ipv4: make ip_local_reserved_ports per netns

ip_local_port_range is already per netns, so should ip_local_reserved_ports
be. And since it is none by default we don't actually need it when we don't
enable CONFIG_SYSCTL.

By the way, rename inet_is_reserved_local_port() to inet_is_local_reserved_port()

Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/ip.h b/include/net/ip.h
index 14c50a1..512bcd5 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -208,11 +208,19 @@
 
 void inet_get_local_port_range(struct net *net, int *low, int *high);
 
-extern unsigned long *sysctl_local_reserved_ports;
-static inline int inet_is_reserved_local_port(int port)
+#if CONFIG_SYSCTL
+static inline int inet_is_local_reserved_port(struct net *net, int port)
 {
-	return test_bit(port, sysctl_local_reserved_ports);
+	if (!net->ipv4.sysctl_local_reserved_ports)
+		return 0;
+	return test_bit(port, net->ipv4.sysctl_local_reserved_ports);
 }
+#else
+static inline int inet_is_local_reserved_port(struct net *net, int port)
+{
+	return 0;
+}
+#endif
 
 extern int sysctl_ip_nonlocal_bind;