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git.proxmox.com Git - mirror_ubuntu-eoan-kernel.git/blob - include/linux/radix-tree.h
2 * Copyright (C) 2001 Momchil Velikov
3 * Portions Copyright (C) 2001 Christoph Hellwig
4 * Copyright (C) 2006 Nick Piggin
5 * Copyright (C) 2012 Konstantin Khlebnikov
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License as
9 * published by the Free Software Foundation; either version 2, or (at
10 * your option) any later version.
12 * This program is distributed in the hope that it will be useful, but
13 * WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
21 #ifndef _LINUX_RADIX_TREE_H
22 #define _LINUX_RADIX_TREE_H
24 #include <linux/bitops.h>
25 #include <linux/kernel.h>
26 #include <linux/list.h>
27 #include <linux/preempt.h>
28 #include <linux/rcupdate.h>
29 #include <linux/spinlock.h>
30 #include <linux/types.h>
31 #include <linux/xarray.h>
33 /* Keep unconverted code working */
34 #define radix_tree_root xarray
35 #define radix_tree_node xa_node
38 * The bottom two bits of the slot determine how the remaining bits in the
39 * slot are interpreted:
45 * The internal entry may be a pointer to the next level in the tree, a
46 * sibling entry, or an indicator that the entry in this slot has been moved
47 * to another location in the tree and the lookup should be restarted. While
48 * NULL fits the 'data pointer' pattern, it means that there is no entry in
49 * the tree for this index (no matter what level of the tree it is found at).
50 * This means that storing a NULL entry in the tree is the same as deleting
51 * the entry from the tree.
53 #define RADIX_TREE_ENTRY_MASK 3UL
54 #define RADIX_TREE_INTERNAL_NODE 2UL
56 static inline bool radix_tree_is_internal_node(void *ptr
)
58 return ((unsigned long)ptr
& RADIX_TREE_ENTRY_MASK
) ==
59 RADIX_TREE_INTERNAL_NODE
;
62 /*** radix-tree API starts here ***/
64 #define RADIX_TREE_MAP_SHIFT XA_CHUNK_SHIFT
65 #define RADIX_TREE_MAP_SIZE (1UL << RADIX_TREE_MAP_SHIFT)
66 #define RADIX_TREE_MAP_MASK (RADIX_TREE_MAP_SIZE-1)
68 #define RADIX_TREE_MAX_TAGS XA_MAX_MARKS
69 #define RADIX_TREE_TAG_LONGS XA_MARK_LONGS
71 #define RADIX_TREE_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(unsigned long))
72 #define RADIX_TREE_MAX_PATH (DIV_ROUND_UP(RADIX_TREE_INDEX_BITS, \
73 RADIX_TREE_MAP_SHIFT))
75 /* The IDR tag is stored in the low bits of xa_flags */
76 #define ROOT_IS_IDR ((__force gfp_t)4)
77 /* The top bits of xa_flags are used to store the root tags */
78 #define ROOT_TAG_SHIFT (__GFP_BITS_SHIFT)
80 #define RADIX_TREE_INIT(name, mask) XARRAY_INIT(name, mask)
82 #define RADIX_TREE(name, mask) \
83 struct radix_tree_root name = RADIX_TREE_INIT(name, mask)
85 #define INIT_RADIX_TREE(root, mask) xa_init_flags(root, mask)
87 static inline bool radix_tree_empty(const struct radix_tree_root
*root
)
89 return root
->xa_head
== NULL
;
93 * struct radix_tree_iter - radix tree iterator state
95 * @index: index of current slot
96 * @next_index: one beyond the last index for this chunk
97 * @tags: bit-mask for tag-iterating
98 * @node: node that contains current slot
100 * This radix tree iterator works in terms of "chunks" of slots. A chunk is a
101 * subinterval of slots contained within one radix tree leaf node. It is
102 * described by a pointer to its first slot and a struct radix_tree_iter
103 * which holds the chunk's position in the tree and its size. For tagged
104 * iteration radix_tree_iter also holds the slots' bit-mask for one chosen
107 struct radix_tree_iter
{
109 unsigned long next_index
;
111 struct radix_tree_node
*node
;
115 * Radix-tree synchronization
117 * The radix-tree API requires that users provide all synchronisation (with
118 * specific exceptions, noted below).
120 * Synchronization of access to the data items being stored in the tree, and
121 * management of their lifetimes must be completely managed by API users.
123 * For API usage, in general,
124 * - any function _modifying_ the tree or tags (inserting or deleting
125 * items, setting or clearing tags) must exclude other modifications, and
126 * exclude any functions reading the tree.
