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SubjectRe: [PATCH] usb/serial: Add compat_ioctl pass-through
On Fri, 28 Nov 2008 14:28:02 -0800
Keith Packard <keithp@keithp.com> wrote:

> USB serial devices with extended IOCTLs cannot be used in a 64-bit kernel
> from 32-bit user space as the compat_ioctl path is missing. This adds a
> pass-through so that drivers may offer this functionality. This requires
> that all drivers actually implement a compat_ioctl function if they want to
> support this operation.
>
> Signed-off-by: Keith Packard <keithp@keithp.com>

Would be far better to keep compatible ioctls anyway however that aside
clearly it should be passed on.

> +static int serial_compat_ioctl(struct tty_struct *tty, struct file *file,
> + unsigned int cmd, unsigned long arg)
> +{
> + struct usb_serial_port *port = tty->driver_data;
> + int retval = -ENODEV;

Can never be used only overwritten so why not replace with -ENOIOCTLCMD
and remove the else of the if

Also I get a CodingStyle whine about the port->serial-> side of the if
not needing { }

> + /* Called with bkl held */
> int (*ioctl)(struct tty_struct *tty, struct file *file,
> unsigned int cmd, unsigned long arg);

No... the ioctl path for tty comes from unlocked_ioctl so the BKL is not
held and should not be held.

Alan


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