1 // SPDX-License-Identifier: GPL-2.0+
3 * XArray implementation
4 * Copyright (c) 2017-2018 Microsoft Corporation
5 * Copyright (c) 2018-2020 Oracle
6 * Author: Matthew Wilcox <willy@infradead.org>
9 #include <linux/bitmap.h>
10 #include <linux/export.h>
11 #include <linux/list.h>
12 #include <linux/slab.h>
13 #include <linux/xarray.h>
16 * Coding conventions in this file:
18 * @xa is used to refer to the entire xarray.
19 * @xas is the 'xarray operation state'. It may be either a pointer to
20 * an xa_state, or an xa_state stored on the stack. This is an unfortunate
22 * @index is the index of the entry being operated on
23 * @mark is an xa_mark_t; a small number indicating one of the mark bits.
24 * @node refers to an xa_node; usually the primary one being operated on by
26 * @offset is the index into the slots array inside an xa_node.
27 * @parent refers to the @xa_node closer to the head than @node.
28 * @entry refers to something stored in a slot in the xarray
31 static inline unsigned int xa_lock_type(const struct xarray *xa)
33 return (__force unsigned int)xa->xa_flags & 3;
36 static inline void xas_lock_type(struct xa_state *xas, unsigned int lock_type)
38 if (lock_type == XA_LOCK_IRQ)
40 else if (lock_type == XA_LOCK_BH)
46 static inline void xas_unlock_type(struct xa_state *xas, unsigned int lock_type)
48 if (lock_type == XA_LOCK_IRQ)
50 else if (lock_type == XA_LOCK_BH)
56 static inline bool xa_track_free(const struct xarray *xa)
58 return xa->xa_flags & XA_FLAGS_TRACK_FREE;
61 static inline bool xa_zero_busy(const struct xarray *xa)
63 return xa->xa_flags & XA_FLAGS_ZERO_BUSY;
66 static inline void xa_mark_set(struct xarray *xa, xa_mark_t mark)
68 if (!(xa->xa_flags & XA_FLAGS_MARK(mark)))
69 xa->xa_flags |= XA_FLAGS_MARK(mark);
72 static inline void xa_mark_clear(struct xarray *xa, xa_mark_t mark)
74 if (xa->xa_flags & XA_FLAGS_MARK(mark))
75 xa->xa_flags &= ~(XA_FLAGS_MARK(mark));
78 static inline unsigned long *node_marks(struct xa_node *node, xa_mark_t mark)
80 return node->marks[(__force unsigned)mark];
83 static inline bool node_get_mark(struct xa_node *node,
84 unsigned int offset, xa_mark_t mark)
86 return test_bit(offset, node_marks(node, mark));
89 /* returns true if the bit was set */
90 static inline bool node_set_mark(struct xa_node *node, unsigned int offset,
93 return __test_and_set_bit(offset, node_marks(node, mark));
96 /* returns true if the bit was set */
97 static inline bool node_clear_mark(struct xa_node *node, unsigned int offset,
100 return __test_and_clear_bit(offset, node_marks(node, mark));
103 static inline bool node_any_mark(struct xa_node *node, xa_mark_t mark)
105 return !bitmap_empty(node_marks(node, mark), XA_CHUNK_SIZE);
108 static inline void node_mark_all(struct xa_node *node, xa_mark_t mark)
110 bitmap_fill(node_marks(node, mark), XA_CHUNK_SIZE);
113 #define mark_inc(mark) do { \
114 mark = (__force xa_mark_t)((__force unsigned)(mark) + 1); \
118 * xas_squash_marks() - Merge all marks to the first entry
119 * @xas: Array operation state.
121 * Set a mark on the first entry if any entry has it set. Clear marks on
122 * all sibling entries.
124 static void xas_squash_marks(const struct xa_state *xas)
126 unsigned int mark = 0;
127 unsigned int limit = xas->xa_offset + xas->xa_sibs + 1;
133 unsigned long *marks = xas->xa_node->marks[mark];
134 if (find_next_bit(marks, limit, xas->xa_offset + 1) == limit)
136 __set_bit(xas->xa_offset, marks);
137 bitmap_clear(marks, xas->xa_offset + 1, xas->xa_sibs);
138 } while (mark++ != (__force unsigned)XA_MARK_MAX);
141 /* extracts the offset within this node from the index */
142 static unsigned int get_offset(unsigned long index, struct xa_node *node)
144 return (index >> node->shift) & XA_CHUNK_MASK;
147 static void xas_set_offset(struct xa_state *xas)
149 xas->xa_offset = get_offset(xas->xa_index, xas->xa_node);
152 /* move the index either forwards (find) or backwards (sibling slot) */
153 static void xas_move_index(struct xa_state *xas, unsigned long offset)
155 unsigned int shift = xas->xa_node->shift;
156 xas->xa_index &= ~XA_CHUNK_MASK << shift;
157 xas->xa_index += offset << shift;
160 static void xas_advance(struct xa_state *xas)
163 xas_move_index(xas, xas->xa_offset);
166 static void *set_bounds(struct xa_state *xas)
168 xas->xa_node = XAS_BOUNDS;
173 * Starts a walk. If the @xas is already valid, we assume that it's on
174 * the right path and just return where we've got to. If we're in an
175 * error state, return NULL. If the index is outside the current scope
176 * of the xarray, return NULL without changing @xas->xa_node. Otherwise
177 * set @xas->xa_node to NULL and return the current head of the array.
179 static void *xas_start(struct xa_state *xas)
184 return xas_reload(xas);
188 entry = xa_head(xas->xa);
189 if (!xa_is_node(entry)) {
191 return set_bounds(xas);
193 if ((xas->xa_index >> xa_to_node(entry)->shift) > XA_CHUNK_MASK)
194 return set_bounds(xas);
201 static void *xas_descend(struct xa_state *xas, struct xa_node *node)
203 unsigned int offset = get_offset(xas->xa_index, node);
204 void *entry = xa_entry(xas->xa, node, offset);
207 if (xa_is_sibling(entry)) {
208 offset = xa_to_sibling(entry);
209 entry = xa_entry(xas->xa, node, offset);
212 xas->xa_offset = offset;
217 * xas_load() - Load an entry from the XArray (advanced).
218 * @xas: XArray operation state.
220 * Usually walks the @xas to the appropriate state to load the entry
221 * stored at xa_index. However, it will do nothing and return %NULL if
222 * @xas is in an error state. xas_load() will never expand the tree.
224 * If the xa_state is set up to operate on a multi-index entry, xas_load()
225 * may return %NULL or an internal entry, even if there are entries
226 * present within the range specified by @xas.
228 * Context: Any context. The caller should hold the xa_lock or the RCU lock.
229 * Return: Usually an entry in the XArray, but see description for exceptions.
