[GENETLINK]: Relax dances with genl_lock.

The genl_unregister_family() calls the genl_unregister_mc_groups(), 
which takes and releases the genl_lock and then locks and releases
this lock itself.

Relax this behavior, all the more so the genl_unregister_mc_groups() 
is called from genl_unregister_family() only.
Signed-off-by: NPavel Emelyanov <xemul@openvz.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/netlink/genetlink.c

@@ -230,10 +230,8 @@ static void genl_unregister_mc_groups(struct genl_family *family)
 {
 	struct genl_multicast_group *grp, *tmp;
 
-	genl_lock();
 	list_for_each_entry_safe(grp, tmp, &family->mcast_groups, list)
 		__genl_unregister_mc_group(family, grp);
-	genl_unlock();
 }
 
 /**
@@ -396,10 +394,10 @@ int genl_unregister_family(struct genl_family *family)
 {
 	struct genl_family *rc;
 
-	genl_unregister_mc_groups(family);
-
 	genl_lock();
 
+	genl_unregister_mc_groups(family);
+
 	list_for_each_entry(rc, genl_family_chain(family->id), family_list) {
 		if (family->id != rc->id || strcmp(rc->name, family->name))
 			continue;