RDMA/uverbs: Use cdev_device_add() instead of cdev_add()

Instead of doing two step process to add char device and create underlying
device, use cdev_device_add() which does both.

Currently a kobject per uverbs_device is created to keep reference to its
holding ib_uverbs_device in addition to its underlying device 'dev'.

Instead just use uverbs_device->dev to keep a reference to.

With this change there is single reference tracker for ib_uverbs_device
structure.

This allows for subsequent patch to registers group attribute as well
using single API cdev_device_add().
Signed-off-by: Parav Pandit <parav@mellanox.com>
Reviewed-by: Daniel Jurgens <danielj@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/core/uverbs.h

@@ -100,13 +100,12 @@ struct ib_uverbs_device {
 	atomic_t				refcount;
 	int					num_comp_vectors;
 	struct completion			comp;
-	struct device			       *dev;
+	struct device				dev;
 	struct ib_device	__rcu	       *ib_dev;
 	int					devnum;
 	struct cdev			        cdev;
 	struct rb_root				xrcd_tree;
 	struct mutex				xrcd_tree_mutex;
-	struct kobject				kobj;
 	struct srcu_struct			disassociate_srcu;
 	struct mutex				lists_mutex; /* protect lists */
 	struct list_head			uverbs_file_list;

drivers/infiniband/core/uverbs_main.c

@@ -169,20 +169,16 @@ int uverbs_dealloc_mw(struct ib_mw *mw)
 	return ret;
 }
 
-static void ib_uverbs_release_dev(struct kobject *kobj)
+static void ib_uverbs_release_dev(struct device *device)
 {
 	struct ib_uverbs_device *dev =
-		container_of(kobj, struct ib_uverbs_device, kobj);
+			container_of(device, struct ib_uverbs_device, dev);
 
 	uverbs_destroy_api(dev->uapi);
 	cleanup_srcu_struct(&dev->disassociate_srcu);
 	kfree(dev);
 }
 
-static struct kobj_type ib_uverbs_dev_ktype = {
-	.release = ib_uverbs_release_dev,
-};
-
 static void ib_uverbs_release_async_event_file(struct kref *ref)
 {
 	struct ib_uverbs_async_event_file *file =
@@ -265,7 +261,7 @@ void ib_uverbs_release_file(struct kref *ref)
 	if (atomic_dec_and_test(&file->device->refcount))
 		ib_uverbs_comp_dev(file->device);
 
-	kobject_put(&file->device->kobj);
+	put_device(&file->device->dev);
 	kfree(file);
 }
 
@@ -838,6 +834,7 @@ static int ib_uverbs_open(struct inode *inode, struct file *filp)
 	if (!atomic_inc_not_zero(&dev->refcount))
 		return -ENXIO;
 
+	get_device(&dev->dev);
 	srcu_key = srcu_read_lock(&dev->disassociate_srcu);
 	mutex_lock(&dev->lists_mutex);
 	ib_dev = srcu_dereference(dev->ib_dev,
@@ -877,7 +874,6 @@ static int ib_uverbs_open(struct inode *inode, struct file *filp)
 	init_rwsem(&file->hw_destroy_rwsem);
 
 	filp->private_data = file;
-	kobject_get(&dev->kobj);
 	list_add_tail(&file->list, &dev->uverbs_file_list);
 	mutex_unlock(&dev->lists_mutex);
 	srcu_read_unlock(&dev->disassociate_srcu, srcu_key);
@@ -898,6 +894,7 @@ static int ib_uverbs_open(struct inode *inode, struct file *filp)
 	if (atomic_dec_and_test(&dev->refcount))
 		ib_uverbs_comp_dev(dev);
 
+	put_device(&dev->dev);
 	return ret;
 }
 
@@ -953,14 +950,12 @@ static struct ib_client uverbs_client = {
 static ssize_t show_ibdev(struct device *device, struct device_attribute *attr,
 			  char *buf)
 {
+	struct ib_uverbs_device *dev =
+			container_of(device, struct ib_uverbs_device, dev);
 	int ret = -ENODEV;
 	int srcu_key;
-	struct ib_uverbs_device *dev = dev_get_drvdata(device);
 	struct ib_device *ib_dev;
 
-	if (!dev)
-		return -ENODEV;
-
 	srcu_key = srcu_read_lock(&dev->disassociate_srcu);
 	ib_dev = srcu_dereference(dev->ib_dev, &dev->disassociate_srcu);
 	if (ib_dev)
@@ -974,13 +969,12 @@ static DEVICE_ATTR(ibdev, S_IRUGO, show_ibdev, NULL);
 static ssize_t show_dev_abi_version(struct device *device,
 				    struct device_attribute *attr, char *buf)
 {
-	struct ib_uverbs_device *dev = dev_get_drvdata(device);
+	struct ib_uverbs_device *dev =
+			container_of(device, struct ib_uverbs_device, dev);
 	int ret = -ENODEV;
 	int srcu_key;
 	struct ib_device *ib_dev;
 