231 void *xas_load(struct xa_state *xas)
233 void *entry = xas_start(xas);
235 while (xa_is_node(entry)) {
236 struct xa_node *node = xa_to_node(entry);
238 if (xas->xa_shift > node->shift)
240 entry = xas_descend(xas, node);
241 if (node->shift == 0)
246 EXPORT_SYMBOL_GPL(xas_load);
248 /* Move the radix tree node cache here */
249 extern struct kmem_cache *radix_tree_node_cachep;
250 extern void radix_tree_node_rcu_free(struct rcu_head *head);
252 #define XA_RCU_FREE ((struct xarray *)1)
254 static void xa_node_free(struct xa_node *node)
256 XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
257 node->array = XA_RCU_FREE;
258 call_rcu(&node->rcu_head, radix_tree_node_rcu_free);
262 * xas_destroy() - Free any resources allocated during the XArray operation.
263 * @xas: XArray operation state.
265 * This function is now internal-only.
267 static void xas_destroy(struct xa_state *xas)
269 struct xa_node *node = xas->xa_alloc;
273 XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
274 kmem_cache_free(radix_tree_node_cachep, node);
275 xas->xa_alloc = NULL;
279 * xas_nomem() - Allocate memory if needed.
280 * @xas: XArray operation state.
281 * @gfp: Memory allocation flags.
283 * If we need to add new nodes to the XArray, we try to allocate memory
284 * with GFP_NOWAIT while holding the lock, which will usually succeed.
285 * If it fails, @xas is flagged as needing memory to continue. The caller
286 * should drop the lock and call xas_nomem(). If xas_nomem() succeeds,
287 * the caller should retry the operation.
289 * Forward progress is guaranteed as one node is allocated here and
290 * stored in the xa_state where it will be found by xas_alloc(). More
291 * nodes will likely be found in the slab allocator, but we do not tie
294 * Return: true if memory was needed, and was successfully allocated.
296 bool xas_nomem(struct xa_state *xas, gfp_t gfp)
298 if (xas->xa_node != XA_ERROR(-ENOMEM)) {
302 if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT)
303 gfp |= __GFP_ACCOUNT;
304 xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp);
307 XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list));
308 xas->xa_node = XAS_RESTART;
311 EXPORT_SYMBOL_GPL(xas_nomem);
314 * __xas_nomem() - Drop locks and allocate memory if needed.
315 * @xas: XArray operation state.
316 * @gfp: Memory allocation flags.
318 * Internal variant of xas_nomem().
320 * Return: true if memory was needed, and was successfully allocated.
322 static bool __xas_nomem(struct xa_state *xas, gfp_t gfp)
323 __must_hold(xas->xa->xa_lock)
325 unsigned int lock_type = xa_lock_type(xas->xa);
327 if (xas->xa_node != XA_ERROR(-ENOMEM)) {
331 if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT)
332 gfp |= __GFP_ACCOUNT;
333 if (gfpflags_allow_blocking(gfp)) {
334 xas_unlock_type(xas, lock_type);
335 xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp);
336 xas_lock_type(xas, lock_type);
338 xas->xa_alloc = kmem_cache_alloc(radix_tree_node_cachep, gfp);
342 XA_NODE_BUG_ON(xas->xa_alloc, !list_empty(&xas->xa_alloc->private_list));
343 xas->xa_node = XAS_RESTART;
347 static void xas_update(struct xa_state *xas, struct xa_node *node)
350 xas->xa_update(node);
352 XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
355 static void *xas_alloc(struct xa_state *xas, unsigned int shift)
357 struct xa_node *parent = xas->xa_node;
358 struct xa_node *node = xas->xa_alloc;
360 if (xas_invalid(xas))
364 xas->xa_alloc = NULL;
366 gfp_t gfp = GFP_NOWAIT | __GFP_NOWARN;
368 if (xas->xa->xa_flags & XA_FLAGS_ACCOUNT)
369 gfp |= __GFP_ACCOUNT;
371 node = kmem_cache_alloc(radix_tree_node_cachep, gfp);
373 xas_set_err(xas, -ENOMEM);
379 node->offset = xas->xa_offset;
381 XA_NODE_BUG_ON(node, parent->count > XA_CHUNK_SIZE);
382 xas_update(xas, parent);
384 XA_NODE_BUG_ON(node, shift > BITS_PER_LONG);
385 XA_NODE_BUG_ON(node, !list_empty(&node->private_list));
389 RCU_INIT_POINTER(node->parent, xas->xa_node);
390 node->array = xas->xa;
395 #ifdef CONFIG_XARRAY_MULTI
396 /* Returns the number of indices covered by a given xa_state */
397 static unsigned long xas_size(const struct xa_state *xas)
399 return (xas->xa_sibs + 1UL) << xas->xa_shift;
404 * Use this to calculate the maximum index that will need to be created
405 * in order to add the entry described by @xas. Because we cannot store a
406 * multiple-index entry at index 0, the calculation is a little more complex
407 * than you might expect.
409 static unsigned long xas_max(struct xa_state *xas)
411 unsigned long max = xas->xa_index;
413 #ifdef CONFIG_XARRAY_MULTI
414 if (xas->xa_shift || xas->xa_sibs) {
415 unsigned long mask = xas_size(xas) - 1;
425 /* The maximum index that can be contained in the array without expanding it */
426 static unsigned long max_index(void *entry)
428 if (!xa_is_node(entry))
430 return (XA_CHUNK_SIZE << xa_to_node(entry)->shift) - 1;
433 static void xas_shrink(struct xa_state *xas)
435 struct xarray *xa = xas->xa;
436 struct xa_node *node = xas->xa_node;
441 XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
442 if (node->count != 1)
444 entry = xa_entry_locked(xa, node, 0);
447 if (!xa_is_node(entry) && node->shift)
449 if (xa_is_zero(entry) && xa_zero_busy(xa))
451 xas->xa_node = XAS_BOUNDS;
453 RCU_INIT_POINTER(xa->xa_head, entry);
454 if (xa_track_free(xa) && !node_get_mark(node, 0, XA_FREE_MARK))
455 xa_mark_clear(xa, XA_FREE_MARK);
459 if (!xa_is_node(entry))
460 RCU_INIT_POINTER(node->slots[0], XA_RETRY_ENTRY);
461 xas_update(xas, node);
463 if (!xa_is_node(entry))
465 node = xa_to_node(entry);
471 * xas_delete_node() - Attempt to delete an xa_node
472 * @xas: Array operation state.
474 * Attempts to delete the @xas->xa_node. This will fail if xa->node has
475 * a non-zero reference count.
477 static void xas_delete_node(struct xa_state *xas)
479 struct xa_node *node = xas->xa_node;
482 struct xa_node *parent;
484 XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
488 parent = xa_parent_locked(xas->xa, node);
489 xas->xa_node = parent;
490 xas->xa_offset = node->offset;
494 xas->xa->xa_head = NULL;
495 xas->xa_node = XAS_BOUNDS;
499 parent->slots[xas->xa_offset] = NULL;
501 XA_NODE_BUG_ON(parent, parent->count > XA_CHUNK_SIZE);
503 xas_update(xas, node);
511 * xas_free_nodes() - Free this node and all nodes that it references
512 * @xas: Array operation state.
515 * This node has been removed from the tree. We must now free it and all
516 * of its subnodes. There may be RCU walkers with references into the tree,
517 * so we must replace all entries with retry markers.
