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 xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp);
304 XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list));
305 xas->xa_node = XAS_RESTART;
308 EXPORT_SYMBOL_GPL(xas_nomem);
311 * __xas_nomem() - Drop locks and allocate memory if needed.
312 * @xas: XArray operation state.
313 * @gfp: Memory allocation flags.
315 * Internal variant of xas_nomem().
317 * Return: true if memory was needed, and was successfully allocated.
319 static bool __xas_nomem(struct xa_state *xas, gfp_t gfp)
320 __must_hold(xas->xa->xa_lock)
322 unsigned int lock_type = xa_lock_type(xas->xa);
324 if (xas->xa_node != XA_ERROR(-ENOMEM)) {
328 if (gfpflags_allow_blocking(gfp)) {
329 xas_unlock_type(xas, lock_type);
330 xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp);
331 xas_lock_type(xas, lock_type);
333 xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp);
337 XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list));
338 xas->xa_node = XAS_RESTART;
342 static void xas_update(struct xa_state *xas, struct xa_node *node)
345 xas->xa_update(node);
347 XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
350 static void *xas_alloc(struct xa_state *xas, unsigned int shift)
352 struct xa_node *parent = xas->xa_node;
353 struct xa_node *node = xas->xa_alloc;
355 if (xas_invalid(xas))
359 xas->xa_alloc = NULL;
361 node = kmem_cache_alloc(radix_tree_node_cachep,
362 GFP_NOWAIT | __GFP_NOWARN);
364 xas_set_err(xas, -ENOMEM);
370 node->offset = xas->xa_offset;
372 XA_NODE_BUG_ON(node, parent->count > XA_CHUNK_SIZE);
373 xas_update(xas, parent);
375 XA_NODE_BUG_ON(node, shift > BITS_PER_LONG);
376 XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
380 RCU_INIT_POINTER(node->parent, xas->xa_node);
381 node->array = xas->xa;
386 #ifdef CONFIG_XARRAY_MULTI
387 /* Returns the number of indices covered by a given xa_state */
388 static unsigned long xas_size(const struct xa_state *xas)
390 return (xas->xa_sibs + 1UL) << xas->xa_shift;
395 * Use this to calculate the maximum index that will need to be created
396 * in order to add the entry described by @xas. Because we cannot store a
397 * multiple-index entry at index 0, the calculation is a little more complex
398 * than you might expect.
400 static unsigned long xas_max(struct xa_state *xas)
402 unsigned long max = xas->xa_index;
404 #ifdef CONFIG_XARRAY_MULTI
405 if (xas->xa_shift || xas->xa_sibs) {
406 unsigned long mask = xas_size(xas) - 1;
416 /* The maximum index that can be contained in the array without expanding it */
417 static unsigned long max_index(void *entry)
419 if (!xa_is_node(entry))
421 return (XA_CHUNK_SIZE << xa_to_node(entry)->shift) - 1;
424 static void xas_shrink(struct xa_state *xas)
426 struct xarray *xa = xas->xa;
427 struct xa_node *node = xas->xa_node;
432 XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
433 if (node->count != 1)
435 entry = xa_entry_locked(xa, node, 0);
438 if (!xa_is_node(entry) && node->shift)
440 if (xa_is_zero(entry) && xa_zero_busy(xa))
442 xas->xa_node = XAS_BOUNDS;
444 RCU_INIT_POINTER(xa->xa_head, entry);
445 if (xa_track_free(xa) && !node_get_mark(node, 0, XA_FREE_MARK))
446 xa_mark_clear(xa, XA_FREE_MARK);
450 if (!xa_is_node(entry))
451 RCU_INIT_POINTER(node->slots[0], XA_RETRY_ENTRY);
452 xas_update(xas, node);
454 if (!xa_is_node(entry))
456 node = xa_to_node(entry);
462 * xas_delete_node() - Attempt to delete an xa_node
463 * @xas: Array operation state.
465 * Attempts to delete the @xas->xa_node. This will fail if xa->node has
466 * a non-zero reference count.
468 static void xas_delete_node(struct xa_state *xas)
470 struct xa_node *node = xas->xa_node;
473 struct xa_node *parent;
475 XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
479 parent = xa_parent_locked(xas->xa, node);
480 xas->xa_node = parent;
481 xas->xa_offset = node->offset;
485 xas->xa->xa_head = NULL;
486 xas->xa_node = XAS_BOUNDS;
490 parent->slots[xas->xa_offset] = NULL;
492 XA_NODE_BUG_ON(parent, parent->count > XA_CHUNK_SIZE);
494 xas_update(xas, node);
502 * xas_free_nodes() - Free this node and all nodes that it references
503 * @xas: Array operation state.
506 * This node has been removed from the tree. We must now free it and all
507 * of its subnodes. There may be RCU walkers with references into the tree,
508 * so we must replace all entries with retry markers.
