bgpd: clarify nht path validity logic

path_valid is the previous path validity state. Setting BGP_PATH_VALID to true if path_valid is false is confusing. Clarify the logic. Signed-off-by: Louis Scalbert <[email protected]>
FRRouting · Feb 9, 2022 · f3fc37a · f3fc37a
1 parent 74309be
commit f3fc37a
Showing 1 changed file with 13 additions and 12 deletions.
diff --git a/bgpd/bgp_nht.c b/bgpd/bgp_nht.c
@@ -970,6 +970,7 @@ void evaluate_paths(struct bgp_nexthop_cache *bnc)
 	safi_t safi;
 	struct bgp *bgp_path;
 	const struct prefix *p;
+	bool path_valid_changed, bnc_is_valid_nexthop;
 
 	if (BGP_DEBUG(nht, NHT)) {
 		char buf[PREFIX2STR_BUFFER];
@@ -1019,8 +1020,7 @@ void evaluate_paths(struct bgp_nexthop_cache *bnc)
 		 * do not check for a valid label.
 		 */
 
-		bool bnc_is_valid_nexthop = false;
-		bool path_valid = false;
+		bnc_is_valid_nexthop = false;
 
 		if (safi == SAFI_UNICAST && path->sub_type == BGP_ROUTE_IMPORTED
 		    && path->extra && path->extra->num_labels
@@ -1076,23 +1076,24 @@ void evaluate_paths(struct bgp_nexthop_cache *bnc)
 		    || path->attr->srte_color != 0)
 			SET_FLAG(path->flags, BGP_PATH_IGP_CHANGED);
 
-		path_valid = CHECK_FLAG(path->flags, BGP_PATH_VALID);
-		if (path_valid != bnc_is_valid_nexthop) {
-			if (path_valid) {
-				/* No longer valid, clear flag */
-				bgp_aggregate_decrement(bgp_path, p, path, afi,
-							safi);
-				bgp_path_info_unset_flag(dest, path,
-							 BGP_PATH_VALID);
-			} else {
+		path_valid_changed = CHECK_FLAG(path->flags, BGP_PATH_VALID) !=
+				     bnc_is_valid_nexthop;
+		if (path_valid_changed) {
+			if (bnc_is_valid_nexthop) {
 				/* Path becomes valid, set flag */
 				bgp_path_info_set_flag(dest, path,
 						       BGP_PATH_VALID);
 				bgp_aggregate_increment(bgp_path, p, path, afi,
 							safi);
+			} else {
+				/* No longer valid, clear flag */
+				bgp_aggregate_decrement(bgp_path, p, path, afi,
+							safi);
+				bgp_path_info_unset_flag(dest, path,
+							 BGP_PATH_VALID);
 			}
 		}
-		if ((path_valid != bnc_is_valid_nexthop ||
+		if ((path_valid_changed ||
 		     CHECK_FLAG(path->flags, BGP_PATH_IGP_CHANGED)) &&
 		    safi == SAFI_EVPN &&
 		    bgp_evpn_is_prefix_nht_supported(