519 static void xas_free_nodes(struct xa_state *xas, struct xa_node *top)
521 unsigned int offset = 0;
522 struct xa_node *node = top;
525 void *entry = xa_entry_locked(xas->xa, node, offset);
527 if (node->shift && xa_is_node(entry)) {
528 node = xa_to_node(entry);
533 RCU_INIT_POINTER(node->slots[offset], XA_RETRY_ENTRY);
535 while (offset == XA_CHUNK_SIZE) {
536 struct xa_node *parent;
538 parent = xa_parent_locked(xas->xa, node);
539 offset = node->offset + 1;
542 xas_update(xas, node);
552 * xas_expand adds nodes to the head of the tree until it has reached
553 * sufficient height to be able to contain @xas->xa_index
555 static int xas_expand(struct xa_state *xas, void *head)
557 struct xarray *xa = xas->xa;
558 struct xa_node *node = NULL;
559 unsigned int shift = 0;
560 unsigned long max = xas_max(xas);
565 while ((max >> shift) >= XA_CHUNK_SIZE)
566 shift += XA_CHUNK_SHIFT;
567 return shift + XA_CHUNK_SHIFT;
568 } else if (xa_is_node(head)) {
569 node = xa_to_node(head);
570 shift = node->shift + XA_CHUNK_SHIFT;
574 while (max > max_index(head)) {
577 XA_NODE_BUG_ON(node, shift > BITS_PER_LONG);
578 node = xas_alloc(xas, shift);
583 if (xa_is_value(head))
585 RCU_INIT_POINTER(node->slots[0], head);
587 /* Propagate the aggregated mark info to the new child */
589 if (xa_track_free(xa) && mark == XA_FREE_MARK) {
590 node_mark_all(node, XA_FREE_MARK);
591 if (!xa_marked(xa, XA_FREE_MARK)) {
592 node_clear_mark(node, 0, XA_FREE_MARK);
593 xa_mark_set(xa, XA_FREE_MARK);
595 } else if (xa_marked(xa, mark)) {
596 node_set_mark(node, 0, mark);
598 if (mark == XA_MARK_MAX)
604 * Now that the new node is fully initialised, we can add
607 if (xa_is_node(head)) {
608 xa_to_node(head)->offset = 0;
609 rcu_assign_pointer(xa_to_node(head)->parent, node);
611 head = xa_mk_node(node);
612 rcu_assign_pointer(xa->xa_head, head);
613 xas_update(xas, node);
615 shift += XA_CHUNK_SHIFT;
623 * xas_create() - Create a slot to store an entry in.
624 * @xas: XArray operation state.
625 * @allow_root: %true if we can store the entry in the root directly
627 * Most users will not need to call this function directly, as it is called
628 * by xas_store(). It is useful for doing conditional store operations
629 * (see the xa_cmpxchg() implementation for an example).
631 * Return: If the slot already existed, returns the contents of this slot.
632 * If the slot was newly created, returns %NULL. If it failed to create the
633 * slot, returns %NULL and indicates the error in @xas.
635 static void *xas_create(struct xa_state *xas, bool allow_root)
637 struct xarray *xa = xas->xa;
640 struct xa_node *node = xas->xa_node;
642 unsigned int order = xas->xa_shift;
645 entry = xa_head_locked(xa);
647 if (!entry && xa_zero_busy(xa))
648 entry = XA_ZERO_ENTRY;
649 shift = xas_expand(xas, entry);
652 if (!shift && !allow_root)
653 shift = XA_CHUNK_SHIFT;
654 entry = xa_head_locked(xa);
656 } else if (xas_error(xas)) {
659 unsigned int offset = xas->xa_offset;
662 entry = xa_entry_locked(xa, node, offset);
663 slot = &node->slots[offset];
666 entry = xa_head_locked(xa);
670 while (shift > order) {
671 shift -= XA_CHUNK_SHIFT;
673 node = xas_alloc(xas, shift);
676 if (xa_track_free(xa))
677 node_mark_all(node, XA_FREE_MARK);
678 rcu_assign_pointer(*slot, xa_mk_node(node));
679 } else if (xa_is_node(entry)) {
680 node = xa_to_node(entry);
684 entry = xas_descend(xas, node);
685 slot = &node->slots[xas->xa_offset];
692 * xas_create_range() - Ensure that stores to this range will succeed
693 * @xas: XArray operation state.
695 * Creates all of the slots in the range covered by @xas. Sets @xas to
696 * create single-index entries and positions it at the beginning of the
697 * range. This is for the benefit of users which have not yet been
698 * converted to use multi-index entries.
700 void xas_create_range(struct xa_state *xas)
702 unsigned long index = xas->xa_index;
703 unsigned char shift = xas->xa_shift;
704 unsigned char sibs = xas->xa_sibs;
706 xas->xa_index |= ((sibs + 1) << shift) - 1;
707 if (xas_is_node(xas) && xas->xa_node->shift == xas->xa_shift)
708 xas->xa_offset |= sibs;
713 xas_create(xas, true);
716 if (xas->xa_index <= (index | XA_CHUNK_MASK))
718 xas->xa_index -= XA_CHUNK_SIZE;
721 struct xa_node *node = xas->xa_node;
722 xas->xa_node = xa_parent_locked(xas->xa, node);
723 xas->xa_offset = node->offset - 1;
724 if (node->offset != 0)
730 xas->xa_shift = shift;
732 xas->xa_index = index;
735 xas->xa_index = index;
739 EXPORT_SYMBOL_GPL(xas_create_range);
741 static void update_node(struct xa_state *xas, struct xa_node *node,
742 int count, int values)
744 if (!node || (!count && !values))
747 node->count += count;
748 node->nr_values += values;
749 XA_NODE_BUG_ON(node, node->count > XA_CHUNK_SIZE);
750 XA_NODE_BUG_ON(node, node->nr_values > XA_CHUNK_SIZE);
751 xas_update(xas, node);
753 xas_delete_node(xas);
757 * xas_store() - Store this entry in the XArray.
758 * @xas: XArray operation state.
761 * If @xas is operating on a multi-index entry, the entry returned by this
762 * function is essentially meaningless (it may be an internal entry or it
763 * may be %NULL, even if there are non-NULL entries at some of the indices
764 * covered by the range). This is not a problem for any current users,
765 * and can be changed if needed.
767 * Return: The old entry at this index.
769 void *xas_store(struct xa_state *xas, void *entry)
771 struct xa_node *node;
772 void __rcu **slot = &xas->xa->xa_head;
773 unsigned int offset, max;
777 bool value = xa_is_value(entry);
780 bool allow_root = !xa_is_node(entry) && !xa_is_zero(entry);
781 first = xas_create(xas, allow_root);
783 first = xas_load(xas);
786 if (xas_invalid(xas))
789 if (node && (xas->xa_shift < node->shift))
791 if ((first == entry) && !xas->xa_sibs)
795 offset = xas->xa_offset;
796 max = xas->xa_offset + xas->xa_sibs;
798 slot = &node->slots[offset];
800 xas_squash_marks(xas);
807 * Must clear the marks before setting the entry to NULL,
808 * otherwise xas_for_each_marked may find a NULL entry and
809 * stop early. rcu_assign_pointer contains a release barrier
810 * so the mark clearing will appear to happen before the
811 * entry is set to NULL.