510 static void xas_free_nodes(struct xa_state *xas, struct xa_node *top)
512 unsigned int offset = 0;
513 struct xa_node *node = top;
516 void *entry = xa_entry_locked(xas->xa, node, offset);
518 if (node->shift && xa_is_node(entry)) {
519 node = xa_to_node(entry);
524 RCU_INIT_POINTER(node->slots[offset], XA_RETRY_ENTRY);
526 while (offset == XA_CHUNK_SIZE) {
527 struct xa_node *parent;
529 parent = xa_parent_locked(xas->xa, node);
530 offset = node->offset + 1;
533 xas_update(xas, node);
543 * xas_expand adds nodes to the head of the tree until it has reached
544 * sufficient height to be able to contain @xas->xa_index
546 static int xas_expand(struct xa_state *xas, void *head)
548 struct xarray *xa = xas->xa;
549 struct xa_node *node = NULL;
550 unsigned int shift = 0;
551 unsigned long max = xas_max(xas);
556 while ((max >> shift) >= XA_CHUNK_SIZE)
557 shift += XA_CHUNK_SHIFT;
558 return shift + XA_CHUNK_SHIFT;
559 } else if (xa_is_node(head)) {
560 node = xa_to_node(head);
561 shift = node->shift + XA_CHUNK_SHIFT;
565 while (max > max_index(head)) {
568 XA_NODE_BUG_ON(node, shift > BITS_PER_LONG);
569 node = xas_alloc(xas, shift);
574 if (xa_is_value(head))
576 RCU_INIT_POINTER(node->slots[0], head);
578 /* Propagate the aggregated mark info to the new child */
580 if (xa_track_free(xa) && mark == XA_FREE_MARK) {
581 node_mark_all(node, XA_FREE_MARK);
582 if (!xa_marked(xa, XA_FREE_MARK)) {
583 node_clear_mark(node, 0, XA_FREE_MARK);
584 xa_mark_set(xa, XA_FREE_MARK);
586 } else if (xa_marked(xa, mark)) {
587 node_set_mark(node, 0, mark);
589 if (mark == XA_MARK_MAX)
595 * Now that the new node is fully initialised, we can add
598 if (xa_is_node(head)) {
599 xa_to_node(head)->offset = 0;
600 rcu_assign_pointer(xa_to_node(head)->parent, node);
602 head = xa_mk_node(node);
603 rcu_assign_pointer(xa->xa_head, head);
604 xas_update(xas, node);
606 shift += XA_CHUNK_SHIFT;
614 * xas_create() - Create a slot to store an entry in.
615 * @xas: XArray operation state.
616 * @allow_root: %true if we can store the entry in the root directly
618 * Most users will not need to call this function directly, as it is called
619 * by xas_store(). It is useful for doing conditional store operations
620 * (see the xa_cmpxchg() implementation for an example).
622 * Return: If the slot already existed, returns the contents of this slot.
623 * If the slot was newly created, returns %NULL. If it failed to create the
624 * slot, returns %NULL and indicates the error in @xas.
626 static void *xas_create(struct xa_state *xas, bool allow_root)
628 struct xarray *xa = xas->xa;
631 struct xa_node *node = xas->xa_node;
633 unsigned int order = xas->xa_shift;
636 entry = xa_head_locked(xa);
638 if (!entry && xa_zero_busy(xa))
639 entry = XA_ZERO_ENTRY;
640 shift = xas_expand(xas, entry);
643 if (!shift && !allow_root)
644 shift = XA_CHUNK_SHIFT;
645 entry = xa_head_locked(xa);
647 } else if (xas_error(xas)) {
650 unsigned int offset = xas->xa_offset;
653 entry = xa_entry_locked(xa, node, offset);
654 slot = &node->slots[offset];
657 entry = xa_head_locked(xa);
661 while (shift > order) {
662 shift -= XA_CHUNK_SHIFT;
664 node = xas_alloc(xas, shift);
667 if (xa_track_free(xa))
668 node_mark_all(node, XA_FREE_MARK);
669 rcu_assign_pointer(*slot, xa_mk_node(node));
670 } else if (xa_is_node(entry)) {
671 node = xa_to_node(entry);
675 entry = xas_descend(xas, node);
676 slot = &node->slots[xas->xa_offset];
683 * xas_create_range() - Ensure that stores to this range will succeed
684 * @xas: XArray operation state.
686 * Creates all of the slots in the range covered by @xas. Sets @xas to
687 * create single-index entries and positions it at the beginning of the
688 * range. This is for the benefit of users which have not yet been
689 * converted to use multi-index entries.
691 void xas_create_range(struct xa_state *xas)
693 unsigned long index = xas->xa_index;
694 unsigned char shift = xas->xa_shift;
695 unsigned char sibs = xas->xa_sibs;
697 xas->xa_index |= ((sibs + 1) << shift) - 1;
698 if (xas_is_node(xas) && xas->xa_node->shift == xas->xa_shift)
699 xas->xa_offset |= sibs;
704 xas_create(xas, true);
707 if (xas->xa_index <= (index | XA_CHUNK_MASK))
709 xas->xa_index -= XA_CHUNK_SIZE;
712 struct xa_node *node = xas->xa_node;
713 xas->xa_node = xa_parent_locked(xas->xa, node);
714 xas->xa_offset = node->offset - 1;
715 if (node->offset != 0)
721 xas->xa_shift = shift;
723 xas->xa_index = index;
726 xas->xa_index = index;
730 EXPORT_SYMBOL_GPL(xas_create_range);
732 static void update_node(struct xa_state *xas, struct xa_node *node,
733 int count, int values)
735 if (!node || (!count && !values))
738 node->count += count;
739 node->nr_values += values;
740 XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
741 XA_NODE_BUG_ON(node, node->nr_values > XA_CHUNK_SIZE);
742 xas_update(xas, node);
744 xas_delete_node(xas);
748 * xas_store() - Store this entry in the XArray.
749 * @xas: XArray operation state.
752 * If @xas is operating on a multi-index entry, the entry returned by this
753 * function is essentially meaningless (it may be an internal entry or it
754 * may be %NULL, even if there are non-NULL entries at some of the indices
755 * covered by the range). This is not a problem for any current users,
756 * and can be changed if needed.
758 * Return: The old entry at this index.
760 void *xas_store(struct xa_state *xas, void *entry)
762 struct xa_node *node;
763 void __rcu **slot = &xas->xa->xa_head;
764 unsigned int offset, max;
768 bool value = xa_is_value(entry);
771 first = xas_create(xas, !xa_is_node(entry));
773 first = xas_load(xas);
775 if (xas_invalid(xas))
778 if (node && (xas->xa_shift < node->shift))
780 if ((first == entry) && !xas->xa_sibs)
784 offset = xas->xa_offset;
785 max = xas->xa_offset + xas->xa_sibs;
787 slot = &node->slots[offset];
789 xas_squash_marks(xas);
796 * Must clear the marks before setting the entry to NULL,
797 * otherwise xas_for_each_marked may find a NULL entry and
798 * stop early. rcu_assign_pointer contains a release barrier
799 * so the mark clearing will appear to happen before the
800 * entry is set to NULL.
