zebra: don't include backup nhs in main nhe dependency tree

We don't want to install backup nexthops - yet - as part of the
nexthop-id-based kernel interactions on netlink platforms. Avoid
mixing backup and primary nexthops in the tree of dependencies
in the ecmp cases.

Signed-off-by: Mark Stapp <mjs@voltanet.io>

diff --git a/zebra/zebra_nhg.c b/zebra/zebra_nhg.c
index 47843484c88c6986f048328b272e887aaafb6fc5..fceddcb7459dc0c346ed6f4ba231e1e0cb622911 100644 (file)
--- a/zebra/zebra_nhg.c
+++ b/zebra/zebra_nhg.c
@@ -638,7 +638,7 @@ static bool zebra_nhe_find(struct nhg_hash_entry **nhe, /* return value */
 {
        bool created = false;
        bool recursive = false;
-       struct nhg_hash_entry *newnhe;
+       struct nhg_hash_entry *newnhe, *backup_nhe;
        struct nexthop *nh = NULL;
 
        if (IS_ZEBRA_DEBUG_NHG_DETAIL)
@@ -724,14 +724,20 @@ static bool zebra_nhe_find(struct nhg_hash_entry **nhe, /* return value */
                }
        }
 
-       /* If there are backup nexthops, add them to the
-        * depends tree also. The rules here are a little different.
-        */
+       if (recursive)
+               SET_FLAG((*nhe)->flags, NEXTHOP_GROUP_RECURSIVE);
+
        if (zebra_nhg_get_backup_nhg(newnhe) == NULL ||
            zebra_nhg_get_backup_nhg(newnhe)->nexthop == NULL)
-               goto backups_done;
+               goto done;
+
+       /* If there are backup nexthops, add them to the backup
+        * depends tree. The rules here are a little different.
+        */
+       recursive = false;
+       backup_nhe = newnhe->backup_info->nhe;
 
-       nh = zebra_nhg_get_backup_nhg(newnhe)->nexthop;
+       nh = backup_nhe->nhg.nexthop;
 
        /* Singleton recursive NH */
        if (nh->next == NULL &&
@@ -741,7 +747,7 @@ static bool zebra_nhe_find(struct nhg_hash_entry **nhe, /* return value */
                                   __func__, nh);
 
                /* Single recursive nexthop */
-               handle_recursive_depend(&newnhe->nhg_depends,
+               handle_recursive_depend(&backup_nhe->nhg_depends,
                                        nh->resolved, afi);
                recursive = true;
        } else {
@@ -754,15 +760,13 @@ static bool zebra_nhe_find(struct nhg_hash_entry **nhe, /* return value */
                                                      NEXTHOP_FLAG_RECURSIVE) ?
                                           "(R)" : "");
 
-                       depends_find_add(&newnhe->nhg_depends,
+                       depends_find_add(&backup_nhe->nhg_depends,
                                         nh, afi);
                }
        }
 
-backups_done:
-
        if (recursive)
-               SET_FLAG((*nhe)->flags, NEXTHOP_GROUP_RECURSIVE);
+               SET_FLAG(backup_nhe->flags, NEXTHOP_GROUP_RECURSIVE);
 
 done:
 
@@ -2402,6 +2406,16 @@ static uint8_t zebra_nhg_nhe2grp_internal(struct nh_grp *grp,
                }
        }
 
+       if (nhe->backup_info == NULL || nhe->backup_info->nhe == NULL)
+               goto done;
+
+       /* TODO -- For now, we are not trying to use or install any
+        * backup info in this nexthop-id path: we aren't prepared
+        * to use the backups here yet. We're just debugging what we find.
+        */
+       if (IS_ZEBRA_DEBUG_NHG_DETAIL)
+               zlog_debug("%s: skipping backup nhe",  __func__);
+
 done:
        return i;
 }