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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>
15 #include "radix-tree.h"
18 * Coding conventions in this file:
20 * @xa is used to refer to the entire xarray.
21 * @xas is the 'xarray operation state'. It may be either a pointer to
22 * an xa_state, or an xa_state stored on the stack. This is an unfortunate
24 * @index is the index of the entry being operated on
25 * @mark is an xa_mark_t; a small number indicating one of the mark bits.
26 * @node refers to an xa_node; usually the primary one being operated on by
28 * @offset is the index into the slots array inside an xa_node.
29 * @parent refers to the @xa_node closer to the head than @node.
30 * @entry refers to something stored in a slot in the xarray
33 static inline unsigned int xa_lock_type(const struct xarray
*xa
)
35 return (__force
unsigned int)xa
->xa_flags
& 3;
38 static inline void xas_lock_type(struct xa_state
*xas
, unsigned int lock_type
)
40 if (lock_type
== XA_LOCK_IRQ
)
42 else if (lock_type
== XA_LOCK_BH
)
48 static inline void xas_unlock_type(struct xa_state
*xas
, unsigned int lock_type
)
50 if (lock_type
== XA_LOCK_IRQ
)
52 else if (lock_type
== XA_LOCK_BH
)
58 static inline bool xa_track_free(const struct xarray
*xa
)
60 return xa
->xa_flags
& XA_FLAGS_TRACK_FREE
;
63 static inline bool xa_zero_busy(const struct xarray
*xa
)
65 return xa
->xa_flags
& XA_FLAGS_ZERO_BUSY
;
68 static inline void xa_mark_set(struct xarray
*xa
, xa_mark_t mark
)
70 if (!(xa
->xa_flags
& XA_FLAGS_MARK(mark
)))
71 xa
->xa_flags
|= XA_FLAGS_MARK(mark
);
74 static inline void xa_mark_clear(struct xarray
*xa
, xa_mark_t mark
)
76 if (xa
->xa_flags
& XA_FLAGS_MARK(mark
))
77 xa
->xa_flags
&= ~(XA_FLAGS_MARK(mark
));
80 static inline unsigned long *node_marks(struct xa_node
*node
, xa_mark_t mark
)
82 return node
->marks
[(__force
unsigned)mark
];
85 static inline bool node_get_mark(struct xa_node
*node
,
86 unsigned int offset
, xa_mark_t mark
)
88 return test_bit(offset
, node_marks(node
, mark
));
91 /* returns true if the bit was set */
92 static inline bool node_set_mark(struct xa_node
*node
, unsigned int offset
,
95 return __test_and_set_bit(offset
, node_marks(node
, mark
));
98 /* returns true if the bit was set */
99 static inline bool node_clear_mark(struct xa_node
*node
, unsigned int offset
,
102 return __test_and_clear_bit(offset
, node_marks(node
, mark
));
105 static inline bool node_any_mark(struct xa_node
*node
, xa_mark_t mark
)
107 return !bitmap_empty(node_marks(node
, mark
), XA_CHUNK_SIZE
);
110 static inline void node_mark_all(struct xa_node
*node
, xa_mark_t mark
)
112 bitmap_fill(node_marks(node
, mark
), XA_CHUNK_SIZE
);
115 #define mark_inc(mark) do { \
116 mark = (__force xa_mark_t)((__force unsigned)(mark) + 1); \
120 * xas_squash_marks() - Merge all marks to the first entry
121 * @xas: Array operation state.
123 * Set a mark on the first entry if any entry has it set. Clear marks on
124 * all sibling entries.
126 static void xas_squash_marks(const struct xa_state
*xas
)
128 unsigned int mark
= 0;
129 unsigned int limit
= xas
->xa_offset
+ xas
->xa_sibs
+ 1;
135 unsigned long *marks
= xas
->xa_node
->marks
[mark
];
136 if (find_next_bit(marks
, limit
, xas
->xa_offset
+ 1) == limit
)
138 __set_bit(xas
->xa_offset
, marks
);
139 bitmap_clear(marks
, xas
->xa_offset
+ 1, xas
->xa_sibs
);
140 } while (mark
++ != (__force
unsigned)XA_MARK_MAX
);
143 /* extracts the offset within this node from the index */
144 static unsigned int get_offset(unsigned long index
, struct xa_node
*node
)
146 return (index
>> node
->shift
) & XA_CHUNK_MASK
;
149 static void xas_set_offset(struct xa_state
*xas
)
151 xas
->xa_offset
= get_offset(xas
->xa_index
, xas
->xa_node
);
154 /* move the index either forwards (find) or backwards (sibling slot) */
155 static void xas_move_index(struct xa_state
*xas
, unsigned long offset
)
157 unsigned int shift
= xas
->xa_node
->shift
;
158 xas
->xa_index
&= ~XA_CHUNK_MASK
<< shift
;
159 xas
->xa_index
+= offset
<< shift
;
162 static void xas_next_offset(struct xa_state
*xas
)
165 xas_move_index(xas
, xas
->xa_offset
);
168 static void *set_bounds(struct xa_state
*xas
)
170 xas
->xa_node
= XAS_BOUNDS
;
175 * Starts a walk. If the @xas is already valid, we assume that it's on
176 * the right path and just return where we've got to. If we're in an
177 * error state, return NULL. If the index is outside the current scope
178 * of the xarray, return NULL without changing @xas->xa_node. Otherwise
179 * set @xas->xa_node to NULL and return the current head of the array.
181 static void *xas_start(struct xa_state
*xas
)
186 return xas_reload(xas
);
190 entry
= xa_head(xas
->xa
);
191 if (!xa_is_node(entry
)) {
193 return set_bounds(xas
);
195 if ((xas
->xa_index
>> xa_to_node(entry
)->shift
) > XA_CHUNK_MASK
)
196 return set_bounds(xas
);
203 static void *xas_descend(struct xa_state
*xas
, struct xa_node
*node
)
205 unsigned int offset
= get_offset(xas
->xa_index
, node
);
206 void *entry
= xa_entry(xas
->xa
, node
, offset
);
209 while (xa_is_sibling(entry
)) {
210 offset
= xa_to_sibling(entry
);
211 entry
= xa_entry(xas
->xa
, node
, offset
);
212 if (node
->shift
&& xa_is_node(entry
))
213 entry
= XA_RETRY_ENTRY
;
216 xas
->xa_offset
= offset
;
221 * xas_load() - Load an entry from the XArray (advanced).
222 * @xas: XArray operation state.
224 * Usually walks the @xas to the appropriate state to load the entry
225 * stored at xa_index. However, it will do nothing and return %NULL if
226 * @xas is in an error state. xas_load() will never expand the tree.
228 * If the xa_state is set up to operate on a multi-index entry, xas_load()
229 * may return %NULL or an internal entry, even if there are entries
230 * present within the range specified by @xas.
232 * Context: Any context. The caller should hold the xa_lock or the RCU lock.
233 * Return: Usually an entry in the XArray, but see description for exceptions.
235 void *xas_load(struct xa_state
*xas
)
237 void *entry
= xas_start(xas
);
239 while (xa_is_node(entry
)) {
240 struct xa_node
*node
= xa_to_node(entry
);
242 if (xas
->xa_shift
> node
->shift
)
244 entry
= xas_descend(xas
, node
);
245 if (node
->shift
== 0)
250 EXPORT_SYMBOL_GPL(xas_load
);
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 * Most users will not need to call this function; it is called for you
268 void xas_destroy(struct xa_state
*xas
)
270 struct xa_node
*next
, *node
= xas
->xa_alloc
;
273 XA_NODE_BUG_ON(node
, !list_empty(&node
->private_list
));
274 next
= rcu_dereference_raw(node
->parent
);
275 radix_tree_node_rcu_free(&node
->rcu_head
);
276 xas
->xa_alloc
= node
= next
;
281 * xas_nomem() - Allocate memory if needed.
282 * @xas: XArray operation state.
283 * @gfp: Memory allocation flags.
285 * If we need to add new nodes to the XArray, we try to allocate memory
286 * with GFP_NOWAIT while holding the lock, which will usually succeed.
287 * If it fails, @xas is flagged as needing memory to continue. The caller
288 * should drop the lock and call xas_nomem(). If xas_nomem() succeeds,
289 * the caller should retry the operation.
291 * Forward progress is guaranteed as one node is allocated here and
292 * stored in the xa_state where it will be found by xas_alloc(). More
293 * nodes will likely be found in the slab allocator, but we do not tie
296 * Return: true if memory was needed, and was successfully allocated.
