inet: constify ip headers and in6_addr

Add const qualifiers to structs iphdr, ipv6hdr and in6_addr pointers
where possible, to make code intention more obvious.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 4f49e5d..cb7658a 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -76,8 +76,8 @@
 
 static int	tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb);
 static void	__tcp_v6_send_check(struct sk_buff *skb,
-				    struct in6_addr *saddr,
-				    struct in6_addr *daddr);
+				    const struct in6_addr *saddr,
+				    const struct in6_addr *daddr);
 
 static const struct inet_connection_sock_af_ops ipv6_mapped;
 static const struct inet_connection_sock_af_ops ipv6_specific;
@@ -86,7 +86,7 @@
 static const struct tcp_sock_af_ops tcp_sock_ipv6_mapped_specific;
 #else
 static struct tcp_md5sig_key *tcp_v6_md5_do_lookup(struct sock *sk,
-						   struct in6_addr *addr)
+						   const struct in6_addr *addr)
 {
 	return NULL;
 }
@@ -106,8 +106,8 @@
 }
 
 static __inline__ __sum16 tcp_v6_check(int len,
-				   struct in6_addr *saddr,
-				   struct in6_addr *daddr,
+				   const struct in6_addr *saddr,
+				   const struct in6_addr *daddr,
 				   __wsum base)
 {
 	return csum_ipv6_magic(saddr, daddr, len, IPPROTO_TCP, base);
@@ -331,7 +331,7 @@
 static void tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 		u8 type, u8 code, int offset, __be32 info)
 {
-	struct ipv6hdr *hdr = (struct ipv6hdr*)skb->data;
+	const struct ipv6hdr *hdr = (const struct ipv6hdr*)skb->data;
 	const struct tcphdr *th = (struct tcphdr *)(skb->data+offset);
 	struct ipv6_pinfo *np;
 	struct sock *sk;
@@ -551,7 +551,7 @@
 
 #ifdef CONFIG_TCP_MD5SIG
 static struct tcp_md5sig_key *tcp_v6_md5_do_lookup(struct sock *sk,
-						   struct in6_addr *addr)
+						   const struct in6_addr *addr)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 	int i;
@@ -580,7 +580,7 @@
 	return tcp_v6_md5_do_lookup(sk, &inet6_rsk(req)->rmt_addr);
 }
 
-static int tcp_v6_md5_do_add(struct sock *sk, struct in6_addr *peer,
+static int tcp_v6_md5_do_add(struct sock *sk, const struct in6_addr *peer,
 			     char *newkey, u8 newkeylen)
 {
 	/* Add key to the list */
@@ -645,7 +645,7 @@
 				 newkey, newkeylen);
 }
 
-static int tcp_v6_md5_do_del(struct sock *sk, struct in6_addr *peer)
+static int tcp_v6_md5_do_del(struct sock *sk, const struct in6_addr *peer)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 	int i;
@@ -753,8 +753,8 @@
 }
 
 static int tcp_v6_md5_hash_pseudoheader(struct tcp_md5sig_pool *hp,
-					struct in6_addr *daddr,
-					struct in6_addr *saddr, int nbytes)
+					const struct in6_addr *daddr,
+					const struct in6_addr *saddr, int nbytes)
 {
 	struct tcp6_pseudohdr *bp;
 	struct scatterlist sg;
@@ -771,7 +771,7 @@
 }
 
