ipv6/addrconf: allocate a per netns hash table

Add a per netns hash table and a dedicated spinlock,
first step to get rid of the global inet6_addr_lst[] one.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

include/net/netns/ipv6.h

@@ -92,6 +92,10 @@ struct netns_ipv6 {
 	struct sock             *tcp_sk;
 	struct sock             *igmp_sk;
 	struct sock		*mc_autojoin_sk;
+
+	struct hlist_head	*inet6_addr_lst;
+	spinlock_t		addrconf_hash_lock;
+
 #ifdef CONFIG_IPV6_MROUTE
 #ifndef CONFIG_IPV6_MROUTE_MULTIPLE_TABLES
 	struct mr_table		*mrt6;

net/ipv6/addrconf.c

@@ -7111,6 +7111,13 @@ static int __net_init addrconf_init_net(struct net *net)
 	int err = -ENOMEM;
 	struct ipv6_devconf *all, *dflt;
 
+	spin_lock_init(&net->ipv6.addrconf_hash_lock);
+	net->ipv6.inet6_addr_lst = kcalloc(IN6_ADDR_HSIZE,
+					   sizeof(struct hlist_head),
+					   GFP_KERNEL);
+	if (!net->ipv6.inet6_addr_lst)
+		goto err_alloc_addr;
+
 	all = kmemdup(&ipv6_devconf, sizeof(ipv6_devconf), GFP_KERNEL);
 	if (!all)
 		goto err_alloc_all;
@@ -7172,11 +7179,15 @@ static int __net_init addrconf_init_net(struct net *net)
 err_alloc_dflt:
 	kfree(all);
 err_alloc_all:
+	kfree(net->ipv6.inet6_addr_lst);
+err_alloc_addr:
 	return err;
 }
 
 static void __net_exit addrconf_exit_net(struct net *net)
 {
+	int i;
+
 #ifdef CONFIG_SYSCTL
 	__addrconf_sysctl_unregister(net, net->ipv6.devconf_dflt,
 				     NETCONFA_IFINDEX_DEFAULT);
@@ -7187,6 +7198,15 @@ static void __net_exit addrconf_exit_net(struct net *net)
 	net->ipv6.devconf_dflt = NULL;
 	kfree(net->ipv6.devconf_all);
 	net->ipv6.devconf_all = NULL;
+
+	/*
+	 *	Check hash table, then free it.
+	 */
+	for (i = 0; i < IN6_ADDR_HSIZE; i++)
+		WARN_ON_ONCE(!hlist_empty(&net->ipv6.inet6_addr_lst[i]));
+
+	kfree(net->ipv6.inet6_addr_lst);
+	net->ipv6.inet6_addr_lst = NULL;
 }
 
 static struct pernet_operations addrconf_ops = {