src/vnet/dpo/dpo.c - fdio/vpp - Gitiles

 /*
  * Copyright (c) 2016 Cisco and/or its affiliates.
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at:
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 /**
  * @brief
  * A Data-Path Object is an object that represents actions that are
  * applied to packets are they are switched through VPP.
  *
  * The DPO is a base class that is specialised by other objects to provide
  * concreate actions
  *
  * The VLIB graph nodes are graph of types, the DPO graph is a graph of instances.
  */

 #include <vnet/dpo/dpo.h>
 #include <vnet/ip/lookup.h>
 #include <vnet/ip/format.h>
 #include <vnet/adj/adj.h>

 #include <vnet/dpo/load_balance.h>
 #include <vnet/dpo/mpls_label_dpo.h>
 #include <vnet/dpo/lookup_dpo.h>
 #include <vnet/dpo/drop_dpo.h>
 #include <vnet/dpo/receive_dpo.h>
 #include <vnet/dpo/punt_dpo.h>
 #include <vnet/dpo/classify_dpo.h>
 #include <vnet/dpo/ip_null_dpo.h>
 #include <vnet/dpo/replicate_dpo.h>
 #include <vnet/dpo/interface_dpo.h>
 #include <vnet/dpo/mpls_disposition.h>

 /**
  * Array of char* names for the DPO types and protos
  */
 static const char* dpo_type_names[] = DPO_TYPES;
 static const char* dpo_proto_names[] = DPO_PROTOS;

 /**
  * @brief Vector of virtual function tables for the DPO types
  *
  * This is a vector so we can dynamically register new DPO types in plugins.
  */
 static dpo_vft_t *dpo_vfts;

 /**
  * @brief vector of graph node names associated with each DPO type and protocol.
  *
  *   dpo_nodes[child_type][child_proto][node_X] = node_name;
  * i.e.
  *   dpo_node[DPO_LOAD_BALANCE][DPO_PROTO_IP4][0] = "ip4-lookup"
  *   dpo_node[DPO_LOAD_BALANCE][DPO_PROTO_IP4][1] = "ip4-load-balance"
  *
  * This is a vector so we can dynamically register new DPO types in plugins.
  */
 static const char* const * const ** dpo_nodes;

 /**
  * @brief Vector of edge indicies from parent DPO nodes to child
  *
  * dpo_edges[child_type][child_proto][parent_type][parent_proto] = edge_index
  *
  * This array is derived at init time from the dpo_nodes above. Note that
  * the third dimension in dpo_nodes is lost, hence, the edge index from each
  * node MUST be the same.
  * Including both the child and parent protocol is required to support the
  * case where it changes as the grapth is traversed, most notablly when an
  * MPLS label is popped.
  *
  * Note that this array is child type specific, not child instance specific.
  */
 static u32 ****dpo_edges;

 /**
  * @brief The DPO type value that can be assigend to the next dynamic
  *        type registration.
  */
 static dpo_type_t dpo_dynamic = DPO_LAST;

 dpo_proto_t
 vnet_link_to_dpo_proto (vnet_link_t linkt)
 {
     switch (linkt)
     {
     case VNET_LINK_IP6:
         return (DPO_PROTO_IP6);
     case VNET_LINK_IP4:
         return (DPO_PROTO_IP4);
     case VNET_LINK_MPLS:
         return (DPO_PROTO_MPLS);
     case VNET_LINK_ETHERNET:
         return (DPO_PROTO_ETHERNET);
     case VNET_LINK_NSH:
         return (DPO_PROTO_NSH);
     case VNET_LINK_ARP:
 	break;
     }
     ASSERT(0);
     return (0);
 }

 u8 *
 format_dpo_type (u8 * s, va_list * args)
 {
     dpo_type_t type = va_arg (*args, int);

     s = format(s, "%s", dpo_type_names[type]);

