l2tp: auto load type modules

It should not be necessary to do explicit module loading when
configuring L2TP. Modules should be loaded as needed instead
(as is done already with netlink and other tunnel types).

This patch adds a new module alias type and code to load
the sub module on demand.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 12 insertions, 0 deletions

diff --git a/net/l2tp/l2tp_core.h b/net/l2tp/l2tp_core.h
index 68aa9ffd4ae4..5871537af387 100644
--- a/net/l2tp/l2tp_core.h
+++ b/net/l2tp/l2tp_core.h
@@ -321,4 +321,7 @@ do {									\
 #define l2tp_dbg(ptr, type, fmt, ...)                                   \
         l2tp_printk(ptr, type, pr_debug, fmt, ##__VA_ARGS__)
 
+#define MODULE_ALIAS_L2TP_PWTYPE(type) \
+        MODULE_ALIAS("net-l2tp-type-" __stringify(type))
+
 #endif /* _L2TP_CORE_H_ */
diff --git a/net/l2tp/l2tp_eth.c b/net/l2tp/l2tp_eth.c
index 4b552873b556..e253c26f31ac 100644
--- a/net/l2tp/l2tp_eth.c
+++ b/net/l2tp/l2tp_eth.c
@@ -358,3 +358,4 @@ MODULE_LICENSE("GPL");
 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
 MODULE_DESCRIPTION("L2TP ethernet pseudowire driver");
 MODULE_VERSION("1.0");
+MODULE_ALIAS_L2TP_PWTYPE(5);
diff --git a/net/l2tp/l2tp_netlink.c b/net/l2tp/l2tp_netlink.c
index 9e13c2ff8789..f93c5be612a7 100644
--- a/net/l2tp/l2tp_netlink.c
+++ b/net/l2tp/l2tp_netlink.c
@@ -576,6 +576,13 @@ static int l2tp_nl_cmd_session_create(struct sk_buff *skb, struct genl_info *inf
         if (info->attrs[L2TP_ATTR_MRU])
                 cfg.mru = nla_get_u16(info->attrs[L2TP_ATTR_MRU]);
 
+#ifdef CONFIG_MODULES
+        if (l2tp_nl_cmd_ops[cfg.pw_type] == NULL) {
+                genl_unlock();
+                request_module("net-l2tp-type-%u", cfg.pw_type);
+                genl_lock();
+        }
+#endif
         if ((l2tp_nl_cmd_ops[cfg.pw_type] == NULL) ||
             (l2tp_nl_cmd_ops[cfg.pw_type]->session_create == NULL)) {
                 ret = -EPROTONOSUPPORT;
diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c
index f56c9f69e9f2..1ad18c55064c 100644
--- a/net/l2tp/l2tp_ppp.c
+++ b/net/l2tp/l2tp_ppp.c
@@ -1863,3 +1863,4 @@ MODULE_DESCRIPTION("PPP over L2TP over UDP");
 MODULE_LICENSE("GPL");
 MODULE_VERSION(PPPOL2TP_DRV_VERSION);
 MODULE_ALIAS("pppox-proto-" __stringify(PX_PROTO_OL2TP));
+MODULE_ALIAS_L2TP_PWTYPE(11);