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 target - info about current target node as recursing through overlay
28 * @np: node where current level of overlay will be applied
29 * @in_livetree: @np is a node in the live devicetree
31 * Used in the algorithm to create the portion of a changeset that describes
32 * an overlay fragment, which is a devicetree subtree. Initially @np is a node
33 * in the live devicetree where the overlay subtree is targeted to be grafted
34 * into. When recursing to the next level of the overlay subtree, the target
35 * also recurses to the next level of the live devicetree, as long as overlay
36 * subtree node also exists in the live devicetree. When a node in the overlay
37 * subtree does not exist at the same level in the live devicetree, target->np
38 * points to a newly allocated node, and all subsequent targets in the subtree
39 * will be newly allocated nodes.
42 struct device_node *np;
47 * struct fragment - info about fragment nodes in overlay expanded device tree
48 * @target: target of the overlay operation
49 * @overlay: pointer to the __overlay__ node
52 struct device_node *target;
53 struct device_node *overlay;
57 * struct overlay_changeset
58 * @id: changeset identifier
59 * @ovcs_list: list on which we are located
60 * @fdt: FDT that was unflattened to create @overlay_tree
61 * @overlay_tree: expanded device tree that contains the fragment nodes
62 * @count: count of fragment structures
63 * @fragments: fragment nodes in the overlay expanded device tree
64 * @symbols_fragment: last element of @fragments[] is the __symbols__ node
65 * @cset: changeset to apply fragments to live device tree
67 struct overlay_changeset {
69 struct list_head ovcs_list;
71 struct device_node *overlay_tree;
73 struct fragment *fragments;
74 bool symbols_fragment;
75 struct of_changeset cset;
78 /* flags are sticky - once set, do not reset */
79 static int devicetree_state_flags;
80 #define DTSF_APPLY_FAIL 0x01
81 #define DTSF_REVERT_FAIL 0x02
84 * If a changeset apply or revert encounters an error, an attempt will
85 * be made to undo partial changes, but may fail. If the undo fails
86 * we do not know the state of the devicetree.
88 static int devicetree_corrupt(void)
90 return devicetree_state_flags &
91 (DTSF_APPLY_FAIL | DTSF_REVERT_FAIL);
94 static int build_changeset_next_level(struct overlay_changeset *ovcs,
95 struct target *target, const struct device_node *overlay_node);
98 * of_resolve_phandles() finds the largest phandle in the live tree.
99 * of_overlay_apply() may add a larger phandle to the live tree.
100 * Do not allow race between two overlays being applied simultaneously:
101 * mutex_lock(&of_overlay_phandle_mutex)
102 * of_resolve_phandles()
104 * mutex_unlock(&of_overlay_phandle_mutex)
106 static DEFINE_MUTEX(of_overlay_phandle_mutex);
108 void of_overlay_mutex_lock(void)
110 mutex_lock(&of_overlay_phandle_mutex);
113 void of_overlay_mutex_unlock(void)
115 mutex_unlock(&of_overlay_phandle_mutex);
119 static LIST_HEAD(ovcs_list);
120 static DEFINE_IDR(ovcs_idr);
122 static BLOCKING_NOTIFIER_HEAD(overlay_notify_chain);
125 * of_overlay_notifier_register() - Register notifier for overlay operations
126 * @nb: Notifier block to register
128 * Register for notification on overlay operations on device tree nodes. The
129 * reported actions definied by @of_reconfig_change. The notifier callback
130 * furthermore receives a pointer to the affected device tree node.
132 * Note that a notifier callback is not supposed to store pointers to a device
133 * tree node or its content beyond @OF_OVERLAY_POST_REMOVE corresponding to the
134 * respective node it received.
136 int of_overlay_notifier_register(struct notifier_block *nb)
138 return blocking_notifier_chain_register(&overlay_notify_chain, nb);
140 EXPORT_SYMBOL_GPL(of_overlay_notifier_register);
143 * of_overlay_notifier_register() - Unregister notifier for overlay operations
144 * @nb: Notifier block to unregister
146 int of_overlay_notifier_unregister(struct notifier_block *nb)
148 return blocking_notifier_chain_unregister(&overlay_notify_chain, nb);
150 EXPORT_SYMBOL_GPL(of_overlay_notifier_unregister);
152 static char *of_overlay_action_name[] = {
159 static int overlay_notify(struct overlay_changeset *ovcs,
160 enum of_overlay_notify_action action)
162 struct of_overlay_notify_data nd;
165 for (i = 0; i < ovcs->count; i++) {
166 struct fragment *fragment = &ovcs->fragments[i];
168 nd.target = fragment->target;
169 nd.overlay = fragment->overlay;
171 ret = blocking_notifier_call_chain(&overlay_notify_chain,
173 if (ret == NOTIFY_OK || ret == NOTIFY_STOP)
176 ret = notifier_to_errno(ret);
177 pr_err("overlay changeset %s notifier error %d, target: %pOF\n",
178 of_overlay_action_name[action], ret, nd.target);
187 * The values of properties in the "/__symbols__" node are paths in
188 * the ovcs->overlay_tree. When duplicating the properties, the paths
189 * need to be adjusted to be the correct path for the live device tree.
191 * The paths refer to a node in the subtree of a fragment node's "__overlay__"
192 * node, for example "/fragment@0/__overlay__/symbol_path_tail",
193 * where symbol_path_tail can be a single node or it may be a multi-node path.
195 * The duplicated property value will be modified by replacing the
196 * "/fragment_name/__overlay/" portion of the value with the target
197 * path from the fragment node.
199 static struct property *dup_and_fixup_symbol_prop(
200 struct overlay_changeset *ovcs, const struct property *prop)
202 struct fragment *fragment;
203 struct property *new_prop;
204 struct device_node *fragment_node;
205 struct device_node *overlay_node;
207 const char *path_tail;
208 const char *target_path;
210 int overlay_name_len;
217 if (strnlen(prop->value, prop->length) >= prop->length)
220 path_len = strlen(path);
224 fragment_node = __of_find_node_by_path(ovcs->overlay_tree, path + 1);
225 overlay_node = __of_find_node_by_path(fragment_node, "__overlay__/");
226 of_node_put(fragment_node);
227 of_node_put(overlay_node);
229 for (k = 0; k < ovcs->count; k++) {
230 fragment = &ovcs->fragments[k];
231 if (fragment->overlay == overlay_node)
234 if (k >= ovcs->count)
237 overlay_name_len = snprintf(NULL, 0, "%pOF", fragment->overlay);
239 if (overlay_name_len > path_len)
241 path_tail = path + overlay_name_len;
242 path_tail_len = strlen(path_tail);
244 target_path = kasprintf(GFP_KERNEL, "%pOF", fragment->target);
247 target_path_len = strlen(target_path);
249 new_prop = kzalloc(sizeof(*new_prop), GFP_KERNEL);
251 goto err_free_target_path;
253 new_prop->name = kstrdup(prop->name, GFP_KERNEL);
254 new_prop->length = target_path_len + path_tail_len + 1;
255 new_prop->value = kzalloc(new_prop->length, GFP_KERNEL);
256 if (!new_prop->name || !new_prop->value)
257 goto err_free_new_prop;
259 strcpy(new_prop->value, target_path);
260 strcpy(new_prop->value + target_path_len, path_tail);
262 of_property_set_flag(new_prop, OF_DYNAMIC);
267 kfree(new_prop->name);
268 kfree(new_prop->value);
270 err_free_target_path:
277 * add_changeset_property() - add @overlay_prop to overlay changeset
278 * @ovcs: overlay changeset
279 * @target: where @overlay_prop will be placed
280 * @overlay_prop: property to add or update, from overlay tree
281 * @is_symbols_prop: 1 if @overlay_prop is from node "/__symbols__"
283 * If @overlay_prop does not already exist in live devicetree, add changeset
284 * entry to add @overlay_prop in @target, else add changeset entry to update
285 * value of @overlay_prop.
287 * @target may be either in the live devicetree or in a new subtree that
288 * is contained in the changeset.
290 * Some special properties are not updated (no error returned).
292 * Update of property in symbols node is not allowed.
294 * Returns 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if
297 static int add_changeset_property(struct overlay_changeset *ovcs,
298 struct target *target, struct property *overlay_prop,
299 bool is_symbols_prop)
301 struct property *new_prop = NULL, *prop;
304 if (!of_prop_cmp(overlay_prop->name, "name") ||
305 !of_prop_cmp(overlay_prop->name, "phandle") ||
306 !of_prop_cmp(overlay_prop->name, "linux,phandle"))
309 if (target->in_livetree)
310 prop = of_find_property(target->np, overlay_prop->name, NULL);
314 if (is_symbols_prop) {
317 new_prop = dup_and_fixup_symbol_prop(ovcs, overlay_prop);
319 new_prop = __of_prop_dup(overlay_prop, GFP_KERNEL);
326 ret = of_changeset_add_property(&ovcs->cset, target->np,
329 ret = of_changeset_update_property(&ovcs->cset, target->np,
333 kfree(new_prop->name);
334 kfree(new_prop->value);
341 * add_changeset_node() - add @node (and children) to overlay changeset
342 * @ovcs: overlay changeset
343 * @target: where @node will be placed in live tree or changeset
344 * @node: node from within overlay device tree fragment
346 * If @node does not already exist in @target, add changeset entry
347 * to add @node in @target.
349 * If @node already exists in @target, and the existing node has
350 * a phandle, the overlay node is not allowed to have a phandle.
352 * If @node has child nodes, add the children recursively via
353 * build_changeset_next_level().
355 * NOTE_1: A live devicetree created from a flattened device tree (FDT) will
356 * not contain the full path in node->full_name. Thus an overlay
357 * created from an FDT also will not contain the full path in
358 * node->full_name. However, a live devicetree created from Open
359 * Firmware may have the full path in node->full_name.
361 * add_changeset_node() follows the FDT convention and does not include
362 * the full path in node->full_name. Even though it expects the overlay
363 * to not contain the full path, it uses kbasename() to remove the
364 * full path should it exist. It also uses kbasename() in comparisons
365 * to nodes in the live devicetree so that it can apply an overlay to
366 * a live devicetree created from Open Firmware.
368 * NOTE_2: Multiple mods of created nodes not supported.
369 * If more than one fragment contains a node that does not already exist
370 * in the live tree, then for each fragment of_changeset_attach_node()
371 * will add a changeset entry to add the node. When the changeset is
372 * applied, __of_attach_node() will attach the node twice (once for
373 * each fragment). At this point the device tree will be corrupted.
375 * TODO: add integrity check to ensure that multiple fragments do not
376 * create the same node.
378 * Returns 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if
381 static int add_changeset_node(struct overlay_changeset *ovcs,
382 struct target *target, struct device_node *node)
384 const char *node_kbasename;
385 struct device_node *tchild;
386 struct target target_child;
389 node_kbasename = kbasename(node->full_name);
391 for_each_child_of_node(target->np, tchild)
392 if (!of_node_cmp(node_kbasename, kbasename(tchild->full_name)))
396 tchild = __of_node_dup(node, node_kbasename);
400 tchild->parent = target->np;
401 of_node_set_flag(tchild, OF_OVERLAY);
403 ret = of_changeset_attach_node(&ovcs->cset, tchild);
407 target_child.np = tchild;
408 target_child.in_livetree = false;
410 ret = build_changeset_next_level(ovcs, &target_child, node);
415 if (node->phandle && tchild->phandle) {
418 target_child.np = tchild;
419 target_child.in_livetree = target->in_livetree;
420 ret = build_changeset_next_level(ovcs, &target_child, node);
428 * build_changeset_next_level() - add level of overlay changeset
429 * @ovcs: overlay changeset
430 * @target: where to place @overlay_node in live tree
431 * @overlay_node: node from within an overlay device tree fragment
433 * Add the properties (if any) and nodes (if any) from @overlay_node to the
434 * @ovcs->cset changeset. If an added node has child nodes, they will
435 * be added recursively.
437 * Do not allow symbols node to have any children.
439 * Returns 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if
440 * invalid @overlay_node.
442 static int build_changeset_next_level(struct overlay_changeset *ovcs,
443 struct target *target, const struct device_node *overlay_node)
445 struct device_node *child;
446 struct property *prop;
449 for_each_property_of_node(overlay_node, prop) {
450 ret = add_changeset_property(ovcs, target, prop, 0);
452 pr_debug("Failed to apply prop @%pOF/%s, err=%d\n",
453 target->np, prop->name, ret);
458 for_each_child_of_node(overlay_node, child) {
459 ret = add_changeset_node(ovcs, target, child);
461 pr_debug("Failed to apply node @%pOF/%pOFn, err=%d\n",
462 target->np, child, ret);
472 * Add the properties from __overlay__ node to the @ovcs->cset changeset.
474 static int build_changeset_symbols_node(struct overlay_changeset *ovcs,
475 struct target *target,
476 const struct device_node *overlay_symbols_node)
478 struct property *prop;
481 for_each_property_of_node(overlay_symbols_node, prop) {
482 ret = add_changeset_property(ovcs, target, prop, 1);
484 pr_debug("Failed to apply prop @%pOF/%s, err=%d\n",
485 target->np, prop->name, ret);
494 * build_changeset() - populate overlay changeset in @ovcs from @ovcs->fragments
495 * @ovcs: Overlay changeset
497 * Create changeset @ovcs->cset to contain the nodes and properties of the
498 * overlay device tree fragments in @ovcs->fragments[]. If an error occurs,
499 * any portions of the changeset that were successfully created will remain
502 * Returns 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if
503 * invalid overlay in @ovcs->fragments[].
505 static int build_changeset(struct overlay_changeset *ovcs)
507 struct fragment *fragment;
508 struct target target;
509 int fragments_count, i, ret;
512 * if there is a symbols fragment in ovcs->fragments[i] it is
513 * the final element in the array
515 if (ovcs->symbols_fragment)
516 fragments_count = ovcs->count - 1;
518 fragments_count = ovcs->count;
520 for (i = 0; i < fragments_count; i++) {
521 fragment = &ovcs->fragments[i];
523 target.np = fragment->target;
524 target.in_livetree = true;
525 ret = build_changeset_next_level(ovcs, &target,
528 pr_debug("apply failed '%pOF'\n", fragment->target);
533 if (ovcs->symbols_fragment) {
534 fragment = &ovcs->fragments[ovcs->count - 1];
536 target.np = fragment->target;
537 target.in_livetree = true;
538 ret = build_changeset_symbols_node(ovcs, &target,
541 pr_debug("apply failed '%pOF'\n", fragment->target);
550 * Find the target node using a number of different strategies
551 * in order of preference:
553 * 1) "target" property containing the phandle of the target
554 * 2) "target-path" property containing the path of the target
556 static struct device_node *find_target(struct device_node *info_node)
558 struct device_node *node;
563 ret = of_property_read_u32(info_node, "target", &val);
565 node = of_find_node_by_phandle(val);
567 pr_err("find target, node: %pOF, phandle 0x%x not found\n",
572 ret = of_property_read_string(info_node, "target-path", &path);
574 node = of_find_node_by_path(path);
576 pr_err("find target, node: %pOF, path '%s' not found\n",
581 pr_err("find target, node: %pOF, no target property\n", info_node);
587 * init_overlay_changeset() - initialize overlay changeset from overlay tree
588 * @ovcs: Overlay changeset to build
589 * @fdt: the FDT that was unflattened to create @tree
590 * @tree: Contains all the overlay fragments and overlay fixup nodes
592 * Initialize @ovcs. Populate @ovcs->fragments with node information from
593 * the top level of @tree. The relevant top level nodes are the fragment
594 * nodes and the __symbols__ node. Any other top level node will be ignored.
596 * Returns 0 on success, -ENOMEM if memory allocation failure, -EINVAL if error
597 * detected in @tree, or -ENOSPC if idr_alloc() error.
599 static int init_overlay_changeset(struct overlay_changeset *ovcs,
600 const void *fdt, struct device_node *tree)
602 struct device_node *node, *overlay_node;
603 struct fragment *fragment;
604 struct fragment *fragments;
608 * Warn for some issues. Can not return -EINVAL for these until
609 * of_unittest_apply_overlay() is fixed to pass these checks.
611 if (!of_node_check_flag(tree, OF_DYNAMIC))
612 pr_debug("%s() tree is not dynamic\n", __func__);
614 if (!of_node_check_flag(tree, OF_DETACHED))
615 pr_debug("%s() tree is not detached\n", __func__);
617 if (!of_node_is_root(tree))
618 pr_debug("%s() tree is not root\n", __func__);
620 ovcs->overlay_tree = tree;
623 INIT_LIST_HEAD(&ovcs->ovcs_list);
625 of_changeset_init(&ovcs->cset);
627 id = idr_alloc(&ovcs_idr, ovcs, 1, 0, GFP_KERNEL);
634 for_each_child_of_node(tree, node) {
635 overlay_node = of_get_child_by_name(node, "__overlay__");
638 of_node_put(overlay_node);
642 node = of_get_child_by_name(tree, "__symbols__");
648 fragments = kcalloc(cnt, sizeof(*fragments), GFP_KERNEL);
655 for_each_child_of_node(tree, node) {
656 overlay_node = of_get_child_by_name(node, "__overlay__");
660 fragment = &fragments[cnt];
661 fragment->overlay = overlay_node;
662 fragment->target = find_target(node);
663 if (!fragment->target) {
664 of_node_put(fragment->overlay);
666 goto err_free_fragments;
673 * if there is a symbols fragment in ovcs->fragments[i] it is
674 * the final element in the array
676 node = of_get_child_by_name(tree, "__symbols__");
678 ovcs->symbols_fragment = 1;
679 fragment = &fragments[cnt];
680 fragment->overlay = node;
681 fragment->target = of_find_node_by_path("/__symbols__");
683 if (!fragment->target) {
684 pr_err("symbols in overlay, but not in live tree\n");
686 goto err_free_fragments;
693 pr_err("no fragments or symbols in overlay\n");
695 goto err_free_fragments;
700 ovcs->fragments = fragments;
707 idr_remove(&ovcs_idr, id);
709 pr_err("%s() failed, ret = %d\n", __func__, ret);
714 static void free_overlay_changeset(struct overlay_changeset *ovcs)
718 if (ovcs->cset.entries.next)
719 of_changeset_destroy(&ovcs->cset);
722 idr_remove(&ovcs_idr, ovcs->id);
724 for (i = 0; i < ovcs->count; i++) {
725 of_node_put(ovcs->fragments[i].target);
726 of_node_put(ovcs->fragments[i].overlay);
728 kfree(ovcs->fragments);
730 * There should be no live pointers into ovcs->overlay_tree and
731 * ovcs->fdt due to the policy that overlay notifiers are not allowed
732 * to retain pointers into the overlay devicetree.
734 kfree(ovcs->overlay_tree);
740 * internal documentation
742 * of_overlay_apply() - Create and apply an overlay changeset
743 * @fdt: the FDT that was unflattened to create @tree
744 * @tree: Expanded overlay device tree
745 * @ovcs_id: Pointer to overlay changeset id
747 * Creates and applies an overlay changeset.
749 * If an error occurs in a pre-apply notifier, then no changes are made
750 * to the device tree.
753 * A non-zero return value will not have created the changeset if error is from:
755 * - building the changeset
756 * - overlay changeset pre-apply notifier
758 * If an error is returned by an overlay changeset pre-apply notifier
759 * then no further overlay changeset pre-apply notifier will be called.
761 * A non-zero return value will have created the changeset if error is from:
762 * - overlay changeset entry notifier
763 * - overlay changeset post-apply notifier
765 * If an error is returned by an overlay changeset post-apply notifier
766 * then no further overlay changeset post-apply notifier will be called.
768 * If more than one notifier returns an error, then the last notifier
769 * error to occur is returned.
771 * If an error occurred while applying the overlay changeset, then an
772 * attempt is made to revert any changes that were made to the
773 * device tree. If there were any errors during the revert attempt
774 * then the state of the device tree can not be determined, and any
775 * following attempt to apply or remove an overlay changeset will be
778 * Returns 0 on success, or a negative error number. Overlay changeset
779 * id is returned to *ovcs_id.
782 static int of_overlay_apply(const void *fdt, struct device_node *tree,
785 struct overlay_changeset *ovcs;
786 int ret = 0, ret_revert, ret_tmp;
789 * As of this point, fdt and tree belong to the overlay changeset.
790 * overlay changeset code is responsible for freeing them.
793 if (devicetree_corrupt()) {
794 pr_err("devicetree state suspect, refuse to apply overlay\n");
801 ovcs = kzalloc(sizeof(*ovcs), GFP_KERNEL);
809 of_overlay_mutex_lock();
810 mutex_lock(&of_mutex);
812 ret = of_resolve_phandles(tree);
816 ret = init_overlay_changeset(ovcs, fdt, tree);
821 * after overlay_notify(), ovcs->overlay_tree related pointers may have
822 * leaked to drivers, so can not kfree() tree, aka ovcs->overlay_tree;
823 * and can not free fdt, aka ovcs->fdt
825 ret = overlay_notify(ovcs, OF_OVERLAY_PRE_APPLY);
827 pr_err("overlay changeset pre-apply notify error %d\n", ret);
828 goto err_free_overlay_changeset;
831 ret = build_changeset(ovcs);
833 goto err_free_overlay_changeset;
836 ret = __of_changeset_apply_entries(&ovcs->cset, &ret_revert);
839 pr_debug("overlay changeset revert error %d\n",
841 devicetree_state_flags |= DTSF_APPLY_FAIL;
843 goto err_free_overlay_changeset;
846 of_populate_phandle_cache();
848 ret = __of_changeset_apply_notify(&ovcs->cset);
850 pr_err("overlay changeset entry notify error %d\n", ret);
851 /* notify failure is not fatal, continue */
853 list_add_tail(&ovcs->ovcs_list, &ovcs_list);
856 ret_tmp = overlay_notify(ovcs, OF_OVERLAY_POST_APPLY);
858 pr_err("overlay changeset post-apply notify error %d\n",
870 err_free_overlay_changeset:
871 free_overlay_changeset(ovcs);
874 mutex_unlock(&of_mutex);
875 of_overlay_mutex_unlock();
878 pr_debug("%s() err=%d\n", __func__, ret);
883 int of_overlay_fdt_apply(const void *overlay_fdt, u32 overlay_fdt_size,
889 struct device_node *overlay_root;
894 if (overlay_fdt_size < sizeof(struct fdt_header) ||
895 fdt_check_header(overlay_fdt)) {
896 pr_err("Invalid overlay_fdt header\n");
900 size = fdt_totalsize(overlay_fdt);
901 if (overlay_fdt_size < size)
905 * Must create permanent copy of FDT because of_fdt_unflatten_tree()
906 * will create pointers to the passed in FDT in the unflattened tree.
908 new_fdt = kmemdup(overlay_fdt, size, GFP_KERNEL);
912 of_fdt_unflatten_tree(new_fdt, NULL, &overlay_root);
914 pr_err("unable to unflatten overlay_fdt\n");
916 goto out_free_new_fdt;
919 ret = of_overlay_apply(new_fdt, overlay_root, ovcs_id);
922 * new_fdt and overlay_root now belong to the overlay
924 * overlay changeset code is responsible for freeing them.
938 EXPORT_SYMBOL_GPL(of_overlay_fdt_apply);
943 * Returns 1 if @np is @tree or is contained in @tree, else 0
945 static int find_node(struct device_node *tree, struct device_node *np)
947 struct device_node *child;
952 for_each_child_of_node(tree, child) {
953 if (find_node(child, np)) {
963 * Is @remove_ce_node a child of, a parent of, or the same as any
964 * node in an overlay changeset more topmost than @remove_ovcs?
966 * Returns 1 if found, else 0
968 static int node_overlaps_later_cs(struct overlay_changeset *remove_ovcs,
969 struct device_node *remove_ce_node)
971 struct overlay_changeset *ovcs;
972 struct of_changeset_entry *ce;
974 list_for_each_entry_reverse(ovcs, &ovcs_list, ovcs_list) {
975 if (ovcs == remove_ovcs)
978 list_for_each_entry(ce, &ovcs->cset.entries, node) {
979 if (find_node(ce->np, remove_ce_node)) {
980 pr_err("%s: #%d overlaps with #%d @%pOF\n",
981 __func__, remove_ovcs->id, ovcs->id,
985 if (find_node(remove_ce_node, ce->np)) {
986 pr_err("%s: #%d overlaps with #%d @%pOF\n",
987 __func__, remove_ovcs->id, ovcs->id,
998 * We can safely remove the overlay only if it's the top-most one.
999 * Newly applied overlays are inserted at the tail of the overlay list,
1000 * so a top most overlay is the one that is closest to the tail.
1002 * The topmost check is done by exploiting this property. For each
1003 * affected device node in the log list we check if this overlay is
1004 * the one closest to the tail. If another overlay has affected this
1005 * device node and is closest to the tail, then removal is not permited.
