linux-kernel - Re: [PATCH 16/21] perf/cxlpmu: Replace IRQF_ONESHOT with IRQF_NO

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Message-ID: <20260123120517.00000d58@huawei.com>
Date: Fri, 23 Jan 2026 12:05:17 +0000
From: Jonathan Cameron <jonathan.cameron@...wei.com>
To: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
CC: <linux-kernel@...r.kernel.org>, <linux-rt-devel@...ts.linux.dev>, "Thomas
 Gleixner" <tglx@...nel.org>, Will Deacon <will@...nel.org>, Mark Rutland
	<mark.rutland@....com>, <linux-cxl@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 16/21] perf/cxlpmu: Replace IRQF_ONESHOT with
 IRQF_NO_THREAD

On Fri, 23 Jan 2026 12:37:02 +0100
Sebastian Andrzej Siewior <bigeasy@...utronix.de> wrote:

> Passing IRQF_ONESHOT ensures that the interrupt source is masked until
> the secondary (threaded) handler is done. If only a primary handler is
> used then the flag makes no sense because the interrupt can not fire
> (again) while its handler is running.
> The flag also disallows force-threading of the primary handler and the
> irq-core will warn about this.
> 
> The intention here was probably not allowing forced-threading.
> 
> Replace IRQF_ONESHOT with IRQF_NO_THREAD.
> 
I don't think we are that likely to see force-threading on CXL
systems (I could be wrong!), but still good to correct this.

Reviewed-by: Jonathan Cameron <jonathan.cameron@...wei.com>

> Cc: Jonathan Cameron <jonathan.cameron@...wei.com>
> Cc: Will Deacon <will@...nel.org>
> Cc: Mark Rutland <mark.rutland@....com>
> Cc: linux-cxl@...r.kernel.org
> Cc: linux-arm-kernel@...ts.infradead.org
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
> ---
>  drivers/perf/cxl_pmu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/perf/cxl_pmu.c b/drivers/perf/cxl_pmu.c
> index d094030220bf2..68a54d97d2a8a 100644
> --- a/drivers/perf/cxl_pmu.c
> +++ b/drivers/perf/cxl_pmu.c
> @@ -877,7 +877,7 @@ static int cxl_pmu_probe(struct device *dev)
>  	if (!irq_name)
>  		return -ENOMEM;
>  
> -	rc = devm_request_irq(dev, irq, cxl_pmu_irq, IRQF_SHARED | IRQF_ONESHOT,
> +	rc = devm_request_irq(dev, irq, cxl_pmu_irq, IRQF_SHARED | IRQF_NO_THREAD,
>  			      irq_name, info);
>  	if (rc)
>  		return rc;