Re: [Intel-gfx] [PATCH v9 09/10] vfio/pci: Copy hot-reset device info to userspace in the devices loop

[Jason Gunthorpe <jgg@nvidia.com>]

On Mon, Jul 10, 2023 at 07:31:25PM -0700, Yi Liu wrote:

> @@ -1311,29 +1296,17 @@ static int vfio_pci_ioctl_get_pci_hot_reset_info(
>  	ret = vfio_pci_for_each_slot_or_bus(vdev->pdev, vfio_pci_fill_devs,
>  					    &fill, slot);
>  	mutex_unlock(&vdev->vdev.dev_set->lock);
> +	if (ret)
> +		return ret;
>  
> -	/*
> -	 * If a device was removed between counting and filling, we may come up
> -	 * short of fill.max.  If a device was added, we'll have a return of
> -	 * -EAGAIN above.
> -	 */
> -	if (!ret) {
> -		hdr.count = fill.cur;
> -		hdr.flags = fill.flags;
> -	}
> -
> -reset_info_exit:
> +	hdr.count = fill.count;
> +	hdr.flags = fill.flags;
>  	if (copy_to_user(arg, &hdr, minsz))
> -		ret = -EFAULT;
> -
> -	if (!ret) {
> -		if (copy_to_user(&arg->devices, devices,
> -				 hdr.count * sizeof(*devices)))
> -			ret = -EFAULT;
> -	}
> +		return -EFAULT;
>  
> -	kfree(devices);
> -	return ret;
> +	if (fill.count != fill.devices - arg->devices)
> +		return -ENOSPC;

This should be > right? The previous code returned ENOSPC only if
their were more devices than requested, not less.

Jason