802 rcu_assign_pointer(*slot, entry);
803 if (xa_is_node(next))
804 xas_free_nodes(xas, xa_to_node(next));
807 count += !next - !entry;
808 values += !xa_is_value(first) - !value;
812 if (!xa_is_sibling(entry))
813 entry = xa_mk_sibling(xas->xa_offset);
815 if (offset == XA_CHUNK_MASK)
818 next = xa_entry_locked(xas->xa, node, ++offset);
819 if (!xa_is_sibling(next)) {
820 if (!entry && (offset > max))
827 update_node(xas, node, count, values);
830 EXPORT_SYMBOL_GPL(xas_store);
833 * xas_get_mark() - Returns the state of this mark.
834 * @xas: XArray operation state.
835 * @mark: Mark number.
837 * Return: true if the mark is set, false if the mark is clear or @xas
838 * is in an error state.
840 bool xas_get_mark(const struct xa_state *xas, xa_mark_t mark)
842 if (xas_invalid(xas))
845 return xa_marked(xas->xa, mark);
846 return node_get_mark(xas->xa_node, xas->xa_offset, mark);
848 EXPORT_SYMBOL_GPL(xas_get_mark);
851 * xas_set_mark() - Sets the mark on this entry and its parents.
852 * @xas: XArray operation state.
853 * @mark: Mark number.
855 * Sets the specified mark on this entry, and walks up the tree setting it
856 * on all the ancestor entries. Does nothing if @xas has not been walked to
857 * an entry, or is in an error state.
859 void xas_set_mark(const struct xa_state *xas, xa_mark_t mark)
861 struct xa_node *node = xas->xa_node;
862 unsigned int offset = xas->xa_offset;
864 if (xas_invalid(xas))
868 if (node_set_mark(node, offset, mark))
870 offset = node->offset;
871 node = xa_parent_locked(xas->xa, node);
874 if (!xa_marked(xas->xa, mark))
875 xa_mark_set(xas->xa, mark);
877 EXPORT_SYMBOL_GPL(xas_set_mark);
880 * xas_clear_mark() - Clears the mark on this entry and its parents.
881 * @xas: XArray operation state.
882 * @mark: Mark number.
884 * Clears the specified mark on this entry, and walks back to the head
885 * attempting to clear it on all the ancestor entries. Does nothing if
886 * @xas has not been walked to an entry, or is in an error state.
888 void xas_clear_mark(const struct xa_state *xas, xa_mark_t mark)
890 struct xa_node *node = xas->xa_node;
891 unsigned int offset = xas->xa_offset;
893 if (xas_invalid(xas))
897 if (!node_clear_mark(node, offset, mark))
899 if (node_any_mark(node, mark))
902 offset = node->offset;
903 node = xa_parent_locked(xas->xa, node);
906 if (xa_marked(xas->xa, mark))
907 xa_mark_clear(xas->xa, mark);
909 EXPORT_SYMBOL_GPL(xas_clear_mark);
912 * xas_init_marks() - Initialise all marks for the entry
913 * @xas: Array operations state.
915 * Initialise all marks for the entry specified by @xas. If we're tracking
916 * free entries with a mark, we need to set it on all entries. All other
919 * This implementation is not as efficient as it could be; we may walk
920 * up the tree multiple times.
922 void xas_init_marks(const struct xa_state *xas)
927 if (xa_track_free(xas->xa) && mark == XA_FREE_MARK)
928 xas_set_mark(xas, mark);
930 xas_clear_mark(xas, mark);
931 if (mark == XA_MARK_MAX)
936 EXPORT_SYMBOL_GPL(xas_init_marks);
939 * xas_pause() - Pause a walk to drop a lock.
940 * @xas: XArray operation state.
942 * Some users need to pause a walk and drop the lock they're holding in
943 * order to yield to a higher priority thread or carry out an operation
944 * on an entry. Those users should call this function before they drop
945 * the lock. It resets the @xas to be suitable for the next iteration
946 * of the loop after the user has reacquired the lock. If most entries
947 * found during a walk require you to call xas_pause(), the xa_for_each()
948 * iterator may be more appropriate.
950 * Note that xas_pause() only works for forward iteration. If a user needs
951 * to pause a reverse iteration, we will need a xas_pause_rev().
953 void xas_pause(struct xa_state *xas)
955 struct xa_node *node = xas->xa_node;
957 if (xas_invalid(xas))
961 unsigned int offset = xas->xa_offset;
962 while (++offset < XA_CHUNK_SIZE) {
963 if (!xa_is_sibling(xa_entry(xas->xa, node, offset)))
966 xas->xa_index += (offset - xas->xa_offset) << node->shift;
970 xas->xa_node = XAS_RESTART;
972 EXPORT_SYMBOL_GPL(xas_pause);
975 * __xas_prev() - Find the previous entry in the XArray.
976 * @xas: XArray operation state.
978 * Helper function for xas_prev() which handles all the complex cases
981 void *__xas_prev(struct xa_state *xas)
985 if (!xas_frozen(xas->xa_node))
987 if (xas_not_node(xas->xa_node))
988 return xas_load(xas);
990 if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node))
993 while (xas->xa_offset == 255) {
994 xas->xa_offset = xas->xa_node->offset - 1;
995 xas->xa_node = xa_parent(xas->xa, xas->xa_node);
997 return set_bounds(xas);
1001 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1002 if (!xa_is_node(entry))
1005 xas->xa_node = xa_to_node(entry);
1006 xas_set_offset(xas);
1009 EXPORT_SYMBOL_GPL(__xas_prev);
1012 * __xas_next() - Find the next entry in the XArray.
1013 * @xas: XArray operation state.
1015 * Helper function for xas_next() which handles all the complex cases
1018 void *__xas_next(struct xa_state *xas)
1022 if (!xas_frozen(xas->xa_node))
1024 if (xas_not_node(xas->xa_node))
1025 return xas_load(xas);
1027 if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node))
1030 while (xas->xa_offset == XA_CHUNK_SIZE) {
1031 xas->xa_offset = xas->xa_node->offset + 1;
1032 xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1034 return set_bounds(xas);
1038 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1039 if (!xa_is_node(entry))
1042 xas->xa_node = xa_to_node(entry);
1043 xas_set_offset(xas);
1046 EXPORT_SYMBOL_GPL(__xas_next);
1049 * xas_find() - Find the next present entry in the XArray.
