뮤텍스 예제에서 질문이여

#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
 
struct account{
        int balance;
        pthread_mutex_t mutex;
};
 
void *disburse_money(int amout)
{
}
 
 
int withdraw(struct account *account, int amount)
{
 
        pthread_mutex_lock(&(account->mutex));
        const int balance = account->balance;
        if(balance < amount){
                pthread_mutex_unlock(&account->mutex);
                return -1;
        }
 
        account->balance = balance - amount;
        pthread_mutex_unlock(&(account->mutex));
 
        printf("%d\n", account->balance);
        disburse_money(amount);
 
        return 0;
}
 
int main()
{
        struct account abcd;
        abcd.balance = 10000;
        abcd.mutex = PTHREAD_MUTEX_INITIALIZER;
 
        withdraw(&abcd, 5000);
        return 0;
}