vat: unload unused vat plugins

If the corresponding vpp plugin is absent, return a non-zero
clib_error_t * from vat_plugin_register ("xxx plugin not loaded"). The
vat plugin calls dlclose on the vat plugin, and it disappears.

Depending on the plugin configuration, this can reduce the vpp virtual
size by several gigabytes.

Added a VAT_PLUGIN(<plugin-name>) macro to vat_helper_macros, clean up
boilerplate vat_plugin_register() implementations. Fixed a number of
non-standard vat_plugin_register methods.

Type: refactor

Change-Id: Iac908e5af7d5497c78d6aa9c3c51cdae08374045
Signed-off-by: Dave Barach <dave@barachs.net>

20 files changed, 68 insertions, 287 deletions

diff --git a/src/plugins/acl/acl_test.c b/src/plugins/acl/acl_test.c
index 19a6f915381..9185cc12329 100644
--- a/src/plugins/acl/acl_test.c
+++ b/src/plugins/acl/acl_test.c
@@ -1489,7 +1489,7 @@ _(acl_plugin_get_conn_table_max_entries, "")
 
 
 static
-void acl_vat_api_hookup (vat_main_t *vam)
+void acl_api_hookup (vat_main_t *vam)
 {
     acl_test_main_t * sm = &acl_test_main;
     /* Hook up handlers for replies from the data plane plug-in */
@@ -1515,20 +1515,4 @@ void acl_vat_api_hookup (vat_main_t *vam)
 #undef _
 }
 
-clib_error_t * vat_plugin_register (vat_main_t *vam)
-{
-  acl_test_main_t * sm = &acl_test_main;
-  u8 * name;
-
-  sm->vat_main = vam;
-
-  name = format (0, "acl_%08x%c", api_version, 0);
-  sm->msg_id_base = vl_client_get_first_plugin_msg_id ((char *) name);
-
-  if (sm->msg_id_base != (u16) ~0)
-    acl_vat_api_hookup (vam);
-
-  vec_free(name);
-
-  return 0;
-}
+VAT_PLUGIN_REGISTER(acl);
diff --git a/src/plugins/avf/avf_test.c b/src/plugins/avf/avf_test.c
index 368d5035bb9..17f43088b10 100644
--- a/src/plugins/avf/avf_test.c
+++ b/src/plugins/avf/avf_test.c
@@ -202,7 +202,7 @@ _(avf_create, "<pci-address> [rx-queue-size <size>] "		\
 _(avf_delete, "<sw_if_index>")
 
 static void
-avf_vat_api_hookup (vat_main_t * vam)
+avf_api_hookup (vat_main_t * vam)
 {
   avf_test_main_t *avm __attribute__ ((unused)) = &avf_test_main;
 #define _(N,n)                                                  \
@@ -226,24 +226,7 @@ avf_vat_api_hookup (vat_main_t * vam)
 #undef _
 }
 
-clib_error_t *
-vat_plugin_register (vat_main_t * vam)
-{
-  avf_test_main_t *avm = &avf_test_main;
-  u8 *name;
-
-  avm->vat_main = vam;
-
-  name = format (0, "avf_%08x%c", api_version, 0);
-  avm->msg_id_base = vl_client_get_first_plugin_msg_id ((char *) name);
-
-  if (avm->msg_id_base != (u16) ~ 0)
-    avf_vat_api_hookup (vam);
-
-  vec_free (name);
-
-  return 0;
-}
+VAT_PLUGIN_REGISTER (avf);
 
 /*
  * fd.io coding-style-patch-verification: ON
diff --git a/src/plugins/cdp/cdp_test.c b/src/plugins/cdp/cdp_test.c
index 33b54498f7f..2e24ddc8c0a 100644
--- a/src/plugins/cdp/cdp_test.c
+++ b/src/plugins/cdp/cdp_test.c
@@ -150,25 +150,7 @@ cdp_api_hookup (vat_main_t * vam)
 #undef _
 }
 
-clib_error_t *
-vat_plugin_register (vat_main_t * vam)
-{
-  cdp_test_main_t *sm = &cdp_test_main;
-  u8 *name;
-
-  sm->vat_main = vam;
-
-  /* Ask the vpp engine for the first assigned message-id */
-  name = format (0, "cdp_%08x%c", api_version, 0);
-  sm->msg_id_base = vl_client_get_first_plugin_msg_id ((char *) name);
-
-  if (sm->msg_id_base != (u16) ~ 0)
-    cdp_api_hookup (vam);
-
-  vec_free (name);
-
-  return 0;
-}
+VAT_PLUGIN_REGISTER (cdp);
 