     return (s);
 }

 u8 *
 format_dpo_id (u8 * s, va_list * args)
 {
     dpo_id_t *dpo = va_arg (*args, dpo_id_t*);
     u32 indent = va_arg (*args, u32);

     s = format(s, "[@%d]: ", dpo->dpoi_next_node);

     if (NULL != dpo_vfts[dpo->dpoi_type].dv_format)
     {
         return (format(s, "%U",
                        dpo_vfts[dpo->dpoi_type].dv_format,
                        dpo->dpoi_index,
                        indent));
     }

     switch (dpo->dpoi_type)
     {
     case DPO_FIRST:
 	s = format(s, "unset");
 	break;
     default:
 	s = format(s, "unknown");
 	break;
     }
     return (s);
 }

 u8 *
 format_dpo_proto (u8 * s, va_list * args)
 {
     dpo_proto_t proto = va_arg (*args, int);

     return (format(s, "%s", dpo_proto_names[proto]));
 }

 void
 dpo_set (dpo_id_t *dpo,
 	 dpo_type_t type,
 	 dpo_proto_t proto,
 	 index_t index)
 {
     dpo_id_t tmp = *dpo;

     dpo->dpoi_type = type;
     dpo->dpoi_proto = proto,
     dpo->dpoi_index = index;

     if (DPO_ADJACENCY == type)
     {
 	/*
 	 * set the adj subtype
 	 */
 	ip_adjacency_t *adj;

 	adj = adj_get(index);

 	switch (adj->lookup_next_index)
 	{
 	case IP_LOOKUP_NEXT_ARP:
 	    dpo->dpoi_type = DPO_ADJACENCY_INCOMPLETE;
 	    break;
 	case IP_LOOKUP_NEXT_MIDCHAIN:
 	    dpo->dpoi_type = DPO_ADJACENCY_MIDCHAIN;
 	    break;
 	case IP_LOOKUP_NEXT_MCAST_MIDCHAIN:
 	    dpo->dpoi_type = DPO_ADJACENCY_MCAST_MIDCHAIN;
 	    break;
 	case IP_LOOKUP_NEXT_MCAST:
 	    dpo->dpoi_type = DPO_ADJACENCY_MCAST;
             break;
 	case IP_LOOKUP_NEXT_GLEAN:
 	    dpo->dpoi_type = DPO_ADJACENCY_GLEAN;
 	    break;
 	default:
 	    break;
 	}
     }
     dpo_lock(dpo);
     dpo_unlock(&tmp);
 }

 void
 dpo_reset (dpo_id_t *dpo)
 {
     dpo_id_t tmp = DPO_INVALID;

     /*
      * use the atomic copy operation.
      */
     dpo_copy(dpo, &tmp);
 }

 /**
  * \brief
  * Compare two Data-path objects
  *
  * like memcmp, return 0 is matching, !0 otherwise.
  */
 int
 dpo_cmp (const dpo_id_t *dpo1,
 	 const dpo_id_t *dpo2)
 {
     int res;

     res = dpo1->dpoi_type - dpo2->dpoi_type;

     if (0 != res) return (res);

     return (dpo1->dpoi_index - dpo2->dpoi_index);
 }

 void
 dpo_copy (dpo_id_t *dst,
 	  const dpo_id_t *src)
 {
     dpo_id_t tmp = *dst;

     /*
      * the destination is written in a single u64 write - hence atomically w.r.t
      * any packets inflight.
      */
     *((u64*)dst) = *(u64*)src;

     dpo_lock(dst);
     dpo_unlock(&tmp);
 }

 int
 dpo_is_adj (const dpo_id_t *dpo)
 {
     return ((dpo->dpoi_type == DPO_ADJACENCY) ||
 	    (dpo->dpoi_type == DPO_ADJACENCY_INCOMPLETE) ||
 	    (dpo->dpoi_type == DPO_ADJACENCY_MIDCHAIN) ||
 	    (dpo->dpoi_type == DPO_ADJACENCY_GLEAN));
 }

 void
 dpo_register (dpo_type_t type,
 	      const dpo_vft_t *vft,
               const char * const * const * nodes)
 {
     vec_validate(dpo_vfts, type);
     dpo_vfts[type] = *vft;

     vec_validate(dpo_nodes, type);
     dpo_nodes[type] = nodes;
 }

 dpo_type_t
 dpo_register_new_type (const dpo_vft_t *vft,
                        const char * const * const * nodes)
 {
     dpo_type_t type = dpo_dynamic++;

     dpo_register(type, vft, nodes);

     return (type);
 }

 void
 dpo_lock (dpo_id_t *dpo)
 {
     if (!dpo_id_is_valid(dpo))
 	return;

     dpo_vfts[dpo->dpoi_type].dv_lock(dpo);
 }

 void
 dpo_unlock (dpo_id_t *dpo)
 {
     if (!dpo_id_is_valid(dpo))
 	return;

     dpo_vfts[dpo->dpoi_type].dv_unlock(dpo);
 }


 static u32
 dpo_get_next_node (dpo_type_t child_type,
                    dpo_proto_t child_proto,
                    const dpo_id_t *parent_dpo)
 {
     dpo_proto_t parent_proto;
     dpo_type_t parent_type;

     parent_type = parent_dpo->dpoi_type;
     parent_proto = parent_dpo->dpoi_proto;

     vec_validate(dpo_edges, child_type);
     vec_validate(dpo_edges[child_type], child_proto);
     vec_validate(dpo_edges[child_type][child_proto], parent_type);
     vec_validate_init_empty(
         dpo_edges[child_type][child_proto][parent_type],
         parent_proto, ~0);

     /*
      * if the edge index has not yet been created for this node to node transistion
      */
     if (~0 == dpo_edges[child_type][child_proto][parent_type][parent_proto])
     {
         vlib_node_t *parent_node, *child_node;
         vlib_main_t *vm;
         u32 edge ,pp, cc;

         vm = vlib_get_main();

         vlib_worker_thread_barrier_sync(vm);

         ASSERT(NULL != dpo_nodes[child_type]);
         ASSERT(NULL != dpo_nodes[child_type][child_proto]);
         ASSERT(NULL != dpo_nodes[parent_type]);
         ASSERT(NULL != dpo_nodes[parent_type][parent_proto]);

         cc = 0;

         /*
          * create a graph arc from each of the parent's registered node types,
          * to each of the childs.
          */
         while (NULL != dpo_nodes[child_type][child_proto][cc])
         {
             child_node =
                 vlib_get_node_by_name(vm,
                                       (u8*) dpo_nodes[child_type][child_proto][cc]);

             pp = 0;

             while (NULL != dpo_nodes[parent_type][parent_proto][pp])
             {
                 parent_node =
                     vlib_get_node_by_name(vm,
                                           (u8*) dpo_nodes[parent_type][parent_proto][pp]);

                 edge = vlib_node_add_next(vm,
                                           child_node->index,
                                           parent_node->index);

                 if (~0 == dpo_edges[child_type][child_proto][parent_type][parent_proto])
                 {
                     dpo_edges[child_type][child_proto][parent_type][parent_proto] = edge;
                 }
                 else
                 {
                     ASSERT(dpo_edges[child_type][child_proto][parent_type][parent_proto] == edge);
                 }
                 pp++;
             }
             cc++;
         }

         vlib_worker_thread_barrier_release(vm);
     }

     return (dpo_edges[child_type][child_proto][parent_type][parent_proto]);
 }

 /**
  * @brief Stack one DPO object on another, and thus establish a child parent
  * relationship. The VLIB graph arc used is taken from the parent and child types
  * passed.
  */
 static void
 dpo_stack_i (u32 edge,
              dpo_id_t *dpo,
              const dpo_id_t *parent)
 {
     /*
      * in order to get an atomic update of the parent we create a temporary,
      * from a copy of the child, and add the next_node. then we copy to the parent
      */
     dpo_id_t tmp = DPO_INVALID;
     dpo_copy(&tmp, parent);

