linux-kernel - Re: [PATCH kernel v4 1/8] genirq/ipi: Simplify irq_reserve

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Date:   Tue, 24 Nov 2020 17:54:16 +0100
From:   Cédric Le Goater <clg@...d.org>
To:     Alexey Kardashevskiy <aik@...abs.ru>,
        <linux-kernel@...r.kernel.org>
CC:     Marc Zyngier <maz@...nel.org>, <x86@...nel.org>,
        <linux-gpio@...r.kernel.org>, Oliver O'Halloran <oohall@...il.com>,
        Frederic Barrat <fbarrat@...ux.ibm.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Michal Suchánek <msuchanek@...e.de>,
        <linuxppc-dev@...ts.ozlabs.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        Matt Redfearn <matt.redfearn@...s.com>,
        Qais Yousef <qsyousef@...il.com>, <linux-mips@...ux-mips.org>
Subject: Re: [PATCH kernel v4 1/8] genirq/ipi: Simplify irq_reserve_ipi

On 11/24/20 7:17 AM, Alexey Kardashevskiy wrote:
> __irq_domain_alloc_irqs() can already handle virq==-1 and free
> descriptors if it failed allocating hardware interrupts so let's skip
> this extra step.
> 
> Signed-off-by: Alexey Kardashevskiy <aik@...abs.ru>

LGTM,

Reviewed-by: Cédric Le Goater <clg@...d.org>

Copying the MIPS folks since the IPI interface is only used under arch/mips.

C.
 
> ---
>  kernel/irq/ipi.c | 16 +++-------------
>  1 file changed, 3 insertions(+), 13 deletions(-)
> 
> diff --git a/kernel/irq/ipi.c b/kernel/irq/ipi.c
> index 43e3d1be622c..1b2807318ea9 100644
> --- a/kernel/irq/ipi.c
> +++ b/kernel/irq/ipi.c
> @@ -75,18 +75,12 @@ int irq_reserve_ipi(struct irq_domain *domain,
>  		}
>  	}
>  
> -	virq = irq_domain_alloc_descs(-1, nr_irqs, 0, NUMA_NO_NODE, NULL);
> -	if (virq <= 0) {
> -		pr_warn("Can't reserve IPI, failed to alloc descs\n");
> -		return -ENOMEM;
> -	}
> -
> -	virq = __irq_domain_alloc_irqs(domain, virq, nr_irqs, NUMA_NO_NODE,
> -				       (void *) dest, true, NULL);
> +	virq = __irq_domain_alloc_irqs(domain, -1, nr_irqs, NUMA_NO_NODE,
> +				       (void *) dest, false, NULL);
>  
>  	if (virq <= 0) {
>  		pr_warn("Can't reserve IPI, failed to alloc hw irqs\n");
> -		goto free_descs;
> +		return -EBUSY;
>  	}
>  
>  	for (i = 0; i < nr_irqs; i++) {
> @@ -96,10 +90,6 @@ int irq_reserve_ipi(struct irq_domain *domain,
>  		irq_set_status_flags(virq + i, IRQ_NO_BALANCING);
>  	}
>  	return virq;
> -
> -free_descs:
> -	irq_free_descs(virq, nr_irqs);
> -	return -EBUSY;
>  }
>  
>  /**
>