gtp: switch from struct socket to struct sock for the GTP sockets

After enabling the UDP encapsulation, only the sk member is used.

Holding the socket would prevent user space from closing the socket,
but holding a reference to the sk member does not have the same
effect.

This change will make it simpler to later detach the sockets from
the netdevice.

Signed-off-by: Andreas Schultz <aschultz@tpip.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/gtp.c

@@ -66,8 +66,8 @@ struct pdp_ctx {
 struct gtp_dev {
 	struct list_head	list;
 
-	struct socket		*sock0;
-	struct socket		*sock1u;
+	struct sock		*sk0;
+	struct sock		*sk1u;
 
 	struct net_device	*dev;
 
@@ -261,17 +261,19 @@ static int gtp1u_udp_encap_recv(struct gtp_dev *gtp, struct sk_buff *skb,
 
 static void gtp_encap_disable(struct gtp_dev *gtp)
 {
-	if (gtp->sock0 && gtp->sock0->sk) {
-		udp_sk(gtp->sock0->sk)->encap_type = 0;
-		rcu_assign_sk_user_data(gtp->sock0->sk, NULL);
+	if (gtp->sk0) {
+		udp_sk(gtp->sk0)->encap_type = 0;
+		rcu_assign_sk_user_data(gtp->sk0, NULL);
+		sock_put(gtp->sk0);
 	}
-	if (gtp->sock1u && gtp->sock1u->sk) {
-		udp_sk(gtp->sock1u->sk)->encap_type = 0;
-		rcu_assign_sk_user_data(gtp->sock1u->sk, NULL);
+	if (gtp->sk1u) {
+		udp_sk(gtp->sk1u)->encap_type = 0;
+		rcu_assign_sk_user_data(gtp->sk1u, NULL);
+		sock_put(gtp->sk1u);
 	}
 
-	gtp->sock0 = NULL;
-	gtp->sock1u = NULL;
+	gtp->sk0 = NULL;
+	gtp->sk1u = NULL;
 }
 
 static void gtp_encap_destroy(struct sock *sk)
@@ -484,14 +486,14 @@ static int gtp_build_skb_ip4(struct sk_buff *skb, struct net_device *dev,
 
 	switch (pctx->gtp_version) {
 	case GTP_V0:
-		if (gtp->sock0)
-			sk = gtp->sock0->sk;
+		if (gtp->sk0)
+			sk = gtp->sk0;
 		else
 			sk = NULL;
 		break;
 	case GTP_V1:
-		if (gtp->sock1u)
-			sk = gtp->sock1u->sk;
+		if (gtp->sk1u)
+			sk = gtp->sk1u;
 		else
 			sk = NULL;
 		break;
@@ -504,7 +506,7 @@ static int gtp_build_skb_ip4(struct sk_buff *skb, struct net_device *dev,
 		return -ENOENT;
 	}
 
-	rt = ip4_route_output_gtp(sock_net(sk), &fl4, gtp->sock0->sk,
+	rt = ip4_route_output_gtp(sock_net(sk), &fl4, gtp->sk0,
 				  pctx->sgsn_addr_ip4.s_addr);
 	if (IS_ERR(rt)) {
 		netdev_dbg(dev, "no route to SSGN %pI4\n",
@@ -839,18 +841,20 @@ static int gtp_encap_enable(struct net_device *dev, struct gtp_dev *gtp,
 
 	netdev_dbg(dev, "enable gtp on %p, %p\n", sock0, sock1u);
 
-	gtp->sock0 = sock0;
-	gtp->sock1u = sock1u;
+	sock_hold(sock0->sk);
+	gtp->sk0 = sock0->sk;
+	sock_hold(sock1u->sk);
+	gtp->sk1u = sock1u->sk;
 
 	tuncfg.sk_user_data = gtp;
 	tuncfg.encap_rcv = gtp_encap_recv;
 	tuncfg.encap_destroy = gtp_encap_destroy;
 
 	tuncfg.encap_type = UDP_ENCAP_GTP0;
-	setup_udp_tunnel_sock(sock_net(gtp->sock0->sk), gtp->sock0, &tuncfg);
+	setup_udp_tunnel_sock(sock_net(gtp->sk0), sock0, &tuncfg);
 
 	tuncfg.encap_type = UDP_ENCAP_GTP1U;
-	setup_udp_tunnel_sock(sock_net(gtp->sock1u->sk), gtp->sock1u, &tuncfg);
+	setup_udp_tunnel_sock(sock_net(gtp->sk1u), sock1u, &tuncfg);
 
 	err = 0;
 err2: