xref: /openbmc/linux/drivers/acpi/acpica/utdelete.c (revision 293d5b43)
1 /*******************************************************************************
2  *
3  * Module Name: utdelete - object deletion and reference count utilities
4  *
5  ******************************************************************************/
6 
7 /*
8  * Copyright (C) 2000 - 2016, Intel Corp.
9  * All rights reserved.
10  *
11  * Redistribution and use in source and binary forms, with or without
12  * modification, are permitted provided that the following conditions
13  * are met:
14  * 1. Redistributions of source code must retain the above copyright
15  *    notice, this list of conditions, and the following disclaimer,
16  *    without modification.
17  * 2. Redistributions in binary form must reproduce at minimum a disclaimer
18  *    substantially similar to the "NO WARRANTY" disclaimer below
19  *    ("Disclaimer") and any redistribution must be conditioned upon
20  *    including a substantially similar Disclaimer requirement for further
21  *    binary redistribution.
22  * 3. Neither the names of the above-listed copyright holders nor the names
23  *    of any contributors may be used to endorse or promote products derived
24  *    from this software without specific prior written permission.
25  *
26  * Alternatively, this software may be distributed under the terms of the
27  * GNU General Public License ("GPL") version 2 as published by the Free
28  * Software Foundation.
29  *
30  * NO WARRANTY
31  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
32  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
33  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
34  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
35  * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
36  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
37  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
38  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
39  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
40  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
41  * POSSIBILITY OF SUCH DAMAGES.
42  */
43 
44 #include <acpi/acpi.h>
45 #include "accommon.h"
46 #include "acinterp.h"
47 #include "acnamesp.h"
48 #include "acevents.h"
49 
50 #define _COMPONENT          ACPI_UTILITIES
51 ACPI_MODULE_NAME("utdelete")
52 
53 /* Local prototypes */
54 static void acpi_ut_delete_internal_obj(union acpi_operand_object *object);
55 
56 static void
57 acpi_ut_update_ref_count(union acpi_operand_object *object, u32 action);
58 
59 /*******************************************************************************
60  *
61  * FUNCTION:    acpi_ut_delete_internal_obj
62  *
63  * PARAMETERS:  object         - Object to be deleted
64  *
65  * RETURN:      None
66  *
67  * DESCRIPTION: Low level object deletion, after reference counts have been
68  *              updated (All reference counts, including sub-objects!)
69  *
70  ******************************************************************************/
71 
72 static void acpi_ut_delete_internal_obj(union acpi_operand_object *object)
73 {
74 	void *obj_pointer = NULL;
75 	union acpi_operand_object *handler_desc;
76 	union acpi_operand_object *second_desc;
77 	union acpi_operand_object *next_desc;
78 	union acpi_operand_object *start_desc;
79 	union acpi_operand_object **last_obj_ptr;
80 
81 	ACPI_FUNCTION_TRACE_PTR(ut_delete_internal_obj, object);
82 
83 	if (!object) {
84 		return_VOID;
85 	}
86 
87 	/*
88 	 * Must delete or free any pointers within the object that are not
89 	 * actual ACPI objects (for example, a raw buffer pointer).
90 	 */
91 	switch (object->common.type) {
92 	case ACPI_TYPE_STRING:
93 
94 		ACPI_DEBUG_PRINT((ACPI_DB_ALLOCATIONS,
95 				  "**** String %p, ptr %p\n", object,
96 				  object->string.pointer));
97 
98 		/* Free the actual string buffer */
99 
100 		if (!(object->common.flags & AOPOBJ_STATIC_POINTER)) {
101 
102 			/* But only if it is NOT a pointer into an ACPI table */
103 
104 			obj_pointer = object->string.pointer;
105 		}
106 		break;
107 
108 	case ACPI_TYPE_BUFFER:
109 
110 		ACPI_DEBUG_PRINT((ACPI_DB_ALLOCATIONS,
111 				  "**** Buffer %p, ptr %p\n", object,
112 				  object->buffer.pointer));
113 
114 		/* Free the actual buffer */
115 
116 		if (!(object->common.flags & AOPOBJ_STATIC_POINTER)) {
117 
118 			/* But only if it is NOT a pointer into an ACPI table */
119 
120 			obj_pointer = object->buffer.pointer;
121 		}
122 		break;
123 
124 	case ACPI_TYPE_PACKAGE:
125 
126 		ACPI_DEBUG_PRINT((ACPI_DB_ALLOCATIONS,
127 				  " **** Package of count %X\n",
128 				  object->package.count));
129 
130 		/*
131 		 * Elements of the package are not handled here, they are deleted
132 		 * separately
133 		 */
134 
135 		/* Free the (variable length) element pointer array */
136 
137 		obj_pointer = object->package.elements;
138 		break;
139 
140 		/*
141 		 * These objects have a possible list of notify handlers.
142 		 * Device object also may have a GPE block.
143 		 */
144 	case ACPI_TYPE_DEVICE:
145 
146 		if (object->device.gpe_block) {
147 			(void)acpi_ev_delete_gpe_block(object->device.
148 						       gpe_block);
149 		}
150 
151 		/*lint -fallthrough */
152 
153 	case ACPI_TYPE_PROCESSOR:
154 	case ACPI_TYPE_THERMAL:
155 
156 		/* Walk the address handler list for this object */
157 
158 		handler_desc = object->common_notify.handler;
159 		while (handler_desc) {
160 			next_desc = handler_desc->address_space.next;
161 			acpi_ut_remove_reference(handler_desc);
162 			handler_desc = next_desc;
163 		}
164 		break;
165 
166 	case ACPI_TYPE_MUTEX:
167 
168 		ACPI_DEBUG_PRINT((ACPI_DB_ALLOCATIONS,
169 				  "***** Mutex %p, OS Mutex %p\n",
170 				  object, object->mutex.os_mutex));
171 
172 		if (object == acpi_gbl_global_lock_mutex) {
173 
174 			/* Global Lock has extra semaphore */
175 
176 			(void)
177 			    acpi_os_delete_semaphore
178 			    (acpi_gbl_global_lock_semaphore);
179 			acpi_gbl_global_lock_semaphore = NULL;
180 
181 			acpi_os_delete_mutex(object->mutex.os_mutex);
182 			acpi_gbl_global_lock_mutex = NULL;
183 		} else {
184 			acpi_ex_unlink_mutex(object);
185 			acpi_os_delete_mutex(object->mutex.os_mutex);
186 		}
187 		break;
188 
189 	case ACPI_TYPE_EVENT:
190 
191 		ACPI_DEBUG_PRINT((ACPI_DB_ALLOCATIONS,
192 				  "***** Event %p, OS Semaphore %p\n",
193 				  object, object->event.os_semaphore));
194 
195 		(void)acpi_os_delete_semaphore(object->event.os_semaphore);
196 		object->event.os_semaphore = NULL;
197 		break;
198 
199 	case ACPI_TYPE_METHOD:
200 
201 		ACPI_DEBUG_PRINT((ACPI_DB_ALLOCATIONS,
202 				  "***** Method %p\n", object));
203 
204 		/* Delete the method mutex if it exists */
205 
206 		if (object->method.mutex) {
207 			acpi_os_delete_mutex(object->method.mutex->mutex.
208 					     os_mutex);
209 			acpi_ut_delete_object_desc(object->method.mutex);
210 			object->method.mutex = NULL;
211 		}
212 
213 		if (object->method.node) {
214 			object->method.node = NULL;
215 		}
216 		break;
217 
218 	case ACPI_TYPE_REGION:
219 
220 		ACPI_DEBUG_PRINT((ACPI_DB_ALLOCATIONS,
221 				  "***** Region %p\n", object));
222 
223 		/*
224 		 * Update address_range list. However, only permanent regions
225 		 * are installed in this list. (Not created within a method)
226 		 */
227 		if (!(object->region.node->flags & ANOBJ_TEMPORARY)) {
228 			acpi_ut_remove_address_range(object->region.space_id,
229 						     object->region.node);
230 		}
231 
232 		second_desc = acpi_ns_get_secondary_object(object);
233 		if (second_desc) {
234 			/*
235 			 * Free the region_context if and only if the handler is one of the
236 			 * default handlers -- and therefore, we created the context object
237 			 * locally, it was not created by an external caller.
238 			 */
239 			handler_desc = object->region.handler;
240 			if (handler_desc) {
241 				next_desc =
242 				    handler_desc->address_space.region_list;
243 				start_desc = next_desc;
244 				last_obj_ptr =
245 				    &handler_desc->address_space.region_list;
246 
247 				/* Remove the region object from the handler list */
248 
249 				while (next_desc) {
250 					if (next_desc == object) {
251 						*last_obj_ptr =
252 						    next_desc->region.next;
253 						break;
254 					}
255 
256 					/* Walk the linked list of handlers */
257 
258 					last_obj_ptr = &next_desc->region.next;
259 					next_desc = next_desc->region.next;
260 
261 					/* Prevent infinite loop if list is corrupted */
262 
263 					if (next_desc == start_desc) {
264 						ACPI_ERROR((AE_INFO,
265 							    "Circular region list in address handler object %p",
266 							    handler_desc));
267 						return_VOID;
268 					}
269 				}
270 
271 				if (handler_desc->address_space.handler_flags &
272 				    ACPI_ADDR_HANDLER_DEFAULT_INSTALLED) {
273 
274 					/* Deactivate region and free region context */
275 
276 					if (handler_desc->address_space.setup) {
277 						(void)handler_desc->
278 						    address_space.setup(object,
279 									ACPI_REGION_DEACTIVATE,
280 									handler_desc->
281 									address_space.
282 									context,
283 									&second_desc->
284 									extra.
285 									region_context);
286 					}
287 				}
288 
289 				acpi_ut_remove_reference(handler_desc);
290 			}
291 
292 			/* Now we can free the Extra object */
293 
294 			acpi_ut_delete_object_desc(second_desc);
295 		}
296 		break;
297 
298 	case ACPI_TYPE_BUFFER_FIELD:
299 
300 		ACPI_DEBUG_PRINT((ACPI_DB_ALLOCATIONS,
301 				  "***** Buffer Field %p\n", object));
302 
303 		second_desc = acpi_ns_get_secondary_object(object);
304 		if (second_desc) {
305 			acpi_ut_delete_object_desc(second_desc);
306 		}
307 		break;
308 
309 	case ACPI_TYPE_LOCAL_BANK_FIELD:
310 
311 		ACPI_DEBUG_PRINT((ACPI_DB_ALLOCATIONS,
312 				  "***** Bank Field %p\n", object));
313 
314 		second_desc = acpi_ns_get_secondary_object(object);
315 		if (second_desc) {
316 			acpi_ut_delete_object_desc(second_desc);
317 		}
318 		break;
319 
320 	default:
321 
322 		break;
323 	}
324 
325 	/* Free any allocated memory (pointer within the object) found above */
326 
327 	if (obj_pointer) {
328 		ACPI_DEBUG_PRINT((ACPI_DB_ALLOCATIONS,
329 				  "Deleting Object Subptr %p\n", obj_pointer));
330 		ACPI_FREE(obj_pointer);
331 	}
332 
333 	/* Now the object can be safely deleted */
334 
335 	ACPI_DEBUG_PRINT((ACPI_DB_ALLOCATIONS, "Deleting Object %p [%s]\n",
336 			  object, acpi_ut_get_object_type_name(object)));
337 
338 	acpi_ut_delete_object_desc(object);
339 	return_VOID;
340 }
341 
342 /*******************************************************************************
343  *
344  * FUNCTION:    acpi_ut_delete_internal_object_list
345  *
346  * PARAMETERS:  obj_list        - Pointer to the list to be deleted
347  *
348  * RETURN:      None
349  *
350  * DESCRIPTION: This function deletes an internal object list, including both
351  *              simple objects and package objects
352  *
353  ******************************************************************************/
354 
355 void acpi_ut_delete_internal_object_list(union acpi_operand_object **obj_list)
356 {
357 	union acpi_operand_object **internal_obj;
358 
359 	ACPI_FUNCTION_ENTRY();
360 
361 	/* Walk the null-terminated internal list */
362 
363 	for (internal_obj = obj_list; *internal_obj; internal_obj++) {
364 		acpi_ut_remove_reference(*internal_obj);
365 	}
366 
367 	/* Free the combined parameter pointer list and object array */
368 
369 	ACPI_FREE(obj_list);
370 	return;
371 }
372 
373 /*******************************************************************************
374  *
375  * FUNCTION:    acpi_ut_update_ref_count
376  *
377  * PARAMETERS:  object          - Object whose ref count is to be updated
378  *              action          - What to do (REF_INCREMENT or REF_DECREMENT)
379  *
380  * RETURN:      None. Sets new reference count within the object
381  *
382  * DESCRIPTION: Modify the reference count for an internal acpi object
383  *
384  ******************************************************************************/
385 
386 static void
387 acpi_ut_update_ref_count(union acpi_operand_object *object, u32 action)
388 {
389 	u16 original_count;
390 	u16 new_count = 0;
391 	acpi_cpu_flags lock_flags;
392 
393 	ACPI_FUNCTION_NAME(ut_update_ref_count);
394 
395 	if (!object) {
396 		return;
397 	}
398 
399 	/*
400 	 * Always get the reference count lock. Note: Interpreter and/or
401 	 * Namespace is not always locked when this function is called.