298 bool xas_nomem(struct xa_state
*xas
, gfp_t gfp
)
300 if (xas
->xa_node
!= XA_ERROR(-ENOMEM
)) {
304 if (xas
->xa
->xa_flags
& XA_FLAGS_ACCOUNT
)
305 gfp
|= __GFP_ACCOUNT
;
306 xas
->xa_alloc
= kmem_cache_alloc_lru(radix_tree_node_cachep
, xas
->xa_lru
, gfp
);
309 xas
->xa_alloc
->parent
= NULL
;
310 XA_NODE_BUG_ON(xas
->xa_alloc
, !list_empty(&xas
->xa_alloc
->private_list
));
311 xas
->xa_node
= XAS_RESTART
;
314 EXPORT_SYMBOL_GPL(xas_nomem
);
317 * __xas_nomem() - Drop locks and allocate memory if needed.
318 * @xas: XArray operation state.
319 * @gfp: Memory allocation flags.
321 * Internal variant of xas_nomem().
323 * Return: true if memory was needed, and was successfully allocated.
325 static bool __xas_nomem(struct xa_state
*xas
, gfp_t gfp
)
326 __must_hold(xas
->xa
->xa_lock
)
328 unsigned int lock_type
= xa_lock_type(xas
->xa
);
330 if (xas
->xa_node
!= XA_ERROR(-ENOMEM
)) {
334 if (xas
->xa
->xa_flags
& XA_FLAGS_ACCOUNT
)
335 gfp
|= __GFP_ACCOUNT
;
336 if (gfpflags_allow_blocking(gfp
)) {
337 xas_unlock_type(xas
, lock_type
);
338 xas
->xa_alloc
= kmem_cache_alloc_lru(radix_tree_node_cachep
, xas
->xa_lru
, gfp
);
339 xas_lock_type(xas
, lock_type
);
341 xas
->xa_alloc
= kmem_cache_alloc_lru(radix_tree_node_cachep
, xas
->xa_lru
, gfp
);
345 xas
->xa_alloc
->parent
= NULL
;
346 XA_NODE_BUG_ON(xas
->xa_alloc
, !list_empty(&xas
->xa_alloc
->private_list
));
347 xas
->xa_node
= XAS_RESTART
;
351 static void xas_update(struct xa_state
*xas
, struct xa_node
*node
)
354 xas
->xa_update(node
);
356 XA_NODE_BUG_ON(node
, !list_empty(&node
->private_list
));
359 static void *xas_alloc(struct xa_state
*xas
, unsigned int shift
)
361 struct xa_node
*parent
= xas
->xa_node
;
362 struct xa_node
*node
= xas
->xa_alloc
;
364 if (xas_invalid(xas
))
368 xas
->xa_alloc
= NULL
;
370 gfp_t gfp
= GFP_NOWAIT
| __GFP_NOWARN
;
372 if (xas
->xa
->xa_flags
& XA_FLAGS_ACCOUNT
)
373 gfp
|= __GFP_ACCOUNT
;
375 node
= kmem_cache_alloc_lru(radix_tree_node_cachep
, xas
->xa_lru
, gfp
);
377 xas_set_err(xas
, -ENOMEM
);
383 node
->offset
= xas
->xa_offset
;
385 XA_NODE_BUG_ON(node
, parent
->count
> XA_CHUNK_SIZE
);
386 xas_update(xas
, parent
);
388 XA_NODE_BUG_ON(node
, shift
> BITS_PER_LONG
);
389 XA_NODE_BUG_ON(node
, !list_empty(&node
->private_list
));
393 RCU_INIT_POINTER(node
->parent
, xas
->xa_node
);
394 node
->array
= xas
->xa
;
399 #ifdef CONFIG_XARRAY_MULTI
400 /* Returns the number of indices covered by a given xa_state */
401 static unsigned long xas_size(const struct xa_state
*xas
)
403 return (xas
->xa_sibs
+ 1UL) << xas
->xa_shift
;
408 * Use this to calculate the maximum index that will need to be created
409 * in order to add the entry described by @xas. Because we cannot store a
410 * multi-index entry at index 0, the calculation is a little more complex
411 * than you might expect.
413 static unsigned long xas_max(struct xa_state
*xas
)
415 unsigned long max
= xas
->xa_index
;
417 #ifdef CONFIG_XARRAY_MULTI
418 if (xas
->xa_shift
|| xas
->xa_sibs
) {
419 unsigned long mask
= xas_size(xas
) - 1;
429 /* The maximum index that can be contained in the array without expanding it */
430 static unsigned long max_index(void *entry
)
432 if (!xa_is_node(entry
))
434 return (XA_CHUNK_SIZE
<< xa_to_node(entry
)->shift
) - 1;
437 static void xas_shrink(struct xa_state
*xas
)
439 struct xarray
*xa
= xas
->xa
;
440 struct xa_node
*node
= xas
->xa_node
;
445 XA_NODE_BUG_ON(node
, node
->count
> XA_CHUNK_SIZE
);
446 if (node
->count
!= 1)
448 entry
= xa_entry_locked(xa
, node
, 0);
451 if (!xa_is_node(entry
) && node
->shift
)
453 if (xa_is_zero(entry
) && xa_zero_busy(xa
))
455 xas
->xa_node
= XAS_BOUNDS
;
457 RCU_INIT_POINTER(xa
->xa_head
, entry
);
458 if (xa_track_free(xa
) && !node_get_mark(node
, 0, XA_FREE_MARK
))
459 xa_mark_clear(xa
, XA_FREE_MARK
);
463 if (!xa_is_node(entry
))
464 RCU_INIT_POINTER(node
->slots
[0], XA_RETRY_ENTRY
);
465 xas_update(xas
, node
);
467 if (!xa_is_node(entry
))
469 node
= xa_to_node(entry
);
475 * xas_delete_node() - Attempt to delete an xa_node
476 * @xas: Array operation state.
478 * Attempts to delete the @xas->xa_node. This will fail if xa->node has
479 * a non-zero reference count.
481 static void xas_delete_node(struct xa_state
*xas
)
483 struct xa_node
*node
= xas
->xa_node
;
486 struct xa_node
*parent
;
488 XA_NODE_BUG_ON(node
, node
->count
> XA_CHUNK_SIZE
);
492 parent
= xa_parent_locked(xas
->xa
, node
);
493 xas
->xa_node
= parent
;
494 xas
->xa_offset
= node
->offset
;
498 xas
->xa
->xa_head
= NULL
;
499 xas
->xa_node
= XAS_BOUNDS
;
503 parent
->slots
[xas
->xa_offset
] = NULL
;
505 XA_NODE_BUG_ON(parent
, parent
->count
> XA_CHUNK_SIZE
);
507 xas_update(xas
, node
);
515 * xas_free_nodes() - Free this node and all nodes that it references
516 * @xas: Array operation state.
519 * This node has been removed from the tree. We must now free it and all
520 * of its subnodes. There may be RCU walkers with references into the tree,
521 * so we must replace all entries with retry markers.
523 static void xas_free_nodes(struct xa_state
*xas
, struct xa_node
*top
)
525 unsigned int offset
= 0;
526 struct xa_node
*node
= top
;
529 void *entry
= xa_entry_locked(xas
->xa
, node
, offset
);
531 if (node
->shift
&& xa_is_node(entry
)) {
532 node
= xa_to_node(entry
);
537 RCU_INIT_POINTER(node
->slots
[offset
], XA_RETRY_ENTRY
);
539 while (offset
== XA_CHUNK_SIZE
) {
540 struct xa_node
*parent
;
542 parent
= xa_parent_locked(xas
->xa
, node
);
543 offset
= node
->offset
+ 1;
546 xas_update(xas
, node
);
556 * xas_expand adds nodes to the head of the tree until it has reached
557 * sufficient height to be able to contain @xas->xa_index
559 static int xas_expand(struct xa_state
*xas
, void *head
)
561 struct xarray
*xa
= xas
->xa
;
562 struct xa_node
*node
= NULL
;
563 unsigned int shift
= 0;
564 unsigned long max
= xas_max(xas
);
569 while ((max
>> shift
) >= XA_CHUNK_SIZE
)
570 shift
+= XA_CHUNK_SHIFT
;
571 return shift
+ XA_CHUNK_SHIFT
;
572 } else if (xa_is_node(head
)) {
573 node
= xa_to_node(head
);
574 shift
= node
->shift
+ XA_CHUNK_SHIFT
;
578 while (max
> max_index(head
)) {
581 XA_NODE_BUG_ON(node
, shift
> BITS_PER_LONG
);
582 node
= xas_alloc(xas
, shift
);
587 if (xa_is_value(head
))
589 RCU_INIT_POINTER(node
->slots
[0], head
);
591 /* Propagate the aggregated mark info to the new child */
593 if (xa_track_free(xa
) && mark
== XA_FREE_MARK
) {
594 node_mark_all(node
, XA_FREE_MARK
);
595 if (!xa_marked(xa
, XA_FREE_MARK
)) {
596 node_clear_mark(node
, 0, XA_FREE_MARK
);
597 xa_mark_set(xa
, XA_FREE_MARK
);
599 } else if (xa_marked(xa
, mark
)) {
600 node_set_mark(node
, 0, mark
);
602 if (mark
== XA_MARK_MAX
)
608 * Now that the new node is fully initialised, we can add
611 if (xa_is_node(head
)) {
612 xa_to_node(head
)->offset
= 0;
613 rcu_assign_pointer(xa_to_node(head
)->parent
, node
);
615 head
= xa_mk_node(node
);
616 rcu_assign_pointer(xa
->xa_head
, head
);
617 xas_update(xas
, node
);
619 shift
+= XA_CHUNK_SHIFT
;
627 * xas_create() - Create a slot to store an entry in.
