From 212d978a2d20c943724d0eb672aea9f7c4c222ba Mon Sep 17 00:00:00 2001
From: Alexandre Passos <apassos@google.com>
Date: Tue, 21 Aug 2018 10:13:15 -0700
Subject: [PATCH] Do not increment the refcount of the tensorbuffer for
 ResourceStridedSliceAssign.

This will trigger a copy if there are concurrent writes to the variable.

PiperOrigin-RevId: 209615011
---
 tensorflow/core/kernels/strided_slice_op.cc | 38 +++++++++++----------
 1 file changed, 20 insertions(+), 18 deletions(-)

diff --git a/tensorflow/core/kernels/strided_slice_op.cc b/tensorflow/core/kernels/strided_slice_op.cc
index 59fdc2262ab..7b537fef5be 100644
--- a/tensorflow/core/kernels/strided_slice_op.cc
+++ b/tensorflow/core/kernels/strided_slice_op.cc
@@ -300,7 +300,8 @@ class StridedSliceAssignOp : public OpKernel {
     gtl::InlinedVector<int64, 4> end;
     gtl::InlinedVector<int64, 4> strides;
 
-    Tensor old_lhs;
+    Tensor* old_lhs = nullptr;
+    Tensor tmp;
     if (context->input_dtype(0) == DT_RESOURCE) {
       Var* v;
       OP_REQUIRES_OK(context,
@@ -308,29 +309,30 @@ class StridedSliceAssignOp : public OpKernel {
       mutex_lock ml(*v->mu());
       OP_REQUIRES_OK(context,
                      PrepareToUpdateVariable<Device, T>(context, v->tensor()));
-      old_lhs = *v->tensor();
-      OP_REQUIRES(context, old_lhs.dtype() == DataTypeToEnum<T>::value,
+      old_lhs = v->tensor();
+      OP_REQUIRES(context, old_lhs->dtype() == DataTypeToEnum<T>::value,
                   errors::InvalidArgument(
-                      "l-value dtype ", DataTypeString(old_lhs.dtype()),
+                      "l-value dtype ", DataTypeString(old_lhs->dtype()),
                       " does not match r-value dtype ",
                       DataTypeString(DataTypeToEnum<T>::value)));
     } else {
       context->forward_ref_input_to_ref_output(0, 0);
-      old_lhs = context->mutable_input(0, true);
+      tmp = context->mutable_input(0, true);
+      old_lhs = &tmp;
     }
 
     OP_REQUIRES_OK(
-        context,
-        ValidateStridedSliceOp(
-            &context->input(1), &context->input(2), context->input(3),
-            old_lhs.shape(), begin_mask, end_mask, ellipsis_mask, new_axis_mask,
-            shrink_axis_mask, &processing_shape, &final_shape, &is_identity,
-            &is_simple_slice, &slice_dim0, &begin, &end, &strides));
+        context, ValidateStridedSliceOp(
+                     &context->input(1), &context->input(2), context->input(3),
+                     old_lhs->shape(), begin_mask, end_mask, ellipsis_mask,
+                     new_axis_mask, shrink_axis_mask, &processing_shape,
+                     &final_shape, &is_identity, &is_simple_slice, &slice_dim0,
+                     &begin, &end, &strides));
 
     if (processing_shape.num_elements()) {
       const Tensor& input = context->input(4);
       TensorShape input_shape = input.shape();
-      TensorShape original_shape = old_lhs.shape();
+      TensorShape original_shape = old_lhs->shape();
       // TODO(aselle): This check is too strong, we only should need
       // input_shape to be broadcastable to final_shape
       OP_REQUIRES(
@@ -345,12 +347,12 @@ class StridedSliceAssignOp : public OpKernel {
       // scalar shape
 
 // Handle general dimensions
-#define HANDLE_DIM(NDIM)                                                 \
-  if (processing_dims == NDIM) {                                         \
-    HandleStridedSliceAssignCase<Device, T, NDIM>()(                     \
-        context, begin, end, strides, processing_shape, is_simple_slice, \
-        &old_lhs);                                                       \
-    return;                                                              \
+#define HANDLE_DIM(NDIM)                                                       \
+  if (processing_dims == NDIM) {                                               \
+    HandleStridedSliceAssignCase<Device, T, NDIM>()(context, begin, end,       \
+                                                    strides, processing_shape, \
+                                                    is_simple_slice, old_lhs); \
+    return;                                                                    \
   }
       HANDLE_DIM(0);
       HANDLE_DIM(1);