• Thomas Gleixner's avatar
    x86/ioapic: Force affinity setting in setup_ioapic_dest() · 4857c91f
    Thomas Gleixner authored
    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: aa5cb97f 'x86/irq: Remove x86_io_apic_ops.set_affinity and related interfaces'
    Reported-and-tested-by: default avatarMika Westerberg <mika.westerberg@linux.intel.com>
    Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
    Cc: Jiang Liu <jiang.liu@linux.intel.com>
    Cc: jarkko.nikula@linux.intel.com
    4857c91f
io_apic.c 76.9 KB