linux-kernel - Re: [RFC Part2 v1 03/21] x86, irq: Save destination CPU ID in irq

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Message-ID: <alpine.DEB.2.10.1409161046460.4247@nanos>
Date:	Tue, 16 Sep 2014 10:47:27 -0700 (PDT)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Jiang Liu <jiang.liu@...ux.intel.com>
cc:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Randy Dunlap <rdunlap@...radead.org>,
	Yinghai Lu <yinghai@...nel.org>,
	Borislav Petkov <bp@...en8.de>,
	Grant Likely <grant.likely@...aro.org>,
	Marc Zyngier <marc.zyngier@....com>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Tony Luck <tony.luck@...el.com>,
	Joerg Roedel <joro@...tes.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	x86@...nel.org, linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org, linux-acpi@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [RFC Part2 v1 03/21] x86, irq: Save destination CPU ID in
 irq_cfg



On Thu, 11 Sep 2014, Jiang Liu wrote:

> Cache destination CPU APIC ID into struct irq_cfg when assigning vector
> for interrupt. Upper layer just needs to read the cached APIC ID instead
> of calling apic->cpu_mask_to_apicid_and(), it helps to hide APIC driver
> details from IOAPIC/HPET/MSI drivers..
> 
> Signed-off-by: Jiang Liu <jiang.liu@...ux.intel.com>
> ---
>  arch/x86/include/asm/hw_irq.h |    1 +
>  arch/x86/kernel/apic/vector.c |    4 ++++
>  2 files changed, 5 insertions(+)
> 
> diff --git a/arch/x86/include/asm/hw_irq.h b/arch/x86/include/asm/hw_irq.h
> index 7624fffc2822..3d51d74d6c01 100644
> --- a/arch/x86/include/asm/hw_irq.h
> +++ b/arch/x86/include/asm/hw_irq.h
> @@ -116,6 +116,7 @@ struct irq_data;
>  struct irq_cfg {
>  	cpumask_var_t		domain;
>  	cpumask_var_t		old_domain;
> +	unsigned int		dest_apicid;
>  	u8			vector;
>  	u8			move_in_progress : 1;
>  #ifdef CONFIG_IRQ_REMAP
> diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c
> index 7562cb15b3bd..287ae4e8d500 100644
> --- a/arch/x86/kernel/apic/vector.c
> +++ b/arch/x86/kernel/apic/vector.c
> @@ -188,6 +188,10 @@ next:
>  	}
>  	free_cpumask_var(tmp_mask);

Lacks a comment what this call is actually doing.
  
> +	if (!err)
> +		err = apic->cpu_mask_to_apicid_and(mask, cfg->domain,
> +						   &cfg->dest_apicid);
> +

Thanks,

	tglx
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