Fixing Race Condition Using For Loop code in operating system?

Fixing Race Condition Using For Loop
 

#include <pthread.h>
#include <semaphore.h>
#include <stdio.h>

int val = 100;
const int max = 1000000;
pthread_mutex_t m1;

void *tentry_fun1(void *pv) {
  int i;
  printf("A--welcome\n");
  for (i = 1; i <= max; i++) {
    pthread_mutex_lock(&m1);
    val++;
    pthread_mutex_unlock(&m1);        
  }
  // pthread_exit(NULL);
}
void *tentry_fun2(void *pv) {
  int i;
  printf("B--welcome\n");
  for (i = 1; i <= max; i++) {
   pthread_mutex_lock(&m1);
   val--;
   pthread_mutex_unlock(&m1); 
  }
  // pthread_exit(NULL);
}
int main() {
  pthread_t pt1, pt2; // thread handle
  pthread_mutex_init(&m1);
  pthread_create(&pt1, NULL, tentry_fun1, NULL);
  pthread_create(&pt2, NULL, tentry_fun2, NULL);
  pthread_join(pt1, NULL);
  pthread_join(pt2, NULL);
  pthread_mutex_destroy(&m1);
  printf("main--final value=%d\n", val);
  return 0; // exit(0);
}