 /*
  * fd.io coding-style-patch-verification: ON
diff --git a/src/plugins/ct6/ct6_test.c b/src/plugins/ct6/ct6_test.c
index 507620eaf0b..2f985a60970 100644
--- a/src/plugins/ct6/ct6_test.c
+++ b/src/plugins/ct6/ct6_test.c
@@ -173,25 +173,7 @@ ct6_api_hookup (vat_main_t * vam)
 #undef _
 }
 
-clib_error_t *
-vat_plugin_register (vat_main_t * vam)
-{
-  ct6_test_main_t *ctmp = &ct6_test_main;
-  u8 *name;
-
-  ctmp->vat_main = vam;
-
-  /* Ask the vpp engine for the first assigned message-id */
-  name = format (0, "ct6_%08x%c", api_version, 0);
-  ctmp->msg_id_base = vl_client_get_first_plugin_msg_id ((char *) name);
-
-  if (ctmp->msg_id_base != (u16) ~ 0)
-    ct6_api_hookup (vam);
-
-  vec_free (name);
-
-  return 0;
-}
+VAT_PLUGIN_REGISTER (ct6);
 
 /*
  * fd.io coding-style-patch-verification: ON
diff --git a/src/plugins/dpdk/api/dpdk_test.c b/src/plugins/dpdk/api/dpdk_test.c
index 637b4016111..4594a9d3b81 100644
--- a/src/plugins/dpdk/api/dpdk_test.c
+++ b/src/plugins/dpdk/api/dpdk_test.c
@@ -77,7 +77,7 @@ _(sw_interface_set_dpdk_hqos_tctbl_reply)
 foreach_standard_reply_retval_handler;
 #undef _
 
-/* 
+/*
  * Table of message reply handlers, must include boilerplate handlers
  * we just generated
  */
@@ -336,7 +336,7 @@ api_sw_interface_set_dpdk_hqos_tctbl (vat_main_t * vam)
   return 0;
 }
 
-/* 
+/*
  * List of messages that the api test plugin sends,
  * and that the data plane plugin processes
  */
@@ -361,36 +361,19 @@ static void dpdk_api_hookup (vat_main_t *vam)
                           vl_noop_handler,                      \
                           vl_api_##n##_t_endian,                \
                           vl_api_##n##_t_print,                 \
-                          sizeof(vl_api_##n##_t), 1); 
+                          sizeof(vl_api_##n##_t), 1);
   foreach_vpe_api_reply_msg;
 #undef _
 
   /* API messages we can send */
 #define _(n,h) hash_set_mem (vam->function_by_name, #n, api_##n);
   foreach_vpe_api_msg;
-#undef _    
-    
+#undef _
+
   /* Help strings */
 #define _(n,h) hash_set_mem (vam->help_by_name, #n, h);
   foreach_vpe_api_msg;
 #undef _
 }
 
-clib_error_t * vat_plugin_register (vat_main_t *vam)
-{
-  dpdk_test_main_t * dm = &dpdk_test_main;
-  u8 * name;
-
-  dm->vat_main = vam;
-
-  /* Ask the vpp engine for the first assigned message-id */
-  name = format (0, "dpdk_%08x%c", api_version, 0);
-  dm->msg_id_base = vl_client_get_first_plugin_msg_id ((char *) name);
-
-  if (dm->msg_id_base != (u16) ~0)
-    dpdk_api_hookup (vam);
-  
-  vec_free(name);
-  
-  return 0;
-}
+VAT_PLUGIN_REGISTER(dpdk);
diff --git a/src/plugins/flowprobe/flowprobe_test.c b/src/plugins/flowprobe/flowprobe_test.c
index 19b7a733795..53fdb23be5d 100644
--- a/src/plugins/flowprobe/flowprobe_test.c
+++ b/src/plugins/flowprobe/flowprobe_test.c
@@ -206,7 +206,7 @@ _(flowprobe_tx_interface_add_del, "<intfc> [disable]") \
 _(flowprobe_params, "record <[l2] [l3] [l4]> [active <timer> passive <timer>]")
 
 static void
-flowprobe_vat_api_hookup (vat_main_t * vam)
+flowprobe_api_hookup (vat_main_t * vam)
 {
   flowprobe_test_main_t *sm = &flowprobe_test_main;
   /* Hook up handlers for replies from the data plane plug-in */
@@ -232,26 +232,7 @@ flowprobe_vat_api_hookup (vat_main_t * vam)
 #undef _
 }
 
