l2tp: define parameters of l2tp_session_get*() as "const"

Make l2tp_pernet()'s parameter constant, so that l2tp_session_get*() can
declare their "net" variable as "const".
Also constify "ifname" in l2tp_session_get_by_ifname().
Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/l2tp/l2tp_core.c

@@ -120,7 +120,7 @@ static inline struct l2tp_tunnel *l2tp_tunnel(struct sock *sk)
 	return sk->sk_user_data;
 }
 
-static inline struct l2tp_net *l2tp_pernet(struct net *net)
+static inline struct l2tp_net *l2tp_pernet(const struct net *net)
 {
 	BUG_ON(!net);
 
@@ -232,7 +232,7 @@ l2tp_session_id_hash(struct l2tp_tunnel *tunnel, u32 session_id)
 /* Lookup a session. A new reference is held on the returned session.
  * Optionally calls session->ref() too if do_ref is true.
  */
-struct l2tp_session *l2tp_session_get(struct net *net,
+struct l2tp_session *l2tp_session_get(const struct net *net,
 				      struct l2tp_tunnel *tunnel,
 				      u32 session_id, bool do_ref)
 {
@@ -307,7 +307,8 @@ EXPORT_SYMBOL_GPL(l2tp_session_get_nth);
 /* Lookup a session by interface name.
  * This is very inefficient but is only used by management interfaces.
  */
-struct l2tp_session *l2tp_session_get_by_ifname(struct net *net, char *ifname,
+struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net,
+						const char *ifname,
 						bool do_ref)
 {
 	struct l2tp_net *pn = l2tp_pernet(net);

net/l2tp/l2tp_core.h

@@ -230,12 +230,13 @@ static inline struct l2tp_tunnel *l2tp_sock_to_tunnel(struct sock *sk)
 	return tunnel;
 }
 
-struct l2tp_session *l2tp_session_get(struct net *net,
+struct l2tp_session *l2tp_session_get(const struct net *net,
 				      struct l2tp_tunnel *tunnel,
 				      u32 session_id, bool do_ref);
 struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth,
 					  bool do_ref);
-struct l2tp_session *l2tp_session_get_by_ifname(struct net *net, char *ifname,
+struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net,
+						const char *ifname,
 						bool do_ref);
 struct l2tp_tunnel *l2tp_tunnel_find(struct net *net, u32 tunnel_id);
 struct l2tp_tunnel *l2tp_tunnel_find_nth(struct net *net, int nth);