Use LINKER_INITIALIZED for mutexes with static storage class.

This was causing exit-time races as some threads were accessing the
mutex as it was being destructed.

			---------------

It is illegal to use any static type with a constructor/destructor with static
storage class in a multithreaded C++ programme that can exit(), even if the
constructor is protected by C++11's function-scope static initialization rules,
because exit-time destruction is unsafe in the presence of multiple threads.

For things that are not function-scope, the construction is also unsafe,
because global contruction ordering is undefined in general.

The LINKER_INITIALIZED variant constructor for TensorFlow's mutex avoids these
problems, at the cost of relying on the linker to zero-initialize the BSS
region.

PiperOrigin-RevId: 176612772

1 files changed, 1 insertions, 1 deletions

diff --git a/tensorflow/contrib/ffmpeg/default/ffmpeg_lib_test.cc b/tensorflow/contrib/ffmpeg/default/ffmpeg_lib_test.cc
index 2871c14628..85b61b2616 100644
--- a/tensorflow/contrib/ffmpeg/default/ffmpeg_lib_test.cc
+++ b/tensorflow/contrib/ffmpeg/default/ffmpeg_lib_test.cc
@@ -39,7 +39,7 @@ const char kTestMp3Filename[] =
 
 // Set to true via a command line flag iff the test is expected to have FFmpeg
 // installed.
-mutex mu;
+mutex mu(LINKER_INITIALIZED);
 bool should_ffmpeg_be_installed GUARDED_BY(mu) = false;
 
 string ParseTestFlags(int* argc, char** argv) {