ipv4: Constify the sk parameter of ip_route_output_*().

These functions don't need to modify the socket, so let's allow the
callers to pass a const struct sock *.

Signed-off-by: Guillaume Nault <[e-mail]>
Reviewed-by: Simon Horman <[e-mail]>
Reviewed-by: David Ahern <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/net/route.h

···
 }
 
 static inline struct rtable *ip_route_output_ports(struct net *net, struct flowi4 *fl4,
-						   struct sock *sk,
+						   const struct sock *sk,
 						   __be32 daddr, __be32 saddr,
 						   __be16 dport, __be16 sport,
 						   __u8 proto, __u8 tos, int oif)
···
 static inline struct rtable *ip_route_connect(struct flowi4 *fl4, __be32 dst,
 					      __be32 src, int oif, u8 protocol,
 					      __be16 sport, __be16 dport,
-					      struct sock *sk)
+					      const struct sock *sk)
 {
 	struct net *net = sock_net(sk);
 	struct rtable *rt;
···
 static inline struct rtable *ip_route_newports(struct flowi4 *fl4, struct rtable *rt,
 					       __be16 orig_sport, __be16 orig_dport,
 					       __be16 sport, __be16 dport,
-					       struct sock *sk)
+					       const struct sock *sk)
 {
 	if (sport != orig_sport || dport != orig_dport) {
 		fl4->fl4_dport = dport;