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    Subject[tip:x86/apic] x86: fix set_extra_move_desc calling
    Commit-ID:  fa74c9073370e57fa28e02aff13f4d7b1806505c
    Author: Yinghai Lu <>
    AuthorDate: Tue, 24 Mar 2009 13:23:16 -0700
    Committer: Ingo Molnar <>
    CommitDate: Tue, 24 Mar 2009 22:12:10 +0100

    x86: fix set_extra_move_desc calling

    Impact: fix bug with irq-descriptor moving when logical flat

    Rusty observed:

    > The effect of setting desc->affinity (ie. from userspace via sysfs) has varied
    > over time. In 2.6.27, the 32-bit code anded the value with cpu_online_map,
    > and both 32 and 64-bit did that anding whenever a cpu was unplugged.
    > 2.6.29 consolidated this into one routine (and fixed hotplug) but introduced
    > another variation: anding the affinity with cfg->domain. Is this right, or
    > should we just set it to what the user said? Or as now, indicate that we're
    > restricting it.

    Eric pointed out that desc->affinity should be what the user requested,
    if it is at all possible to honor the user space request.

    This bug got introduced by commit 22f65d31b "x86: Update io_apic.c to use
    new cpumask API".

    Fix it by moving the masking to before the descriptor moving ...

    Reported-by: Rusty Russell <>
    Reported-by: Eric W. Biederman <>
    LKML-Reference: <>
    Signed-off-by: Ingo Molnar <>

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

    diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
    index 86827d8..1ed6c06 100644
    --- a/arch/x86/kernel/apic/io_apic.c
    +++ b/arch/x86/kernel/apic/io_apic.c
    @@ -592,8 +592,9 @@ set_desc_affinity(struct irq_desc *desc, const struct cpumask *mask)
    if (assign_irq_vector(irq, cfg, mask))
    return BAD_APICID;

    - cpumask_and(desc->affinity, cfg->domain, mask);
    + /* check that before desc->addinity get updated */
    set_extra_move_desc(desc, mask);
    + cpumask_and(desc->affinity, cfg->domain, mask);

    return apic->cpu_mask_to_apicid_and(desc->affinity, cpu_online_mask);

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      Last update: 2009-03-24 22:23    [W:0.023 / U:49.588 seconds]
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