Re: [PATCH] u_serial.c - Force destroy tty_port in gserial_free_port

Re: [PATCH] u_serial.c - Force destroy tty_port in gserial_free_port

[Felipe Balbi]

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Hi,

On Thu, Oct 09, 2014 at 11:23:59AM +1100, Andre Wolokita wrote:
> Issuing a modprobe -r g_serial command to the target
> over the gadget serial communications line causes
> modprobe to enter uninterruptable sleep, leaving the
> system in an unstable state.

does anybody know if this is a valid usecase ? I'd expect us to return
-EBUSY in such a case, no ? In any case, using g_serial to rmmod
g_serial is, from what I can tell, not supported.

Let's wait to hear from Alan Cox or somebody else.

> The associated tty_port.count won't drop to 0 because
> the command is issued over the very line being removed.
> 
> Destroying the tty_port will ensure that resources are
> freed and modprobe will not hang.
> 
> Signed-off-by: Andre Wolokita <Andre.Wolokita@analog.com>
> ---
>  drivers/usb/gadget/function/u_serial.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c
> index ad0aca8..db631c4 100644
> --- a/drivers/usb/gadget/function/u_serial.c
> +++ b/drivers/usb/gadget/function/u_serial.c
> @@ -1074,10 +1074,10 @@ static int gs_closed(struct gs_port *port)
>  static void gserial_free_port(struct gs_port *port)
>  {
>         tasklet_kill(&port->push);
> +       tty_port_destroy(&port->port);
>         /* wait for old opens to finish */
>         wait_event(port->port.close_wait, gs_closed(port));
>         WARN_ON(port->port_usb != NULL);
> -       tty_port_destroy(&port->port);
>         kfree(port);
>  }
> 
> -- 

-- 
balbi

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