staging: lustre: handle lnet_check_routes() errors

After adding a route, lnet_check_routes() is called to ensure that
the route added doesn't invalidate the routing configuration.  If
lnet_check_routes() fails then the route just added, which caused the
current configuration to be invalidated is deleted, and an error
is returned to the user.
Signed-off-by: Amir Shehata <amir.shehata@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-6218
Reviewed-on: http://review.whamcloud.com/13445Reviewed-by: Liang Zhen <liang.zhen@intel.com>
Reviewed-by: Doug Oucharek <doug.s.oucharek@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lnet/lnet/api-ni.c

@@ -1907,8 +1907,14 @@ LNetCtl(unsigned int cmd, void *arg)
 				    config->cfg_config_u.cfg_route.rtr_hop,
 				    config->cfg_nid,
 				    config->cfg_config_u.cfg_route.rtr_priority);
+		if (!rc) {
+			rc = lnet_check_routes();
+			if (rc)
+				lnet_del_route(config->cfg_net,
+					       config->cfg_nid);
+		}
 		mutex_unlock(&the_lnet.ln_api_mutex);
-		return rc ? rc : lnet_check_routes();
+		return rc;
 
 	case IOC_LIBCFS_DEL_ROUTE:
 		config = arg;