[HICN-342] No need to take a lock on the hash entry if the lookup for

a data hit the CS. Data packets coming from the network are dropped,
data packets coming from an application face are either dropped or
sent to the push node (which does not require a lock on the hash
entry)

Change-Id: Icf662dffa33b9dda2e2a69fc2104a69a82ef19fd
Signed-off-by: Alberto Compagno <acompagn+fdio@cisco.com>

2 files changed, 45 insertions, 35 deletions

diff --git a/hicn-plugin/src/data_pcslookup_node.c b/hicn-plugin/src/data_pcslookup_node.c
index fdf855e57..1ae36202f 100644
--- a/hicn-plugin/src/data_pcslookup_node.c
+++ b/hicn-plugin/src/data_pcslookup_node.c
@@ -14,12 +14,12 @@
  */
 
 #include "data_pcslookup.h"
+#include "infra.h"
 #include "mgmt.h"
 #include "parser.h"
-#include "infra.h"
+#include "state.h"
 #include "strategy.h"
 #include "strategy_dpo_manager.h"
-#include "state.h"
 
 /* Stats string values */
 static char *hicn_data_pcslookup_error_strings[] = {
@@ -37,10 +37,9 @@ vlib_node_registration_t hicn_data_pcslookup_node;
  * hICN node for handling data. It performs a lookup in the PIT.
  */
 static uword
-hicn_data_pcslookup_node_fn (vlib_main_t * vm, vlib_node_runtime_t * node,
-			     vlib_frame_t * frame)
+hicn_data_pcslookup_node_fn (vlib_main_t * vm,
+			     vlib_node_runtime_t * node, vlib_frame_t * frame)
 {
-
   u32 n_left_from, *from, *to_next;
   hicn_data_pcslookup_next_t next_index;
   hicn_data_pcslookup_runtime_t *rt;
@@ -87,7 +86,8 @@ hicn_data_pcslookup_node_fn (vlib_main_t * vm, vlib_node_runtime_t * node,
 	    {
 	      vlib_buffer_t *b1;
 	      b1 = vlib_get_buffer (vm, from[1]);
-	      //Prefetch two cache lines-- 128 byte-- so that we load the hicn_buffer_t as well
+	      // Prefetch two cache lines-- 128 byte-- so that we load the
+	      // hicn_buffer_t as well
 	      CLIB_PREFETCH (b1, 2 * CLIB_CACHE_LINE_BYTES, STORE);
 	      CLIB_PREFETCH (b1->data, CLIB_CACHE_LINE_BYTES, LOAD);
 	    }
@@ -99,10 +99,9 @@ hicn_data_pcslookup_node_fn (vlib_main_t * vm, vlib_node_runtime_t * node,
 	  to_next += 1;
 	  n_left_to_next -= 1;
 
-
 	  b0 = vlib_get_buffer (vm, bi0);
 	  hb0 = hicn_get_buffer (b0);
-          next0 = HICN_DATA_PCSLOOKUP_NEXT_ERROR_DROP;
+	  next0 = HICN_DATA_PCSLOOKUP_NEXT_ERROR_DROP;
 
 	  /* Incr packet counter */
 	  stats.pkts_processed += 1;
@@ -111,26 +110,24 @@ hicn_data_pcslookup_node_fn (vlib_main_t * vm, vlib_node_runtime_t * node,
 	  nameptr = (u8 *) (&name);
 
 	  if (PREDICT_TRUE (ret0 == HICN_ERROR_NONE &&
-                            hicn_hashtb_fullhash (nameptr, namelen,
-                                                  &name_hash) == HICN_ERROR_NONE))
+			    hicn_hashtb_fullhash (nameptr, namelen,
+						  &name_hash) ==
+			    HICN_ERROR_NONE))
 	    {
 	      int res =
 		hicn_hashtb_lookup_node (rt->pitcs->pcs_table, nameptr,
 					 namelen, name_hash,
-					 !(hb0->flags &
-					   HICN_BUFFER_FLAGS_FACE_IS_APP)
-					 /* take lock */ ,
+					 1 /*is_data. Do not take lock if hit CS */ ,
 					 &node_id0, &dpo_ctx_id0, &vft_id0,
-					 &is_cs0,
-					 &hash_entry_id, &bucket_id,
+					 &is_cs0, &hash_entry_id, &bucket_id,
 					 &bucket_is_overflown);
 
 	      stats.pkts_data_count += 1;
 
 #if HICN_FEATURE_CS
-	      if ((res == HICN_ERROR_HASHTB_HASH_NOT_FOUND
-		   || (res == HICN_ERROR_NONE && is_cs0))
-		  && ((hb0->flags & HICN_BUFFER_FLAGS_FACE_IS_APP)))
+	      if ((res == HICN_ERROR_HASHTB_HASH_NOT_FOUND ||
+		   (res == HICN_ERROR_NONE && is_cs0)) &&
+		  ((hb0->flags & HICN_BUFFER_FLAGS_FACE_IS_APP)))
 		{
 		  next0 = HICN_DATA_PCSLOOKUP_NEXT_STORE_DATA;
 		}
@@ -169,9 +166,8 @@ hicn_data_pcslookup_node_fn (vlib_main_t * vm, vlib_node_runtime_t * node,
 	   * Fix in case of a wrong speculation. Needed to
 	   * clone the data in the right frame
 	   */
-	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
-					   to_next, n_left_to_next,
-					   bi0, next0);
+	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index, to_next,
+					   n_left_to_next, bi0, next0);
 
