// SPDX-License-Identifier: GPL-2.0 #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; }