Jeff Garzik <jeff@garzik.org> writes:

quoted text
> commit 008b5fcf3c1d8456005de26ddd4256b1369225e8
> Author: Jeff Garzik <jeff@garzik.org>
> Date:   Fri Oct 19 00:45:51 2007 -0400
>
>     [IRQ ARG REMOVAL] core interrupt delivery infrastructure updates
>
>  include/asm-generic/irq_regs.h |   25 +++++++++++++++++++++++++
>  include/linux/interrupt.h      |    4 ++--
>  kernel/irq/handle.c            |    5 +++--
>  kernel/irq/manage.c            |    4 ++--
>  kernel/irq/spurious.c          |    3 ++-
>  lib/irq_regs.c                 |    5 +++++
>  6 files changed, 39 insertions(+), 7 deletions(-)
>
> 008b5fcf3c1d8456005de26ddd4256b1369225e8
> diff --git a/include/asm-generic/irq_regs.h b/include/asm-generic/irq_regs.h
> index 5ae1d07..1d99ef4 100644
> --- a/include/asm-generic/irq_regs.h
> +++ b/include/asm-generic/irq_regs.h
> @@ -34,4 +34,29 @@ static inline struct pt_regs *set_irq_regs(struct pt_regs
> *new_regs)
>  	return old_regs;
>  }
>  
> +DECLARE_PER_CPU(unsigned int, __irqfunc_irqs);
> +
> +static inline unsigned int get_irqfunc_irq(void)
> +{
> +	return __get_cpu_var(__irqfunc_irqs);
> +}
> +
> +#if 0
> +static inline unsigned int set_irqfunc_irq(unsigned int new_irq)
> +{
> +	unsigned int old_irq, *pirq = &__get_cpu_var(__irqfunc_irqs);
> +
> +	old_irq = *pirq;
> +	*pirq = new_irq;
> +	return old_irq;
> +}
> +#else
> +static inline void set_irqfunc_irq(unsigned int new_irq)
> +{
> +	int *pirq = &__get_cpu_var(__irqfunc_irqs);
> +
> +	*pirq = new_irq;
> +}
> +#endif

Please look at handle_IRQ_event.  Local irqs are enabled so irq
recursion can happen.  So not handling old_irq is a big nasty
bug.

Eric
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