1 // SPDX-License-Identifier: GPL-2.0+
3 * XArray implementation
4 * Copyright (c) 2017-2018 Microsoft Corporation
5 * Copyright (c) 2018-2020 Oracle
6 * Author: Matthew Wilcox <willy@infradead.org>
9 #include <linux/bitmap.h>
10 #include <linux/export.h>
11 #include <linux/list.h>
12 #include <linux/slab.h>
13 #include <linux/xarray.h>
16 * Coding conventions in this file:
18 * @xa is used to refer to the entire xarray.
19 * @xas is the 'xarray operation state'. It may be either a pointer to
20 * an xa_state, or an xa_state stored on the stack. This is an unfortunate
22 * @index is the index of the entry being operated on
23 * @mark is an xa_mark_t; a small number indicating one of the mark bits.
24 * @node refers to an xa_node; usually the primary one being operated on by
26 * @offset is the index into the slots array inside an xa_node.
27 * @parent refers to the @xa_node closer to the head than @node.
28 * @entry refers to something stored in a slot in the xarray
31 static inline unsigned int xa_lock_type(const struct xarray *xa)
33 return (__force unsigned int)xa->xa_flags & 3;
36 static inline void xas_lock_type(struct xa_state *xas, unsigned int lock_type)
38 if (lock_type == XA_LOCK_IRQ)
40 else if (lock_type == XA_LOCK_BH)
46 static inline void xas_unlock_type(struct xa_state *xas, unsigned int lock_type)
48 if (lock_type == XA_LOCK_IRQ)
50 else if (lock_type == XA_LOCK_BH)
56 static inline bool xa_track_free(const struct xarray *xa)
58 return xa->xa_flags & XA_FLAGS_TRACK_FREE;
61 static inline bool xa_zero_busy(const struct xarray *xa)
63 return xa->xa_flags & XA_FLAGS_ZERO_BUSY;
66 static inline void xa_mark_set(struct xarray *xa, xa_mark_t mark)
68 if (!(xa->xa_flags & XA_FLAGS_MARK(mark)))
69 xa->xa_flags |= XA_FLAGS_MARK(mark);
72 static inline void xa_mark_clear(struct xarray *xa, xa_mark_t mark)
74 if (xa->xa_flags & XA_FLAGS_MARK(mark))
75 xa->xa_flags &= ~(XA_FLAGS_MARK(mark));
78 static inline unsigned long *node_marks(struct xa_node *node, xa_mark_t mark)
80 return node->marks[(__force unsigned)mark];
83 static inline bool node_get_mark(struct xa_node *node,
84 unsigned int offset, xa_mark_t mark)
86 return test_bit(offset, node_marks(node, mark));
89 /* returns true if the bit was set */
90 static inline bool node_set_mark(struct xa_node *node, unsigned int offset,
93 return __test_and_set_bit(offset, node_marks(node, mark));
96 /* returns true if the bit was set */
97 static inline bool node_clear_mark(struct xa_node *node, unsigned int offset,
100 return __test_and_clear_bit(offset, node_marks(node, mark));
103 static inline bool node_any_mark(struct xa_node *node, xa_mark_t mark)
105 return !bitmap_empty(node_marks(node, mark), XA_CHUNK_SIZE);
108 static inline void node_mark_all(struct xa_node *node, xa_mark_t mark)
110 bitmap_fill(node_marks(node, mark), XA_CHUNK_SIZE);
113 #define mark_inc(mark) do { \
114 mark = (__force xa_mark_t)((__force unsigned)(mark) + 1); \
118 * xas_squash_marks() - Merge all marks to the first entry
119 * @xas: Array operation state.
121 * Set a mark on the first entry if any entry has it set. Clear marks on
122 * all sibling entries.
124 static void xas_squash_marks(const struct xa_state *xas)
126 unsigned int mark = 0;
127 unsigned int limit = xas->xa_offset + xas->xa_sibs + 1;
133 unsigned long *marks = xas->xa_node->marks[mark];
134 if (find_next_bit(marks, limit, xas->xa_offset + 1) == limit)
136 __set_bit(xas->xa_offset, marks);
137 bitmap_clear(marks, xas->xa_offset + 1, xas->xa_sibs);
138 } while (mark++ != (__force unsigned)XA_MARK_MAX);
141 /* extracts the offset within this node from the index */
142 static unsigned int get_offset(unsigned long index, struct xa_node *node)
144 return (index >> node->shift) & XA_CHUNK_MASK;
147 static void xas_set_offset(struct xa_state *xas)
149 xas->xa_offset = get_offset(xas->xa_index, xas->xa_node);
152 /* move the index either forwards (find) or backwards (sibling slot) */
153 static void xas_move_index(struct xa_state *xas, unsigned long offset)
155 unsigned int shift = xas->xa_node->shift;
156 xas->xa_index &= ~XA_CHUNK_MASK << shift;
157 xas->xa_index += offset << shift;
160 static void xas_next_offset(struct xa_state *xas)
163 xas_move_index(xas, xas->xa_offset);
166 static void *set_bounds(struct xa_state *xas)
168 xas->xa_node = XAS_BOUNDS;
173 * Starts a walk. If the @xas is already valid, we assume that it's on
174 * the right path and just return where we've got to. If we're in an
175 * error state, return NULL. If the index is outside the current scope
176 * of the xarray, return NULL without changing @xas->xa_node. Otherwise
177 * set @xas->xa_node to NULL and return the current head of the array.
179 static void *xas_start(struct xa_state *xas)
184 return xas_reload(xas);
188 entry = xa_head(xas->xa);
189 if (!xa_is_node(entry)) {
191 return set_bounds(xas);
193 if ((xas->xa_index >> xa_to_node(entry)->shift) > XA_CHUNK_MASK)
194 return set_bounds(xas);
201 static void *xas_descend(struct xa_state *xas, struct xa_node *node)
203 unsigned int offset = get_offset(xas->xa_index, node);
204 void *entry = xa_entry(xas->xa, node, offset);
207 if (xa_is_sibling(entry)) {
208 offset = xa_to_sibling(entry);
209 entry = xa_entry(xas->xa, node, offset);
210 if (node->shift && xa_is_node(entry))
211 entry = XA_RETRY_ENTRY;
214 xas->xa_offset = offset;
219 * xas_load() - Load an entry from the XArray (advanced).
220 * @xas: XArray operation state.
222 * Usually walks the @xas to the appropriate state to load the entry
223 * stored at xa_index. However, it will do nothing and return %NULL if
224 * @xas is in an error state. xas_load() will never expand the tree.
226 * If the xa_state is set up to operate on a multi-index entry, xas_load()
227 * may return %NULL or an internal entry, even if there are entries
228 * present within the range specified by @xas.
230 * Context: Any context. The caller should hold the xa_lock or the RCU lock.
231 * Return: Usually an entry in the XArray, but see description for exceptions.
233 void *xas_load(struct xa_state *xas)
235 void *entry = xas_start(xas);
237 while (xa_is_node(entry)) {
238 struct xa_node *node = xa_to_node(entry);
240 if (xas->xa_shift > node->shift)
242 entry = xas_descend(xas, node);
243 if (node->shift == 0)
248 EXPORT_SYMBOL_GPL(xas_load);
250 /* Move the radix tree node cache here */
251 extern struct kmem_cache *radix_tree_node_cachep;
252 extern void radix_tree_node_rcu_free(struct rcu_head *head);
254 #define XA_RCU_FREE ((struct xarray *)1)
256 static void xa_node_free(struct xa_node *node)
258 XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
259 node->array = XA_RCU_FREE;
260 call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
264 * xas_destroy() - Free any resources allocated during the XArray operation.
265 * @xas: XArray operation state.
267 * Most users will not need to call this function; it is called for you
270 void xas_destroy(struct xa_state *xas)
272 struct xa_node *next, *node = xas->xa_alloc;
275 XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
276 next = rcu_dereference_raw(node->parent);
277 radix_tree_node_rcu_free(&node->rcu_head);
278 xas->xa_alloc = node = next;
283 * xas_nomem() - Allocate memory if needed.
