[IPSEC]: Implement xfrm type module autoloading.

net/xfrm/xfrm_policy.c

@@ -15,6 +15,7 @@
 
 #include <linux/config.h>
 #include <linux/slab.h>
+#include <linux/kmod.h>
 #include <net/xfrm.h>
 #include <net/ip.h>
 
@@ -74,16 +75,25 @@ struct xfrm_type *xfrm_get_type(u8 proto, unsigned short family)
 	struct xfrm_policy_afinfo *afinfo = xfrm_policy_get_afinfo(family);
 	struct xfrm_type_map *typemap;
 	struct xfrm_type *type;
+	int modload_attempted = 0;
 
 	if (unlikely(afinfo == NULL))
 		return NULL;
 	typemap = afinfo->type_map;
 
+retry:
 	read_lock(&typemap->lock);
 	type = typemap->map[proto];
 	if (unlikely(type && !try_module_get(type->owner)))
 		type = NULL;
 	read_unlock(&typemap->lock);
+	if (!type && !modload_attempted) {
+		request_module("xfrm-type-%d-%d",
+			       (int) family, (int) proto);
+		modload_attempted = 1;
+		goto retry;
+	}
+
 	xfrm_policy_put_afinfo(afinfo);
 	return type;
 }