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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>
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
*next
, *node
= xas
->xa_alloc
;
272 XA_NODE_BUG_ON(node
, !list_empty(&node
->private_list
));
273 next
= rcu_dereference_raw(node
->parent
);
274 radix_tree_node_rcu_free(&node
->rcu_head
);
275 xas
->xa_alloc
= node
= next
;
280 * xas_nomem() - Allocate memory if needed.
281 * @xas: XArray operation state.
282 * @gfp: Memory allocation flags.
284 * If we need to add new nodes to the XArray, we try to allocate memory
285 * with GFP_NOWAIT while holding the lock, which will usually succeed.
286 * If it fails, @xas is flagged as needing memory to continue. The caller
287 * should drop the lock and call xas_nomem(). If xas_nomem() succeeds,
288 * the caller should retry the operation.
290 * Forward progress is guaranteed as one node is allocated here and
291 * stored in the xa_state where it will be found by xas_alloc(). More
292 * nodes will likely be found in the slab allocator, but we do not tie
295 * Return: true if memory was needed, and was successfully allocated.
297 bool xas_nomem(struct xa_state
*xas
, gfp_t gfp
)
299 if (xas
->xa_node
!= XA_ERROR(-ENOMEM
)) {
303 if (xas
->xa
->xa_flags
& XA_FLAGS_ACCOUNT
)
304 gfp
|= __GFP_ACCOUNT
;
305 xas
->xa_alloc
= kmem_cache_alloc(radix_tree_node_cachep
, gfp
);
308 xas
->xa_alloc
->parent
= NULL
;
309 XA_NODE_BUG_ON(xas
->xa_alloc
, !list_empty(&xas
->xa_alloc
->private_list
));
310 xas
->xa_node
= XAS_RESTART
;
313 EXPORT_SYMBOL_GPL(xas_nomem
);
316 * __xas_nomem() - Drop locks and allocate memory if needed.
317 * @xas: XArray operation state.
318 * @gfp: Memory allocation flags.
320 * Internal variant of xas_nomem().
322 * Return: true if memory was needed, and was successfully allocated.
324 static bool __xas_nomem(struct xa_state
*xas
, gfp_t gfp
)
325 __must_hold(xas
->xa
->xa_lock
)
327 unsigned int lock_type
= xa_lock_type(xas
->xa
);
329 if (xas
->xa_node
!= XA_ERROR(-ENOMEM
)) {
333 if (xas
->xa
->xa_flags
& XA_FLAGS_ACCOUNT
)
334 gfp
|= __GFP_ACCOUNT
;
335 if (gfpflags_allow_blocking(gfp
)) {
336 xas_unlock_type(xas
, lock_type
);
337 xas
->xa_alloc
= kmem_cache_alloc(radix_tree_node_cachep
, gfp
);
338 xas_lock_type(xas
, lock_type
);
340 xas
->xa_alloc
= kmem_cache_alloc(radix_tree_node_cachep
, gfp
);
344 xas
->xa_alloc
->parent
= NULL
;
345 XA_NODE_BUG_ON(xas
->xa_alloc
, !list_empty(&xas
->xa_alloc
->private_list
));
346 xas
->xa_node
= XAS_RESTART
;
350 static void xas_update(struct xa_state
*xas
, struct xa_node
*node
)
353 xas
->xa_update(node
);
355 XA_NODE_BUG_ON(node
, !list_empty(&node
->private_list
));
358 static void *xas_alloc(struct xa_state
*xas
, unsigned int shift
)
360 struct xa_node
*parent
= xas
->xa_node
;
361 struct xa_node
*node
= xas
->xa_alloc
;
363 if (xas_invalid(xas
))
367 xas
->xa_alloc
= NULL
;
369 gfp_t gfp
= GFP_NOWAIT
| __GFP_NOWARN
;
371 if (xas
->xa
->xa_flags
& XA_FLAGS_ACCOUNT
)
372 gfp
|= __GFP_ACCOUNT
;
374 node
= kmem_cache_alloc(radix_tree_node_cachep
, gfp
);
376 xas_set_err(xas
, -ENOMEM
);
382 node
->offset
= xas
->xa_offset
;
384 XA_NODE_BUG_ON(node
, parent
->count
> XA_CHUNK_SIZE
);
385 xas_update(xas
, parent
);
387 XA_NODE_BUG_ON(node
, shift
> BITS_PER_LONG
);
388 XA_NODE_BUG_ON(node
, !list_empty(&node
->private_list
));
392 RCU_INIT_POINTER(node
->parent
, xas
->xa_node
);
393 node
->array
= xas
->xa
;
398 #ifdef CONFIG_XARRAY_MULTI
399 /* Returns the number of indices covered by a given xa_state */
400 static unsigned long xas_size(const struct xa_state
*xas
)
402 return (xas
->xa_sibs
+ 1UL) << xas
->xa_shift
;
407 * Use this to calculate the maximum index that will need to be created
408 * in order to add the entry described by @xas. Because we cannot store a
409 * multi-index entry at index 0, the calculation is a little more complex
410 * than you might expect.
412 static unsigned long xas_max(struct xa_state
*xas
)
414 unsigned long max
= xas
->xa_index
;
416 #ifdef CONFIG_XARRAY_MULTI
417 if (xas
->xa_shift
|| xas
->xa_sibs
) {
418 unsigned long mask
= xas_size(xas
) - 1;
428 /* The maximum index that can be contained in the array without expanding it */
429 static unsigned long max_index(void *entry
)
431 if (!xa_is_node(entry
))
433 return (XA_CHUNK_SIZE
<< xa_to_node(entry
)->shift
) - 1;
436 static void xas_shrink(struct xa_state
*xas
)
438 struct xarray
*xa
= xas
->xa
;
439 struct xa_node
*node
= xas
->xa_node
;
444 XA_NODE_BUG_ON(node
, node
->count
> XA_CHUNK_SIZE
);
445 if (node
->count
!= 1)
447 entry
= xa_entry_locked(xa
, node
, 0);
450 if (!xa_is_node(entry
) && node
->shift
)
452 if (xa_is_zero(entry
) && xa_zero_busy(xa
))
454 xas
->xa_node
= XAS_BOUNDS
;
456 RCU_INIT_POINTER(xa
->xa_head
, entry
);
457 if (xa_track_free(xa
) && !node_get_mark(node
, 0, XA_FREE_MARK
))
458 xa_mark_clear(xa
, XA_FREE_MARK
);
462 if (!xa_is_node(entry
))
463 RCU_INIT_POINTER(node
->slots
[0], XA_RETRY_ENTRY
);
464 xas_update(xas
, node
);
466 if (!xa_is_node(entry
))
468 node
= xa_to_node(entry
);
474 * xas_delete_node() - Attempt to delete an xa_node
475 * @xas: Array operation state.
477 * Attempts to delete the @xas->xa_node. This will fail if xa->node has
478 * a non-zero reference count.
480 static void xas_delete_node(struct xa_state
*xas
)
482 struct xa_node
*node
= xas
->xa_node
;
485 struct xa_node
*parent
;
487 XA_NODE_BUG_ON(node
, node
->count
> XA_CHUNK_SIZE
);
491 parent
= xa_parent_locked(xas
->xa
, node
);
492 xas
->xa_node
= parent
;
493 xas
->xa_offset
= node
->offset
;
497 xas
->xa
->xa_head
= NULL
;
498 xas
->xa_node
= XAS_BOUNDS
;
502 parent
->slots
[xas
->xa_offset
] = NULL
;
504 XA_NODE_BUG_ON(parent
, parent
->count
> XA_CHUNK_SIZE
);
506 xas_update(xas
, node
);
514 * xas_free_nodes() - Free this node and all nodes that it references
515 * @xas: Array operation state.
518 * This node has been removed from the tree. We must now free it and all
519 * of its subnodes. There may be RCU walkers with references into the tree,
520 * so we must replace all entries with retry markers.
522 static void xas_free_nodes(struct xa_state
*xas
, struct xa_node
*top
)
524 unsigned int offset
= 0;
525 struct xa_node
*node
= top
;
528 void *entry
= xa_entry_locked(xas
->xa
, node
, offset
);
530 if (node
->shift
&& xa_is_node(entry
)) {
531 node
= xa_to_node(entry
);
536 RCU_INIT_POINTER(node
->slots
[offset
], XA_RETRY_ENTRY
);
538 while (offset
== XA_CHUNK_SIZE
) {
539 struct xa_node
*parent
;
541 parent
= xa_parent_locked(xas
->xa
, node
);
542 offset
= node
->offset
+ 1;
545 xas_update(xas
, node
);
555 * xas_expand adds nodes to the head of the tree until it has reached
556 * sufficient height to be able to contain @xas->xa_index
558 static int xas_expand(struct xa_state
*xas
, void *head
)
560 struct xarray
*xa
= xas
->xa
;
561 struct xa_node
*node
= NULL
;
562 unsigned int shift
= 0;
563 unsigned long max
= xas_max(xas
);
568 while ((max
>> shift
) >= XA_CHUNK_SIZE
)
569 shift
+= XA_CHUNK_SHIFT
;
570 return shift
+ XA_CHUNK_SHIFT
;
571 } else if (xa_is_node(head
)) {
572 node
= xa_to_node(head
);
573 shift
= node
->shift
+ XA_CHUNK_SHIFT
;
577 while (max
> max_index(head
)) {
580 XA_NODE_BUG_ON(node
, shift
> BITS_PER_LONG
);
581 node
= xas_alloc(xas
, shift
);
586 if (xa_is_value(head
))
588 RCU_INIT_POINTER(node
->slots
[0], head
);
590 /* Propagate the aggregated mark info to the new child */
592 if (xa_track_free(xa
) && mark
== XA_FREE_MARK
) {
593 node_mark_all(node
, XA_FREE_MARK
);
594 if (!xa_marked(xa
, XA_FREE_MARK
)) {
595 node_clear_mark(node
, 0, XA_FREE_MARK
);
596 xa_mark_set(xa
, XA_FREE_MARK
);
598 } else if (xa_marked(xa
, mark
)) {
599 node_set_mark(node
, 0, mark
);
601 if (mark
== XA_MARK_MAX
)
607 * Now that the new node is fully initialised, we can add
610 if (xa_is_node(head
)) {
611 xa_to_node(head
)->offset
= 0;
612 rcu_assign_pointer(xa_to_node(head
)->parent
, node
);
614 head
= xa_mk_node(node
);
615 rcu_assign_pointer(xa
->xa_head
, head
);
616 xas_update(xas
, node
);
618 shift
+= XA_CHUNK_SHIFT
;
626 * xas_create() - Create a slot to store an entry in.
627 * @xas: XArray operation state.
628 * @allow_root: %true if we can store the entry in the root directly
630 * Most users will not need to call this function directly, as it is called
631 * by xas_store(). It is useful for doing conditional store operations
632 * (see the xa_cmpxchg() implementation for an example).
634 * Return: If the slot already existed, returns the contents of this slot.
635 * If the slot was newly created, returns %NULL. If it failed to create the
636 * slot, returns %NULL and indicates the error in @xas.
638 static void *xas_create(struct xa_state
*xas
, bool allow_root
)
640 struct xarray
*xa
= xas
->xa
;
643 struct xa_node
*node
= xas
->xa_node
;
645 unsigned int order
= xas
->xa_shift
;
648 entry
= xa_head_locked(xa
);
650 if (!entry
&& xa_zero_busy(xa
))
651 entry
= XA_ZERO_ENTRY
;
652 shift
= xas_expand(xas
, entry
);
655 if (!shift
&& !allow_root
)
656 shift
= XA_CHUNK_SHIFT
;
657 entry
= xa_head_locked(xa
);
659 } else if (xas_error(xas
)) {
662 unsigned int offset
= xas
->xa_offset
;
665 entry
= xa_entry_locked(xa
, node
, offset
);
666 slot
= &node
->slots
[offset
];
669 entry
= xa_head_locked(xa
);
673 while (shift
> order
) {
674 shift
-= XA_CHUNK_SHIFT
;
676 node
= xas_alloc(xas
, shift
);
679 if (xa_track_free(xa
))
680 node_mark_all(node
, XA_FREE_MARK
);
681 rcu_assign_pointer(*slot
, xa_mk_node(node
));
682 } else if (xa_is_node(entry
)) {
683 node
= xa_to_node(entry
);
687 entry
= xas_descend(xas
, node
);
688 slot
= &node
->slots
[xas
->xa_offset
];
695 * xas_create_range() - Ensure that stores to this range will succeed
696 * @xas: XArray operation state.
698 * Creates all of the slots in the range covered by @xas. Sets @xas to
699 * create single-index entries and positions it at the beginning of the
700 * range. This is for the benefit of users which have not yet been
701 * converted to use multi-index entries.
703 void xas_create_range(struct xa_state
*xas
)
705 unsigned long index
= xas
->xa_index
;
706 unsigned char shift
= xas
->xa_shift
;
707 unsigned char sibs
= xas
->xa_sibs
;
709 xas
->xa_index
|= ((sibs
+ 1UL) << shift
) - 1;
710 if (xas_is_node(xas
) && xas
->xa_node
->shift
== xas
->xa_shift
)
711 xas
->xa_offset
|= sibs
;
716 xas_create(xas
, true);
719 if (xas
->xa_index
<= (index
| XA_CHUNK_MASK
))
721 xas
->xa_index
-= XA_CHUNK_SIZE
;
724 struct xa_node
*node
= xas
->xa_node
;
725 if (node
->shift
>= shift
)
727 xas
->xa_node
= xa_parent_locked(xas
->xa
, node
);
728 xas
->xa_offset
= node
->offset
- 1;
729 if (node
->offset
!= 0)
735 xas
->xa_shift
= shift
;
737 xas
->xa_index
= index
;
740 xas
->xa_index
= index
;
744 EXPORT_SYMBOL_GPL(xas_create_range
);
746 static void update_node(struct xa_state
*xas
, struct xa_node
*node
,
747 int count
, int values
)
749 if (!node
|| (!count
&& !values
))
752 node
->count
+= count
;
753 node
->nr_values
+= values
;
754 XA_NODE_BUG_ON(node
, node
->count
> XA_CHUNK_SIZE
);
755 XA_NODE_BUG_ON(node
, node
->nr_values
> XA_CHUNK_SIZE
);
756 xas_update(xas
, node
);
758 xas_delete_node(xas
);
762 * xas_store() - Store this entry in the XArray.
763 * @xas: XArray operation state.
766 * If @xas is operating on a multi-index entry, the entry returned by this
767 * function is essentially meaningless (it may be an internal entry or it
768 * may be %NULL, even if there are non-NULL entries at some of the indices
769 * covered by the range). This is not a problem for any current users,
770 * and can be changed if needed.
772 * Return: The old entry at this index.
774 void *xas_store(struct xa_state
*xas
, void *entry
)
776 struct xa_node
*node
;
777 void __rcu
**slot
= &xas
->xa
->xa_head
;
778 unsigned int offset
, max
;
782 bool value
= xa_is_value(entry
);
785 bool allow_root
= !xa_is_node(entry
) && !xa_is_zero(entry
);
786 first
= xas_create(xas
, allow_root
);
788 first
= xas_load(xas
);
791 if (xas_invalid(xas
))
794 if (node
&& (xas
->xa_shift
< node
->shift
))
796 if ((first
== entry
) && !xas
->xa_sibs
)
800 offset
= xas
->xa_offset
;
801 max
= xas
->xa_offset
+ xas
->xa_sibs
;
803 slot
= &node
->slots
[offset
];
805 xas_squash_marks(xas
);
812 * Must clear the marks before setting the entry to NULL,
813 * otherwise xas_for_each_marked may find a NULL entry and
814 * stop early. rcu_assign_pointer contains a release barrier
815 * so the mark clearing will appear to happen before the
816 * entry is set to NULL.
818 rcu_assign_pointer(*slot
, entry
);
819 if (xa_is_node(next
) && (!node
|| node
->shift
))
820 xas_free_nodes(xas
, xa_to_node(next
));
823 count
+= !next
- !entry
;
824 values
+= !xa_is_value(first
) - !value
;
828 if (!xa_is_sibling(entry
))
829 entry
= xa_mk_sibling(xas
->xa_offset
);
831 if (offset
== XA_CHUNK_MASK
)
834 next
= xa_entry_locked(xas
->xa
, node
, ++offset
);
835 if (!xa_is_sibling(next
)) {
836 if (!entry
&& (offset
> max
))
843 update_node(xas
, node
, count
, values
);
846 EXPORT_SYMBOL_GPL(xas_store
);
849 * xas_get_mark() - Returns the state of this mark.
850 * @xas: XArray operation state.
851 * @mark: Mark number.
853 * Return: true if the mark is set, false if the mark is clear or @xas
854 * is in an error state.
856 bool xas_get_mark(const struct xa_state
*xas
, xa_mark_t mark
)
858 if (xas_invalid(xas
))
861 return xa_marked(xas
->xa
, mark
);
862 return node_get_mark(xas
->xa_node
, xas
->xa_offset
, mark
);
864 EXPORT_SYMBOL_GPL(xas_get_mark
);
867 * xas_set_mark() - Sets the mark on this entry and its parents.
868 * @xas: XArray operation state.
869 * @mark: Mark number.
871 * Sets the specified mark on this entry, and walks up the tree setting it
872 * on all the ancestor entries. Does nothing if @xas has not been walked to
873 * an entry, or is in an error state.
875 void xas_set_mark(const struct xa_state
*xas
, xa_mark_t mark
)
877 struct xa_node
*node
= xas
->xa_node
;
878 unsigned int offset
= xas
->xa_offset
;
880 if (xas_invalid(xas
))
884 if (node_set_mark(node
, offset
, mark
))
886 offset
= node
->offset
;
887 node
= xa_parent_locked(xas
->xa
, node
);
890 if (!xa_marked(xas
->xa
, mark
))
891 xa_mark_set(xas
->xa
, mark
);
893 EXPORT_SYMBOL_GPL(xas_set_mark
);
896 * xas_clear_mark() - Clears the mark on this entry and its parents.
897 * @xas: XArray operation state.
898 * @mark: Mark number.
900 * Clears the specified mark on this entry, and walks back to the head
901 * attempting to clear it on all the ancestor entries. Does nothing if
902 * @xas has not been walked to an entry, or is in an error state.
904 void xas_clear_mark(const struct xa_state
*xas
, xa_mark_t mark
)
906 struct xa_node
*node
= xas
->xa_node
;
907 unsigned int offset
= xas
->xa_offset
;
909 if (xas_invalid(xas
))
913 if (!node_clear_mark(node
, offset
, mark
))
915 if (node_any_mark(node
, mark
))
918 offset
= node
->offset
;
919 node
= xa_parent_locked(xas
->xa
, node
);
922 if (xa_marked(xas
->xa
, mark
))
923 xa_mark_clear(xas
->xa
, mark
);
925 EXPORT_SYMBOL_GPL(xas_clear_mark
);
928 * xas_init_marks() - Initialise all marks for the entry
929 * @xas: Array operations state.
931 * Initialise all marks for the entry specified by @xas. If we're tracking
932 * free entries with a mark, we need to set it on all entries. All other
935 * This implementation is not as efficient as it could be; we may walk
936 * up the tree multiple times.
938 void xas_init_marks(const struct xa_state
*xas
)
943 if (xa_track_free(xas
->xa
) && mark
== XA_FREE_MARK
)
944 xas_set_mark(xas
, mark
);
946 xas_clear_mark(xas
, mark
);
947 if (mark
== XA_MARK_MAX
)
952 EXPORT_SYMBOL_GPL(xas_init_marks
);
954 #ifdef CONFIG_XARRAY_MULTI
955 static unsigned int node_get_marks(struct xa_node
*node
, unsigned int offset
)
957 unsigned int marks
= 0;
958 xa_mark_t mark
= XA_MARK_0
;
961 if (node_get_mark(node
, offset
, mark
))
962 marks
|= 1 << (__force
unsigned int)mark
;
963 if (mark
== XA_MARK_MAX
)
971 static void node_set_marks(struct xa_node
*node
, unsigned int offset
,
972 struct xa_node
*child
, unsigned int marks
)
974 xa_mark_t mark
= XA_MARK_0
;
977 if (marks
& (1 << (__force
unsigned int)mark
)) {
978 node_set_mark(node
, offset
, mark
);
980 node_mark_all(child
, mark
);
982 if (mark
== XA_MARK_MAX
)
989 * xas_split_alloc() - Allocate memory for splitting an entry.
990 * @xas: XArray operation state.
991 * @entry: New entry which will be stored in the array.
992 * @order: Current entry order.
993 * @gfp: Memory allocation flags.
995 * This function should be called before calling xas_split().
996 * If necessary, it will allocate new nodes (and fill them with @entry)
997 * to prepare for the upcoming split of an entry of @order size into
998 * entries of the order stored in the @xas.
1000 * Context: May sleep if @gfp flags permit.
1002 void xas_split_alloc(struct xa_state
*xas
, void *entry
, unsigned int order
,
1005 unsigned int sibs
= (1 << (order
% XA_CHUNK_SHIFT
)) - 1;
1006 unsigned int mask
= xas
->xa_sibs
;
1008 /* XXX: no support for splitting really large entries yet */
1009 if (WARN_ON(xas
->xa_shift
+ 2 * XA_CHUNK_SHIFT
< order
))
1011 if (xas
->xa_shift
+ XA_CHUNK_SHIFT
> order
)
1016 void *sibling
= NULL
;
1017 struct xa_node
*node
;
1019 node
= kmem_cache_alloc(radix_tree_node_cachep
, gfp
);
1022 node
->array
= xas
->xa
;
1023 for (i
= 0; i
< XA_CHUNK_SIZE
; i
++) {
1024 if ((i
& mask
) == 0) {
1025 RCU_INIT_POINTER(node
->slots
[i
], entry
);
1026 sibling
= xa_mk_sibling(i
);
1028 RCU_INIT_POINTER(node
->slots
[i
], sibling
);
1031 RCU_INIT_POINTER(node
->parent
, xas
->xa_alloc
);
1032 xas
->xa_alloc
= node
;
1033 } while (sibs
-- > 0);
1038 xas_set_err(xas
, -ENOMEM
);
1040 EXPORT_SYMBOL_GPL(xas_split_alloc
);
1043 * xas_split() - Split a multi-index entry into smaller entries.
1044 * @xas: XArray operation state.
1045 * @entry: New entry to store in the array.
1046 * @order: Current entry order.
1048 * The size of the new entries is set in @xas. The value in @entry is
1049 * copied to all the replacement entries.
1051 * Context: Any context. The caller should hold the xa_lock.
1053 void xas_split(struct xa_state
*xas
, void *entry
, unsigned int order
)
1055 unsigned int sibs
= (1 << (order
% XA_CHUNK_SHIFT
)) - 1;
1056 unsigned int offset
, marks
;
1057 struct xa_node
*node
;
1058 void *curr
= xas_load(xas
);
1061 node
= xas
->xa_node
;
1065 marks
= node_get_marks(node
, xas
->xa_offset
);
1067 offset
= xas
->xa_offset
+ sibs
;
1069 if (xas
->xa_shift
< node
->shift
) {
1070 struct xa_node
*child
= xas
->xa_alloc
;
1072 xas
->xa_alloc
= rcu_dereference_raw(child
->parent
);
1073 child
->shift
= node
->shift
- XA_CHUNK_SHIFT
;
1074 child
->offset
= offset
;
1075 child
->count
= XA_CHUNK_SIZE
;
1076 child
->nr_values
= xa_is_value(entry
) ?