127 * - any function _reading_ the tree or tags (looking up items or tags,
128 * gang lookups) must exclude modifications to the tree, but may occur
129 * concurrently with other readers.
131 * The notable exceptions to this rule are the following functions:
132 * __radix_tree_lookup
134 * radix_tree_lookup_slot
136 * radix_tree_gang_lookup
137 * radix_tree_gang_lookup_tag
138 * radix_tree_gang_lookup_tag_slot
141 * The first 7 functions are able to be called locklessly, using RCU. The
142 * caller must ensure calls to these functions are made within rcu_read_lock()
143 * regions. Other readers (lock-free or otherwise) and modifications may be
144 * running concurrently.
146 * It is still required that the caller manage the synchronization and lifetimes
147 * of the items. So if RCU lock-free lookups are used, typically this would mean
148 * that the items have their own locks, or are amenable to lock-free access; and
149 * that the items are freed by RCU (or only freed after having been deleted from
150 * the radix tree *and* a synchronize_rcu() grace period).
152 * (Note, rcu_assign_pointer and rcu_dereference are not needed to control
153 * access to data items when inserting into or looking up from the radix tree)
155 * Note that the value returned by radix_tree_tag_get() may not be relied upon
156 * if only the RCU read lock is held. Functions to set/clear tags and to
157 * delete nodes running concurrently with it may affect its result such that
158 * two consecutive reads in the same locked section may return different
159 * values. If reliability is required, modification functions must also be
160 * excluded from concurrency.
162 * radix_tree_tagged is able to be called without locking or RCU.
166 * radix_tree_deref_slot - dereference a slot
167 * @slot: slot pointer, returned by radix_tree_lookup_slot
169 * For use with radix_tree_lookup_slot(). Caller must hold tree at least read
170 * locked across slot lookup and dereference. Not required if write lock is
171 * held (ie. items cannot be concurrently inserted).
173 * radix_tree_deref_retry must be used to confirm validity of the pointer if
174 * only the read lock is held.
176 * Return: entry stored in that slot.
178 static inline void *radix_tree_deref_slot(void __rcu
**slot
)
180 return rcu_dereference(*slot
);
184 * radix_tree_deref_slot_protected - dereference a slot with tree lock held
185 * @slot: slot pointer, returned by radix_tree_lookup_slot
187 * Similar to radix_tree_deref_slot. The caller does not hold the RCU read
188 * lock but it must hold the tree lock to prevent parallel updates.
190 * Return: entry stored in that slot.
192 static inline void *radix_tree_deref_slot_protected(void __rcu
**slot
,
193 spinlock_t
*treelock
)
195 return rcu_dereference_protected(*slot
, lockdep_is_held(treelock
));
199 * radix_tree_deref_retry - check radix_tree_deref_slot
200 * @arg: pointer returned by radix_tree_deref_slot
201 * Returns: 0 if retry is not required, otherwise retry is required
203 * radix_tree_deref_retry must be used with radix_tree_deref_slot.
205 static inline int radix_tree_deref_retry(void *arg
)
207 return unlikely(radix_tree_is_internal_node(arg
));
211 * radix_tree_exception - radix_tree_deref_slot returned either exception?
212 * @arg: value returned by radix_tree_deref_slot
213 * Returns: 0 if well-aligned pointer, non-0 if either kind of exception.
