tcp: Clean up reverse xmas tree in cookie_v[46]_check().

We will grow and cut the xmas tree in cookie_v[46]_check().
This patch cleans it up to make later patches tidy.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20231129022924.96156-2-kuniyu@amazon.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

net/ipv4/syncookies.c

@@ -331,18 +331,18 @@ EXPORT_SYMBOL_GPL(cookie_tcp_reqsk_alloc);
 struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
 {
 	struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt;
+	const struct tcphdr *th = tcp_hdr(skb);
+	__u32 cookie = ntohl(th->ack_seq) - 1;
 	struct tcp_options_received tcp_opt;
+	struct tcp_sock *tp = tcp_sk(sk);
 	struct inet_request_sock *ireq;
 	struct tcp_request_sock *treq;
-	struct tcp_sock *tp = tcp_sk(sk);
-	const struct tcphdr *th = tcp_hdr(skb);
-	__u32 cookie = ntohl(th->ack_seq) - 1;
-	struct sock *ret = sk;
 	struct request_sock *req;
+	struct sock *ret = sk;
 	int full_space, mss;
+	struct flowi4 fl4;
 	struct rtable *rt;
 	__u8 rcv_wscale;
-	struct flowi4 fl4;
 	u32 tsoff = 0;
 	int l3index;
 

net/ipv6/syncookies.c

@@ -127,17 +127,17 @@ EXPORT_SYMBOL_GPL(__cookie_v6_check);
 
 struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
 {
+	const struct tcphdr *th = tcp_hdr(skb);
+	__u32 cookie = ntohl(th->ack_seq) - 1;
+	struct ipv6_pinfo *np = inet6_sk(sk);
 	struct tcp_options_received tcp_opt;
+	struct tcp_sock *tp = tcp_sk(sk);
 	struct inet_request_sock *ireq;
 	struct tcp_request_sock *treq;
-	struct ipv6_pinfo *np = inet6_sk(sk);
-	struct tcp_sock *tp = tcp_sk(sk);
-	const struct tcphdr *th = tcp_hdr(skb);
-	__u32 cookie = ntohl(th->ack_seq) - 1;
-	struct sock *ret = sk;
 	struct request_sock *req;
-	int full_space, mss;
 	struct dst_entry *dst;
+	struct sock *ret = sk;
+	int full_space, mss;
 	__u8 rcv_wscale;
 	u32 tsoff = 0;
 	int l3index;