1 // SPDX-License-Identifier: GPL-2.0+
3 * XArray implementation
4 * Copyright (c) 2017-2018 Microsoft Corporation
5 * Copyright (c) 2018-2020 Oracle
6 * Author: Matthew Wilcox <willy@infradead.org>
9 #include <linux/bitmap.h>
10 #include <linux/export.h>
11 #include <linux/list.h>
12 #include <linux/slab.h>
13 #include <linux/xarray.h>
16 * Coding conventions in this file:
18 * @xa is used to refer to the entire xarray.
19 * @xas is the 'xarray operation state'. It may be either a pointer to
20 * an xa_state, or an xa_state stored on the stack. This is an unfortunate
22 * @index is the index of the entry being operated on
23 * @mark is an xa_mark_t; a small number indicating one of the mark bits.
24 * @node refers to an xa_node; usually the primary one being operated on by
26 * @offset is the index into the slots array inside an xa_node.
27 * @parent refers to the @xa_node closer to the head than @node.
28 * @entry refers to something stored in a slot in the xarray
31 static inline unsigned int xa_lock_type(const struct xarray *xa)
33 return (__force unsigned int)xa->xa_flags & 3;
36 static inline void xas_lock_type(struct xa_state *xas, unsigned int lock_type)
38 if (lock_type == XA_LOCK_IRQ)
40 else if (lock_type == XA_LOCK_BH)
46 static inline void xas_unlock_type(struct xa_state *xas, unsigned int lock_type)
48 if (lock_type == XA_LOCK_IRQ)
50 else if (lock_type == XA_LOCK_BH)
56 static inline bool xa_track_free(const struct xarray *xa)
58 return xa->xa_flags & XA_FLAGS_TRACK_FREE;
61 static inline bool xa_zero_busy(const struct xarray *xa)
63 return xa->xa_flags & XA_FLAGS_ZERO_BUSY;
66 static inline void xa_mark_set(struct xarray *xa, xa_mark_t mark)
68 if (!(xa->xa_flags & XA_FLAGS_MARK(mark)))
69 xa->xa_flags |= XA_FLAGS_MARK(mark);
72 static inline void xa_mark_clear(struct xarray *xa, xa_mark_t mark)
74 if (xa->xa_flags & XA_FLAGS_MARK(mark))
75 xa->xa_flags &= ~(XA_FLAGS_MARK(mark));
78 static inline unsigned long *node_marks(struct xa_node *node, xa_mark_t mark)
80 return node->marks[(__force unsigned)mark];
83 static inline bool node_get_mark(struct xa_node *node,
84 unsigned int offset, xa_mark_t mark)
86 return test_bit(offset, node_marks(node, mark));
89 /* returns true if the bit was set */
90 static inline bool node_set_mark(struct xa_node *node, unsigned int offset,
93 return __test_and_set_bit(offset, node_marks(node, mark));
96 /* returns true if the bit was set */
97 static inline bool node_clear_mark(struct xa_node *node, unsigned int offset,
100 return __test_and_clear_bit(offset, node_marks(node, mark));
103 static inline bool node_any_mark(struct xa_node *node, xa_mark_t mark)
105 return !bitmap_empty(node_marks(node, mark), XA_CHUNK_SIZE);
108 static inline void node_mark_all(struct xa_node *node, xa_mark_t mark)
110 bitmap_fill(node_marks(node, mark), XA_CHUNK_SIZE);
113 #define mark_inc(mark) do { \
114 mark = (__force xa_mark_t)((__force unsigned)(mark) + 1); \
118 * xas_squash_marks() - Merge all marks to the first entry
119 * @xas: Array operation state.
121 * Set a mark on the first entry if any entry has it set. Clear marks on
122 * all sibling entries.
124 static void xas_squash_marks(const struct xa_state *xas)
126 unsigned int mark = 0;
127 unsigned int limit = xas->xa_offset + xas->xa_sibs + 1;
133 unsigned long *marks = xas->xa_node->marks[mark];
134 if (find_next_bit(marks, limit, xas->xa_offset + 1) == limit)
136 __set_bit(xas->xa_offset, marks);
137 bitmap_clear(marks, xas->xa_offset + 1, xas->xa_sibs);
138 } while (mark++ != (__force unsigned)XA_MARK_MAX);
141 /* extracts the offset within this node from the index */
142 static unsigned int get_offset(unsigned long index, struct xa_node *node)
144 return (index >> node->shift) & XA_CHUNK_MASK;
147 static void xas_set_offset(struct xa_state *xas)
149 xas->xa_offset = get_offset(xas->xa_index, xas->xa_node);
152 /* move the index either forwards (find) or backwards (sibling slot) */
153 static void xas_move_index(struct xa_state *xas, unsigned long offset)
155 unsigned int shift = xas->xa_node->shift;
156 xas->xa_index &= ~XA_CHUNK_MASK << shift;
157 xas->xa_index += offset << shift;
160 static void xas_advance(struct xa_state *xas)
163 xas_move_index(xas, xas->xa_offset);
166 static void *set_bounds(struct xa_state *xas)
168 xas->xa_node = XAS_BOUNDS;
173 * Starts a walk. If the @xas is already valid, we assume that it's on
174 * the right path and just return where we've got to. If we're in an
175 * error state, return NULL. If the index is outside the current scope
176 * of the xarray, return NULL without changing @xas->xa_node. Otherwise
177 * set @xas->xa_node to NULL and return the current head of the array.
179 static void *xas_start(struct xa_state *xas)
184 return xas_reload(xas);
188 entry = xa_head(xas->xa);
189 if (!xa_is_node(entry)) {
191 return set_bounds(xas);
193 if ((xas->xa_index >> xa_to_node(entry)->shift) > XA_CHUNK_MASK)
194 return set_bounds(xas);
201 static void *xas_descend(struct xa_state *xas, struct xa_node *node)
203 unsigned int offset = get_offset(xas->xa_index, node);
204 void *entry = xa_entry(xas->xa, node, offset);
207 if (xa_is_sibling(entry)) {
208 offset = xa_to_sibling(entry);
209 entry = xa_entry(xas->xa, node, offset);
212 xas->xa_offset = offset;
217 * xas_load() - Load an entry from the XArray (advanced).
218 * @xas: XArray operation state.
220 * Usually walks the @xas to the appropriate state to load the entry
221 * stored at xa_index. However, it will do nothing and return %NULL if
222 * @xas is in an error state. xas_load() will never expand the tree.
224 * If the xa_state is set up to operate on a multi-index entry, xas_load()
225 * may return %NULL or an internal entry, even if there are entries
226 * present within the range specified by @xas.
228 * Context: Any context. The caller should hold the xa_lock or the RCU lock.
229 * Return: Usually an entry in the XArray, but see description for exceptions.
231 void *xas_load(struct xa_state *xas)
233 void *entry = xas_start(xas);
235 while (xa_is_node(entry)) {
236 struct xa_node *node = xa_to_node(entry);
238 if (xas->xa_shift > node->shift)
240 entry = xas_descend(xas, node);
241 if (node->shift == 0)
246 EXPORT_SYMBOL_GPL(xas_load);
248 /* Move the radix tree node cache here */
249 extern struct kmem_cache *radix_tree_node_cachep;
250 extern void radix_tree_node_rcu_free(struct rcu_head *head);
252 #define XA_RCU_FREE ((struct xarray *)1)
254 static void xa_node_free(struct xa_node *node)
256 XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
257 node->array = XA_RCU_FREE;
258 call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
262 * xas_destroy() - Free any resources allocated during the XArray operation.
263 * @xas: XArray operation state.
265 * This function is now internal-only.
