Re: [PATCH] tty:n_gsm.c: destroy port by tty_port_destroy()

[Xiaoming Ni]

On 2019/10/31 18:11, Jiri Slaby wrote:
> On 24. 09. 19, 11:25, Xiaoming Ni wrote:
> > According to the comment of tty_port_destroy():
> >      When a port was initialized using tty_port_init, one has to destroy
> >      the port by tty_port_destroy();
>
> It continues with a part saying:
>     Either indirectly by using tty_port refcounting
>     (tty_port_put) or directly if refcounting is not used.
>
> > tty_port_init() is called in gsm_dlci_alloc()
> > so tty_port_destroy() needs to be called in gsm_dlci_free()
> >
> > Signed-off-by: Xiaoming Ni <nixiaoming@xxxxxxxxxx>
> > ---
> >   drivers/tty/n_gsm.c | 1 +
> >   1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
> > index 36a3eb4..3f5bcc9 100644
> > --- a/drivers/tty/n_gsm.c
> > +++ b/drivers/tty/n_gsm.c
> > @@ -1681,6 +1681,7 @@ static void gsm_dlci_free(struct tty_port *port)
> >   
> >   	del_timer_sync(&dlci->t1);
> >   	dlci->gsm->dlci[dlci->addr] = NULL;
> > +	tty_port_destroy(&dlci->port);
>
> This is wrong. gsm_dlci_free is tty_port_operations->destruct, i.e.
> n_gsm uses tty_port refcounting and tty_port_destroy was called on this
> port in tty_port_destructor already.
>
> Greg, please revert.
>
> thanks,

Function call flow
tty_port_put
    ===>  tty_port_destructor
         ===> tty_port_destroy
              Port->ops->destruct(port);
               ===> .destruct = gsm_dlci_free

Thank you for your correction, I am wrong.

thanks