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

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Message-ID: <20110607105508.1f3033fa@archvile>
Date:	Tue, 7 Jun 2011 10:55:08 +0200
From:	David Jander <david.jander@...tonic.nl>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: Why does handle_simple_irq() require IRQ's to be disabled?


Dear Thomas,

On Tue, 7 Jun 2011 10:26:26 +0200 (CEST)
Thomas Gleixner <tglx@...utronix.de> wrote:

> On Tue, 7 Jun 2011, David Jander wrote:
> > On Mon, 6 Jun 2011 18:18:41 +0200 (CEST)
> > Thomas Gleixner <tglx@...utronix.de> wrote:
> > > handle_nested_irq() is your friend.
> > 
> > Thanks! This worked without disabling IRQ's.
> > One last question, though:
> > 
> > I set up the handler using irq_set_chip_and_handler(irq, ...,
> > handle_simple_irq);
> > From the interrupt thread, I call handle_nested_irq(). Is it OK, that in
> > this case, the defined handler function (handle_simple_irq) is not used?
> > Does this still make sense? Wouldn't calling just irq_set_chip() be enough
> > here (it seems to work correctly)?
> 
> It should be enough. Though you should mark the demuxed interrupts
> with irq_set_nested_thread(irqnr, true). That avoids that you create
> extra threads for the demuxed interrupts which are never used.

Cool! Now the disturbingly big list of kernel threads is gone :-)

Thanks a lot!

-- 
David Jander
Protonic Holland.
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