1078 RCU_INIT_POINTER(child
->parent
, node
);
1079 node_set_marks(node
, offset
, child
, marks
);
1080 rcu_assign_pointer(node
->slots
[offset
],
1082 if (xa_is_value(curr
))
1084 xas_update(xas
, child
);
1086 unsigned int canon
= offset
- xas
->xa_sibs
;
1088 node_set_marks(node
, canon
, NULL
, marks
);
1089 rcu_assign_pointer(node
->slots
[canon
], entry
);
1090 while (offset
> canon
)
1091 rcu_assign_pointer(node
->slots
[offset
--],
1092 xa_mk_sibling(canon
));
1093 values
+= (xa_is_value(entry
) - xa_is_value(curr
)) *
1096 } while (offset
-- > xas
->xa_offset
);
1098 node
->nr_values
+= values
;
1099 xas_update(xas
, node
);
1101 EXPORT_SYMBOL_GPL(xas_split
);
1105 * xas_pause() - Pause a walk to drop a lock.
1106 * @xas: XArray operation state.
1108 * Some users need to pause a walk and drop the lock they're holding in
1109 * order to yield to a higher priority thread or carry out an operation
1110 * on an entry. Those users should call this function before they drop
1111 * the lock. It resets the @xas to be suitable for the next iteration
1112 * of the loop after the user has reacquired the lock. If most entries
1113 * found during a walk require you to call xas_pause(), the xa_for_each()
1114 * iterator may be more appropriate.
1116 * Note that xas_pause() only works for forward iteration. If a user needs
1117 * to pause a reverse iteration, we will need a xas_pause_rev().
1119 void xas_pause(struct xa_state
*xas
)
1121 struct xa_node
*node
= xas
->xa_node
;
1123 if (xas_invalid(xas
))
1126 xas
->xa_node
= XAS_RESTART
;
1128 unsigned long offset
= xas
->xa_offset
;
1129 while (++offset
< XA_CHUNK_SIZE
) {
1130 if (!xa_is_sibling(xa_entry(xas
->xa
, node
, offset
)))
1133 xas
->xa_index
+= (offset
- xas
->xa_offset
) << node
->shift
;
1134 if (xas
->xa_index
== 0)
1135 xas
->xa_node
= XAS_BOUNDS
;
1140 EXPORT_SYMBOL_GPL(xas_pause
);
1143 * __xas_prev() - Find the previous entry in the XArray.
1144 * @xas: XArray operation state.
1146 * Helper function for xas_prev() which handles all the complex cases
1149 void *__xas_prev(struct xa_state
*xas
)
1153 if (!xas_frozen(xas
->xa_node
))
1156 return set_bounds(xas
);
1157 if (xas_not_node(xas
->xa_node
))
1158 return xas_load(xas
);
1160 if (xas
->xa_offset
!= get_offset(xas
->xa_index
, xas
->xa_node
))
1163 while (xas
->xa_offset
== 255) {
1164 xas
->xa_offset
= xas
->xa_node
->offset
- 1;
1165 xas
->xa_node
= xa_parent(xas
->xa
, xas
->xa_node
);
1167 return set_bounds(xas
);
1171 entry
= xa_entry(xas
->xa
, xas
->xa_node
, xas
->xa_offset
);
1172 if (!xa_is_node(entry
))
1175 xas
->xa_node
= xa_to_node(entry
);
1176 xas_set_offset(xas
);
1179 EXPORT_SYMBOL_GPL(__xas_prev
);
1182 * __xas_next() - Find the next entry in the XArray.
1183 * @xas: XArray operation state.
1185 * Helper function for xas_next() which handles all the complex cases
1188 void *__xas_next(struct xa_state
*xas
)
1192 if (!xas_frozen(xas
->xa_node
))
1195 return set_bounds(xas
);
1196 if (xas_not_node(xas
->xa_node
))
1197 return xas_load(xas
);
1199 if (xas
->xa_offset
!= get_offset(xas
->xa_index
, xas
->xa_node
))
1202 while (xas
->xa_offset
== XA_CHUNK_SIZE
) {
1203 xas
->xa_offset
= xas
->xa_node
->offset
+ 1;
1204 xas
->xa_node
= xa_parent(xas
->xa
, xas
->xa_node
);
1206 return set_bounds(xas
);
1210 entry
= xa_entry(xas
->xa
, xas
->xa_node
, xas
->xa_offset
);
1211 if (!xa_is_node(entry
))
1214 xas
->xa_node
= xa_to_node(entry
);
1215 xas_set_offset(xas
);
1218 EXPORT_SYMBOL_GPL(__xas_next
);
1221 * xas_find() - Find the next present entry in the XArray.
1222 * @xas: XArray operation state.
1223 * @max: Highest index to return.
1225 * If the @xas has not yet been walked to an entry, return the entry
1226 * which has an index >= xas.xa_index. If it has been walked, the entry
1227 * currently being pointed at has been processed, and so we move to the
1230 * If no entry is found and the array is smaller than @max, the iterator
1231 * is set to the smallest index not yet in the array. This allows @xas
1232 * to be immediately passed to xas_store().
1234 * Return: The entry, if found, otherwise %NULL.
1236 void *xas_find(struct xa_state
*xas
, unsigned long max
)
1240 if (xas_error(xas
) || xas
->xa_node
== XAS_BOUNDS
)
1242 if (xas
->xa_index
> max
)
1243 return set_bounds(xas
);
1245 if (!xas
->xa_node
) {
1247 return set_bounds(xas
);
1248 } else if (xas
->xa_node
== XAS_RESTART
) {
1249 entry
= xas_load(xas
);
1250 if (entry
|| xas_not_node(xas
->xa_node
))
1252 } else if (!xas
->xa_node
->shift
&&
1253 xas
->xa_offset
!= (xas
->xa_index
& XA_CHUNK_MASK
)) {
1254 xas
->xa_offset
= ((xas
->xa_index
- 1) & XA_CHUNK_MASK
) + 1;
1259 while (xas
->xa_node
&& (xas
->xa_index
<= max
)) {
1260 if (unlikely(xas
->xa_offset
== XA_CHUNK_SIZE
)) {
1261 xas
->xa_offset
= xas
->xa_node
->offset
+ 1;
1262 xas
->xa_node
= xa_parent(xas
->xa
, xas
->xa_node
);
1266 entry
= xa_entry(xas
->xa
, xas
->xa_node
, xas
->xa_offset
);
1267 if (xa_is_node(entry
)) {
1268 xas
->xa_node
= xa_to_node(entry
);
1272 if (entry
&& !xa_is_sibling(entry
))
1279 xas
->xa_node
= XAS_BOUNDS
;
1282 EXPORT_SYMBOL_GPL(xas_find
);
1285 * xas_find_marked() - Find the next marked entry in the XArray.
1286 * @xas: XArray operation state.
1287 * @max: Highest index to return.
1288 * @mark: Mark number to search for.
1290 * If the @xas has not yet been walked to an entry, return the marked entry
1291 * which has an index >= xas.xa_index. If it has been walked, the entry
1292 * currently being pointed at has been processed, and so we return the
1293 * first marked entry with an index > xas.xa_index.
1295 * If no marked entry is found and the array is smaller than @max, @xas is
1296 * set to the bounds state and xas->xa_index is set to the smallest index
1297 * not yet in the array. This allows @xas to be immediately passed to
1300 * If no entry is found before @max is reached, @xas is set to the restart
1303 * Return: The entry, if found, otherwise %NULL.
