linux-kernel - Re: [PATCH] genirq: Simplify the check for __irq_get_desc

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Date: Mon, 06 May 2024 19:55:04 +0200
From: Thomas Gleixner <tglx@...utronix.de>
To: Jinjie Ruan <ruanjinjie@...wei.com>, linux-kernel@...r.kernel.org
Cc: ruanjinjie@...wei.com
Subject: Re: [PATCH] genirq: Simplify the check for __irq_get_desc_lock()

On Mon, May 06 2024 at 20:50, Jinjie Ruan wrote:

> If it set "_IRQ_DESC_PERCPU" in "check" but the desc is not percpu, or if
> the desc is percpu but it not set "_IRQ_DESC_PERCPU" in "check", it both
> return NULL, so simplify the check in __irq_get_desc_lock() with "!=".

What is exactly simplified here?

> Signed-off-by: Jinjie Ruan <ruanjinjie@...wei.com>
> ---
>  kernel/irq/irqdesc.c | 6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
>
> diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
> index 88ac3652fcf2..6c52deb134b9 100644
> --- a/kernel/irq/irqdesc.c
> +++ b/kernel/irq/irqdesc.c
> @@ -882,11 +882,7 @@ __irq_get_desc_lock(unsigned int irq, unsigned long *flags, bool bus,
>  
>  	if (desc) {
>  		if (check & _IRQ_DESC_CHECK) {
> -			if ((check & _IRQ_DESC_PERCPU) &&
> -			    !irq_settings_is_per_cpu_devid(desc))
> -				return NULL;
> -
> -			if (!(check & _IRQ_DESC_PERCPU) &&
> +			if (!!(check & _IRQ_DESC_PERCPU) !=
>  			    irq_settings_is_per_cpu_devid(desc))
>  				return NULL;

The existing code is readable and obvious. This is not.

Thanks,

        tglx