284 * @xas: XArray operation state.
285 * @gfp: Memory allocation flags.
287 * If we need to add new nodes to the XArray, we try to allocate memory
288 * with GFP_NOWAIT while holding the lock, which will usually succeed.
289 * If it fails, @xas is flagged as needing memory to continue. The caller
290 * should drop the lock and call xas_nomem(). If xas_nomem() succeeds,
291 * the caller should retry the operation.
293 * Forward progress is guaranteed as one node is allocated here and
294 * stored in the xa_state where it will be found by xas_alloc(). More
295 * nodes will likely be found in the slab allocator, but we do not tie
298 * Return: true if memory was needed, and was successfully allocated.
300 bool xas_nomem(struct xa_state *xas, gfp_t gfp)
302 if (xas->xa_node != XA_ERROR(-ENOMEM)) {
306 if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT)
307 gfp |= __GFP_ACCOUNT;
308 xas->xa_alloc = kmem_cache_alloc_lru(radix_tree_node_cachep, xas->xa_lru, gfp);
311 xas->xa_alloc->parent = NULL;
312 XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list));
313 xas->xa_node = XAS_RESTART;
316 EXPORT_SYMBOL_GPL(xas_nomem);
319 * __xas_nomem() - Drop locks and allocate memory if needed.
320 * @xas: XArray operation state.
321 * @gfp: Memory allocation flags.
323 * Internal variant of xas_nomem().
325 * Return: true if memory was needed, and was successfully allocated.
327 static bool __xas_nomem(struct xa_state *xas, gfp_t gfp)
328 __must_hold(xas->xa->xa_lock)
330 unsigned int lock_type = xa_lock_type(xas->xa);
332 if (xas->xa_node != XA_ERROR(-ENOMEM)) {
336 if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT)
337 gfp |= __GFP_ACCOUNT;
338 if (gfpflags_allow_blocking(gfp)) {
339 xas_unlock_type(xas, lock_type);
340 xas->xa_alloc = kmem_cache_alloc_lru(radix_tree_node_cachep, xas->xa_lru, gfp);
341 xas_lock_type(xas, lock_type);
343 xas->xa_alloc = kmem_cache_alloc_lru(radix_tree_node_cachep, xas->xa_lru, gfp);
347 xas->xa_alloc->parent = NULL;
348 XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list));
349 xas->xa_node = XAS_RESTART;
353 static void xas_update(struct xa_state *xas, struct xa_node *node)
356 xas->xa_update(node);
358 XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
361 static void *xas_alloc(struct xa_state *xas, unsigned int shift)
363 struct xa_node *parent = xas->xa_node;
364 struct xa_node *node = xas->xa_alloc;
366 if (xas_invalid(xas))
370 xas->xa_alloc = NULL;
372 gfp_t gfp = GFP_NOWAIT | __GFP_NOWARN;
374 if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT)
375 gfp |= __GFP_ACCOUNT;
377 node = kmem_cache_alloc_lru(radix_tree_node_cachep, xas->xa_lru, gfp);
379 xas_set_err(xas, -ENOMEM);
385 node->offset = xas->xa_offset;
387 XA_NODE_BUG_ON(node, parent->count > XA_CHUNK_SIZE);
388 xas_update(xas, parent);
390 XA_NODE_BUG_ON(node, shift > BITS_PER_LONG);
391 XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
395 RCU_INIT_POINTER(node->parent, xas->xa_node);
396 node->array = xas->xa;
401 #ifdef CONFIG_XARRAY_MULTI
402 /* Returns the number of indices covered by a given xa_state */
403 static unsigned long xas_size(const struct xa_state *xas)
405 return (xas->xa_sibs + 1UL) << xas->xa_shift;
410 * Use this to calculate the maximum index that will need to be created
411 * in order to add the entry described by @xas. Because we cannot store a
412 * multi-index entry at index 0, the calculation is a little more complex
413 * than you might expect.
415 static unsigned long xas_max(struct xa_state *xas)
417 unsigned long max = xas->xa_index;
419 #ifdef CONFIG_XARRAY_MULTI
420 if (xas->xa_shift || xas->xa_sibs) {
421 unsigned long mask = xas_size(xas) - 1;
431 /* The maximum index that can be contained in the array without expanding it */
432 static unsigned long max_index(void *entry)
434 if (!xa_is_node(entry))
436 return (XA_CHUNK_SIZE << xa_to_node(entry)->shift) - 1;
439 static void xas_shrink(struct xa_state *xas)
441 struct xarray *xa = xas->xa;
442 struct xa_node *node = xas->xa_node;
447 XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
448 if (node->count != 1)
450 entry = xa_entry_locked(xa, node, 0);
453 if (!xa_is_node(entry) && node->shift)
455 if (xa_is_zero(entry) && xa_zero_busy(xa))
457 xas->xa_node = XAS_BOUNDS;
459 RCU_INIT_POINTER(xa->xa_head, entry);
460 if (xa_track_free(xa) && !node_get_mark(node, 0, XA_FREE_MARK))
461 xa_mark_clear(xa, XA_FREE_MARK);
465 if (!xa_is_node(entry))
466 RCU_INIT_POINTER(node->slots[0], XA_RETRY_ENTRY);
467 xas_update(xas, node);
469 if (!xa_is_node(entry))
471 node = xa_to_node(entry);
477 * xas_delete_node() - Attempt to delete an xa_node
478 * @xas: Array operation state.
480 * Attempts to delete the @xas->xa_node. This will fail if xa->node has
481 * a non-zero reference count.
483 static void xas_delete_node(struct xa_state *xas)
485 struct xa_node *node = xas->xa_node;
488 struct xa_node *parent;
490 XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
494 parent = xa_parent_locked(xas->xa, node);
495 xas->xa_node = parent;
496 xas->xa_offset = node->offset;
500 xas->xa->xa_head = NULL;
501 xas->xa_node = XAS_BOUNDS;
505 parent->slots[xas->xa_offset] = NULL;
507 XA_NODE_BUG_ON(parent, parent->count > XA_CHUNK_SIZE);
509 xas_update(xas, node);
517 * xas_free_nodes() - Free this node and all nodes that it references
518 * @xas: Array operation state.
521 * This node has been removed from the tree. We must now free it and all
522 * of its subnodes. There may be RCU walkers with references into the tree,
523 * so we must replace all entries with retry markers.
525 static void xas_free_nodes(struct xa_state *xas, struct xa_node *top)
527 unsigned int offset = 0;
528 struct xa_node *node = top;
531 void *entry = xa_entry_locked(xas->xa, node, offset);
533 if (node->shift && xa_is_node(entry)) {
534 node = xa_to_node(entry);
539 RCU_INIT_POINTER(node->slots[offset], XA_RETRY_ENTRY);
541 while (offset == XA_CHUNK_SIZE) {
542 struct xa_node *parent;
544 parent = xa_parent_locked(xas->xa, node);
545 offset = node->offset + 1;
548 xas_update(xas, node);
558 * xas_expand adds nodes to the head of the tree until it has reached
559 * sufficient height to be able to contain @xas->xa_index
561 static int xas_expand(struct xa_state *xas, void *head)
563 struct xarray *xa = xas->xa;
564 struct xa_node *node = NULL;
565 unsigned int shift = 0;
566 unsigned long max = xas_max(xas);
571 while ((max >> shift) >= XA_CHUNK_SIZE)
572 shift += XA_CHUNK_SHIFT;
573 return shift + XA_CHUNK_SHIFT;
574 } else if (xa_is_node(head)) {
575 node = xa_to_node(head);
576 shift = node->shift + XA_CHUNK_SHIFT;
580 while (max > max_index(head)) {
583 XA_NODE_BUG_ON(node, shift > BITS_PER_LONG);
584 node = xas_alloc(xas, shift);
589 if (xa_is_value(head))
591 RCU_INIT_POINTER(node->slots[0], head);
593 /* Propagate the aggregated mark info to the new child */
595 if (xa_track_free(xa) && mark == XA_FREE_MARK) {
596 node_mark_all(node, XA_FREE_MARK);
597 if (!xa_marked(xa, XA_FREE_MARK)) {
598 node_clear_mark(node, 0, XA_FREE_MARK);
599 xa_mark_set(xa, XA_FREE_MARK);
601 } else if (xa_marked(xa, mark)) {
602 node_set_mark(node, 0, mark);
604 if (mark == XA_MARK_MAX)
610 * Now that the new node is fully initialised, we can add
613 if (xa_is_node(head)) {
614 xa_to_node(head)->offset = 0;
615 rcu_assign_pointer(xa_to_node(head)->parent, node);
617 head = xa_mk_node(node);
618 rcu_assign_pointer(xa->xa_head, head);
619 xas_update(xas, node);
621 shift += XA_CHUNK_SHIFT;
629 * xas_create() - Create a slot to store an entry in.
630 * @xas: XArray operation state.
631 * @allow_root: %true if we can store the entry in the root directly
633 * Most users will not need to call this function directly, as it is called
634 * by xas_store(). It is useful for doing conditional store operations
635 * (see the xa_cmpxchg() implementation for an example).
637 * Return: If the slot already existed, returns the contents of this slot.
638 * If the slot was newly created, returns %NULL. If it failed to create the
639 * slot, returns %NULL and indicates the error in @xas.
641 static void *xas_create(struct xa_state *xas, bool allow_root)
643 struct xarray *xa = xas->xa;
646 struct xa_node *node = xas->xa_node;
648 unsigned int order = xas->xa_shift;
651 entry = xa_head_locked(xa);
653 if (!entry && xa_zero_busy(xa))
654 entry = XA_ZERO_ENTRY;
655 shift = xas_expand(xas, entry);
658 if (!shift && !allow_root)
659 shift = XA_CHUNK_SHIFT;
660 entry = xa_head_locked(xa);
662 } else if (xas_error(xas)) {
665 unsigned int offset = xas->xa_offset;
668 entry = xa_entry_locked(xa, node, offset);
669 slot = &node->slots[offset];
672 entry = xa_head_locked(xa);
676 while (shift > order) {
677 shift -= XA_CHUNK_SHIFT;
679 node = xas_alloc(xas, shift);
682 if (xa_track_free(xa))
683 node_mark_all(node, XA_FREE_MARK);
684 rcu_assign_pointer(*slot, xa_mk_node(node));
685 } else if (xa_is_node(entry)) {
686 node = xa_to_node(entry);
690 entry = xas_descend(xas, node);
691 slot = &node->slots[xas->xa_offset];
698 * xas_create_range() - Ensure that stores to this range will succeed
699 * @xas: XArray operation state.
701 * Creates all of the slots in the range covered by @xas. Sets @xas to
702 * create single-index entries and positions it at the beginning of the
703 * range. This is for the benefit of users which have not yet been
704 * converted to use multi-index entries.
706 void xas_create_range(struct xa_state *xas)
708 unsigned long index = xas->xa_index;
709 unsigned char shift = xas->xa_shift;
710 unsigned char sibs = xas->xa_sibs;
712 xas->xa_index |= ((sibs + 1UL) << shift) - 1;
713 if (xas_is_node(xas) && xas->xa_node->shift == xas->xa_shift)
714 xas->xa_offset |= sibs;
719 xas_create(xas, true);
722 if (xas->xa_index <= (index | XA_CHUNK_MASK))
724 xas->xa_index -= XA_CHUNK_SIZE;
727 struct xa_node *node = xas->xa_node;
728 if (node->shift >= shift)
730 xas->xa_node = xa_parent_locked(xas->xa, node);
731 xas->xa_offset = node->offset - 1;
732 if (node->offset != 0)
738 xas->xa_shift = shift;
740 xas->xa_index = index;
743 xas->xa_index = index;
747 EXPORT_SYMBOL_GPL(xas_create_range);
749 static void update_node(struct xa_state *xas, struct xa_node *node,
750 int count, int values)
752 if (!node || (!count && !values))
755 node->count += count;
756 node->nr_values += values;
757 XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
758 XA_NODE_BUG_ON(node, node->nr_values > XA_CHUNK_SIZE);
759 xas_update(xas, node);
761 xas_delete_node(xas);
765 * xas_store() - Store this entry in the XArray.
766 * @xas: XArray operation state.
769 * If @xas is operating on a multi-index entry, the entry returned by this
770 * function is essentially meaningless (it may be an internal entry or it
771 * may be %NULL, even if there are non-NULL entries at some of the indices
772 * covered by the range). This is not a problem for any current users,
773 * and can be changed if needed.
775 * Return: The old entry at this index.
777 void *xas_store(struct xa_state *xas, void *entry)
779 struct xa_node *node;
780 void __rcu **slot = &xas->xa->xa_head;
781 unsigned int offset, max;
785 bool value = xa_is_value(entry);
788 bool allow_root = !xa_is_node(entry) && !xa_is_zero(entry);
789 first = xas_create(xas, allow_root);
791 first = xas_load(xas);
794 if (xas_invalid(xas))
797 if (node && (xas->xa_shift < node->shift))
799 if ((first == entry) && !xas->xa_sibs)
803 offset = xas->xa_offset;
804 max = xas->xa_offset + xas->xa_sibs;
806 slot = &node->slots[offset];
808 xas_squash_marks(xas);
815 * Must clear the marks before setting the entry to NULL,
816 * otherwise xas_for_each_marked may find a NULL entry and
817 * stop early. rcu_assign_pointer contains a release barrier
818 * so the mark clearing will appear to happen before the
819 * entry is set to NULL.
821 rcu_assign_pointer(*slot, entry);
822 if (xa_is_node(next) && (!node || node->shift))
823 xas_free_nodes(xas, xa_to_node(next));
826 count += !next - !entry;
827 values += !xa_is_value(first) - !value;
831 if (!xa_is_sibling(entry))
832 entry = xa_mk_sibling(xas->xa_offset);
834 if (offset == XA_CHUNK_MASK)
837 next = xa_entry_locked(xas->xa, node, ++offset);
838 if (!xa_is_sibling(next)) {
839 if (!entry && (offset > max))
846 update_node(xas, node, count, values);
849 EXPORT_SYMBOL_GPL(xas_store);
852 * xas_get_mark() - Returns the state of this mark.
853 * @xas: XArray operation state.
854 * @mark: Mark number.
856 * Return: true if the mark is set, false if the mark is clear or @xas
857 * is in an error state.
859 bool xas_get_mark(const struct xa_state *xas, xa_mark_t mark)
861 if (xas_invalid(xas))
864 return xa_marked(xas->xa, mark);
865 return node_get_mark(xas->xa_node, xas->xa_offset, mark);
867 EXPORT_SYMBOL_GPL(xas_get_mark);
870 * xas_set_mark() - Sets the mark on this entry and its parents.
871 * @xas: XArray operation state.
872 * @mark: Mark number.
874 * Sets the specified mark on this entry, and walks up the tree setting it
875 * on all the ancestor entries. Does nothing if @xas has not been walked to
876 * an entry, or is in an error state.
878 void xas_set_mark(const struct xa_state *xas, xa_mark_t mark)
880 struct xa_node *node = xas->xa_node;
881 unsigned int offset = xas->xa_offset;
883 if (xas_invalid(xas))
887 if (node_set_mark(node, offset, mark))
889 offset = node->offset;
890 node = xa_parent_locked(xas->xa, node);
893 if (!xa_marked(xas->xa, mark))
894 xa_mark_set(xas->xa, mark);
896 EXPORT_SYMBOL_GPL(xas_set_mark);
899 * xas_clear_mark() - Clears the mark on this entry and its parents.