1305 void *xas_find_marked(struct xa_state
*xas
, unsigned long max
, xa_mark_t mark
)
1307 bool advance
= true;
1308 unsigned int offset
;
1313 if (xas
->xa_index
> max
)
1316 if (!xas
->xa_node
) {
1319 } else if (xas_top(xas
->xa_node
)) {
1321 entry
= xa_head(xas
->xa
);
1322 xas
->xa_node
= NULL
;
1323 if (xas
->xa_index
> max_index(entry
))
1325 if (!xa_is_node(entry
)) {
1326 if (xa_marked(xas
->xa
, mark
))
1331 xas
->xa_node
= xa_to_node(entry
);
1332 xas
->xa_offset
= xas
->xa_index
>> xas
->xa_node
->shift
;
1335 while (xas
->xa_index
<= max
) {
1336 if (unlikely(xas
->xa_offset
== XA_CHUNK_SIZE
)) {
1337 xas
->xa_offset
= xas
->xa_node
->offset
+ 1;
1338 xas
->xa_node
= xa_parent(xas
->xa
, xas
->xa_node
);
1346 entry
= xa_entry(xas
->xa
, xas
->xa_node
, xas
->xa_offset
);
1347 if (xa_is_sibling(entry
)) {
1348 xas
->xa_offset
= xa_to_sibling(entry
);
1349 xas_move_index(xas
, xas
->xa_offset
);
1353 offset
= xas_find_chunk(xas
, advance
, mark
);
1354 if (offset
> xas
->xa_offset
) {
1356 xas_move_index(xas
, offset
);
1358 if ((xas
->xa_index
- 1) >= max
)
1360 xas
->xa_offset
= offset
;
1361 if (offset
== XA_CHUNK_SIZE
)
1365 entry
= xa_entry(xas
->xa
, xas
->xa_node
, xas
->xa_offset
);
1366 if (!entry
&& !(xa_track_free(xas
->xa
) && mark
== XA_FREE_MARK
))
1368 if (!xa_is_node(entry
))
1370 xas
->xa_node
= xa_to_node(entry
);
1371 xas_set_offset(xas
);
1375 if (xas
->xa_index
> max
)
1377 return set_bounds(xas
);
1379 xas
->xa_node
= XAS_RESTART
;
1382 EXPORT_SYMBOL_GPL(xas_find_marked
);
1385 * xas_find_conflict() - Find the next present entry in a range.
1386 * @xas: XArray operation state.
1388 * The @xas describes both a range and a position within that range.
1390 * Context: Any context. Expects xa_lock to be held.
1391 * Return: The next entry in the range covered by @xas or %NULL.
1393 void *xas_find_conflict(struct xa_state
*xas
)
1403 if (xas_top(xas
->xa_node
)) {
1404 curr
= xas_start(xas
);
1407 while (xa_is_node(curr
)) {
1408 struct xa_node
*node
= xa_to_node(curr
);
1409 curr
= xas_descend(xas
, node
);
1415 if (xas
->xa_node
->shift
> xas
->xa_shift
)
1419 if (xas
->xa_node
->shift
== xas
->xa_shift
) {
1420 if ((xas
->xa_offset
& xas
->xa_sibs
) == xas
->xa_sibs
)
1422 } else if (xas
->xa_offset
== XA_CHUNK_MASK
) {
1423 xas
->xa_offset
= xas
->xa_node
->offset
;
1424 xas
->xa_node
= xa_parent_locked(xas
->xa
, xas
->xa_node
);
1429 curr
= xa_entry_locked(xas
->xa
, xas
->xa_node
, ++xas
->xa_offset
);
1430 if (xa_is_sibling(curr
))
1432 while (xa_is_node(curr
)) {
1433 xas
->xa_node
= xa_to_node(curr
);
1435 curr
= xa_entry_locked(xas
->xa
, xas
->xa_node
, 0);
1440 xas
->xa_offset
-= xas
->xa_sibs
;
1443 EXPORT_SYMBOL_GPL(xas_find_conflict
);
1446 * xa_load() - Load an entry from an XArray.
1448 * @index: index into array.
1450 * Context: Any context. Takes and releases the RCU lock.
1451 * Return: The entry at @index in @xa.
1453 void *xa_load(struct xarray
*xa
, unsigned long index
)
1455 XA_STATE(xas
, xa
, index
);
1460 entry
= xas_load(&xas
);
1461 if (xa_is_zero(entry
))
1463 } while (xas_retry(&xas
, entry
));
1468 EXPORT_SYMBOL(xa_load
);
1470 static void *xas_result(struct xa_state
*xas
, void *curr
)
1472 if (xa_is_zero(curr
))
1475 curr
= xas
->xa_node
;
1480 * __xa_erase() - Erase this entry from the XArray while locked.
1482 * @index: Index into array.
1484 * After this function returns, loading from @index will return %NULL.
1485 * If the index is part of a multi-index entry, all indices will be erased
1486 * and none of the entries will be part of a multi-index entry.
1488 * Context: Any context. Expects xa_lock to be held on entry.
1489 * Return: The entry which used to be at this index.
1491 void *__xa_erase(struct xarray
*xa
, unsigned long index
)
1493 XA_STATE(xas
, xa
, index
);
1494 return xas_result(&xas
, xas_store(&xas
, NULL
));
1496 EXPORT_SYMBOL(__xa_erase
);
1499 * xa_erase() - Erase this entry from the XArray.
1501 * @index: Index of entry.
1503 * After this function returns, loading from @index will return %NULL.
1504 * If the index is part of a multi-index entry, all indices will be erased
1505 * and none of the entries will be part of a multi-index entry.
1507 * Context: Any context. Takes and releases the xa_lock.
1508 * Return: The entry which used to be at this index.
1510 void *xa_erase(struct xarray
*xa
, unsigned long index
)
1515 entry
= __xa_erase(xa
, index
);
1520 EXPORT_SYMBOL(xa_erase
);
1523 * __xa_store() - Store this entry in the XArray.
1525 * @index: Index into array.
1526 * @entry: New entry.
1527 * @gfp: Memory allocation flags.
1529 * You must already be holding the xa_lock when calling this function.
1530 * It will drop the lock if needed to allocate memory, and then reacquire
1533 * Context: Any context. Expects xa_lock to be held on entry. May
1534 * release and reacquire xa_lock if @gfp flags permit.
1535 * Return: The old entry at this index or xa_err() if an error happened.
1537 void *__xa_store(struct xarray
*xa
, unsigned long index
, void *entry
, gfp_t gfp
)
1539 XA_STATE(xas
, xa
, index
);
1542 if (WARN_ON_ONCE(xa_is_advanced(entry
)))
1543 return XA_ERROR(-EINVAL
);
1544 if (xa_track_free(xa
) && !entry
)
1545 entry
= XA_ZERO_ENTRY
;
1548 curr
= xas_store(&xas
, entry
);
1549 if (xa_track_free(xa
))
1550 xas_clear_mark(&xas
, XA_FREE_MARK
);
1551 } while (__xas_nomem(&xas
, gfp
));
1553 return xas_result(&xas
, curr
);
1555 EXPORT_SYMBOL(__xa_store
);
1558 * xa_store() - Store this entry in the XArray.
1560 * @index: Index into array.
1561 * @entry: New entry.
1562 * @gfp: Memory allocation flags.
1564 * After this function returns, loads from this index will return @entry.
1565 * Storing into an existing multi-index entry updates the entry of every index.
1566 * The marks associated with @index are unaffected unless @entry is %NULL.
1568 * Context: Any context. Takes and releases the xa_lock.
1569 * May sleep if the @gfp flags permit.
