vlib: refactor trajectory trace debug feature

trajectory trace has been broken for a while because we used to save the
buffer trajectory in a vector pointed to in opaque2. This does not work
well when opaque2 is copied (eg. because of a clone) as 2 buffers end up
sharing the same vector.
This dedicates a full cacheline in the buffer metadata instead when
trajectory is compiled in. No dynamic allocation, no sharing, no tears.

Type: refactor

Change-Id: I6a028ca1b48d38f393a36979e5e452c2dd48ad3f
Signed-off-by: Benoît Ganne <bganne@cisco.com>

44 files changed, 98 insertions, 275 deletions

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 3fc72d72884..a291c4d022d 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -142,6 +142,15 @@ if (VPP_ENABLE_SANITIZE_ADDR)
 endif (VPP_ENABLE_SANITIZE_ADDR)
 
 ##############################################################################
+# trajectory trace
+##############################################################################
+
+option(VPP_ENABLE_TRAJECTORY_TRACE "Build vpp with trajectory tracing enabled" OFF)
+if(VPP_ENABLE_TRAJECTORY_TRACE)
+  set(CMAKE_C_FLAGS "-DVLIB_BUFFER_TRACE_TRAJECTORY=1 ${CMAKE_C_FLAGS}")
+endif()
+
+##############################################################################
 # install config
 ##############################################################################
 option(VPP_SET_RPATH "Set rpath for resulting binaries and libraries." ON)
diff --git a/src/plugins/af_xdp/device.c b/src/plugins/af_xdp/device.c
index fabf85adfa6..35ba617d6e3 100644
--- a/src/plugins/af_xdp/device.c
+++ b/src/plugins/af_xdp/device.c
@@ -208,6 +208,18 @@ af_xdp_create_queue (vlib_main_t * vm, af_xdp_create_if_args_t * args,
   umem_config.comp_size = args->txq_size;
   umem_config.frame_size =
     sizeof (vlib_buffer_t) + vlib_buffer_get_default_data_size (vm);
+  /*
+   * Note about headroom: for some reasons, there seem to be a discrepency
+   * between 0-copy and copy mode:
+   *   - 0-copy: XDP_PACKET_HEADROOM will be added to the user headroom
+   *   - copy: nothing is added to the user headroom
+   * We privileged 0-copy and set headroom so that frame_headroom +
+   * XDP_PACKET_HEADROOM == sizeof(vlib_buffer_t), ie data will correctly
+   * point to vlib_buffer_t->data for 0-copy. In copy mode, we have to add
+   * XDP_PACKET_HEADROOM to desc offset during refill.
+   */
+  STATIC_ASSERT (sizeof (vlib_buffer_t) >= XDP_PACKET_HEADROOM, "wrong size");
+  umem_config.frame_headroom = sizeof (vlib_buffer_t) - XDP_PACKET_HEADROOM;
   umem_config.flags = XDP_UMEM_UNALIGNED_CHUNK_FLAG;
   if (xsk_umem__create
       (umem, uword_to_pointer (vm->buffer_main->buffer_mem_start, void *),
diff --git a/src/plugins/af_xdp/input.c b/src/plugins/af_xdp/input.c
index 65eee75cb92..da422bdccaf 100644
--- a/src/plugins/af_xdp/input.c
+++ b/src/plugins/af_xdp/input.c
@@ -130,17 +130,11 @@ af_xdp_device_input_refill (vlib_main_t * vm,
 
   /*
    * Note about headroom: for some reasons, there seem to be a discrepency
-   * between 0-copy and copy mode:
-   *   - 0-copy: XDP_PACKET_HEADROOM will be added to the user headroom
-   *   - copy: nothing is added to the user headroom
-   * We privileged 0-copy and set headroom to 0. As XDP_PACKET_HEADROOM ==
-   * sizeof(vlib_buffer_t), data will correctly point to vlib_buffer_t->data.
-   * In copy mode, we have to add sizeof(vlib_buffer_t) to desc offset during
-   * refill.
+   * between 0-copy and copy mode. See
+   * src/plugins/af_xdp/device.c:af_xdp_create_queue()
    */
-  STATIC_ASSERT (sizeof (vlib_buffer_t) == XDP_PACKET_HEADROOM, "wrong size");
-#define bi2addr(bi) \
-  (((bi) << CLIB_LOG2_CACHE_LINE_BYTES) + (copy ? sizeof(vlib_buffer_t) : 0))
+#define bi2addr(bi)                                                           \
+  (((bi) << CLIB_LOG2_CACHE_LINE_BYTES) + (copy ? XDP_PACKET_HEADROOM : 0))
 
 wrap_around:
 
@@ -218,8 +212,8 @@ af_xdp_device_input_bufs (vlib_main_t * vm, const af_xdp_device_t * ad,
   const u32 mask = rxq->rx.mask;
   u32 n = n_rx, *bi = bis, bytes = 0;
 
-#define addr2bi(addr) \
-  (((addr) - (copy ? sizeof(vlib_buffer_t) : 0)) >> CLIB_LOG2_CACHE_LINE_BYTES)
+#define addr2bi(addr)                                                         \
+  (((addr) - (copy ? XDP_PACKET_HEADROOM : 0)) >> CLIB_LOG2_CACHE_LINE_BYTES)
 
   while (n >= 1)
     {
diff --git a/src/plugins/avf/input.c b/src/plugins/avf/input.c
index 03ec2883601..6e437da2a16 100644
--- a/src/plugins/avf/input.c
+++ b/src/plugins/avf/input.c
@@ -230,11 +230,6 @@ avf_process_rx_burst (vlib_main_t * vm, vlib_node_runtime_t * node,
 	  n_rx_bytes += avf_rx_attach_tail (vm, &bt, b[3], qw1[3], tail + 3);
 	}
 
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b[0]);
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b[1]);
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b[2]);
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b[3]);
-
       /* next */
       qw1 += 4;
       tail += 4;
@@ -251,8 +246,6 @@ avf_process_rx_burst (vlib_main_t * vm, vlib_node_runtime_t * node,
       if (maybe_multiseg)
 	n_rx_bytes += avf_rx_attach_tail (vm, &bt, b[0], qw1[0], tail + 0);
 
