l2tp: use IDR for all session lookups

Add generic session getter which uses IDR. Replace all users of
l2tp_tunnel_get_session which uses the per-tunnel session list to use
the generic getter.
Signed-off-by: James Chapman <jchapman@katalix.com>
Reviewed-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/l2tp/l2tp_core.c

@@ -316,6 +316,16 @@ struct l2tp_session *l2tp_v2_session_get(const struct net *net, u16 tunnel_id, u
 }
 EXPORT_SYMBOL_GPL(l2tp_v2_session_get);
 
+struct l2tp_session *l2tp_session_get(const struct net *net, struct sock *sk, int pver,
+				      u32 tunnel_id, u32 session_id)
+{
+	if (pver == L2TP_HDR_VER_2)
+		return l2tp_v2_session_get(net, tunnel_id, session_id);
+	else
+		return l2tp_v3_session_get(net, sk, session_id);
+}
+EXPORT_SYMBOL_GPL(l2tp_session_get);
+
 struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth)
 {
 	int hash;

net/l2tp/l2tp_core.h

@@ -232,6 +232,8 @@ struct l2tp_session *l2tp_tunnel_get_session(struct l2tp_tunnel *tunnel,
 
 struct l2tp_session *l2tp_v3_session_get(const struct net *net, struct sock *sk, u32 session_id);
 struct l2tp_session *l2tp_v2_session_get(const struct net *net, u16 tunnel_id, u16 session_id);
+struct l2tp_session *l2tp_session_get(const struct net *net, struct sock *sk, int pver,
+				      u32 tunnel_id, u32 session_id);
 struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth);
 struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net,
 						const char *ifname);

net/l2tp/l2tp_netlink.c

@@ -61,7 +61,8 @@ static struct l2tp_session *l2tp_nl_session_get(struct genl_info *info)
 		session_id = nla_get_u32(info->attrs[L2TP_ATTR_SESSION_ID]);
 		tunnel = l2tp_tunnel_get(net, tunnel_id);
 		if (tunnel) {
-			session = l2tp_tunnel_get_session(tunnel, session_id);
+			session = l2tp_session_get(net, tunnel->sock, tunnel->version,
+						   tunnel_id, session_id);
 			l2tp_tunnel_dec_refcount(tunnel);
 		}
 	}
@@ -635,7 +636,8 @@ static int l2tp_nl_cmd_session_create(struct sk_buff *skb, struct genl_info *inf
 							   &cfg);
 
 	if (ret >= 0) {
-		session = l2tp_tunnel_get_session(tunnel, session_id);
+		session = l2tp_session_get(net, tunnel->sock, tunnel->version,
+					   tunnel_id, session_id);
 		if (session) {
 			ret = l2tp_session_notify(&l2tp_nl_family, info, session,
 						  L2TP_CMD_SESSION_CREATE);

net/l2tp/l2tp_ppp.c

@@ -753,7 +753,8 @@ static int pppol2tp_connect(struct socket *sock, struct sockaddr *uservaddr,
 	if (tunnel->peer_tunnel_id == 0)
 		tunnel->peer_tunnel_id = info.peer_tunnel_id;
 
-	session = l2tp_tunnel_get_session(tunnel, info.session_id);
+	session = l2tp_session_get(sock_net(sk), tunnel->sock, tunnel->version,
+				   info.tunnel_id, info.session_id);
 	if (session) {
 		drop_refcnt = true;
 
@@ -1045,7 +1046,8 @@ static int pppol2tp_tunnel_copy_stats(struct pppol2tp_ioc_stats *stats,
 	/* If session_id is set, search the corresponding session in the
 	 * context of this tunnel and record the session's statistics.
 	 */
-	session = l2tp_tunnel_get_session(tunnel, stats->session_id);
+	session = l2tp_session_get(tunnel->l2tp_net, tunnel->sock, tunnel->version,
+				   tunnel->tunnel_id, stats->session_id);
 	if (!session)
 		return -EBADR;