1 // SPDX-License-Identifier: GPL-2.0+
3 * XArray implementation
4 * Copyright (c) 2017 Microsoft Corporation
5 * Author: Matthew Wilcox <willy@infradead.org>
8 #include <linux/bitmap.h>
9 #include <linux/export.h>
10 #include <linux/list.h>
11 #include <linux/slab.h>
12 #include <linux/xarray.h>
15 * Coding conventions in this file:
17 * @xa is used to refer to the entire xarray.
18 * @xas is the 'xarray operation state'. It may be either a pointer to
19 * an xa_state, or an xa_state stored on the stack. This is an unfortunate
21 * @index is the index of the entry being operated on
22 * @mark is an xa_mark_t; a small number indicating one of the mark bits.
23 * @node refers to an xa_node; usually the primary one being operated on by
25 * @offset is the index into the slots array inside an xa_node.
26 * @parent refers to the @xa_node closer to the head than @node.
27 * @entry refers to something stored in a slot in the xarray
30 static inline unsigned int xa_lock_type(const struct xarray *xa)
32 return (__force unsigned int)xa->xa_flags & 3;
35 static inline void xas_lock_type(struct xa_state *xas, unsigned int lock_type)
37 if (lock_type == XA_LOCK_IRQ)
39 else if (lock_type == XA_LOCK_BH)
45 static inline void xas_unlock_type(struct xa_state *xas, unsigned int lock_type)
47 if (lock_type == XA_LOCK_IRQ)
49 else if (lock_type == XA_LOCK_BH)
55 static inline bool xa_track_free(const struct xarray *xa)
57 return xa->xa_flags & XA_FLAGS_TRACK_FREE;
60 static inline bool xa_zero_busy(const struct xarray *xa)
62 return xa->xa_flags & XA_FLAGS_ZERO_BUSY;
65 static inline void xa_mark_set(struct xarray *xa, xa_mark_t mark)
67 if (!(xa->xa_flags & XA_FLAGS_MARK(mark)))
68 xa->xa_flags |= XA_FLAGS_MARK(mark);
71 static inline void xa_mark_clear(struct xarray *xa, xa_mark_t mark)
73 if (xa->xa_flags & XA_FLAGS_MARK(mark))
74 xa->xa_flags &= ~(XA_FLAGS_MARK(mark));
77 static inline unsigned long *node_marks(struct xa_node *node, xa_mark_t mark)
79 return node->marks[(__force unsigned)mark];
82 static inline bool node_get_mark(struct xa_node *node,
83 unsigned int offset, xa_mark_t mark)
85 return test_bit(offset, node_marks(node, mark));
88 /* returns true if the bit was set */
89 static inline bool node_set_mark(struct xa_node *node, unsigned int offset,
92 return __test_and_set_bit(offset, node_marks(node, mark));
95 /* returns true if the bit was set */
96 static inline bool node_clear_mark(struct xa_node *node, unsigned int offset,
99 return __test_and_clear_bit(offset, node_marks(node, mark));
102 static inline bool node_any_mark(struct xa_node *node, xa_mark_t mark)
104 return !bitmap_empty(node_marks(node, mark), XA_CHUNK_SIZE);
107 static inline void node_mark_all(struct xa_node *node, xa_mark_t mark)
109 bitmap_fill(node_marks(node, mark), XA_CHUNK_SIZE);
112 #define mark_inc(mark) do { \
113 mark = (__force xa_mark_t)((__force unsigned)(mark) + 1); \
117 * xas_squash_marks() - Merge all marks to the first entry
118 * @xas: Array operation state.
120 * Set a mark on the first entry if any entry has it set. Clear marks on
121 * all sibling entries.
123 static void xas_squash_marks(const struct xa_state *xas)
125 unsigned int mark = 0;
126 unsigned int limit = xas->xa_offset + xas->xa_sibs + 1;
132 unsigned long *marks = xas->xa_node->marks[mark];
133 if (find_next_bit(marks, limit, xas->xa_offset + 1) == limit)
135 __set_bit(xas->xa_offset, marks);
136 bitmap_clear(marks, xas->xa_offset + 1, xas->xa_sibs);
137 } while (mark++ != (__force unsigned)XA_MARK_MAX);
140 /* extracts the offset within this node from the index */
141 static unsigned int get_offset(unsigned long index, struct xa_node *node)
143 return (index >> node->shift) & XA_CHUNK_MASK;
146 static void xas_set_offset(struct xa_state *xas)
148 xas->xa_offset = get_offset(xas->xa_index, xas->xa_node);
151 /* move the index either forwards (find) or backwards (sibling slot) */
152 static void xas_move_index(struct xa_state *xas, unsigned long offset)
154 unsigned int shift = xas->xa_node->shift;
155 xas->xa_index &= ~XA_CHUNK_MASK << shift;
156 xas->xa_index += offset << shift;
159 static void xas_advance(struct xa_state *xas)
162 xas_move_index(xas, xas->xa_offset);
165 static void *set_bounds(struct xa_state *xas)
167 xas->xa_node = XAS_BOUNDS;
172 * Starts a walk. If the @xas is already valid, we assume that it's on
173 * the right path and just return where we've got to. If we're in an
174 * error state, return NULL. If the index is outside the current scope
175 * of the xarray, return NULL without changing @xas->xa_node. Otherwise
176 * set @xas->xa_node to NULL and return the current head of the array.
178 static void *xas_start(struct xa_state *xas)
183 return xas_reload(xas);
187 entry = xa_head(xas->xa);
188 if (!xa_is_node(entry)) {
190 return set_bounds(xas);
192 if ((xas->xa_index >> xa_to_node(entry)->shift) > XA_CHUNK_MASK)
193 return set_bounds(xas);
200 static void *xas_descend(struct xa_state *xas, struct xa_node *node)
202 unsigned int offset = get_offset(xas->xa_index, node);
203 void *entry = xa_entry(xas->xa, node, offset);
206 if (xa_is_sibling(entry)) {
207 offset = xa_to_sibling(entry);
208 entry = xa_entry(xas->xa, node, offset);
211 xas->xa_offset = offset;
216 * xas_load() - Load an entry from the XArray (advanced).
217 * @xas: XArray operation state.
219 * Usually walks the @xas to the appropriate state to load the entry
220 * stored at xa_index. However, it will do nothing and return %NULL if
221 * @xas is in an error state. xas_load() will never expand the tree.
223 * If the xa_state is set up to operate on a multi-index entry, xas_load()
224 * may return %NULL or an internal entry, even if there are entries
225 * present within the range specified by @xas.
227 * Context: Any context. The caller should hold the xa_lock or the RCU lock.
228 * Return: Usually an entry in the XArray, but see description for exceptions.
