Merge pull request FRRouting#16404 from FRRouting/mergify/bp/dev/10.1…

…/pr-16368

bgpd: backpressure - fix to properly remove dest for bgp under deletion (backport FRRouting#16368)

bgpd/bgp_evpn.c

@@ -6332,16 +6332,16 @@ struct bgpevpn *bgp_evpn_new(struct bgp *bgp, vni_t vni,
 void bgp_evpn_free(struct bgp *bgp, struct bgpevpn *vpn)
 {
 	struct bgp_dest *dest = NULL;
-	uint32_t ann_count = zebra_announce_count(&bm->zebra_announce_head);
+	struct bgp_dest *dest_next = NULL;
 
-	while (ann_count) {
-		dest = zebra_announce_pop(&bm->zebra_announce_head);
-		ann_count--;
+	for (dest = zebra_announce_first(&bm->zebra_announce_head); dest;
+	     dest = dest_next) {
+		dest_next = zebra_announce_next(&bm->zebra_announce_head, dest);
 		if (dest->za_vpn == vpn) {
 			bgp_path_info_unlock(dest->za_bgp_pi);
 			bgp_dest_unlock_node(dest);
-		} else
-			zebra_announce_add_tail(&bm->zebra_announce_head, dest);
+			zebra_announce_del(&bm->zebra_announce_head, dest);
+		}
 	}
 
 	bgp_evpn_remote_ip_hash_destroy(vpn);

bgpd/bgpd.c

@@ -3913,21 +3913,34 @@ int bgp_delete(struct bgp *bgp)
 	safi_t safi;
 	int i;
 	struct bgp_dest *dest = NULL;
+	struct bgp_dest *dest_next = NULL;
+	struct bgp_table *dest_table = NULL;
 	struct graceful_restart_info *gr_info;
-	uint32_t ann_count = zebra_announce_count(&bm->zebra_announce_head);
+	uint32_t cnt_before, cnt_after;
 
 	assert(bgp);
 
-	while (ann_count) {
-		dest = zebra_announce_pop(&bm->zebra_announce_head);
-		ann_count--;
-		if (dest->za_bgp_pi->peer->bgp == bgp) {
+	/*
+	 * Iterate the pending dest list and remove all the dest pertaininig to
+	 * the bgp under delete.
+	 */
+	cnt_before = zebra_announce_count(&bm->zebra_announce_head);
+	for (dest = zebra_announce_first(&bm->zebra_announce_head); dest;
+	     dest = dest_next) {
+		dest_next = zebra_announce_next(&bm->zebra_announce_head, dest);
+		dest_table = bgp_dest_table(dest);
+		if (dest_table->bgp == bgp) {
 			bgp_path_info_unlock(dest->za_bgp_pi);
 			bgp_dest_unlock_node(dest);
-		} else
-			zebra_announce_add_tail(&bm->zebra_announce_head, dest);
+			zebra_announce_del(&bm->zebra_announce_head, dest);
+		}
 	}
 
+	cnt_after = zebra_announce_count(&bm->zebra_announce_head);
+	if (BGP_DEBUG(zebra, ZEBRA))
+		zlog_debug("Zebra Announce Fifo cleanup count before %u and after %u during BGP %s deletion",
+			   cnt_before, cnt_after, bgp->name_pretty);
+
 	bgp_soft_reconfig_table_task_cancel(bgp, NULL, NULL);
 
 	/* make sure we withdraw any exported routes */