1050 * @xas: XArray operation state.
1051 * @max: Highest index to return.
1053 * If the @xas has not yet been walked to an entry, return the entry
1054 * which has an index >= xas.xa_index. If it has been walked, the entry
1055 * currently being pointed at has been processed, and so we move to the
1058 * If no entry is found and the array is smaller than @max, the iterator
1059 * is set to the smallest index not yet in the array. This allows @xas
1060 * to be immediately passed to xas_store().
1062 * Return: The entry, if found, otherwise %NULL.
1064 void *xas_find(struct xa_state *xas, unsigned long max)
1071 if (!xas->xa_node) {
1073 return set_bounds(xas);
1074 } else if (xas_top(xas->xa_node)) {
1075 entry = xas_load(xas);
1076 if (entry || xas_not_node(xas->xa_node))
1078 } else if (!xas->xa_node->shift &&
1079 xas->xa_offset != (xas->xa_index & XA_CHUNK_MASK)) {
1080 xas->xa_offset = ((xas->xa_index - 1) & XA_CHUNK_MASK) + 1;
1085 while (xas->xa_node && (xas->xa_index <= max)) {
1086 if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) {
1087 xas->xa_offset = xas->xa_node->offset + 1;
1088 xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1092 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1093 if (xa_is_node(entry)) {
1094 xas->xa_node = xa_to_node(entry);
1098 if (entry && !xa_is_sibling(entry))
1105 xas->xa_node = XAS_BOUNDS;
1108 EXPORT_SYMBOL_GPL(xas_find);
1111 * xas_find_marked() - Find the next marked entry in the XArray.
1112 * @xas: XArray operation state.
1113 * @max: Highest index to return.
1114 * @mark: Mark number to search for.
1116 * If the @xas has not yet been walked to an entry, return the marked entry
1117 * which has an index >= xas.xa_index. If it has been walked, the entry
1118 * currently being pointed at has been processed, and so we return the
1119 * first marked entry with an index > xas.xa_index.
1121 * If no marked entry is found and the array is smaller than @max, @xas is
1122 * set to the bounds state and xas->xa_index is set to the smallest index
1123 * not yet in the array. This allows @xas to be immediately passed to
1126 * If no entry is found before @max is reached, @xas is set to the restart
1129 * Return: The entry, if found, otherwise %NULL.
1131 void *xas_find_marked(struct xa_state *xas, unsigned long max, xa_mark_t mark)
1133 bool advance = true;
1134 unsigned int offset;
1140 if (!xas->xa_node) {
1143 } else if (xas_top(xas->xa_node)) {
1145 entry = xa_head(xas->xa);
1146 xas->xa_node = NULL;
1147 if (xas->xa_index > max_index(entry))
1149 if (!xa_is_node(entry)) {
1150 if (xa_marked(xas->xa, mark))
1155 xas->xa_node = xa_to_node(entry);
1156 xas->xa_offset = xas->xa_index >> xas->xa_node->shift;
1159 while (xas->xa_index <= max) {
1160 if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) {
1161 xas->xa_offset = xas->xa_node->offset + 1;
1162 xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1170 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1171 if (xa_is_sibling(entry)) {
1172 xas->xa_offset = xa_to_sibling(entry);
1173 xas_move_index(xas, xas->xa_offset);
1177 offset = xas_find_chunk(xas, advance, mark);
1178 if (offset > xas->xa_offset) {
1180 xas_move_index(xas, offset);
1182 if ((xas->xa_index - 1) >= max)
1184 xas->xa_offset = offset;
1185 if (offset == XA_CHUNK_SIZE)
1189 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1190 if (!xa_is_node(entry))
1192 xas->xa_node = xa_to_node(entry);
1193 xas_set_offset(xas);
1197 if (xas->xa_index > max)
1199 return set_bounds(xas);
1201 xas->xa_node = XAS_RESTART;
1204 EXPORT_SYMBOL_GPL(xas_find_marked);
1207 * xas_find_conflict() - Find the next present entry in a range.
1208 * @xas: XArray operation state.
1210 * The @xas describes both a range and a position within that range.
1212 * Context: Any context. Expects xa_lock to be held.
1213 * Return: The next entry in the range covered by @xas or %NULL.
1215 void *xas_find_conflict(struct xa_state *xas)
1225 if (xas_top(xas->xa_node)) {
1226 curr = xas_start(xas);
1229 while (xa_is_node(curr)) {
1230 struct xa_node *node = xa_to_node(curr);
1231 curr = xas_descend(xas, node);
1237 if (xas->xa_node->shift > xas->xa_shift)
1241 if (xas->xa_node->shift == xas->xa_shift) {
1242 if ((xas->xa_offset & xas->xa_sibs) == xas->xa_sibs)
1244 } else if (xas->xa_offset == XA_CHUNK_MASK) {
1245 xas->xa_offset = xas->xa_node->offset;
1246 xas->xa_node = xa_parent_locked(xas->xa, xas->xa_node);
1251 curr = xa_entry_locked(xas->xa, xas->xa_node, ++xas->xa_offset);
1252 if (xa_is_sibling(curr))
1254 while (xa_is_node(curr)) {
1255 xas->xa_node = xa_to_node(curr);
1257 curr = xa_entry_locked(xas->xa, xas->xa_node, 0);
1262 xas->xa_offset -= xas->xa_sibs;
1265 EXPORT_SYMBOL_GPL(xas_find_conflict);
1268 * xa_load() - Load an entry from an XArray.
1270 * @index: index into array.
1272 * Context: Any context. Takes and releases the RCU lock.
1273 * Return: The entry at @index in @xa.
