zebra: properly set the NEXTHOP_GROUP_VALID flag

Properly set the NEXTHOP_GROUP_VALID flag and use it
as a conditional for installation decisions for individual
nexthop and groups containing it.

We set the NEXTHOP_GROUP_VALID flag it is:

1) A fully resolved active nexthop
or
2) Its a group that contains at least one VALID NHE

Signed-off-by: Stephen Worley <sworley@cumulusnetworks.com>
(cherry picked from commit 086e4e02f5fe02849ad9a6c17472094c1c1cbd98)

diff --git a/zebra/zebra_nhg.c b/zebra/zebra_nhg.c
index 7bdfc12a45529c5046df137a9bf8d4c2ca5e427e..717f03d890a12f148f73fa46410fb745bbee4bc2 100644 (file)
--- a/zebra/zebra_nhg.c
+++ b/zebra/zebra_nhg.c
@@ -1709,6 +1709,36 @@ static unsigned nexthop_active_check(struct route_node *rn,
        return CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_ACTIVE);
 }
 
+/* Helper function called after resolution to walk nhg rb trees
+ * and toggle the NEXTHOP_GROUP_VALID flag if the nexthop
+ * is active on singleton NHEs.
+ */
+static bool zebra_nhg_set_valid_if_active(struct nhg_hash_entry *nhe)
+{
+       struct nhg_connected *rb_node_dep = NULL;
+       bool valid = false;
+
+       if (!zebra_nhg_depends_is_empty(nhe)) {
+               /* Is at least one depend valid? */
+               frr_each(nhg_connected_tree, &nhe->nhg_depends, rb_node_dep) {
+                       if (zebra_nhg_set_valid_if_active(rb_node_dep->nhe))
+                               valid = true;
+               }
+
+               goto done;
+       }
+
+       /* should be fully resolved singleton at this point */
+       if (CHECK_FLAG(nhe->nhg->nexthop->flags, NEXTHOP_FLAG_ACTIVE))
+               valid = true;
+
+done:
+       if (valid)
+               SET_FLAG(nhe->flags, NEXTHOP_GROUP_VALID);
+
+       return valid;
+}
+
 /*
  * Iterate over all nexthops of the given RIB entry and refresh their
  * ACTIVE flag.  If any nexthop is found to toggle the ACTIVE flag,
@@ -1783,8 +1813,11 @@ int nexthop_active_update(struct route_node *rn, struct route_entry *re)
                route_entry_update_nhe(re, new_nhe);
        }
 
+       /* Walk the NHE depends tree and toggle NEXTHOP_GROUP_VALID
+        * flag where appropriate.
+        */
        if (curr_active)
-               SET_FLAG(re->nhe->flags, NEXTHOP_GROUP_VALID);
+               zebra_nhg_set_valid_if_active(re->nhe);
 
        /*
         * Do not need these nexthops anymore since they
@@ -1843,6 +1876,15 @@ static uint8_t zebra_nhg_nhe2grp_internal(struct nh_grp *grp,
                        /* This is a group within a group */
                        i = zebra_nhg_nhe2grp_internal(grp, i, depend, max_num);
                } else {
+                       if (!CHECK_FLAG(depend->flags, NEXTHOP_GROUP_VALID)) {
+                               if (IS_ZEBRA_DEBUG_RIB_DETAILED
+                                   || IS_ZEBRA_DEBUG_NHG)
+                                       zlog_debug(
+                                               "%s: Nexthop ID (%u) not valid, not appending to dataplane install group",
+                                               __func__, depend->id);
+                               continue;
+                       }
+
                        /* If the nexthop not installed/queued for install don't
                         * put in the ID array.
                         */
@@ -1902,7 +1944,8 @@ void zebra_nhg_install_kernel(struct nhg_hash_entry *nhe)
                zebra_nhg_install_kernel(rb_node_dep->nhe);
        }
 
-       if (!CHECK_FLAG(nhe->flags, NEXTHOP_GROUP_INSTALLED)
+       if (CHECK_FLAG(nhe->flags, NEXTHOP_GROUP_VALID)
+           && !CHECK_FLAG(nhe->flags, NEXTHOP_GROUP_INSTALLED)
            && !CHECK_FLAG(nhe->flags, NEXTHOP_GROUP_QUEUED)) {
                /* Change its type to us since we are installing it */
                nhe->type = ZEBRA_ROUTE_NHG;