900 * @xas: XArray operation state.
901 * @mark: Mark number.
903 * Clears the specified mark on this entry, and walks back to the head
904 * attempting to clear it on all the ancestor entries. Does nothing if
905 * @xas has not been walked to an entry, or is in an error state.
907 void xas_clear_mark(const struct xa_state *xas, xa_mark_t mark)
909 struct xa_node *node = xas->xa_node;
910 unsigned int offset = xas->xa_offset;
912 if (xas_invalid(xas))
916 if (!node_clear_mark(node, offset, mark))
918 if (node_any_mark(node, mark))
921 offset = node->offset;
922 node = xa_parent_locked(xas->xa, node);
925 if (xa_marked(xas->xa, mark))
926 xa_mark_clear(xas->xa, mark);
928 EXPORT_SYMBOL_GPL(xas_clear_mark);
931 * xas_init_marks() - Initialise all marks for the entry
932 * @xas: Array operations state.
934 * Initialise all marks for the entry specified by @xas. If we're tracking
935 * free entries with a mark, we need to set it on all entries. All other
938 * This implementation is not as efficient as it could be; we may walk
939 * up the tree multiple times.
941 void xas_init_marks(const struct xa_state *xas)
946 if (xa_track_free(xas->xa) && mark == XA_FREE_MARK)
947 xas_set_mark(xas, mark);
949 xas_clear_mark(xas, mark);
950 if (mark == XA_MARK_MAX)
955 EXPORT_SYMBOL_GPL(xas_init_marks);
957 #ifdef CONFIG_XARRAY_MULTI
958 static unsigned int node_get_marks(struct xa_node *node, unsigned int offset)
960 unsigned int marks = 0;
961 xa_mark_t mark = XA_MARK_0;
964 if (node_get_mark(node, offset, mark))
965 marks |= 1 << (__force unsigned int)mark;
966 if (mark == XA_MARK_MAX)
974 static void node_set_marks(struct xa_node *node, unsigned int offset,
975 struct xa_node *child, unsigned int marks)
977 xa_mark_t mark = XA_MARK_0;
980 if (marks & (1 << (__force unsigned int)mark)) {
981 node_set_mark(node, offset, mark);
983 node_mark_all(child, mark);
985 if (mark == XA_MARK_MAX)
992 * xas_split_alloc() - Allocate memory for splitting an entry.
993 * @xas: XArray operation state.
994 * @entry: New entry which will be stored in the array.
995 * @order: Current entry order.
996 * @gfp: Memory allocation flags.
998 * This function should be called before calling xas_split().
999 * If necessary, it will allocate new nodes (and fill them with @entry)
1000 * to prepare for the upcoming split of an entry of @order size into
1001 * entries of the order stored in the @xas.
1003 * Context: May sleep if @gfp flags permit.
1005 void xas_split_alloc(struct xa_state *xas, void *entry, unsigned int order,
1008 unsigned int sibs = (1 << (order % XA_CHUNK_SHIFT)) - 1;
1009 unsigned int mask = xas->xa_sibs;
1011 /* XXX: no support for splitting really large entries yet */
1012 if (WARN_ON(xas->xa_shift + 2 * XA_CHUNK_SHIFT < order))
1014 if (xas->xa_shift + XA_CHUNK_SHIFT > order)
1019 void *sibling = NULL;
1020 struct xa_node *node;
1022 node = kmem_cache_alloc_lru(radix_tree_node_cachep, xas->xa_lru, gfp);
1025 node->array = xas->xa;
1026 for (i = 0; i < XA_CHUNK_SIZE; i++) {
1027 if ((i & mask) == 0) {
1028 RCU_INIT_POINTER(node->slots[i], entry);
1029 sibling = xa_mk_sibling(i);
1031 RCU_INIT_POINTER(node->slots[i], sibling);
1034 RCU_INIT_POINTER(node->parent, xas->xa_alloc);
1035 xas->xa_alloc = node;
1036 } while (sibs-- > 0);
1041 xas_set_err(xas, -ENOMEM);
1043 EXPORT_SYMBOL_GPL(xas_split_alloc);
1046 * xas_split() - Split a multi-index entry into smaller entries.
1047 * @xas: XArray operation state.
1048 * @entry: New entry to store in the array.
1049 * @order: Current entry order.
1051 * The size of the new entries is set in @xas. The value in @entry is
1052 * copied to all the replacement entries.
1054 * Context: Any context. The caller should hold the xa_lock.
1056 void xas_split(struct xa_state *xas, void *entry, unsigned int order)
1058 unsigned int sibs = (1 << (order % XA_CHUNK_SHIFT)) - 1;
1059 unsigned int offset, marks;
1060 struct xa_node *node;
1061 void *curr = xas_load(xas);
1064 node = xas->xa_node;
1068 marks = node_get_marks(node, xas->xa_offset);
1070 offset = xas->xa_offset + sibs;
1072 if (xas->xa_shift < node->shift) {
1073 struct xa_node *child = xas->xa_alloc;
1075 xas->xa_alloc = rcu_dereference_raw(child->parent);
1076 child->shift = node->shift - XA_CHUNK_SHIFT;
1077 child->offset = offset;
1078 child->count = XA_CHUNK_SIZE;
1079 child->nr_values = xa_is_value(entry) ?
1081 RCU_INIT_POINTER(child->parent, node);
1082 node_set_marks(node, offset, child, marks);
1083 rcu_assign_pointer(node->slots[offset],
1085 if (xa_is_value(curr))
1087 xas_update(xas, child);
1089 unsigned int canon = offset - xas->xa_sibs;
1091 node_set_marks(node, canon, NULL, marks);
1092 rcu_assign_pointer(node->slots[canon], entry);
1093 while (offset > canon)
1094 rcu_assign_pointer(node->slots[offset--],
1095 xa_mk_sibling(canon));
1096 values += (xa_is_value(entry) - xa_is_value(curr)) *
1099 } while (offset-- > xas->xa_offset);
1101 node->nr_values += values;
1102 xas_update(xas, node);
1104 EXPORT_SYMBOL_GPL(xas_split);
1108 * xas_pause() - Pause a walk to drop a lock.
1109 * @xas: XArray operation state.
1111 * Some users need to pause a walk and drop the lock they're holding in
1112 * order to yield to a higher priority thread or carry out an operation
1113 * on an entry. Those users should call this function before they drop
1114 * the lock. It resets the @xas to be suitable for the next iteration
1115 * of the loop after the user has reacquired the lock. If most entries
1116 * found during a walk require you to call xas_pause(), the xa_for_each()
1117 * iterator may be more appropriate.
1119 * Note that xas_pause() only works for forward iteration. If a user needs
1120 * to pause a reverse iteration, we will need a xas_pause_rev().
1122 void xas_pause(struct xa_state *xas)
1124 struct xa_node *node = xas->xa_node;
1126 if (xas_invalid(xas))
1129 xas->xa_node = XAS_RESTART;
1131 unsigned long offset = xas->xa_offset;
1132 while (++offset < XA_CHUNK_SIZE) {
1133 if (!xa_is_sibling(xa_entry(xas->xa, node, offset)))
1136 xas->xa_index += (offset - xas->xa_offset) << node->shift;
1137 if (xas->xa_index == 0)
1138 xas->xa_node = XAS_BOUNDS;
1143 EXPORT_SYMBOL_GPL(xas_pause);
1146 * __xas_prev() - Find the previous entry in the XArray.
1147 * @xas: XArray operation state.
1149 * Helper function for xas_prev() which handles all the complex cases
1152 void *__xas_prev(struct xa_state *xas)
1156 if (!xas_frozen(xas->xa_node))
1159 return set_bounds(xas);
1160 if (xas_not_node(xas->xa_node))
1161 return xas_load(xas);
1163 if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node))
1166 while (xas->xa_offset == 255) {
1167 xas->xa_offset = xas->xa_node->offset - 1;
1168 xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1170 return set_bounds(xas);
1174 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1175 if (!xa_is_node(entry))
1178 xas->xa_node = xa_to_node(entry);
1179 xas_set_offset(xas);
1182 EXPORT_SYMBOL_GPL(__xas_prev);
1185 * __xas_next() - Find the next entry in the XArray.
