scsi: bsg: Fix device unregistration

device_initialize() is used to take a refcount on the device. However,
put_device() is not called during device teardown. This leads to a
leak of private data of the driver core, dev_name(), etc. This is
reported by kmemleak at boot time if we compile kernel with
DEBUG_TEST_DRIVER_REMOVE.

Fix memory leaks during unregistration and implement a release
function.

Link: https://lore.kernel.org/r/20210911105306.1511-1-yuzenghui@huawei.com
Fixes: ead09dd3 ("scsi: bsg: Simplify device registration")
Reviewed-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

block/bsg.c

@@ -165,13 +165,20 @@ static const struct file_operations bsg_fops = {
 	.llseek		=	default_llseek,
 };
 
+static void bsg_device_release(struct device *dev)
+{
+	struct bsg_device *bd = container_of(dev, struct bsg_device, device);
+
+	ida_simple_remove(&bsg_minor_ida, MINOR(bd->device.devt));
+	kfree(bd);
+}
+
 void bsg_unregister_queue(struct bsg_device *bd)
 {
 	if (bd->queue->kobj.sd)
 		sysfs_remove_link(&bd->queue->kobj, "bsg");
 	cdev_device_del(&bd->cdev, &bd->device);
-	ida_simple_remove(&bsg_minor_ida, MINOR(bd->device.devt));
-	kfree(bd);
+	put_device(&bd->device);
 }
 EXPORT_SYMBOL_GPL(bsg_unregister_queue);
 
@@ -193,11 +200,13 @@ struct bsg_device *bsg_register_queue(struct request_queue *q,
 	if (ret < 0) {
 		if (ret == -ENOSPC)
 			dev_err(parent, "bsg: too many bsg devices\n");
-		goto out_kfree;
+		kfree(bd);
+		return ERR_PTR(ret);
 	}
 	bd->device.devt = MKDEV(bsg_major, ret);
 	bd->device.class = bsg_class;
 	bd->device.parent = parent;
+	bd->device.release = bsg_device_release;
 	dev_set_name(&bd->device, "%s", name);
 	device_initialize(&bd->device);
 
@@ -205,7 +214,7 @@ struct bsg_device *bsg_register_queue(struct request_queue *q,
 	bd->cdev.owner = THIS_MODULE;
 	ret = cdev_device_add(&bd->cdev, &bd->device);
 	if (ret)
-		goto out_ida_remove;
+		goto out_put_device;
 
 	if (q->kobj.sd) {
 		ret = sysfs_create_link(&q->kobj, &bd->device.kobj, "bsg");
@@ -217,10 +226,8 @@ struct bsg_device *bsg_register_queue(struct request_queue *q,
 
 out_device_del:
 	cdev_device_del(&bd->cdev, &bd->device);
-out_ida_remove:
-	ida_simple_remove(&bsg_minor_ida, MINOR(bd->device.devt));
-out_kfree:
-	kfree(bd);
+out_put_device:
+	put_device(&bd->device);
 	return ERR_PTR(ret);
 }
 EXPORT_SYMBOL_GPL(bsg_register_queue);