fib: add barrier sync, pool/vector expand cases

load_balance_alloc_i(...) is not thread safe when the
load_balance_pool or combined counter vectors expand.

Type: fix

Signed-off-by: Dave Barach <dave@barachs.net>
Change-Id: I7f295ed77350d1df0434d5ff461eedafe79131de
(cherry picked from commit 8341f76fd1cd4351961cd8161cfed2814fc55103)

3 files changed, 66 insertions, 1 deletions

diff --git a/src/vlib/counter.c b/src/vlib/counter.c
index 558bbe0e990..c134229b751 100644
--- a/src/vlib/counter.c
+++ b/src/vlib/counter.c
@@ -119,6 +119,44 @@ vlib_validate_combined_counter (vlib_combined_counter_main_t * cm, u32 index)
 		       3 /*STAT_DIR_TYPE_COUNTER_VECTOR_COMBINED */ );
 }
 
+int
+  vlib_validate_combined_counter_will_expand
+  (vlib_combined_counter_main_t * cm, u32 index)
+{
+  vlib_thread_main_t *tm = vlib_get_thread_main ();
+  int i;
+  void *oldheap = vlib_stats_push_heap (cm->counters);
+
+  /* Possibly once in recorded history */
+  if (PREDICT_FALSE (vec_len (cm->counters) == 0))
+    {
+      vlib_stats_pop_heap (cm, oldheap, index,
+			   3 /*STAT_DIR_TYPE_COUNTER_VECTOR_COMBINED */ );
+      return 1;
+    }
+
+  for (i = 0; i < tm->n_vlib_mains; i++)
+    {
+      /* Trivially OK, and proves that index >= vec_len(...) */
+      if (index < vec_len (cm->counters[i]))
+	continue;
+      if (_vec_resize_will_expand
+	  (cm->counters[i],
+	   index - vec_len (cm->counters[i]) /* length_increment */ ,
+	   sizeof (cm->counters[i]) /* data_bytes */ ,
+	   0 /* header_bytes */ ,
+	   CLIB_CACHE_LINE_BYTES /* data_alignment */ ))
+	{
+	  vlib_stats_pop_heap (cm, oldheap, index,
+			       3 /*STAT_DIR_TYPE_COUNTER_VECTOR_COMBINED */ );
+	  return 1;
+	}
+    }
+  vlib_stats_pop_heap (cm, oldheap, index,
+		       3 /*STAT_DIR_TYPE_COUNTER_VECTOR_COMBINED */ );
+  return 0;
+}
+
 void
 vlib_free_combined_counter (vlib_combined_counter_main_t * cm)
 {
diff --git a/src/vlib/counter.h b/src/vlib/counter.h
index e9978ba25f5..6e8c65ede08 100644
--- a/src/vlib/counter.h
+++ b/src/vlib/counter.h
@@ -314,6 +314,9 @@ void vlib_free_simple_counter (vlib_simple_counter_main_t * cm);
 
 void vlib_validate_combined_counter (vlib_combined_counter_main_t * cm,
 				     u32 index);
+int vlib_validate_combined_counter_will_expand
+  (vlib_combined_counter_main_t * cm, u32 index);
+
 void vlib_free_combined_counter (vlib_combined_counter_main_t * cm);
 
 /** Obtain the number of simple or combined counters allocated.
diff --git a/src/vnet/dpo/load_balance.c b/src/vnet/dpo/load_balance.c
index 7acccca61bf..c029341f147 100644
--- a/src/vnet/dpo/load_balance.c
+++ b/src/vnet/dpo/load_balance.c
@@ -93,12 +93,33 @@ static load_balance_t *
 load_balance_alloc_i (void)
 {
     load_balance_t *lb;
+    u8 need_barrier_sync = 0;
+    vlib_main_t *vm = vlib_get_main();
+    ASSERT (vm->thread_index == 0);
+
+    pool_get_aligned_will_expand (load_balance_pool, need_barrier_sync,
+                                  CLIB_CACHE_LINE_BYTES);
+    if (need_barrier_sync)
+        vlib_worker_thread_barrier_sync (vm);
 
     pool_get_aligned(load_balance_pool, lb, CLIB_CACHE_LINE_BYTES);
     clib_memset(lb, 0, sizeof(*lb));
 
     lb->lb_map = INDEX_INVALID;
     lb->lb_urpf = INDEX_INVALID;
+
+    if (need_barrier_sync == 0)
+    {
+        need_barrier_sync += vlib_validate_combined_counter_will_expand
+            (&(load_balance_main.lbm_to_counters),
+             load_balance_get_index(lb));
+        need_barrier_sync += vlib_validate_combined_counter_will_expand
+            (&(load_balance_main.lbm_via_counters),
+             load_balance_get_index(lb));
+        if (need_barrier_sync)
+            vlib_worker_thread_barrier_sync (vm);
+    }
+
     vlib_validate_combined_counter(&(load_balance_main.lbm_to_counters),
                                    load_balance_get_index(lb));
     vlib_validate_combined_counter(&(load_balance_main.lbm_via_counters),
@@ -108,6 +129,9 @@ load_balance_alloc_i (void)
     vlib_zero_combined_counter(&(load_balance_main.lbm_via_counters),
                                load_balance_get_index(lb));
 
+    if (need_barrier_sync)
+        vlib_worker_thread_barrier_release (vm);
+
     return (lb);
 }
 
@@ -1121,7 +1145,7 @@ load_balance_inline (vlib_main_t * vm,
 	      vnet_buffer(b0)->ip.flow_hash = bier_compute_flow_hash(bh0);
 	  }
 
-	  dpo0 = load_balance_get_bucket_i(lb0, 
+	  dpo0 = load_balance_get_bucket_i(lb0,
 					   vnet_buffer(b0)->ip.flow_hash &
 					   (lb0->lb_n_buckets_minus_1));