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 - 2022, 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  ******************************************************************************/
acpi_ns_get_next_node(struct acpi_namespace_node * parent_node,struct acpi_namespace_node * child_node)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 
acpi_ns_get_next_node_typed(acpi_object_type type,struct acpi_namespace_node * parent_node,struct acpi_namespace_node * child_node)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
acpi_ns_walk_namespace(acpi_object_type type,acpi_handle start_node,u32 max_depth,u32 flags,acpi_walk_callback descending_callback,acpi_walk_callback ascending_callback,void * context,void ** return_value)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 		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