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, 19 insertions, 41 deletions

diff --git a/src/vnet/ip/ip_init.c b/src/vnet/ip/ip_init.c
index 638cbd167db..b3ab90d6dc3 100644
--- a/src/vnet/ip/ip_init.c
+++ b/src/vnet/ip/ip_init.c
@@ -101,50 +101,28 @@ do {						\
       }
   }
 
-  if ((error = vlib_call_init_function (vm, vnet_main_init)))
-    return error;
-
-  if ((error = vlib_call_init_function (vm, ip4_init)))
-    return error;
-
-  if ((error = vlib_call_init_function (vm, ip6_init)))
-    return error;
-
-  if ((error = vlib_call_init_function (vm, icmp4_init)))
-    return error;
-
-  if ((error = vlib_call_init_function (vm, icmp6_init)))
-    return error;
-
-  if ((error = vlib_call_init_function (vm, ip6_hop_by_hop_init)))
-    return error;
-
-  if ((error = vlib_call_init_function (vm, udp_local_init)))
-    return error;
-
-  if ((error = vlib_call_init_function (vm, udp_init)))
-    return error;
-
-  if ((error = vlib_call_init_function (vm, ip_classify_init)))
-    return error;
-
-  if ((error = vlib_call_init_function (vm, in_out_acl_init)))
-    return error;
-
-  if ((error = vlib_call_init_function (vm, policer_classify_init)))
-    return error;
-
-  if ((error = vlib_call_init_function (vm, flow_classify_init)))
-    return error;
-
-  if ((error = vlib_call_init_function (vm, dns_init)))
-    return error;
-
   return error;
 }
 
-VLIB_INIT_FUNCTION (ip_main_init);
-
+/* *INDENT-OFF* */
+VLIB_INIT_FUNCTION (ip_main_init) =
+{
+  .init_order =
+  VLIB_INITS ("vnet_main_init",
+              "ip4_init",
+              "ip6_init",
+              "icmp4_init",
+              "icmp6_init",
+              "ip6_hop_by_hop_init",
+              "udp_local_init",
+              "udp_init",
+              "ip_classify_init",
+              "in_out_acl_init",
+              "policer_classify_init",
+              "flow_classify_init",
+              "dns_init"),
+};
+/* *INDENT-ON* */
 
 /*
  * fd.io coding-style-patch-verification: ON