xref: /freebsd/sys/contrib/dev/acpica/components/namespace/nsalloc.c (revision 722b16673c40aedf280895f2f2f676bb494518d7)
1 /*******************************************************************************
2  *
3  * Module Name: nsalloc - Namespace allocation and deletion utilities
4  *
5  ******************************************************************************/
6 
7 /******************************************************************************
8  *
9  * 1. Copyright Notice
10  *
11  * Some or all of this work - Copyright (c) 1999 - 2023, Intel Corp.
12  * All rights reserved.
13  *
14  * 2. License
15  *
16  * 2.1. This is your license from Intel Corp. under its intellectual property
17  * rights. You may have additional license terms from the party that provided
18  * you this software, covering your right to use that party's intellectual
19  * property rights.
20  *
21  * 2.2. Intel grants, free of charge, to any person ("Licensee") obtaining a
22  * copy of the source code appearing in this file ("Covered Code") an
23  * irrevocable, perpetual, worldwide license under Intel's copyrights in the
24  * base code distributed originally by Intel ("Original Intel Code") to copy,
25  * make derivatives, distribute, use and display any portion of the Covered
26  * Code in any form, with the right to sublicense such rights; and
27  *
28  * 2.3. Intel grants Licensee a non-exclusive and non-transferable patent
29  * license (with the right to sublicense), under only those claims of Intel
30  * patents that are infringed by the Original Intel Code, to make, use, sell,
31  * offer to sell, and import the Covered Code and derivative works thereof
32  * solely to the minimum extent necessary to exercise the above copyright
33  * license, and in no event shall the patent license extend to any additions
34  * to or modifications of the Original Intel Code. No other license or right
35  * is granted directly or by implication, estoppel or otherwise;
36  *
37  * The above copyright and patent license is granted only if the following
38  * conditions are met:
39  *
40  * 3. Conditions
41  *
42  * 3.1. Redistribution of Source with Rights to Further Distribute Source.
43  * Redistribution of source code of any substantial portion of the Covered
44  * Code or modification with rights to further distribute source must include
45  * the above Copyright Notice, the above License, this list of Conditions,
46  * and the following Disclaimer and Export Compliance provision. In addition,
47  * Licensee must cause all Covered Code to which Licensee contributes to
48  * contain a file documenting the changes Licensee made to create that Covered
49  * Code and the date of any change. Licensee must include in that file the
50  * documentation of any changes made by any predecessor Licensee. Licensee
51  * must include a prominent statement that the modification is derived,
52  * directly or indirectly, from Original Intel Code.
53  *
54  * 3.2. Redistribution of Source with no Rights to Further Distribute Source.
55  * Redistribution of source code of any substantial portion of the Covered
56  * Code or modification without rights to further distribute source must
57  * include the following Disclaimer and Export Compliance provision in the
58  * documentation and/or other materials provided with distribution. In
59  * addition, Licensee may not authorize further sublicense of source of any
60  * portion of the Covered Code, and must include terms to the effect that the
61  * license from Licensee to its licensee is limited to the intellectual
62  * property embodied in the software Licensee provides to its licensee, and
63  * not to intellectual property embodied in modifications its licensee may
64  * make.
65  *
66  * 3.3. Redistribution of Executable. Redistribution in executable form of any
67  * substantial portion of the Covered Code or modification must reproduce the
68  * above Copyright Notice, and the following Disclaimer and Export Compliance
69  * provision in the documentation and/or other materials provided with the
70  * distribution.
71  *
72  * 3.4. Intel retains all right, title, and interest in and to the Original
73  * Intel Code.
74  *
75  * 3.5. Neither the name Intel nor any other trademark owned or controlled by
76  * Intel shall be used in advertising or otherwise to promote the sale, use or
77  * other dealings in products derived from or relating to the Covered Code
78  * without prior written authorization from Intel.
