Function domainset_empty_vm

freebsd/kern/kern_cpuset.c:522–550

* Are any of the domains in the mask empty? If so, silently * remove them and update the domainset accordingly. If only empty * domains are present, we must return failure. */

 * domains are present, we must return failure.
 */
static bool
domainset_empty_vm(struct domainset *domain)
{
	domainset_t empty;
	int i, j;

	DOMAINSET_ZERO(&empty);
	for (i = 0; i < vm_ndomains; i++)
		if (VM_DOMAIN_EMPTY(i))
			DOMAINSET_SET(i, &empty);
	if (DOMAINSET_SUBSET(&empty, &domain->ds_mask))
		return (true);

	/* Remove empty domains from the set and recompute. */
	DOMAINSET_ANDNOT(&domain->ds_mask, &empty);
	domain->ds_cnt = DOMAINSET_COUNT(&domain->ds_mask);
	for (i = j = 0; i < DOMAINSET_FLS(&domain->ds_mask); i++)
		if (DOMAINSET_ISSET(i, &domain->ds_mask))
			domain->ds_order[j++] = i;

	/* Convert a PREFER policy referencing an empty domain to RR. */
	if (domain->ds_policy == DOMAINSET_POLICY_PREFER &&
	    DOMAINSET_ISSET(domain->ds_prefer, &empty)) {
		domain->ds_policy = DOMAINSET_POLICY_ROUNDROBIN;
		domain->ds_prefer = -1;
	}

	return (false);
}

/*
 * Create or lookup a domainset based on the key held in 'domain'.