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b[0]);
-
       /* next */
       qw1 += 1;
       tail += 1;
diff --git a/src/plugins/dhcp/client.c b/src/plugins/dhcp/client.c
index e79cb694378..f93643390e9 100644
--- a/src/plugins/dhcp/client.c
+++ b/src/plugins/dhcp/client.c
@@ -500,7 +500,6 @@ send_dhcp_pkt (dhcp_client_main_t * dcm, dhcp_client_t * c,
 
   /* Build a dhcpv4 pkt from whole cloth */
   b = vlib_get_buffer (vm, bi);
-  VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b);
 
   ASSERT (b->current_data == 0);
 
diff --git a/src/plugins/dhcp/dhcp4_proxy_node.c b/src/plugins/dhcp/dhcp4_proxy_node.c
index 6a3c51018d1..2ddad25bb11 100644
--- a/src/plugins/dhcp/dhcp4_proxy_node.c
+++ b/src/plugins/dhcp/dhcp4_proxy_node.c
@@ -370,7 +370,6 @@ dhcp_proxy_to_server_input (vlib_main_t * vm,
 			 DHCP_PROXY_ERROR_ALLOC_FAIL, 1);
 		      continue;
 		    }
-		  VLIB_BUFFER_TRACE_TRAJECTORY_INIT (c0);
 		  ci0 = vlib_get_buffer_index (vm, c0);
 		  server = &proxy->dhcp_servers[ii];
 
diff --git a/src/plugins/dhcp/dhcp6_proxy_node.c b/src/plugins/dhcp/dhcp6_proxy_node.c
index 3b95e7f9f09..33fb8a37992 100644
--- a/src/plugins/dhcp/dhcp6_proxy_node.c
+++ b/src/plugins/dhcp/dhcp6_proxy_node.c
@@ -443,7 +443,6 @@ dhcpv6_proxy_to_server_input (vlib_main_t * vm,
 			 DHCPV6_PROXY_ERROR_ALLOC_FAIL, 1);
 		      continue;
 		    }
-		  VLIB_BUFFER_TRACE_TRAJECTORY_INIT (c0);
 		  ci0 = vlib_get_buffer_index (vm, c0);
 		  server = &proxy->dhcp_servers[ii];
 
diff --git a/src/plugins/dpdk/device/device.c b/src/plugins/dpdk/device/device.c
index be20b4f8551..94b3f6b289a 100644
--- a/src/plugins/dpdk/device/device.c
+++ b/src/plugins/dpdk/device/device.c
@@ -311,11 +311,6 @@ VNET_DEVICE_CLASS_TX_FN (dpdk_device_class) (vlib_main_t * vm,
       or_flags = b[0]->flags | b[1]->flags | b[2]->flags | b[3]->flags;
       all_or_flags |= or_flags;
 
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b[0]);
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b[1]);
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b[2]);
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b[3]);
-
       if (or_flags & VLIB_BUFFER_NEXT_PRESENT)
 	{
 	  dpdk_validate_rte_mbuf (vm, b[0], 1);
@@ -374,9 +369,6 @@ VNET_DEVICE_CLASS_TX_FN (dpdk_device_class) (vlib_main_t * vm,
       or_flags = b[0]->flags | b[1]->flags;
       all_or_flags |= or_flags;
 
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b[0]);
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b[1]);
-
       if (or_flags & VLIB_BUFFER_NEXT_PRESENT)
 	{
 	  dpdk_validate_rte_mbuf (vm, b[0], 1);
@@ -412,7 +404,6 @@ VNET_DEVICE_CLASS_TX_FN (dpdk_device_class) (vlib_main_t * vm,
     {
       b[0] = vlib_buffer_from_rte_mbuf (mb[0]);
       all_or_flags |= b[0]->flags;
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b[0]);
 
       dpdk_validate_rte_mbuf (vm, b[0], 1);
       dpdk_buffer_tx_offload (xd, b[0], mb[0]);
diff --git a/src/plugins/dpdk/device/node.c b/src/plugins/dpdk/device/node.c
index 2eec74eaab2..98cda4c452f 100644
--- a/src/plugins/dpdk/device/node.c
+++ b/src/plugins/dpdk/device/node.c
@@ -216,11 +216,6 @@ dpdk_process_rx_burst (vlib_main_t * vm, dpdk_per_thread_data_t * ptd,
 	  n_bytes += dpdk_process_subseq_segs (vm, b[3], mb[3], &bt);
 	}
 
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b[0]);
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b[1]);
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b[2]);
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b[3]);
-
       /* next */
       mb += 4;
       n_left -= 4;
@@ -238,7 +233,6 @@ dpdk_process_rx_burst (vlib_main_t * vm, dpdk_per_thread_data_t * ptd,
 
       if (maybe_multiseg)
 	n_bytes += dpdk_process_subseq_segs (vm, b[0], mb[0], &bt);
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b[0]);
 
       /* next */
       mb += 1;
diff --git a/src/plugins/flowprobe/node.c b/src/plugins/flowprobe/node.c
index 70dc7267fd8..ab3640ca135 100644
--- a/src/plugins/flowprobe/node.c
+++ b/src/plugins/flowprobe/node.c
@@ -650,7 +650,6 @@ flowprobe_get_buffer (vlib_main_t * vm, flowprobe_variant_t which)
       /* Initialize the buffer */
       b0 = fm->context[which].buffers_per_worker[my_cpu_number] =
 	vlib_get_buffer (vm, bi0);
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b0);
 
       b0->current_data = 0;
       b0->current_length = flowprobe_get_headersize ();
diff --git a/src/plugins/igmp/igmp_pkt.c b/src/plugins/igmp/igmp_pkt.c
index 8912e5af882..c2ce5c71255 100644
--- a/src/plugins/igmp/igmp_pkt.c
+++ b/src/plugins/igmp/igmp_pkt.c
@@ -38,7 +38,6 @@ igmp_pkt_get_buffer (igmp_pkt_build_t * bk)
     return (NULL);
 
   b = vlib_get_buffer (vm, bi);
-  VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b);
 
   b->flags |= VNET_BUFFER_F_LOCALLY_ORIGINATED;
   b->flags |= VLIB_BUFFER_IS_TRACED;
diff --git a/src/plugins/marvell/pp2/input.c b/src/plugins/marvell/pp2/input.c
index 202572dc152..44f01355e39 100644
--- a/src/plugins/marvell/pp2/input.c
+++ b/src/plugins/marvell/pp2/input.c
@@ -233,9 +233,6 @@ mrvl_pp2_device_input_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 	  clib_memcpy_fast (vnet_buffer (b1)->sw_if_index, sw_if_index,
 			    sizeof (sw_if_index));
 