-clib_error_t *
-vat_plugin_register (vat_main_t * vam)
-{
-  flowprobe_test_main_t *sm = &flowprobe_test_main;
-  u8 *name;
-
-  sm->vat_main = vam;
-
-  /* Ask the vpp engine for the first assigned message-id */
-  name = format (0, "flowprobe_%08x%c", api_version, 0);
-  sm->msg_id_base = vl_client_get_first_plugin_msg_id ((char *) name);
-
-  /* Don't attempt to hook up API messages if the data plane plugin is AWOL */
-  if (sm->msg_id_base != (u16) ~ 0)
-    flowprobe_vat_api_hookup (vam);
-
-  vec_free (name);
-
-  return 0;
-}
+VAT_PLUGIN_REGISTER (flowprobe);
 
 /*
  * fd.io coding-style-patch-verification: ON
diff --git a/src/plugins/gtpu/gtpu_test.c b/src/plugins/gtpu/gtpu_test.c
index f9812c65ccf..5e9afa257d0 100644
--- a/src/plugins/gtpu/gtpu_test.c
+++ b/src/plugins/gtpu/gtpu_test.c
@@ -450,7 +450,7 @@ _(gtpu_add_del_tunnel,                                                 \
 _(gtpu_tunnel_dump, "[<intfc> | sw_if_index <nn>]")                    \
 
 static void
-gtpu_vat_api_hookup (vat_main_t *vam)
+gtpu_api_hookup (vat_main_t *vam)
 {
   gtpu_test_main_t * gtm = &gtpu_test_main;
   /* Hook up handlers for replies from the data plane plug-in */
@@ -476,22 +476,4 @@ gtpu_vat_api_hookup (vat_main_t *vam)
 #undef _
 }
 
-clib_error_t * vat_plugin_register (vat_main_t *vam)
-{
-  gtpu_test_main_t * gtm = &gtpu_test_main;
-
-  u8 * name;
-
-  gtm->vat_main = vam;
-
-  /* Ask the vpp engine for the first assigned message-id */
-  name = format (0, "gtpu_%08x%c", api_version, 0);
-  gtm->msg_id_base = vl_client_get_first_plugin_msg_id ((char *) name);
-
-  if (gtm->msg_id_base != (u16) ~0)
-    gtpu_vat_api_hookup (vam);
-
-  vec_free(name);
-
-  return 0;
-}
+VAT_PLUGIN_REGISTER(gtpu);
diff --git a/src/plugins/http_static/http_static_test.c b/src/plugins/http_static/http_static_test.c
index 0720463cf63..545980b38dd 100644
--- a/src/plugins/http_static/http_static_test.c
+++ b/src/plugins/http_static/http_static_test.c
@@ -208,25 +208,7 @@ http_static_api_hookup (vat_main_t * vam)
 #undef _
 }
 
-clib_error_t *
-vat_plugin_register (vat_main_t * vam)
-{
-  http_static_test_main_t *htmp = &http_static_test_main;
-  u8 *name;
-
-  htmp->vat_main = vam;
-
-  /* Ask the vpp engine for the first assigned message-id */
-  name = format (0, "http_static_%08x%c", api_version, 0);
-  htmp->msg_id_base = vl_client_get_first_plugin_msg_id ((char *) name);
-
-  if (htmp->msg_id_base != (u16) ~ 0)
-    http_static_api_hookup (vam);
-
-  vec_free (name);
-
-  return 0;
-}
+VAT_PLUGIN_REGISTER (http_static);
 