215 static inline int radix_tree_exception(void *arg
)
217 return unlikely((unsigned long)arg
& RADIX_TREE_ENTRY_MASK
);
220 int radix_tree_insert(struct radix_tree_root
*, unsigned long index
,
222 void *__radix_tree_lookup(const struct radix_tree_root
*, unsigned long index
,
223 struct radix_tree_node
**nodep
, void __rcu
***slotp
);
224 void *radix_tree_lookup(const struct radix_tree_root
*, unsigned long);
225 void __rcu
**radix_tree_lookup_slot(const struct radix_tree_root
*,
226 unsigned long index
);
227 void __radix_tree_replace(struct radix_tree_root
*, struct radix_tree_node
*,
228 void __rcu
**slot
, void *entry
);
229 void radix_tree_iter_replace(struct radix_tree_root
*,
230 const struct radix_tree_iter
*, void __rcu
**slot
, void *entry
);
231 void radix_tree_replace_slot(struct radix_tree_root
*,
232 void __rcu
**slot
, void *entry
);
233 void radix_tree_iter_delete(struct radix_tree_root
*,
234 struct radix_tree_iter
*iter
, void __rcu
**slot
);
235 void *radix_tree_delete_item(struct radix_tree_root
*, unsigned long, void *);
236 void *radix_tree_delete(struct radix_tree_root
*, unsigned long);
237 unsigned int radix_tree_gang_lookup(const struct radix_tree_root
*,
238 void **results
, unsigned long first_index
,
239 unsigned int max_items
);
240 int radix_tree_preload(gfp_t gfp_mask
);
241 int radix_tree_maybe_preload(gfp_t gfp_mask
);
242 void radix_tree_init(void);
243 void *radix_tree_tag_set(struct radix_tree_root
*,
244 unsigned long index
, unsigned int tag
);
245 void *radix_tree_tag_clear(struct radix_tree_root
*,
246 unsigned long index
, unsigned int tag
);
247 int radix_tree_tag_get(const struct radix_tree_root
*,
248 unsigned long index
, unsigned int tag
);
249 void radix_tree_iter_tag_clear(struct radix_tree_root
*,
250 const struct radix_tree_iter
*iter
, unsigned int tag
);
251 unsigned int radix_tree_gang_lookup_tag(const struct radix_tree_root
*,
252 void **results
, unsigned long first_index
,
253 unsigned int max_items
, unsigned int tag
);
254 unsigned int radix_tree_gang_lookup_tag_slot(const struct radix_tree_root
*,
255 void __rcu
***results
, unsigned long first_index
,
256 unsigned int max_items
, unsigned int tag
);
257 int radix_tree_tagged(const struct radix_tree_root
*, unsigned int tag
);
259 static inline void radix_tree_preload_end(void)
264 void __rcu
**idr_get_free(struct radix_tree_root
*root
,
265 struct radix_tree_iter
*iter
, gfp_t gfp
,
269 RADIX_TREE_ITER_TAG_MASK
= 0x0f, /* tag index in lower nybble */
270 RADIX_TREE_ITER_TAGGED
= 0x10, /* lookup tagged slots */
271 RADIX_TREE_ITER_CONTIG
= 0x20, /* stop at first hole */
275 * radix_tree_iter_init - initialize radix tree iterator
277 * @iter: pointer to iterator state
278 * @start: iteration starting index
281 static __always_inline
void __rcu
**
282 radix_tree_iter_init(struct radix_tree_iter
*iter
, unsigned long start
)
285 * Leave iter->tags uninitialized. radix_tree_next_chunk() will fill it
286 * in the case of a successful tagged chunk lookup. If the lookup was
287 * unsuccessful or non-tagged then nobody cares about ->tags.
289 * Set index to zero to bypass next_index overflow protection.
290 * See the comment in radix_tree_next_chunk() for details.
293 iter
->next_index
= start
;
298 * radix_tree_next_chunk - find next chunk of slots for iteration
300 * @root: radix tree root
301 * @iter: iterator state
302 * @flags: RADIX_TREE_ITER_* flags and tag index
303 * Returns: pointer to chunk first slot, or NULL if there no more left
305 * This function looks up the next chunk in the radix tree starting from
306 * @iter->next_index. It returns a pointer to the chunk's first slot.
307 * Also it fills @iter with data about chunk: position in the tree (index),
308 * its end (next_index), and constructs a bit mask for tagged iterating (tags).
310 void __rcu
**radix_tree_next_chunk(const struct radix_tree_root
*,
311 struct radix_tree_iter
*iter
, unsigned flags
);
314 * radix_tree_iter_lookup - look up an index in the radix tree
315 * @root: radix tree root
316 * @iter: iterator state
317 * @index: key to look up
319 * If @index is present in the radix tree, this function returns the slot
320 * containing it and updates @iter to describe the entry. If @index is not
321 * present, it returns NULL.
323 static inline void __rcu
**
324 radix_tree_iter_lookup(const struct radix_tree_root
*root
,
325 struct radix_tree_iter
*iter
, unsigned long index
)
327 radix_tree_iter_init(iter
, index
);
328 return radix_tree_next_chunk(root
, iter
, RADIX_TREE_ITER_CONTIG
);
332 * radix_tree_iter_find - find a present entry
333 * @root: radix tree root
334 * @iter: iterator state
335 * @index: start location
337 * This function returns the slot containing the entry with the lowest index
338 * which is at least @index. If @index is larger than any present entry, this
339 * function returns NULL. The @iter is updated to describe the entry found.
341 static inline void __rcu
**
342 radix_tree_iter_find(const struct radix_tree_root
*root
,
343 struct radix_tree_iter
*iter
, unsigned long index
)
345 radix_tree_iter_init(iter
, index
);
346 return radix_tree_next_chunk(root
, iter
, 0);
350 * radix_tree_iter_retry - retry this chunk of the iteration
351 * @iter: iterator state
353 * If we iterate over a tree protected only by the RCU lock, a race
354 * against deletion or creation may result in seeing a slot for which
355 * radix_tree_deref_retry() returns true. If so, call this function
356 * and continue the iteration.
