[PATCH] sysctl: add a parent entry to ctl_table and set the parent entry

Add a parent entry into the ctl_table so you can walk the list of parents and
find the entire path to a ctl_table entry.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 19 insertions, 0 deletions

diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 89150494bd10..1371d7b86810 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -1022,6 +1022,7 @@ struct ctl_table
         int maxlen;
         mode_t mode;
         ctl_table *child;
+        ctl_table *parent;              /* Automatically set */
         proc_handler *proc_handler;     /* Callback for text formatting */
         ctl_handler *strategy;          /* Callback function for all r/w */
         struct proc_dir_entry *de;      /* /proc control block */
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index b3ee791ad663..3ca1d5ff0319 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1240,6 +1240,23 @@ int do_sysctl_strategy (ctl_table *table,
 }
 #endif /* CONFIG_SYSCTL_SYSCALL */
 
+static void sysctl_set_parent(struct ctl_table *parent, struct ctl_table *table)
+{
+        for (; table->ctl_name || table->procname; table++) {
+                table->parent = parent;
+                if (table->child)
+                        sysctl_set_parent(table, table->child);
+        }
+}
+
+static __init int sysctl_init(void)
+{
+        sysctl_set_parent(NULL, root_table);
+        return 0;
+}
+
+core_initcall(sysctl_init);
+
 /**
  * register_sysctl_table - register a sysctl hierarchy
  * @table: the top-level table structure
@@ -1318,6 +1335,7 @@ struct ctl_table_header *register_sysctl_table(ctl_table * table)
         INIT_LIST_HEAD(&tmp->ctl_entry);
         tmp->used = 0;
         tmp->unregistering = NULL;
+        sysctl_set_parent(NULL, table);
         spin_lock(&sysctl_lock);
         list_add_tail(&tmp->ctl_entry, &root_table_header.ctl_entry);
         spin_unlock(&sysctl_lock);