sysctl: Add size to register_net_sysctl function

This commit adds size to the register_net_sysctl indirection function to
facilitate the removal of the sentinel elements (last empty markers)
from the ctl_table arrays. Though we don't actually remove any sentinels
in this commit, register_net_sysctl* now has the capability of
forwarding table_size for when that happens.

We create a new function register_net_sysctl_sz with an extra size
argument. A macro replaces the existing register_net_sysctl. The size in
the macro is SIZE_MAX instead of ARRAY_SIZE to avoid compilation errors
while we systematically migrate to register_net_sysctl_sz. Will change
to ARRAY_SIZE in subsequent commits.

Care is taken to add table_size to the stopping criteria in such a way
that when we remove the empty sentinel element, it will continue
stopping in the last element of the ctl_table array.

Signed-off-by: Joel Granados <j.granados@samsung.com>
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

1 files changed, 6 insertions, 4 deletions

diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index 78beaa765c73..e4e5fe75a281 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -469,15 +469,17 @@ void unregister_pernet_device(struct pernet_operations *);
 
 struct ctl_table;
 
+#define register_net_sysctl(net, path, table)	\
+	register_net_sysctl_sz(net, path, table, SIZE_MAX)
 #ifdef CONFIG_SYSCTL
 int net_sysctl_init(void);
-struct ctl_table_header *register_net_sysctl(struct net *net, const char *path,
-					     struct ctl_table *table);
+struct ctl_table_header *register_net_sysctl_sz(struct net *net, const char *path,
+					     struct ctl_table *table, size_t table_size);
 void unregister_net_sysctl_table(struct ctl_table_header *header);
 #else
 static inline int net_sysctl_init(void) { return 0; }
-static inline struct ctl_table_header *register_net_sysctl(struct net *net,
-	const char *path, struct ctl_table *table)
+static inline struct ctl_table_header *register_net_sysctl_sz(struct net *net,
+	const char *path, struct ctl_table *table, size_t table_size)
 {
 	return NULL;
 }