628 * @xas: XArray operation state.
629 * @allow_root: %true if we can store the entry in the root directly
631 * Most users will not need to call this function directly, as it is called
632 * by xas_store(). It is useful for doing conditional store operations
633 * (see the xa_cmpxchg() implementation for an example).
635 * Return: If the slot already existed, returns the contents of this slot.
636 * If the slot was newly created, returns %NULL. If it failed to create the
637 * slot, returns %NULL and indicates the error in @xas.
639 static void *xas_create(struct xa_state
*xas
, bool allow_root
)
641 struct xarray
*xa
= xas
->xa
;
644 struct xa_node
*node
= xas
->xa_node
;
646 unsigned int order
= xas
->xa_shift
;
649 entry
= xa_head_locked(xa
);
651 if (!entry
&& xa_zero_busy(xa
))
652 entry
= XA_ZERO_ENTRY
;
653 shift
= xas_expand(xas
, entry
);
656 if (!shift
&& !allow_root
)
657 shift
= XA_CHUNK_SHIFT
;
658 entry
= xa_head_locked(xa
);
660 } else if (xas_error(xas
)) {
663 unsigned int offset
= xas
->xa_offset
;
666 entry
= xa_entry_locked(xa
, node
, offset
);
667 slot
= &node
->slots
[offset
];
670 entry
= xa_head_locked(xa
);
674 while (shift
> order
) {
675 shift
-= XA_CHUNK_SHIFT
;
677 node
= xas_alloc(xas
, shift
);
680 if (xa_track_free(xa
))
681 node_mark_all(node
, XA_FREE_MARK
);
682 rcu_assign_pointer(*slot
, xa_mk_node(node
));
683 } else if (xa_is_node(entry
)) {
684 node
= xa_to_node(entry
);
688 entry
= xas_descend(xas
, node
);
689 slot
= &node
->slots
[xas
->xa_offset
];
696 * xas_create_range() - Ensure that stores to this range will succeed
697 * @xas: XArray operation state.
699 * Creates all of the slots in the range covered by @xas. Sets @xas to
700 * create single-index entries and positions it at the beginning of the
701 * range. This is for the benefit of users which have not yet been
702 * converted to use multi-index entries.
704 void xas_create_range(struct xa_state
*xas
)
706 unsigned long index
= xas
->xa_index
;
707 unsigned char shift
= xas
->xa_shift
;
708 unsigned char sibs
= xas
->xa_sibs
;
710 xas
->xa_index
|= ((sibs
+ 1UL) << shift
) - 1;
711 if (xas_is_node(xas
) && xas
->xa_node
->shift
== xas
->xa_shift
)
712 xas
->xa_offset
|= sibs
;
717 xas_create(xas
, true);
720 if (xas
->xa_index
<= (index
| XA_CHUNK_MASK
))
722 xas
->xa_index
-= XA_CHUNK_SIZE
;
725 struct xa_node
*node
= xas
->xa_node
;
726 if (node
->shift
>= shift
)
728 xas
->xa_node
= xa_parent_locked(xas
->xa
, node
);
729 xas
->xa_offset
= node
->offset
- 1;
730 if (node
->offset
!= 0)
736 xas
->xa_shift
= shift
;
738 xas
->xa_index
= index
;
741 xas
->xa_index
= index
;
745 EXPORT_SYMBOL_GPL(xas_create_range
);
747 static void update_node(struct xa_state
*xas
, struct xa_node
*node
,
748 int count
, int values
)
750 if (!node
|| (!count
&& !values
))
753 node
->count
+= count
;
754 node
->nr_values
+= values
;
755 XA_NODE_BUG_ON(node
, node
->count
> XA_CHUNK_SIZE
);
756 XA_NODE_BUG_ON(node
, node
->nr_values
> XA_CHUNK_SIZE
);
757 xas_update(xas
, node
);
759 xas_delete_node(xas
);
763 * xas_store() - Store this entry in the XArray.
764 * @xas: XArray operation state.
767 * If @xas is operating on a multi-index entry, the entry returned by this
768 * function is essentially meaningless (it may be an internal entry or it
769 * may be %NULL, even if there are non-NULL entries at some of the indices
770 * covered by the range). This is not a problem for any current users,
771 * and can be changed if needed.
773 * Return: The old entry at this index.
775 void *xas_store(struct xa_state
*xas
, void *entry
)
777 struct xa_node
*node
;
778 void __rcu
**slot
= &xas
->xa
->xa_head
;
779 unsigned int offset
, max
;
783 bool value
= xa_is_value(entry
);
786 bool allow_root
= !xa_is_node(entry
) && !xa_is_zero(entry
);
787 first
= xas_create(xas
, allow_root
);
789 first
= xas_load(xas
);
792 if (xas_invalid(xas
))
795 if (node
&& (xas
->xa_shift
< node
->shift
))
797 if ((first
== entry
) && !xas
->xa_sibs
)
801 offset
= xas
->xa_offset
;
802 max
= xas
->xa_offset
+ xas
->xa_sibs
;
804 slot
= &node
->slots
[offset
];
806 xas_squash_marks(xas
);
813 * Must clear the marks before setting the entry to NULL,
814 * otherwise xas_for_each_marked may find a NULL entry and
815 * stop early. rcu_assign_pointer contains a release barrier
816 * so the mark clearing will appear to happen before the
817 * entry is set to NULL.
819 rcu_assign_pointer(*slot
, entry
);
820 if (xa_is_node(next
) && (!node
|| node
->shift
))
821 xas_free_nodes(xas
, xa_to_node(next
));
824 count
+= !next
- !entry
;
825 values
+= !xa_is_value(first
) - !value
;
829 if (!xa_is_sibling(entry
))
830 entry
= xa_mk_sibling(xas
->xa_offset
);
832 if (offset
== XA_CHUNK_MASK
)
835 next
= xa_entry_locked(xas
->xa
, node
, ++offset
);
836 if (!xa_is_sibling(next
)) {
837 if (!entry
&& (offset
> max
))
844 update_node(xas
, node
, count
, values
);
847 EXPORT_SYMBOL_GPL(xas_store
);
850 * xas_get_mark() - Returns the state of this mark.
851 * @xas: XArray operation state.
852 * @mark: Mark number.
854 * Return: true if the mark is set, false if the mark is clear or @xas
855 * is in an error state.
857 bool xas_get_mark(const struct xa_state
*xas
, xa_mark_t mark
)
859 if (xas_invalid(xas
))
862 return xa_marked(xas
->xa
, mark
);
863 return node_get_mark(xas
->xa_node
, xas
->xa_offset
, mark
);
865 EXPORT_SYMBOL_GPL(xas_get_mark
);
868 * xas_set_mark() - Sets the mark on this entry and its parents.
869 * @xas: XArray operation state.
870 * @mark: Mark number.
872 * Sets the specified mark on this entry, and walks up the tree setting it
873 * on all the ancestor entries. Does nothing if @xas has not been walked to
874 * an entry, or is in an error state.
876 void xas_set_mark(const struct xa_state
*xas
, xa_mark_t mark
)
878 struct xa_node
*node
= xas
->xa_node
;
879 unsigned int offset
= xas
->xa_offset
;
881 if (xas_invalid(xas
))
885 if (node_set_mark(node
, offset
, mark
))
887 offset
= node
->offset
;
888 node
= xa_parent_locked(xas
->xa
, node
);
891 if (!xa_marked(xas
->xa
, mark
))
892 xa_mark_set(xas
->xa
, mark
);
894 EXPORT_SYMBOL_GPL(xas_set_mark
);
897 * xas_clear_mark() - Clears the mark on this entry and its parents.
898 * @xas: XArray operation state.
899 * @mark: Mark number.
901 * Clears the specified mark on this entry, and walks back to the head
902 * attempting to clear it on all the ancestor entries. Does nothing if
903 * @xas has not been walked to an entry, or is in an error state.
905 void xas_clear_mark(const struct xa_state
*xas
, xa_mark_t mark
)
907 struct xa_node
*node
= xas
->xa_node
;
908 unsigned int offset
= xas
->xa_offset
;
910 if (xas_invalid(xas
))
914 if (!node_clear_mark(node
, offset
, mark
))
916 if (node_any_mark(node
, mark
))
919 offset
= node
->offset
;
920 node
= xa_parent_locked(xas
->xa
, node
);
923 if (xa_marked(xas
->xa
, mark
))
924 xa_mark_clear(xas
->xa
, mark
);
926 EXPORT_SYMBOL_GPL(xas_clear_mark
);
929 * xas_init_marks() - Initialise all marks for the entry
930 * @xas: Array operations state.
932 * Initialise all marks for the entry specified by @xas. If we're tracking
933 * free entries with a mark, we need to set it on all entries. All other
936 * This implementation is not as efficient as it could be; we may walk
937 * up the tree multiple times.
939 void xas_init_marks(const struct xa_state
*xas
)
944 if (xa_track_free(xas
->xa
) && mark
== XA_FREE_MARK
)
945 xas_set_mark(xas
, mark
);
947 xas_clear_mark(xas
, mark
);
948 if (mark
== XA_MARK_MAX
)
953 EXPORT_SYMBOL_GPL(xas_init_marks
);
955 #ifdef CONFIG_XARRAY_MULTI
956 static unsigned int node_get_marks(struct xa_node
*node
, unsigned int offset
)
958 unsigned int marks
= 0;
959 xa_mark_t mark
= XA_MARK_0
;
962 if (node_get_mark(node
, offset
, mark
))
963 marks
|= 1 << (__force
unsigned int)mark
;
964 if (mark
== XA_MARK_MAX
)
972 static void node_set_marks(struct xa_node
*node
, unsigned int offset
,
973 struct xa_node
*child
, unsigned int marks
)
975 xa_mark_t mark
= XA_MARK_0
;
978 if (marks
& (1 << (__force
unsigned int)mark
)) {
979 node_set_mark(node
, offset
, mark
);
981 node_mark_all(child
, mark
);
983 if (mark
== XA_MARK_MAX
)
990 * xas_split_alloc() - Allocate memory for splitting an entry.
991 * @xas: XArray operation state.
992 * @entry: New entry which will be stored in the array.
993 * @order: Current entry order.
994 * @gfp: Memory allocation flags.
996 * This function should be called before calling xas_split().
997 * If necessary, it will allocate new nodes (and fill them with @entry)
998 * to prepare for the upcoming split of an entry of @order size into
999 * entries of the order stored in the @xas.
1001 * Context: May sleep if @gfp flags permit.
1003 void xas_split_alloc(struct xa_state
*xas
, void *entry
, unsigned int order
,
1006 unsigned int sibs
= (1 << (order
% XA_CHUNK_SHIFT
)) - 1;
1007 unsigned int mask
= xas
->xa_sibs
;
1009 /* XXX: no support for splitting really large entries yet */
1010 if (WARN_ON(xas
->xa_shift
+ 2 * XA_CHUNK_SHIFT
< order
))
1012 if (xas
->xa_shift
+ XA_CHUNK_SHIFT
> order
)
1017 void *sibling
= NULL
;
1018 struct xa_node
*node
;
1020 node
= kmem_cache_alloc_lru(radix_tree_node_cachep
, xas
->xa_lru
, gfp
);
1023 node
->array
= xas
->xa
;
1024 for (i
= 0; i
< XA_CHUNK_SIZE
; i
++) {
1025 if ((i
& mask
) == 0) {
1026 RCU_INIT_POINTER(node
->slots
[i
], entry
);
1027 sibling
= xa_mk_sibling(i
);
1029 RCU_INIT_POINTER(node
->slots
[i
], sibling
);
1032 RCU_INIT_POINTER(node
->parent
, xas
->xa_alloc
);
1033 xas
->xa_alloc
= node
;
1034 } while (sibs
-- > 0);
1039 xas_set_err(xas
, -ENOMEM
);
1041 EXPORT_SYMBOL_GPL(xas_split_alloc
);
1044 * xas_split() - Split a multi-index entry into smaller entries.
1045 * @xas: XArray operation state.
1046 * @entry: New entry to store in the array.
1047 * @order: Current entry order.
1049 * The size of the new entries is set in @xas. The value in @entry is
1050 * copied to all the replacement entries.
1052 * Context: Any context. The caller should hold the xa_lock.
1054 void xas_split(struct xa_state
*xas
, void *entry
, unsigned int order
)
1056 unsigned int sibs
= (1 << (order
% XA_CHUNK_SHIFT
)) - 1;
1057 unsigned int offset
, marks
;
1058 struct xa_node
*node
;
1059 void *curr
= xas_load(xas
);
1062 node
= xas
->xa_node
;
1066 marks
= node_get_marks(node
, xas
->xa_offset
);
1068 offset
= xas
->xa_offset
+ sibs
;
1070 if (xas
->xa_shift
< node
->shift
) {
1071 struct xa_node
*child
= xas
->xa_alloc
;
1073 xas
->xa_alloc
= rcu_dereference_raw(child
->parent
);
1074 child
->shift
= node
->shift
- XA_CHUNK_SHIFT
;
1075 child
->offset
= offset
;
1076 child
->count
= XA_CHUNK_SIZE
;
1077 child
->nr_values
= xa_is_value(entry
) ?
1079 RCU_INIT_POINTER(child
->parent
, node
);
1080 node_set_marks(node
, offset
, child
, marks
);
1081 rcu_assign_pointer(node
->slots
[offset
],
1083 if (xa_is_value(curr
))
1085 xas_update(xas
, child
);
1087 unsigned int canon
= offset
- xas
->xa_sibs
;
1089 node_set_marks(node
, canon
, NULL
, marks
);
1090 rcu_assign_pointer(node
->slots
[canon
], entry
);
1091 while (offset
> canon
)
1092 rcu_assign_pointer(node
->slots
[offset
--],
1093 xa_mk_sibling(canon
));
1094 values
+= (xa_is_value(entry
) - xa_is_value(curr
)) *
1097 } while (offset
-- > xas
->xa_offset
);
1099 node
->nr_values
+= values
;
1100 xas_update(xas
, node
);
1102 EXPORT_SYMBOL_GPL(xas_split
);
1106 * xas_pause() - Pause a walk to drop a lock.
1107 * @xas: XArray operation state.
1109 * Some users need to pause a walk and drop the lock they're holding in
1110 * order to yield to a higher priority thread or carry out an operation
1111 * on an entry. Those users should call this function before they drop
1112 * the lock. It resets the @xas to be suitable for the next iteration
1113 * of the loop after the user has reacquired the lock. If most entries
1114 * found during a walk require you to call xas_pause(), the xa_for_each()
1115 * iterator may be more appropriate.
1117 * Note that xas_pause() only works for forward iteration. If a user needs
1118 * to pause a reverse iteration, we will need a xas_pause_rev().
1120 void xas_pause(struct xa_state
*xas
)
1122 struct xa_node
*node
= xas
->xa_node
;
1124 if (xas_invalid(xas
))
1127 xas
->xa_node
= XAS_RESTART
;
1129 unsigned long offset
= xas
->xa_offset
;
1130 while (++offset
< XA_CHUNK_SIZE
) {
1131 if (!xa_is_sibling(xa_entry(xas
->xa
, node
, offset
)))
1134 xas
->xa_index
+= (offset
- xas
->xa_offset
) << node
->shift
;
1135 if (xas
->xa_index
== 0)
1136 xas
->xa_node
= XAS_BOUNDS
;
1141 EXPORT_SYMBOL_GPL(xas_pause
);
1144 * __xas_prev() - Find the previous entry in the XArray.
1145 * @xas: XArray operation state.
1147 * Helper function for xas_prev() which handles all the complex cases
1150 void *__xas_prev(struct xa_state
*xas
)
1154 if (!xas_frozen(xas
->xa_node
))
1157 return set_bounds(xas
);
1158 if (xas_not_node(xas
->xa_node
))
1159 return xas_load(xas
);
1161 if (xas
->xa_offset
!= get_offset(xas
->xa_index
, xas
->xa_node
))
1164 while (xas
->xa_offset
== 255) {
1165 xas
->xa_offset
= xas
->xa_node
->offset
- 1;
1166 xas
->xa_node
= xa_parent(xas
->xa
, xas
->xa_node
);
1168 return set_bounds(xas
);
1172 entry
= xa_entry(xas
->xa
, xas
->xa_node
, xas
->xa_offset
);
1173 if (!xa_is_node(entry
))
1176 xas
->xa_node
= xa_to_node(entry
);
1177 xas_set_offset(xas
);
1180 EXPORT_SYMBOL_GPL(__xas_prev
);
1183 * __xas_next() - Find the next entry in the XArray.
1184 * @xas: XArray operation state.
