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1 /******************************************************************************
2  *
3  * Module Name: dsmethod - Parser/Interpreter interface - control method parsing
4  *
5  *****************************************************************************/
6 
7 /*
8  * Copyright (C) 2000 - 2014, 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 "acdispat.h"
47 #include "acinterp.h"
48 #include "acnamesp.h"
49 #ifdef	ACPI_DISASSEMBLER
50 #include "acdisasm.h"
51 #endif
52 #include "acparser.h"
53 #include "amlcode.h"
54 
55 #define _COMPONENT          ACPI_DISPATCHER
56 ACPI_MODULE_NAME("dsmethod")
57 
58 /* Local prototypes */
59 static acpi_status
60 acpi_ds_detect_named_opcodes(struct acpi_walk_state *walk_state,
61 			     union acpi_parse_object **out_op);
62 
63 static acpi_status
64 acpi_ds_create_method_mutex(union acpi_operand_object *method_desc);
65 
66 /*******************************************************************************
67  *
68  * FUNCTION:    acpi_ds_auto_serialize_method
69  *
70  * PARAMETERS:  node                        - Namespace Node of the method
71  *              obj_desc                    - Method object attached to node
72  *
73  * RETURN:      Status
74  *
75  * DESCRIPTION: Parse a control method AML to scan for control methods that
76  *              need serialization due to the creation of named objects.
77  *
78  * NOTE: It is a bit of overkill to mark all such methods serialized, since
79  * there is only a problem if the method actually blocks during execution.
80  * A blocking operation is, for example, a Sleep() operation, or any access
81  * to an operation region. However, it is probably not possible to easily
82  * detect whether a method will block or not, so we simply mark all suspicious
83  * methods as serialized.
84  *
85  * NOTE2: This code is essentially a generic routine for parsing a single
86  * control method.
87  *
88  ******************************************************************************/
89 
90 acpi_status
acpi_ds_auto_serialize_method(struct acpi_namespace_node * node,union acpi_operand_object * obj_desc)91 acpi_ds_auto_serialize_method(struct acpi_namespace_node *node,
92 			      union acpi_operand_object *obj_desc)
93 {
94 	acpi_status status;
95 	union acpi_parse_object *op = NULL;
96 	struct acpi_walk_state *walk_state;
97 
98 	ACPI_FUNCTION_TRACE_PTR(ds_auto_serialize_method, node);
99 
100 	ACPI_DEBUG_PRINT((ACPI_DB_PARSE,
101 			  "Method auto-serialization parse [%4.4s] %p\n",
102 			  acpi_ut_get_node_name(node), node));
103 
104 	/* Create/Init a root op for the method parse tree */
105 
106 	op = acpi_ps_alloc_op(AML_METHOD_OP);
107 	if (!op) {
108 		return_ACPI_STATUS(AE_NO_MEMORY);
109 	}
110 
111 	acpi_ps_set_name(op, node->name.integer);
112 	op->common.node = node;
113 
114 	/* Create and initialize a new walk state */
115 
116 	walk_state =
117 	    acpi_ds_create_walk_state(node->owner_id, NULL, NULL, NULL);
118 	if (!walk_state) {
119 		return_ACPI_STATUS(AE_NO_MEMORY);
120 	}
121 
122 	status =
123 	    acpi_ds_init_aml_walk(walk_state, op, node,
124 				  obj_desc->method.aml_start,
125 				  obj_desc->method.aml_length, NULL, 0);
126 	if (ACPI_FAILURE(status)) {
127 		acpi_ds_delete_walk_state(walk_state);
128 		return_ACPI_STATUS(status);
129 	}
130 
131 	walk_state->descending_callback = acpi_ds_detect_named_opcodes;
132 
133 	/* Parse the method, scan for creation of named objects */
134 
135 	status = acpi_ps_parse_aml(walk_state);
136 	if (ACPI_FAILURE(status)) {
137 		return_ACPI_STATUS(status);
138 	}
139 
140 	acpi_ps_delete_parse_tree(op);
141 	return_ACPI_STATUS(status);
142 }
143 
144 /*******************************************************************************
145  *
146  * FUNCTION:    acpi_ds_detect_named_opcodes
147  *
148  * PARAMETERS:  walk_state      - Current state of the parse tree walk
149  *              out_op          - Unused, required for parser interface
150  *
151  * RETURN:      Status
152  *
153  * DESCRIPTION: Descending callback used during the loading of ACPI tables.
