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>

1 files changed, 7 insertions, 5 deletions

diff --git a/src/plugins/crypto_ia32/main.c b/src/plugins/crypto_ia32/main.c
index 45bf34e7814..a02fc38f99e 100644
--- a/src/plugins/crypto_ia32/main.c
+++ b/src/plugins/crypto_ia32/main.c
@@ -97,10 +97,7 @@ crypto_ia32_init (vlib_main_t * vm)
 {
   crypto_ia32_main_t *cm = &crypto_ia32_main;
   vlib_thread_main_t *tm = vlib_get_thread_main ();
-  clib_error_t *error;
-
-  if ((error = vlib_call_init_function (vm, vnet_crypto_init)))
-    return error;
+  clib_error_t *error = 0;
 
   vec_validate_aligned (cm->per_thread_data, tm->n_vlib_mains - 1,
 			CLIB_CACHE_LINE_BYTES);
@@ -124,7 +121,12 @@ error:
   return error;
 }
 
-VLIB_INIT_FUNCTION (crypto_ia32_init);
+/* *INDENT-OFF* */
+VLIB_INIT_FUNCTION (crypto_ia32_init) =
+{
+  .runs_after = VLIB_INITS ("vnet_crypto_init"),
+};
+/* *INDENT-ON* */
 
 #include <vpp/app/version.h>