regression caused by: genirq: do not leave interupts enabled on free_irq

["Yinghai Lu" <yhlu.kernel@gmail.com>]

last week found:
after latest kernel kexec RHEL 5.1 or other stack kernel, the nvidia
forcedeth doesn't work anymore.

I stared at forcedeth.c two days. and revert every patches about that
doesn't help.

and figure out 2.6.25-rc2 works.

with git-bisect found

commit 89d694b9dbe769ca1004e01db0ca43964806a611
Author: Thomas Gleixner <tglx@linutronix.de>
Date:   Mon Feb 18 18:25:17 2008 +0100

    genirq: do not leave interupts enabled on free_irq

    The default_disable() function was changed in commit:

     76d2160147f43f982dfe881404cfde9fd0a9da21
     genirq: do not mask interrupts by default

    It removed the mask function in favour of the default delayed
    interrupt disabling. Unfortunately this also broke the shutdown in
    free_irq() when the last handler is removed from the interrupt for
    those architectures which rely on the default implementations. Now we
    can end up with a enabled interrupt line after the last handler was
    removed, which can result in spurious interrupts.

    Fix this by adding a default_shutdown function, which is only
    installed, when the irqchip implementation does provide neither a
    shutdown nor a disable function.

    [@stable: affected versions: .21 - .24 ]

    Pointed-out-by: Michael Hennerich <Michael.Hennerich@analog.com>
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Acked-by: Ingo Molnar <mingo@elte.hu>
    Cc: stable@kernel.org
    Tested-by: Michael Hennerich <Michael.Hennerich@analog.com>

caused the regression.

it affected all my servers that are using Nvidia MCP55.

maybe we need to revert that patch.

YH