1186 * Helper function for xas_next() which handles all the complex cases
1189 void *__xas_next(struct xa_state
*xas
)
1193 if (!xas_frozen(xas
->xa_node
))
1196 return set_bounds(xas
);
1197 if (xas_not_node(xas
->xa_node
))
1198 return xas_load(xas
);
1200 if (xas
->xa_offset
!= get_offset(xas
->xa_index
, xas
->xa_node
))
1203 while (xas
->xa_offset
== XA_CHUNK_SIZE
) {
1204 xas
->xa_offset
= xas
->xa_node
->offset
+ 1;
1205 xas
->xa_node
= xa_parent(xas
->xa
, xas
->xa_node
);
1207 return set_bounds(xas
);
1211 entry
= xa_entry(xas
->xa
, xas
->xa_node
, xas
->xa_offset
);
1212 if (!xa_is_node(entry
))
1215 xas
->xa_node
= xa_to_node(entry
);
1216 xas_set_offset(xas
);
1219 EXPORT_SYMBOL_GPL(__xas_next
);
1222 * xas_find() - Find the next present entry in the XArray.
1223 * @xas: XArray operation state.
1224 * @max: Highest index to return.
1226 * If the @xas has not yet been walked to an entry, return the entry
1227 * which has an index >= xas.xa_index. If it has been walked, the entry
1228 * currently being pointed at has been processed, and so we move to the
1231 * If no entry is found and the array is smaller than @max, the iterator
1232 * is set to the smallest index not yet in the array. This allows @xas
1233 * to be immediately passed to xas_store().
1235 * Return: The entry, if found, otherwise %NULL.
1237 void *xas_find(struct xa_state
*xas
, unsigned long max
)
1241 if (xas_error(xas
) || xas
->xa_node
== XAS_BOUNDS
)
1243 if (xas
->xa_index
> max
)
1244 return set_bounds(xas
);
1246 if (!xas
->xa_node
) {
1248 return set_bounds(xas
);
1249 } else if (xas
->xa_node
== XAS_RESTART
) {
1250 entry
= xas_load(xas
);
1251 if (entry
|| xas_not_node(xas
->xa_node
))
1253 } else if (!xas
->xa_node
->shift
&&
1254 xas
->xa_offset
!= (xas
->xa_index
& XA_CHUNK_MASK
)) {
1255 xas
->xa_offset
= ((xas
->xa_index
- 1) & XA_CHUNK_MASK
) + 1;
1258 xas_next_offset(xas
);
1260 while (xas
->xa_node
&& (xas
->xa_index
<= max
)) {
1261 if (unlikely(xas
->xa_offset
== XA_CHUNK_SIZE
)) {
1262 xas
->xa_offset
= xas
->xa_node
->offset
+ 1;
1263 xas
->xa_node
= xa_parent(xas
->xa
, xas
->xa_node
);
1267 entry
= xa_entry(xas
->xa
, xas
->xa_node
, xas
->xa_offset
);
1268 if (xa_is_node(entry
)) {
1269 xas
->xa_node
= xa_to_node(entry
);
1273 if (entry
&& !xa_is_sibling(entry
))
1276 xas_next_offset(xas
);
1280 xas
->xa_node
= XAS_BOUNDS
;
1283 EXPORT_SYMBOL_GPL(xas_find
);
1286 * xas_find_marked() - Find the next marked entry in the XArray.
1287 * @xas: XArray operation state.
1288 * @max: Highest index to return.
1289 * @mark: Mark number to search for.
1291 * If the @xas has not yet been walked to an entry, return the marked entry
1292 * which has an index >= xas.xa_index. If it has been walked, the entry
1293 * currently being pointed at has been processed, and so we return the
1294 * first marked entry with an index > xas.xa_index.
1296 * If no marked entry is found and the array is smaller than @max, @xas is
1297 * set to the bounds state and xas->xa_index is set to the smallest index
1298 * not yet in the array. This allows @xas to be immediately passed to
1301 * If no entry is found before @max is reached, @xas is set to the restart
1304 * Return: The entry, if found, otherwise %NULL.
1306 void *xas_find_marked(struct xa_state
*xas
, unsigned long max
, xa_mark_t mark
)
1308 bool advance
= true;
1309 unsigned int offset
;
1314 if (xas
->xa_index
> max
)
1317 if (!xas
->xa_node
) {
1320 } else if (xas_top(xas
->xa_node
)) {
1322 entry
= xa_head(xas
->xa
);
1323 xas
->xa_node
= NULL
;
1324 if (xas
->xa_index
> max_index(entry
))
1326 if (!xa_is_node(entry
)) {
1327 if (xa_marked(xas
->xa
, mark
))
1332 xas
->xa_node
= xa_to_node(entry
);
1333 xas
->xa_offset
= xas
->xa_index
>> xas
->xa_node
->shift
;
1336 while (xas
->xa_index
<= max
) {
1337 if (unlikely(xas
->xa_offset
== XA_CHUNK_SIZE
)) {
1338 xas
->xa_offset
= xas
->xa_node
->offset
+ 1;
1339 xas
->xa_node
= xa_parent(xas
->xa
, xas
->xa_node
);
1347 entry
= xa_entry(xas
->xa
, xas
->xa_node
, xas
->xa_offset
);
1348 if (xa_is_sibling(entry
)) {
1349 xas
->xa_offset
= xa_to_sibling(entry
);
1350 xas_move_index(xas
, xas
->xa_offset
);
1354 offset
= xas_find_chunk(xas
, advance
, mark
);
1355 if (offset
> xas
->xa_offset
) {
1357 xas_move_index(xas
, offset
);
1359 if ((xas
->xa_index
- 1) >= max
)
1361 xas
->xa_offset
= offset
;
1362 if (offset
== XA_CHUNK_SIZE
)
1366 entry
= xa_entry(xas
->xa
, xas
->xa_node
, xas
->xa_offset
);
1367 if (!entry
&& !(xa_track_free(xas
->xa
) && mark
== XA_FREE_MARK
))
1369 if (!xa_is_node(entry
))
1371 xas
->xa_node
= xa_to_node(entry
);
1372 xas_set_offset(xas
);
1376 if (xas
->xa_index
> max
)
1378 return set_bounds(xas
);
1380 xas
->xa_node
= XAS_RESTART
;
1383 EXPORT_SYMBOL_GPL(xas_find_marked
);
1386 * xas_find_conflict() - Find the next present entry in a range.
1387 * @xas: XArray operation state.
1389 * The @xas describes both a range and a position within that range.
1391 * Context: Any context. Expects xa_lock to be held.
1392 * Return: The next entry in the range covered by @xas or %NULL.
1394 void *xas_find_conflict(struct xa_state
*xas
)
1404 if (xas_top(xas
->xa_node
)) {
1405 curr
= xas_start(xas
);
1408 while (xa_is_node(curr
)) {
1409 struct xa_node
*node
= xa_to_node(curr
);
1410 curr
= xas_descend(xas
, node
);
1416 if (xas
->xa_node
->shift
> xas
->xa_shift
)
1420 if (xas
->xa_node
->shift
== xas
->xa_shift
) {
1421 if ((xas
->xa_offset
& xas
->xa_sibs
) == xas
->xa_sibs
)
1423 } else if (xas
->xa_offset
== XA_CHUNK_MASK
) {
1424 xas
->xa_offset
= xas
->xa_node
->offset
;
1425 xas
->xa_node
= xa_parent_locked(xas
->xa
, xas
->xa_node
);
1430 curr
= xa_entry_locked(xas
->xa
, xas
->xa_node
, ++xas
->xa_offset
);
1431 if (xa_is_sibling(curr
))
1433 while (xa_is_node(curr
)) {
1434 xas
->xa_node
= xa_to_node(curr
);
1436 curr
= xa_entry_locked(xas
->xa
, xas
->xa_node
, 0);
1441 xas
->xa_offset
-= xas
->xa_sibs
;
1444 EXPORT_SYMBOL_GPL(xas_find_conflict
);
1447 * xa_load() - Load an entry from an XArray.
1449 * @index: index into array.
1451 * Context: Any context. Takes and releases the RCU lock.
1452 * Return: The entry at @index in @xa.
1454 void *xa_load(struct xarray
*xa
, unsigned long index
)
1456 XA_STATE(xas
, xa
, index
);
1461 entry
= xas_load(&xas
);
1462 if (xa_is_zero(entry
))
1464 } while (xas_retry(&xas
, entry
));
1469 EXPORT_SYMBOL(xa_load
);
1471 static void *xas_result(struct xa_state
*xas
, void *curr
)
1473 if (xa_is_zero(curr
))
1476 curr
= xas
->xa_node
;
1481 * __xa_erase() - Erase this entry from the XArray while locked.
1483 * @index: Index into array.
1485 * After this function returns, loading from @index will return %NULL.
1486 * If the index is part of a multi-index entry, all indices will be erased
1487 * and none of the entries will be part of a multi-index entry.
1489 * Context: Any context. Expects xa_lock to be held on entry.
1490 * Return: The entry which used to be at this index.