     /*
      * get the edge index for the parent to child VLIB graph transisition
      */
     tmp.dpoi_next_node = edge;

     /*
      * this update is atomic.
      */
     dpo_copy(dpo, &tmp);

     dpo_reset(&tmp);
 }

 /**
  * @brief Stack one DPO object on another, and thus establish a child-parent
  * relationship. The VLIB graph arc used is taken from the parent and child types
  * passed.
  */
 void
 dpo_stack (dpo_type_t child_type,
            dpo_proto_t child_proto,
            dpo_id_t *dpo,
            const dpo_id_t *parent)
 {
     dpo_stack_i(dpo_get_next_node(child_type, child_proto, parent), dpo, parent);
 }

 /**
  * @brief Stack one DPO object on another, and thus establish a child parent
  * relationship. A new VLIB graph arc is created from the child node passed
  * to the nodes registered by the parent. The VLIB infra will ensure this arc
  * is added only once.
  */
 void
 dpo_stack_from_node (u32 child_node_index,
                      dpo_id_t *dpo,
                      const dpo_id_t *parent)
 {
     dpo_proto_t parent_proto;
     vlib_node_t *parent_node;
     dpo_type_t parent_type;
     vlib_main_t *vm;
     u32 edge;

     parent_type = parent->dpoi_type;
     parent_proto = parent->dpoi_proto;

     vm = vlib_get_main();

     ASSERT(NULL != dpo_nodes[parent_type]);
     ASSERT(NULL != dpo_nodes[parent_type][parent_proto]);

     parent_node =
         vlib_get_node_by_name(vm, (u8*) dpo_nodes[parent_type][parent_proto][0]);

     edge = vlib_node_get_next(vm,
                               child_node_index,
                               parent_node->index);

     if (~0 == edge)
     {
         vlib_worker_thread_barrier_sync(vm);

         edge = vlib_node_add_next(vm,
                                   child_node_index,
                                   parent_node->index);

         vlib_worker_thread_barrier_release(vm);
     }

     dpo_stack_i(edge, dpo, parent);
 }

 static clib_error_t *
 dpo_module_init (vlib_main_t * vm)
 {
     drop_dpo_module_init();
     punt_dpo_module_init();
     receive_dpo_module_init();
     load_balance_module_init();
     mpls_label_dpo_module_init();
     classify_dpo_module_init();
     lookup_dpo_module_init();
     ip_null_dpo_module_init();
     replicate_module_init();
     interface_dpo_module_init();
     mpls_disp_dpo_module_init();

     return (NULL);
 }

 VLIB_INIT_FUNCTION(dpo_module_init);

 static clib_error_t *
 dpo_memory_show (vlib_main_t * vm,
 		 unformat_input_t * input,
 		 vlib_cli_command_t * cmd)
 {
     dpo_vft_t *vft;

     vlib_cli_output (vm, "DPO memory");
     vlib_cli_output (vm, "%=30s %=5s %=8s/%=9s   totals",
 		     "Name","Size", "in-use", "allocated");

     vec_foreach(vft, dpo_vfts)
     {
 	if (NULL != vft->dv_mem_show)
 	    vft->dv_mem_show();
     }

     return (NULL);
 }

 /* *INDENT-OFF* */
 /*?
  * The '<em>sh dpo memory </em>' command displays the memory usage for each
  * data-plane object type.
  *
  * @cliexpar
  * @cliexstart{show dpo memory}
  * DPO memory
  *             Name               Size  in-use /allocated   totals
  *         load-balance            64     12   /    12      768/768
  *           Adjacency            256      1   /    1       256/256
  *            Receive              24      5   /    5       120/120
  *            Lookup               12      0   /    0       0/0
  *           Classify              12      0   /    0       0/0
  *          MPLS label             24      0   /    0       0/0
  * @cliexend
 ?*/
 VLIB_CLI_COMMAND (show_fib_memory, static) = {
     .path = "show dpo memory",
     .function = dpo_memory_show,
     .short_help = "show dpo memory",
 };
 /* *INDENT-ON* */
	/*
	* Copyright (c) 2016 Cisco and/or its affiliates.
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at:
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/
	/**
	* @brief
	* A Data-Path Object is an object that represents actions that are
	* applied to packets are they are switched through VPP.
	*
	* The DPO is a base class that is specialised by other objects to provide
	* concreate actions
	*
	* The VLIB graph nodes are graph of types, the DPO graph is a graph of instances.
	*/

