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 if (!start_node) {
173 return_ACPI_STATUS(AE_NO_NAMESPACE);
174 }
175 }
176
177 /* Null child means "get first node" */
178
179 parent_node = start_node;
180 child_node = acpi_ns_get_next_node(parent_node, NULL);
181 child_type = ACPI_TYPE_ANY;
182 level = 1;
183
184 /*
185 * Traverse the tree of nodes until we bubble back up to where we
186 * started. When Level is zero, the loop is done because we have
187 * bubbled up to (and passed) the original parent handle (start_entry)
188 */
189 while (level > 0 && child_node) {
190 status = AE_OK;
191
192 /* Found next child, get the type if we are not searching for ANY */
193
194 if (type != ACPI_TYPE_ANY) {
195 child_type = child_node->type;
196 }
197
198 /*
199 * Ignore all temporary namespace nodes (created during control
200 * method execution) unless told otherwise. These temporary nodes
201 * can cause a race condition because they can be deleted during
202 * the execution of the user function (if the namespace is
203 * unlocked before invocation of the user function.) Only the
204 * debugger namespace dump will examine the temporary nodes.
205 */
206 if ((child_node->flags & ANOBJ_TEMPORARY) &&
207 !(flags & ACPI_NS_WALK_TEMP_NODES)) {
208 status = AE_CTRL_DEPTH;
209 }
210
211 /* Type must match requested type */
212
213 else if (child_type == type) {
214 /*
215 * Found a matching node, invoke the user callback function.
216 * Unlock the namespace if flag is set.
217 */
218 if (flags & ACPI_NS_WALK_UNLOCK) {
219 mutex_status =
220 acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
221 if (ACPI_FAILURE(mutex_status)) {
222 return_ACPI_STATUS(mutex_status);
223 }
224 }
225
226 /*
227 * Invoke the user function, either descending, ascending,
228 * or both.
229 */
230 if (!node_previously_visited) {
231 if (descending_callback) {
232 status =
233 descending_callback(child_node,
234 level, context,
235 return_value);
236 }
237 } else {
238 if (ascending_callback) {
239 status =
240 ascending_callback(child_node,
241 level, context,
242 return_value);
243 }
244 }
245
246 if (flags & ACPI_NS_WALK_UNLOCK) {
247 mutex_status =
248 acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE);
249 if (ACPI_FAILURE(mutex_status)) {
250 return_ACPI_STATUS(mutex_status);
251 }
252 }
253
254 switch (status) {
255 case AE_OK:
256 case AE_CTRL_DEPTH:
257
258 /* Just keep going */
259 break;
260
261 case AE_CTRL_TERMINATE:
262
263 /* Exit now, with OK status */
264
265 return_ACPI_STATUS(AE_OK);
266
267 default:
268
269 /* All others are valid exceptions */
270
271 return_ACPI_STATUS(status);
272 }
273 }
274
275 /*
276 * Depth first search: Attempt to go down another level in the
277 * namespace if we are allowed to. Don't go any further if we have
278 * reached the caller specified maximum depth or if the user
279 * function has specified that the maximum depth has been reached.
280 */
281 if (!node_previously_visited &&
282 (level < max_depth) && (status != AE_CTRL_DEPTH)) {
283 if (child_node->child) {
284
285 /* There is at least one child of this node, visit it */
286
287 level++;
288 parent_node = child_node;
289 child_node =
290 acpi_ns_get_next_node(parent_node, NULL);
291 continue;
292 }
293 }
294
295 /* No more children, re-visit this node */
296
297 if (!node_previously_visited) {
298 node_previously_visited = TRUE;
299 continue;
300 }
301
302 /* No more children, visit peers */
303
304 child_node = acpi_ns_get_next_node(parent_node, child_node);
305 if (child_node) {
306 node_previously_visited = FALSE;
307 }
308
309 /* No peers, re-visit parent */
310
311 else {
312 /*
313 * No more children of this node (acpi_ns_get_next_node failed), go
314 * back upwards in the namespace tree to the node's parent.
315 */
316 level--;
317 child_node = parent_node;
318 parent_node = parent_node->parent;
319
320 node_previously_visited = TRUE;
321 }
322 }
323
324 /* Complete walk, not terminated by user function */
325
326 return_ACPI_STATUS(AE_OK);
327}
328