l2tp: define parameters of l2tp_tunnel_find*() as "const"

BugLink: https://bugs.launchpad.net/bugs/1883916

commit 2f858b92 upstream.

l2tp_tunnel_find() and l2tp_tunnel_find_nth() don't modify "net".
Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Giuliano Procida <gprocida@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

net/l2tp/l2tp_core.c

@@ -378,7 +378,7 @@ static int l2tp_session_add_to_tunnel(struct l2tp_tunnel *tunnel,
 
 /* Lookup a tunnel by id
  */
-struct l2tp_tunnel *l2tp_tunnel_find(struct net *net, u32 tunnel_id)
+struct l2tp_tunnel *l2tp_tunnel_find(const struct net *net, u32 tunnel_id)
 {
 	struct l2tp_tunnel *tunnel;
 	struct l2tp_net *pn = l2tp_pernet(net);
@@ -396,7 +396,7 @@ struct l2tp_tunnel *l2tp_tunnel_find(struct net *net, u32 tunnel_id)
 }
 EXPORT_SYMBOL_GPL(l2tp_tunnel_find);
 
-struct l2tp_tunnel *l2tp_tunnel_find_nth(struct net *net, int nth)
+struct l2tp_tunnel *l2tp_tunnel_find_nth(const struct net *net, int nth)
 {
 	struct l2tp_net *pn = l2tp_pernet(net);
 	struct l2tp_tunnel *tunnel;

net/l2tp/l2tp_core.h

@@ -244,8 +244,8 @@ struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth,
 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);
+struct l2tp_tunnel *l2tp_tunnel_find(const struct net *net, u32 tunnel_id);
+struct l2tp_tunnel *l2tp_tunnel_find_nth(const struct net *net, int nth);
 
 int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id,
 		       u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg,