[PATCH 1/3] of: dynamic: add of_property_alloc() and of_property_free()

[Clément Léger]

Add function which allows to dynamically allocate and free properties.
Use this function internally for all code that used the same logic
(mainly __of_prop_dup()).

Signed-off-by: Clément Léger <clement.leger at bootlin.com>
---
 drivers/of/dynamic.c | 101 ++++++++++++++++++++++++++++++-------------
 include/linux/of.h   |  16 +++++++
 2 files changed, 88 insertions(+), 29 deletions(-)

diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c
index cd3821a6444f..e8700e509d2e 100644
--- a/drivers/of/dynamic.c
+++ b/drivers/of/dynamic.c
@@ -313,9 +313,7 @@ static void property_list_free(struct property *prop_list)
 
 	for (prop = prop_list; prop != NULL; prop = next) {
 		next = prop->next;
-		kfree(prop->name);
-		kfree(prop->value);
-		kfree(prop);
+		of_property_free(prop);
 	}
 }
 
@@ -367,48 +365,95 @@ void of_node_release(struct kobject *kobj)
 }
 
 /**
- * __of_prop_dup - Copy a property dynamically.
- * @prop:	Property to copy
+ * of_property_free - Free a property allocated dynamically.
+ * @prop:	Property to be freed
+ */
+void of_property_free(const struct property *prop)
+{
+	kfree(prop->value);
+	kfree(prop->name);
+	kfree(prop);
+}
+EXPORT_SYMBOL(of_property_free);
+
+/**
+ * of_property_alloc - Allocate a property dynamically.
+ * @name:	Name of the new property
+ * @value:	Value that will be copied into the new property value
+ * @value_len:	length of @value to be copied into the new property value
+ * @len:	Length of new property value, must be greater than @value_len
  * @allocflags:	Allocation flags (typically pass GFP_KERNEL)
  *
- * Copy a property by dynamically allocating the memory of both the
+ * Create a property by dynamically allocating the memory of both the
  * property structure and the property name & contents. The property's
  * flags have the OF_DYNAMIC bit set so that we can differentiate between
  * dynamically allocated properties and not.
  *
  * Return: The newly allocated property or NULL on out of memory error.
  */
-struct property *__of_prop_dup(const struct property *prop, gfp_t allocflags)
+struct property *of_property_alloc(const char *name, const void *value,
+				   int value_len, int len, gfp_t allocflags)
 {
-	struct property *new;
+	int alloc_len = len;
+	struct property *prop;
+
+	if (len < value_len)
+		return NULL;
 
-	new = kzalloc(sizeof(*new), allocflags);
-	if (!new)
+	prop = kzalloc(sizeof(*prop), allocflags);
+	if (!prop)
 		return NULL;
 
+	prop->name = kstrdup(name, allocflags);
+	if (!prop->name)
+		goto out_err;
+
 	/*
-	 * NOTE: There is no check for zero length value.
-	 * In case of a boolean property, this will allocate a value
-	 * of zero bytes. We do this to work around the use
-	 * of of_get_property() calls on boolean values.
+	 * Even if the property has no value, it must be set to a
+	 * non-null value since of_get_property() is used to check
+	 * some values that might or not have a values (ranges for
+	 * instance). Moreover, when the node is released, prop->value
+	 * is kfreed so the memory must come from kmalloc.
 	 */
-	new->name = kstrdup(prop->name, allocflags);
-	new->value = kmemdup(prop->value, prop->length, allocflags);
-	new->length = prop->length;
-	if (!new->name || !new->value)
-		goto err_free;
+	if (!alloc_len)
+		alloc_len = 1;
 
-	/* mark the property as dynamic */
-	of_property_set_flag(new, OF_DYNAMIC);
+	prop->value = kzalloc(alloc_len, allocflags);
+	if (!prop->value)
+		goto out_err;
 
-	return new;
+	if (value)
+		memcpy(prop->value, value, value_len);
+
+	prop->length = len;
+	of_property_set_flag(prop, OF_DYNAMIC);
+
+	return prop;
+
+out_err:
+	of_property_free(prop);
 
- err_free:
-	kfree(new->name);
-	kfree(new->value);
-	kfree(new);
 	return NULL;
 }
+EXPORT_SYMBOL(of_property_alloc);
+
+/**
+ * __of_prop_dup - Copy a property dynamically.
+ * @prop:	Property to copy
+ * @allocflags:	Allocation flags (typically pass GFP_KERNEL)
+ *
+ * Copy a property by dynamically allocating the memory of both the
+ * property structure and the property name & contents. The property's
+ * flags have the OF_DYNAMIC bit set so that we can differentiate between
+ * dynamically allocated properties and not.
+ *
+ * Return: The newly allocated property or NULL on out of memory error.
+ */
+struct property *__of_prop_dup(const struct property *prop, gfp_t allocflags)
+{
+	return of_property_alloc(prop->name, prop->value, prop->length,
+				 prop->length, allocflags);
+}
 
 /**
  * __of_node_dup() - Duplicate or create an empty device node dynamically.
@@ -447,9 +492,7 @@ struct device_node *__of_node_dup(const struct device_node *np,
 			if (!new_pp)
 				goto err_prop;
 			if (__of_add_property(node, new_pp)) {
-				kfree(new_pp->name);
-				kfree(new_pp->value);
-				kfree(new_pp);
+				of_property_free(new_pp);
 				goto err_prop;
 			}
 		}
diff --git a/include/linux/of.h b/include/linux/of.h
index 04971e85fbc9..6b345eb71c19 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -1463,6 +1463,11 @@ enum of_reconfig_change {
 };
 
 #ifdef CONFIG_OF_DYNAMIC
+extern struct property *of_property_alloc(const char *name, const void *value,
+					  int value_len, int len,
+					  gfp_t allocflags);
+extern void of_property_free(const struct property *prop);
+
 extern int of_reconfig_notifier_register(struct notifier_block *);
 extern int of_reconfig_notifier_unregister(struct notifier_block *);
 extern int of_reconfig_notify(unsigned long, struct of_reconfig_data *rd);
@@ -1507,6 +1512,17 @@ static inline int of_changeset_update_property(struct of_changeset *ocs,
 	return of_changeset_action(ocs, OF_RECONFIG_UPDATE_PROPERTY, np, prop);
 }
 #else /* CONFIG_OF_DYNAMIC */
+
+static inline struct property *of_property_alloc(const char *name,
+						 const void *value,
+						 int value_len, int len,
+						 gfp_t allocflags)
+{
+	return NULL;
+}
+
+static inline  void of_property_free(const struct property *prop) {}
+
 static inline int of_reconfig_notifier_register(struct notifier_block *nb)
 {
 	return -EINVAL;
-- 
2.34.1