Re: [RFC v1 7/8] mshv: implement in-kernel device framework

[Matthew Wilcox]

On Fri, Jul 09, 2021 at 11:43:38AM +0000, Wei Liu wrote:
> +static long
> +mshv_partition_ioctl_create_device(struct mshv_partition *partition,
> +	void __user *user_args)
> +{
[...]
> +	mshv_partition_get(partition);
> +	r = anon_inode_getfd(ops->name, &mshv_device_fops, dev, O_RDWR | O_CLOEXEC);
> +	if (r < 0) {
> +		mshv_partition_put_no_destroy(partition);
> +		list_del(&dev->partition_node);
> +		ops->destroy(dev);
> +		goto out;
> +	}
> +
> +	cd->fd = r;
> +	r = 0;

Why return the fd in memory instead of returning the fd as the return
value from the ioctl?

> +	if (copy_to_user(user_args, &tmp, sizeof(tmp))) {
> +		r = -EFAULT;
> +		goto out;
> +	}

... this could then disappear.