vlib: add postmortem pcap dispatch trace

Inspired by a real-life conundrum: scenario X involves a vpp crash in
ip4-load-balance because vnet_buffer(b)->ip.adj_index[VLIB_TX] is
(still) set to ~0.

The problem takes most of a day to occur, and we need to see the
broken packet's graph trajectory, metadata, etc. to understand the
problem.

Fix a signed/unsigned ASSERT bug in vlib_get_trace_count().

Rename elog_post_mortem_dump() -> vlib_post_mortem_dump(), add
dispatch trace post-mortem dump.

Add FILTER_FLAG_POST_MORTEM so we can (putatively) capture a ludicrous
number of buffer traces, without actually using more than one dispatch
cycle's worth of memory.

Type: improvement

Signed-off-by: Dave Barach <dave@barachs.net>
Change-Id: If093202ef071df46e290370bd9b33bf6560d30e6

1 files changed, 3 insertions, 3 deletions

diff --git a/src/vpp/vnet/main.c b/src/vpp/vnet/main.c
index 397cf8328c5..582ad5fdc31 100644
--- a/src/vpp/vnet/main.c
+++ b/src/vpp/vnet/main.c
@@ -399,13 +399,13 @@ test_plugin_path_config (vlib_main_t * vm, unformat_input_t * input)
 VLIB_CONFIG_FUNCTION (test_plugin_path_config, "test_plugin_path");
 
 void vl_msg_api_post_mortem_dump (void);
-void elog_post_mortem_dump (void);
+void vlib_post_mortem_dump (void);
 
 void
 os_panic (void)
 {
   vl_msg_api_post_mortem_dump ();
-  elog_post_mortem_dump ();
+  vlib_post_mortem_dump ();
   abort ();
 }
 
@@ -428,7 +428,7 @@ os_exit (int code)
       recursion_block = 1;
 
       vl_msg_api_post_mortem_dump ();
-      elog_post_mortem_dump ();
+      vlib_post_mortem_dump ();
       vhost_user_unmap_all ();
       abort ();
     }