402 	 */
403 	lock_flags = acpi_os_acquire_lock(acpi_gbl_reference_count_lock);
404 	original_count = object->common.reference_count;
405 
406 	/* Perform the reference count action (increment, decrement) */
407 
408 	switch (action) {
409 	case REF_INCREMENT:
410 
411 		new_count = original_count + 1;
412 		object->common.reference_count = new_count;
413 		acpi_os_release_lock(acpi_gbl_reference_count_lock, lock_flags);
414 
415 		/* The current reference count should never be zero here */
416 
417 		if (!original_count) {
418 			ACPI_WARNING((AE_INFO,
419 				      "Obj %p, Reference Count was zero before increment\n",
420 				      object));
421 		}
422 
423 		ACPI_DEBUG_PRINT((ACPI_DB_ALLOCATIONS,
424 				  "Obj %p Type %.2X Refs %.2X [Incremented]\n",
425 				  object, object->common.type, new_count));
426 		break;
427 
428 	case REF_DECREMENT:
429 
430 		/* The current reference count must be non-zero */
431 
432 		if (original_count) {
433 			new_count = original_count - 1;
434 			object->common.reference_count = new_count;
435 		}
436 
437 		acpi_os_release_lock(acpi_gbl_reference_count_lock, lock_flags);
438 
439 		if (!original_count) {
440 			ACPI_WARNING((AE_INFO,
441 				      "Obj %p, Reference Count is already zero, cannot decrement\n",
442 				      object));
443 		}
444 
445 		ACPI_DEBUG_PRINT((ACPI_DB_ALLOCATIONS,
446 				  "Obj %p Type %.2X Refs %.2X [Decremented]\n",
447 				  object, object->common.type, new_count));
448 
449 		/* Actually delete the object on a reference count of zero */
450 
451 		if (new_count == 0) {
452 			acpi_ut_delete_internal_obj(object);
453 		}
454 		break;
455 
456 	default:
457 
458 		acpi_os_release_lock(acpi_gbl_reference_count_lock, lock_flags);
459 		ACPI_ERROR((AE_INFO, "Unknown Reference Count action (0x%X)",
460 			    action));
461 		return;
462 	}
463 
464 	/*
465 	 * Sanity check the reference count, for debug purposes only.
466 	 * (A deleted object will have a huge reference count)
467 	 */
468 	if (new_count > ACPI_MAX_REFERENCE_COUNT) {
469 		ACPI_WARNING((AE_INFO,
470 			      "Large Reference Count (0x%X) in object %p, Type=0x%.2X",
471 			      new_count, object, object->common.type));
472 	}
473 }
474 
475 /*******************************************************************************
476  *
477  * FUNCTION:    acpi_ut_update_object_reference
478  *
479  * PARAMETERS:  object              - Increment ref count for this object
480  *                                    and all sub-objects
481  *              action              - Either REF_INCREMENT or REF_DECREMENT
482  *
483  * RETURN:      Status
484  *
485  * DESCRIPTION: Increment the object reference count
486  *
487  * Object references are incremented when:
488  * 1) An object is attached to a Node (namespace object)
489  * 2) An object is copied (all subobjects must be incremented)
490  *
491  * Object references are decremented when:
492  * 1) An object is detached from an Node
493  *
494  ******************************************************************************/
495 
496 acpi_status
497 acpi_ut_update_object_reference(union acpi_operand_object *object, u16 action)
498 {
499 	acpi_status status = AE_OK;
500 	union acpi_generic_state *state_list = NULL;
501 	union acpi_operand_object *next_object = NULL;
502 	union acpi_operand_object *prev_object;
503 	union acpi_generic_state *state;
504 	u32 i;
505 
506 	ACPI_FUNCTION_NAME(ut_update_object_reference);
507 
508 	while (object) {
509 
510 		/* Make sure that this isn't a namespace handle */
511 
512 		if (ACPI_GET_DESCRIPTOR_TYPE(object) == ACPI_DESC_TYPE_NAMED) {
513 			ACPI_DEBUG_PRINT((ACPI_DB_ALLOCATIONS,
514 					  "Object %p is NS handle\n", object));
515 			return (AE_OK);
516 		}
517 
518 		/*
519 		 * All sub-objects must have their reference count incremented
520 		 * also. Different object types have different subobjects.
