[PATCH net-next 1/3] lwtunnel: autoload of lwt modules

[Robert Shearman]

The lwt implementations using net devices can autoload using the
existing mechanism using IFLA_INFO_KIND. However, there's no mechanism
that lwt modules not using net devices can use.

Therefore, add the ability to autoload modules registering lwt
operations for lwt implementations not using a net device so that
users don't have to manually load the modules.

Signed-off-by: Robert Shearman <rshea...@brocade.com>
---
 include/net/lwtunnel.h |  4 +++-
 net/core/lwtunnel.c    | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/include/net/lwtunnel.h b/include/net/lwtunnel.h
index 66350ce3e955..e9f116e29c22 100644
--- a/include/net/lwtunnel.h
+++ b/include/net/lwtunnel.h
@@ -170,6 +170,8 @@ static inline int lwtunnel_input(struct sk_buff *skb)
        return -EOPNOTSUPP;
 }
 
-#endif
+#endif /* CONFIG_LWTUNNEL */
+
+#define MODULE_ALIAS_RTNL_LWT(encap_type) MODULE_ALIAS("rtnl-lwt-" 
__stringify(encap_type))
 
 #endif /* __NET_LWTUNNEL_H */
diff --git a/net/core/lwtunnel.c b/net/core/lwtunnel.c
index 299cfc24d888..8ef5e5cec03e 100644
--- a/net/core/lwtunnel.c
+++ b/net/core/lwtunnel.c
@@ -27,6 +27,30 @@
 #include <net/rtnetlink.h>
 #include <net/ip6_fib.h>
 
+#ifdef CONFIG_MODULES
+
+static const char *lwtunnel_encap_str(enum lwtunnel_encap_types encap_type)
+{
+       switch (encap_type) {
+       case LWTUNNEL_ENCAP_MPLS:
+               return "LWTUNNEL_ENCAP_MPLS";
+       case LWTUNNEL_ENCAP_IP:
+               return "LWTUNNEL_ENCAP_IP";
+       case LWTUNNEL_ENCAP_ILA:
+               return "LWTUNNEL_ENCAP_ILA";
+       case LWTUNNEL_ENCAP_IP6:
+               return "LWTUNNEL_ENCAP_IP6";
+       case LWTUNNEL_ENCAP_NONE:
+       case __LWTUNNEL_ENCAP_MAX:
+               /* should not have got here */
+               break;
+       }
+       WARN_ON(1);
+       return "LWTUNNEL_ENCAP_NONE";
+}
+
+#endif /* CONFIG_MODULES */
+
 struct lwtunnel_state *lwtunnel_state_alloc(int encap_len)
 {
        struct lwtunnel_state *lws;
@@ -85,6 +109,14 @@ int lwtunnel_build_state(struct net_device *dev, u16 
encap_type,
        ret = -EOPNOTSUPP;
        rcu_read_lock();
        ops = rcu_dereference(lwtun_encaps[encap_type]);
+#ifdef CONFIG_MODULES
+       if (!ops) {
+               rcu_read_unlock();
+               request_module("rtnl-lwt-%s", lwtunnel_encap_str(encap_type));
+               rcu_read_lock();
+               ops = rcu_dereference(lwtun_encaps[encap_type]);
+       }
+#endif
        if (likely(ops && ops->build_state))
                ret = ops->build_state(dev, encap, family, cfg, lws);
        rcu_read_unlock();
-- 
2.1.4