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Commit d6b0c580 authored by Dmitry Torokhov's avatar Dmitry Torokhov
Browse files

devres: allow adding custom actions to the stack 



Sometimes drivers need to execute one-off actions in their error handling
or device teardown paths. An example would be toggling a GPIO line to
reset the controlled device into predefined state.

To allow performing such actions when using managed resources let's allow
adding them to stack/group of devres resources.

Acked-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarDmitry Torokhov <dmitry.torokhov@gmail.com>
parent 7241443f

drivers/base/devres.c

+74 −0
Original line number Original line Diff line number Diff line
@@ -670,6 +670,80 @@ int devres_release_group(struct device *dev, void *id) 
}

}

EXPORT_SYMBOL_GPL(devres_release_group);

EXPORT_SYMBOL_GPL(devres_release_group);





/*

 * Custom devres actions allow inserting a simple function call

 * into the teadown sequence.

 */



struct action_devres {

	void *data;

	void (*action)(void *);

};



static int devm_action_match(struct device *dev, void *res, void *p)

{

	struct action_devres *devres = res;

	struct action_devres *target = p;



	return devres->action == target->action &&

	       devres->data == target->data;

}



static void devm_action_release(struct device *dev, void *res)

{

	struct action_devres *devres = res;



	devres->action(devres->data);

}



/**

 * devm_add_action() - add a custom action to list of managed resources

 * @dev: Device that owns the action

 * @action: Function that should be called

 * @data: Pointer to data passed to @action implementation

 *

 * This adds a custom action to the list of managed resources so that

 * it gets executed as part of standard resource unwinding.

 */

int devm_add_action(struct device *dev, void (*action)(void *), void *data)

{

	struct action_devres *devres;



	devres = devres_alloc(devm_action_release,

			      sizeof(struct action_devres), GFP_KERNEL);

	if (!devres)

		return -ENOMEM;



	devres->data = data;

	devres->action = action;



	devres_add(dev, devres);

	return 0;

}

EXPORT_SYMBOL_GPL(devm_add_action);



/**

 * devm_remove_action() - removes previously added custom action

 * @dev: Device that owns the action

 * @action: Function implementing the action

 * @data: Pointer to data passed to @action implementation

 *

 * Removes instance of @action previously added by devm_add_action().

 * Both action and data should match one of the existing entries.

 */

void devm_remove_action(struct device *dev, void (*action)(void *), void *data)

{

	struct action_devres devres = {

		.data = data,

		.action = action,

	};



	WARN_ON(devres_destroy(dev, devm_action_release, devm_action_match,

			       &devres));



}

EXPORT_SYMBOL_GPL(devm_remove_action);



/*

/*

 * Managed kzalloc/kfree

 * Managed kzalloc/kfree

 */

 */

include/linux/device.h

+4 −0
Original line number Original line Diff line number Diff line
@@ -567,6 +567,10 @@ extern void devm_kfree(struct device *dev, void *p); 
void __iomem *devm_request_and_ioremap(struct device *dev,

void __iomem *devm_request_and_ioremap(struct device *dev,

			struct resource *res);

			struct resource *res);





/* allows to add/remove a custom action to devres stack */

int devm_add_action(struct device *dev, void (*action)(void *), void *data);

void devm_remove_action(struct device *dev, void (*action)(void *), void *data);



struct device_dma_parameters {

struct device_dma_parameters {

	/*

	/*

	 * a low level driver may set these to teach IOMMU code about

	 * a low level driver may set these to teach IOMMU code about