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

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Message-ID: <55D2004D.9010401@linaro.org>
Date:	Mon, 17 Aug 2015 17:39:57 +0200
From:	Eric Auger <eric.auger@...aro.org>
To:	Alex Williamson <alex.williamson@...hat.com>
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 08/12/2015 08:56 PM, Alex Williamson wrote:
> 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()?
OK
> 
>> +{
>> +	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?
sure

Eric
> 
>> +	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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