1570 * Return: The old entry at this index on success, xa_err(-EINVAL) if @entry
1571 * cannot be stored in an XArray, or xa_err(-ENOMEM) if memory allocation
1574 void *xa_store(struct xarray
*xa
, unsigned long index
, void *entry
, gfp_t gfp
)
1579 curr
= __xa_store(xa
, index
, entry
, gfp
);
1584 EXPORT_SYMBOL(xa_store
);
1587 * __xa_cmpxchg() - Store this entry in the XArray.
1589 * @index: Index into array.
1590 * @old: Old value to test against.
1591 * @entry: New entry.
1592 * @gfp: Memory allocation flags.
1594 * You must already be holding the xa_lock when calling this function.
1595 * It will drop the lock if needed to allocate memory, and then reacquire
1598 * Context: Any context. Expects xa_lock to be held on entry. May
1599 * release and reacquire xa_lock if @gfp flags permit.
1600 * Return: The old entry at this index or xa_err() if an error happened.
1602 void *__xa_cmpxchg(struct xarray
*xa
, unsigned long index
,
1603 void *old
, void *entry
, gfp_t gfp
)
1605 XA_STATE(xas
, xa
, index
);
1608 if (WARN_ON_ONCE(xa_is_advanced(entry
)))
1609 return XA_ERROR(-EINVAL
);
1612 curr
= xas_load(&xas
);
1614 xas_store(&xas
, entry
);
1615 if (xa_track_free(xa
) && entry
&& !curr
)
1616 xas_clear_mark(&xas
, XA_FREE_MARK
);
1618 } while (__xas_nomem(&xas
, gfp
));
1620 return xas_result(&xas
, curr
);
1622 EXPORT_SYMBOL(__xa_cmpxchg
);
1625 * __xa_insert() - Store this entry in the XArray if no entry is present.
1627 * @index: Index into array.
1628 * @entry: New entry.
1629 * @gfp: Memory allocation flags.
1631 * Inserting a NULL entry will store a reserved entry (like xa_reserve())
1632 * if no entry is present. Inserting will fail if a reserved entry is
1633 * present, even though loading from this index will return NULL.
1635 * Context: Any context. Expects xa_lock to be held on entry. May
1636 * release and reacquire xa_lock if @gfp flags permit.
1637 * Return: 0 if the store succeeded. -EBUSY if another entry was present.
1638 * -ENOMEM if memory could not be allocated.
1640 int __xa_insert(struct xarray
*xa
, unsigned long index
, void *entry
, gfp_t gfp
)
1642 XA_STATE(xas
, xa
, index
);
1645 if (WARN_ON_ONCE(xa_is_advanced(entry
)))
1648 entry
= XA_ZERO_ENTRY
;
1651 curr
= xas_load(&xas
);
1653 xas_store(&xas
, entry
);
1654 if (xa_track_free(xa
))
1655 xas_clear_mark(&xas
, XA_FREE_MARK
);
1657 xas_set_err(&xas
, -EBUSY
);
1659 } while (__xas_nomem(&xas
, gfp
));
1661 return xas_error(&xas
);
1663 EXPORT_SYMBOL(__xa_insert
);
1665 #ifdef CONFIG_XARRAY_MULTI
1666 static void xas_set_range(struct xa_state
*xas
, unsigned long first
,
1669 unsigned int shift
= 0;
1670 unsigned long sibs
= last
- first
;
1671 unsigned int offset
= XA_CHUNK_MASK
;
1673 xas_set(xas
, first
);
1675 while ((first
& XA_CHUNK_MASK
) == 0) {
1676 if (sibs
< XA_CHUNK_MASK
)
1678 if ((sibs
== XA_CHUNK_MASK
) && (offset
< XA_CHUNK_MASK
))
1680 shift
+= XA_CHUNK_SHIFT
;
1681 if (offset
== XA_CHUNK_MASK
)
1682 offset
= sibs
& XA_CHUNK_MASK
;
1683 sibs
>>= XA_CHUNK_SHIFT
;
1684 first
>>= XA_CHUNK_SHIFT
;
1687 offset
= first
& XA_CHUNK_MASK
;
1688 if (offset
+ sibs
> XA_CHUNK_MASK
)
1689 sibs
= XA_CHUNK_MASK
- offset
;
1690 if ((((first
+ sibs
+ 1) << shift
) - 1) > last
)
1693 xas
->xa_shift
= shift
;
1694 xas
->xa_sibs
= sibs
;
1698 * xa_store_range() - Store this entry at a range of indices in the XArray.
1700 * @first: First index to affect.
1701 * @last: Last index to affect.
1702 * @entry: New entry.
1703 * @gfp: Memory allocation flags.
1705 * After this function returns, loads from any index between @first and @last,
1706 * inclusive will return @entry.
1707 * Storing into an existing multi-index entry updates the entry of every index.
1708 * The marks associated with @index are unaffected unless @entry is %NULL.
1710 * Context: Process context. Takes and releases the xa_lock. May sleep
1711 * if the @gfp flags permit.
1712 * Return: %NULL on success, xa_err(-EINVAL) if @entry cannot be stored in
1713 * an XArray, or xa_err(-ENOMEM) if memory allocation failed.
1715 void *xa_store_range(struct xarray
*xa
, unsigned long first
,
1716 unsigned long last
, void *entry
, gfp_t gfp
)
1718 XA_STATE(xas
, xa
, 0);
1720 if (WARN_ON_ONCE(xa_is_internal(entry
)))
1721 return XA_ERROR(-EINVAL
);
1723 return XA_ERROR(-EINVAL
);
1728 unsigned int order
= BITS_PER_LONG
;
1730 order
= __ffs(last
+ 1);
1731 xas_set_order(&xas
, last
, order
);
1732 xas_create(&xas
, true);
1733 if (xas_error(&xas
))
1737 xas_set_range(&xas
, first
, last
);
1738 xas_store(&xas
, entry
);
1739 if (xas_error(&xas
))
1741 first
+= xas_size(&xas
);
1742 } while (first
<= last
);
1745 } while (xas_nomem(&xas
, gfp
));
1747 return xas_result(&xas
, NULL
);
1749 EXPORT_SYMBOL(xa_store_range
);
1752 * xa_get_order() - Get the order of an entry.
1754 * @index: Index of the entry.
1756 * Return: A number between 0 and 63 indicating the order of the entry.
1758 int xa_get_order(struct xarray
*xa
, unsigned long index
)
1760 XA_STATE(xas
, xa
, index
);
1765 entry
= xas_load(&xas
);
1774 unsigned int slot
= xas
.xa_offset
+ (1 << order
);
1776 if (slot
>= XA_CHUNK_SIZE
)
1778 if (!xa_is_sibling(xas
.xa_node
->slots
[slot
]))
1783 order
+= xas
.xa_node
->shift
;
1789 EXPORT_SYMBOL(xa_get_order
);
1790 #endif /* CONFIG_XARRAY_MULTI */
1793 * __xa_alloc() - Find somewhere to store this entry in the XArray.
1795 * @id: Pointer to ID.
1796 * @limit: Range for allocated ID.
1797 * @entry: New entry.
1798 * @gfp: Memory allocation flags.
1800 * Finds an empty entry in @xa between @limit.min and @limit.max,
1801 * stores the index into the @id pointer, then stores the entry at
1802 * that index. A concurrent lookup will not see an uninitialised @id.
1804 * Context: Any context. Expects xa_lock to be held on entry. May
1805 * release and reacquire xa_lock if @gfp flags permit.
1806 * Return: 0 on success, -ENOMEM if memory could not be allocated or
1807 * -EBUSY if there are no free entries in @limit.
