linux-kernel - Re: [PATCH v3 03/10] VFIO: platform: single handler using function pointer

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Date:	Wed, 12 Aug 2015 12:56:20 -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 03/10] VFIO: platform: single handler using function
 pointer

On Mon, 2015-08-10 at 15:20 +0200, Eric Auger wrote:
> A single handler now is registered whatever the use case: automasked
> or not. A function pointer is set according to the wished behavior
> and the handler calls this function.
> 
> The irq lock is taken/released in the root handler. eventfd_signal can
> be called in regions not allowed to sleep.
> 
> Signed-off-by: Eric Auger <eric.auger@...aro.org>
> 
> ---
> 
> v4: creation
> ---
>  drivers/vfio/platform/vfio_platform_irq.c     | 21 +++++++++++++++------
>  drivers/vfio/platform/vfio_platform_private.h |  1 +
>  2 files changed, 16 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/vfio/platform/vfio_platform_irq.c b/drivers/vfio/platform/vfio_platform_irq.c
> index 40f057a..b31b1f0 100644
> --- a/drivers/vfio/platform/vfio_platform_irq.c
> +++ b/drivers/vfio/platform/vfio_platform_irq.c
> @@ -148,11 +148,8 @@ static int vfio_platform_set_irq_unmask(struct vfio_platform_device *vdev,
>  static irqreturn_t vfio_automasked_irq_handler(int irq, void *dev_id)
>  {
>  	struct vfio_platform_irq *irq_ctx = dev_id;
> -	unsigned long flags;
>  	int ret = IRQ_NONE;
>  
> -	spin_lock_irqsave(&irq_ctx->lock, flags);
> -
>  	if (!irq_ctx->masked) {
>  		ret = IRQ_HANDLED;
>  
> @@ -161,8 +158,6 @@ static irqreturn_t vfio_automasked_irq_handler(int irq, void *dev_id)
>  		irq_ctx->masked = true;
>  	}
>  
> -	spin_unlock_irqrestore(&irq_ctx->lock, flags);
> -
>  	if (ret == IRQ_HANDLED)
>  		eventfd_signal(irq_ctx->trigger, 1);

Has this been run with lockdep to check whether this is safe to call
with spinlock_irqsave held?

>  
> @@ -178,6 +173,19 @@ static irqreturn_t vfio_irq_handler(int irq, void *dev_id)
>  	return IRQ_HANDLED;
>  }
>  
> +static irqreturn_t vfio_handler(int irq, void *dev_id)
> +{
> +	struct vfio_platform_irq *irq_ctx = dev_id;
> +	unsigned long flags;
> +	irqreturn_t ret;
> +
> +	spin_lock_irqsave(&irq_ctx->lock, flags);
> +	ret = irq_ctx->handler(irq, dev_id);
> +	spin_unlock_irqrestore(&irq_ctx->lock, flags);
> +
> +	return ret;
> +}
> +
>  static void vfio_platform_irq_bypass_stop(struct irq_bypass_producer *prod)
>  {
>  }
> @@ -229,9 +237,10 @@ static int vfio_set_trigger(struct vfio_platform_device *vdev, int index,
>  	}
>  
>  	irq->trigger = trigger;
> +	irq->handler = handler;
>  
>  	irq_set_status_flags(irq->hwirq, IRQ_NOAUTOEN);
> -	ret = request_irq(irq->hwirq, handler, 0, irq->name, irq);
> +	ret = request_irq(irq->hwirq, vfio_handler, 0, irq->name, irq);
>  	if (ret) {
>  		kfree(irq->name);
>  		eventfd_ctx_put(trigger);
> diff --git a/drivers/vfio/platform/vfio_platform_private.h b/drivers/vfio/platform/vfio_platform_private.h
> index 8b4f814..f848a6b 100644
> --- a/drivers/vfio/platform/vfio_platform_private.h
> +++ b/drivers/vfio/platform/vfio_platform_private.h
> @@ -40,6 +40,7 @@ struct vfio_platform_irq {
>  	struct virqfd		*mask;
>  	struct irq_bypass_producer producer;
>  	bool			forwarded;
> +	irqreturn_t (*handler)(int irq, void *dev_id);
>  };
>  
>  struct vfio_platform_region {



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