ematch: Fix auto-loading of ematch modules.

In tcf_em_validate(), after calling request_module() to load the
kind-specific module, set em->ops to NULL before returning -EAGAIN, so
that module_put() is not called again by tcf_em_tree_destroy().

Signed-off-by: Ignacy Gawędzki <ignacy.gawedzki@green-communications.fr>
Acked-by: Cong Wang <cwang@twopensource.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/ematch.c b/net/sched/ematch.c
index 6742200..fbb7ebf 100644
--- a/net/sched/ematch.c
+++ b/net/sched/ematch.c
@@ -228,6 +228,7 @@
 				 * to replay the request.
 				 */
 				module_put(em->ops->owner);
+				em->ops = NULL;
 				err = -EAGAIN;
 			}
 #endif