 static int tcp_v6_md5_hash_hdr(char *md5_hash, struct tcp_md5sig_key *key,
-			       struct in6_addr *daddr, struct in6_addr *saddr,
+			       const struct in6_addr *daddr, struct in6_addr *saddr,
 			       struct tcphdr *th)
 {
 	struct tcp_md5sig_pool *hp;
@@ -807,7 +807,7 @@
 			       struct sock *sk, struct request_sock *req,
 			       struct sk_buff *skb)
 {
-	struct in6_addr *saddr, *daddr;
+	const struct in6_addr *saddr, *daddr;
 	struct tcp_md5sig_pool *hp;
 	struct hash_desc *desc;
 	struct tcphdr *th = tcp_hdr(skb);
@@ -819,7 +819,7 @@
 		saddr = &inet6_rsk(req)->loc_addr;
 		daddr = &inet6_rsk(req)->rmt_addr;
 	} else {
-		struct ipv6hdr *ip6h = ipv6_hdr(skb);
+		const struct ipv6hdr *ip6h = ipv6_hdr(skb);
 		saddr = &ip6h->saddr;
 		daddr = &ip6h->daddr;
 	}
@@ -857,7 +857,7 @@
 {
 	__u8 *hash_location = NULL;
 	struct tcp_md5sig_key *hash_expected;
-	struct ipv6hdr *ip6h = ipv6_hdr(skb);
+	const struct ipv6hdr *ip6h = ipv6_hdr(skb);
 	struct tcphdr *th = tcp_hdr(skb);
 	int genhash;
 	u8 newhash[16];
@@ -915,7 +915,7 @@
 #endif
 
 static void __tcp_v6_send_check(struct sk_buff *skb,
-				struct in6_addr *saddr, struct in6_addr *daddr)
+				const struct in6_addr *saddr, const struct in6_addr *daddr)
 {
 	struct tcphdr *th = tcp_hdr(skb);
 
@@ -939,7 +939,7 @@
 
 static int tcp_v6_gso_send_check(struct sk_buff *skb)
 {
-	struct ipv6hdr *ipv6h;
+	const struct ipv6hdr *ipv6h;
 	struct tcphdr *th;
 
 	if (!pskb_may_pull(skb, sizeof(*th)))
@@ -957,7 +957,7 @@
 static struct sk_buff **tcp6_gro_receive(struct sk_buff **head,
 					 struct sk_buff *skb)
 {
-	struct ipv6hdr *iph = skb_gro_network_header(skb);
+	const struct ipv6hdr *iph = skb_gro_network_header(skb);
 
 	switch (skb->ip_summed) {
 	case CHECKSUM_COMPLETE:
@@ -978,7 +978,7 @@
 
 static int tcp6_gro_complete(struct sk_buff *skb)
 {
-	struct ipv6hdr *iph = ipv6_hdr(skb);
+	const struct ipv6hdr *iph = ipv6_hdr(skb);
 	struct tcphdr *th = tcp_hdr(skb);
 
 	th->check = ~tcp_v6_check(skb->len - skb_transport_offset(skb),
@@ -1702,7 +1702,7 @@
 static int tcp_v6_rcv(struct sk_buff *skb)
 {
 	struct tcphdr *th;
-	struct ipv6hdr *hdr;
+	const struct ipv6hdr *hdr;
 	struct sock *sk;
 	int ret;
 	struct net *net = dev_net(skb->dev);
@@ -2028,8 +2028,8 @@
 			 struct sock *sk, struct request_sock *req, int i, int uid)
 {
 	int ttd = req->expires - jiffies;
-	struct in6_addr *src = &inet6_rsk(req)->loc_addr;
-	struct in6_addr *dest = &inet6_rsk(req)->rmt_addr;
+	const struct in6_addr *src = &inet6_rsk(req)->loc_addr;
+	const struct in6_addr *dest = &inet6_rsk(req)->rmt_addr;
 
 	if (ttd < 0)
 		ttd = 0;
@@ -2057,7 +2057,7 @@
 
 static void get_tcp6_sock(struct seq_file *seq, struct sock *sp, int i)
 {
-	struct in6_addr *dest, *src;
+	const struct in6_addr *dest, *src;
 	__u16 destp, srcp;
 	int timer_active;
 	unsigned long timer_expires;
@@ -2114,7 +2114,7 @@
 static void get_timewait6_sock(struct seq_file *seq,
 			       struct inet_timewait_sock *tw, int i)
 {
-	struct in6_addr *dest, *src;
+	const struct in6_addr *dest, *src;
 	__u16 destp, srcp;
 	struct inet6_timewait_sock *tw6 = inet6_twsk((struct sock *)tw);
 	int ttd = tw->tw_ttd - jiffies;