	#include <vnet/dpo/dpo.h>
	#include <vnet/ip/lookup.h>
	#include <vnet/ip/format.h>
	#include <vnet/adj/adj.h>

	#include <vnet/dpo/load_balance.h>
	#include <vnet/dpo/mpls_label_dpo.h>
	#include <vnet/dpo/lookup_dpo.h>
	#include <vnet/dpo/drop_dpo.h>
	#include <vnet/dpo/receive_dpo.h>
	#include <vnet/dpo/punt_dpo.h>
	#include <vnet/dpo/classify_dpo.h>
	#include <vnet/dpo/ip_null_dpo.h>
	#include <vnet/dpo/replicate_dpo.h>
	#include <vnet/dpo/interface_dpo.h>
	#include <vnet/dpo/mpls_disposition.h>

	/**
	* Array of char* names for the DPO types and protos
	*/
	static const char* dpo_type_names[] = DPO_TYPES;
	static const char* dpo_proto_names[] = DPO_PROTOS;

	/**
	* @brief Vector of virtual function tables for the DPO types
	*
	* This is a vector so we can dynamically register new DPO types in plugins.
	*/
	static dpo_vft_t *dpo_vfts;

	/**
	* @brief vector of graph node names associated with each DPO type and protocol.
	*
	* dpo_nodes[child_type][child_proto][node_X] = node_name;
	* i.e.
	* dpo_node[DPO_LOAD_BALANCE][DPO_PROTO_IP4][0] = "ip4-lookup"
	* dpo_node[DPO_LOAD_BALANCE][DPO_PROTO_IP4][1] = "ip4-load-balance"
	*
	* This is a vector so we can dynamically register new DPO types in plugins.
	*/
	static const char* const * const ** dpo_nodes;

	/**
	* @brief Vector of edge indicies from parent DPO nodes to child
	*
	* dpo_edges[child_type][child_proto][parent_type][parent_proto] = edge_index
	*
	* This array is derived at init time from the dpo_nodes above. Note that
	* the third dimension in dpo_nodes is lost, hence, the edge index from each
	* node MUST be the same.
	* Including both the child and parent protocol is required to support the
	* case where it changes as the grapth is traversed, most notablly when an
	* MPLS label is popped.
	*
	* Note that this array is child type specific, not child instance specific.
	*/
	static u32 ****dpo_edges;

	/**
	* @brief The DPO type value that can be assigend to the next dynamic
	* type registration.
	*/
	static dpo_type_t dpo_dynamic = DPO_LAST;

	dpo_proto_t
	vnet_link_to_dpo_proto (vnet_link_t linkt)
	{
	switch (linkt)
	{
	case VNET_LINK_IP6:
	return (DPO_PROTO_IP6);
	case VNET_LINK_IP4:
	return (DPO_PROTO_IP4);
	case VNET_LINK_MPLS:
	return (DPO_PROTO_MPLS);
	case VNET_LINK_ETHERNET:
	return (DPO_PROTO_ETHERNET);
	case VNET_LINK_NSH:
	return (DPO_PROTO_NSH);
	case VNET_LINK_ARP:
	break;
	}
	ASSERT(0);
	return (0);
	}

	u8 *
	format_dpo_type (u8 * s, va_list * args)
	{
	dpo_type_t type = va_arg (*args, int);

	s = format(s, "%s", dpo_type_names[type]);