1809 int __xa_alloc(struct xarray
*xa
, u32
*id
, void *entry
,
1810 struct xa_limit limit
, gfp_t gfp
)
1812 XA_STATE(xas
, xa
, 0);
1814 if (WARN_ON_ONCE(xa_is_advanced(entry
)))
1816 if (WARN_ON_ONCE(!xa_track_free(xa
)))
1820 entry
= XA_ZERO_ENTRY
;
1823 xas
.xa_index
= limit
.min
;
1824 xas_find_marked(&xas
, limit
.max
, XA_FREE_MARK
);
1825 if (xas
.xa_node
== XAS_RESTART
)
1826 xas_set_err(&xas
, -EBUSY
);
1829 xas_store(&xas
, entry
);
1830 xas_clear_mark(&xas
, XA_FREE_MARK
);
1831 } while (__xas_nomem(&xas
, gfp
));
1833 return xas_error(&xas
);
1835 EXPORT_SYMBOL(__xa_alloc
);
1838 * __xa_alloc_cyclic() - Find somewhere to store this entry in the XArray.
1840 * @id: Pointer to ID.
1841 * @entry: New entry.
1842 * @limit: Range of allocated ID.
1843 * @next: Pointer to next ID to allocate.
1844 * @gfp: Memory allocation flags.
1846 * Finds an empty entry in @xa between @limit.min and @limit.max,
1847 * stores the index into the @id pointer, then stores the entry at
1848 * that index. A concurrent lookup will not see an uninitialised @id.
1849 * The search for an empty entry will start at @next and will wrap
1850 * around if necessary.
1852 * Context: Any context. Expects xa_lock to be held on entry. May
1853 * release and reacquire xa_lock if @gfp flags permit.
1854 * Return: 0 if the allocation succeeded without wrapping. 1 if the
1855 * allocation succeeded after wrapping, -ENOMEM if memory could not be
1856 * allocated or -EBUSY if there are no free entries in @limit.
1858 int __xa_alloc_cyclic(struct xarray
*xa
, u32
*id
, void *entry
,
1859 struct xa_limit limit
, u32
*next
, gfp_t gfp
)
1861 u32 min
= limit
.min
;
1864 limit
.min
= max(min
, *next
);
1865 ret
= __xa_alloc(xa
, id
, entry
, limit
, gfp
);
1866 if ((xa
->xa_flags
& XA_FLAGS_ALLOC_WRAPPED
) && ret
== 0) {
1867 xa
->xa_flags
&= ~XA_FLAGS_ALLOC_WRAPPED
;
1871 if (ret
< 0 && limit
.min
> min
) {
1873 ret
= __xa_alloc(xa
, id
, entry
, limit
, gfp
);
1881 xa
->xa_flags
|= XA_FLAGS_ALLOC_WRAPPED
;
1885 EXPORT_SYMBOL(__xa_alloc_cyclic
);
1888 * __xa_set_mark() - Set this mark on this entry while locked.
1890 * @index: Index of entry.
1891 * @mark: Mark number.
1893 * Attempting to set a mark on a %NULL entry does not succeed.
1895 * Context: Any context. Expects xa_lock to be held on entry.
1897 void __xa_set_mark(struct xarray
*xa
, unsigned long index
, xa_mark_t mark
)
1899 XA_STATE(xas
, xa
, index
);
1900 void *entry
= xas_load(&xas
);
1903 xas_set_mark(&xas
, mark
);
1905 EXPORT_SYMBOL(__xa_set_mark
);
1908 * __xa_clear_mark() - Clear this mark on this entry while locked.
1910 * @index: Index of entry.
1911 * @mark: Mark number.
1913 * Context: Any context. Expects xa_lock to be held on entry.
1915 void __xa_clear_mark(struct xarray
*xa
, unsigned long index
, xa_mark_t mark
)
1917 XA_STATE(xas
, xa
, index
);
1918 void *entry
= xas_load(&xas
);
1921 xas_clear_mark(&xas
, mark
);
1923 EXPORT_SYMBOL(__xa_clear_mark
);
1926 * xa_get_mark() - Inquire whether this mark is set on this entry.
1928 * @index: Index of entry.
1929 * @mark: Mark number.
1931 * This function uses the RCU read lock, so the result may be out of date
1932 * by the time it returns. If you need the result to be stable, use a lock.
1934 * Context: Any context. Takes and releases the RCU lock.
1935 * Return: True if the entry at @index has this mark set, false if it doesn't.
1937 bool xa_get_mark(struct xarray
*xa
, unsigned long index
, xa_mark_t mark
)
1939 XA_STATE(xas
, xa
, index
);
1943 entry
= xas_start(&xas
);
1944 while (xas_get_mark(&xas
, mark
)) {
1945 if (!xa_is_node(entry
))
1947 entry
= xas_descend(&xas
, xa_to_node(entry
));
1955 EXPORT_SYMBOL(xa_get_mark
);
1958 * xa_set_mark() - Set this mark on this entry.
1960 * @index: Index of entry.
1961 * @mark: Mark number.
1963 * Attempting to set a mark on a %NULL entry does not succeed.
1965 * Context: Process context. Takes and releases the xa_lock.
1967 void xa_set_mark(struct xarray
*xa
, unsigned long index
, xa_mark_t mark
)
1970 __xa_set_mark(xa
, index
, mark
);
1973 EXPORT_SYMBOL(xa_set_mark
);
1976 * xa_clear_mark() - Clear this mark on this entry.
1978 * @index: Index of entry.
1979 * @mark: Mark number.
1981 * Clearing a mark always succeeds.
1983 * Context: Process context. Takes and releases the xa_lock.
1985 void xa_clear_mark(struct xarray
*xa
, unsigned long index
, xa_mark_t mark
)
1988 __xa_clear_mark(xa
, index
, mark
);
1991 EXPORT_SYMBOL(xa_clear_mark
);
1994 * xa_find() - Search the XArray for an entry.
1996 * @indexp: Pointer to an index.
1997 * @max: Maximum index to search to.
1998 * @filter: Selection criterion.
2000 * Finds the entry in @xa which matches the @filter, and has the lowest
2001 * index that is at least @indexp and no more than @max.
2002 * If an entry is found, @indexp is updated to be the index of the entry.
2003 * This function is protected by the RCU read lock, so it may not find
2004 * entries which are being simultaneously added. It will not return an
2005 * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
2007 * Context: Any context. Takes and releases the RCU lock.
2008 * Return: The entry, if found, otherwise %NULL.
2010 void *xa_find(struct xarray
*xa
, unsigned long *indexp
,
2011 unsigned long max
, xa_mark_t filter
)
2013 XA_STATE(xas
, xa
, *indexp
);
2018 if ((__force
unsigned int)filter
< XA_MAX_MARKS
)
2019 entry
= xas_find_marked(&xas
, max
, filter
);
2021 entry
= xas_find(&xas
, max
);
2022 } while (xas_retry(&xas
, entry
));
2026 *indexp
= xas
.xa_index
;
2029 EXPORT_SYMBOL(xa_find
);
2031 static bool xas_sibling(struct xa_state
*xas
)
2033 struct xa_node
*node
= xas
->xa_node
;
2036 if (!IS_ENABLED(CONFIG_XARRAY_MULTI
) || !node
)
2038 mask
= (XA_CHUNK_SIZE
<< node
->shift
) - 1;
2039 return (xas
->xa_index
& mask
) >
2040 ((unsigned long)xas
->xa_offset
<< node
->shift
);
2044 * xa_find_after() - Search the XArray for a present entry.
2046 * @indexp: Pointer to an index.
2047 * @max: Maximum index to search to.
2048 * @filter: Selection criterion.
2050 * Finds the entry in @xa which matches the @filter and has the lowest
2051 * index that is above @indexp and no more than @max.
2052 * If an entry is found, @indexp is updated to be the index of the entry.
2053 * This function is protected by the RCU read lock, so it may miss entries
2054 * which are being simultaneously added. It will not return an
2055 * %XA_RETRY_ENTRY; if you need to see retry entries, use xas_find().
2057 * Context: Any context. Takes and releases the RCU lock.
2058 * Return: The pointer, if found, otherwise %NULL.
