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, 2 insertions, 2 deletions

diff --git a/tensorflow/core/lib/random/random.cc b/tensorflow/core/lib/random/random.cc
index 723c1100f8..82dc829507 100644
--- a/tensorflow/core/lib/random/random.cc
+++ b/tensorflow/core/lib/random/random.cc
@@ -33,14 +33,14 @@ std::mt19937_64 InitRngWithDefaultSeed() { return std::mt19937_64(); }
 
 uint64 New64() {
   static std::mt19937_64* rng = InitRngWithRandomSeed();
-  static mutex mu;
+  static mutex mu(LINKER_INITIALIZED);
   mutex_lock l(mu);
   return (*rng)();
 }
 
 uint64 New64DefaultSeed() {
   static std::mt19937_64 rng = InitRngWithDefaultSeed();
-  static mutex mu;
+  static mutex mu(LINKER_INITIALIZED);
   mutex_lock l(mu);
   return rng();
 }