Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit c6a4759e authored by Josef Bacik's avatar Josef Bacik Committed by Jens Axboe
Browse files

nbd: add device refcounting 



In order to support deleting the device on disconnect we need to
refcount the actual nbd_device struct.  So add the refcounting framework
and change how we free the normal devices at rmmod time so we can catch
reference leaks.

Signed-off-by: default avatarJosef Bacik <jbacik@fb.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 47d902b9

drivers/block/nbd.c

+86 −18
Original line number Diff line number Diff line
@@ -99,10 +99,12 @@ struct nbd_device { 


	int index;

	refcount_t config_refs;

	refcount_t refs;

	struct nbd_config *config;

	struct mutex config_lock;

	struct gendisk *disk;



	struct list_head list;

	struct task_struct *task_recv;

	struct task_struct *task_setup;

};
@@ -165,6 +167,28 @@ static struct device_attribute pid_attr = { 
	.show = pid_show,

};



static void nbd_dev_remove(struct nbd_device *nbd)

{

	struct gendisk *disk = nbd->disk;

	if (disk) {

		del_gendisk(disk);

		blk_cleanup_queue(disk->queue);

		blk_mq_free_tag_set(&nbd->tag_set);

		put_disk(disk);

	}

	kfree(nbd);

}



static void nbd_put(struct nbd_device *nbd)

{

	if (refcount_dec_and_mutex_lock(&nbd->refs,

					&nbd_index_mutex)) {

		idr_remove(&nbd_index_idr, nbd->index);

		mutex_unlock(&nbd_index_mutex);

		nbd_dev_remove(nbd);

	}

}



static int nbd_disconnected(struct nbd_config *config)

{

	return test_bit(NBD_DISCONNECTED, &config->runtime_flags) ||
@@ -1005,6 +1029,7 @@ static void nbd_config_put(struct nbd_device *nbd) 
		}

		nbd_reset(nbd);

		mutex_unlock(&nbd->config_lock);

		nbd_put(nbd);

		module_put(THIS_MODULE);

	}

}
@@ -1199,6 +1224,10 @@ static int nbd_open(struct block_device *bdev, fmode_t mode) 
		ret = -ENXIO;

		goto out;

	}

	if (!refcount_inc_not_zero(&nbd->refs)) {

		ret = -ENXIO;

		goto out;

	}

	if (!refcount_inc_not_zero(&nbd->config_refs)) {

		struct nbd_config *config;
@@ -1214,6 +1243,7 @@ static int nbd_open(struct block_device *bdev, fmode_t mode) 
			goto out;

		}

		refcount_set(&nbd->config_refs, 1);

		refcount_inc(&nbd->refs);

		mutex_unlock(&nbd->config_lock);

	}

out:
@@ -1225,6 +1255,7 @@ static void nbd_release(struct gendisk *disk, fmode_t mode) 
{

	struct nbd_device *nbd = disk->private_data;

	nbd_config_put(nbd);

	nbd_put(nbd);

}



static const struct block_device_operations nbd_fops =
@@ -1378,18 +1409,6 @@ static const struct blk_mq_ops nbd_mq_ops = { 
	.timeout	= nbd_xmit_timeout,

};



static void nbd_dev_remove(struct nbd_device *nbd)

{

	struct gendisk *disk = nbd->disk;

	if (disk) {

		del_gendisk(disk);

		blk_cleanup_queue(disk->queue);

		blk_mq_free_tag_set(&nbd->tag_set);

		put_disk(disk);

	}

	kfree(nbd);

}



static int nbd_dev_add(int index)

{

	struct nbd_device *nbd;
@@ -1452,6 +1471,8 @@ static int nbd_dev_add(int index) 


	mutex_init(&nbd->config_lock);

	refcount_set(&nbd->config_refs, 0);

	refcount_set(&nbd->refs, 1);

	INIT_LIST_HEAD(&nbd->list);

	disk->major = NBD_MAJOR;

	disk->first_minor = index << part_shift;

	disk->fops = &nbd_fops;
@@ -1549,16 +1570,26 @@ static int nbd_genl_connect(struct sk_buff *skb, struct genl_info *info) 
	} else {

		nbd = idr_find(&nbd_index_idr, index);

	}

	mutex_unlock(&nbd_index_mutex);

	if (!nbd) {

		printk(KERN_ERR "nbd: couldn't find device at index %d\n",

		       index);

		mutex_unlock(&nbd_index_mutex);

		return -EINVAL;

	}

	if (!refcount_inc_not_zero(&nbd->refs)) {

		mutex_unlock(&nbd_index_mutex);

		if (index == -1)

			goto again;

		printk(KERN_ERR "nbd: device at index %d is going down\n",

		       index);

		return -EINVAL;

