zebra: keep table route entries at vrf disabling

At VRF disabling, keep the route entries that was associated to its
table ID but not to the VRF itself. Kernel flushes these entries so we
need to reinstall them.

Signed-off-by: Louis Scalbert <louis.scalbert@6wind.com>

zebra/zebra_vrf.c

@@ -184,12 +184,18 @@ static void zebra_vrf_disable_update_vrfid(struct zebra_vrf *zvrf, afi_t afi,
 		/* Assign the kernel route entries to the default VRF,
 		 * even though they are not actually owned by it.
 		 *
-		 * Remove route nodes that have been created by FRR daemons.
-		 * They are not needed if the VRF is disabled.
+		 * Remove route nodes that were created by FRR daemons,
+		 * unless they are associated with the table rather than the VRF.
+		 * Routes associated with the VRF are not needed once the VRF is
+		 * disabled.
 		 */
 		RNODE_FOREACH_RE_SAFE (rn, re, nre) {
-			if (re->type == ZEBRA_ROUTE_KERNEL) {
+			if (re->type == ZEBRA_ROUTE_KERNEL ||
+			    CHECK_FLAG(re->flags, ZEBRA_FLAG_TABLEID)) {
 				nexthop_vrf_update(rn, re, VRF_DEFAULT);
+				if (CHECK_FLAG(re->flags, ZEBRA_FLAG_TABLEID))
+					/* reinstall routes */
+					rib_install_kernel(rn, re, NULL);
 				rn_delete = false;
 			} else
 				rib_unlink(rn, re);