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1/*
2 * Functions for working with device tree overlays
3 *
4 * Copyright (C) 2012 Pantelis Antoniou <panto@antoniou-consulting.com>
5 * Copyright (C) 2012 Texas Instruments Inc.
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * version 2 as published by the Free Software Foundation.
10 */
11#undef DEBUG
12#include <linux/kernel.h>
13#include <linux/module.h>
14#include <linux/of.h>
15#include <linux/of_device.h>
16#include <linux/string.h>
17#include <linux/ctype.h>
18#include <linux/errno.h>
19#include <linux/string.h>
20#include <linux/slab.h>
21#include <linux/err.h>
22#include <linux/idr.h>
23
24#include "of_private.h"
25
26/**
27 * struct of_overlay_info - Holds a single overlay info
28 * @target: target of the overlay operation
29 * @overlay: pointer to the overlay contents node
30 *
31 * Holds a single overlay state, including all the overlay logs &
32 * records.
33 */
34struct of_overlay_info {
35 struct device_node *target;
36 struct device_node *overlay;
37};
38
39/**
40 * struct of_overlay - Holds a complete overlay transaction
41 * @node: List on which we are located
42 * @count: Count of ovinfo structures
43 * @ovinfo_tab: Overlay info table (count sized)
44 * @cset: Changeset to be used
45 *
46 * Holds a complete overlay transaction
47 */
48struct of_overlay {
49 int id;
50 struct list_head node;
51 int count;
52 struct of_overlay_info *ovinfo_tab;
53 struct of_changeset cset;
54};
55
56static int of_overlay_apply_one(struct of_overlay *ov,
57 struct device_node *target, const struct device_node *overlay);
58
59static int of_overlay_apply_single_property(struct of_overlay *ov,
60 struct device_node *target, struct property *prop)
61{
62 struct property *propn, *tprop;
63
64 /* NOTE: Multiple changes of single properties not supported */
65 tprop = of_find_property(target, prop->name, NULL);
66
67 /* special properties are not meant to be updated (silent NOP) */
68 if (of_prop_cmp(prop->name, "name") == 0 ||
69 of_prop_cmp(prop->name, "phandle") == 0 ||
70 of_prop_cmp(prop->name, "linux,phandle") == 0)
71 return 0;
72
73 propn = __of_prop_dup(prop, GFP_KERNEL);
74 if (propn == NULL)
75 return -ENOMEM;
76
77 /* not found? add */
78 if (tprop == NULL)
79 return of_changeset_add_property(&ov->cset, target, propn);
80
81 /* found? update */
82 return of_changeset_update_property(&ov->cset, target, propn);
83}
84
85static int of_overlay_apply_single_device_node(struct of_overlay *ov,
86 struct device_node *target, struct device_node *child)
87{
88 const char *cname;
89 struct device_node *tchild;
90 int ret = 0;
91
92 cname = kbasename(child->full_name);
93 if (cname == NULL)
94 return -ENOMEM;
95
96 /* NOTE: Multiple mods of created nodes not supported */
97 tchild = of_get_child_by_name(target, cname);
98 if (tchild != NULL) {
99 /* apply overlay recursively */
100 ret = of_overlay_apply_one(ov, tchild, child);
101 of_node_put(tchild);
102 } else {
103 /* create empty tree as a target */
104 tchild = __of_node_dup(child, "%s/%s", target->full_name, cname);
105 if (!tchild)
106 return -ENOMEM;
107
108 /* point to parent */
109 tchild->parent = target;
110
111 ret = of_changeset_attach_node(&ov->cset, tchild);
112 if (ret)
113 return ret;
114
115 ret = of_overlay_apply_one(ov, tchild, child);
116 if (ret)
117 return ret;
118 }
119
120 return ret;
121}
122
123/*
124 * Apply a single overlay node recursively.
125 *
126 * Note that the in case of an error the target node is left
127 * in a inconsistent state. Error recovery should be performed
128 * by using the changeset.
129 */
130static int of_overlay_apply_one(struct of_overlay *ov,
131 struct device_node *target, const struct device_node *overlay)
132{
133 struct device_node *child;
134 struct property *prop;
135 int ret;
136
137 for_each_property_of_node(overlay, prop) {
138 ret = of_overlay_apply_single_property(ov, target, prop);
139 if (ret) {
140 pr_err("%s: Failed to apply prop @%s/%s\n",
141 __func__, target->full_name, prop->name);
142 return ret;
143 }
144 }
145
146 for_each_child_of_node(overlay, child) {
147 ret = of_overlay_apply_single_device_node(ov, target, child);
148 if (ret != 0) {
149 pr_err("%s: Failed to apply single node @%s/%s\n",
150 __func__, target->full_name,
151 child->name);
152 of_node_put(child);
153 return ret;
154 }
155 }
156
157 return 0;
158}
159
160/**
161 * of_overlay_apply() - Apply @count overlays pointed at by @ovinfo_tab
162 * @ov: Overlay to apply
163 *
164 * Applies the overlays given, while handling all error conditions
165 * appropriately. Either the operation succeeds, or if it fails the
166 * live tree is reverted to the state before the attempt.
167 * Returns 0, or an error if the overlay attempt failed.
168 */
169static int of_overlay_apply(struct of_overlay *ov)
170{
171 int i, err;
172
173 /* first we apply the overlays atomically */
174 for (i = 0; i < ov->count; i++) {
175 struct of_overlay_info *ovinfo = &ov->ovinfo_tab[i];
176
177 err = of_overlay_apply_one(ov, ovinfo->target, ovinfo->overlay);
178 if (err != 0) {
179 pr_err("%s: overlay failed '%s'\n",
180 __func__, ovinfo->target->full_name);
181 return err;
182 }
183 }
184
185 return 0;
186}
187
188/*
189 * Find the target node using a number of different strategies
190 * in order of preference
191 *
192 * "target" property containing the phandle of the target
193 * "target-path" property containing the path of the target
194 */
195static struct device_node *find_target_node(struct device_node *info_node)
196{
197 const char *path;
198 u32 val;
199 int ret;
200
201 /* first try to go by using the target as a phandle */
202 ret = of_property_read_u32(info_node, "target", &val);
203 if (ret == 0)
204 return of_find_node_by_phandle(val);
205
206 /* now try to locate by path */
207 ret = of_property_read_string(info_node, "target-path", &path);
208 if (ret == 0)
209 return of_find_node_by_path(path);
210
211 pr_err("%s: Failed to find target for node %p (%s)\n", __func__,
212 info_node, info_node->name);
213
214 return NULL;
215}
216
217/**
218 * of_fill_overlay_info() - Fill an overlay info structure
219 * @ov Overlay to fill
220 * @info_node: Device node containing the overlay
221 * @ovinfo: Pointer to the overlay info structure to fill
222 *
223 * Fills an overlay info structure with the overlay information
224 * from a device node. This device node must have a target property
225 * which contains a phandle of the overlay target node, and an
226 * __overlay__ child node which has the overlay contents.
227 * Both ovinfo->target & ovinfo->overlay have their references taken.
228 *
229 * Returns 0 on success, or a negative error value.
230 */
231static int of_fill_overlay_info(struct of_overlay *ov,
232 struct device_node *info_node, struct of_overlay_info *ovinfo)
233{
234 ovinfo->overlay = of_get_child_by_name(info_node, "__overlay__");
235 if (ovinfo->overlay == NULL)
236 goto err_fail;
237
238 ovinfo->target = find_target_node(info_node);
239 if (ovinfo->target == NULL)
240 goto err_fail;
241
242 return 0;
243
244err_fail:
245 of_node_put(ovinfo->target);
246 of_node_put(ovinfo->overlay);
247
248 memset(ovinfo, 0, sizeof(*ovinfo));
249 return -EINVAL;
250}
251
252/**
253 * of_build_overlay_info() - Build an overlay info array
254 * @ov Overlay to build
255 * @tree: Device node containing all the overlays
256 *
257 * Helper function that given a tree containing overlay information,
258 * allocates and builds an overlay info array containing it, ready
259 * for use using of_overlay_apply.
260 *
261 * Returns 0 on success with the @cntp @ovinfop pointers valid,
262 * while on error a negative error value is returned.
263 */
264static int of_build_overlay_info(struct of_overlay *ov,
265 struct device_node *tree)
266{
267 struct device_node *node;
268 struct of_overlay_info *ovinfo;
269 int cnt, err;
270
271 /* worst case; every child is a node */
272 cnt = 0;
273 for_each_child_of_node(tree, node)
274 cnt++;
275
276 ovinfo = kcalloc(cnt, sizeof(*ovinfo), GFP_KERNEL);
277 if (ovinfo == NULL)
278 return -ENOMEM;
279
280 cnt = 0;
281 for_each_child_of_node(tree, node) {
282 memset(&ovinfo[cnt], 0, sizeof(*ovinfo));
283 err = of_fill_overlay_info(ov, node, &ovinfo[cnt]);
284 if (err == 0)
285 cnt++;
286 }
287
288 /* if nothing filled, return error */
289 if (cnt == 0) {
290 kfree(ovinfo);
291 return -ENODEV;
292 }
293
294 ov->count = cnt;
295 ov->ovinfo_tab = ovinfo;
296
297 return 0;
298}
299
300/**
301 * of_free_overlay_info() - Free an overlay info array
302 * @ov Overlay to free the overlay info from
303 * @ovinfo_tab: Array of overlay_info's to free
304 *
305 * Releases the memory of a previously allocated ovinfo array
306 * by of_build_overlay_info.
307 * Returns 0, or an error if the arguments are bogus.
308 */
309static int of_free_overlay_info(struct of_overlay *ov)
310{
311 struct of_overlay_info *ovinfo;
312 int i;
313
314 /* do it in reverse */
315 for (i = ov->count - 1; i >= 0; i--) {
316 ovinfo = &ov->ovinfo_tab[i];
317
318 of_node_put(ovinfo->target);
319 of_node_put(ovinfo->overlay);
320 }
321 kfree(ov->ovinfo_tab);
322
323 return 0;
324}
325
326static LIST_HEAD(ov_list);
327static DEFINE_IDR(ov_idr);
328
329/**
330 * of_overlay_create() - Create and apply an overlay
331 * @tree: Device node containing all the overlays
332 *
333 * Creates and applies an overlay while also keeping track
334 * of the overlay in a list. This list can be used to prevent
335 * illegal overlay removals.
336 *
337 * Returns the id of the created overlay, or a negative error number
338 */
339int of_overlay_create(struct device_node *tree)
340{
341 struct of_overlay *ov;
342 int err, id;
343
344 /* allocate the overlay structure */
345 ov = kzalloc(sizeof(*ov), GFP_KERNEL);
346 if (ov == NULL)
347 return -ENOMEM;
348 ov->id = -1;
349
350 INIT_LIST_HEAD(&ov->node);
351
352 of_changeset_init(&ov->cset);
353
354 mutex_lock(&of_mutex);
355
356 id = idr_alloc(&ov_idr, ov, 0, 0, GFP_KERNEL);
357 if (id < 0) {
358 pr_err("%s: idr_alloc() failed for tree@%s\n",
359 __func__, tree->full_name);
360 err = id;
361 goto err_destroy_trans;
362 }
363 ov->id = id;
364
365 /* build the overlay info structures */
366 err = of_build_overlay_info(ov, tree);
367 if (err) {
368 pr_err("%s: of_build_overlay_info() failed for tree@%s\n",
369 __func__, tree->full_name);
370 goto err_free_idr;
371 }
372
373 /* apply the overlay */
374 err = of_overlay_apply(ov);
375 if (err) {
376 pr_err("%s: of_overlay_apply() failed for tree@%s\n",
377 __func__, tree->full_name);
378 goto err_abort_trans;
379 }
380
381 /* apply the changeset */
382 err = __of_changeset_apply(&ov->cset);
383 if (err) {
384 pr_err("%s: __of_changeset_apply() failed for tree@%s\n",
385 __func__, tree->full_name);
386 goto err_revert_overlay;
387 }
388
389 /* add to the tail of the overlay list */
390 list_add_tail(&ov->node, &ov_list);
391
392 mutex_unlock(&of_mutex);
393
394 return id;
395
396err_revert_overlay:
397err_abort_trans:
398 of_free_overlay_info(ov);
399err_free_idr:
400 idr_remove(&ov_idr, ov->id);
401err_destroy_trans:
402 of_changeset_destroy(&ov->cset);
403 kfree(ov);
404 mutex_unlock(&of_mutex);
405
406 return err;
407}
408EXPORT_SYMBOL_GPL(of_overlay_create);
409
410/* check whether the given node, lies under the given tree */
411static int overlay_subtree_check(struct device_node *tree,
412 struct device_node *dn)
413{
414 struct device_node *child;
415
416 /* match? */
417 if (tree == dn)
418 return 1;
419
420 for_each_child_of_node(tree, child) {
421 if (overlay_subtree_check(child, dn)) {
422 of_node_put(child);
423 return 1;
424 }
425 }
426
427 return 0;
428}
429
430/* check whether this overlay is the topmost */
431static int overlay_is_topmost(struct of_overlay *ov, struct device_node *dn)
432{
433 struct of_overlay *ovt;
434 struct of_changeset_entry *ce;
435
436 list_for_each_entry_reverse(ovt, &ov_list, node) {
437 /* if we hit ourselves, we're done */
438 if (ovt == ov)
439 break;
440
441 /* check against each subtree affected by this overlay */
442 list_for_each_entry(ce, &ovt->cset.entries, node) {
443 if (overlay_subtree_check(ce->np, dn)) {
444 pr_err("%s: #%d clashes #%d @%s\n",
445 __func__, ov->id, ovt->id,
446 dn->full_name);
447 return 0;
448 }
449 }
450 }
451
452 /* overlay is topmost */
453 return 1;
454}
455
456/*
457 * We can safely remove the overlay only if it's the top-most one.
458 * Newly applied overlays are inserted at the tail of the overlay list,
459 * so a top most overlay is the one that is closest to the tail.
460 *
461 * The topmost check is done by exploiting this property. For each
462 * affected device node in the log list we check if this overlay is
463 * the one closest to the tail. If another overlay has affected this
464 * device node and is closest to the tail, then removal is not permited.
465 */
466static int overlay_removal_is_ok(struct of_overlay *ov)
467{
468 struct of_changeset_entry *ce;
469
470 list_for_each_entry(ce, &ov->cset.entries, node) {
471 if (!overlay_is_topmost(ov, ce->np)) {
472 pr_err("%s: overlay #%d is not topmost\n",
473 __func__, ov->id);
474 return 0;
475 }
476 }
477
478 return 1;
479}
480
481/**
482 * of_overlay_destroy() - Removes an overlay
483 * @id: Overlay id number returned by a previous call to of_overlay_create
484 *
485 * Removes an overlay if it is permissible.
486 *
487 * Returns 0 on success, or a negative error number
488 */
489int of_overlay_destroy(int id)
490{
491 struct of_overlay *ov;
492 int err;
493
494 mutex_lock(&of_mutex);
495
496 ov = idr_find(&ov_idr, id);
497 if (ov == NULL) {
498 err = -ENODEV;
499 pr_err("%s: Could not find overlay #%d\n",
500 __func__, id);
501 goto out;
502 }
503
504 /* check whether the overlay is safe to remove */
505 if (!overlay_removal_is_ok(ov)) {
506 err = -EBUSY;
507 pr_err("%s: removal check failed for overlay #%d\n",
508 __func__, id);
509 goto out;
510 }
511
512
513 list_del(&ov->node);
514 __of_changeset_revert(&ov->cset);
515 of_free_overlay_info(ov);
516 idr_remove(&ov_idr, id);
517 of_changeset_destroy(&ov->cset);
518 kfree(ov);
519
520 err = 0;
521
522out:
523 mutex_unlock(&of_mutex);
524
525 return err;
526}
527EXPORT_SYMBOL_GPL(of_overlay_destroy);
528
529/**
530 * of_overlay_destroy_all() - Removes all overlays from the system
531 *
532 * Removes all overlays from the system in the correct order.
533 *
534 * Returns 0 on success, or a negative error number
535 */
536int of_overlay_destroy_all(void)
537{
538 struct of_overlay *ov, *ovn;
539
540 mutex_lock(&of_mutex);
541
542 /* the tail of list is guaranteed to be safe to remove */
543 list_for_each_entry_safe_reverse(ov, ovn, &ov_list, node) {
544 list_del(&ov->node);
545 __of_changeset_revert(&ov->cset);
546 of_free_overlay_info(ov);
547 idr_remove(&ov_idr, ov->id);
548 kfree(ov);
549 }
550
551 mutex_unlock(&of_mutex);
552
553 return 0;
554}
555EXPORT_SYMBOL_GPL(of_overlay_destroy_all);
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Functions for working with device tree overlays
4 *
5 * Copyright (C) 2012 Pantelis Antoniou <panto@antoniou-consulting.com>
6 * Copyright (C) 2012 Texas Instruments Inc.
7 */
8
9#define pr_fmt(fmt) "OF: overlay: " fmt
10
11#include <linux/kernel.h>
12#include <linux/module.h>
13#include <linux/of.h>
14#include <linux/of_device.h>
15#include <linux/of_fdt.h>
16#include <linux/string.h>
17#include <linux/ctype.h>
18#include <linux/errno.h>
19#include <linux/slab.h>
20#include <linux/libfdt.h>
21#include <linux/err.h>
22#include <linux/idr.h>
23
24#include "of_private.h"
25
26/**
27 * struct fragment - info about fragment nodes in overlay expanded device tree
28 * @target: target of the overlay operation
29 * @overlay: pointer to the __overlay__ node
30 */
31struct fragment {
32 struct device_node *target;
33 struct device_node *overlay;
34};
35
36/**
37 * struct overlay_changeset
38 * @id: changeset identifier
39 * @ovcs_list: list on which we are located
40 * @fdt: FDT that was unflattened to create @overlay_tree
41 * @overlay_tree: expanded device tree that contains the fragment nodes
42 * @count: count of fragment structures
43 * @fragments: fragment nodes in the overlay expanded device tree
44 * @symbols_fragment: last element of @fragments[] is the __symbols__ node
45 * @cset: changeset to apply fragments to live device tree
46 */
47struct overlay_changeset {
48 int id;
49 struct list_head ovcs_list;
50 const void *fdt;
51 struct device_node *overlay_tree;
52 int count;
53 struct fragment *fragments;
54 bool symbols_fragment;
55 struct of_changeset cset;
56};
57
58/* flags are sticky - once set, do not reset */
59static int devicetree_state_flags;
60#define DTSF_APPLY_FAIL 0x01
61#define DTSF_REVERT_FAIL 0x02
62
63/*
64 * If a changeset apply or revert encounters an error, an attempt will
65 * be made to undo partial changes, but may fail. If the undo fails
66 * we do not know the state of the devicetree.
67 */
68static int devicetree_corrupt(void)
69{
70 return devicetree_state_flags &
71 (DTSF_APPLY_FAIL | DTSF_REVERT_FAIL);
72}
73
74static int build_changeset_next_level(struct overlay_changeset *ovcs,
75 struct device_node *target_node,
76 const struct device_node *overlay_node);
77
78/*
79 * of_resolve_phandles() finds the largest phandle in the live tree.
80 * of_overlay_apply() may add a larger phandle to the live tree.
81 * Do not allow race between two overlays being applied simultaneously:
82 * mutex_lock(&of_overlay_phandle_mutex)
83 * of_resolve_phandles()
84 * of_overlay_apply()
85 * mutex_unlock(&of_overlay_phandle_mutex)
86 */
87static DEFINE_MUTEX(of_overlay_phandle_mutex);
88
89void of_overlay_mutex_lock(void)
90{
91 mutex_lock(&of_overlay_phandle_mutex);
92}
93
94void of_overlay_mutex_unlock(void)
95{
96 mutex_unlock(&of_overlay_phandle_mutex);
97}
98
99
100static LIST_HEAD(ovcs_list);
101static DEFINE_IDR(ovcs_idr);
102
103static BLOCKING_NOTIFIER_HEAD(overlay_notify_chain);
104
105/**
106 * of_overlay_notifier_register() - Register notifier for overlay operations
107 * @nb: Notifier block to register
108 *
109 * Register for notification on overlay operations on device tree nodes. The
110 * reported actions definied by @of_reconfig_change. The notifier callback
111 * furthermore receives a pointer to the affected device tree node.
112 *
113 * Note that a notifier callback is not supposed to store pointers to a device
114 * tree node or its content beyond @OF_OVERLAY_POST_REMOVE corresponding to the
115 * respective node it received.
116 */
117int of_overlay_notifier_register(struct notifier_block *nb)
118{
119 return blocking_notifier_chain_register(&overlay_notify_chain, nb);
120}
121EXPORT_SYMBOL_GPL(of_overlay_notifier_register);
122
123/**
124 * of_overlay_notifier_register() - Unregister notifier for overlay operations
125 * @nb: Notifier block to unregister
126 */
127int of_overlay_notifier_unregister(struct notifier_block *nb)
128{
129 return blocking_notifier_chain_unregister(&overlay_notify_chain, nb);
130}
131EXPORT_SYMBOL_GPL(of_overlay_notifier_unregister);
132
133static char *of_overlay_action_name[] = {
134 "pre-apply",
135 "post-apply",
136 "pre-remove",
137 "post-remove",
138};
139
140static int overlay_notify(struct overlay_changeset *ovcs,
141 enum of_overlay_notify_action action)
142{
143 struct of_overlay_notify_data nd;
144 int i, ret;
145
146 for (i = 0; i < ovcs->count; i++) {
147 struct fragment *fragment = &ovcs->fragments[i];
148
149 nd.target = fragment->target;
150 nd.overlay = fragment->overlay;
151
152 ret = blocking_notifier_call_chain(&overlay_notify_chain,
153 action, &nd);
154 if (ret == NOTIFY_OK || ret == NOTIFY_STOP)
155 return 0;
156 if (ret) {
157 ret = notifier_to_errno(ret);
158 pr_err("overlay changeset %s notifier error %d, target: %pOF\n",
159 of_overlay_action_name[action], ret, nd.target);
160 return ret;
161 }
162 }
163
164 return 0;
165}
166
167/*
168 * The values of properties in the "/__symbols__" node are paths in
169 * the ovcs->overlay_tree. When duplicating the properties, the paths
170 * need to be adjusted to be the correct path for the live device tree.
171 *
172 * The paths refer to a node in the subtree of a fragment node's "__overlay__"
173 * node, for example "/fragment@0/__overlay__/symbol_path_tail",
174 * where symbol_path_tail can be a single node or it may be a multi-node path.
175 *
176 * The duplicated property value will be modified by replacing the
177 * "/fragment_name/__overlay/" portion of the value with the target
178 * path from the fragment node.
179 */
180static struct property *dup_and_fixup_symbol_prop(
181 struct overlay_changeset *ovcs, const struct property *prop)
182{
183 struct fragment *fragment;
184 struct property *new_prop;
185 struct device_node *fragment_node;
186 struct device_node *overlay_node;
187 const char *path;
188 const char *path_tail;
189 const char *target_path;
190 int k;
191 int overlay_name_len;
192 int path_len;
193 int path_tail_len;
194 int target_path_len;
195
196 if (!prop->value)
197 return NULL;
198 if (strnlen(prop->value, prop->length) >= prop->length)
199 return NULL;
200 path = prop->value;
201 path_len = strlen(path);
202
203 if (path_len < 1)
204 return NULL;
205 fragment_node = __of_find_node_by_path(ovcs->overlay_tree, path + 1);
206 overlay_node = __of_find_node_by_path(fragment_node, "__overlay__/");
207 of_node_put(fragment_node);
208 of_node_put(overlay_node);
209
210 for (k = 0; k < ovcs->count; k++) {
211 fragment = &ovcs->fragments[k];
212 if (fragment->overlay == overlay_node)
213 break;
214 }
215 if (k >= ovcs->count)
216 return NULL;
217
218 overlay_name_len = snprintf(NULL, 0, "%pOF", fragment->overlay);
219
220 if (overlay_name_len > path_len)
221 return NULL;
222 path_tail = path + overlay_name_len;
223 path_tail_len = strlen(path_tail);
224
225 target_path = kasprintf(GFP_KERNEL, "%pOF", fragment->target);
226 if (!target_path)
227 return NULL;
228 target_path_len = strlen(target_path);
229
230 new_prop = kzalloc(sizeof(*new_prop), GFP_KERNEL);
231 if (!new_prop)
232 goto err_free_target_path;
233
234 new_prop->name = kstrdup(prop->name, GFP_KERNEL);
235 new_prop->length = target_path_len + path_tail_len + 1;
236 new_prop->value = kzalloc(new_prop->length, GFP_KERNEL);
237 if (!new_prop->name || !new_prop->value)
238 goto err_free_new_prop;
239
240 strcpy(new_prop->value, target_path);
241 strcpy(new_prop->value + target_path_len, path_tail);
242
243 of_property_set_flag(new_prop, OF_DYNAMIC);
244
245 return new_prop;
246
247err_free_new_prop:
248 kfree(new_prop->name);
249 kfree(new_prop->value);
250 kfree(new_prop);
251err_free_target_path:
252 kfree(target_path);
253
254 return NULL;
255}
256
257/**
258 * add_changeset_property() - add @overlay_prop to overlay changeset
259 * @ovcs: overlay changeset
260 * @target_node: where to place @overlay_prop in live tree
261 * @overlay_prop: property to add or update, from overlay tree
262 * @is_symbols_prop: 1 if @overlay_prop is from node "/__symbols__"
263 *
264 * If @overlay_prop does not already exist in @target_node, add changeset entry
265 * to add @overlay_prop in @target_node, else add changeset entry to update
266 * value of @overlay_prop.
267 *
268 * Some special properties are not updated (no error returned).
269 *
270 * Update of property in symbols node is not allowed.
271 *
272 * Returns 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if
273 * invalid @overlay.
274 */
275static int add_changeset_property(struct overlay_changeset *ovcs,
276 struct device_node *target_node,
277 struct property *overlay_prop,
278 bool is_symbols_prop)
279{
280 struct property *new_prop = NULL, *prop;
281 int ret = 0;
282
283 prop = of_find_property(target_node, overlay_prop->name, NULL);
284
285 if (!of_prop_cmp(overlay_prop->name, "name") ||
286 !of_prop_cmp(overlay_prop->name, "phandle") ||
287 !of_prop_cmp(overlay_prop->name, "linux,phandle"))
288 return 0;
289
290 if (is_symbols_prop) {
291 if (prop)
292 return -EINVAL;
293 new_prop = dup_and_fixup_symbol_prop(ovcs, overlay_prop);
294 } else {
295 new_prop = __of_prop_dup(overlay_prop, GFP_KERNEL);
296 }
297
298 if (!new_prop)
299 return -ENOMEM;
300
301 if (!prop)
302 ret = of_changeset_add_property(&ovcs->cset, target_node,
303 new_prop);
304 else
305 ret = of_changeset_update_property(&ovcs->cset, target_node,
306 new_prop);
307
308 if (ret) {
309 kfree(new_prop->name);
310 kfree(new_prop->value);
311 kfree(new_prop);
312 }
313 return ret;
314}
315
316/**
317 * add_changeset_node() - add @node (and children) to overlay changeset
318 * @ovcs: overlay changeset
319 * @target_node: where to place @node in live tree
320 * @node: node from within overlay device tree fragment
321 *
322 * If @node does not already exist in @target_node, add changeset entry
323 * to add @node in @target_node.
324 *
325 * If @node already exists in @target_node, and the existing node has
326 * a phandle, the overlay node is not allowed to have a phandle.
327 *
328 * If @node has child nodes, add the children recursively via
329 * build_changeset_next_level().
330 *
331 * NOTE_1: A live devicetree created from a flattened device tree (FDT) will
332 * not contain the full path in node->full_name. Thus an overlay
333 * created from an FDT also will not contain the full path in
334 * node->full_name. However, a live devicetree created from Open
335 * Firmware may have the full path in node->full_name.
336 *
337 * add_changeset_node() follows the FDT convention and does not include
338 * the full path in node->full_name. Even though it expects the overlay
339 * to not contain the full path, it uses kbasename() to remove the
340 * full path should it exist. It also uses kbasename() in comparisons
341 * to nodes in the live devicetree so that it can apply an overlay to
342 * a live devicetree created from Open Firmware.
343 *
344 * NOTE_2: Multiple mods of created nodes not supported.
345 * If more than one fragment contains a node that does not already exist
346 * in the live tree, then for each fragment of_changeset_attach_node()
347 * will add a changeset entry to add the node. When the changeset is
348 * applied, __of_attach_node() will attach the node twice (once for
349 * each fragment). At this point the device tree will be corrupted.
350 *
351 * TODO: add integrity check to ensure that multiple fragments do not
352 * create the same node.
353 *
354 * Returns 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if
355 * invalid @overlay.
356 */
357static int add_changeset_node(struct overlay_changeset *ovcs,
358 struct device_node *target_node, struct device_node *node)
359{
360 const char *node_kbasename;
361 struct device_node *tchild;
362 int ret = 0;
363
364 node_kbasename = kbasename(node->full_name);
365
366 for_each_child_of_node(target_node, tchild)
367 if (!of_node_cmp(node_kbasename, kbasename(tchild->full_name)))
368 break;
369
370 if (!tchild) {
371 tchild = __of_node_dup(node, node_kbasename);
372 if (!tchild)
373 return -ENOMEM;
374
375 tchild->parent = target_node;
376
377 ret = of_changeset_attach_node(&ovcs->cset, tchild);
378 if (ret)
379 return ret;
380
381 return build_changeset_next_level(ovcs, tchild, node);
382 }
383
384 if (node->phandle && tchild->phandle)
385 ret = -EINVAL;
386 else
387 ret = build_changeset_next_level(ovcs, tchild, node);
388 of_node_put(tchild);
389
390 return ret;
391}
392
393/**
394 * build_changeset_next_level() - add level of overlay changeset
395 * @ovcs: overlay changeset
396 * @target_node: where to place @overlay_node in live tree
397 * @overlay_node: node from within an overlay device tree fragment
398 *
399 * Add the properties (if any) and nodes (if any) from @overlay_node to the
400 * @ovcs->cset changeset. If an added node has child nodes, they will
401 * be added recursively.
402 *
403 * Do not allow symbols node to have any children.
404 *
405 * Returns 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if
406 * invalid @overlay_node.
407 */
408static int build_changeset_next_level(struct overlay_changeset *ovcs,
409 struct device_node *target_node,
410 const struct device_node *overlay_node)
411{
412 struct device_node *child;
413 struct property *prop;
414 int ret;
415
416 for_each_property_of_node(overlay_node, prop) {
417 ret = add_changeset_property(ovcs, target_node, prop, 0);
418 if (ret) {
419 pr_debug("Failed to apply prop @%pOF/%s, err=%d\n",
420 target_node, prop->name, ret);
421 return ret;
422 }
423 }
424
425 for_each_child_of_node(overlay_node, child) {
426 ret = add_changeset_node(ovcs, target_node, child);
427 if (ret) {
428 pr_debug("Failed to apply node @%pOF/%s, err=%d\n",
429 target_node, child->name, ret);
430 of_node_put(child);
431 return ret;
432 }
433 }
434
435 return 0;
436}
437
438/*
439 * Add the properties from __overlay__ node to the @ovcs->cset changeset.
440 */
441static int build_changeset_symbols_node(struct overlay_changeset *ovcs,
442 struct device_node *target_node,
443 const struct device_node *overlay_symbols_node)
444{
445 struct property *prop;
446 int ret;
447
448 for_each_property_of_node(overlay_symbols_node, prop) {
449 ret = add_changeset_property(ovcs, target_node, prop, 1);
450 if (ret) {
451 pr_debug("Failed to apply prop @%pOF/%s, err=%d\n",
452 target_node, prop->name, ret);
453 return ret;
454 }
455 }
456
457 return 0;
458}
459
460/**
461 * build_changeset() - populate overlay changeset in @ovcs from @ovcs->fragments
462 * @ovcs: Overlay changeset
463 *
464 * Create changeset @ovcs->cset to contain the nodes and properties of the
465 * overlay device tree fragments in @ovcs->fragments[]. If an error occurs,
466 * any portions of the changeset that were successfully created will remain
467 * in @ovcs->cset.
468 *
469 * Returns 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if
470 * invalid overlay in @ovcs->fragments[].
471 */
472static int build_changeset(struct overlay_changeset *ovcs)
473{
474 struct fragment *fragment;
475 int fragments_count, i, ret;
476
477 /*
478 * if there is a symbols fragment in ovcs->fragments[i] it is
479 * the final element in the array
480 */
481 if (ovcs->symbols_fragment)
482 fragments_count = ovcs->count - 1;
483 else
484 fragments_count = ovcs->count;
485
486 for (i = 0; i < fragments_count; i++) {
487 fragment = &ovcs->fragments[i];
488
489 ret = build_changeset_next_level(ovcs, fragment->target,
490 fragment->overlay);
491 if (ret) {
492 pr_debug("apply failed '%pOF'\n", fragment->target);
493 return ret;
494 }
495 }
496
497 if (ovcs->symbols_fragment) {
498 fragment = &ovcs->fragments[ovcs->count - 1];
499 ret = build_changeset_symbols_node(ovcs, fragment->target,
500 fragment->overlay);
501 if (ret) {
502 pr_debug("apply failed '%pOF'\n", fragment->target);
503 return ret;
504 }
505 }
506
507 return 0;
508}
509
510/*
511 * Find the target node using a number of different strategies
512 * in order of preference:
513 *
514 * 1) "target" property containing the phandle of the target
515 * 2) "target-path" property containing the path of the target
516 */
517static struct device_node *find_target_node(struct device_node *info_node)
518{
519 struct device_node *node;
520 const char *path;
521 u32 val;
522 int ret;
523
524 ret = of_property_read_u32(info_node, "target", &val);
525 if (!ret) {
526 node = of_find_node_by_phandle(val);
527 if (!node)
528 pr_err("find target, node: %pOF, phandle 0x%x not found\n",
529 info_node, val);
530 return node;
531 }
532
533 ret = of_property_read_string(info_node, "target-path", &path);
534 if (!ret) {
535 node = of_find_node_by_path(path);
536 if (!node)
537 pr_err("find target, node: %pOF, path '%s' not found\n",
538 info_node, path);
539 return node;
540 }
541
542 pr_err("find target, node: %pOF, no target property\n", info_node);
543
544 return NULL;
545}
546
547/**
548 * init_overlay_changeset() - initialize overlay changeset from overlay tree
549 * @ovcs: Overlay changeset to build
550 * @fdt: the FDT that was unflattened to create @tree
551 * @tree: Contains all the overlay fragments and overlay fixup nodes
552 *
553 * Initialize @ovcs. Populate @ovcs->fragments with node information from
554 * the top level of @tree. The relevant top level nodes are the fragment
555 * nodes and the __symbols__ node. Any other top level node will be ignored.
556 *
557 * Returns 0 on success, -ENOMEM if memory allocation failure, -EINVAL if error
558 * detected in @tree, or -ENOSPC if idr_alloc() error.
559 */
560static int init_overlay_changeset(struct overlay_changeset *ovcs,
561 const void *fdt, struct device_node *tree)
562{
563 struct device_node *node, *overlay_node;
564 struct fragment *fragment;
565 struct fragment *fragments;
566 int cnt, id, ret;
567
568 /*
569 * Warn for some issues. Can not return -EINVAL for these until
570 * of_unittest_apply_overlay() is fixed to pass these checks.
571 */
572 if (!of_node_check_flag(tree, OF_DYNAMIC))
573 pr_debug("%s() tree is not dynamic\n", __func__);
574
575 if (!of_node_check_flag(tree, OF_DETACHED))
576 pr_debug("%s() tree is not detached\n", __func__);
577
578 if (!of_node_is_root(tree))
579 pr_debug("%s() tree is not root\n", __func__);
580
581 ovcs->overlay_tree = tree;
582 ovcs->fdt = fdt;
583
584 INIT_LIST_HEAD(&ovcs->ovcs_list);
585
586 of_changeset_init(&ovcs->cset);
587
588 id = idr_alloc(&ovcs_idr, ovcs, 1, 0, GFP_KERNEL);
589 if (id <= 0)
590 return id;
591
592 cnt = 0;
593
594 /* fragment nodes */
595 for_each_child_of_node(tree, node) {
596 overlay_node = of_get_child_by_name(node, "__overlay__");
597 if (overlay_node) {
598 cnt++;
599 of_node_put(overlay_node);
600 }
601 }
602
603 node = of_get_child_by_name(tree, "__symbols__");
604 if (node) {
605 cnt++;
606 of_node_put(node);
607 }
608
609 fragments = kcalloc(cnt, sizeof(*fragments), GFP_KERNEL);
610 if (!fragments) {
611 ret = -ENOMEM;
612 goto err_free_idr;
613 }
614
615 cnt = 0;
616 for_each_child_of_node(tree, node) {
617 overlay_node = of_get_child_by_name(node, "__overlay__");
618 if (!overlay_node)
619 continue;
620
621 fragment = &fragments[cnt];
622 fragment->overlay = overlay_node;
623 fragment->target = find_target_node(node);
624 if (!fragment->target) {
625 of_node_put(fragment->overlay);
626 ret = -EINVAL;
627 goto err_free_fragments;
628 }
629
630 cnt++;
631 }
632
633 /*
634 * if there is a symbols fragment in ovcs->fragments[i] it is
635 * the final element in the array
636 */
637 node = of_get_child_by_name(tree, "__symbols__");
638 if (node) {
639 ovcs->symbols_fragment = 1;
640 fragment = &fragments[cnt];
641 fragment->overlay = node;
642 fragment->target = of_find_node_by_path("/__symbols__");
643
644 if (!fragment->target) {
645 pr_err("symbols in overlay, but not in live tree\n");
646 ret = -EINVAL;
647 goto err_free_fragments;
648 }
649
650 cnt++;
651 }
652
653 if (!cnt) {
654 pr_err("no fragments or symbols in overlay\n");
655 ret = -EINVAL;
656 goto err_free_fragments;
657 }
658
659 ovcs->id = id;
660 ovcs->count = cnt;
661 ovcs->fragments = fragments;
662
663 return 0;
664
665err_free_fragments:
666 kfree(fragments);
667err_free_idr:
668 idr_remove(&ovcs_idr, id);
669
670 pr_err("%s() failed, ret = %d\n", __func__, ret);
671
672 return ret;
673}
674
675static void free_overlay_changeset(struct overlay_changeset *ovcs)
676{
677 int i;
678
679 if (ovcs->cset.entries.next)
680 of_changeset_destroy(&ovcs->cset);
681
682 if (ovcs->id)
683 idr_remove(&ovcs_idr, ovcs->id);
684
685 for (i = 0; i < ovcs->count; i++) {
686 of_node_put(ovcs->fragments[i].target);
687 of_node_put(ovcs->fragments[i].overlay);
688 }
689 kfree(ovcs->fragments);
690 /*
691 * There should be no live pointers into ovcs->overlay_tree and
692 * ovcs->fdt due to the policy that overlay notifiers are not allowed
693 * to retain pointers into the overlay devicetree.
694 */
695 kfree(ovcs->overlay_tree);
696 kfree(ovcs->fdt);
697 kfree(ovcs);
698}
699
700/*
701 * internal documentation
702 *
703 * of_overlay_apply() - Create and apply an overlay changeset
704 * @fdt: the FDT that was unflattened to create @tree
705 * @tree: Expanded overlay device tree
706 * @ovcs_id: Pointer to overlay changeset id
707 *
708 * Creates and applies an overlay changeset.
709 *
710 * If an error occurs in a pre-apply notifier, then no changes are made
711 * to the device tree.
712 *
713
714 * A non-zero return value will not have created the changeset if error is from:
715 * - parameter checks
716 * - building the changeset
717 * - overlay changeset pre-apply notifier
718 *
719 * If an error is returned by an overlay changeset pre-apply notifier
720 * then no further overlay changeset pre-apply notifier will be called.
721 *
722 * A non-zero return value will have created the changeset if error is from:
723 * - overlay changeset entry notifier
724 * - overlay changeset post-apply notifier
725 *
726 * If an error is returned by an overlay changeset post-apply notifier
727 * then no further overlay changeset post-apply notifier will be called.
728 *
729 * If more than one notifier returns an error, then the last notifier
730 * error to occur is returned.
731 *
732 * If an error occurred while applying the overlay changeset, then an
733 * attempt is made to revert any changes that were made to the
734 * device tree. If there were any errors during the revert attempt
735 * then the state of the device tree can not be determined, and any
736 * following attempt to apply or remove an overlay changeset will be
737 * refused.
738 *
739 * Returns 0 on success, or a negative error number. Overlay changeset
740 * id is returned to *ovcs_id.
741 */
742
743static int of_overlay_apply(const void *fdt, struct device_node *tree,
744 int *ovcs_id)
745{
746 struct overlay_changeset *ovcs;
747 int ret = 0, ret_revert, ret_tmp;
748
749 /*
750 * As of this point, fdt and tree belong to the overlay changeset.
751 * overlay changeset code is responsible for freeing them.
752 */
753
754 if (devicetree_corrupt()) {
755 pr_err("devicetree state suspect, refuse to apply overlay\n");
756 kfree(fdt);
757 kfree(tree);
758 ret = -EBUSY;
759 goto out;
760 }
761
762 ovcs = kzalloc(sizeof(*ovcs), GFP_KERNEL);
763 if (!ovcs) {
764 kfree(fdt);
765 kfree(tree);
766 ret = -ENOMEM;
767 goto out;
768 }
769
770 of_overlay_mutex_lock();
771 mutex_lock(&of_mutex);
772
773 ret = of_resolve_phandles(tree);
774 if (ret)
775 goto err_free_tree;
776
777 ret = init_overlay_changeset(ovcs, fdt, tree);
778 if (ret)
779 goto err_free_tree;
780
781 /*
782 * after overlay_notify(), ovcs->overlay_tree related pointers may have
783 * leaked to drivers, so can not kfree() tree, aka ovcs->overlay_tree;
784 * and can not free fdt, aka ovcs->fdt
785 */
786 ret = overlay_notify(ovcs, OF_OVERLAY_PRE_APPLY);
787 if (ret) {
788 pr_err("overlay changeset pre-apply notify error %d\n", ret);
789 goto err_free_overlay_changeset;
790 }
791
792 ret = build_changeset(ovcs);
793 if (ret)
794 goto err_free_overlay_changeset;
795
796 ret_revert = 0;
797 ret = __of_changeset_apply_entries(&ovcs->cset, &ret_revert);
798 if (ret) {
799 if (ret_revert) {
800 pr_debug("overlay changeset revert error %d\n",
801 ret_revert);
802 devicetree_state_flags |= DTSF_APPLY_FAIL;
803 }
804 goto err_free_overlay_changeset;
805 }
806
807 ret = __of_changeset_apply_notify(&ovcs->cset);
808 if (ret)
809 pr_err("overlay changeset entry notify error %d\n", ret);
810 /* notify failure is not fatal, continue */
811
812 list_add_tail(&ovcs->ovcs_list, &ovcs_list);
813 *ovcs_id = ovcs->id;
814
815 ret_tmp = overlay_notify(ovcs, OF_OVERLAY_POST_APPLY);
816 if (ret_tmp) {
817 pr_err("overlay changeset post-apply notify error %d\n",
818 ret_tmp);
819 if (!ret)
820 ret = ret_tmp;
821 }
822
823 goto out_unlock;
824
825err_free_tree:
826 kfree(fdt);
827 kfree(tree);
828
829err_free_overlay_changeset:
830 free_overlay_changeset(ovcs);
831
832out_unlock:
833 mutex_unlock(&of_mutex);
834 of_overlay_mutex_unlock();
835
836out:
837 pr_debug("%s() err=%d\n", __func__, ret);
838
839 return ret;
840}
841
842int of_overlay_fdt_apply(const void *overlay_fdt, u32 overlay_fdt_size,
843 int *ovcs_id)
844{
845 const void *new_fdt;
846 int ret;
847 u32 size;
848 struct device_node *overlay_root;
849
850 *ovcs_id = 0;
851 ret = 0;
852
853 if (overlay_fdt_size < sizeof(struct fdt_header) ||
854 fdt_check_header(overlay_fdt)) {
855 pr_err("Invalid overlay_fdt header\n");
856 return -EINVAL;
857 }
858
859 size = fdt_totalsize(overlay_fdt);
860 if (overlay_fdt_size < size)
861 return -EINVAL;
862
863 /*
864 * Must create permanent copy of FDT because of_fdt_unflatten_tree()
865 * will create pointers to the passed in FDT in the unflattened tree.
866 */
867 new_fdt = kmemdup(overlay_fdt, size, GFP_KERNEL);
868 if (!new_fdt)
869 return -ENOMEM;
870
871 of_fdt_unflatten_tree(new_fdt, NULL, &overlay_root);
872 if (!overlay_root) {
873 pr_err("unable to unflatten overlay_fdt\n");
874 ret = -EINVAL;
875 goto out_free_new_fdt;
876 }
877
878 ret = of_overlay_apply(new_fdt, overlay_root, ovcs_id);
879 if (ret < 0) {
880 /*
881 * new_fdt and overlay_root now belong to the overlay
882 * changeset.
883 * overlay changeset code is responsible for freeing them.
884 */
885 goto out;
886 }
887
888 return 0;
889
890
891out_free_new_fdt:
892 kfree(new_fdt);
893
894out:
895 return ret;
896}
897EXPORT_SYMBOL_GPL(of_overlay_fdt_apply);
898
899/*
900 * Find @np in @tree.
901 *
902 * Returns 1 if @np is @tree or is contained in @tree, else 0
903 */
904static int find_node(struct device_node *tree, struct device_node *np)
905{
906 struct device_node *child;
907
908 if (tree == np)
909 return 1;
910
911 for_each_child_of_node(tree, child) {
912 if (find_node(child, np)) {
913 of_node_put(child);
914 return 1;
915 }
916 }
917
918 return 0;
919}
920
921/*
922 * Is @remove_ce_node a child of, a parent of, or the same as any
923 * node in an overlay changeset more topmost than @remove_ovcs?
924 *
925 * Returns 1 if found, else 0
926 */
927static int node_overlaps_later_cs(struct overlay_changeset *remove_ovcs,
928 struct device_node *remove_ce_node)
929{
930 struct overlay_changeset *ovcs;
931 struct of_changeset_entry *ce;
932
933 list_for_each_entry_reverse(ovcs, &ovcs_list, ovcs_list) {
934 if (ovcs == remove_ovcs)
935 break;
936
937 list_for_each_entry(ce, &ovcs->cset.entries, node) {
938 if (find_node(ce->np, remove_ce_node)) {
939 pr_err("%s: #%d overlaps with #%d @%pOF\n",
940 __func__, remove_ovcs->id, ovcs->id,
941 remove_ce_node);
942 return 1;
943 }
944 if (find_node(remove_ce_node, ce->np)) {
945 pr_err("%s: #%d overlaps with #%d @%pOF\n",
946 __func__, remove_ovcs->id, ovcs->id,
947 remove_ce_node);
948 return 1;
949 }
950 }
951 }
952
953 return 0;
954}
955
956/*
957 * We can safely remove the overlay only if it's the top-most one.
958 * Newly applied overlays are inserted at the tail of the overlay list,
959 * so a top most overlay is the one that is closest to the tail.
960 *
961 * The topmost check is done by exploiting this property. For each
962 * affected device node in the log list we check if this overlay is
963 * the one closest to the tail. If another overlay has affected this
964 * device node and is closest to the tail, then removal is not permited.
965 */
966static int overlay_removal_is_ok(struct overlay_changeset *remove_ovcs)
967{
968 struct of_changeset_entry *remove_ce;
969
970 list_for_each_entry(remove_ce, &remove_ovcs->cset.entries, node) {
971 if (node_overlaps_later_cs(remove_ovcs, remove_ce->np)) {
972 pr_err("overlay #%d is not topmost\n", remove_ovcs->id);
973 return 0;
974 }
975 }
976
977 return 1;
978}
979
980/**
981 * of_overlay_remove() - Revert and free an overlay changeset
982 * @ovcs_id: Pointer to overlay changeset id
983 *
984 * Removes an overlay if it is permissible. @ovcs_id was previously returned
985 * by of_overlay_fdt_apply().
986 *
987 * If an error occurred while attempting to revert the overlay changeset,
988 * then an attempt is made to re-apply any changeset entry that was
989 * reverted. If an error occurs on re-apply then the state of the device
990 * tree can not be determined, and any following attempt to apply or remove
991 * an overlay changeset will be refused.
992 *
993 * A non-zero return value will not revert the changeset if error is from:
994 * - parameter checks
995 * - overlay changeset pre-remove notifier
996 * - overlay changeset entry revert
997 *
998 * If an error is returned by an overlay changeset pre-remove notifier
999 * then no further overlay changeset pre-remove notifier will be called.
1000 *
1001 * If more than one notifier returns an error, then the last notifier
1002 * error to occur is returned.
1003 *
1004 * A non-zero return value will revert the changeset if error is from:
1005 * - overlay changeset entry notifier
1006 * - overlay changeset post-remove notifier
1007 *
1008 * If an error is returned by an overlay changeset post-remove notifier
1009 * then no further overlay changeset post-remove notifier will be called.
1010 *
1011 * Returns 0 on success, or a negative error number. *ovcs_id is set to
1012 * zero after reverting the changeset, even if a subsequent error occurs.
1013 */
1014int of_overlay_remove(int *ovcs_id)
1015{
1016 struct overlay_changeset *ovcs;
1017 int ret, ret_apply, ret_tmp;
1018
1019 ret = 0;
1020
1021 if (devicetree_corrupt()) {
1022 pr_err("suspect devicetree state, refuse to remove overlay\n");
1023 ret = -EBUSY;
1024 goto out;
1025 }
1026
1027 mutex_lock(&of_mutex);
1028
1029 ovcs = idr_find(&ovcs_idr, *ovcs_id);
1030 if (!ovcs) {
1031 ret = -ENODEV;
1032 pr_err("remove: Could not find overlay #%d\n", *ovcs_id);
1033 goto out_unlock;
1034 }
1035
1036 if (!overlay_removal_is_ok(ovcs)) {
1037 ret = -EBUSY;
1038 goto out_unlock;
1039 }
1040
1041 ret = overlay_notify(ovcs, OF_OVERLAY_PRE_REMOVE);
1042 if (ret) {
1043 pr_err("overlay changeset pre-remove notify error %d\n", ret);
1044 goto out_unlock;
1045 }
1046
1047 list_del(&ovcs->ovcs_list);
1048
1049 ret_apply = 0;
1050 ret = __of_changeset_revert_entries(&ovcs->cset, &ret_apply);
1051 if (ret) {
1052 if (ret_apply)
1053 devicetree_state_flags |= DTSF_REVERT_FAIL;
1054 goto out_unlock;
1055 }
1056
1057 ret = __of_changeset_revert_notify(&ovcs->cset);
1058 if (ret)
1059 pr_err("overlay changeset entry notify error %d\n", ret);
1060 /* notify failure is not fatal, continue */
1061
1062 *ovcs_id = 0;
1063
1064 ret_tmp = overlay_notify(ovcs, OF_OVERLAY_POST_REMOVE);
1065 if (ret_tmp) {
1066 pr_err("overlay changeset post-remove notify error %d\n",
1067 ret_tmp);
1068 if (!ret)
1069 ret = ret_tmp;
1070 }
1071
1072 free_overlay_changeset(ovcs);
1073
1074out_unlock:
1075 mutex_unlock(&of_mutex);
1076
1077out:
1078 pr_debug("%s() err=%d\n", __func__, ret);
1079
1080 return ret;
1081}
1082EXPORT_SYMBOL_GPL(of_overlay_remove);
1083
1084/**
1085 * of_overlay_remove_all() - Reverts and frees all overlay changesets
1086 *
1087 * Removes all overlays from the system in the correct order.
1088 *
1089 * Returns 0 on success, or a negative error number
1090 */
1091int of_overlay_remove_all(void)
1092{
1093 struct overlay_changeset *ovcs, *ovcs_n;
1094 int ret;
1095
1096 /* the tail of list is guaranteed to be safe to remove */
1097 list_for_each_entry_safe_reverse(ovcs, ovcs_n, &ovcs_list, ovcs_list) {
1098 ret = of_overlay_remove(&ovcs->id);
1099 if (ret)
1100 return ret;
1101 }
1102
1103 return 0;
1104}
1105EXPORT_SYMBOL_GPL(of_overlay_remove_all);