1186 * @xas: XArray operation state.
1188 * Helper function for xas_next() which handles all the complex cases
1191 void *__xas_next(struct xa_state *xas)
1195 if (!xas_frozen(xas->xa_node))
1198 return set_bounds(xas);
1199 if (xas_not_node(xas->xa_node))
1200 return xas_load(xas);
1202 if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node))
1205 while (xas->xa_offset == XA_CHUNK_SIZE) {
1206 xas->xa_offset = xas->xa_node->offset + 1;
1207 xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1209 return set_bounds(xas);
1213 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1214 if (!xa_is_node(entry))
1217 xas->xa_node = xa_to_node(entry);
1218 xas_set_offset(xas);
1221 EXPORT_SYMBOL_GPL(__xas_next);
1224 * xas_find() - Find the next present entry in the XArray.
1225 * @xas: XArray operation state.
1226 * @max: Highest index to return.
1228 * If the @xas has not yet been walked to an entry, return the entry
1229 * which has an index >= xas.xa_index. If it has been walked, the entry
1230 * currently being pointed at has been processed, and so we move to the
1233 * If no entry is found and the array is smaller than @max, the iterator
1234 * is set to the smallest index not yet in the array. This allows @xas
1235 * to be immediately passed to xas_store().
1237 * Return: The entry, if found, otherwise %NULL.
1239 void *xas_find(struct xa_state *xas, unsigned long max)
1243 if (xas_error(xas) || xas->xa_node == XAS_BOUNDS)
1245 if (xas->xa_index > max)
1246 return set_bounds(xas);
1248 if (!xas->xa_node) {
1250 return set_bounds(xas);
1251 } else if (xas->xa_node == XAS_RESTART) {
1252 entry = xas_load(xas);
1253 if (entry || xas_not_node(xas->xa_node))
1255 } else if (!xas->xa_node->shift &&
1256 xas->xa_offset != (xas->xa_index & XA_CHUNK_MASK)) {
1257 xas->xa_offset = ((xas->xa_index - 1) & XA_CHUNK_MASK) + 1;
1260 xas_next_offset(xas);
1262 while (xas->xa_node && (xas->xa_index <= max)) {
1263 if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) {
1264 xas->xa_offset = xas->xa_node->offset + 1;
1265 xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1269 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1270 if (xa_is_node(entry)) {
1271 xas->xa_node = xa_to_node(entry);
1275 if (entry && !xa_is_sibling(entry))
1278 xas_next_offset(xas);
1282 xas->xa_node = XAS_BOUNDS;
1285 EXPORT_SYMBOL_GPL(xas_find);
1288 * xas_find_marked() - Find the next marked entry in the XArray.
1289 * @xas: XArray operation state.
1290 * @max: Highest index to return.
1291 * @mark: Mark number to search for.
1293 * If the @xas has not yet been walked to an entry, return the marked entry
1294 * which has an index >= xas.xa_index. If it has been walked, the entry
1295 * currently being pointed at has been processed, and so we return the
1296 * first marked entry with an index > xas.xa_index.
1298 * If no marked entry is found and the array is smaller than @max, @xas is
1299 * set to the bounds state and xas->xa_index is set to the smallest index
1300 * not yet in the array. This allows @xas to be immediately passed to
1303 * If no entry is found before @max is reached, @xas is set to the restart
1306 * Return: The entry, if found, otherwise %NULL.
1308 void *xas_find_marked(struct xa_state *xas, unsigned long max, xa_mark_t mark)
1310 bool advance = true;
1311 unsigned int offset;
1316 if (xas->xa_index > max)
1319 if (!xas->xa_node) {
1322 } else if (xas_top(xas->xa_node)) {
1324 entry = xa_head(xas->xa);
1325 xas->xa_node = NULL;
1326 if (xas->xa_index > max_index(entry))
1328 if (!xa_is_node(entry)) {
1329 if (xa_marked(xas->xa, mark))
1334 xas->xa_node = xa_to_node(entry);
1335 xas->xa_offset = xas->xa_index >> xas->xa_node->shift;
1338 while (xas->xa_index <= max) {
1339 if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) {
1340 xas->xa_offset = xas->xa_node->offset + 1;
1341 xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1349 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1350 if (xa_is_sibling(entry)) {
1351 xas->xa_offset = xa_to_sibling(entry);
1352 xas_move_index(xas, xas->xa_offset);
1356 offset = xas_find_chunk(xas, advance, mark);
1357 if (offset > xas->xa_offset) {
1359 xas_move_index(xas, offset);
1361 if ((xas->xa_index - 1) >= max)
1363 xas->xa_offset = offset;
1364 if (offset == XA_CHUNK_SIZE)
1368 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1369 if (!entry && !(xa_track_free(xas->xa) && mark == XA_FREE_MARK))
1371 if (!xa_is_node(entry))
1373 xas->xa_node = xa_to_node(entry);
1374 xas_set_offset(xas);
1378 if (xas->xa_index > max)
1380 return set_bounds(xas);
1382 xas->xa_node = XAS_RESTART;
1385 EXPORT_SYMBOL_GPL(xas_find_marked);
1388 * xas_find_conflict() - Find the next present entry in a range.
1389 * @xas: XArray operation state.
1391 * The @xas describes both a range and a position within that range.
1393 * Context: Any context. Expects xa_lock to be held.
1394 * Return: The next entry in the range covered by @xas or %NULL.
1396 void *xas_find_conflict(struct xa_state *xas)
1406 if (xas_top(xas->xa_node)) {
1407 curr = xas_start(xas);
1410 while (xa_is_node(curr)) {
1411 struct xa_node *node = xa_to_node(curr);
1412 curr = xas_descend(xas, node);
1418 if (xas->xa_node->shift > xas->xa_shift)
1422 if (xas->xa_node->shift == xas->xa_shift) {
1423 if ((xas->xa_offset & xas->xa_sibs) == xas->xa_sibs)
1425 } else if (xas->xa_offset == XA_CHUNK_MASK) {
1426 xas->xa_offset = xas->xa_node->offset;
1427 xas->xa_node = xa_parent_locked(xas->xa, xas->xa_node);
1432 curr = xa_entry_locked(xas->xa, xas->xa_node, ++xas->xa_offset);
1433 if (xa_is_sibling(curr))
1435 while (xa_is_node(curr)) {
1436 xas->xa_node = xa_to_node(curr);
1438 curr = xa_entry_locked(xas->xa, xas->xa_node, 0);
1443 xas->xa_offset -= xas->xa_sibs;
1446 EXPORT_SYMBOL_GPL(xas_find_conflict);
1449 * xa_load() - Load an entry from an XArray.
1451 * @index: index into array.
1453 * Context: Any context. Takes and releases the RCU lock.
1454 * Return: The entry at @index in @xa.
1456 void *xa_load(struct xarray *xa, unsigned long index)
1458 XA_STATE(xas, xa, index);
1463 entry = xas_load(&xas);
1464 if (xa_is_zero(entry))
1466 } while (xas_retry(&xas, entry));
1471 EXPORT_SYMBOL(xa_load);
1473 static void *xas_result(struct xa_state *xas, void *curr)
1475 if (xa_is_zero(curr))
1478 curr = xas->xa_node;
1483 * __xa_erase() - Erase this entry from the XArray while locked.
1485 * @index: Index into array.
1487 * After this function returns, loading from @index will return %NULL.
1488 * If the index is part of a multi-index entry, all indices will be erased
1489 * and none of the entries will be part of a multi-index entry.
1491 * Context: Any context. Expects xa_lock to be held on entry.
1492 * Return: The entry which used to be at this index.
