sysctl: Add size arg to __register_sysctl_init

This commit adds table_size to __register_sysctl_init in preparation for
the removal of the sentinel elements in the ctl_table arrays (last empty
markers). And though we do *not* remove any sentinels in this commit, we
set things up by calculating the ctl_table array size with ARRAY_SIZE.

We add a table_size argument to __register_sysctl_init and modify the
register_sysctl_init macro to calculate the array size with ARRAY_SIZE.
The original callers do not need to be updated as they will go through
the new macro.

Signed-off-by: Joel Granados <[email protected]>
Suggested-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Luis Chamberlain <[email protected]>

Author: Joelgranados

fs/proc/proc_sysctl.c

@@ -1433,6 +1433,7 @@ EXPORT_SYMBOL(register_sysctl_sz);
  * 	lifetime use of the sysctl.
  * @table_name: The name of sysctl table, only used for log printing when
  *              registration fails
+ * @table_size: The number of elements in table
  *
  * The sysctl interface is used by userspace to query or modify at runtime
  * a predefined value set on a variable. These variables however have default
@@ -1445,16 +1446,9 @@ EXPORT_SYMBOL(register_sysctl_sz);
  * Context: if your base directory does not exist it will be created for you.
  */
 void __init __register_sysctl_init(const char *path, struct ctl_table *table,
-				 const char *table_name)
+				 const char *table_name, size_t table_size)
 {
-	int count = 0;
-	struct ctl_table *entry;
-	struct ctl_table_header t_hdr, *hdr;
-
-	t_hdr.ctl_table = table;
-	list_for_each_table_entry(entry, (&t_hdr))
-		count++;
-	hdr = register_sysctl_sz(path, table, count);
+	struct ctl_table_header *hdr = register_sysctl_sz(path, table, table_size);
 
 	if (unlikely(!hdr)) {
 		pr_err("failed when register_sysctl_sz %s to %s\n", table_name, path);

include/linux/sysctl.h

@@ -236,8 +236,9 @@ void unregister_sysctl_table(struct ctl_table_header * table);
 
 extern int sysctl_init_bases(void);
 extern void __register_sysctl_init(const char *path, struct ctl_table *table,
-				 const char *table_name);
-#define register_sysctl_init(path, table) __register_sysctl_init(path, table, #table)
+				 const char *table_name, size_t table_size);
+#define register_sysctl_init(path, table)	\
+	__register_sysctl_init(path, table, #table, ARRAY_SIZE(table))
 extern struct ctl_table_header *register_sysctl_mount_point(const char *path);
 
 void do_sysctl_args(void);