From 36156f9241cb0f9e37d998052873ca7501ad4b36 Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Mon, 27 Aug 2018 10:21:45 +0200 Subject: [PATCH 1/3] 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 Signed-off-by: Rob Herring --- 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 466e3c8582f0..bc420d2aa5f5 100644 --- a/drivers/of/base.c +++ b/drivers/of/base.c @@ -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 diff --git a/include/linux/of.h b/include/linux/of.h index 4d25e4f952d9..b99a1a8c2952 100644 --- a/include/linux/of.h +++ b/include/linux/of.h @@ -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) From f42b0e18f2e5cf34f73ef1b6327b49040b307a33 Mon Sep 17 00:00:00 2001 From: Rob Herring Date: Mon, 27 Aug 2018 07:50:47 -0500 Subject: [PATCH 2/3] of: add node name compare helper functions In preparation to remove device_node.name pointer, add helper functions for node name comparisons which are a common pattern throughout the kernel. Cc: Frank Rowand Signed-off-by: Rob Herring --- drivers/of/base.c | 22 ++++++++++++++++++++++ include/linux/of.h | 13 +++++++++++++ 2 files changed, 35 insertions(+) diff --git a/drivers/of/base.c b/drivers/of/base.c index bc420d2aa5f5..9095b8290150 100644 --- a/drivers/of/base.c +++ b/drivers/of/base.c @@ -54,6 +54,28 @@ DEFINE_MUTEX(of_mutex); */ DEFINE_RAW_SPINLOCK(devtree_lock); +bool of_node_name_eq(const struct device_node *np, const char *name) +{ + const char *node_name; + size_t len; + + if (!np) + return false; + + node_name = kbasename(np->full_name); + len = strchrnul(node_name, '@') - node_name; + + return (strlen(name) == len) && (strncmp(node_name, name, len) == 0); +} + +bool of_node_name_prefix(const struct device_node *np, const char *prefix) +{ + if (!np) + return false; + + return strncmp(kbasename(np->full_name), prefix, strlen(prefix)) == 0; +} + int of_n_addr_cells(struct device_node *np) { u32 cells; diff --git a/include/linux/of.h b/include/linux/of.h index b99a1a8c2952..688c52dd7b3e 100644 --- a/include/linux/of.h +++ b/include/linux/of.h @@ -256,6 +256,9 @@ static inline unsigned long of_read_ulong(const __be32 *cell, int size) #define OF_IS_DYNAMIC(x) test_bit(OF_DYNAMIC, &x->_flags) #define OF_MARK_DYNAMIC(x) set_bit(OF_DYNAMIC, &x->_flags) +extern bool of_node_name_eq(const struct device_node *np, const char *name); +extern bool of_node_name_prefix(const struct device_node *np, const char *prefix); + static inline const char *of_node_full_name(const struct device_node *np) { return np ? np->full_name : ""; @@ -563,6 +566,16 @@ static inline struct device_node *to_of_node(const struct fwnode_handle *fwnode) return NULL; } +static inline bool of_node_name_eq(const struct device_node *np, const char *name) +{ + return false; +} + +static inline bool of_node_name_prefix(const struct device_node *np, const char *prefix) +{ + return false; +} + static inline const char* of_node_full_name(const struct device_node *np) { return ""; From 0413bedabc886c3a56804d1c80a58e99077b1d91 Mon Sep 17 00:00:00 2001 From: Rob Herring Date: Tue, 28 Aug 2018 15:10:48 -0500 Subject: [PATCH 3/3] of: Add device_type access helper functions In preparation to remove direct access to device_node.type, add of_node_is_type() and of_node_get_device_type() helpers to check and retrieve the device type. Cc: Frank Rowand Signed-off-by: Rob Herring --- include/linux/of.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/include/linux/of.h b/include/linux/of.h index 688c52dd7b3e..99b0ebf49632 100644 --- a/include/linux/of.h +++ b/include/linux/of.h @@ -988,6 +988,18 @@ static inline struct device_node *of_find_matching_node( return of_find_matching_node_and_match(from, matches, NULL); } +static inline const char *of_node_get_device_type(const struct device_node *np) +{ + return of_get_property(np, "type", NULL); +} + +static inline bool of_node_is_type(const struct device_node *np, const char *type) +{ + const char *match = of_node_get_device_type(np); + + return np && match && type && !strcmp(match, type); +} + /** * of_property_count_u8_elems - Count the number of u8 elements in a property *