diff --git a/include/net/tcp.h b/include/net/tcp.h
index e9b48b094683..acc620a4a45f 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -431,17 +431,34 @@ extern int tcp_disconnect(struct sock *sk, int flags);
 extern __u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS];
 extern struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb, 
 				    struct ip_options *opt);
+#ifdef CONFIG_SYN_COOKIES
 extern __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb, 
 				     __u16 *mss);
+#else
+static inline __u32 cookie_v4_init_sequence(struct sock *sk,
+					    struct sk_buff *skb,
+					    __u16 *mss)
+{
+	return 0;
+}
+#endif
 
 extern __u32 cookie_init_timestamp(struct request_sock *req);
 extern bool cookie_check_timestamp(struct tcp_options_received *opt, bool *);
 
 /* From net/ipv6/syncookies.c */
 extern struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
+#ifdef CONFIG_SYN_COOKIES
 extern __u32 cookie_v6_init_sequence(struct sock *sk, struct sk_buff *skb,
 				     __u16 *mss);
-
+#else
+static inline __u32 cookie_v6_init_sequence(struct sock *sk,
+					    struct sk_buff *skb,
+					    __u16 *mss)
+{
+	return 0;
+}
+#endif
 /* tcp_output.c */
 
 extern void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index ea0d2183df4b..21fab3edb92c 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1124,7 +1124,7 @@ static int tcp_is_sackblock_valid(struct tcp_sock *tp, int is_dsack,
 		return 0;
 
 	/* ...Then it's D-SACK, and must reside below snd_una completely */
-	if (!after(end_seq, tp->snd_una))
+	if (after(end_seq, tp->snd_una))
 		return 0;
 
 	if (!before(start_seq, tp->undo_marker))