1492 void *__xa_erase(struct xarray
*xa
, unsigned long index
)
1494 XA_STATE(xas
, xa
, index
);
1495 return xas_result(&xas
, xas_store(&xas
, NULL
));
1497 EXPORT_SYMBOL(__xa_erase
);
1500 * xa_erase() - Erase this entry from the XArray.
1502 * @index: Index of entry.
1504 * After this function returns, loading from @index will return %NULL.
1505 * If the index is part of a multi-index entry, all indices will be erased
1506 * and none of the entries will be part of a multi-index entry.
1508 * Context: Any context. Takes and releases the xa_lock.
1509 * Return: The entry which used to be at this index.
1511 void *xa_erase(struct xarray
*xa
, unsigned long index
)
1516 entry
= __xa_erase(xa
, index
);
1521 EXPORT_SYMBOL(xa_erase
);
1524 * __xa_store() - Store this entry in the XArray.
1526 * @index: Index into array.
1527 * @entry: New entry.
1528 * @gfp: Memory allocation flags.
1530 * You must already be holding the xa_lock when calling this function.
1531 * It will drop the lock if needed to allocate memory, and then reacquire
1534 * Context: Any context. Expects xa_lock to be held on entry. May
1535 * release and reacquire xa_lock if @gfp flags permit.
1536 * Return: The old entry at this index or xa_err() if an error happened.
1538 void *__xa_store(struct xarray
*xa
, unsigned long index
, void *entry
, gfp_t gfp
)
1540 XA_STATE(xas
, xa
, index
);
1543 if (WARN_ON_ONCE(xa_is_advanced(entry
)))
1544 return XA_ERROR(-EINVAL
);
1545 if (xa_track_free(xa
) && !entry
)
1546 entry
= XA_ZERO_ENTRY
;
1549 curr
= xas_store(&xas
, entry
);
1550 if (xa_track_free(xa
))
1551 xas_clear_mark(&xas
, XA_FREE_MARK
);
1552 } while (__xas_nomem(&xas
, gfp
));
1554 return xas_result(&xas
, curr
);
1556 EXPORT_SYMBOL(__xa_store
);
1559 * xa_store() - Store this entry in the XArray.
1561 * @index: Index into array.
1562 * @entry: New entry.
1563 * @gfp: Memory allocation flags.
1565 * After this function returns, loads from this index will return @entry.
1566 * Storing into an existing multi-index entry updates the entry of every index.
1567 * The marks associated with @index are unaffected unless @entry is %NULL.
1569 * Context: Any context. Takes and releases the xa_lock.
1570 * May sleep if the @gfp flags permit.
1571 * Return: The old entry at this index on success, xa_err(-EINVAL) if @entry
1572 * cannot be stored in an XArray, or xa_err(-ENOMEM) if memory allocation
1575 void *xa_store(struct xarray
*xa
, unsigned long index
, void *entry
, gfp_t gfp
)
1580 curr
= __xa_store(xa
, index
, entry
, gfp
);
1585 EXPORT_SYMBOL(xa_store
);
1588 * __xa_cmpxchg() - Store this entry in the XArray.
1590 * @index: Index into array.
1591 * @old: Old value to test against.
1592 * @entry: New entry.
1593 * @gfp: Memory allocation flags.
1595 * You must already be holding the xa_lock when calling this function.
1596 * It will drop the lock if needed to allocate memory, and then reacquire
1599 * Context: Any context. Expects xa_lock to be held on entry. May
1600 * release and reacquire xa_lock if @gfp flags permit.
1601 * Return: The old entry at this index or xa_err() if an error happened.
1603 void *__xa_cmpxchg(struct xarray
*xa
, unsigned long index
,
1604 void *old
, void *entry
, gfp_t gfp
)
1606 XA_STATE(xas
, xa
, index
);
1609 if (WARN_ON_ONCE(xa_is_advanced(entry
)))
1610 return XA_ERROR(-EINVAL
);
1613 curr
= xas_load(&xas
);
1615 xas_store(&xas
, entry
);
1616 if (xa_track_free(xa
) && entry
&& !curr
)
1617 xas_clear_mark(&xas
, XA_FREE_MARK
);
1619 } while (__xas_nomem(&xas
, gfp
));
1621 return xas_result(&xas
, curr
);
1623 EXPORT_SYMBOL(__xa_cmpxchg
);
1626 * __xa_insert() - Store this entry in the XArray if no entry is present.
1628 * @index: Index into array.
1629 * @entry: New entry.
1630 * @gfp: Memory allocation flags.
1632 * Inserting a NULL entry will store a reserved entry (like xa_reserve())
1633 * if no entry is present. Inserting will fail if a reserved entry is
1634 * present, even though loading from this index will return NULL.
1636 * Context: Any context. Expects xa_lock to be held on entry. May
1637 * release and reacquire xa_lock if @gfp flags permit.
1638 * Return: 0 if the store succeeded. -EBUSY if another entry was present.
1639 * -ENOMEM if memory could not be allocated.
1641 int __xa_insert(struct xarray
*xa
, unsigned long index
, void *entry
, gfp_t gfp
)
1643 XA_STATE(xas
, xa
, index
);
1646 if (WARN_ON_ONCE(xa_is_advanced(entry
)))
1649 entry
= XA_ZERO_ENTRY
;
1652 curr
= xas_load(&xas
);
1654 xas_store(&xas
, entry
);
1655 if (xa_track_free(xa
))
1656 xas_clear_mark(&xas
, XA_FREE_MARK
);
1658 xas_set_err(&xas
, -EBUSY
);
1660 } while (__xas_nomem(&xas
, gfp
));
1662 return xas_error(&xas
);
1664 EXPORT_SYMBOL(__xa_insert
);
1666 #ifdef CONFIG_XARRAY_MULTI
1667 static void xas_set_range(struct xa_state
*xas
, unsigned long first
,
1670 unsigned int shift
= 0;
1671 unsigned long sibs
= last
- first
;
1672 unsigned int offset
= XA_CHUNK_MASK
;
1674 xas_set(xas
, first
);
1676 while ((first
& XA_CHUNK_MASK
) == 0) {
1677 if (sibs
< XA_CHUNK_MASK
)
1679 if ((sibs
== XA_CHUNK_MASK
) && (offset
< XA_CHUNK_MASK
))
1681 shift
+= XA_CHUNK_SHIFT
;
1682 if (offset
== XA_CHUNK_MASK
)
1683 offset
= sibs
& XA_CHUNK_MASK
;
1684 sibs
>>= XA_CHUNK_SHIFT
;
1685 first
>>= XA_CHUNK_SHIFT
;
1688 offset
= first
& XA_CHUNK_MASK
;
1689 if (offset
+ sibs
> XA_CHUNK_MASK
)
1690 sibs
= XA_CHUNK_MASK
- offset
;
1691 if ((((first
+ sibs
+ 1) << shift
) - 1) > last
)
1694 xas
->xa_shift
= shift
;
1695 xas
->xa_sibs
= sibs
;
1699 * xa_store_range() - Store this entry at a range of indices in the XArray.
1701 * @first: First index to affect.
1702 * @last: Last index to affect.
1703 * @entry: New entry.
1704 * @gfp: Memory allocation flags.
1706 * After this function returns, loads from any index between @first and @last,
1707 * inclusive will return @entry.
1708 * Storing into an existing multi-index entry updates the entry of every index.
1709 * The marks associated with @index are unaffected unless @entry is %NULL.
1711 * Context: Process context. Takes and releases the xa_lock. May sleep
1712 * if the @gfp flags permit.
1713 * Return: %NULL on success, xa_err(-EINVAL) if @entry cannot be stored in
1714 * an XArray, or xa_err(-ENOMEM) if memory allocation failed.
1716 void *xa_store_range(struct xarray
*xa
, unsigned long first
,
1717 unsigned long last
, void *entry
, gfp_t gfp
)
1719 XA_STATE(xas
, xa
, 0);
1721 if (WARN_ON_ONCE(xa_is_internal(entry
)))
1722 return XA_ERROR(-EINVAL
);
1724 return XA_ERROR(-EINVAL
);
1729 unsigned int order
= BITS_PER_LONG
;
1731 order
= __ffs(last
+ 1);
1732 xas_set_order(&xas
, last
, order
);
1733 xas_create(&xas
, true);
1734 if (xas_error(&xas
))
1738 xas_set_range(&xas
, first
, last
);
1739 xas_store(&xas
, entry
);
1740 if (xas_error(&xas
))
1742 first
+= xas_size(&xas
);
1743 } while (first
<= last
);
1746 } while (xas_nomem(&xas
, gfp
));
1748 return xas_result(&xas
, NULL
);
1750 EXPORT_SYMBOL(xa_store_range
);
1753 * xa_get_order() - Get the order of an entry.
1755 * @index: Index of the entry.