813 rcu_assign_pointer(*slot, entry);
814 if (xa_is_node(next) && (!node || node->shift))
815 xas_free_nodes(xas, xa_to_node(next));
818 count += !next - !entry;
819 values += !xa_is_value(first) - !value;
823 if (!xa_is_sibling(entry))
824 entry = xa_mk_sibling(xas->xa_offset);
826 if (offset == XA_CHUNK_MASK)
829 next = xa_entry_locked(xas->xa, node, ++offset);
830 if (!xa_is_sibling(next)) {
831 if (!entry && (offset > max))
838 update_node(xas, node, count, values);
841 EXPORT_SYMBOL_GPL(xas_store);
844 * xas_get_mark() - Returns the state of this mark.
845 * @xas: XArray operation state.
846 * @mark: Mark number.
848 * Return: true if the mark is set, false if the mark is clear or @xas
849 * is in an error state.
851 bool xas_get_mark(const struct xa_state *xas, xa_mark_t mark)
853 if (xas_invalid(xas))
856 return xa_marked(xas->xa, mark);
857 return node_get_mark(xas->xa_node, xas->xa_offset, mark);
859 EXPORT_SYMBOL_GPL(xas_get_mark);
862 * xas_set_mark() - Sets the mark on this entry and its parents.
863 * @xas: XArray operation state.
864 * @mark: Mark number.
866 * Sets the specified mark on this entry, and walks up the tree setting it
867 * on all the ancestor entries. Does nothing if @xas has not been walked to
868 * an entry, or is in an error state.
870 void xas_set_mark(const struct xa_state *xas, xa_mark_t mark)
872 struct xa_node *node = xas->xa_node;
873 unsigned int offset = xas->xa_offset;
875 if (xas_invalid(xas))
879 if (node_set_mark(node, offset, mark))
881 offset = node->offset;
882 node = xa_parent_locked(xas->xa, node);
885 if (!xa_marked(xas->xa, mark))
886 xa_mark_set(xas->xa, mark);
888 EXPORT_SYMBOL_GPL(xas_set_mark);
891 * xas_clear_mark() - Clears the mark on this entry and its parents.
892 * @xas: XArray operation state.
893 * @mark: Mark number.
895 * Clears the specified mark on this entry, and walks back to the head
896 * attempting to clear it on all the ancestor entries. Does nothing if
897 * @xas has not been walked to an entry, or is in an error state.
899 void xas_clear_mark(const struct xa_state *xas, xa_mark_t mark)
901 struct xa_node *node = xas->xa_node;
902 unsigned int offset = xas->xa_offset;
904 if (xas_invalid(xas))
908 if (!node_clear_mark(node, offset, mark))
910 if (node_any_mark(node, mark))
913 offset = node->offset;
914 node = xa_parent_locked(xas->xa, node);
917 if (xa_marked(xas->xa, mark))
918 xa_mark_clear(xas->xa, mark);
920 EXPORT_SYMBOL_GPL(xas_clear_mark);
923 * xas_init_marks() - Initialise all marks for the entry
924 * @xas: Array operations state.
926 * Initialise all marks for the entry specified by @xas. If we're tracking
927 * free entries with a mark, we need to set it on all entries. All other
930 * This implementation is not as efficient as it could be; we may walk
931 * up the tree multiple times.
933 void xas_init_marks(const struct xa_state *xas)
938 if (xa_track_free(xas->xa) && mark == XA_FREE_MARK)
939 xas_set_mark(xas, mark);
941 xas_clear_mark(xas, mark);
942 if (mark == XA_MARK_MAX)
947 EXPORT_SYMBOL_GPL(xas_init_marks);
950 * xas_pause() - Pause a walk to drop a lock.
951 * @xas: XArray operation state.
953 * Some users need to pause a walk and drop the lock they're holding in
954 * order to yield to a higher priority thread or carry out an operation
955 * on an entry. Those users should call this function before they drop
956 * the lock. It resets the @xas to be suitable for the next iteration
957 * of the loop after the user has reacquired the lock. If most entries
958 * found during a walk require you to call xas_pause(), the xa_for_each()
959 * iterator may be more appropriate.
961 * Note that xas_pause() only works for forward iteration. If a user needs
962 * to pause a reverse iteration, we will need a xas_pause_rev().
964 void xas_pause(struct xa_state *xas)
966 struct xa_node *node = xas->xa_node;
968 if (xas_invalid(xas))
971 xas->xa_node = XAS_RESTART;
973 unsigned int offset = xas->xa_offset;
974 while (++offset < XA_CHUNK_SIZE) {
975 if (!xa_is_sibling(xa_entry(xas->xa, node, offset)))
978 xas->xa_index += (offset - xas->xa_offset) << node->shift;
979 if (xas->xa_index == 0)
980 xas->xa_node = XAS_BOUNDS;
985 EXPORT_SYMBOL_GPL(xas_pause);
988 * __xas_prev() - Find the previous entry in the XArray.
989 * @xas: XArray operation state.
991 * Helper function for xas_prev() which handles all the complex cases
994 void *__xas_prev(struct xa_state *xas)
998 if (!xas_frozen(xas->xa_node))
1001 return set_bounds(xas);
1002 if (xas_not_node(xas->xa_node))
1003 return xas_load(xas);
1005 if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node))
1008 while (xas->xa_offset == 255) {
1009 xas->xa_offset = xas->xa_node->offset - 1;
1010 xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1012 return set_bounds(xas);
1016 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1017 if (!xa_is_node(entry))
1020 xas->xa_node = xa_to_node(entry);
1021 xas_set_offset(xas);
1024 EXPORT_SYMBOL_GPL(__xas_prev);
1027 * __xas_next() - Find the next entry in the XArray.
1028 * @xas: XArray operation state.
1030 * Helper function for xas_next() which handles all the complex cases
1033 void *__xas_next(struct xa_state *xas)
1037 if (!xas_frozen(xas->xa_node))
1040 return set_bounds(xas);
1041 if (xas_not_node(xas->xa_node))
1042 return xas_load(xas);
1044 if (xas->xa_offset != get_offset(xas->xa_index, xas->xa_node))
1047 while (xas->xa_offset == XA_CHUNK_SIZE) {
1048 xas->xa_offset = xas->xa_node->offset + 1;
1049 xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1051 return set_bounds(xas);
1055 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1056 if (!xa_is_node(entry))
1059 xas->xa_node = xa_to_node(entry);
1060 xas_set_offset(xas);
1063 EXPORT_SYMBOL_GPL(__xas_next);
1066 * xas_find() - Find the next present entry in the XArray.
1067 * @xas: XArray operation state.
1068 * @max: Highest index to return.
1070 * If the @xas has not yet been walked to an entry, return the entry
1071 * which has an index >= xas.xa_index. If it has been walked, the entry
1072 * currently being pointed at has been processed, and so we move to the
1075 * If no entry is found and the array is smaller than @max, the iterator
1076 * is set to the smallest index not yet in the array. This allows @xas
1077 * to be immediately passed to xas_store().
1079 * Return: The entry, if found, otherwise %NULL.
