diff mbox series

[v5,05/15] software_node: Enforce parent before child ordering of nodes arrays

Message ID 20210107132838.396641-6-djrscally@gmail.com
State Accepted
Commit d9b1103bc622b20498c1d2fb9c00805b9d6f2921
Headers show
Series None | expand

Commit Message

Daniel Scally Jan. 7, 2021, 1:28 p.m. UTC 
Registering software_nodes with the .parent member set to point to a
currently unregistered software_node has the potential for problems,
so enforce parent -> child ordering in arrays passed in to
software_node_register_nodes().

Software nodes that are children of another software node should be
unregistered before their parent. To allow easy unregistering of an array
of software_nodes ordered parent to child, reverse the order in which
software_node_unregister_nodes() unregisters software_nodes.

Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Daniel Scally <djrscally@gmail.com>
---
Changes in v5:

	- None

 drivers/base/swnode.c | 42 ++++++++++++++++++++++++++++++------------
 1 file changed, 30 insertions(+), 12 deletions(-)

Comments

Greg Kroah-Hartman Jan. 10, 2021, 3:09 p.m. UTC | #1 
On Thu, Jan 07, 2021 at 01:28:28PM +0000, Daniel Scally wrote:
> Registering software_nodes with the .parent member set to point to a

> currently unregistered software_node has the potential for problems,

> so enforce parent -> child ordering in arrays passed in to

> software_node_register_nodes().

> 

> Software nodes that are children of another software node should be

> unregistered before their parent. To allow easy unregistering of an array

> of software_nodes ordered parent to child, reverse the order in which

> software_node_unregister_nodes() unregisters software_nodes.

> 

> Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> Signed-off-by: Daniel Scally <djrscally@gmail.com>

> ---

> Changes in v5:

> 

> 	- None


Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff mbox series

Patch

diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c
index 4fcc1a6fb724..166c5cc73f39 100644
--- a/drivers/base/swnode.c
+++ b/drivers/base/swnode.c
@@ -692,7 +692,11 @@  swnode_register(const struct software_node *node, struct swnode *parent,
  * software_node_register_nodes - Register an array of software nodes
  * @nodes: Zero terminated array of software nodes to be registered
  *
- * Register multiple software nodes at once.
+ * Register multiple software nodes at once. If any node in the array
+ * has its .parent pointer set (which can only be to another software_node),
+ * then its parent **must** have been registered before it is; either outside
+ * of this function or by ordering the array such that parent comes before
+ * child.
  */
 int software_node_register_nodes(const struct software_node *nodes)
 {
@@ -700,14 +704,23 @@  int software_node_register_nodes(const struct software_node *nodes)
 	int i;
 
 	for (i = 0; nodes[i].name; i++) {
-		ret = software_node_register(&nodes[i]);
-		if (ret) {
-			software_node_unregister_nodes(nodes);
-			return ret;
+		const struct software_node *parent = nodes[i].parent;
+
+		if (parent && !software_node_to_swnode(parent)) {
+			ret = -EINVAL;
+			goto err_unregister_nodes;
 		}
+
+		ret = software_node_register(&nodes[i]);
+		if (ret)
+			goto err_unregister_nodes;
 	}
 
 	return 0;
+
+err_unregister_nodes:
+	software_node_unregister_nodes(nodes);
+	return ret;
 }
 EXPORT_SYMBOL_GPL(software_node_register_nodes);
 
@@ -715,18 +728,23 @@  EXPORT_SYMBOL_GPL(software_node_register_nodes);
  * software_node_unregister_nodes - Unregister an array of software nodes
  * @nodes: Zero terminated array of software nodes to be unregistered
  *
- * Unregister multiple software nodes at once.
+ * Unregister multiple software nodes at once. If parent pointers are set up
+ * in any of the software nodes then the array **must** be ordered such that
+ * parents come before their children.
  *
- * NOTE: Be careful using this call if the nodes had parent pointers set up in
- * them before registering.  If so, it is wiser to remove the nodes
- * individually, in the correct order (child before parent) instead of relying
- * on the sequential order of the list of nodes in the array.
+ * NOTE: If you are uncertain whether the array is ordered such that
+ * parents will be unregistered before their children, it is wiser to
+ * remove the nodes individually, in the correct order (child before
+ * parent).
  */
 void software_node_unregister_nodes(const struct software_node *nodes)
 {
-	int i;
+	unsigned int i = 0;
+
+	while (nodes[i].name)
+		i++;
 
-	for (i = 0; nodes[i].name; i++)
+	while (i--)
 		software_node_unregister(&nodes[i]);
 }
 EXPORT_SYMBOL_GPL(software_node_unregister_nodes);