init / exit function ordering

The vlib init function subsystem now supports a mix of procedural and
formally-specified ordering constraints. We should eliminate procedural
knowledge wherever possible.

The following schemes are *roughly* equivalent:

static clib_error_t *init_runs_first (vlib_main_t *vm)
{
   clib_error_t *error;

   ... do some stuff...

   if ((error = vlib_call_init_function (init_runs_next)))
     return error;
   ...
}
VLIB_INIT_FUNCTION (init_runs_first);

and

static clib_error_t *init_runs_first (vlib_main_t *vm)
{
   ... do some stuff...
}
VLIB_INIT_FUNCTION (init_runs_first) =
{
    .runs_before = VLIB_INITS("init_runs_next"),
};

The first form will [most likely] call "init_runs_next" on the
spot. The second form means that "init_runs_first" runs before
"init_runs_next," possibly much earlier in the sequence.

Please DO NOT construct sets of init functions where A before B
actually means A *right before* B. It's not necessary - simply combine
A and B - and it leads to hugely annoying debugging exercises when
trying to switch from ad-hoc procedural ordering constraints to formal
ordering constraints.

Change-Id: I5e4353503bf43b4acb11a45fb33c79a5ade8426c
Signed-off-by: Dave Barach <dave@barachs.net>

3 files changed, 7 insertions, 10 deletions

diff --git a/src/vlibmemory/memory_api.c b/src/vlibmemory/memory_api.c
index 9fc26b986f5..10425dd971c 100644
--- a/src/vlibmemory/memory_api.c
+++ b/src/vlibmemory/memory_api.c
@@ -954,8 +954,10 @@ vlibmemory_init (vlib_main_t * vm)
 {
   api_main_t *am = &api_main;
   svm_map_region_args_t _a, *a = &_a;
-  clib_error_t *error;
   u8 *remove_path1, *remove_path2;
+  void vlibsocket_reference (void);
+
+  vlibsocket_reference ();
 
   /*
    * By popular request / to avoid support fires, remove any old api segment
@@ -993,9 +995,7 @@ vlibmemory_init (vlib_main_t * vm)
 
   svm_region_init_args (a);
 
-  error = vlib_call_init_function (vm, vlibsocket_init);
-
-  return error;
+  return 0;
 }
 
 void
diff --git a/src/vlibmemory/socket_api.c b/src/vlibmemory/socket_api.c
index f0c7f1feeb1..31c1ff9880e 100644
--- a/src/vlibmemory/socket_api.c
+++ b/src/vlibmemory/socket_api.c
@@ -805,14 +805,11 @@ socksvr_config (vlib_main_t * vm, unformat_input_t * input)
 
 VLIB_CONFIG_FUNCTION (socksvr_config, "socksvr");
 
-clib_error_t *
-vlibsocket_init (vlib_main_t * vm)
+void
+vlibsocket_reference ()
 {
-  return 0;
 }
 
-VLIB_INIT_FUNCTION (vlibsocket_init);
-
 /*
  * fd.io coding-style-patch-verification: ON
  *
diff --git a/src/vlibmemory/vlib_api.c b/src/vlibmemory/vlib_api.c
index 7763a88becf..73dd5bda33c 100644
--- a/src/vlibmemory/vlib_api.c
+++ b/src/vlibmemory/vlib_api.c
@@ -306,7 +306,7 @@ vl_api_clnt_process (vlib_main_t * vm, vlib_node_runtime_t * node,
   q = shm->vl_input_queue;
 
   e = vlib_call_init_exit_functions
-    (vm, vm->api_init_function_registrations, 1 /* call_once */ );
+    (vm, &vm->api_init_function_registrations, 1 /* call_once */ );
   if (e)
     clib_error_report (e);