267 static void xas_destroy(struct xa_state *xas)
269 struct xa_node *next, *node = xas->xa_alloc;
272 XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
273 next = rcu_dereference_raw(node->parent);
274 radix_tree_node_rcu_free(&node->rcu_head);
275 xas->xa_alloc = node = next;
280 * xas_nomem() - Allocate memory if needed.
281 * @xas: XArray operation state.
282 * @gfp: Memory allocation flags.
284 * If we need to add new nodes to the XArray, we try to allocate memory
285 * with GFP_NOWAIT while holding the lock, which will usually succeed.
286 * If it fails, @xas is flagged as needing memory to continue. The caller
287 * should drop the lock and call xas_nomem(). If xas_nomem() succeeds,
288 * the caller should retry the operation.
290 * Forward progress is guaranteed as one node is allocated here and
291 * stored in the xa_state where it will be found by xas_alloc(). More
292 * nodes will likely be found in the slab allocator, but we do not tie
295 * Return: true if memory was needed, and was successfully allocated.
297 bool xas_nomem(struct xa_state *xas, gfp_t gfp)
299 if (xas->xa_node != XA_ERROR(-ENOMEM)) {
303 if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT)
304 gfp |= __GFP_ACCOUNT;
305 xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp);
308 xas->xa_alloc->parent = NULL;
309 XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list));
310 xas->xa_node = XAS_RESTART;
313 EXPORT_SYMBOL_GPL(xas_nomem);
316 * __xas_nomem() - Drop locks and allocate memory if needed.
317 * @xas: XArray operation state.
318 * @gfp: Memory allocation flags.
320 * Internal variant of xas_nomem().
322 * Return: true if memory was needed, and was successfully allocated.
324 static bool __xas_nomem(struct xa_state *xas, gfp_t gfp)
325 __must_hold(xas->xa->xa_lock)
327 unsigned int lock_type = xa_lock_type(xas->xa);
329 if (xas->xa_node != XA_ERROR(-ENOMEM)) {
333 if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT)
334 gfp |= __GFP_ACCOUNT;
335 if (gfpflags_allow_blocking(gfp)) {
336 xas_unlock_type(xas, lock_type);
337 xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp);
338 xas_lock_type(xas, lock_type);
340 xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp);
344 xas->xa_alloc->parent = NULL;
345 XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list));
346 xas->xa_node = XAS_RESTART;
350 static void xas_update(struct xa_state *xas, struct xa_node *node)
353 xas->xa_update(node);
355 XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
358 static void *xas_alloc(struct xa_state *xas, unsigned int shift)
360 struct xa_node *parent = xas->xa_node;
361 struct xa_node *node = xas->xa_alloc;
363 if (xas_invalid(xas))
367 xas->xa_alloc = NULL;
369 gfp_t gfp = GFP_NOWAIT | __GFP_NOWARN;
371 if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT)
372 gfp |= __GFP_ACCOUNT;
374 node = kmem_cache_alloc(radix_tree_node_cachep, gfp);
376 xas_set_err(xas, -ENOMEM);
382 node->offset = xas->xa_offset;
384 XA_NODE_BUG_ON(node, parent->count > XA_CHUNK_SIZE);
385 xas_update(xas, parent);
387 XA_NODE_BUG_ON(node, shift > BITS_PER_LONG);
388 XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
392 RCU_INIT_POINTER(node->parent, xas->xa_node);
393 node->array = xas->xa;
398 #ifdef CONFIG_XARRAY_MULTI
399 /* Returns the number of indices covered by a given xa_state */
400 static unsigned long xas_size(const struct xa_state *xas)
402 return (xas->xa_sibs + 1UL) << xas->xa_shift;
407 * Use this to calculate the maximum index that will need to be created
408 * in order to add the entry described by @xas. Because we cannot store a
409 * multi-index entry at index 0, the calculation is a little more complex
410 * than you might expect.
412 static unsigned long xas_max(struct xa_state *xas)
414 unsigned long max = xas->xa_index;
416 #ifdef CONFIG_XARRAY_MULTI
417 if (xas->xa_shift || xas->xa_sibs) {
418 unsigned long mask = xas_size(xas) - 1;
428 /* The maximum index that can be contained in the array without expanding it */
429 static unsigned long max_index(void *entry)
431 if (!xa_is_node(entry))
433 return (XA_CHUNK_SIZE << xa_to_node(entry)->shift) - 1;
436 static void xas_shrink(struct xa_state *xas)
438 struct xarray *xa = xas->xa;
439 struct xa_node *node = xas->xa_node;
444 XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
445 if (node->count != 1)
447 entry = xa_entry_locked(xa, node, 0);
450 if (!xa_is_node(entry) && node->shift)
452 if (xa_is_zero(entry) && xa_zero_busy(xa))
454 xas->xa_node = XAS_BOUNDS;
456 RCU_INIT_POINTER(xa->xa_head, entry);
457 if (xa_track_free(xa) && !node_get_mark(node, 0, XA_FREE_MARK))
458 xa_mark_clear(xa, XA_FREE_MARK);
462 if (!xa_is_node(entry))
463 RCU_INIT_POINTER(node->slots[0], XA_RETRY_ENTRY);
464 xas_update(xas, node);
466 if (!xa_is_node(entry))
468 node = xa_to_node(entry);
474 * xas_delete_node() - Attempt to delete an xa_node
475 * @xas: Array operation state.
477 * Attempts to delete the @xas->xa_node. This will fail if xa->node has
478 * a non-zero reference count.
480 static void xas_delete_node(struct xa_state *xas)
482 struct xa_node *node = xas->xa_node;
485 struct xa_node *parent;
487 XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
491 parent = xa_parent_locked(xas->xa, node);
492 xas->xa_node = parent;
493 xas->xa_offset = node->offset;
497 xas->xa->xa_head = NULL;
498 xas->xa_node = XAS_BOUNDS;
502 parent->slots[xas->xa_offset] = NULL;
504 XA_NODE_BUG_ON(parent, parent->count > XA_CHUNK_SIZE);
506 xas_update(xas, node);
514 * xas_free_nodes() - Free this node and all nodes that it references
515 * @xas: Array operation state.
518 * This node has been removed from the tree. We must now free it and all
519 * of its subnodes. There may be RCU walkers with references into the tree,
520 * so we must replace all entries with retry markers.
522 static void xas_free_nodes(struct xa_state *xas, struct xa_node *top)
524 unsigned int offset = 0;
525 struct xa_node *node = top;
528 void *entry = xa_entry_locked(xas->xa, node, offset);
530 if (node->shift && xa_is_node(entry)) {
531 node = xa_to_node(entry);
536 RCU_INIT_POINTER(node->slots[offset], XA_RETRY_ENTRY);
538 while (offset == XA_CHUNK_SIZE) {
539 struct xa_node *parent;
541 parent = xa_parent_locked(xas->xa, node);
542 offset = node->offset + 1;
545 xas_update(xas, node);
555 * xas_expand adds nodes to the head of the tree until it has reached
556 * sufficient height to be able to contain @xas->xa_index
558 static int xas_expand(struct xa_state *xas, void *head)
560 struct xarray *xa = xas->xa;
561 struct xa_node *node = NULL;
562 unsigned int shift = 0;
563 unsigned long max = xas_max(xas);
568 while ((max >> shift) >= XA_CHUNK_SIZE)
569 shift += XA_CHUNK_SHIFT;
570 return shift + XA_CHUNK_SHIFT;
571 } else if (xa_is_node(head)) {
572 node = xa_to_node(head);
573 shift = node->shift + XA_CHUNK_SHIFT;
577 while (max > max_index(head)) {
580 XA_NODE_BUG_ON(node, shift > BITS_PER_LONG);
581 node = xas_alloc(xas, shift);
586 if (xa_is_value(head))
588 RCU_INIT_POINTER(node->slots[0], head);
590 /* Propagate the aggregated mark info to the new child */
592 if (xa_track_free(xa) && mark == XA_FREE_MARK) {
593 node_mark_all(node, XA_FREE_MARK);
594 if (!xa_marked(xa, XA_FREE_MARK)) {
595 node_clear_mark(node, 0, XA_FREE_MARK);
596 xa_mark_set(xa, XA_FREE_MARK);
598 } else if (xa_marked(xa, mark)) {
599 node_set_mark(node, 0, mark);
601 if (mark == XA_MARK_MAX)
607 * Now that the new node is fully initialised, we can add
610 if (xa_is_node(head)) {
611 xa_to_node(head)->offset = 0;
612 rcu_assign_pointer(xa_to_node(head)->parent, node);
614 head = xa_mk_node(node);
615 rcu_assign_pointer(xa->xa_head, head);
616 xas_update(xas, node);
618 shift += XA_CHUNK_SHIFT;
626 * xas_create() - Create a slot to store an entry in.