1081 void *xas_find(struct xa_state *xas, unsigned long max)
1085 if (xas_error(xas) || xas->xa_node == XAS_BOUNDS)
1087 if (xas->xa_index > max)
1088 return set_bounds(xas);
1090 if (!xas->xa_node) {
1092 return set_bounds(xas);
1093 } else if (xas->xa_node == XAS_RESTART) {
1094 entry = xas_load(xas);
1095 if (entry || xas_not_node(xas->xa_node))
1097 } else if (!xas->xa_node->shift &&
1098 xas->xa_offset != (xas->xa_index & XA_CHUNK_MASK)) {
1099 xas->xa_offset = ((xas->xa_index - 1) & XA_CHUNK_MASK) + 1;
1104 while (xas->xa_node && (xas->xa_index <= max)) {
1105 if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) {
1106 xas->xa_offset = xas->xa_node->offset + 1;
1107 xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1111 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1112 if (xa_is_node(entry)) {
1113 xas->xa_node = xa_to_node(entry);
1117 if (entry && !xa_is_sibling(entry))
1124 xas->xa_node = XAS_BOUNDS;
1127 EXPORT_SYMBOL_GPL(xas_find);
1130 * xas_find_marked() - Find the next marked entry in the XArray.
1131 * @xas: XArray operation state.
1132 * @max: Highest index to return.
1133 * @mark: Mark number to search for.
1135 * If the @xas has not yet been walked to an entry, return the marked entry
1136 * which has an index >= xas.xa_index. If it has been walked, the entry
1137 * currently being pointed at has been processed, and so we return the
1138 * first marked entry with an index > xas.xa_index.
1140 * If no marked entry is found and the array is smaller than @max, @xas is
1141 * set to the bounds state and xas->xa_index is set to the smallest index
1142 * not yet in the array. This allows @xas to be immediately passed to
1145 * If no entry is found before @max is reached, @xas is set to the restart
1148 * Return: The entry, if found, otherwise %NULL.
1150 void *xas_find_marked(struct xa_state *xas, unsigned long max, xa_mark_t mark)
1152 bool advance = true;
1153 unsigned int offset;
1158 if (xas->xa_index > max)
1161 if (!xas->xa_node) {
1164 } else if (xas_top(xas->xa_node)) {
1166 entry = xa_head(xas->xa);
1167 xas->xa_node = NULL;
1168 if (xas->xa_index > max_index(entry))
1170 if (!xa_is_node(entry)) {
1171 if (xa_marked(xas->xa, mark))
1176 xas->xa_node = xa_to_node(entry);
1177 xas->xa_offset = xas->xa_index >> xas->xa_node->shift;
1180 while (xas->xa_index <= max) {
1181 if (unlikely(xas->xa_offset == XA_CHUNK_SIZE)) {
1182 xas->xa_offset = xas->xa_node->offset + 1;
1183 xas->xa_node = xa_parent(xas->xa, xas->xa_node);
1191 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1192 if (xa_is_sibling(entry)) {
1193 xas->xa_offset = xa_to_sibling(entry);
1194 xas_move_index(xas, xas->xa_offset);
1198 offset = xas_find_chunk(xas, advance, mark);
1199 if (offset > xas->xa_offset) {
1201 xas_move_index(xas, offset);
1203 if ((xas->xa_index - 1) >= max)
1205 xas->xa_offset = offset;
1206 if (offset == XA_CHUNK_SIZE)
1210 entry = xa_entry(xas->xa, xas->xa_node, xas->xa_offset);
1211 if (!xa_is_node(entry))
1213 xas->xa_node = xa_to_node(entry);
1214 xas_set_offset(xas);
1218 if (xas->xa_index > max)
1220 return set_bounds(xas);
1222 xas->xa_node = XAS_RESTART;
1225 EXPORT_SYMBOL_GPL(xas_find_marked);
1228 * xas_find_conflict() - Find the next present entry in a range.
1229 * @xas: XArray operation state.
1231 * The @xas describes both a range and a position within that range.
1233 * Context: Any context. Expects xa_lock to be held.
1234 * Return: The next entry in the range covered by @xas or %NULL.
1236 void *xas_find_conflict(struct xa_state *xas)
1246 if (xas_top(xas->xa_node)) {
1247 curr = xas_start(xas);
1250 while (xa_is_node(curr)) {
1251 struct xa_node *node = xa_to_node(curr);
1252 curr = xas_descend(xas, node);
1258 if (xas->xa_node->shift > xas->xa_shift)
1262 if (xas->xa_node->shift == xas->xa_shift) {
1263 if ((xas->xa_offset & xas->xa_sibs) == xas->xa_sibs)
1265 } else if (xas->xa_offset == XA_CHUNK_MASK) {
1266 xas->xa_offset = xas->xa_node->offset;
1267 xas->xa_node = xa_parent_locked(xas->xa, xas->xa_node);
1272 curr = xa_entry_locked(xas->xa, xas->xa_node, ++xas->xa_offset);
1273 if (xa_is_sibling(curr))
1275 while (xa_is_node(curr)) {
1276 xas->xa_node = xa_to_node(curr);
1278 curr = xa_entry_locked(xas->xa, xas->xa_node, 0);
1283 xas->xa_offset -= xas->xa_sibs;
1286 EXPORT_SYMBOL_GPL(xas_find_conflict);
1289 * xa_load() - Load an entry from an XArray.
1291 * @index: index into array.
1293 * Context: Any context. Takes and releases the RCU lock.
1294 * Return: The entry at @index in @xa.
1296 void *xa_load(struct xarray *xa, unsigned long index)
1298 XA_STATE(xas, xa, index);
1303 entry = xas_load(&xas);
1304 if (xa_is_zero(entry))
1306 } while (xas_retry(&xas, entry));
1311 EXPORT_SYMBOL(xa_load);
1313 static void *xas_result(struct xa_state *xas, void *curr)
1315 if (xa_is_zero(curr))
1318 curr = xas->xa_node;
1323 * __xa_erase() - Erase this entry from the XArray while locked.
1325 * @index: Index into array.
1327 * After this function returns, loading from @index will return %NULL.
1328 * If the index is part of a multi-index entry, all indices will be erased
1329 * and none of the entries will be part of a multi-index entry.
1331 * Context: Any context. Expects xa_lock to be held on entry.
1332 * Return: The entry which used to be at this index.
1334 void *__xa_erase(struct xarray *xa, unsigned long index)
1336 XA_STATE(xas, xa, index);
1337 return xas_result(&xas, xas_store(&xas, NULL));
1339 EXPORT_SYMBOL(__xa_erase);
1342 * xa_erase() - Erase this entry from the XArray.
1344 * @index: Index of entry.
1346 * After this function returns, loading from @index will return %NULL.
1347 * If the index is part of a multi-index entry, all indices will be erased
1348 * and none of the entries will be part of a multi-index entry.
1350 * Context: Any context. Takes and releases the xa_lock.
1351 * Return: The entry which used to be at this index.
1353 void *xa_erase(struct xarray *xa, unsigned long index)
1358 entry = __xa_erase(xa, index);
1363 EXPORT_SYMBOL(xa_erase);
1366 * __xa_store() - Store this entry in the XArray.
1368 * @index: Index into array.
1369 * @entry: New entry.
1370 * @gfp: Memory allocation flags.
1372 * You must already be holding the xa_lock when calling this function.
