[PATCH] vfio/platform: Use common error handling code in vfio_set_trigger()

[PATCH] vfio/platform: Use common error handling code in vfio_set_trigger()

[Markus Elfring]

From: Markus Elfring <elfring@users.sourceforge.net>
Date: Mon, 15 Jan 2024 18:08:29 +0100

Add a jump target so that a bit of exception handling can be better reused
in an if branch of this function.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
---
 drivers/vfio/platform/vfio_platform_irq.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/vfio/platform/vfio_platform_irq.c b/drivers/vfio/platform/vfio_platform_irq.c
index 61a1bfb68ac7..8604ce4f3fee 100644
--- a/drivers/vfio/platform/vfio_platform_irq.c
+++ b/drivers/vfio/platform/vfio_platform_irq.c
@@ -193,8 +193,8 @@ static int vfio_set_trigger(struct vfio_platform_device *vdev, int index,

 	trigger = eventfd_ctx_fdget(fd);
 	if (IS_ERR(trigger)) {
-		kfree(irq->name);
-		return PTR_ERR(trigger);
+		ret = PTR_ERR(trigger);
+		goto free_name;
 	}

 	irq->trigger = trigger;
@@ -202,9 +202,10 @@ static int vfio_set_trigger(struct vfio_platform_device *vdev, int index,
 	irq_set_status_flags(irq->hwirq, IRQ_NOAUTOEN);
 	ret = request_irq(irq->hwirq, handler, 0, irq->name, irq);
 	if (ret) {
-		kfree(irq->name);
 		eventfd_ctx_put(trigger);
 		irq->trigger = NULL;
+free_name:
+		kfree(irq->name);
 		return ret;
 	}

--
2.43.0

Re: [PATCH] vfio/platform: Use common error handling code in vfio_set_trigger()

[Alex Williamson]

On Mon, 15 Jan 2024 18:16:01 +0100
Markus Elfring <Markus.Elfring@web.de> wrote:

> From: Markus Elfring <elfring@users.sourceforge.net>
> Date: Mon, 15 Jan 2024 18:08:29 +0100
> 
> Add a jump target so that a bit of exception handling can be better reused
> in an if branch of this function.
> 
> Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
> ---
>  drivers/vfio/platform/vfio_platform_irq.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/vfio/platform/vfio_platform_irq.c b/drivers/vfio/platform/vfio_platform_irq.c
> index 61a1bfb68ac7..8604ce4f3fee 100644
> --- a/drivers/vfio/platform/vfio_platform_irq.c
> +++ b/drivers/vfio/platform/vfio_platform_irq.c
> @@ -193,8 +193,8 @@ static int vfio_set_trigger(struct vfio_platform_device *vdev, int index,
> 
>  	trigger = eventfd_ctx_fdget(fd);
>  	if (IS_ERR(trigger)) {
> -		kfree(irq->name);
> -		return PTR_ERR(trigger);
> +		ret = PTR_ERR(trigger);
> +		goto free_name;
>  	}
> 
>  	irq->trigger = trigger;
> @@ -202,9 +202,10 @@ static int vfio_set_trigger(struct vfio_platform_device *vdev, int index,
>  	irq_set_status_flags(irq->hwirq, IRQ_NOAUTOEN);
>  	ret = request_irq(irq->hwirq, handler, 0, irq->name, irq);
>  	if (ret) {
> -		kfree(irq->name);
>  		eventfd_ctx_put(trigger);
>  		irq->trigger = NULL;
> +free_name:
> +		kfree(irq->name);
>  		return ret;
>  	}
> 

TBH, this doesn't seem like a worthwhile exit point consolidation.  A
change like this might be justified if there were some common unlock
code that could be shared, but for a simple free and return errno by
jumping to a different exception block, rather than even a common exit
block, I don't see the value.  Thanks,

Alex

Re: vfio/platform: Use common error handling code in vfio_set_trigger()

[Markus Elfring]

> TBH, this doesn't seem like a worthwhile exit point consolidation.  A
> change like this might be justified if there were some common unlock
> code that could be shared, but for a simple free and return errno by
> jumping to a different exception block, rather than even a common exit
> block, I don't see the value.

Can it be helpful to store the shown kfree() call only once
in this function implementation?

Regards,
Markus

Re: vfio/platform: Use common error handling code in vfio_set_trigger()

[Alex Williamson]

On Tue, 16 Jan 2024 12:32:23 +0100
Markus Elfring <Markus.Elfring@web.de> wrote:

> > TBH, this doesn't seem like a worthwhile exit point consolidation.  A
> > change like this might be justified if there were some common unlock
> > code that could be shared, but for a simple free and return errno by
> > jumping to a different exception block, rather than even a common exit
> > block, I don't see the value.  
> 
> Can it be helpful to store the shown kfree() call only once
> in this function implementation?

I don't believe it's worthwhile, it's a simple function with simple
exit paths and consolidating those exit paths for a trivial kfree() is
unnecessarily complex.  Thanks,

Alex