[RFC PATCH kernel] powerpc/xive: Drop deregistered irqs

[Benjamin Herrenschmidt]

On Fri, 2019-07-12 at 18:20 +1000, Alexey Kardashevskiy wrote:
> 
> diff --git a/arch/powerpc/sysdev/xive/common.c b/arch/powerpc/sysdev/xive/common.c
> index 082c7e1c20f0..65742e280337 100644
> --- a/arch/powerpc/sysdev/xive/common.c
> +++ b/arch/powerpc/sysdev/xive/common.c
> @@ -148,8 +148,12 @@ static u32 xive_scan_interrupts(struct xive_cpu *xc, bool just_peek)
>  		irq = xive_read_eq(&xc->queue[prio], just_peek);
>  
>  		/* Found something ? That's it */
> -		if (irq)
> -			break;
> +		if (irq) {
> +			/* Another CPU may have shut this irq down, check it */
> +			if (irq_to_desc(irq))

What if it gets deregistered here .... ?

> +				break;
> +			irq = 0;
> +		}
>  
>  		/* Clear pending bits */
>  		xc->pending_prio &= ~(1 << prio);

Wouldn't it be better to check the return value from generic_handle_irq
instead ?

Cheers,
Ben.