1007 static int overlay_removal_is_ok(struct overlay_changeset *remove_ovcs)
1009 struct of_changeset_entry *remove_ce;
1011 list_for_each_entry(remove_ce, &remove_ovcs->cset.entries, node) {
1012 if (node_overlaps_later_cs(remove_ovcs, remove_ce->np)) {
1013 pr_err("overlay #%d is not topmost\n", remove_ovcs->id);
1022 * of_overlay_remove() - Revert and free an overlay changeset
1023 * @ovcs_id: Pointer to overlay changeset id
1025 * Removes an overlay if it is permissible. @ovcs_id was previously returned
1026 * by of_overlay_fdt_apply().
1028 * If an error occurred while attempting to revert the overlay changeset,
1029 * then an attempt is made to re-apply any changeset entry that was
1030 * reverted. If an error occurs on re-apply then the state of the device
1031 * tree can not be determined, and any following attempt to apply or remove
1032 * an overlay changeset will be refused.
1034 * A non-zero return value will not revert the changeset if error is from:
1035 * - parameter checks
1036 * - overlay changeset pre-remove notifier
1037 * - overlay changeset entry revert
1039 * If an error is returned by an overlay changeset pre-remove notifier
1040 * then no further overlay changeset pre-remove notifier will be called.
1042 * If more than one notifier returns an error, then the last notifier
1043 * error to occur is returned.
1045 * A non-zero return value will revert the changeset if error is from:
1046 * - overlay changeset entry notifier
1047 * - overlay changeset post-remove notifier
1049 * If an error is returned by an overlay changeset post-remove notifier
1050 * then no further overlay changeset post-remove notifier will be called.
1052 * Returns 0 on success, or a negative error number. *ovcs_id is set to
1053 * zero after reverting the changeset, even if a subsequent error occurs.
1055 int of_overlay_remove(int *ovcs_id)
1057 struct overlay_changeset *ovcs;
1058 int ret, ret_apply, ret_tmp;
1062 if (devicetree_corrupt()) {
1063 pr_err("suspect devicetree state, refuse to remove overlay\n");
1068 mutex_lock(&of_mutex);
1070 ovcs = idr_find(&ovcs_idr, *ovcs_id);
1073 pr_err("remove: Could not find overlay #%d\n", *ovcs_id);
1077 if (!overlay_removal_is_ok(ovcs)) {
1082 ret = overlay_notify(ovcs, OF_OVERLAY_PRE_REMOVE);
1084 pr_err("overlay changeset pre-remove notify error %d\n", ret);
1088 list_del(&ovcs->ovcs_list);
1091 * Disable phandle cache. Avoids race condition that would arise
1092 * from removing cache entry when the associated node is deleted.
1094 of_free_phandle_cache();
1097 ret = __of_changeset_revert_entries(&ovcs->cset, &ret_apply);
1099 of_populate_phandle_cache();
1103 devicetree_state_flags |= DTSF_REVERT_FAIL;
1107 ret = __of_changeset_revert_notify(&ovcs->cset);
1109 pr_err("overlay changeset entry notify error %d\n", ret);
1110 /* notify failure is not fatal, continue */
1114 ret_tmp = overlay_notify(ovcs, OF_OVERLAY_POST_REMOVE);
1116 pr_err("overlay changeset post-remove notify error %d\n",
1122 free_overlay_changeset(ovcs);
1125 mutex_unlock(&of_mutex);
1128 pr_debug("%s() err=%d\n", __func__, ret);
1132 EXPORT_SYMBOL_GPL(of_overlay_remove);
1135 * of_overlay_remove_all() - Reverts and frees all overlay changesets
1137 * Removes all overlays from the system in the correct order.
1139 * Returns 0 on success, or a negative error number
1141 int of_overlay_remove_all(void)
1143 struct overlay_changeset *ovcs, *ovcs_n;
1146 /* the tail of list is guaranteed to be safe to remove */
1147 list_for_each_entry_safe_reverse(ovcs, ovcs_n, &ovcs_list, ovcs_list) {
1148 ret = of_overlay_remove(&ovcs->id);
1155 EXPORT_SYMBOL_GPL(of_overlay_remove_all);