ip_tunnel: embed hash list head

The IP tunnel hash heads can be embedded in the per-net structure
since it is a fixed size. Reduce the size so that the total structure
fits in a page size. The original size was overly large, even NETDEV_HASHBITS
is only 8 bits!

Also, add some white space for readability.

Signed-off-by: Stephen Hemminger <[email protected]>
Acked-by: Pravin B Shelar <[email protected]>.
Signed-off-by: David S. Miller <[email protected]>

include/net/ip_tunnels.h

@@ -86,12 +86,12 @@ struct tnl_ptk_info {
 #define PACKET_RCVD	0
 #define PACKET_REJECT	1
 
-#define IP_TNL_HASH_BITS   10
+#define IP_TNL_HASH_BITS   7
 #define IP_TNL_HASH_SIZE   (1 << IP_TNL_HASH_BITS)
 
 struct ip_tunnel_net {
-	struct hlist_head *tunnels;
 	struct net_device *fb_tunnel_dev;
+	struct hlist_head tunnels[IP_TNL_HASH_SIZE];
 };
 
 #ifdef CONFIG_INET

net/ipv4/ip_tunnel.c

@@ -838,26 +838,26 @@ int ip_tunnel_init_net(struct net *net, int ip_tnl_net_id,
 {
 	struct ip_tunnel_net *itn = net_generic(net, ip_tnl_net_id);
 	struct ip_tunnel_parm parms;
+	unsigned int i;
 
-	itn->tunnels = kzalloc(IP_TNL_HASH_SIZE * sizeof(struct hlist_head), GFP_KERNEL);
-	if (!itn->tunnels)
-		return -ENOMEM;
+	for (i = 0; i < IP_TNL_HASH_SIZE; i++)
+		INIT_HLIST_HEAD(&itn->tunnels[i]);
 
 	if (!ops) {
 		itn->fb_tunnel_dev = NULL;
 		return 0;
 	}
+
 	memset(&parms, 0, sizeof(parms));
 	if (devname)
 		strlcpy(parms.name, devname, IFNAMSIZ);
 
 	rtnl_lock();
 	itn->fb_tunnel_dev = __ip_tunnel_create(net, ops, &parms);
 	rtnl_unlock();
-	if (IS_ERR(itn->fb_tunnel_dev)) {
-		kfree(itn->tunnels);
+
+	if (IS_ERR(itn->fb_tunnel_dev))
 		return PTR_ERR(itn->fb_tunnel_dev);
-	}
 
 	return 0;
 }
@@ -887,7 +887,6 @@ void ip_tunnel_delete_net(struct ip_tunnel_net *itn)
 	ip_tunnel_destroy(itn, &list);
 	unregister_netdevice_many(&list);
 	rtnl_unlock();
-	kfree(itn->tunnels);
 }
 EXPORT_SYMBOL_GPL(ip_tunnel_delete_net);