linux-kernel - Re: [PATCH 2/7] can: m_can: m_can_rx_handler(): only handle active interrupts

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Message-Id: <DC69H7OUANQR.ZVMFRCS8UF4D@baylibre.com>
Date: Tue, 19 Aug 2025 10:29:09 +0200
From: "Markus Schneider-Pargmann" <msp@...libre.com>
To: "Marc Kleine-Budde" <mkl@...gutronix.de>, "Chandrasekar Ramakrishnan"
 <rcsekar@...sung.com>, "Vincent Mailhol" <mailhol.vincent@...adoo.fr>,
 "Patrik Flykt" <patrik.flykt@...ux.intel.com>, "Dong Aisheng"
 <b29396@...escale.com>, "Fengguang Wu" <fengguang.wu@...el.com>, "Varka
 Bhadram" <varkabhadram@...il.com>, "Wu Bo" <wubo.oduw@...il.com>, "Philipp
 Zabel" <p.zabel@...gutronix.de>
Cc: <linux-can@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
 <kernel@...gutronix.de>
Subject: Re: [PATCH 2/7] can: m_can: m_can_rx_handler(): only handle active
 interrupts

On Tue Aug 12, 2025 at 7:36 PM CEST, Marc Kleine-Budde wrote:
> Among other things, the M_CAN IP core has an Interrupt Register (IR)
> and an Interrupt Enable (IE) register. An interrupt is triggered if at
> least 1 bit is set in the bitwise and of IR and IE.
>
> Depending on the configuration not all interrupts are enabled in the
> IE register. However the m_can_rx_handler() IRQ handler looks at all
> interrupts not just the enabled ones. This may lead to handling of not
> activated interrupts.

But isn't that happening for m_can_interrupt_handler() in general then?

Best
Markus

>
> Fix the problem and mask the irqstatus (IR register) with the
> active_interrupts (cache value of IE register).
>
> Fixes: e0d1f4816f2a ("can: m_can: add Bosch M_CAN controller support")
> Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
> ---
>  drivers/net/can/m_can/m_can.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
> index fe74dbd2c966..a51dc0bb8124 100644
> --- a/drivers/net/can/m_can/m_can.c
> +++ b/drivers/net/can/m_can/m_can.c
> @@ -1006,6 +1006,7 @@ static int m_can_rx_handler(struct net_device *dev, int quota, u32 irqstatus)
>  	int rx_work_or_err;
>  	int work_done = 0;
>  
> +	irqstatus &= cdev->active_interrupts;
>  	if (!irqstatus)
>  		goto end;
>  


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