linux-kernel - Re: [PATCH 2/2] USB: serial: ark3116.c: Move TIOCGSERIAL ioctl case to function.

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Date:   Tue, 2 Jan 2018 16:00:02 +0100
From:   Johan Hovold <johan@...nel.org>
To:     Mikhail Zaytsev <flashed@...l.ru>
Cc:     Johan Hovold <johan@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] USB: serial: ark3116.c: Move TIOCGSERIAL ioctl case
 to function.

On Wed, Dec 13, 2017 at 04:45:06PM +0300, Mikhail Zaytsev wrote:
> The patch moves TIOCGSERIAL ioctl case to get_serial_info function.
> 
> Signed-off-by: Mikhail Zaytsev <flashed@...l.ru>
> ---
>  drivers/usb/serial/ark3116.c | 35 +++++++++++++++++++++--------------
>  1 file changed, 21 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/usb/serial/ark3116.c b/drivers/usb/serial/ark3116.c
> index 2e957c76f..2ce8fe10e 100644
> --- a/drivers/usb/serial/ark3116.c
> +++ b/drivers/usb/serial/ark3116.c
> @@ -36,6 +36,7 @@
>  #define DRIVER_DESC "USB ARK3116 serial/IrDA driver"
>  #define DRIVER_DEV_DESC "ARK3116 RS232/IrDA"
>  #define DRIVER_NAME "ark3116"
> +#define ARK3116_BAUDRATE 460800

I thought you and Oliver agreed this wasn't needed (wanted). Just
hard-code this number in the new helper as before.

>  /* usb timeout of 1 second */
>  #define ARK_TIMEOUT 1000
> @@ -397,27 +398,33 @@ static int ark3116_open(struct tty_struct *tty, struct usb_serial_port *port)
>  	return result;
>  }
>  
> +static int ark3116_get_serial_info(struct usb_serial_port *port,
> +			unsigned long arg)

Keep the (void __user *) cast in ark3116_ioctl below and pass a struct
serial_struct __user pointer here.

> +{
> +	struct serial_struct ser;
> +
> +	memset(&ser, 0, sizeof(ser));
> +
> +	ser.type = PORT_16654;
> +	ser.line = port->minor;
> +	ser.port = port->port_number;
> +	ser.custom_divisor = 0;

Might as well drop this redundant assignment as well.

> +	ser.baud_base = ARK3116_BAUDRATE;
> +
> +	if (copy_to_user((void __user *)arg, &ser, sizeof(ser)))
> +		return -EFAULT;
> +
> +	return 0;
> +}
> +
>  static int ark3116_ioctl(struct tty_struct *tty,
>  			 unsigned int cmd, unsigned long arg)
>  {
>  	struct usb_serial_port *port = tty->driver_data;
> -	struct serial_struct serstruct;
> -	void __user *user_arg = (void __user *)arg;
>  
>  	switch (cmd) {
>  	case TIOCGSERIAL:
> -		/* XXX: Some of these values are probably wrong. */
> -		memset(&serstruct, 0, sizeof(serstruct));
> -		serstruct.type = PORT_16654;
> -		serstruct.line = port->minor;
> -		serstruct.port = port->port_number;
> -		serstruct.custom_divisor = 0;
> -		serstruct.baud_base = 460800;
> -
> -		if (copy_to_user(user_arg, &serstruct, sizeof(serstruct)))
> -			return -EFAULT;
> -
> -		return 0;
> +		return ark3116_get_serial_info(port, arg);
>  	default:
>  		break;
>  	}

Thanks,
Johan