The DRD manual contains this section on C++11 threads support.

If you want to use the c++11 class std::thread you will need to do the following to annotate the std::shared_ptr<> objects used in the implementation of that class:

• Add the following code at the start of a common header or at the start of each source file, before any C++ header files are included:

    #include <valgrind/drd.h>
    #define _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(addr)
    ANNOTATE_HAPPENS_BEFORE(addr)
    #define _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(addr)
    ANNOTATE_HAPPENS_AFTER(addr)

• Download the GCC source code and from the source file libstdc++-v3/src/c++11/thread.cc, copy the implementation of the execute_native_thread_routine() and std::thread::_M_start_thread() functions into a source file that is linked with your application. Make sure that also in this source file the _GLIBCXX_SYNCHRONIZATION_HAPPENS_*() macros are defined properly.

One might see a lot of false positives when using DRD with an application that uses the C++11 threads API, which would be fixed by the preceding fix.

However, when using GCC 5.4 and Valgrind 3.11 (possibly, using older versions too) this issue does not seem to be present any more. It is, however, something to keep in mind when one suddenly sees a lot of false positives in one's DRD output while using the C++11 threads API.