From d9b1103bc622b20498c1d2fb9c00805b9d6f2921 Mon Sep 17 00:00:00 2001 From: Daniel Scally Date: Thu, 7 Jan 2021 14:28:28 +0100 Subject: [PATCH] media: software_node: Enforce parent before child ordering of nodes arrays 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 Reviewed-by: Laurent Pinchart Signed-off-by: Daniel Scally Reviewed-by: Heikki Krogerus Acked-by: Greg Kroah-Hartman Acked-by: Rafael J. Wysocki Signed-off-by: Sakari Ailus Signed-off-by: Mauro Carvalho Chehab --- drivers/base/swnode.c | 42 ++++++++++++++++++++++++++++++------------ 1 file changed, 30 insertions(+), 12 deletions(-) diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c index 4fcc1a6..166c5cc 100644 --- a/drivers/base/swnode.c +++ b/drivers/base/swnode.c @@ -692,7 +692,11 @@ out_err: * 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); -- 2.7.4