1494 void *__xa_erase(struct xarray *xa, unsigned long index)
1496 XA_STATE(xas, xa, index);
1497 return xas_result(&xas, xas_store(&xas, NULL));
1499 EXPORT_SYMBOL(__xa_erase);
1502 * xa_erase() - Erase this entry from the XArray.
1504 * @index: Index of entry.
1506 * After this function returns, loading from @index will return %NULL.
1507 * If the index is part of a multi-index entry, all indices will be erased
1508 * and none of the entries will be part of a multi-index entry.
1510 * Context: Any context. Takes and releases the xa_lock.
1511 * Return: The entry which used to be at this index.
1513 void *xa_erase(struct xarray *xa, unsigned long index)
1518 entry = __xa_erase(xa, index);
1523 EXPORT_SYMBOL(xa_erase);
1526 * __xa_store() - Store this entry in the XArray.
1528 * @index: Index into array.
1529 * @entry: New entry.
1530 * @gfp: Memory allocation flags.
1532 * You must already be holding the xa_lock when calling this function.
1533 * It will drop the lock if needed to allocate memory, and then reacquire
1536 * Context: Any context. Expects xa_lock to be held on entry. May
1537 * release and reacquire xa_lock if @gfp flags permit.
1538 * Return: The old entry at this index or xa_err() if an error happened.
1540 void *__xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
1542 XA_STATE(xas, xa, index);
1545 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1546 return XA_ERROR(-EINVAL);
1547 if (xa_track_free(xa) && !entry)
1548 entry = XA_ZERO_ENTRY;
1551 curr = xas_store(&xas, entry);
1552 if (xa_track_free(xa))
1553 xas_clear_mark(&xas, XA_FREE_MARK);
1554 } while (__xas_nomem(&xas, gfp));
1556 return xas_result(&xas, curr);
1558 EXPORT_SYMBOL(__xa_store);
1561 * xa_store() - Store this entry in the XArray.
1563 * @index: Index into array.
1564 * @entry: New entry.
1565 * @gfp: Memory allocation flags.
1567 * After this function returns, loads from this index will return @entry.
1568 * Storing into an existing multi-index entry updates the entry of every index.
1569 * The marks associated with @index are unaffected unless @entry is %NULL.
1571 * Context: Any context. Takes and releases the xa_lock.
1572 * May sleep if the @gfp flags permit.
1573 * Return: The old entry at this index on success, xa_err(-EINVAL) if @entry
1574 * cannot be stored in an XArray, or xa_err(-ENOMEM) if memory allocation
1577 void *xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
1582 curr = __xa_store(xa, index, entry, gfp);
1587 EXPORT_SYMBOL(xa_store);
1590 * __xa_cmpxchg() - Store this entry in the XArray.
1592 * @index: Index into array.
1593 * @old: Old value to test against.
1594 * @entry: New entry.
1595 * @gfp: Memory allocation flags.
1597 * You must already be holding the xa_lock when calling this function.
1598 * It will drop the lock if needed to allocate memory, and then reacquire
1601 * Context: Any context. Expects xa_lock to be held on entry. May
1602 * release and reacquire xa_lock if @gfp flags permit.
1603 * Return: The old entry at this index or xa_err() if an error happened.
1605 void *__xa_cmpxchg(struct xarray *xa, unsigned long index,
1606 void *old, void *entry, gfp_t gfp)
1608 XA_STATE(xas, xa, index);
1611 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1612 return XA_ERROR(-EINVAL);
1615 curr = xas_load(&xas);
1617 xas_store(&xas, entry);
1618 if (xa_track_free(xa) && entry && !curr)
1619 xas_clear_mark(&xas, XA_FREE_MARK);
1621 } while (__xas_nomem(&xas, gfp));
1623 return xas_result(&xas, curr);
1625 EXPORT_SYMBOL(__xa_cmpxchg);
1628 * __xa_insert() - Store this entry in the XArray if no entry is present.
1630 * @index: Index into array.
1631 * @entry: New entry.
1632 * @gfp: Memory allocation flags.
1634 * Inserting a NULL entry will store a reserved entry (like xa_reserve())
1635 * if no entry is present. Inserting will fail if a reserved entry is
1636 * present, even though loading from this index will return NULL.
1638 * Context: Any context. Expects xa_lock to be held on entry. May
1639 * release and reacquire xa_lock if @gfp flags permit.
1640 * Return: 0 if the store succeeded. -EBUSY if another entry was present.
1641 * -ENOMEM if memory could not be allocated.
1643 int __xa_insert(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
1645 XA_STATE(xas, xa, index);
1648 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1651 entry = XA_ZERO_ENTRY;
1654 curr = xas_load(&xas);
1656 xas_store(&xas, entry);
1657 if (xa_track_free(xa))
1658 xas_clear_mark(&xas, XA_FREE_MARK);
1660 xas_set_err(&xas, -EBUSY);
1662 } while (__xas_nomem(&xas, gfp));
1664 return xas_error(&xas);
1666 EXPORT_SYMBOL(__xa_insert);
1668 #ifdef CONFIG_XARRAY_MULTI
1669 static void xas_set_range(struct xa_state *xas, unsigned long first,
1672 unsigned int shift = 0;
1673 unsigned long sibs = last - first;
1674 unsigned int offset = XA_CHUNK_MASK;
1676 xas_set(xas, first);
1678 while ((first & XA_CHUNK_MASK) == 0) {
1679 if (sibs < XA_CHUNK_MASK)
1681 if ((sibs == XA_CHUNK_MASK) && (offset < XA_CHUNK_MASK))
1683 shift += XA_CHUNK_SHIFT;
1684 if (offset == XA_CHUNK_MASK)
1685 offset = sibs & XA_CHUNK_MASK;
1686 sibs >>= XA_CHUNK_SHIFT;
1687 first >>= XA_CHUNK_SHIFT;
1690 offset = first & XA_CHUNK_MASK;
1691 if (offset + sibs > XA_CHUNK_MASK)
1692 sibs = XA_CHUNK_MASK - offset;
1693 if ((((first + sibs + 1) << shift) - 1) > last)
1696 xas->xa_shift = shift;
1697 xas->xa_sibs = sibs;
1701 * xa_store_range() - Store this entry at a range of indices in the XArray.
1703 * @first: First index to affect.
1704 * @last: Last index to affect.
1705 * @entry: New entry.
1706 * @gfp: Memory allocation flags.
1708 * After this function returns, loads from any index between @first and @last,
1709 * inclusive will return @entry.
1710 * Storing into an existing multi-index entry updates the entry of every index.
1711 * The marks associated with @index are unaffected unless @entry is %NULL.
1713 * Context: Process context. Takes and releases the xa_lock. May sleep
1714 * if the @gfp flags permit.
1715 * Return: %NULL on success, xa_err(-EINVAL) if @entry cannot be stored in
1716 * an XArray, or xa_err(-ENOMEM) if memory allocation failed.
1718 void *xa_store_range(struct xarray *xa, unsigned long first,
1719 unsigned long last, void *entry, gfp_t gfp)
1721 XA_STATE(xas, xa, 0);
1723 if (WARN_ON_ONCE(xa_is_internal(entry)))
1724 return XA_ERROR(-EINVAL);
1726 return XA_ERROR(-EINVAL);
1731 unsigned int order = BITS_PER_LONG;
1733 order = __ffs(last + 1);
1734 xas_set_order(&xas, last, order);
1735 xas_create(&xas, true);
1736 if (xas_error(&xas))
1740 xas_set_range(&xas, first, last);
1741 xas_store(&xas, entry);
1742 if (xas_error(&xas))
1744 first += xas_size(&xas);
1745 } while (first <= last);
1748 } while (xas_nomem(&xas, gfp));
1750 return xas_result(&xas, NULL);
1752 EXPORT_SYMBOL(xa_store_range);
1755 * xa_get_order() - Get the order of an entry.
1757 * @index: Index of the entry.
1759 * Return: A number between 0 and 63 indicating the order of the entry.
