nswalk.c

  1// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
  2/******************************************************************************
  3 *
  4 * Module Name: nswalk - Functions for walking the ACPI namespace
  5 *
  6 * Copyright (C) 2000 - 2025, Intel Corp.
  7 *
  8 *****************************************************************************/
  9
 10#include <acpi/acpi.h>
 11#include "accommon.h"
 12#include "acnamesp.h"
 13
 14#define _COMPONENT          ACPI_NAMESPACE
 15ACPI_MODULE_NAME("nswalk")
 16
 17/*******************************************************************************
 18 *
 19 * FUNCTION:    acpi_ns_get_next_node
 20 *
 21 * PARAMETERS:  parent_node         - Parent node whose children we are
 22 *                                    getting
 23 *              child_node          - Previous child that was found.
 24 *                                    The NEXT child will be returned
 25 *
 26 * RETURN:      struct acpi_namespace_node - Pointer to the NEXT child or NULL if
 27 *                                    none is found.
 28 *
 29 * DESCRIPTION: Return the next peer node within the namespace. If Handle
 30 *              is valid, Scope is ignored. Otherwise, the first node
 31 *              within Scope is returned.
 32 *
 33 ******************************************************************************/
 34struct acpi_namespace_node *acpi_ns_get_next_node(struct acpi_namespace_node
 35						  *parent_node,
 36						  struct acpi_namespace_node
 37						  *child_node)
 38{
 39	ACPI_FUNCTION_ENTRY();
 40
 41	if (!child_node) {
 42
 43		/* It's really the parent's _scope_ that we want */
 44
 45		return (parent_node->child);
 46	}
 47
 48	/* Otherwise just return the next peer */
 49
 50	return (child_node->peer);
 51}
 52
 53/*******************************************************************************
 54 *
 55 * FUNCTION:    acpi_ns_get_next_node_typed
 56 *
 57 * PARAMETERS:  type                - Type of node to be searched for
 58 *              parent_node         - Parent node whose children we are
 59 *                                    getting
 60 *              child_node          - Previous child that was found.
 61 *                                    The NEXT child will be returned
 62 *
 63 * RETURN:      struct acpi_namespace_node - Pointer to the NEXT child or NULL if
 64 *                                    none is found.
 65 *
 66 * DESCRIPTION: Return the next peer node within the namespace. If Handle
 67 *              is valid, Scope is ignored. Otherwise, the first node
 68 *              within Scope is returned.
 69 *
 70 ******************************************************************************/
 71
 72struct acpi_namespace_node *acpi_ns_get_next_node_typed(acpi_object_type type,
 73							struct
 74							acpi_namespace_node
 75							*parent_node,
 76							struct
 77							acpi_namespace_node
 78							*child_node)
 79{
 80	struct acpi_namespace_node *next_node = NULL;
 81
 82	ACPI_FUNCTION_ENTRY();
 83
 84	next_node = acpi_ns_get_next_node(parent_node, child_node);
 85
 86
 87	/* If any type is OK, we are done */
 88
 89	if (type == ACPI_TYPE_ANY) {
 90
 91		/* next_node is NULL if we are at the end-of-list */
 92
 93		return (next_node);
 94	}
 95
 96	/* Must search for the node -- but within this scope only */
 97
 98	while (next_node) {
 99
100		/* If type matches, we are done */
101
102		if (next_node->type == type) {
103			return (next_node);
104		}
105
106		/* Otherwise, move on to the next peer node */
107
108		next_node = next_node->peer;
109	}
110
111	/* Not found */
112
113	return (NULL);
114}
115
116/*******************************************************************************
117 *
118 * FUNCTION:    acpi_ns_walk_namespace
119 *
120 * PARAMETERS:  type                - acpi_object_type to search for
121 *              start_node          - Handle in namespace where search begins
122 *              max_depth           - Depth to which search is to reach
123 *              flags               - Whether to unlock the NS before invoking
124 *                                    the callback routine
125 *              descending_callback - Called during tree descent
126 *                                    when an object of "Type" is found
127 *              ascending_callback  - Called during tree ascent
128 *                                    when an object of "Type" is found
129 *              context             - Passed to user function(s) above
130 *              return_value        - from the user_function if terminated
131 *                                    early. Otherwise, returns NULL.
132 * RETURNS:     Status
133 *
134 * DESCRIPTION: Performs a modified depth-first walk of the namespace tree,
135 *              starting (and ending) at the node specified by start_handle.
136 *              The callback function is called whenever a node that matches
137 *              the type parameter is found. If the callback function returns
138 *              a non-zero value, the search is terminated immediately and
139 *              this value is returned to the caller.
140 *
141 *              The point of this procedure is to provide a generic namespace
142 *              walk routine that can be called from multiple places to
143 *              provide multiple services; the callback function(s) can be
144 *              tailored to each task, whether it is a print function,
145 *              a compare function, etc.
146 *
147 ******************************************************************************/
148
149acpi_status
150acpi_ns_walk_namespace(acpi_object_type type,
151		       acpi_handle start_node,
152		       u32 max_depth,
153		       u32 flags,
154		       acpi_walk_callback descending_callback,
155		       acpi_walk_callback ascending_callback,
156		       void *context, void **return_value)
157{
158	acpi_status status;
159	acpi_status mutex_status;
160	struct acpi_namespace_node *child_node;
161	struct acpi_namespace_node *parent_node;
162	acpi_object_type child_type;
163	u32 level;
164	u8 node_previously_visited = FALSE;
165
166	ACPI_FUNCTION_TRACE(ns_walk_namespace);
167
168	/* Special case for the namespace Root Node */
169
170	if (start_node == ACPI_ROOT_OBJECT) {
171		start_node = acpi_gbl_root_node;
172	}
173
174	/* Avoid walking the namespace if the StartNode is NULL */
175
176	if (!start_node) {
177		return_ACPI_STATUS(AE_NO_NAMESPACE);
178	}
179
180	/* Null child means "get first node" */
181
182	parent_node = start_node;
183	child_node = acpi_ns_get_next_node(parent_node, NULL);
184	child_type = ACPI_TYPE_ANY;
185	level = 1;
186
187	/*
188	 * Traverse the tree of nodes until we bubble back up to where we
189	 * started. When Level is zero, the loop is done because we have
190	 * bubbled up to (and passed) the original parent handle (start_entry)
191	 */
192	while (level > 0 && child_node) {
193		status = AE_OK;
194
195		/* Found next child, get the type if we are not searching for ANY */
196
197		if (type != ACPI_TYPE_ANY) {
198			child_type = child_node->type;
199		}
200
201		/*
202		 * Ignore all temporary namespace nodes (created during control
203		 * method execution) unless told otherwise. These temporary nodes
204		 * can cause a race condition because they can be deleted during
205		 * the execution of the user function (if the namespace is
206		 * unlocked before invocation of the user function.) Only the
207		 * debugger namespace dump will examine the temporary nodes.
208		 */
209		if ((child_node->flags & ANOBJ_TEMPORARY) &&
210		    !(flags & ACPI_NS_WALK_TEMP_NODES)) {
211			status = AE_CTRL_DEPTH;
212		}
213
214		/* Type must match requested type */
215
216		else if (child_type == type) {
217			/*
218			 * Found a matching node, invoke the user callback function.
219			 * Unlock the namespace if flag is set.
220			 */
221			if (flags & ACPI_NS_WALK_UNLOCK) {
222				mutex_status =
223				    acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
224				if (ACPI_FAILURE(mutex_status)) {
225					return_ACPI_STATUS(mutex_status);
226				}
227			}
228
229			/*
230			 * Invoke the user function, either descending, ascending,
231			 * or both.
232			 */
233			if (!node_previously_visited) {
234				if (descending_callback) {
235					status =
236					    descending_callback(child_node,
237								level, context,
238								return_value);
239				}
240			} else {
241				if (ascending_callback) {
242					status =
243					    ascending_callback(child_node,
244							       level, context,
245							       return_value);
246				}
247			}
248
249			if (flags & ACPI_NS_WALK_UNLOCK) {
250				mutex_status =
251				    acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE);
252				if (ACPI_FAILURE(mutex_status)) {
253					return_ACPI_STATUS(mutex_status);
254				}
255			}
256
257			switch (status) {
258			case AE_OK:
259			case AE_CTRL_DEPTH:
260
261				/* Just keep going */
262				break;
263
264			case AE_CTRL_TERMINATE:
265
266				/* Exit now, with OK status */
267
268				return_ACPI_STATUS(AE_OK);
269
270			default:
271
272				/* All others are valid exceptions */
273
274				return_ACPI_STATUS(status);
275			}
276		}
277
278		/*
279		 * Depth first search: Attempt to go down another level in the
280		 * namespace if we are allowed to. Don't go any further if we have
281		 * reached the caller specified maximum depth or if the user
282		 * function has specified that the maximum depth has been reached.
283		 */
284		if (!node_previously_visited &&
285		    (level < max_depth) && (status != AE_CTRL_DEPTH)) {
286			if (child_node->child) {
287
288				/* There is at least one child of this node, visit it */
289
290				level++;
291				parent_node = child_node;
292				child_node =
293				    acpi_ns_get_next_node(parent_node, NULL);
294				continue;
295			}
296		}
297
298		/* No more children, re-visit this node */
299
300		if (!node_previously_visited) {
301			node_previously_visited = TRUE;
302			continue;
303		}
304
305		/* No more children, visit peers */
306
307		child_node = acpi_ns_get_next_node(parent_node, child_node);
308		if (child_node) {
309			node_previously_visited = FALSE;
310		}
311
312		/* No peers, re-visit parent */
313
314		else {
315			/*
316			 * No more children of this node (acpi_ns_get_next_node failed), go
317			 * back upwards in the namespace tree to the node's parent.
318			 */
319			level--;
320			child_node = parent_node;
321			parent_node = parent_node->parent;
322
323			node_previously_visited = TRUE;
324		}
325	}
326
327	/* Complete walk, not terminated by user function */
328
329	return_ACPI_STATUS(AE_OK);
330}