std::shared_mutex recursive protection by thread_local storage

Question

The idea is to use the std::shared_mutex all right, but protect deadlocks in case that std::shared_mutex::lock() for exclusive access is called by the same thread.

For example:

std::shared_mutex m;
void f2()
{
  m.lock();
}
void f1()
{
   m.lock();
   f2();
}

f1() would lock because std::shared_mutex cannot be called recursively. For this I have two options: Either to use my own tlock of read-write mutex which uses Windows Mutex which supports recursive locking, or to use this sort of a locking function based on a thread_local variable:

thread_local bool LockedStuff = 0;
void Lock(std::function<...> f)
{
    if (LockedStuff)
        {
         f(...);
         return;
        }
    LockedStuff = 1;
    m.lock();
    f(...);
    m.unlock();
    LockedLinks = 0;
}

The question is, is there anything I'm missing that can go wrong with the above implementation? Thanks a lot.

Answer 1

That you don't RAII your mutex and thread local variable. If exception is called inside the function your mutex will be forever locked.