net: Convert ip6 tables pernet_operations

The pernet_operations:

    ip6table_filter_net_ops
    ip6table_mangle_net_ops
    ip6table_nat_net_ops
    ip6table_raw_net_ops
    ip6table_security_net_ops

have exit methods, which call ip6t_unregister_table().
ip6table_filter_net_ops has init method registering
filter table.

Since there must not be in-flight ipv6 packets at the time
of pernet_operations execution and since pernet_operations
don't send ipv6 packets each other, these pernet_operations
are safe to be async.

Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/netfilter/ip6table_filter.c

@@ -87,6 +87,7 @@ static void __net_exit ip6table_filter_net_exit(struct net *net)
 static struct pernet_operations ip6table_filter_net_ops = {
 	.init = ip6table_filter_net_init,
 	.exit = ip6table_filter_net_exit,
+	.async = true,
 };
 
 static int __init ip6table_filter_init(void)

net/ipv6/netfilter/ip6table_mangle.c

@@ -107,6 +107,7 @@ static void __net_exit ip6table_mangle_net_exit(struct net *net)
 
 static struct pernet_operations ip6table_mangle_net_ops = {
 	.exit = ip6table_mangle_net_exit,
+	.async = true,
 };
 
 static int __init ip6table_mangle_init(void)

net/ipv6/netfilter/ip6table_nat.c

@@ -131,6 +131,7 @@ static void __net_exit ip6table_nat_net_exit(struct net *net)
 
 static struct pernet_operations ip6table_nat_net_ops = {
 	.exit	= ip6table_nat_net_exit,
+	.async	= true,
 };
 
 static int __init ip6table_nat_init(void)

net/ipv6/netfilter/ip6table_raw.c

@@ -75,6 +75,7 @@ static void __net_exit ip6table_raw_net_exit(struct net *net)
 
 static struct pernet_operations ip6table_raw_net_ops = {
 	.exit = ip6table_raw_net_exit,
+	.async = true,
 };
 
 static int __init ip6table_raw_init(void)

net/ipv6/netfilter/ip6table_security.c

@@ -74,6 +74,7 @@ static void __net_exit ip6table_security_net_exit(struct net *net)
 
 static struct pernet_operations ip6table_security_net_ops = {
 	.exit = ip6table_security_net_exit,
+	.async = true,
 };
 
 static int __init ip6table_security_init(void)