Re: [PATCH v4 43/47] vfio: convert vfio_group_ioctl_get_device_fd() to FD_PREPARE()

[Jason Gunthorpe <jgg@ziepe.ca>]

On Sun, Nov 23, 2025 at 05:34:01PM +0100, Christian Brauner wrote:
> Signed-off-by: Christian Brauner <brauner@kernel.org>
> ---
>  drivers/vfio/group.c | 28 +++++-----------------------
>  1 file changed, 5 insertions(+), 23 deletions(-)
> 
> diff --git a/drivers/vfio/group.c b/drivers/vfio/group.c
> index c376a6279de0..d47ffada6912 100644
> --- a/drivers/vfio/group.c
> +++ b/drivers/vfio/group.c
> @@ -299,10 +299,8 @@ static int vfio_group_ioctl_get_device_fd(struct vfio_group *group,
>  					  char __user *arg)
>  {
>  	struct vfio_device *device;
> -	struct file *filep;
>  	char *buf;
> -	int fdno;
> -	int ret;
> +	int fd;
>  
>  	buf = strndup_user(arg, PAGE_SIZE);
>  	if (IS_ERR(buf))
> @@ -313,26 +311,10 @@ static int vfio_group_ioctl_get_device_fd(struct vfio_group *group,
>  	if (IS_ERR(device))
>  		return PTR_ERR(device);
>  
> -	fdno = get_unused_fd_flags(O_CLOEXEC);
> -	if (fdno < 0) {
> -		ret = fdno;
> -		goto err_put_device;
> -	}
> -
> -	filep = vfio_device_open_file(device);
> -	if (IS_ERR(filep)) {
> -		ret = PTR_ERR(filep);
> -		goto err_put_fdno;
> -	}
> -
> -	fd_install(fdno, filep);
> -	return fdno;
> -
> -err_put_fdno:
> -	put_unused_fd(fdno);
> -err_put_device:
> -	vfio_device_put_registration(device);
> -	return ret;
> +	fd = FD_ADD(O_CLOEXEC, vfio_device_open_file(device));
> +	if (fd < 0)
> +		vfio_device_put_registration(device);
> +	return fd;
>  }

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Tough I'd bikeshed this name and suggest something with INSTALL in the
macro as we've always used install to mean the FD is visible to
userspace and is the barrier where we have to start to be careful.

Jason