79  *
80  * 4. Disclaimer and Export Compliance
81  *
82  * 4.1. INTEL MAKES NO WARRANTY OF ANY KIND REGARDING ANY SOFTWARE PROVIDED
83  * HERE. ANY SOFTWARE ORIGINATING FROM INTEL OR DERIVED FROM INTEL SOFTWARE
84  * IS PROVIDED "AS IS," AND INTEL WILL NOT PROVIDE ANY SUPPORT, ASSISTANCE,
85  * INSTALLATION, TRAINING OR OTHER SERVICES. INTEL WILL NOT PROVIDE ANY
86  * UPDATES, ENHANCEMENTS OR EXTENSIONS. INTEL SPECIFICALLY DISCLAIMS ANY
87  * IMPLIED WARRANTIES OF MERCHANTABILITY, NONINFRINGEMENT AND FITNESS FOR A
88  * PARTICULAR PURPOSE.
89  *
90  * 4.2. IN NO EVENT SHALL INTEL HAVE ANY LIABILITY TO LICENSEE, ITS LICENSEES
91  * OR ANY OTHER THIRD PARTY, FOR ANY LOST PROFITS, LOST DATA, LOSS OF USE OR
92  * COSTS OF PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, OR FOR ANY INDIRECT,
93  * SPECIAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THIS AGREEMENT, UNDER ANY
94  * CAUSE OF ACTION OR THEORY OF LIABILITY, AND IRRESPECTIVE OF WHETHER INTEL
95  * HAS ADVANCE NOTICE OF THE POSSIBILITY OF SUCH DAMAGES. THESE LIMITATIONS
96  * SHALL APPLY NOTWITHSTANDING THE FAILURE OF THE ESSENTIAL PURPOSE OF ANY
97  * LIMITED REMEDY.
98  *
99  * 4.3. Licensee shall not export, either directly or indirectly, any of this
100  * software or system incorporating such software without first obtaining any
101  * required license or other approval from the U. S. Department of Commerce or
102  * any other agency or department of the United States Government. In the
103  * event Licensee exports any such software from the United States or
104  * re-exports any such software from a foreign destination, Licensee shall
105  * ensure that the distribution and export/re-export of the software is in
106  * compliance with all laws, regulations, orders, or other restrictions of the
107  * U.S. Export Administration Regulations. Licensee agrees that neither it nor
108  * any of its subsidiaries will export/re-export any technical data, process,
109  * software, or service, directly or indirectly, to any country for which the
110  * United States government or any agency thereof requires an export license,
111  * other governmental approval, or letter of assurance, without first obtaining
112  * such license, approval or letter.
113  *
114  *****************************************************************************
115  *
116  * Alternatively, you may choose to be licensed under the terms of the
117  * following license:
118  *
119  * Redistribution and use in source and binary forms, with or without
120  * modification, are permitted provided that the following conditions
121  * are met:
122  * 1. Redistributions of source code must retain the above copyright
123  *    notice, this list of conditions, and the following disclaimer,
124  *    without modification.
125  * 2. Redistributions in binary form must reproduce at minimum a disclaimer
126  *    substantially similar to the "NO WARRANTY" disclaimer below
127  *    ("Disclaimer") and any redistribution must be conditioned upon
128  *    including a substantially similar Disclaimer requirement for further
129  *    binary redistribution.
130  * 3. Neither the names of the above-listed copyright holders nor the names
131  *    of any contributors may be used to endorse or promote products derived
132  *    from this software without specific prior written permission.
133  *
134  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
135  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
136  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
137  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
138  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
139  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
140  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
141  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
142  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
143  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
144  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
145  *
146  * Alternatively, you may choose to be licensed under the terms of the
147  * GNU General Public License ("GPL") version 2 as published by the Free
148  * Software Foundation.