358 static inline __must_check
359 void __rcu
**radix_tree_iter_retry(struct radix_tree_iter
*iter
)
361 iter
->next_index
= iter
->index
;
366 static inline unsigned long
367 __radix_tree_iter_add(struct radix_tree_iter
*iter
, unsigned long slots
)
369 return iter
->index
+ slots
;
373 * radix_tree_iter_resume - resume iterating when the chunk may be invalid
374 * @slot: pointer to current slot
375 * @iter: iterator state
376 * Returns: New slot pointer
378 * If the iterator needs to release then reacquire a lock, the chunk may
379 * have been invalidated by an insertion or deletion. Call this function
380 * before releasing the lock to continue the iteration from the next index.
382 void __rcu
**__must_check
radix_tree_iter_resume(void __rcu
**slot
,
383 struct radix_tree_iter
*iter
);
386 * radix_tree_chunk_size - get current chunk size
388 * @iter: pointer to radix tree iterator
389 * Returns: current chunk size
391 static __always_inline
long
392 radix_tree_chunk_size(struct radix_tree_iter
*iter
)
394 return iter
->next_index
- iter
->index
;
398 * radix_tree_next_slot - find next slot in chunk
400 * @slot: pointer to current slot
401 * @iter: pointer to interator state
402 * @flags: RADIX_TREE_ITER_*, should be constant
403 * Returns: pointer to next slot, or NULL if there no more left
405 * This function updates @iter->index in the case of a successful lookup.
406 * For tagged lookup it also eats @iter->tags.
408 * There are several cases where 'slot' can be passed in as NULL to this
409 * function. These cases result from the use of radix_tree_iter_resume() or
410 * radix_tree_iter_retry(). In these cases we don't end up dereferencing
411 * 'slot' because either:
412 * a) we are doing tagged iteration and iter->tags has been set to 0, or
413 * b) we are doing non-tagged iteration, and iter->index and iter->next_index
414 * have been set up so that radix_tree_chunk_size() returns 1 or 0.
416 static __always_inline
void __rcu
**radix_tree_next_slot(void __rcu
**slot
,
417 struct radix_tree_iter
*iter
, unsigned flags
)
419 if (flags
& RADIX_TREE_ITER_TAGGED
) {
421 if (unlikely(!iter
->tags
))
423 if (likely(iter
->tags
& 1ul)) {
424 iter
->index
= __radix_tree_iter_add(iter
, 1);
428 if (!(flags
& RADIX_TREE_ITER_CONTIG
)) {
429 unsigned offset
= __ffs(iter
->tags
);
431 iter
->tags
>>= offset
++;
432 iter
->index
= __radix_tree_iter_add(iter
, offset
);
437 long count
= radix_tree_chunk_size(iter
);
439 while (--count
> 0) {
441 iter
->index
= __radix_tree_iter_add(iter
, 1);
445 if (flags
& RADIX_TREE_ITER_CONTIG
) {
446 /* forbid switching to the next chunk */
447 iter
->next_index
= 0;
459 * radix_tree_for_each_slot - iterate over non-empty slots
461 * @slot: the void** variable for pointer to slot
462 * @root: the struct radix_tree_root pointer
463 * @iter: the struct radix_tree_iter pointer
464 * @start: iteration starting index
466 * @slot points to radix tree slot, @iter->index contains its index.
468 #define radix_tree_for_each_slot(slot, root, iter, start) \
469 for (slot = radix_tree_iter_init(iter, start) ; \
470 slot || (slot = radix_tree_next_chunk(root, iter, 0)) ; \
471 slot = radix_tree_next_slot(slot, iter, 0))
474 * radix_tree_for_each_tagged - iterate over tagged slots
476 * @slot: the void** variable for pointer to slot
477 * @root: the struct radix_tree_root pointer
478 * @iter: the struct radix_tree_iter pointer
479 * @start: iteration starting index
482 * @slot points to radix tree slot, @iter->index contains its index.
484 #define radix_tree_for_each_tagged(slot, root, iter, start, tag) \
485 for (slot = radix_tree_iter_init(iter, start) ; \
486 slot || (slot = radix_tree_next_chunk(root, iter, \
487 RADIX_TREE_ITER_TAGGED | tag)) ; \
488 slot = radix_tree_next_slot(slot, iter, \
489 RADIX_TREE_ITER_TAGGED | tag))
491 #endif /* _LINUX_RADIX_TREE_H */