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Commit 3d060aeb authored by Andy Shevchenko's avatar Andy Shevchenko Committed by Lee Jones
Browse files

driver core: implement device_for_each_child_reverse() 



The new function device_for_each_child_reverse() is helpful to traverse the
registered devices in a reversed order, e.g. in the case when an operation on
each device should be done first on the last added device, then on one before
last and so on.

Signed-off-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarLee Jones <lee.jones@linaro.org>
parent 2e0fed7f

drivers/base/core.c

+43 −0
Original line number Diff line number Diff line
@@ -1252,6 +1252,19 @@ void device_unregister(struct device *dev) 
}

EXPORT_SYMBOL_GPL(device_unregister);



static struct device *prev_device(struct klist_iter *i)

{

	struct klist_node *n = klist_prev(i);

	struct device *dev = NULL;

	struct device_private *p;



	if (n) {

		p = to_device_private_parent(n);

		dev = p->device;

	}

	return dev;

}



static struct device *next_device(struct klist_iter *i)

{

	struct klist_node *n = klist_next(i);
@@ -1340,6 +1353,36 @@ int device_for_each_child(struct device *parent, void *data, 
}

EXPORT_SYMBOL_GPL(device_for_each_child);



/**

 * device_for_each_child_reverse - device child iterator in reversed order.

 * @parent: parent struct device.

 * @fn: function to be called for each device.

 * @data: data for the callback.

 *

 * Iterate over @parent's child devices, and call @fn for each,

 * passing it @data.

 *

 * We check the return of @fn each time. If it returns anything

 * other than 0, we break out and return that value.

 */

int device_for_each_child_reverse(struct device *parent, void *data,

				  int (*fn)(struct device *dev, void *data))

{

	struct klist_iter i;

	struct device *child;

	int error = 0;



	if (!parent->p)

		return 0;



	klist_iter_init(&parent->p->klist_children, &i);

	while ((child = prev_device(&i)) && !error)

		error = fn(child, data);

	klist_iter_exit(&i);

	return error;

}

EXPORT_SYMBOL_GPL(device_for_each_child_reverse);



/**

 * device_find_child - device iterator for locating a particular device.

 * @parent: parent struct device

include/linux/device.h

+2 −0
Original line number Diff line number Diff line
@@ -958,6 +958,8 @@ extern int __must_check device_add(struct device *dev); 
extern void device_del(struct device *dev);

extern int device_for_each_child(struct device *dev, void *data,

		     int (*fn)(struct device *dev, void *data));

extern int device_for_each_child_reverse(struct device *dev, void *data,

		     int (*fn)(struct device *dev, void *data));

extern struct device *device_find_child(struct device *dev, void *data,

				int (*match)(struct device *dev, void *data));

extern int device_rename(struct device *dev, const char *new_name);