 /*
  * fd.io coding-style-patch-verification: ON
diff --git a/src/plugins/ikev2/ikev2_test.c b/src/plugins/ikev2/ikev2_test.c
index 68c50684824..57724b84161 100644
--- a/src/plugins/ikev2/ikev2_test.c
+++ b/src/plugins/ikev2/ikev2_test.c
@@ -807,7 +807,7 @@ _(ikev2_initiate_del_child_sa, "<ispi>")                                \
 _(ikev2_initiate_rekey_child_sa, "<ispi>")
 
 static void
-ikev2_vat_api_hookup (vat_main_t * vam)
+ikev2_api_hookup (vat_main_t * vam)
 {
   ikev2_test_main_t *sm = &ikev2_test_main;
   /* Hook up handlers for replies from the data plane plug-in */
@@ -833,24 +833,7 @@ ikev2_vat_api_hookup (vat_main_t * vam)
 #undef _
 }
 
-clib_error_t *
-vat_plugin_register (vat_main_t * vam)
-{
-  ikev2_test_main_t *sm = &ikev2_test_main;
-  u8 *name;
-
-  sm->vat_main = vam;
-
-  name = format (0, "ikev2_%08x%c", api_version, 0);
-  sm->msg_id_base = vl_client_get_first_plugin_msg_id ((char *) name);
-
-  if (sm->msg_id_base != (u16) ~ 0)
-    ikev2_vat_api_hookup (vam);
-
-  vec_free (name);
-
-  return 0;
-}
+VAT_PLUGIN_REGISTER (ikev2);
 
 /*
  * fd.io coding-style-patch-verification: ON
diff --git a/src/plugins/ioam/lib-pot/pot_test.c b/src/plugins/ioam/lib-pot/pot_test.c
index e02640b44dc..d0cf49eea37 100644
--- a/src/plugins/ioam/lib-pot/pot_test.c
+++ b/src/plugins/ioam/lib-pot/pot_test.c
@@ -111,7 +111,7 @@ foreach_standard_reply_retval_handler;
 foreach_custom_reply_retval_handler;
 #undef _
 
-/* 
+/*
  * Table of message reply handlers, must include boilerplate handlers
  * we just generated
  */
@@ -167,7 +167,7 @@ static int api_pot_profile_add (vat_main_t *vam)
         rv = -99;
         goto OUT;
       }
-    
+
     M2(POT_PROFILE_ADD, mp, vec_len(name));
 
     mp->list_name_len = vec_len(name);
@@ -187,11 +187,11 @@ static int api_pot_profile_add (vat_main_t *vam)
       }
     mp->id = id;
     mp->max_bits = bits;
-      
+
     S(mp);
     W (ret);
     return ret;
-  
+
 OUT:
     vec_free(name);
     return(rv);
@@ -206,7 +206,7 @@ static int api_pot_profile_activate (vat_main_t *vam)
     u8 id = 0;
     int rv = 0;
     int ret;
-    
+
     while (unformat_check_input(input) != UNFORMAT_END_OF_INPUT)
       {
         if (unformat(input, "name %s", &name))
@@ -223,17 +223,17 @@ static int api_pot_profile_activate (vat_main_t *vam)
         rv = -99;
         goto OUT;
       }
-    
+
     M2(POT_PROFILE_ACTIVATE, mp, vec_len(name));
 
     mp->list_name_len = vec_len(name);
     clib_memcpy(mp->list_name, name, mp->list_name_len);
     mp->id = id;
-      
+
     S(mp);
     W (ret);
     return ret;
-  
+
 OUT:
     vec_free(name);
     return(rv);
@@ -244,7 +244,7 @@ static int api_pot_profile_del (vat_main_t *vam)
 {
     vl_api_pot_profile_del_t *mp;
     int ret;
-   
+
     M(POT_PROFILE_DEL, mp);
     mp->list_name_len = 0;
     S(mp);
@@ -274,7 +274,7 @@ static int api_pot_profile_show_config_dump (vat_main_t *vam)
     return ret;
 }
 
-/* 
+/*
  * List of messages that the api test plugin sends,
  * and that the data plane plugin processes
  */
@@ -287,7 +287,7 @@ _(pot_profile_activate, "name <name> id [0-1] ")    			\
 _(pot_profile_del, "[id <nn>]")                                         \
 _(pot_profile_show_config_dump, "id [0-1]")
 
