Browse files

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: default avatarBart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: default avatarHannes Reinecke <hare@suse.com>
Reviewed-by: default avatarOmar Sandoval <osandov@fb.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 1608fd1c

block/blk-mq-sysfs.c

+28 −7
Original line number Diff line number Diff line
@@ -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;

}

block/blk-mq.h

+1 −0
Original line number Diff line number Diff line
@@ -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);

block/blk-sysfs.c

+3 −3
Original line number Diff line number Diff line
@@ -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);

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