linux-kernel - Re: [PATCH v3 05/10] VFIO: platform: add vfio_platform_is

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Message-ID: <1439405805.4023.529.camel@redhat.com>
Date:	Wed, 12 Aug 2015 12:56:45 -0600
From:	Alex Williamson <alex.williamson@...hat.com>
To:	Eric Auger <eric.auger@...aro.org>
Cc:	eric.auger@...com, linux-arm-kernel@...ts.infradead.org,
	kvmarm@...ts.cs.columbia.edu, kvm@...r.kernel.org,
	christoffer.dall@...aro.org, marc.zyngier@....com,
	feng.wu@...el.com, linux-kernel@...r.kernel.org,
	patches@...aro.org, pbonzini@...hat.com
Subject: Re: [PATCH v3 05/10] VFIO: platform: add vfio_platform_is_active

On Mon, 2015-08-10 at 15:20 +0200, Eric Auger wrote:
> This function returns whether the IRQ is active at irqchip level or
> VFIO masked. If either is true, it is considered the IRQ is active.
> Currently there is no way to differentiate userspace masked IRQ from
> automasked IRQ. There might be false detection of activity. However
> it is currently acceptable to have false detection.
> 
> Signed-off-by: Eric Auger <eric.auger@...aro.org>
> 
> ---
> ---
>  drivers/vfio/platform/vfio_platform_irq.c | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
> 
> diff --git a/drivers/vfio/platform/vfio_platform_irq.c b/drivers/vfio/platform/vfio_platform_irq.c
> index a285384..efaee58 100644
> --- a/drivers/vfio/platform/vfio_platform_irq.c
> +++ b/drivers/vfio/platform/vfio_platform_irq.c
> @@ -205,6 +205,23 @@ static int vfio_platform_set_automasked(struct vfio_platform_irq *irq,
>  	return 0;
>  }
>  
> +static int vfio_platform_is_active(struct vfio_platform_irq *irq)

vfio_platform_irq_is_active()?

> +{
> +	unsigned long flags;
> +	bool active, masked, outstanding;
> +	int ret;
> +
> +	spin_lock_irqsave(&irq->lock, flags);
> +
> +	ret = irq_get_irqchip_state(irq->hwirq, IRQCHIP_STATE_ACTIVE, &active);
> +	BUG_ON(ret);

Why can't we propagate this error to the caller and let them decide?

> +	masked = irq->masked;
> +	outstanding = active || masked;
> +
> +	spin_unlock_irqrestore(&irq->lock, flags);
> +	return outstanding;
> +}
> +
>  static void vfio_platform_irq_bypass_stop(struct irq_bypass_producer *prod)
>  {
>  }



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