1373 * It will drop the lock if needed to allocate memory, and then reacquire
1376 * Context: Any context. Expects xa_lock to be held on entry. May
1377 * release and reacquire xa_lock if @gfp flags permit.
1378 * Return: The old entry at this index or xa_err() if an error happened.
1380 void *__xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
1382 XA_STATE(xas, xa, index);
1385 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1386 return XA_ERROR(-EINVAL);
1387 if (xa_track_free(xa) && !entry)
1388 entry = XA_ZERO_ENTRY;
1391 curr = xas_store(&xas, entry);
1392 if (xa_track_free(xa))
1393 xas_clear_mark(&xas, XA_FREE_MARK);
1394 } while (__xas_nomem(&xas, gfp));
1396 return xas_result(&xas, curr);
1398 EXPORT_SYMBOL(__xa_store);
1401 * xa_store() - Store this entry in the XArray.
1403 * @index: Index into array.
1404 * @entry: New entry.
1405 * @gfp: Memory allocation flags.
1407 * After this function returns, loads from this index will return @entry.
1408 * Storing into an existing multislot entry updates the entry of every index.
1409 * The marks associated with @index are unaffected unless @entry is %NULL.
1411 * Context: Any context. Takes and releases the xa_lock.
1412 * May sleep if the @gfp flags permit.
1413 * Return: The old entry at this index on success, xa_err(-EINVAL) if @entry
1414 * cannot be stored in an XArray, or xa_err(-ENOMEM) if memory allocation
1417 void *xa_store(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
1422 curr = __xa_store(xa, index, entry, gfp);
1427 EXPORT_SYMBOL(xa_store);
1430 * __xa_cmpxchg() - Store this entry in the XArray.
1432 * @index: Index into array.
1433 * @old: Old value to test against.
1434 * @entry: New entry.
1435 * @gfp: Memory allocation flags.
1437 * You must already be holding the xa_lock when calling this function.
1438 * It will drop the lock if needed to allocate memory, and then reacquire
1441 * Context: Any context. Expects xa_lock to be held on entry. May
1442 * release and reacquire xa_lock if @gfp flags permit.
1443 * Return: The old entry at this index or xa_err() if an error happened.
1445 void *__xa_cmpxchg(struct xarray *xa, unsigned long index,
1446 void *old, void *entry, gfp_t gfp)
1448 XA_STATE(xas, xa, index);
1451 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1452 return XA_ERROR(-EINVAL);
1455 curr = xas_load(&xas);
1457 xas_store(&xas, entry);
1458 if (xa_track_free(xa) && entry && !curr)
1459 xas_clear_mark(&xas, XA_FREE_MARK);
1461 } while (__xas_nomem(&xas, gfp));
1463 return xas_result(&xas, curr);
1465 EXPORT_SYMBOL(__xa_cmpxchg);
1468 * __xa_insert() - Store this entry in the XArray if no entry is present.
1470 * @index: Index into array.
1471 * @entry: New entry.
1472 * @gfp: Memory allocation flags.
1474 * Inserting a NULL entry will store a reserved entry (like xa_reserve())
1475 * if no entry is present. Inserting will fail if a reserved entry is
1476 * present, even though loading from this index will return NULL.
1478 * Context: Any context. Expects xa_lock to be held on entry. May
1479 * release and reacquire xa_lock if @gfp flags permit.
1480 * Return: 0 if the store succeeded. -EBUSY if another entry was present.
1481 * -ENOMEM if memory could not be allocated.
1483 int __xa_insert(struct xarray *xa, unsigned long index, void *entry, gfp_t gfp)
1485 XA_STATE(xas, xa, index);
1488 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1491 entry = XA_ZERO_ENTRY;
1494 curr = xas_load(&xas);
1496 xas_store(&xas, entry);
1497 if (xa_track_free(xa))
1498 xas_clear_mark(&xas, XA_FREE_MARK);
1500 xas_set_err(&xas, -EBUSY);
1502 } while (__xas_nomem(&xas, gfp));
1504 return xas_error(&xas);
1506 EXPORT_SYMBOL(__xa_insert);
1508 #ifdef CONFIG_XARRAY_MULTI
1509 static void xas_set_range(struct xa_state *xas, unsigned long first,
1512 unsigned int shift = 0;
1513 unsigned long sibs = last - first;
1514 unsigned int offset = XA_CHUNK_MASK;
1516 xas_set(xas, first);
1518 while ((first & XA_CHUNK_MASK) == 0) {
1519 if (sibs < XA_CHUNK_MASK)
1521 if ((sibs == XA_CHUNK_MASK) && (offset < XA_CHUNK_MASK))
1523 shift += XA_CHUNK_SHIFT;
1524 if (offset == XA_CHUNK_MASK)
1525 offset = sibs & XA_CHUNK_MASK;
1526 sibs >>= XA_CHUNK_SHIFT;
1527 first >>= XA_CHUNK_SHIFT;
1530 offset = first & XA_CHUNK_MASK;
1531 if (offset + sibs > XA_CHUNK_MASK)
1532 sibs = XA_CHUNK_MASK - offset;
1533 if ((((first + sibs + 1) << shift) - 1) > last)
1536 xas->xa_shift = shift;
1537 xas->xa_sibs = sibs;
1541 * xa_store_range() - Store this entry at a range of indices in the XArray.
1543 * @first: First index to affect.
1544 * @last: Last index to affect.
1545 * @entry: New entry.
1546 * @gfp: Memory allocation flags.
1548 * After this function returns, loads from any index between @first and @last,
1549 * inclusive will return @entry.
1550 * Storing into an existing multislot entry updates the entry of every index.
1551 * The marks associated with @index are unaffected unless @entry is %NULL.
1553 * Context: Process context. Takes and releases the xa_lock. May sleep
1554 * if the @gfp flags permit.
1555 * Return: %NULL on success, xa_err(-EINVAL) if @entry cannot be stored in
1556 * an XArray, or xa_err(-ENOMEM) if memory allocation failed.
1558 void *xa_store_range(struct xarray *xa, unsigned long first,
1559 unsigned long last, void *entry, gfp_t gfp)
1561 XA_STATE(xas, xa, 0);
1563 if (WARN_ON_ONCE(xa_is_internal(entry)))
1564 return XA_ERROR(-EINVAL);
1566 return XA_ERROR(-EINVAL);
1571 unsigned int order = BITS_PER_LONG;
1573 order = __ffs(last + 1);
1574 xas_set_order(&xas, last, order);
1575 xas_create(&xas, true);
1576 if (xas_error(&xas))
1580 xas_set_range(&xas, first, last);
1581 xas_store(&xas, entry);
1582 if (xas_error(&xas))
1584 first += xas_size(&xas);
1585 } while (first <= last);
1588 } while (xas_nomem(&xas, gfp));
1590 return xas_result(&xas, NULL);
1592 EXPORT_SYMBOL(xa_store_range);
1593 #endif /* CONFIG_XARRAY_MULTI */
1596 * __xa_alloc() - Find somewhere to store this entry in the XArray.
1598 * @id: Pointer to ID.
1599 * @limit: Range for allocated ID.
1600 * @entry: New entry.
1601 * @gfp: Memory allocation flags.
