tcp memory pressure controls

This patch introduces memory pressure controls for the tcp
protocol. It uses the generic socket memory pressure code
introduced in earlier patches, and fills in the
necessary data in cg_proto struct.

Signed-off-by: Glauber Costa <glommer@parallels.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujtisu.com>
CC: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/tcp_ipv4.c

@@ -73,6 +73,7 @@
 #include <net/xfrm.h>
 #include <net/netdma.h>
 #include <net/secure_seq.h>
+#include <net/tcp_memcontrol.h>
 
 #include <linux/inet.h>
 #include <linux/ipv6.h>
@@ -1917,6 +1918,7 @@ static int tcp_v4_init_sock(struct sock *sk)
 	sk->sk_rcvbuf = sysctl_tcp_rmem[1];
 
 	local_bh_disable();
+	sock_update_memcg(sk);
 	sk_sockets_allocated_inc(sk);
 	local_bh_enable();
 
@@ -1974,6 +1976,7 @@ void tcp_v4_destroy_sock(struct sock *sk)
 	}
 
 	sk_sockets_allocated_dec(sk);
+	sock_release_memcg(sk);
 }
 EXPORT_SYMBOL(tcp_v4_destroy_sock);
 
@@ -2634,10 +2637,14 @@ struct proto tcp_prot = {
 	.compat_setsockopt	= compat_tcp_setsockopt,
 	.compat_getsockopt	= compat_tcp_getsockopt,
 #endif
+#ifdef CONFIG_CGROUP_MEM_RES_CTLR_KMEM
+	.init_cgroup		= tcp_init_cgroup,
+	.destroy_cgroup		= tcp_destroy_cgroup,
+	.proto_cgroup		= tcp_proto_cgroup,
+#endif
 };
 EXPORT_SYMBOL(tcp_prot);
 
-
 static int __net_init tcp_sk_init(struct net *net)
 {
 	return inet_ctl_sock_create(&net->ipv4.tcp_sock,