linux-kernel - Re: [PATCH v2] tty: nozomi: tty_unregister_device -> tty_port_unregister

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Date:   Wed, 21 Jul 2021 20:53:47 +0800
From:   Dongliang Mu <mudongliangabcd@...il.com>
To:     Johan Hovold <johan@...nel.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>, stable@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...e.de>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] tty: nozomi: tty_unregister_device -> tty_port_unregister_device

On Wed, Jul 21, 2021 at 8:01 PM Johan Hovold <johan@...nel.org> wrote:
>
> On Wed, Jul 21, 2021 at 07:33:04PM +0800, Dongliang Mu wrote:
> > The pairwise api invocation of tty_port_register_device should be
> > tty_port_unregister_device, other than tty_unregister_device.
>
> Are you sure about that? Please explain why you think this to be the
> case and why this change is needed.

I am sure about this.

1. From the implementation,
    tty_port_register_device -> tty_port_register_device_attr ->
tty_port_link_device; tty_register_device_attr
    tty_register_device -> tty_register_device_attr

    tty_port_unregister_device -> serdev_tty_port_unregister;
tty_unregister_device
    tty_unregister_device

    As to the functionability, tty_port_register_device pairs with
tty_port_unregister_device; meanwhile, the same to tty_register_device
and tty_unregister_device.

2. From the function naming style,

    tty_port_register_device - tty_port_unregister_device;
tty_register_device - tty_unregister_device

>
> > Fixes: a6afd9f3e819 ("tty: move a number of tty drivers from drivers/char/ to drivers/tty/")
>
> Please try a little harder, that's clearly not the commit that changed
> to the port registration helper.
>
> > Cc: stable@...r.kernel.org
>
> Why do you think this is stable material? (hint: it is not)

>From the documentation, this label could make the patch automatically
go to stable tree. And stable tree is also using the incorrect api.

If I have any misunderstanding, please let me know.

>
> > Signed-off-by: Dongliang Mu <mudongliangabcd@...il.com>
> > ---
> >  drivers/tty/nozomi.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/tty/nozomi.c b/drivers/tty/nozomi.c
> > index 0c80f25c8c3d..08bdd82f60b5 100644
> > --- a/drivers/tty/nozomi.c
> > +++ b/drivers/tty/nozomi.c
> > @@ -1417,7 +1417,8 @@ static int nozomi_card_init(struct pci_dev *pdev,
> >
> >  err_free_tty:
> >       for (i--; i >= 0; i--) {
> > -             tty_unregister_device(ntty_driver, dc->index_start + i);
> > +             tty_port_unregister_device(&dc->port[i].port, ntty_driver,
> > +                             dc->index_start + i);
> >               tty_port_destroy(&dc->port[i].port);
> >       }
> >       free_irq(pdev->irq, dc);
>
> Johan