Merge branch 'for-2.6.26' of git://neil.brown.name/md
[linux-2.6] / drivers / acpi / dispatcher / dswstate.c
1 /******************************************************************************
2  *
3  * Module Name: dswstate - Dispatcher parse tree walk management routines
4  *
5  *****************************************************************************/
6
7 /*
8  * Copyright (C) 2000 - 2008, 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 <acpi/acparser.h>
46 #include <acpi/acdispat.h>
47 #include <acpi/acnamesp.h>
48
49 #define _COMPONENT          ACPI_DISPATCHER
50 ACPI_MODULE_NAME("dswstate")
51
52   /* Local prototypes */
53 static acpi_status acpi_ds_result_stack_push(struct acpi_walk_state *ws);
54 static acpi_status acpi_ds_result_stack_pop(struct acpi_walk_state *ws);
55
56 /*******************************************************************************
57  *
58  * FUNCTION:    acpi_ds_result_pop
59  *
60  * PARAMETERS:  Object              - Where to return the popped object
61  *              walk_state          - Current Walk state
62  *
63  * RETURN:      Status
64  *
65  * DESCRIPTION: Pop an object off the top of this walk's result stack
66  *
67  ******************************************************************************/
68
69 acpi_status
70 acpi_ds_result_pop(union acpi_operand_object **object,
71                    struct acpi_walk_state *walk_state)
72 {
73         acpi_native_uint index;
74         union acpi_generic_state *state;
75         acpi_status status;
76
77         ACPI_FUNCTION_NAME(ds_result_pop);
78
79         state = walk_state->results;
80
81         /* Incorrect state of result stack */
82
83         if (state && !walk_state->result_count) {
84                 ACPI_ERROR((AE_INFO, "No results on result stack"));
85                 return (AE_AML_INTERNAL);
86         }
87
88         if (!state && walk_state->result_count) {
89                 ACPI_ERROR((AE_INFO, "No result state for result stack"));
90                 return (AE_AML_INTERNAL);
91         }
92
93         /* Empty result stack */
94
95         if (!state) {
96                 ACPI_ERROR((AE_INFO, "Result stack is empty! State=%p",
97                             walk_state));
98                 return (AE_AML_NO_RETURN_VALUE);
99         }
100
101         /* Return object of the top element and clean that top element result stack */
102
103         walk_state->result_count--;
104         index = walk_state->result_count % ACPI_RESULTS_FRAME_OBJ_NUM;
105
106         *object = state->results.obj_desc[index];
107         if (!*object) {
108                 ACPI_ERROR((AE_INFO,
109                             "No result objects on result stack, State=%p",
110                             walk_state));
111                 return (AE_AML_NO_RETURN_VALUE);
112         }
113
114         state->results.obj_desc[index] = NULL;
115         if (index == 0) {
116                 status = acpi_ds_result_stack_pop(walk_state);
117                 if (ACPI_FAILURE(status)) {
118                         return (status);
119                 }
120         }
121
122         ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
123                           "Obj=%p [%s] Index=%X State=%p Num=%X\n", *object,
124                           acpi_ut_get_object_type_name(*object),
125                           (u32) index, walk_state, walk_state->result_count));
126
127         return (AE_OK);
128 }
129
130 /*******************************************************************************
131  *
132  * FUNCTION:    acpi_ds_result_push
133  *
134  * PARAMETERS:  Object              - Where to return the popped object
135  *              walk_state          - Current Walk state
136  *
137  * RETURN:      Status
138  *
139  * DESCRIPTION: Push an object onto the current result stack
140  *
141  ******************************************************************************/
142
143 acpi_status
144 acpi_ds_result_push(union acpi_operand_object * object,
145                     struct acpi_walk_state * walk_state)
146 {
147         union acpi_generic_state *state;
148         acpi_status status;
149         acpi_native_uint index;
150
151         ACPI_FUNCTION_NAME(ds_result_push);
152
153         if (walk_state->result_count > walk_state->result_size) {
154                 ACPI_ERROR((AE_INFO, "Result stack is full"));
155                 return (AE_AML_INTERNAL);
156         } else if (walk_state->result_count == walk_state->result_size) {
