[Bridge] [PATCH v3 08/14] sysctl: Add size to register_net_sysctl function

[Joel Granados]

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.grana...@samsung.com>
Suggested-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 include/net/net_namespace.h | 10 ++++++----
 net/sysctl_net.c            | 22 +++++++++++++---------
 2 files changed, 19 insertions(+), 13 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;
 }
diff --git a/net/sysctl_net.c b/net/sysctl_net.c
index d9cbbb51b143..051ed5f6fc93 100644
--- a/net/sysctl_net.c
+++ b/net/sysctl_net.c
@@ -122,12 +122,13 @@ __init int net_sysctl_init(void)
  *    allocated.
  */
 static void ensure_safe_net_sysctl(struct net *net, const char *path,
-                                  struct ctl_table *table)
+                                  struct ctl_table *table, size_t table_size)
 {
        struct ctl_table *ent;
 
        pr_debug("Registering net sysctl (net %p): %s\n", net, path);
-       for (ent = table; ent->procname; ent++) {
+       ent = table;
+       for (size_t i = 0; i < table_size && ent->procname; ent++, i++) {
                unsigned long addr;
                const char *where;
 
@@ -160,21 +161,24 @@ static void ensure_safe_net_sysctl(struct net *net, const 
char *path,
        }
 }
 
-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)
 {
-       int count = 0;
+       int count;
        struct ctl_table *entry;
 
        if (!net_eq(net, &init_net))
-               ensure_safe_net_sysctl(net, path, table);
+               ensure_safe_net_sysctl(net, path, table, table_size);
 
-       for (entry = table; entry->procname; entry++)
-               count++;
+       entry = table;
+       for (count = 0 ; count < table_size && entry->procname; entry++, 
count++)
+               ;
 
        return __register_sysctl_table(&net->sysctls, path, table, count);
 }
-EXPORT_SYMBOL_GPL(register_net_sysctl);
+EXPORT_SYMBOL_GPL(register_net_sysctl_sz);
 
 void unregister_net_sysctl_table(struct ctl_table_header *header)
 {
-- 
2.30.2