149  *
150  *****************************************************************************/
151 
152 #include <contrib/dev/acpica/include/acpi.h>
153 #include <contrib/dev/acpica/include/accommon.h>
154 #include <contrib/dev/acpica/include/acnamesp.h>
155 
156 
157 #define _COMPONENT          ACPI_NAMESPACE
158         ACPI_MODULE_NAME    ("nsalloc")
159 
160 
161 /*******************************************************************************
162  *
163  * FUNCTION:    AcpiNsCreateNode
164  *
165  * PARAMETERS:  Name            - Name of the new node (4 char ACPI name)
166  *
167  * RETURN:      New namespace node (Null on failure)
168  *
169  * DESCRIPTION: Create a namespace node
170  *
171  ******************************************************************************/
172 
173 ACPI_NAMESPACE_NODE *
AcpiNsCreateNode(UINT32 Name)174 AcpiNsCreateNode (
175     UINT32                  Name)
176 {
177     ACPI_NAMESPACE_NODE     *Node;
178 #ifdef ACPI_DBG_TRACK_ALLOCATIONS
179     UINT32                  Temp;
180 #endif
181 
182 
183     ACPI_FUNCTION_TRACE (NsCreateNode);
184 
185 
186     Node = AcpiOsAcquireObject (AcpiGbl_NamespaceCache);
187     if (!Node)
188     {
189         return_PTR (NULL);
190     }
191 
192     ACPI_MEM_TRACKING (AcpiGbl_NsNodeList->TotalAllocated++);
193 
194 #ifdef ACPI_DBG_TRACK_ALLOCATIONS
195         Temp = AcpiGbl_NsNodeList->TotalAllocated -
196             AcpiGbl_NsNodeList->TotalFreed;
197         if (Temp > AcpiGbl_NsNodeList->MaxOccupied)
198         {
199             AcpiGbl_NsNodeList->MaxOccupied = Temp;
200         }
201 #endif
202 
203     Node->Name.Integer = Name;
204     ACPI_SET_DESCRIPTOR_TYPE (Node, ACPI_DESC_TYPE_NAMED);
205     return_PTR (Node);
206 }
207 
208 
209 /*******************************************************************************
210  *
211  * FUNCTION:    AcpiNsDeleteNode
212  *
213  * PARAMETERS:  Node            - Node to be deleted
214  *
215  * RETURN:      None
216  *
217  * DESCRIPTION: Delete a namespace node. All node deletions must come through
218  *              here. Detaches any attached objects, including any attached
219  *              data. If a handler is associated with attached data, it is
220  *              invoked before the node is deleted.
221  *
222  ******************************************************************************/
223 
224 void
AcpiNsDeleteNode(ACPI_NAMESPACE_NODE * Node)225 AcpiNsDeleteNode (
226     ACPI_NAMESPACE_NODE     *Node)
227 {
228     ACPI_OPERAND_OBJECT     *ObjDesc;
229     ACPI_OPERAND_OBJECT     *NextDesc;
230 
231 
232     ACPI_FUNCTION_NAME (NsDeleteNode);
233 
234 
235     if (!Node)
236     {
237         return_VOID;
238     }
239 
240     /* Detach an object if there is one */
241 
242     AcpiNsDetachObject (Node);
243 
244     /*
245      * Delete an attached data object list if present (objects that were
246      * attached via AcpiAttachData). Note: After any normal object is
247      * detached above, the only possible remaining object(s) are data
248      * objects, in a linked list.
249      */
250     ObjDesc = Node->Object;
251     while (ObjDesc &&
252         (ObjDesc->Common.Type == ACPI_TYPE_LOCAL_DATA))
253     {
254         /* Invoke the attached data deletion handler if present */
255 
256         if (ObjDesc->Data.Handler)
257         {
258             ObjDesc->Data.Handler (Node, ObjDesc->Data.Pointer);
259         }
260 
261         NextDesc = ObjDesc->Common.NextObject;
262         AcpiUtRemoveReference (ObjDesc);
263         ObjDesc = NextDesc;
264     }
265 
266     /* Special case for the statically allocated root node */
267 
268     if (Node == AcpiGbl_RootNode)
269     {
270         return;
271     }
272 
273     /* Now we can delete the node */
274 
275     (void) AcpiOsReleaseObject (AcpiGbl_NamespaceCache, Node);
276 
277     ACPI_MEM_TRACKING (AcpiGbl_NsNodeList->TotalFreed++);
278     ACPI_DEBUG_PRINT ((ACPI_DB_ALLOCATIONS, "Node %p, Remaining %X\n",
279         Node, AcpiGbl_CurrentNodeCount));
280 }
281 
282 
283 /*******************************************************************************
284  *
285  * FUNCTION:    AcpiNsRemoveNode
286  *
287  * PARAMETERS:  Node            - Node to be removed/deleted
288  *
289  * RETURN:      None
290  *
291  * DESCRIPTION: Remove (unlink) and delete a namespace node
292  *
293  ******************************************************************************/
294 
295 void
AcpiNsRemoveNode(ACPI_NAMESPACE_NODE * Node)296 AcpiNsRemoveNode (
297     ACPI_NAMESPACE_NODE     *Node)
298 {
299     ACPI_NAMESPACE_NODE     *ParentNode;
300     ACPI_NAMESPACE_NODE     *PrevNode;
301     ACPI_NAMESPACE_NODE     *NextNode;
302 
303 
304     ACPI_FUNCTION_TRACE_PTR (NsRemoveNode, Node);
305 
306 
307     ParentNode = Node->Parent;
308 
309     PrevNode = NULL;
310     NextNode = ParentNode->Child;
311 
312     /* Find the node that is the previous peer in the parent's child list */
313 
314     while (NextNode != Node)
315     {
316         PrevNode = NextNode;
317         NextNode = NextNode->Peer;
318     }
319 
320     if (PrevNode)
321     {
322         /* Node is not first child, unlink it */
323 
324         PrevNode->Peer = Node->Peer;
325     }
326     else
327     {
328         /*
329          * Node is first child (has no previous peer).