-	  VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b0);
-	  VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b1);
-
 	  if (PREDICT_FALSE (n_trace > 0))
 	    {
 	      mrvl_pp2_input_trace (vm, node, next0, b0, &n_trace, ppif, d);
@@ -277,8 +274,6 @@ mrvl_pp2_device_input_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 	  clib_memcpy_fast (vnet_buffer (b0)->sw_if_index, sw_if_index,
 			    sizeof (sw_if_index));
 
-	  VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b0);
-
 	  if (PREDICT_FALSE (n_trace > 0))
 	    mrvl_pp2_input_trace (vm, node, next0, b0, &n_trace, ppif, d);
 
diff --git a/src/plugins/memif/node.c b/src/plugins/memif/node.c
index 675acf3b49e..b2422f9e323 100644
--- a/src/plugins/memif/node.c
+++ b/src/plugins/memif/node.c
@@ -91,8 +91,6 @@ memif_trace_buffer (vlib_main_t * vm, vlib_node_runtime_t * node,
 		    memif_if_t * mif, vlib_buffer_t * b, u32 next, u16 qid,
 		    uword * n_tracep)
 {
-  VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b);
-
   if (PREDICT_TRUE
       (b != 0 && vlib_trace_buffer (vm, node, next, b, /* follow_chain */ 0)))
     {
diff --git a/src/plugins/nat/lib/ipfix_logging.c b/src/plugins/nat/lib/ipfix_logging.c
index 2a5130e09d0..6e5e4b6c750 100644
--- a/src/plugins/nat/lib/ipfix_logging.c
+++ b/src/plugins/nat/lib/ipfix_logging.c
@@ -613,7 +613,6 @@ nat_ipfix_logging_nat44_ses (u32 thread_index, u8 nat_event, u32 src_ip,
 	}
 
       b0 = sitd->nat44_session_buffer = vlib_get_buffer (vm, bi0);
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b0);
       offset = 0;
     }
   else
@@ -714,7 +713,6 @@ nat_ipfix_logging_addr_exhausted (u32 thread_index, u32 pool_id, int do_flush)
 	}
 
       b0 = sitd->addr_exhausted_buffer = vlib_get_buffer (vm, bi0);
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b0);
       offset = 0;
     }
   else
@@ -800,7 +798,6 @@ nat_ipfix_logging_max_entries_per_usr (u32 thread_index,
 	}
 
       b0 = sitd->max_entries_per_user_buffer = vlib_get_buffer (vm, bi0);
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b0);
       offset = 0;
     }
   else
@@ -892,7 +889,6 @@ nat_ipfix_logging_max_ses (u32 thread_index, u32 limit, int do_flush)
 	}
 
       b0 = sitd->max_sessions_buffer = vlib_get_buffer (vm, bi0);
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b0);
       offset = 0;
     }
   else
@@ -981,7 +977,6 @@ nat_ipfix_logging_max_bib (u32 thread_index, u32 limit, int do_flush)
 	}
 
       b0 = sitd->max_bibs_buffer = vlib_get_buffer (vm, bi0);
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b0);
       offset = 0;
     }
   else
@@ -1071,7 +1066,6 @@ nat_ipfix_logging_nat64_bibe (u32 thread_index, u8 nat_event,
 	}
 
       b0 = sitd->nat64_bib_buffer = vlib_get_buffer (vm, bi0);
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b0);
       offset = 0;
     }
   else
@@ -1175,7 +1169,6 @@ nat_ipfix_logging_nat64_ses (u32 thread_index, u8 nat_event,
 	}
 
       b0 = sitd->nat64_ses_buffer = vlib_get_buffer (vm, bi0);
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b0);
       offset = 0;
     }
   else
diff --git a/src/plugins/nat/nat44-ei/nat44_ei_ha.c b/src/plugins/nat/nat44-ei/nat44_ei_ha.c
index d94d07bdbfa..91eea98f84d 100644
--- a/src/plugins/nat/nat44-ei/nat44_ei_ha.c
+++ b/src/plugins/nat/nat44-ei/nat44_ei_ha.c
@@ -749,7 +749,6 @@ nat_ha_event_add (nat_ha_event_t *event, u8 do_flush, u32 session_thread_index,
 
       b = td->state_sync_buffer = vlib_get_buffer (vm, bi);
       clib_memset (vnet_buffer (b), 0, sizeof (*vnet_buffer (b)));
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b);
       offset = 0;
     }
   else
diff --git a/src/plugins/ping/ping.c b/src/plugins/ping/ping.c
index f3e238b9cd7..d09babd0be2 100644
--- a/src/plugins/ping/ping.c
+++ b/src/plugins/ping/ping.c
@@ -964,7 +964,6 @@ send_ip46_ping (vlib_main_t * vm,
     ERROR_OUT (SEND_PING_ALLOC_FAIL);
 
   b0 = vlib_get_buffer (vm, bi0);
-  VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b0);
 
   /*
    * if the user did not provide a source interface,
diff --git a/src/plugins/vmxnet3/output.c b/src/plugins/vmxnet3/output.c
index 4c9b7093f73..0de91d9bf21 100644
--- a/src/plugins/vmxnet3/output.c
+++ b/src/plugins/vmxnet3/output.c
@@ -175,7 +175,6 @@ VNET_DEVICE_CLASS_TX_FN (vmxnet3_device_class) (vlib_main_t * vm,
       for (i = 0; i < space_needed; i++)
 	{
 	  b0 = vlib_get_buffer (vm, bi0);
-	  VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b0);
 
 	  desc_idx = txq->tx_ring.produce;
 
diff --git a/src/plugins/vrrp/vrrp_packet.c b/src/plugins/vrrp/vrrp_packet.c
index b77f336930a..8daee500ece 100644
--- a/src/plugins/vrrp/vrrp_packet.c
+++ b/src/plugins/vrrp/vrrp_packet.c
@@ -313,7 +313,6 @@ vrrp_adv_send (vrrp_vr_t * vr, int shutdown)
       bi0 = vec_elt (bi, i);
       b = vlib_get_buffer (vm, bi0);
 
