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Commit 36156f92 authored by Johan Hovold's avatar Johan Hovold Committed by Rob Herring
Browse files

of: add helper to lookup compatible child node 



Add of_get_compatible_child() helper that can be used to lookup
compatible child nodes.

Several drivers currently use of_find_compatible_node() to lookup child
nodes while failing to notice that the of_find_ functions search the
entire tree depth-first (from a given start node) and therefore can
match unrelated nodes. The fact that these functions also drop a
reference to the node they start searching from (e.g. the parent node)
is typically also overlooked, something which can lead to use-after-free
bugs.

Signed-off-by: default avatarJohan Hovold <johan@kernel.org>
Signed-off-by: default avatarRob Herring <robh@kernel.org>
parent 5b394b2d

drivers/of/base.c

+25 −0
Original line number Diff line number Diff line
@@ -719,6 +719,31 @@ struct device_node *of_get_next_available_child(const struct device_node *node, 
}

EXPORT_SYMBOL(of_get_next_available_child);



/**

 * of_get_compatible_child - Find compatible child node

 * @parent:	parent node

 * @compatible:	compatible string

 *

 * Lookup child node whose compatible property contains the given compatible

 * string.

 *

 * Returns a node pointer with refcount incremented, use of_node_put() on it

 * when done; or NULL if not found.

 */

struct device_node *of_get_compatible_child(const struct device_node *parent,

				const char *compatible)

{

	struct device_node *child;



	for_each_child_of_node(parent, child) {

		if (of_device_is_compatible(child, compatible))

			break;

	}



	return child;

}

EXPORT_SYMBOL(of_get_compatible_child);



/**

 *	of_get_child_by_name - Find the child node by name for a given parent

 *	@node:	parent node

include/linux/of.h

+8 −0
Original line number Diff line number Diff line
@@ -290,6 +290,8 @@ extern struct device_node *of_get_next_child(const struct device_node *node, 
extern struct device_node *of_get_next_available_child(

	const struct device_node *node, struct device_node *prev);



extern struct device_node *of_get_compatible_child(const struct device_node *parent,

					const char *compatible);

extern struct device_node *of_get_child_by_name(const struct device_node *node,

					const char *name);
@@ -632,6 +634,12 @@ static inline bool of_have_populated_dt(void) 
	return false;

}



static inline struct device_node *of_get_compatible_child(const struct device_node *parent,

					const char *compatible)

{

	return NULL;

}



static inline struct device_node *of_get_child_by_name(

					const struct device_node *node,

					const char *name)