RDMA/core: Use refcount_t instead of atomic_t on refcount of ib_uverbs_device

The refcount_t API will WARN on underflow and overflow of a reference
counter, and avoid use-after-free risks.

Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Weihang Li <[e-mail]>
Signed-off-by: Jason Gunthorpe <[e-mail]>

drivers/infiniband/core/uverbs.h

···
  */
 
 struct ib_uverbs_device {
-	atomic_t				refcount;
+	refcount_t				refcount;
 	u32					num_comp_vectors;
 	struct completion			comp;
 	struct device				dev;

drivers/infiniband/core/uverbs_main.c

···
 		module_put(ib_dev->ops.owner);
 	srcu_read_unlock(&file->device->disassociate_srcu, srcu_key);
 
-	if (atomic_dec_and_test(&file->device->refcount))
+	if (refcount_dec_and_test(&file->device->refcount))
 		ib_uverbs_comp_dev(file->device);
 
 	if (file->default_async_file)
···
 	int srcu_key;
 
 	dev = container_of(inode->i_cdev, struct ib_uverbs_device, cdev);
-	if (!atomic_inc_not_zero(&dev->refcount))
+	if (!refcount_inc_not_zero(&dev->refcount))
 		return -ENXIO;
 
 	get_device(&dev->dev);
···
 err:
 	mutex_unlock(&dev->lists_mutex);
 	srcu_read_unlock(&dev->disassociate_srcu, srcu_key);
-	if (atomic_dec_and_test(&dev->refcount))
+	if (refcount_dec_and_test(&dev->refcount))
 		ib_uverbs_comp_dev(dev);
 
 	put_device(&dev->dev);
···
 	uverbs_dev->dev.release = ib_uverbs_release_dev;
 	uverbs_dev->groups[0] = &dev_attr_group;
 	uverbs_dev->dev.groups = uverbs_dev->groups;
-	atomic_set(&uverbs_dev->refcount, 1);
+	refcount_set(&uverbs_dev->refcount, 1);
 	init_completion(&uverbs_dev->comp);
 	uverbs_dev->xrcd_tree = RB_ROOT;
 	mutex_init(&uverbs_dev->xrcd_tree_mutex);
···
 err_uapi:
 	ida_free(&uverbs_ida, devnum);
 err:
-	if (atomic_dec_and_test(&uverbs_dev->refcount))
+	if (refcount_dec_and_test(&uverbs_dev->refcount))
 		ib_uverbs_comp_dev(uverbs_dev);
 	wait_for_completion(&uverbs_dev->comp);
 	put_device(&uverbs_dev->dev);
···
 		wait_clients = 0;
 	}
 
-	if (atomic_dec_and_test(&uverbs_dev->refcount))
+	if (refcount_dec_and_test(&uverbs_dev->refcount))
 		ib_uverbs_comp_dev(uverbs_dev);
 	if (wait_clients)
 		wait_for_completion(&uverbs_dev->comp);