	return (s);
	}

	u8 *
	format_dpo_id (u8 * s, va_list * args)
	{
	dpo_id_t dpo = va_arg (args, dpo_id_t*);
	u32 indent = va_arg (*args, u32);

	s = format(s, "[@%d]: ", dpo->dpoi_next_node);

	if (NULL != dpo_vfts[dpo->dpoi_type].dv_format)
	{
	return (format(s, "%U",
	dpo_vfts[dpo->dpoi_type].dv_format,
	dpo->dpoi_index,
	indent));
	}

	switch (dpo->dpoi_type)
	{
	case DPO_FIRST:
	s = format(s, "unset");
	break;
	default:
	s = format(s, "unknown");
	break;
	}
	return (s);
	}

	u8 *
	format_dpo_proto (u8 * s, va_list * args)
	{
	dpo_proto_t proto = va_arg (*args, int);

	return (format(s, "%s", dpo_proto_names[proto]));
	}

	void
	dpo_set (dpo_id_t *dpo,
	dpo_type_t type,
	dpo_proto_t proto,
	index_t index)
	{
	dpo_id_t tmp = *dpo;

	dpo->dpoi_type = type;
	dpo->dpoi_proto = proto,
	dpo->dpoi_index = index;

	if (DPO_ADJACENCY == type)
	{
	/*
	* set the adj subtype
	*/
	ip_adjacency_t *adj;

	adj = adj_get(index);

	switch (adj->lookup_next_index)
	{
	case IP_LOOKUP_NEXT_ARP:
	dpo->dpoi_type = DPO_ADJACENCY_INCOMPLETE;
	break;
	case IP_LOOKUP_NEXT_MIDCHAIN:
	dpo->dpoi_type = DPO_ADJACENCY_MIDCHAIN;
	break;
	case IP_LOOKUP_NEXT_MCAST_MIDCHAIN:
	dpo->dpoi_type = DPO_ADJACENCY_MCAST_MIDCHAIN;
	break;
	case IP_LOOKUP_NEXT_MCAST:
	dpo->dpoi_type = DPO_ADJACENCY_MCAST;
	break;
	case IP_LOOKUP_NEXT_GLEAN:
	dpo->dpoi_type = DPO_ADJACENCY_GLEAN;
	break;
	default:
	break;
	}
	}
	dpo_lock(dpo);
	dpo_unlock(&tmp);
	}

	void
	dpo_reset (dpo_id_t *dpo)
	{
	dpo_id_t tmp = DPO_INVALID;

	/*
	* use the atomic copy operation.
	*/
	dpo_copy(dpo, &tmp);
	}

	/**
	* \brief
	* Compare two Data-path objects
	*
	* like memcmp, return 0 is matching, !0 otherwise.
	*/
	int
	dpo_cmp (const dpo_id_t *dpo1,
	const dpo_id_t *dpo2)
	{
	int res;

	res = dpo1->dpoi_type - dpo2->dpoi_type;

	if (0 != res) return (res);

	return (dpo1->dpoi_index - dpo2->dpoi_index);
	}

	void
	dpo_copy (dpo_id_t *dst,
	const dpo_id_t *src)
	{
	dpo_id_t tmp = *dst;

	/*
	* the destination is written in a single u64 write - hence atomically w.r.t
	* any packets inflight.
	*/
	((u64)dst) = (u64)src;

	dpo_lock(dst);
	dpo_unlock(&tmp);
	}

	int
	dpo_is_adj (const dpo_id_t *dpo)
	{
	return ((dpo->dpoi_type == DPO_ADJACENCY) \|\|
	(dpo->dpoi_type == DPO_ADJACENCY_INCOMPLETE) \|\|
	(dpo->dpoi_type == DPO_ADJACENCY_MIDCHAIN) \|\|
	(dpo->dpoi_type == DPO_ADJACENCY_GLEAN));
	}