230 void *xas_load(struct xa_state *xas)
232 void *entry = xas_start(xas);
234 while (xa_is_node(entry)) {
235 struct xa_node *node = xa_to_node(entry);
237 if (xas->xa_shift > node->shift)
239 entry = xas_descend(xas, node);
240 if (node->shift == 0)
245 EXPORT_SYMBOL_GPL(xas_load);
247 /* Move the radix tree node cache here */
248 extern struct kmem_cache *radix_tree_node_cachep;
249 extern void radix_tree_node_rcu_free(struct rcu_head *head);
251 #define XA_RCU_FREE ((struct xarray *)1)
253 static void xa_node_free(struct xa_node *node)
255 XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
256 node->array = XA_RCU_FREE;
257 call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
261 * xas_destroy() - Free any resources allocated during the XArray operation.
262 * @xas: XArray operation state.
264 * This function is now internal-only.
266 static void xas_destroy(struct xa_state *xas)
268 struct xa_node *node = xas->xa_alloc;
272 XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
273 kmem_cache_free(radix_tree_node_cachep, node);
274 xas->xa_alloc = NULL;
278 * xas_nomem() - Allocate memory if needed.
279 * @xas: XArray operation state.
280 * @gfp: Memory allocation flags.
282 * If we need to add new nodes to the XArray, we try to allocate memory
283 * with GFP_NOWAIT while holding the lock, which will usually succeed.
284 * If it fails, @xas is flagged as needing memory to continue. The caller
285 * should drop the lock and call xas_nomem(). If xas_nomem() succeeds,
286 * the caller should retry the operation.
288 * Forward progress is guaranteed as one node is allocated here and
289 * stored in the xa_state where it will be found by xas_alloc(). More
290 * nodes will likely be found in the slab allocator, but we do not tie
293 * Return: true if memory was needed, and was successfully allocated.
295 bool xas_nomem(struct xa_state *xas, gfp_t gfp)
297 if (xas->xa_node != XA_ERROR(-ENOMEM)) {
301 if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT)
302 gfp |= __GFP_ACCOUNT;
303 xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp);
306 XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list));
307 xas->xa_node = XAS_RESTART;
310 EXPORT_SYMBOL_GPL(xas_nomem);
313 * __xas_nomem() - Drop locks and allocate memory if needed.
314 * @xas: XArray operation state.
315 * @gfp: Memory allocation flags.
317 * Internal variant of xas_nomem().
319 * Return: true if memory was needed, and was successfully allocated.
321 static bool __xas_nomem(struct xa_state *xas, gfp_t gfp)
322 __must_hold(xas->xa->xa_lock)
324 unsigned int lock_type = xa_lock_type(xas->xa);
326 if (xas->xa_node != XA_ERROR(-ENOMEM)) {
330 if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT)
331 gfp |= __GFP_ACCOUNT;
332 if (gfpflags_allow_blocking(gfp)) {
333 xas_unlock_type(xas, lock_type);
334 xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp);
335 xas_lock_type(xas, lock_type);
337 xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp);
341 XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list));
342 xas->xa_node = XAS_RESTART;
346 static void xas_update(struct xa_state *xas, struct xa_node *node)
349 xas->xa_update(node);
351 XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
354 static void *xas_alloc(struct xa_state *xas, unsigned int shift)
356 struct xa_node *parent = xas->xa_node;
357 struct xa_node *node = xas->xa_alloc;
359 if (xas_invalid(xas))
363 xas->xa_alloc = NULL;
365 gfp_t gfp = GFP_NOWAIT | __GFP_NOWARN;
367 if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT)
368 gfp |= __GFP_ACCOUNT;
370 node = kmem_cache_alloc(radix_tree_node_cachep, gfp);
372 xas_set_err(xas, -ENOMEM);
378 node->offset = xas->xa_offset;
380 XA_NODE_BUG_ON(node, parent->count > XA_CHUNK_SIZE);
381 xas_update(xas, parent);
383 XA_NODE_BUG_ON(node, shift > BITS_PER_LONG);
384 XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
388 RCU_INIT_POINTER(node->parent, xas->xa_node);
389 node->array = xas->xa;
394 #ifdef CONFIG_XARRAY_MULTI
395 /* Returns the number of indices covered by a given xa_state */
396 static unsigned long xas_size(const struct xa_state *xas)
398 return (xas->xa_sibs + 1UL) << xas->xa_shift;
403 * Use this to calculate the maximum index that will need to be created
404 * in order to add the entry described by @xas. Because we cannot store a
405 * multiple-index entry at index 0, the calculation is a little more complex
406 * than you might expect.
408 static unsigned long xas_max(struct xa_state *xas)
410 unsigned long max = xas->xa_index;
412 #ifdef CONFIG_XARRAY_MULTI
413 if (xas->xa_shift || xas->xa_sibs) {
414 unsigned long mask = xas_size(xas) - 1;
424 /* The maximum index that can be contained in the array without expanding it */
425 static unsigned long max_index(void *entry)
427 if (!xa_is_node(entry))
429 return (XA_CHUNK_SIZE << xa_to_node(entry)->shift) - 1;
432 static void xas_shrink(struct xa_state *xas)
434 struct xarray *xa = xas->xa;
435 struct xa_node *node = xas->xa_node;
440 XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
441 if (node->count != 1)
443 entry = xa_entry_locked(xa, node, 0);
446 if (!xa_is_node(entry) && node->shift)
448 if (xa_is_zero(entry) && xa_zero_busy(xa))
450 xas->xa_node = XAS_BOUNDS;
452 RCU_INIT_POINTER(xa->xa_head, entry);
453 if (xa_track_free(xa) && !node_get_mark(node, 0, XA_FREE_MARK))
454 xa_mark_clear(xa, XA_FREE_MARK);
458 if (!xa_is_node(entry))
459 RCU_INIT_POINTER(node->slots[0], XA_RETRY_ENTRY);
460 xas_update(xas, node);
462 if (!xa_is_node(entry))
464 node = xa_to_node(entry);
470 * xas_delete_node() - Attempt to delete an xa_node
471 * @xas: Array operation state.
473 * Attempts to delete the @xas->xa_node. This will fail if xa->node has
474 * a non-zero reference count.
476 static void xas_delete_node(struct xa_state *xas)
478 struct xa_node *node = xas->xa_node;
481 struct xa_node *parent;
483 XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
487 parent = xa_parent_locked(xas->xa, node);
488 xas->xa_node = parent;
489 xas->xa_offset = node->offset;
493 xas->xa->xa_head = NULL;
494 xas->xa_node = XAS_BOUNDS;
498 parent->slots[xas->xa_offset] = NULL;
500 XA_NODE_BUG_ON(parent, parent->count > XA_CHUNK_SIZE);
502 xas_update(xas, node);
510 * xas_free_nodes() - Free this node and all nodes that it references
511 * @xas: Array operation state.
514 * This node has been removed from the tree. We must now free it and all
515 * of its subnodes. There may be RCU walkers with references into the tree,
516 * so we must replace all entries with retry markers.