	}

	mutex_unlock(&nbd_index_mutex);



	mutex_lock(&nbd->config_lock);

	if (refcount_read(&nbd->config_refs)) {

		mutex_unlock(&nbd->config_lock);

		nbd_put(nbd);

		if (index == -1)

			goto again;

		printk(KERN_ERR "nbd: nbd%d already in use\n", index);
@@ -1566,11 +1597,13 @@ static int nbd_genl_connect(struct sk_buff *skb, struct genl_info *info) 
	}

	if (WARN_ON(nbd->config)) {

		mutex_unlock(&nbd->config_lock);

		nbd_put(nbd);

		return -EINVAL;

	}

	config = nbd->config = nbd_alloc_config();

	if (!nbd->config) {

		mutex_unlock(&nbd->config_lock);

		nbd_put(nbd);

		printk(KERN_ERR "nbd: couldn't allocate config\n");

		return -ENOMEM;

	}
@@ -1655,14 +1688,23 @@ static int nbd_genl_disconnect(struct sk_buff *skb, struct genl_info *info) 
	index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);

	mutex_lock(&nbd_index_mutex);

	nbd = idr_find(&nbd_index_idr, index);

	mutex_unlock(&nbd_index_mutex);

	if (!nbd) {

		mutex_unlock(&nbd_index_mutex);

		printk(KERN_ERR "nbd: couldn't find device at index %d\n",

		       index);

		return -EINVAL;

	}

	if (!refcount_inc_not_zero(&nbd->config_refs))

	if (!refcount_inc_not_zero(&nbd->refs)) {

		mutex_unlock(&nbd_index_mutex);

		printk(KERN_ERR "nbd: device at index %d is going down\n",

		       index);

		return -EINVAL;

	}

	mutex_unlock(&nbd_index_mutex);

	if (!refcount_inc_not_zero(&nbd->config_refs)) {

		nbd_put(nbd);

		return 0;

	}

	mutex_lock(&nbd->config_lock);

	nbd_disconnect(nbd);

	mutex_unlock(&nbd->config_lock);
@@ -1670,6 +1712,7 @@ static int nbd_genl_disconnect(struct sk_buff *skb, struct genl_info *info) 
			       &nbd->config->runtime_flags))

		nbd_config_put(nbd);

	nbd_config_put(nbd);

	nbd_put(nbd);

	return 0;

}
@@ -1690,16 +1733,24 @@ static int nbd_genl_reconfigure(struct sk_buff *skb, struct genl_info *info) 
	index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);

	mutex_lock(&nbd_index_mutex);

	nbd = idr_find(&nbd_index_idr, index);

	mutex_unlock(&nbd_index_mutex);

	if (!nbd) {

		mutex_unlock(&nbd_index_mutex);

		printk(KERN_ERR "nbd: couldn't find a device at index %d\n",

		       index);

		return -EINVAL;

	}

	if (!refcount_inc_not_zero(&nbd->refs)) {

		mutex_unlock(&nbd_index_mutex);

		printk(KERN_ERR "nbd: device at index %d is going down\n",

		       index);

		return -EINVAL;

	}

	mutex_unlock(&nbd_index_mutex);



	if (!refcount_inc_not_zero(&nbd->config_refs)) {

		dev_err(nbd_to_dev(nbd),

			"not configured, cannot reconfigure\n");

		nbd_put(nbd);

		return -EINVAL;

	}
@@ -1758,6 +1809,7 @@ static int nbd_genl_reconfigure(struct sk_buff *skb, struct genl_info *info) 
out:

	mutex_unlock(&nbd->config_lock);

	nbd_config_put(nbd);

	nbd_put(nbd);

	return ret;

}
@@ -2003,16 +2055,32 @@ static int __init nbd_init(void) 


static int nbd_exit_cb(int id, void *ptr, void *data)

{

	struct list_head *list = (struct list_head *)data;

	struct nbd_device *nbd = ptr;

	nbd_dev_remove(nbd);



	refcount_inc(&nbd->refs);

	list_add_tail(&nbd->list, list);

	return 0;

}



static void __exit nbd_cleanup(void)

{

	struct nbd_device *nbd;

	LIST_HEAD(del_list);



	nbd_dbg_close();



	idr_for_each(&nbd_index_idr, &nbd_exit_cb, NULL);

	mutex_lock(&nbd_index_mutex);

	idr_for_each(&nbd_index_idr, &nbd_exit_cb, &del_list);

	mutex_unlock(&nbd_index_mutex);



	list_for_each_entry(nbd, &del_list, list) {

		if (refcount_read(&nbd->refs) != 2)

			printk(KERN_ERR "nbd: possibly leaking a device\n");

		nbd_put(nbd);

		nbd_put(nbd);

	}



	idr_destroy(&nbd_index_idr);

	genl_unregister_family(&nbd_genl_family);

	destroy_workqueue(recv_workqueue);