linux-kernel - Re: [PATCH] soc: fsl: qe: qe_ports_ic: Consolidate chained IRQ handler install/remove

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Message-ID: <3860577c-2cef-4e10-9cc1-33246d261a8b@kernel.org>
Date: Mon, 19 Jan 2026 08:00:01 +0100
From: "Christophe Leroy (CS GROUP)" <chleroy@...nel.org>
To: Chen Ni <nichen@...as.ac.cn>, qiang.zhao@....com
Cc: linuxppc-dev@...ts.ozlabs.org, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] soc: fsl: qe: qe_ports_ic: Consolidate chained IRQ
 handler install/remove



Le 19/01/2026 à 06:57, Chen Ni a écrit :
> [Vous ne recevez pas souvent de courriers de nichen@...as.ac.cn. Découvrez pourquoi ceci est important à https://aka.ms/LearnAboutSenderIdentification ]
> 
> The driver currently sets the handler data and the chained handler in
> two separate steps. This creates a theoretical race window where an
> interrupt could fire after the handler is set but before the data is
> assigned, leading to a NULL pointer dereference.

I don't understand what you mean, how can this happen ?

irq_set_handler_data() is called _before_ irq_set_chained_handler(), so 
how could an interrupt fire _before_ the data is assigned ?

> 
> Replace the two calls with irq_set_chained_handler_and_data() to set
> both the handler and its data atomically under the irq_desc->lock.
> 
> Signed-off-by: Chen Ni <nichen@...as.ac.cn>
> ---
>   drivers/soc/fsl/qe/qe_ports_ic.c | 3 +--
>   1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/soc/fsl/qe/qe_ports_ic.c b/drivers/soc/fsl/qe/qe_ports_ic.c
> index 61dd09fec6f6..8e2107e2cde5 100644
> --- a/drivers/soc/fsl/qe/qe_ports_ic.c
> +++ b/drivers/soc/fsl/qe/qe_ports_ic.c
> @@ -114,8 +114,7 @@ static int qepic_probe(struct platform_device *pdev)
>          if (!data->host)
>                  return -ENODEV;
> 
> -       irq_set_handler_data(irq, data);
> -       irq_set_chained_handler(irq, qepic_cascade);
> +       irq_set_chained_handler_and_data(irq, qepic_cascade, data);
> 
>          return 0;
>   }
> --
> 2.25.1
>