518 static void xas_free_nodes(struct xa_state *xas, struct xa_node *top)
520 unsigned int offset = 0;
521 struct xa_node *node = top;
524 void *entry = xa_entry_locked(xas->xa, node, offset);
526 if (node->shift && xa_is_node(entry)) {
527 node = xa_to_node(entry);
532 RCU_INIT_POINTER(node->slots[offset], XA_RETRY_ENTRY);
534 while (offset == XA_CHUNK_SIZE) {
535 struct xa_node *parent;
537 parent = xa_parent_locked(xas->xa, node);
538 offset = node->offset + 1;
541 xas_update(xas, node);
551 * xas_expand adds nodes to the head of the tree until it has reached
552 * sufficient height to be able to contain @xas->xa_index
554 static int xas_expand(struct xa_state *xas, void *head)
556 struct xarray *xa = xas->xa;
557 struct xa_node *node = NULL;
558 unsigned int shift = 0;
559 unsigned long max = xas_max(xas);
564 while ((max >> shift) >= XA_CHUNK_SIZE)
565 shift += XA_CHUNK_SHIFT;
566 return shift + XA_CHUNK_SHIFT;
567 } else if (xa_is_node(head)) {
568 node = xa_to_node(head);
569 shift = node->shift + XA_CHUNK_SHIFT;
573 while (max > max_index(head)) {
576 XA_NODE_BUG_ON(node, shift > BITS_PER_LONG);
577 node = xas_alloc(xas, shift);
582 if (xa_is_value(head))
584 RCU_INIT_POINTER(node->slots[0], head);
586 /* Propagate the aggregated mark info to the new child */
588 if (xa_track_free(xa) && mark == XA_FREE_MARK) {
589 node_mark_all(node, XA_FREE_MARK);
590 if (!xa_marked(xa, XA_FREE_MARK)) {
591 node_clear_mark(node, 0, XA_FREE_MARK);
592 xa_mark_set(xa, XA_FREE_MARK);
594 } else if (xa_marked(xa, mark)) {
595 node_set_mark(node, 0, mark);
597 if (mark == XA_MARK_MAX)
603 * Now that the new node is fully initialised, we can add
606 if (xa_is_node(head)) {
607 xa_to_node(head)->offset = 0;
608 rcu_assign_pointer(xa_to_node(head)->parent, node);
610 head = xa_mk_node(node);
611 rcu_assign_pointer(xa->xa_head, head);
612 xas_update(xas, node);
614 shift += XA_CHUNK_SHIFT;
622 * xas_create() - Create a slot to store an entry in.
623 * @xas: XArray operation state.
624 * @allow_root: %true if we can store the entry in the root directly
626 * Most users will not need to call this function directly, as it is called
627 * by xas_store(). It is useful for doing conditional store operations
628 * (see the xa_cmpxchg() implementation for an example).
630 * Return: If the slot already existed, returns the contents of this slot.
631 * If the slot was newly created, returns %NULL. If it failed to create the
632 * slot, returns %NULL and indicates the error in @xas.
634 static void *xas_create(struct xa_state *xas, bool allow_root)
636 struct xarray *xa = xas->xa;
639 struct xa_node *node = xas->xa_node;
641 unsigned int order = xas->xa_shift;
644 entry = xa_head_locked(xa);
646 if (!entry && xa_zero_busy(xa))
647 entry = XA_ZERO_ENTRY;
648 shift = xas_expand(xas, entry);
651 if (!shift && !allow_root)
652 shift = XA_CHUNK_SHIFT;
653 entry = xa_head_locked(xa);
655 } else if (xas_error(xas)) {
658 unsigned int offset = xas->xa_offset;
661 entry = xa_entry_locked(xa, node, offset);
662 slot = &node->slots[offset];
665 entry = xa_head_locked(xa);
669 while (shift > order) {
670 shift -= XA_CHUNK_SHIFT;
672 node = xas_alloc(xas, shift);
675 if (xa_track_free(xa))
676 node_mark_all(node, XA_FREE_MARK);
677 rcu_assign_pointer(*slot, xa_mk_node(node));
678 } else if (xa_is_node(entry)) {
679 node = xa_to_node(entry);
683 entry = xas_descend(xas, node);
684 slot = &node->slots[xas->xa_offset];
691 * xas_create_range() - Ensure that stores to this range will succeed
692 * @xas: XArray operation state.
694 * Creates all of the slots in the range covered by @xas. Sets @xas to
695 * create single-index entries and positions it at the beginning of the
696 * range. This is for the benefit of users which have not yet been
697 * converted to use multi-index entries.
699 void xas_create_range(struct xa_state *xas)
701 unsigned long index = xas->xa_index;
702 unsigned char shift = xas->xa_shift;
703 unsigned char sibs = xas->xa_sibs;
705 xas->xa_index |= ((sibs + 1) << shift) - 1;
706 if (xas_is_node(xas) && xas->xa_node->shift == xas->xa_shift)
707 xas->xa_offset |= sibs;
712 xas_create(xas, true);
715 if (xas->xa_index <= (index | XA_CHUNK_MASK))
717 xas->xa_index -= XA_CHUNK_SIZE;
720 struct xa_node *node = xas->xa_node;
721 xas->xa_node = xa_parent_locked(xas->xa, node);
722 xas->xa_offset = node->offset - 1;
723 if (node->offset != 0)
729 xas->xa_shift = shift;
731 xas->xa_index = index;
734 xas->xa_index = index;
738 EXPORT_SYMBOL_GPL(xas_create_range);
740 static void update_node(struct xa_state *xas, struct xa_node *node,
741 int count, int values)
743 if (!node || (!count && !values))
746 node->count += count;
747 node->nr_values += values;
748 XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
749 XA_NODE_BUG_ON(node, node->nr_values > XA_CHUNK_SIZE);
750 xas_update(xas, node);
752 xas_delete_node(xas);
756 * xas_store() - Store this entry in the XArray.
757 * @xas: XArray operation state.
760 * If @xas is operating on a multi-index entry, the entry returned by this
761 * function is essentially meaningless (it may be an internal entry or it
762 * may be %NULL, even if there are non-NULL entries at some of the indices
763 * covered by the range). This is not a problem for any current users,
764 * and can be changed if needed.
766 * Return: The old entry at this index.
768 void *xas_store(struct xa_state *xas, void *entry)
770 struct xa_node *node;
771 void __rcu **slot = &xas->xa->xa_head;
772 unsigned int offset, max;
776 bool value = xa_is_value(entry);
779 bool allow_root = !xa_is_node(entry) && !xa_is_zero(entry);
780 first = xas_create(xas, allow_root);
782 first = xas_load(xas);
785 if (xas_invalid(xas))
788 if (node && (xas->xa_shift < node->shift))
790 if ((first == entry) && !xas->xa_sibs)
794 offset = xas->xa_offset;
795 max = xas->xa_offset + xas->xa_sibs;
797 slot = &node->slots[offset];
799 xas_squash_marks(xas);
806 * Must clear the marks before setting the entry to NULL,
807 * otherwise xas_for_each_marked may find a NULL entry and
808 * stop early. rcu_assign_pointer contains a release barrier
809 * so the mark clearing will appear to happen before the
810 * entry is set to NULL.
