L2-LEARN:fix l2fib entry seq num not updated on hit (VPP-888)

fixed instability in l2bd_multi_instnce test - sometimes failing with extra
packets captured

it appears l2-learn was not updating hit entries but rather a copy of them.

if the ager did not have a chance to run before the test was running the
learning cycle - entries were not updated with the packet's seq num - causing
packets to flood when hitting the stale seq_num in l2-fwd - hence the extra
packets

fixed handling of filter entries

revert workaround for instability in test

Change-Id: I16d918e6310a5bf40bad5b7335b2140c2867cb71
Signed-off-by: Eyal Bari <ebari@cisco.com>
(cherry picked from commit 25ff2ea3a31e422094f6d91eab46222a29a77c4b)

5 files changed, 64 insertions, 87 deletions

diff --git a/src/vnet/l2/l2_api.c b/src/vnet/l2/l2_api.c
index aa3dcb7e49e..a0b40d6d840 100644
--- a/src/vnet/l2/l2_api.c
+++ b/src/vnet/l2/l2_api.c
@@ -187,30 +187,24 @@ vl_api_l2fib_add_del_t_handler (vl_api_l2fib_add_del_t * mp)
   l2input_main_t *l2im = &l2input_main;
   vl_api_l2fib_add_del_reply_t *rmp;
   int rv = 0;
-  u64 mac = 0;
-  u32 sw_if_index = ntohl (mp->sw_if_index);
   u32 bd_id = ntohl (mp->bd_id);
-  u32 bd_index;
-  u32 static_mac;
-  u32 filter_mac;
-  u32 bvi_mac;
-  uword *p;
-
-  mac = mp->mac;
+  uword *p = hash_get (bdm->bd_index_by_bd_id, bd_id);
 
-  p = hash_get (bdm->bd_index_by_bd_id, bd_id);
   if (!p)
     {
       rv = VNET_API_ERROR_NO_SUCH_ENTRY;
       goto bad_sw_if_index;
     }
-  bd_index = p[0];
+  u32 bd_index = p[0];
 
+  u64 mac = mp->mac;
   if (mp->is_add)
     {
-      filter_mac = mp->filter_mac ? 1 : 0;
-      if (filter_mac == 0)
+      if (mp->filter_mac)
+	l2fib_add_filter_entry (mac, bd_index);
+      else
 	{
+	  u32 sw_if_index = ntohl (mp->sw_if_index);
 	  VALIDATE_SW_IF_INDEX (mp);
 	  if (vec_len (l2im->configs) <= sw_if_index)
 	    {
@@ -227,11 +221,11 @@ vl_api_l2fib_add_del_t_handler (vl_api_l2fib_add_del_t * mp)
 		  goto bad_sw_if_index;
 		}
 	    }
+	  u32 static_mac = mp->static_mac ? 1 : 0;
+	  u32 bvi_mac = mp->bvi_mac ? 1 : 0;
+	  l2fib_add_fwd_entry (mac, bd_index, sw_if_index, static_mac,
+			       bvi_mac);
 	}
-      static_mac = mp->static_mac ? 1 : 0;
-      bvi_mac = mp->bvi_mac ? 1 : 0;
-      l2fib_add_entry (mac, bd_index, sw_if_index, static_mac, filter_mac,
-		       bvi_mac);
     }
   else
     {
diff --git a/src/vnet/l2/l2_fib.c b/src/vnet/l2/l2_fib.c
index 2bb6d105335..6f8f6e06330 100644
--- a/src/vnet/l2/l2_fib.c
+++ b/src/vnet/l2/l2_fib.c
@@ -413,8 +413,10 @@ l2fib_add (vlib_main_t * vm,
 	}
     }
 
-  l2fib_add_entry (mac, bd_index, sw_if_index, static_mac, filter_mac,
-		   bvi_mac);
+  if (filter_mac)
+    l2fib_add_filter_entry (mac, bd_index);
+  else
+    l2fib_add_fwd_entry (mac, bd_index, sw_if_index, static_mac, bvi_mac);
 
 done:
   return error;
@@ -464,7 +466,6 @@ l2fib_test_command_fn (vlib_main_t * vm,
   u64 mac, save_mac;
   u32 bd_index = 0;
   u32 sw_if_index = 8;
-  u32 filter_mac = 0;
   u32 bvi_mac = 0;
   u32 is_add = 0;
   u32 is_del = 0;
@@ -503,8 +504,7 @@ l2fib_test_command_fn (vlib_main_t * vm,
       for (i = 0; i < count; i++)
 	{
 	  u64 tmp;
-	  l2fib_add_entry (mac, bd_index, sw_if_index, mac,
-			   filter_mac, bvi_mac);
+	  l2fib_add_fwd_entry (mac, bd_index, sw_if_index, mac, bvi_mac);
 	  tmp = clib_net_to_host_u64 (mac);
 	  tmp >>= 16;
 	  tmp++;
diff --git a/src/vnet/l2/l2_fib.h b/src/vnet/l2/l2_fib.h
index 031845029ac..21dcc4513e0 100644
--- a/src/vnet/l2/l2_fib.h
+++ b/src/vnet/l2/l2_fib.h
@@ -350,6 +350,19 @@ l2fib_add_entry (u64 mac,
 		 u32 bd_index,
 		 u32 sw_if_index, u32 static_mac, u32 drop_mac, u32 bvi_mac);
 
+static inline void
+l2fib_add_fwd_entry (u64 mac, u32 bd_index, u32 sw_if_index, u32 static_mac,
+		     u32 bvi_mac)
+{
+  l2fib_add_entry (mac, bd_index, sw_if_index, static_mac, 0, bvi_mac);
+}
+
+static inline void
+l2fib_add_filter_entry (u64 mac, u32 bd_index)
+{
+  l2fib_add_entry (mac, bd_index, ~0, 1, 1, 0);
+}
+
 u32 l2fib_del_entry (u64 mac, u32 bd_index);
 
 void l2fib_start_ager_scan (vlib_main_t * vm);
diff --git a/src/vnet/l2/l2_input.c b/src/vnet/l2/l2_input.c
index 22fc2a9894f..d536d15b8de 100644
--- a/src/vnet/l2/l2_input.c
+++ b/src/vnet/l2/l2_input.c
@@ -671,7 +671,7 @@ set_int_l2_mode (vlib_main_t * vm, vnet_main_t * vnet_main,	/*           */
 
 	      /* create the l2fib entry for the bvi interface */
 	      mac = *((u64 *) hi->hw_address);
-	      l2fib_add_entry (mac, bd_index, sw_if_index, 1, 0, 1);	/* static + bvi */
+	      l2fib_add_fwd_entry (mac, bd_index, sw_if_index, 1, 1);	/* static + bvi */
 
 	      /* Disable learning by default. no use since l2fib entry is static. */
 	      config->feature_bitmap &= ~L2INPUT_FEAT_LEARN;
diff --git a/src/vnet/l2/l2_learn.c b/src/vnet/l2/l2_learn.c
index 3ff2e704a6e..b9904d3edf5 100644
--- a/src/vnet/l2/l2_learn.c
+++ b/src/vnet/l2/l2_learn.c
@@ -131,27 +131,22 @@ l2learn_process (vlib_node_runtime_t * node,
 					    feature_bitmap);
 
   /* Check mac table lookup result */
-
   if (PREDICT_TRUE (result0->fields.sw_if_index == sw_if_index0))
     {
       /*
        * The entry was in the table, and the sw_if_index matched, the normal case
        */
       counter_base[L2LEARN_ERROR_HIT] += 1;
-      if (!result0->fields.static_mac)
-	{
-	  if (PREDICT_FALSE (result0->fields.timestamp != timestamp))
-	    result0->fields.timestamp = timestamp;
-	  if (PREDICT_FALSE
-	      (result0->fields.sn.as_u16 != vnet_buffer (b0)->l2.l2fib_sn))
-	    result0->fields.sn.as_u16 = vnet_buffer (b0)->l2.l2fib_sn;
-	}
+      int update = !result0->fields.static_mac &&
+	(result0->fields.timestamp != timestamp ||
+	 result0->fields.sn.as_u16 != vnet_buffer (b0)->l2.l2fib_sn);
+
+      if (PREDICT_TRUE (!update))
+	return;
     }
   else if (result0->raw == ~0)
     {
-
       /* The entry was not in table, so add it  */
-
       counter_base[L2LEARN_ERROR_MISS] += 1;
 
