4 files changed, 134 insertions, 6 deletions

diff --git a/src/vnet/buffer.h b/src/vnet/buffer.h
index 7567b875248..045328816cd 100644
--- a/src/vnet/buffer.h
+++ b/src/vnet/buffer.h
@@ -317,9 +317,26 @@ typedef struct
 {
   union
   {
+#if VLIB_BUFFER_TRACE_TRAJECTORY > 0
+    /* buffer trajectory tracing */
+    struct
+    {
+      u16 *trajectory_trace;
+    };
+#endif
+    u32 unused[12];
   };
 } vnet_buffer_opaque2_t;
 
+#define vnet_buffer2(b) ((vnet_buffer_opaque2_t *) (b)->opaque2)
+
+/*
+ * The opaque2 field of the vlib_buffer_t is intepreted as a
+ * vnet_buffer_opaque2_t. Hence it should be big enough to accommodate one.
+ */
+STATIC_ASSERT (sizeof (vnet_buffer_opaque2_t) <=
+	       STRUCT_SIZE_OF (vlib_buffer_t, opaque2),
+	       "VNET buffer opaque2 meta-data too large for vlib_buffer");
 
 
 #endif /* included_vnet_buffer_h */
diff --git a/src/vnet/interface.c b/src/vnet/interface.c
index 159ce8c6494..eb5d3d0fced 100644
--- a/src/vnet/interface.c
+++ b/src/vnet/interface.c
@@ -1170,6 +1170,7 @@ vnet_interface_init (vlib_main_t * vm)
   vnet_interface_main_t *im = &vnm->interface_main;
   vlib_buffer_t *b = 0;
   vnet_buffer_opaque_t *o = 0;
+  clib_error_t *error;
 
   /*
    * Keep people from shooting themselves in the foot.
@@ -1250,15 +1251,17 @@ vnet_interface_init (vlib_main_t * vm)
       }
   }
 
-  {
-    clib_error_t *error;
+  if ((error = vlib_call_init_function (vm, vnet_interface_cli_init)))
+    return error;
 
-    if ((error = vlib_call_init_function (vm, vnet_interface_cli_init)))
-      return error;
+  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;
-  }
-  vnm->interface_tag_by_sw_if_index = hash_create (0, sizeof (uword));
+#endif
+
+  return 0;
 }
 
 VLIB_INIT_FUNCTION (vnet_interface_init);
diff --git a/src/vnet/unix/gdb_funcs.c b/src/vnet/unix/gdb_funcs.c
index 32e22d924ba..40d0d663472 100644
--- a/src/vnet/unix/gdb_funcs.c
+++ b/src/vnet/unix/gdb_funcs.c
@@ -190,6 +190,8 @@ show_gdb_command_fn (vlib_main_t * vm,
                      vlib_cli_command_t * cmd)
 {
   vlib_cli_output (vm, "vl(p) returns vec_len(p)");
+  vlib_cli_output (vm, "vb(b) returns vnet_buffer(b) [opaque]");
+  vlib_cli_output (vm, "vb2(b) returns vnet_buffer2(b) [opaque2]");
   vlib_cli_output (vm, "pe(p) returns pool_elts(p)");
   vlib_cli_output (vm, "pifi(p, i) returns pool_is_free_index(p, i)");
   vlib_cli_output (vm, "gdb_show_errors(0|1) dumps error counters");
@@ -217,6 +219,17 @@ vnet_buffer_opaque_t *vb (void *vb_arg)
     return rv;
 }
 
+vnet_buffer_opaque2_t *vb2 (void *vb_arg)
+{
+    vlib_buffer_t *b = (vlib_buffer_t *)vb_arg;
+    vnet_buffer_opaque2_t *rv;
+    
+    rv = vnet_buffer2(b);
+
+    return rv;
+}
+
+
 /* Cafeteria plan, maybe you don't want these functions */
 clib_error_t * 
 gdb_func_init (vlib_main_t * vm) { return 0; } 
diff --git a/src/vnet/util/trajectory.c b/src/vnet/util/trajectory.c
new file mode 100644
index 00000000000..24b51254ecd
--- /dev/null
+++ b/src/vnet/util/trajectory.c
@@ -0,0 +1,95 @@
+/*
+ * 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)
+{
+  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:
+ */