627 * @xas: XArray operation state.
628 * @allow_root: %true if we can store the entry in the root directly
630 * Most users will not need to call this function directly, as it is called
631 * by xas_store(). It is useful for doing conditional store operations
632 * (see the xa_cmpxchg() implementation for an example).
634 * Return: If the slot already existed, returns the contents of this slot.
635 * If the slot was newly created, returns %NULL. If it failed to create the
636 * slot, returns %NULL and indicates the error in @xas.
638 static void *xas_create(struct xa_state *xas, bool allow_root)
640 struct xarray *xa = xas->xa;
643 struct xa_node *node = xas->xa_node;
645 unsigned int order = xas->xa_shift;
648 entry = xa_head_locked(xa);
650 if (!entry && xa_zero_busy(xa))
651 entry = XA_ZERO_ENTRY;
652 shift = xas_expand(xas, entry);
655 if (!shift && !allow_root)
656 shift = XA_CHUNK_SHIFT;
657 entry = xa_head_locked(xa);
659 } else if (xas_error(xas)) {
662 unsigned int offset = xas->xa_offset;
665 entry = xa_entry_locked(xa, node, offset);
666 slot = &node->slots[offset];
669 entry = xa_head_locked(xa);
673 while (shift > order) {
674 shift -= XA_CHUNK_SHIFT;
676 node = xas_alloc(xas, shift);
679 if (xa_track_free(xa))
680 node_mark_all(node, XA_FREE_MARK);
681 rcu_assign_pointer(*slot, xa_mk_node(node));
682 } else if (xa_is_node(entry)) {
683 node = xa_to_node(entry);
687 entry = xas_descend(xas, node);
688 slot = &node->slots[xas->xa_offset];
695 * xas_create_range() - Ensure that stores to this range will succeed
696 * @xas: XArray operation state.
698 * Creates all of the slots in the range covered by @xas. Sets @xas to
699 * create single-index entries and positions it at the beginning of the
700 * range. This is for the benefit of users which have not yet been
701 * converted to use multi-index entries.
703 void xas_create_range(struct xa_state *xas)
705 unsigned long index = xas->xa_index;
706 unsigned char shift = xas->xa_shift;
707 unsigned char sibs = xas->xa_sibs;
709 xas->xa_index |= ((sibs + 1) << shift) - 1;
710 if (xas_is_node(xas) && xas->xa_node->shift == xas->xa_shift)
711 xas->xa_offset |= sibs;
716 xas_create(xas, true);
719 if (xas->xa_index <= (index | XA_CHUNK_MASK))
721 xas->xa_index -= XA_CHUNK_SIZE;
724 struct xa_node *node = xas->xa_node;
725 if (node->shift >= shift)
727 xas->xa_node = xa_parent_locked(xas->xa, node);
728 xas->xa_offset = node->offset - 1;
729 if (node->offset != 0)
735 xas->xa_shift = shift;
737 xas->xa_index = index;
740 xas->xa_index = index;
744 EXPORT_SYMBOL_GPL(xas_create_range);
746 static void update_node(struct xa_state *xas, struct xa_node *node,
747 int count, int values)
749 if (!node || (!count && !values))
752 node->count += count;
753 node->nr_values += values;
754 XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
755 XA_NODE_BUG_ON(node, node->nr_values > XA_CHUNK_SIZE);
756 xas_update(xas, node);
758 xas_delete_node(xas);
762 * xas_store() - Store this entry in the XArray.
763 * @xas: XArray operation state.
766 * If @xas is operating on a multi-index entry, the entry returned by this
767 * function is essentially meaningless (it may be an internal entry or it
768 * may be %NULL, even if there are non-NULL entries at some of the indices
769 * covered by the range). This is not a problem for any current users,
770 * and can be changed if needed.
772 * Return: The old entry at this index.
774 void *xas_store(struct xa_state *xas, void *entry)
776 struct xa_node *node;
777 void __rcu **slot = &xas->xa->xa_head;
778 unsigned int offset, max;
782 bool value = xa_is_value(entry);
785 bool allow_root = !xa_is_node(entry) && !xa_is_zero(entry);
786 first = xas_create(xas, allow_root);
788 first = xas_load(xas);
791 if (xas_invalid(xas))
794 if (node && (xas->xa_shift < node->shift))
796 if ((first == entry) && !xas->xa_sibs)
800 offset = xas->xa_offset;
801 max = xas->xa_offset + xas->xa_sibs;
803 slot = &node->slots[offset];
805 xas_squash_marks(xas);
812 * Must clear the marks before setting the entry to NULL,
813 * otherwise xas_for_each_marked may find a NULL entry and
814 * stop early. rcu_assign_pointer contains a release barrier
815 * so the mark clearing will appear to happen before the
816 * entry is set to NULL.
818 rcu_assign_pointer(*slot, entry);
819 if (xa_is_node(next) && (!node || node->shift))
820 xas_free_nodes(xas, xa_to_node(next));
823 count += !next - !entry;
824 values += !xa_is_value(first) - !value;
828 if (!xa_is_sibling(entry))
829 entry = xa_mk_sibling(xas->xa_offset);
831 if (offset == XA_CHUNK_MASK)
834 next = xa_entry_locked(xas->xa, node, ++offset);
835 if (!xa_is_sibling(next)) {
836 if (!entry && (offset > max))
843 update_node(xas, node, count, values);
846 EXPORT_SYMBOL_GPL(xas_store);
849 * xas_get_mark() - Returns the state of this mark.
850 * @xas: XArray operation state.
851 * @mark: Mark number.
853 * Return: true if the mark is set, false if the mark is clear or @xas
854 * is in an error state.
856 bool xas_get_mark(const struct xa_state *xas, xa_mark_t mark)
858 if (xas_invalid(xas))
861 return xa_marked(xas->xa, mark);
862 return node_get_mark(xas->xa_node, xas->xa_offset, mark);
864 EXPORT_SYMBOL_GPL(xas_get_mark);
867 * xas_set_mark() - Sets the mark on this entry and its parents.
868 * @xas: XArray operation state.
869 * @mark: Mark number.
871 * Sets the specified mark on this entry, and walks up the tree setting it
872 * on all the ancestor entries. Does nothing if @xas has not been walked to
873 * an entry, or is in an error state.
875 void xas_set_mark(const struct xa_state *xas, xa_mark_t mark)
877 struct xa_node *node = xas->xa_node;
878 unsigned int offset = xas->xa_offset;
880 if (xas_invalid(xas))
884 if (node_set_mark(node, offset, mark))
886 offset = node->offset;
887 node = xa_parent_locked(xas->xa, node);
890 if (!xa_marked(xas->xa, mark))
891 xa_mark_set(xas->xa, mark);
893 EXPORT_SYMBOL_GPL(xas_set_mark);
896 * xas_clear_mark() - Clears the mark on this entry and its parents.
