[TCP]: struct tcp_sack_block annotations

Some of the instances of tcp_sack_block are host-endian, some - net-endian.
Define struct tcp_sack_block_wire identical to struct tcp_sack_block
with u32 replaced with __be32; annotate uses of tcp_sack_block replacing
net-endian ones with tcp_sack_block_wire.  Change is obviously safe since
for cc(1) __be32 is typedefed to u32.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/tcp.h

@@ -166,6 +166,11 @@ struct tcp_info
 #include <net/inet_timewait_sock.h>
 
 /* This defines a selective acknowledgement block. */
+struct tcp_sack_block_wire {
+	__be32	start_seq;
+	__be32	end_seq;
+};
+
 struct tcp_sack_block {
 	__u32	start_seq;
 	__u32	end_seq;

net/ipv4/netfilter/ip_nat_helper.c

@@ -283,7 +283,7 @@ sack_adjust(struct sk_buff *skb,
 	    struct ip_nat_seq *natseq)
 {
 	while (sackoff < sackend) {
-		struct tcp_sack_block *sack;
+		struct tcp_sack_block_wire *sack;
 		u_int32_t new_start_seq, new_end_seq;
 
 		sack = (void *)skb->data + sackoff;

net/ipv4/tcp_input.c

@@ -935,7 +935,7 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
 	const struct inet_connection_sock *icsk = inet_csk(sk);
 	struct tcp_sock *tp = tcp_sk(sk);
 	unsigned char *ptr = ack_skb->h.raw + TCP_SKB_CB(ack_skb)->sacked;
-	struct tcp_sack_block *sp = (struct tcp_sack_block *)(ptr+2);
+	struct tcp_sack_block_wire *sp = (struct tcp_sack_block_wire *)(ptr+2);
 	int num_sacks = (ptr[1] - TCPOLEN_SACK_BASE)>>3;
 	int reord = tp->packets_out;
 	int prior_fackets;