linux-kernel - Re: [PATCH V1 1/5] irqchip/loongson-eiointc: Fix returned value on parsing MADT

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Message-ID: <87h6uagnzo.wl-maz@kernel.org>
Date:   Fri, 24 Mar 2023 15:36:43 +0000
From:   Marc Zyngier <maz@...nel.org>
To:     Jianmin Lv <lvjianmin@...ngson.cn>
Cc:     Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org,
        loongarch@...ts.linux.dev,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Jiaxun Yang <jiaxun.yang@...goat.com>,
        Huacai Chen <chenhuacai@...ngson.cn>,
        loongson-kernel@...ts.loongnix.cn
Subject: Re: [PATCH V1 1/5] irqchip/loongson-eiointc: Fix returned value on parsing MADT

On Fri, 24 Mar 2023 06:08:50 +0000,
Jianmin Lv <lvjianmin@...ngson.cn> wrote:
> 
> In pch_pic_parse_madt(), a NULL parent pointer will be
> returned from acpi_get_vec_parent() for second pch-pic domain
> related to second bridge while calling eiointc_acpi_init() at
> first time, where the parent of it has not been initialized
> yet, and will be initialized during second time calling
> eiointc_acpi_init(). So, it's reasonable to return zero so
> that failure of acpi_table_parse_madt() will be avoided, or else
> acpi_cascade_irqdomain_init() will return and initialization of
> followed pch_msi domain will be skipped.
> 
> Although it does not matter when pch_msi_parse_madt() returns
> -EINVAL if no invalid parent is found, it's also reasonable to
> return zero for that.
> 
> Change-Id: I4d278534999ec3e5c8db6d40155ba2665d9de86f
> Signed-off-by: Jianmin Lv <lvjianmin@...ngson.cn>
> ---
>  drivers/irqchip/irq-loongson-eiointc.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-loongson-eiointc.c b/drivers/irqchip/irq-loongson-eiointc.c
> index d15fd38c1756..62a632d73991 100644
> --- a/drivers/irqchip/irq-loongson-eiointc.c
> +++ b/drivers/irqchip/irq-loongson-eiointc.c
> @@ -343,7 +343,7 @@ static int __init pch_pic_parse_madt(union acpi_subtable_headers *header,
>  	if (parent)
>  		return pch_pic_acpi_init(parent, pchpic_entry);
>  
> -	return -EINVAL;
> +	return 0;

Why can't you detect this particular case instead of blindly
suppressing the error?

	M.

-- 
Without deviation from the norm, progress is not possible.