1757 * Return: A number between 0 and 63 indicating the order of the entry.
1759 int xa_get_order(struct xarray
*xa
, unsigned long index
)
1761 XA_STATE(xas
, xa
, index
);
1766 entry
= xas_load(&xas
);
1775 unsigned int slot
= xas
.xa_offset
+ (1 << order
);
1777 if (slot
>= XA_CHUNK_SIZE
)
1779 if (!xa_is_sibling(xas
.xa_node
->slots
[slot
]))
1784 order
+= xas
.xa_node
->shift
;
1790 EXPORT_SYMBOL(xa_get_order
);
1791 #endif /* CONFIG_XARRAY_MULTI */
1794 * __xa_alloc() - Find somewhere to store this entry in the XArray.
1796 * @id: Pointer to ID.
1797 * @limit: Range for allocated ID.
1798 * @entry: New entry.
1799 * @gfp: Memory allocation flags.
1801 * Finds an empty entry in @xa between @limit.min and @limit.max,
1802 * stores the index into the @id pointer, then stores the entry at
1803 * that index. A concurrent lookup will not see an uninitialised @id.
1805 * Must only be operated on an xarray initialized with flag XA_FLAGS_ALLOC set
1806 * in xa_init_flags().
1808 * Context: Any context. Expects xa_lock to be held on entry. May
1809 * release and reacquire xa_lock if @gfp flags permit.
1810 * Return: 0 on success, -ENOMEM if memory could not be allocated or
1811 * -EBUSY if there are no free entries in @limit.
1813 int __xa_alloc(struct xarray
*xa
, u32
*id
, void *entry
,
1814 struct xa_limit limit
, gfp_t gfp
)
1816 XA_STATE(xas
, xa
, 0);
1818 if (WARN_ON_ONCE(xa_is_advanced(entry
)))
1820 if (WARN_ON_ONCE(!xa_track_free(xa
)))
1824 entry
= XA_ZERO_ENTRY
;
1827 xas
.xa_index
= limit
.min
;
1828 xas_find_marked(&xas
, limit
.max
, XA_FREE_MARK
);
1829 if (xas
.xa_node
== XAS_RESTART
)
1830 xas_set_err(&xas
, -EBUSY
);
1833 xas_store(&xas
, entry
);
1834 xas_clear_mark(&xas
, XA_FREE_MARK
);
1835 } while (__xas_nomem(&xas
, gfp
));
1837 return xas_error(&xas
);
1839 EXPORT_SYMBOL(__xa_alloc
);
1842 * __xa_alloc_cyclic() - Find somewhere to store this entry in the XArray.
1844 * @id: Pointer to ID.
1845 * @entry: New entry.
1846 * @limit: Range of allocated ID.
1847 * @next: Pointer to next ID to allocate.
1848 * @gfp: Memory allocation flags.
1850 * Finds an empty entry in @xa between @limit.min and @limit.max,
1851 * stores the index into the @id pointer, then stores the entry at
1852 * that index. A concurrent lookup will not see an uninitialised @id.
1853 * The search for an empty entry will start at @next and will wrap
1854 * around if necessary.
1856 * Must only be operated on an xarray initialized with flag XA_FLAGS_ALLOC set
1857 * in xa_init_flags().
1859 * Context: Any context. Expects xa_lock to be held on entry. May
1860 * release and reacquire xa_lock if @gfp flags permit.
1861 * Return: 0 if the allocation succeeded without wrapping. 1 if the
1862 * allocation succeeded after wrapping, -ENOMEM if memory could not be
1863 * allocated or -EBUSY if there are no free entries in @limit.
1865 int __xa_alloc_cyclic(struct xarray
*xa
, u32
*id
, void *entry
,
1866 struct xa_limit limit
, u32
*next
, gfp_t gfp
)
1868 u32 min
= limit
.min
;
1871 limit
.min
= max(min
, *next
);
1872 ret
= __xa_alloc(xa
, id
, entry
, limit
, gfp
);
1873 if ((xa
->xa_flags
& XA_FLAGS_ALLOC_WRAPPED
) && ret
== 0) {
1874 xa
->xa_flags
&= ~XA_FLAGS_ALLOC_WRAPPED
;
1878 if (ret
< 0 && limit
.min
> min
) {
1880 ret
= __xa_alloc(xa
, id
, entry
, limit
, gfp
);
1888 xa
->xa_flags
|= XA_FLAGS_ALLOC_WRAPPED
;
1892 EXPORT_SYMBOL(__xa_alloc_cyclic
);
1895 * __xa_set_mark() - Set this mark on this entry while locked.
1897 * @index: Index of entry.
1898 * @mark: Mark number.
1900 * Attempting to set a mark on a %NULL entry does not succeed.
1902 * Context: Any context. Expects xa_lock to be held on entry.
1904 void __xa_set_mark(struct xarray
*xa
, unsigned long index
, xa_mark_t mark
)
1906 XA_STATE(xas
, xa
, index
);
1907 void *entry
= xas_load(&xas
);
1910 xas_set_mark(&xas
, mark
);
1912 EXPORT_SYMBOL(__xa_set_mark
);
1915 * __xa_clear_mark() - Clear this mark on this entry while locked.
1917 * @index: Index of entry.
1918 * @mark: Mark number.
1920 * Context: Any context. Expects xa_lock to be held on entry.
1922 void __xa_clear_mark(struct xarray
*xa
, unsigned long index
, xa_mark_t mark
)
1924 XA_STATE(xas
, xa
, index
);
1925 void *entry
= xas_load(&xas
);
1928 xas_clear_mark(&xas
, mark
);
1930 EXPORT_SYMBOL(__xa_clear_mark
);
1933 * xa_get_mark() - Inquire whether this mark is set on this entry.
1935 * @index: Index of entry.
1936 * @mark: Mark number.
1938 * This function uses the RCU read lock, so the result may be out of date
1939 * by the time it returns. If you need the result to be stable, use a lock.
1941 * Context: Any context. Takes and releases the RCU lock.
1942 * Return: True if the entry at @index has this mark set, false if it doesn't.
1944 bool xa_get_mark(struct xarray
*xa
, unsigned long index
, xa_mark_t mark
)
1946 XA_STATE(xas
, xa
, index
);
1950 entry
= xas_start(&xas
);
1951 while (xas_get_mark(&xas
, mark
)) {
1952 if (!xa_is_node(entry
))
1954 entry
= xas_descend(&xas
, xa_to_node(entry
));
1962 EXPORT_SYMBOL(xa_get_mark
);
1965 * xa_set_mark() - Set this mark on this entry.
1967 * @index: Index of entry.
1968 * @mark: Mark number.
1970 * Attempting to set a mark on a %NULL entry does not succeed.
1972 * Context: Process context. Takes and releases the xa_lock.
1974 void xa_set_mark(struct xarray
*xa
, unsigned long index
, xa_mark_t mark
)
1977 __xa_set_mark(xa
, index
, mark
);
1980 EXPORT_SYMBOL(xa_set_mark
);
1983 * xa_clear_mark() - Clear this mark on this entry.
1985 * @index: Index of entry.
1986 * @mark: Mark number.
1988 * Clearing a mark always succeeds.
1990 * Context: Process context. Takes and releases the xa_lock.
1992 void xa_clear_mark(struct xarray
*xa
, unsigned long index
, xa_mark_t mark
)
1995 __xa_clear_mark(xa
, index
, mark
);
1998 EXPORT_SYMBOL(xa_clear_mark
);
2001 * xa_find() - Search the XArray for an entry.
2003 * @indexp: Pointer to an index.
2004 * @max: Maximum index to search to.
2005 * @filter: Selection criterion.
2007 * Finds the entry in @xa which matches the @filter, and has the lowest
2008 * index that is at least @indexp and no more than @max.
2009 * If an entry is found, @indexp is updated to be the index of the entry.
2010 * This function is protected by the RCU read lock, so it may not find
2011 * entries which are being simultaneously added. It will not return an
2012 * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
2014 * Context: Any context. Takes and releases the RCU lock.
2015 * Return: The entry, if found, otherwise %NULL.
2017 void *xa_find(struct xarray
*xa
, unsigned long *indexp
,
2018 unsigned long max
, xa_mark_t filter
)
2020 XA_STATE(xas
, xa
, *indexp
);
2025 if ((__force
unsigned int)filter
< XA_MAX_MARKS
)
2026 entry
= xas_find_marked(&xas
, max
, filter
);
2028 entry
= xas_find(&xas
, max
);
2029 } while (xas_retry(&xas
, entry
));
2033 *indexp
= xas
.xa_index
;
2036 EXPORT_SYMBOL(xa_find
);
2038 static bool xas_sibling(struct xa_state
*xas
)
2040 struct xa_node
*node
= xas
->xa_node
;
2043 if (!IS_ENABLED(CONFIG_XARRAY_MULTI
) || !node
)
2045 mask
= (XA_CHUNK_SIZE
<< node
->shift
) - 1;
2046 return (xas
->xa_index
& mask
) >
2047 ((unsigned long)xas
->xa_offset
<< node
->shift
);
2051 * xa_find_after() - Search the XArray for a present entry.