	void
	dpo_register (dpo_type_t type,
	const dpo_vft_t *vft,
	const char * const * const * nodes)
	{
	vec_validate(dpo_vfts, type);
	dpo_vfts[type] = *vft;

	vec_validate(dpo_nodes, type);
	dpo_nodes[type] = nodes;
	}

	dpo_type_t
	dpo_register_new_type (const dpo_vft_t *vft,
	const char * const * const * nodes)
	{
	dpo_type_t type = dpo_dynamic++;

	dpo_register(type, vft, nodes);

	return (type);
	}

	void
	dpo_lock (dpo_id_t *dpo)
	{
	if (!dpo_id_is_valid(dpo))
	return;

	dpo_vfts[dpo->dpoi_type].dv_lock(dpo);
	}

	void
	dpo_unlock (dpo_id_t *dpo)
	{
	if (!dpo_id_is_valid(dpo))
	return;

	dpo_vfts[dpo->dpoi_type].dv_unlock(dpo);
	}


	static u32
	dpo_get_next_node (dpo_type_t child_type,
	dpo_proto_t child_proto,
	const dpo_id_t *parent_dpo)
	{
	dpo_proto_t parent_proto;
	dpo_type_t parent_type;

	parent_type = parent_dpo->dpoi_type;
	parent_proto = parent_dpo->dpoi_proto;

	vec_validate(dpo_edges, child_type);
	vec_validate(dpo_edges[child_type], child_proto);
	vec_validate(dpo_edges[child_type][child_proto], parent_type);
	vec_validate_init_empty(
	dpo_edges[child_type][child_proto][parent_type],
	parent_proto, ~0);

	/*
	* if the edge index has not yet been created for this node to node transistion
	*/
	if (~0 == dpo_edges[child_type][child_proto][parent_type][parent_proto])
	{
	vlib_node_t parent_node, child_node;
	vlib_main_t *vm;
	u32 edge ,pp, cc;

	vm = vlib_get_main();

	vlib_worker_thread_barrier_sync(vm);

	ASSERT(NULL != dpo_nodes[child_type]);
	ASSERT(NULL != dpo_nodes[child_type][child_proto]);
	ASSERT(NULL != dpo_nodes[parent_type]);
	ASSERT(NULL != dpo_nodes[parent_type][parent_proto]);

	cc = 0;

	/*
	* create a graph arc from each of the parent's registered node types,
	* to each of the childs.
	*/
	while (NULL != dpo_nodes[child_type][child_proto][cc])
	{
	child_node =
	vlib_get_node_by_name(vm,
	(u8*) dpo_nodes[child_type][child_proto][cc]);

	pp = 0;

	while (NULL != dpo_nodes[parent_type][parent_proto][pp])
	{
	parent_node =
	vlib_get_node_by_name(vm,
	(u8*) dpo_nodes[parent_type][parent_proto][pp]);

	edge = vlib_node_add_next(vm,
	child_node->index,
	parent_node->index);

	if (~0 == dpo_edges[child_type][child_proto][parent_type][parent_proto])
	{
	dpo_edges[child_type][child_proto][parent_type][parent_proto] = edge;
	}
	else
	{
	ASSERT(dpo_edges[child_type][child_proto][parent_type][parent_proto] == edge);
	}
	pp++;
	}
	cc++;
	}

	vlib_worker_thread_barrier_release(vm);
	}

	return (dpo_edges[child_type][child_proto][parent_type][parent_proto]);
	}

	/**
	* @brief Stack one DPO object on another, and thus establish a child parent
	* relationship. The VLIB graph arc used is taken from the parent and child types
	* passed.
	*/
	static void
	dpo_stack_i (u32 edge,
	dpo_id_t *dpo,
	const dpo_id_t *parent)
	{
	/*
	* in order to get an atomic update of the parent we create a temporary,
	* from a copy of the child, and add the next_node. then we copy to the parent
	*/
	dpo_id_t tmp = DPO_INVALID;
	dpo_copy(&tmp, parent);