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b);
       b->flags |= VNET_BUFFER_F_LOCALLY_ORIGINATED;
       vnet_buffer (b)->sw_if_index[VLIB_RX] = 0;
       vnet_buffer (b)->sw_if_index[VLIB_TX] = vr->config.sw_if_index;
@@ -500,7 +499,6 @@ vrrp_garp_or_na_send (vrrp_vr_t * vr)
       addr = vec_elt_at_index (vr->config.vr_addrs, i);
       b = vlib_get_buffer (vm, bi[i]);
 
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b);
       b->flags |= VNET_BUFFER_F_LOCALLY_ORIGINATED;
       vnet_buffer (b)->sw_if_index[VLIB_RX] = 0;
       vnet_buffer (b)->sw_if_index[VLIB_TX] = vr->config.sw_if_index;
@@ -704,7 +702,6 @@ vrrp_vr_multicast_group_join (vrrp_vr_t * vr)
 
   b = vlib_get_buffer (vm, bi);
 
-  VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b);
   b->flags |= VNET_BUFFER_F_LOCALLY_ORIGINATED;
 
   vnet_buffer (b)->sw_if_index[VLIB_RX] = 0;
diff --git a/src/vlib/buffer.h b/src/vlib/buffer.h
index 297240d45f7..349b7324996 100644
--- a/src/vlib/buffer.h
+++ b/src/vlib/buffer.h
@@ -98,6 +98,15 @@ enum
 #define VLIB_BUFFER_FLAG_USER(n) (1 << LOG2_VLIB_BUFFER_FLAG_USER(n))
 #define VLIB_BUFFER_FLAGS_ALL (0x0f)
 
+/** \brief Compile time buffer trajectory tracing option
+    Turn this on if you run into "bad monkey" contexts,
+    and you want to know exactly which nodes they've visited...
+    See vlib/main.c...
+*/
+#ifndef VLIB_BUFFER_TRACE_TRAJECTORY
+#define VLIB_BUFFER_TRACE_TRAJECTORY 0
+#endif /* VLIB_BUFFER_TRACE_TRAJECTORY */
+
 /** VLIB buffer representation. */
 typedef union
 {
@@ -169,6 +178,20 @@ typedef union
     /**< More opaque data, see ../vnet/vnet/buffer.h */
     u32 opaque2[14];
 
+#if VLIB_BUFFER_TRACE_TRAJECTORY > 0
+    /** trace trajectory data - we use a specific cacheline for that in the
+     * buffer when it is compiled-in */
+#define VLIB_BUFFER_TRACE_TRAJECTORY_MAX     31
+#define VLIB_BUFFER_TRACE_TRAJECTORY_SZ	     64
+#define VLIB_BUFFER_TRACE_TRAJECTORY_INIT(b) (b)->trajectory_nb = 0
+    CLIB_ALIGN_MARK (trajectory, 64);
+    u16 trajectory_nb;
+    u16 trajectory_trace[VLIB_BUFFER_TRACE_TRAJECTORY_MAX];
+#else /* VLIB_BUFFER_TRACE_TRAJECTORY */
+#define VLIB_BUFFER_TRACE_TRAJECTORY_SZ 0
+#define VLIB_BUFFER_TRACE_TRAJECTORY_INIT(b)
+#endif /* VLIB_BUFFER_TRACE_TRAJECTORY */
+
     /** start of buffer headroom */
       CLIB_ALIGN_MARK (headroom, 64);
 
@@ -191,7 +214,8 @@ typedef union
 #endif
 } vlib_buffer_t;
 
-STATIC_ASSERT_SIZEOF (vlib_buffer_t, 128 + VLIB_BUFFER_PRE_DATA_SIZE);
+STATIC_ASSERT_SIZEOF (vlib_buffer_t, 128 + VLIB_BUFFER_TRACE_TRAJECTORY_SZ +
+				       VLIB_BUFFER_PRE_DATA_SIZE);
 STATIC_ASSERT (VLIB_BUFFER_PRE_DATA_SIZE % CLIB_CACHE_LINE_BYTES == 0,
 	       "VLIB_BUFFER_PRE_DATA_SIZE must be divisible by cache line size");
 
@@ -477,26 +501,6 @@ typedef struct
 
 clib_error_t *vlib_buffer_main_init (struct vlib_main_t *vm);
 
-/*
- */
-
-/** \brief Compile time buffer trajectory tracing option
-    Turn this on if you run into "bad monkey" contexts,
-    and you want to know exactly which nodes they've visited...
-    See vlib/main.c...
-*/
-#define VLIB_BUFFER_TRACE_TRAJECTORY 0
-
-#if VLIB_BUFFER_TRACE_TRAJECTORY > 0
-extern void (*vlib_buffer_trace_trajectory_cb) (vlib_buffer_t * b, u32 index);
-extern void (*vlib_buffer_trace_trajectory_init_cb) (vlib_buffer_t * b);
-extern void vlib_buffer_trace_trajectory_init (vlib_buffer_t * b);
-#define VLIB_BUFFER_TRACE_TRAJECTORY_INIT(b) \
-  vlib_buffer_trace_trajectory_init (b);
-#else
-#define VLIB_BUFFER_TRACE_TRAJECTORY_INIT(b)
-#endif /* VLIB_BUFFER_TRACE_TRAJECTORY */
-
 extern u16 __vlib_buffer_external_hdr_size;
 #define VLIB_BUFFER_SET_EXT_HDR_SIZE(x) \
 static void __clib_constructor \
diff --git a/src/vlib/main.c b/src/vlib/main.c
index bee63970f3d..f833aa25acf 100644
--- a/src/vlib/main.c
+++ b/src/vlib/main.c
@@ -934,29 +934,14 @@ vlib_elog_main_loop_event (vlib_main_t * vm,
     }
 }
 