2060 void *xa_find_after(struct xarray
*xa
, unsigned long *indexp
,
2061 unsigned long max
, xa_mark_t filter
)
2063 XA_STATE(xas
, xa
, *indexp
+ 1);
2066 if (xas
.xa_index
== 0)
2071 if ((__force
unsigned int)filter
< XA_MAX_MARKS
)
2072 entry
= xas_find_marked(&xas
, max
, filter
);
2074 entry
= xas_find(&xas
, max
);
2076 if (xas_invalid(&xas
))
2078 if (xas_sibling(&xas
))
2080 if (!xas_retry(&xas
, entry
))
2086 *indexp
= xas
.xa_index
;
2089 EXPORT_SYMBOL(xa_find_after
);
2091 static unsigned int xas_extract_present(struct xa_state
*xas
, void **dst
,
2092 unsigned long max
, unsigned int n
)
2098 xas_for_each(xas
, entry
, max
) {
2099 if (xas_retry(xas
, entry
))
2110 static unsigned int xas_extract_marked(struct xa_state
*xas
, void **dst
,
2111 unsigned long max
, unsigned int n
, xa_mark_t mark
)
2117 xas_for_each_marked(xas
, entry
, max
, mark
) {
2118 if (xas_retry(xas
, entry
))
2130 * xa_extract() - Copy selected entries from the XArray into a normal array.
2131 * @xa: The source XArray to copy from.
2132 * @dst: The buffer to copy entries into.
2133 * @start: The first index in the XArray eligible to be selected.
2134 * @max: The last index in the XArray eligible to be selected.
2135 * @n: The maximum number of entries to copy.
2136 * @filter: Selection criterion.
2138 * Copies up to @n entries that match @filter from the XArray. The
2139 * copied entries will have indices between @start and @max, inclusive.
2141 * The @filter may be an XArray mark value, in which case entries which are
2142 * marked with that mark will be copied. It may also be %XA_PRESENT, in
2143 * which case all entries which are not %NULL will be copied.
2145 * The entries returned may not represent a snapshot of the XArray at a
2146 * moment in time. For example, if another thread stores to index 5, then
2147 * index 10, calling xa_extract() may return the old contents of index 5
2148 * and the new contents of index 10. Indices not modified while this
2149 * function is running will not be skipped.
2151 * If you need stronger guarantees, holding the xa_lock across calls to this
2152 * function will prevent concurrent modification.
2154 * Context: Any context. Takes and releases the RCU lock.
2155 * Return: The number of entries copied.
2157 unsigned int xa_extract(struct xarray
*xa
, void **dst
, unsigned long start
,
2158 unsigned long max
, unsigned int n
, xa_mark_t filter
)
2160 XA_STATE(xas
, xa
, start
);
2165 if ((__force
unsigned int)filter
< XA_MAX_MARKS
)
2166 return xas_extract_marked(&xas
, dst
, max
, n
, filter
);
2167 return xas_extract_present(&xas
, dst
, max
, n
);
2169 EXPORT_SYMBOL(xa_extract
);
2172 * xa_delete_node() - Private interface for workingset code.
2173 * @node: Node to be removed from the tree.
2174 * @update: Function to call to update ancestor nodes.
2176 * Context: xa_lock must be held on entry and will not be released.
2178 void xa_delete_node(struct xa_node
*node
, xa_update_node_t update
)
2180 struct xa_state xas
= {
2182 .xa_index
= (unsigned long)node
->offset
<<
2183 (node
->shift
+ XA_CHUNK_SHIFT
),
2184 .xa_shift
= node
->shift
+ XA_CHUNK_SHIFT
,
2185 .xa_offset
= node
->offset
,
2186 .xa_node
= xa_parent_locked(node
->array
, node
),
2187 .xa_update
= update
,
2190 xas_store(&xas
, NULL
);
2192 EXPORT_SYMBOL_GPL(xa_delete_node
); /* For the benefit of the test suite */
2195 * xa_destroy() - Free all internal data structures.
2198 * After calling this function, the XArray is empty and has freed all memory
2199 * allocated for its internal data structures. You are responsible for
2200 * freeing the objects referenced by the XArray.
2202 * Context: Any context. Takes and releases the xa_lock, interrupt-safe.
2204 void xa_destroy(struct xarray
*xa
)
2206 XA_STATE(xas
, xa
, 0);
2207 unsigned long flags
;
2211 xas_lock_irqsave(&xas
, flags
);
2212 entry
= xa_head_locked(xa
);
2213 RCU_INIT_POINTER(xa
->xa_head
, NULL
);
2214 xas_init_marks(&xas
);
2215 if (xa_zero_busy(xa
))
2216 xa_mark_clear(xa
, XA_FREE_MARK
);
2217 /* lockdep checks we're still holding the lock in xas_free_nodes() */
2218 if (xa_is_node(entry
))
2219 xas_free_nodes(&xas
, xa_to_node(entry
));
2220 xas_unlock_irqrestore(&xas
, flags
);
2222 EXPORT_SYMBOL(xa_destroy
);
2225 void xa_dump_node(const struct xa_node
*node
)
2231 if ((unsigned long)node
& 3) {
2232 pr_cont("node %px\n", node
);
2236 pr_cont("node %px %s %d parent %px shift %d count %d values %d "
2237 "array %px list %px %px marks",
2238 node
, node
->parent
? "offset" : "max", node
->offset
,
2239 node
->parent
, node
->shift
, node
->count
, node
->nr_values
,
2240 node
->array
, node
->private_list
.prev
, node
->private_list
.next
);
2241 for (i
= 0; i
< XA_MAX_MARKS
; i
++)
2242 for (j
= 0; j
< XA_MARK_LONGS
; j
++)
2243 pr_cont(" %lx", node
->marks
[i
][j
]);
2247 void xa_dump_index(unsigned long index
, unsigned int shift
)
2250 pr_info("%lu: ", index
);
2251 else if (shift
>= BITS_PER_LONG
)
2252 pr_info("0-%lu: ", ~0UL);
2254 pr_info("%lu-%lu: ", index
, index
| ((1UL << shift
) - 1));
2257 void xa_dump_entry(const void *entry
, unsigned long index
, unsigned long shift
)
2262 xa_dump_index(index
, shift
);
2264 if (xa_is_node(entry
)) {
2266 pr_cont("%px\n", entry
);
2269 struct xa_node
*node
= xa_to_node(entry
);
2271 for (i
= 0; i
< XA_CHUNK_SIZE
; i
++)
2272 xa_dump_entry(node
->slots
[i
],
2273 index
+ (i
<< node
->shift
), node
->shift
);
2275 } else if (xa_is_value(entry
))
2276 pr_cont("value %ld (0x%lx) [%px]\n", xa_to_value(entry
),
2277 xa_to_value(entry
), entry
);
2278 else if (!xa_is_internal(entry
))
2279 pr_cont("%px\n", entry
);
2280 else if (xa_is_retry(entry
))
2281 pr_cont("retry (%ld)\n", xa_to_internal(entry
));
2282 else if (xa_is_sibling(entry
))
2283 pr_cont("sibling (slot %ld)\n", xa_to_sibling(entry
));
2284 else if (xa_is_zero(entry
))
2285 pr_cont("zero (%ld)\n", xa_to_internal(entry
));
2287 pr_cont("UNKNOWN ENTRY (%px)\n", entry
);
2290 void xa_dump(const struct xarray
*xa
)
2292 void *entry
= xa
->xa_head
;
2293 unsigned int shift
= 0;
2295 pr_info("xarray: %px head %px flags %x marks %d %d %d\n", xa
, entry
,
2296 xa
->xa_flags
, xa_marked(xa
, XA_MARK_0
),
2297 xa_marked(xa
, XA_MARK_1
), xa_marked(xa
, XA_MARK_2
));
2298 if (xa_is_node(entry
))
2299 shift
= xa_to_node(entry
)->shift
+ XA_CHUNK_SHIFT
;
2300 xa_dump_entry(entry
, 0, shift
);