154  *              Currently used to detect methods that must be marked serialized
155  *              in order to avoid problems with the creation of named objects.
156  *
157  ******************************************************************************/
158 
159 static acpi_status
acpi_ds_detect_named_opcodes(struct acpi_walk_state * walk_state,union acpi_parse_object ** out_op)160 acpi_ds_detect_named_opcodes(struct acpi_walk_state *walk_state,
161 			     union acpi_parse_object **out_op)
162 {
163 
164 	ACPI_FUNCTION_NAME(acpi_ds_detect_named_opcodes);
165 
166 	/* We are only interested in opcodes that create a new name */
167 
168 	if (!
169 	    (walk_state->op_info->
170 	     flags & (AML_NAMED | AML_CREATE | AML_FIELD))) {
171 		return (AE_OK);
172 	}
173 
174 	/*
175 	 * At this point, we know we have a Named object opcode.
176 	 * Mark the method as serialized. Later code will create a mutex for
177 	 * this method to enforce serialization.
178 	 *
179 	 * Note, ACPI_METHOD_IGNORE_SYNC_LEVEL flag means that we will ignore the
180 	 * Sync Level mechanism for this method, even though it is now serialized.
181 	 * Otherwise, there can be conflicts with existing ASL code that actually
182 	 * uses sync levels.
183 	 */
184 	walk_state->method_desc->method.sync_level = 0;
185 	walk_state->method_desc->method.info_flags |=
186 	    (ACPI_METHOD_SERIALIZED | ACPI_METHOD_IGNORE_SYNC_LEVEL);
187 
188 	ACPI_DEBUG_PRINT((ACPI_DB_INFO,
189 			  "Method serialized [%4.4s] %p - [%s] (%4.4X)\n",
190 			  walk_state->method_node->name.ascii,
191 			  walk_state->method_node, walk_state->op_info->name,
192 			  walk_state->opcode));
193 
194 	/* Abort the parse, no need to examine this method any further */
195 
196 	return (AE_CTRL_TERMINATE);
197 }
198 
199 /*******************************************************************************
200  *
201  * FUNCTION:    acpi_ds_method_error
202  *
203  * PARAMETERS:  status          - Execution status
204  *              walk_state      - Current state
205  *
206  * RETURN:      Status
207  *
208  * DESCRIPTION: Called on method error. Invoke the global exception handler if
209  *              present, dump the method data if the disassembler is configured
210  *
211  *              Note: Allows the exception handler to change the status code
212  *
213  ******************************************************************************/
214 
215 acpi_status
acpi_ds_method_error(acpi_status status,struct acpi_walk_state * walk_state)216 acpi_ds_method_error(acpi_status status, struct acpi_walk_state * walk_state)
217 {
218 	ACPI_FUNCTION_ENTRY();
219 
220 	/* Ignore AE_OK and control exception codes */
221 
222 	if (ACPI_SUCCESS(status) || (status & AE_CODE_CONTROL)) {
223 		return (status);
224 	}
225 
226 	/* Invoke the global exception handler */
227 
228 	if (acpi_gbl_exception_handler) {
229 
230 		/* Exit the interpreter, allow handler to execute methods */
231 
232 		acpi_ex_exit_interpreter();
233 
234 		/*
235 		 * Handler can map the exception code to anything it wants, including
236 		 * AE_OK, in which case the executing method will not be aborted.
237 		 */
238 		status = acpi_gbl_exception_handler(status,
239 						    walk_state->method_node ?
