[PATCH] nvme: fix crash and memory leak during invalid cdev teardown

[Daniel Wagner]

>  static int nvme_add_ns_head_cdev(struct nvme_ns_head *head)
>  {
>  	int ret;
> +	char *name;
>  
>  	head->cdev_device.parent = &head->subsys->dev;
> -	ret = dev_set_name(&head->cdev_device, "ng%dn%d",
> -			   head->subsys->instance, head->instance);
> -	if (ret)
> -		return ret;
> -	ret = nvme_cdev_add(&head->cdev, &head->cdev_device,
> +	name = kasprintf(GFP_KERNEL, "ng%dn%d", head->subsys->instance,
> +			 head->instance);
> +	if (!name)
> +		return -ENOMEM;
> +
> +	ret = nvme_cdev_add(name, &head->cdev, &head->cdev_device,
>  			    &nvme_ns_head_chr_fops, THIS_MODULE);
> +	if (ret)
> +		dev_err(disk_to_dev(head->disk),
> +			"Unable to create the %s device", name);
> +	else
> +		set_bit(NVME_NSHEAD_CDEV_LIVE, &head->flags);
> +
> +	kfree(name);
>  	return ret;
>  }

nvme_add_ns_head_cdev returns the error code but nvme_mpath_set_live
handle the return code. So we either don't need to return the error code
or we should do something in nvme_mpath_set_live with it.