Re: [PATCH] pinctrl: renesas: rzg2l: Execute atomically the interrupt configuration

[Geert Uytterhoeven <geert@linux-m68k.org>]

Hi Claudiu,

Thanks for your patch!

On Thu, Mar 7, 2024 at 12:25 PM Claudiu <claudiu.beznea@tuxon.dev> wrote:
> From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
>
> Lockdep detects a possible deadlock as listed below. This is because it
> detects the IA55 interrupt controller .irq_eoi() API is called from
> interrupt context while configuration-specific API (e.g., .irq_enable())
> could be called from process context on resume path (by calling
> rzg2l_gpio_irq_restore()). To avoid this, protect the call of
> rzg2l_gpio_irq_enable() with spin_lock_irqsave()/spin_unlock_irqrestore().
> With this the same approach that is available in __setup_irq() is mimicked
> to pinctrl IRQ resume function.

You mean __setup_irq() in kernel/irq/manage.c?
That one uses the raw spinlock methods?

> --- a/drivers/pinctrl/renesas/pinctrl-rzg2l.c
> +++ b/drivers/pinctrl/renesas/pinctrl-rzg2l.c
> @@ -2063,8 +2063,17 @@ static void rzg2l_gpio_irq_restore(struct rzg2l_pinctrl *pctrl)
>                         continue;
>                 }
>
> -               if (!irqd_irq_disabled(data))
> +               if (!irqd_irq_disabled(data)) {
> +                       unsigned long flags;
> +
> +                       /*
> +                        * This has to be atomically executed to protect against a concurrent
> +                        * interrupt.
> +                        */
> +                       spin_lock_irqsave(&pctrl->lock, flags);
>                         rzg2l_gpio_irq_enable(data);
> +                       spin_unlock_irqrestore(&pctrl->lock, flags);
> +               }
>         }
>  }

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-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