feature: introduce feature arc end nodes

This change allows us to keep feature path disabled
until 1st feature is enabled. Enabling 1st feature also means
that end feature node is enabled helping feature arc tenants
to reach the end.

Change-Id: Idbd64e681bd2b42e7c67612074649e5ae51f46e6
Signed-off-by: Damjan Marion <damarion@cisco.com>

3 files changed, 35 insertions, 23 deletions

diff --git a/vnet/vnet/devices/devices.c b/vnet/vnet/devices/devices.c
index a1100194f3d..624cf76b2c2 100644
--- a/vnet/vnet/devices/devices.c
+++ b/vnet/vnet/devices/devices.c
@@ -52,6 +52,7 @@ VNET_FEATURE_ARC_INIT (device_input, static) =
 {
   .arc_name  = "device-input",
   .start_nodes = VNET_FEATURES ("device-input"),
+  .end_node = "ethernet-input",
   .arc_index_ptr = &feature_main.device_input_feature_arc_index,
 };
 
diff --git a/vnet/vnet/feature/feature.c b/vnet/vnet/feature/feature.c
index e1d172e5707..032fe784ace 100644
--- a/vnet/vnet/feature/feature.c
+++ b/vnet/vnet/feature/feature.c
@@ -108,6 +108,9 @@ vnet_feature_init (vlib_main_t * vm)
 	  freg = freg->next;
 	}
 
+      cm->end_feature_index =
+	vnet_get_feature_index (arc_index, areg->end_node);
+
       /* next */
       areg = areg->next;
       arc_index++;
@@ -118,25 +121,6 @@ vnet_feature_init (vlib_main_t * vm)
 
 VLIB_INIT_FUNCTION (vnet_feature_init);
 
-void
-vnet_config_update_feature_count (vnet_feature_main_t * fm, u8 arc,
-				  u32 sw_if_index, int is_add)
-{
-  uword bit_value;
-
-  vec_validate (fm->feature_count_by_sw_if_index[arc], sw_if_index);
-
-  fm->feature_count_by_sw_if_index[arc][sw_if_index] += is_add ? 1 : -1;
-
-  ASSERT (fm->feature_count_by_sw_if_index[arc][sw_if_index] >= 0);
-
-  bit_value = fm->feature_count_by_sw_if_index[arc][sw_if_index] > 0;
-
-  fm->sw_if_index_has_features[arc] =
-    clib_bitmap_set (fm->sw_if_index_has_features[arc], sw_if_index,
-		     bit_value);
-}
-
 u8
 vnet_get_feature_arc_index (const char *s)
 {
@@ -180,6 +164,9 @@ vnet_get_feature_index (u8 arc, const char *s)
   vnet_feature_registration_t *reg;
   uword *p;
 
+  if (s == 0)
+    return ~0;
+
   p = hash_get_mem (fm->next_feature_by_name[arc], s);
   if (p == 0)
     return ~0;
@@ -196,6 +183,8 @@ vnet_feature_enable_disable_with_index (u8 arc_index, u32 feature_index,
 {
   vnet_feature_main_t *fm = &feature_main;
   vnet_feature_config_main_t *cm;
+  i16 feature_count;
+  int is_first_or_last;
   u32 ci;
 
   if (arc_index == (u8) ~ 0)
@@ -209,8 +198,9 @@ vnet_feature_enable_disable_with_index (u8 arc_index, u32 feature_index,
   ci = cm->config_index_by_sw_if_index[sw_if_index];
 
   vec_validate (fm->feature_count_by_sw_if_index[arc_index], sw_if_index);
-  if (!enable_disable
-      && fm->feature_count_by_sw_if_index[arc_index][sw_if_index] < 1)
+  feature_count = fm->feature_count_by_sw_if_index[arc_index][sw_if_index];
+
+  if (!enable_disable && feature_count < 1)
     return 0;
 
   ci = (enable_disable
@@ -220,9 +210,27 @@ vnet_feature_enable_disable_with_index (u8 arc_index, u32 feature_index,
      n_feature_config_bytes);
   cm->config_index_by_sw_if_index[sw_if_index] = ci;
 
-  vnet_config_update_feature_count (fm, arc_index, sw_if_index,
-				    enable_disable);
+  /* update feature count */
+  enable_disable = (enable_disable > 0);
+  feature_count += enable_disable ? 1 : -1;
+  is_first_or_last = (feature_count == enable_disable);
+  ASSERT (feature_count >= 0);
+
+  if (is_first_or_last && cm->end_feature_index != ~0)
+    {
+      /*register end node */
+      ci = (enable_disable
+	    ? vnet_config_add_feature
+	    : vnet_config_del_feature)
+	(vlib_get_main (), &cm->config_main, ci, cm->end_feature_index, 0, 0);
+      cm->config_index_by_sw_if_index[sw_if_index] = ci;
+    }
+
+  fm->sw_if_index_has_features[arc_index] =
+    clib_bitmap_set (fm->sw_if_index_has_features[arc_index], sw_if_index,
+		     (feature_count > 0));
 
+  fm->feature_count_by_sw_if_index[arc_index][sw_if_index] = feature_count;
   return 0;
 }
 
diff --git a/vnet/vnet/feature/feature.h b/vnet/vnet/feature/feature.h
index 0b33f0567e9..b27aaf17804 100644
--- a/vnet/vnet/feature/feature.h
+++ b/vnet/vnet/feature/feature.h
@@ -29,6 +29,8 @@ typedef struct _vnet_feature_arc_registration
   /** Start nodes */
   char **start_nodes;
   int n_start_nodes;
+  /** End node */
+  char *end_node;
   /* Feature arc index, assigned by init function */
   u8 feature_arc_index;
   u8 *arc_index_ptr;
@@ -63,6 +65,7 @@ typedef struct vnet_feature_config_main_t_
 {
   vnet_config_main_t config_main;
   u32 *config_index_by_sw_if_index;
+  u32 end_feature_index;
 } vnet_feature_config_main_t;
 
 typedef struct