1275 void *xa_load(struct xarray *xa, unsigned long index)
1277 XA_STATE(xas, xa, index);
1282 entry = xas_load(&xas);
1283 if (xa_is_zero(entry))
1285 } while (xas_retry(&xas, entry));
1290 EXPORT_SYMBOL(xa_load);
1292 static void *xas_result(struct xa_state *xas, void *curr)
1294 if (xa_is_zero(curr))
1297 curr = xas->xa_node;
1302 * __xa_erase() - Erase this entry from the XArray while locked.
1304 * @index: Index into array.
1306 * After this function returns, loading from @index will return %NULL.
1307 * If the index is part of a multi-index entry, all indices will be erased
1308 * and none of the entries will be part of a multi-index entry.
1310 * Context: Any context. Expects xa_lock to be held on entry.
1311 * Return: The entry which used to be at this index.
1313 void *__xa_erase(struct xarray *xa, unsigned long index)
1315 XA_STATE(xas, xa, index);
1316 return xas_result(&xas, xas_store(&xas, NULL));
1318 EXPORT_SYMBOL(__xa_erase);
1321 * xa_erase() - Erase this entry from the XArray.
1323 * @index: Index of entry.
1325 * After this function returns, loading from @index will return %NULL.
1326 * If the index is part of a multi-index entry, all indices will be erased
1327 * and none of the entries will be part of a multi-index entry.
1329 * Context: Any context. Takes and releases the xa_lock.
1330 * Return: The entry which used to be at this index.
1332 void *xa_erase(struct xarray *xa, unsigned long index)
1337 entry = __xa_erase(xa, index);
1342 EXPORT_SYMBOL(xa_erase);
1345 * __xa_store() - Store this entry in the XArray.
1347 * @index: Index into array.
1348 * @entry: New entry.
1349 * @gfp: Memory allocation flags.
1351 * You must already be holding the xa_lock when calling this function.
1352 * It will drop the lock if needed to allocate memory, and then reacquire
1355 * Context: Any context. Expects xa_lock to be held on entry. May
1356 * release and reacquire xa_lock if @gfp flags permit.
1357 * Return: The old entry at this index or xa_err() if an error happened.
1359 void *__xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
1361 XA_STATE(xas, xa, index);
1364 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1365 return XA_ERROR(-EINVAL);
1366 if (xa_track_free(xa) && !entry)
1367 entry = XA_ZERO_ENTRY;
1370 curr = xas_store(&xas, entry);
1371 if (xa_track_free(xa))
1372 xas_clear_mark(&xas, XA_FREE_MARK);
1373 } while (__xas_nomem(&xas, gfp));
1375 return xas_result(&xas, curr);
1377 EXPORT_SYMBOL(__xa_store);
1380 * xa_store() - Store this entry in the XArray.
1382 * @index: Index into array.
1383 * @entry: New entry.
1384 * @gfp: Memory allocation flags.
1386 * After this function returns, loads from this index will return @entry.
1387 * Storing into an existing multislot entry updates the entry of every index.
1388 * The marks associated with @index are unaffected unless @entry is %NULL.
1390 * Context: Any context. Takes and releases the xa_lock.
1391 * May sleep if the @gfp flags permit.
1392 * Return: The old entry at this index on success, xa_err(-EINVAL) if @entry
1393 * cannot be stored in an XArray, or xa_err(-ENOMEM) if memory allocation
1396 void *xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
1401 curr = __xa_store(xa, index, entry, gfp);
1406 EXPORT_SYMBOL(xa_store);
1409 * __xa_cmpxchg() - Store this entry in the XArray.
1411 * @index: Index into array.
1412 * @old: Old value to test against.
1413 * @entry: New entry.
1414 * @gfp: Memory allocation flags.
1416 * You must already be holding the xa_lock when calling this function.
1417 * It will drop the lock if needed to allocate memory, and then reacquire
1420 * Context: Any context. Expects xa_lock to be held on entry. May
1421 * release and reacquire xa_lock if @gfp flags permit.
1422 * Return: The old entry at this index or xa_err() if an error happened.
1424 void *__xa_cmpxchg(struct xarray *xa, unsigned long index,
1425 void *old, void *entry, gfp_t gfp)
1427 XA_STATE(xas, xa, index);
1430 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1431 return XA_ERROR(-EINVAL);
1432 if (xa_track_free(xa) && !entry)
1433 entry = XA_ZERO_ENTRY;
1436 curr = xas_load(&xas);
1437 if (curr == XA_ZERO_ENTRY)
1440 xas_store(&xas, entry);
1441 if (xa_track_free(xa))
1442 xas_clear_mark(&xas, XA_FREE_MARK);
1444 } while (__xas_nomem(&xas, gfp));
1446 return xas_result(&xas, curr);
1448 EXPORT_SYMBOL(__xa_cmpxchg);
1451 * __xa_insert() - Store this entry in the XArray if no entry is present.
1453 * @index: Index into array.
1454 * @entry: New entry.
1455 * @gfp: Memory allocation flags.
1457 * Inserting a NULL entry will store a reserved entry (like xa_reserve())
1458 * if no entry is present. Inserting will fail if a reserved entry is
1459 * present, even though loading from this index will return NULL.
1461 * Context: Any context. Expects xa_lock to be held on entry. May
1462 * release and reacquire xa_lock if @gfp flags permit.
1463 * Return: 0 if the store succeeded. -EBUSY if another entry was present.
1464 * -ENOMEM if memory could not be allocated.
1466 int __xa_insert(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
1468 XA_STATE(xas, xa, index);
1471 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1474 entry = XA_ZERO_ENTRY;
1477 curr = xas_load(&xas);
1479 xas_store(&xas, entry);
1480 if (xa_track_free(xa))
1481 xas_clear_mark(&xas, XA_FREE_MARK);
1483 xas_set_err(&xas, -EBUSY);
1485 } while (__xas_nomem(&xas, gfp));
1487 return xas_error(&xas);
1489 EXPORT_SYMBOL(__xa_insert);
1492 * __xa_reserve() - Reserve this index in the XArray.
1494 * @index: Index into array.
1495 * @gfp: Memory allocation flags.
1497 * Ensures there is somewhere to store an entry at @index in the array.
1498 * If there is already something stored at @index, this function does
1499 * nothing. If there was nothing there, the entry is marked as reserved.
