From 36156f9241cb0f9e37d998052873ca7501ad4b36 Mon Sep 17 00:00:00 2001
From: Johan Hovold
Date: Mon, 27 Aug 2018 10:21:45 +0200
Subject: 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>
---
 drivers/of/base.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

(limited to 'drivers')

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
-- 
cgit v1.2.3


From f42b0e18f2e5cf34f73ef1b6327b49040b307a33 Mon Sep 17 00:00:00 2001
From: Rob Herring
Date: Mon, 27 Aug 2018 07:50:47 -0500
Subject: 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 <frowand.list@gmail.com>
Signed-off-by: Rob Herring <robh@kernel.org>
---
 drivers/of/base.c  | 22 ++++++++++++++++++++++
 include/linux/of.h | 13 +++++++++++++
 2 files changed, 35 insertions(+)

(limited to 'drivers')

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 : "<no-node>";
@@ -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 "<no-node>";
-- 
cgit v1.2.3