240 						    walk_state->method_node->
241 						    name.integer : 0,
242 						    walk_state->opcode,
243 						    walk_state->aml_offset,
244 						    NULL);
245 		acpi_ex_enter_interpreter();
246 	}
247 
248 	acpi_ds_clear_implicit_return(walk_state);
249 
250 #ifdef ACPI_DISASSEMBLER
251 	if (ACPI_FAILURE(status)) {
252 
253 		/* Display method locals/args if disassembler is present */
254 
255 		acpi_dm_dump_method_info(status, walk_state, walk_state->op);
256 	}
257 #endif
258 
259 	return (status);
260 }
261 
262 /*******************************************************************************
263  *
264  * FUNCTION:    acpi_ds_create_method_mutex
265  *
266  * PARAMETERS:  obj_desc            - The method object
267  *
268  * RETURN:      Status
269  *
270  * DESCRIPTION: Create a mutex object for a serialized control method
271  *
272  ******************************************************************************/
273 
274 static acpi_status
acpi_ds_create_method_mutex(union acpi_operand_object * method_desc)275 acpi_ds_create_method_mutex(union acpi_operand_object *method_desc)
276 {
277 	union acpi_operand_object *mutex_desc;
278 	acpi_status status;
279 
280 	ACPI_FUNCTION_TRACE(ds_create_method_mutex);
281 
282 	/* Create the new mutex object */
283 
284 	mutex_desc = acpi_ut_create_internal_object(ACPI_TYPE_MUTEX);
285 	if (!mutex_desc) {
286 		return_ACPI_STATUS(AE_NO_MEMORY);
287 	}
288 
289 	/* Create the actual OS Mutex */
290 
291 	status = acpi_os_create_mutex(&mutex_desc->mutex.os_mutex);
292 	if (ACPI_FAILURE(status)) {
293 		acpi_ut_delete_object_desc(mutex_desc);
294 		return_ACPI_STATUS(status);
295 	}
296 
297 	mutex_desc->mutex.sync_level = method_desc->method.sync_level;
298 	method_desc->method.mutex = mutex_desc;
299 	return_ACPI_STATUS(AE_OK);
300 }
301 
302 /*******************************************************************************
303  *
304  * FUNCTION:    acpi_ds_begin_method_execution
305  *
306  * PARAMETERS:  method_node         - Node of the method
307  *              obj_desc            - The method object
308  *              walk_state          - current state, NULL if not yet executing
309  *                                    a method.
310  *
311  * RETURN:      Status
312  *
313  * DESCRIPTION: Prepare a method for execution. Parses the method if necessary,
314  *              increments the thread count, and waits at the method semaphore
315  *              for clearance to execute.
316  *
317  ******************************************************************************/
318 
319 acpi_status
acpi_ds_begin_method_execution(struct acpi_namespace_node * method_node,union acpi_operand_object * obj_desc,struct acpi_walk_state * walk_state)320 acpi_ds_begin_method_execution(struct acpi_namespace_node *method_node,
321 			       union acpi_operand_object *obj_desc,
322 			       struct acpi_walk_state *walk_state)
323 {
324 	acpi_status status = AE_OK;
325 
326 	ACPI_FUNCTION_TRACE_PTR(ds_begin_method_execution, method_node);
327 
328 	if (!method_node) {
329 		return_ACPI_STATUS(AE_NULL_ENTRY);
330 	}
331 
332 	/* Prevent wraparound of thread count */
333 
334 	if (obj_desc->method.thread_count == ACPI_UINT8_MAX) {
335 		ACPI_ERROR((AE_INFO,
336 			    "Method reached maximum reentrancy limit (255)"));
337 		return_ACPI_STATUS(AE_AML_METHOD_LIMIT);
338 	}
339 
340 	/*
341 	 * If this method is serialized, we need to acquire the method mutex.
342 	 */
343 	if (obj_desc->method.info_flags & ACPI_METHOD_SERIALIZED) {
344 		/*
345 		 * Create a mutex for the method if it is defined to be Serialized
346 		 * and a mutex has not already been created. We defer the mutex creation
347 		 * until a method is actually executed, to minimize the object count
348 		 */
349 		if (!obj_desc->method.mutex) {
350 			status = acpi_ds_create_method_mutex(obj_desc);
351 			if (ACPI_FAILURE(status)) {
352 				return_ACPI_STATUS(status);
353 			}
354 		}
355 
356 		/*
357 		 * The current_sync_level (per-thread) must be less than or equal to
358 		 * the sync level of the method. This mechanism provides some
359 		 * deadlock prevention.
360 		 *
361 		 * If the method was auto-serialized, we just ignore the sync level
362 		 * mechanism, because auto-serialization of methods can interfere
363 		 * with ASL code that actually uses sync levels.
364 		 *
365 		 * Top-level method invocation has no walk state at this point
366 		 */
367 		if (walk_state &&
368 		    (!(obj_desc->method.
