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    SubjectRe: [PATCH] x86, irq: Check if irq is remapped before freeing irte
    On 10/18/2010 03:31 PM, Thomas Gleixner wrote:
    > On Mon, 18 Oct 2010, Yinghai Lu wrote:
    >
    >> On 10/18/2010 02:17 PM, Thomas Gleixner wrote:
    >>>
    >>>
    >>> On Mon, 18 Oct 2010, Thomas Gleixner wrote:
    >>>
    >>>> On Mon, 18 Oct 2010, Yinghai Lu wrote:
    >>>>>
    >>>>> Index: linux-2.6/drivers/pci/intr_remapping.c
    >>>>> ===================================================================
    >>>>> --- linux-2.6.orig/drivers/pci/intr_remapping.c
    >>>>> +++ linux-2.6/drivers/pci/intr_remapping.c
    >>>>> @@ -60,7 +60,7 @@ int get_irte(int irq, struct irte *entry
    >>>>> unsigned long flags;
    >>>>> int index;
    >>>>>
    >>>>> - if (!entry || !irq_iommu)
    >>>>> + if (!entry || !irq_iommu || !irq_iommu->iommu)
    >>>>> return -1;
    >>>>
    >>>> Hmm, why do we need this? This is only called from
    >>>> ir_ioapic_set_affinity() and ir_msi_set_affinity().
    >
    > That does not answer that question !
    we don't need that checking there.
    >
    >>>> We should never end up there when intr_remapping=off, right ?
    >>>
    >>> Thinking more about it, this check is actively bogus. The call sites do:
    >>>
    >>> struct irte irte;
    >>>
    >>> if (get_irte(irq, &irte))
    >>> return -1;
    >>>
    >>> So entry _CANNOT_ be NULL.
    >>>
    >>> And in fact we should change get_irte() to
    >>>
    >>> get_irte(struct irq_2_iommu *irq_iommu, struct irte *entry)
    >>>
    >>> The call site already knows about it. No need to lookup irq_iommu
    >>> based on the irq number.
    >>
    >> looks like all irq-irte related API could replace "int irq" to "struct irq_2_iommu *irq_iommu"
    >>
    >> extern int get_irte(int irq, struct irte *entry);
    >> extern int modify_irte(int irq, struct irte *irte_modified);
    >> extern int alloc_irte(struct intel_iommu *iommu, int irq, u16 count);
    >> extern int set_irte_irq(int irq, struct intel_iommu *iommu, u16 index,
    >> u16 sub_handle);
    >> extern int map_irq_to_irte_handle(int irq, u16 *sub_handle);
    >> extern int free_irte(int irq);
    >
    > Probably, but we need to figure out which functions need which checks
    > instead of having either redundant or superflous ones there.
    >
    only free_irte().

    because other have have protection from intr_remapping_enabled or irq_remapped(get_irq_chip_data(irq)) or with ir related chip.

    this one works too.

    ---
    arch/x86/kernel/apic/io_apic.c | 3 ++-
    1 file changed, 2 insertions(+), 1 deletion(-)

    Index: linux-2.6/arch/x86/kernel/apic/io_apic.c
    ===================================================================
    --- linux-2.6.orig/arch/x86/kernel/apic/io_apic.c
    +++ linux-2.6/arch/x86/kernel/apic/io_apic.c
    @@ -3109,7 +3109,8 @@ void destroy_irq(unsigned int irq)

    irq_set_status_flags(irq, IRQ_NOREQUEST|IRQ_NOPROBE);

    - free_irte(irq);
    + if (intr_remapping_enabled)
    + free_irte(irq);
    raw_spin_lock_irqsave(&vector_lock, flags);
    __clear_irq_vector(irq, cfg);
    raw_spin_unlock_irqrestore(&vector_lock, flags);

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