commit 04e148570dbb420409ce9212f2e8c03e675bea48
author Nicolas Capens <capn@google.com> Tue Aug 27 23:55:01 2019 -0400
committer Nicolas Capens <nicolascapens@google.com> Wed Aug 28 04:55:13 2019 +0000
tree 8c9990a7704fa9f4635cf29267f55f22d7fd1ee7
parent cde4dd9601ce8ee950b2b3a153d04aa1b0940d9b

Make round-robin task enqueue index thread safe

Addresses TSAN error in Chromium viz_unittests and cc_unittests.

Bug: b/139010488
Change-Id: I1a53487c4787170c38898cca47bf76145ebdf6bd
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/35608
Presubmit-Ready: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>

src/Yarn/Scheduler.cpp

diff --git a/src/Yarn/Scheduler.cpp b/src/Yarn/Scheduler.cpp
index 25b432e..827aa90 100644
--- a/src/Yarn/Scheduler.cpp
+++ b/src/Yarn/Scheduler.cpp
@@ -99,6 +99,7 @@
 }
 
 Scheduler::Scheduler()
+    : nextEnqueueIndex(0)
 {
     for (size_t i = 0; i < spinningWorkers.size(); i++)
     {

src/Yarn/Scheduler.hpp

diff --git a/src/Yarn/Scheduler.hpp b/src/Yarn/Scheduler.hpp
index 9649e02..992dade 100644
--- a/src/Yarn/Scheduler.hpp
+++ b/src/Yarn/Scheduler.hpp
@@ -294,7 +294,7 @@
 
     // TODO: Make this lot thread-safe so setWorkerThreadCount() can be called
     // during execution of tasks.
-    unsigned int nextEnqueueIndex = 0;
+    std::atomic<unsigned int> nextEnqueueIndex;
     unsigned int numWorkerThreads = 0;
     std::array<Worker*, MaxWorkerThreads> workerThreads;