Change ARP and IP6-ND nodes to use interface-output node for output

The current mechanism for setting up arp-input and ip6-discover-neighbor
output nodes for interfaces using their interface link up/down callback
function is inefficient and has potential timing issue, as observed for
bonded interface. Now both nodes will setup output interface sw_if_index
in the the sw_if_index[VLIB_TX] field of current packet buffer and then
use the interface-ouput node to tx the packet.

One side effect is that vlib_node_add_next_with_slot() needs to be
modified to allow the same output node-id to be put at the specified
slot, even if another slot contain that same node-id already exist. This
requirement is caused by BVI support where all loopback interfaces set
up as BVIs will have the same output node-id being l2-input while, for
output-interface node, the output slot must match the hw_if_index of the
interface.

Change-Id: I18bd1d4fe9bea047018796f7b8a4d4c20ee31d6e
Signed-off-by: John Lo <loj@cisco.com>

1 files changed, 3 insertions, 27 deletions

diff --git a/vnet/vnet/ip/ip6_forward.c b/vnet/vnet/ip/ip6_forward.c
index a79bae6905a..4a161e7271c 100644
--- a/vnet/vnet/ip/ip6_forward.c
+++ b/vnet/vnet/ip/ip6_forward.c
@@ -1768,6 +1768,7 @@ void ip6_register_protocol (u32 protocol, u32 node_index)
 
 typedef enum {
   IP6_DISCOVER_NEIGHBOR_NEXT_DROP,
+  IP6_DISCOVER_NEIGHBOR_NEXT_REPLY_TX,
   IP6_DISCOVER_NEIGHBOR_N_NEXT,
 } ip6_discover_neighbor_next_t;
 
@@ -1933,11 +1934,7 @@ ip6_discover_neighbor (vlib_main_t * vm,
                                      sizeof (ethernet_header_t));
 	    vlib_buffer_advance (b0, -adj0->rewrite_header.data_bytes);
 
-            /* $$$$ hack in case next0 == 0 */
-            b0->error = node->errors[IP6_DISCOVER_NEIGHBOR_ERROR_DROP];
-	    next0 = 
-              vec_elt (im->discover_neighbor_next_index_by_hw_if_index, 
-                       hw_if0->hw_if_index);
+	    next0 = IP6_DISCOVER_NEIGHBOR_NEXT_REPLY_TX;
 
 	    vlib_set_next_frame_buffer (vm, node, next0, bi0);
 	  }
@@ -1969,32 +1966,11 @@ VLIB_REGISTER_NODE (ip6_discover_neighbor_node) = {
   .n_next_nodes = IP6_DISCOVER_NEIGHBOR_N_NEXT,
   .next_nodes = {
     [IP6_DISCOVER_NEIGHBOR_NEXT_DROP] = "error-drop",
+    [IP6_DISCOVER_NEIGHBOR_NEXT_REPLY_TX] = "interface-output",
   },
 };
 
 clib_error_t *
-ip6_discover_neighbor_hw_interface_link_up_down (vnet_main_t * vnm,
-                                                 u32 hw_if_index,
-                                                 u32 flags)
-{
-  vlib_main_t * vm = vnm->vlib_main;
-  ip6_main_t * im = &ip6_main;
-  vnet_hw_interface_t * hw_if;
-
-  hw_if = vnet_get_hw_interface (vnm, hw_if_index);
-
-  vec_validate_init_empty 
-    (im->discover_neighbor_next_index_by_hw_if_index, hw_if_index, 0);
-  im->discover_neighbor_next_index_by_hw_if_index[hw_if_index]
-    = vlib_node_add_next (vm, ip6_discover_neighbor_node.index,
-                          hw_if->output_node_index);
-  return 0;
-}
-
-VNET_HW_INTERFACE_LINK_UP_DOWN_FUNCTION 
-(ip6_discover_neighbor_hw_interface_link_up_down);
-
-clib_error_t *
 ip6_probe_neighbor (vlib_main_t * vm, ip6_address_t * dst, u32 sw_if_index)
 {
   vnet_main_t * vnm = vnet_get_main();