	/*
	* get the edge index for the parent to child VLIB graph transisition
	*/
	tmp.dpoi_next_node = edge;

	/*
	* this update is atomic.
	*/
	dpo_copy(dpo, &tmp);

	dpo_reset(&tmp);
	}

	/**
	* @brief Stack one DPO object on another, and thus establish a child-parent
	* relationship. The VLIB graph arc used is taken from the parent and child types
	* passed.
	*/
	void
	dpo_stack (dpo_type_t child_type,
	dpo_proto_t child_proto,
	dpo_id_t *dpo,
	const dpo_id_t *parent)
	{
	dpo_stack_i(dpo_get_next_node(child_type, child_proto, parent), dpo, parent);
	}

	/**
	* @brief Stack one DPO object on another, and thus establish a child parent
	* relationship. A new VLIB graph arc is created from the child node passed
	* to the nodes registered by the parent. The VLIB infra will ensure this arc
	* is added only once.
	*/
	void
	dpo_stack_from_node (u32 child_node_index,
	dpo_id_t *dpo,
	const dpo_id_t *parent)
	{
	dpo_proto_t parent_proto;
	vlib_node_t *parent_node;
	dpo_type_t parent_type;
	vlib_main_t *vm;
	u32 edge;

	parent_type = parent->dpoi_type;
	parent_proto = parent->dpoi_proto;

	vm = vlib_get_main();

	ASSERT(NULL != dpo_nodes[parent_type]);
	ASSERT(NULL != dpo_nodes[parent_type][parent_proto]);

	parent_node =
	vlib_get_node_by_name(vm, (u8*) dpo_nodes[parent_type][parent_proto][0]);

	edge = vlib_node_get_next(vm,
	child_node_index,
	parent_node->index);

	if (~0 == edge)
	{
	vlib_worker_thread_barrier_sync(vm);

	edge = vlib_node_add_next(vm,
	child_node_index,
	parent_node->index);

	vlib_worker_thread_barrier_release(vm);
	}

	dpo_stack_i(edge, dpo, parent);
	}

	static clib_error_t *
	dpo_module_init (vlib_main_t * vm)
	{
	drop_dpo_module_init();
	punt_dpo_module_init();
	receive_dpo_module_init();
	load_balance_module_init();
	mpls_label_dpo_module_init();
	classify_dpo_module_init();
	lookup_dpo_module_init();
	ip_null_dpo_module_init();
	replicate_module_init();
	interface_dpo_module_init();
	mpls_disp_dpo_module_init();

	return (NULL);
	}

	VLIB_INIT_FUNCTION(dpo_module_init);

	static clib_error_t *
	dpo_memory_show (vlib_main_t * vm,
	unformat_input_t * input,
	vlib_cli_command_t * cmd)
	{
	dpo_vft_t *vft;

	vlib_cli_output (vm, "DPO memory");
	vlib_cli_output (vm, "%=30s %=5s %=8s/%=9s totals",
	"Name","Size", "in-use", "allocated");

	vec_foreach(vft, dpo_vfts)
	{
	if (NULL != vft->dv_mem_show)
	vft->dv_mem_show();
	}

	return (NULL);
	}

	/* INDENT-OFF */
	/*?
	* The '<em>sh dpo memory </em>' command displays the memory usage for each
	* data-plane object type.
	*
	* @cliexpar
	* @cliexstart{show dpo memory}
	* DPO memory
	* Name Size in-use /allocated totals
	* load-balance 64 12 / 12 768/768
	* Adjacency 256 1 / 1 256/256
	* Receive 24 5 / 5 120/120
	* Lookup 12 0 / 0 0/0
	* Classify 12 0 / 0 0/0
	* MPLS label 24 0 / 0 0/0
	* @cliexend
	?*/
	VLIB_CLI_COMMAND (show_fib_memory, static) = {
	.path = "show dpo memory",
	.function = dpo_memory_show,
	.short_help = "show dpo memory",
	};
	/* INDENT-ON */