521 		 */
522 		switch (object->common.type) {
523 		case ACPI_TYPE_DEVICE:
524 		case ACPI_TYPE_PROCESSOR:
525 		case ACPI_TYPE_POWER:
526 		case ACPI_TYPE_THERMAL:
527 			/*
528 			 * Update the notify objects for these types (if present)
529 			 * Two lists, system and device notify handlers.
530 			 */
531 			for (i = 0; i < ACPI_NUM_NOTIFY_TYPES; i++) {
532 				prev_object =
533 				    object->common_notify.notify_list[i];
534 				while (prev_object) {
535 					next_object =
536 					    prev_object->notify.next[i];
537 					acpi_ut_update_ref_count(prev_object,
538 								 action);
539 					prev_object = next_object;
540 				}
541 			}
542 			break;
543 
544 		case ACPI_TYPE_PACKAGE:
545 			/*
546 			 * We must update all the sub-objects of the package,
547 			 * each of whom may have their own sub-objects.
548 			 */
549 			for (i = 0; i < object->package.count; i++) {
550 				/*
551 				 * Null package elements are legal and can be simply
552 				 * ignored.
553 				 */
554 				next_object = object->package.elements[i];
555 				if (!next_object) {
556 					continue;
557 				}
558 
559 				switch (next_object->common.type) {
560 				case ACPI_TYPE_INTEGER:
561 				case ACPI_TYPE_STRING:
562 				case ACPI_TYPE_BUFFER:
563 					/*
564 					 * For these very simple sub-objects, we can just
565 					 * update the reference count here and continue.
566 					 * Greatly increases performance of this operation.
567 					 */
568 					acpi_ut_update_ref_count(next_object,
569 								 action);
570 					break;
571 
572 				default:
573 					/*
574 					 * For complex sub-objects, push them onto the stack
575 					 * for later processing (this eliminates recursion.)
576 					 */
577 					status =
578 					    acpi_ut_create_update_state_and_push
579 					    (next_object, action, &state_list);
580 					if (ACPI_FAILURE(status)) {
581 						goto error_exit;
582 					}
583 					break;
584 				}
585 			}
586 			next_object = NULL;
587 			break;
588 
589 		case ACPI_TYPE_BUFFER_FIELD:
590 
591 			next_object = object->buffer_field.buffer_obj;
592 			break;
593 
594 		case ACPI_TYPE_LOCAL_REGION_FIELD:
595 
596 			next_object = object->field.region_obj;
597 			break;
598 
599 		case ACPI_TYPE_LOCAL_BANK_FIELD:
600 
601 			next_object = object->bank_field.bank_obj;
602 			status =
603 			    acpi_ut_create_update_state_and_push(object->
604 								 bank_field.
605 								 region_obj,
606 								 action,
607 								 &state_list);
608 			if (ACPI_FAILURE(status)) {
609 				goto error_exit;
610 			}
611 			break;
612 
613 		case ACPI_TYPE_LOCAL_INDEX_FIELD:
614 
615 			next_object = object->index_field.index_obj;
616 			status =
617 			    acpi_ut_create_update_state_and_push(object->
618 								 index_field.
619 								 data_obj,
620 								 action,
621 								 &state_list);
622 			if (ACPI_FAILURE(status)) {
623 				goto error_exit;
624 			}
625 			break;
626 
627 		case ACPI_TYPE_LOCAL_REFERENCE:
628 			/*
629 			 * The target of an Index (a package, string, or buffer) or a named
630 			 * reference must track changes to the ref count of the index or
631 			 * target object.