897 * @xas: XArray operation state.
898 * @mark: Mark number.
900 * Clears the specified mark on this entry, and walks back to the head
901 * attempting to clear it on all the ancestor entries. Does nothing if
902 * @xas has not been walked to an entry, or is in an error state.
904 void xas_clear_mark(const struct xa_state *xas, xa_mark_t mark)
906 struct xa_node *node = xas->xa_node;
907 unsigned int offset = xas->xa_offset;
909 if (xas_invalid(xas))
913 if (!node_clear_mark(node, offset, mark))
915 if (node_any_mark(node, mark))
918 offset = node->offset;
919 node = xa_parent_locked(xas->xa, node);
922 if (xa_marked(xas->xa, mark))
923 xa_mark_clear(xas->xa, mark);
925 EXPORT_SYMBOL_GPL(xas_clear_mark);
928 * xas_init_marks() - Initialise all marks for the entry
929 * @xas: Array operations state.
931 * Initialise all marks for the entry specified by @xas. If we're tracking
932 * free entries with a mark, we need to set it on all entries. All other
935 * This implementation is not as efficient as it could be; we may walk
936 * up the tree multiple times.
938 void xas_init_marks(const struct xa_state *xas)
943 if (xa_track_free(xas->xa) && mark == XA_FREE_MARK)
944 xas_set_mark(xas, mark);
946 xas_clear_mark(xas, mark);
947 if (mark == XA_MARK_MAX)
952 EXPORT_SYMBOL_GPL(xas_init_marks);
954 #ifdef CONFIG_XARRAY_MULTI
955 static unsigned int node_get_marks(struct xa_node *node, unsigned int offset)
957 unsigned int marks = 0;
958 xa_mark_t mark = XA_MARK_0;
961 if (node_get_mark(node, offset, mark))
962 marks |= 1 << (__force unsigned int)mark;
963 if (mark == XA_MARK_MAX)
971 static void node_set_marks(struct xa_node *node, unsigned int offset,
972 struct xa_node *child, unsigned int marks)
974 xa_mark_t mark = XA_MARK_0;
977 if (marks & (1 << (__force unsigned int)mark)) {
978 node_set_mark(node, offset, mark);
980 node_mark_all(child, mark);
982 if (mark == XA_MARK_MAX)
989 * xas_split_alloc() - Allocate memory for splitting an entry.
990 * @xas: XArray operation state.
991 * @entry: New entry which will be stored in the array.
992 * @order: New entry order.
993 * @gfp: Memory allocation flags.
995 * This function should be called before calling xas_split().
996 * If necessary, it will allocate new nodes (and fill them with @entry)
997 * to prepare for the upcoming split of an entry of @order size into
998 * entries of the order stored in the @xas.
1000 * Context: May sleep if @gfp flags permit.
1002 void xas_split_alloc(struct xa_state *xas, void *entry, unsigned int order,
1005 unsigned int sibs = (1 << (order % XA_CHUNK_SHIFT)) - 1;
1006 unsigned int mask = xas->xa_sibs;
1008 /* XXX: no support for splitting really large entries yet */
1009 if (WARN_ON(xas->xa_shift + 2 * XA_CHUNK_SHIFT < order))
1011 if (xas->xa_shift + XA_CHUNK_SHIFT > order)
1017 struct xa_node *node;
1019 node = kmem_cache_alloc(radix_tree_node_cachep, gfp);
1022 node->array = xas->xa;
1023 for (i = 0; i < XA_CHUNK_SIZE; i++) {
1024 if ((i & mask) == 0) {
1025 RCU_INIT_POINTER(node->slots[i], entry);
1026 sibling = xa_mk_sibling(0);
1028 RCU_INIT_POINTER(node->slots[i], sibling);
1031 RCU_INIT_POINTER(node->parent, xas->xa_alloc);
1032 xas->xa_alloc = node;
1033 } while (sibs-- > 0);
1038 xas_set_err(xas, -ENOMEM);
1040 EXPORT_SYMBOL_GPL(xas_split_alloc);
1043 * xas_split() - Split a multi-index entry into smaller entries.
1044 * @xas: XArray operation state.
1045 * @entry: New entry to store in the array.
1046 * @order: New entry order.
1048 * The value in the entry is copied to all the replacement entries.
1050 * Context: Any context. The caller should hold the xa_lock.
1052 void xas_split(struct xa_state *xas, void *entry, unsigned int order)
1054 unsigned int sibs = (1 << (order % XA_CHUNK_SHIFT)) - 1;
1055 unsigned int offset, marks;
1056 struct xa_node *node;
1057 void *curr = xas_load(xas);
1060 node = xas->xa_node;
1064 marks = node_get_marks(node, xas->xa_offset);
1066 offset = xas->xa_offset + sibs;
1068 if (xas->xa_shift < node->shift) {
1069 struct xa_node *child = xas->xa_alloc;
1071 xas->xa_alloc = rcu_dereference_raw(child->parent);
1072 child->shift = node->shift - XA_CHUNK_SHIFT;
1073 child->offset = offset;
1074 child->count = XA_CHUNK_SIZE;
1075 child->nr_values = xa_is_value(entry) ?
1077 RCU_INIT_POINTER(child->parent, node);
1078 node_set_marks(node, offset, child, marks);
1079 rcu_assign_pointer(node->slots[offset],
1081 if (xa_is_value(curr))
1083 xas_update(xas, child);
1085 unsigned int canon = offset - xas->xa_sibs;
1087 node_set_marks(node, canon, NULL, marks);
1088 rcu_assign_pointer(node->slots[canon], entry);
1089 while (offset > canon)
1090 rcu_assign_pointer(node->slots[offset--],
1091 xa_mk_sibling(canon));
1092 values += (xa_is_value(entry) - xa_is_value(curr)) *
1095 } while (offset-- > xas->xa_offset);
1097 node->nr_values += values;
1098 xas_update(xas, node);
1100 EXPORT_SYMBOL_GPL(xas_split);
1104 * xas_pause() - Pause a walk to drop a lock.
1105 * @xas: XArray operation state.
1107 * Some users need to pause a walk and drop the lock they're holding in
1108 * order to yield to a higher priority thread or carry out an operation
1109 * on an entry. Those users should call this function before they drop
1110 * the lock. It resets the @xas to be suitable for the next iteration
1111 * of the loop after the user has reacquired the lock. If most entries
1112 * found during a walk require you to call xas_pause(), the xa_for_each()
1113 * iterator may be more appropriate.
1115 * Note that xas_pause() only works for forward iteration. If a user needs
1116 * to pause a reverse iteration, we will need a xas_pause_rev().
1118 void xas_pause(struct xa_state *xas)
1120 struct xa_node *node = xas->xa_node;
1122 if (xas_invalid(xas))
1125 xas->xa_node = XAS_RESTART;
1127 unsigned long offset = xas->xa_offset;
1128 while (++offset < XA_CHUNK_SIZE) {
1129 if (!xa_is_sibling(xa_entry(xas->xa, node, offset)))
1132 xas->xa_index += (offset - xas->xa_offset) << node->shift;
1133 if (xas->xa_index == 0)
1134 xas->xa_node = XAS_BOUNDS;
1139 EXPORT_SYMBOL_GPL(xas_pause);
1142 * __xas_prev() - Find the previous entry in the XArray.
1143 * @xas: XArray operation state.
