linux-kernel - Re: [tip: irq/core] genirq: Warn about using IRQF

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Message-ID: <20260203083826.1gOzxrwt@linutronix.de>
Date: Tue, 3 Feb 2026 09:38:26 +0100
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: Bert Karwatzki <spasswolf@....de>
Cc: linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org,
	Jiri Kosina <jikos@...nel.org>, Jonathan Cameron <jic23@...nel.org>,
	Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
	Thomas Gleixner <tglx@...nel.org>,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>
Subject: Re: [tip: irq/core] genirq: Warn about using IRQF_ONESHOT without a
 threaded handler

On 2026-02-03 00:27:40 [+0100], Bert Karwatzki wrote:
> 
> The warning appears because iio_triggered_buffer_setup_ext() (in 
> drivers/iio/buffer/industrialio-triggered-buffer.c) is called with thread = NULL
> during the probe of the iio device and calls iio_alloc_pollfunc()
> (in drivers/iio/industrialio-trigger.c) with thread = NULL and type = IRQF_ONESHOT.
> 
> A simple fix could be this:
> 
> diff --git a/drivers/iio/buffer/industrialio-triggered-buffer.c b/drivers/iio/buffer/industrialio-triggered-buffer.c
> index 9bf75dee7ff8..40eea3a44724 100644
> --- a/drivers/iio/buffer/industrialio-triggered-buffer.c
> +++ b/drivers/iio/buffer/industrialio-triggered-buffer.c
> @@ -64,7 +64,7 @@ int iio_triggered_buffer_setup_ext(struct iio_dev *indio_dev,
>  
>         indio_dev->pollfunc = iio_alloc_pollfunc(h,
>                                                  thread,
> -                                                IRQF_ONESHOT,
> +                                                thread ? IRQF_ONESHOT : 0,
>                                                  indio_dev,
>                                                  "%s_consumer%d",
>                                                  indio_dev->name,
> 
> 
> Are there any problems with this?

Urgh. Haven't seen those.

Looking at all the users of of *iio_triggered_buffer_setup*() the
primary handler is either NULL or iio_pollfunc_store_time(). 
So IRQF_ONESHOST should work all the time.

Then there is 
- drivers/iio/adc/vf610_adc.c 
- drivers/iio/common/hid-sensors/hid-sensor-trigger.c

They use iio_pollfunc_store_time() as primary and have no secondary.
This would trigger the warning but not having a secondary handler while
returning IRQF_WAKE_THREAD should create a warning of its own.
What did I miss?

> Bert Karwatzki

Sebastian