-#if VLIB_BUFFER_TRACE_TRAJECTORY > 0
-void (*vlib_buffer_trace_trajectory_cb) (vlib_buffer_t * b, u32 node_index);
-void (*vlib_buffer_trace_trajectory_init_cb) (vlib_buffer_t * b);
-
-void
-vlib_buffer_trace_trajectory_init (vlib_buffer_t * b)
-{
-  if (PREDICT_TRUE (vlib_buffer_trace_trajectory_init_cb != 0))
-    {
-      (*vlib_buffer_trace_trajectory_init_cb) (b);
-    }
-}
-
-#endif
-
 static inline void
 add_trajectory_trace (vlib_buffer_t * b, u32 node_index)
 {
 #if VLIB_BUFFER_TRACE_TRAJECTORY > 0
-  if (PREDICT_TRUE (vlib_buffer_trace_trajectory_cb != 0))
-    {
-      (*vlib_buffer_trace_trajectory_cb) (b, node_index);
-    }
+  if (PREDICT_FALSE (b->trajectory_nb >= VLIB_BUFFER_TRACE_TRAJECTORY_MAX))
+    return;
+  b->trajectory_trace[b->trajectory_nb] = node_index;
+  b->trajectory_nb++;
 #endif
 }
 
diff --git a/src/vnet/CMakeLists.txt b/src/vnet/CMakeLists.txt
index 0a3b7101ab5..6e02efd68a0 100644
--- a/src/vnet/CMakeLists.txt
+++ b/src/vnet/CMakeLists.txt
@@ -1340,7 +1340,6 @@ list(APPEND VNET_SOURCES
   util/radix.c
   util/refcount.c
   util/throttle.c
-  util/trajectory.c
 )
 
 list(APPEND VNET_HEADERS
diff --git a/src/vnet/bfd/bfd_main.c b/src/vnet/bfd/bfd_main.c
index 30d98f6ab34..9e575afcaca 100644
--- a/src/vnet/bfd/bfd_main.c
+++ b/src/vnet/bfd/bfd_main.c
@@ -924,7 +924,6 @@ bfd_send_echo (vlib_main_t * vm, vlib_node_runtime_t * rt,
 	}
       vlib_buffer_t *b = vlib_get_buffer (vm, bi);
       ASSERT (b->current_data == 0);
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b);
       bfd_echo_pkt_t *pkt = vlib_buffer_get_current (b);
       clib_memset (pkt, 0, sizeof (*pkt));
       pkt->discriminator = bs->local_discr;
@@ -993,7 +992,6 @@ bfd_send_periodic (vlib_main_t * vm, vlib_node_runtime_t * rt,
 	}
       vlib_buffer_t *b = vlib_get_buffer (vm, bi);
       ASSERT (b->current_data == 0);
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b);
       bfd_init_control_frame (bm, bs, b);
       switch (bs->poll_state)
 	{
diff --git a/src/vnet/bonding/device.c b/src/vnet/bonding/device.c
index c69d5a40145..8a0c1092251 100644
--- a/src/vnet/bonding/device.c
+++ b/src/vnet/bonding/device.c
@@ -422,11 +422,6 @@ bond_tx_inline (vlib_main_t * vm, bond_if_t * bif, vlib_buffer_t ** b,
 	  CLIB_PREFETCH (pb[3]->data, CLIB_CACHE_LINE_BYTES, LOAD);
 	}
 
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b[0]);
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b[1]);
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b[2]);
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b[3]);
-
       if (lb_alg == BOND_LB_L2)
 	{
 	  h[0] = bond_lb_l2 (b[0]);
@@ -474,8 +469,6 @@ bond_tx_inline (vlib_main_t * vm, bond_if_t * bif, vlib_buffer_t ** b,
 
   while (n_left > 0)
     {
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b[0]);
-
       if (bif->lb == BOND_LB_L2)
 	h[0] = bond_lb_l2 (b[0]);
       else if (bif->lb == BOND_LB_L34)
diff --git a/src/vnet/bonding/node.c b/src/vnet/bonding/node.c
index d49894fcb74..21a968177fe 100644
--- a/src/vnet/bonding/node.c
+++ b/src/vnet/bonding/node.c
@@ -328,11 +328,6 @@ VLIB_NODE_FN (bond_input_node) (vlib_main_t * vm,
 				    &n_rx_packets, &n_rx_bytes);
 	}
 
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b[0]);
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b[1]);
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b[2]);
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b[3]);
-
       /* next */
       n_left -= 4;
       b += 4;
@@ -352,8 +347,6 @@ VLIB_NODE_FN (bond_input_node) (vlib_main_t * vm,
 	bond_sw_if_idx_rewrite (vm, node, b[0], bond_sw_if_index,
 				&n_rx_packets, &n_rx_bytes);
 
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b[0]);
-
       /* next */
       n_left -= 1;
       b += 1;
diff --git a/src/vnet/buffer.h b/src/vnet/buffer.h
index 00e9aa698c6..19585e22506 100644
--- a/src/vnet/buffer.h
+++ b/src/vnet/buffer.h
@@ -491,13 +491,6 @@ typedef struct
   {
     struct
     {
-#if VLIB_BUFFER_TRACE_TRAJECTORY > 0
-      /* buffer trajectory tracing */
-      u16 *trajectory_trace;
-#endif
-    };
-    struct
-    {
       u64 pad[1];
       u64 pg_replay_timestamp;
     };
diff --git a/src/vnet/devices/af_packet/node.c b/src/vnet/devices/af_packet/node.c
index 9f1782e2d13..16cd69a52ce 100644
--- a/src/vnet/devices/af_packet/node.c
+++ b/src/vnet/devices/af_packet/node.c
@@ -332,7 +332,6 @@ af_packet_device_input_fn (vlib_main_t * vm, vlib_node_runtime_t * node,
 	    }
 