1145 * Helper function for xas_prev() which handles all the complex cases
1148 void *__xas_prev(struct xa_state *xas)
1152 if (!xas_frozen(xas->xa_node))
1155 return set_bounds(xas);
1156 if (xas_not_node(xas->xa_node))
1157 return xas_load(xas);
1159 if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node))
1162 while (xas->xa_offset == 255) {
1163 xas->xa_offset = xas->xa_node->offset - 1;
1164 xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1166 return set_bounds(xas);
1170 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1171 if (!xa_is_node(entry))
1174 xas->xa_node = xa_to_node(entry);
1175 xas_set_offset(xas);
1178 EXPORT_SYMBOL_GPL(__xas_prev);
1181 * __xas_next() - Find the next entry in the XArray.
1182 * @xas: XArray operation state.
1184 * Helper function for xas_next() which handles all the complex cases
1187 void *__xas_next(struct xa_state *xas)
1191 if (!xas_frozen(xas->xa_node))
1194 return set_bounds(xas);
1195 if (xas_not_node(xas->xa_node))
1196 return xas_load(xas);
1198 if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node))
1201 while (xas->xa_offset == XA_CHUNK_SIZE) {
1202 xas->xa_offset = xas->xa_node->offset + 1;
1203 xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1205 return set_bounds(xas);
1209 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1210 if (!xa_is_node(entry))
1213 xas->xa_node = xa_to_node(entry);
1214 xas_set_offset(xas);
1217 EXPORT_SYMBOL_GPL(__xas_next);
1220 * xas_find() - Find the next present entry in the XArray.
1221 * @xas: XArray operation state.
1222 * @max: Highest index to return.
1224 * If the @xas has not yet been walked to an entry, return the entry
1225 * which has an index >= xas.xa_index. If it has been walked, the entry
1226 * currently being pointed at has been processed, and so we move to the
1229 * If no entry is found and the array is smaller than @max, the iterator
1230 * is set to the smallest index not yet in the array. This allows @xas
1231 * to be immediately passed to xas_store().
1233 * Return: The entry, if found, otherwise %NULL.
1235 void *xas_find(struct xa_state *xas, unsigned long max)
1239 if (xas_error(xas) || xas->xa_node == XAS_BOUNDS)
1241 if (xas->xa_index > max)
1242 return set_bounds(xas);
1244 if (!xas->xa_node) {
1246 return set_bounds(xas);
1247 } else if (xas->xa_node == XAS_RESTART) {
1248 entry = xas_load(xas);
1249 if (entry || xas_not_node(xas->xa_node))
1251 } else if (!xas->xa_node->shift &&
1252 xas->xa_offset != (xas->xa_index & XA_CHUNK_MASK)) {
1253 xas->xa_offset = ((xas->xa_index - 1) & XA_CHUNK_MASK) + 1;
1258 while (xas->xa_node && (xas->xa_index <= max)) {
1259 if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) {
1260 xas->xa_offset = xas->xa_node->offset + 1;
1261 xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1265 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1266 if (xa_is_node(entry)) {
1267 xas->xa_node = xa_to_node(entry);
1271 if (entry && !xa_is_sibling(entry))
1278 xas->xa_node = XAS_BOUNDS;
1281 EXPORT_SYMBOL_GPL(xas_find);
1284 * xas_find_marked() - Find the next marked entry in the XArray.
1285 * @xas: XArray operation state.
1286 * @max: Highest index to return.
1287 * @mark: Mark number to search for.
1289 * If the @xas has not yet been walked to an entry, return the marked entry
1290 * which has an index >= xas.xa_index. If it has been walked, the entry
1291 * currently being pointed at has been processed, and so we return the
1292 * first marked entry with an index > xas.xa_index.
1294 * If no marked entry is found and the array is smaller than @max, @xas is
1295 * set to the bounds state and xas->xa_index is set to the smallest index
1296 * not yet in the array. This allows @xas to be immediately passed to
1299 * If no entry is found before @max is reached, @xas is set to the restart
1302 * Return: The entry, if found, otherwise %NULL.
1304 void *xas_find_marked(struct xa_state *xas, unsigned long max, xa_mark_t mark)
1306 bool advance = true;
1307 unsigned int offset;
1312 if (xas->xa_index > max)
1315 if (!xas->xa_node) {
1318 } else if (xas_top(xas->xa_node)) {
1320 entry = xa_head(xas->xa);
1321 xas->xa_node = NULL;
1322 if (xas->xa_index > max_index(entry))
1324 if (!xa_is_node(entry)) {
1325 if (xa_marked(xas->xa, mark))
1330 xas->xa_node = xa_to_node(entry);
1331 xas->xa_offset = xas->xa_index >> xas->xa_node->shift;
1334 while (xas->xa_index <= max) {
1335 if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) {
1336 xas->xa_offset = xas->xa_node->offset + 1;
1337 xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1345 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1346 if (xa_is_sibling(entry)) {
1347 xas->xa_offset = xa_to_sibling(entry);
1348 xas_move_index(xas, xas->xa_offset);
1352 offset = xas_find_chunk(xas, advance, mark);
1353 if (offset > xas->xa_offset) {
1355 xas_move_index(xas, offset);
1357 if ((xas->xa_index - 1) >= max)
1359 xas->xa_offset = offset;
1360 if (offset == XA_CHUNK_SIZE)
1364 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1365 if (!entry && !(xa_track_free(xas->xa) && mark == XA_FREE_MARK))
1367 if (!xa_is_node(entry))
1369 xas->xa_node = xa_to_node(entry);
1370 xas_set_offset(xas);
1374 if (xas->xa_index > max)
1376 return set_bounds(xas);
1378 xas->xa_node = XAS_RESTART;
1381 EXPORT_SYMBOL_GPL(xas_find_marked);
1384 * xas_find_conflict() - Find the next present entry in a range.
1385 * @xas: XArray operation state.
1387 * The @xas describes both a range and a position within that range.
1389 * Context: Any context. Expects xa_lock to be held.
1390 * Return: The next entry in the range covered by @xas or %NULL.
1392 void *xas_find_conflict(struct xa_state *xas)
1402 if (xas_top(xas->xa_node)) {
1403 curr = xas_start(xas);
1406 while (xa_is_node(curr)) {
1407 struct xa_node *node = xa_to_node(curr);
1408 curr = xas_descend(xas, node);
1414 if (xas->xa_node->shift > xas->xa_shift)
1418 if (xas->xa_node->shift == xas->xa_shift) {
1419 if ((xas->xa_offset & xas->xa_sibs) == xas->xa_sibs)
1421 } else if (xas->xa_offset == XA_CHUNK_MASK) {
1422 xas->xa_offset = xas->xa_node->offset;
1423 xas->xa_node = xa_parent_locked(xas->xa, xas->xa_node);
1428 curr = xa_entry_locked(xas->xa, xas->xa_node, ++xas->xa_offset);
1429 if (xa_is_sibling(curr))
1431 while (xa_is_node(curr)) {
1432 xas->xa_node = xa_to_node(curr);
1434 curr = xa_entry_locked(xas->xa, xas->xa_node, 0);
1439 xas->xa_offset -= xas->xa_sibs;
1442 EXPORT_SYMBOL_GPL(xas_find_conflict);
1445 * xa_load() - Load an entry from an XArray.
1447 * @index: index into array.
1449 * Context: Any context. Takes and releases the RCU lock.
1450 * Return: The entry at @index in @xa.
1452 void *xa_load(struct xarray *xa, unsigned long index)
1454 XA_STATE(xas, xa, index);
1459 entry = xas_load(&xas);
1460 if (xa_is_zero(entry))
1462 } while (xas_retry(&xas, entry));
1467 EXPORT_SYMBOL(xa_load);
1469 static void *xas_result(struct xa_state *xas, void *curr)
1471 if (xa_is_zero(curr))
1474 curr = xas->xa_node;
1479 * __xa_erase() - Erase this entry from the XArray while locked.
1481 * @index: Index into array.
1483 * After this function returns, loading from @index will return %NULL.