330          * Link peer list to parent
331          */
332         ParentNode->Child = Node->Peer;
333     }
334 
335     /* Delete the node and any attached objects */
336 
337     AcpiNsDeleteNode (Node);
338     return_VOID;
339 }
340 
341 
342 /*******************************************************************************
343  *
344  * FUNCTION:    AcpiNsInstallNode
345  *
346  * PARAMETERS:  WalkState       - Current state of the walk
347  *              ParentNode      - The parent of the new Node
348  *              Node            - The new Node to install
349  *              Type            - ACPI object type of the new Node
350  *
351  * RETURN:      None
352  *
353  * DESCRIPTION: Initialize a new namespace node and install it amongst
354  *              its peers.
355  *
356  *              Note: Current namespace lookup is linear search. This appears
357  *              to be sufficient as namespace searches consume only a small
358  *              fraction of the execution time of the ACPI subsystem.
359  *
360  ******************************************************************************/
361 
362 void
AcpiNsInstallNode(ACPI_WALK_STATE * WalkState,ACPI_NAMESPACE_NODE * ParentNode,ACPI_NAMESPACE_NODE * Node,ACPI_OBJECT_TYPE Type)363 AcpiNsInstallNode (
364     ACPI_WALK_STATE         *WalkState,
365     ACPI_NAMESPACE_NODE     *ParentNode,    /* Parent */
366     ACPI_NAMESPACE_NODE     *Node,          /* New Child*/
367     ACPI_OBJECT_TYPE        Type)
368 {
369     ACPI_OWNER_ID           OwnerId = 0;
370     ACPI_NAMESPACE_NODE     *ChildNode;
371 
372 
373     ACPI_FUNCTION_TRACE (NsInstallNode);
374 
375 
376     if (WalkState)
377     {
378         /*
379          * Get the owner ID from the Walk state. The owner ID is used to
380          * track table deletion and deletion of objects created by methods.
381          */
382         OwnerId = WalkState->OwnerId;
383 
384         if ((WalkState->MethodDesc) &&
385             (ParentNode != WalkState->MethodNode))
386         {
387             /*
388              * A method is creating a new node that is not a child of the
389              * method (it is non-local). Mark the executing method as having
390              * modified the namespace. This is used for cleanup when the
391              * method exits.
392              */
393             WalkState->MethodDesc->Method.InfoFlags |=
394                 ACPI_METHOD_MODIFIED_NAMESPACE;
395         }
396     }
397 
398     /* Link the new entry into the parent and existing children */
399 
400     Node->Peer = NULL;
401     Node->Parent = ParentNode;
402     ChildNode = ParentNode->Child;
403 
404     if (!ChildNode)
405     {
406         ParentNode->Child = Node;
407     }
408     else
409     {
410         /* Add node to the end of the peer list */
411 
412         while (ChildNode->Peer)
413         {
414             ChildNode = ChildNode->Peer;
415         }
416 
417         ChildNode->Peer = Node;
418     }
419 
420     /* Init the new entry */
421 
422     Node->OwnerId = OwnerId;
423     Node->Type = (UINT8) Type;
424 
425     ACPI_DEBUG_PRINT ((ACPI_DB_NAMES,
426         "%4.4s (%s) [Node %p Owner %3.3X] added to %4.4s (%s) [Node %p]\n",
427         AcpiUtGetNodeName (Node), AcpiUtGetTypeName (Node->Type), Node, OwnerId,
428         AcpiUtGetNodeName (ParentNode), AcpiUtGetTypeName (ParentNode->Type),
429         ParentNode));
430 
431     return_VOID;
432 }
433 
434 
435 /*******************************************************************************
436  *
437  * FUNCTION:    AcpiNsDeleteChildren
438  *
439  * PARAMETERS:  ParentNode      - Delete this objects children
440  *
441  * RETURN:      None.
