Function vmem_add1

freebsd/kern/subr_vmem.c:827–874

SYSINIT(vfs, SI_SUB_CONFIGURE, SI_ORDER_ANY, vmem_start_callout, NULL);

static void
vmem_add1(vmem_t *vm, vmem_addr_t addr, vmem_size_t size, int type)
{
	bt_t *btfree, *btprev, *btspan;

	VMEM_ASSERT_LOCKED(vm);
	MPASS(type == BT_TYPE_SPAN || type == BT_TYPE_SPAN_STATIC);
	MPASS((size & vm->vm_quantum_mask) == 0);

	if (vm->vm_releasefn == NULL) {
		/*
		 * The new segment will never be released, so see if it is
		 * contiguous with respect to an existing segment.  In this case
		 * a span tag is not needed, and it may be possible now or in
		 * the future to coalesce the new segment with an existing free
		 * segment.
		 */
		btprev = TAILQ_LAST(&vm->vm_seglist, vmem_seglist);
		if ((!bt_isbusy(btprev) && !bt_isfree(btprev)) ||
		    btprev->bt_start + btprev->bt_size != addr)
			btprev = NULL;
	} else {
		btprev = NULL;
	}

	if (btprev == NULL || bt_isbusy(btprev)) {
		if (btprev == NULL) {
			btspan = bt_alloc(vm);
			btspan->bt_type = type;
			btspan->bt_start = addr;
			btspan->bt_size = size;
			bt_insseg_tail(vm, btspan);
		}

		btfree = bt_alloc(vm);
		btfree->bt_type = BT_TYPE_FREE;
		btfree->bt_start = addr;
		btfree->bt_size = size;
		bt_insseg_tail(vm, btfree);
		bt_insfree(vm, btfree);
	} else {
		bt_remfree(vm, btprev);
		btprev->bt_size += size;
		bt_insfree(vm, btprev);
	}

	vm->vm_size += size;
}

static void
vmem_destroy1(vmem_t *vm)