Function bt_save

freebsd/kern/subr_vmem.c:374–380

* Hide MAXALLOC tags before dropping the arena lock to ensure that a * concurrent allocation attempt does not grab them. */

 * concurrent allocation attempt does not grab them.
 */
static void
bt_save(vmem_t *vm)
{
	KASSERT(vm->vm_nfreetags >= BT_MAXALLOC,
	    ("%s: insufficient free tags %d", __func__, vm->vm_nfreetags));
	vm->vm_nfreetags -= BT_MAXALLOC;
}

static void
bt_restore(vmem_t *vm)