linux-kernel - [PATCH 05/18] software_node: Alter software_node_unregister_nodes() to unregister the array in reverse order

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Message-Id: <20201130133129.1024662-6-djrscally@gmail.com>
Date:   Mon, 30 Nov 2020 13:31:16 +0000
From:   Daniel Scally <djrscally@...il.com>
To:     linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
        linux-gpio@...r.kernel.org, linux-i2c@...r.kernel.org,
        linux-media@...r.kernel.org, devel@...ica.org
Cc:     rjw@...ysocki.net, lenb@...nel.org, gregkh@...uxfoundation.org,
        mika.westerberg@...ux.intel.com, andriy.shevchenko@...ux.intel.com,
        linus.walleij@...aro.org, bgolaszewski@...libre.com,
        wsa@...nel.org, yong.zhi@...el.com, sakari.ailus@...ux.intel.com,
        bingbu.cao@...el.com, tian.shu.qiu@...el.com, mchehab@...nel.org,
        robert.moore@...el.com, erik.kaneda@...el.com, pmladek@...e.com,
        rostedt@...dmis.org, sergey.senozhatsky@...il.com,
        linux@...musvillemoes.dk, kieran.bingham+renesas@...asonboard.com,
        jacopo+renesas@...ndi.org,
        laurent.pinchart+renesas@...asonboard.com,
        jorhand@...ux.microsoft.com, kitakar@...il.com,
        heikki.krogerus@...ux.intel.com
Subject: [PATCH 05/18] software_node: Alter software_node_unregister_nodes() to unregister the array in reverse order

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
this function unregisters software_nodes.

Suggested-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Signed-off-by: Daniel Scally <djrscally@...il.com>
---
Changes since RFC v3:

	Switched this functionality from a new function to replacing
	the existing software_nodes_unregister_nodes()

 drivers/base/swnode.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c
index af7930b3679e..d39e1c76d98d 100644
--- a/drivers/base/swnode.c
+++ b/drivers/base/swnode.c
@@ -720,20 +720,25 @@ 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
+ * @nodes: Zero terminated array of software nodes to be unregistered. 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.
  *
  * Unregister multiple software nodes at once.
  *
- * 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);
-- 
2.25.1