[PATCH RFC v2 06/13] sysctl, net: add register_net_sysctl{_sz}() wrappers for MODULE_SYSCTL_TABLE

[Mauricio Faria de Oliveira <mfo@igalia.com>]

Add a MODULE_SYSCTL_TABLE call into register_net_sysctl{_sz}() for existing
callers to automatically use it.

Add optional 'template arguments' to support a dynamic table/path defined
at run-time based on a 'template' available at build-time.

Split the update of callers with template arguments into separate commits,
disabling the macro for now.

Signed-off-by: Mauricio Faria de Oliveira <mfo@igalia.com>
---
 include/linux/sysctl.h      |  3 +++
 include/net/net_namespace.h | 45 ++++++++++++++++++++++++++++++++++++++++-----
 net/sysctl_net.c            | 10 +++++-----
 3 files changed, 48 insertions(+), 10 deletions(-)

diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 7e05fafd5544e1c4a3283dc13b0692f39515d01e..9e00a086ff1d47ab18021b3d79b0e8a93037cb2d 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -309,6 +309,9 @@ struct ctl_table_root {
  *
  * Define the macro SYSCTL_MODULE_ALIASES_DISABLE to disable this.
  */
+
+#define SYSCTL_MODULE_ALIASES_DISABLE
+
 #if defined(CONFIG_SYSCTL_MODULE_ALIASES) && defined(MODULE) &&			\
     !defined(SYSCTL_MODULE_ALIASES_DISABLE)
 
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index e5ee673b9fcf846aefcc309d4cca1a8fc870aae2..2127049c71cedade45922d7f0d3b7a3ce0af67e0 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -520,13 +520,48 @@ void unregister_pernet_device(struct pernet_operations *);
 
 struct ctl_table;
 
-#define register_net_sysctl(net, path, table)	\
-	register_net_sysctl_sz(net, path, table, ARRAY_SIZE(table))
+/*
+ * The register_net_sysctl{_sz}() wrappers for MODULE_SYSCTL_TABLE
+ * automatically create symbols in sysctl registration sites.
+ *
+ * See register_sysctl() and MODULE_SYSCTL_TABLE() in <linux/sysctl.h>
+ * for information about template arguments and options for the macro.
+ *
+ * Usage:
+ * - register_net_sysctl(net, path, table);
+ * - register_net_sysctl(net, path, table, table_tmpl);
+ * - register_net_sysctl(net, path, table, table_tmpl, path_tmpl);
+ * - register_net_sysctl_sz(net, path, table, size);
+ * - register_net_sysctl_sz(net, path, table, size, table_tmpl);
+ * - register_net_sysctl_sz(net, path, table, size, table_tmpl, path_tmpl);
+ */
+#define _register_net_sysctl_sz(net, path, table, size, table_tmpl, path_tmpl)	\
+({										\
+	MODULE_SYSCTL_TABLE(path_tmpl, table_tmpl);				\
+	__register_net_sysctl_sz(net, path, table, size);			\
+})
+
+#define register_net_sysctl_sz(net, path, table, size, tmpl_args...)		\
+	_register_net_sysctl_sz(net, path, table, size,				\
+				__sysctl_table_tmpl_or_default(table,		\
+							       ## tmpl_args),	\
+				__sysctl_path_tmpl_or_default(path,		\
+							      ## tmpl_args))
+#define register_net_sysctl(net, path, table, tmpl_args...)			\
+	register_net_sysctl_sz(net, path, table,				\
+			       __sysctl_table_array_size(table, ## tmpl_args),	\
+			       ## tmpl_args)
+
+/* Helper macro for optional template arguments */
+#define __sysctl_table_array_size(table, tmpl_args...)	\
+	ARRAY_SIZE(__sysctl_table_tmpl_or_default(table, ## tmpl_args))
+
 #ifdef CONFIG_SYSCTL
 int net_sysctl_init(void);
-struct ctl_table_header *register_net_sysctl_sz(struct net *net, const char *path,
-						const struct ctl_table *table,
-						size_t table_size);
+struct ctl_table_header *__register_net_sysctl_sz(struct net *net,
+						  const char *path,
+						  const 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; }
diff --git a/net/sysctl_net.c b/net/sysctl_net.c
index e190a639eef2f6929c4aed85ad625aaf8a6ebd6a..e003210e0917760b707dae1e738c50d7c3969deb 100644
--- a/net/sysctl_net.c
+++ b/net/sysctl_net.c
@@ -160,10 +160,10 @@ static int ensure_safe_net_sysctl(struct net *net, const char *path,
 	return 0;
 }
 
-struct ctl_table_header *register_net_sysctl_sz(struct net *net,
-						const char *path,
-						const struct ctl_table *table,
-						size_t table_size)
+struct ctl_table_header *__register_net_sysctl_sz(struct net *net,
+						  const char *path,
+						  const struct ctl_table *table,
+						  size_t table_size)
 {
 	if (!net_eq(net, &init_net))
 		if (ensure_safe_net_sysctl(net, path, table, table_size))
@@ -171,7 +171,7 @@ struct ctl_table_header *register_net_sysctl_sz(struct net *net,
 
 	return __register_sysctl_table(&net->sysctls, path, table, table_size);
 }
-EXPORT_SYMBOL_GPL(register_net_sysctl_sz);
+EXPORT_SYMBOL_GPL(__register_net_sysctl_sz);
 
 void unregister_net_sysctl_table(struct ctl_table_header *header)
 {

-- 
2.47.3