       if (msm->global_learn_count == msm->global_learn_limit)
@@ -161,32 +156,27 @@ l2learn_process (vlib_node_runtime_t * node,
 	   * In the future, limits could also be per-interface or bridge-domain.
 	   */
 	  counter_base[L2LEARN_ERROR_LIMIT] += 1;
-	  goto done;
-
-	}
-      else
-	{
-	  BVT (clib_bihash_kv) kv;
-	  /* It is ok to learn */
-
-	  result0->raw = 0;	/* clear all fields */
-	  result0->fields.sw_if_index = sw_if_index0;
-	  result0->fields.timestamp = timestamp;
-	  result0->fields.sn.as_u16 = vnet_buffer (b0)->l2.l2fib_sn;
-	  kv.key = key0->raw;
-	  kv.value = result0->raw;
-
-	  BV (clib_bihash_add_del) (msm->mac_table, &kv, 1 /* is_add */ );
-
-	  cached_key->raw = ~0;	/* invalidate the cache */
-	  msm->global_learn_count++;
+	  return;
 	}
 
+      /* It is ok to learn */
+      msm->global_learn_count++;
+      result0->raw = 0;		/* clear all fields */
+      result0->fields.sw_if_index = sw_if_index0;
+      cached_key->raw = ~0;	/* invalidate the cache */
     }
   else
     {
-
       /* The entry was in the table, but with the wrong sw_if_index mapping (mac move) */
+      if (result0->fields.filter)
+	{
+	  ASSERT (result0->fields.sw_if_index == ~0);
+	  /* drop packet because lookup matched a filter mac entry */
+	  b0->error = node->errors[L2LEARN_ERROR_FILTER_DROP];
+	  *next0 = L2LEARN_NEXT_DROP;
+	  return;
+	}
+
       counter_base[L2LEARN_ERROR_MAC_MOVE] += 1;
 
       if (result0->fields.static_mac)
@@ -197,44 +187,24 @@ l2learn_process (vlib_node_runtime_t * node,
 	   */
 	  b0->error = node->errors[L2LEARN_ERROR_MAC_MOVE_VIOLATE];
 	  *next0 = L2LEARN_NEXT_DROP;
+	  return;
 	}
-      else
-	{
-	  /*
-	   * Update the entry
-	   * TODO: may want to rate limit mac moves
-	   * TODO: check global/bridge domain/interface learn limits
-	   */
-	  BVT (clib_bihash_kv) kv;
-
-	  result0->raw = 0;	/* clear all fields */
-	  result0->fields.sw_if_index = sw_if_index0;
-	  result0->fields.timestamp = timestamp;
-	  result0->fields.sn.as_u16 = vnet_buffer (b0)->l2.l2fib_sn;
 
-	  kv.key = key0->raw;
-	  kv.value = result0->raw;
-
-	  cached_key->raw = ~0;	/* invalidate the cache */
-
-	  BV (clib_bihash_add_del) (msm->mac_table, &kv, 1 /* is_add */ );
-	}
+      /*
+       * TODO: may want to rate limit mac moves
+       * TODO: check global/bridge domain/interface learn limits
+       */
+      result0->fields.sw_if_index = sw_if_index0;
     }
 
-  if (result0->fields.filter)
-    {
-      /* drop packet because lookup matched a filter mac entry */
+  /* Update the entry */
+  result0->fields.timestamp = timestamp;
+  result0->fields.sn.as_u16 = vnet_buffer (b0)->l2.l2fib_sn;
 
-      if (*next0 != L2LEARN_NEXT_DROP)
-	{
-	  /* if we're not already dropping the packet, do it now */
-	  b0->error = node->errors[L2LEARN_ERROR_FILTER_DROP];
-	  *next0 = L2LEARN_NEXT_DROP;
-	}
-    }
-
-done:
-  return;
+  BVT (clib_bihash_kv) kv;
+  kv.key = key0->raw;
+  kv.value = result0->raw;
+  BV (clib_bihash_add_del) (msm->mac_table, &kv, 1 /* is_add */ );
 }