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

From: Andrew Morton
Date: Tue Jun 24 2008 - 18:23:47 EST


On Sun, 22 Jun 2008 00:45:25 +0200 (CEST)
Guennadi Liakhovetski <g.liakhovetski@xxxxxx> 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@xxxxxx>
> Tested-by: Vipul Gandhi <vcgandhi1@xxxxxxx>
>
> ---
>
> 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?
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