1500 * Loading from a reserved entry returns a %NULL pointer.
1502 * If you do not use the entry that you have reserved, call xa_release()
1503 * or xa_erase() to free any unnecessary memory.
1505 * Context: Any context. Expects the xa_lock to be held on entry. May
1506 * release the lock, sleep and reacquire the lock if the @gfp flags permit.
1507 * Return: 0 if the reservation succeeded or -ENOMEM if it failed.
1509 int __xa_reserve(struct xarray *xa, unsigned long index, gfp_t gfp)
1511 XA_STATE(xas, xa, index);
1515 curr = xas_load(&xas);
1517 xas_store(&xas, XA_ZERO_ENTRY);
1518 if (xa_track_free(xa))
1519 xas_clear_mark(&xas, XA_FREE_MARK);
1521 } while (__xas_nomem(&xas, gfp));
1523 return xas_error(&xas);
1525 EXPORT_SYMBOL(__xa_reserve);
1527 #ifdef CONFIG_XARRAY_MULTI
1528 static void xas_set_range(struct xa_state *xas, unsigned long first,
1531 unsigned int shift = 0;
1532 unsigned long sibs = last - first;
1533 unsigned int offset = XA_CHUNK_MASK;
1535 xas_set(xas, first);
1537 while ((first & XA_CHUNK_MASK) == 0) {
1538 if (sibs < XA_CHUNK_MASK)
1540 if ((sibs == XA_CHUNK_MASK) && (offset < XA_CHUNK_MASK))
1542 shift += XA_CHUNK_SHIFT;
1543 if (offset == XA_CHUNK_MASK)
1544 offset = sibs & XA_CHUNK_MASK;
1545 sibs >>= XA_CHUNK_SHIFT;
1546 first >>= XA_CHUNK_SHIFT;
1549 offset = first & XA_CHUNK_MASK;
1550 if (offset + sibs > XA_CHUNK_MASK)
1551 sibs = XA_CHUNK_MASK - offset;
1552 if ((((first + sibs + 1) << shift) - 1) > last)
1555 xas->xa_shift = shift;
1556 xas->xa_sibs = sibs;
1560 * xa_store_range() - Store this entry at a range of indices in the XArray.
1562 * @first: First index to affect.
1563 * @last: Last index to affect.
1564 * @entry: New entry.
1565 * @gfp: Memory allocation flags.
1567 * After this function returns, loads from any index between @first and @last,
1568 * inclusive will return @entry.
1569 * Storing into an existing multislot entry updates the entry of every index.
1570 * The marks associated with @index are unaffected unless @entry is %NULL.
1572 * Context: Process context. Takes and releases the xa_lock. May sleep
1573 * if the @gfp flags permit.
1574 * Return: %NULL on success, xa_err(-EINVAL) if @entry cannot be stored in
1575 * an XArray, or xa_err(-ENOMEM) if memory allocation failed.
1577 void *xa_store_range(struct xarray *xa, unsigned long first,
1578 unsigned long last, void *entry, gfp_t gfp)
1580 XA_STATE(xas, xa, 0);
1582 if (WARN_ON_ONCE(xa_is_internal(entry)))
1583 return XA_ERROR(-EINVAL);
1585 return XA_ERROR(-EINVAL);
1590 unsigned int order = BITS_PER_LONG;
1592 order = __ffs(last + 1);
1593 xas_set_order(&xas, last, order);
1594 xas_create(&xas, true);
1595 if (xas_error(&xas))
1599 xas_set_range(&xas, first, last);
1600 xas_store(&xas, entry);
1601 if (xas_error(&xas))
1603 first += xas_size(&xas);
1604 } while (first <= last);
1607 } while (xas_nomem(&xas, gfp));
1609 return xas_result(&xas, NULL);
1611 EXPORT_SYMBOL(xa_store_range);
1612 #endif /* CONFIG_XARRAY_MULTI */
1615 * __xa_alloc() - Find somewhere to store this entry in the XArray.
1617 * @id: Pointer to ID.
1618 * @limit: Range for allocated ID.
1619 * @entry: New entry.
1620 * @gfp: Memory allocation flags.
1622 * Finds an empty entry in @xa between @limit.min and @limit.max,
1623 * stores the index into the @id pointer, then stores the entry at
1624 * that index. A concurrent lookup will not see an uninitialised @id.
1626 * Context: Any context. Expects xa_lock to be held on entry. May
1627 * release and reacquire xa_lock if @gfp flags permit.
1628 * Return: 0 on success, -ENOMEM if memory could not be allocated or
1629 * -EBUSY if there are no free entries in @limit.
1631 int __xa_alloc(struct xarray *xa, u32 *id, void *entry,
1632 struct xa_limit limit, gfp_t gfp)
1634 XA_STATE(xas, xa, 0);
1636 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1638 if (WARN_ON_ONCE(!xa_track_free(xa)))
1642 entry = XA_ZERO_ENTRY;
1645 xas.xa_index = limit.min;
1646 xas_find_marked(&xas, limit.max, XA_FREE_MARK);
1647 if (xas.xa_node == XAS_RESTART)
1648 xas_set_err(&xas, -EBUSY);
1651 xas_store(&xas, entry);
1652 xas_clear_mark(&xas, XA_FREE_MARK);
1653 } while (__xas_nomem(&xas, gfp));
1655 return xas_error(&xas);
1657 EXPORT_SYMBOL(__xa_alloc);
1660 * __xa_alloc_cyclic() - Find somewhere to store this entry in the XArray.
1662 * @id: Pointer to ID.
1663 * @entry: New entry.
1664 * @limit: Range of allocated ID.
1665 * @next: Pointer to next ID to allocate.
1666 * @gfp: Memory allocation flags.
1668 * Finds an empty entry in @xa between @limit.min and @limit.max,
1669 * stores the index into the @id pointer, then stores the entry at
1670 * that index. A concurrent lookup will not see an uninitialised @id.
1671 * The search for an empty entry will start at @next and will wrap
1672 * around if necessary.