-static void 
+static void
 pot_vat_api_hookup (vat_main_t *vam)
 {
     pot_test_main_t * sm = &pot_test_main;
@@ -299,21 +299,22 @@ pot_vat_api_hookup (vat_main_t *vam)
                            vl_noop_handler,                     \
                            vl_api_##n##_t_endian,               \
                            vl_api_##n##_t_print,                \
-                           sizeof(vl_api_##n##_t), 1); 
+                           sizeof(vl_api_##n##_t), 1);
     foreach_vpe_api_reply_msg;
 #undef _
 
     /* API messages we can send */
 #define _(n,h) hash_set_mem (vam->function_by_name, #n, api_##n);
     foreach_vpe_api_msg;
-#undef _    
-    
+#undef _
+
     /* Help strings */
 #define _(n,h) hash_set_mem (vam->help_by_name, #n, h);
     foreach_vpe_api_msg;
 #undef _
 }
 
+
 clib_error_t *
 pot_vat_plugin_register (vat_main_t *vam)
 {
@@ -324,11 +325,12 @@ pot_vat_plugin_register (vat_main_t *vam)
 
   name = format (0, "ioam_pot_%08x%c", api_version, 0);
   sm->msg_id_base = vl_client_get_first_plugin_msg_id ((char *) name);
+  vec_free(name);
 
   if (sm->msg_id_base != (u16) ~0)
     pot_vat_api_hookup (vam);
-  
-  vec_free(name);
-  
+  else
+    return clib_error_return (0, "ioam_pot plugin not loaded...");
+
   return 0;
 }
diff --git a/src/plugins/lacp/lacp_test.c b/src/plugins/lacp/lacp_test.c
index 0a8631d4df1..4e28a6d80bd 100644
--- a/src/plugins/lacp/lacp_test.c
+++ b/src/plugins/lacp/lacp_test.c
@@ -206,6 +206,10 @@ vat_plugin_register (vat_main_t * vam)
   /* Ask the vpp engine for the first assigned message-id */
   name = format (0, "lacp_%08x%c", api_version, 0);
   lm->msg_id_base = vl_client_get_first_plugin_msg_id ((char *) name);
+  vec_free (name);
+
+  if (lm->msg_id_base == (u16) ~ 0)
+    return clib_error_return (0, "lacp plugin not loaded...");
 
   /* Get the control ping ID */
 #define _(id,n,crc) \
@@ -217,8 +221,6 @@ vat_plugin_register (vat_main_t * vam)
   if (lm->msg_id_base != (u16) ~ 0)
     lacp_vat_api_hookup (vam);
 
-  vec_free (name);
-
   return 0;
 }
 
diff --git a/src/plugins/lb/lb_test.c b/src/plugins/lb/lb_test.c
index 00ad673d354..4ac306bba1c 100644
--- a/src/plugins/lb/lb_test.c
+++ b/src/plugins/lb/lb_test.c
@@ -349,8 +349,8 @@ _(lb_add_del_vip, "<prefix> "  \
 _(lb_add_del_as, "<vip-prefix> [protocol (tcp|udp) port <n>] "  \
                  "[<address>] [del] [flush]")
 
-static void 
-lb_vat_api_hookup (vat_main_t *vam)
+static void
+lb_api_hookup (vat_main_t *vam)
 {
   lb_test_main_t * lbtm = &lb_test_main;
   /* Hook up handlers for replies from the data plane plug-in */
@@ -376,22 +376,4 @@ lb_vat_api_hookup (vat_main_t *vam)
 #undef _
 }
 
-clib_error_t * vat_plugin_register (vat_main_t *vam)
-{
-  lb_test_main_t * lbtm = &lb_test_main;
-
-  u8 * name;
-
-  lbtm->vat_main = vam;
-
-  /* Ask the vpp engine for the first assigned message-id */
-  name = format (0, "lb_%08x%c", api_version, 0);
-  lbtm->msg_id_base = vl_client_get_first_plugin_msg_id ((char *) name);
-
-  if (lbtm->msg_id_base != (u16) ~0)
-    lb_vat_api_hookup (vam);
-
-  vec_free(name);
-
-  return 0;
-}
+VAT_PLUGIN_REGISTER(lb);
diff --git a/src/plugins/mactime/mactime_test.c b/src/plugins/mactime/mactime_test.c
index 4557e57dbff..c9c1a475ad9 100644
--- a/src/plugins/mactime/mactime_test.c
+++ b/src/plugins/mactime/mactime_test.c
@@ -300,25 +300,7 @@ mactime_api_hookup (vat_main_t * vam)
 #undef _
 }
 
