fib: Always honour flow hash flag

Type: fix

Signed-off-by: Neale Ranns <neale@graphiant.com>
Change-Id: Id7b27edf3712aaa3c277e752b9ca78bb91d184a1

4 files changed, 50 insertions, 17 deletions

diff --git a/src/vnet/adj/.clang-format b/src/vnet/adj/.clang-format
new file mode 100644
index 00000000000..9d159247d51
--- /dev/null
+++ b/src/vnet/adj/.clang-format
@@ -0,0 +1,2 @@
+DisableFormat: true
+SortIncludes: false
diff --git a/src/vnet/adj/adj_midchain.c b/src/vnet/adj/adj_midchain.c
index 93cfb550e3e..a21cd21ea25 100644
--- a/src/vnet/adj/adj_midchain.c
+++ b/src/vnet/adj/adj_midchain.c
@@ -623,8 +623,23 @@ adj_nbr_midchain_stack_on_fib_entry (adj_index_t ai,
                 choice = load_balance_get_bucket_i (lb, hash & lb->lb_n_buckets_minus_1);
                 dpo_copy (&tmp, choice);
             }
-            else if (adj->ia_flags & ADJ_FLAG_MIDCHAIN_FIXUP_FLOW_HASH)
+            else if (lb->lb_n_buckets > 1)
             {
+                /*
+                 * the client has chosen not to use the stacking to select a
+                 * bucket, and there are more than one buckets. there's no
+                 * value in using the midchain's fixed rewrite string to select
+                 * the path, so force a flow hash on the inner.
+                 */
+                adj->rewrite_header.flags |= VNET_REWRITE_FIXUP_FLOW_HASH;
+            }
+
+            if (adj->ia_flags & ADJ_FLAG_MIDCHAIN_FIXUP_FLOW_HASH)
+            {
+                /*
+                 * The client, for reasons unbeknownst to adj, wants to force
+                 * a flow hash on the inner, we will oblige.
+                 */
                 adj->rewrite_header.flags |= VNET_REWRITE_FIXUP_FLOW_HASH;
             }
         }
diff --git a/src/vnet/gre/gre.c b/src/vnet/gre/gre.c
index a355a224ee1..0669c676bf5 100644
--- a/src/vnet/gre/gre.c
+++ b/src/vnet/gre/gre.c
@@ -410,11 +410,15 @@ gre_update_adj (vnet_main_t * vnm, u32 sw_if_index, adj_index_t ai)
 
   ti = gm->tunnel_index_by_sw_if_index[sw_if_index];
   t = pool_elt_at_index (gm->tunnels, ti);
+  af = ADJ_FLAG_NONE;
 
-  if (t->flags & TUNNEL_ENCAP_DECAP_FLAG_ENCAP_INNER_HASH)
-    af = ADJ_FLAG_MIDCHAIN_FIXUP_FLOW_HASH;
-  else
-    af = ADJ_FLAG_MIDCHAIN_IP_STACK;
+  /*
+   * the user has not requested that the load-balancing be based on
+   * a flow hash of the inner packet. so use the stacking to choose
+   * a path.
+   */
+  if (!(t->flags & TUNNEL_ENCAP_DECAP_FLAG_ENCAP_INNER_HASH))
+    af |= ADJ_FLAG_MIDCHAIN_IP_STACK;
 
   if (VNET_LINK_ETHERNET == adj_get_link_type (ai))
     af |= ADJ_FLAG_MIDCHAIN_NO_COUNT;
@@ -435,10 +439,15 @@ mgre_mk_complete_walk (adj_index_t ai, void *data)
   mgre_walk_ctx_t *ctx = data;
   adj_flags_t af;
 
-  if (ctx->t->flags & TUNNEL_ENCAP_DECAP_FLAG_ENCAP_INNER_HASH)
-    af = ADJ_FLAG_MIDCHAIN_FIXUP_FLOW_HASH;
-  else
-    af = ADJ_FLAG_MIDCHAIN_IP_STACK;
+  af = ADJ_FLAG_NONE;
+
+  /*
+   * the user has not requested that the load-balancing be based on
+   * a flow hash of the inner packet. so use the stacking to choose
+   * a path.
+   */
+  if (!(ctx->t->flags & TUNNEL_ENCAP_DECAP_FLAG_ENCAP_INNER_HASH))
+    af |= ADJ_FLAG_MIDCHAIN_IP_STACK;
 
   adj_nbr_midchain_update_rewrite
     (ai, gre_get_fixup (ctx->t->tunnel_dst.fp_proto,
diff --git a/src/vnet/ipip/ipip.c b/src/vnet/ipip/ipip.c
index d43bcd1cb53..e6ea3ebe79d 100644
--- a/src/vnet/ipip/ipip.c
+++ b/src/vnet/ipip/ipip.c
@@ -335,14 +335,18 @@ ipip_update_adj (vnet_main_t * vnm, u32 sw_if_index, adj_index_t ai)
   ipip_tunnel_t *t;
   adj_flags_t af;
 
+  af = ADJ_FLAG_NONE;
   t = ipip_tunnel_db_find_by_sw_if_index (sw_if_index);
   if (!t)
     return;
 
-  if (t->flags & TUNNEL_ENCAP_DECAP_FLAG_ENCAP_INNER_HASH)
-    af = ADJ_FLAG_MIDCHAIN_FIXUP_FLOW_HASH;
-  else
-    af = ADJ_FLAG_MIDCHAIN_IP_STACK;
+  /*
+   * the user has not requested that the load-balancing be based on
+   * a flow hash of the inner packet. so use the stacking to choose
+   * a path.
+   */
+  if (!(t->flags & TUNNEL_ENCAP_DECAP_FLAG_ENCAP_INNER_HASH))
+    af |= ADJ_FLAG_MIDCHAIN_IP_STACK;
 
   if (VNET_LINK_ETHERNET == adj_get_link_type (ai))
     af |= ADJ_FLAG_MIDCHAIN_NO_COUNT;
@@ -372,10 +376,13 @@ mipip_mk_complete_walk (adj_index_t ai, void *data)
   af = ADJ_FLAG_NONE;
   fixup = ipip_get_fixup (ctx->t, adj_get_link_type (ai), &af);
 
-  if (ctx->t->flags & TUNNEL_ENCAP_DECAP_FLAG_ENCAP_INNER_HASH)
-    af = ADJ_FLAG_MIDCHAIN_FIXUP_FLOW_HASH;
-  else
-    af = ADJ_FLAG_MIDCHAIN_IP_STACK;
+  /*
+   * the user has not requested that the load-balancing be based on
+   * a flow hash of the inner packet. so use the stacking to choose
+   * a path.
+   */
+  if (!(ctx->t->flags & TUNNEL_ENCAP_DECAP_FLAG_ENCAP_INNER_HASH))
+    af |= ADJ_FLAG_MIDCHAIN_IP_STACK;
 
   adj_nbr_midchain_update_rewrite
     (ai, fixup,