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authorJohan Hovold <johan@kernel.org>2018-08-27 10:21:45 +0200
committerRob Herring <robh@kernel.org>2018-08-29 08:06:46 -0500
commit36156f9241cb0f9e37d998052873ca7501ad4b36 (patch)
tree203d1e52a9e5a942a2b99ae0ecb984fa87453df8 /drivers/of
parent5b394b2ddf0347bef56e50c69a58773c94343ff3 (diff)
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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: Johan Hovold <johan@kernel.org> Signed-off-by: Rob Herring <robh@kernel.org>
Diffstat (limited to 'drivers/of')
-rw-r--r--drivers/of/base.c25
1 files changed, 25 insertions, 0 deletions
diff --git a/drivers/of/base.c b/drivers/of/base.c
index 466e3c8582f0..bc420d2aa5f5 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -720,6 +720,31 @@ 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
* @name: child name to look for.