linux-kernel - [PATCH 7/7] of: dynamic: add lifecycle docbook info to node creation functions

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Message-Id: <20230213185702.395776-8-frowand.list@gmail.com>
Date:   Mon, 13 Feb 2023 12:57:02 -0600
From:   Frank Rowand <frowand.list@...il.com>
To:     Rob Herring <robh+dt@...nel.org>
Cc:     devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 7/7] of: dynamic: add lifecycle docbook info to node creation functions

The existing docbook comments for the functions related to creating
a devicetree node do not explain the reference count of a newly
created node, how decrementing the reference count to zero will
free the associated memory, and the caller's responsibility to
call of_node_put() on the node.  Explain what happens when the
reference count is decremented to zero.

Signed-off-by: Frank Rowand <frowand.list@...il.com>
---
 drivers/of/dynamic.c |  3 ++-
 include/linux/of.h   | 11 +++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c
index 657a65006056..12aa99018969 100644
--- a/drivers/of/dynamic.c
+++ b/drivers/of/dynamic.c
@@ -443,7 +443,8 @@ struct property *__of_prop_dup(const struct property *prop, gfp_t allocflags)
  * another node.  The node data are dynamically allocated and all the node
  * flags have the OF_DYNAMIC & OF_DETACHED bits set.
  *
- * Return: The newly allocated node or NULL on out of memory error.
+ * Return: The newly allocated node or NULL on out of memory error.  Use
+ * of_node_put() on it when done to free the memory allocated for it.
  */
 struct device_node *__of_node_dup(const struct device_node *np,
 				  const char *full_name)
diff --git a/include/linux/of.h b/include/linux/of.h
index 8b9f94386dc3..e20a08c8a8c8 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -100,6 +100,17 @@ struct of_reconfig_data {
 	struct property		*old_prop;
 };
 
+/**
+ * of_node_init - initialize a devicetree node
+ * @node: Pointer to device node that has been created by kzalloc()
+ * @phandle_name: Name of property holding a phandle value
+ *
+ * On return the device_node refcount is set to one.  Use of_node_put()
+ * on @node when done to free the memory allocated for it.  If the node
+ * is NOT a dynamic node the memory will not be freed. The decision of
+ * whether to free the memory will be done by node->release(), which is
+ * of_node_release().
+ */
 /* initialize a node */
 extern struct kobj_type of_node_ktype;
 extern const struct fwnode_operations of_fwnode_ops;
-- 
Frank Rowand <frowand.list@...il.com>