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[PATCH v3 03/10] VFIO: platform: single handler using function pointer

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  [PATCH v3 03/10] VFIO: platform: single handler using function pointer Eric Auger <eric.auger@linaro.org> - 2015-08-10 15:30 +0200
    Re: [PATCH v3 03/10] VFIO: platform: single handler using function  pointer Alex Williamson <alex.williamson@redhat.com> - 2015-08-12 21:00 +0200
      Re: [PATCH v3 03/10] VFIO: platform: single handler using function  pointer Eric Auger <eric.auger@linaro.org> - 2015-08-17 17:30 +0200

#1204263 — [PATCH v3 03/10] VFIO: platform: single handler using function pointer

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@linaro.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);
 
@@ -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 {
-- 
1.9.1

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#1206328 — 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@linaro.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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#1208649 — Re: [PATCH v3 03/10] VFIO: platform: single handler using function pointer

Alex,
On 08/12/2015 08:56 PM, Alex Williamson wrote:
> 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@linaro.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?

No I did not check with lockdep and I will do. There is a comment in
fs/eventfd.c in eventfd_signal function comments that says:

"This function is supposed to be called by the kernel in paths that do
not allow sleeping. In this function we allow the counter to reach the
ULLONG_MAX value, and we signal this as overflow condition by returining
a POLLERR to poll(2)."

so I understood from this it is safe.

Best Regards

Eric

> 
>>  
>> @@ -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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