linux-kernel - Re: [PATCH] irqchip/sifive-plic: Respect mask state when setting affinity

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Message-ID: <87fre3mhkh.fsf@yellow.woof>
Date: Thu, 07 Aug 2025 14:39:42 +0200
From: Nam Cao <namcao@...utronix.de>
To: Inochi Amaoto <inochiama@...il.com>, Thomas Gleixner
 <tglx@...utronix.de>, Paul Walmsley <paul.walmsley@...ive.com>, Samuel
 Holland <samuel.holland@...ive.com>
Cc: Inochi Amaoto <inochiama@...il.com>, linux-kernel@...r.kernel.org,
 linux-riscv@...ts.infradead.org, Yixun Lan <dlan@...too.org>, Longbin Li
 <looong.bin@...il.com>
Subject: Re: [PATCH] irqchip/sifive-plic: Respect mask state when setting
 affinity

Inochi Amaoto <inochiama@...il.com> writes:

> The plic_set_affinity always call plic_irq_enable(), which clears up
> the priority setting even the irq is only masked. This make the irq
> unmasked unexpectly.
>
> Replace the plic_irq_enable/disable() with plic_irq_toggle() to
> avoid changing priority setting.
>
> Suggested-by: Thomas Gleixner <tglx@...utronix.de>
> Signed-off-by: Inochi Amaoto <inochiama@...il.com>
> ---
>  drivers/irqchip/irq-sifive-plic.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c
> index bf69a4802b71..5bf5050996da 100644
> --- a/drivers/irqchip/irq-sifive-plic.c
> +++ b/drivers/irqchip/irq-sifive-plic.c
> @@ -148,6 +148,7 @@ static void plic_irq_enable(struct irq_data *d)
>  
>  static void plic_irq_disable(struct irq_data *d)
>  {
> +	plic_irq_mask(d);
>  	plic_irq_toggle(irq_data_get_effective_affinity_mask(d), d, 0);
>  }

This part is not required for the problem you are addressing, right?

I do not oppose the change, I'm just curious if I miss something here.

>  
> @@ -179,12 +180,14 @@ static int plic_set_affinity(struct irq_data *d,
>  	if (cpu >= nr_cpu_ids)
>  		return -EINVAL;
>  
> -	plic_irq_disable(d);
> +	/* Invalidate the original routing entry */
> +	plic_irq_toggle(irq_data_get_effective_affinity_mask(d), d, 0);
>  
>  	irq_data_update_effective_affinity(d, cpumask_of(cpu));
>  
> +	/* Setting the new routing entry if irq is enabled */
>  	if (!irqd_irq_disabled(d))
> -		plic_irq_enable(d);
> +		plic_irq_toggle(irq_data_get_effective_affinity_mask(d), d, 1);
>  
>  	return IRQ_SET_MASK_OK_DONE;
>  }

This part makes sense:

Reviewed-by: Nam Cao <namcao@...utronix.de>
Tested-by: Nam Cao <namcao@...utronix.de> # VisionFive 2