2053 * @indexp: Pointer to an index.
2054 * @max: Maximum index to search to.
2055 * @filter: Selection criterion.
2057 * Finds the entry in @xa which matches the @filter and has the lowest
2058 * index that is above @indexp and no more than @max.
2059 * If an entry is found, @indexp is updated to be the index of the entry.
2060 * This function is protected by the RCU read lock, so it may miss entries
2061 * which are being simultaneously added. It will not return an
2062 * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
2064 * Context: Any context. Takes and releases the RCU lock.
2065 * Return: The pointer, if found, otherwise %NULL.
2067 void *xa_find_after(struct xarray
*xa
, unsigned long *indexp
,
2068 unsigned long max
, xa_mark_t filter
)
2070 XA_STATE(xas
, xa
, *indexp
+ 1);
2073 if (xas
.xa_index
== 0)
2078 if ((__force
unsigned int)filter
< XA_MAX_MARKS
)
2079 entry
= xas_find_marked(&xas
, max
, filter
);
2081 entry
= xas_find(&xas
, max
);
2083 if (xas_invalid(&xas
))
2085 if (xas_sibling(&xas
))
2087 if (!xas_retry(&xas
, entry
))
2093 *indexp
= xas
.xa_index
;
2096 EXPORT_SYMBOL(xa_find_after
);
2098 static unsigned int xas_extract_present(struct xa_state
*xas
, void **dst
,
2099 unsigned long max
, unsigned int n
)
2105 xas_for_each(xas
, entry
, max
) {
2106 if (xas_retry(xas
, entry
))
2117 static unsigned int xas_extract_marked(struct xa_state
*xas
, void **dst
,
2118 unsigned long max
, unsigned int n
, xa_mark_t mark
)
2124 xas_for_each_marked(xas
, entry
, max
, mark
) {
2125 if (xas_retry(xas
, entry
))
2137 * xa_extract() - Copy selected entries from the XArray into a normal array.
2138 * @xa: The source XArray to copy from.
2139 * @dst: The buffer to copy entries into.
2140 * @start: The first index in the XArray eligible to be selected.
2141 * @max: The last index in the XArray eligible to be selected.
2142 * @n: The maximum number of entries to copy.
2143 * @filter: Selection criterion.
2145 * Copies up to @n entries that match @filter from the XArray. The
2146 * copied entries will have indices between @start and @max, inclusive.
2148 * The @filter may be an XArray mark value, in which case entries which are
2149 * marked with that mark will be copied. It may also be %XA_PRESENT, in
2150 * which case all entries which are not %NULL will be copied.
2152 * The entries returned may not represent a snapshot of the XArray at a
2153 * moment in time. For example, if another thread stores to index 5, then
2154 * index 10, calling xa_extract() may return the old contents of index 5
2155 * and the new contents of index 10. Indices not modified while this
2156 * function is running will not be skipped.
2158 * If you need stronger guarantees, holding the xa_lock across calls to this
2159 * function will prevent concurrent modification.
2161 * Context: Any context. Takes and releases the RCU lock.
2162 * Return: The number of entries copied.
2164 unsigned int xa_extract(struct xarray
*xa
, void **dst
, unsigned long start
,
2165 unsigned long max
, unsigned int n
, xa_mark_t filter
)
2167 XA_STATE(xas
, xa
, start
);
2172 if ((__force
unsigned int)filter
< XA_MAX_MARKS
)
2173 return xas_extract_marked(&xas
, dst
, max
, n
, filter
);
2174 return xas_extract_present(&xas
, dst
, max
, n
);
2176 EXPORT_SYMBOL(xa_extract
);
2179 * xa_delete_node() - Private interface for workingset code.
2180 * @node: Node to be removed from the tree.
2181 * @update: Function to call to update ancestor nodes.
2183 * Context: xa_lock must be held on entry and will not be released.
2185 void xa_delete_node(struct xa_node
*node
, xa_update_node_t update
)
2187 struct xa_state xas
= {
2189 .xa_index
= (unsigned long)node
->offset
<<
2190 (node
->shift
+ XA_CHUNK_SHIFT
),
2191 .xa_shift
= node
->shift
+ XA_CHUNK_SHIFT
,
2192 .xa_offset
= node
->offset
,
2193 .xa_node
= xa_parent_locked(node
->array
, node
),
2194 .xa_update
= update
,
2197 xas_store(&xas
, NULL
);
2199 EXPORT_SYMBOL_GPL(xa_delete_node
); /* For the benefit of the test suite */
2202 * xa_destroy() - Free all internal data structures.
2205 * After calling this function, the XArray is empty and has freed all memory
2206 * allocated for its internal data structures. You are responsible for
2207 * freeing the objects referenced by the XArray.
2209 * Context: Any context. Takes and releases the xa_lock, interrupt-safe.
2211 void xa_destroy(struct xarray
*xa
)
2213 XA_STATE(xas
, xa
, 0);
2214 unsigned long flags
;
2218 xas_lock_irqsave(&xas
, flags
);
2219 entry
= xa_head_locked(xa
);
2220 RCU_INIT_POINTER(xa
->xa_head
, NULL
);
2221 xas_init_marks(&xas
);
2222 if (xa_zero_busy(xa
))
2223 xa_mark_clear(xa
, XA_FREE_MARK
);
2224 /* lockdep checks we're still holding the lock in xas_free_nodes() */
2225 if (xa_is_node(entry
))
2226 xas_free_nodes(&xas
, xa_to_node(entry
));
2227 xas_unlock_irqrestore(&xas
, flags
);
2229 EXPORT_SYMBOL(xa_destroy
);
2232 void xa_dump_node(const struct xa_node
*node
)
2238 if ((unsigned long)node
& 3) {
2239 pr_cont("node %px\n", node
);
2243 pr_cont("node %px %s %d parent %px shift %d count %d values %d "
2244 "array %px list %px %px marks",
2245 node
, node
->parent
? "offset" : "max", node
->offset
,
2246 node
->parent
, node
->shift
, node
->count
, node
->nr_values
,
2247 node
->array
, node
->private_list
.prev
, node
->private_list
.next
);
2248 for (i
= 0; i
< XA_MAX_MARKS
; i
++)
2249 for (j
= 0; j
< XA_MARK_LONGS
; j
++)
2250 pr_cont(" %lx", node
->marks
[i
][j
]);
2254 void xa_dump_index(unsigned long index
, unsigned int shift
)
2257 pr_info("%lu: ", index
);
2258 else if (shift
>= BITS_PER_LONG
)
2259 pr_info("0-%lu: ", ~0UL);
2261 pr_info("%lu-%lu: ", index
, index
| ((1UL << shift
) - 1));
2264 void xa_dump_entry(const void *entry
, unsigned long index
, unsigned long shift
)
2269 xa_dump_index(index
, shift
);
2271 if (xa_is_node(entry
)) {
2273 pr_cont("%px\n", entry
);
2276 struct xa_node
*node
= xa_to_node(entry
);
2278 for (i
= 0; i
< XA_CHUNK_SIZE
; i
++)
2279 xa_dump_entry(node
->slots
[i
],
2280 index
+ (i
<< node
->shift
), node
->shift
);
2282 } else if (xa_is_value(entry
))
2283 pr_cont("value %ld (0x%lx) [%px]\n", xa_to_value(entry
),
2284 xa_to_value(entry
), entry
);
2285 else if (!xa_is_internal(entry
))
2286 pr_cont("%px\n", entry
);
2287 else if (xa_is_retry(entry
))
2288 pr_cont("retry (%ld)\n", xa_to_internal(entry
));
2289 else if (xa_is_sibling(entry
))
2290 pr_cont("sibling (slot %ld)\n", xa_to_sibling(entry
));
2291 else if (xa_is_zero(entry
))
2292 pr_cont("zero (%ld)\n", xa_to_internal(entry
));
2294 pr_cont("UNKNOWN ENTRY (%px)\n", entry
);
2297 void xa_dump(const struct xarray
*xa
)
2299 void *entry
= xa
->xa_head
;
2300 unsigned int shift
= 0;
2302 pr_info("xarray: %px head %px flags %x marks %d %d %d\n", xa
, entry
,
2303 xa
->xa_flags
, xa_marked(xa
, XA_MARK_0
),
2304 xa_marked(xa
, XA_MARK_1
), xa_marked(xa
, XA_MARK_2
));
2305 if (xa_is_node(entry
))
2306 shift
= xa_to_node(entry
)->shift
+ XA_CHUNK_SHIFT
;
2307 xa_dump_entry(entry
, 0, shift
);