From 5d7294578434b26c80bc01a40266a22c54756c25 Mon Sep 17 00:00:00 2001
From: Leo Chen <39020268+leo0519@users.noreply.github.com>
Date: Wed, 27 Apr 2022 17:28:08 +0800
Subject: [PATCH] Fix the race condition in cumsum operator (#42205)

* Fix the race condition in cumsum operator

* Optimize cumsum operator
---
 paddle/phi/kernels/gpu/cumsum_kernel.cu | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/paddle/phi/kernels/gpu/cumsum_kernel.cu b/paddle/phi/kernels/gpu/cumsum_kernel.cu
index e04f2b5f876..13975ddd3ef 100644
--- a/paddle/phi/kernels/gpu/cumsum_kernel.cu
+++ b/paddle/phi/kernels/gpu/cumsum_kernel.cu
@@ -39,14 +39,12 @@ __device__ void BlockReverse(
   int tx = threadIdx.x;
 
   int offset = tx;
-  int in_index = src_base + offset;
-  if (offset >= valid_item) {
-    sh_mem[offset] = 0;
-  } else {
-    int sh_mem_index = BLOCK_SIZE - offset - 1;
-    T data = idata[in_index];
-    sh_mem[sh_mem_index] = data;
+  T src_data = 0;
+  int src_offset = BLOCK_SIZE - offset - 1;
+  if (src_offset < valid_item) {
+    src_data = idata[src_base + src_offset];
   }
+  sh_mem[offset] = src_data;
 
   __syncthreads();
   int out_index = dst_base - offset;
-- 
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