Nest: Fix race condition during reconfiguration, part 2

If export filter is changed during reconfiguration and a route disappears
between reconfiguration and refeed (e.g., if the route is a static route
also removed during the reconfiguration), the route is not withdrawn.

The issue was fixed for regular channels by an earlier patch. This patch
fixes the issue for channels in RA_ACCEPTED mode (first-pass-the-filter),
used by BGP with 'secondary' option.

diff --git a/nest/rt-table.c b/nest/rt-table.c
index 07bb0b127e51d91eb2168c1aa163e97d073bcfd2..83f0e71309c429f2b9fcfcdbb437e3ad41edbfea 100644 (file)
--- a/nest/rt-table.c
+++ b/nest/rt-table.c
@@ -543,8 +543,18 @@ rt_notify_accepted(struct announce_hook *ah, net *net, rte *new_changed, rte *ol
    *
    * - We found new_best the same as new_changed, therefore it cannot
    *   be old_best and we have to continue search for old_best.
+   *
+   * There is also a hack to ensure consistency in case of changed filters.
+   * It does not find the proper old_best, just selects a non-NULL route.
    */
 
+  /* Hack for changed filters */
+  if (old_changed && (old_changed->lastmod <= ah->last_out_filter_change))
+    {
+      old_best = old_changed;
+      goto found;
+    }
+
   /* First case */
   if (old_meet)
     if (old_best = export_filter(ah, old_changed, &old_free, NULL, 1))