linux-kernel - Re: [PATCH] tty:n_gsm.c: destroy port by tty_port

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Message-ID: <20191104164919.GA2282079@kroah.com>
Date:   Mon, 4 Nov 2019 17:49:19 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Jiri Slaby <jslaby@...e.com>
Cc:     Xiaoming Ni <nixiaoming@...wei.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tty:n_gsm.c: destroy port by tty_port_destroy()

On Thu, Oct 31, 2019 at 11:11:24AM +0100, 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@...wei.com>
> > ---
> >  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.

Now reverted.

sorry about that.

greg k-h