linux-kernel - Re: [RFC PATCH] genirq: Provide generic_handle_domain_irq

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Date:   Mon, 16 May 2022 12:18:14 +0200
From:   Lukas Wunner <lukas@...ner.de>
To:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc:     linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Basavaraj Natikar <Basavaraj.Natikar@....com>,
        Hans de Goede <hdegoede@...hat.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Mark Gross <markgross@...nel.org>, Michael Buesch <m@...s.ch>,
        Rafa?? Mi??ecki <zajec5@...il.com>,
        Shyam Sundar S K <Shyam-sundar.S-k@....com>,
        linux-gpio@...r.kernel.org, linux-wireless@...r.kernel.org,
        platform-driver-x86@...r.kernel.org
Subject: Re: [RFC PATCH] genirq: Provide generic_handle_domain_irq_safe().

On Mon, May 09, 2022 at 04:04:08PM +0200, Sebastian Andrzej Siewior wrote:
> The problem with generic_handle_domain_irq() is that with `threadirqs'
> it will trigger "WARN_ON_ONCE(!in_hardirq())".

Now silenced by:
https://git.kernel.org/linus/792ea6a074ae


> +int generic_handle_domain_irq_safe(struct irq_domain *domain, unsigned int hwirq)
> +{
> +	unsigned long flags;
> +	int ret;
> +
> +	local_irq_save(flags);
> +	ret = handle_irq_desc(irq_resolve_mapping(domain, hwirq));
> +	local_irq_restore(flags);
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(generic_handle_domain_irq_safe);

AFAICS you don't need to disable hardirqs at least for the "threadirqs"
case because irq_forced_thread_fn() already does that.


>  drivers/bcma/driver_gpio.c                 |  2 +-
>  drivers/gpio/gpio-mlxbf2.c                 |  6 ++----
>  drivers/pinctrl/pinctrl-amd.c              |  2 +-
>  drivers/platform/x86/intel/int0002_vgpio.c |  3 +--
>  drivers/ssb/driver_gpio.c                  |  6 ++++--

>From a quick look, the proper solution for all of those drivers is
probably to just add IRQF_NO_THREAD and be done with it.

Thanks,

Lukas