1484 * If the index is part of a multi-index entry, all indices will be erased
1485 * and none of the entries will be part of a multi-index entry.
1487 * Context: Any context. Expects xa_lock to be held on entry.
1488 * Return: The entry which used to be at this index.
1490 void *__xa_erase(struct xarray *xa, unsigned long index)
1492 XA_STATE(xas, xa, index);
1493 return xas_result(&xas, xas_store(&xas, NULL));
1495 EXPORT_SYMBOL(__xa_erase);
1498 * xa_erase() - Erase this entry from the XArray.
1500 * @index: Index of entry.
1502 * After this function returns, loading from @index will return %NULL.
1503 * If the index is part of a multi-index entry, all indices will be erased
1504 * and none of the entries will be part of a multi-index entry.
1506 * Context: Any context. Takes and releases the xa_lock.
1507 * Return: The entry which used to be at this index.
1509 void *xa_erase(struct xarray *xa, unsigned long index)
1514 entry = __xa_erase(xa, index);
1519 EXPORT_SYMBOL(xa_erase);
1522 * __xa_store() - Store this entry in the XArray.
1524 * @index: Index into array.
1525 * @entry: New entry.
1526 * @gfp: Memory allocation flags.
1528 * You must already be holding the xa_lock when calling this function.
1529 * It will drop the lock if needed to allocate memory, and then reacquire
1532 * Context: Any context. Expects xa_lock to be held on entry. May
1533 * release and reacquire xa_lock if @gfp flags permit.
1534 * Return: The old entry at this index or xa_err() if an error happened.
1536 void *__xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
1538 XA_STATE(xas, xa, index);
1541 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1542 return XA_ERROR(-EINVAL);
1543 if (xa_track_free(xa) && !entry)
1544 entry = XA_ZERO_ENTRY;
1547 curr = xas_store(&xas, entry);
1548 if (xa_track_free(xa))
1549 xas_clear_mark(&xas, XA_FREE_MARK);
1550 } while (__xas_nomem(&xas, gfp));
1552 return xas_result(&xas, curr);
1554 EXPORT_SYMBOL(__xa_store);
1557 * xa_store() - Store this entry in the XArray.
1559 * @index: Index into array.
1560 * @entry: New entry.
1561 * @gfp: Memory allocation flags.
1563 * After this function returns, loads from this index will return @entry.
1564 * Storing into an existing multi-index entry updates the entry of every index.
1565 * The marks associated with @index are unaffected unless @entry is %NULL.
1567 * Context: Any context. Takes and releases the xa_lock.
1568 * May sleep if the @gfp flags permit.
1569 * Return: The old entry at this index on success, xa_err(-EINVAL) if @entry
1570 * cannot be stored in an XArray, or xa_err(-ENOMEM) if memory allocation
1573 void *xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
1578 curr = __xa_store(xa, index, entry, gfp);
1583 EXPORT_SYMBOL(xa_store);
1586 * __xa_cmpxchg() - Store this entry in the XArray.
1588 * @index: Index into array.
1589 * @old: Old value to test against.
1590 * @entry: New entry.
1591 * @gfp: Memory allocation flags.
1593 * You must already be holding the xa_lock when calling this function.
1594 * It will drop the lock if needed to allocate memory, and then reacquire
1597 * Context: Any context. Expects xa_lock to be held on entry. May
1598 * release and reacquire xa_lock if @gfp flags permit.
1599 * Return: The old entry at this index or xa_err() if an error happened.
1601 void *__xa_cmpxchg(struct xarray *xa, unsigned long index,
1602 void *old, void *entry, gfp_t gfp)
1604 XA_STATE(xas, xa, index);
1607 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1608 return XA_ERROR(-EINVAL);
1611 curr = xas_load(&xas);
1613 xas_store(&xas, entry);
1614 if (xa_track_free(xa) && entry && !curr)
1615 xas_clear_mark(&xas, XA_FREE_MARK);
1617 } while (__xas_nomem(&xas, gfp));
1619 return xas_result(&xas, curr);
1621 EXPORT_SYMBOL(__xa_cmpxchg);
1624 * __xa_insert() - Store this entry in the XArray if no entry is present.
1626 * @index: Index into array.
1627 * @entry: New entry.
1628 * @gfp: Memory allocation flags.
1630 * Inserting a NULL entry will store a reserved entry (like xa_reserve())
1631 * if no entry is present. Inserting will fail if a reserved entry is
1632 * present, even though loading from this index will return NULL.
1634 * Context: Any context. Expects xa_lock to be held on entry. May
1635 * release and reacquire xa_lock if @gfp flags permit.
1636 * Return: 0 if the store succeeded. -EBUSY if another entry was present.
1637 * -ENOMEM if memory could not be allocated.
1639 int __xa_insert(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
1641 XA_STATE(xas, xa, index);
1644 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1647 entry = XA_ZERO_ENTRY;
1650 curr = xas_load(&xas);
1652 xas_store(&xas, entry);
1653 if (xa_track_free(xa))
1654 xas_clear_mark(&xas, XA_FREE_MARK);
1656 xas_set_err(&xas, -EBUSY);
1658 } while (__xas_nomem(&xas, gfp));
1660 return xas_error(&xas);
1662 EXPORT_SYMBOL(__xa_insert);
1664 #ifdef CONFIG_XARRAY_MULTI
1665 static void xas_set_range(struct xa_state *xas, unsigned long first,
1668 unsigned int shift = 0;
1669 unsigned long sibs = last - first;
1670 unsigned int offset = XA_CHUNK_MASK;
1672 xas_set(xas, first);
1674 while ((first & XA_CHUNK_MASK) == 0) {
1675 if (sibs < XA_CHUNK_MASK)
1677 if ((sibs == XA_CHUNK_MASK) && (offset < XA_CHUNK_MASK))
1679 shift += XA_CHUNK_SHIFT;
1680 if (offset == XA_CHUNK_MASK)
1681 offset = sibs & XA_CHUNK_MASK;
1682 sibs >>= XA_CHUNK_SHIFT;
1683 first >>= XA_CHUNK_SHIFT;
1686 offset = first & XA_CHUNK_MASK;
1687 if (offset + sibs > XA_CHUNK_MASK)
1688 sibs = XA_CHUNK_MASK - offset;
1689 if ((((first + sibs + 1) << shift) - 1) > last)
1692 xas->xa_shift = shift;
1693 xas->xa_sibs = sibs;
1697 * xa_store_range() - Store this entry at a range of indices in the XArray.
1699 * @first: First index to affect.
1700 * @last: Last index to affect.
1701 * @entry: New entry.
1702 * @gfp: Memory allocation flags.
1704 * After this function returns, loads from any index between @first and @last,
1705 * inclusive will return @entry.
1706 * Storing into an existing multi-index entry updates the entry of every index.
1707 * The marks associated with @index are unaffected unless @entry is %NULL.
1709 * Context: Process context. Takes and releases the xa_lock. May sleep
1710 * if the @gfp flags permit.
1711 * Return: %NULL on success, xa_err(-EINVAL) if @entry cannot be stored in
1712 * an XArray, or xa_err(-ENOMEM) if memory allocation failed.
1714 void *xa_store_range(struct xarray *xa, unsigned long first,
1715 unsigned long last, void *entry, gfp_t gfp)
1717 XA_STATE(xas, xa, 0);
1719 if (WARN_ON_ONCE(xa_is_internal(entry)))
1720 return XA_ERROR(-EINVAL);
1722 return XA_ERROR(-EINVAL);
1727 unsigned int order = BITS_PER_LONG;
1729 order = __ffs(last + 1);
1730 xas_set_order(&xas, last, order);
1731 xas_create(&xas, true);
1732 if (xas_error(&xas))
1736 xas_set_range(&xas, first, last);
1737 xas_store(&xas, entry);
1738 if (xas_error(&xas))
1740 first += xas_size(&xas);
1741 } while (first <= last);
1744 } while (xas_nomem(&xas, gfp));
1746 return xas_result(&xas, NULL);
1748 EXPORT_SYMBOL(xa_store_range);
1751 * xa_get_order() - Get the order of an entry.