1603 * Finds an empty entry in @xa between @limit.min and @limit.max,
1604 * stores the index into the @id pointer, then stores the entry at
1605 * that index. A concurrent lookup will not see an uninitialised @id.
1607 * Context: Any context. Expects xa_lock to be held on entry. May
1608 * release and reacquire xa_lock if @gfp flags permit.
1609 * Return: 0 on success, -ENOMEM if memory could not be allocated or
1610 * -EBUSY if there are no free entries in @limit.
1612 int __xa_alloc(struct xarray *xa, u32 *id, void *entry,
1613 struct xa_limit limit, gfp_t gfp)
1615 XA_STATE(xas, xa, 0);
1617 if (WARN_ON_ONCE(xa_is_advanced(entry)))
1619 if (WARN_ON_ONCE(!xa_track_free(xa)))
1623 entry = XA_ZERO_ENTRY;
1626 xas.xa_index = limit.min;
1627 xas_find_marked(&xas, limit.max, XA_FREE_MARK);
1628 if (xas.xa_node == XAS_RESTART)
1629 xas_set_err(&xas, -EBUSY);
1632 xas_store(&xas, entry);
1633 xas_clear_mark(&xas, XA_FREE_MARK);
1634 } while (__xas_nomem(&xas, gfp));
1636 return xas_error(&xas);
1638 EXPORT_SYMBOL(__xa_alloc);
1641 * __xa_alloc_cyclic() - Find somewhere to store this entry in the XArray.
1643 * @id: Pointer to ID.
1644 * @entry: New entry.
1645 * @limit: Range of allocated ID.
1646 * @next: Pointer to next ID to allocate.
1647 * @gfp: Memory allocation flags.
1649 * Finds an empty entry in @xa between @limit.min and @limit.max,
1650 * stores the index into the @id pointer, then stores the entry at
1651 * that index. A concurrent lookup will not see an uninitialised @id.
1652 * The search for an empty entry will start at @next and will wrap
1653 * around if necessary.
1655 * Context: Any context. Expects xa_lock to be held on entry. May
1656 * release and reacquire xa_lock if @gfp flags permit.
1657 * Return: 0 if the allocation succeeded without wrapping. 1 if the
1658 * allocation succeeded after wrapping, -ENOMEM if memory could not be
1659 * allocated or -EBUSY if there are no free entries in @limit.
1661 int __xa_alloc_cyclic(struct xarray *xa, u32 *id, void *entry,
1662 struct xa_limit limit, u32 *next, gfp_t gfp)
1664 u32 min = limit.min;
1667 limit.min = max(min, *next);
1668 ret = __xa_alloc(xa, id, entry, limit, gfp);
1669 if ((xa->xa_flags & XA_FLAGS_ALLOC_WRAPPED) && ret == 0) {
1670 xa->xa_flags &= ~XA_FLAGS_ALLOC_WRAPPED;
1674 if (ret < 0 && limit.min > min) {
1676 ret = __xa_alloc(xa, id, entry, limit, gfp);
1684 xa->xa_flags |= XA_FLAGS_ALLOC_WRAPPED;
1688 EXPORT_SYMBOL(__xa_alloc_cyclic);
1691 * __xa_set_mark() - Set this mark on this entry while locked.
1693 * @index: Index of entry.
1694 * @mark: Mark number.
1696 * Attempting to set a mark on a %NULL entry does not succeed.
1698 * Context: Any context. Expects xa_lock to be held on entry.
1700 void __xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1702 XA_STATE(xas, xa, index);
1703 void *entry = xas_load(&xas);
1706 xas_set_mark(&xas, mark);
1708 EXPORT_SYMBOL(__xa_set_mark);
1711 * __xa_clear_mark() - Clear this mark on this entry while locked.
1713 * @index: Index of entry.
1714 * @mark: Mark number.
1716 * Context: Any context. Expects xa_lock to be held on entry.
1718 void __xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1720 XA_STATE(xas, xa, index);
1721 void *entry = xas_load(&xas);
1724 xas_clear_mark(&xas, mark);
1726 EXPORT_SYMBOL(__xa_clear_mark);
1729 * xa_get_mark() - Inquire whether this mark is set on this entry.
1731 * @index: Index of entry.
1732 * @mark: Mark number.
1734 * This function uses the RCU read lock, so the result may be out of date
1735 * by the time it returns. If you need the result to be stable, use a lock.
1737 * Context: Any context. Takes and releases the RCU lock.
1738 * Return: True if the entry at @index has this mark set, false if it doesn't.
1740 bool xa_get_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1742 XA_STATE(xas, xa, index);
1746 entry = xas_start(&xas);
1747 while (xas_get_mark(&xas, mark)) {
1748 if (!xa_is_node(entry))
1750 entry = xas_descend(&xas, xa_to_node(entry));
1758 EXPORT_SYMBOL(xa_get_mark);
1761 * xa_set_mark() - Set this mark on this entry.
1763 * @index: Index of entry.
1764 * @mark: Mark number.
1766 * Attempting to set a mark on a %NULL entry does not succeed.
1768 * Context: Process context. Takes and releases the xa_lock.
1770 void xa_set_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1773 __xa_set_mark(xa, index, mark);
1776 EXPORT_SYMBOL(xa_set_mark);
1779 * xa_clear_mark() - Clear this mark on this entry.
1781 * @index: Index of entry.
1782 * @mark: Mark number.
1784 * Clearing a mark always succeeds.
1786 * Context: Process context. Takes and releases the xa_lock.
1788 void xa_clear_mark(struct xarray *xa, unsigned long index, xa_mark_t mark)
1791 __xa_clear_mark(xa, index, mark);
1794 EXPORT_SYMBOL(xa_clear_mark);
1797 * xa_find() - Search the XArray for an entry.
1799 * @indexp: Pointer to an index.
1800 * @max: Maximum index to search to.
1801 * @filter: Selection criterion.
1803 * Finds the entry in @xa which matches the @filter, and has the lowest
1804 * index that is at least @indexp and no more than @max.
1805 * If an entry is found, @indexp is updated to be the index of the entry.
1806 * This function is protected by the RCU read lock, so it may not find
1807 * entries which are being simultaneously added. It will not return an
1808 * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
1810 * Context: Any context. Takes and releases the RCU lock.
1811 * Return: The entry, if found, otherwise %NULL.
1813 void *xa_find(struct xarray *xa, unsigned long *indexp,
1814 unsigned long max, xa_mark_t filter)
1816 XA_STATE(xas, xa, *indexp);
1821 if ((__force unsigned int)filter < XA_MAX_MARKS)
1822 entry = xas_find_marked(&xas, max, filter);
1824 entry = xas_find(&xas, max);
1825 } while (xas_retry(&xas, entry));
1829 *indexp = xas.xa_index;
1832 EXPORT_SYMBOL(xa_find);
1834 static bool xas_sibling(struct xa_state *xas)
1836 struct xa_node *node = xas->xa_node;
1841 mask = (XA_CHUNK_SIZE << node->shift) - 1;
1842 return (xas->xa_index & mask) >
1843 ((unsigned long)xas->xa_offset << node->shift);
1847 * xa_find_after() - Search the XArray for a present entry.
