c++ - What is the race condition in this code? -

the following implementation of sleepconditionvariablecs, wakeallconditionvariable, , thread creation functions. problem when try create thread creating thread gets stuck on waitforsingleobject( cv->mut, infinite ); in sleepconditionvariablecs. cant figure out race condition here is.

 typedef struct {   int waiters_count;   handle sema_;   handle mut; } condition_variable;  void sleepconditionvariablecs(condition_variable *cv, critical_section *cs, int32_t dwmilliseconds){     waitforsingleobject( cv->mut, infinite ); //acuire object lock      cv->waiters_count++;     leavecriticalsection (cs);     if (signalobjectandwait(cv->mut, cv->sema_, dwmilliseconds, false) == wait_timeout){ //signalobjectandwait releases lock         cv->waiters_count--;     }     entercriticalsection(cs); }  void wakeallconditionvariable(condition_variable *cv){     waitforsingleobject( cv->mut, infinite );      while (cv->waiters_count > 0){         cv->waiters_count = cv->waiters_count - 1;         releasesemaphore (cv->sema_, 1, 0);     }     releasemutex(cv->mut); }  void kernelthread_creationwait(void *kthread){     kernelthread *thread =  (kernelthread *) kthread;      entercriticalsection(thread->lock);     thread->state = thread_created;      wakeallconditionvariable(thread->condition_variable);      leavecriticalsection(thread->lock);     kernelthread_main(kthread); }  kernelthread* createkernelthread(){     eventhandler_gethandler();      unsigned long threadid;     int t;     void *hand;      kernelthread *thread = kernelthread_malloc();     entercriticalsection(thread->lock);     thread->state = thread_waitingforcreation;     hand = createthread(null,             0, // security, stack size             (lpthread_start_routine)&kernelthread_creationwait, // start             (void *)thread,             0,             &threadid); // param, creation flags, id     if (hand == null){         printf("error: return handle createthread() null\n");         exit(-1);     }     thread->thread = hand;     thread->thread_id = threadid;      sleepconditionvariablecs(thread->condition_variable,thread->lock,infinite);     leavecriticalsection(thread->lock);      return thread; }  void initializeconditionvariable (condition_variable *cv){     cv->waiters_count = 0;     cv->sema_ = createsemaphore (null,       // no security                                 0,          // 0                                 0x7fffffff, // max count                                 null);      // unnamed     cv->mut = createmutex(           null,              // default security attributes           false,             // not owned           null);             // unnamed mutex } 

check out following detailed analysis of gotchas when trying implement pthread-style condition variables using win32 apis. http://www.cs.wustl.edu/~schmidt/win32-cv-1.html. (section 3.4, in particular).

in code see 1 problem @ moment. in sleepconditionvariablecs():

    leavecriticalsection (cs);     if (signalobjectandwait(cv->mut, cv->sema_, dwmilliseconds, false) == wait_timeout){ //signalobjectandwait releases lock         // right here have not acquired cv->mut         cv->waiters_count--; // data race (with cv->waiters_count uses in wakeallconditionvariable()     }