157
158                 /* Extend the result stack */
159
160                 status = acpi_ds_result_stack_push(walk_state);
161                 if (ACPI_FAILURE(status)) {
162                         ACPI_ERROR((AE_INFO,
163                                     "Failed to extend the result stack"));
164                         return (status);
165                 }
166         }
167
168         if (!(walk_state->result_count < walk_state->result_size)) {
169                 ACPI_ERROR((AE_INFO, "No free elements in result stack"));
170                 return (AE_AML_INTERNAL);
171         }
172
173         state = walk_state->results;
174         if (!state) {
175                 ACPI_ERROR((AE_INFO, "No result stack frame during push"));
176                 return (AE_AML_INTERNAL);
177         }
178
179         if (!object) {
180                 ACPI_ERROR((AE_INFO,
181                             "Null Object! Obj=%p State=%p Num=%X",
182                             object, walk_state, walk_state->result_count));
183                 return (AE_BAD_PARAMETER);
184         }
185
186         /* Assign the address of object to the top free element of result stack */
187
188         index = walk_state->result_count % ACPI_RESULTS_FRAME_OBJ_NUM;
189         state->results.obj_desc[index] = object;
190         walk_state->result_count++;
191
192         ACPI_DEBUG_PRINT((ACPI_DB_EXEC, "Obj=%p [%s] State=%p Num=%X Cur=%X\n",
193                           object,
194                           acpi_ut_get_object_type_name((union
195                                                         acpi_operand_object *)
196                                                        object), walk_state,
197                           walk_state->result_count,
198                           walk_state->current_result));
199
200         return (AE_OK);
201 }
202
203 /*******************************************************************************
204  *
205  * FUNCTION:    acpi_ds_result_stack_push
206  *
207  * PARAMETERS:  walk_state          - Current Walk state
208  *
209  * RETURN:      Status
210  *
211  * DESCRIPTION: Push an object onto the walk_state result stack
212  *
213  ******************************************************************************/
214
215 static acpi_status acpi_ds_result_stack_push(struct acpi_walk_state *walk_state)
216 {
217         union acpi_generic_state *state;
218
219         ACPI_FUNCTION_NAME(ds_result_stack_push);
220
221         /* Check for stack overflow */
222
223         if (((u32) walk_state->result_size + ACPI_RESULTS_FRAME_OBJ_NUM) >
224             ACPI_RESULTS_OBJ_NUM_MAX) {
225                 ACPI_ERROR((AE_INFO, "Result stack overflow: State=%p Num=%X",
226                             walk_state, walk_state->result_size));
227                 return (AE_STACK_OVERFLOW);
228         }
229
230         state = acpi_ut_create_generic_state();
231         if (!state) {
232                 return (AE_NO_MEMORY);
233         }
234
235         state->common.descriptor_type = ACPI_DESC_TYPE_STATE_RESULT;
236         acpi_ut_push_generic_state(&walk_state->results, state);
237
238         /* Increase the length of the result stack by the length of frame */
239
240         walk_state->result_size += ACPI_RESULTS_FRAME_OBJ_NUM;
241
242         ACPI_DEBUG_PRINT((ACPI_DB_EXEC, "Results=%p State=%p\n",
243                           state, walk_state));
244
245         return (AE_OK);
246 }
247
248 /*******************************************************************************
249  *
250  * FUNCTION:    acpi_ds_result_stack_pop
251  *
252  * PARAMETERS:  walk_state          - Current Walk state
253  *
254  * RETURN:      Status
255  *
256  * DESCRIPTION: Pop an object off of the walk_state result stack
257  *
258  ******************************************************************************/
259
260 static acpi_status acpi_ds_result_stack_pop(struct acpi_walk_state *walk_state)
261 {
262         union acpi_generic_state *state;
263
264         ACPI_FUNCTION_NAME(ds_result_stack_pop);
265
266         /* Check for stack underflow */
267
268         if (walk_state->results == NULL) {
269                 ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
270                                   "Result stack underflow - State=%p\n",
271                                   walk_state));
272                 return (AE_AML_NO_OPERAND);
273         }
274
275         if (walk_state->result_size < ACPI_RESULTS_FRAME_OBJ_NUM) {
276                 ACPI_ERROR((AE_INFO, "Insufficient result stack size"));
277                 return (AE_AML_INTERNAL);
278         }
279
280         state = acpi_ut_pop_generic_state(&walk_state->results);
281         acpi_ut_delete_generic_state(state);
282
283         /* Decrease the length of result stack by the length of frame */
284
285         walk_state->result_size -= ACPI_RESULTS_FRAME_OBJ_NUM;
286
287         ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
288                           "Result=%p RemainingResults=%X State=%p\n",
289                           state, walk_state->result_count, walk_state));
290
291         return (AE_OK);
292 }
293
294 /*******************************************************************************
295  *
296  * FUNCTION:    acpi_ds_obj_stack_push
297  *
298  * PARAMETERS:  Object              - Object to push
299  *              walk_state          - Current Walk state
300  *
301  * RETURN:      Status
302  *
303  * DESCRIPTION: Push an object onto this walk's object/operand stack
304  *
305  ******************************************************************************/
306
307 acpi_status
308 acpi_ds_obj_stack_push(void *object, struct acpi_walk_state * walk_state)
309 {
310         ACPI_FUNCTION_NAME(ds_obj_stack_push);
311
312         /* Check for stack overflow */
313
314         if (walk_state->num_operands >= ACPI_OBJ_NUM_OPERANDS) {
315                 ACPI_ERROR((AE_INFO,
316                             "Object stack overflow! Obj=%p State=%p #Ops=%X",
317                             object, walk_state, walk_state->num_operands));
318                 return (AE_STACK_OVERFLOW);
319         }
320
321         /* Put the object onto the stack */
322
323         walk_state->operands[walk_state->operand_index] = object;
324         walk_state->num_operands++;
325
326         /* For the usual order of filling the operand stack */
327
328         walk_state->operand_index++;
329
330         ACPI_DEBUG_PRINT((ACPI_DB_EXEC, "Obj=%p [%s] State=%p #Ops=%X\n",
331                           object,
332                           acpi_ut_get_object_type_name((union
333                                                         acpi_operand_object *)
334                                                        object), walk_state,
335                           walk_state->num_operands));
336
337         return (AE_OK);
338 }
339
340 /*******************************************************************************
341  *
342  * FUNCTION:    acpi_ds_obj_stack_pop
343  *
344  * PARAMETERS:  pop_count           - Number of objects/entries to pop
345  *              walk_state          - Current Walk state
346  *
347  * RETURN:      Status
348  *
349  * DESCRIPTION: Pop this walk's object stack.  Objects on the stack are NOT
350  *              deleted by this routine.
351  *
352  ******************************************************************************/
353
354 acpi_status
355 acpi_ds_obj_stack_pop(u32 pop_count, struct acpi_walk_state * walk_state)
356 {
357         u32 i;
358
359         ACPI_FUNCTION_NAME(ds_obj_stack_pop);
360
361         for (i = 0; i < pop_count; i++) {
362
363                 /* Check for stack underflow */
364
365                 if (walk_state->num_operands == 0) {
366                         ACPI_ERROR((AE_INFO,
367                                     "Object stack underflow! Count=%X State=%p #Ops=%X",
368                                     pop_count, walk_state,
369                                     walk_state->num_operands));
370                         return (AE_STACK_UNDERFLOW);
371                 }
372
373                 /* Just set the stack entry to null */
374
375                 walk_state->num_operands--;
376                 walk_state->operands[walk_state->num_operands] = NULL;
377         }
378
379         ACPI_DEBUG_PRINT((ACPI_DB_EXEC, "Count=%X State=%p #Ops=%X\n",
380                           pop_count, walk_state, walk_state->num_operands));
381
382         return (AE_OK);
383 }
384
385 /*******************************************************************************
386  *
387  * FUNCTION:    acpi_ds_obj_stack_pop_and_delete
388  *
389  * PARAMETERS:  pop_count           - Number of objects/entries to pop
390  *              walk_state          - Current Walk state
391  *
392  * RETURN:      Status
393  *
394  * DESCRIPTION: Pop this walk's object stack and delete each object that is
395  *              popped off.
396  *
397  ******************************************************************************/
398
399 void
400 acpi_ds_obj_stack_pop_and_delete(u32 pop_count,
401                                  struct acpi_walk_state *walk_state)
402 {
403         acpi_native_int i;
404         union acpi_operand_object *obj_desc;
405
406         ACPI_FUNCTION_NAME(ds_obj_stack_pop_and_delete);
407
408         if (pop_count == 0) {
409                 return;
410         }
411
412         for (i = (acpi_native_int) (pop_count - 1); i >= 0; i--) {
413                 if (walk_state->num_operands == 0) {
414                         return;
415                 }
416
417                 /* Pop the stack and delete an object if present in this stack entry */
418
419                 walk_state->num_operands--;
420                 obj_desc = walk_state->operands[i];
421                 if (obj_desc) {
422                         acpi_ut_remove_reference(walk_state->operands[i]);
423                         walk_state->operands[i] = NULL;
424                 }
425         }
426
427         ACPI_DEBUG_PRINT((ACPI_DB_EXEC, "Count=%X State=%p #Ops=%X\n",
428                           pop_count, walk_state, walk_state->num_operands));
429 }
430
431 /*******************************************************************************
432  *
433  * FUNCTION:    acpi_ds_get_current_walk_state
434  *
435  * PARAMETERS:  Thread          - Get current active state for this Thread
436  *
437  * RETURN:      Pointer to the current walk state
438  *
439  * DESCRIPTION: Get the walk state that is at the head of the list (the "current"
440  *              walk state.)
441  *
442  ******************************************************************************/
443
444 struct acpi_walk_state *acpi_ds_get_current_walk_state(struct acpi_thread_state
445                                                        *thread)
446 {
447         ACPI_FUNCTION_NAME(ds_get_current_walk_state);
448
449         if (!thread) {
450                 return (NULL);
451         }
452
453         ACPI_DEBUG_PRINT((ACPI_DB_PARSE, "Current WalkState %p\n",
454                           thread->walk_state_list));
455
456         return (thread->walk_state_list);
457 }
458
459 /*******************************************************************************
460  *
461  * FUNCTION:    acpi_ds_push_walk_state
462  *
463  * PARAMETERS:  walk_state      - State to push
464  *              Thread          - Thread state object
465  *
466  * RETURN:      None
467  *
468  * DESCRIPTION: Place the Thread state at the head of the state list
469  *
470  ******************************************************************************/
471
472 void
473 acpi_ds_push_walk_state(struct acpi_walk_state *walk_state,
474                         struct acpi_thread_state *thread)
475 {
476         ACPI_FUNCTION_TRACE(ds_push_walk_state);
477
478         walk_state->next = thread->walk_state_list;
479         thread->walk_state_list = walk_state;
480
481         return_VOID;
482 }
483
484 /*******************************************************************************
485  *
486  * FUNCTION:    acpi_ds_pop_walk_state
487  *
488  * PARAMETERS:  Thread      - Current thread state
489  *
490  * RETURN:      A walk_state object popped from the thread's stack
491  *
492  * DESCRIPTION: Remove and return the walkstate object that is at the head of
493  *              the walk stack for the given walk list.  NULL indicates that
494  *              the list is empty.
495  *
496  ******************************************************************************/
497
498 struct acpi_walk_state *acpi_ds_pop_walk_state(struct acpi_thread_state *thread)
499 {
500         struct acpi_walk_state *walk_state;
501
502         ACPI_FUNCTION_TRACE(ds_pop_walk_state);
503
504         walk_state = thread->walk_state_list;
505
506         if (walk_state) {
507
508                 /* Next walk state becomes the current walk state */
509
510                 thread->walk_state_list = walk_state->next;
511
512                 /*
513                  * Don't clear the NEXT field, this serves as an indicator
514                  * that there is a parent WALK STATE
515                  * Do Not: walk_state->Next = NULL;
516                  */
517         }
518
519         return_PTR(walk_state);
520 }
521
522 /*******************************************************************************
523  *
524  * FUNCTION:    acpi_ds_create_walk_state
525  *
526  * PARAMETERS:  owner_id        - ID for object creation
527  *              Origin          - Starting point for this walk
528  *              method_desc     - Method object
529  *              Thread          - Current thread state
530  *
531  * RETURN:      Pointer to the new walk state.
532  *
533  * DESCRIPTION: Allocate and initialize a new walk state.  The current walk
534  *              state is set to this new state.
535  *
536  ******************************************************************************/
537
538 struct acpi_walk_state *acpi_ds_create_walk_state(acpi_owner_id owner_id, union acpi_parse_object
539                                                   *origin, union acpi_operand_object
540                                                   *method_desc, struct acpi_thread_state
541                                                   *thread)
542 {
543         struct acpi_walk_state *walk_state;
544
545         ACPI_FUNCTION_TRACE(ds_create_walk_state);
546
547         walk_state = ACPI_ALLOCATE_ZEROED(sizeof(struct acpi_walk_state));
548         if (!walk_state) {
549                 return_PTR(NULL);
550         }
551
552         walk_state->descriptor_type = ACPI_DESC_TYPE_WALK;
553         walk_state->method_desc = method_desc;
554         walk_state->owner_id = owner_id;
555         walk_state->origin = origin;
556         walk_state->thread = thread;
557
558         walk_state->parser_state.start_op = origin;
559
560         /* Init the method args/local */
561
562 #if (!defined (ACPI_NO_METHOD_EXECUTION) && !defined (ACPI_CONSTANT_EVAL_ONLY))
563         acpi_ds_method_data_init(walk_state);
564 #endif
565
566         /* Put the new state at the head of the walk list */
567
568         if (thread) {
569                 acpi_ds_push_walk_state(walk_state, thread);
570         }
571
572         return_PTR(walk_state);
573 }
574
575 /*******************************************************************************
576  *
577  * FUNCTION:    acpi_ds_init_aml_walk
578  *
579  * PARAMETERS:  walk_state      - New state to be initialized
580  *              Op              - Current parse op
581  *              method_node     - Control method NS node, if any
582  *              aml_start       - Start of AML
583  *              aml_length      - Length of AML
584  *              Info            - Method info block (params, etc.)
585  *              pass_number     - 1, 2, or 3
586  *
587  * RETURN:      Status
588  *
589  * DESCRIPTION: Initialize a walk state for a pass 1 or 2 parse tree walk
590  *
591  ******************************************************************************/
592
593 acpi_status
594 acpi_ds_init_aml_walk(struct acpi_walk_state *walk_state,
595                       union acpi_parse_object *op,
596                       struct acpi_namespace_node *method_node,
597                       u8 * aml_start,
598                       u32 aml_length,
599                       struct acpi_evaluate_info *info, u8 pass_number)
600 {
601         acpi_status status;
602         struct acpi_parse_state *parser_state = &walk_state->parser_state;
603         union acpi_parse_object *extra_op;
604
605         ACPI_FUNCTION_TRACE(ds_init_aml_walk);
606
607         walk_state->parser_state.aml =
608             walk_state->parser_state.aml_start = aml_start;
609         walk_state->parser_state.aml_end =
610             walk_state->parser_state.pkg_end = aml_start + aml_length;
611
612         /* The next_op of the next_walk will be the beginning of the method */
613
614         walk_state->next_op = NULL;
615         walk_state->pass_number = pass_number;
616
617         if (info) {
618                 if (info->parameter_type == ACPI_PARAM_GPE) {
619                         walk_state->gpe_event_info =
620                             ACPI_CAST_PTR(struct acpi_gpe_event_info,
621                                           info->parameters);
622                 } else {
623                         walk_state->params = info->parameters;
624                         walk_state->caller_return_desc = &info->return_object;
625                 }
626         }
627
628         status = acpi_ps_init_scope(&walk_state->parser_state, op);
629         if (ACPI_FAILURE(status)) {
630                 return_ACPI_STATUS(status);
631         }
632
633         if (method_node) {
634                 walk_state->parser_state.start_node = method_node;
635                 walk_state->walk_type = ACPI_WALK_METHOD;
636                 walk_state->method_node = method_node;
637                 walk_state->method_desc =
638                     acpi_ns_get_attached_object(method_node);
639
640                 /* Push start scope on scope stack and make it current  */
641
642                 status =
643                     acpi_ds_scope_stack_push(method_node, ACPI_TYPE_METHOD,
644                                              walk_state);
645                 if (ACPI_FAILURE(status)) {
646                         return_ACPI_STATUS(status);
647                 }
648
649                 /* Init the method arguments */
650
651                 status = acpi_ds_method_data_init_args(walk_state->params,
652                                                        ACPI_METHOD_NUM_ARGS,
653                                                        walk_state);
654                 if (ACPI_FAILURE(status)) {
655                         return_ACPI_STATUS(status);
656                 }
657         } else {
658                 /*
659                  * Setup the current scope.
660                  * Find a Named Op that has a namespace node associated with it.
661                  * search upwards from this Op.  Current scope is the first
662                  * Op with a namespace node.
663                  */
664                 extra_op = parser_state->start_op;
665                 while (extra_op && !extra_op->common.node) {
666                         extra_op = extra_op->common.parent;
667                 }
668
669                 if (!extra_op) {
670                         parser_state->start_node = NULL;
671                 } else {
672                         parser_state->start_node = extra_op->common.node;
673                 }
674
675                 if (parser_state->start_node) {
676
677                         /* Push start scope on scope stack and make it current  */
678
679                         status =
680                             acpi_ds_scope_stack_push(parser_state->start_node,
681                                                      parser_state->start_node->
682                                                      type, walk_state);
683                         if (ACPI_FAILURE(status)) {
684                                 return_ACPI_STATUS(status);
685                         }
686                 }
687         }
688
689         status = acpi_ds_init_callbacks(walk_state, pass_number);
690         return_ACPI_STATUS(status);
691 }
692
693 /*******************************************************************************
694  *
695  * FUNCTION:    acpi_ds_delete_walk_state
696  *
697  * PARAMETERS:  walk_state      - State to delete
698  *
699  * RETURN:      Status
700  *
701  * DESCRIPTION: Delete a walk state including all internal data structures
702  *
703  ******************************************************************************/
704
705 void acpi_ds_delete_walk_state(struct acpi_walk_state *walk_state)
706 {
707         union acpi_generic_state *state;
708
709         ACPI_FUNCTION_TRACE_PTR(ds_delete_walk_state, walk_state);
710
711         if (!walk_state) {
712                 return;
713         }
714
715         if (walk_state->descriptor_type != ACPI_DESC_TYPE_WALK) {
716                 ACPI_ERROR((AE_INFO, "%p is not a valid walk state",
717                             walk_state));
718                 return;
719         }
720
721         /* There should not be any open scopes */
722
723         if (walk_state->parser_state.scope) {
724                 ACPI_ERROR((AE_INFO, "%p walk still has a scope list",
725                             walk_state));
726                 acpi_ps_cleanup_scope(&walk_state->parser_state);
727         }
728
729         /* Always must free any linked control states */
730
731         while (walk_state->control_state) {
732                 state = walk_state->control_state;
733                 walk_state->control_state = state->common.next;
734
735                 acpi_ut_delete_generic_state(state);
736         }
737
738         /* Always must free any linked parse states */
739
740         while (walk_state->scope_info) {
741                 state = walk_state->scope_info;
742                 walk_state->scope_info = state->common.next;
743
744                 acpi_ut_delete_generic_state(state);
745         }
746
747         /* Always must free any stacked result states */
748
749         while (walk_state->results) {
750                 state = walk_state->results;
751                 walk_state->results = state->common.next;
752
753                 acpi_ut_delete_generic_state(state);
754         }
755
756         ACPI_FREE(walk_state);
757         return_VOID;
758 }