tcp: add const qualifiers where possible

Adding const qualifiers to pointers can ease code review, and spot some
bugs. It might allow compiler to optimize code further.

For example, is it legal to temporary write a null cksum into tcphdr
in tcp_md5_hash_header() ? I am afraid a sniffer could catch the
temporary null value...

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 3 deletions

diff --git a/net/ipv6/syncookies.c b/net/ipv6/syncookies.c
index ac838965ff34..5a0d6648bbbc 100644
--- a/net/ipv6/syncookies.c
+++ b/net/ipv6/syncookies.c
@@ -115,7 +115,7 @@ static __u32 check_tcp_syn_cookie(__u32 cookie, const struct in6_addr *saddr,
                 & COOKIEMASK;
 }
 
-__u32 cookie_v6_init_sequence(struct sock *sk, struct sk_buff *skb, __u16 *mssp)
+__u32 cookie_v6_init_sequence(struct sock *sk, const struct sk_buff *skb, __u16 *mssp)
 {
         const struct ipv6hdr *iph = ipv6_hdr(skb);
         const struct tcphdr *th = tcp_hdr(skb);
@@ -137,7 +137,7 @@ __u32 cookie_v6_init_sequence(struct sock *sk, struct sk_buff *skb, __u16 *mssp)
                                      jiffies / (HZ * 60), mssind);
 }
 
-static inline int cookie_check(struct sk_buff *skb, __u32 cookie)
+static inline int cookie_check(const struct sk_buff *skb, __u32 cookie)
 {
         const struct ipv6hdr *iph = ipv6_hdr(skb);
         const struct tcphdr *th = tcp_hdr(skb);
@@ -152,7 +152,7 @@ static inline int cookie_check(struct sk_buff *skb, __u32 cookie)
 struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
 {
         struct tcp_options_received tcp_opt;
-        u8 *hash_location;
+        const u8 *hash_location;
         struct inet_request_sock *ireq;
         struct inet6_request_sock *ireq6;
         struct tcp_request_sock *treq;