linux-kernel - Re: [PATCH 1/2] gpio: em: remove the gpiochip before removing the irq domain

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Message-ID: <CAMuHMdUB7fU1grp7jgrFWad183RLcRE7CDNQYczgm_Ur-Nu_9g@mail.gmail.com>
Date:   Wed, 10 Jul 2019 12:13:04 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Phil Reid <preid@...ctromag.com.au>
Cc:     Bartosz Golaszewski <brgl@...ev.pl>,
        Linus Walleij <linus.walleij@...aro.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        stable <stable@...r.kernel.org>
Subject: Re: [PATCH 1/2] gpio: em: remove the gpiochip before removing the irq domain

Hi Phil,

On Wed, Jul 10, 2019 at 11:37 AM Phil Reid <preid@...ctromag.com.au> wrote:
> On 10/07/2019 17:08, Bartosz Golaszewski wrote:
> > From: Bartosz Golaszewski <bgolaszewski@...libre.com>
> >
> > In commit 8764c4ca5049 ("gpio: em: use the managed version of
> > gpiochip_add_data()") we implicitly altered the ordering of resource
> > freeing: since gpiochip_remove() calls gpiochip_irqchip_remove()
> > internally, we now can potentially use the irq_domain after it was
> > destroyed in the remove() callback (as devm resources are freed after
> > remove() has returned).
> >
> > Use devm_add_action() to keep the ordering right and entirely kill
> > the remove() callback in the driver.
> >
> > Reported-by: Geert Uytterhoeven <geert@...ux-m68k.org>
> > Fixes: 8764c4ca5049 ("gpio: em: use the managed version of gpiochip_add_data()")
> > Cc: stable@...r.kernel.org
> > Signed-off-by: Bartosz Golaszewski <bgolaszewski@...libre.com>

> > --- a/drivers/gpio/gpio-em.c
> > +++ b/drivers/gpio/gpio-em.c

> > @@ -333,39 +340,32 @@ static int em_gio_probe(struct platform_device *pdev)
> >               return -ENXIO;
> >       }
> >
> > +     ret = devm_add_action(&pdev->dev,
> > +                           em_gio_irq_domain_remove, p->irq_domain);
>
> Could devm_add_action_or_reset be used?

Thank you very much for bringing this function to my attention!
I was just wondering if devm_add_action() should call the action on
failure, as this is what most callers seem to do anyway.

>
> > +     if (ret) {
> > +             irq_domain_remove(p->irq_domain);
> > +             return ret;
> > +     }

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds