Re: [PATCH v5 1/4] uio: add ioctl support

[Greg KH <gregkh@linuxfoundation.org>]

On Tue, Oct 06, 2015 at 08:17:36PM +0300, Vlad Zolotarov wrote:
> Add the ability for underlying device drivers to register the ioctl
> commands. This is useful when some interaction with the user space
> beyond sysfs capabilities is required, e.g. query the interrupt mode
> or bind eventfd to interrupt notifications (similarly to vfio ioctl
> VFIO_DEVICE_SET_IRQS).
> 
> Signed-off-by: Vlad Zolotarov <vladz@cloudius-systems.com>
> ---
>  drivers/uio/uio.c          | 15 +++++++++++++++
>  include/linux/uio_driver.h |  3 +++
>  2 files changed, 18 insertions(+)
> 
> diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
> index 8196581..714b0e5 100644
> --- a/drivers/uio/uio.c
> +++ b/drivers/uio/uio.c
> @@ -704,6 +704,20 @@ static int uio_mmap(struct file *filep, struct vm_area_struct *vma)
>  	}
>  }
>  
> +static long uio_ioctl(struct file *filep, unsigned int cmd, unsigned long arg)
> +{
> +	struct uio_listener *listener = filep->private_data;
> +	struct uio_device *idev = listener->dev;
> +
> +	if (!idev->info)
> +		return -EIO;
> +
> +	if (!idev->info->ioctl)
> +		return -ENOTTY;
> +
> +	return idev->info->ioctl(idev->info, cmd, arg);
> +}

As Stephen said, I will not take this, sorry.  It opens up the ability
to add "new system calls" to a huge range of crappy drivers, it's
something that vendors have been trying to push for years and is
something that I will not allow.

greg k-h