812 rcu_assign_pointer(*slot, entry);
813 if (xa_is_node(next) && (!node || node->shift))
814 xas_free_nodes(xas, xa_to_node(next));
817 count += !next - !entry;
818 values += !xa_is_value(first) - !value;
822 if (!xa_is_sibling(entry))
823 entry = xa_mk_sibling(xas->xa_offset);
825 if (offset == XA_CHUNK_MASK)
828 next = xa_entry_locked(xas->xa, node, ++offset);
829 if (!xa_is_sibling(next)) {
830 if (!entry && (offset > max))
837 update_node(xas, node, count, values);
840 EXPORT_SYMBOL_GPL(xas_store);
843 * xas_get_mark() - Returns the state of this mark.
844 * @xas: XArray operation state.
845 * @mark: Mark number.
847 * Return: true if the mark is set, false if the mark is clear or @xas
848 * is in an error state.
850 bool xas_get_mark(const struct xa_state *xas, xa_mark_t mark)
852 if (xas_invalid(xas))
855 return xa_marked(xas->xa, mark);
856 return node_get_mark(xas->xa_node, xas->xa_offset, mark);
858 EXPORT_SYMBOL_GPL(xas_get_mark);
861 * xas_set_mark() - Sets the mark on this entry and its parents.
862 * @xas: XArray operation state.
863 * @mark: Mark number.
865 * Sets the specified mark on this entry, and walks up the tree setting it
866 * on all the ancestor entries. Does nothing if @xas has not been walked to
867 * an entry, or is in an error state.
869 void xas_set_mark(const struct xa_state *xas, xa_mark_t mark)
871 struct xa_node *node = xas->xa_node;
872 unsigned int offset = xas->xa_offset;
874 if (xas_invalid(xas))
878 if (node_set_mark(node, offset, mark))
880 offset = node->offset;
881 node = xa_parent_locked(xas->xa, node);
884 if (!xa_marked(xas->xa, mark))
885 xa_mark_set(xas->xa, mark);
887 EXPORT_SYMBOL_GPL(xas_set_mark);
890 * xas_clear_mark() - Clears the mark on this entry and its parents.
891 * @xas: XArray operation state.
892 * @mark: Mark number.
894 * Clears the specified mark on this entry, and walks back to the head
895 * attempting to clear it on all the ancestor entries. Does nothing if
896 * @xas has not been walked to an entry, or is in an error state.
898 void xas_clear_mark(const struct xa_state *xas, xa_mark_t mark)
900 struct xa_node *node = xas->xa_node;
901 unsigned int offset = xas->xa_offset;
903 if (xas_invalid(xas))
907 if (!node_clear_mark(node, offset, mark))
909 if (node_any_mark(node, mark))
912 offset = node->offset;
913 node = xa_parent_locked(xas->xa, node);
916 if (xa_marked(xas->xa, mark))
917 xa_mark_clear(xas->xa, mark);
919 EXPORT_SYMBOL_GPL(xas_clear_mark);
922 * xas_init_marks() - Initialise all marks for the entry
923 * @xas: Array operations state.
925 * Initialise all marks for the entry specified by @xas. If we're tracking
926 * free entries with a mark, we need to set it on all entries. All other
929 * This implementation is not as efficient as it could be; we may walk
930 * up the tree multiple times.
932 void xas_init_marks(const struct xa_state *xas)
937 if (xa_track_free(xas->xa) && mark == XA_FREE_MARK)
938 xas_set_mark(xas, mark);
940 xas_clear_mark(xas, mark);
941 if (mark == XA_MARK_MAX)
946 EXPORT_SYMBOL_GPL(xas_init_marks);
949 * xas_pause() - Pause a walk to drop a lock.
950 * @xas: XArray operation state.
952 * Some users need to pause a walk and drop the lock they're holding in
953 * order to yield to a higher priority thread or carry out an operation
954 * on an entry. Those users should call this function before they drop
955 * the lock. It resets the @xas to be suitable for the next iteration
956 * of the loop after the user has reacquired the lock. If most entries
957 * found during a walk require you to call xas_pause(), the xa_for_each()
958 * iterator may be more appropriate.
960 * Note that xas_pause() only works for forward iteration. If a user needs
961 * to pause a reverse iteration, we will need a xas_pause_rev().
963 void xas_pause(struct xa_state *xas)
965 struct xa_node *node = xas->xa_node;
967 if (xas_invalid(xas))
970 xas->xa_node = XAS_RESTART;
972 unsigned int offset = xas->xa_offset;
973 while (++offset < XA_CHUNK_SIZE) {
974 if (!xa_is_sibling(xa_entry(xas->xa, node, offset)))
977 xas->xa_index += (offset - xas->xa_offset) << node->shift;
978 if (xas->xa_index == 0)
979 xas->xa_node = XAS_BOUNDS;
984 EXPORT_SYMBOL_GPL(xas_pause);
987 * __xas_prev() - Find the previous entry in the XArray.
988 * @xas: XArray operation state.
990 * Helper function for xas_prev() which handles all the complex cases
993 void *__xas_prev(struct xa_state *xas)
997 if (!xas_frozen(xas->xa_node))
1000 return set_bounds(xas);
1001 if (xas_not_node(xas->xa_node))
1002 return xas_load(xas);
1004 if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node))
1007 while (xas->xa_offset == 255) {
1008 xas->xa_offset = xas->xa_node->offset - 1;
1009 xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1011 return set_bounds(xas);
1015 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1016 if (!xa_is_node(entry))
1019 xas->xa_node = xa_to_node(entry);
1020 xas_set_offset(xas);
1023 EXPORT_SYMBOL_GPL(__xas_prev);
1026 * __xas_next() - Find the next entry in the XArray.
1027 * @xas: XArray operation state.
1029 * Helper function for xas_next() which handles all the complex cases
1032 void *__xas_next(struct xa_state *xas)
1036 if (!xas_frozen(xas->xa_node))
1039 return set_bounds(xas);
1040 if (xas_not_node(xas->xa_node))
1041 return xas_load(xas);
1043 if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node))
1046 while (xas->xa_offset == XA_CHUNK_SIZE) {
1047 xas->xa_offset = xas->xa_node->offset + 1;
1048 xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1050 return set_bounds(xas);
1054 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1055 if (!xa_is_node(entry))
1058 xas->xa_node = xa_to_node(entry);
1059 xas_set_offset(xas);
1062 EXPORT_SYMBOL_GPL(__xas_next);
1065 * xas_find() - Find the next present entry in the XArray.
1066 * @xas: XArray operation state.
1067 * @max: Highest index to return.
1069 * If the @xas has not yet been walked to an entry, return the entry
1070 * which has an index >= xas.xa_index. If it has been walked, the entry
1071 * currently being pointed at has been processed, and so we move to the
1074 * If no entry is found and the array is smaller than @max, the iterator
1075 * is set to the smallest index not yet in the array. This allows @xas
1076 * to be immediately passed to xas_store().
1078 * Return: The entry, if found, otherwise %NULL.