1753 * @index: Index of the entry.
1755 * Return: A number between 0 and 63 indicating the order of the entry.
1757 int xa_get_order(struct xarray *xa, unsigned long index)
1759 XA_STATE(xas, xa, index);
1764 entry = xas_load(&xas);
1773 unsigned int slot = xas.xa_offset + (1 << order);
1775 if (slot >= XA_CHUNK_SIZE)
1777 if (!xa_is_sibling(xas.xa_node->slots[slot]))
1782 order += xas.xa_node->shift;
1788 EXPORT_SYMBOL(xa_get_order);
1789 #endif /* CONFIG_XARRAY_MULTI */
1792 * __xa_alloc() - Find somewhere to store this entry in the XArray.
1794 * @id: Pointer to ID.
1795 * @limit: Range for allocated ID.
1796 * @entry: New entry.
1797 * @gfp: Memory allocation flags.
1799 * Finds an empty entry in @xa between @limit.min and @limit.max,
1800 * stores the index into the @id pointer, then stores the entry at
1801 * that index. A concurrent lookup will not see an uninitialised @id.
1803 * Context: Any context. Expects xa_lock to be held on entry. May
1804 * release and reacquire xa_lock if @gfp flags permit.
1805 * Return: 0 on success, -ENOMEM if memory could not be allocated or
1806 * -EBUSY if there are no free entries in @limit.
1808 int __xa_alloc(struct xarray *xa, u32 *id, void *entry,
1809 struct xa_limit limit, gfp_t gfp)
1811 XA_STATE(xas, xa, 0);
1813 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1815 if (WARN_ON_ONCE(!xa_track_free(xa)))
1819 entry = XA_ZERO_ENTRY;
1822 xas.xa_index = limit.min;
1823 xas_find_marked(&xas, limit.max, XA_FREE_MARK);
1824 if (xas.xa_node == XAS_RESTART)
1825 xas_set_err(&xas, -EBUSY);
1828 xas_store(&xas, entry);
1829 xas_clear_mark(&xas, XA_FREE_MARK);
1830 } while (__xas_nomem(&xas, gfp));
1832 return xas_error(&xas);
1834 EXPORT_SYMBOL(__xa_alloc);
1837 * __xa_alloc_cyclic() - Find somewhere to store this entry in the XArray.
1839 * @id: Pointer to ID.
1840 * @entry: New entry.
1841 * @limit: Range of allocated ID.
1842 * @next: Pointer to next ID to allocate.
1843 * @gfp: Memory allocation flags.
1845 * Finds an empty entry in @xa between @limit.min and @limit.max,
1846 * stores the index into the @id pointer, then stores the entry at
1847 * that index. A concurrent lookup will not see an uninitialised @id.
1848 * The search for an empty entry will start at @next and will wrap
1849 * around if necessary.
1851 * Context: Any context. Expects xa_lock to be held on entry. May
1852 * release and reacquire xa_lock if @gfp flags permit.
1853 * Return: 0 if the allocation succeeded without wrapping. 1 if the
1854 * allocation succeeded after wrapping, -ENOMEM if memory could not be
1855 * allocated or -EBUSY if there are no free entries in @limit.
1857 int __xa_alloc_cyclic(struct xarray *xa, u32 *id, void *entry,
1858 struct xa_limit limit, u32 *next, gfp_t gfp)
1860 u32 min = limit.min;
1863 limit.min = max(min, *next);
1864 ret = __xa_alloc(xa, id, entry, limit, gfp);
1865 if ((xa->xa_flags & XA_FLAGS_ALLOC_WRAPPED) && ret == 0) {
1866 xa->xa_flags &= ~XA_FLAGS_ALLOC_WRAPPED;
1870 if (ret < 0 && limit.min > min) {
1872 ret = __xa_alloc(xa, id, entry, limit, gfp);
1880 xa->xa_flags |= XA_FLAGS_ALLOC_WRAPPED;
1884 EXPORT_SYMBOL(__xa_alloc_cyclic);
1887 * __xa_set_mark() - Set this mark on this entry while locked.
1889 * @index: Index of entry.
1890 * @mark: Mark number.
1892 * Attempting to set a mark on a %NULL entry does not succeed.
1894 * Context: Any context. Expects xa_lock to be held on entry.
1896 void __xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1898 XA_STATE(xas, xa, index);
1899 void *entry = xas_load(&xas);
1902 xas_set_mark(&xas, mark);
1904 EXPORT_SYMBOL(__xa_set_mark);
1907 * __xa_clear_mark() - Clear this mark on this entry while locked.
1909 * @index: Index of entry.
1910 * @mark: Mark number.
1912 * Context: Any context. Expects xa_lock to be held on entry.
1914 void __xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1916 XA_STATE(xas, xa, index);
1917 void *entry = xas_load(&xas);
1920 xas_clear_mark(&xas, mark);
1922 EXPORT_SYMBOL(__xa_clear_mark);
1925 * xa_get_mark() - Inquire whether this mark is set on this entry.
1927 * @index: Index of entry.
1928 * @mark: Mark number.
1930 * This function uses the RCU read lock, so the result may be out of date
1931 * by the time it returns. If you need the result to be stable, use a lock.
1933 * Context: Any context. Takes and releases the RCU lock.
1934 * Return: True if the entry at @index has this mark set, false if it doesn't.
1936 bool xa_get_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1938 XA_STATE(xas, xa, index);
1942 entry = xas_start(&xas);
1943 while (xas_get_mark(&xas, mark)) {
1944 if (!xa_is_node(entry))
1946 entry = xas_descend(&xas, xa_to_node(entry));
1954 EXPORT_SYMBOL(xa_get_mark);
1957 * xa_set_mark() - Set this mark on this entry.
1959 * @index: Index of entry.
1960 * @mark: Mark number.
1962 * Attempting to set a mark on a %NULL entry does not succeed.
1964 * Context: Process context. Takes and releases the xa_lock.
1966 void xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1969 __xa_set_mark(xa, index, mark);
1972 EXPORT_SYMBOL(xa_set_mark);
1975 * xa_clear_mark() - Clear this mark on this entry.
1977 * @index: Index of entry.
1978 * @mark: Mark number.
1980 * Clearing a mark always succeeds.
1982 * Context: Process context. Takes and releases the xa_lock.
1984 void xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1987 __xa_clear_mark(xa, index, mark);
1990 EXPORT_SYMBOL(xa_clear_mark);
1993 * xa_find() - Search the XArray for an entry.
1995 * @indexp: Pointer to an index.
1996 * @max: Maximum index to search to.
1997 * @filter: Selection criterion.
1999 * Finds the entry in @xa which matches the @filter, and has the lowest
2000 * index that is at least @indexp and no more than @max.
2001 * If an entry is found, @indexp is updated to be the index of the entry.
2002 * This function is protected by the RCU read lock, so it may not find
2003 * entries which are being simultaneously added. It will not return an
2004 * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
2006 * Context: Any context. Takes and releases the RCU lock.
2007 * Return: The entry, if found, otherwise %NULL.
