northd: fix lb_action when there are no active backends for lb health…

…_check

Fix the following warning reported by ovn-controller when there are no
active backends for lb health_check and selection_fields have been
configured for hash computation

flow|WARN|error parsing actions "drop; hash_fields="ip_dst,ip_src,tcp_dst,tcp_src");":
Syntax error at `hash_fields' expecting end of input.

Fixes: 5af304e ("Support selection fields in load balancer.")
Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Signed-off-by: 0-day Robot <robot@bytheb.org>

northd/ovn-northd.c

@@ -3598,6 +3598,8 @@ static void build_lb_vip_ct_lb_actions(struct lb_vip *lb_vip,
                                        struct ds *action,
                                        char *selection_fields)
 {
+    bool skip_hash_fields = false;
+
     if (lb_vip->health_check) {
         ds_put_cstr(action, "ct_lb(backends=");
 
@@ -3616,6 +3618,7 @@ static void build_lb_vip_ct_lb_actions(struct lb_vip *lb_vip,
         }
 
         if (!n_active_backends) {
+            skip_hash_fields = true;
             ds_clear(action);
             ds_put_cstr(action, "drop;");
         } else {
@@ -3626,7 +3629,7 @@ static void build_lb_vip_ct_lb_actions(struct lb_vip *lb_vip,
         ds_put_format(action, "ct_lb(backends=%s);", lb_vip->backend_ips);
     }
 
-    if (selection_fields && selection_fields[0]) {
+    if (!skip_hash_fields && selection_fields && selection_fields[0]) {
         ds_chomp(action, ';');
         ds_chomp(action, ')');
         ds_put_format(action, "; hash_fields=\"%s\");", selection_fields);