1080 void *xas_find(struct xa_state *xas, unsigned long max)
1084 if (xas_error(xas) || xas->xa_node == XAS_BOUNDS)
1087 if (!xas->xa_node) {
1089 return set_bounds(xas);
1090 } else if (xas->xa_node == XAS_RESTART) {
1091 entry = xas_load(xas);
1092 if (entry || xas_not_node(xas->xa_node))
1094 } else if (!xas->xa_node->shift &&
1095 xas->xa_offset != (xas->xa_index & XA_CHUNK_MASK)) {
1096 xas->xa_offset = ((xas->xa_index - 1) & XA_CHUNK_MASK) + 1;
1101 while (xas->xa_node && (xas->xa_index <= max)) {
1102 if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) {
1103 xas->xa_offset = xas->xa_node->offset + 1;
1104 xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1108 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1109 if (xa_is_node(entry)) {
1110 xas->xa_node = xa_to_node(entry);
1114 if (entry && !xa_is_sibling(entry))
1121 xas->xa_node = XAS_BOUNDS;
1124 EXPORT_SYMBOL_GPL(xas_find);
1127 * xas_find_marked() - Find the next marked entry in the XArray.
1128 * @xas: XArray operation state.
1129 * @max: Highest index to return.
1130 * @mark: Mark number to search for.
1132 * If the @xas has not yet been walked to an entry, return the marked entry
1133 * which has an index >= xas.xa_index. If it has been walked, the entry
1134 * currently being pointed at has been processed, and so we return the
1135 * first marked entry with an index > xas.xa_index.
1137 * If no marked entry is found and the array is smaller than @max, @xas is
1138 * set to the bounds state and xas->xa_index is set to the smallest index
1139 * not yet in the array. This allows @xas to be immediately passed to
1142 * If no entry is found before @max is reached, @xas is set to the restart
1145 * Return: The entry, if found, otherwise %NULL.
1147 void *xas_find_marked(struct xa_state *xas, unsigned long max, xa_mark_t mark)
1149 bool advance = true;
1150 unsigned int offset;
1156 if (!xas->xa_node) {
1159 } else if (xas_top(xas->xa_node)) {
1161 entry = xa_head(xas->xa);
1162 xas->xa_node = NULL;
1163 if (xas->xa_index > max_index(entry))
1165 if (!xa_is_node(entry)) {
1166 if (xa_marked(xas->xa, mark))
1171 xas->xa_node = xa_to_node(entry);
1172 xas->xa_offset = xas->xa_index >> xas->xa_node->shift;
1175 while (xas->xa_index <= max) {
1176 if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) {
1177 xas->xa_offset = xas->xa_node->offset + 1;
1178 xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1186 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1187 if (xa_is_sibling(entry)) {
1188 xas->xa_offset = xa_to_sibling(entry);
1189 xas_move_index(xas, xas->xa_offset);
1193 offset = xas_find_chunk(xas, advance, mark);
1194 if (offset > xas->xa_offset) {
1196 xas_move_index(xas, offset);
1198 if ((xas->xa_index - 1) >= max)
1200 xas->xa_offset = offset;
1201 if (offset == XA_CHUNK_SIZE)
1205 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1206 if (!xa_is_node(entry))
1208 xas->xa_node = xa_to_node(entry);
1209 xas_set_offset(xas);
1213 if (xas->xa_index > max)
1215 return set_bounds(xas);
1217 xas->xa_node = XAS_RESTART;
1220 EXPORT_SYMBOL_GPL(xas_find_marked);
1223 * xas_find_conflict() - Find the next present entry in a range.
1224 * @xas: XArray operation state.
1226 * The @xas describes both a range and a position within that range.
1228 * Context: Any context. Expects xa_lock to be held.
1229 * Return: The next entry in the range covered by @xas or %NULL.
1231 void *xas_find_conflict(struct xa_state *xas)
1241 if (xas_top(xas->xa_node)) {
1242 curr = xas_start(xas);
1245 while (xa_is_node(curr)) {
1246 struct xa_node *node = xa_to_node(curr);
1247 curr = xas_descend(xas, node);
1253 if (xas->xa_node->shift > xas->xa_shift)
1257 if (xas->xa_node->shift == xas->xa_shift) {
1258 if ((xas->xa_offset & xas->xa_sibs) == xas->xa_sibs)
1260 } else if (xas->xa_offset == XA_CHUNK_MASK) {
1261 xas->xa_offset = xas->xa_node->offset;
1262 xas->xa_node = xa_parent_locked(xas->xa, xas->xa_node);
1267 curr = xa_entry_locked(xas->xa, xas->xa_node, ++xas->xa_offset);
1268 if (xa_is_sibling(curr))
1270 while (xa_is_node(curr)) {
1271 xas->xa_node = xa_to_node(curr);
1273 curr = xa_entry_locked(xas->xa, xas->xa_node, 0);
1278 xas->xa_offset -= xas->xa_sibs;
1281 EXPORT_SYMBOL_GPL(xas_find_conflict);
1284 * xa_load() - Load an entry from an XArray.
1286 * @index: index into array.
1288 * Context: Any context. Takes and releases the RCU lock.
1289 * Return: The entry at @index in @xa.
1291 void *xa_load(struct xarray *xa, unsigned long index)
1293 XA_STATE(xas, xa, index);
1298 entry = xas_load(&xas);
1299 if (xa_is_zero(entry))
1301 } while (xas_retry(&xas, entry));
1306 EXPORT_SYMBOL(xa_load);
1308 static void *xas_result(struct xa_state *xas, void *curr)
1310 if (xa_is_zero(curr))
1313 curr = xas->xa_node;
1318 * __xa_erase() - Erase this entry from the XArray while locked.
1320 * @index: Index into array.
1322 * After this function returns, loading from @index will return %NULL.
1323 * If the index is part of a multi-index entry, all indices will be erased
1324 * and none of the entries will be part of a multi-index entry.
1326 * Context: Any context. Expects xa_lock to be held on entry.
1327 * Return: The entry which used to be at this index.
1329 void *__xa_erase(struct xarray *xa, unsigned long index)
1331 XA_STATE(xas, xa, index);
1332 return xas_result(&xas, xas_store(&xas, NULL));
1334 EXPORT_SYMBOL(__xa_erase);
1337 * xa_erase() - Erase this entry from the XArray.
1339 * @index: Index of entry.
1341 * After this function returns, loading from @index will return %NULL.
1342 * If the index is part of a multi-index entry, all indices will be erased
1343 * and none of the entries will be part of a multi-index entry.
1345 * Context: Any context. Takes and releases the xa_lock.
1346 * Return: The entry which used to be at this index.
1348 void *xa_erase(struct xarray *xa, unsigned long index)
1353 entry = __xa_erase(xa, index);
1358 EXPORT_SYMBOL(xa_erase);
1361 * __xa_store() - Store this entry in the XArray.
1363 * @index: Index into array.
1364 * @entry: New entry.
1365 * @gfp: Memory allocation flags.
1367 * You must already be holding the xa_lock when calling this function.
1368 * It will drop the lock if needed to allocate memory, and then reacquire
1371 * Context: Any context. Expects xa_lock to be held on entry. May
1372 * release and reacquire xa_lock if @gfp flags permit.
