linux-kernel - Re: [PATCH v6 1/2] ACPI: introduce a function to find the first physical device

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Message-ID: <2019009.4Y5n3ZF6bK@vostro.rjw.lan>
Date:	Tue, 16 Feb 2016 02:20:36 +0100
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Aleksey Makarov <aleksey.makarov@...aro.org>
Cc:	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	Graeme Gregory <graeme.gregory@...aro.org>,
	Russell King <linux@....linux.org.uk>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Shannon Zhao <shannon.zhao@...aro.org>,
	Andy Shevchenko <andy.shevchenko@...il.com>,
	Vladimir Zapolskiy <vz@...ia.com>, Len Brown <lenb@...nel.org>
Subject: Re: [PATCH v6 1/2] ACPI: introduce a function to find the first physical device

On Wednesday, January 20, 2016 08:29:26 PM Aleksey Makarov wrote:
> Factor out the code that finds the first physical device
> of a given ACPI device.  It is used in several places.
> 
> Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>

I guess the above doesn't apply any more, does it?

> Signed-off-by: Aleksey Makarov <aleksey.makarov@...aro.org>
> ---
>  drivers/acpi/acpi_platform.c | 19 ++-----------------
>  drivers/acpi/bus.c           | 33 ++++++++++++++++++++++-----------
>  drivers/acpi/internal.h      |  1 +
>  3 files changed, 25 insertions(+), 28 deletions(-)
> 
> diff --git a/drivers/acpi/acpi_platform.c b/drivers/acpi/acpi_platform.c
> index 296b7a1..c3af108 100644
> --- a/drivers/acpi/acpi_platform.c
> +++ b/drivers/acpi/acpi_platform.c
> @@ -43,7 +43,6 @@ static const struct acpi_device_id forbidden_id_list[] = {
>  struct platform_device *acpi_create_platform_device(struct acpi_device *adev)
>  {
>  	struct platform_device *pdev = NULL;
> -	struct acpi_device *acpi_parent;
>  	struct platform_device_info pdevinfo;
>  	struct resource_entry *rentry;
>  	struct list_head resource_list;
> @@ -82,22 +81,8 @@ struct platform_device *acpi_create_platform_device(struct acpi_device *adev)
>  	 * attached to it, that physical device should be the parent of the
>  	 * platform device we are about to create.
>  	 */
> -	pdevinfo.parent = NULL;
> -	acpi_parent = adev->parent;
> -	if (acpi_parent) {
> -		struct acpi_device_physical_node *entry;
> -		struct list_head *list;
> -
> -		mutex_lock(&acpi_parent->physical_node_lock);
> -		list = &acpi_parent->physical_node_list;
> -		if (!list_empty(list)) {
> -			entry = list_first_entry(list,
> -					struct acpi_device_physical_node,
> -					node);
> -			pdevinfo.parent = entry->dev;
> -		}
> -		mutex_unlock(&acpi_parent->physical_node_lock);
> -	}
> +	pdevinfo.parent = adev->parent ?
> +		acpi_get_first_physical_node(adev->parent) : NULL;
>  	pdevinfo.name = dev_name(&adev->dev);
>  	pdevinfo.id = -1;
>  	pdevinfo.res = resources;
> diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
> index a212cef..832b26d 100644
> --- a/drivers/acpi/bus.c
> +++ b/drivers/acpi/bus.c
> @@ -478,24 +478,35 @@ static void acpi_device_remove_notify_handler(struct acpi_device *device)
>                               Device Matching
>     -------------------------------------------------------------------------- */
>  
> -static struct acpi_device *acpi_primary_dev_companion(struct acpi_device *adev,
> -						      const struct device *dev)
> +/**
> + * acpi_device_fix_parent - Get first physical node of an ACPI device

Please fix the function name here.

> + * @adev: ACPI device in question
> + */
> +struct device *acpi_get_first_physical_node(struct acpi_device *adev)
>  {
>  	struct mutex *physical_node_lock = &adev->physical_node_lock;
> +	struct device *node = NULL;
>  
>  	mutex_lock(physical_node_lock);
> -	if (list_empty(&adev->physical_node_list)) {
> -		adev = NULL;
> -	} else {
> -		const struct acpi_device_physical_node *node;
>  
> +	if (!list_empty(&adev->physical_node_list))
>  		node = list_first_entry(&adev->physical_node_list,
> -					struct acpi_device_physical_node, node);
> -		if (node->dev != dev)
> -			adev = NULL;
> -	}
> +				struct acpi_device_physical_node, node)->dev;
> +

No, you don't have to change all that code.

Exercise: rework this function with as few lines of code changed as you possibly can.

>  	mutex_unlock(physical_node_lock);
> -	return adev;
> +
> +	return node;
> +}
> +
> +static struct acpi_device *acpi_primary_dev_companion(struct acpi_device *adev,
> +						      const struct device *dev)
> +{
> +	const struct device *node = acpi_get_first_physical_node(adev);

s/node/phys_dev/ ?

> +
> +	if (node && node == dev)
> +		return adev;
> +
> +	return NULL;

return phys_dev && phys_dev == dev ? adev : NULL;

One line of code instead of 4.

>  }
>  
>  /**
> diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
> index 11d87bf..ee9312ba 100644
> --- a/drivers/acpi/internal.h
> +++ b/drivers/acpi/internal.h
> @@ -98,6 +98,7 @@ bool acpi_device_is_present(struct acpi_device *adev);
>  bool acpi_device_is_battery(struct acpi_device *adev);
>  bool acpi_device_is_first_physical_node(struct acpi_device *adev,
>  					const struct device *dev);
> +struct device *acpi_get_first_physical_node(struct acpi_device *adev);
>  
>  /* --------------------------------------------------------------------------
>                       Device Matching and Notification
> 

Thanks,
Rafael