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#include <stdio.h>
#include <pthread.h>
pthread_mutex_t a = PTHREAD_MUTEX_INITIALIZER;
pthread_mutex_t b = PTHREAD_MUTEX_INITIALIZER;
pthread_barrier_t bar;
void *ba_lock(void *arg)
{
int ret, i;
pthread_mutex_lock(&b);
if (pthread_barrier_wait(&bar) == PTHREAD_BARRIER_SERIAL_THREAD)
pthread_barrier_destroy(&bar);
pthread_mutex_lock(&a);
pthread_mutex_unlock(&a);
pthread_mutex_unlock(&b);
}
int main(void)
{
pthread_t t;
pthread_barrier_init(&bar, NULL, 2);
if (pthread_create(&t, NULL, ba_lock, NULL)) {
fprintf(stderr, "pthread_create() failed\n");
return 1;
}
pthread_mutex_lock(&a);
if (pthread_barrier_wait(&bar) == PTHREAD_BARRIER_SERIAL_THREAD)
pthread_barrier_destroy(&bar);
pthread_mutex_lock(&b);
pthread_mutex_unlock(&b);
pthread_mutex_unlock(&a);
pthread_join(t, NULL);
return 0;
}
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