442  *
443  * DESCRIPTION: Delete all children of the parent object. In other words,
444  *              deletes a "scope".
445  *
446  ******************************************************************************/
447 
448 void
AcpiNsDeleteChildren(ACPI_NAMESPACE_NODE * ParentNode)449 AcpiNsDeleteChildren (
450     ACPI_NAMESPACE_NODE     *ParentNode)
451 {
452     ACPI_NAMESPACE_NODE     *NextNode;
453     ACPI_NAMESPACE_NODE     *NodeToDelete;
454 
455 
456     ACPI_FUNCTION_TRACE_PTR (NsDeleteChildren, ParentNode);
457 
458 
459     if (!ParentNode)
460     {
461         return_VOID;
462     }
463 
464     /* Deallocate all children at this level */
465 
466     NextNode = ParentNode->Child;
467     while (NextNode)
468     {
469         /* Grandchildren should have all been deleted already */
470 
471         if (NextNode->Child)
472         {
473             ACPI_ERROR ((AE_INFO, "Found a grandchild! P=%p C=%p",
474                 ParentNode, NextNode));
475         }
476 
477         /*
478          * Delete this child node and move on to the next child in the list.
479          * No need to unlink the node since we are deleting the entire branch.
480          */
481         NodeToDelete = NextNode;
482         NextNode = NextNode->Peer;
483         AcpiNsDeleteNode (NodeToDelete);
484     }
485 
486     /* Clear the parent's child pointer */
487 
488     ParentNode->Child = NULL;
489     return_VOID;
490 }
491 
492 
493 /*******************************************************************************
494  *
495  * FUNCTION:    AcpiNsDeleteNamespaceSubtree
496  *
497  * PARAMETERS:  ParentNode      - Root of the subtree to be deleted
498  *
499  * RETURN:      None.
500  *
501  * DESCRIPTION: Delete a subtree of the namespace. This includes all objects
502  *              stored within the subtree.
503  *
504  ******************************************************************************/
505 
506 void
AcpiNsDeleteNamespaceSubtree(ACPI_NAMESPACE_NODE * ParentNode)507 AcpiNsDeleteNamespaceSubtree (
508     ACPI_NAMESPACE_NODE     *ParentNode)
509 {
510     ACPI_NAMESPACE_NODE     *ChildNode = NULL;
511     UINT32                  Level = 1;
512     ACPI_STATUS             Status;
513 
514 
515     ACPI_FUNCTION_TRACE (NsDeleteNamespaceSubtree);
516 
517 
518     if (!ParentNode)
519     {
520         return_VOID;
521     }
522 
523     /* Lock namespace for possible update */
524 
525     Status = AcpiUtAcquireMutex (ACPI_MTX_NAMESPACE);
526     if (ACPI_FAILURE (Status))
527     {
528         return_VOID;
529     }
530 
531     /*
532      * Traverse the tree of objects until we bubble back up
533      * to where we started.
534      */
535     while (Level > 0)
536     {
537         /* Get the next node in this scope (NULL if none) */
538 
539         ChildNode = AcpiNsGetNextNode (ParentNode, ChildNode);
540         if (ChildNode)
541         {
542             /* Found a child node - detach any attached object */
543 
544             AcpiNsDetachObject (ChildNode);
545 
546             /* Check if this node has any children */
547 
548             if (ChildNode->Child)
549             {
550                 /*
551                  * There is at least one child of this node,
552                  * visit the node
553                  */
554                 Level++;
555                 ParentNode = ChildNode;
556                 ChildNode  = NULL;
557             }
558         }
559         else
560         {
561             /*
562              * No more children of this parent node.