-	if (!dev)
-		return -ENODEV;
 	srcu_key = srcu_read_lock(&dev->disassociate_srcu);
 	ib_dev = srcu_dereference(dev->ib_dev, &dev->disassociate_srcu);
 	if (ib_dev)
@@ -1031,7 +1025,6 @@ static void ib_uverbs_add_one(struct ib_device *device)
 	init_completion(&uverbs_dev->comp);
 	uverbs_dev->xrcd_tree = RB_ROOT;
 	mutex_init(&uverbs_dev->xrcd_tree_mutex);
-	kobject_init(&uverbs_dev->kobj, &ib_uverbs_dev_ktype);
 	mutex_init(&uverbs_dev->lists_mutex);
 	INIT_LIST_HEAD(&uverbs_dev->uverbs_file_list);
 	INIT_LIST_HEAD(&uverbs_dev->uverbs_events_file_list);
@@ -1052,40 +1045,41 @@ static void ib_uverbs_add_one(struct ib_device *device)
 	if (ib_uverbs_create_uapi(device, uverbs_dev))
 		goto err_uapi;
 
-	cdev_init(&uverbs_dev->cdev, NULL);
+	device_initialize(&uverbs_dev->dev);
+	uverbs_dev->dev.class = uverbs_class;
+	uverbs_dev->dev.parent = device->dev.parent;
+	uverbs_dev->dev.devt = base;
+	uverbs_dev->dev.release = ib_uverbs_release_dev;
+	dev_set_name(&uverbs_dev->dev, "uverbs%d", uverbs_dev->devnum);
+
+	cdev_init(&uverbs_dev->cdev,
+		  device->mmap ? &uverbs_mmap_fops : &uverbs_fops);
 	uverbs_dev->cdev.owner = THIS_MODULE;
-	uverbs_dev->cdev.ops = device->mmap ? &uverbs_mmap_fops : &uverbs_fops;
-	cdev_set_parent(&uverbs_dev->cdev, &uverbs_dev->kobj);
-	kobject_set_name(&uverbs_dev->cdev.kobj, "uverbs%d", uverbs_dev->devnum);
-	if (cdev_add(&uverbs_dev->cdev, base, 1))
-		goto err_cdev;
 
-	uverbs_dev->dev = device_create(uverbs_class, device->dev.parent,
-					uverbs_dev->cdev.dev, uverbs_dev,
-					"uverbs%d", uverbs_dev->devnum);
-	if (IS_ERR(uverbs_dev->dev))
+	ret = cdev_device_add(&uverbs_dev->cdev, &uverbs_dev->dev);
+	if (ret)
 		goto err_cdev;
 
-	if (device_create_file(uverbs_dev->dev, &dev_attr_ibdev))
-		goto err_class;
-	if (device_create_file(uverbs_dev->dev, &dev_attr_abi_version))
-		goto err_class;
+	if (device_create_file(&uverbs_dev->dev, &dev_attr_ibdev))
+		goto err_file;
+	if (device_create_file(&uverbs_dev->dev, &dev_attr_abi_version))
+		goto err_file;
 
 	ib_set_client_data(device, &uverbs_client, uverbs_dev);
 
 	return;
 
-err_class:
-	device_destroy(uverbs_class, uverbs_dev->cdev.dev);
+err_file:
+	cdev_device_del(&uverbs_dev->cdev, &uverbs_dev->dev);
 err_cdev:
 	cdev_del(&uverbs_dev->cdev);
+	put_device(&uverbs_dev->dev);
 err_uapi:
 	clear_bit(devnum, dev_map);
 err:
 	if (atomic_dec_and_test(&uverbs_dev->refcount))
 		ib_uverbs_comp_dev(uverbs_dev);
 	wait_for_completion(&uverbs_dev->comp);
-	kobject_put(&uverbs_dev->kobj);
 	return;
 }
 
@@ -1155,9 +1149,7 @@ static void ib_uverbs_remove_one(struct ib_device *device, void *client_data)
 	if (!uverbs_dev)
 		return;
 
-	dev_set_drvdata(uverbs_dev->dev, NULL);
-	device_destroy(uverbs_class, uverbs_dev->cdev.dev);
-	cdev_del(&uverbs_dev->cdev);
+	cdev_device_del(&uverbs_dev->cdev, &uverbs_dev->dev);
 	clear_bit(uverbs_dev->devnum, dev_map);
 
 	if (device->disassociate_ucontext) {
@@ -1181,7 +1173,7 @@ static void ib_uverbs_remove_one(struct ib_device *device, void *client_data)
 	if (wait_clients)
 		wait_for_completion(&uverbs_dev->comp);
 
-	kobject_put(&uverbs_dev->kobj);
+	put_device(&uverbs_dev->dev);
 }
 
 static char *uverbs_devnode(struct device *dev, umode_t *mode)