net/ipv6/addrconf: simplify sysctl registration

Struct ctl_table_header holds pointer to sysctl table which could be used
for freeing it after unregistration. IPv4 sysctls already use that.
Remove redundant NULL assignment: ndev allocated using kzalloc.

This also saves some bytes: sysctl table could be shorter than
DEVCONF_MAX+1 if some options are disable in config.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 19 insertions, 27 deletions

diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index 7edc14fb66b6..58d6e158755f 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -63,7 +63,8 @@ struct ipv6_devconf {
         } stable_secret;
         __s32           use_oif_addrs_only;
         __s32           keep_addr_on_down;
-        void            *sysctl;
+
+        struct ctl_table_header *sysctl_header;
 };
 
 struct ipv6_params {
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index a6c99275bd8c..5a42c0fe0449 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -359,7 +359,6 @@ static struct inet6_dev *ipv6_add_dev(struct net_device *dev)
                 ndev->addr_gen_mode = IN6_ADDR_GEN_MODE_EUI64;
 
         ndev->cnf.mtu6 = dev->mtu;
-        ndev->cnf.sysctl = NULL;
         ndev->nd_parms = neigh_parms_alloc(dev, &nd_tbl);
         if (!ndev->nd_parms) {
                 kfree(ndev);
@@ -5620,13 +5619,7 @@ int addrconf_sysctl_ignore_routes_with_linkdown(struct ctl_table *ctl,
         return ret;
 }
 
-static struct addrconf_sysctl_table
-{
-        struct ctl_table_header *sysctl_header;
-        struct ctl_table addrconf_vars[DEVCONF_MAX+1];
-} addrconf_sysctl __read_mostly = {
-        .sysctl_header = NULL,
-        .addrconf_vars = {
+static const struct ctl_table addrconf_sysctl[] = {
                 {
                         .procname       = "forwarding",
                         .data           = &ipv6_devconf.forwarding,
@@ -5944,52 +5937,50 @@ static struct addrconf_sysctl_table
                 {
                         /* sentinel */
                 }
-        },
 };
 
 static int __addrconf_sysctl_register(struct net *net, char *dev_name,
                 struct inet6_dev *idev, struct ipv6_devconf *p)
 {
         int i;
-        struct addrconf_sysctl_table *t;
+        struct ctl_table *table;
         char path[sizeof("net/ipv6/conf/") + IFNAMSIZ];
 
-        t = kmemdup(&addrconf_sysctl, sizeof(*t), GFP_KERNEL);
-        if (!t)
+        table = kmemdup(addrconf_sysctl, sizeof(addrconf_sysctl), GFP_KERNEL);
+        if (!table)
                 goto out;
 
-        for (i = 0; t->addrconf_vars[i].data; i++) {
-                t->addrconf_vars[i].data += (char *)p - (char *)&ipv6_devconf;
-                t->addrconf_vars[i].extra1 = idev; /* embedded; no ref */
-                t->addrconf_vars[i].extra2 = net;
+        for (i = 0; table[i].data; i++) {
+                table[i].data += (char *)p - (char *)&ipv6_devconf;
+                table[i].extra1 = idev; /* embedded; no ref */
+                table[i].extra2 = net;
         }
 
         snprintf(path, sizeof(path), "net/ipv6/conf/%s", dev_name);
 
-        t->sysctl_header = register_net_sysctl(net, path, t->addrconf_vars);
-        if (!t->sysctl_header)
+        p->sysctl_header = register_net_sysctl(net, path, table);
+        if (!p->sysctl_header)
                 goto free;
 
-        p->sysctl = t;
         return 0;
 
 free:
-        kfree(t);
+        kfree(table);
 out:
         return -ENOBUFS;
 }
 
 static void __addrconf_sysctl_unregister(struct ipv6_devconf *p)
 {
-        struct addrconf_sysctl_table *t;
+        struct ctl_table *table;
 
-        if (!p->sysctl)
+        if (!p->sysctl_header)
                 return;
 
-        t = p->sysctl;
-        p->sysctl = NULL;
-        unregister_net_sysctl_table(t->sysctl_header);
-        kfree(t);
+        table = p->sysctl_header->ctl_table_arg;
+        unregister_net_sysctl_table(p->sysctl_header);
+        p->sysctl_header = NULL;
+        kfree(table);
 }
 
 static int addrconf_sysctl_register(struct inet6_dev *idev)