-clib_error_t *
-vat_plugin_register (vat_main_t * vam)
-{
-  mactime_test_main_t *sm = &mactime_test_main;
-  u8 *name;
-
-  sm->vat_main = vam;
-
-  /* Ask the vpp engine for the first assigned message-id */
-  name = format (0, "mactime_%08x%c", api_version, 0);
-  sm->msg_id_base = vl_client_get_first_plugin_msg_id ((char *) name);
-
-  if (sm->msg_id_base != (u16) ~ 0)
-    mactime_api_hookup (vam);
-
-  vec_free (name);
-
-  return 0;
-}
+VAT_PLUGIN_REGISTER (mactime);
 
 /*
  * fd.io coding-style-patch-verification: ON
diff --git a/src/plugins/memif/memif_test.c b/src/plugins/memif/memif_test.c
index 510462ef6a8..e26094b82a8 100644
--- a/src/plugins/memif/memif_test.c
+++ b/src/plugins/memif/memif_test.c
@@ -482,6 +482,10 @@ vat_plugin_register (vat_main_t * vam)
   /* Ask the vpp engine for the first assigned message-id */
   name = format (0, "memif_%08x%c", api_version, 0);
   mm->msg_id_base = vl_client_get_first_plugin_msg_id ((char *) name);
+  vec_free (name);
+
+  if (mm->msg_id_base == (u16) ~ 0)
+    return clib_error_return (0, "memif plugin not loaded...");
 
   /* Get the control ping ID */
 #define _(id,n,crc) \
@@ -493,8 +497,6 @@ vat_plugin_register (vat_main_t * vam)
   if (mm->msg_id_base != (u16) ~ 0)
     memif_vat_api_hookup (vam);
 
-  vec_free (name);
-
   return 0;
 }
 
diff --git a/src/plugins/nat/nat_test.c b/src/plugins/nat/nat_test.c
index 0371ec48553..1dd25b31205 100644
--- a/src/plugins/nat/nat_test.c
+++ b/src/plugins/nat/nat_test.c
@@ -1171,11 +1171,12 @@ clib_error_t * vat_plugin_register (vat_main_t *vam)
   /* Ask the vpp engine for the first assigned message-id */
   name = format (0, "nat_%08x%c", api_version, 0);
   sm->msg_id_base = vl_client_get_first_plugin_msg_id ((char *) name);
+  vec_free(name);
 
   if (sm->msg_id_base != (u16) ~0)
     snat_vat_api_hookup (vam);
-
-  vec_free(name);
+  else
+    return clib_error_return (0, "nat plugin not loaded...");
 
   return 0;
 }
diff --git a/src/plugins/nsh/nsh_test.c b/src/plugins/nsh/nsh_test.c
index 0852956dc3e..091ad97dfe9 100644
--- a/src/plugins/nsh/nsh_test.c
+++ b/src/plugins/nsh/nsh_test.c
@@ -402,11 +402,12 @@ clib_error_t * vat_plugin_register (vat_main_t *vam)
   /* Ask the vpp engine for the first assigned message-id */
   name = format (0, "nsh_%08x%c", api_version, 0);
   sm->msg_id_base = vl_client_get_first_plugin_msg_id ((char *) name);
+  vec_free(name);
 
   if (sm->msg_id_base != (u16) ~0)
     nsh_vat_api_hookup (vam);
-
-  vec_free(name);
+  else
+    return clib_error_return (0, "nsh plugin not loaded...");
 
   return 0;
 }
diff --git a/src/plugins/nsim/nsim_test.c b/src/plugins/nsim/nsim_test.c
index e3c95c7c204..3e38bd04305 100644
--- a/src/plugins/nsim/nsim_test.c
+++ b/src/plugins/nsim/nsim_test.c
@@ -306,25 +306,7 @@ nsim_api_hookup (vat_main_t * vam)
 #undef _
 }
 
