| From 9f914aeae99f53e7cbecbf997ad58f4dd07619c5 Mon Sep 17 00:00:00 2001 |
| From: Johan Hovold <johan@kernel.org> |
| Date: Mon, 27 Aug 2018 10:21:45 +0200 |
| Subject: of: add helper to lookup compatible child node |
| |
| [ Upstream commit 36156f9241cb0f9e37d998052873ca7501ad4b36 ] |
| |
| 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> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| drivers/of/base.c | 25 +++++++++++++++++++++++++ |
| include/linux/of.h | 8 ++++++++ |
| 2 files changed, 33 insertions(+) |
| |
| diff --git a/drivers/of/base.c b/drivers/of/base.c |
| index 31341290cd91..c6e019208d17 100644 |
| --- a/drivers/of/base.c |
| +++ b/drivers/of/base.c |
| @@ -712,6 +712,31 @@ 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 |
| diff --git a/include/linux/of.h b/include/linux/of.h |
| index dd10626a615f..d9371c9cd88a 100644 |
| --- a/include/linux/of.h |
| +++ b/include/linux/of.h |
| @@ -265,6 +265,8 @@ 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); |
| |
| @@ -462,6 +464,12 @@ 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) |
| -- |
| 2.17.1 |
| |