atomic_limit_counter.cpp

int add_count(unsigned long delta)
{
	int c;
	int cm;
	int old;
	int new;

	do {
		split_counterandmax(&counterandmax, &old, &c, &cm);
		if (delta > MAX_COUNTERMAX || c + delta > cm)
			goto slowpath;
		new = merge_counterandmax(c + delta, cm);
	} while (atomic_cmpxchg(&counterandmax, old, new) != old);
	return 1;
slowpath:
	spin_lock(&gblcnt_mutex);
	globalize_count();
	if (globalcountmax - globalcount - globalreserve < delta) {
		flush_local_count();
		if (globalcountmax - globalcount - globalreserve < delta) {
			spin_unlock(&gblcnt_mutex);
			return 0;
		}
	}
	globalcount += delta;
	balance_count();
	spin_unlock(&gblcnt_mutex);
	return 1;
}