2009 void *xa_find(struct xarray *xa, unsigned long *indexp,
2010 unsigned long max, xa_mark_t filter)
2012 XA_STATE(xas, xa, *indexp);
2017 if ((__force unsigned int)filter < XA_MAX_MARKS)
2018 entry = xas_find_marked(&xas, max, filter);
2020 entry = xas_find(&xas, max);
2021 } while (xas_retry(&xas, entry));
2025 *indexp = xas.xa_index;
2028 EXPORT_SYMBOL(xa_find);
2030 static bool xas_sibling(struct xa_state *xas)
2032 struct xa_node *node = xas->xa_node;
2037 mask = (XA_CHUNK_SIZE << node->shift) - 1;
2038 return (xas->xa_index & mask) >
2039 ((unsigned long)xas->xa_offset << node->shift);
2043 * xa_find_after() - Search the XArray for a present entry.
2045 * @indexp: Pointer to an index.
2046 * @max: Maximum index to search to.
2047 * @filter: Selection criterion.
2049 * Finds the entry in @xa which matches the @filter and has the lowest
2050 * index that is above @indexp and no more than @max.
2051 * If an entry is found, @indexp is updated to be the index of the entry.
2052 * This function is protected by the RCU read lock, so it may miss entries
2053 * which are being simultaneously added. It will not return an
2054 * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
2056 * Context: Any context. Takes and releases the RCU lock.
2057 * Return: The pointer, if found, otherwise %NULL.
2059 void *xa_find_after(struct xarray *xa, unsigned long *indexp,
2060 unsigned long max, xa_mark_t filter)
2062 XA_STATE(xas, xa, *indexp + 1);
2065 if (xas.xa_index == 0)
2070 if ((__force unsigned int)filter < XA_MAX_MARKS)
2071 entry = xas_find_marked(&xas, max, filter);
2073 entry = xas_find(&xas, max);
2075 if (xas_invalid(&xas))
2077 if (xas_sibling(&xas))
2079 if (!xas_retry(&xas, entry))
2085 *indexp = xas.xa_index;
2088 EXPORT_SYMBOL(xa_find_after);
2090 static unsigned int xas_extract_present(struct xa_state *xas, void **dst,
2091 unsigned long max, unsigned int n)
2097 xas_for_each(xas, entry, max) {
2098 if (xas_retry(xas, entry))
2109 static unsigned int xas_extract_marked(struct xa_state *xas, void **dst,
2110 unsigned long max, unsigned int n, xa_mark_t mark)
2116 xas_for_each_marked(xas, entry, max, mark) {
2117 if (xas_retry(xas, entry))
2129 * xa_extract() - Copy selected entries from the XArray into a normal array.
2130 * @xa: The source XArray to copy from.
2131 * @dst: The buffer to copy entries into.
2132 * @start: The first index in the XArray eligible to be selected.
2133 * @max: The last index in the XArray eligible to be selected.
2134 * @n: The maximum number of entries to copy.
2135 * @filter: Selection criterion.
2137 * Copies up to @n entries that match @filter from the XArray. The
2138 * copied entries will have indices between @start and @max, inclusive.
2140 * The @filter may be an XArray mark value, in which case entries which are
2141 * marked with that mark will be copied. It may also be %XA_PRESENT, in
2142 * which case all entries which are not %NULL will be copied.
2144 * The entries returned may not represent a snapshot of the XArray at a
2145 * moment in time. For example, if another thread stores to index 5, then
2146 * index 10, calling xa_extract() may return the old contents of index 5
2147 * and the new contents of index 10. Indices not modified while this
2148 * function is running will not be skipped.
2150 * If you need stronger guarantees, holding the xa_lock across calls to this
2151 * function will prevent concurrent modification.
2153 * Context: Any context. Takes and releases the RCU lock.
2154 * Return: The number of entries copied.
2156 unsigned int xa_extract(struct xarray *xa, void **dst, unsigned long start,
2157 unsigned long max, unsigned int n, xa_mark_t filter)
2159 XA_STATE(xas, xa, start);
2164 if ((__force unsigned int)filter < XA_MAX_MARKS)
2165 return xas_extract_marked(&xas, dst, max, n, filter);
2166 return xas_extract_present(&xas, dst, max, n);
2168 EXPORT_SYMBOL(xa_extract);
2171 * xa_destroy() - Free all internal data structures.
2174 * After calling this function, the XArray is empty and has freed all memory
2175 * allocated for its internal data structures. You are responsible for
2176 * freeing the objects referenced by the XArray.
2178 * Context: Any context. Takes and releases the xa_lock, interrupt-safe.
2180 void xa_destroy(struct xarray *xa)
2182 XA_STATE(xas, xa, 0);
2183 unsigned long flags;
2187 xas_lock_irqsave(&xas, flags);
2188 entry = xa_head_locked(xa);
2189 RCU_INIT_POINTER(xa->xa_head, NULL);
2190 xas_init_marks(&xas);
2191 if (xa_zero_busy(xa))
2192 xa_mark_clear(xa, XA_FREE_MARK);
2193 /* lockdep checks we're still holding the lock in xas_free_nodes() */
2194 if (xa_is_node(entry))
2195 xas_free_nodes(&xas, xa_to_node(entry));
2196 xas_unlock_irqrestore(&xas, flags);
2198 EXPORT_SYMBOL(xa_destroy);
2201 void xa_dump_node(const struct xa_node *node)
2207 if ((unsigned long)node & 3) {
2208 pr_cont("node %px\n", node);
2212 pr_cont("node %px %s %d parent %px shift %d count %d values %d "
2213 "array %px list %px %px marks",
2214 node, node->parent ? "offset" : "max", node->offset,
2215 node->parent, node->shift, node->count, node->nr_values,
2216 node->array, node->private_list.prev, node->private_list.next);
2217 for (i = 0; i < XA_MAX_MARKS; i++)
2218 for (j = 0; j < XA_MARK_LONGS; j++)
2219 pr_cont(" %lx", node->marks[i][j]);
2223 void xa_dump_index(unsigned long index, unsigned int shift)
2226 pr_info("%lu: ", index);
2227 else if (shift >= BITS_PER_LONG)
2228 pr_info("0-%lu: ", ~0UL);
2230 pr_info("%lu-%lu: ", index, index | ((1UL << shift) - 1));
2233 void xa_dump_entry(const void *entry, unsigned long index, unsigned long shift)
2238 xa_dump_index(index, shift);
2240 if (xa_is_node(entry)) {
2242 pr_cont("%px\n", entry);
2245 struct xa_node *node = xa_to_node(entry);
2247 for (i = 0; i < XA_CHUNK_SIZE; i++)
2248 xa_dump_entry(node->slots[i],
2249 index + (i << node->shift), node->shift);
2251 } else if (xa_is_value(entry))
2252 pr_cont("value %ld (0x%lx) [%px]\n", xa_to_value(entry),
2253 xa_to_value(entry), entry);
2254 else if (!xa_is_internal(entry))
2255 pr_cont("%px\n", entry);
2256 else if (xa_is_retry(entry))
2257 pr_cont("retry (%ld)\n", xa_to_internal(entry));
2258 else if (xa_is_sibling(entry))
2259 pr_cont("sibling (slot %ld)\n", xa_to_sibling(entry));
2260 else if (xa_is_zero(entry))
2261 pr_cont("zero (%ld)\n", xa_to_internal(entry));
2263 pr_cont("UNKNOWN ENTRY (%px)\n", entry);
2266 void xa_dump(const struct xarray *xa)
2268 void *entry = xa->xa_head;
2269 unsigned int shift = 0;
2271 pr_info("xarray: %px head %px flags %x marks %d %d %d\n", xa, entry,
2272 xa->xa_flags, xa_marked(xa, XA_MARK_0),
2273 xa_marked(xa, XA_MARK_1), xa_marked(xa, XA_MARK_2));
2274 if (xa_is_node(entry))
2275 shift = xa_to_node(entry)->shift + XA_CHUNK_SHIFT;
2276 xa_dump_entry(entry, 0, shift);