linux-kernel - Re: [Patch V4 08/42] x86, ACPI, irq: enhance error handling in function acpi_register

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Message-ID: <alpine.DEB.2.10.1406100113070.3830@nanos>
Date:	Tue, 10 Jun 2014 01:19:11 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Jiang Liu <jiang.liu@...ux.intel.com>
cc:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Grant Likely <grant.likely@...aro.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>,
	Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
	x86@...nel.org, Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Tony Luck <tony.luck@...el.com>,
	Joerg Roedel <joro@...tes.org>,
	Paul Gortmaker <paul.gortmaker@...driver.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
	linux-acpi@...r.kernel.org, linux-pm@...r.kernel.org
Subject: Re: [Patch V4 08/42] x86, ACPI, irq: enhance error handling in
 function acpi_register_gsi()

On Mon, 9 Jun 2014, Jiang Liu wrote:

> Function mp_register_gsi() may return invalid GSI if error happens,
> so enhance acpi_register_gsi() to handle possible error cases.

Can you please explain how that happens? I think I know it, but it'd
be nice if it would be documented.

> Signed-off-by: Jiang Liu <jiang.liu@...ux.intel.com>
> ---
>  arch/x86/kernel/acpi/boot.c |   10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
> index 392360c607dc..f201579cd0df 100644
> --- a/arch/x86/kernel/acpi/boot.c
> +++ b/arch/x86/kernel/acpi/boot.c
> @@ -97,6 +97,8 @@ static u32 isa_irq_to_gsi[NR_IRQS_LEGACY] __read_mostly = {
>  	0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15
>  };
>  
> +#define	ACPI_INVALID_GSI		INT_MIN
> +
>  static unsigned int gsi_to_irq(unsigned int gsi)
>  {
>  	unsigned int irq = gsi + NR_IRQS_LEGACY;
> @@ -441,7 +443,7 @@ static int mp_register_gsi(struct device *dev, u32 gsi, int trigger,
>  			     polarity == ACPI_ACTIVE_HIGH ? 0 : 1);
>  	ret = io_apic_set_pci_routing(dev, gsi_to_irq(gsi), &irq_attr);
>  	if (ret < 0)
> -		gsi = INT_MIN;
> +		gsi = ACPI_INVALID_GSI;
>  
>  	return gsi;
>  }
> @@ -666,13 +668,13 @@ int (*acpi_suspend_lowlevel)(void);
>   */
>  int acpi_register_gsi(struct device *dev, u32 gsi, int trigger, int polarity)
>  {
> -	unsigned int irq;
>  	unsigned int plat_gsi = gsi;

The assignemend of gsi to plat_gsi is pointless
  
>  	plat_gsi = (*__acpi_register_gsi)(dev, gsi, trigger, polarity);

__acpi_register_gsi is a function pointer, so

  	plat_gsi = __acpi_register_gsi(dev, gsi, trigger, polarity);

is completely correct and way simpler to read.

> -	irq = gsi_to_irq(plat_gsi);
> +	if (plat_gsi != ACPI_INVALID_GSI)
> +		return gsi_to_irq(plat_gsi);
>  
> -	return irq;
> +	return -1;
>  }
>  EXPORT_SYMBOL_GPL(acpi_register_gsi);

No need to repost the whole series. Just reply with a new version to
this.

Thanks,

	tglx
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