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    SubjectRe: [PATCH] acpi: add support for extended IRQ to PCI link
    From
    On Sun, Nov 8, 2015 at 6:07 PM, Sinan Kaya <okaya@codeaurora.org> 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.

    In commit messages and in comments I see this narrow lines, any reason
    to make them short, except increasing number of lines?

    > --- 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@intel.com>
    > * Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
    > * Copyright (C) 2002 Dominik Brodowski <devel@brodo.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;
    > };
    > @@ -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--) {

    Why not

    if ((acpi_irq_balance || !link->irq.active) && irq < ACPI_MAX_IRQS) {
    int i = link->irq.possible_count;

    while (--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) {

    --
    With Best Regards,
    Andy Shevchenko


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