369 		       info_flags & ACPI_METHOD_IGNORE_SYNC_LEVEL))
370 		    && (walk_state->thread->current_sync_level >
371 			obj_desc->method.mutex->mutex.sync_level)) {
372 			ACPI_ERROR((AE_INFO,
373 				    "Cannot acquire Mutex for method [%4.4s], current SyncLevel is too large (%u)",
374 				    acpi_ut_get_node_name(method_node),
375 				    walk_state->thread->current_sync_level));
376 
377 			return_ACPI_STATUS(AE_AML_MUTEX_ORDER);
378 		}
379 
380 		/*
381 		 * Obtain the method mutex if necessary. Do not acquire mutex for a
382 		 * recursive call.
383 		 */
384 		if (!walk_state ||
385 		    !obj_desc->method.mutex->mutex.thread_id ||
386 		    (walk_state->thread->thread_id !=
387 		     obj_desc->method.mutex->mutex.thread_id)) {
388 			/*
389 			 * Acquire the method mutex. This releases the interpreter if we
390 			 * block (and reacquires it before it returns)
391 			 */
392 			status =
393 			    acpi_ex_system_wait_mutex(obj_desc->method.mutex->
394 						      mutex.os_mutex,
395 						      ACPI_WAIT_FOREVER);
396 			if (ACPI_FAILURE(status)) {
397 				return_ACPI_STATUS(status);
398 			}
399 
400 			/* Update the mutex and walk info and save the original sync_level */
401 
402 			if (walk_state) {
403 				obj_desc->method.mutex->mutex.
404 				    original_sync_level =
405 				    walk_state->thread->current_sync_level;
406 
407 				obj_desc->method.mutex->mutex.thread_id =
408 				    walk_state->thread->thread_id;
409 				walk_state->thread->current_sync_level =
410 				    obj_desc->method.sync_level;
411 			} else {
412 				obj_desc->method.mutex->mutex.
413 				    original_sync_level =
414 				    obj_desc->method.mutex->mutex.sync_level;
415 
416 				obj_desc->method.mutex->mutex.thread_id =
417 				    acpi_os_get_thread_id();
418 			}
419 		}
420 
421 		/* Always increase acquisition depth */
422 
423 		obj_desc->method.mutex->mutex.acquisition_depth++;
424 	}
425 
426 	/*
427 	 * Allocate an Owner ID for this method, only if this is the first thread
428 	 * to begin concurrent execution. We only need one owner_id, even if the
429 	 * method is invoked recursively.
430 	 */
431 	if (!obj_desc->method.owner_id) {
432 		status = acpi_ut_allocate_owner_id(&obj_desc->method.owner_id);
433 		if (ACPI_FAILURE(status)) {
434 			goto cleanup;
435 		}
436 	}
437 
438 	/*
439 	 * Increment the method parse tree thread count since it has been
440 	 * reentered one more time (even if it is the same thread)
441 	 */
442 	obj_desc->method.thread_count++;
443 	acpi_method_count++;
444 	return_ACPI_STATUS(status);
445 
446 cleanup:
447 	/* On error, must release the method mutex (if present) */
448 
449 	if (obj_desc->method.mutex) {
450 		acpi_os_release_mutex(obj_desc->method.mutex->mutex.os_mutex);
451 	}
452 	return_ACPI_STATUS(status);
453 }
454 
455 /*******************************************************************************
456  *
457  * FUNCTION:    acpi_ds_call_control_method
458  *
459  * PARAMETERS:  thread              - Info for this thread
460  *              this_walk_state     - Current walk state
461  *              op                  - Current Op to be walked
462  *
463  * RETURN:      Status
464  *
465  * DESCRIPTION: Transfer execution to a called control method
466  *
467  ******************************************************************************/
468 
469 acpi_status
acpi_ds_call_control_method(struct acpi_thread_state * thread,struct acpi_walk_state * this_walk_state,union acpi_parse_object * op)470 acpi_ds_call_control_method(struct acpi_thread_state *thread,
471 			    struct acpi_walk_state *this_walk_state,
472 			    union acpi_parse_object *op)
473 {
474 	acpi_status status;
475 	struct acpi_namespace_node *method_node;
476 	struct acpi_walk_state *next_walk_state = NULL;
477 	union acpi_operand_object *obj_desc;
478 	struct acpi_evaluate_info *info;
479 	u32 i;
480 
481 	ACPI_FUNCTION_TRACE_PTR(ds_call_control_method, this_walk_state);
482 
483 	ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
484 			  "Calling method %p, currentstate=%p\n",
485 			  this_walk_state->prev_op, this_walk_state));
486 
487 	/*
488 	 * Get the namespace entry for the control method we are about to call
489 	 */
490 	method_node = this_walk_state->method_call_node;
491 	if (!method_node) {
492 		return_ACPI_STATUS(AE_NULL_ENTRY);
493 	}
494 
495 	obj_desc = acpi_ns_get_attached_object(method_node);
496 	if (!obj_desc) {
497 		return_ACPI_STATUS(AE_NULL_OBJECT);
498 	}
499 
500 	/* Init for new method, possibly wait on method mutex */
501 
502 	status = acpi_ds_begin_method_execution(method_node, obj_desc,
503 						this_walk_state);
504 	if (ACPI_FAILURE(status)) {
505 		return_ACPI_STATUS(status);
506 	}
507 
508 	/* Begin method parse/execution. Create a new walk state */
509 
510 	next_walk_state = acpi_ds_create_walk_state(obj_desc->method.owner_id,
511 						    NULL, obj_desc, thread);
512 	if (!next_walk_state) {
513 		status = AE_NO_MEMORY;
514 		goto cleanup;
515 	}
516 
517 	/*
518 	 * The resolved arguments were put on the previous walk state's operand
519 	 * stack. Operands on the previous walk state stack always
520 	 * start at index 0. Also, null terminate the list of arguments
521 	 */
522 	this_walk_state->operands[this_walk_state->num_operands] = NULL;
523 
524 	/*
525 	 * Allocate and initialize the evaluation information block
526 	 * TBD: this is somewhat inefficient, should change interface to
527 	 * ds_init_aml_walk. For now, keeps this struct off the CPU stack
528 	 */
529 	info = ACPI_ALLOCATE_ZEROED(sizeof(struct acpi_evaluate_info));
530 	if (!info) {
531 		status = AE_NO_MEMORY;
532 		goto cleanup;
533 	}
534 
535 	info->parameters = &this_walk_state->operands[0];
536 
537 	status = acpi_ds_init_aml_walk(next_walk_state, NULL, method_node,
538 				       obj_desc->method.aml_start,
539 				       obj_desc->method.aml_length, info,
540 				       ACPI_IMODE_EXECUTE);
541 
542 	ACPI_FREE(info);
543 	if (ACPI_FAILURE(status)) {
544 		goto cleanup;
545 	}
546 
547 	/*
548 	 * Delete the operands on the previous walkstate operand stack
549 	 * (they were copied to new objects)
550 	 */
551 	for (i = 0; i < obj_desc->method.param_count; i++) {
552 		acpi_ut_remove_reference(this_walk_state->operands[i]);
553 		this_walk_state->operands[i] = NULL;
554 	}
555 
556 	/* Clear the operand stack */
557 
558 	this_walk_state->num_operands = 0;
559 
560 	ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
561 			  "**** Begin nested execution of [%4.4s] **** WalkState=%p\n",
562 			  method_node->name.ascii, next_walk_state));
563 
564 	/* Invoke an internal method if necessary */
565 
566 	if (obj_desc->method.info_flags & ACPI_METHOD_INTERNAL_ONLY) {
567 		status =
568 		    obj_desc->method.dispatch.implementation(next_walk_state);
569 		if (status == AE_OK) {
570 			status = AE_CTRL_TERMINATE;
571 		}
572 	}
573 
574 	return_ACPI_STATUS(status);
575 
576 cleanup:
577 
578 	/* On error, we must terminate the method properly */
579 
580 	acpi_ds_terminate_control_method(obj_desc, next_walk_state);
581 	if (next_walk_state) {
582 		acpi_ds_delete_walk_state(next_walk_state);
583 	}
584 
585 	return_ACPI_STATUS(status);
586 }
587 
588 /*******************************************************************************
589  *
590  * FUNCTION:    acpi_ds_restart_control_method
591  *
592  * PARAMETERS:  walk_state          - State for preempted method (caller)
593  *              return_desc         - Return value from the called method
594  *
595  * RETURN:      Status
596  *
597  * DESCRIPTION: Restart a method that was preempted by another (nested) method
598  *              invocation. Handle the return value (if any) from the callee.
599  *
600  ******************************************************************************/
601 
602 acpi_status
acpi_ds_restart_control_method(struct acpi_walk_state * walk_state,union acpi_operand_object * return_desc)603 acpi_ds_restart_control_method(struct acpi_walk_state *walk_state,
604 			       union acpi_operand_object *return_desc)
605 {
606 	acpi_status status;
607 	int same_as_implicit_return;
608 
609 	ACPI_FUNCTION_TRACE_PTR(ds_restart_control_method, walk_state);
610 
611 	ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
612 			  "****Restart [%4.4s] Op %p ReturnValueFromCallee %p\n",
613 			  acpi_ut_get_node_name(walk_state->method_node),
614 			  walk_state->method_call_op, return_desc));
615 
616 	ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
617 			  "    ReturnFromThisMethodUsed?=%X ResStack %p Walk %p\n",
618 			  walk_state->return_used,
619 			  walk_state->results, walk_state));
620 
621 	/* Did the called method return a value? */
622 
623 	if (return_desc) {
624 
625 		/* Is the implicit return object the same as the return desc? */
626 
627 		same_as_implicit_return =
628 		    (walk_state->implicit_return_obj == return_desc);
629 
630 		/* Are we actually going to use the return value? */
631 
632 		if (walk_state->return_used) {
633 
634 			/* Save the return value from the previous method */
635 
636 			status = acpi_ds_result_push(return_desc, walk_state);
637 			if (ACPI_FAILURE(status)) {
638 				acpi_ut_remove_reference(return_desc);
639 				return_ACPI_STATUS(status);
640 			}
641 
642 			/*
643 			 * Save as THIS method's return value in case it is returned
644 			 * immediately to yet another method
645 			 */
646 			walk_state->return_desc = return_desc;
647 		}
648 
649 		/*
650 		 * The following code is the optional support for the so-called
651 		 * "implicit return". Some AML code assumes that the last value of the
652 		 * method is "implicitly" returned to the caller, in the absence of an
653 		 * explicit return value.
654 		 *
655 		 * Just save the last result of the method as the return value.
656 		 *
657 		 * NOTE: this is optional because the ASL language does not actually
658 		 * support this behavior.
659 		 */
660 		else if (!acpi_ds_do_implicit_return
661 			 (return_desc, walk_state, FALSE)
662 			 || same_as_implicit_return) {
663 			/*
664 			 * Delete the return value if it will not be used by the
665 			 * calling method or remove one reference if the explicit return
666 			 * is the same as the implicit return value.
667 			 */
668 			acpi_ut_remove_reference(return_desc);
669 		}
670 	}
671 
672 	return_ACPI_STATUS(AE_OK);
673 }
674 
675 /*******************************************************************************
676  *
677  * FUNCTION:    acpi_ds_terminate_control_method
678  *
679  * PARAMETERS:  method_desc         - Method object
680  *              walk_state          - State associated with the method
681  *
682  * RETURN:      None
683  *
684  * DESCRIPTION: Terminate a control method. Delete everything that the method
685  *              created, delete all locals and arguments, and delete the parse
686  *              tree if requested.
687  *
688  * MUTEX:       Interpreter is locked
689  *
690  ******************************************************************************/
691 
692 void
acpi_ds_terminate_control_method(union acpi_operand_object * method_desc,struct acpi_walk_state * walk_state)693 acpi_ds_terminate_control_method(union acpi_operand_object *method_desc,
694 				 struct acpi_walk_state *walk_state)
695 {
696 
697 	ACPI_FUNCTION_TRACE_PTR(ds_terminate_control_method, walk_state);
698 
699 	/* method_desc is required, walk_state is optional */
700 
701 	if (!method_desc) {
702 		return_VOID;
703 	}
704 
705 	if (walk_state) {
706 
707 		/* Delete all arguments and locals */
708 
709 		acpi_ds_method_data_delete_all(walk_state);
710 
711 		/*
712 		 * If method is serialized, release the mutex and restore the
713 		 * current sync level for this thread
714 		 */
715 		if (method_desc->method.mutex) {
716 
717 			/* Acquisition Depth handles recursive calls */
718 
719 			method_desc->method.mutex->mutex.acquisition_depth--;
720 			if (!method_desc->method.mutex->mutex.acquisition_depth) {
721 				walk_state->thread->current_sync_level =
722 				    method_desc->method.mutex->mutex.
723 				    original_sync_level;
724 
725 				acpi_os_release_mutex(method_desc->method.
726 						      mutex->mutex.os_mutex);
727 				method_desc->method.mutex->mutex.thread_id = 0;
728 			}
729 		}
730 
731 		/*
732 		 * Delete any namespace objects created anywhere within the
733 		 * namespace by the execution of this method. Unless:
734 		 * 1) This method is a module-level executable code method, in which
735 		 *    case we want make the objects permanent.
736 		 * 2) There are other threads executing the method, in which case we
737 		 *    will wait until the last thread has completed.
738 		 */
739 		if (!(method_desc->method.info_flags & ACPI_METHOD_MODULE_LEVEL)
740 		    && (method_desc->method.thread_count == 1)) {
741 
742 			/* Delete any direct children of (created by) this method */
743 
744 			acpi_ns_delete_namespace_subtree(walk_state->
745 							 method_node);
746 
747 			/*
748 			 * Delete any objects that were created by this method
749 			 * elsewhere in the namespace (if any were created).
750 			 * Use of the ACPI_METHOD_MODIFIED_NAMESPACE optimizes the
751 			 * deletion such that we don't have to perform an entire
752 			 * namespace walk for every control method execution.
753 			 */
754 			if (method_desc->method.
755 			    info_flags & ACPI_METHOD_MODIFIED_NAMESPACE) {
756 				acpi_ns_delete_namespace_by_owner(method_desc->
757 								  method.
758 								  owner_id);
759 				method_desc->method.info_flags &=
760 				    ~ACPI_METHOD_MODIFIED_NAMESPACE;
761 			}
762 		}
763 	}
764 
765 	/* Decrement the thread count on the method */
766 
767 	if (method_desc->method.thread_count) {
768 		method_desc->method.thread_count--;
769 	} else {
770 		ACPI_ERROR((AE_INFO, "Invalid zero thread count in method"));
771 	}
772 
773 	/* Are there any other threads currently executing this method? */
774 
775 	if (method_desc->method.thread_count) {
776 		/*
777 		 * Additional threads. Do not release the owner_id in this case,
778 		 * we immediately reuse it for the next thread executing this method
779 		 */
780 		ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
781 				  "*** Completed execution of one thread, %u threads remaining\n",
782 				  method_desc->method.thread_count));
783 	} else {
784 		/* This is the only executing thread for this method */
785 
786 		/*
787 		 * Support to dynamically change a method from not_serialized to
788 		 * Serialized if it appears that the method is incorrectly written and
789 		 * does not support multiple thread execution. The best example of this
790 		 * is if such a method creates namespace objects and blocks. A second
791 		 * thread will fail with an AE_ALREADY_EXISTS exception.
792 		 *
793 		 * This code is here because we must wait until the last thread exits
794 		 * before marking the method as serialized.
795 		 */
796 		if (method_desc->method.
797 		    info_flags & ACPI_METHOD_SERIALIZED_PENDING) {
798 			if (walk_state) {
799 				ACPI_INFO((AE_INFO,
800 					   "Marking method %4.4s as Serialized because of AE_ALREADY_EXISTS error",
801 					   walk_state->method_node->name.
802 					   ascii));
803 			}
804 
805 			/*
806 			 * Method tried to create an object twice and was marked as
807 			 * "pending serialized". The probable cause is that the method
808 			 * cannot handle reentrancy.
809 			 *
810 			 * The method was created as not_serialized, but it tried to create
811 			 * a named object and then blocked, causing the second thread
812 			 * entrance to begin and then fail. Workaround this problem by
813 			 * marking the method permanently as Serialized when the last
814 			 * thread exits here.
815 			 */
816 			method_desc->method.info_flags &=
817 			    ~ACPI_METHOD_SERIALIZED_PENDING;
818 			method_desc->method.info_flags |=
819 			    (ACPI_METHOD_SERIALIZED |
820 			     ACPI_METHOD_IGNORE_SYNC_LEVEL);
821 			method_desc->method.sync_level = 0;
822 		}
823 
824 		/* No more threads, we can free the owner_id */
825 
826 		if (!
827 		    (method_desc->method.
828 		     info_flags & ACPI_METHOD_MODULE_LEVEL)) {
829 			acpi_ut_release_owner_id(&method_desc->method.owner_id);
830 		}
831 	}
832 
833 	return_VOID;
834 }
835