sysctl: Remove the unnecessary sysctl_set parent concept.

In sysctl_net register the two networking roots in the proper order.

In register_sysctl walk the sysctl sets in the reverse order of the
sysctl roots.

Remove parent from ctl_table_set and setup_sysctl_set as it is no
longer needed.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

fs/proc/proc_sysctl.c

@@ -995,13 +995,20 @@ struct ctl_table_header *__register_sysctl_paths(
 	header->attached_by = header->ctl_table;
 	header->attached_to = root_table;
 	header->parent = &root_table_header;
-	for (set = header->set; set; set = set->parent) {
+	set = header->set;
+	root = header->root;
+	for (;;) {
 		struct ctl_table_header *p;
 		list_for_each_entry(p, &set->list, ctl_entry) {
 			if (p->unregistering)
 				continue;
 			try_attach(p, header);
 		}
+		if (root == &sysctl_table_root)
+			break;
+		root = list_entry(root->root_list.prev,
+				  struct ctl_table_root, root_list);
+		set = lookup_header_set(root, namespaces);
 	}
 	header->parent->count++;
 	list_add_tail(&header->ctl_entry, &header->set->list);
@@ -1072,11 +1079,9 @@ void unregister_sysctl_table(struct ctl_table_header * header)
 EXPORT_SYMBOL(unregister_sysctl_table);
 
 void setup_sysctl_set(struct ctl_table_set *p,
-	struct ctl_table_set *parent,
 	int (*is_seen)(struct ctl_table_set *))
 {
 	INIT_LIST_HEAD(&p->list);
-	p->parent = parent ? parent : &sysctl_table_root.default_set;
 	p->is_seen = is_seen;
 }
 

include/linux/sysctl.h

@@ -1047,7 +1047,6 @@ struct ctl_table_header
 
 struct ctl_table_set {
 	struct list_head list;
-	struct ctl_table_set *parent;
 	int (*is_seen)(struct ctl_table_set *);
 };
 
@@ -1070,7 +1069,6 @@ struct ctl_path {
 void proc_sys_poll_notify(struct ctl_table_poll *poll);
 
 extern void setup_sysctl_set(struct ctl_table_set *p,
-	struct ctl_table_set *parent,
 	int (*is_seen)(struct ctl_table_set *));
 extern void retire_sysctl_set(struct ctl_table_set *set);
 
@@ -1102,7 +1100,6 @@ static inline void unregister_sysctl_table(struct ctl_table_header * table)
 }
 
 static inline void setup_sysctl_set(struct ctl_table_set *p,
-	struct ctl_table_set *parent,
 	int (*is_seen)(struct ctl_table_set *))
 {
 }

net/sysctl_net.c

@@ -75,7 +75,6 @@ static struct ctl_table_root net_sysctl_ro_root = {
 static int __net_init sysctl_net_init(struct net *net)
 {
 	setup_sysctl_set(&net->sysctls,
-			 &net_sysctl_ro_root.default_set,
 			 is_seen);
 	return 0;
 }
@@ -96,9 +95,9 @@ static __init int net_sysctl_init(void)
 	ret = register_pernet_subsys(&sysctl_pernet_ops);
 	if (ret)
 		goto out;
-	register_sysctl_root(&net_sysctl_root);
-	setup_sysctl_set(&net_sysctl_ro_root.default_set, NULL, NULL);
+	setup_sysctl_set(&net_sysctl_ro_root.default_set, NULL);
 	register_sysctl_root(&net_sysctl_ro_root);
+	register_sysctl_root(&net_sysctl_root);
 out:
 	return ret;
 }