1761 int xa_get_order(struct xarray *xa, unsigned long index)
1763 XA_STATE(xas, xa, index);
1768 entry = xas_load(&xas);
1777 unsigned int slot = xas.xa_offset + (1 << order);
1779 if (slot >= XA_CHUNK_SIZE)
1781 if (!xa_is_sibling(xas.xa_node->slots[slot]))
1786 order += xas.xa_node->shift;
1792 EXPORT_SYMBOL(xa_get_order);
1793 #endif /* CONFIG_XARRAY_MULTI */
1796 * __xa_alloc() - Find somewhere to store this entry in the XArray.
1798 * @id: Pointer to ID.
1799 * @limit: Range for allocated ID.
1800 * @entry: New entry.
1801 * @gfp: Memory allocation flags.
1803 * Finds an empty entry in @xa between @limit.min and @limit.max,
1804 * stores the index into the @id pointer, then stores the entry at
1805 * that index. A concurrent lookup will not see an uninitialised @id.
1807 * Context: Any context. Expects xa_lock to be held on entry. May
1808 * release and reacquire xa_lock if @gfp flags permit.
1809 * Return: 0 on success, -ENOMEM if memory could not be allocated or
1810 * -EBUSY if there are no free entries in @limit.
1812 int __xa_alloc(struct xarray *xa, u32 *id, void *entry,
1813 struct xa_limit limit, gfp_t gfp)
1815 XA_STATE(xas, xa, 0);
1817 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1819 if (WARN_ON_ONCE(!xa_track_free(xa)))
1823 entry = XA_ZERO_ENTRY;
1826 xas.xa_index = limit.min;
1827 xas_find_marked(&xas, limit.max, XA_FREE_MARK);
1828 if (xas.xa_node == XAS_RESTART)
1829 xas_set_err(&xas, -EBUSY);
1832 xas_store(&xas, entry);
1833 xas_clear_mark(&xas, XA_FREE_MARK);
1834 } while (__xas_nomem(&xas, gfp));
1836 return xas_error(&xas);
1838 EXPORT_SYMBOL(__xa_alloc);
1841 * __xa_alloc_cyclic() - Find somewhere to store this entry in the XArray.
1843 * @id: Pointer to ID.
1844 * @entry: New entry.
1845 * @limit: Range of allocated ID.
1846 * @next: Pointer to next ID to allocate.
1847 * @gfp: Memory allocation flags.
1849 * Finds an empty entry in @xa between @limit.min and @limit.max,
1850 * stores the index into the @id pointer, then stores the entry at
1851 * that index. A concurrent lookup will not see an uninitialised @id.
1852 * The search for an empty entry will start at @next and will wrap
1853 * around if necessary.
1855 * Context: Any context. Expects xa_lock to be held on entry. May
1856 * release and reacquire xa_lock if @gfp flags permit.
1857 * Return: 0 if the allocation succeeded without wrapping. 1 if the
1858 * allocation succeeded after wrapping, -ENOMEM if memory could not be
1859 * allocated or -EBUSY if there are no free entries in @limit.
1861 int __xa_alloc_cyclic(struct xarray *xa, u32 *id, void *entry,
1862 struct xa_limit limit, u32 *next, gfp_t gfp)
1864 u32 min = limit.min;
1867 limit.min = max(min, *next);
1868 ret = __xa_alloc(xa, id, entry, limit, gfp);
1869 if ((xa->xa_flags & XA_FLAGS_ALLOC_WRAPPED) && ret == 0) {
1870 xa->xa_flags &= ~XA_FLAGS_ALLOC_WRAPPED;
1874 if (ret < 0 && limit.min > min) {
1876 ret = __xa_alloc(xa, id, entry, limit, gfp);
1884 xa->xa_flags |= XA_FLAGS_ALLOC_WRAPPED;
1888 EXPORT_SYMBOL(__xa_alloc_cyclic);
1891 * __xa_set_mark() - Set this mark on this entry while locked.
1893 * @index: Index of entry.
1894 * @mark: Mark number.
1896 * Attempting to set a mark on a %NULL entry does not succeed.
1898 * Context: Any context. Expects xa_lock to be held on entry.
1900 void __xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1902 XA_STATE(xas, xa, index);
1903 void *entry = xas_load(&xas);
1906 xas_set_mark(&xas, mark);
1908 EXPORT_SYMBOL(__xa_set_mark);
1911 * __xa_clear_mark() - Clear this mark on this entry while locked.
1913 * @index: Index of entry.
1914 * @mark: Mark number.
1916 * Context: Any context. Expects xa_lock to be held on entry.
1918 void __xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1920 XA_STATE(xas, xa, index);
1921 void *entry = xas_load(&xas);
1924 xas_clear_mark(&xas, mark);
1926 EXPORT_SYMBOL(__xa_clear_mark);
1929 * xa_get_mark() - Inquire whether this mark is set on this entry.
1931 * @index: Index of entry.
1932 * @mark: Mark number.
1934 * This function uses the RCU read lock, so the result may be out of date
1935 * by the time it returns. If you need the result to be stable, use a lock.
1937 * Context: Any context. Takes and releases the RCU lock.
1938 * Return: True if the entry at @index has this mark set, false if it doesn't.
1940 bool xa_get_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1942 XA_STATE(xas, xa, index);
1946 entry = xas_start(&xas);
1947 while (xas_get_mark(&xas, mark)) {
1948 if (!xa_is_node(entry))
1950 entry = xas_descend(&xas, xa_to_node(entry));
1958 EXPORT_SYMBOL(xa_get_mark);
1961 * xa_set_mark() - Set this mark on this entry.
1963 * @index: Index of entry.
1964 * @mark: Mark number.
1966 * Attempting to set a mark on a %NULL entry does not succeed.
1968 * Context: Process context. Takes and releases the xa_lock.
1970 void xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1973 __xa_set_mark(xa, index, mark);
1976 EXPORT_SYMBOL(xa_set_mark);
1979 * xa_clear_mark() - Clear this mark on this entry.
1981 * @index: Index of entry.
1982 * @mark: Mark number.
1984 * Clearing a mark always succeeds.
1986 * Context: Process context. Takes and releases the xa_lock.
1988 void xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1991 __xa_clear_mark(xa, index, mark);
1994 EXPORT_SYMBOL(xa_clear_mark);
1997 * xa_find() - Search the XArray for an entry.
1999 * @indexp: Pointer to an index.
2000 * @max: Maximum index to search to.
2001 * @filter: Selection criterion.
2003 * Finds the entry in @xa which matches the @filter, and has the lowest
2004 * index that is at least @indexp and no more than @max.
2005 * If an entry is found, @indexp is updated to be the index of the entry.
2006 * This function is protected by the RCU read lock, so it may not find
2007 * entries which are being simultaneously added. It will not return an
2008 * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
2010 * Context: Any context. Takes and releases the RCU lock.
2011 * Return: The entry, if found, otherwise %NULL.
2013 void *xa_find(struct xarray *xa, unsigned long *indexp,
2014 unsigned long max, xa_mark_t filter)
2016 XA_STATE(xas, xa, *indexp);
2021 if ((__force unsigned int)filter < XA_MAX_MARKS)
2022 entry = xas_find_marked(&xas, max, filter);
2024 entry = xas_find(&xas, max);
2025 } while (xas_retry(&xas, entry));
2029 *indexp = xas.xa_index;
2032 EXPORT_SYMBOL(xa_find);
2034 static bool xas_sibling(struct xa_state *xas)
2036 struct xa_node *node = xas->xa_node;
2039 if (!IS_ENABLED(CONFIG_XARRAY_MULTI) || !node)
2041 mask = (XA_CHUNK_SIZE << node->shift) - 1;
2042 return (xas->xa_index & mask) >
2043 ((unsigned long)xas->xa_offset << node->shift);
2047 * xa_find_after() - Search the XArray for a present entry.
2049 * @indexp: Pointer to an index.
