l2tp: fix unused function warning

Removing one of the callers of pppol2tp_session_get_sock caused a harmless
warning in some configurations:

net/l2tp/l2tp_ppp.c:142:21: 'pppol2tp_session_get_sock' defined but not used [-Wunused-function]

Rather than adding another #ifdef here, using a proper IS_ENABLED()
check makes the code more readable and avoids those warnings while
letting the compiler figure out for itself which code is needed.

This adds one pointer for the unused show() callback in struct
l2tp_session, but that seems harmless.

Fixes: b0e29063dcb3 ("l2tp: remove pppol2tp_session_ioctl()")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/l2tp/l2tp_core.h

@@ -118,9 +118,7 @@ struct l2tp_session {
 	int (*build_header)(struct l2tp_session *session, void *buf);
 	void (*recv_skb)(struct l2tp_session *session, struct sk_buff *skb, int data_len);
 	void (*session_close)(struct l2tp_session *session);
-#if IS_ENABLED(CONFIG_L2TP_DEBUGFS)
 	void (*show)(struct seq_file *m, void *priv);
-#endif
 	uint8_t			priv[0];	/* private data */
 };
 

net/l2tp/l2tp_eth.c

@@ -199,7 +199,6 @@ static void l2tp_eth_delete(struct l2tp_session *session)
 	}
 }
 
-#if IS_ENABLED(CONFIG_L2TP_DEBUGFS)
 static void l2tp_eth_show(struct seq_file *m, void *arg)
 {
 	struct l2tp_session *session = arg;
@@ -219,7 +218,6 @@ static void l2tp_eth_show(struct seq_file *m, void *arg)
 
 	dev_put(dev);
 }
-#endif
 
 static void l2tp_eth_adjust_mtu(struct l2tp_tunnel *tunnel,
 				struct l2tp_session *session,
@@ -305,9 +303,8 @@ static int l2tp_eth_create(struct net *net, struct l2tp_tunnel *tunnel,
 
 	session->recv_skb = l2tp_eth_dev_recv;
 	session->session_close = l2tp_eth_delete;
-#if IS_ENABLED(CONFIG_L2TP_DEBUGFS)
-	session->show = l2tp_eth_show;
-#endif
+	if (IS_ENABLED(CONFIG_L2TP_DEBUGFS))
+		session->show = l2tp_eth_show;
 
 	spriv = l2tp_session_priv(session);
 

net/l2tp/l2tp_ppp.c

@@ -533,7 +533,6 @@ out:
 	return error;
 }
 
-#if IS_ENABLED(CONFIG_L2TP_DEBUGFS)
 static void pppol2tp_show(struct seq_file *m, void *arg)
 {
 	struct l2tp_session *session = arg;
@@ -547,16 +546,14 @@ static void pppol2tp_show(struct seq_file *m, void *arg)
 		sock_put(sk);
 	}
 }
-#endif
 
 static void pppol2tp_session_init(struct l2tp_session *session)
 {
 	struct pppol2tp_session *ps;
 
 	session->recv_skb = pppol2tp_recv;
-#if IS_ENABLED(CONFIG_L2TP_DEBUGFS)
-	session->show = pppol2tp_show;
-#endif
+	if (IS_ENABLED(CONFIG_L2TP_DEBUGFS))
+		session->show = pppol2tp_show;
 
 	ps = l2tp_session_priv(session);
 	mutex_init(&ps->sk_lock);