1373 * Return: The old entry at this index or xa_err() if an error happened.
1375 void *__xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
1377 XA_STATE(xas, xa, index);
1380 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1381 return XA_ERROR(-EINVAL);
1382 if (xa_track_free(xa) && !entry)
1383 entry = XA_ZERO_ENTRY;
1386 curr = xas_store(&xas, entry);
1387 if (xa_track_free(xa))
1388 xas_clear_mark(&xas, XA_FREE_MARK);
1389 } while (__xas_nomem(&xas, gfp));
1391 return xas_result(&xas, curr);
1393 EXPORT_SYMBOL(__xa_store);
1396 * xa_store() - Store this entry in the XArray.
1398 * @index: Index into array.
1399 * @entry: New entry.
1400 * @gfp: Memory allocation flags.
1402 * After this function returns, loads from this index will return @entry.
1403 * Storing into an existing multislot entry updates the entry of every index.
1404 * The marks associated with @index are unaffected unless @entry is %NULL.
1406 * Context: Any context. Takes and releases the xa_lock.
1407 * May sleep if the @gfp flags permit.
1408 * Return: The old entry at this index on success, xa_err(-EINVAL) if @entry
1409 * cannot be stored in an XArray, or xa_err(-ENOMEM) if memory allocation
1412 void *xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
1417 curr = __xa_store(xa, index, entry, gfp);
1422 EXPORT_SYMBOL(xa_store);
1425 * __xa_cmpxchg() - Store this entry in the XArray.
1427 * @index: Index into array.
1428 * @old: Old value to test against.
1429 * @entry: New entry.
1430 * @gfp: Memory allocation flags.
1432 * You must already be holding the xa_lock when calling this function.
1433 * It will drop the lock if needed to allocate memory, and then reacquire
1436 * Context: Any context. Expects xa_lock to be held on entry. May
1437 * release and reacquire xa_lock if @gfp flags permit.
1438 * Return: The old entry at this index or xa_err() if an error happened.
1440 void *__xa_cmpxchg(struct xarray *xa, unsigned long index,
1441 void *old, void *entry, gfp_t gfp)
1443 XA_STATE(xas, xa, index);
1446 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1447 return XA_ERROR(-EINVAL);
1450 curr = xas_load(&xas);
1452 xas_store(&xas, entry);
1453 if (xa_track_free(xa) && entry && !curr)
1454 xas_clear_mark(&xas, XA_FREE_MARK);
1456 } while (__xas_nomem(&xas, gfp));
1458 return xas_result(&xas, curr);
1460 EXPORT_SYMBOL(__xa_cmpxchg);
1463 * __xa_insert() - Store this entry in the XArray if no entry is present.
1465 * @index: Index into array.
1466 * @entry: New entry.
1467 * @gfp: Memory allocation flags.
1469 * Inserting a NULL entry will store a reserved entry (like xa_reserve())
1470 * if no entry is present. Inserting will fail if a reserved entry is
1471 * present, even though loading from this index will return NULL.
1473 * Context: Any context. Expects xa_lock to be held on entry. May
1474 * release and reacquire xa_lock if @gfp flags permit.
1475 * Return: 0 if the store succeeded. -EBUSY if another entry was present.
1476 * -ENOMEM if memory could not be allocated.
1478 int __xa_insert(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
1480 XA_STATE(xas, xa, index);
1483 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1486 entry = XA_ZERO_ENTRY;
1489 curr = xas_load(&xas);
1491 xas_store(&xas, entry);
1492 if (xa_track_free(xa))
1493 xas_clear_mark(&xas, XA_FREE_MARK);
1495 xas_set_err(&xas, -EBUSY);
1497 } while (__xas_nomem(&xas, gfp));
1499 return xas_error(&xas);
1501 EXPORT_SYMBOL(__xa_insert);
1503 #ifdef CONFIG_XARRAY_MULTI
1504 static void xas_set_range(struct xa_state *xas, unsigned long first,
1507 unsigned int shift = 0;
1508 unsigned long sibs = last - first;
1509 unsigned int offset = XA_CHUNK_MASK;
1511 xas_set(xas, first);
1513 while ((first & XA_CHUNK_MASK) == 0) {
1514 if (sibs < XA_CHUNK_MASK)
1516 if ((sibs == XA_CHUNK_MASK) && (offset < XA_CHUNK_MASK))
1518 shift += XA_CHUNK_SHIFT;
1519 if (offset == XA_CHUNK_MASK)
1520 offset = sibs & XA_CHUNK_MASK;
1521 sibs >>= XA_CHUNK_SHIFT;
1522 first >>= XA_CHUNK_SHIFT;
1525 offset = first & XA_CHUNK_MASK;
1526 if (offset + sibs > XA_CHUNK_MASK)
1527 sibs = XA_CHUNK_MASK - offset;
1528 if ((((first + sibs + 1) << shift) - 1) > last)
1531 xas->xa_shift = shift;
1532 xas->xa_sibs = sibs;
1536 * xa_store_range() - Store this entry at a range of indices in the XArray.
1538 * @first: First index to affect.
1539 * @last: Last index to affect.
1540 * @entry: New entry.
1541 * @gfp: Memory allocation flags.
1543 * After this function returns, loads from any index between @first and @last,
1544 * inclusive will return @entry.
1545 * Storing into an existing multislot entry updates the entry of every index.
1546 * The marks associated with @index are unaffected unless @entry is %NULL.
1548 * Context: Process context. Takes and releases the xa_lock. May sleep
1549 * if the @gfp flags permit.
1550 * Return: %NULL on success, xa_err(-EINVAL) if @entry cannot be stored in
1551 * an XArray, or xa_err(-ENOMEM) if memory allocation failed.
1553 void *xa_store_range(struct xarray *xa, unsigned long first,
1554 unsigned long last, void *entry, gfp_t gfp)
1556 XA_STATE(xas, xa, 0);
1558 if (WARN_ON_ONCE(xa_is_internal(entry)))
1559 return XA_ERROR(-EINVAL);
1561 return XA_ERROR(-EINVAL);
1566 unsigned int order = BITS_PER_LONG;
1568 order = __ffs(last + 1);
1569 xas_set_order(&xas, last, order);
1570 xas_create(&xas, true);
1571 if (xas_error(&xas))
1575 xas_set_range(&xas, first, last);
1576 xas_store(&xas, entry);
1577 if (xas_error(&xas))
1579 first += xas_size(&xas);
1580 } while (first <= last);
1583 } while (xas_nomem(&xas, gfp));
1585 return xas_result(&xas, NULL);
1587 EXPORT_SYMBOL(xa_store_range);
1588 #endif /* CONFIG_XARRAY_MULTI */
1591 * __xa_alloc() - Find somewhere to store this entry in the XArray.
1593 * @id: Pointer to ID.
1594 * @limit: Range for allocated ID.
1595 * @entry: New entry.
1596 * @gfp: Memory allocation flags.
1598 * Finds an empty entry in @xa between @limit.min and @limit.max,
1599 * stores the index into the @id pointer, then stores the entry at
1600 * that index. A concurrent lookup will not see an uninitialised @id.
