2 files changed, 82 insertions, 15 deletions

diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 4f5047df8a9e..3b6e2c9fbb2e 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -1059,7 +1059,15 @@ struct ctl_table_header
         struct completion *unregistering;
 };
 
+/* struct ctl_path describes where in the hierarchy a table is added */
+struct ctl_path {
+        const char *procname;
+        int ctl_name;
+};
+
 struct ctl_table_header *register_sysctl_table(struct ctl_table * table);
+struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
+                                                struct ctl_table *table);
 
 void unregister_sysctl_table(struct ctl_table_header * table);
 int sysctl_check_table(struct ctl_table *table);
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 8e96558cb8f3..f580542333eb 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1561,11 +1561,12 @@ static __init int sysctl_init(void)
 core_initcall(sysctl_init);
 
 /**
- * register_sysctl_table - register a sysctl hierarchy
+ * register_sysctl_paths - register a sysctl hierarchy
+ * @path: The path to the directory the sysctl table is in.
  * @table: the top-level table structure
  *
  * Register a sysctl table hierarchy. @table should be a filled in ctl_table
- * array. An entry with a ctl_name of 0 terminates the table. 
+ * array. A completely 0 filled entry terminates the table.
  *
  * The members of the &struct ctl_table structure are used as follows:
  *
@@ -1628,25 +1629,76 @@ core_initcall(sysctl_init);
  * This routine returns %NULL on a failure to register, and a pointer
  * to the table header on success.
  */
-struct ctl_table_header *register_sysctl_table(struct ctl_table * table)
+struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
+                                                struct ctl_table *table)
 {
-        struct ctl_table_header *tmp;
-        tmp = kmalloc(sizeof(struct ctl_table_header), GFP_KERNEL);
-        if (!tmp)
+        struct ctl_table_header *header;
+        struct ctl_table *new, **prevp;
+        unsigned int n, npath;
+
+        /* Count the path components */
+        for (npath = 0; path[npath].ctl_name || path[npath].procname; ++npath)
+                ;
+
+        /*
+         * For each path component, allocate a 2-element ctl_table array.
+         * The first array element will be filled with the sysctl entry
+         * for this, the second will be the sentinel (ctl_name == 0).
+         *
+         * We allocate everything in one go so that we don't have to
+         * worry about freeing additional memory in unregister_sysctl_table.
+         */
+        header = kzalloc(sizeof(struct ctl_table_header) +
+                         (2 * npath * sizeof(struct ctl_table)), GFP_KERNEL);
+        if (!header)
                 return NULL;
-        tmp->ctl_table = table;
-        INIT_LIST_HEAD(&tmp->ctl_entry);
-        tmp->used = 0;
-        tmp->unregistering = NULL;
-        sysctl_set_parent(NULL, table);
-        if (sysctl_check_table(tmp->ctl_table)) {
-                kfree(tmp);
+
+        new = (struct ctl_table *) (header + 1);
+
+        /* Now connect the dots */
+        prevp = &header->ctl_table;
+        for (n = 0; n < npath; ++n, ++path) {
+                /* Copy the procname */
+                new->procname = path->procname;
+                new->ctl_name = path->ctl_name;
+                new->mode     = 0555;
+
+                *prevp = new;
+                prevp = &new->child;
+
+                new += 2;
+        }
+        *prevp = table;
+
+        INIT_LIST_HEAD(&header->ctl_entry);
+        header->used = 0;
+        header->unregistering = NULL;
+        sysctl_set_parent(NULL, header->ctl_table);
+        if (sysctl_check_table(header->ctl_table)) {
+                kfree(header);
                 return NULL;
         }
         spin_lock(&sysctl_lock);
-        list_add_tail(&tmp->ctl_entry, &root_table_header.ctl_entry);
+        list_add_tail(&header->ctl_entry, &root_table_header.ctl_entry);
         spin_unlock(&sysctl_lock);
-        return tmp;
+
+        return header;
+}
+
+/**
+ * register_sysctl_table - register a sysctl table hierarchy
+ * @table: the top-level table structure
+ *
+ * Register a sysctl table hierarchy. @table should be a filled in ctl_table
+ * array. A completely 0 filled entry terminates the table.
+ *
+ * See register_sysctl_paths for more details.
+ */
+struct ctl_table_header *register_sysctl_table(struct ctl_table *table)
+{
+        static const struct ctl_path null_path[] = { {} };
+
+        return register_sysctl_paths(null_path, table);
 }
 
 /**
@@ -1675,6 +1727,12 @@ struct ctl_table_header *register_sysctl_table(struct ctl_table * table)
         return NULL;
 }
 
+struct ctl_table_header *register_sysctl_paths(const struct ctl_path *path,
+                                                    struct ctl_table *table)
+{
+        return NULL;
+}
+
 void unregister_sysctl_table(struct ctl_table_header * table)
 {
 }
@@ -2733,6 +2791,7 @@ EXPORT_SYMBOL(proc_dostring);
 EXPORT_SYMBOL(proc_doulongvec_minmax);
 EXPORT_SYMBOL(proc_doulongvec_ms_jiffies_minmax);
 EXPORT_SYMBOL(register_sysctl_table);
+EXPORT_SYMBOL(register_sysctl_paths);
 EXPORT_SYMBOL(sysctl_intvec);
 EXPORT_SYMBOL(sysctl_jiffies);
 EXPORT_SYMBOL(sysctl_ms_jiffies);