Re: [PATCH] USB: serial: suppress driver bind attributes

[Greg KH <greg@kroah.com>]

On Thu, Jan 16, 2020 at 05:07:05PM +0100, Johan Hovold wrote:
> USB-serial drivers must not be unbound from their ports before the
> corresponding USB driver is unbound from the parent interface so
> suppress the bind and unbind attributes.
> 
> Unbinding a serial driver while it's port is open is a sure way to
> trigger a crash as any driver state is released on unbind while port
> hangup is handled on the parent USB interface level. Drivers for
> multiport devices where ports share a resource such as an interrupt
> endpoint also generally cannot handle individual ports going away.
> 
> Cc: stable <stable@vger.kernel.org>
> Signed-off-by: Johan Hovold <johan@kernel.org>
> ---
>  drivers/usb/serial/usb-serial.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
> index 8f066bb55d7d..dc7a65b9ec98 100644
> --- a/drivers/usb/serial/usb-serial.c
> +++ b/drivers/usb/serial/usb-serial.c
> @@ -1317,6 +1317,9 @@ static int usb_serial_register(struct usb_serial_driver *driver)
>  		return -EINVAL;
>  	}
>  
> +	/* Prevent individual ports from being unbound. */
> +	driver->driver.suppress_bind_attrs = true;

We can still unbind the usb driver though, right?  If so, this is fine
with me.

thanks,

greg k-h