第三种情况

#include<stdio.h>
#include<unistd.h>
#include<pthread.h>
#include<string.h>

pthread_mutex_t mutex1, mutex2;
void * workA(void * arg) {
    pthread_mutex_lock(&mutex1);
    sleep(1);
    pthread_mutex_lock(&mutex2);

    printf("workA......\n");

    pthread_mutex_unlock(&mutex2);
    pthread_mutex_unlock(&mutex1);

    return NULL;
}

void * workB(void * arg) {
    pthread_mutex_lock(&mutex2);
    sleep(1);
    pthread_mutex_lock(&mutex1);

    printf("workB......\n");

    pthread_mutex_unlock(&mutex1);
    pthread_mutex_unlock(&mutex2);
    
    return NULL;
}


int main() {
    pthread_mutex_init(&mutex1, NULL);
    pthread_mutex_init(&mutex2, NULL);

    pthread_t tid1, tid2;
    pthread_create(&tid1, NULL, workA, NULL);
    pthread_create(&tid2, NULL, workB, NULL);

    pthread_join(tid1, NULL);
    pthread_join(tid2, NULL); 

    pthread_mutex_destroy(&mutex1);
    pthread_mutex_destroy(&mutex2);


    return 0;
}