632 			 */
633 			if ((object->reference.class == ACPI_REFCLASS_INDEX) ||
634 			    (object->reference.class == ACPI_REFCLASS_NAME)) {
635 				next_object = object->reference.object;
636 			}
637 			break;
638 
639 		case ACPI_TYPE_REGION:
640 		default:
641 
642 			break;	/* No subobjects for all other types */
643 		}
644 
645 		/*
646 		 * Now we can update the count in the main object. This can only
647 		 * happen after we update the sub-objects in case this causes the
648 		 * main object to be deleted.
649 		 */
650 		acpi_ut_update_ref_count(object, action);
651 		object = NULL;
652 
653 		/* Move on to the next object to be updated */
654 
655 		if (next_object) {
656 			object = next_object;
657 			next_object = NULL;
658 		} else if (state_list) {
659 			state = acpi_ut_pop_generic_state(&state_list);
660 			object = state->update.object;
661 			acpi_ut_delete_generic_state(state);
662 		}
663 	}
664 
665 	return (AE_OK);
666 
667 error_exit:
668 
669 	ACPI_EXCEPTION((AE_INFO, status,
670 			"Could not update object reference count"));
671 
672 	/* Free any stacked Update State objects */
673 
674 	while (state_list) {
675 		state = acpi_ut_pop_generic_state(&state_list);
676 		acpi_ut_delete_generic_state(state);
677 	}
678 
679 	return (status);
680 }
681 
682 /*******************************************************************************
683  *
684  * FUNCTION:    acpi_ut_add_reference
685  *
686  * PARAMETERS:  object          - Object whose reference count is to be
687  *                                incremented
688  *
689  * RETURN:      None
690  *
691  * DESCRIPTION: Add one reference to an ACPI object
692  *
693  ******************************************************************************/
694 
695 void acpi_ut_add_reference(union acpi_operand_object *object)
696 {
697 
698 	ACPI_FUNCTION_NAME(ut_add_reference);
699 
700 	/* Ensure that we have a valid object */
701 
702 	if (!acpi_ut_valid_internal_object(object)) {
703 		return;
704 	}
705 
706 	ACPI_DEBUG_PRINT((ACPI_DB_ALLOCATIONS,
707 			  "Obj %p Current Refs=%X [To Be Incremented]\n",
708 			  object, object->common.reference_count));
709 
710 	/* Increment the reference count */
711 
712 	(void)acpi_ut_update_object_reference(object, REF_INCREMENT);
713 	return;
714 }
715 
716 /*******************************************************************************
717  *
718  * FUNCTION:    acpi_ut_remove_reference
719  *
720  * PARAMETERS:  object         - Object whose ref count will be decremented
721  *
722  * RETURN:      None
723  *
724  * DESCRIPTION: Decrement the reference count of an ACPI internal object
725  *
726  ******************************************************************************/
727 
728 void acpi_ut_remove_reference(union acpi_operand_object *object)
729 {
730 
731 	ACPI_FUNCTION_NAME(ut_remove_reference);
732 
733 	/*
734 	 * Allow a NULL pointer to be passed in, just ignore it. This saves
735 	 * each caller from having to check. Also, ignore NS nodes.
736 	 */
737 	if (!object ||
738 	    (ACPI_GET_DESCRIPTOR_TYPE(object) == ACPI_DESC_TYPE_NAMED)) {
739 		return;
740 	}
741 
742 	/* Ensure that we have a valid object */
743 
744 	if (!acpi_ut_valid_internal_object(object)) {
745 		return;
746 	}
747 
748 	ACPI_DEBUG_PRINT((ACPI_DB_ALLOCATIONS,
749 			  "Obj %p Current Refs=%X [To Be Decremented]\n",
750 			  object, object->common.reference_count));
751 
752 	/*
753 	 * Decrement the reference count, and only actually delete the object
754 	 * if the reference count becomes 0. (Must also decrement the ref count
755 	 * of all subobjects!)
756 	 */
757 	(void)acpi_ut_update_object_reference(object, REF_DECREMENT);
758 	return;
759 }
760