1602 * Context: Any context. Expects xa_lock to be held on entry. May
1603 * release and reacquire xa_lock if @gfp flags permit.
1604 * Return: 0 on success, -ENOMEM if memory could not be allocated or
1605 * -EBUSY if there are no free entries in @limit.
1607 int __xa_alloc(struct xarray *xa, u32 *id, void *entry,
1608 struct xa_limit limit, gfp_t gfp)
1610 XA_STATE(xas, xa, 0);
1612 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1614 if (WARN_ON_ONCE(!xa_track_free(xa)))
1618 entry = XA_ZERO_ENTRY;
1621 xas.xa_index = limit.min;
1622 xas_find_marked(&xas, limit.max, XA_FREE_MARK);
1623 if (xas.xa_node == XAS_RESTART)
1624 xas_set_err(&xas, -EBUSY);
1627 xas_store(&xas, entry);
1628 xas_clear_mark(&xas, XA_FREE_MARK);
1629 } while (__xas_nomem(&xas, gfp));
1631 return xas_error(&xas);
1633 EXPORT_SYMBOL(__xa_alloc);
1636 * __xa_alloc_cyclic() - Find somewhere to store this entry in the XArray.
1638 * @id: Pointer to ID.
1639 * @entry: New entry.
1640 * @limit: Range of allocated ID.
1641 * @next: Pointer to next ID to allocate.
1642 * @gfp: Memory allocation flags.
1644 * Finds an empty entry in @xa between @limit.min and @limit.max,
1645 * stores the index into the @id pointer, then stores the entry at
1646 * that index. A concurrent lookup will not see an uninitialised @id.
1647 * The search for an empty entry will start at @next and will wrap
1648 * around if necessary.
1650 * Context: Any context. Expects xa_lock to be held on entry. May
1651 * release and reacquire xa_lock if @gfp flags permit.
1652 * Return: 0 if the allocation succeeded without wrapping. 1 if the
1653 * allocation succeeded after wrapping, -ENOMEM if memory could not be
1654 * allocated or -EBUSY if there are no free entries in @limit.
1656 int __xa_alloc_cyclic(struct xarray *xa, u32 *id, void *entry,
1657 struct xa_limit limit, u32 *next, gfp_t gfp)
1659 u32 min = limit.min;
1662 limit.min = max(min, *next);
1663 ret = __xa_alloc(xa, id, entry, limit, gfp);
1664 if ((xa->xa_flags & XA_FLAGS_ALLOC_WRAPPED) && ret == 0) {
1665 xa->xa_flags &= ~XA_FLAGS_ALLOC_WRAPPED;
1669 if (ret < 0 && limit.min > min) {
1671 ret = __xa_alloc(xa, id, entry, limit, gfp);
1679 xa->xa_flags |= XA_FLAGS_ALLOC_WRAPPED;
1683 EXPORT_SYMBOL(__xa_alloc_cyclic);
1686 * __xa_set_mark() - Set this mark on this entry while locked.
1688 * @index: Index of entry.
1689 * @mark: Mark number.
1691 * Attempting to set a mark on a %NULL entry does not succeed.
1693 * Context: Any context. Expects xa_lock to be held on entry.
1695 void __xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1697 XA_STATE(xas, xa, index);
1698 void *entry = xas_load(&xas);
1701 xas_set_mark(&xas, mark);
1703 EXPORT_SYMBOL(__xa_set_mark);
1706 * __xa_clear_mark() - Clear this mark on this entry while locked.
1708 * @index: Index of entry.
1709 * @mark: Mark number.
1711 * Context: Any context. Expects xa_lock to be held on entry.
1713 void __xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1715 XA_STATE(xas, xa, index);
1716 void *entry = xas_load(&xas);
1719 xas_clear_mark(&xas, mark);
1721 EXPORT_SYMBOL(__xa_clear_mark);
1724 * xa_get_mark() - Inquire whether this mark is set on this entry.
1726 * @index: Index of entry.
1727 * @mark: Mark number.
1729 * This function uses the RCU read lock, so the result may be out of date
1730 * by the time it returns. If you need the result to be stable, use a lock.
1732 * Context: Any context. Takes and releases the RCU lock.
1733 * Return: True if the entry at @index has this mark set, false if it doesn't.
1735 bool xa_get_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1737 XA_STATE(xas, xa, index);
1741 entry = xas_start(&xas);
1742 while (xas_get_mark(&xas, mark)) {
1743 if (!xa_is_node(entry))
1745 entry = xas_descend(&xas, xa_to_node(entry));
1753 EXPORT_SYMBOL(xa_get_mark);
1756 * xa_set_mark() - Set this mark on this entry.
1758 * @index: Index of entry.
1759 * @mark: Mark number.
1761 * Attempting to set a mark on a %NULL entry does not succeed.
1763 * Context: Process context. Takes and releases the xa_lock.
1765 void xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1768 __xa_set_mark(xa, index, mark);
1771 EXPORT_SYMBOL(xa_set_mark);
1774 * xa_clear_mark() - Clear this mark on this entry.
1776 * @index: Index of entry.
1777 * @mark: Mark number.
1779 * Clearing a mark always succeeds.
1781 * Context: Process context. Takes and releases the xa_lock.
1783 void xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1786 __xa_clear_mark(xa, index, mark);
1789 EXPORT_SYMBOL(xa_clear_mark);
1792 * xa_find() - Search the XArray for an entry.
1794 * @indexp: Pointer to an index.
1795 * @max: Maximum index to search to.
1796 * @filter: Selection criterion.
1798 * Finds the entry in @xa which matches the @filter, and has the lowest
1799 * index that is at least @indexp and no more than @max.
1800 * If an entry is found, @indexp is updated to be the index of the entry.
1801 * This function is protected by the RCU read lock, so it may not find
1802 * entries which are being simultaneously added. It will not return an
1803 * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
1805 * Context: Any context. Takes and releases the RCU lock.
1806 * Return: The entry, if found, otherwise %NULL.
1808 void *xa_find(struct xarray *xa, unsigned long *indexp,
1809 unsigned long max, xa_mark_t filter)
1811 XA_STATE(xas, xa, *indexp);
1816 if ((__force unsigned int)filter < XA_MAX_MARKS)
1817 entry = xas_find_marked(&xas, max, filter);
1819 entry = xas_find(&xas, max);
1820 } while (xas_retry(&xas, entry));
1824 *indexp = xas.xa_index;
1827 EXPORT_SYMBOL(xa_find);
1829 static bool xas_sibling(struct xa_state *xas)
1831 struct xa_node *node = xas->xa_node;
1836 mask = (XA_CHUNK_SIZE << node->shift) - 1;
1837 return (xas->xa_index & mask) > (xas->xa_offset << node->shift);
1841 * xa_find_after() - Search the XArray for a present entry.
1843 * @indexp: Pointer to an index.
1844 * @max: Maximum index to search to.
1845 * @filter: Selection criterion.
