Re: [PATCH] genirq: use irq_mask as fallback for irq_disable.

[Andrew Morton <akpm@linux-foundation.org>]

On Fri, 19 Apr 2013 15:41:02 +0200 Andreas Fenkart <andreas.fenkart@streamunlimited.com> wrote:

> This is in line with irq_enable that uses the same fallback.
> When masked, interrupts are still latched into the status register
> so when unmasked there is an interrupt straight away.
> 
> ...
>
> --- a/kernel/irq/chip.c
> +++ b/kernel/irq/chip.c
> @@ -216,10 +216,11 @@ void irq_enable(struct irq_desc *desc)
>  void irq_disable(struct irq_desc *desc)
>  {
>  	irq_state_set_disabled(desc);
> -	if (desc->irq_data.chip->irq_disable) {
> +	if (desc->irq_data.chip->irq_disable)
>  		desc->irq_data.chip->irq_disable(&desc->irq_data);
> -		irq_state_set_masked(desc);
> -	}
> +	else
> +		desc->irq_data.chip->irq_mask(&desc->irq_data);
> +	irq_state_set_masked(desc);
>  }
>  
>  void irq_percpu_enable(struct irq_desc *desc, unsigned int cpu)

Well I hope Thomas knows what this patch does, because I sure don't.

Does it fix a bug?  Does it add a bug?  Does it have any
runtime-observable effects at all?  If so, what are they?