ipv6: constify inet6_mc_check()

inet6_mc_check() is essentially a read-only function.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/addrconf.h

@@ -223,7 +223,7 @@ int ipv6_sock_mc_drop(struct sock *sk, int ifindex,
 		      const struct in6_addr *addr);
 void __ipv6_sock_mc_close(struct sock *sk);
 void ipv6_sock_mc_close(struct sock *sk);
-bool inet6_mc_check(struct sock *sk, const struct in6_addr *mc_addr,
+bool inet6_mc_check(const struct sock *sk, const struct in6_addr *mc_addr,
 		    const struct in6_addr *src_addr);
 
 int ipv6_dev_mc_inc(struct net_device *dev, const struct in6_addr *addr);

net/ipv6/mcast.c

@@ -627,12 +627,12 @@ int ip6_mc_msfget(struct sock *sk, struct group_filter *gsf,
 	return 0;
 }
 
-bool inet6_mc_check(struct sock *sk, const struct in6_addr *mc_addr,
+bool inet6_mc_check(const struct sock *sk, const struct in6_addr *mc_addr,
 		    const struct in6_addr *src_addr)
 {
-	struct ipv6_pinfo *np = inet6_sk(sk);
-	struct ipv6_mc_socklist *mc;
-	struct ip6_sf_socklist *psl;
+	const struct ipv6_pinfo *np = inet6_sk(sk);
+	const struct ipv6_mc_socklist *mc;
+	const struct ip6_sf_socklist *psl;
 	bool rv = true;
 
 	rcu_read_lock();