Does the POSIX standard allow a named shared memory block to contain a mutex and condition variable?

We've been trying to use a mutex and condition variable to synchronise access to named shared memory by two processes on a LynuxWorks LynxOS-SE system (POSIX-conformant).

One shared memory block is called "/sync" and contains the mutex and condition variable, the other is "/data" and contains the actual data we are syncing access to.

We're seeing failures from pthread_cond_signal() if both processes don't perform the mmap() calls in exactly the same order, or if one process mmaps in some other piece of shared memory before it mmaps the "/sync" memory.

This example code is about as short as I can make it:

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <sys/file.h>
#include <stdlib.h>
#include <pthread.h>
#include <errno.h>
#include <iostream>
#include <string>
using namespace std;

static const string shm_name_sync("/sync");
static const string shm_name_data("/data");

struct shared_memory_sync
{
  pthread_mutex_t mutex;
  pthread_cond_t condition;
};

struct shared_memory_data
{
  int a;
  int b;
};


//Create 2 shared memory objects
// - sync contains 2 shared synchronisation objects (mutex and condition)
// - data not important 
void create()
{
  // Create and map 'sync' shared memory
  int fd_sync = shm_open(shm_name_sync.c_str(), O_CREAT|O_RDWR, S_IRUSR|S_IWUSR);
  ftruncate(fd_sync, sizeof(shared_memory_sync));
  void* addr_sync = mmap(0, sizeof(shared_memory_sync), PROT_READ|PROT_WRITE, MAP_SHARED, fd_sync, 0);
  shared_memory_sync* p_sync = static_cast<shared
unix ipc posix shared-memory lynxos
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