1847 * Finds the entry in @xa which matches the @filter and has the lowest
1848 * index that is above @indexp and no more than @max.
1849 * If an entry is found, @indexp is updated to be the index of the entry.
1850 * This function is protected by the RCU read lock, so it may miss entries
1851 * which are being simultaneously added. It will not return an
1852 * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
1854 * Context: Any context. Takes and releases the RCU lock.
1855 * Return: The pointer, if found, otherwise %NULL.
1857 void *xa_find_after(struct xarray *xa, unsigned long *indexp,
1858 unsigned long max, xa_mark_t filter)
1860 XA_STATE(xas, xa, *indexp + 1);
1863 if (xas.xa_index == 0)
1868 if ((__force unsigned int)filter < XA_MAX_MARKS)
1869 entry = xas_find_marked(&xas, max, filter);
1871 entry = xas_find(&xas, max);
1872 if (xas.xa_node == XAS_BOUNDS)
1874 if (xas_sibling(&xas))
1876 if (!xas_retry(&xas, entry))
1882 *indexp = xas.xa_index;
1885 EXPORT_SYMBOL(xa_find_after);
1887 static unsigned int xas_extract_present(struct xa_state *xas, void **dst,
1888 unsigned long max, unsigned int n)
1894 xas_for_each(xas, entry, max) {
1895 if (xas_retry(xas, entry))
1906 static unsigned int xas_extract_marked(struct xa_state *xas, void **dst,
1907 unsigned long max, unsigned int n, xa_mark_t mark)
1913 xas_for_each_marked(xas, entry, max, mark) {
1914 if (xas_retry(xas, entry))
1926 * xa_extract() - Copy selected entries from the XArray into a normal array.
1927 * @xa: The source XArray to copy from.
1928 * @dst: The buffer to copy entries into.
1929 * @start: The first index in the XArray eligible to be selected.
1930 * @max: The last index in the XArray eligible to be selected.
1931 * @n: The maximum number of entries to copy.
1932 * @filter: Selection criterion.
1934 * Copies up to @n entries that match @filter from the XArray. The
1935 * copied entries will have indices between @start and @max, inclusive.
1937 * The @filter may be an XArray mark value, in which case entries which are
1938 * marked with that mark will be copied. It may also be %XA_PRESENT, in
1939 * which case all entries which are not %NULL will be copied.
1941 * The entries returned may not represent a snapshot of the XArray at a
1942 * moment in time. For example, if another thread stores to index 5, then
1943 * index 10, calling xa_extract() may return the old contents of index 5
1944 * and the new contents of index 10. Indices not modified while this
1945 * function is running will not be skipped.
1947 * If you need stronger guarantees, holding the xa_lock across calls to this
1948 * function will prevent concurrent modification.
1950 * Context: Any context. Takes and releases the RCU lock.
1951 * Return: The number of entries copied.
1953 unsigned int xa_extract(struct xarray *xa, void **dst, unsigned long start,
1954 unsigned long max, unsigned int n, xa_mark_t filter)
1956 XA_STATE(xas, xa, start);
1961 if ((__force unsigned int)filter < XA_MAX_MARKS)
1962 return xas_extract_marked(&xas, dst, max, n, filter);
1963 return xas_extract_present(&xas, dst, max, n);
1965 EXPORT_SYMBOL(xa_extract);
1968 * xa_destroy() - Free all internal data structures.
1971 * After calling this function, the XArray is empty and has freed all memory
1972 * allocated for its internal data structures. You are responsible for
1973 * freeing the objects referenced by the XArray.
1975 * Context: Any context. Takes and releases the xa_lock, interrupt-safe.
1977 void xa_destroy(struct xarray *xa)
1979 XA_STATE(xas, xa, 0);
1980 unsigned long flags;
1984 xas_lock_irqsave(&xas, flags);
1985 entry = xa_head_locked(xa);
1986 RCU_INIT_POINTER(xa->xa_head, NULL);
1987 xas_init_marks(&xas);
1988 if (xa_zero_busy(xa))
1989 xa_mark_clear(xa, XA_FREE_MARK);
1990 /* lockdep checks we're still holding the lock in xas_free_nodes() */
1991 if (xa_is_node(entry))
1992 xas_free_nodes(&xas, xa_to_node(entry));
1993 xas_unlock_irqrestore(&xas, flags);
1995 EXPORT_SYMBOL(xa_destroy);
1998 void xa_dump_node(const struct xa_node *node)
2004 if ((unsigned long)node & 3) {
2005 pr_cont("node %px\n", node);
2009 pr_cont("node %px %s %d parent %px shift %d count %d values %d "
2010 "array %px list %px %px marks",
2011 node, node->parent ? "offset" : "max", node->offset,
2012 node->parent, node->shift, node->count, node->nr_values,
2013 node->array, node->private_list.prev, node->private_list.next);
2014 for (i = 0; i < XA_MAX_MARKS; i++)
2015 for (j = 0; j < XA_MARK_LONGS; j++)
2016 pr_cont(" %lx", node->marks[i][j]);
2020 void xa_dump_index(unsigned long index, unsigned int shift)
2023 pr_info("%lu: ", index);
2024 else if (shift >= BITS_PER_LONG)
2025 pr_info("0-%lu: ", ~0UL);
2027 pr_info("%lu-%lu: ", index, index | ((1UL << shift) - 1));
2030 void xa_dump_entry(const void *entry, unsigned long index, unsigned long shift)
2035 xa_dump_index(index, shift);
2037 if (xa_is_node(entry)) {
2039 pr_cont("%px\n", entry);
2042 struct xa_node *node = xa_to_node(entry);
2044 for (i = 0; i < XA_CHUNK_SIZE; i++)
2045 xa_dump_entry(node->slots[i],
2046 index + (i << node->shift), node->shift);
2048 } else if (xa_is_value(entry))
2049 pr_cont("value %ld (0x%lx) [%px]\n", xa_to_value(entry),
2050 xa_to_value(entry), entry);
2051 else if (!xa_is_internal(entry))
2052 pr_cont("%px\n", entry);
2053 else if (xa_is_retry(entry))
2054 pr_cont("retry (%ld)\n", xa_to_internal(entry));
2055 else if (xa_is_sibling(entry))
2056 pr_cont("sibling (slot %ld)\n", xa_to_sibling(entry));
2057 else if (xa_is_zero(entry))
2058 pr_cont("zero (%ld)\n", xa_to_internal(entry));
2060 pr_cont("UNKNOWN ENTRY (%px)\n", entry);
2063 void xa_dump(const struct xarray *xa)
2065 void *entry = xa->xa_head;
2066 unsigned int shift = 0;
2068 pr_info("xarray: %px head %px flags %x marks %d %d %d\n", xa, entry,
2069 xa->xa_flags, xa_marked(xa, XA_MARK_0),
2070 xa_marked(xa, XA_MARK_1), xa_marked(xa, XA_MARK_2));
2071 if (xa_is_node(entry))
2072 shift = xa_to_node(entry)->shift + XA_CHUNK_SHIFT;
2073 xa_dump_entry(entry, 0, shift);