linux-kernel - Re: [PATCH] acpi: add support for extended IRQ to PCI link

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Message-ID: <56402E23.1070805@linux.intel.com>
Date:	Mon, 9 Nov 2015 13:24:51 +0800
From:	Jiang Liu <jiang.liu@...ux.intel.com>
To:	Sinan Kaya <okaya@...eaurora.org>, linux-acpi@...r.kernel.org,
	timur@...eaurora.org, cov@...eaurora.org, jcm@...hat.com
Cc:	agross@...eaurora.org, linux-arm-msm@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Len Brown <lenb@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] acpi: add support for extended IRQ to PCI link

On 2015/11/9 0:07, Sinan Kaya wrote:
> The ACPI compiler uses the extended format when
> used interrupt numbers are greater than 256.
> The PCI link code currently only supports simple
> interrupt format. The IRQ numbers are represented
> using 32 bits when extended IRQ syntax. This patch
> changes the interrupt number type to 32 bits and
> places an upper limit of 1020 as possible interrupt
> id. Additional checks have been placed to prevent
> out of bounds writes.
> 
> Signed-off-by: Sinan Kaya <okaya@...eaurora.org>
> ---
>  drivers/acpi/pci_link.c | 35 ++++++++++++++++++++++-------------
>  1 file changed, 22 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/acpi/pci_link.c b/drivers/acpi/pci_link.c
> index 7c8408b..18a9190 100644
> --- a/drivers/acpi/pci_link.c
> +++ b/drivers/acpi/pci_link.c
> @@ -1,6 +1,7 @@
>  /*
>   *  pci_link.c - ACPI PCI Interrupt Link Device Driver ($Revision: 34 $)
>   *
> + *  Copyright (c) 2015, The Linux Foundation. All rights reserved.
>   *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@...el.com>
>   *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@...el.com>
>   *  Copyright (C) 2002       Dominik Brodowski <devel@...do.de>
> @@ -67,12 +68,12 @@ static struct acpi_scan_handler pci_link_handler = {
>   * later even the link is disable. Instead, we just repick the active irq
>   */
>  struct acpi_pci_link_irq {
> -	u8 active;		/* Current IRQ */
> +	u32 active;		/* Current IRQ */
>  	u8 triggering;		/* All IRQs */
>  	u8 polarity;		/* All IRQs */
>  	u8 resource_type;
>  	u8 possible_count;
> -	u8 possible[ACPI_PCI_LINK_MAX_POSSIBLE];
> +	u32 possible[ACPI_PCI_LINK_MAX_POSSIBLE];
>  	u8 initialized:1;
>  	u8 reserved:7;
>  };
Hi Sinan,
	This data structure become some sort of big, any idea to reduce
memory consumption?
Thanks,
Gerry

> @@ -437,7 +438,7 @@ static int acpi_pci_link_set(struct acpi_pci_link *link, int irq)
>   * enabled system.
>   */
>  
> -#define ACPI_MAX_IRQS		256
> +#define ACPI_MAX_IRQS		1020
>  #define ACPI_MAX_ISA_IRQ	16
>  
>  #define PIRQ_PENALTY_PCI_AVAILABLE	(0)
> @@ -493,7 +494,8 @@ int __init acpi_irq_penalty_init(void)
>  					    penalty;
>  			}
>  
> -		} else if (link->irq.active) {
> +		} else if (link->irq.active &&
> +			(link->irq.active < ACPI_MAX_IRQS)) {
>  			acpi_irq_penalty[link->irq.active] +=
>  			    PIRQ_PENALTY_PCI_POSSIBLE;
>  		}
> @@ -542,14 +544,19 @@ static int acpi_pci_link_allocate(struct acpi_pci_link *link)
>  		irq = link->irq.possible[link->irq.possible_count - 1];
>  
>  	if (acpi_irq_balance || !link->irq.active) {
> -		/*
> -		 * Select the best IRQ.  This is done in reverse to promote
> -		 * the use of IRQs 9, 10, 11, and >15.
> -		 */
> -		for (i = (link->irq.possible_count - 1); i >= 0; i--) {
> -			if (acpi_irq_penalty[irq] >
> -			    acpi_irq_penalty[link->irq.possible[i]])
> -				irq = link->irq.possible[i];
> +
> +		if (irq < ACPI_MAX_IRQS) {
> +			/*
> +			 * Select the best IRQ.  This is done in reverse to
> +			 * promote the use of IRQs 9, 10, 11, and >15.
> +			 */
> +			for (i = (link->irq.possible_count - 1); i >= 0;
> +				i--) {
> +				if ((link->irq.possible[i] < ACPI_MAX_IRQS) &&
> +				    (acpi_irq_penalty[irq] >
> +				    acpi_irq_penalty[link->irq.possible[i]]))
> +					irq = link->irq.possible[i];
> +			}
>  		}
>  	}
>  	if (acpi_irq_penalty[irq] >= PIRQ_PENALTY_ISA_ALWAYS) {
> @@ -568,7 +575,9 @@ static int acpi_pci_link_allocate(struct acpi_pci_link *link)
>  			    acpi_device_bid(link->device));
>  		return -ENODEV;
>  	} else {
> -		acpi_irq_penalty[link->irq.active] += PIRQ_PENALTY_PCI_USING;
> +		if (link->irq.active < ACPI_MAX_IRQS)
> +			acpi_irq_penalty[link->irq.active] +=
> +				PIRQ_PENALTY_PCI_USING;
>  		printk(KERN_WARNING PREFIX "%s [%s] enabled at IRQ %d\n",
>  		       acpi_device_name(link->device),
>  		       acpi_device_bid(link->device), link->irq.active);
> 
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