ipv6: sr: restruct ifdefines

There are too many ifdef in IPv6 segment routing code that may cause logic
problems. like commit 160e9d27 ("ipv6: sr: fix invalid unregister error
path"). To avoid this, the init functions are redefined for both cases. The
code could be more clear after all fidefs are removed.
Suggested-by: Simon Horman <horms@kernel.org>
Suggested-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20240529040908.3472952-1-liuhangbin@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

include/net/seg6.h

@@ -52,10 +52,17 @@ static inline struct seg6_pernet_data *seg6_pernet(struct net *net)
 
 extern int seg6_init(void);
 extern void seg6_exit(void);
+#ifdef CONFIG_IPV6_SEG6_LWTUNNEL
 extern int seg6_iptunnel_init(void);
 extern void seg6_iptunnel_exit(void);
 extern int seg6_local_init(void);
 extern void seg6_local_exit(void);
+#else
+static inline int seg6_iptunnel_init(void) { return 0; }
+static inline void seg6_iptunnel_exit(void) {}
+static inline int seg6_local_init(void) { return 0; }
+static inline void seg6_local_exit(void) {}
+#endif
 
 extern bool seg6_validate_srh(struct ipv6_sr_hdr *srh, int len, bool reduced);
 extern struct ipv6_sr_hdr *seg6_get_srh(struct sk_buff *skb, int flags);

include/net/seg6_hmac.h

@@ -49,9 +49,16 @@ extern int seg6_hmac_info_del(struct net *net, u32 key);
 extern int seg6_push_hmac(struct net *net, struct in6_addr *saddr,
 			  struct ipv6_sr_hdr *srh);
 extern bool seg6_hmac_validate_skb(struct sk_buff *skb);
+#ifdef CONFIG_IPV6_SEG6_HMAC
 extern int seg6_hmac_init(void);
 extern void seg6_hmac_exit(void);
 extern int seg6_hmac_net_init(struct net *net);
 extern void seg6_hmac_net_exit(struct net *net);
+#else
+static inline int seg6_hmac_init(void) { return 0; }
+static inline void seg6_hmac_exit(void) {}
+static inline int seg6_hmac_net_init(struct net *net) { return 0; }
+static inline void seg6_hmac_net_exit(struct net *net) {}
+#endif
 
 #endif

net/ipv6/seg6.c

@@ -21,9 +21,7 @@
 #include <net/genetlink.h>
 #include <linux/seg6.h>
 #include <linux/seg6_genl.h>
-#ifdef CONFIG_IPV6_SEG6_HMAC
 #include <net/seg6_hmac.h>
-#endif
 
 bool seg6_validate_srh(struct ipv6_sr_hdr *srh, int len, bool reduced)
 {
@@ -437,13 +435,11 @@ static int __net_init seg6_net_init(struct net *net)
 
 	net->ipv6.seg6_data = sdata;
 
-#ifdef CONFIG_IPV6_SEG6_HMAC
 	if (seg6_hmac_net_init(net)) {
 		kfree(rcu_dereference_raw(sdata->tun_src));
 		kfree(sdata);
 		return -ENOMEM;
 	}
-#endif
 
 	return 0;
 }
@@ -452,9 +448,7 @@ static void __net_exit seg6_net_exit(struct net *net)
 {
 	struct seg6_pernet_data *sdata = seg6_pernet(net);
 
-#ifdef CONFIG_IPV6_SEG6_HMAC
 	seg6_hmac_net_exit(net);
-#endif
 
 	kfree(rcu_dereference_raw(sdata->tun_src));
 	kfree(sdata);
@@ -520,41 +514,28 @@ int __init seg6_init(void)
 	if (err)
 		goto out_unregister_pernet;
 
-#ifdef CONFIG_IPV6_SEG6_LWTUNNEL
 	err = seg6_iptunnel_init();
 	if (err)
 		goto out_unregister_genl;
 
 	err = seg6_local_init();
-	if (err) {
-		seg6_iptunnel_exit();
-		goto out_unregister_genl;
-	}
-#endif
+	if (err)
+		goto out_unregister_iptun;
 
-#ifdef CONFIG_IPV6_SEG6_HMAC
 	err = seg6_hmac_init();
 	if (err)
-		goto out_unregister_iptun;
-#endif
+		goto out_unregister_seg6;
 
 	pr_info("Segment Routing with IPv6\n");
 
 out:
 	return err;
-#ifdef CONFIG_IPV6_SEG6_HMAC
-out_unregister_iptun:
-#ifdef CONFIG_IPV6_SEG6_LWTUNNEL
+out_unregister_seg6:
 	seg6_local_exit();
+out_unregister_iptun:
 	seg6_iptunnel_exit();
-#endif
-#endif
-#ifdef CONFIG_IPV6_SEG6_LWTUNNEL
 out_unregister_genl:
-#endif
-#if IS_ENABLED(CONFIG_IPV6_SEG6_LWTUNNEL) || IS_ENABLED(CONFIG_IPV6_SEG6_HMAC)
 	genl_unregister_family(&seg6_genl_family);
-#endif
 out_unregister_pernet:
 	unregister_pernet_subsys(&ip6_segments_ops);
 	goto out;
@@ -562,13 +543,9 @@ int __init seg6_init(void)
 
 void seg6_exit(void)
 {
-#ifdef CONFIG_IPV6_SEG6_HMAC
 	seg6_hmac_exit();
-#endif
-#ifdef CONFIG_IPV6_SEG6_LWTUNNEL
 	seg6_local_exit();
 	seg6_iptunnel_exit();
-#endif
 	genl_unregister_family(&seg6_genl_family);
 	unregister_pernet_subsys(&ip6_segments_ops);
 }