l2tp: don't export tunnel and session free functions

Tunnel and session instances are reference counted, and shouldn't be
directly freed by pseudowire code.

Rather than exporting l2tp_tunnel_free and l2tp_session_free, make them
private to l2tp_core.c, and export the refcount functions instead.

In order to do this, the refcount functions cannot be declared as
inline.  Since the codepaths which take and drop tunnel and session
references are not directly in the datapath this shouldn't cause
performance issues.

Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 41 insertions, 19 deletions

diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index 7f4aef5a58ba..f22fe34eb8fc 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -149,12 +149,51 @@ l2tp_session_id_hash(struct l2tp_tunnel *tunnel, u32 session_id)
 	return &tunnel->session_hlist[hash_32(session_id, L2TP_HASH_BITS)];
 }
 
-void l2tp_tunnel_free(struct l2tp_tunnel *tunnel)
+static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel)
 {
 	sock_put(tunnel->sock);
 	/* the tunnel is freed in the socket destructor */
 }
-EXPORT_SYMBOL(l2tp_tunnel_free);
+
+static void l2tp_session_free(struct l2tp_session *session)
+{
+	struct l2tp_tunnel *tunnel = session->tunnel;
+
+	if (tunnel) {
+		if (WARN_ON(tunnel->magic != L2TP_TUNNEL_MAGIC))
+			goto out;
+		l2tp_tunnel_dec_refcount(tunnel);
+	}
+
+out:
+	kfree(session);
+}
+
+void l2tp_tunnel_inc_refcount(struct l2tp_tunnel *tunnel)
+{
+	refcount_inc(&tunnel->ref_count);
+}
+EXPORT_SYMBOL_GPL(l2tp_tunnel_inc_refcount);
+
+void l2tp_tunnel_dec_refcount(struct l2tp_tunnel *tunnel)
+{
+	if (refcount_dec_and_test(&tunnel->ref_count))
+		l2tp_tunnel_free(tunnel);
+}
+EXPORT_SYMBOL_GPL(l2tp_tunnel_dec_refcount);
+
+void l2tp_session_inc_refcount(struct l2tp_session *session)
+{
+	refcount_inc(&session->ref_count);
+}
+EXPORT_SYMBOL_GPL(l2tp_session_inc_refcount);
+
+void l2tp_session_dec_refcount(struct l2tp_session *session)
+{
+	if (refcount_dec_and_test(&session->ref_count))
+		l2tp_session_free(session);
+}
+EXPORT_SYMBOL_GPL(l2tp_session_dec_refcount);
 
 /* Lookup a tunnel. A new reference is held on the returned tunnel. */
 struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id)
@@ -1581,23 +1620,6 @@ void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel)
 }
 EXPORT_SYMBOL_GPL(l2tp_tunnel_delete);
 
-/* Really kill the session.
- */
-void l2tp_session_free(struct l2tp_session *session)
-{
-	struct l2tp_tunnel *tunnel = session->tunnel;
-
-	if (tunnel) {
-		if (WARN_ON(tunnel->magic != L2TP_TUNNEL_MAGIC))
-			goto out;
-		l2tp_tunnel_dec_refcount(tunnel);
-	}
-
-out:
-	kfree(session);
-}
-EXPORT_SYMBOL_GPL(l2tp_session_free);
-
 /* This function is used by the netlink SESSION_DELETE command and by
  * pseudowire modules.
  */