 	  /* trace */
-	  VLIB_BUFFER_TRACE_TRAJECTORY_INIT (first_b0);
 	  if (PREDICT_FALSE
 	      (n_trace > 0 && vlib_trace_buffer (vm, node, next0, first_b0,
 						 /* follow_chain */ 0)))
diff --git a/src/vnet/devices/virtio/node.c b/src/vnet/devices/virtio/node.c
index 98df322ea15..df8c0fa9a64 100644
--- a/src/vnet/devices/virtio/node.c
+++ b/src/vnet/devices/virtio/node.c
@@ -522,8 +522,6 @@ virtio_device_input_gso_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 	    }
 
 	  /* trace */
-	  VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b0);
-
 	  if (PREDICT_FALSE (n_trace > 0 && vlib_trace_buffer (vm, node, next0, b0,	/* follow_chain */
 							       1)))
 	    {
diff --git a/src/vnet/devices/virtio/vhost_user_input.c b/src/vnet/devices/virtio/vhost_user_input.c
index 739125bbcfe..1636bd8c4a9 100644
--- a/src/vnet/devices/virtio/vhost_user_input.c
+++ b/src/vnet/devices/virtio/vhost_user_input.c
@@ -686,8 +686,6 @@ vhost_user_if_input (vlib_main_t *vm, vhost_user_main_t *vum,
       last_avail_idx++;
       last_used_idx++;
 
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b_head);
-
       vnet_buffer (b_head)->sw_if_index[VLIB_RX] = vui->sw_if_index;
       vnet_buffer (b_head)->sw_if_index[VLIB_TX] = (u32) ~ 0;
       b_head->error = 0;
@@ -1318,8 +1316,6 @@ vhost_user_if_input_packed (vlib_main_t *vm, vhost_user_main_t *vum,
       b_head->total_length_not_including_first_buffer -=
 	b_head->current_length;
 
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b_head);
-
       vnet_buffer (b_head)->sw_if_index[VLIB_RX] = vui->sw_if_index;
       vnet_buffer (b_head)->sw_if_index[VLIB_TX] = ~0;
       b_head->error = 0;
diff --git a/src/vnet/dpo/replicate_dpo.c b/src/vnet/dpo/replicate_dpo.c
index 929fed0b831..5f88f12b910 100644
--- a/src/vnet/dpo/replicate_dpo.c
+++ b/src/vnet/dpo/replicate_dpo.c
@@ -791,8 +791,6 @@ replicate_inline (vlib_main_t * vm,
                 {
                     replicate_trace_t *t;
 
-                    if (c0 != b0)
-		      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (c0);
                     t = vlib_add_trace (vm, node, c0, sizeof (*t));
                     t->rep_index = repi0;
                     t->dpo = *dpo0;
diff --git a/src/vnet/interface.c b/src/vnet/interface.c
index cd734cedd5c..32fb1f2e64a 100644
--- a/src/vnet/interface.c
+++ b/src/vnet/interface.c
@@ -1439,11 +1439,6 @@ vnet_interface_init (vlib_main_t * vm)
 
   vnm->interface_tag_by_sw_if_index = hash_create (0, sizeof (uword));
 
-#if VLIB_BUFFER_TRACE_TRAJECTORY > 0
-  if ((error = vlib_call_init_function (vm, trajectory_trace_init)))
-    return error;
-#endif
-
   return 0;
 }
 
diff --git a/src/vnet/ip-neighbor/ip4_neighbor.h b/src/vnet/ip-neighbor/ip4_neighbor.h
index 11309af82d5..c330dfa59e7 100644
--- a/src/vnet/ip-neighbor/ip4_neighbor.h
+++ b/src/vnet/ip-neighbor/ip4_neighbor.h
@@ -61,7 +61,6 @@ ip4_neighbor_probe (vlib_main_t * vm,
   h0->ip4_over_ethernet[0].ip4 = *src;
   h0->ip4_over_ethernet[1].ip4 = *dst;
 
-  VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b0);
   vnet_buffer (b0)->sw_if_index[VLIB_TX] = adj0->rewrite_header.sw_if_index;
 
   vlib_buffer_advance (b0, -adj0->rewrite_header.data_bytes);
diff --git a/src/vnet/ip-neighbor/ip6_neighbor.h b/src/vnet/ip-neighbor/ip6_neighbor.h
index 681e634861c..ad2ace21948 100644
--- a/src/vnet/ip-neighbor/ip6_neighbor.h
+++ b/src/vnet/ip-neighbor/ip6_neighbor.h
@@ -86,7 +86,6 @@ ip6_neighbor_probe (vlib_main_t * vm,
     ip6_tcp_udp_icmp_compute_checksum (vm, 0, &h0->ip, &bogus_length);
 
   ASSERT (bogus_length == 0);
-  VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b0);
 
   vnet_buffer (b0)->sw_if_index[VLIB_TX] = sw_if_index;
 
diff --git a/src/vnet/ip/ip_frag.c b/src/vnet/ip/ip_frag.c
index 33fbb9b2a9d..cafa9a66d6b 100644
--- a/src/vnet/ip/ip_frag.c
+++ b/src/vnet/ip/ip_frag.c
@@ -77,7 +77,6 @@ frag_buffer_alloc (vlib_buffer_t * org_b, u32 * bi)
     return 0;
 
   vlib_buffer_t *b = vlib_get_buffer (vm, *bi);
-  VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b);
   vlib_buffer_copy_trace_flag (vm, org_b, *bi);
 
   return b;
diff --git a/src/vnet/ip/punt_node.c b/src/vnet/ip/punt_node.c
index 90953e63704..7f9beef0ffe 100644
--- a/src/vnet/ip/punt_node.c
+++ b/src/vnet/ip/punt_node.c
@@ -546,8 +546,6 @@ punt_socket_rx_fd (vlib_main_t * vm, vlib_node_runtime_t * node, u32 fd)
   b->flags = VNET_BUFFER_F_LOCALLY_ORIGINATED;
   b->current_length = size - sizeof (packetdesc);
 