1849 * @indexp: Pointer to an index.
1850 * @max: Maximum index to search to.
1851 * @filter: Selection criterion.
1853 * Finds the entry in @xa which matches the @filter and has the lowest
1854 * index that is above @indexp and no more than @max.
1855 * If an entry is found, @indexp is updated to be the index of the entry.
1856 * This function is protected by the RCU read lock, so it may miss entries
1857 * which are being simultaneously added. It will not return an
1858 * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
1860 * Context: Any context. Takes and releases the RCU lock.
1861 * Return: The pointer, if found, otherwise %NULL.
1863 void *xa_find_after(struct xarray *xa, unsigned long *indexp,
1864 unsigned long max, xa_mark_t filter)
1866 XA_STATE(xas, xa, *indexp + 1);
1869 if (xas.xa_index == 0)
1874 if ((__force unsigned int)filter < XA_MAX_MARKS)
1875 entry = xas_find_marked(&xas, max, filter);
1877 entry = xas_find(&xas, max);
1879 if (xas_invalid(&xas))
1881 if (xas_sibling(&xas))
1883 if (!xas_retry(&xas, entry))
1889 *indexp = xas.xa_index;
1892 EXPORT_SYMBOL(xa_find_after);
1894 static unsigned int xas_extract_present(struct xa_state *xas, void **dst,
1895 unsigned long max, unsigned int n)
1901 xas_for_each(xas, entry, max) {
1902 if (xas_retry(xas, entry))
1913 static unsigned int xas_extract_marked(struct xa_state *xas, void **dst,
1914 unsigned long max, unsigned int n, xa_mark_t mark)
1920 xas_for_each_marked(xas, entry, max, mark) {
1921 if (xas_retry(xas, entry))
1933 * xa_extract() - Copy selected entries from the XArray into a normal array.
1934 * @xa: The source XArray to copy from.
1935 * @dst: The buffer to copy entries into.
1936 * @start: The first index in the XArray eligible to be selected.
1937 * @max: The last index in the XArray eligible to be selected.
1938 * @n: The maximum number of entries to copy.
1939 * @filter: Selection criterion.
1941 * Copies up to @n entries that match @filter from the XArray. The
1942 * copied entries will have indices between @start and @max, inclusive.
1944 * The @filter may be an XArray mark value, in which case entries which are
1945 * marked with that mark will be copied. It may also be %XA_PRESENT, in
1946 * which case all entries which are not %NULL will be copied.
1948 * The entries returned may not represent a snapshot of the XArray at a
1949 * moment in time. For example, if another thread stores to index 5, then
1950 * index 10, calling xa_extract() may return the old contents of index 5
1951 * and the new contents of index 10. Indices not modified while this
1952 * function is running will not be skipped.
1954 * If you need stronger guarantees, holding the xa_lock across calls to this
1955 * function will prevent concurrent modification.
1957 * Context: Any context. Takes and releases the RCU lock.
1958 * Return: The number of entries copied.
1960 unsigned int xa_extract(struct xarray *xa, void **dst, unsigned long start,
1961 unsigned long max, unsigned int n, xa_mark_t filter)
1963 XA_STATE(xas, xa, start);
1968 if ((__force unsigned int)filter < XA_MAX_MARKS)
1969 return xas_extract_marked(&xas, dst, max, n, filter);
1970 return xas_extract_present(&xas, dst, max, n);
1972 EXPORT_SYMBOL(xa_extract);
1975 * xa_destroy() - Free all internal data structures.
1978 * After calling this function, the XArray is empty and has freed all memory
1979 * allocated for its internal data structures. You are responsible for
1980 * freeing the objects referenced by the XArray.
1982 * Context: Any context. Takes and releases the xa_lock, interrupt-safe.
1984 void xa_destroy(struct xarray *xa)
1986 XA_STATE(xas, xa, 0);
1987 unsigned long flags;
1991 xas_lock_irqsave(&xas, flags);
1992 entry = xa_head_locked(xa);
1993 RCU_INIT_POINTER(xa->xa_head, NULL);
1994 xas_init_marks(&xas);
1995 if (xa_zero_busy(xa))
1996 xa_mark_clear(xa, XA_FREE_MARK);
1997 /* lockdep checks we're still holding the lock in xas_free_nodes() */
1998 if (xa_is_node(entry))
1999 xas_free_nodes(&xas, xa_to_node(entry));
2000 xas_unlock_irqrestore(&xas, flags);
2002 EXPORT_SYMBOL(xa_destroy);
2005 void xa_dump_node(const struct xa_node *node)
2011 if ((unsigned long)node & 3) {
2012 pr_cont("node %px\n", node);
2016 pr_cont("node %px %s %d parent %px shift %d count %d values %d "
2017 "array %px list %px %px marks",
2018 node, node->parent ? "offset" : "max", node->offset,
2019 node->parent, node->shift, node->count, node->nr_values,
2020 node->array, node->private_list.prev, node->private_list.next);
2021 for (i = 0; i < XA_MAX_MARKS; i++)
2022 for (j = 0; j < XA_MARK_LONGS; j++)
2023 pr_cont(" %lx", node->marks[i][j]);
2027 void xa_dump_index(unsigned long index, unsigned int shift)
2030 pr_info("%lu: ", index);
2031 else if (shift >= BITS_PER_LONG)
2032 pr_info("0-%lu: ", ~0UL);
2034 pr_info("%lu-%lu: ", index, index | ((1UL << shift) - 1));
2037 void xa_dump_entry(const void *entry, unsigned long index, unsigned long shift)
2042 xa_dump_index(index, shift);
2044 if (xa_is_node(entry)) {
2046 pr_cont("%px\n", entry);
2049 struct xa_node *node = xa_to_node(entry);
2051 for (i = 0; i < XA_CHUNK_SIZE; i++)
2052 xa_dump_entry(node->slots[i],
2053 index + (i << node->shift), node->shift);
2055 } else if (xa_is_value(entry))
2056 pr_cont("value %ld (0x%lx) [%px]\n", xa_to_value(entry),
2057 xa_to_value(entry), entry);
2058 else if (!xa_is_internal(entry))
2059 pr_cont("%px\n", entry);
2060 else if (xa_is_retry(entry))
2061 pr_cont("retry (%ld)\n", xa_to_internal(entry));
2062 else if (xa_is_sibling(entry))
2063 pr_cont("sibling (slot %ld)\n", xa_to_sibling(entry));
2064 else if (xa_is_zero(entry))
2065 pr_cont("zero (%ld)\n", xa_to_internal(entry));
2067 pr_cont("UNKNOWN ENTRY (%px)\n", entry);
2070 void xa_dump(const struct xarray *xa)
2072 void *entry = xa->xa_head;
2073 unsigned int shift = 0;
2075 pr_info("xarray: %px head %px flags %x marks %d %d %d\n", xa, entry,
2076 xa->xa_flags, xa_marked(xa, XA_MARK_0),
2077 xa_marked(xa, XA_MARK_1), xa_marked(xa, XA_MARK_2));
2078 if (xa_is_node(entry))
2079 shift = xa_to_node(entry)->shift + XA_CHUNK_SHIFT;
2080 xa_dump_entry(entry, 0, shift);