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

int testvar;
int done;

#define barrier() __asm__ __volatile__("" ::: "memory")
void *thread_start(void *arg)
{
	while (!done) {
		if (testvar == 1)
			testvar = 0;
		barrier();
	}
	return arg;
}

int main(void)
{
	pthread_t thr;
	int ret;

	ret = pthread_create(&thr, NULL, thread_start, NULL);
	if (ret != 0)
		fprintf(stderr, "pthread_create: error %d\n", ret);

	while (!done) {
		if (testvar == 0)
			testvar = 1;
		barrier();
	}
	return 0;
}