Re: [PATCH] Fix serial_match_port() for dynamic major tty-device numbers

[Andrew Morton <akpm@linux-foundation.org>]

On Sun, 22 Jun 2008 00:45:25 +0200 (CEST)
Guennadi Liakhovetski <g.liakhovetski@gmx.de> wrote:

> As reported by Vipul Gandhi, the current serial_match_port() doesn't work 
> for tty-devices using dynamic major number allocation. Fix it.
> 
> Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
> Tested-by: Vipul Gandhi <vcgandhi1@aol.com>
> 
> ---
> 
> diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
> index 0f5a179..593ae85 100644
> --- a/drivers/serial/serial_core.c
> +++ b/drivers/serial/serial_core.c
> @@ -1949,7 +1949,9 @@ struct uart_match {
>  static int serial_match_port(struct device *dev, void *data)
>  {
>  	struct uart_match *match = data;
> -	dev_t devt = MKDEV(match->driver->major, match->driver->minor) + match->port->line;
> +	struct tty_driver *tty_drv = match->driver->tty_driver;
> +	dev_t devt = MKDEV(tty_drv->major, tty_drv->minor_start) +
> +		match->port->line;
>  
>  	return dev->devt == devt; /* Actually, only one tty per port */

Well that sounds bad.  We need to work out whether this fix is needed
in 2.6.25 and possibly eariler.

What are the consequences of this error?