-clib_error_t *
-vat_plugin_register (vat_main_t * vam)
-{
-  nsim_test_main_t *sm = &nsim_test_main;
-  u8 *name;
-
-  sm->vat_main = vam;
-
-  /* Ask the vpp engine for the first assigned message-id */
-  name = format (0, "nsim_%08x%c", api_version, 0);
-  sm->msg_id_base = vl_client_get_first_plugin_msg_id ((char *) name);
-
-  if (sm->msg_id_base != (u16) ~ 0)
-    nsim_api_hookup (vam);
-
-  vec_free (name);
-
-  return 0;
-}
+VAT_PLUGIN_REGISTER (nsim);
 
 /*
  * fd.io coding-style-patch-verification: ON
diff --git a/src/plugins/pppoe/pppoe_test.c b/src/plugins/pppoe/pppoe_test.c
index 0d085ed3d97..d8ad19dc175 100644
--- a/src/plugins/pppoe/pppoe_test.c
+++ b/src/plugins/pppoe/pppoe_test.c
@@ -283,7 +283,7 @@ _(pppoe_add_del_session,                                                 \
 _(pppoe_session_dump, "[<intfc> | sw_if_index <nn>]")                    \
 
 static void
-pppoe_vat_api_hookup (vat_main_t *vam)
+pppoe_api_hookup (vat_main_t *vam)
 {
   pppoe_test_main_t * pem = &pppoe_test_main;
   /* Hook up handlers for replies from the data plane plug-in */
@@ -309,22 +309,4 @@ pppoe_vat_api_hookup (vat_main_t *vam)
 #undef _
 }
 
-clib_error_t * vat_plugin_register (vat_main_t *vam)
-{
-  pppoe_test_main_t * pem = &pppoe_test_main;
-
-  u8 * name;
-
-  pem->vat_main = vam;
-
-  /* Ask the vpp engine for the first assigned message-id */
-  name = format (0, "pppoe_%08x%c", api_version, 0);
-  pem->msg_id_base = vl_client_get_first_plugin_msg_id ((char *) name);
-
-  if (pem->msg_id_base != (u16) ~0)
-    pppoe_vat_api_hookup (vam);
-
-  vec_free(name);
-
-  return 0;
-}
+VAT_PLUGIN_REGISTER(pppoe);
diff --git a/src/plugins/stn/stn_test.c b/src/plugins/stn/stn_test.c
index 8fdbeb926b6..40ebd77d914 100644
--- a/src/plugins/stn/stn_test.c
+++ b/src/plugins/stn/stn_test.c
@@ -154,6 +154,10 @@ vat_plugin_register (vat_main_t * vam)
 
   name = format (0, "stn_%08x%c", api_version, 0);
   sm->msg_id_base = vl_client_get_first_plugin_msg_id ((char *) name);
+  vec_free (name);
+
+  if (sm->msg_id_base == (u16) ~ 0)
+    return clib_error_return (0, "stn plugin not loaded...");
 
   /* Get the control ping ID */
 #define _(id,n,crc) \
@@ -165,8 +169,6 @@ vat_plugin_register (vat_main_t * vam)
   if (sm->msg_id_base != (u16) ~ 0)
     stn_vat_api_hookup (vam);
 
-  vec_free (name);
-
   return 0;
 }
 
diff --git a/src/plugins/vmxnet3/vmxnet3_test.c b/src/plugins/vmxnet3/vmxnet3_test.c
index d32bceefe5b..7a70f619a55 100644
--- a/src/plugins/vmxnet3/vmxnet3_test.c
+++ b/src/plugins/vmxnet3/vmxnet3_test.c
@@ -330,6 +330,10 @@ vat_plugin_register (vat_main_t * vam)
 
   name = format (0, "vmxnet3_%08x%c", api_version, 0);
   vxm->msg_id_base = vl_client_get_first_plugin_msg_id ((char *) name);
+  vec_free (name);
+
+  if (vxm->msg_id_base == (u16) ~ 0)
+    return clib_error_return (0, "vmxnet3 plugin not loaded...");
 
   /* Get the control ping ID */
 #define _(id,n,crc) \
@@ -338,10 +342,7 @@ vat_plugin_register (vat_main_t * vam)
 #undef _
   vxm->ping_id = vl_msg_api_get_msg_index ((u8 *) (VL_API_CONTROL_PING_CRC));
 
-  if (vxm->msg_id_base != (u16) ~ 0)
-    vmxnet3_vat_api_hookup (vam);
-
-  vec_free (name);
+  vmxnet3_vat_api_hookup (vam);
 
   return 0;
 }