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

- From: Matthew Wilcox \<willy@infradead.org\>
- Date: 2021-07-09 15:33:01 
- List: virtualization
- Page: https://ratatoskr.run/virtualization/2021/07/1437445
- Thread: https://ratatoskr.run/linux-hyperv/2021/07/1437169/t.md

```text
On Fri, Jul 09, 2021 at 01:50:13PM +0000, Wei Liu wrote:
> On Fri, Jul 09, 2021 at 02:02:04PM +0100, Matthew Wilcox wrote:
> > 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.
> 
> Thanks for your comment, Matthew.
> 
> This is intentionally because I didn't want to deviate from KVM's API.
> The fewer differences the better.

Then don't define your own structure.  Use theirs.
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