1 // SPDX-License-Identifier: GPL-2.0
3 * Functions for working with device tree overlays
5 * Copyright (C) 2012 Pantelis Antoniou <panto@antoniou-consulting.com>
6 * Copyright (C) 2012 Texas Instruments Inc.
9 #define pr_fmt(fmt) "OF: overlay: " fmt
11 #include <linux/kernel.h>
12 #include <linux/module.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>
24 #include "of_private.h"
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
32 struct device_node *target;
33 struct device_node *overlay;
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
47 struct overlay_changeset {
49 struct list_head ovcs_list;
51 struct device_node *overlay_tree;
53 struct fragment *fragments;
54 bool symbols_fragment;
55 struct of_changeset cset;
58 /* flags are sticky - once set, do not reset */
59 static int devicetree_state_flags;
60 #define DTSF_APPLY_FAIL 0x01
61 #define DTSF_REVERT_FAIL 0x02
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.
68 static int devicetree_corrupt(void)
70 return devicetree_state_flags &
71 (DTSF_APPLY_FAIL | DTSF_REVERT_FAIL);
74 static int build_changeset_next_level(struct overlay_changeset *ovcs,
75 struct device_node *target_node,
76 const struct device_node *overlay_node);
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()
85 * mutex_unlock(&of_overlay_phandle_mutex)
87 static DEFINE_MUTEX(of_overlay_phandle_mutex);
89 void of_overlay_mutex_lock(void)
91 mutex_lock(&of_overlay_phandle_mutex);
94 void of_overlay_mutex_unlock(void)
96 mutex_unlock(&of_overlay_phandle_mutex);
100 static LIST_HEAD(ovcs_list);
101 static DEFINE_IDR(ovcs_idr);
103 static BLOCKING_NOTIFIER_HEAD(overlay_notify_chain);
105 int of_overlay_notifier_register(struct notifier_block *nb)
107 return blocking_notifier_chain_register(&overlay_notify_chain, nb);
109 EXPORT_SYMBOL_GPL(of_overlay_notifier_register);
111 int of_overlay_notifier_unregister(struct notifier_block *nb)
113 return blocking_notifier_chain_unregister(&overlay_notify_chain, nb);
115 EXPORT_SYMBOL_GPL(of_overlay_notifier_unregister);
117 static char *of_overlay_action_name[] = {
124 static int overlay_notify(struct overlay_changeset *ovcs,
125 enum of_overlay_notify_action action)
127 struct of_overlay_notify_data nd;
130 for (i = 0; i < ovcs->count; i++) {
131 struct fragment *fragment = &ovcs->fragments[i];
133 nd.target = fragment->target;
134 nd.overlay = fragment->overlay;
136 ret = blocking_notifier_call_chain(&overlay_notify_chain,
138 if (ret == NOTIFY_OK || ret == NOTIFY_STOP)
141 ret = notifier_to_errno(ret);
142 pr_err("overlay changeset %s notifier error %d, target: %pOF\n",
143 of_overlay_action_name[action], ret, nd.target);
152 * The values of properties in the "/__symbols__" node are paths in
153 * the ovcs->overlay_tree. When duplicating the properties, the paths
154 * need to be adjusted to be the correct path for the live device tree.
156 * The paths refer to a node in the subtree of a fragment node's "__overlay__"
157 * node, for example "/fragment@0/__overlay__/symbol_path_tail",
158 * where symbol_path_tail can be a single node or it may be a multi-node path.
160 * The duplicated property value will be modified by replacing the
161 * "/fragment_name/__overlay/" portion of the value with the target
162 * path from the fragment node.
164 static struct property *dup_and_fixup_symbol_prop(
165 struct overlay_changeset *ovcs, const struct property *prop)
167 struct fragment *fragment;
168 struct property *new_prop;
169 struct device_node *fragment_node;
170 struct device_node *overlay_node;
172 const char *path_tail;
173 const char *target_path;
175 int overlay_name_len;
182 if (strnlen(prop->value, prop->length) >= prop->length)
185 path_len = strlen(path);
189 fragment_node = __of_find_node_by_path(ovcs->overlay_tree, path + 1);
190 overlay_node = __of_find_node_by_path(fragment_node, "__overlay__/");
191 of_node_put(fragment_node);
192 of_node_put(overlay_node);
194 for (k = 0; k < ovcs->count; k++) {
195 fragment = &ovcs->fragments[k];
196 if (fragment->overlay == overlay_node)
199 if (k >= ovcs->count)
202 overlay_name_len = snprintf(NULL, 0, "%pOF", fragment->overlay);
204 if (overlay_name_len > path_len)
206 path_tail = path + overlay_name_len;
207 path_tail_len = strlen(path_tail);
209 target_path = kasprintf(GFP_KERNEL, "%pOF", fragment->target);
212 target_path_len = strlen(target_path);
214 new_prop = kzalloc(sizeof(*new_prop), GFP_KERNEL);
216 goto err_free_target_path;
218 new_prop->name = kstrdup(prop->name, GFP_KERNEL);
219 new_prop->length = target_path_len + path_tail_len + 1;
220 new_prop->value = kzalloc(new_prop->length, GFP_KERNEL);
221 if (!new_prop->name || !new_prop->value)
222 goto err_free_new_prop;
224 strcpy(new_prop->value, target_path);
225 strcpy(new_prop->value + target_path_len, path_tail);
227 of_property_set_flag(new_prop, OF_DYNAMIC);
232 kfree(new_prop->name);
233 kfree(new_prop->value);
235 err_free_target_path:
242 * add_changeset_property() - add @overlay_prop to overlay changeset
243 * @ovcs: overlay changeset
244 * @target_node: where to place @overlay_prop in live tree
245 * @overlay_prop: property to add or update, from overlay tree
246 * @is_symbols_prop: 1 if @overlay_prop is from node "/__symbols__"
248 * If @overlay_prop does not already exist in @target_node, add changeset entry
249 * to add @overlay_prop in @target_node, else add changeset entry to update
250 * value of @overlay_prop.
252 * Some special properties are not updated (no error returned).
254 * Update of property in symbols node is not allowed.
256 * Returns 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if
259 static int add_changeset_property(struct overlay_changeset *ovcs,
260 struct device_node *target_node,
261 struct property *overlay_prop,
262 bool is_symbols_prop)
264 struct property *new_prop = NULL, *prop;
267 prop = of_find_property(target_node, overlay_prop->name, NULL);
269 if (!of_prop_cmp(overlay_prop->name, "name") ||
270 !of_prop_cmp(overlay_prop->name, "phandle") ||
271 !of_prop_cmp(overlay_prop->name, "linux,phandle"))
274 if (is_symbols_prop) {
277 new_prop = dup_and_fixup_symbol_prop(ovcs, overlay_prop);
279 new_prop = __of_prop_dup(overlay_prop, GFP_KERNEL);
286 ret = of_changeset_add_property(&ovcs->cset, target_node,
289 ret = of_changeset_update_property(&ovcs->cset, target_node,
293 kfree(new_prop->name);
294 kfree(new_prop->value);
301 * add_changeset_node() - add @node (and children) to overlay changeset
302 * @ovcs: overlay changeset
303 * @target_node: where to place @node in live tree
304 * @node: node from within overlay device tree fragment
306 * If @node does not already exist in @target_node, add changeset entry
307 * to add @node in @target_node.
309 * If @node already exists in @target_node, and the existing node has
310 * a phandle, the overlay node is not allowed to have a phandle.
312 * If @node has child nodes, add the children recursively via
313 * build_changeset_next_level().
315 * NOTE: Multiple mods of created nodes not supported.
316 * If more than one fragment contains a node that does not already exist
317 * in the live tree, then for each fragment of_changeset_attach_node()
318 * will add a changeset entry to add the node. When the changeset is
319 * applied, __of_attach_node() will attach the node twice (once for
320 * each fragment). At this point the device tree will be corrupted.
322 * TODO: add integrity check to ensure that multiple fragments do not
323 * create the same node.
325 * Returns 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if
328 static int add_changeset_node(struct overlay_changeset *ovcs,
329 struct device_node *target_node, struct device_node *node)
331 const char *node_kbasename;
332 struct device_node *tchild;
335 node_kbasename = kbasename(node->full_name);
337 for_each_child_of_node(target_node, tchild)
338 if (!of_node_cmp(node_kbasename, kbasename(tchild->full_name)))
342 tchild = __of_node_dup(node, "%pOF/%s",
343 target_node, node_kbasename);
347 tchild->parent = target_node;
349 ret = of_changeset_attach_node(&ovcs->cset, tchild);
353 return build_changeset_next_level(ovcs, tchild, node);
356 if (node->phandle && tchild->phandle)
359 ret = build_changeset_next_level(ovcs, tchild, node);
366 * build_changeset_next_level() - add level of overlay changeset
367 * @ovcs: overlay changeset
368 * @target_node: where to place @overlay_node in live tree
369 * @overlay_node: node from within an overlay device tree fragment
371 * Add the properties (if any) and nodes (if any) from @overlay_node to the
372 * @ovcs->cset changeset. If an added node has child nodes, they will
373 * be added recursively.
375 * Do not allow symbols node to have any children.
377 * Returns 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if
378 * invalid @overlay_node.
380 static int build_changeset_next_level(struct overlay_changeset *ovcs,
381 struct device_node *target_node,
382 const struct device_node *overlay_node)
384 struct device_node *child;
385 struct property *prop;
388 for_each_property_of_node(overlay_node, prop) {
389 ret = add_changeset_property(ovcs, target_node, prop, 0);
391 pr_debug("Failed to apply prop @%pOF/%s, err=%d\n",
392 target_node, prop->name, ret);
397 for_each_child_of_node(overlay_node, child) {
398 ret = add_changeset_node(ovcs, target_node, child);
400 pr_debug("Failed to apply node @%pOF/%s, err=%d\n",
401 target_node, child->name, ret);
411 * Add the properties from __overlay__ node to the @ovcs->cset changeset.
413 static int build_changeset_symbols_node(struct overlay_changeset *ovcs,
414 struct device_node *target_node,
415 const struct device_node *overlay_symbols_node)
417 struct property *prop;
420 for_each_property_of_node(overlay_symbols_node, prop) {
421 ret = add_changeset_property(ovcs, target_node, prop, 1);
423 pr_debug("Failed to apply prop @%pOF/%s, err=%d\n",
424 target_node, prop->name, ret);
433 * build_changeset() - populate overlay changeset in @ovcs from @ovcs->fragments
434 * @ovcs: Overlay changeset
436 * Create changeset @ovcs->cset to contain the nodes and properties of the
437 * overlay device tree fragments in @ovcs->fragments[]. If an error occurs,
438 * any portions of the changeset that were successfully created will remain
441 * Returns 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if
442 * invalid overlay in @ovcs->fragments[].
444 static int build_changeset(struct overlay_changeset *ovcs)
446 struct fragment *fragment;
447 int fragments_count, i, ret;
450 * if there is a symbols fragment in ovcs->fragments[i] it is
451 * the final element in the array
453 if (ovcs->symbols_fragment)
454 fragments_count = ovcs->count - 1;
456 fragments_count = ovcs->count;
458 for (i = 0; i < fragments_count; i++) {
459 fragment = &ovcs->fragments[i];
461 ret = build_changeset_next_level(ovcs, fragment->target,
464 pr_debug("apply failed '%pOF'\n", fragment->target);
469 if (ovcs->symbols_fragment) {
470 fragment = &ovcs->fragments[ovcs->count - 1];
471 ret = build_changeset_symbols_node(ovcs, fragment->target,
474 pr_debug("apply failed '%pOF'\n", fragment->target);
483 * Find the target node using a number of different strategies
484 * in order of preference:
486 * 1) "target" property containing the phandle of the target
487 * 2) "target-path" property containing the path of the target
489 static struct device_node *find_target_node(struct device_node *info_node)
491 struct device_node *node;
496 ret = of_property_read_u32(info_node, "target", &val);
498 node = of_find_node_by_phandle(val);
500 pr_err("find target, node: %pOF, phandle 0x%x not found\n",
505 ret = of_property_read_string(info_node, "target-path", &path);
507 node = of_find_node_by_path(path);
509 pr_err("find target, node: %pOF, path '%s' not found\n",
514 pr_err("find target, node: %pOF, no target property\n", info_node);
520 * init_overlay_changeset() - initialize overlay changeset from overlay tree
521 * @ovcs: Overlay changeset to build
522 * @fdt: the FDT that was unflattened to create @tree
523 * @tree: Contains all the overlay fragments and overlay fixup nodes
525 * Initialize @ovcs. Populate @ovcs->fragments with node information from
526 * the top level of @tree. The relevant top level nodes are the fragment
527 * nodes and the __symbols__ node. Any other top level node will be ignored.
529 * Returns 0 on success, -ENOMEM if memory allocation failure, -EINVAL if error
530 * detected in @tree, or -ENOSPC if idr_alloc() error.
532 static int init_overlay_changeset(struct overlay_changeset *ovcs,
533 const void *fdt, struct device_node *tree)
535 struct device_node *node, *overlay_node;
536 struct fragment *fragment;
537 struct fragment *fragments;
541 * Warn for some issues. Can not return -EINVAL for these until
542 * of_unittest_apply_overlay() is fixed to pass these checks.
544 if (!of_node_check_flag(tree, OF_DYNAMIC))
545 pr_debug("%s() tree is not dynamic\n", __func__);
547 if (!of_node_check_flag(tree, OF_DETACHED))
548 pr_debug("%s() tree is not detached\n", __func__);
550 if (!of_node_is_root(tree))
551 pr_debug("%s() tree is not root\n", __func__);
553 ovcs->overlay_tree = tree;
556 INIT_LIST_HEAD(&ovcs->ovcs_list);
558 of_changeset_init(&ovcs->cset);
560 id = idr_alloc(&ovcs_idr, ovcs, 1, 0, GFP_KERNEL);
567 for_each_child_of_node(tree, node) {
568 overlay_node = of_get_child_by_name(node, "__overlay__");
571 of_node_put(overlay_node);
575 node = of_get_child_by_name(tree, "__symbols__");
581 fragments = kcalloc(cnt, sizeof(*fragments), GFP_KERNEL);
588 for_each_child_of_node(tree, node) {
589 overlay_node = of_get_child_by_name(node, "__overlay__");
593 fragment = &fragments[cnt];
594 fragment->overlay = overlay_node;
595 fragment->target = find_target_node(node);
596 if (!fragment->target) {
597 of_node_put(fragment->overlay);
599 goto err_free_fragments;
606 * if there is a symbols fragment in ovcs->fragments[i] it is
607 * the final element in the array
609 node = of_get_child_by_name(tree, "__symbols__");
611 ovcs->symbols_fragment = 1;
612 fragment = &fragments[cnt];
613 fragment->overlay = node;
614 fragment->target = of_find_node_by_path("/__symbols__");
616 if (!fragment->target) {
617 pr_err("symbols in overlay, but not in live tree\n");
619 goto err_free_fragments;
626 pr_err("no fragments or symbols in overlay\n");
628 goto err_free_fragments;
633 ovcs->fragments = fragments;
640 idr_remove(&ovcs_idr, id);
642 pr_err("%s() failed, ret = %d\n", __func__, ret);
647 static void free_overlay_changeset(struct overlay_changeset *ovcs)
651 if (ovcs->cset.entries.next)
652 of_changeset_destroy(&ovcs->cset);
655 idr_remove(&ovcs_idr, ovcs->id);
657 for (i = 0; i < ovcs->count; i++) {
658 of_node_put(ovcs->fragments[i].target);
659 of_node_put(ovcs->fragments[i].overlay);
661 kfree(ovcs->fragments);
666 * would like to: kfree(ovcs->overlay_tree);
667 * but can not since drivers may have pointers into this data
669 * would like to: kfree(ovcs->fdt);
670 * but can not since drivers may have pointers into this data
677 * internal documentation
679 * of_overlay_apply() - Create and apply an overlay changeset
680 * @fdt: the FDT that was unflattened to create @tree
681 * @tree: Expanded overlay device tree
682 * @ovcs_id: Pointer to overlay changeset id
684 * Creates and applies an overlay changeset.
686 * If an error occurs in a pre-apply notifier, then no changes are made
687 * to the device tree.
690 * A non-zero return value will not have created the changeset if error is from:
692 * - building the changeset
693 * - overlay changeset pre-apply notifier
695 * If an error is returned by an overlay changeset pre-apply notifier
696 * then no further overlay changeset pre-apply notifier will be called.
698 * A non-zero return value will have created the changeset if error is from:
699 * - overlay changeset entry notifier
700 * - overlay changeset post-apply notifier
702 * If an error is returned by an overlay changeset post-apply notifier
703 * then no further overlay changeset post-apply notifier will be called.
705 * If more than one notifier returns an error, then the last notifier
706 * error to occur is returned.
708 * If an error occurred while applying the overlay changeset, then an
709 * attempt is made to revert any changes that were made to the
710 * device tree. If there were any errors during the revert attempt
711 * then the state of the device tree can not be determined, and any
712 * following attempt to apply or remove an overlay changeset will be
715 * Returns 0 on success, or a negative error number. Overlay changeset
716 * id is returned to *ovcs_id.
719 static int of_overlay_apply(const void *fdt, struct device_node *tree,
722 struct overlay_changeset *ovcs;
723 int ret = 0, ret_revert, ret_tmp;
726 * As of this point, fdt and tree belong to the overlay changeset.
727 * overlay changeset code is responsible for freeing them.
730 if (devicetree_corrupt()) {
731 pr_err("devicetree state suspect, refuse to apply overlay\n");
738 ovcs = kzalloc(sizeof(*ovcs), GFP_KERNEL);
746 of_overlay_mutex_lock();
747 mutex_lock(&of_mutex);
749 ret = of_resolve_phandles(tree);
753 ret = init_overlay_changeset(ovcs, fdt, tree);
758 * after overlay_notify(), ovcs->overlay_tree related pointers may have
759 * leaked to drivers, so can not kfree() tree, aka ovcs->overlay_tree;
760 * and can not free fdt, aka ovcs->fdt
762 ret = overlay_notify(ovcs, OF_OVERLAY_PRE_APPLY);
764 pr_err("overlay changeset pre-apply notify error %d\n", ret);
765 goto err_free_overlay_changeset;
768 ret = build_changeset(ovcs);
770 goto err_free_overlay_changeset;
773 ret = __of_changeset_apply_entries(&ovcs->cset, &ret_revert);
776 pr_debug("overlay changeset revert error %d\n",
778 devicetree_state_flags |= DTSF_APPLY_FAIL;
780 goto err_free_overlay_changeset;
783 ret = __of_changeset_apply_notify(&ovcs->cset);
785 pr_err("overlay changeset entry notify error %d\n", ret);
786 /* notify failure is not fatal, continue */
788 list_add_tail(&ovcs->ovcs_list, &ovcs_list);
791 ret_tmp = overlay_notify(ovcs, OF_OVERLAY_POST_APPLY);
793 pr_err("overlay changeset post-apply notify error %d\n",
805 err_free_overlay_changeset:
806 free_overlay_changeset(ovcs);
809 mutex_unlock(&of_mutex);
810 of_overlay_mutex_unlock();
813 pr_debug("%s() err=%d\n", __func__, ret);
818 int of_overlay_fdt_apply(const void *overlay_fdt, u32 overlay_fdt_size,
824 struct device_node *overlay_root;
829 if (overlay_fdt_size < sizeof(struct fdt_header) ||
830 fdt_check_header(overlay_fdt)) {
831 pr_err("Invalid overlay_fdt header\n");
835 size = fdt_totalsize(overlay_fdt);
836 if (overlay_fdt_size < size)
840 * Must create permanent copy of FDT because of_fdt_unflatten_tree()
841 * will create pointers to the passed in FDT in the unflattened tree.
843 new_fdt = kmemdup(overlay_fdt, size, GFP_KERNEL);
847 of_fdt_unflatten_tree(new_fdt, NULL, &overlay_root);
849 pr_err("unable to unflatten overlay_fdt\n");
851 goto out_free_new_fdt;
854 ret = of_overlay_apply(new_fdt, overlay_root, ovcs_id);
857 * new_fdt and overlay_root now belong to the overlay
859 * overlay changeset code is responsible for freeing them.
873 EXPORT_SYMBOL_GPL(of_overlay_fdt_apply);
878 * Returns 1 if @np is @tree or is contained in @tree, else 0
880 static int find_node(struct device_node *tree, struct device_node *np)
882 struct device_node *child;
887 for_each_child_of_node(tree, child) {
888 if (find_node(child, np)) {
898 * Is @remove_ce_node a child of, a parent of, or the same as any
899 * node in an overlay changeset more topmost than @remove_ovcs?
901 * Returns 1 if found, else 0
903 static int node_overlaps_later_cs(struct overlay_changeset *remove_ovcs,
904 struct device_node *remove_ce_node)
906 struct overlay_changeset *ovcs;
907 struct of_changeset_entry *ce;
909 list_for_each_entry_reverse(ovcs, &ovcs_list, ovcs_list) {
910 if (ovcs == remove_ovcs)
913 list_for_each_entry(ce, &ovcs->cset.entries, node) {
914 if (find_node(ce->np, remove_ce_node)) {
915 pr_err("%s: #%d overlaps with #%d @%pOF\n",
916 __func__, remove_ovcs->id, ovcs->id,
920 if (find_node(remove_ce_node, ce->np)) {
921 pr_err("%s: #%d overlaps with #%d @%pOF\n",
922 __func__, remove_ovcs->id, ovcs->id,
933 * We can safely remove the overlay only if it's the top-most one.
934 * Newly applied overlays are inserted at the tail of the overlay list,
935 * so a top most overlay is the one that is closest to the tail.
937 * The topmost check is done by exploiting this property. For each
938 * affected device node in the log list we check if this overlay is
939 * the one closest to the tail. If another overlay has affected this
940 * device node and is closest to the tail, then removal is not permited.
942 static int overlay_removal_is_ok(struct overlay_changeset *remove_ovcs)
944 struct of_changeset_entry *remove_ce;
946 list_for_each_entry(remove_ce, &remove_ovcs->cset.entries, node) {
947 if (node_overlaps_later_cs(remove_ovcs, remove_ce->np)) {
948 pr_err("overlay #%d is not topmost\n", remove_ovcs->id);
957 * of_overlay_remove() - Revert and free an overlay changeset
958 * @ovcs_id: Pointer to overlay changeset id
960 * Removes an overlay if it is permissible. @ovcs_id was previously returned
961 * by of_overlay_apply().
963 * If an error occurred while attempting to revert the overlay changeset,
964 * then an attempt is made to re-apply any changeset entry that was
965 * reverted. If an error occurs on re-apply then the state of the device
966 * tree can not be determined, and any following attempt to apply or remove
967 * an overlay changeset will be refused.
969 * A non-zero return value will not revert the changeset if error is from:
971 * - overlay changeset pre-remove notifier
972 * - overlay changeset entry revert
974 * If an error is returned by an overlay changeset pre-remove notifier
975 * then no further overlay changeset pre-remove notifier will be called.
977 * If more than one notifier returns an error, then the last notifier
978 * error to occur is returned.
980 * A non-zero return value will revert the changeset if error is from:
981 * - overlay changeset entry notifier
982 * - overlay changeset post-remove notifier
984 * If an error is returned by an overlay changeset post-remove notifier
985 * then no further overlay changeset post-remove notifier will be called.
987 * Returns 0 on success, or a negative error number. *ovcs_id is set to
988 * zero after reverting the changeset, even if a subsequent error occurs.
990 int of_overlay_remove(int *ovcs_id)
992 struct overlay_changeset *ovcs;
993 int ret, ret_apply, ret_tmp;
997 if (devicetree_corrupt()) {
998 pr_err("suspect devicetree state, refuse to remove overlay\n");
1003 mutex_lock(&of_mutex);
1005 ovcs = idr_find(&ovcs_idr, *ovcs_id);
1008 pr_err("remove: Could not find overlay #%d\n", *ovcs_id);
1012 if (!overlay_removal_is_ok(ovcs)) {
1017 ret = overlay_notify(ovcs, OF_OVERLAY_PRE_REMOVE);
1019 pr_err("overlay changeset pre-remove notify error %d\n", ret);
1023 list_del(&ovcs->ovcs_list);
1026 ret = __of_changeset_revert_entries(&ovcs->cset, &ret_apply);
1029 devicetree_state_flags |= DTSF_REVERT_FAIL;
1033 ret = __of_changeset_revert_notify(&ovcs->cset);
1035 pr_err("overlay changeset entry notify error %d\n", ret);
1036 /* notify failure is not fatal, continue */
1040 ret_tmp = overlay_notify(ovcs, OF_OVERLAY_POST_REMOVE);
1042 pr_err("overlay changeset post-remove notify error %d\n",
1048 free_overlay_changeset(ovcs);
1051 mutex_unlock(&of_mutex);
1054 pr_debug("%s() err=%d\n", __func__, ret);
1058 EXPORT_SYMBOL_GPL(of_overlay_remove);
1061 * of_overlay_remove_all() - Reverts and frees all overlay changesets
1063 * Removes all overlays from the system in the correct order.
1065 * Returns 0 on success, or a negative error number
1067 int of_overlay_remove_all(void)
1069 struct overlay_changeset *ovcs, *ovcs_n;
1072 /* the tail of list is guaranteed to be safe to remove */
1073 list_for_each_entry_safe_reverse(ovcs, ovcs_n, &ovcs_list, ovcs_list) {
1074 ret = of_overlay_remove(&ovcs->id);
1081 EXPORT_SYMBOL_GPL(of_overlay_remove_all);