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 - 2019, Intel Corp.
7 *
8 *****************************************************************************/
9
10 #include <acpi/acpi.h>
11 #include "accommon.h"
12 #include "acnamesp.h"
13
14 #define _COMPONENT ACPI_NAMESPACE
15 ACPI_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 ******************************************************************************/
34 struct 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
72 struct 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
149 acpi_status
150 acpi_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 /* Null child means "get first node" */
175
176 parent_node = start_node;
177 child_node = acpi_ns_get_next_node(parent_node, NULL);
178 child_type = ACPI_TYPE_ANY;
179 level = 1;
180
181 /*
182 * Traverse the tree of nodes until we bubble back up to where we
183 * started. When Level is zero, the loop is done because we have
184 * bubbled up to (and passed) the original parent handle (start_entry)
185 */
186 while (level > 0 && child_node) {
187 status = AE_OK;
188
189 /* Found next child, get the type if we are not searching for ANY */
190
191 if (type != ACPI_TYPE_ANY) {
192 child_type = child_node->type;
193 }
194
195 /*
196 * Ignore all temporary namespace nodes (created during control
197 * method execution) unless told otherwise. These temporary nodes
198 * can cause a race condition because they can be deleted during
199 * the execution of the user function (if the namespace is
200 * unlocked before invocation of the user function.) Only the
201 * debugger namespace dump will examine the temporary nodes.
202 */
203 if ((child_node->flags & ANOBJ_TEMPORARY) &&
204 !(flags & ACPI_NS_WALK_TEMP_NODES)) {
205 status = AE_CTRL_DEPTH;
206 }
207
208 /* Type must match requested type */
209
210 else if (child_type == type) {
211 /*
212 * Found a matching node, invoke the user callback function.
213 * Unlock the namespace if flag is set.
214 */
215 if (flags & ACPI_NS_WALK_UNLOCK) {
216 mutex_status =
217 acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
218 if (ACPI_FAILURE(mutex_status)) {
219 return_ACPI_STATUS(mutex_status);
220 }
221 }
222
223 /*
224 * Invoke the user function, either descending, ascending,
225 * or both.
226 */
227 if (!node_previously_visited) {
228 if (descending_callback) {
229 status =
230 descending_callback(child_node,
231 level, context,
232 return_value);
233 }
234 } else {
235 if (ascending_callback) {
236 status =
237 ascending_callback(child_node,
238 level, context,
239 return_value);
240 }
241 }
242
243 if (flags & ACPI_NS_WALK_UNLOCK) {
244 mutex_status =
245 acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE);
246 if (ACPI_FAILURE(mutex_status)) {
247 return_ACPI_STATUS(mutex_status);
248 }
249 }
250
251 switch (status) {
252 case AE_OK:
253 case AE_CTRL_DEPTH:
254
255 /* Just keep going */
256 break;
257
258 case AE_CTRL_TERMINATE:
259
260 /* Exit now, with OK status */
261
262 return_ACPI_STATUS(AE_OK);
263
264 default:
265
266 /* All others are valid exceptions */
267
268 return_ACPI_STATUS(status);
269 }
270 }
271
272 /*
273 * Depth first search: Attempt to go down another level in the
274 * namespace if we are allowed to. Don't go any further if we have
275 * reached the caller specified maximum depth or if the user
276 * function has specified that the maximum depth has been reached.
277 */
278 if (!node_previously_visited &&
279 (level < max_depth) && (status != AE_CTRL_DEPTH)) {
280 if (child_node->child) {
281
282 /* There is at least one child of this node, visit it */
283
284 level++;
285 parent_node = child_node;
286 child_node =
287 acpi_ns_get_next_node(parent_node, NULL);
288 continue;
289 }
290 }
291
292 /* No more children, re-visit this node */
293
294 if (!node_previously_visited) {
295 node_previously_visited = TRUE;
296 continue;
297 }
298
299 /* No more children, visit peers */
300
301 child_node = acpi_ns_get_next_node(parent_node, child_node);
302 if (child_node) {
303 node_previously_visited = FALSE;
304 }
305
306 /* No peers, re-visit parent */
307
308 else {
309 /*
310 * No more children of this node (acpi_ns_get_next_node failed), go
311 * back upwards in the namespace tree to the node's parent.
312 */
313 level--;
314 child_node = parent_node;
315 parent_node = parent_node->parent;
316
317 node_previously_visited = TRUE;
318 }
319 }
320
321 /* Complete walk, not terminated by user function */
322
323 return_ACPI_STATUS(AE_OK);
324 }