-  VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b);
-
   switch (packetdesc.action)
     {
     case PUNT_L2:
diff --git a/src/vnet/ip6-nd/ip6_ra.c b/src/vnet/ip6-nd/ip6_ra.c
index 547ecf31034..270e428afad 100644
--- a/src/vnet/ip6-nd/ip6_ra.c
+++ b/src/vnet/ip6-nd/ip6_ra.c
@@ -1132,7 +1132,6 @@ create_buffer_for_rs (vlib_main_t * vm, ip6_ra_t * radv_info)
     }
 
   p0 = vlib_get_buffer (vm, bi0);
-  VLIB_BUFFER_TRACE_TRAJECTORY_INIT (p0);
   p0->flags |= VNET_BUFFER_F_LOCALLY_ORIGINATED;
 
   vnet_buffer (p0)->sw_if_index[VLIB_RX] = sw_if_index;
diff --git a/src/vnet/ipfix-export/flow_report.c b/src/vnet/ipfix-export/flow_report.c
index a831c3cbede..5d25bb5d413 100644
--- a/src/vnet/ipfix-export/flow_report.c
+++ b/src/vnet/ipfix-export/flow_report.c
@@ -119,9 +119,6 @@ send_template_packet (flow_report_main_t * frm,
 
   b0 = vlib_get_buffer (vm, bi0);
 
-  /* Initialize the buffer */
-  VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b0);
-
   ASSERT (vec_len (fr->rewrite) < vlib_buffer_get_default_data_size (vm));
 
   clib_memcpy_fast (b0->data, fr->rewrite, vec_len (fr->rewrite));
diff --git a/src/vnet/ipfix-export/ipfix_doc.md b/src/vnet/ipfix-export/ipfix_doc.md
index 1c7aad7750d..edae3f73660 100644
--- a/src/vnet/ipfix-export/ipfix_doc.md
+++ b/src/vnet/ipfix-export/ipfix_doc.md
@@ -299,7 +299,6 @@ This function creates the packet header for an ipfix data packet
    	}
 
          b0 = vlib_get_buffer (vm, bi0);
-         VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b0);
          offset = 0;
          mlm->buffers_by_thread[thread_index] = b0;
        }
diff --git a/src/vnet/session/session_node.c b/src/vnet/session/session_node.c
index 9fae9996698..d30df33a5e7 100644
--- a/src/vnet/session/session_node.c
+++ b/src/vnet/session/session_node.c
@@ -1141,9 +1141,6 @@ session_tx_fifo_read_and_snd_i (session_worker_t * wrk,
 
       n_left -= 2;
 
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b0);
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b1);
-
       vec_add1 (wrk->pending_tx_buffers, bi0);
       vec_add1 (wrk->pending_tx_buffers, bi1);
       vec_add1 (wrk->pending_tx_nexts, next_index);
@@ -1171,8 +1168,6 @@ session_tx_fifo_read_and_snd_i (session_worker_t * wrk,
 
       n_left -= 1;
 
-      VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b0);
-
       vec_add1 (wrk->pending_tx_buffers, bi0);
       vec_add1 (wrk->pending_tx_nexts, next_index);
     }
diff --git a/src/vnet/syslog/syslog.c b/src/vnet/syslog/syslog.c
index 20728b8a17a..8f3313950e8 100644
--- a/src/vnet/syslog/syslog.c
+++ b/src/vnet/syslog/syslog.c
@@ -170,7 +170,6 @@ syslog_msg_send (syslog_msg_t * syslog_msg)
     return -1;
 
   b = vlib_get_buffer (vm, bi);
-  VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b);
 
   /* one message per UDP datagram RFC5426 3.1. */
   tmp = format (0, "%U", format_syslog_msg, syslog_msg);
diff --git a/src/vnet/tcp/tcp.h b/src/vnet/tcp/tcp.h
index 23b61313568..a02a295e72b 100644
--- a/src/vnet/tcp/tcp.h
+++ b/src/vnet/tcp/tcp.h
@@ -288,15 +288,6 @@ tcp_get_worker (u32 thread_index)
   return &tcp_main.wrk_ctx[thread_index];
 }
 
-#if (VLIB_BUFFER_TRACE_TRAJECTORY)
-#define tcp_trajectory_add_start(b, start)			\
-{								\
-    (*vlib_buffer_trace_trajectory_cb) (b, start);		\
-}
-#else
-#define tcp_trajectory_add_start(b, start)
-#endif
-
 tcp_connection_t *tcp_connection_alloc (u8 thread_index);
 tcp_connection_t *tcp_connection_alloc_w_base (u8 thread_index,
 					       tcp_connection_t * base);
diff --git a/src/vnet/tcp/tcp_output.c b/src/vnet/tcp/tcp_output.c
index dac50b5bf40..bde06da87ed 100644
--- a/src/vnet/tcp/tcp_output.c
+++ b/src/vnet/tcp/tcp_output.c
@@ -345,7 +345,7 @@ tcp_reuse_buffer (vlib_main_t * vm, vlib_buffer_t * b)
   b->current_length = 0;
   b->total_length_not_including_first_buffer = 0;
   vnet_buffer (b)->tcp.flags = 0;
-
+  VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b);
   /* Leave enough space for headers */
   return vlib_buffer_make_headroom (b, TRANSPORT_MAX_HDRS_LEN);
 }
@@ -359,7 +359,6 @@ tcp_init_buffer (vlib_main_t * vm, vlib_buffer_t * b)
   b->total_length_not_including_first_buffer = 0;
   b->current_data = 0;
   vnet_buffer (b)->tcp.flags = 0;
-  VLIB_BUFFER_TRACE_TRAJECTORY_INIT (b);
   /* Leave enough space for headers */
   return vlib_buffer_make_headroom (b, TRANSPORT_MAX_HDRS_LEN);
 }
@@ -555,8 +554,6 @@ tcp_enqueue_to_ip_lookup (tcp_worker_ctx_t * wrk, vlib_buffer_t * b, u32 bi,
   vnet_buffer (b)->sw_if_index[VLIB_TX] = fib_index;
   vnet_buffer (b)->sw_if_index[VLIB_RX] = 0;
 
-  tcp_trajectory_add_start (b, 1);
-
   session_add_pending_tx_buffer (vm->thread_index, bi,
 				 tm->ipl_next_node[!is_ip4]);
 
@@ -633,7 +630,6 @@ tcp_make_reset_in_place (vlib_main_t * vm, vlib_buffer_t * b, u8 is_ip4)
     }
 
   tcp_reuse_buffer (vm, b);
-  tcp_trajectory_add_start (b, 4);
   th = vlib_buffer_push_tcp_net_order (b, dst_port, src_port, seq, ack,
 				       sizeof (tcp_header_t), flags, 0);
 
