Comment 12 for bug 1598312

3b806e2b94cad37a8809df7c86f7cfdcd3baa719 is the first bad commit
commit 3b806e2b94cad37a8809df7c86f7cfdcd3baa719
Author: Thomas Gleixner <email address hidden>
Date: Mon Sep 14 12:00:55 2015 +0200

    x86/ioapic: Force affinity setting in setup_ioapic_dest()

    BugLink: http://bugs.launchpad.net/bugs/1509886

    commit 4857c91f0d195f05908fff296ba1ec5fca87066c upstream.

    The recent ioapic cleanups changed the affinity setting in
    setup_ioapic_dest() from a direct write to the hardware to the delayed
    affinity setup via irq_set_affinity().

    That results in a warning from chained_irq_exit():
    WARNING: CPU: 0 PID: 5 at kernel/irq/migration.c:32 irq_move_masked_irq
    [<ffffffff810a0a88>] irq_move_masked_irq+0xb8/0xc0
    [<ffffffff8103c161>] ioapic_ack_level+0x111/0x130
    [<ffffffff812bbfe8>] intel_gpio_irq_handler+0x148/0x1c0

    The reason is that irq_set_affinity() does not write directly to the
    hardware. It marks the affinity setting as pending and executes it
    from the next interrupt. The chained handler infrastructure does not
    take the irq descriptor lock for performance reasons because such a
    chained interrupt is not visible to any interfaces. So the delayed
    affinity setting triggers the warning in irq_move_masked_irq().

    Restore the old behaviour by calling the set_affinity function of the
    ioapic chip in setup_ioapic_dest(). This is safe as none of the
    interrupts can be on the fly at this point.

    Fixes: aa5cb97f14a2 'x86/irq: Remove x86_io_apic_ops.set_affinity and related interfaces'
    Reported-and-tested-by: Mika Westerberg <email address hidden>
    Signed-off-by: Thomas Gleixner <email address hidden>
    Cc: Jiang Liu <email address hidden>
    Cc: <email address hidden>
    Signed-off-by: Greg Kroah-Hartman <email address hidden>

    Signed-off-by: Tim Gardner <email address hidden>
    Signed-off-by: Brad Figg <email address hidden>

:040000 040000 0233ddd54b0d7f34ceb513fe09e8df462ab8b777 e811435d773d53cdb9c2a26e68586f0dc2e41bf8 M arch