Re: [PATCH v2 1/2] resource: Add device-managed request/release_resource()

[Bjorn Helgaas <bhelgaas@google.com>]

On Fri, Aug 01, 2014 at 02:15:10PM +0200, Thierry Reding wrote:
> From: Thierry Reding <treding@nvidia.com>
> 
> Provide device-managed implementations of the request_resource() and
> release_resource() functions. Upon failure to request a resource, the
> new devm_request_resource() function will output an error message for
> consistent error reporting.
> 
> Signed-off-by: Thierry Reding <treding@nvidia.com>

Applied both, with Tejun's ack on the first, for v3.18, thanks!

> ---
> Changes in v2:
> - use more natural flow for error handling
> - don't needlessly check for NULL pointers
> 
>  Documentation/driver-model/devres.txt |  2 +
>  include/linux/ioport.h                |  5 +++
>  kernel/resource.c                     | 70 +++++++++++++++++++++++++++++++++++
>  3 files changed, 77 insertions(+)
> 
> diff --git a/Documentation/driver-model/devres.txt b/Documentation/driver-model/devres.txt
> index d14710b04439..befc3fe12ba6 100644
> --- a/Documentation/driver-model/devres.txt
> +++ b/Documentation/driver-model/devres.txt
> @@ -264,8 +264,10 @@ IIO
>  IO region
>    devm_release_mem_region()
>    devm_release_region()
> +  devm_release_resource()
>    devm_request_mem_region()
>    devm_request_region()
> +  devm_request_resource()
>  
>  IOMAP
>    devm_ioport_map()
> diff --git a/include/linux/ioport.h b/include/linux/ioport.h
> index 142ec544167c..2c5250222278 100644
> --- a/include/linux/ioport.h
> +++ b/include/linux/ioport.h
> @@ -215,6 +215,11 @@ static inline int __deprecated check_region(resource_size_t s,
>  
>  /* Wrappers for managed devices */
>  struct device;
> +
> +extern int devm_request_resource(struct device *dev, struct resource *root,
> +				 struct resource *new);
> +extern void devm_release_resource(struct device *dev, struct resource *new);
> +
>  #define devm_request_region(dev,start,n,name) \
>  	__devm_request_region(dev, &ioport_resource, (start), (n), (name))
>  #define devm_request_mem_region(dev,start,n,name) \
> diff --git a/kernel/resource.c b/kernel/resource.c
> index da14b8d09296..ca24f19f9d18 100644
> --- a/kernel/resource.c
> +++ b/kernel/resource.c
> @@ -1248,6 +1248,76 @@ int release_mem_region_adjustable(struct resource *parent,
>  /*
>   * Managed region resource
>   */
> +static void devm_resource_release(struct device *dev, void *ptr)
> +{
> +	struct resource **r = ptr;
> +
> +	release_resource(*r);
> +}
> +
> +/**
> + * devm_request_resource() - request and reserve an I/O or memory resource
> + * @dev: device for which to request the resource
> + * @root: root of the resource tree from which to request the resource
> + * @new: descriptor of the resource to request
> + *
> + * This is a device-managed version of request_resource(). There is usually
> + * no need to release resources requested by this function explicitly since
> + * that will be taken care of when the device is unbound from its driver.
> + * If for some reason the resource needs to be released explicitly, because
> + * of ordering issues for example, drivers must call devm_release_resource()
> + * rather than the regular release_resource().
> + *
> + * When a conflict is detected between any existing resources and the newly
> + * requested resource, an error message will be printed.
> + *
> + * Returns 0 on success or a negative error code on failure.
> + */
> +int devm_request_resource(struct device *dev, struct resource *root,
> +			  struct resource *new)
> +{
> +	struct resource *conflict, **ptr;
> +
> +	ptr = devres_alloc(devm_resource_release, sizeof(*ptr), GFP_KERNEL);
> +	if (!ptr)
> +		return -ENOMEM;
> +
> +	*ptr = new;
> +
> +	conflict = request_resource_conflict(root, new);
> +	if (conflict) {
> +		dev_err(dev, "resource collision: %pR conflicts with %s %pR\n",
> +			new, conflict->name, conflict);
> +		devres_free(ptr);
> +		return -EBUSY;
> +	}
> +
> +	devres_add(dev, ptr);
> +	return 0;
> +}
> +EXPORT_SYMBOL(devm_request_resource);
> +
> +static int devm_resource_match(struct device *dev, void *res, void *data)
> +{
> +	struct resource **ptr = res;
> +
> +	return *ptr == data;
> +}
> +
> +/**
> + * devm_release_resource() - release a previously requested resource
> + * @dev: device for which to release the resource
> + * @new: descriptor of the resource to release
> + *
> + * Releases a resource previously requested using devm_request_resource().
> + */
> +void devm_release_resource(struct device *dev, struct resource *new)
> +{
> +	WARN_ON(devres_release(dev, devm_resource_release, devm_resource_match,
> +			       new));
> +}
> +EXPORT_SYMBOL(devm_release_resource);
> +
>  struct region_devres {
>  	struct resource *parent;
>  	resource_size_t start;
> -- 
> 2.0.3
>