1674 * Context: Any context. Expects xa_lock to be held on entry. May
1675 * release and reacquire xa_lock if @gfp flags permit.
1676 * Return: 0 if the allocation succeeded without wrapping. 1 if the
1677 * allocation succeeded after wrapping, -ENOMEM if memory could not be
1678 * allocated or -EBUSY if there are no free entries in @limit.
1680 int __xa_alloc_cyclic(struct xarray *xa, u32 *id, void *entry,
1681 struct xa_limit limit, u32 *next, gfp_t gfp)
1683 u32 min = limit.min;
1686 limit.min = max(min, *next);
1687 ret = __xa_alloc(xa, id, entry, limit, gfp);
1688 if ((xa->xa_flags & XA_FLAGS_ALLOC_WRAPPED) && ret == 0) {
1689 xa->xa_flags &= ~XA_FLAGS_ALLOC_WRAPPED;
1693 if (ret < 0 && limit.min > min) {
1695 ret = __xa_alloc(xa, id, entry, limit, gfp);
1703 xa->xa_flags |= XA_FLAGS_ALLOC_WRAPPED;
1707 EXPORT_SYMBOL(__xa_alloc_cyclic);
1710 * __xa_set_mark() - Set this mark on this entry while locked.
1712 * @index: Index of entry.
1713 * @mark: Mark number.
1715 * Attempting to set a mark on a %NULL entry does not succeed.
1717 * Context: Any context. Expects xa_lock to be held on entry.
1719 void __xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1721 XA_STATE(xas, xa, index);
1722 void *entry = xas_load(&xas);
1725 xas_set_mark(&xas, mark);
1727 EXPORT_SYMBOL(__xa_set_mark);
1730 * __xa_clear_mark() - Clear this mark on this entry while locked.
1732 * @index: Index of entry.
1733 * @mark: Mark number.
1735 * Context: Any context. Expects xa_lock to be held on entry.
1737 void __xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1739 XA_STATE(xas, xa, index);
1740 void *entry = xas_load(&xas);
1743 xas_clear_mark(&xas, mark);
1745 EXPORT_SYMBOL(__xa_clear_mark);
1748 * xa_get_mark() - Inquire whether this mark is set on this entry.
1750 * @index: Index of entry.
1751 * @mark: Mark number.
1753 * This function uses the RCU read lock, so the result may be out of date
1754 * by the time it returns. If you need the result to be stable, use a lock.
1756 * Context: Any context. Takes and releases the RCU lock.
1757 * Return: True if the entry at @index has this mark set, false if it doesn't.
1759 bool xa_get_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1761 XA_STATE(xas, xa, index);
1765 entry = xas_start(&xas);
1766 while (xas_get_mark(&xas, mark)) {
1767 if (!xa_is_node(entry))
1769 entry = xas_descend(&xas, xa_to_node(entry));
1777 EXPORT_SYMBOL(xa_get_mark);
1780 * xa_set_mark() - Set this mark on this entry.
1782 * @index: Index of entry.
1783 * @mark: Mark number.
1785 * Attempting to set a mark on a %NULL entry does not succeed.
1787 * Context: Process context. Takes and releases the xa_lock.
1789 void xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1792 __xa_set_mark(xa, index, mark);
1795 EXPORT_SYMBOL(xa_set_mark);
1798 * xa_clear_mark() - Clear this mark on this entry.
1800 * @index: Index of entry.
1801 * @mark: Mark number.
1803 * Clearing a mark always succeeds.
1805 * Context: Process context. Takes and releases the xa_lock.
1807 void xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1810 __xa_clear_mark(xa, index, mark);
1813 EXPORT_SYMBOL(xa_clear_mark);
1816 * xa_find() - Search the XArray for an entry.
1818 * @indexp: Pointer to an index.
1819 * @max: Maximum index to search to.
1820 * @filter: Selection criterion.
1822 * Finds the entry in @xa which matches the @filter, and has the lowest
1823 * index that is at least @indexp and no more than @max.
1824 * If an entry is found, @indexp is updated to be the index of the entry.
1825 * This function is protected by the RCU read lock, so it may not find
1826 * entries which are being simultaneously added. It will not return an
1827 * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
1829 * Context: Any context. Takes and releases the RCU lock.
1830 * Return: The entry, if found, otherwise %NULL.
1832 void *xa_find(struct xarray *xa, unsigned long *indexp,
1833 unsigned long max, xa_mark_t filter)
1835 XA_STATE(xas, xa, *indexp);
1840 if ((__force unsigned int)filter < XA_MAX_MARKS)
1841 entry = xas_find_marked(&xas, max, filter);
1843 entry = xas_find(&xas, max);
1844 } while (xas_retry(&xas, entry));
1848 *indexp = xas.xa_index;
1851 EXPORT_SYMBOL(xa_find);
1854 * xa_find_after() - Search the XArray for a present entry.
1856 * @indexp: Pointer to an index.
1857 * @max: Maximum index to search to.
1858 * @filter: Selection criterion.
1860 * Finds the entry in @xa which matches the @filter and has the lowest
1861 * index that is above @indexp and no more than @max.
1862 * If an entry is found, @indexp is updated to be the index of the entry.
1863 * This function is protected by the RCU read lock, so it may miss entries
1864 * which are being simultaneously added. It will not return an
1865 * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
1867 * Context: Any context. Takes and releases the RCU lock.
1868 * Return: The pointer, if found, otherwise %NULL.
1870 void *xa_find_after(struct xarray *xa, unsigned long *indexp,
1871 unsigned long max, xa_mark_t filter)
1873 XA_STATE(xas, xa, *indexp + 1);
1878 if ((__force unsigned int)filter < XA_MAX_MARKS)
1879 entry = xas_find_marked(&xas, max, filter);
1881 entry = xas_find(&xas, max);
1882 if (xas.xa_node == XAS_BOUNDS)
1885 if (xas.xa_index & ((1UL << xas.xa_shift) - 1))
1888 if (xas.xa_offset < (xas.xa_index & XA_CHUNK_MASK))
1891 if (!xas_retry(&xas, entry))
1897 *indexp = xas.xa_index;
1900 EXPORT_SYMBOL(xa_find_after);
1902 static unsigned int xas_extract_present(struct xa_state *xas, void **dst,
1903 unsigned long max, unsigned int n)
1909 xas_for_each(xas, entry, max) {
1910 if (xas_retry(xas, entry))
1921 static unsigned int xas_extract_marked(struct xa_state *xas, void **dst,
1922 unsigned long max, unsigned int n, xa_mark_t mark)
1928 xas_for_each_marked(xas, entry, max, mark) {
1929 if (xas_retry(xas, entry))
1941 * xa_extract() - Copy selected entries from the XArray into a normal array.
