linux-kernel - Re: Why does handle_simple_irq() require IRQ's to be disabled?

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Date:	Mon, 6 Jun 2011 18:18:41 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	David Jander <david.jander@...tonic.nl>
cc:	linux-kernel@...r.kernel.org
Subject: Re: Why does handle_simple_irq() require IRQ's to be disabled?

On Mon, 6 Jun 2011, David Jander wrote:
> 
> Hi,
> 
> I am trying to implement/fix interrupt controller functionality in
> gpio/pca953x.c, and for some reason which I don't understand, I need to disable
> interrupts with local_irq_disable() before calling generic_handle_irq(). This
> does not seem right.
> If I follow the code of handle_simple_irq(), the handler function setup for
> this IRQ, I get to handle_irq_event_percpu(), which has a
> WARN_ONCE(!irqs_disabled(),...
> This WARN is triggered, since nobody explicitly disables interrupts. Why?
>  
> generic_hanlde_irq() is called from a threaded interrupt handler of the parent
> of this interrupt controller, and calling local_irq_disable() here seems like
> a crime. What am I doing wrong?

handle_nested_irq() is your friend.
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