563              * Move up to the grandparent.
564              */
565             Level--;
566 
567             /*
568              * Now delete all of the children of this parent
569              * all at the same time.
570              */
571             AcpiNsDeleteChildren (ParentNode);
572 
573             /* New "last child" is this parent node */
574 
575             ChildNode = ParentNode;
576 
577             /* Move up the tree to the grandparent */
578 
579             ParentNode = ParentNode->Parent;
580         }
581     }
582 
583     (void) AcpiUtReleaseMutex (ACPI_MTX_NAMESPACE);
584     return_VOID;
585 }
586 
587 
588 /*******************************************************************************
589  *
590  * FUNCTION:    AcpiNsDeleteNamespaceByOwner
591  *
592  * PARAMETERS:  OwnerId     - All nodes with this owner will be deleted
593  *
594  * RETURN:      Status
595  *
596  * DESCRIPTION: Delete entries within the namespace that are owned by a
597  *              specific ID. Used to delete entire ACPI tables. All
598  *              reference counts are updated.
599  *
600  * MUTEX:       Locks namespace during deletion walk.
601  *
602  ******************************************************************************/
603 
604 void
AcpiNsDeleteNamespaceByOwner(ACPI_OWNER_ID OwnerId)605 AcpiNsDeleteNamespaceByOwner (
606     ACPI_OWNER_ID            OwnerId)
607 {
608     ACPI_NAMESPACE_NODE     *ChildNode;
609     ACPI_NAMESPACE_NODE     *DeletionNode;
610     ACPI_NAMESPACE_NODE     *ParentNode;
611     UINT32                  Level;
612     ACPI_STATUS             Status;
613 
614 
615     ACPI_FUNCTION_TRACE_U32 (NsDeleteNamespaceByOwner, OwnerId);
616 
617 
618     if (OwnerId == 0)
619     {
620         return_VOID;
621     }
622 
623     /* Lock namespace for possible update */
624 
625     Status = AcpiUtAcquireMutex (ACPI_MTX_NAMESPACE);
626     if (ACPI_FAILURE (Status))
627     {
628         return_VOID;
629     }
630 
631     DeletionNode = NULL;
632     ParentNode = AcpiGbl_RootNode;
633     ChildNode = NULL;
634     Level = 1;
635 
636     /*
637      * Traverse the tree of nodes until we bubble back up
638      * to where we started.
639      */
640     while (Level > 0)
641     {
642         /*
643          * Get the next child of this parent node. When ChildNode is NULL,
644          * the first child of the parent is returned
645          */
646         ChildNode = AcpiNsGetNextNode (ParentNode, ChildNode);
647 
648         if (DeletionNode)
649         {
650             AcpiNsDeleteChildren (DeletionNode);
651             AcpiNsRemoveNode (DeletionNode);
652             DeletionNode = NULL;
653         }
654 
655         if (ChildNode)
656         {
657             if (ChildNode->OwnerId == OwnerId)
658             {
659                 /* Found a matching child node - detach any attached object */
660 
661                 AcpiNsDetachObject (ChildNode);
662             }
663 
664             /* Check if this node has any children */
665 
666             if (ChildNode->Child)
667             {
668                 /*
669                  * There is at least one child of this node,
670                  * visit the node
671                  */
672                 Level++;
673                 ParentNode = ChildNode;
674                 ChildNode  = NULL;
675             }
676             else if (ChildNode->OwnerId == OwnerId)
677             {
678                 DeletionNode = ChildNode;
679             }
680         }
681         else
682         {
683             /*
684              * No more children of this parent node.
685              * Move up to the grandparent.
686              */
687             Level--;
688             if (Level != 0)
689             {
690                 if (ParentNode->OwnerId == OwnerId)
691                 {
692                     DeletionNode = ParentNode;
693                 }
694             }
695 
696             /* New "last child" is this parent node */
697 
698             ChildNode = ParentNode;
699 
700             /* Move up the tree to the grandparent */
701 
702             ParentNode = ParentNode->Parent;
703         }
704     }
705 
706     (void) AcpiUtReleaseMutex (ACPI_MTX_NAMESPACE);
707     return_VOID;
708 }
709