1942 * @xa: The source XArray to copy from.
1943 * @dst: The buffer to copy entries into.
1944 * @start: The first index in the XArray eligible to be selected.
1945 * @max: The last index in the XArray eligible to be selected.
1946 * @n: The maximum number of entries to copy.
1947 * @filter: Selection criterion.
1949 * Copies up to @n entries that match @filter from the XArray. The
1950 * copied entries will have indices between @start and @max, inclusive.
1952 * The @filter may be an XArray mark value, in which case entries which are
1953 * marked with that mark will be copied. It may also be %XA_PRESENT, in
1954 * which case all entries which are not %NULL will be copied.
1956 * The entries returned may not represent a snapshot of the XArray at a
1957 * moment in time. For example, if another thread stores to index 5, then
1958 * index 10, calling xa_extract() may return the old contents of index 5
1959 * and the new contents of index 10. Indices not modified while this
1960 * function is running will not be skipped.
1962 * If you need stronger guarantees, holding the xa_lock across calls to this
1963 * function will prevent concurrent modification.
1965 * Context: Any context. Takes and releases the RCU lock.
1966 * Return: The number of entries copied.
1968 unsigned int xa_extract(struct xarray *xa, void **dst, unsigned long start,
1969 unsigned long max, unsigned int n, xa_mark_t filter)
1971 XA_STATE(xas, xa, start);
1976 if ((__force unsigned int)filter < XA_MAX_MARKS)
1977 return xas_extract_marked(&xas, dst, max, n, filter);
1978 return xas_extract_present(&xas, dst, max, n);
1980 EXPORT_SYMBOL(xa_extract);
1983 * xa_destroy() - Free all internal data structures.
1986 * After calling this function, the XArray is empty and has freed all memory
1987 * allocated for its internal data structures. You are responsible for
1988 * freeing the objects referenced by the XArray.
1990 * Context: Any context. Takes and releases the xa_lock, interrupt-safe.
1992 void xa_destroy(struct xarray *xa)
1994 XA_STATE(xas, xa, 0);
1995 unsigned long flags;
1999 xas_lock_irqsave(&xas, flags);
2000 entry = xa_head_locked(xa);
2001 RCU_INIT_POINTER(xa->xa_head, NULL);
2002 xas_init_marks(&xas);
2003 if (xa_zero_busy(xa))
2004 xa_mark_clear(xa, XA_FREE_MARK);
2005 /* lockdep checks we're still holding the lock in xas_free_nodes() */
2006 if (xa_is_node(entry))
2007 xas_free_nodes(&xas, xa_to_node(entry));
2008 xas_unlock_irqrestore(&xas, flags);
2010 EXPORT_SYMBOL(xa_destroy);
2013 void xa_dump_node(const struct xa_node *node)
2019 if ((unsigned long)node & 3) {
2020 pr_cont("node %px\n", node);
2024 pr_cont("node %px %s %d parent %px shift %d count %d values %d "
2025 "array %px list %px %px marks",
2026 node, node->parent ? "offset" : "max", node->offset,
2027 node->parent, node->shift, node->count, node->nr_values,
2028 node->array, node->private_list.prev, node->private_list.next);
2029 for (i = 0; i < XA_MAX_MARKS; i++)
2030 for (j = 0; j < XA_MARK_LONGS; j++)
2031 pr_cont(" %lx", node->marks[i][j]);
2035 void xa_dump_index(unsigned long index, unsigned int shift)
2038 pr_info("%lu: ", index);
2039 else if (shift >= BITS_PER_LONG)
2040 pr_info("0-%lu: ", ~0UL);
2042 pr_info("%lu-%lu: ", index, index | ((1UL << shift) - 1));
2045 void xa_dump_entry(const void *entry, unsigned long index, unsigned long shift)
2050 xa_dump_index(index, shift);
2052 if (xa_is_node(entry)) {
2054 pr_cont("%px\n", entry);
2057 struct xa_node *node = xa_to_node(entry);
2059 for (i = 0; i < XA_CHUNK_SIZE; i++)
2060 xa_dump_entry(node->slots[i],
2061 index + (i << node->shift), node->shift);
2063 } else if (xa_is_value(entry))
2064 pr_cont("value %ld (0x%lx) [%px]\n", xa_to_value(entry),
2065 xa_to_value(entry), entry);
2066 else if (!xa_is_internal(entry))
2067 pr_cont("%px\n", entry);
2068 else if (xa_is_retry(entry))
2069 pr_cont("retry (%ld)\n", xa_to_internal(entry));
2070 else if (xa_is_sibling(entry))
2071 pr_cont("sibling (slot %ld)\n", xa_to_sibling(entry));
2072 else if (xa_is_zero(entry))
2073 pr_cont("zero (%ld)\n", xa_to_internal(entry));
2075 pr_cont("UNKNOWN ENTRY (%px)\n", entry);
2078 void xa_dump(const struct xarray *xa)
2080 void *entry = xa->xa_head;
2081 unsigned int shift = 0;
2083 pr_info("xarray: %px head %px flags %x marks %d %d %d\n", xa, entry,
2084 xa->xa_flags, xa_marked(xa, XA_MARK_0),
2085 xa_marked(xa, XA_MARK_1), xa_marked(xa, XA_MARK_2));
2086 if (xa_is_node(entry))
2087 shift = xa_to_node(entry)->shift + XA_CHUNK_SHIFT;
2088 xa_dump_entry(entry, 0, shift);