@@ -1018,7 +1014,6 @@ tcp_session_push_header (transport_connection_t * tconn, vlib_buffer_t * b)
       tcp_retransmit_timer_set (&wrk->timer_wheel, tc);
       tc->rto_boff = 0;
     }
-  tcp_trajectory_add_start (b, 3);
   return 0;
 }
 
diff --git a/src/vnet/unix/gdb_funcs.c b/src/vnet/unix/gdb_funcs.c
index 797cb0eb7d1..886d849c173 100644
--- a/src/vnet/unix/gdb_funcs.c
+++ b/src/vnet/unix/gdb_funcs.c
@@ -380,6 +380,47 @@ gdb_validate_buffer (vlib_buffer_t * b)
   return 0;
 }
 
+/**
+ * Dump a trajectory trace, reasonably easy to call from gdb
+ */
+void
+gdb_dump_trajectory_trace (u32 bi)
+{
+#if VLIB_BUFFER_TRACE_TRAJECTORY > 0
+  vlib_main_t *vm = vlib_get_main ();
+  vlib_node_main_t *vnm = &vm->node_main;
+  vlib_buffer_t *b;
+  u16 *trace;
+  u8 i;
+
+  b = vlib_get_buffer (vm, bi);
+
+  trace = b->trajectory_trace;
+
+  fformat (stderr, "Context trace for bi %d b 0x%llx, visited %d\n", bi, b,
+	   b->trajectory_nb);
+
+  for (i = 0; i < b->trajectory_nb; i++)
+    {
+      u32 node_index;
+
+      node_index = trace[i];
+
+      if (node_index >= vec_len (vnm->nodes))
+	{
+	  fformat (stderr, "Skip bogus node index %d\n", node_index);
+	  continue;
+	}
+
+      fformat (stderr, "%v (%d)\n", vnm->nodes[node_index]->name, node_index);
+    }
+#else
+  fformat (stderr, "in vlib/buffers.h, "
+		   "#define VLIB_BUFFER_TRACE_TRAJECTORY 1\n");
+
+#endif
+}
+
 /* Cafeteria plan, maybe you don't want these functions */
 clib_error_t *
 gdb_func_init (vlib_main_t * vm)
diff --git a/src/vnet/unix/tuntap.c b/src/vnet/unix/tuntap.c
index 50f02df9e82..4a848349ae1 100644
--- a/src/vnet/unix/tuntap.c
+++ b/src/vnet/unix/tuntap.c
@@ -336,14 +336,6 @@ tuntap_rx (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * frame)
     vnet_buffer (b)->sw_if_index[VLIB_RX] = tm->sw_if_index;
     vnet_buffer (b)->sw_if_index[VLIB_TX] = (u32) ~ 0;
 
-    /*
-     * Turn this on if you run into
-     * "bad monkey" contexts, and you want to know exactly
-     * which nodes they've visited...
-     */
-    if (VLIB_BUFFER_TRACE_TRAJECTORY)
-      b->pre_data[0] = 0;
-
     b->error = node->errors[0];
 
     if (tm->is_ether)
diff --git a/src/vnet/util/trajectory.c b/src/vnet/util/trajectory.c
deleted file mode 100644
index 2538c7ee64a..00000000000
--- a/src/vnet/util/trajectory.c
+++ /dev/null
@@ -1,99 +0,0 @@
-/*
- * Copyright (c) 2017 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.
- */
-
-/** \file
- * Buffer trace trajectory utilities
- */
-
-#include <vnet/vnet.h>
-
-/**
- * Dump a trajectory trace, reasonably easy to call from gdb
- */
-void
-vnet_dump_trajectory_trace (vlib_main_t * vm, u32 bi)
-{
-#if VLIB_BUFFER_TRACE_TRAJECTORY > 0
-  vlib_node_main_t *vnm = &vm->node_main;
-  vlib_buffer_t *b;
-  u16 *trace;
-  u8 i;
-
-  b = vlib_get_buffer (vm, bi);
-
-  trace = vnet_buffer2 (b)->trajectory_trace;
-
-  fformat (stderr, "Context trace for bi %d b 0x%llx, visited %d\n",
-	   bi, b, vec_len (trace));
-
-  for (i = 0; i < vec_len (trace); i++)
-    {
-      u32 node_index;
-
-      node_index = trace[i];
-
-      if (node_index >= vec_len (vnm->nodes))
-	{
-	  fformat (stderr, "Skip bogus node index %d\n", node_index);
-	  continue;
-	}
-
-      fformat (stderr, "%v (%d)\n", vnm->nodes[node_index]->name, node_index);
-    }
-#else
-  fformat (stderr, "in vlib/buffers.h, "
-	   "#define VLIB_BUFFER_TRACE_TRAJECTORY 1\n");
-
-#endif
-}
-
-#if VLIB_BUFFER_TRACE_TRAJECTORY > 0
-
-void
-init_trajectory_trace (vlib_buffer_t * b)
-{
-  if (!clib_mem_is_vec (vnet_buffer2 (b)->trajectory_trace))
-    {
-      vnet_buffer2 (b)->trajectory_trace = 0;
-      vec_validate (vnet_buffer2 (b)->trajectory_trace, 7);
-    }
-  _vec_len (vnet_buffer2 (b)->trajectory_trace) = 0;
-}
-
-void
-add_trajectory_trace (vlib_buffer_t * b, u32 node_index)
-{
-  vec_add1 (vnet_buffer2 (b)->trajectory_trace, (u16) node_index);
-}
-
-static clib_error_t *
-trajectory_trace_init (vlib_main_t * vm)
-{
-  vlib_buffer_trace_trajectory_cb = add_trajectory_trace;
-  vlib_buffer_trace_trajectory_init_cb = init_trajectory_trace;
-  return 0;
-}
-
-VLIB_INIT_FUNCTION (trajectory_trace_init);
-
-#endif
-
-/*
- * fd.io coding-style-patch-verification: ON
- *
- * Local Variables:
- * eval: (c-set-style "gnu")
- * End:
- */