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Mon, 14 Sep 2026 08:25:23 -0700 (PDT) Sender: Guenter Roeck Date: Mon, 14 Sep 2026 08:25:23 -0700 From: Guenter Roeck To: Cong Nguyen Cc: Simon Guinot , linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] hwmon: (gpio-fan) return IRQ_HANDLED from the shared alarm IRQ handler Message-ID: <53810ee8-8b5c-41ed-8644-ba23fd69bb81@roeck-us.net> References: <20260914104136.1797979-1-congnt264@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260914104136.1797979-1-congnt264@gmail.com> On Mon, Sep 14, 2026 at 05:41:36PM +0700, Cong Nguyen wrote: > fan_alarm_irq_handler() always schedules alarm_work but returns IRQ_NONE, > so the kernel treats every alarm interrupt as unhandled. On a shared > line that risks the whole line being disabled as spurious. > > v1 just fixed that, but it was still IRQF_SHARED, and always returning > IRQ_HANDLED there defeats spurious-interrupt detection for the line -- > if the interrupt ever fires without a real event, nothing catches it, > and a fault could spin the CPU in the handler. > > Sashiko flagged this in v1, and Guenter confirmed: this interrupt must > not be shared. So v2 drops IRQF_SHARED too. > > Fixes: d6fe1360f42e ("hwmon: add generic GPIO fan driver") > Reported-by: Sashiko AI review > Link: https://lore.kernel.org/r/20260901160931.DD3811F00A3D@smtp.kernel.org > Assisted-by: Claude:claude-opus-4 > Signed-off-by: Cong Nguyen Applied. Thanks, Guenter