Function vm_page_busy_downgrade

freebsd/vm/vm_page.c:912–927

* vm_page_busy_downgrade: * * Downgrade an exclusive busy page into a single shared busy page. */

 *	Downgrade an exclusive busy page into a single shared busy page.
 */
void
vm_page_busy_downgrade(vm_page_t m)
{
	u_int x;

	vm_page_assert_xbusied(m);

	x = vm_page_busy_fetch(m);
	for (;;) {
		if (atomic_fcmpset_rel_int(&m->busy_lock,
		    &x, VPB_SHARERS_WORD(1)))
			break;
	}
	if ((x & VPB_BIT_WAITERS) != 0)
		wakeup(m);
}

/*
 *