2050 * @max: Maximum index to search to.
2051 * @filter: Selection criterion.
2053 * Finds the entry in @xa which matches the @filter and has the lowest
2054 * index that is above @indexp and no more than @max.
2055 * If an entry is found, @indexp is updated to be the index of the entry.
2056 * This function is protected by the RCU read lock, so it may miss entries
2057 * which are being simultaneously added. It will not return an
2058 * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
2060 * Context: Any context. Takes and releases the RCU lock.
2061 * Return: The pointer, if found, otherwise %NULL.
2063 void *xa_find_after(struct xarray *xa, unsigned long *indexp,
2064 unsigned long max, xa_mark_t filter)
2066 XA_STATE(xas, xa, *indexp + 1);
2069 if (xas.xa_index == 0)
2074 if ((__force unsigned int)filter < XA_MAX_MARKS)
2075 entry = xas_find_marked(&xas, max, filter);
2077 entry = xas_find(&xas, max);
2079 if (xas_invalid(&xas))
2081 if (xas_sibling(&xas))
2083 if (!xas_retry(&xas, entry))
2089 *indexp = xas.xa_index;
2092 EXPORT_SYMBOL(xa_find_after);
2094 static unsigned int xas_extract_present(struct xa_state *xas, void **dst,
2095 unsigned long max, unsigned int n)
2101 xas_for_each(xas, entry, max) {
2102 if (xas_retry(xas, entry))
2113 static unsigned int xas_extract_marked(struct xa_state *xas, void **dst,
2114 unsigned long max, unsigned int n, xa_mark_t mark)
2120 xas_for_each_marked(xas, entry, max, mark) {
2121 if (xas_retry(xas, entry))
2133 * xa_extract() - Copy selected entries from the XArray into a normal array.
2134 * @xa: The source XArray to copy from.
2135 * @dst: The buffer to copy entries into.
2136 * @start: The first index in the XArray eligible to be selected.
2137 * @max: The last index in the XArray eligible to be selected.
2138 * @n: The maximum number of entries to copy.
2139 * @filter: Selection criterion.
2141 * Copies up to @n entries that match @filter from the XArray. The
2142 * copied entries will have indices between @start and @max, inclusive.
2144 * The @filter may be an XArray mark value, in which case entries which are
2145 * marked with that mark will be copied. It may also be %XA_PRESENT, in
2146 * which case all entries which are not %NULL will be copied.
2148 * The entries returned may not represent a snapshot of the XArray at a
2149 * moment in time. For example, if another thread stores to index 5, then
2150 * index 10, calling xa_extract() may return the old contents of index 5
2151 * and the new contents of index 10. Indices not modified while this
2152 * function is running will not be skipped.
2154 * If you need stronger guarantees, holding the xa_lock across calls to this
2155 * function will prevent concurrent modification.
2157 * Context: Any context. Takes and releases the RCU lock.
2158 * Return: The number of entries copied.
2160 unsigned int xa_extract(struct xarray *xa, void **dst, unsigned long start,
2161 unsigned long max, unsigned int n, xa_mark_t filter)
2163 XA_STATE(xas, xa, start);
2168 if ((__force unsigned int)filter < XA_MAX_MARKS)
2169 return xas_extract_marked(&xas, dst, max, n, filter);
2170 return xas_extract_present(&xas, dst, max, n);
2172 EXPORT_SYMBOL(xa_extract);
2175 * xa_delete_node() - Private interface for workingset code.
2176 * @node: Node to be removed from the tree.
2177 * @update: Function to call to update ancestor nodes.
2179 * Context: xa_lock must be held on entry and will not be released.
2181 void xa_delete_node(struct xa_node *node, xa_update_node_t update)
2183 struct xa_state xas = {
2185 .xa_index = (unsigned long)node->offset <<
2186 (node->shift + XA_CHUNK_SHIFT),
2187 .xa_shift = node->shift + XA_CHUNK_SHIFT,
2188 .xa_offset = node->offset,
2189 .xa_node = xa_parent_locked(node->array, node),
2190 .xa_update = update,
2193 xas_store(&xas, NULL);
2195 EXPORT_SYMBOL_GPL(xa_delete_node); /* For the benefit of the test suite */
2198 * xa_destroy() - Free all internal data structures.
2201 * After calling this function, the XArray is empty and has freed all memory
2202 * allocated for its internal data structures. You are responsible for
2203 * freeing the objects referenced by the XArray.
2205 * Context: Any context. Takes and releases the xa_lock, interrupt-safe.
2207 void xa_destroy(struct xarray *xa)
2209 XA_STATE(xas, xa, 0);
2210 unsigned long flags;
2214 xas_lock_irqsave(&xas, flags);
2215 entry = xa_head_locked(xa);
2216 RCU_INIT_POINTER(xa->xa_head, NULL);
2217 xas_init_marks(&xas);
2218 if (xa_zero_busy(xa))
2219 xa_mark_clear(xa, XA_FREE_MARK);
2220 /* lockdep checks we're still holding the lock in xas_free_nodes() */
2221 if (xa_is_node(entry))
2222 xas_free_nodes(&xas, xa_to_node(entry));
2223 xas_unlock_irqrestore(&xas, flags);
2225 EXPORT_SYMBOL(xa_destroy);
2228 void xa_dump_node(const struct xa_node *node)
2234 if ((unsigned long)node & 3) {
2235 pr_cont("node %px\n", node);
2239 pr_cont("node %px %s %d parent %px shift %d count %d values %d "
2240 "array %px list %px %px marks",
2241 node, node->parent ? "offset" : "max", node->offset,
2242 node->parent, node->shift, node->count, node->nr_values,
2243 node->array, node->private_list.prev, node->private_list.next);
2244 for (i = 0; i < XA_MAX_MARKS; i++)
2245 for (j = 0; j < XA_MARK_LONGS; j++)
2246 pr_cont(" %lx", node->marks[i][j]);
2250 void xa_dump_index(unsigned long index, unsigned int shift)
2253 pr_info("%lu: ", index);
2254 else if (shift >= BITS_PER_LONG)
2255 pr_info("0-%lu: ", ~0UL);
2257 pr_info("%lu-%lu: ", index, index | ((1UL << shift) - 1));
2260 void xa_dump_entry(const void *entry, unsigned long index, unsigned long shift)
2265 xa_dump_index(index, shift);
2267 if (xa_is_node(entry)) {
2269 pr_cont("%px\n", entry);
2272 struct xa_node *node = xa_to_node(entry);
2274 for (i = 0; i < XA_CHUNK_SIZE; i++)
2275 xa_dump_entry(node->slots[i],
2276 index + (i << node->shift), node->shift);
2278 } else if (xa_is_value(entry))
2279 pr_cont("value %ld (0x%lx) [%px]\n", xa_to_value(entry),
2280 xa_to_value(entry), entry);
2281 else if (!xa_is_internal(entry))
2282 pr_cont("%px\n", entry);
2283 else if (xa_is_retry(entry))
2284 pr_cont("retry (%ld)\n", xa_to_internal(entry));
2285 else if (xa_is_sibling(entry))
2286 pr_cont("sibling (slot %ld)\n", xa_to_sibling(entry));
2287 else if (xa_is_zero(entry))
2288 pr_cont("zero (%ld)\n", xa_to_internal(entry));
2290 pr_cont("UNKNOWN ENTRY (%px)\n", entry);
2293 void xa_dump(const struct xarray *xa)
2295 void *entry = xa->xa_head;
2296 unsigned int shift = 0;
2298 pr_info("xarray: %px head %px flags %x marks %d %d %d\n", xa, entry,
2299 xa->xa_flags, xa_marked(xa, XA_MARK_0),
2300 xa_marked(xa, XA_MARK_1), xa_marked(xa, XA_MARK_2));
2301 if (xa_is_node(entry))
2302 shift = xa_to_node(entry)->shift + XA_CHUNK_SHIFT;
2303 xa_dump_entry(entry, 0, shift);