Prevent re-entrant walks on an adjacency.

The re-entrant walks were caused when the walk from an IP adj updated a fib_netry with an MPLS adj which in turn triggers a walk of the IP adj. Re-entrant walks do unnecessary work.
also fixed a walk merge issue where the encountered walk should only be checked for equivalence woth the most recent alk, not any in the list. Otherwise an UO,DOWN,UP beceoms (2*)UP,DOWN

Change-Id: Ib8b27f055dc6c1366d33740276d1c26cd314220a
Signed-off-by: Neale Ranns <nranns@cisco.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/vnet/vnet/ip/lookup.h b/vnet/vnet/ip/lookup.h
index a609e2fe7c0..4b6aaa10da9 100644
--- a/vnet/vnet/ip/lookup.h
+++ b/vnet/vnet/ip/lookup.h
@@ -168,6 +168,17 @@ typedef void (*adj_midchain_fixup_t)(vlib_main_t * vm,
 				     struct ip_adjacency_t_ *adj,
 				     vlib_buffer_t * b0);
 
+/**
+ * @brief Flags on an IP adjacency
+ */
+typedef enum ip_adjacency_flags_t_
+{
+    /**
+     * Currently a sync walk is active. Used to prevent re-entrant walking
+     */
+    IP_ADJ_SYNC_WALK_ACTIVE = (1 << 0),
+} ip_adjacency_flags_t;
+
 /** @brief IP unicast adjacency.
     @note cache aligned.
 */
@@ -254,6 +265,12 @@ typedef struct ip_adjacency_t_ {
    * remaining cachelines
    */
   fib_node_t ia_node;
+
+  /**
+   * Flags on the adjacency
+   */
+  ip_adjacency_flags_t ia_flags;
+
 } ip_adjacency_t;
 
 STATIC_ASSERT((STRUCT_OFFSET_OF(ip_adjacency_t, cacheline0) == 0),