northd: fix lflow grouping in build_lb_rules

Do not group lflows if the corresponding datapath does not run
copp meters and the previous one has an associated copp entry.
In order to fix the issue reset lflow_ref pointer to NULL if the logical
router/logical flow runs a copp meter.

Fixes: deec972 ("northd: optimize build_lb_rules routine")
Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Acked-by: Dumitru Ceara <dceara@redhat.com>
Signed-off-by: Numan Siddique <numans@ovn.org>
(cherry picked from commit 664f2aa)

northd/northd.c

@@ -6865,14 +6865,15 @@ build_lb_rules(struct hmap *lflows, struct ovn_northd_lb *lb,
             if (reject) {
                 meter = copp_meter_get(COPP_REJECT, od->nbs->copp,
                                        meter_groups);
-            } else if (ovn_dp_group_add_with_reference(lflow_ref, od)) {
-                continue;
             }
-            lflow_ref = ovn_lflow_add_at_with_hash(lflows, od,
-                    S_SWITCH_IN_LB, priority,
-                    ds_cstr(match), ds_cstr(action),
-                    NULL, meter, &lb->nlb->header_,
-                    OVS_SOURCE_LOCATOR, hash);
+            if (meter || !ovn_dp_group_add_with_reference(lflow_ref, od)) {
+                struct ovn_lflow *lflow = ovn_lflow_add_at_with_hash(
+                        lflows, od, S_SWITCH_IN_LB, priority,
+                        ds_cstr(match), ds_cstr(action),
+                        NULL, meter, &lb->nlb->header_,
+                        OVS_SOURCE_LOCATOR, hash);
+                lflow_ref = meter ? NULL : lflow;
+            }
         }
     }
 }