thread safety of the mutex ctor

I hope this isn't a stupid question, but.... Is the boost mutex constructor thread-safe? I am writing a singleton template and trying to avoid the static initialisation/destruction order fiasco. I envisage two threads accessing a function like this concurrently: template<typename T> boost::shared_ptr<T> my_func() { static boost::mutex m; boost::mutex::scoped_lock l(m); static boost::shared_ptr<T> p(new T); return p; } and my worry is that both threads could attempt to do the static initialisation of m concurrently. Is there protection against this? Is it even possible to protect against this? I've tried to use boost::call_once, which would give sufficient guarantees but it's quite inflexible as nothing can be passed to or from the function being called. I know that integral types (like a pthread_t) of static storage are initialised before main() and before constructors of statically allocated objects are called, which means there would be no problem using a pthread_t above. However, constructors of objects of static storage are called at a time when there could be multiple threads running. Am I worrying about nothing? Or is there a problem here? Thanks, James -- James E Taylor ___________________________________ NOCC, http://nocc.sourceforge.net