 	  /* Maybe trace */
 	  if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE) &&
@@ -217,24 +213,22 @@ hicn_data_pcslookup_format_trace (u8 * s, va_list * args)
   return (s);
 }
 
-
 /*
  * Node registration for the data forwarder node
  */
 /* *INDENT-OFF* */
-VLIB_REGISTER_NODE (hicn_data_pcslookup_node) =
+VLIB_REGISTER_NODE(hicn_data_pcslookup_node) =
 {
   .function = hicn_data_pcslookup_node_fn,
   .name = "hicn-data-pcslookup",
-  .vector_size = sizeof (u32),
-  .runtime_data_bytes = sizeof (hicn_data_pcslookup_runtime_t),
+  .vector_size = sizeof(u32),
+  .runtime_data_bytes = sizeof(hicn_data_pcslookup_runtime_t),
   .format_trace = hicn_data_pcslookup_format_trace,
-  .type =  VLIB_NODE_TYPE_INTERNAL,
-  .n_errors = ARRAY_LEN (hicn_data_pcslookup_error_strings),
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  .n_errors = ARRAY_LEN(hicn_data_pcslookup_error_strings),
   .error_strings = hicn_data_pcslookup_error_strings,
   .n_next_nodes = HICN_DATA_PCSLOOKUP_N_NEXT,
-  .next_nodes =
-  {
+  .next_nodes = {
     [HICN_DATA_PCSLOOKUP_NEXT_V4_LOOKUP] = "ip4-lookup",
     [HICN_DATA_PCSLOOKUP_NEXT_V6_LOOKUP] = "ip6-lookup",
     [HICN_DATA_PCSLOOKUP_NEXT_STORE_DATA] = "hicn-data-push",
diff --git a/hicn-plugin/src/pcs.h b/hicn-plugin/src/pcs.h
index c7e8a4b59..d9c48954e 100644
--- a/hicn-plugin/src/pcs.h
+++ b/hicn-plugin/src/pcs.h
@@ -499,8 +499,16 @@ hicn_pcs_cs_update (vlib_main_t * vm, hicn_pit_cs_t * pitcs,
           policy_vft->hicn_cs_delete_get (pitcs, policy_state,
                                           &node, &pcs_entry, &hash_entry);
 
-          hicn_pcs_cs_delete (vm, pitcs, &pcs_entry, &node, hash_entry, NULL,
-                              NULL);
+          /*
+           * We don't have to decrease the lock (therefore we cannot
+           * use hicn_pcs_cs_delete function)
+           */
+          policy_vft->hicn_cs_dequeue (pitcs, node, pcs_entry, policy_state);
+
+          hicn_cs_delete_trimmed (pitcs, &pcs_entry, hash_entry, &node, vm);
+
+          /* Update the global CS counter */
+          pitcs->pcs_cs_count--;
         }
     }
   else
@@ -541,14 +549,14 @@ hicn_pcs_cs_delete (vlib_main_t * vm, hicn_pit_cs_t * pitcs,
     }
 
   /* A data could have been inserted in the CS through a push. In this case locks == 0 */
-  if (hash_entry->locks == 0 || hash_entry->locks == 1)
+  hash_entry->locks--;
+  if (hash_entry->locks == 0)
     {
       hicn_pcs_delete_internal
 	(pitcs, pcs_entryp, hash_entry, nodep, vm, dpo_vft, hicn_dpo_id);
     }
   else
     {
-      hash_entry->locks--;
       hash_entry->he_flags |= HICN_HASH_ENTRY_FLAG_DELETED;
     }
 }
@@ -603,8 +611,16 @@ hicn_pcs_cs_insert (vlib_main_t * vm, hicn_pit_cs_t * pitcs,
 	  policy_vft->hicn_cs_delete_get (pitcs, policy_state,
 					  &node, &pcs_entry, &hash_entry);
 
-	  hicn_pcs_cs_delete (vm, pitcs, &pcs_entry, &node, hash_entry, NULL,
-			      NULL);
+          /*
+           * We don't have to decrease the lock (therefore we cannot
+           * use hicn_pcs_cs_delete function)
+           */
+          policy_vft->hicn_cs_dequeue (pitcs, node, pcs_entry, policy_state);
+
+          hicn_cs_delete_trimmed (pitcs, &pcs_entry, hash_entry, &node, vm);
+
+          /* Update the global CS counter */
+          pitcs->pcs_cs_count--;
 	}
     }
   return ret;