Date: Wed, 1 Apr 2009 12:14:25 +0200 (CEST)
From: Thomas Gleixner <tglx@linutronix.de>
To: Luis Henriques <henrix@sapo.pt>
cc: Ingo Molnar <mingo@elte.hu>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH -tip] irq: DEBUG_SHIRQ executed on irq setup failure
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On Tue, 31 Mar 2009, Luis Henriques wrote:

> When requesting an IRQ, the DEBUG_SHIRQ code executes a fake IRQ just to make
> sure the driver is ready to receive an IRQ immediately.  The problem was that
> this fake IRQ was being executed even if interrupt line failed to be allocated
> by __setup_irq.

Good point !

> Signed-off-by: Luis Henriques <henrix@sapo.pt>
> ---
>  kernel/irq/manage.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
> index a3eb7ba..8e1be16 100644
> --- a/kernel/irq/manage.c
> +++ b/kernel/irq/manage.c
> @@ -914,7 +914,7 @@ int request_threaded_irq(unsigned int irq, irq_handler_t handler,
>  		kfree(action);
>  
>  #ifdef CONFIG_DEBUG_SHIRQ
> -	if (irqflags & IRQF_SHARED) {
> +	if (retval && (irqflags & IRQF_SHARED)) {

  !retval might actually prevent the situation you described above :)

Thanks,

	tglx
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