thread race condition

race.c

#include <semaphore.h>
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/mman.h>

#define MAX_SIZE 32
typedef enum {false, true} bool;

//gcc -o main main.c -lpthread

volatile int cnt = 0; /* global */ 
sem_t empty, mutex, full;

void *fun_thread1(void *tmp);


void *fun_thread2(void *tmp);

int main(int argc, char **argv)
{
   int tmp = 0;

   /* 세마포어를 생성화고 초기화 한다. */
   if( sem_init(&mutex, 0, 1) < 0) {
      perror("mutex: semaphore initilization");
      exit(0);
    }

   if( sem_init(&full, 0, 0) < 0 ){
      perror("full: semaphore initilization");
      exit(0);
   }    

   if( sem_init(&empty, 0, MAX_SIZE) < 0 ){
      perror("full: semaphore initilization");
      exit(0);
   }


   pthread_t tid_1, tid_2;

   pthread_create(&tid_1, NULL, fun_thread1, &tmp);
   pthread_create(&tid_2, NULL, fun_thread2, &tmp);
   pthread_join( tid_1, NULL);
   pthread_join( tid_2, NULL);

   printf("=======%d\n", cnt);

   return 0;
}

void *fun_thread1(void *tmp){
  int i;
   for(i=0; i<10000000; i++){
      sem_wait(&mutex);
      cnt++;
      sem_post(&mutex);
   }
}

void *fun_thread2(void *tmp){
   int i;

   for(i=0; i<10000000; i++){
      sem_wait(&mutex);
      cnt++;
      sem_post(&mutex);
   }
}